cải thiện tính toàn vẹn niêm mạc trực tiếp loại trừ tác nhân gây bệnh có thể gây tổn thương biểu mô hoặc bằng cách tăng cường tiết IgA (sIgA) sản xuất (có thể thông qua gây tiết TGF-b) và gây tiết các cytokine chống viêm, có thể phá vỡ vòng tròn luẩn quẩn nơi có tình trạng viêm làm tăng tính thấm của ruột | The Infant Intestinal Microbiota in Allergy 195 Figure 2 Mechanisms by which specific components of intestinal microbiota may protect from allergic sensitization and or alleviate symptoms. Adequate microbial composition may reduce allergen uptake by providing maturational stimulus for gut barrier function enhancing allergen degradation by production of digestive enzymes this may also reduce allergen allergenicity improving mucosal integrity by direct exclusion of pathogens that may cause epithelial damage or by enhancing secretory IgA sIgA production possibly via inducing TGF-b secretion and by inducing secretion of anti-inflammatory cytokines which may break a vicious circle where inflammation increases gut permeability allowing invasion of pathogens and allergens which then results in further inflammation. Danger signals caused by epithelial damage and inflammation promote the maturation of dendritic cells which influence the differentiation of naive Th cells. Presentation of allergen in absence of danger signals may promote formation of regulatory T cells Treg and thus formation of tolerance to the allergen. The fate of Th cells in the presence of danger signals depends on additional stimulus presence of TGF-b produced . by epithelial cells may promote development of Treg population and again tolerance to the allergen presence of IL-12 andIFN-g produced . by macrophages or dendritic cells promotes development of Th1 population and non-allergic type immune responses whereas presence of IL-10 may promote formation of allergen specific Th2 cells. In the symptomatic phase induction of antiinflammatory cytokines may also directly alleviate the allergic inflammation by active suppression. Abbreviations sIgA secretory IgA M M-cell iDC immature dendritic cell mDC mature dendritic cell IL interleukin TGF transforming growth factor Th T-helper Treg regulatory T-cell MF macrophage. immunological deviancies that could result in impaired recognition of specific .
