Talking microbes: When gut bacteria interact with diet and host organs

Abstract

Obesity and diabetes have reached epidemic proportions. Evidence suggests that besides dietary habits and physical activity, other environmental factors, such as gut microbes, are recognized as additional partners implicated in the control of energy homeostasis. Studies on the human gut microbiota have shown that the general population can be stratified on the sole basis of three dominant bacteria (i.e., the concept of enterotypes), while some others have suggested categorizing the population according to their microbiome gene richness. Both aspects have been strengthened by recent studies investigating the impact of nutrients (e.g., dietary fibers, fat feeding) and dietary habits (i.e., vegans versus omnivores) of different populations. Using preclinical models, quite a few novel mechanisms have been proposed in these gut microbiota-host interactions, including the role of novel bacteria, the regulation of antimicrobial peptide production, the maintenance of the gut barrier function and intestinal innate immunity. In this review, we discuss several of the aforementioned aspects. Nonetheless, determining the overall mechanisms by which microbes dialogue with host cells will require further investigations before anticipating the development of next-generation nutritional interventions using prebiotics, probiotics, synbiotics, or even specific nutrients for promoting health benefits.

Keywords: Diabetes; Energy metabolism; Gut microbiota; Innate immunity; Obesity.

Figure 1

Crosstalks between host and microbes: impact on metabolism. The intestinal barrier is composed of different factors such as epithelial cells, a mucus layer, and antimicrobial peptides produced by host cells. The inner mucus layer and the antimicrobial peptides help to segregate microbes at distance of the epithelium. Moreover, specific microbes such as Akkermansia muciniphila have been shown to improve gut barrier function and mucus layer thickness. During high‐fat diet feeding and low fibers intake, the gut microbiota composition is different, inflammatory components translocate into the blood via the altered gut barrier function.