Host-microbiome interactions in atopic and allergic diseases

The environmental exposome impacts the human microbiome, which in turn influences various immune and metabolic functions. Microbiome dysbiosis can be triggered by exposome components and may lead to the development of atopies or exacerbation of existing allergic conditions via the disruption of epithelial barriers and alteration of immune responses. The gut microbiome is a key regulator of the immune system, and immune homeostasis is maintained through bidirectional communication between the gut and distant tissues and organs. The skin microbiome also plays a central role in tuning host immunity and may contribute significantly to the emergence and progression of allergic skin disease. The loss of balance between the host and its microbiota can lead to the breakdown of immune tolerance and may thus contribute to allergy development. In this review, we discuss the current understanding of host-microbe and environmental interactions which have been linked with atopy and allergic diseases.