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Objectives: To investigate the role of reactive-oxygen-species (ROS) induced epitopes on human-serum-albumin (HSA) and thyroid antigens in psoriasis autoimmunity.  , Methods: This study was performed in the College of Medicine, Qassim University, Buraidah, Saudi Arabia between May 2014 and February 2015. The study was designed to explore the role of ROS-induced epitopes in psoriasis autoimmunity. Singlet-oxygen (or ROS)-induced epitopes on protein (ROS-epitopes-albumin) was characterized by in-vitro and in-vivo. Thyroid antigens were prepared from rabbit thyroid, and thyroglobulin was isolated from thyroid extract. Immunocross-reactions of protein-A purified anti-ROS-epitopes-HSA-immunoglobulin G (IgGs) with thyroid antigen, thyroglobulin, and their oxidized forms were determined. Binding characteristics of autoantibodies in chronic plaque psoriasis patients (n=26) against ROS-epitopes-HSA and also with native and oxidized thyroid antigens were screened, and the results were compared with age-matched controls (n=22). , Results: The anti-ROS-epitopes-HSA-IgGs showed cross-reactions with thyroid antigen, thyroglobulin and with their oxidized forms. High degree of specific binding by psoriasis IgGs to ROS-epitopes-HSA, ROS-thyroid antigen and ROS-thyroglobulin was observed. Immunoglobulin G from normal-human-controls showed negligible binding with all tested antigens. Moreover, sera from psoriasis patients had higher levels of carbonyl contents compared with control sera.  , Conclusion: Structural alterations in albumin, thyroid antigens by ROS, generate unique neo-epitopes that might be one of the factors for the induction of autoantibodies in psoriasis.

Background: Vitiligo is a common pigmentary disorder, the precise etiology of which remains obscure. Tyrosinase, a key enzyme involved in melanin synthesis, has now been implicated as an autoantigen for vitiligo patients, but it is not clear how this prevalent protein becomes antigenic in vitiligo., Objective: To investigate the status and contribution of oxidized tyrosinase in vitiligo and to explore whether oxidized tyrosinase has a role in disease progression., Methods: Tyrosinase was modified by reactive-oxygen-species (ROS). Binding characteristics of antibodies in vitiligo patients (n=25) with varying disease duration (DD) and disease severity were screened against ROS-modified tyrosinase (ROS-tyrosinase) by immunoassays and their results were compared with healthy controls (n=23)., Results: The ROS caused extensive alterations in conformation and function of tyrosinase. Protein-A purified IgGs from vitiligo patients (Vt-IgG) showed strong binding to ROS-tyrosinase in comparison with IgGs from healthy controls (p<0.001). Interestingly, not only was there an increased number of subjects positive for anti-ROS-tyrosinase-IgGs, but also the levels of these IgGs were significantly higher among vitiligo patients, whose DD were ≥10 years as compared to patients with short DD (<10 years). In addition, a significant correlation was observed between the levels of anti-ROS-tyrosinase-IgGs and the patients' ages or with disease severity. Experimentally induced anti-ROS-tyrosinase-IgGs show reactivity with tyrosinase from vitiligo patients. Furthermore, vitiligo patients had lower levels of tyrosinase activity compared with healthy controls. Not only these, levels of carbonylation were also higher among vitiligo patients whose DD were ≥10 years as compared to patients with DD<10 years., Conclusions: This is the first study to demonstrate the role of oxidized tyrosinase in vitiligo. Our novel results support an association between oxidized tyrosinase and vitiligo autoimmunity. The stronger antibodies response to oxidized tyrosinase in vitiligo patients with higher DD or with severe patients suggests that oxidized tyrosinase may be a useful biomarker in evaluating the progression of vitiligo and in elucidating the mechanisms of disease pathogenesis., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Present study probes the role of peroxynitrite (ONOO(-))-modified thymidine-5'-monophosphate (TMP) in SLE patients with different disease activity scores according to the SLE Disease Activity Index (SLEDAI). Serum analysis showed significant increased number of subjects positive for anti-ONOO(-)-TMP-protein antibodies in SLE patients with different SLEDAI scores. Interestingly, the levels of these antibodies were significantly higher among SLE patients, whose SLEDAI scores were ≥20. In addition, a significant correlation was observed between the levels of anti-ONOO(-)-TMP-protein antibodies and the SLEDAI score (r = 0.595, p < 0.0001). In short, this study shows a positive association between anti-ONOO(-)-TMP-protein antibodies and SLEDAI. The stronger response observed in patients with higher SLEDAI scores suggests that anti-ONOO(-)-TMP-protein antibodies may be useful in evaluating the progression of SLE and in elucidating the mechanisms of disease pathogenesis.

Protein modifications by 4-hydroxy-2-nonenals (HNE) are involved in various diseases. Histones are DNA protective nucleoprotein, which adopt different structures under oxidative stress. This study was undertaken to test the role of HNE-modified-histone-H2A (HNE-H2A) in systemic lupus erythematosus (SLE). Our data revealed that HNE-mediated-lipid peroxidation in histone-H2A caused alteration in histidine, lysine and cystein residues. In addition, protein carbonyl contents were also high in HNE-H2A. HNE-specific quencher, L-carnosine further reiterates HNE-modifications. Specificity of autoantibodies from SLE patients (n=48) were analyzed towards HNE-H2A and their results were compared with sex- and age-matched controls (n=36). SLE autoantibodies show preferential binding to HNE-H2A in comparison with histone-H2A (p<0.0001). Furthermore, HNE-H2A was also detected in SLE peripheral blood mononuclear cells. In conclusion, this is the first study to demonstrate the role of HNE-modified-histone in SLE. Preferential binding of HNE-H2A by affinity purified SLE-IgG pointed out the likely role of HNE-H2A in the initiation/progression of SLE., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objectives: This study was undertaken to investigate the role of lipid oxidative-by-product 4-hydroxy-2-nonenal (HNE)-modified human serum albumin (HSA), chromatin, reactive oxygen species (ROS)-modified chromatin and nitric oxide (NO)-modified chromatin in systemic lupus erythematosus (SLE)., Methods: HSA was modified by HNE. Immunogenicity of modified HSA was probed by inducing polyclonal antibodies in rabbits. Chromatin was isolated from goat liver and modified by ROS or NO. Immunocross-reactions of Protein-A purified anti-HNE-HSA-IgG with chromatin, ROS-chromatin and NO-chromatin were determined. Autoantibodies from 74 SLE patients were screened. HSA was isolated from SLE patients (SLE-HSA) and immunocross-reactions of isolated SLE-HSA with HNE-specific antibodies were investigated., Results: HNE-HSA was found to be highly immunogenic in rabbits. The notable feature of anti-HNE-HSA-IgG showed cross-reactions with chromatin, ROS-chromatin and NO-chromatin (p< 0.01). High degree of specific binding to HNE-HSA, chromatin, ROS-chromatin or NO-chromatin was observed with antibodies from 55% of SLE patients. SLE anti-native/ oxidized chromatin antibodies showed specificity towards HNE-HSA. Furthermore, SLE-HSA showed binding with HNE-specific antibodies., Conclusions: This is the first study to demonstrate that chromatin and its oxidized forms have been recognized by antibodies against HNE modified epitopes. Our results provide an important insight into the immunological basis of the reported HNE-modified epitopes in SLE.

This study was undertaken to investigate the role of peroxynitrite (ONOO(-)) modified thymine-5'-monophosphate (TMP) in the generation of anti-DNA autoantibodies in patients with systemic lupus erythematosus (SLE). TMP was exposed to ONOO(-) in vitro and challenged in vivo. TMP and ONOO(-)-modified-TMP were found to be nonimmunogenic in rabbits. TMP-linked-BSA and ONOO(-)-modified-TMP-BSA induced high titer antibodies. Induced antibodies against ONOO(-)-TMP-BSA show crossreactions with nucleic acids conformers. A high degree of specific binding by SLE autoantibodies with ONOO(-)-TMP-BSA was observed. Our novel results provide an important insight into the immunological basis of anti-DNA autoantibodies generation in SLE.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with autoantibodies as a near universal feature of the disease. Earlier investigations from our laboratory revealed increased oxidative damage in SLE patients. Therefore, we hypothesized that oxidative by-products, such as hydroxyl radical (*OH), could lead to neoantigens like *OH damaged human serum albumin (HSA), which could in turn initiate autoimmunity in SLE. In the present study, the binding characteristics of SLE autoantibodies with native and *OH damaged HSA were assessed. SLE patients (n = 74) were examined by direct binding ELISA and the results were compared with healthy age- and sex-matched controls (n = 44). High degree of specific binding by 52.7% of patients sera towards *OH damaged HSA, in comparison to its native analogue (p < 0.05) was observed. Normal human sera showed negligible binding with either antigen. Competitive ELISA and gel retardation assays reiterate the direct binding results. The increase in total serum protein carbonyl levels in the SLE patients was largely due to an increase in oxidized albumin. HSA of SLE patients (SLE-HSA) and normal subjects (normal-HSA) were purified. Spectroscopic analysis confirmed that the SLE-HSA samples contained higher levels of carbonyls than normal-HSA (p < 0.01). SLE-HSA was conformationally altered, with more exposure of its hydrophobic regions. Collectively, the oxidation of plasma proteins, especially HSA, might enhance oxidative stress in SLE patients.

Anti-DNA antibodies are now considered as a universal diagnostic feature for the patients with systemic lupus erythematosus (SLE) but the mechanism(s) involved in the generation of these autoantibodies remains to be investigated. Bisphenol A (BPA) is a synthetic phenol extensively used in the manufacturing of polycarbonated plastics. Upon mixing in the diet, it causes several health hazards. This study was undertaken to investigate the contribution of BPA induced DNA damage in SLE patients. Human DNA was modified by BPA in-vitro and the binding characteristics of SLE circulating immunoglobulin Gs (SLE-IgGs) with BPA damaged DNA (BPA-DNA) were screened and compared with the IgGs from normal healthy humans (NH-IgGs). Immunogenicity of BPA-DNA was determined by immunisation in rabbits. DNA from SLE patients (SLE-DNA) or healthy humans (NH-DNA) were isolated and their binding specificity with rabbit anti-BPA-DNA-IgGs was studied. Treatment of human DNA with BPA caused extensive damaged. Circulating SLE-IgGs showed strong recognition of BPA-DNA. BPA-DNA induced high titre antibodies in rabbits. Rabbit anti-BPA-DNA-IgGs showed strong cross reaction with isolated DNA from SLE patients. In short, we concluded that the structural alterations in DNA by BPA, generate neo-epitopes that may be a factor responsible for the induction of anti-DNA autoantibodies in SLE. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]