The interplay between host immune cells and gut microbiota in chronic inflammatory diseases

Many benefits provided by the gut microbiota to the host rely on its intricate interactions with host cells. Perturbations of the gut microbiota, termed gut dysbiosis, affect the interplay between the gut microbiota and host cells, resulting in dysregulation of inflammation that contributes to the pathogenesis of chronic inflammatory diseases, including inflammatory bowel disease, multiple sclerosis, allergic asthma and rheumatoid arthritis. In this review, we provide an overview of how gut bacteria modulates host metabolic and immune functions, summarize studies that examined the roles of gut dysbiosis in chronic inflammatory diseases, and finally discuss measures to correct gut dysbiosis as potential therapeutics for chronic inflammatory diseases. Improved understanding of interactions between gut microbes and the immune system may inform therapies for chronic inflammatory diseases. Naturally occuring microbe populations in the gut, including bacteria and viruses, maintain a symbiosis with host cells that is crucial to the healthy functioning of the body. Imbalances in these populations affect the immune system and our ability to resist infections. Gabriel Núñez at the University of Michigan, USA, and co-workers reviewed research into the roles of gut microbes and how they interact with the immune system. The team highlight the vital role of bacterial enzymes in digesting food and producing nutrients, and examine how alterations in microbe populations are linked to the development of diseases, including bowel disorders, rheumatoid arthritis and multiple sclerosis. Enhanced understanding of how host cells and gut microbes interact could inform future treatments.