Interactions of the immune and sensory nervous systems in atopy

A striking feature underlying all atopic disorders, such as asthma, atopic dermatitis, and food allergy, is the presence of pathologic sensory responses, reflexes, and behaviors. These symptoms, exemplified by chronic airway irritation and cough, chronic itch and scratching, as well as gastrointestinal discomfort and dysfunction, are often cited as the most debilitating aspects of atopic disorders. Emerging studies have highlighted how the immune system shapes the scope and intensity of sensory responses by directly modulating the sensory nervous system. Additionally, factors produced by neurons have demonstrated novel functions in propagating atopic inflammation at barrier surfaces. In this review, we highlight new studies that have changed our understanding of atopy through advances in characterizing the reciprocal interactions between the immune and sensory nervous systems. Atopic disorders such as asthma, atopic dermatitis, and food allergy include aberrant type 2 inflammation at barrier surfaces along with pathologic sensations like airway irritation and cough, itch, and gastrointestinal (GI) discomfort. Emerging research has also highlighted that the sensory nervous system can reciprocally influence barrier inflammation. This review summarizes recent findings describing how neuroimmune interactions shape atopic disorders.