Protective Effect Of Faecalibacterium Prausnitzii Supernatant On Experimental Colitis By Inhibiting TLR-4/NF-?B-signaling

Background and Aims:Faecalibacterium prausnitzii(F.prausnitzii),a symbiotic anaerobic 'bacterium in intestine,can maintain the health of intestine and provide nutrition for enterocytes.It is decreasing in IBD patients and has showed anti-inflammatory effects in experimental colitis mice.The present study is to observe the anti-inflammation effect of F.prausnitzii supernatant.in DSS-induced colitis and its effect on TLR-4/NF-?B signaling.Methods:Twenty-four C57BL/6 mice were randomly divided into the healthy control group,the colitis group and the F.prausnitzii supernatant traeted group.The healthy control group freely drank clean water.The colitis group and the F.prausnitzii supernatant group received 3.5%DSS in tap water for five days from the first day to the fifth day to induce colitis,F.prausnitzii supernatant group was given a Lavage intervention from start to finish of the whole experiment.The weight loss,colon length and the histopathological damage in colon issue was observed.PCR was carried out to determine the mRNA levels of TLR4 and p-NK-KB in colon.An immunohistochemical assay was applied to examine p-NK-KB protein expression in colon tissues.Level of TNF-?,IL-6 and COX-2 in serum was detected by ELISA.Results:Compared to the healthy control group,the colitis group showed more weight loss(p<0.01),colon shortening(p<0.05),and higher histopathological score(p<0.001);In F.prausnitzii supernatant treatment group,the weight loss(p<0.05),colon shortening(p<0.05)and the histopathological score(p<0.01)were all improved comparing to colitis group.Compared with the healthy control group,the level of TLR4 mRNA in colitis group was increasing(p<0.05),and p-NF-kB was increasing both in mRNA(p<0.05)and protein levels(p<0.001);In F.prausnitzii supernatant treatment group,the expression of TLR4 mRNA level(p<0.01)and protein levels(p<0.001)of p-NF-kB were decreased than that of colitis group,and p-NF-kB mRNA was decreased but there was no statistical differences comparing to colitis group.The colitis group was observed a higher levels of TNF-a(p<0.001),IL-6(p<0.01)and COX-2(p<0.05)in serum than that of the healthy group.And the level of TNF-a,IL-6 and COX-2 in.prausnitzii supernatant group was lower that that of colitis group(p<0.05).Conclusions:The present study reveals that F.prausnitzii supernatant has an obvious anti-inflammation in experimental colitis and its mechanism may be related to inhibiting TLR-4/NF-?B signaling,downregulating the expression of inflammatory cytokines and inflammatory mediators.