Immunological Functions of Oxidized Human Immunoglobulin G in Type 1 Diabetes Mellitus: Its Potential Role in Diabetic Smokers as a Biomarker of Elevated Oxidative Stress

Abstract

The role of oxidized immunoglobulin G in type 1 diabetic smokers has been investigated in the present study. Human immunoglobulin G (IgG) was modified by reactive oxygen species (ROS). The binding characteristics of circulating autoantibodies in type 1 diabetes patients against native and modified IgG were assessed by direct binding ELISA. High degree of specific binding by 68.5% of patients sera towards ROS-modified IgG was observed in comparison to its native analogue (p< 0.05). In addition, diabetic smokers (n= 28) were examined and the results were compared with diabetic non-smokers (n= 26). Circulating antibodies of diabetic smokers showed substantially stronger binding to modified IgG as compared with the antibodies present in diabetic non-smokers (p< 0.05). Normal human sera (n= 53) showed negligible binding with either antigen. Competitive inhibition ELISA reiterates the direct binding results. The increase in total serum protein carbonyl levels in the diabetic smokers was largely due to an increase in oxidized IgG. Diabetic smokers showed substantially higher carbonyl contents in sera as well as in purified IgG as compared with sera and IgG of diabetic non-smokers. Collectively, the oxidation of plasma proteins, especially IgG, might enhance oxidative stress in type 1 diabetes smokers.

Antibodies against 4-Hydroxy-2-nonenal Modified Epitopes Recognized Chromatin and Its Oxidized Forms: Role of Chromatin, Oxidized Forms of Chromatin and 4-Hydroxy-2-nonenal Modified Epitopes in the Etiopathogenesis of SLE

“…Antibody specificity was determined by competitive binding assays as previously described [23,24]. Varying concentrations of inhibitors (0-20 µg/ml) were allowed to interact with a constant amount of antiserum or affinity purified IgG for 2 h at 37…”

Preferential Recognition of Peroxynitrite Damaged Thymidine-Monophosphate by Anti-DNA Autoantibodies in Systemic Lupus Erythematosus

“…[20] Briefly, polystryrene maxisorp immunoplates were coated with 100 µL of ONOO − -modified and unmodified TMP-BSA conjugates (10 µg/mL) in carbonate buffer (0.05 M, pH 9.6). The plates were coated for 2 h at room temperature (RT) and overnight at 4 • C. Each sample was coated in duplicate and half of the plates served as control devoid of only antigen coating.…”

Redox proteomic identification of carbonylated proteins in autism plasma: insight into oxidative stress and its related biomarkers in autism

“…Elevated levels of oxidized IgG have been observed in various diseases, including AD [14], rheumatoid arthritis [39], end-stage renal disease patients [40] and type 1 diabetes mellitus etc. [41, 42]. Very recently, five IgG proteins including Ig gamma-2B chain C region (IGH-3), Ig lambda-2 chain C region (IGLC2), IGKC and Ig kappa chain V-V region HP R16.7 were identified as carbonylated proteins in the serum of 3-month-old triple transgenic AD mice (3× Tg-AD mice) [43].…”