- Associate Research Professor, Medicine
- Evaluation of the therapeutic potential of eNAMPT monoclonal antibodies (mAbs) in preclinical models of acute lung injury and ARDS.
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- Tumurkhuu, G., Casanova, N. G., Kempf, C. L., Ercan Laguna, D., Camp, S. M., Dagvadorj, J., Song, J. H., Reyes Hernon, V., Travelli, C., Montano, E. N., Yu, J. M., Ishimori, M., Wallace, D. J., Sammani, S., Jefferies, C., & Garcia, J. G. (2023). eNAMPT/TLR4 inflammatory cascade activation is a key contributor to SLE Lung vasculitis and alveolar hemorrhage. Journal of translational autoimmunity, 6, 100181.More infoEffective therapies to reduce the severity and high mortality of pulmonary vasculitis and diffuse alveolar hemorrhage (DAH) in patients with systemic lupus erythematosus (SLE) is a serious unmet need. We explored whether biologic neutralization of eNAMPT (extracellular nicotinamide phosphoribosyl-transferase), a novel DAMP and Toll-like receptor 4 ligand, represents a viable therapeutic strategy in lupus vasculitis.
- Bermudez, T., Sammani, S., Song, J. H., Hernon, V. R., Kempf, C. L., Garcia, A. N., Burt, J., Hufford, M., Camp, S. M., Cress, A. E., Desai, A. A., Natarajan, V., Jacobson, J. R., Dudek, S. M., Cancio, L. C., Alvarez, J., Rafikov, R., Li, Y., Zhang, D. D., , Casanova, N. G., et al. (2022). eNAMPT neutralization reduces preclinical ARDS severity via rectified NFkB and Akt/mTORC2 signaling. Scientific reports, 12(1), 696.More infoDespite encouraging preclinical data, therapies to reduce ARDS mortality remains a globally unmet need, including during the COVID-19 pandemic. We previously identified extracellular nicotinamide phosphoribosyltransferase (eNAMPT) as a novel damage-associated molecular pattern protein (DAMP) via TLR4 ligation which regulates inflammatory cascade activation. eNAMPT is tightly linked to human ARDS by biomarker and genotyping studies in ARDS subjects. We now hypothesize that an eNAMPT-neutralizing mAb will significantly reduce the severity of ARDS lung inflammatory lung injury in diverse preclinical rat and porcine models. Sprague Dawley rats received eNAMPT mAb intravenously following exposure to intratracheal lipopolysaccharide (LPS) or to a traumatic blast (125 kPa) but prior to initiation of ventilator-induced lung injury (VILI) (4 h). Yucatan minipigs received intravenous eNAMPT mAb 2 h after initiation of septic shock and VILI (12 h). Each rat/porcine ARDS/VILI model was strongly associated with evidence of severe inflammatory lung injury with NFkB pathway activation and marked dysregulation of the Akt/mTORC2 signaling pathway. eNAMPT neutralization dramatically reduced inflammatory indices and the severity of lung injury in each rat/porcine ARDS/VILI model (~ 50% reduction) including reduction in serum lactate, and plasma levels of eNAMPT, IL-6, TNFα and Ang-2. The eNAMPT mAb further rectified NFkB pathway activation and preserved the Akt/mTORC2 signaling pathway. These results strongly support targeting the eNAMPT/TLR4 inflammatory pathway as a potential ARDS strategy to reduce inflammatory lung injury and ARDS mortality.
- Casanova, N. G., Reyes-Hernon, V., Gregory, T., Sun, B., Bermudez, T., Hufford, M. K., Oita, R. C., Camp, S. M., Hernandez-Molina, G., Serrano, J. R., Sun, X., Fimbres, J., Mirsaeidi, M., Sammani, S., Bime, C., & Garcia, J. G. (2022). Biochemical and genomic identification of novel biomarkers in progressive sarcoidosis: HBEGF, eNAMPT, and ANG-2. Frontiers in medicine, 9, 1012827.More infoProgressive pulmonary fibrosis is a serious complication in subjects with sarcoidosis. The absence of reliable, non-invasive biomarkers that detect early progression exacerbates the difficulty in predicting sarcoidosis severity. To potentially address this unmet need, we evaluated a panel of markers for an association with sarcoidosis progression (HBEGF, NAMPT, IL1-RA, IL-6, IL-8, ANG-2). This panel encompasses proteins related to inflammation, vascular injury, cell proliferation, and fibroblast mitogenesis processes.
- Garcia, A. N., Casanova, N. G., Kempf, C. L., Bermudez, T., Valera, D. G., Song, J. H., Sun, X., Cai, H., Moreno-Vinasco, L., Gregory, T., Oita, R. C., Hernon, V. R., Camp, S. M., Rogers, C., Kyubwa, E. M., Menon, N., Axtelle, J., Rappaport, J., Bime, C., , Sammani, S., et al. (2022). eNAMPT Is a Novel Damage-associated Molecular Pattern Protein That Contributes to the Severity of Radiation-induced Lung Fibrosis. American journal of respiratory cell and molecular biology, 66(5), 497-509.More infoThe paucity of therapeutic strategies to reduce the severity of radiation-induced lung fibrosis (RILF), a life-threatening complication of intended or accidental ionizing radiation exposure, is a serious unmet need. We evaluated the contribution of eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a damage-associated molecular pattern (DAMP) protein and TLR4 (Toll-like receptor 4) ligand, to the severity of whole-thorax lung irradiation (WTLI)-induced RILF. Wild-type (WT) and heterozygous C57BL6 mice and nonhuman primates (NHPs, ) were exposed to a single WTLI dose (9.8 or 10.7 Gy for NHPs, 20 Gy for mice). WT mice received IgG (control) or an eNAMPT-neutralizing polyclonal or monoclonal antibody (mAb) intraperitoneally 4 hours after WTLI and weekly thereafter. At 8-12 weeks after WTLI, NAMPT expression was assessed by immunohistochemistry, biochemistry, and plasma biomarker studies. RILF severity was determined by BAL protein/cells, hematoxylin and eosin, and trichrome blue staining and soluble collagen assays. RNA sequencing and bioinformatic analyses identified differentially expressed lung tissue genes/pathways. NAMPT lung tissue expression was increased in both WTLI-exposed WT mice and NHPs. mice and eNAMPT polyclonal antibody/mAb-treated mice exhibited significantly attenuated WTLI-mediated lung fibrosis with reduced: ) NAMPT and trichrome blue staining; ) dysregulated lung tissue expression of smooth muscle actin, p-SMAD2/p-SMAD1/5/9, TGF-β, TSP1 (thrombospondin-1), NOX4, IL-1β, and NRF2; ) plasma eNAMPT and IL-1β concentrations; and ) soluble collagen. Multiple WTLI-induced dysregulated differentially expressed lung tissue genes/pathways with known tissue fibrosis involvement were each rectified in mice receiving eNAMPT mAbs.The eNAMPT/TLR4 inflammatory network is essentially involved in radiation pathobiology, with eNAMPT neutralization an effective therapeutic strategy to reduce RILF severity.
- Garcia, A. N., Casanova, N. G., Valera, D. G., Sun, X., Song, J. H., Kempf, C. L., Moreno-Vinasco, L., Burns, K., Bermudez, T., Valdez, M., Cuellar, G., Gregory, T., Oita, R. C., Hernon, V. R., Barber, C., Camp, S. M., Martin, D., Liu, Z., Bime, C., , Sammani, S., et al. (2022). Involvement of eNAMPT/TLR4 signaling in murine radiation pneumonitis: protection by eNAMPT neutralization. Translational research : the journal of laboratory and clinical medicine, 239, 44-57.More infoTherapeutic strategies to prevent or reduce the severity of radiation pneumonitis are a serious unmet need. We evaluated extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a damage-associated molecular pattern protein (DAMP) and Toll-Like Receptor 4 (TLR4) ligand, as a therapeutic target in murine radiation pneumonitis. Radiation-induced murine and human NAMPT expression was assessed in vitro, in tissues (IHC, biochemistry, imaging), and in plasma. Wild type C57Bl6 mice (WT) and Nampt heterozygous mice were exposed to 20Gy whole thoracic lung irradiation (WTLI) with or without weekly IP injection of IgG (control) or an eNAMPT-neutralizing polyclonal (pAb) or monoclonal antibody (mAb). BAL protein/cells and H&E staining were used to generate a WTLI severity score. Differentially-expressed genes (DEGs)/pathways were identified by RNA sequencing and bioinformatic analyses. Radiation exposure increases in vitro NAMPT expression in lung epithelium (NAMPT promoter activity) and NAMPT lung tissue expression in WTLI-exposed mice. Nampt mice and eNAMPT pAb/mAb-treated mice exhibited significant histologic attenuation of WTLI-mediated lung injury with reduced levels of BAL protein and cells, and plasma levels of eNAMPT, IL-6, and IL-1β. Genomic and biochemical studies from WTLI-exposed lung tissues highlighted dysregulation of NFkB/cytokine and MAP kinase signaling pathways which were rectified by eNAMPT mAb treatment. The eNAMPT/TLR4 pathway is essentially involved in radiation pathobiology with eNAMPT neutralization an effective therapeutic strategy to reduce the severity of radiation pneumonitis.
- Kempf, C. L., Sammani, S., Bermudez, T., Song, J. H., Hernon, V. R., Hufford, M. K., Burt, J., Camp, S. M., Dudek, S. M., & Garcia, J. G. (2022). Critical role for the lung endothelial nonmuscle myosin light-chain kinase isoform in the severity of inflammatory murine lung injury. Pulmonary circulation, 12(2), e12061.More infoGlobal knockout of the nonmuscle isoform of myosin light-chain kinase (nmMLCK), a primary cellular regulator of cytoskeletal machinery, is strongly protective in preclinical murine models of inflammatory lung injury. The current study was designed to assess the specific contribution of endothelial cell (EC) nmMLCK to the severity of murine inflammatory lung injury produced by lipopolysaccharide (LPS) and mechanical ventilation ventilator-induced lung injury or ventilation (VILI). Responses to combined LPS/VILI exposure were assessed in: (i) wild-type (WT) C57BL/6J mice; (ii) transgenic mice with global deletion of nmMLCK ( ); (iii) transgenic nm mice with overexpression of nmMLCK restricted to the endothelium ( ). Lung inflammation indices included lung histology, bronchoalveolar lavage (BAL) polymorphonuclear leukocytes (PMNs), lung protein biochemistry, tissue albumin levels, Evans blue dye (EBD) lung extravasation, and plasma cytokines (interleukin-6 [IL-6], keratinocyte chemoattractant [KC]/IL-8, IL-1bβ, extracellular nicotinamide phosphoribosyltransferase, tumor necrosis factor-α). Compared to WT C57BL/6J mice, the severity of LPS/VILI-induced lung injury was markedly reduced in mice with global nmMLCK deletion reflected by reductions in histologic inflammatory lung injury, BAL PMN counts, mitogen-activated protein kinase, and NF-kB pathway activation in lung homogenates, plasma cytokine levels, and parameters of lung permeability (increased BAL protein, tissue albumin levels, EBD lung extravasation). In contrast, mice with restricted overexpression of nmMLCK in EC ( ) showed significant persistence of LPS/VILI-induced lung injury severity compared to WT mice. In conclusion, these studies strongly endorse the role of EC nmMLCK in driving the severity of preclinical inflammatory lung injury. Precise targeting of EC nmMLCK may represent an attractive therapeutic strategy to reduce lung inflammation and both lung and systemic vascular permeability.
- Sammani, S., Bermudez, T., Kempf, C. L., Song, J. H., Fleming, J. C., Reyes Hernon, V., Hufford, M., Tang, L., Cai, H., Camp, S. M., Natarajan, V., Jacobson, J. R., Dudek, S. M., Martin, D. R., Karmonik, C., Sun, X., Sun, B., Casanova, N. G., Bime, C., & Garcia, J. G. (2022). eNAMPT Neutralization Preserves Lung Fluid Balance and Reduces Acute Renal Injury in Porcine Sepsis/VILI-Induced Inflammatory Lung Injury. Frontiers in physiology, 13, 916159.More infoNumerous potential ARDS therapeutics, based upon preclinical successful rodent studies that utilized LPS challenge without mechanical ventilation, have failed in Phase 2/3 clinical trials. Recently, ALT-100 mAb, a novel biologic that neutralizes the TLR4 ligand and DAMP, eNAMPT (extracellular nicotinamide phosphoribosyltransferase), was shown to reduce septic shock/VILI-induced porcine lung injury when delivered 2 h after injury onset. We now examine the ALT-100 mAb efficacy on acute kidney injury (AKI) and lung fluid balance in a porcine ARDS/VILI model when delivered 6 h post injury. Compared to control PBS-treated pigs, exposure of ALT-100 mAb-treated pigs (0.4 mg/kg, 2 h or 6 h after injury initiation) to LPS-induced pneumonia/septic shock and VILI (12 h), demonstrated significantly diminished lung injury severity (histology, BAL PMNs, plasma cytokines), biochemical/genomic evidence of NF-kB/MAP kinase/cytokine receptor signaling, and AKI (histology, plasma lipocalin). ALT-100 mAb treatment effectively preserved lung fluid balance reflected by reduced BAL protein/tissue albumin levels, lung wet/dry tissue ratios, ultrasound-derived B lines, and chest radiograph opacities. Delayed ALT-100 mAb at 2 h was significantly more protective than 6 h delivery only for plasma eNAMPT while trending toward greater protection for remaining inflammatory indices. Delayed ALT-100 treatment also decreased lung/renal injury indices in LPS/VILI-exposed rats when delivered up to 12 h after LPS. These studies indicate the delayed delivery of the eNAMPT-neutralizing ALT-100 mAb reduces inflammatory lung injury, preserves lung fluid balance, and reduces multi-organ dysfunction, and may potentially address the unmet need for novel therapeutics that reduce ARDS/VILI mortality.
- Song, J. H., Mascarenhas, J. B., Sammani, S., Kempf, C. L., Cai, H., Camp, S. M., Bermudez, T., Zhang, D. D., Natarajan, V., & Garcia, J. G. (2022). TLR4 activation induces inflammatory vascular permeability via Dock1 targeting and NOX4 upregulation. Biochimica et biophysica acta. Molecular basis of disease, 1868(12), 166562.More infoThe loss of vascular integrity is a cardinal feature of acute inflammatory responses evoked by activation of the TLR4 inflammatory cascade. Utilizing in vitro and in vivo models of inflammatory lung injury, we explored TLR4-mediated dysregulated signaling that results in the loss of endothelial cell (EC) barrier integrity and vascular permeability, focusing on Dock1 and Elmo1 complexes that are intimately involved in regulation of Rac1 GTPase activity, a well recognized modulator of vascular integrity. Marked reductions in Dock1 and Elmo1 expression was observed in lung tissues (porcine, rat, mouse) exposed to TLR4 ligand-mediated acute inflammatory lung injury (LPS, eNAMPT) in combination with injurious mechanical ventilation. Lung tissue levels of Dock1 and Elmo1 were preserved in animals receiving an eNAMPT-neutralizing mAb in conjunction with highly significant decreases in alveolar edema and lung injury severity, consistent with Dock1/Elmo1 as pathologic TLR4 targets directly involved in inflammation-mediated loss of vascular barrier integrity. In vitro studies determined that pharmacologic inhibition of Dock1-mediated activation of Rac1 (TBOPP) significantly exacerbated TLR4 agonist-induced EC barrier dysfunction (LPS, eNAMPT) and attenuated increases in EC barrier integrity elicited by barrier-enhancing ligands of the S1P1 receptor (sphingosine-1-phosphate, Tysiponate). The EC barrier-disrupting influence of Dock1 inhibition on S1PR1 barrier regulation occurred in concert with: 1) suppressed formation of EC barrier-enhancing lamellipodia, 2) altered nmMLCK-mediated MLC2 phosphorylation, and 3) upregulation of NOX4 expression and increased ROS. These studies indicate that Dock1 is essential for maintaining EC junctional integrity and is a critical target in TLR4-mediated inflammatory lung injury.
- Zhao, F., Barber, C. J., Sammani, S., Wan, L., Miller, B. W., Furenlid, L. R., Li, Z., Gotur, D. B., Barrios, R., Woolfenden, J. M., Martin, D. R., & Liu, Z. (2022). Use of radiolabeled hyaluronic acid for preclinical assessment of inflammatory injury and acute respiratory distress syndrome. Nuclear medicine and biology, 114-115, 86-98.More infoAcute respiratory distress syndrome (ARDS) is accompanied by a dramatic increase in lung hyaluronic acid (HA), leading to a dose-dependent reduction of pulmonary oxygenation. This pattern is associated with severe infections, such as COVID-19, and other important lung injury etiologies. HA actively participates in molecular pathways involved in the cytokine storm of COVID-19-induced ARDS. The objective of this study was to evaluate an imaging approach of radiolabeled HA for assessment of dysregulated HA deposition in mouse models with skin inflammation and lipopolysaccharide (LPS)-induced ARDS using a novel portable intensified Quantum Imaging Detector (iQID) gamma camera system.
- Ahmed, M., Zaghloul, N., Zimmerman, P., Casanova, N. G., Sun, X., Song, J. H., Hernon, V. R., Sammani, S., Rischard, F., Rafikova, O., Rafikov, R., Makino, A., Kempf, C. L., Camp, S. M., Wang, J., Desai, A. A., Lussier, Y., Yuan, J. X., & Garcia, J. G. (2021). Endothelial eNAMPT drives EndMT and preclinical PH: rescue by an eNAMPT-neutralizing mAb. Pulmonary circulation, 11(4), 20458940211059712.More infoPharmacologic interventions to halt/reverse the vascular remodeling and right ventricular dysfunction in pulmonary arterial hypertension (PAH) remains an unmet need. We previously demonstrated extracellular nicotinamide phosphoribosyltransferase (eNAMPT) as a DAMP (damage-associated molecular pattern protein) contributing to PAH pathobiology via TLR4 ligation. We examined the role of endothelial cell (EC)-specific eNAMPT in experimental PH and an eNAMPT-neutralizing mAb as a therapeutic strategy to reverse established PH. Hemodynamic/echocardiographic measurements and tissue analyses were performed in Sprague Dawley rats exposed to 10% hypoxia/Sugen (three weeks) followed by return to normoxia and weekly intraperitoneal delivery of the eNAMPT mAb (1 mg/kg). WT C57BL/6J mice and conditional EC-cNAMPT mice were exposed to 10% hypoxia (three weeks). Biochemical and RNA sequencing studies were performed on rat PH lung tissues and human PAH PBMCs. Hypoxia/Sugen-exposed rats exhibited multiple indices of severe PH (right ventricular systolic pressure, Fulton index), including severe vascular remodeling, compared to control rats. PH severity indices and plasma levels of eNAMPT, IL-6, and TNF- were all significantly attenuated by eNAMPT mAb neutralization. Compared to hypoxia-exposed WT mice, cNAMPT KO mice exhibited significantly reduced PH severity and evidence of EC to mesenchymal transition (EndMT). Finally, biochemical and RNAseq analyses revealed eNAMPT mAb-mediated rectification of dysregulated inflammatory signaling pathways (TLR/NF-κB, MAP kinase, Akt/mTOR) and EndMT in rat PH lung tissues and human PAH PBMCs. These studies underscore EC-derived eNAMPT as a key contributor to PAH pathobiology and support the eNAMPT/TLR4 inflammatory pathway as a highly druggable therapeutic target to reduce PH severity and reverse PAH.
- Sammani, S. (2020). Direct Extracellular NAMPT Involvement in Pulmonary Hypertension and Vascular Remodeling. Transcriptional Regulation by SOX and HIF-2α. Am J Respir Cell Mol Biol.
- Sammani, S. (2020). Endothelial eNAMPT Amplifies Preclinical Acute Lung Injury: Efficacy of an eNAMPT-Neutralising mAb. Eur Respir J.
- Kempf, C., Zhou, T., Casanova, N., Batai, K., Sammani, S., Pouladi, N., Bime, C., Bime, C., Pouladi, N., Sammani, S., Batai, K., Casanova, N., Zhou, T., & Kempf, C. (2018). GWAS in African Americans identifies the Selectin P Ligand gene, SELPLG, as an ARDS risk gene. American J Respiratory Critical Care Medicine.More infoRationale: Genetic factors are involved in acute respiratory distress syndrome (ARDS) susceptibility. Identification of novel candidate genes associated with increased risk and severity will improve our understanding of ARDS pathophysiology and enhance efforts to develop novel preventive and therapeutic approaches.Objectives: To identify genetic susceptibility targets for ARDS.Methods: A genome-wide association study was performed on 232 African American patients with ARDS and 162 at-risk control subjects. The Identify Candidate Causal SNPs and Pathways platform was used to infer the association of known gene sets with the top prioritized intragenic SNPs. Preclinical validation of SELPLG (selectin P ligand gene) was performed using mouse models of LPS- and ventilator-induced lung injury. Exonic variation within SELPLG distinguishing patients with ARDS from sepsis control subjects was confirmed in an independent cohort.Measurements and Main Results: Pathway prioritization analysis identified a nonsynonymous coding SNP (rs2228315) within SELPLG, encoding P-selectin glycoprotein ligand 1, to be associated with increased susceptibility. In an independent cohort, two exonic SELPLG SNPs were significantly associated with ARDS susceptibility. Additional support for SELPLG as an ARDS candidate gene was derived from preclinical ARDS models where SELPLG gene expression in lung tissues was significantly increased in both ventilator-induced (twofold increase) and LPS-induced (5.7-fold increase) murine lung injury models compared with controls. Furthermore, Selplg−/− mice exhibited significantly reduced LPS-induced inflammatory lung injury compared with wild-type C57/B6 mice. Finally, an antibody that neutralizes P-selectin glycoprotein ligand 1 significantly attenuated LPS-induced lung inflammation.Conclusions: These findings identify SELPLG as a novel ARDS susceptibility gene among individuals of European and African descent.
- Liu, P., Rojo de la Vega, M., Sammani, S., Mascarenhas, J. B., Kerins, M., Dodson, M., Sun, X., Wang, T., Ooi, A., Garcia, J. G., & Zhang, D. D. (2018). RPA1 binding to NRF2 switches ARE-dependent transcriptional activation to ARE-NRE-dependent repression. Proceedings of the National Academy of Sciences of the United States of America, 115(44), E10352-E10361.More infoNRF2 regulates cellular redox homeostasis, metabolic balance, and proteostasis by forming a dimer with small musculoaponeurotic fibrosarcoma proteins (sMAFs) and binding to antioxidant response elements (AREs) to activate target gene transcription. In contrast, NRF2-ARE-dependent transcriptional repression is unreported. Here, we describe NRF2-mediated gene repression via a specific seven-nucleotide sequence flanking the ARE, which we term the NRF2-replication protein A1 (RPA1) element (NRE). Mechanistically, RPA1 competes with sMAF for NRF2 binding, followed by interaction of NRF2-RPA1 with the ARE-NRE and eduction of promoter activity. Genome-wide in silico and RNA-seq analyses revealed this NRF2-RPA1-ARE-NRE complex mediates negative regulation of many genes with diverse functions, indicating that this mechanism is a fundamental cellular process. Notably, repression of , which encodes the nonmuscle myosin light chain kinase, by the NRF2-RPA1-ARE-NRE complex disrupts vascular integrity in preclinical inflammatory lung injury models, illustrating the translational significance of NRF2-mediated transcriptional repression. Our findings reveal a gene-suppressive function of NRF2 and a subset of negatively regulated NRF2 target genes, underscoring the broad impact of NRF2 in physiological and pathological settings.
- Palumbo, S., Shin, Y. J., Ahmad, K., Desai, A. A., Quijada, H., Mohamed, M., Knox, A., Sammani, S., Colson, B. A., Wang, T., Garcia, J. G., & Hecker, L. (2017). Dysregulated Nox4 ubiquitination contributes to redox imbalance and age-related severity of acute lung injury. American journal of physiology. Lung cellular and molecular physiology, ajplung.00305.2016.More infoAcute respiratory distress syndrome (ARDS) is a devastating critical illness disproportionately affecting the elderly population(higher incidence and mortality). The integrity of the lung endothelial cell (EC) monolayer is critical for preservation of lung function. However, mechanisms mediating EC barrier regulation in aging remain unclear. We assessed the severity of acute lung injury (ALI) in young (2 months) and aged (18 months) mice using a two-hit pre-clinical model. Compared to young cohorts, aged mice exhibited increased ALI severity, with greater vascular permeability characterized by elevated albumin influx, levels of bronchoalveolar lavage (BAL) cells (neutrophils) and protein. Aged/injured mice also demonstrated elevated levels of reactive oxygen species (ROS) in the BAL, associated with upregulation of the ROS-generating enzyme, Nox4. We evaluated the role of aging in human lung EC barrier regulation utilizing a cellular model of replicative senescence. Senescent EC populations were defined by increases in beta-galactosidase activity and p16 levels. In response to lipopolysaccharide (LPS) challenge, senescent ECs demonstrate exacerbated permeability responses compared to control "young" ECs. LPS challenge led to a rapid induction of Nox4 expression in both control and senescent ECs, which was post-translationally mediated via the proteasome/ubiquitin system. However, senescent ECs demonstrated deficient Nox4 ubiquitination, resulting in sustained expression of Nox4and alterations in cellular redox homeostasis. Pharmacologic inhibition of Nox4 in senescent ECs reduced LPS-induced alterations in permeability. These studies provide insight into the roles of Nox4/senescence in EC barrier responses and offer a mechanistic link to the increased incidence and mortality of ARDS associated with aging.
- Sun, X., Mathew, B., Sammani, S., Jacobson, J. R., & Garcia, J. G. (2017). Simvastatin-induced sphingosine 1-phosphate receptor 1 expression is KLF2-dependent in human lung endothelial cells. Pulmonary circulation, 7(1), 117-125.More infoWe have demonstrated that simvastatin and sphingosine 1-phosphate (S1P) both attenuate increased vascular permeability in preclinical models of acute respiratory distress syndrome. However, the underlying mechanisms remain unclear. As Krüppel-like factor 2 (KLF2) serves as a critical regulator for cellular stress response in endothelial cells (EC), we hypothesized that simvastatin enhances endothelial barrier function via increasing expression of the barrier-promoting S1P receptor, S1PR1, via a KLF2-dependent mechanism. S1PR1 luciferase reporter promoter activity in human lung artery EC (HPAEC) was tested after simvastatin (5 μM), and S1PR1 and KLF2 protein expression detected by immunoblotting. In vivo, transcription and expression of S1PR1 and KLF2 in mice lungs were detected by microarray profiling and immunoblotting after exposure to simvastatin (10 mg/kg). Endothelial barrier function was measured by trans-endothelial electrical resistance with the S1PR1 agonist FTY720-(S)-phosphonate. Both S1PR1 and KLF2 gene expression (mRNA, protein) were significantly increased by simvastatin in vitro and in vivo. S1PR1 promoter activity was significantly increased by simvastatin (P
- Clark, S. E., Purcell, J. E., Sammani, S., Steffen, E. K., Crim, M. J., Livingston, R. S., Besch-Williford, C., & Fortman, J. D. (2016). Bordetella pseudohinzii as a Confounding Organism in Murine Models of Pulmonary Disease. Comparative medicine, 66(5), 361-366.More infoA group studying acute lung injury observed an increased percentage of neutrophils in the bronchoalveolar lavage (BAL) fluid of mice. BAL was performed, and lung samples were collected sterilely from 5 C57BL/6 mice that had been bred inhouse. Pure colonies of bacteria, initially identified as Bordetella hinzii were cultured from 2 of the 5 mice which had the highest percentages of neutrophils (21% and 26%) in the BAL fluid. Subsequent sequencing of a portion of the ompA gene from this isolate demonstrated 100% homology with the published B. pseudohinzii sequence. We then selected 10 mice from the investigator's colony to determine the best test to screen for B. pseudohinzii in the facility. BAL was performed, the left lung lobe was collected for culture and PCR analysis, the right lung lobe and nasal passages were collected for histopathology, an oral swab was collected for culture, and an oral swab and fecal pellets were collected for PCR analysis. B. pseudohinzii was cultured from the oral cavity, lung, or both in 8 of the 10 mice analyzed. All 8 of these mice were fecal PCR positive for B. pseudohinzii; 7 had increased neutrophils (5% to 20%) in the BAL fluid, whereas the 8th mouse had a normal neutrophil percentage (2%). Active bronchopneumonia was not observed, but some infected mice had mild to moderate rhinitis. B. pseudohinzii appears to be a microbial agent of importance in mouse colonies that can confound pulmonary research. Commercial vendors and institutions should consider colony screening, routine reporting, and exclusion of B. pseudohinzii.
- Letsiou, E., Sammani, S., Wang, H., Belvitch, P., & Dudek, S. M. (2016). Parkin regulates lipopolysaccharide-induced proinflammatory responses in acute lung injury. Translational research : the journal of laboratory and clinical medicine.More infoThe acute respiratory distress syndrome (ARDS) is a serious condition resulting from direct or indirect lung injury that is associated with high mortality and morbidity. A key biological event in the pathogenesis of the acute lung injury (ALI) that causes acute respiratory distress syndrome is activation of the lung endothelium cells (ECs), which is triggered by a variety of inflammatory insults leading to barrier disruption and excessive accumulation of neutrophils. Recently, we demonstrated that imatinib protects against lipopolysaccharide (LPS)-induced EC activation by inhibiting c-Abl kinase. In the present study, we explored the role of parkin, a novel c-Abl substrate, in ALI. Parkin is an E3 ubiquitin ligase originally characterized in the pathogenesis of Parkinson disease; however, its potential role in acute inflammatory processes and lung EC function remains largely unknown. Using parkin deficient (PARK2-/-) mice, we now demonstrate that parkin mediates LPS-induced ALI. After LPS, PARK2-/- mice have reduced total protein and cell levels in bronchoalveolar lavage (BAL) compared to wild type. Moreover, in LPS-treated PARK2-/- lungs, the sequestration and activation of neutrophils and release of inflammatory cytokines (interleukin 6 [IL-6], tumor necrosis factor alpha [TNF-α]) are significantly reduced. The BAL levels of soluble VCAM-1 and ICAM-1 are also decreased in LPS-treated PARK2-/- mice compared to wild type. In cultured human lung endothelial cells, downregulation of parkin by small interfering RNA decreases LPS-induced VCAM-1 expression, IL-8 and IL-6 secretion, and NF-kB phosphorylation. These results suggest a previously unidentified role of parkin in mediating endotoxin-induced endothelial proinflammatory signaling and indicate that it may play a critical role in acute inflammation.
- Camp, S. M., Ceco, E., Evenoski, C. L., Danilov, S. M., Zhou, T., Chiang, E. T., Moreno-Vinasco, L., Mapes, B., Zhao, J., Gursoy, G., Brown, M. E., Adyshev, D. M., Siddiqui, S. S., Quijada, H., Sammani, S., Letsiou, E., Saadat, L., Yousef, M., Wang, T., , Liang, J., et al. (2015). Unique Toll-Like Receptor 4 Activation by NAMPT/PBEF Induces NFκB Signaling and Inflammatory Lung Injury. Scientific reports, 5, 13135.More infoVentilator-induced inflammatory lung injury (VILI) is mechanistically linked to increased NAMPT transcription and circulating levels of nicotinamide phosphoribosyl-transferase (NAMPT/PBEF). Although VILI severity is attenuated by reduced NAMPT/PBEF bioavailability, the precise contribution of NAMPT/PBEF and excessive mechanical stress to VILI pathobiology is unknown. We now report that NAMPT/PBEF induces lung NFκB transcriptional activities and inflammatory injury via direct ligation of Toll-like receptor 4 (TLR4). Computational analysis demonstrated that NAMPT/PBEF and MD-2, a TLR4-binding protein essential for LPS-induced TLR4 activation, share ~30% sequence identity and exhibit striking structural similarity in loop regions critical for MD-2-TLR4 binding. Unlike MD-2, whose TLR4 binding alone is insufficient to initiate TLR4 signaling, NAMPT/PBEF alone produces robust TLR4 activation, likely via a protruding region of NAMPT/PBEF (S402-N412) with structural similarity to LPS. The identification of this unique mode of TLR4 activation by NAMPT/PBEF advances the understanding of innate immunity responses as well as the untoward events associated with mechanical stress-induced lung inflammation.
- Letsiou, E., Sammani, S., Zhang, W., Zhou, T., Quijada, H., Moreno-Vinasco, L., Dudek, S. M., & Garcia, J. G. (2015). Pathologic mechanical stress and endotoxin exposure increases lung endothelial microparticle shedding. American journal of respiratory cell and molecular biology, 52(2), 193-204.More infoAcute lung injury (ALI) results from infectious challenges and from pathologic lung distention produced by excessive tidal volume delivered during mechanical ventilation (ventilator-induced lung injury [VILI]) and is characterized by extensive alveolar and vascular dysfunction. Identification of novel ALI therapies is hampered by the lack of effective ALI/VILI biomarkers. We explored endothelial cell (EC)-derived microparticles (EMPs) (0.1-1 μm) as potentially important markers and potential mediators of lung vascular injury in preclinical models of ALI and VILI. We characterized EMPs (annexin V and CD31 immunoreactivity) produced from human lung ECs exposed to physiologic or pathologic mechanical stress (5 or 18% cyclic stretch [CS]) or to endotoxin (LPS). EC exposure to 18% CS or to LPS resulted in increased EMP shedding compared with static cells (∼ 4-fold and ∼ 2.5-fold increases, respectively). Proteomic analysis revealed unique 18% CS-derived (n = 10) and LPS-derived EMP proteins (n = 43). VILI-challenged mice (40 ml/kg, 4 h) exhibited increased plasma and bronchoalveolar lavage CD62E (E-selectin)-positive MPs compared with control mice. Finally, mice receiving intratracheal instillation of 18% CS-derived EMPs displayed significant lung inflammation and injury. These findings indicate that ALI/VILI-producing stimuli induce significant shedding of distinct EMP populations that may serve as potential ALI biomarkers and contribute to the severity of lung injury.
- Mathew, B., Takekoshi, D., Sammani, S., Epshtein, Y., Sharma, R., Smith, B. D., Mitra, S., Desai, A. A., Weichselbaum, R. R., Garcia, J. G., & Jacobson, J. R. (2015). Role of GADD45a in murine models of radiation- and bleomycin-induced lung injury. American journal of physiology. Lung cellular and molecular physiology, 309(12), L1420-9.More infoWe previously reported protective effects of GADD45a (growth arrest and DNA damage-inducible gene 45 alpha) in murine ventilator-induced lung injury (VILI) via effects on Akt-mediated endothelial cell signaling. In the present study we investigated the role of GADD45a in separate murine models of radiation- and bleomycin-induced lung injury. Initial studies of wild-type mice subjected to single-dose thoracic radiation (10 Gy) confirmed a significant increase in lung GADD45a expression within 24 h and persistent at 6 wk. Mice deficient in GADD45a (GADD45a(-/-)) demonstrated increased susceptibility to radiation-induced lung injury (RILI, 10 Gy) evidenced by increased bronchoalveolar lavage (BAL) fluid total cell counts, protein and albumin levels, and levels of inflammatory cytokines compared with RILI-challenged wild-type animals at 2 and 4 wk. Furthermore, GADD45a(-/-) mice had decreased total and phosphorylated lung Akt levels both at baseline and 6 wk after RILI challenge relative to wild-type mice while increased RILI susceptibility was observed in both Akt(+/-) mice and mice treated with an Akt inhibitor beginning 1 wk prior to irradiation. Additionally, overexpression of a constitutively active Akt1 transgene reversed RILI-susceptibility in GADD45a(-/-) mice. In separate studies, lung fibrotic changes 2 wk after treatment with bleomycin (0.25 U/kg IT) was significantly increased in GADD45a(-/-) mice compared with wild-type mice assessed by lung collagen content and histology. These data implicate GADD45a as an important modulator of lung inflammatory responses across different injury models and highlight GADD45a-mediated signaling as a novel target in inflammatory lung injury clinically.
- Rizzo, A. N., Sammani, S., Esquinca, A. E., Jacobson, J. R., Garcia, J. G., Letsiou, E., & Dudek, S. M. (2015). Imatinib attenuates inflammation and vascular leak in a clinically relevant two-hit model of acute lung injury. American journal of physiology. Lung cellular and molecular physiology, 309(11), L1294-304.More infoAcute lung injury/acute respiratory distress syndrome (ALI/ARDS), an illness characterized by life-threatening vascular leak, is a significant cause of morbidity and mortality in critically ill patients. Recent preclinical studies and clinical observations have suggested a potential role for the chemotherapeutic agent imatinib in restoring vascular integrity. Our prior work demonstrates differential effects of imatinib in mouse models of ALI, namely attenuation of LPS-induced lung injury but exacerbation of ventilator-induced lung injury (VILI). Because of the critical role of mechanical ventilation in the care of patients with ARDS, in the present study we pursued an assessment of the effectiveness of imatinib in a "two-hit" model of ALI caused by combined LPS and VILI. Imatinib significantly decreased bronchoalveolar lavage protein, total cells, neutrophils, and TNF-α levels in mice exposed to LPS plus VILI, indicating that it attenuates ALI in this clinically relevant model. In subsequent experiments focusing on its protective role in LPS-induced lung injury, imatinib attenuated ALI when given 4 h after LPS, suggesting potential therapeutic effectiveness when given after the onset of injury. Mechanistic studies in mouse lung tissue and human lung endothelial cells revealed that imatinib inhibits LPS-induced NF-κB expression and activation. Overall, these results further characterize the therapeutic potential of imatinib against inflammatory vascular leak.
- Chen, J., Tang, H., Sysol, J. R., Moreno-Vinasco, L., Shioura, K. M., Chen, T., Gorshkova, I., Wang, L., Huang, L. S., Usatyuk, P. V., Sammani, S., Zhou, G., Raj, J. U., Garcia, J. G., Berdyshev, E., Yuan, J. X., Natarajan, V., & Machado, R. F. (2014). The sphingosine kinase 1/sphingosine-1-phosphate pathway in pulmonary arterial hypertension. American journal of respiratory and critical care medicine, 190(9), 1032-43.More infoSphingosine kinases (SphKs) 1 and 2 regulate the synthesis of the bioactive sphingolipid sphingosine-1-phosphate (S1P), an important lipid mediator that promotes cell proliferation, migration, and angiogenesis.
- Goldman, J. L., Sammani, S., Kempf, C., Saadat, L., Letsiou, E., Wang, T., Moreno-Vinasco, L., Rizzo, A. N., Fortman, J. D., & Garcia, J. G. (2014). Pleiotropic effects of interleukin-6 in a "two-hit" murine model of acute respiratory distress syndrome. Pulmonary circulation, 4(2), 280-8.More infoPatients with acute respiratory distress syndrome (ARDS) exhibit elevated levels of interleukin-6 (IL-6), which correlate with increased morbidity and mortality. The exact role of IL-6 in ARDS has proven difficult to study because it exhibits either pro- or anti-inflammatory actions in mouse models of lung injury, depending on the model utilized. In order to improve understanding of the role of this complex cytokine in ARDS, we evaluated IL-6 using the clinically relevant combination of lipopolysaccharide (LPS) and ventilator-induced lung injury (VILI) in IL-6(-/-) mice. Bronchoalveolar lavage fluid (BAL), whole-lung tissue, and histology were evaluated for inflammatory markers of injury. Transendothelial electrical resistance was used to evaluate the action of IL-6 on endothelial cells in vitro. In wild-type mice, the combination model showed a significant increase in lung injury compared to either LPS or VILI alone. IL-6(-/-) mice exhibited a statistically significant decrease in BAL cellular inflammation as well as lower histologic scores for lung injury, changes observed only in the combination model. A paradoxical increase in BAL total protein was observed in IL-6(-/-) mice exposed to LPS, suggesting that IL-6 provides protection from vascular leakage. However, in vitro data showed that IL-6, when combined with its soluble receptor, actually caused a significant increase in endothelial cell permeability, suggesting that the protection seen in vivo was likely due to complex interactions of IL-6 and other inflammatory mediators rather than to direct effects of IL-6. These studies suggest that a dual-injury model exhibits utility in evaluating the pleiotropic effects of IL-6 in ARDS on inflammatory cells and lung endothelium.
- Moreno-Vinasco, L., Quijada, H., Sammani, S., Siegler, J., Letsiou, E., Deaton, R., Saadat, L., Zaidi, R. S., Messana, J., Gann, P. H., Machado, R. F., Ma, W., Camp, S. M., Wang, T., & Garcia, J. G. (2014). Nicotinamide phosphoribosyltransferase inhibitor is a novel therapeutic candidate in murine models of inflammatory lung injury. American journal of respiratory cell and molecular biology, 51(2), 223-8.More infoWe previously identified the intracellular nicotinamide phosphoribosyltransferase (iNAMPT, aka pre-B-cell colony enhancing factor) as a candidate gene promoting acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI) with circulating nicotinamide phosphoribosyltransferase potently inducing NF-κB signaling in lung endothelium. iNAMPT also synthesizes intracellular nicotinamide adenine dinucleotide (iNAD) in response to extracellular oxidative stress, contributing to the inhibition of apoptosis via ill-defined mechanisms. We now further define the role of iNAMPT activity in the pathogenesis of ARDS/VILI using the selective iNAMPT inhibitor FK-866. C57/B6 mice were exposed to VILI (40 ml/kg, 4 h) or LPS (1.5 mg/kg, 18 h) after osmotic pump delivery of FK-866 (100 mg/kg/d, intraperitoneally). Assessment of total bronchoalveolar lavage (BAL) protein, polymorphonuclear neutrophil (PMN) levels, cytokine levels (TNF-α, IL-6, IL-1α), lung iNAD levels, and injury scores revealed that FK-866-mediated iNAMPT inhibition successfully reduced lung tissue iNAD levels, BAL injury indices, inflammatory cell infiltration, and lung injury scores in LPS- and VILI-exposed mice. FK-866 further increased lung PMN apoptosis, as reflected by caspase-3 activation in BAL PMNs. These findings support iNAMPT inhibition via FK-866 as a novel therapeutic agent for ARDS via enhanced apoptosis in inflammatory PMNs.
- Sun, X., Elangovan, V. R., Mapes, B., Camp, S. M., Sammani, S., Saadat, L., Ceco, E., Ma, S. F., Flores, C., MacDougall, M. S., Quijada, H., Liu, B., Kempf, C. L., Wang, T., Chiang, E. T., & Garcia, J. G. (2014). The NAMPT promoter is regulated by mechanical stress, signal transducer and activator of transcription 5, and acute respiratory distress syndrome-associated genetic variants. American journal of respiratory cell and molecular biology, 51(5), 660-7.More infoIncreased nicotinamide phosphoribosyltransferase (NAMPT) transcription is mechanistically linked to ventilator-induced inflammatory lung injury (VILI), with VILI severity attenuated by reduced NAMPT bioavailability. The molecular mechanisms of NAMPT promoter regulation in response to excessive mechanical stress remain poorly understood. The objective of this study was to define the contribution of specific transcription factors, acute respiratory distress syndrome (ARDS)-associated single nucleotide polymorphisms (SNPs), and promoter demethylation to NAMPT transcriptional regulation in response to mechanical stress. In vivo NAMPT protein expression levels were examined in mice exposed to high tidal volume mechanical ventilation. In vitro NAMPT expression levels were examined in human pulmonary artery endothelial cells exposed to 5 or 18% cyclic stretch (CS), with NAMPT promoter activity assessed using NAMPT promoter luciferase reporter constructs with a series of nested deletions. In vitro NAMPT transcriptional regulation was further characterized by measuring luciferase activity, DNA demethylation, and chromatin immunoprecipitation. VILI-challenged mice exhibited significantly increased NAMPT expression in bronchoalveolar lavage leukocytes and in lung endothelium. A mechanical stress-inducible region (MSIR) was identified in the NAMPT promoter from -2,428 to -2,128 bp. This MSIR regulates NAMPT promoter activity, mRNA expression, and signal transducer and activator of transcription 5 (STAT5) binding, which is significantly increased by 18% CS. In addition, NAMPT promoter activity was increased by pharmacologic promoter demethylation and inhibited by STAT5 silencing. ARDS-associated NAMPT promoter SNPs rs59744560 (-948G/T) and rs7789066 (-2,422A/G) each significantly elevated NAMPT promoter activity in response to 18% CS in a STAT5-dependent manner. Our results show that NAMPT is a key novel ARDS therapeutic target and candidate gene with genetic/epigenetic transcriptional regulation in response to excessive mechanical stress.
- Wang, L., Sammani, S., Moreno-Vinasco, L., Letsiou, E., Wang, T., Camp, S. M., Bittman, R., Garcia, J. G., & Dudek, S. M. (2014). FTY720 (s)-phosphonate preserves sphingosine 1-phosphate receptor 1 expression and exhibits superior barrier protection to FTY720 in acute lung injury. Critical care medicine, 42(3), e189-99.More infoEffective therapies are needed to reverse the increased vascular permeability that characterizes acute inflammatory diseases such as acute lung injury. FTY720 is a pharmaceutical analog of the potent barrier-enhancing phospholipid, sphingosine 1-phosphate. Because both FTY720 and sphingosine 1-phosphate have properties that may limit their usefulness in patients with acute lung injury, alternative compounds are needed for therapeutic use. The objective of this study is to characterize the effects of FTY720 (S)-phosphonate, a novel analog of FTY720-phosphate, on variables of pulmonary vascular permeability in vitro and alveolar-capillary permeability in vivo.
- Wang, T., Moreno-Vinasco, L., Ma, S. F., Zhou, T., Shimizu, Y., Sammani, S., Epshtein, Y., Watterson, D. M., Dudek, S. M., & Garcia, J. G. (2014). Nonmuscle myosin light chain kinase regulates murine asthmatic inflammation. American journal of respiratory cell and molecular biology, 50(6), 1129-35.More infoMyosin light chain kinase (MLCK; gene code, MYLK) is a multifunctional enzyme involved in isoform-specific nonmuscle (nm) and smooth muscle contraction, inflammation, and vascular permeability, processes directly relevant to asthma pathobiology. In this report, we highlight the contribution of the nm isoform (nmMLCK) to asthma susceptibility and severity, supported by studies in two lines of transgenic mice with knocking out nmMLCK or selectively overexpressing nmMLCK in endothelium. These mice were sensitized to exhibit ovalbumin-mediated allergic inflammation. Genetically engineered mice with targeted nmMLCK deletion (nmMLCK(-/-)) exhibited significant reductions in lung inflammation and airway hyperresponsiveness. Conversely, mice with overexpressed nmMLCK in endothelium (nmMLCK(ec/ec)) exhibited elevated susceptibility and severity in asthmatic inflammation. In addition, reduction of nmMLCK expression in pulmonary endothelium by small interfering RNA results in reduced asthmatic inflammation in wild-type mice. These pathophysiological assessments demonstrate the positive contribution of nmMLCK to asthmatic inflammation, and a clear correlation of the level of nmMLCK with the degree of experimental allergic inflammation. This study confirms MYLK as an asthma candidate gene, and verifies nmMLCK as a novel molecular target in asthmatic pathobiology.
- Chen, W., Sammani, S., Mitra, S., Ma, S. F., Garcia, J. G., & Jacobson, J. R. (2012). Critical role for integrin-β4 in the attenuation of murine acute lung injury by simvastatin. American journal of physiology. Lung cellular and molecular physiology, 303(4), L279-85.More infoThe statins are a class of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase inhibitors that are recognized to have pleiotropic properties. We previously reported the attenuation of LPS-induced murine acute lung injury (ALI) by simvastatin in vivo and identified relevant effects of simvastatin on endothelial cell (EC) signaling, activation, and barrier function in vitro. In particular, simvastatin induces the upregulation of integrin-β4, which in turn inhibits EC inflammatory responses via attenuation of MAPK signaling. The role of integrin-β4 in murine ALI protection by simvastatin, however, is unknown. We initially confirmed a time- and dose-dependent effect of simvastatin on increased integrin-β4 mRNA expression in human lung EC with peak protein expression evident at 16 h. Subsequently, reciprocal immunoprecipitation demonstrated an attenuation of LPS-induced integrin-β4 tyrosine phosphorylation by simvastatin (5 μM, 16 h). Increased expression of EC inflammatory cytokines [IL-6, IL-8, monocyte chemoattractant protein (MCP)-1, regulated on activation normal T cell expressed and secreted (RANTES)] by LPS (500 ng/ml, 4 h) was also significantly attenuated by simvastatin pretreatment (5 μM, 16 h), but this effect was reversed by cotreatment with an integrin-β4-blocking antibody. Finally, although simvastatin (20 mg/kg) conferred significant protection in murine ALI as evidenced by decreased bronchoalveolar lavage fluid cell counts, protein, inflammatory cytokines (IL-6, IL-1β, MCP-1, RANTES), decreased Evans blue dye albumin extravasation in lung tissue, and changes on lung histology, these effects were reversed by the integrin-β4-blocking antibody (IV, 1 mg/kg, 2 h before LPS). These findings support integrin-β4 as an important mediator of ALI protection by simvastatin and implicate signaling by integrin-β4 as a novel therapeutic target in patients with ALI.
- Sun, X., Singleton, P. A., Letsiou, E., Zhao, J., Belvitch, P., Sammani, S., Chiang, E. T., Moreno-Vinasco, L., Wade, M. S., Zhou, T., Liu, B., Parastatidis, I., Thomson, L., Ischiropoulos, H., Natarajan, V., Jacobson, J. R., Machado, R. F., Dudek, S. M., & Garcia, J. G. (2012). Sphingosine-1-phosphate receptor-3 is a novel biomarker in acute lung injury. American journal of respiratory cell and molecular biology, 47(5), 628-36.More infoThe inflamed lung exhibits oxidative and nitrative modifications of multiple target proteins, potentially reflecting disease severity and progression. We identified sphingosine-1-phosphate receptor-3 (S1PR3), a critical signaling molecule mediating cell proliferation and vascular permeability, as a nitrated plasma protein in mice with acute lung injury (ALI). We explored S1PR3 as a potential biomarker in murine and human ALI. In vivo nitrated and total S1PR3 concentrations were determined by immunoprecipitation and microarray studies in mice, and by ELISA in human plasma. In vitro nitrated S1PR3 concentrations were evaluated in human lung vascular endothelial cells (ECs) or within microparticles shed from ECs after exposure to barrier-disrupting agonists (LPS, low-molecular-weight hyaluronan, and thrombin). The effects of S1PR3-containing microparticles on EC barrier function were assessed by transendothelial electrical resistance (TER). Nitrated S1PR3 was identified in the plasma of murine ALI and in humans with severe sepsis-induced ALI. Elevated total S1PR3 plasma concentrations (> 251 pg/ml) were linked to sepsis and ALI mortality. In vitro EC exposure to barrier-disrupting agents induced S1PR3 nitration and the shedding of S1PR3-containing microparticles, which significantly reduced TER, consistent with increased permeability. These changes were attenuated by reduced S1PR3 expression (small interfering RNAs). These results suggest that microparticles containing nitrated S1PR3 shed into the circulation during inflammatory lung states, and represent a novel ALI biomarker linked to disease severity and outcome.
- Wang, T., Wang, L., Zaidi, S. R., Sammani, S., Siegler, J., Moreno-Vinasco, L., Mathew, B., Natarajan, V., & Garcia, J. G. (2012). Hydrogen sulfide attenuates particulate matter-induced human lung endothelial barrier disruption via combined reactive oxygen species scavenging and Akt activation. American journal of respiratory cell and molecular biology, 47(4), 491-6.More infoExposure to particulate air pollution is associated with increased cardiopulmonary morbidity and mortality, although the pathogenic mechanisms are poorly understood. We previously demonstrated that particulate matter (PM) exposure triggers massive oxidative stress in vascular endothelial cells (ECs), resulting in the loss of EC integrity and lung vascular hyperpermeability. We investigated the protective role of hydrogen sulfide (H(2)S), an endogenous gaseous molecule present in the circulation, on PM-induced human lung EC barrier disruption and pulmonary inflammation. Alterations in EC monolayer permeability, as reflected by transendothelial electrical resistance (TER), the generation of reactive oxygen species (ROS), and murine pulmonary inflammatory responses, were studied after exposures to PM and NaSH, an H(2)S donor. Similar to N-acetyl cysteine (5 mM), NaSH (10 μM) significantly scavenged PM-induced EC ROS and inhibited the oxidative activation of p38 mitogen-activated protein kinase. Concurrent with these events, NaSH (10 μM) activated Akt, which helps maintain endothelial integrity. Both of these pathways contribute to the protective effect of H(2)S against PM-induced endothelial barrier dysfunction. Furthermore, NaSH (20 mg/kg) reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in a murine model of PM-induced lung inflammation. These data suggest a potentially protective role for H(2)S in PM-induced inflammatory lung injury and vascular hyperpermeability.
- Barca-Mayo, O., Liao, X. H., DiCosmo, C., Dumitrescu, A., Moreno-Vinasco, L., Wade, M. S., Sammani, S., Mirzapoiazova, T., Garcia, J. G., Refetoff, S., & Weiss, R. E. (2011). Role of type 2 deiodinase in response to acute lung injury (ALI) in mice. Proceedings of the National Academy of Sciences of the United States of America, 108(49), E1321-9.More infoThyroid hormone (TH) metabolism, mediated by deiodinase types 1, 2, and 3 (D1, D2, and D3) is profoundly affected by acute illness. We examined the role of TH metabolism during ventilator-induced lung injury (VILI) in mice. Mice exposed to VILI recapitulated the serum TH findings of acute illness, namely a decrease in 3,5,3'-triiodothyronine (T(3)) and thyroid-stimulating hormone and an increase in reverse T(3). Both D2 immunoreactivity and D2 enzymatic activity were increased significantly. D1 and D3 activity did not change. Using D2 knockout (D2KO) mice, we determined whether the increase in D2 was an adaptive response. Although similar changes in serum TH levels were observed in D2KO and WT mice, D2KO mice exhibited greater susceptibility to VILI than WT mice, as evidenced by poorer alveoli integrity and quantified by lung chemokine and cytokine mRNA induction. These data suggest that an increase in lung D2 is protective against VILI. Similar findings of increased inflammatory markers were found in hypothyroid WT mice exposed to VILI compared with euthyroid mice, indicating that the lungs were functionally hypothyroid. Treatment of D2KO mice with T(3) reversed many of the lung chemokine and cytokine profiles seen in response to VILI, demonstrating a role for T(3) in the treatment of lung injury. We conclude that TH metabolism in the lung is linked to the response to inflammatory injury and speculate that D2 exerts its protective effect by making more TH available to the injured lung tissue.
- Ma, S. F., Xie, L., Pino-Yanes, M., Sammani, S., Wade, M. S., Letsiou, E., Siegler, J., Wang, T., Infusino, G., Kittles, R. A., Flores, C., Zhou, T., Prabhakar, B. S., Moreno-Vinasco, L., Villar, J., Jacobson, J. R., Dudek, S. M., & Garcia, J. G. (2011). Type 2 deiodinase and host responses of sepsis and acute lung injury. American journal of respiratory cell and molecular biology, 45(6), 1203-11.More infoThe role of thyroid hormone metabolism in clinical outcomes of the critically ill remains unclear. Using preclinical models of acute lung injury (ALI), we assessed the gene and protein expression of type 2 deiodinase (DIO2), a key driver for synthesis of biologically active triiodothyronine, and addressed potential association of DIO2 genetic variants with ALI in a multiethnic cohort. DIO2 gene and protein expression levels in murine lung were validated by microarrays and immunoblotting. Lung injury was assessed by levels of bronchoalveolar lavage protein and leukocytes. Single-nucleotide polymorphisms were genotyped and ALI susceptibility association assessed. Significant increases in both DIO2 gene and D2 protein expression were observed in lung tissues from murine ALI models (LPS- and ventilator-induced lung injury), with expression directly increasing with the extent of lung injury. Mice with reduced levels of DIO2 expression (by silencing RNA) demonstrated reduced thyroxine levels in plasma and increased lung injury (increased bronchoalveolar lavage protein and leukocytes), suggesting a protective role for DIO2 in ALI. The G (Ala) allele of the Thr92Ala coding single-nucleotide polymorphism (rs225014) was protective in severe sepsis and severe sepsis-associated ALI after adjustments for age, sex, and genetic ancestry in a logistic regression model in European Americans. Our studies indicate that DIO2 is a novel ALI candidate gene, the nonsynonymous Thr92Ala coding variant of which confers ALI protection. Increased DIO2 expression may dampen the ALI inflammatory response, thereby strengthening the premise that thyroid hormone metabolism is intimately linked to the integrated response to inflammatory injury in critically ill patients.
- Mathew, B., Huang, Y., Jacobson, J. R., Berdyshev, E., Gerhold, L. M., Wang, T., Moreno-Vinasco, L., Lang, G., Zhao, Y., Chen, C. T., LaRiviere, P. J., Mauceri, H., Sammani, S., Husain, A. N., Dudek, S. M., Natarajan, V., Lussier, Y. A., Weichselbaum, R. R., & Garcia, J. G. (2011). Simvastatin attenuates radiation-induced murine lung injury and dysregulated lung gene expression. American journal of respiratory cell and molecular biology, 44(3), 415-22.More infoNovel therapies are desperately needed for radiation-induced lung injury (RILI), which, despite aggressive corticosteroid therapy, remains a potentially fatal and dose-limiting complication of thoracic radiotherapy. We assessed the utility of simvastatin, an anti-inflammatory and lung barrier-protective agent, in a dose- and time-dependent murine model of RILI (18-(25 Gy). Simvastatin reduced multiple RILI indices, including vascular leak, leukocyte infiltration, and histological evidence of oxidative stress, while reversing RILI-associated dysregulated gene expression, including p53, nuclear factor-erythroid-2-related factor, and sphingolipid metabolic pathway genes. To identify key regulators of simvastatin-mediated RILI protection, we integrated whole-lung gene expression data obtained from radiated and simvastatin-treated mice with protein-protein interaction network analysis (single-network analysis of proteins). Topological analysis of the gene product interaction network identified eight top-prioritized genes (Ccna2a, Cdc2, fcer1 g, Syk, Vav3, Mmp9, Itgam, Cd44) as regulatory nodes within an activated RILI network. These studies identify the involvement of specific genes and gene networks in RILI pathobiology, and confirm that statins represent a novel strategy to limit RILI.
- Mathew, B., Jacobson, J. R., Berdyshev, E., Huang, Y., Sun, X., Zhao, Y., Gerhold, L. M., Siegler, J., Evenoski, C., Wang, T., Zhou, T., Zaidi, R., Moreno-Vinasco, L., Bittman, R., Chen, C. T., LaRiviere, P. J., Sammani, S., Lussier, Y. A., Dudek, S. M., , Natarajan, V., et al. (2011). Role of sphingolipids in murine radiation-induced lung injury: protection by sphingosine 1-phosphate analogs. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 25(10), 3388-400.More infoClinically significant radiation-induced lung injury (RILI) is a common toxicity in patients administered thoracic radiotherapy. Although the molecular etiology is poorly understood, we previously characterized a murine model of RILI in which alterations in lung barrier integrity surfaced as a potentially important pathobiological event and genome-wide lung gene mRNA levels identified dysregulation of sphingolipid metabolic pathway genes. We hypothesized that sphingolipid signaling components serve as modulators and novel therapeutic targets of RILI. Sphingolipid involvement in murine RILI was confirmed by radiation-induced increases in lung expression of sphingosine kinase (SphK) isoforms 1 and 2 and increases in the ratio of ceramide to sphingosine 1-phosphate (S1P) and dihydro-S1P (DHS1P) levels in plasma, bronchoalveolar lavage fluid, and lung tissue. Mice with a targeted deletion of SphK1 (SphK1(-/-)) or with reduced expression of S1P receptors (S1PR1(+/-), S1PR2(-/-), and S1PR3(-/-)) exhibited marked RILI susceptibility. Finally, studies of 3 potent vascular barrier-protective S1P analogs, FTY720, (S)-FTY720-phosphonate (fTyS), and SEW-2871, identified significant RILI attenuation and radiation-induced gene dysregulation by the phosphonate analog, fTyS (0.1 and 1 mg/kg i.p., 2×/wk) and to a lesser degree by SEW-2871 (1 mg/kg i.p., 2×/wk), compared with those in controls. These results support the targeting of S1P signaling as a novel therapeutic strategy in RILI.
- Mathew, B., Lennon, F. E., Siegler, J., Mirzapoiazova, T., Mambetsariev, N., Sammani, S., Gerhold, L. M., LaRiviere, P. J., Chen, C. T., Garcia, J. G., Salgia, R., Moss, J., & Singleton, P. A. (2011). The novel role of the mu opioid receptor in lung cancer progression: a laboratory investigation. Anesthesia and analgesia, 112(3), 558-67.More infoThe possibility that μ opioid agonists can influence cancer recurrence is a subject of recent interest. Epidemiologic studies suggested that there were differences in cancer recurrence in breast and prostate cancer contingent on anesthetic regimens. In this study, we identify a possible mechanism for these epidemiologic findings on the basis of μ opioid receptor (MOR) regulation of Lewis lung carcinoma (LLC) tumorigenicity in cell and animal models.
- Mirzapoiazova, T., Moitra, J., Moreno-Vinasco, L., Sammani, S., Turner, J. R., Chiang, E. T., Evenoski, C., Wang, T., Singleton, P. A., Huang, Y., Lussier, Y. A., Watterson, D. M., Dudek, S. M., & Garcia, J. G. (2011). Non-muscle myosin light chain kinase isoform is a viable molecular target in acute inflammatory lung injury. American journal of respiratory cell and molecular biology, 44(1), 40-52.More infoAcute lung injury (ALI) and mechanical ventilator-induced lung injury (VILI), major causes of acute respiratory failure with elevated morbidity and mortality, are characterized by significant pulmonary inflammation and alveolar/vascular barrier dysfunction. Previous studies highlighted the role of the non-muscle myosin light chain kinase isoform (nmMLCK) as an essential element of the inflammatory response, with variants in the MYLK gene that contribute to ALI susceptibility. To define nmMLCK involvement further in acute inflammatory syndromes, we used two murine models of inflammatory lung injury, induced by either an intratracheal administration of lipopolysaccharide (LPS model) or mechanical ventilation with increased tidal volumes (the VILI model). Intravenous delivery of the membrane-permeant MLC kinase peptide inhibitor, PIK, produced a dose-dependent attenuation of both LPS-induced lung inflammation and VILI (~50% reductions in alveolar/vascular permeability and leukocyte influx). Intravenous injections of nmMLCK silencing RNA, either directly or as cargo within angiotensin-converting enzyme (ACE) antibody-conjugated liposomes (to target the pulmonary vasculature selectively), decreased nmMLCK lung expression (∼70% reduction) and significantly attenuated LPS-induced and VILI-induced lung inflammation (∼40% reduction in bronchoalveolar lavage protein). Compared with wild-type mice, nmMLCK knockout mice were significantly protected from VILI, with significant reductions in VILI-induced gene expression in biological pathways such as nrf2-mediated oxidative stress, coagulation, p53-signaling, leukocyte extravasation, and IL-6-signaling. These studies validate nmMLCK as an attractive target for ameliorating the adverse effects of dysregulated lung inflammation.
- Mitra, S., Sammani, S., Wang, T., Boone, D. L., Meyer, N. J., Dudek, S. M., Moreno-Vinasco, L., Garcia, J. G., & Jacobson, J. R. (2011). Role of growth arrest and DNA damage-inducible α in Akt phosphorylation and ubiquitination after mechanical stress-induced vascular injury. American journal of respiratory and critical care medicine, 184(9), 1030-40.More infoThe stress-induced growth arrest and DNA damage-inducible a (GADD45a) gene is up-regulated by mechanical stress with GADD45a knockout (GADD45a(-/-)) mice demonstrating both increased susceptibility to ventilator-induced lung injury (VILI) and reduced levels of the cell survival and vascular permeability signaling effector (Akt). However, the functional role of GADD45a in the pathogenesis of VILI is unknown.
- Sammani, S., Park, K. S., Zaidi, S. R., Mathew, B., Wang, T., Huang, Y., Zhou, T., Lussier, Y. A., Husain, A. N., Moreno-Vinasco, L., Vigneswaran, W. T., & Garcia, J. G. (2011). A sphingosine 1-phosphate 1 receptor agonist modulates brain death-induced neurogenic pulmonary injury. American journal of respiratory cell and molecular biology, 45(5), 1022-7.More infoLung transplantation remains the only viable therapy for patients with end-stage lung disease. However, the full utilization of this strategy is severely compromised by a lack of donor lung availability. The vast majority of donor lungs available for transplantation are from individuals after brain death (BD). Unfortunately, the early autonomic storm that accompanies BD often results in neurogenic pulmonary edema (NPE), producing varying degrees of lung injury or leading to primary graft dysfunction after transplantation. We demonstrated that sphingosine 1-phosphate (S1P)/analogues, which are major barrier-enhancing agents, reduce vascular permeability via the S1P1 receptor, S1PR1. Because primary lung graft dysfunction is induced by lung vascular endothelial cell barrier dysfunction, we hypothesized that the S1PR1 agonist, SEW-2871, may attenuate NPE when administered to the donor shortly after BD. Significant lung injury was observed after BD, with increases of approximately 60% in bronchoalveolar lavage (BAL) total protein, cell counts, and lung tissue wet/dry (W/D) weight ratios. In contrast, rats receiving SEW-2871 (0.1 mg/kg) 15 minutes after BD and assessed after 4 hours exhibited significant lung protection (∼ 50% reduction, P = 0.01), as reflected by reduced BAL protein/albumin, cytokines, cellularity, and lung tissue wet/dry weight ratio. Microarray analysis at 4 hours revealed a global impact of both BD and SEW on lung gene expression, with a differential gene expression of enriched immune-response/inflammation pathways across all groups. Overall, SEW served to attenuate the BD-mediated up-regulation of gene expression. Two potential biomarkers, TNF and chemokine CC motif receptor-like 2, exhibited gene array dysregulation. We conclude that SEW-2871 significantly attenuates BD-induced lung injury, and may serve as a potential candidate to improve human donor availability.
- Mambetsariev, N., Mirzapoiazova, T., Mambetsariev, B., Sammani, S., Lennon, F. E., Garcia, J. G., & Singleton, P. A. (2010). Hyaluronic Acid binding protein 2 is a novel regulator of vascular integrity. Arteriosclerosis, thrombosis, and vascular biology, 30(3), 483-90.More infoThe disruption of the endothelial cell barrier is a critical feature of inflammation and an important contributing factor to acute lung injury (ALI), an inflammatory condition that is a major cause of morbidity and mortality in critically ill patients. We evaluated the role of the extracellular serine protease, hyaluronic acid binding protein 2 (HABP2), in vascular barrier regulation.
- Sammani, S., Moreno-Vinasco, L., Mirzapoiazova, T., Singleton, P. A., Chiang, E. T., Evenoski, C. L., Wang, T., Mathew, B., Husain, A., Moitra, J., Sun, X., Nunez, L., Jacobson, J. R., Dudek, S. M., Natarajan, V., & Garcia, J. G. (2010). Differential effects of sphingosine 1-phosphate receptors on airway and vascular barrier function in the murine lung. American journal of respiratory cell and molecular biology, 43(4), 394-402.More infoThe therapeutic options for ameliorating the profound vascular permeability, alveolar flooding, and organ dysfunction that accompanies acute inflammatory lung injury (ALI) remain limited. Extending our previous finding that the intravenous administration of the sphingolipid angiogenic factor, sphingosine 1-phosphate (S1P), attenuates inflammatory lung injury and vascular permeability via ligation of S1PR(1), we determine that a direct intratracheal or intravenous administration of S1P, or a selective S1P receptor (S1PR(1)) agonist (SEW-2871), produces highly concentration-dependent barrier-regulatory responses in the murine lung. The intratracheal or intravenous administration of S1P or SEW-2871 at < 0.3 mg/kg was protective against LPS-induced murine lung inflammation and permeability. However, intratracheal delivery of S1P at 0.5 mg/kg (for 2 h) resulted in significant alveolar-capillary barrier disruption (with a 42% increase in bronchoalveolar lavage protein), and produced rapid lethality when delivered at 2 mg/kg. Despite the greater selectivity for S1PR(1), intratracheally delivered SEW-2871 at 0.5 mg/kg also resulted in significant alveolar-capillary barrier disruption, but was not lethal at 2 mg/kg. Consistent with the S1PR(1) regulation of alveolar/vascular barrier function, wild-type mice pretreated with the S1PR(1) inverse agonist, SB-649146, or S1PR(1)(+/-) mice exhibited reduced S1P/SEW-2871-mediated barrier protection after challenge with LPS. In contrast, S1PR(2)(-/-) knockout mice as well as mice with reduced S1PR(3) expression (via silencing S1PR3-containing nanocarriers) were protected against LPS-induced barrier disruption compared with control mice. These studies underscore the potential therapeutic effects of highly selective S1PR(1) receptor agonists in reducing inflammatory lung injury, and highlight the critical role of the S1P delivery route, S1PR(1) agonist concentration, and S1PR(1) expression in target tissues.
- Singleton, P. A., Mirzapoiazova, T., Guo, Y., Sammani, S., Mambetsariev, N., Lennon, F. E., Moreno-Vinasco, L., & Garcia, J. G. (2010). High-molecular-weight hyaluronan is a novel inhibitor of pulmonary vascular leakiness. American journal of physiology. Lung cellular and molecular physiology, 299(5), L639-51.More infoEndothelial cell (EC) barrier dysfunction results in increased vascular permeability, a perturbation observed in inflammatory states, tumor angiogenesis, atherosclerosis, and both sepsis and acute lung injury. Therefore, agents that enhance EC barrier integrity have important therapeutic implications. We observed that binding of high-molecular-weight hyaluronan (HMW-HA) to its cognate receptor CD44 within caveolin-enriched microdomains (CEM) enhances human pulmonary EC barrier function. Immunocytochemical analysis indicated that HMW-HA promotes redistribution of a significant population of CEM to areas of cell-cell contact. Quantitative proteomic analysis of CEM isolated from human EC demonstrated HMW-HA-mediated recruitment of cytoskeletal regulatory proteins (annexin A2, protein S100-A10, and filamin A/B). Inhibition of CEM formation [caveolin-1 small interfering RNA (siRNA) and cholesterol depletion] or silencing (siRNA) of CD44, annexin A2, protein S100-A10, or filamin A/B expression abolished HMW-HA-induced actin cytoskeletal reorganization and EC barrier enhancement. To confirm our in vitro results in an in vivo model of inflammatory lung injury with vascular hyperpermeability, we observed that the protective effects of HMW-HA on LPS-induced pulmonary vascular leakiness were blocked in caveolin-1 knockout mice. Furthermore, targeted inhibition of CD44 expression in the mouse pulmonary vasculature significantly reduced HMW-HA-mediated protection from LPS-induced hyperpermeability. These data suggest that HMW-HA, via CD44-mediated CEM signaling events, represents a potentially useful therapeutic agent for syndromes of increased vascular permeability.
- Meyer, N. J., Huang, Y., Singleton, P. A., Sammani, S., Moitra, J., Evenoski, C. L., Husain, A. N., Mitra, S., Moreno-Vinasco, L., Jacobson, J. R., Lussier, Y. A., & Garcia, J. G. (2009). GADD45a is a novel candidate gene in inflammatory lung injury via influences on Akt signaling. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 23(5), 1325-37.More infoWe explored the mechanistic involvement of the growth arrest and DNA damage-inducible gene GADD45a in lipopolysaccharide (LPS)- and ventilator-induced inflammatory lung injury (VILI). Multiple biochemical and genomic parameters of inflammatory lung injury indicated that GADD45a(-/-) mice are modestly susceptible to intratracheal LPS-induced lung injury and profoundly susceptible to high tidal volume VILI, with increases in microvascular permeability and bronchoalveolar lavage levels of inflammatory cytokines. Expression profiling of lung tissues from VILI-challenged GADD45a(-/-) mice revealed strong dysregulation in the B-cell receptor signaling pathway compared with wild-type mice and suggested the involvement of PI3 kinase/Akt signaling components. Western blot analyses of lung homogenates confirmed approximately 50% reduction in Akt protein levels in GADD45a(-/-) mice accompanied by marked increases in Akt ubiquitination. Electrical resistance measurements across human lung endothelial cell monolayers with either reduced GADD45a or Akt expression (siRNAs) revealed significant potentiation of LPS-induced human lung endothelial barrier dysfunction, which was attenuated by overexpression of a constitutively active Akt1 transgene. These studies validate GADD45a as a novel candidate gene in inflammatory lung injury and a significant participant in vascular barrier regulation via effects on Akt-mediated endothelial signaling.
- Wadgaonkar, R., Patel, V., Grinkina, N., Romano, C., Liu, J., Zhao, Y., Sammani, S., Garcia, J. G., & Natarajan, V. (2009). Differential regulation of sphingosine kinases 1 and 2 in lung injury. American journal of physiology. Lung cellular and molecular physiology, 296(4), L603-13.More infoTwo mammalian sphingosine kinase (SphK) isoforms, SphK1 and SphK2, possess identical kinase domains but have distinct kinetic properties and subcellular localizations, suggesting each has one or more specific roles in sphingosine-1-phosphate (S1P) generation. Although both kinases use sphingosine as a substrate to generate S1P, the mechanisms controlling SphK activation and subsequent S1P generation during lung injury are not fully understood. In this study, we established a murine lung injury model to investigate LPS-induced lung injury in SphK1 knockout (SphK1(-/-)) and wild-type (WT) mice. We found that SphK1(-/-) mice were much more susceptible to LPS-induced lung injury compared with their WT counterparts, quantified by multiple parameters including cytokine induction. Intriguingly, overexpression of WT SphK1 delivered by adenoviral vector to the lungs protected SphK1(-/-) mice from lung injury and attenuated the severity of the response to LPS. However, adenoviral overexpression of a SphK1 kinase-dead mutant (SphKKD) in SphK1(-/-) mouse lungs further exacerbated the response to LPS as well as the extent of lung injury. WT SphK2 adenoviral overexpression also failed to provide protection and, in fact, augmented the degree of LPS-induced lung injury. This suggested that, in vascular injury, S1P generated by SphK2 activation plays a distinctly separate role compared with SphK1-dependent S1P generation and survival signaling. Microarray and real-time RT-PCR analysis of SphK1 and SphK2 expression levels during lung injury revealed that, in WT mice, LPS treatment caused significantly enhanced SphK1 expression ( approximately 5x) levels within 6 h, which declined back to baseline levels by 24 h posttreatment. In contrast, expression of SphK2 was gradually induced following LPS treatment and was elevated within 24 h. Collectively, our results for the first time demonstrate distinct functional roles of the two SphK isoforms in the regulation of LPS-induced lung injury.
- Hong, S. B., Huang, Y., Moreno-Vinasco, L., Sammani, S., Moitra, J., Barnard, J. W., Ma, S. F., Mirzapoiazova, T., Evenoski, C., Reeves, R. R., Chiang, E. T., Lang, G. D., Husain, A. N., Dudek, S. M., Jacobson, J. R., Ye, S. Q., Lussier, Y. A., & Garcia, J. G. (2008). Essential role of pre-B-cell colony enhancing factor in ventilator-induced lung injury. American journal of respiratory and critical care medicine, 178(6), 605-17.More infoWe previously demonstrated pre-B-cell colony enhancing factor (PBEF) as a biomarker in sepsis and sepsis-induced acute lung injury (ALI) with genetic variants conferring ALI susceptibility.
- Kolosova, I. A., Mirzapoiazova, T., Moreno-Vinasco, L., Sammani, S., Garcia, J. G., & Verin, A. D. (2008). Protective effect of purinergic agonist ATPgammaS against acute lung injury. American journal of physiology. Lung cellular and molecular physiology, 294(2), L319-24.More infoAcute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are major causes of acute respiratory failure associated with high morbidity and mortality. Although ALI/ARDS pathogenesis is only partly understood, pulmonary endothelium plays a major role by regulating lung fluid balance and pulmonary edema formation. Consequently, endothelium-targeted therapies may have beneficial effects in ALI/ARDS. Recently, attention has been given to the therapeutic potential of purinergic agonists and antagonists for the treatment of cardiovascular and pulmonary diseases. Extracellular purines (adenosine, ADP, and ATP) and pyrimidines (UDP and UTP) are important signaling molecules that mediate diverse biological effects via cell-surface P2Y receptors. We previously described ATP-induced endothelial cell (EC) barrier enhancement via a complex cell signaling and hypothesized endothelial purinoreceptors activation to exert anti-inflammatory barrier-protective effects. To test this hypothesis, we used a murine model of ALI induced by intratracheal administration of endotoxin/lipopolysaccharide (LPS) and cultured pulmonary EC. The nonhydrolyzed ATP analog ATPgammaS (50-100 muM final blood concentration) attenuated inflammatory response with decreased accumulation of cells (48%, P < 0.01) and proteins (57%, P < 0.01) in bronchoalveolar lavage and reduced neutrophil infiltration and extravasation of Evans blue albumin dye into lung tissue. In cell culture model, ATPgammaS inhibited junctional permeability induced by LPS. These findings suggest that purinergic receptor stimulation exerts a protective role against ALI by preserving integrity of endothelial cell-cell junctions.
- Moitra, J., Evenoski, C., Sammani, S., Wadgaonkar, R., Turner, J. R., Ma, S. F., & Garcia, J. G. (2008). A transgenic mouse with vascular endothelial over-expression of the non-muscle myosin light chain kinase-2 isoform is susceptible to inflammatory lung injury: role of sexual dimorphism and age. Translational research : the journal of laboratory and clinical medicine, 151(3), 141-53.More infoWe have generated genetically engineered mice that are uniquely susceptible to lipopolysaccharide (LPS)-induced and mechanical ventilation-induced lung injury in a sex-specific and age-specific manner. These mice express a nonmuscle isoform of the myosin light chain kinase gene (nmMLCK2) targeted to the endothelium. Homozygous mice have significantly reduced fecundity and litter survival until weaning, and they are initially growth delayed but eventually exceed the size of wild-type littermates. Mice at all ages show increased protein transport across the lung barrier; however, the phenotype is most discernible in 8-12-week-old male mice. When subjected to a clinically relevant LPS-induced lung injury model, 8-12-week-old young females and 30-36-week-old males seem to be the most significantly injured group. In contrast, 30-36-week-old males remain the most significantly injured group when mechanically ventilated at high tidal volumes, which is a clinically relevant model of mechanical stress lung injury. These data reveal that nmMLCK2 overexpression in the endothelium exacerbates lung injury in vivo in a sexually dimorphic and age-dependent manner.
- Moreno-Vinasco, L., Gomberg-Maitland, M., Maitland, M. L., Desai, A. A., Singleton, P. A., Sammani, S., Sam, L., Liu, Y., Husain, A. N., Lang, R. M., Ratain, M. J., Lussier, Y. A., & Garcia, J. G. (2008). Genomic assessment of a multikinase inhibitor, sorafenib, in a rodent model of pulmonary hypertension. Physiological genomics, 33(2), 278-91.More infoPulmonary hypertension (PH) and cancer pathology share growth factor- and MAPK stress-mediated signaling pathways resulting in endothelial and smooth muscle cell dysfunction and angioproliferative vasculopathy. In this study, we assessed sorafenib, an antineoplastic agent and inhibitor of multiple kinases important in angiogenesis [VEGF receptor (VEGFR)-1-3, PDGF receptor (PDGFR)-beta, Raf-1 kinase] as a potential PH therapy. Two PH rat models were used: a conventional hypoxia-induced PH model and an augmented PH model combining dual VEGFR-1 and -2 inhibition (SU-5416, single 20 mg/kg injection) with hypoxia. In addition to normoxia-exposed control animals, four groups were maintained at 10% inspired O(2) fraction for 3.5 wk (hypoxia/vehicle, hypoxia/SU-5416, hypoxia/sorafenib, and hypoxia/SU-5416/sorafenib). Compared with normoxic control animals, rats exposed to hypoxia/SU-5416 developed hemodynamic and histological evidence of severe PH while rats exposed to hypoxia alone displayed only mild elevations in hemodynamic values (pulmonary vascular and right ventricular pressures). Sorafenib treatment (daily gavage, 2.5 mg/kg) prevented hemodynamic changes and demonstrated dramatic attenuation of PH-associated vascular remodeling. Compared with normoxic control rats, expression profiling (Affymetrix platform) of lung RNA obtained from hypoxia [false discovery rate (FDR) 6.5%]- and hypoxia/SU-5416 (FDR 1.6%)-challenged rats yielded 1,019 and 465 differentially regulated genes (fold change >1.4), respectively. A novel molecular signature consisting of 38 differentially expressed genes between hypoxia/SU-5416 and hypoxia/SU-5416/sorafenib (FDR 6.7%) was validated by either real-time RT-PCR or immunoblotting. Finally, immunoblotting studies confirmed the upregulation of the MAPK cascade in both PH models, which was abolished by sorafenib. In summary, sorafenib represents a novel potential treatment for severe PH with the MAPK cascade a potential canonical target.
- Moitra, J., Sammani, S., & Garcia, J. G. (2007). Re-evaluation of Evans Blue dye as a marker of albumin clearance in murine models of acute lung injury. Translational research : the journal of laboratory and clinical medicine, 150(4), 253-65.More infoQuantifying the amount of albumin conjugated to Evans Blue dye (EBA) fluxing across organ-specific vascular barriers is a popular technique to measure endothelial monolayer integrity in rodent and murine models of human diseases. We have re-evaluated this technique with a specific focus of assessing the commonly used turbidity correction factors. These factors, originally developed and required in a spectrophotometric assay to quantify Evans Blue (EB) in human infant or dog serum, produced negative numbers when applied to murine models of acute lung injury. We next sought to determine tissue-specific correction factors for murine tissues and experimentally derived such factors, which allow estimation of the amount of EB in formamide extracts of murine tissues as positive numbers. Utilization of a best fit correction factor in a lipopolysaccharide (LPS)-induced murine model of acute lung injury resulted in significantly increased sensitivity and repeatability of the EB dye tissue extravasation assay. This factor may be of significant utility in animal models of inflammatory injury.
- Moreno, L., Singleton, P. A., Sammani, S., Proia, R., Natarajan, V., Moreno, L., Moitra, J., Mirzapoiazova, T., Garcia, J. G., & Evenoski, C. (2007). 88 EFFECT OF THE S1P1 GENE KO ON LIPOPOLYSACCHARIDE-INDUCED MURINE ACUTE LUNG INJURY.. Journal of Investigative Medicine, 55(2), S363.2-S363. doi:10.1136/jim-55-02-88More infoAcute lung injury ALI/ARDS, a significant cause of morbidity and mortality, is characterized by a diffuse inflammatory parenchymal process with pulmonary EC vascular leak and alveolar flooding. This syndrome remains a significant cause of intensive care unit mortality, and more effective therapeutic interventions are needed. Our in vitro studies indicate that sphingosine 1-phosphate (S1P), a phospholipid angiogenic factor and a major barrier-protective product of platelets, produces endothelial cell barrier enhancement through ligation of the S1P family of receptors, especially S1P1, a G protein-coupled receptor expressed on vascular endothelial cells. Our previous data show that S1P, via S1P1, has impressive protective effects in both murine and canine models of ALI (McVerry et al, 2004). To better understand S1P receptors in barrier regulation, we examined LPS-induced ALI in S1P1 receptor heterozygous (S1P1R+/−) mice. Our data demonstrate that the S1P1-R+/− mice exhibit increased barrier disruption compared with wild-type mice, reflected by an increase in protein (25%) and inflammatory cell count (20%) in bronchoalveolar lavage (BAL) fluid. To confirm the role of S1P1R on the S1P barrier-protective effect, we administered S1P (UM final blood concentration, iv) simultaneously with LPS (2.5 mg/kg) and evaluated lung inflammation 18 hours later. LPS-treated wild-type mice treated with S1P demonstrated profound reductions (> 50%) in BAL protein, whereas S1P1+/− mice similarly treated with S1P only exhibited only a ≈10% increase in BAL protein. In conclusion, our data using genetically engineered mice demonstrate a critical need for S1P1 receptors in vivo, particularly in conditions of endotoxemia.
- Singleton, P. A., Moreno-Vinasco, L., Sammani, S., Wanderling, S. L., Moss, J., & Garcia, J. G. (2007). Attenuation of vascular permeability by methylnaltrexone: role of mOP-R and S1P3 transactivation. American journal of respiratory cell and molecular biology, 37(2), 222-31.More infoEndothelial cell (EC) barrier dysfunction (i.e., increased vascular permeability) is observed in inflammatory states, tumor angiogenesis, atherosclerosis, and both sepsis and acute lung injury. Therefore, agents that preserve vascular integrity have important clinical therapeutic implications. We examined the effects of methylnaltrexone (MNTX), a mu opioid receptor (mOP-R) antagonist, on human pulmonary EC barrier disruption produced by edemagenic agents including morphine, the endogenous mOP-R agonist DAMGO, thrombin, and LPS. Pretreatment of EC with MNTX (0.1 muM, 1 h) or the uncharged mOP-R antagonist naloxone attenuated morphine- and DAMGO-induced barrier disruption in vitro. However, MNTX, but not naloxone, pretreatment of EC inhibited thrombin- and LPS-induced barrier disruption, indicating potential mOP-R-independent effects of MNTX. In addition, intravenously delivered MNTX attenuated LPS-induced vascular hyperpermeability in the murine lung. We next examined the mechanistic basis for this MNTX barrier protection and observed that silencing of mOP-R attenuated the morphine- and DAMGO-induced EC barrier disruption, but not the permeability response to either thrombin or LPS. Because activation of the sphingosine 1-phosphate receptor, S1P(3), is key to a number of barrier-disruptive responses, we examined the role of this receptor in the permeability response to mOP-R ligation. Morphine, DAMGO, thrombin, and LPS induced RhoA/ROCK-mediated threonine phosphorylation of S1P(3), which was blocked by MNTX, suggesting S1P(3) transactivation. In addition, silencing of S1P(3) receptor expression (siRNA) abolished the permeability response to each edemagenic agonist. These results indicate that MNTX provides barrier protection against edemagenic agonists via inhibition of S1P(3) receptor activation and represents a potentially useful therapeutic agent for syndromes of increased vascular permeability.
- Singleton, P. A., Salgia, R., Moreno-Vinasco, L., Moitra, J., Sammani, S., Mirzapoiazova, T., & Garcia, J. G. (2007). CD44 regulates hepatocyte growth factor-mediated vascular integrity. Role of c-Met, Tiam1/Rac1, dynamin 2, and cortactin. The Journal of biological chemistry, 282(42), 30643-57.More infoThe preservation of vascular endothelial cell (EC) barrier integrity is critical to normal vessel homeostasis, with barrier dysfunction being a feature of inflammation, tumor angiogenesis, atherosclerosis, and acute lung injury. Therefore, agents that preserve or restore vascular integrity have important therapeutic implications. In this study, we explored the regulation of hepatocyte growth factor (HGF)-mediated enhancement of EC barrier function via CD44 isoforms. We observed that HGF promoted c-Met association with CD44v10 and recruitment of c-Met into caveolin-enriched microdomains (CEM) containing CD44s (standard form). Treatment of EC with CD44v10-blocking antibodies inhibited HGF-mediated c-Met phosphorylation and c-Met recruitment to CEM. Silencing CD44 expression (small interfering RNA) attenuated HGF-induced recruitment of c-Met, Tiam1 (a Rac1 exchange factor), cortactin (an actin cytoskeletal regulator), and dynamin 2 (a vesicular regulator) to CEM as well as HGF-induced trans-EC electrical resistance. In addition, silencing Tiam1 or dynamin 2 reduced HGF-induced Rac1 activation, cortactin recruitment to CEM, and EC barrier regulation. We observed that both HGF- and high molecular weight hyaluronan (CD44 ligand)-mediated protection from lipopolysaccharide-induced pulmonary vascular hyperpermeability was significantly reduced in CD44 knock-out mice, thus validating these in vitro findings in an in vivo murine model of inflammatory lung injury. Taken together, these results suggest that CD44 is an important regulator of HGF/c-Met-mediated in vitro and in vivo barrier enhancement, a process with essential involvement of Tiam1, Rac1, dynamin 2, and cortactin.
- Ma, S. F., Grigoryev, D. N., Taylor, A. D., Nonas, S., Sammani, S., Ye, S. Q., & Garcia, J. G. (2005). Bioinformatic identification of novel early stress response genes in rodent models of lung injury. American journal of physiology. Lung cellular and molecular physiology, 289(3), L468-77.More infoAcute lung injury is a complex illness with a high mortality rate (>30%) and often requires the use of mechanical ventilatory support for respiratory failure. Mechanical ventilation can lead to clinical deterioration due to augmented lung injury in certain patients, suggesting the potential existence of genetic susceptibility to mechanical stretch (6, 48), the nature of which remains unclear. To identify genes affected by ventilator-induced lung injury (VILI), we utilized a bioinformatic-intense candidate gene approach and examined gene expression profiles from rodent VILI models (mouse and rat) using the oligonucleotide microarray platform. To increase statistical power of gene expression analysis, 2,769 mouse/rat orthologous genes identified on RG_U34A and MG_U74Av2 arrays were simultaneously analyzed by significance analysis of microarrays (SAM). This combined ortholog/SAM approach identified 41 up- and 7 downregulated VILI-related candidate genes, results validated by comparable expression levels obtained by either real-time or relative RT-PCR for 15 randomly selected genes. K-mean clustering of 48 VILI-related genes clustered several well-known VILI-associated genes (IL-6, plasminogen activator inhibitor type 1, CCL-2, cyclooxygenase-2) with a number of stress-related genes (Myc, Cyr61, Socs3). The only unannotated member of this cluster (n = 14) was RIKEN_1300002F13 EST, an ortholog of the stress-related Gene33/Mig-6 gene. The further evaluation of this candidate strongly suggested its involvement in development of VILI. We speculate that the ortholog-SAM approach is a useful, time- and resource-efficient tool for identification of candidate genes in a variety of complex disease models such as VILI.
- Peng, X., Abdulnour, R. E., Sammani, S., Ma, S. F., Han, E. J., Hasan, E. J., Tuder, R., Garcia, J. G., & Hassoun, P. M. (2005). Inducible nitric oxide synthase contributes to ventilator-induced lung injury. American journal of respiratory and critical care medicine, 172(4), 470-9.More infoInducible nitric oxide synthase (iNOS) has been implicated in the development of acute lung injury. Recent studies indicate a role for mechanical stress in iNOS and endothelial NOS (eNOS) regulation.
- McVerry, B. J., Peng, X., Hassoun, P. M., Sammani, S., Simon, B. A., & Garcia, J. G. (2004). Sphingosine 1-phosphate reduces vascular leak in murine and canine models of acute lung injury. American journal of respiratory and critical care medicine, 170(9), 987-93.More infoExcessive mechanical stress is a key component of ventilator-associated lung injury, resulting in profound vascular leak and an intense inflammatory response. To extend our in vitro observations concerning the barrier-protective effects of the lipid growth factor sphingosine 1-phosphate (Sph 1-P), we assessed the ability of Sph 1-P to prevent regional pulmonary edema accumulation in clinically relevant rodent and canine models of acute lung injury induced by combined intrabronchial endotoxin administration and high tidal volume mechanical ventilation. Intravenously delivered Sph 1-P significantly attenuated both alveolar and vascular barrier dysfunction while significantly reducing shunt formation associated with lung injury. Whole lung computed tomographic image analysis demonstrated the capability of Sph 1-P to abrogate significantly the accumulation of extravascular lung water evoked by 6-hour exposure to endotoxin. Axial density profiles and vertical density gradients localized the Sph 1-P response to transitional zones between aerated and consolidated lung regions. Together, these results indicate that Sph 1-P represents a novel therapeutic intervention for the prevention of pulmonary edema related to inflammatory injury and increased vascular permeability.
- Peng, X., Hassoun, P. M., Sammani, S., McVerry, B. J., Burne, M. J., Rabb, H., Pearse, D., Tuder, R. M., & Garcia, J. G. (2004). Protective effects of sphingosine 1-phosphate in murine endotoxin-induced inflammatory lung injury. American journal of respiratory and critical care medicine, 169(11), 1245-51.More infoOur prior in vitro studies indicate that sphingosine 1-phosphate (S1P), a phospholipid angiogenic factor, produces endothelial cell barrier enhancement through ligation of endothelial differentiation gene family receptors. We hypothesized that S1P may reduce the vascular leak associated with acute lung injury and found that S1P infusion produced a rapid and significant reduction in lung weight gain (more than 50%) in the isolated perfused murine lung. The effect of S1P was next assessed in a murine model of LPS-mediated microvascular permeability and inflammation with marked increases in parameters of lung injury at both 6 and 24 hours after intratracheal LPS. Each parameter assessed was significantly reduced by intravenous S1P (1 microM final) and in selected experiments by the S1P analogue FTY720 (0.1 mg/kg, intraperitoneally) delivered 1 hour after LPS. S1P produced an approximately 40-50% reduction in LPS-mediated extravasation of Evans blue dye albumin, bronchoalveolar lavage protein content, and lung tissue myeloperoxidase activity (reflecting phagocyte infiltration). Consistent with systemic barrier enhancement, S1P significantly decreased Evans blue dye albumin extravasation and myeloperoxidase content in renal tissues of LPS-treated mice. These studies indicate that S1P significantly decreases pulmonary/renal vascular leakage and inflammation in a murine model of LPS-mediated acute lung injury and may represent a novel therapeutic strategy for vascular barrier dysfunction.