Improving topical treatments for skin diseases.

Skin diseases and skin problems affect millions of people every day. Skin lesions are often difficult to treat locally and much is to be gained by developing more targeted treatments to avoid the use of systemic immunosuppressant drugs. Recent data on the function of microenvironmental factors could help improve such therapies. Vitamins A and D and their metabolites have strong effects on both innate and adaptive immune responses, and can suppress inflammation, lymphocyte infiltration and function, as well as the ability to increase regulatory tasks within the skin. Combinatorial therapy that includes these metabolites, cytokines, chemokines or other agents could help to alter the local microenvironment and sway immune responses as needed, depending on the origin of the skin inflammation. Here, I argue that microenvironmental factors might be used to improve topical treatments in chronic inflammatory skin diseases such as psoriasis and atopic dermatitis, where T cells play a pathogenic role.