Blocking MyD88 signaling with MyD88 inhibitor prevents colitis-associated colorectal cancer development by maintaining colonic microbiota homeostasis

Dextran from human feces-derived Weissella cibaria facilitates intestinal mucosal barrier function by modulating gut bacteria and propionate levels

The disruption of the intestinal mucosal barrier is strongly associated with the onset of various diseases, including inflammatory bowel disease. Exopolysaccharides (EPS) support the functionality of the intestinal barrier. Weissella Cibaria (W. cibaria), belonging to the lactic acid bacteria, exhibits a significant capacity for EPS production. However, the specific mechanisms by which the EPS produced by W. cibaria confers intestinal barrier protection remain unexplored. Here, we characterized the polysaccharide, EPS-2, produced by W. cibaria isolated from the feces of healthy infants. EPS-2 was a novel dextran composed of α-(1 → 6) and α-(1 → 3,6) glycosidic linkages with a molecular weight of 845 kDa. EPS-2 alleviates intestinal mucosal barrier dysfunction in a mouse model of colitis, via a mechanism specifically reliant on the gut microbiota and their metabolic products, which is different from the well-known direct protective effects of other EPS on the intestinal barrier. EPS-2 reversed colitis-induced reductions in Muribaculaceae and propionate levels, thereby enhancing colonic goblet cell function and mucin content. Additionally, EPS-2 decreased the number of LPS-producing bacteria, such as Escherichia_Shigella. EPS-2 alleviated dextran sulfate sodium-induced intestinal inflammation and barrier damage. Therefore, EPS-2 shows promise as a postbiotic treatment for diseases associated with intestinal barrier dysfunction.

Pregnancy-induced changes in the toll-like receptor pathway in the ovine duodenum

Toll-like receptor (TLR) signaling plays a key role in the intestinal innate and adaptive immune responses, and pregnancy has effects on intestinal length and villus height. Nevertheless, it is unclear if early pregnancy modulates the expression of TLR members in the duodenum of ewes. In this study, ovine duodenums were obtained at day 16 of the estrous cycle (N16), and days 13, 16, and 25 of gestation (P13, P16, and P25) from ewes, and mRNA and protein expression of TLR members were analyzed. The results showed that early pregnancy increased the expression of TLR3, TLR5, and TRAF6, but did not influence TLR4 expression. In addition, there were increases in expression of TLR2, MyD88, and IRAK1 at P13 and P16, or only at P16 compared to N16 and P25. In summary, these data suggest that early pregnancy modulates the TLR signal pathway in the maternal duodenum, which may be related to the immunoregulation and adaptation of the maternal duodenum in the ovine.

MyD88 Signaling Accompanied by Microbiota Changes Supports Urinary Bladder Carcinogenesis

Urinary bladder cancer (BC) inflicts a significant impairment of life quality and poses a high mortality risk. Schistosoma haematobium infection can cause BC, and the urinary microbiota of BC patients differs from healthy controls. Importantly, intravesical instillation of the bacterium Bacillus Calmette-Guerin stands as the foremost therapy for non-muscle invasive BC. Hence, studying the receptors and signaling molecules orchestrating bacterial recognition and the cellular response in the context of BC is of paramount importance. Thus, we challenged Toll-like receptor 4 (Tlr4) and myeloid differentiation factor 88 (Myd88) knock-out (KO) mice with N-butyl-N-(4-hydroxylbutyl)-nitrosamine (BBN), a well-known urinary bladder carcinogen. Gut microbiota, gene expression, and urinary bladder pathology were followed. Acute exposure to BBN did not reveal a difference in bladder pathology despite differences in the animal's ability to recognize and react to bacteria. However, chronic treatment resulted in reduced cancer invasiveness among Myd88KO mice while the absence of functional Tlr4 did not influence BC development or progression. These differences correlate with a heightened abundance of the Faecalibaculum genus and the lowest microbial diversity observed among Myd88KO mice. The presented data underscore the important role of microbiota composition and MyD88-mediated signaling during bladder carcinogenesis.