Exercise reduces the risk of inflammatory disease by modulating a variety of tissue and cell types, including those within the gastrointestinal tract. Recent data indicates that exercise can also alter the gut microbiota, but little is known as to whether these changes affect host function. Here, we use a germ-free (GF) animal model to test whether exercise-induced modifications in the gut microbiota can directly affect host responses to microbiota colonization and chemically-induced colitis. Donor mice (n = 19) received access to a running wheel (n = 10) or remained without access (n = 9) for a period of six weeks. After euthanasia, cecal contents were pooled by activity treatment and transplanted into two separate cohorts of GF mice. Two experiments were then conducted. First, mice were euthanized five weeks after the microbiota transplant and tissues were collected for analysis. A second cohort of GF mice were colonized by donor microbiotas for four weeks before dextran-sodium-sulfate was administered to induce acute colitis, after which mice were euthanized for tissue analysis. We observed that microbial transplants from donor (exercised or control) mice led to differences in microbiota β-diversity, metabolite profiles, colon inflammation, and body mass in recipient mice five weeks after colonization. We also demonstrate that colonization of mice with a gut microbiota from exercise-trained mice led to an attenuated response to chemical colitis, evidenced by reduced colon shortening, attenuated mucus depletion and augmented expression of cytokines involved in tissue regeneration. Exercise-induced modifications in the gut microbiota can mediate host-microbial interactions with potentially beneficial outcomes for the host.

IntroductionDietary changes have been shown to significantly alter the composition and metabolic function of the gut microbiota in both mice and humans; however, study of the effects of exercise alone on the gut microbiota and microbial metabolites has been limited to mice. Short chain fatty acids (SCFAs) are bacterial metabolites with numerous downstream effects on the host, influencing satiety, inflammation, and adiposity. Here, we characterized the effects of an aerobic exercise intervention on fecal SCFA output in lean and obese humans.MethodsPreviously sedentary but otherwise healthy adults (n=11 lean; n=4 obese) underwent a six week aerobic exercise intervention. Participants performed 3 exercise sessions per week on a bike and/or treadmill, starting with 30 min at 60% HRR and building up to 60 min at 75% HRR by week 6. Fecal samples were collected before and after the intervention, preceded by a 3‐day control diet. Approximately 0.1 g of fecal samples was immediately stabilized in metaphosphoric acid until SCFA analysis by gas chromatography/mass spectrometry (GC/MS).ResultsSix weeks of exercise caused a significant increase in the fecal concentration of butyrate, acetate, and propionate (p<0.01), among lean individuals. The changes in acetate and butyrate concentrations were strongly correlated to changes in lean mass as a result of training, an effect driven by the lean individuals (r=.633 p<0.029 and r=0.854, p<0.01, respectively). However, exercise training failed to increase fecal SCFA concentration in our small sample of obese individuals (p>0.05).ConclusionA 6‐week aerobic exercise intervention is sufficient to increase fecal SCFA concentrations in lean, adult humans. This effect was not observed in obese individuals, however, and thus suggests that exercise‐induced metabolic changes within the gut may be influenced by obesity status

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IntroductionExercise causes numerous physiological changes that may impact microbial communities at mucosal surfaces. Previously, our lab has shown that six weeks of aerobic exercise significantly alters the composition of the human gut microbiota. In the present study, we characterized the effects of an aerobic exercise on skin and oral microbiotas.MethodsPreviously sedentary but otherwise healthy adults (n= 10) were recruited to undergo a six‐week aerobic exercise intervention. Participants performed three exercise sessions per week on a bike or treadmill, starting with 30 min at 60% HRR and progressing to 60 min at 75% HRR by week six. Skin and oral swabs were collected at baseline and after cessation of exercise training. An additional skin swab was collected after the first exercise session to measure acute changes in skin microbiota. Skin swabs were moistened with sampling buffer before swabbing the antecubital fossa. Oral swabs were taken by swabbing the center of the tongue. DNA was isolated from samples and 16S rRNA gene sequencing was performed.ResultsSix weeks of chronic exercise caused a significant shift in the skin microbiota (unweighted PERMANOVA p = 0.017) that was not evident after a single acute exercise bout. Oral microbial communities were not significantly different from baseline after six weeks of chronic exercise training. For both skin and oral samples, there were no significant changes in alpha diversity or species evenness with exercise, and no significant differences in relative abundance on the genus level.ConclusionA six‐week aerobic exercise intervention is sufficient to alter the skin microbiota, but not the oral microbiota. This study should be replicated with a larger sample size to confirm these preliminary findings.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.