Although dietary fiber treatment alters the gut microbiota and its metabolite production, it is unclear whether or not exercise habits can have a supplemental effect on changes in gut microbiota in dietary fiber-treated mice. To clarify the supplemental effect of voluntary exercise on gut microbiota in partially hydrolyzed guar gum (PHGG), which is a soluble dietary fiber, treated mice under high-fat diet (HFD) feeding, 4-week-old male C57BL/6J mice (n = 80) were randomly divided into two dietary groups: the control-diet (CD) and HFD. Then, each dietary group was treated with or without PHGG, and with or without wheel running. After the experimental period, measurement of maximal oxygen consumption, a glucose tolerance test and fecal materials collection for analysis of gut microbiota were carried out. Voluntary exercise load in PHGG treatment under HFD feeding showed the supplemental effect of exercise on obesity (p < 0.01) and glucose tolerance (p < 0.01). Additionally, in both CD and HFD groups, voluntary exercise accelerated the decrease in the Firmicutes/Bacteroidetes ratio in mice fed with PHGG (p < 0.01). These findings suggest that voluntary exercise might activate the prevention of obesity and insulin resistance more via change in gut microbiota in mice administrated with PHGG.

Macrophages migrate and invade into damaged muscle rapidly and are important for muscle repair and subsequent regeneration. The exact cellular and biological events that cause macrophage migration toward injured muscle are not completely understood. In this study, the effect of macrophage differentiation on the chemotactic capability to invade local damaged muscle was investigated using an in vitro model of muscle injury. We used C2C12 cell myoblasts and J774 cell macrophages, and the “killed-C2C12” cells were combined with live C2C12 cells as a partially damaged muscle model. The cultured J774 cells, with or without lipopolysaccharide (LPS), were treated with Ly294002 (Ly), which is an inhibitor of phosphoinositide 3-kinase (PI3K). In order to evaluate the polarization effect of LPS stimulation on J774 cells, expression of cell surface Toll-like receptor 4 (TLR4), CD11c and CCR2, and expression of F-actin intensity, were analyzed by flow cytometry. The real-time horizontal chemotaxis assay of J774 cells was tested using the TAXIScan device. The expressions of TLR4, CD11c, and F-actin intensity in LPS-treated cells were significantly higher than those in Ctrl cells. In LPS-treated cells, the chemotactic activity toward damaged muscle cells completely disappeared. Moreover, the reduced chemotaxis depended far more on directionality than velocity. However, Ly treatment reversed the reduced chemotactic activity of the LPS-treated cells. In addition, cell-adhesion and F-actin intensity, but not CCR2 expression, in LPS-treated cells, was significantly reduced by Ly treatment. Taken together, our results suggest that the PI3K/Akt activation state drives migration behavior towards damaged muscle cells.

Background: Cactus contains dietary fiber and minerals and is expected to have preventive effects against diabetes, arteriosclerosis, and other diseases. Additionally, cactus intake induces the production of short-chain fatty acids derived from the gut microbiota, which might influence immune functions. In this study, we examined the effects of a cactus (Nopalea cochenillifera: NC)-supplemented diet on lipopolysaccharide (LPS)-induced immune responses and intestinal barrier function. Methods: Male C3H/HeN mice were randomly divided into three groups—no fiber (NF), cellulose-containing fiber (Cellu), and cactus-added (NC) diets—for 6 weeks. The TNF-α and IL-10 responses to LPS, antibody titers, and intestinal barrier function, as well as the fecal microbiota, were analyzed. Results: The plasma TNF-α but not the IL-10 concentrations were significantly higher in the NC group than in the NF and Cellu groups. Furthermore, the plasma IgG antibody titers were significantly higher in the NC group than in the other groups. The NC group showed higher mucin content and IgA antibody titers in their feces compared with the Cellu group. The succinate and lactate contents, which induce a reduction in TNF-α secretion by macrophages, in the cecum of the NC group were significantly lower than those in the Cellu and NF groups. In contrast, the butyrate content was significantly higher in the cecum of the NC group compared to that of the Cellu group, with a significantly higher relative abundance of butyrate-producing bacteria. Conclusions: Taken together, we found that cactus intake regulates innate and adaptive immune function via the gut microbiota in mice. Therefore, cactus supplementation might serve as a strategy to develop novel functional foods with dietary fiber.