Hydroxychloroquine protects melanocytes from autoantibody-induced injury by reducing the binding of antigen-antibody complexes.
Vitiligo is a polygenic autoimmune disorder characterized by loss of pigmentation due to melanocyte destruction. Hydroxychloroquine (HCQ) is an effective immunosuppressant widely used in the treatment of autoimmune disorders. As generalized vitiligo (GV) is commonly considered to be a T cell and autoantibody-induced immune disorder, the present study aimed to determine whether HCQ protects melanocytes from autoantibody‑induced disruption. Anti‑melanocyte antibodies were obtained from the serum of patients with progressive GV and the effects of HCQ on prevent the autoantibody‑induced disruption of melanocytes was observed. Cell‑based ELISA, indirect immunofluorescence and western blotting were used to analyze the autoantibody content of sera samples obtained from 32 patients with progressive GV. The cytotoxicity of HCQ was detected by MTT assay, and 1 µg/ml HCQ was applied to human primary melanocytes (HMCs) to examine whether it could exert protective effects against autoantibody‑induced immune injury. Flow cytometry was used to measure autoantibody binding to the surface of HMCs. Complement‑dependent cytotoxicity (CDC) and antibody‑dependent cell‑mediated cytotoxicity (ADCC) were monitored by MTT and lactate dehydrogenase‑releasing assays. The concentration of autoantibodies in sera samples taken from GV patients was significantly higher than in controls, particularly in patients who had >10% of their body surface affected by vitiligo. The majority of the autoantibodies presented in the HMCs and human keratinocytes (HKCs) and were predominantly localized to the cell surface and cytoplasm. The molecular weights of the autoantigens were identified as 30, 37‑39, 42, 53, 60‑75, 90, 100, 110, and 126 kDa; the 30 kDa protein was observed only in HMCs. The addition of HCQ at a concentration of 1 µg/ml produced no significant cytotoxicity in HMCs and was demonstrated to reduce the binding of GV immunoglobulin G (IgG) to the surface of HMCs. HCQ also significantly decreased the effects of ADCC and CDC that were mediated by GV IgG. The present study provides evidence that HCQ dissociates autoantibody-antigen complexes on the surface of HMCs and reverses ADCC and CDC activity in vitro. Thus, in addition to its effectiveness as an antimalarial therapeutic agent, HCQ may also be a promising potential treatment for patients with vitiligo.
Department of Dermatology, The General Hospital of Air Force, Beijing 100142, P.R. China.
Dong-Guang
DG
Li
Department of Dermatology, The General Hospital of Air Force, Beijing 100142, P.R. China.
Wen-Zhi
WZ
Hu
Department of Dermatology, The 309th Hospital of Chinese PLA, Beijing 100091, P.R. China.
Hui-Jun
HJ
Ma
Department of Dermatology, The General Hospital of Air Force, Beijing 100142, P.R. China.
Wen
W
Liu
Department of Dermatology, The General Hospital of Air Force, Beijing 100142, P.R. China.
Qing-Qi
QQ
Yang
Department of Dermatology, The General Hospital of Air Force, Beijing 100142, P.R. China.
Guang
G
Zhao
D000293:Adolescent; D000328:Adult; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects* / Q000276:immunology*; D000936:Antigen-Antibody Complex / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology; D016022:Case-Control Studies; D002478:Cells, Cultured; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D006886:Hydroxychloroquine / Q000494:pharmacology*; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology; D008297:Male; D008544:Melanocytes / Q000187:drug effects* / Q000276:immunology*; D008875:Middle Aged; D014820:Vitiligo / Q000175:diagnosis / Q000276:immunology; D055815:Young Adult
D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D006886:Hydroxychloroquine