B cell activating factor and T-helper 17 cells: possible synergistic culprits in the pathogenesis of Alopecia Areata

The role of T-helper 17 cells (Th17) and regulatory T-cells (Tregs) in the pathogenesis of alopecia areata (AA) has not been clearly elucidated. B cell activating factor (BAFF) being a regulator of T cell activation could be involved in this pathologic process as well. The current study evaluated the expression of IL-17, IL-22, Foxp3 and BAFF in tissue and sera of AA patients. Forty AA patients and 40 age and sex matched healthy controls were included. Tissue and serum levels of IL-17, IL-22, BAFF as well as serum level of Foxp3 were measured by enzyme-linked immunosorbent assay (ELISA). Immunohistochemical staining was used for assessment of tissue level of Foxp3. Tissue and serum levels of IL-17, tissue levels of IL-22 and BAFF were significantly higher in patients. Serum levels of IL-22, Foxp3 and BAFF were non-significantly higher in patients. Foxp3 immunostaining showed negativity in tissue of patients and controls. A significant positive correlation was found between both tissue levels of IL-17 and BAFF (r = 0.474, P = 0.035) and tissue level of IL-22 and disease duration (r = 0.766, P < 0.001) in AA patients. Th17 cells and BAFF are synergistically involved in the pathogenesis of AA. BAFF represents a promising therapeutic target for such a challenging disease. Defective Tregs number and/or function in AA warrants further studies.