Effect And Mechanism Of CD1d On The Pathogenesis Of Acute Colitis

ObjectiveTo observe the effect of CDld in the progress of acute colitis by using the dextran sulfate sodium(DSS)-induced colitis model of CDld-/-(genetic background:C57BL/6)mice and wild type C57BL/6 mice.Bone marrow-derived cells play a key role in regulating immune response and inflammation in the intestinal mucosal immune system.To determine whether the bone marrow-derived CDld molecule plays a role in the DSS induced colitis model.To further use bone marrow chimeric mice,namely(WT and WT bone marrow autologous transplantation:WT>WT;CDld-/-and CDld-/-bone marrow autologous transplantation:CDld-/->CDld-/-and allograft bone marrow transplantation:WT>CDld-/-or CDld-/->WT),to explore the regulation of CDld molecule in the process of colitis in mice depending on bone marrow derived hematopoietic cells.MethodSPF C57BL/6 and CDld-/-mice were given daily 2.5%DSS feeding for 6 days.The changes in body weight,fecal traits,and activity conditions were recorded every day.Disease activity index(DAI)of mice was assessed and the survival of the mice was recorded.On the 6th day,intestinal permeability was measured with FITC-dextran gavage and the length of the colon was measured.The histopathological changes of the colon were observed with H&E staining.The intestinal epithelial proliferation was detected with immunohistochemistry.SPF C57BL/6 and CDld-/-mice underwent whole body 60 Co gamma-ray irradiation with a dose of 10Gy to ablate their bone marrow,4 groups of bone marrow chimeric mice were constructed by bone marrow transplantation after 3 hours.They were given daily 2.5%DSS feeding for 7 days after 12 weeks.The changes in body weight,activity conditions,and fecal traits were recorded every day and DAI of mice was assessed.On the 7th day,intestinal permeability was measured with FITC-dextran gavage and the length of the colon was measured.The histopathological changes of the colon were observed with H&E staining.Western blot was used to detect the expression of inflammatory cytokines in colon tissue of mice.Results1 Compared with the WT mice,the survival of CD1d-/-mice was higher(P<0.05),the weight loss was slower and disease activity index(DAI)was lower(P<0.05),and the colon length was longer and intestinal permeability was lower(P<0.01),intestinal mucosal damage was lighter and colonic epithelial positive cells proliferated significantly(P?0.05).2.Compared with the receiving WT bone marrow mice,the receiving CDld-/-bone marrow mice lost more weight and had lower DAL the colon length was longer(p<0.05)and intestinal permeability was lower(P<0.01),intestinal mucosal damage was lighter and inflammatory cells infiltrated was less.The expression levels of NLRP3 and IL-18 were higher(P<0.05).Conclusions1.CDld can promote DSS-induced colitis in mice2.Bone marrow hematopoietic cells play a major role in the colitis of CDld-/-mice may by promoting colon expression of NLRP3 inflammasome and its substrates IL-18.