Treatment of psoriasis is always difficult, which requires intensive scientific research.

Tripterygium wilfordii Hook F (TwHF) with acitretin(TwHF + acitretin) is normally used in treating psoriasis. This study aimed to investigate the correlation of plasma miR-126 expression with risk and severity of psoriasis, and its predictive value of response to TwHF + acitretin treatment in psoriasis.

MiRNA-126(MiR-126) expression in plasma was analyzed in psoriasis patients at month 0 (M0), M1, M3 and M6 and in health controls (HCs) at enrollment by qPCR. Psoriasis-affected body surface area (BSA) and Psoriasis Area and Severity Index (PASI) score were used to assess severity and treatment response.

Plasma miR-126 levels were decreased in psoriasis patients compared with HCs (P < 0.001), with area under the curve (AUC) of 0.771. MiR-126 expression was negatively correlated with PASI score (P = 0.001), and negatively associated with psoriasis-affected BSA (P = 0.825). At M6, 65.3% and 36.1% patients achieved PASI 50 and 75, respectively. MiR-126 increased at M1, M3 and M6 after TwHF + acitretin treatment when comparing with M0 (all P < 0.001). Meanwhile, miR-126 expression baseline in PASI 50 group declined when comparing with non-PASI 50 group (P < 0.001). Additionally, data revealed that the cause of high miR-126 baseline level was due to unsuccessfully achieving PASI 50 at M6 after TwHF + acitretin treatment (P < 0.001). However, miR-126 baseline expression was not a predictive factor for PASI 75 achievement (P > 0.05).

Plasma miR-126 expression is negatively correlated with psoriasis risk and severity, and its high baseline level can be used as a biomarker to predict worse clinical response to TwHF + acitretin treatment in psoriasis.