Effect of methotrexate monotherapy on T-cell subsets in the peripheral circulation in psoriasis

Background Psoriasis is a T-helper (Th)1/Th17-mediated chronic inflammatory disease. There is an increased population of Th cells in skin lesions and peripheral circulation of patients with psoriasis. Systemic methotrexate (MTX) is an effective treatment for moderate to severe psoriasis; however, its effect on different T-cell subsets is not yet clear. Aim To study the effect of MTX monotherapy on the psoriatic T-cell profile in the peripheral circulation of patients with psoriasis. Methods This was a follow-up study involving 50 patients with moderate to severe psoriasis treated with systemic MTX for 12 weeks. Blood samples (5 mL) were collected from participants, from which PBMCs were isolated, and T-cell phenotyping was performed by flow cytometry. Results Following 12 weeks of MTX treatment, there was an increase in the percentages of Th2/Treg cells, and a relative decrease in the percentages of Th1/Th17 cells, along with a significant reduction in the median Psoriasis Area and Severity Index (PASI). Conclusion MTX helps in the restoration of the immune balance by decreasing the numbers of Th1 and Th17 cells and increasing the numbers of Th2 and Treg cells, thus resulting in a significant reduction in disease severity. MTX converts a proinflammatory T-cell phenotype to a protective anti-inflammatory phenotype, thus significantly suppressing the inflammation in psoriasis.