Clinical evidence for immunomodulatory effects of probiotic bacteria.
Close, tightly orchestrated interactions between the intestinal epithelium and the mucosa-associated immune system are critical for normal intestinal absorptive and immunological functions. Recent data indicate that commensal intestinal microbiota represents a major modulator of intestinal homeostasis. This review analyses the process of intestinal colonisation and the interaction of microbiota with the intestinal epithelium and mucosal immune system, with special reference to the first years of extrauterine life. Dysregulation of the symbiotic interaction between intestinal microbiota and the mucosa may result in a pathological condition with potential clinical repercussions. Based on the concept that there is a beneficial and symbiotic relation between the host and endogenous microbiota, strategies aimed at directly modulating intestinal microbiota with regard to disease prevention or treatment have been developed. One strategy involves administering viable probiotic bacteria. Clinical evidence for the beneficial effect of probiotics in the prevention and/or treatment of necrotising enterocolitis, infectious and antibiotic-associated diarrhoea, allergic diseases, and inflammatory bowel disorders is reviewed herein.
Ruemmele FM, Bier D, Marteau P, Rechkemmer G, Bourdet-Sicard R, Walker WA, Goulet O. Clinical evidence for immunomodulatory effects of probiotic bacteria. J Pediatr Gastroenterol Nutr. 2009 Feb;48(2):126-41. View Abstract
The gut microbiota shapes intestinal immune responses during health and disease
Abstract: Immunological dysregulation is the cause of many non-infectious human diseases such as autoimmunity, allergy and cancer. The gastrointestinal tract is the primary site of interaction between the host immune system and microorganisms, both symbiotic and pathogenic. In this Review the authors discuss findings indicating that developmental aspects of the adaptive immune system are influenced by bacterial colonisation of the gut. They also highlight the molecular pathways that mediate host-symbiont interactions that regulate proper immune function. Finally, they present recent evidence to support that disturbances in the bacterial microbiota result in dysregulation of adaptive immune cells, and this may underlie disorders such as inflammatory bowel disease. This raises the possibility that the mammalian immune system, which seems to be designed to control microorganisms, is in fact controlled by microorganisms.
The authors conclude: On the basis of clinical, epidemiological and immunological evidence, it seems possible that changes in the intestinal microbiota may be an essential factor in the incidence of numerous inflammatory disorders. It is conceivable that the absence of beneficial microorganisms (owing to dysbiosis) that promote the appropriate development of the immune system leads to the induction of inflammatory responses and immune-mediated disease. The recent identification of symbiotic bacteria with potent anti-inflammatory properties, and their correlative absence during disease, suggests that certain aspects of human health may depend on the status of the microbiota. The medical and social reconsideration of the microbial world may have profound consequences for the health of our future generations.
Round JL, Mazmanian SK., The gut microbiota shapes intestinal immune responses during health and disease. Nat Rev Immunol. 2009 May;9(5):313-23. View Abstract
