Acitretin exerted a greater influence on T‐helper (Th)1 and Th17 than on Th2 cells in treatment of psoriasis vulgaris

T‐helper (Th) cells, including Th1, Th2 and Th17 cells, may play an important role in the pathogenesis of psoriasis vulgaris (PV). Acitretin is an effective treatment for PV; however, its influence on Th cells during the treatment of PV is unclear. This study aimed to investigate the influence of acitretin on Th1, Th2 and Th17 cells in PV patients. PV patients (n = 30) received acitretin p.o. (20 mg/day) for 8 weeks. Sera and skin biopsies were obtained before and after treatment. Double‐labeled immunofluorescence was used to analyze T, Th1, Th2 and Th17 cells in skin lesions. Enzyme‐linked immunosorbent assay and western blot were used to analyze the expressions of interferon (IFN)‐γ, interleukin (IL)‐4 and IL‐17 in sera and skin lesions. The expressions of IFN‐γ mRNA, IL‐4 mRNA and IL‐17 mRNA in skin lesions were detected by in situ hybridization. Acitretin decreased the quantity of T, Th1 and Th17 cells in PV lesions, but had no significant influence on Th2 cells. Acitretin also decreased the expression of IFN‐γ and IL‐17 in serum and lesions. The expressions of IFN‐γ mRNA and IL‐17 mRNA decreased significantly after 8 weeks of therapy. However, acitretin had no significant influence on the expression of IL‐4 protein and mRNA. Acitretin can reverse Th1 and Th17 preponderance in PV patients to some degree. This may be due to the mechanism of acitretin on PV; however, Th2 cells were not affected by acitretin treatment.