Patients with palmoplantar pustulosis have increased IL-17 and IL-22 levels both in the lesion and serum

Recent findings about the pathogenesis of pustulosis palmaris et plantaris (PPP), also known as palmoplantar pustulosis, suggest that IL-17 expression in the acrosyringium as well as infiltration of IL-17 positive cells, e.g. Langerhans cells may play important roles. However, to date, it has not been established whether circulating IL-17 related cytokines are involved in PPP. We studied the circulating IL-17 related cytokines as well as the mRNA levels in lesional skin. IL-17 related cytokine mRNAs were increased in the PPP lesions compared with the control tissues (five patients vs five controls). The serum levels of TNF-alpha, IL-17, IL-22 and IFN-gamma also were significantly increased in PPP, but not IL-23 and IL-8 (48 patients vs 20 controls). Our findings document that not only the serum IL-17 but also tissue IL-17 are elevated in PPP and may be in the pathogenesis of this disorder.