The impact of altered intestinal microbiota on intestinal immune function after acute exhaustive exercise in mice.

Purpose: Long-term training or intense exercise alters gut microbiota. This study aimed to determine the effects of microbiota on colonic permeability and immune function in mice subjected to acute exhaustive exercise.

Methods: C57BL/6 mice were randomly divided into the blank control (C), no exercise experience (NE), under a training protocol (E), phosphate-buffered saline (PBS) transplantation (PT), and fecal microbiota transplantation (FMT) groups. The E group underwent 14 weeks of moderate intensity training. At the end of the 14th week, fecal suspensions were prepared from mice in Group E and transplanted into Group FMT via enema, while Group PT received PBS enemas twice daily for 7 days. Prior to transplantation, both Groups PT and FMT were gavaged with antibiotics for 7 days, followed by 3 days of polyethylene glycol bowel cleansing. The C group was euthanized after a rest period, and the other groups were euthanized after acute exhaustive exercise. Colonic zonulin, occludin, ZO-1, CD14, TLR-4, MD-2, and TNF-α protein levels were detected via western blot, and enzyme-linked immunosorbent assays were used to detect serum LPS, IL-6, and colonic sIgA.

Results: Colonic zonulin protein expression was significantly higher (P < 0.01) and occludin and ZO-1 expression levels were significantly lower in the NE, PT, and FMT groups compared with the C group (P < 0.01). ZO-1 was significantly higher in the FMT group compared with the PT group (P < 0.05). Colonic MD-2, TLR-4, and CD14 expression levels were significantly lower in the FMT group compared with the PT group (P < 0.01, P < 0.05, and P < 0.05, respectively). Serum LPS and IL-6 expression levels were significantly lower in the FMT group compared with the PT group (P < 0.01). Colonic sIgA levels were significantly lower in the NE, E, PT, and FMT groups compared with the C group (P < 0.01), and levels in the FMT group were significantly higher than the levels in the PT group (P < 0.01).

Conclusion: Fecal microbiota transplantation attenuated the increased intestinal permeability, enhanced intestinal immune function, and reduced systemic inflammation induced by acute exhaustive exercise in mice without prior exercise experience.