Gut Microbiota in Health and Disease

Intestinal regulatory T (Treg) cells are critical to maintaining immune tolerance to dietary antigens and gut microbiota. This paper reviews several papers on this topic that were recently published by Japanese researchers. Specifically, Prof. K. Honda and his group have found that commensal microbiota capable of metabolizing butyrate induces the differentiation of colonic Treg cells. In a separate work, Prof. Y. Yokoyama and his group used a novel, culture-independent analytical method (the Yakult Intestinal Flora-Scan) for detection of bacteria in the bloodstream. Their work revealed that bacteremia in invasive surgery patients was ameliorated by synbiotic supplementation; similar results were reported in pediatric surgical cases by Dr. T. Okazaki and his group. This cutting-edge method may lead to the evolution of an altered disease concept; an example of this change is provided by the description of bacteremia in patients with type 2 diabetes, as reported by Dr. J. Sato and her group. In a similar work, Prof. Y. Yamashiro and his group found that infants born by cesarean (C)-section, who typically have gut dysbiosis, exhibit higher carriage of toxigenic Clostridium perfringens. The finding suggests that C-section-born infants may serve as a potential reservoir of this opportunistic pathogen. Another separate work by the laboratory of Dr. K. Yamashiro has revealed that gut dysbiosis is associated with altered metabolism and systemic inflammation in patients with ischemic stroke. These papers are consistent with a study by Prof. N. Sudo and his group, who have made significant progress in research on interaction among the microbiota, gut, and brain.