Autoimmune response to AGE modified human DNA: Implications in type 1 diabetes mellitus

• Human DNA was glycated by methylglyoxal and lysine in presence of copper
• Glycated DNA exhibited altered structure and neo-epitopes
• The glycated DNA has been found immunogenic as compared to the native form
• Autoantibodies in DM type 1 patients showed higher binding to the modified DNA
• Possible role of DNA glycation in diabetes has been discussed

AimsNon-enzymatic glycation of DNA both in vivo and in vitro results in generation of free radicals, known as glycoxidation. Glycoxidation leads to structural perturbation of DNA resulting in generation of neo-antigenic epitopes having implication in autoimmune disorders like diabetes mellitus. In this study human placental DNA was glycated with methylglyoxal (MG) and lysine (Lys) in the presence of Cu2+ and its auto-antibody binding was probed in Type 1 diabetes patients.MethodsGlycation was carried out by incubating DNA with MG, Lys and Cu2+ for 24 h at 37 °C. Carboxyethyl deoxyguanosine (CEdG) formed in glycation reaction was studied by LC-MS and the pathway for Amadori formation was studied by ESI-MS techniques. Furthermore, binding characteristics of auto-antibodies in diabetes patients were assessed by direct binding, competitive ELISA and band shift assay.ResultsDNA glycation with MG, Lys and Cu2+ results in the formation of CEdG (marker of DNA glycation) which was confirmed by LC-MS. The intermediate stages of glycation were confirmed by ESI-MS technique. Serum from diabetes patients exhibited enhanced binding and specificity for glycated DNA as compared to native form.ConclusionsGlycation of DNA has resulted in structural perturbation causing generation of neo-antigenic epitopes thus recognizing auto-antibodies in diabetes.