The microbiota of the gastrointestinal tract: what do we know?
The review deals with modern understanding of the role of human microbiota in the prevention of and protection from immunity-mediated (atopic) diseases. At present, a great deal of evidence have been obtained that the microbiota of the intestinal biotope plays a key role in the pathogenesis of many diseases, including allergy. The article discusses modern methods of diagnosing microbiota and its metabolic activity (16S rRNA sequencing, metabolomic and proteomic methods). Characteristics of a normal gut microbiota are given (interindividual variability, temporal variability, functional redundancy, functional stability). Based on available literature evidence, we analysed the results of studies confirming the impact of environmental factors, delivery, breastfeeding, antibiotic therapy on the formation of early-life microbiota and their correlation with the risk for developing allergy. The impact of microorganisms on the proinflammatory or anti-inflammatory immune response of the respiratory tract has been investigated from the positions of the «gut-lung» axis interactions (polarization of the immune response). The review discusses the results of randomized studies and meta-analyses of using probiotics in allergic patients. The effectiveness of administering probiotic cultures and the main aspects of their molecular mechanisms of action have been shown.