More than skin deep: the systemic nature of atopic dermatitis

Atopic dermatitis is a worldwide prevalent chronic inflammatory skin disease. Although primarily recognized as a disease of children, there is increasing evidence suggesting that it is more common in adults than previously thought. Both immune dysregulation and cutaneous barrier dysfunction are involved in the pathogenesis of the disease, although the exact mechanisms are still unclear. The concept of atopic dermatitis as a biphasic Th1-Th2 disease is changing, as recent evidence supports systemic activation of other multiple Th-cell subsets. Atopic dermatitis has been associated with an increasing number of comorbidities, possibly sharing some common pathological mechanisms. The atopic march is well known and represents the natural progression of atopic diseases in a considerable number of patients, usually starting with the development of atopic dermatitis followed by other atopic conditions, such as asthma and allergic rhinitis. Association of atopic dermatitis with cardiovascular disease, autoimmune diseases, as well as cutaneous and extracutaneous infections have been increasingly reported, although the link is not yet clear. Furthermore, the association between atopic dermatitis and neuropsychiatric conditions has also been widely studied, with an increased risk of mental health disorders strongly influenced by sleep disorders. Altogether, these associations contribute to the burden of atopic dermatitis, which increases the need for a more focused therapeutic approach that includes prevention or early diagnosis and treatment of comorbidities that may arise. This review explores the recent associations with atopic dermatitis and the possible underlying mechanisms involved, which supports the concept of atopic dermatitis as a systemic disease.