Intestinal Microbiota as a Host Defense Mechanism to Infectious Threats

Frontiers in Microbiology

卷:9

Diana Gabriela Iacob²  Simona Iacob²  Luminita Monica Luminos² 

[1] Department of Infectious Diseases, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania;

[2] National Institute of Infectious Diseases “Prof. Dr. Matei Bals”, Bucharest, Romania;

关键词: intestinal microbiota;    infection;    commensal flora;    bacterial enteropathogens;    colonization resistance;    mucosal immunity;   

DOI  :  10.3389/fmicb.2018.03328

来源: DOAJ

【 摘 要 】

The intestinal microbiota is a complex microbial community, with diverse and stable populations hosted by the gastrointestinal tract since birth. This ecosystem holds multiple anti-infectious, anti-inflammatory, and immune modulating roles decisive for intestinal homeostasis. Among these, colonization resistance refers to the dynamic antagonistic interactions between commensals and pathogenic flora. Hence, gut bacteria compete for the same intestinal niches and substrates, while also releasing antimicrobial substances such as bacteriocines and changing the environmental conditions. Short chain fatty acids (SCFAs) generated in anaerobic conditions prompt epigenetic regulatory mechanisms that favor a tolerogenic immune response. In addition, the commensal flora is involved in the synthesis of bactericidal products, namely secondary biliary acids or antimicrobial peptides (AMPs) such as cathellicidin-LL37, an immunomodulatory, antimicrobial, and wound healing peptide. Gut microbiota is protected through symbiotic relations with the hosting organism and by quorum sensing, a specific cell-to-cell communication system. Any alterations of these relationships favor the uncontrollable multiplication of the resident pathobionts or external entero-pathogens, prompting systemic translocations, inflammatory reactions, or exacerbations of bacterial virulence mechanisms (T6SS, T3SS) and ultimately lead to gastrointestinal or systemic infections. The article describes the metabolic and immunological mechanisms through which the intestinal microbiota is both an ally of the organism against enteric pathogens and an enemy that favors the development of infections.

【 授权许可】

Unknown