Intestinal microbiota mining: a Th17/Treg cell perspective

The intestinal microbiota, which consists of a diverse community of gut-resident microbes, tightly coevolves with the mammalian immune system. Even at birth, the microbes inhabited in gut have begun to shape the development of immune system. In turn, the innate and adaptive immune responses constantly and dynamically maintain the intestinal homeostasis by keeping these resident microbes in their proper position. Mining the complex relationships between the intestinal microbiota and the host immunity will benefit to understanding of the mucosal immune system orchestration and developing of novel diagnostic/therapeutic approaches for treating intestinal inflammatory disorders such as infectious diseases in human. In recent years, new technologies, e.g., next-generation sequencing, gnotobiotic animal models, improved- anaerobic culture of bacteria, etc., have been developed and applied to the area of microbiota research. With the advantage of these technologies, we now achieve more in-depth understanding of the interplay between the mucosal immune system and the commensals, especially, of the induction of T helper 17 (Th17) and regulatory T (Treg) cells by different bacteria in human gut. In this review, I will highlight recent progresses, which are largely promoted by the technological advances, on how gut microbiota instructs the Th17/Treg cells development in the intestine.