Diphenylcyclopropenone plays an effective therapeutic role by up-regulating the TSLP/OX40L/IL-13 pathway in severe alopecia areata

Topical immunotherapy with diphenylcyclopropenone (DPCP) is considered to be the most effective treatment of severe AA. However, the mechanism is unclear and an early predictor for the efficacy needs to be explored. The TSLP/OX40L/IL-13 pathway is an important pathway to initiate and maintain Th2 immune responses. Our previous work suggests this pathway may play a role in severe AA treated with DPCP. Thus, to further investigate the mechanism of TSLP/OX40L/IL-13 pathway in severe AA treated with DPCP and explore the predictor for the efficacy of DPCP therapy, we conducted a prospective study to compare expression levels of TSLP, OX40L, Th2 cytokines IL-4, IL-5 and IL13, and Th1 cytokine IFN-γ in severe AA patients before and after the treatment. Results showed that 21 AA patients were responsive (responders) to the DPCP therapy and 12 were not responsive (non-responders). Responders had lower levels of TSLP, OX40L and IL-13 than non-responders before the treatment. After the DPCP treatment, TSLP, IL-5 and IL-13 increased and IFN-γ decreased in responders while there were no changes of TSLP, IL-4, IL-13 and IFN-γ in non-responders. Our data suggest that the TSLP/OX40L/IL-13 pathway is down-regulated in some severe AA patients and DPCP might play a therapeutic role by up-regulating the pathway in these severe AA patients. The TSLP/OX40L/IL-13 pathway could be a predictor of response to the DPCP therapy for severe AA patients.