Interleukin-9 and soluble tumor necrosis factor-like weak inducer of apoptosis in serum and suction blister fluid of nonsegmental vitiligo patients: Relation to disease severity

Background: Autoimmunity is a key player in nonsegmental vitiligo (NSV). Interleukin-9 (IL-9) and tumor necrosis factor-like weak inducer of apoptosis (TWEAK) are pleiotropic cytokines that are involved in many chronic autoimmune diseases. Objectives: To measure IL-9 and TWEAK in serum and suction blister fluid of NSV patients and study their relation to vitiligo. Methods: Thirty NSV patients and thirty controls were recruited. Following detailed history and clinical examination, the vitiligo area scoring index (VASI) and the vitiligo disease activity score (VIDA) of the patients were calculated. IL-9 and TWEAK were measured in serum of patients and controls and in suction blister fluid of patients. Results: Serum levels of IL-9 and TWEAK were significantly higher in patients than in controls (P < 0.001). Meanwhile, in patients, IL-9 and TWEAK were significantly higher in serum than in blister fluid (P < 0.001). A significant positive correlation of serum IL-9 (P < 0.001) and serum TWEAK (P < 0.001) with VASI was detected. A significant positive correlation between serum IL-9 and TWEAK in patients was also detected (P < 0.001). Blister fluid levels of both cytokines showed no significant correlation with any of the studied parameters. Conclusion: The elevated serum IL-9 and TWEAK in NSV possibly contributes to disease development and influences disease severity. Exploring their potential as possible therapeutic targets is, therefore, recommended.