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.

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.Additional supporting information may be found online in the Supporting Information section at the end of the article. Data S1. Supporting information.

Background Intestinal mucositis remained one of the most deleterious side effects in cancer patients undergoing chemotherapy. 5-Fluorouracil (5-FU) treatment was reported to affect the abundance of gut microbiota. In this study, we hypothesize that the probiotics could preserve gut ecology, ameliorate inflammation and protect epithelium by maintaining the tight junction integrity via immune modulations of enterocytes and intestinal stem cells. Our aim is to characterize these changes and to investigate the immune modulation effects and safety of probiotic via a 5-FU-induced intestinal mucositis mouse model.Methods 5-FU-injected BALB/c mice were used. They were either orally administrated saline or probiotic suspension of Lactobacillus casei variety rhamnosus (Lcr35). Diarrhea score, serum pronflammatory cytokines, intestinal histology and T-cells subtypes were assessed. Immunostaining analysis for intestinal stem cells CD44 and Ki67 proliferation were processed. Samples of blood and internal organs were investigated for bacteria translocation.Results Diarrhea was attenuated significantly after oral Lcr35 administration. Serum pro-inflammatory cytokines were significantly increased in 5-FU group and were reversed by Lcr35. There was a tremendous rise of CD3+/CD8+ count in the 5-FU group. The CD8+ count was reversed in the 5-FU+Lcr35 group. 5-FU caused a significant decrease of CD3+CD4+/CD3+CD8+ ratio and was reversed by Lcr35. 5-FU significantly stimulated the expression of CD44 stem cells and was restored by Lcr35. We also found 5-FU could increase the number of Ki67 proliferative cells. No bacterial translocation was found in this study. ConclusionsOur results showed 5-FU caused intestinal inflammation via Th1 and Th17 responses. 5-FU could stimulate stem cells and proliferation cells in a mouse model. We demonstrated chemotherapy could decrease immune competence. Probiotics were shown to modulate immune response. This is the first study to analyze the immune modulation effects and safety of Lactobacillus strains on enterocytes and intestinal stem cells in a 5-FU-induced mucositis mouse model. The model therefore seems well suited to study the effects of different probiotics on chemotherapy-induced mucositis, prior to performing clinical human studies.3