The Studies On Function And Mechanism Of S1PR1 And S1P In Acute Respiratory Distress Syndrome

Part Ⅰ The Role of S1PR1 on Pulmonary Vascular Endothelium in Acute Lung Injury Induced by Influenza Virus Background: Highly pathogenic influenza virus is a threaten to human health.In the early stage of infection,it will cause excessive immune response,which is called“cytokine storm”,and induce acute lung injury(ALI),even death.It has been reported that pulmonary endothelial cells are the key of inflammatory storm induced by influenza virus infection.Targeting sphingosine 1-phosphate receptor 1(S1PR1)can significantly reduce inflammatory immune response.In order to provide potential clinical therapies for ALI caused by influenza,our study further clarify the role of pulmonary vascular endothelial cells in the inflammatory response induced by influenza,and explore the possible mechanism of S1PR1 regulating the production of inflammatory factors.Methods: The functional role and molecular mechanism of S1PR1 were analyzed by generating inducible vascular endothelial cell-specific S1PR1 knockout mice and assessing the therapeutic efficacy of the selective S1PR1 agonist CYM-5442 against acute lung injury(ALI)induced by the 2009 influenza A H1N1 virus.After infection with influenza A(H1N1)virus,the survival time of mice was observed,the wet dry ratio of lung tissue was calculated,the degree of pathological damage of lung tissue was evaluated,and the level of inflammatory factors in bronchoalveolar lavage fluid was detected.The efficacy of combination of S1PR1 agonist CYM-5442 and antiviral drug oseltamivir was also evaluated.Results: Compared with the control mice,the mortality of endothelial cell-specific S1PR1 knockout mice was significantly higher,the degree of pulmonary edema and pathological damage was significantly increased,and the level of inflammatory factors was significantly elevated.The absence of endothelial S1PR1 and the activation of S1PR1 signaling does not affect viral clearance in mice infected with influenza.CYM-5442 can effectively alleviate the immune-mediated pulmonary injury caused by virus infection.Mechanistically,the ERK/JNK/MAPK and NF-kB signaling pathways are involved in the ALI mediated by S1PR1 in infected mice.The phosphorylation levels of ERK,JNK and p65 were weakened by treatment with CYM-5442.Combined administration of the S1PR1 agonist CYM-5442 and the antiviral drug oseltamivir provides maximum protection from ALI.Conclusions: Our current study indicates that S1PR1 plays a vital role in ALI induced by H1N1 infection.Inflammatory response can be regulated by interfering with S1PR1 of pulmonary vascular endothelial cells.The combination of S1PR1 agonist with antiviral drug could be used as a potential therapeutic remedy for future H1N1 virus pandemics.Part Ⅱ Serum Sphingosine-1-Phosphate Levels and Sphingosine-1-Phosphate Gene Polymorphisms in Acute Respiratory Distress SyndromeBackground: Sphingosine-1-phosphate(S1P)is a signaling phospholipid involved in pathophysiologic progression of acute respiratory distress syndrome(ARDS)through its roles in endothelial barrier function and immune modulation.We hypothesized that decreased serum S1P level is associated with the clinical outcomes of ARDS and polymorphisms in the S1P gene are associated with ARDS onset.Methods: This multicenter prospective study from January 2018 to August 2019 includes ARDS patients and healthy blood donors as controls.Blood samples of ARDS patients were collected within 24 hours and 7 days after admission,and relevant clinical data were collected.Serum S1P levels were quantified using enzyme-linked immunosorbent assays.The relationship between serum S1P levels and disease severity and prognosis was analyzed.Eight tag single nucleotide polymorphisms(SNPs)in the S1P gene were detected,and their associations with ARDS onset and S1P levels were evaluated.Results: A total of 121 ARDS patients and 100 healthy individuals were enrolled.Serum S1P levels were significantly lower in ARDS patients than in controls.The number of non-pulmonary organ failures and Acute Physiology and Chronic Health Evaluation Ⅱ(APACHE Ⅱ)scores were negatively correlated with serum S1P levels in ARDS patients.Decreased S1P levels correlated with more organ dysfunction and higher APACHE Ⅱ scores.Changes in S1P levels in ARDS patients were associated with the clinical outcomes.The recessive model for S1P SNP rs3743631 suggests that GG homozygote is associate with a higher risk for ARDS.The dominant model for S1P SNP rs907045 suggests that AA or TA genotype might increase the risk for ARDS.In ARDS patients,the rs3743631 GG genotype showed lower S1P levels than those harboring AG and AA genotypes.The serum S1P levels of rs907045 AA or TA genotype patients were lower than those of TT genotype.Conclusions: Serum S1P levels are dramatically decreased in ARDS patients.Reduced S1P levels are associated with worse clinical outcomes.There is a significant association between S1P rs3743631,rs907045 polymorphisms and susceptibility of ARDS.