Pruritus, Allergy and Autoimmunity: Paving the Way for an Integrated Understanding of Psychodermatological Diseases

Pruritus, or itching, is a significant symptom in psychophysiological dermatoses, which are skin disorders with a psychological component. This review explores the biological mechanisms underlying pruritus, highlighting the role of mast cells in both allergic and autoimmune responses. Allergies, characterized by IgE-mediated hypersensitivity and Th2 responses, can evolve into autoimmune conditions with Th1 and IgE-independent inflammation, as seen in chronic spontaneous urticaria. Autoimmunity is also implicated in other psychodermatological diseases like psoriasis, atopic dermatitis, and alopecia areata, where mast cells contribute to symptoms like pruritus and hair loss. The review also discusses the psychosocial impact of skin and hair, the connection between psychopathology and skin disorders, and the role of mast cells in the circadian rhythm and stress response via interactions with melatonin and CRH. The evidence suggests a complex interplay between allergy, autoimmunity, and psychosomatic factors in these conditions, advocating for an integrated psychodermatological approach to treatment.