Abstract
Interleukin (IL)-10 is a pluripotent cytokine with effects on numerous cell populations, in particular circulating and resident immune cells as well as epithelial cells. With its potent immunoregulatory capacities, its main biological function seems to be the limitation and termination of inflammatory responses. Hence, its low level expression found in psoriasis may have pathophysiological relevance to this immune disease. Remarkably, the induction of IL-10 expression was found by conventional antipsoriatic therapies, supporting the hypothesis that it may be a key cytokine in psoriasis. Furthermore, the first use in clinical trials in patients with established psoriasis showed that it had moderate antipsoriatic effects and was well tolerated. Moreover, long-term application in psoriatic patients in remission showed that it decreases the incidence of relapse and prolongs the disease free interval. The IL-10 antipsoriatic activity is suggested to be due to the effects on different cell populations, including antigen presenting cells and T-cells (type 1 / type 2 balance shift), but not through direct effects on keratinocytes. In conclusion, IL-10 seems to have major clinical and therapeutic implications in psoriasis. Further multicenter, placebo-controlled, double blind trials are required to be an established antipsoriatic therapy. We can come to the conclusion that IL-10 genetic polymorphism and expression is potentially a key immune marker in psoriasis.