Abdullateef A. Alzolibani

Hydroxyl Radical Modification of Immunoglobulin G Generated Cross-Reactive Antibodies: Its Potential Role in Systemic Lupus Erythematosus

Objective Role of reactive oxygen species (ROS) modified human Immunoglobulin G (IgG) in systemic lupus erythematosus (SLE) has been investigated. Methods Human IgG was modified by hydroxyl-radicals. Immunogenicity of native and modified human IgG was probed by inducing polyclonal antibodies in rabbits. Cross-reactions of induced antibodies with nucleic acid, chromatin, different blood proteins and their ROS modified conformers were determined by competitive inhibition ELISA. The binding characteristics of circulating autoantibodies in SLE patients (n = 72) against native and modified IgG were screened by direct binding and competition ELISA and the results were compared with healthy age-matched controls (n = 39). Results Induced antibodies against ROS-modified human IgG exhibited diverse antigen binding characteristics. Native DNA, native chromatin and their ROS-modified conformers were found to be effective inhibitors of induced antibody-immunogen interaction. Induced antibodies against native human IgG showed negligible binding to the above mentioned nucleic acid antigens. SLE sera (48.6%) showed strong binding to ROS-human IgG in comparison with its native analogue (P < 0.01). Normal human sera (NHS) showed negligible binding with either antigen (P > 0.05). Conclusion ROS-induced modifications in human IgG present neo-epitopes, and make it a potential immunogen. The induced antibodies against ROS-modified human IgG resembled the diverse antigen-binding characteristics of naturally occurring SLE anti-DNA autoantibodies. ROS-modified IgG may be one of the factors for the induction of circulating SLE autoantibodies.

4-Hydroxy-2-nonenal modified histone-H2A: a possible antigenic stimulus for systemic lupus erythematosus autoantibodies.

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.

Immunological Studies of Reactive Oxygen Species Damaged Catalase in Patients with Systemic Lupus Erythematosus: Correlation with Disease Activity Index

Objectives: This study was undertaken to investigate the status and contribution of oxidized catalase in systemic lupus erythematosus (SLE) and to explore whether oxidized catalase has a role in disease progression. Methods: Catalase (CAT) was modified by reactive oxygen species (ROS). Sera from 50 SLE patients with varying levels of disease activity according to SLE Disease-Activity-Index (SLEDAI) and 45 age- and sex-matched healthy controls were evaluated for antibodies against oxidized CAT. Results: Serum analysis showed significantly higher level of anti-oxidized-CAT-antibodies in SLE patients compared with controls. Interestingly, not only was there an increased number of subjects positive for anti-oxidized-CAT-antibodies, but also the levels of these antibodies were significantly higher among SLE patients, whose SLEDAI scores were ≥10 as compared with lower SLEDAI scores (<10). In addition, significant correlation was observed between the levels of anti-oxidized-CAT-antibodies and SLEDAI score (r = 0.796). Furthermore, sera from SLE patients had lower levels of CAT activity compared with control sera. Conclusions: These findings support an association between oxidized CAT and SLE. The stronger response observed in serum samples from patients with higher SLEDAI scores suggests that oxidized CAT may be a useful biomarker in evaluating the progression of SLE and in elucidating the mechanisms of disease pathogenesis.

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

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 HNEHSA, 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-HSAshowed 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.

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

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.

Biochemical Markers of Oxidative and Nitrosative Stress in Acne Vulgaris: Correlation With Disease Activity

Acne vulgaris is a multifactorial skin disorder of unknown etiology. Free radical‐mediated reactions have been implicated but their role in eliciting this response and contributing to disease progress remains unexplored. This study was undertaken to investigate the status and contribution of oxidative/nitrosative stress in patients with acne vulgaris. J. Clin. Lab. Anal. 27:45–2, 2013.

Tumor necrosis factor-α −308 G/A and interleukin 10 −1082 A/G gene polymorphisms in patients with acne vulgaris

BACKGROUND Cytokines play an important role in the pathogenesis of acne vulgaris together with other genetic and environmental factors. OBJECTIVE To check for the association of TNF-α and IL-10 gene polymorphisms with the susceptibility and severity of acne in Saudi patients. SUBJECTS AND METHODS Study subjects included 166 Saudi patients (65 males, 101 females) with acne vulgaris. Their mean age±SD was 21.6±5.1 years. These cases were compared to 390 unrelated healthy controls (208 males, 182 females) with a mean age±SD of 20.1±3.3 years. Cases were sub-grouped on the basis of their severity of acne affection into mild, moderate and severe groups. For all participants, genotypic variants of the TNF-α -308 G/A and IL-10 -1082 A/G genes were determined using the real time PCR technique. RESULTS Frequencies of genotypic variants of the TNF-α -308 polymorphism were significantly different in acne cases compared to controls. Further analysis showed that acne cases had significantly higher frequency of both the GG and AA homozygous forms than controls (73.8% vs. 63.6%, p=0.02, odds ratio=1.6). It was also interestingly noticed that the amount of GG homozygosity was notably higher among female cases than male ones (76.0% vs. 54.7%, p=0.006, odds ratio=2.6) whereas male cases had a higher frequency of AA and GA genotypes than female ones (9.4% and 35.9% vs. 4% and 20% respectively). Differences in the frequencies of IL-10 -1082 genotypic variants were statistically insignificant comparing cases to controls (p=0.3). On the other hand, comparing cases-subgroups in terms of the age of onset of the disease, consanguinity, family history, obesity and acne severity; no statistical significance was observed regarding frequencies of genotypic variants related to the both TNF-α -308 and IL-10 -1082 polymorphisms (>0.05). CONCLUSIONS TNF-α -308 polymorphic variants might be a predisposing factor for acne susceptibility, with no apparent relation to its severity whereas IL-10 -1082 variants showed no association with both acne susceptibility and severity.

Immunoglobulin E, Interleukin-18 and Interleukin-12 in Patients with Atopic Dermatitis: Correlation with Disease Activity

INTRODUCTION Atopic dermatitis (AD) is a chronic inflammatory skin disorder. Immunological/inflammatory reactions are reported to play a role in AD but their role in disease activity has not been fully investigated. This study was done to investigate the role of immunoglobulin E (IgE), interleukin (IL)-18 and IL-12 in AD patients with different disease severities. MATERIALS AND METHODS Sera from 50 AD infants with varying levels of disease activity according to the scoring index of atopic dermatitis (SCORAD) index and 30 age-matched healthy controls were evaluated for serum levels of IgE, IL-18 and IL-12/p40. RESULTS Serum analysis showed higher levels of IgE, IL-18 or IL-12/p40 in AD patients compared with controls. Interestingly, not only was there an increased number of subjects positive for IgE, IL-18 or IL-12/p40, but also the levels of these parameters were higher among AD patients whose SCORAD scores were higher. In addition, a significant correlation was observed between the levels of these parameters and SCORAD scores. CONCLUSION These findings support an association between IgE, IL-18 or IL-12/p40 and AD. The stronger response observed in serum samples from patients with higher SCORAD scores suggest that IgE, IL-18 and IL-12/p40 may be useful in evaluating the progression of AD and in elucidating the mechanisms of disease pathogenesis.

Psoriasin: A Novel Marker Linked Obesity with Psoriasis

To evaluate the role of psoriasin, koebnerisin, interleukn (IL)-12 and IL-23 in the pathogenesis of psoriasis and their relations to Psoriasis Area Severity Index (PASI) and obesity. Thirty patients had chronic plaque psoriasis and 30 healthy subjects matched in age and sex were enrolled in this study. Serum from all subjects were used for determination of psoriasin, koebnerisin, IL-12 and IL-23 by ELISA kits. IL-23 and psoriasin were significantly higher in skin psoriasis compared to controls and psoriatic arthritis (PsA). There was a correlation between psoriasin and both PASI and obesity. On the other hand, IL-12 was significantly increased in PsA compared to skin psoriasis (p = 0.000) and controls. Its sensitivity and specificity were 87%, 93%; respectively. To our knowledge, psoriasin is the first biomarker confirm the link between obesity and psoriasis. The risk of developing psoriasis is directly related to higher BMI.

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

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.