CD1d1 Intrinsic Signaling In Macrophages Controls NLRP3 Inflammasome Expression During Inflammatory Bowel Diseases

Background and Aim:Ulcerative colitis and Crohn's disease are the most common forms of human inflammatory bowel disease.Dysregulation of immune responses in the gut often associates with inflammatory bowel diseases(IBD)that imposes problems to human health.Mouse CD1d1,an ortholog of human CD1d mainly participating in lipid-antigen presentation to NKT cells,is able to generate intrinsic signals upon stimulation.Methods:First,to clarify the effect of CD1d1 on DSS induced colitis,Our group used 3%DSS drinking water to feed male wild type(WT)and CD1d1 gene knockout(KO)mice to construct acute enteritis model,To analyze the degree of inflammation,infiltration of inflammatory cells and damage of intestinal mucosa,and secretion and expression of inflammatory factors in peripheral blood and tissue samples.And to determine which cell lines CD1d1 work,We created bone marrow chimeras through bone marrow transplantation experiments and CD1d1^-/-and Cre-Lox P recombinant enzyme systems to cultivate myeloid(macrophages)CD1d1 specific knockout mice(Lym^CD1d1-/-),After DSS-induced colitis,pathological changes and disease severity of colitis compared with wild-type mice.Then we extracted peritoneal macrophages from wild-type and Lym^CD1d1-/-mice and cultured and transfected RAW264.7 cells in vitro,Give LPS stimulation,Western blot,conducted Immunofluorescence and flow cytometry,immunoprecipitation,double luciferase reporter gene technique,Ch IP experiment,small interference RNA,si RNA)Interference,The idea of cell specificity may provide a new research direction for the treatment strategy of ulcerative colitis.Result:CD1d1^-/-mice showed increased tolerance to DSS-induced colitis compared with wild-type mice,showing reduced weight loss and decreased blood stool and colon tissue HE score.bone marrow transplantation and Mice with macrophage-specific CD1d1deficiency(Lym^CD1d1-/-)acquire resistance to DSS-induced colitis,attributing to the absence of CD1d1 dependent transcriptional inhibition of NLRP3 inflammasome components.The hyperactivation of DSS-induced NLRP3 inflammasome accounts for gut epithelial proliferation and intestine-blood-barrier integrity.Mechanisti-cally,occupancy by the natural ligand glycosphingolipid iGb3,CD1d1 responds with intracellular Ser330 dephosphorylation,by thus to reduce the Peroxiredoxin1(PRDX1)-associated AKT-STAT1phosphorylation and subsequent NF-?B activation,eventually causing transcriptional downregulation of Nlrp3 and its immediate substrates Il-1?and Il-18 in macrophages.Conclusion:The endogenous iGb3 binds to macrophage CD1d1 causing intracellular Ser330 dephosphorylation and consequential reduction of AKT-STAT1-PRDX1-I?B?cascade signallings,by thus to suppress the expression of transcriptional factors Rel A,Jun B and ELK-1.CD1d1 delivers negative signals to decrease the transcription of Nlrp3,Il-1?and Il-18 genes,and functionally contributes to the pathogenesis of NLRP3-mediated inflammations.Therefore,the counterbalancing role of CD1d1 in macrophages appears to determine severity of DSS-mediated colitis in mice.These findings propose new intervention strategies for treating IBD and other inflammatory disorders.