The gastrointestinal tract contains trillions of microbes (collectively known as the gut microbiota) that play essential roles in host physiology and health. Studies from our group and others have demonstrated that exercise independently alters the composition and functional capacity of the gut microbiota. Here, we review what is known about the gut microbiota, how it is studied, and how it is influenced by exercise training and discuss the potential mechanisms and implications for human health and disease.

Exercise and the Gut Microbiome: A Review of the Evidence, Potential Mechanisms, and Implications for Human Health

Objective High-fat diet (HFD)-induced metabolic disorders can lead to impaired sperm production. We aim to investigate if HFD-induced gut microbiota dysbiosis can functionally influence spermatogenesis and sperm motility. Design Faecal microbes derived from the HFD-fed or normal diet (ND)-fed male mice were transplanted to the mice maintained on ND. The gut microbes, sperm count and motility were analysed. Human faecal/semen/blood samples were collected to assess microbiota, sperm quality and endotoxin. Results Transplantation of the HFD gut microbes into the ND-maintained (HFD-FMT) mice resulted in a significant decrease in spermatogenesis and sperm motility, whereas similar transplantation with the microbes from the ND-fed mice failed to do so. Analysis of the microbiota showed a profound increase in genus Bacteroides and Prevotella, both of which likely contributed to the metabolic endotoxaemia in the HFD-FMT mice. Interestingly, the gut microbes from clinical subjects revealed a strong negative correlation between the abundance of Bacteroides-Prevotella and sperm motility, and a positive correlation between blood endotoxin and Bacteroides abundance. Transplantation with HFD microbes also led to intestinal infiltration of T cells and macrophages as well as a significant increase of pro-inflammatory cytokines in the epididymis, suggesting that epididymal inflammation have likely contributed to the impairment of sperm motility. RNA-sequencing revealed significant reduction in the expression of those genes involved in gamete meiosis and testicular mitochondrial functions in the HFD-FMT mice. Conclusion We revealed an intimate linkage between HFD-induced microbiota dysbiosis and defect in spermatogenesis with elevated endotoxin, dysregulation of testicular gene expression and localised epididymal inflammation as the potential causes. Trial registration number NCT03634644.

https://gut.bmj.com/content/gutjnl/early/2020/01/02/gutjnl-2019-319127.full.pdf

Impairment of spermatogenesis and sperm motility by the high-fat diet-induced dysbiosis of gut microbes

Lifestyle is a well-known environmental factor that plays a major role in facilitating the development of metabolic syndrome or eventually exacerbating its consequences. Various lifestyle factors, especially changes in dietary habits, extreme temperatures, unusual light–dark cycles, substance abuse, and other stressful factors, are also established modifiers of the endocannabinoid system and its extended version, the endocannabinoidome. The endocannabinoidome is a complex lipid signaling system composed of a plethora (>100) of fatty acid-derived mediators and their receptors and anabolic and catabolic enzymes (>50 proteins) which are deeply involved in the control of energy metabolism and its pathological deviations. A strong link between the endocannabinoidome and another major player in metabolism and dysmetabolism, the gut microbiome, is also emerging. Here, we review several examples of how lifestyle modifications (westernized diets, lack or presence of certain nutritional factors, physical exercise, and the use of cannabis) can modulate the propensity to develop metabolic syndrome by modifying the crosstalk between the endocannabinoidome and the gut microbiome and, hence, how lifestyle interventions can provide new therapies against cardiometabolic risk by ensuring correct functioning of both these systems.

https://www.mdpi.com/2072-6643/11/8/1956/pdf

Lifestyle and Metabolic Syndrome: Contribution of the Endocannabinoidome.

Childhood obesity has reached epidemic levels, representing one of the most serious public health concerns associated with metabolic syndrome and non-alcoholic fatty liver disease (NAFLD). There is limited clinical experience concerning pediatric NAFLD patients, and thus the therapeutic options are scarce. The aim of this study was to evaluate the benefits of exercise on gut microbiota composition and functionality balance, and consequent effects on early obesity and NAFLD onset in an in vivo model. Juvenile (21-day-old) male Wistar rats fed a control diet or a high-fat diet (HFD) were subjected to a combined aerobic and resistance training protocol. Fecal microbiota was sequenced by an Illumina MiSeq system, and parameters related to metabolic syndrome, fecal metabolome, intestinal barrier integrity, bile acid metabolism and transport, and alteration of the gut-liver axis were measured. Exercise decreased HFD-induced body weight gain, metabolic syndrome and hepatic steatosis, as a result of its lipid metabolism modulatory capacity. Gut microbiota composition and functionality were substantially modified as a consequence of diet, age and exercise intervention. In addition, the training protocol increased Parabacteroides, Bacteroides and Flavobacterium genera, correlating with a beneficial metabolomic profile, whereas Blautia, Dysgonomonas and Porphyromonas showed an opposite pattern. Exercise effectively counteracted HFD-induced microbial imbalance, leading to intestinal barrier preservation, which, in turn, prevented deregulation of the gut-liver axis and improved bile acid homeostasis, determining the clinical outcomes of NAFLD. In conclusion, we provide scientific evidence highlighting the benefits of gut microbiota composition and functionality modulation by physical exercise protocols in the management of early obesity and NAFLD development.

/pdf/beneficial-effects-of-exercise-on-gut-microbiota-233zemtnxy.pdf

Beneficial effects of exercise on gut microbiota functionality and barrier integrity, and gut-liver crosstalk in an in vivo model of early obesity and non-alcoholic fatty liver disease.

Odoribacter splanchnicus, belonging to the order Bacteroidales, is a common, short-chain fatty acid producing member of the human intestinal microbiota. A decreased abundance of Odoribacter has been linked to different microbiota-associated diseases, such as non-alcoholic fatty liver disease, cystic fibrosis and inflammatory bowel disease (IBD). The type strain of O. splanchnicus has been genome-sequenced, but otherwise very little is known about this anaerobic bacterium. The species surfaces in many microbiota studies and, consequently, comprehension on its interactions with the host is needed. In this study, we isolated a novel strain of O. splanchnicus from a healthy fecal donor, identified it by genome sequencing and addressed its adhesive, epithelium reinforcing and immunoregulatory properties. Our results show that O. splanchnicus strain 57 is non-adherent to enterocytes or mucus, does not reinforce nor compromise Caco-2 monolayer integrity and most likely harbors penta-acylated, less endotoxic lipid A as part of its lipopolysaccharide (LPS) structure based on the lack of gene lpxM and in vitro results on low-level NF-κB activity. The studies by transmission electron microscopy revealed that O. splanchnicus produces outer membrane vesicles (OMV). O. splanchnicus cells, culture supernatant i.e., spent medium or OMVs did not induce interleukin-8 (IL-8) response in HT-29 enterocyte cells suggesting a very low proinflammatory capacity. On the contrary, the treatment of HT-29 cells with O. splanchnicus cells, spent medium or OMVs prior to exposure to Escherichia coli LPS elicited a significant decrease in IL-8 production as compared to E. coli LPS treatment alone. Moreover, O. splanchnicus spent supernatant induced IL-10 production by immune cells, suggesting anti-inflammatory activity. Our in vitro findings indicate that O. splanchnicus and its effector molecules transported in OMVs could potentially exert anti-inflammatory action in the gut epithelium. Taken together, O. splanchnicus seems to be a commensal with a primarily beneficial interaction with the host.

/pdf/novel-odoribacter-splanchnicus-strain-and-its-outer-membrane-4z9y9vuxr2.pdf

Novel Odoribacter splanchnicus Strain and Its Outer Membrane Vesicles Exert Immunoregulatory Effects in vitro

Diet and exercise are conventional methods for controlling body weight and are linked to alterations in gut microbiota. However, the associations of diet, exercise, and gut microbiota in the control of obesity remain largely unknown. In the present study, using 16S rRNA amplicon sequencing and fecal microbiota transplantation (FMT), normal fat diet (NFD), exercise and their combination resulted in improved metabolic profiles in comparison to sedentary lifestyle with high fat diet (HFD). Moreover, diet exerted more influence than exercise in shaping the gut microbiota. HFD-fed mice receiving FMT from NFD-exercised donors not only showed remarkably reduced food efficacy, but also mitigated metabolic profiles (p < 0.05). The transmissible beneficial effects of FMT were associated with bacterial genera Helicobacter, Odoribacter and AF12 and overrepresentation of oxidative phosphorylation and glycolysis genes. Our findings demonstrate that the beneficial effects of diet and exercise are transmissible via FMT, suggesting a potential therapeutic treatment for obesity.

/pdf/fecal-microbiota-transplantation-confers-beneficial-5bm1mdvuax.pdf

Fu Chou Cheng

Papers

Fecal microbiota transplantation confers beneficial metabolic effects of diet and exercise on diet-induced obese mice