Psychological factors have long been assumed to be involved in the pathogenesis of allergic
skin diseases. The effects of psychological stress on
allergic contact dermatitis (ACD) have been experimentally well investigated; however, the effects of ACD on stress responses are largely unknown. Here, we report that preceding chronic ACD dramatically affects the behavioral and physiological stress responses to social isolation (a psychological stressor). In male BALB/c mice, social isolation combined with long-standing (>2 months) ACD by repeated
hapten application caused characteristic symptoms, including chronic
dermatitis from persistent self-scratching, behavioral changes related to fear/anxiety, and elevated serum
IgE levels. The symptoms were maintained by social isolation alone without further
hapten application after the onset, and were improved by resocialization. Treatment with topical
corticosteroids exacerbated chronic scratch
dermatitis, whereas it was effective for chronic ACD. These results show that the symptoms represent a de novo development of a specific disease state and not a mere exacerbation of a preexisting allergic
inflammation. With this experimental protocol, similar results were obtained in several other strains of mice. This murine model provides a tool for investigating the pathogenesis and treatment of allergic
skin disease with psychodermatological aspects.