Circulating Th17, Th22, and Th1 cells are increased in psoriasis

Abstract

Th17, Th22, and Th1 cells are detected in psoriatic skin lesions and implicated in psoriasis pathogenesis, but inflammatory T cell numbers in blood, as well as the relative importance of each cell type, is unclear. Using 7-color flow cytometry, circulating Th17, Th22, and Th1 cells were quantified in 21 untreated psoriatics and 17 healthy individuals. CCR6 was the best cell surface marker for IL-17A cells when compared with IL-23R or CD161. CCR6, IL-17A, IL-22, CCR6IL-17A, CCR6IL-22, CCR6tumor necrosis factor-α, IL-17AIFN-γ, IL-17AIL-22IFN-γ, and IL-17AIL-22IFN-γ cells were increased in psoriatics (all values P0.001), indicating elevations in circulating Th17 cells, using multiple criteria to define these cells. Th22 (IL-17AIL-22IFN-γ, P0.05) and Th1 (IL-17AIFN-γ, P0.05) cells were also increased in psoriatics, but to a lesser extent. Inhibition of either NF-B or STAT3 in vitro blocked cytokine production by both Th17 and Th1 cells. Circulating levels of Th17 and Th1 cells decreased in a subset of five psoriasis patients serially evaluated following induction therapy with infliximab. In summary, elevated numbers of circulating inflammatory T cells may contribute to cutaneous inflammation and systemic inflammatory disease that occurs in individuals with psoriasis. © 2010 The Society for Investigative Dermatology.