RESUMO
Background and Aims: Vitamin D (VD) plays an important role not only in mineral balance and skeletal maintenance but also in immune modulation. VD status was found correlated with the pathophysiology and severity of inflammatory bowel diseases and other autoimmune disorders. Epithelial barrier function is primarily regulated by the tight-junction (TJ) proteins. In this study, we try to establish an animal model by raising mice fed VD-deficient diet and to investigate the effects of VD-deficient diet on gut integrity and zonulin expression. Methods: Male C57BL/6 mice were administered either VD-deficient [VDD group, 25(OH)2D3 0 IU/per mouse] or VD-sufficient [VDS group, 25(OH)2D3 37.8 IU/per mouse] special diets for 7 weeks. Body weight and diet intake were recorded weekly. Serum VD levels were detected. After sacrifice, jejunum and colon specimens were collected. The villus length and crypt depth of the jejunum as well as mucosa thickness of the colon were measured. Various serum pro-inflammatory cytokines and intestinal TJ proteins were assessed. The serum level of zonulin and the mRNA expression of jejunum zonulin were also investigated. Results: We found that mice fed a VDD diet had a lower serum level of VD after 7 weeks (p < 0.001). VDD mice gained significant less weight (p = 0.022) and took a similar amount of diet (p = 0.398) when compared to mice raised on a VDS diet. Significantly decreased colon mucosa thickness was found in VDD mice compared with the VDS group (p = 0.022). A marked increase in serum pro-inflammatory cytokine levels was demonstrated in VDD mice. All relative levels of claudin (CLD)-1 (p = 0.007), CLD-3 (p < 0.001), CLD-7 (p < 0.001), and zonulin-1 (ZO-1, p = 0.038) protein expressions were significantly decreased in the VDD group when compared to the VDS group. A significant upregulation of mRNA expression of jejunum zonulin (p = 0.043) and elevated serum zonulin (p = 0.001) were found in the VDD group. Conclusions: We successfully demonstrated that VDD could lead to impaired barrier properties. We assume that sufficient VD could maintain intestinal epithelial integrity and prevent mucosal barrier dysfunction. VD supplementation may serve as part of a therapeutic strategy for human autoimmune and infectious diseases with intestinal barrier dysfunction (leaky gut) in the future. To our knowledge, this is the first study to demonstrate that VDD could lead to a significant upregulation in mRNA expression of the jejunum zonulin level and also a marked elevation of serum zonulin in a mouse model.
RESUMO
BACKGROUND AND AIM: Intestinal mucositis remained one of the most deleterious complications in cancer patients undergoing chemotherapy. 5-FU treatment was reported to affect the abundance of gut microbiota and cause mucositis, which might be ameliorated by probiotics. We investigate the potential changes of 5-FU treatment and the modulations of probiotics on gut microbiota in a mouse model. METHODS: Male BALB/c mice received either 5-FU or saline (S). They were separated and fed saline, Lactobacillus casei variety rhamnosus (Lcr) and Lactobacillus reuteri DSM 17938 (BG). Lcr and BG were simultaneously administered with 5-FU for 5 days. Stool specimens were collected for DNA extraction and pyrosequenced for bioinformatic analysis. RESULTS: Fecal microbial communities were obviously diverse. Bacteroides and Bacteroidaceae were the most abundant microbiota in FU.BG group while S24_7 was the most in S.S group. At phylum and class levels, abundances of Betaproteobacteria, Erysipelotrichi, Gammaproteobacteria, and Verrucomicrobia were significantly increased in the FU groups. Probiotics supplementation did increase the abundances of Enterobacteriales and Turicibacterales. We demonstrated that probiotics did modulate the abundance and diversity of gut microbiota. Bacterial motility proteins were found enriched and upregulated in the S.BG group. No mortality was noted. No bacterial translocation was found in spleen and blood among the six groups. CONCLUSION: Gut microbiota of mice undergoing chemotherapy exhibited a distinct disruption in bacterial composition. Probiotic did modulate the abundance and diversity of gut microbiota. This is the first study to analyze the effects and safety of Lactobacillus strains on 5-FU-induced mucositis systematically and assess changes in the intestinal microbiota after probiotic intervention.
