The gut microbiota and immune-regulation: the fate of health and disease

T he gut microbiota is relevant to many diseases due to its direct impact on the development and maintenance of the immune system. Moreover, both the gut microbiota and the immune system are intimately related to many other physiological processes such as metabolism and behavior, as well as the digestive, respiratory and nervous systems. The amount of information gained in the last 5 years signifies the gut microbiota now as another important organ in our body. With diseases such as obesity, stroke, cancer, depression and autism increasing in prevalence, the debate centres upon whether many diseases have a gut origin. The interplay between the intestinal immune system, the epithelial barrier and the bacteria that resides within, is fundamental to maintaining a healthy gut homeostasis and determining the fate of health and disease. The host genetics and many environmental factors such as diet, early exposition to antibiotics, stress, drugs and many pollutants contribute to altering the balance of good and bad bacteria (dysbiosis) in the gut, subsequently compromising the gut permeability, often called 'Leaky gut'. Many inflammatory diseases are collectively being pinned on having a gut wall that allows toxins and autoimmune triggers to escape from the intestinal lumen leading to health problems. In this Special Feature of Clinical & Translational Immunology, we share our insights into the interplay between environmental factors, gut microbiota and metabolites, and their effects on human development, inflammation, infection, obesity, diabetes and chronic kidney disease. Likewise, we briefly discuss the challenges and opportunities in gut microbiota research and how novel therapeutic strategies targeting the gut microbiota will be beneficial for humans. The trillions of microbes that reside in our body and particularly in our gastrointestinal tract, together with our genome, constitute a complex dialogue. Vieira et al. 1 explain how the gut microbiota develops from birth and their interactions with the host become critical for the formation of a healthy or a disease-promoting microbiota. This review exposes the relevance of maternal diet and breastfeeding on gut microbiota modulation from early to late stages of life and the use of prebiotic, probiotic and postbiotic treatment, and fecal microbiota transplantation. The intense enthusiasm for research into the gut microbiota over the past decade has resulted in a deeper understanding into how the bacterial alteration of dietary components may have critical roles in host health and disease. Our diet is one of the main environmental factors that can dramatically …