title: The Role of Microbiota on the Gut Immunology.
abstract: OBJECTIVE
  The human gut contains >100 trillion microbes. This microbiota plays a crucial role in the gut homeostasis. Importantly, the microbiota contributes to the development and regulation of the gut immune system. Dysbiosis of the gut microbiota could also cause several intestinal and extraintestinal diseases. Many experimental studies help us to understand the complex interplay between the host and microbiota.
  
  
  METHODS
  This review presents our current understanding of the mucosal immune system and the role of gut microbiota for the development and functionality of the mucosal immunity, with a particular focus on gut-associated lymphoid tissues, mucosal barrier, TH17 cells, regulatory T cells, innate lymphoid cells, dendritic cells, and IgA-producing B cells and plasma cells.
  
  
  RESULTS
  Comparative studies using germ-free and conventionally-raised animals reveal that the presence of microbiota is important for the development and regulation of innate and adaptive immune systems. The host-microbial symbiosis seems necessary for gut homeostasis. However, the precise mechanisms by which microbiota contributes to development and functionality of the immune system remain to be elucidated.
  
  
  CONCLUSIONS
  Understanding the complex interplay between the host and microbiota and further investigation of the host-microbiota relationship could provide us the insight into the therapeutic and/or preventive strategy for the disorders related to dysbiosis of the gut microbiota.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yang Won
authors.initials: YW
authors.lastname: Min
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. Electronic address: plrhee@skku.edu.
authors.forename: Poong-Lyul
authors.initials: PL
authors.lastname: Rhee
mesh_terms: D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D000069196:Gastrointestinal Microbiome / Q000276:immunology*; D006706:Homeostasis / Q000276:immunology; D006801:Humans; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000096:biosynthesis; D007413:Intestinal Mucosa / Q000276:immunology* / Q000382:microbiology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology
chemical_list: D007070:Immunoglobulin A
keywords: gut; immune system; microbiota; mucosal