Oxymatrine therapy inhibited epidermal cell proliferation and apoptosis in severe plaque psoriasis

BACKGROUND: Psoriasis is a chronic skin disorder that manifests as epidermal keratinocyte hyperplasia. OBJECTIVES: We examined the effect of oxymatrine treatment on cell proliferation and apoptosis in skin lesions of psoriasis. PATIENTS AND METHODS: Patients with severe plaque psoriasis were treated with oxymatrine or with acitretin. The skin lesions were stained with proliferating cell nuclear antigen (PCNA), Ki‐67 and Bcl‐2, as well as examined by terminal deoxynucleotidyl transferase‐mediated dUTP nick‐end labelling (TUNEL). We performed correlations of the Psoriasis Area and Severity Index (PASI) and the proliferation and apoptosis index. RESULTS: Oxymatrine significantly reduced the psoriasis lesions as demonstrated by the reduced PASI score after treatment [6·91; 95% confidence interval (CI) 5·00–8·81, P < 0·001]. In the oxymatrine group, the mitotic index was 26·15 (95% CI 24·80–27·49) before oxymatrine treatment, decreasing to 14·52 (95% CI 13·82–15·25; P < 0·001) after treatment, but remained higher than the normal group (6·24; 95% CI 5·87–6·61, P < 0·001). Oxymatrine also inhibited the proliferation of epidermal cells in the skin lesion as indicated by the reduced proliferation index after treatment (P < 0·01). In addition, oxymatrine treatment reduced cellular apoptosis as shown by increased Bcl‐2 expression and a decrease in TUNEL‐positive cells. The PASI score was positively correlated with mitotic index, proliferation index and apoptotic index (TUNEL), but negatively correlated with Bcl‐2 expression. CONCLUSIONS: Oxymatrine treatment reduced proliferation but inhibited apoptosis of cells in the skin lesion. The balance between cell proliferation and turnover may contribute to the significant alleviation of psoriasis by oxymatrine. What's already known about this topic? Psoriasis manifests as epidermal keratinocyte hyperplasia with proliferation, keratinocyte maturation and turnover rates. Current drugs for psoriasis may inhibit cell proliferation but could not adjust the balance of cell division, differentiation and apoptosis. What does this study add? We studied the efficacy of oxymatrine in the treatment of psoriasis and analysed the correlation of skin lesions, proliferation and apoptosis index before and after oxymatrine treatment. What is the translational message? Our study has demonstrated that oxymatrine is effective in the treatment of severe plaque psoriasis. It has comparable efficacy with acitretin. Because acitretin treatment was sometimes associated with metabolic abnormalities, our study suggests oxymatrine therapy as an alternative treatment for psoriasis in the context of acitretin allergy or adverse reactions.