Discussion On The Mechanism Of Maresin-1 Improving Colitis Based On The Influence Of Macrophage Pyroptosis

Objectives:The aim of this study was to provide new ideas for the treatment of IBD from the perspective of the effect of MaRl on scorch death.Methods:The experiments were divided into in vitro and in vivo experiments.In the in vitro experiments,mouse macrophages induced by lipopolysaccharide(LPS)and dextran sodium sulfate(DSS)were treated with Maresin1 to detect the expression of interleukin1 β(IL-1β)and interleukin-18(IL-18)by RT-qPCR and the cells were detected by Western Blot.The expression of caspase-1 and GSDMD,caspase-1 activity assay kit and electron microscopy were used to detect the expression of caspase-1 vesicles.In the in vivo experiments,50 C57BL/6 mice were randomly divided into control(Con)group,DSS group,DSS+Mar1 group,DSS+Mar1+Caspase-1 inhibitor group and DSS+Caspase-1 inhibitor group by random number table method,and the mice were acclimatized and housed for 1 week.The mice were fed with 3%dextran sodium sulfate(DSS)dissolved in water for 7 days and changed every two days to establish an acute colitis model.Maresin1 1ng/kg/day was injected intraperitoneally for 7 days and Caspase1 inhibitor 10mg/kg/day was injected intraperitoneally for 7 days.Changes in body weight,disease activity index and colon length of mice were measured.Paraffinembedded colon tissue sections were stained with H&E,and then the inflammation and injury of colon were observed by electron microscopy.The expression of IL-1β and IL18 in colon tissue was detected by RT-qPCR,and the expression of caspase-1 and GSDMD,the key proteins of scorching death,was detected by Western Blot in colon tissue.The expression of intestinal barrier proteins Occludin and ZO-1,and apoptotic proteins BAX and BCL-2 were detected by Western Blot.RESULTS:In LPS+DSS-stimulated macrophages,MaRl inhibited the expression of scorch death-related factors IL-1β and IL-18 at the mRNA level,suppressed the expression of scorch death key proteins Caspase-1 and GSDMD,and decreased the activity of scorch death key protein Caspase-1 and the expression of scorch death vesicles.In DSS-induced colitis in mice,Maresin1 significantly improved the symptoms of DSSinduced colitis by causing weight loss,decreased DAI and shortened colon length,while significantly reducing the expression of various inflammatory cytokines(including IL-1β,IL-8),the expression of scorch death key protein Caspase-1,GSDMD and the proapoptotic protein BAX,and promoting the expression of expression of the intestinal barrier proteins Occludin and ZO-1 as well as the anti-apoptotic protein BCL-2.In addition,blocking the classical scorch death pathway with a specific caspase-1 inhibitor abolished the inhibitory effect of Maresin1 on DSS-induced colitis,while the effect of Maresin1 was not statistically different from that of the caspase-1 inhibitor.Conclusion:Marl significantly inhibited the development of DSS-induced scorch death and attenuated DSS-induced colitis in mice,and is expected to be an effective drug candidate for the treatment of IBD.