Intestinal IgA production and its role in host‐microbe interaction

Abstract

Summary Complex and diverse communities of bacteria establish mutualistic and symbiotic relationships with the gut after birth. The intestinal immune system responds to bacterial colonization by acquiring a state of hypo-responsiveness against commensals and active readiness against pathogens. The resulting homeostatic balance involves a continuous dialog between the microbiota and lymphocytes with the intermediation of epithelial and dendritic cells. This dialog causes massive production of immunoglobulin A (IgA), a non-inflammatory antibody specialized in mucosal protection. Here, we discuss recent advances on the regulation of intestinal IgA responses and their role in host-microbe interaction.

Role of secretory IgA in the mucosal sensing of commensal bacteria

“…3 How commensal bacteria foster the development of the mucosal immune system, and in particular the stimulation of the biosynthesis of local SIgA, has been comprehensively reviewed lately. [4][5][6] SIgA is the most abundant antibody molecule on mucosal surfaces of humans and most other mammals. Production of IgA at mucosal surfaces contributes to host defense against intestinal pathogens 7,8 and governs quantitative and qualitative control of commensal microbiota composition by the host.…”

From the intestinal flora to the microbiome

“…These cells induce the production of anti-inflammatory interleukin 10 (IL-10), which contributes to a class change from IgA S to IgA. All of this ensures effective communication between the microbiota and the immune system, inducing a tolerogenic environment towards the microbiota and, at the same time, stimulating the activity of the immune system (33,34). The composition of the microbiota helps to maintain immunological homeostasis, which suggests that the microbiota could be an additional organ of the human organism (35).…”

Rol de la microbiota gastrointestinal en la regulación de la respuesta inmune

“…En resumen, el sistema de IgA es multifacético y actúa para mantener un ambiente antiinflamatorio, compartimentando las respuestas microbianas en el sistema inmune de la mucosa intestinal e induciendo tolerancia hacia la microbiota intestinal normal 13 .…”

“…Sí se puede establecer un cuadro general, comenzando con la S-IgA, la cual participa manteniendo a la microbiota intestinal en cantidades adecuadas para generar la respuesta tolerógenica o antigénica, y colaborando en la presentación antigénica. Esto aún está en discusión, pues se ha descrito que pueden volver mediante receptores especializados ubicados en la célula M 13 . También se ha comprobado que la interacción de las células dendríticas con el medio puede desviar la respuesta inmunológica a Th1, Th2 o Treg, las cuales son respuestas únicas, muy especializadas y diferenciadas entre ellas.…”