| Background and Aims: In recent years, the role of inflammasome was researched entensively in the inflammatory and immunity diseases.NLRP3 (NACHT, LRR and PYD domains-containing protein 3) inflammasome was one of the most thorough study.NLRP3 inflammasome plays an important role in the development of experimental colitis. Faecalibacterium prausnitzii (F. prausnitzii) and its cultured supernatant have anti-inflammatory effect. The study was to explore the role of NLRP3 inflammasome in the process of the colitis in rat and the effects and mechanism of F. prausnitzii and its supernatant inhibited TNBS-induced colitis by regulating expression of NLRP3 inflammasome.Methods:Fifty Sprague-Dawley(SD) rat were divided into normal control group(N=10) and experimental group(N=40).Experimental group were treated with 100mg/kg 5%TNBS by enema to induce colitis; normal group treated with 0.9%Nacl instead in the same way. After 24 hours,the rats of experimental group was randomly divided into colitis PBS group(PBS group),colitis medium group(medium group),colitis F. prausnitzii group(FP group) and colitis F. prausnitzii supernatant group(supernatant group)(10 in each group) and were administered intragastrically with lml PBS, bacteria culture medium, live F.prausnitzii and the culture supernatant of F. prausnitzii once a day for seven days, respectively; normal group with PBS buffer in the same way. During the time,diet,fundamental state,feces and weight of rats were observed.The rats were killed at the eighth day. Appendix section of colon from the anus to the cecum was separated, faeces wiped,the length of the colon was measured; The colon tissue inflammation degree was detected by Macroscopical and Histological analysis; mRNA levels of NLRP3, ASC, caspase-1,IL-1β and IL-18 in r colon tissue of rat were detected by real time PCR; protein levels of NLRP3, ASC(Apoptosis-associated speck-like protein) and caspase-1 in colon tissue were measured through Western Blot; levels of IL-18 and IL-1β in plasma were found by ELISA(enzyme-linked immunosorbent assay).Result:In the process, diet and mental state in the experimental group were poorer compared with normal group. The weight and colon length of PBS group and medium group reduced significantly compared with normal group (P<0.05). The scores of fecal, Macroscopical and Histological analysis in experimental groups were higher than that of normal group, but those were lower in F. prausnitzii group and supernatant group than in PBS group and medium group (P<0.05). Protein levels and mRNA levels of NLRP3, ASC and caspase-1 in colon tissue were significantly higher in PBS group and medium group than those in normal group (P<0.05), F. prausnitzii group and supernatant group decressed those trend(P<0.05). Plasma level and tissue mRNA level of IL-1β rase highly in PBS group and medium group compared with normal group (P<0.05). The levels of above parameter in F. prausnitzii group and supernatant group had significantly lower than that in PBS group and medium group (P<0.05). However, plasma level and tissue mRNA level of IL-18 were significantly lower in PBS group and medium group than that of normal group (P<0.05),E prausnitzii group and supernatant group reduced these levels further. Effects of cultured supernatant on weight change, fecal score, mRNA levels of caspase 1, IL-1β and IL-18 and plasma levels of IL-1β are more obvious than those of F. prausnitzii.Conclusions:NLRP3 inflammasome participated in TNBS-induced colitis. Its downstream effector IL-1β played an inflammatory role, But IL-18 showed both anti-inflammatory and inflammatory effect in the process.F. prausnitzii and its cultured supernatant could elivate TNBS-induced colitis in rat by inhibiting the function of NLRP3 inflammasome, and probably it was the mechanism that the level of IL-1β was reduced. |
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