ABSTRACT
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) result in high mortality, whereas effective treatments are limited. Methionine restriction (MR) has been reported to offer various benefits against multiple pathological processes of organ injuries. However, it remains unknown whether MR has any potential therapeutic value for ALI/ARDS. The current study was set to investigate the therapeutic potential of MR on lipopolysaccharide (LPS)-induced ALI and its underlying mechanisms. We found that MR attenuated LPS-induced pulmonary edema, hemorrhage, atelectasis, and alveolar epithelial cell injuries in mice. MR upregulated cystathionine-gamma-lyase (CSE) expression and enhanced the production of hydrogen sulfide (H2S). MR also inhibited the activation of Toll-like receptors 4 (TLR4)/NF-κB/NOD-like receptor protein 3 (NLRP3), then reduced IL-1ß, IL-6, and TNF-α release and immune cell infiltration. Moreover, the protective effects of MR on LPS-induced ALI were abrogated by inhibiting CSE, whereas exogenous H2S treatment alone mimicked the protective effects of MR in Cse-/- mice after LPS administration. In conclusion, our findings showed that MR attenuated LPS-induced lung injury through CSE and H2S modulation. This work suggests that developing MR towards clinical use for ALI/ARDS patients may be a valuable strategy.
Subject(s)
Acute Lung Injury/prevention & control , Cystathionine gamma-Lyase/metabolism , Hydrogen Sulfide/metabolism , Lipopolysaccharides/metabolism , Methionine/deficiency , Acute Lung Injury/metabolism , Animal Feed , Animals , Disease Models, Animal , Male , Mice , Mice, Inbred C57BLABSTRACT
Hepatopulmonary syndrome (HPS) markedly increases the mortality of patients. However, its pathogenesis remains incompletely understood. Rat HPS develops in common bile duct ligation (CBDL)-induced, but not thioacetamide (TAA)-induced cirrhosis. We investigated the mechanisms of HPS by comparing these two models. Pulmonary histology, blood gas exchange, and the related signals regulating macrophage accumulation were assessed in CBDL and TAA rats. Anti-polymorphonuclear leukocyte (antiPMN) and anti-granulocyte-macrophage colony stimulating factor (antiGM-CSF) antibodies, clodronate liposomes (CL), and monocyte chemoattractant protein 1 (MCP1) inhibitor (bindarit) were administrated in CBDL rats, GM-CSF, and MCP1 were administrated in bone marrow-derived macrophages (BMDMs). Pulmonary inflammatory cell recruitment, vascular dilatation, and hypoxemia were progressively developed by 1 week after CBDL, but only occurred at 4 week after TAA. Neutrophils were the primary inflammatory cells within 3 weeks after CBDL and at 4 week after TAA. M2 macrophages were the primary inflammatory cells, meantime, pulmonary fibrosis, GM-CSFR, and CCR2 were specifically increased from 4 week after CBDL. AntiPMN antibody treatment decreased neutrophil and macrophage accumulation, CL or the combination of antiGM-CSF antibody and bindarit treatment decreased macrophage recruitment, resulting in pulmonary fibrosis, vascular dilatation, and hypoxemia in CBDL rats alleviated. The combination treatment of GM-CSF and MCP1 promoted cell migration, M2 macrophage differentiation, and transforming growth factor-ß1 (TGF-ß1) production in BMDMs. Conclusively, our results highlight neutrophil recruitment mediates pulmonary vascular dilatation and hypoxemia in the early stage of rat HPS. Further, M2 macrophage accumulation induced by GM-CSF/GM-CSFR and MCP1/CCR2 leads to pulmonary fibrosis and promotes vascular dilatation and hypoxemia, as a result, HPS develops.
Subject(s)
Hepatopulmonary Syndrome/etiology , Hypoxia/etiology , Lung/metabolism , Macrophages/metabolism , Microvessels/metabolism , Neutrophils/metabolism , Pulmonary Fibrosis/etiology , Animals , Biphenyl Compounds/blood , Cell Movement , Cell Proliferation , Chemokine CCL2/metabolism , Dilatation, Pathologic , Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Hepatopulmonary Syndrome/immunology , Hepatopulmonary Syndrome/metabolism , Hepatopulmonary Syndrome/pathology , Hypoxia/immunology , Hypoxia/metabolism , Hypoxia/pathology , Inflammation Mediators/metabolism , Leucine/analogs & derivatives , Leucine/blood , Liver Cirrhosis, Experimental/complications , Lung/immunology , Lung/pathology , Macrophages/immunology , Male , Microvessels/immunology , Microvessels/pathology , Neutrophil Infiltration , Neutrophils/immunology , Phenotype , Pulmonary Fibrosis/immunology , Pulmonary Fibrosis/metabolism , Pulmonary Fibrosis/pathology , Rats, Sprague-Dawley , Receptors, CCR2/metabolism , Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Time Factors , Transforming Growth Factor beta1/metabolismABSTRACT
Acute Lung Injury is a common severe pathological condition that is usually caused by lipopolysaccharide (LPS) infection from bacteria. Enhanced activity of nuclear factor erythroid 2-related factor 2 (Nrf2) could attenuate LPS induced lung injury, However, it still remains unknown whether the enhanced activity of Nrf2 via suppression of Nrf2 nucleus export attenuates the LPS induced lung injury. The aim of this study is to investigate the effects of inhibitors of Fyn on the LPS-induced acute lung injury and to explore its underlying molecular mechanisms. Nrf2 localization in the cells was observed by using confocal microscopy and its transcriptional activation was measured by Electrophoretic Mobility Shift Assay and controlled genes expression levels. The lung injury severity was examined by histopathological scoring and oxidative stress level. In this study, we showed that PP2, LMB, and Nrf2 Y568A abrogated Nrf2 nuclear export and thus enhance the Nrf2 transcriptional activity. PP2 attenuated lung injury and the reduction of cells viability induced by LPS. The current study demonstrated, for the first time, that increase of expression of Nrf2 controlled protective genes via suppression of Nrf2 nucleus export could attenuate lung injury.
Subject(s)
Active Transport, Cell Nucleus/drug effects , Acute Lung Injury/prevention & control , Lipopolysaccharides/toxicity , NF-E2-Related Factor 2/metabolism , Pyrimidines/pharmacology , src-Family Kinases/antagonists & inhibitors , A549 Cells , Acute Lung Injury/chemically induced , Acute Lung Injury/metabolism , Acute Lung Injury/pathology , Animals , Apoptosis , Cell Proliferation , Female , Humans , Mice , Mice, Inbred BALB C , NF-E2-Related Factor 2/geneticsABSTRACT
BACKGROUND: Blast limb injury was reported to result in distant organ injury including the lungs, which can be attenuated with transient regional hypothermia (RH) to the injured limb. We aimed to further study hepatic and renal injuries following blast limb trauma and also to evaluate the protective effects of regional traumatic limb hypothermia on such injuries in rats. METHODS: Blast limb trauma (BLT) was created using chartaceous electricity detonators in anesthetized male Sprague-Dawley rats. The BLT rats were randomly allocated to undergo regional traumatic limb hypothermic treatment (RH) for 30 minutes, 60 minutes, or 6 hours immediately after the onset of blast or without RH (n = 8 per group). The severity of hepatic and renal injury was assessed through histologic examination and water content (wet/dry weight) in all animals 6 hours later. The level of plasma tumor necrosis factor α (TNF-α), interleukin 6, hydrogen sulfide (H2S), and myeloperoxidase (MPO) together with hepatic and renal MPO, malondialdehyde (MDA), superoxide dismutase, and total antioxidant capacity were measured 6 hours after the blast injury. RESULTS: Following BLT, hepatic injury was evidenced by histopathologic changes, increased water content, as well as plasma alanine aminotransferase and aspartate aminotransferase. Renal histopathologic but not functional changes were also found. RH treatment for all durations attenuated this distant renal injury, but only RH treatment for 60 minutes and 6 hours attenuated distant hepatic injury following BLT. RH treatment for all durations decreased plasma TNF-α and interleukin 6, reduced liver and kidney MPO activity and kidney MDA, and elevated superoxide dismutase and total antioxidant capacity in both liver and kidneys. RH treatment for 60 minutes is the most effective duration to reduce hepatic MPO activity, plasma TNF-α, and kidney MDA. CONCLUSION: This study indicates that BLT-induced distant renal and hepatic injury could be attenuated by RH treatment through reduction of cytokine release and inhibition of neutrophil accumulation and oxidative stress.
