Biochemical and immunological studies on erythrocytes superoxide dismutase modified by nitric oxide in patients with alopecia areata: Implications in alopecia patchy persistent and alopecia universalis

Alopecia areata (AA) is a non-scarring hair loss disorder that ranges in severity from patchy loss of scalp hair (AA patchy persistent; AAP) to loss of all scalp and body hair (alopecia universalis; AU). The cause of AA is unknown but most evidences support that AA has an autoimmune etiology, where free radicals play an important role. This study was undertaken to investigate the role of nitric oxide (NO) modified erythrocytes superoxide dismutase (eSOD) in AA. Data revealed that NO-induced damage in eSOD caused alteration in hydrophobic or aromatic amino acids and protein carbonyl contents. NO-specific quencher, carboxyl-PTIO further reiterates NO-modifications. Specificity of antibodies from AA patients (n = 26) was analyzed toward NO-modified eSOD (NO-eSOD) and their results were compared with healthy controls (n = 30). Protein-A purified IgG of AA patients (AA-IgG) showed strong binding to NO-eSOD in comparison with IgG from controls. In addition, AA-IgG from patients with AU recognized NO-eSOD in a greater extent as compared to AA-IgG from patients with AAP. Furthermore, AU patients' sera contained higher levels of NO or carbonyl contents and lower levels of SOD activity compared with AAP patients' or control sera. In conclusion, this is the first study to demonstrate the role of NO-modified-eSOD in AA. Our novel results conclude that perturbations in SOD by NO presenting unique neo-epitopes that might be one of the factors for the antigen driven antibodies induction in AA. Preferential binding of NO-eSOD by AA-IgG pointed out the likely role of NO-eSOD in the initiation/progression of AA.