Serum interleukin-6 levels in response to methotrexate treatment in psoriatic patients

Psoriasis is a chronic autoimmune hyperproliferative skin disease. In psoriasis, the cutaneous and systemic overexpression of various proinflammatory cytokines, such as interleukin-6 (IL-6) has been demonstrated. Methotrexate (MTX) has been used in the treatment of psoriasis. The aim of this study is to assess the effect of MTX on serum IL-6 levels and also to find the association between PASI score and IL-6 levels in psoriatic patients during MTX therapy.

We recruited 20 control subjects and 22 Psoriasis vulgaris patients for this study. The patients were treated with 7.5mg of methotrexate per week for 12 weeks. Folic acid was given at 5mg once daily except on the day of MTX for 12 weeks. There were 2 dropouts, because of increased liver enzyme levels. Blood samples were collected at three intervals (i.e., Day 0, 6 weeks, 12 weeks) from psoriatic patients and only once from control subjects. PASI score, biochemical and hematological parameters were assessed. Serum IL-6 level was analyzed by using ELISA.

Biochemical and hematological parameters showed no significant changes. Serum IL-6 level and PASI score declined significantly (p<0.001) from Day 0 to 12 weeks of MTX treatment and also showed positive correlation before (r=0.992; p<0.000) and after (r=0.987; p<0.000) treatment with MTX. Out of 4 clinical indices of PASI, only 2 indices namely Infiltration (I) and Desquamation (D) showed positive correlation with IL-6 before and after MTX treatment.

The treatment response with MTX in psoriatic patients can be seen both at clinical and molecular levels.