title: Interleukin-21 is associated with the severity of psoriasis vulgaris through promoting CD4+ T cells to differentiate into Th17 cells.
abstract: Interleukin-21 (IL-21) and T helper 17 (Th17) cells are known to be involved in the pathogenesis of psoriasis, but little is known about their relationship in psoriasis. Herein, we investigated whether IL-21 could regulate Th17 cell induction in patients with psoriasis vulgaris. 32 patients with psoriasis vulgaris and 13 healthy controls were recruited. Flow cytometry was used to detect the frequencies of cells mainly secreting IL-21 (including IL-21+CD4+ T and IL-21+ Th17 cells) and Th17 cells. An enzyme-linked immunosorbent assay (ELISA) was used to determine the serum content of IL-21. Severity of the psoriasis was evaluated by a Psoriasis Area and Severity Index (PASI) score. In addition, the differentiation of CD4+ T cells with IL-21 and the different frequencies of IL-21+CD4+ T cells, IL-21+ Th17 cells and Th17 cells were assessed, as were serum levels of IL-21 in patients with moderate to severe psoriasis before and after treatment. Our results showed that the levels of IL-21, IL-21+CD4+ T cells, IL-21+ Th17 cells and Th17 cells were significantly increased in patients and positively associated with PASI score (P < 0.01). Moreover, the levels of IL-21, IL-21+CD4+ T cells and IL-21+ Th17 cells were positively correlated with the frequency of Th17 cells (P < 0.01). In vitro experiments demonstrated that IL-21 could promote CD4+ T cells to differentiate into Th17 cells. After a 4-week treatment of acitretin and a topical therapy, all the immune markers observed in patients decreased significantly (P < 0.01), but the levels remained higher than those in healthy controls (P < 0.01). These findings indicate that IL-21 might promote Th17 cell induction in psoriasis and might be a potential immune marker for targeting this disease.
authors: Clinical Institute of China-Japan Friendship Hospital, Graduate School of Peking Union Medical CollegeBeijing, China; Department of Dermatology & Venerology, China-Japan Friendship HospitalBeijing, China.
authors: Ying
authors: Y
authors: Wang
authors: Clinical Institute of China-Japan Friendship Hospital, Graduate School of Peking Union Medical CollegeBeijing, China; Department of Dermatology & Venerology, China-Japan Friendship HospitalBeijing, China.
authors: Li-Li
authors: LL
authors: Wang
authors: Department of Dermatology & Venerology, China-Japan Friendship HospitalBeijing, China; Beijing University of Chinese MedicineBeijing, China.
authors: Hao-Yu
authors: HY
authors: Yang
authors: Department of Dermatology & Venerology, China-Japan Friendship HospitalBeijing, China; Beijing University of Chinese MedicineBeijing, China.
authors: Fei-Fei
authors: FF
authors: Wang
authors: Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University Zhengzhou, Henan, China.
authors: Xue-Xiu
authors: XX
authors: Zhang
authors: Clinical Institute of China-Japan Friendship Hospital, Graduate School of Peking Union Medical CollegeBeijing, China; Department of Dermatology & Venerology, China-Japan Friendship HospitalBeijing, China.
authors: Yan-Ping
authors: YP
authors: Bai
keywords: Psoriasis; Th17 cells; acitretin; interleukin-21