IL4 and major depressive disorder: For example, the established effectiveness of agents targeting the interleukin (IL)-4/IL-13 pathway in both diseases supports the concept of shared biology between these traits.34 Other comorbidities may influence skin inflammation directly, for example obesity and cardiovascular disease have been reported to be causally related to psoriasis risk.35,36 Prevalent mental health disorders such as depression and anxiety are also associated with more severe inflammatory skin disease, but these disorders may be the result of severe inflammatory skin disease rather than the cause.37,38