title: The role of intestinal microbiota and the immune system.
abstract: BACKGROUND
  The human gut is an ecosystem consisting of a great number of commensal bacteria living in symbiosis with the host. Several data confirm that gut microbiota is engaged in a dynamic interaction with the intestinal innate and adaptive immune system, affecting different aspects of its development and function.
  
  
  OBJECTIVE
  To review the immunological functions of gut microbiota and improve knowledge of its therapeutic implications for several intestinal and extra-intestinal diseases associated to dysregulation of the immune system.
  
  
  METHODS
  Significant articles were identified by literature search and selected based on content, including atopic diseases, inflammatory bowel diseases and treatment of these conditions with probiotics.
  
  
  RESULTS
  Accumulating evidence indicates that intestinal microflora has protective, metabolic, trophic and immunological functions and is able to establish a "cross-talk" with the immune component of mucosal immunity, comprising cellular and soluble elements. When one or more steps in this fine interaction fail, autoimmune or auto-inflammatory diseases may occur. Furthermore, it results from the data that probiotics, used for the treatment of the diseases caused by the dysregulation of the immune system, can have a beneficial effect by different mechanisms.
  
  
  CONCLUSIONS
  Gut microbiota interacts with both innate and adaptive immune system, playing a pivotal role in maintenance and disruption of gut immune quiescence. A cross talk between the mucosal immune system and endogenous microflora favours a mutual growth, survival and inflammatory control of the intestinal ecosystem. Based on these evidences, probiotics can be used as an ecological therapy in the treatment of immune diseases.
authors: Department of Internal Medicine, School of Medicine, Catholic University of the Sacred Heart, Gemelli Hospital, Rome, Italy. flaminia.purchiaroni@hotmail.it
authors: F
authors: F
authors: Purchiaroni
authors: A
authors: A
authors: Tortora
authors: M
authors: M
authors: Gabrielli
authors: F
authors: F
authors: Bertucci
authors: G
authors: G
authors: Gigante
authors: G
authors: G
authors: Ianiro
authors: V
authors: V
authors: Ojetti
authors: E
authors: E
authors: Scarpellini
authors: A
authors: A
authors: Gasbarrini
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology; D005767:Gastrointestinal Diseases / Q000276:immunology / Q000382:microbiology / Q000628:therapy; D006801:Humans; D007154:Immune System Diseases / Q000382:microbiology / Q000503:physiopathology / Q000628:therapy*; D007113:Immunity, Innate / Q000276:immunology; D018928:Immunity, Mucosal / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology / Q000382:microbiology; D007422:Intestines / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology; D019936:Probiotics / Q000627:therapeutic use*