title: Mechanisms of probiotic action: Implications for therapeutic applications in inflammatory bowel diseases.
abstract: Probiotics are defined as nonpathogenic living microorganisms, including some commensal bacterial flora, which have beneficial effects on host health and disease prevention and/or treatment. Clinical trials have shown beneficial effects of probiotics on several human diseases, such as inflammatory bowel diseases (IBDs), which are among the most-studied diseases testing probiotics as a potential therapy. However, a significant question regarding clinical use of probiotics is the mechanism underlying the wide range of actions. Studies discussed in this review suggest 3 distinct cellular and molecular mechanisms for probiotic regulation in IBD therapy: 1) Probiotics block pathogenic bacterial effects by producing bactericidal substances and competing with pathogens and toxins for adherence to the intestinal epithelium; 2) Probiotics regulate immune responses by enhancing the innate immunity and modulating pathogen-induced inflammation via toll-like receptor-regulated signaling pathways; and 3) Probiotics regulate intestinal epithelial homeostasis by promoting intestinal epithelial cell survival, enhancing barrier function, and stimulating protective responses. Probiotics modulate host cell signaling pathways, including Akt, mitogen-activated protein kinases, and nuclear factor-kappaB to mediate these intestinal epithelial functions. It is hoped that developing a mechanistic understanding of probiotic action will provide the rationale to support the development of new hypothesis-driven studies to define the clinical efficacy in preventive, adjunctive, or alternative treatments for IBD.
authors.affiliation: Department of Pediatrics, Division of Gastroenterology, Hepatology & Nutrition, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0696, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Vanderpool
authors.forename: Fang
authors.initials: F
authors.lastname: Yan
authors.forename: D Brent
authors.initials: DB
authors.lastname: Polk
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000517:prevention & control*; D004847:Epithelial Cells / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D018928:Immunity, Mucosal / Q000502:physiology*; D015212:Inflammatory Bowel Diseases / Q000276:immunology* / Q000473:pathology / Q000628:therapy*; D007413:Intestinal Mucosa / Q000276:immunology / Q000382:microbiology; D007422:Intestines / Q000276:immunology / Q000382:microbiology; D008297:Male; D019936:Probiotics / Q000627:therapeutic use*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome