Mechanism Of MMP-8 Regulating Intestinal Barrier In Colitis Mice Through NF-κB Signaling Pathway

BackgroundUlcerative colitis(Ulcerative colitis,UC)is still a chronic inflammatory intestinal disease,whose etiology is unclear.Clinically,UC patients often present with intermittent diarrhea,abdominal pain,and mucus,pus and blood as the main complaints.The influencing factors of UC include environmental factors,genetic factors,intestinal microecology,immune imbalance,etc.In the process of disease occurrence and development,intestinal mucosal barrier dysfunction is an important link.The intestinal mucosal barrier includes intestinal epithelial cells,tight junctions between cells,and mucus secreted by epithelial cells and goblet cells.Finding regulatory molecules that regulate the intestinal barrier,especially the tight junction structure of the intestinal epithelium,can provide new ideas for repairing intestinal barrier function and treating UC.The transcriptome sequencing results of our research group showed that compared with the normal group mice,the expression level of Matrix Metalloproteinase-8(MMP-8)in the enteritis group mice was significantly increased,suggesting that MMP-8 may play a role in the pathogenesis of UC.Certain role,bioinformatics analysis also suggested that it may be related to NFκB signaling pathway.Studies have shown that MMP-8 is related to the regulation of tight junction proteins in alveolar epithelial cells and blood-brain barrier cells,and some studies have suggested that MMP-8 regulates the tight junction function of blood-brain barrier epithelial cells through the NF-κB pathway.However,no studies have reported the regulatory role of MMP-8 on the intestinal epithelial barrier in UC.Therefore,whether MMP-8 can regulate the intestinal mucosal barrier function and the regulation mode in UC needs further study.ObjectiveTo explore whether MMP-8 regulates intestinal mucosal barrier function and its possible mechanism through NF-κB signaling pathway in colitis mice.Materials and Methods1.Six male C57BL/6J mice were randomly divided into normal control group and DSS model group.Transcriptome sequencing was performed to find differentially expressed genes in colitis mice;2.twenty-four male C57BL/6J mice were randomly divided into control group,model group,and DSS model group.Model+MMP-8 inhibitor(M8I)group,model+NF-κB inhibitor(BAY 11-7082)group,to explore the role of MMP-8 on the intestinal mucosal barrier and related mechanisms;3.Construction of human colorectal gland In the cancer cell(Ca-co2)monolayer cell inflammation model,in the case of using MMP-8,the cells were treated with MMP-8 inhibitors and NF-κB inhibitors to explore the mechanism of action of MMP-8 on the intestinal barrier.Results1.The results of transcriptome sequencing analysis indicated that the expression of MMP-8 was increased in colitis mice,and MMP-8 was related to NF-κB signaling pathway.2.In vivo studies have shown that compared with the model control group,blocking the MMP-8 or NF-κB pathway can reduce the degree of colitis inflammation in mice and increase the expression of tight junction proteins(Claudin1,Occludin,ZO-1).In addition,the intestinal epithelial mucosal structure of the mice colon was significantly improved,specifically manifested as less mucosal damage and more neatly arranged goblet cells.3.In vitro studies have shown that MMP-8 promotes the expression of inflammatory factors TNF-α and IL-1β and reduces the expression of tight junction proteins(Claudin-1,Occludin,ZO-1),which can be inhibited by MMP-8 inhibitors or NF-κB After treatment,the inflammation and intestinal barrier were alleviated,and the expression of tight junction proteins(Claudin-1,Occludin,ZO-1)increased.Conclusions1.The expression of MMP-8 increases in colitis mice;2.Blocking MMP-8 or NF-κB pathway can inhibit the protein expression of TNF-α and IL-1β,while tight junction proteins(Claudin-1,Occludin,ZO-1)Increased expression can reduce colonic mucosal inflammation and intestinal mucosal barrier damage;3.MMP-8 promotes inflammation and intestinal mucosal barrier dysfunction caused by colitis mice through the NF-κB signal pathway.