Microbiota, regulatory T cell subsets, and allergic disorders.

Epidemiologic studies revealed a crucial role of the environment for the increased prevalence of aller-gic disorders. e microbiota as part of our imme-diate environment promotes immune diversity that facilitates a well-equilibrated balance between immunity and tolerance. Alterations of our sym-biotic microbiota especially in early life is thought to play a fundamental role in defining susceptibility to the development of allergic diseases during adult life on the population level. Due to a high density of bacteria, viruses and fungi and a large contact surface area for host-microbiota inter-actions, the most relevant interaction between microbes and our immune system are thought to occur in the gut. e immune system co-evolved with the symbiotic microbiota and adopted a vari-ety of mechanisms to allow a dynamic state of tol-erance, including the induction of regulatory T cells (Tregs). Foxp3-expressing Tregs are well-described immune regulators in autoimmune and allergic disorders. However, recent years have shown that Tregs can come in di-erent ?avours with dierent regulatory potential and outcome for our immune system. is review summarizes novel findings from basic immunology research that may help to better understand the interaction between the microbiota, dierentiation of Tregs and its consequences for the onset and regulation of allergic disorders