Oxidative stress in systemic lupus erythematosus and allied conditions with vascular involvement

Identification of new hub- ferroptosis-related genes in Lupus Nephritis

Background: Lupus Nephritis (LN) is the primary causation of kidney injury in systemic lupus erythematosus (SLE). Ferroptosis is a programmed cell death. Therefore, understanding the crosstalk between LN and ferroptosis is still a significant challenge. Methods: We obtained the expression profile of LN kidney biopsy samples from the Gene Expression Omnibus database and utilised the R-project software to identify differentially expressed genes (DEGs). Then, we conducted a functional correlation analysis. Ferroptosis-related genes (FRGs) and differentially expressed genes (DEGs) crossover to select FRGs with LN. Afterwards, we used CIBERSORT to assess the infiltration of immune cells in both LN tissues and healthy control samples. Finally, we performed immunohistochemistry on LN human renal tissue. Results: 10619 DEGs screened from the LN biopsy tissue were identified. 22 hub-ferroptosis-related genes with LN (FRGs-LN) were screened out. The CIBERSORT findings revealed that there were significant statistical differences in immune cells between healthy control samples and LN tissues. Immunohistochemistry further demonstrated a significant difference in HRAS, TFRC, ATM, and SRC expression in renal tissue between normal and control groups. Conclusion: We developed a signature that allowed us to identify 22 new biomarkers associated with FRGs-LN. These findings suggest new insights into the pathology and therapeutic potential of LN ferroptosis inhibitors and iron chelators.

Homozygous MTHFR C667T carriers ≤45 years old develop central retinal vein occlusion five years earlier than wild type

PURPOSE

To assess age at 1st central retinal vein occlusion (CRVO) in carriers ≤ 45 years old of the methylenetetrahydrofolate reductase (MTHFR) C667T genotype compared to heterozygous and wild type, and to identify predictors of age at CRVO.

METHODS

Retrospective cohort study consisting of 18 MTHFR TT, 23 MTHFR TC and 28 MTHFR CC participants; information regarding age, sex, age at CRVO, history of dyslipidaemia, hypertension, smoking and plasma HC measured by immunoassay were collected.

RESULTS

Age at CRVO was lower in MTHFR TT than MTHFR TC and CC (32 ± 6 vs 38 ± 5 vs 37 ± 6 years, respectively, p = 0.005); plasma HC was higher in MTHFR TT than in the other genotypes [14.4 (10.8, 19.6) vs 10.4 ((8.6,12.5) vs 8.5 ((7.5,9.8) μmol/l, p = 0.0002). Smoking (cigarettes/day) independently predicted age at CRVO (p = 0.039) and plasma HC (p = 0.005); smoking status (yes/no) predicted ischemic CRVO (p = 0.01) that was more common in the MTHFR TT group (p = 0.006).

CONCLUSIONS

Carriers of the MTHFR TT genotype ≤ 45 years old develop their 1st CRVO on average 5 years earlier than the MTHFR CC genotype; smoking contributes to the prematurity and severity of CRVO in MTHFR TT carriers.

The Role of the Oxidative State and Innate Immunity Mediated by TLR7 and TLR9 in Lupus Nephritis

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE) and is considered one of the leading causes of mortality. Multiple immunological pathways are involved in the pathogenesis of SLE, which makes it imperative to deepen our knowledge about this disease's immune-pathological complexity and explore new therapeutic targets. Since an altered redox state contributes to immune system dysregulation, this document briefly addresses the roles of oxidative stress (OS), oxidative DNA damage, antioxidant enzymes, mitochondrial function, and mitophagy in SLE and LN. Although adaptive immunity's participation in the development of autoimmunity is undeniable, increasing data emphasize the importance of innate immunity elements, particularly the Toll-like receptors (TLRs) that recognize nucleic acid ligands, in inflammatory and autoimmune diseases. Here, we discuss the intriguing roles of TLR7 and TLR9 in developing SLE and LN. Also included are the essential characteristics of conventional treatments and some other novel and little-explored alternatives that offer options to improve renal function in LN.

Juvenile patients with the homozygous MTHFR C677T genotype develop ischemic stroke 5 years earlier than wild type

To compare age at 1st ischaemic stroke (IS) in a cohort of juvenile (< 46 years of age) IS patients evaluated for the rs1801133 polymorphism (C → T677) of the methylene tetrahydrofolate reductase (MTHFR) gene; to identify predictors of age at IS and of type of cerebral vessel involvement, small vessel disease (SVD) vs large vessel disease (LVD) responsible for the IS; to evaluate possible associations between other clinical and laboratory variables. Retrospective cohort study on 82 MTHFR TT, 54 MTHFR TC and 34 MTHFR CC participants; data regarding age, sex, age at IS, history of dyslipidaemia, hypertension, smoking, migraine and homocysteine (HC) as well as neuroimaging were collected. Age at IS was lower in MTHFR TT than MTHFR TC and CC (35 ± 4 vs 38 ± 0 vs 40 ± 3 years, respectively, p = 0.002); plasma HC (median, interquartile range) was higher in MTHFR TT than in the other groups [16.7 (11.8, 28.6) vs 11.4 (8.2, 16.1) vs 9.8 (7.9, 1.3) respectively, p < 0.0001)] and was higher in SVD than LVD [17.4 (12.4, 32.5) vs  11.4 (8.8, 16.4) p < 0.0001]. MTHFR TT independently predicted age at IS (p = 0.0008) alongside smoking both as a categorical (p = 0.003) or continuous variable (p = 0.02), whereas HC independently predicted SVD as categorical (p = 0.01) and continuous variable (p < 0.0001). Smoking positively predicted plasma HC (p = 0.005) and negatively the activated partial thromboplastin ratio (aPTTr) (p = 0.02). Juvenile IS carriers of the MTHFR TT genotype develop their 1st occlusion on average 5 years earlier compared to the CC genotype; smoking contributes to this prematurity adversely affecting plasma HC and coagulation whereas plasma HC predicts IS secondary to SVD. Public health campaigns against smoking should highlight the prematurity of IS in the juvenile population.

Evaluation of thiol/disulfide hemostasis and serum Ischemia modified albumin as oxidative stress biomarkers in systemic lupus erythematosus patients: Relationship with major organ involvement and disease activity

OBJECTIVES

We aimed to compare thiol/disulfide hemostasis and serum ischemia-modified albumin (IMA) levels, which are indicators of oxidative stress (OS), in patients with systemic lupus erythematosus (SLE), with the healthy control (HC) group and to evaluate the relationship of these parameters with disease activity and major organ involvement.

MATERIAL-METHODS

Eighty-four SLE patients and 96 HCs were included in this study. The disease activity of SLE patients was calculated using The Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K). Patients with SLEDAI-2K ≤ 5 were classified as low disease activity (LDA) and those with SLEDAI-2K > 6 as high disease activity (HDA). Thiol/disulfide hemostasis was evaluated using a new automated method and natural thiol (NT), total thiol (TT), disulfide (SS) levels, SS/NT, SS/TT, NT/TT ratios, and serum IMA levels were recorded.

RESULTS

NT and TT levels were significantly lower (490.11 ± 123.61 vs 536.96 ± 86.05, p = 0.003) (532.56 ± 125.80 vs 565.72 ± 89.82, p = 0.046), SS level (21.22 ± 11.75 vs 13.37 ± 9.31, p < 0.001) was higher, and SS/TT (4.64 ± 2.93 vs 2.52 ± 1.82, p < 0.001) and SS/NT (4.12 ± 2.33 vs 2.35 ± 1.59, p < 0.001) ratios were significantly higher in SLE patients compared to HCs. IMA values were not different between the two groups (p = 0.920). NT (449.84 ± 136.98 vs 520.32 ± 104.11, p = 0.012) and TT levels (492.01 ± 138.45±562.97 ± 107.09, p = 0.013) were significantly lower and serum IMA levels (0.802 ± 0.089 vs 0.764 ± 0.040, p = 0.023) were significantly higher in SLE patients with HDA than in LDA patients. There was a weak negative correlation between NT (r = -0.284, p=0.009) (r = -0.291, p = 0.007) and TT levels (r = -0.281, p = 0.010) (r = -0.289, p = 0.008) and a weak positive correlation between IMA levels (r = 0.279, p = 0.011) (r = 0.263, p = 0.016) and SLEDAI-2K, and major organ involvement.

CONCLUSION

It is thought that thiol/disulfide hemostasis and IMA levels may be used as ideal biomarkers of OS in SLE patients and may reflect the disease activity and major organ involvement.

The Potential Role of Ferroptosis in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that is accompanied with autoantibody production and inflammation. Other features of SLE pathogenesis include iron accumulation, oxidative stress, and lipid peroxidation, which are also major biochemical characteristics of ferroptosis, a novel non-apoptotic regulated form of cell death. To date, ferroptosis has been demonstrated to be an important driver of lupus progression, and several ferroptosis inhibitors have therapeutic effect in lupus-prone mice. Given the emerging link between ferroptosis and SLE, it can be postulated that ferroptosis is an integral component in the vicious cycle of immune dysfunction, inflammation, and tissue damage in SLE pathogenesis. In this review, we summarize the potential links between ferroptosis and SLE, with the aim of elucidating the underlying pathogenic mechanism of ferroptosis in lupus, and providing a new promising therapeutic strategy for SLE.

Earlier onset of peripheral arterial thrombosis in homozygous MTHFR C677T carriers than in other MTHFR genotypes: a cohort study

To investigate whether age at first presentation of pure peripheral arterial thrombosis (PAT) in lower and upper limbs and in the splanchnic circulation occurs earlier in carriers of the methylenetetrahydrofolate reductase (MTHFR) T677T genotype compared to the heterozygous and wild type and to identify predictors of a possible earlier onset. Retrospective cohort study on 27 MTHFR TT, 29 MTHFR TC and 29 MTHFR CC participants; data regarding age, sex, age at PAT, clinical history (dyslipidaemia, hypertension, smoking, obesity) and homocysteine (HC) measured by immunoassay were collected. Age at PAT was lower in MTHFR TT than MTHFR TC and CC (43 ± 9 vs 47 ± 9 vs 51 ± 4 years, respectively, p = 0.02); plasma HC was higher in MTHFR TT than in the other groups (25 ± 19 vs 12.7 ± 6.7 vs 11.3 ± 3.3 μmol/l, respectively, p < 0.001) while the activated partial thromboplastin ratio (aPTTr) was lower in MTHFR TT than in other genotypes (0.90 ± 0.10 vs 0.97 ± 0.12 vs 0.97 ± 0.08 μmol/L p < 0.001). Among categorical variables, MTHFR TT and dyslipidaemia independently predicted age at AT (p = 0.01 & p = 0.03, respectively) whereas among the continuous variables HC independently predicted age at PAT (p = 0.02) as well as the aPTTr (p = 0.001); smoking predicted lower limb PAT (p = 0.005). MTHFR TT carriers develop their first PAT an average of 4 and 8 years earlier than MTHF CT and CC genotypes; MTHFR TT, dyslipidaemia and plasma HC contribute to the prematurity of the PAT while the interplay between elevated HC and smoking may affect type of arterial district occlusion.

Homozygous methylentetrahydrofolate reductase C667T genotype anticipates age at venous thromboembolism by one decade

The aim of the study was to compare age at first venous thromboembolism (VTE), plasma homocysteine and activated partial thromboplastin time ratio (aPTTr) amongst unprovoked VTE patients with the methylentetrahydrofolate reductase (MTHFR) C667T genotypes, and to identify predictors of age at first VTE, of plasma homocysteine and of the aPTTr; to evaluate whether heterozygous or homozygous prothrombin (PT) G20210A mutation lowered the age at first VTE when associated with MTHFR TT. Retrospective cohort study on 259 MTHFR TT, 76 MTHFR TC and 64 MTHFR CC participants with unprovoked VTE; each participant contributed age, sex, age at VTE, history of dyslipidaemia, hypertension, smoking, homocysteine (measured by enzyme immunoassay) and aPTTr (measured by standard coagulation assay). Age at first VTE was lower in MTHFR TT than MTHFR TC and CC (41 ± 14 vs. 50 ± 16 vs. 51 ± 12 years, respectively, P < 0.0001); plasma homocysteine was higher in MTHFR TT than in the other groups (22 ± 21 vs. 12 ± 11.6 vs. 10 ± 3.3 μmol/l, respectively, P = 0.0005) whilst aPTTr was not different. MTHFR TT independently predicted age at first VTE (P = 0.001), plasma homocysteine (P < 0.0001) alongside sex (P = 0.0007), age and smoking (P = 0.03 for both). Compound MTHFR TT with PT GA or AA had no lowering effect on age at first VTE compared with MTHFR TT alone (41 ± 13 vs. 41 ± 14 years). Plasma homocysteine inversely related to aPTTr in the MTHFR TT group (P = 0.003). MTHFR TT anticipates age at first VTE by an average of 10 years compared with MTHFR TC and CC genotypes.

Autoimmune haemolytic anaemia and antiphospholipid antibodies in paediatrics: a systematic review and meta-analysis

INTRODUCTION/OBJECTIVE

The relationship between autoimmune haemolytic anaemia (AIHA) and antiphospholipid antibodies (aPL) has never been addressed via a meta-analysis in the paediatric age group. We evaluated the link between AIHA and aPL in childhood systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS).

METHODS

EMBASE and PubMed were screened from inception to May 2020 and Peto's odds ratio for rare events was employed for the between group comparisons.

RESULTS

The meta-analysis included 11 articles for a total of 575 children: the pooled prevalence of AIHA was greater in (1) IgG aCL-positive than IgG aCL-negative children (39.7% vs 20.9%, p = 0.005); (2) in APS-positive than APS-negative SLE children (36.8% vs 13.2%, p = 0.01); and (3) in SLE-related APS than in primary APS children (53% vs 16.2%, p = 0.008).

CONCLUSIONS

The pooled prevalence of AIHA is greatest in SLE with aPL/APS, low-moderate in SLE without aPL/APS, and lowest in primary APS. Key Points • Antiphospholipid antibodies strongly relate to autoimmune haemolytic anaemia. • Autoimmune haemolytic anaemia is more common in systemic lupus erythematosus with antiphospholipid antibodies.

Antiphospholipid Antibodies and Autoimmune Haemolytic Anaemia: A Systematic Review and Meta-Analysis

The relationship between antiphospholipid antibodies (aPL) and autoimmune haemolytic anaemia (AIHA) has never been systematically addressed. The aim of this study is to assess the link between aPL and AIHA in adult systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). This study performed an EMBASE/PubMed search from inception to June 2019 and meta-analysis using Peto’s odds ratios. The pooled prevalence (PP) of IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA) was greater in AIHA +ve than AIHA −ve patients (34.7% vs. 27.6%, p = 0.03; 33.3% vs. 21.8%, p < 0.0001; 20.9% vs. 8.3%, p = 0.01). The PP of AIHA was greater in: (1) IgG and IgM aCL +ve than −ve patients (21.8% vs. 11.1%, p = 0.001 and 18.7% vs. 6.3%, p < 0.0001), (2) in SLE related APS than in primary APS patients (22.8% vs. 3.9% p < 0.0001), (3) in APS +ve than APS −ve SLE patients (23.2% vs. 8.4%, p = 0.01), and (4) in thrombotic APS than non-thrombotic APS/SLE patients (26.8% vs. 10%, p = 0.03). The PP of IgG/IgM aCL and LA was greater in DAT +ve than DAT −ve patients (42.4% vs. 12.8%, p < 0.0001; 26.2% vs. 12.8%, p = 0.03 and 29.2% vs. 15.7%, p = 0.004 respectively). It was found that AIHA prevalence is maximal in SLE with aPL/APS, low-moderate in SLE without aPL and minimal in PAPS. Moreover, AIHA is rightly included among the classification criteria for SLE but not for APS/aPL. The significance of an isolated DAT positivity remains unclear in this setting

The role of oxidative and nitrosative stress in the pathology of osteoarthritis: Novel candidate biomarkers for quantification of degenerative changes in the knee joint

Osteoarthritis (OA) is the most frequently diagnosed joint disorder worldwide with increasing prevalence and crucial impact on the quality of life of affected patients through chronic pain, decreasing mobility and invalidity. Although some risk factors, such as age, obesity and previous joint injury are well established, the exact pathogenesis of OA on a cellular and molecular level remains less understood. Today, the role of nitrosative and oxidative stress has not been investigated conclusively in the pathogenesis of OA yet. Therefore, the objective of this study was to identify biological substances for oxidative and nitrosative stress, which mirror the degenerative processes in an osteoarthritic joint. 69 patients suffering from a diagnosed knee pain participated in this study. Based on the orthopedic diagnosis, patients were classified into an osteoarthritis group (OAG, n=24) or in one of two control groups (meniscopathy, CG1, n=11; anterior cruciate ligament rupture, CG2, n=34). Independently from the study protocol, all patients underwent an invasive surgical intervention which was used to collect samples from the synovial membrane, synovial fluid and human serum. Synovial biopsies were analyzed histopathologically for synovitis (Krenn-Score) and immunohistochemically for detection of end products of oxidative (8-isoprostane F2α) and nitrosative (3-nitrotyrosine) stress. Additionally, the fluid samples were analyzed for 8-isoprostane F2α and 3-nitrotyrosine by competitive ELISA method. The analyzation of inflammation in synovial biopsies revealed a slight synovitis in all three investigated groups. Detectable concentrations of 3-nitrotyrosine were reported in all three investigated groups without showing any significant differences between the synovial biopsies, fluid or human serum. In contrast, significant increased concentrations of 8-isoprostane F2α were detected in OAG compared to both control groups. Furthermore, our data showed a significant correlation between the histopathological synovitis and oxidative stress in OAG (r=0.728, P<0.01). There were no significant differences between the concentrations of 8-isoprostane F2α in synovial fluid and human serum. The findings of the current study support the hypothesis that oxidative and nitrosative stress are components of the multi-factory pathophysiological formation of OA. It seems reasonable that an inflammatory process in the synovial membrane triggers the generation of oxidative and nitrosative acting substances which can lead to a further degradation of the articular cartilage. Based on correlations between the observed degree of inflammation and investigated biomarkers, especially 8-isoprostane F2α seems to be a novel candidate biomarker for OA. However, due to the finding that also both control groups showed increased concentrations of selected biomarkers, future studies have to validate the diagnostic potential of these biomarkers in OA and in related conditions of the knee joint.

Isoprostane in systemic sclerosis: A systematic review and meta-analysis

OBJECTIVES

To further the knowledge of oxidative stress in systemic sclerosis (SSc), we performed a systematic review and meta-analysis on studies measuring isoprostane, a vasoactive agent deriving from arachidonic acid and implicated in the vasculopathy of SSc.

METHODS

Systematic search following the PRISMA guidelines in PubMed and EMBASE between January-1990/December-2017 using the terms: oxidative stress, isoprostane, systemic sclerosis and scleroderma.

RESULTS

After the screening process, 8 studies including 240 SSc patients and 192 controls were included in the systematic review and meta-analysis, 6 investigating urinary and 2 serum isoprostane: random effect meta-analysis revealed isoprostane overgeneration in SSc (p < .001) with wide heterogeneity (I² = 75%). Subgroup analysis on urinary isoprostane favoured excess excretion in SSc (p = .009) with slightly lower heterogeneity (I² = 67%); further subgroup analysis according to unit of measurement revealed no increased isoprostane excretion when expressed as pg/mg creatinine but increased when expressed as pmol/mmol creatinine (p = .05) with medium heterogeneity (I² = 32%). Subgroup analysis on serum isoprostane favoured overproduction in SSc (p < .0001) with no heterogeneity.

CONCLUSION

There is some evidence for isoprostane overgeneration in SSc that confirms the occurrence of oxidative stress in this setting: further prospective studies with specified outcomes are needed to evaluate the prognostic value of this functional biomarker.

Protective Effects of Hydroxychloroquine against Accelerated Atherosclerosis in Systemic Lupus Erythematosus

Cardiovascular (CV) morbidity and mortality are a challenge in management of patients with systemic lupus erythematosus (SLE). Higher risk of CV disease in SLE patients is mostly related to accelerated atherosclerosis. Nevertheless, high prevalence of traditional cardiovascular risk factors in SLE patients does not fully explain the increased CV risk. Despite the pathological bases of accelerated atherosclerosis are not fully understood, it is thought that this process is driven by the complex interplay between SLE and atherosclerosis pathogenesis. Hydroxychloroquine (HCQ) is a cornerstone in treatment of SLE patients and has been thought to exert a broad spectrum of beneficial effects on disease activity, prevention of damage accrual, and mortality. Furthermore, HCQ is thought to protect against accelerated atherosclerosis targeting toll-like receptor signaling, cytokine production, T-cell and monocyte activation, oxidative stress, and endothelial dysfunction. HCQ was also described to have beneficial effects on traditional CV risk factors, such as dyslipidemia and diabetes. In conclusion, despite lacking randomized controlled trials unambiguously proving the protection of HCQ against accelerated atherosclerosis and incidence of CV events in SLE patients, evidence analyzed in this review is in favor of its beneficial effect.

Oxidized low-density lipoprotein and β2-glycoprotein I in patients with systemic lupus erythematosus and increased carotid intima-media thickness: implications in autoimmune-mediated atherosclerosis

Oxidative stress and LDL modification (oxLDL) are early pro-atherogenic events. OxLDL binds β2GPI producing immunogenic oxLDL/β2GPI complexes. Antibodies to these complexes have been associated with arterial thrombosis in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Circulating oxLDL/β2GPI complexes, IgG and IgM antibodies to these complexes were measured by ELISA in 30 SLE patients asymptomatic for cardiovascular disease (mean age 31 years) and 27 age/sex matched healthy controls. Carotid intima-media thickness (IMT) was measured by ultrasound in all patients and controls. Forty-seven percent of SLE presented plaques (median IMT of 0.65 ± 0.12 mm) while only 7% of the controls had plaques (median IMT of 0.50 ± 0.04 mm, P < 0.001). Median optical density (OD450nm) for oxLDL/β2GPI complexes in SLE was 0.244 ± 0.07, higher than controls (0.174 ± 0.09, P < 0.001). Median OD for IgG anti-oxLDL/β2GPI antibodies was also higher in SLE (0.297 ± 0.26) compared to controls (0.194 ± 0.07, P < 0.001) while the median OD for IgM antibodies in SLE (0.444 ± 0.46) was not different than controls (0.326 ± 0.22, P = 0.267). There was no correlation between IMT and oxLDL/β2GPI complexes, IgG or IgM antibodies, possibly reflecting the complex interrelationship between these serologic elements and tissue factors in the arterial wall. These results support the hypothesis that oxLDL/β2GPI complexes and IgG (not IgM) anti-oxLDL/β2GPI antibodies contribute to the development of autoimmune-mediated atherosclerosis

Atherogenic Oxidized Low-Density Lipoprotein/β2-Glycoprotein I (oxLDL/β2GPI) Complexes in Patients with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Oxidized low-density lipoprotein (oxLDL) interacts in vitro with β2-glycoprotein I ( β2GPI) via LDL-derived specific ligands forming oxLDL/ β2GPI complexes. Circulating oxLDL/ β2GPI complexes have been demonstrated in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Autoimmune vascular inflammation and oxidative stress contribute to oxLDL/ β2GPI complex formation. Immunohistochemical staining of atherosclerotic lesions suggest that these complexes are formed in the arterial wall and released into circulation. The demonstration of antibodies to oxLDL/ β2GPI complexes indicates that these complexes are immunogenic, and the coexistence of complexes and antibodies suggest an active pro-thrombotic/pro-atherogenic role in the development of autoimmune vascular complications. Circulating oxLDL/ β2GPI complexes can be measured by ELISA using a monoclonal antibody specific to complexed human β2GPI to capture β2GPI bound to oxLDL. An enzyme-conjugated monoclonal antibody to human Apo B 100 allows the specific detection of oxLDL/ β2GPI complexes. OxLDL/ β2GPI complexes were common in SLE and APS patients suggesting an underlying process of inflammation and oxidation. Using oxLDL/ β2GPI complexes as capture antigen, antibodies to oxLDL/ β2GPI can be measured by ELISA. Serum levels of IgG anti-oxLDL/ β2GPI antibodies were significantly higher in SLE patients with APS compared to SLE controls without APS. Further, high titers of these IgG antibodies were observed in APS patients with a history of arterial thrombosis. The presence of circulating oxLDL/ β2GPI complexes and IgG antibodies to these complexes indicates significant vascular injury and oxidative stress as well as an active role in autoimmune-mediated atherothrombosis.

An anti-DNA antibody prefers damaged dsDNA over native

DNA-protein interactions, including DNA-antibody complexes, have both fundamental and practical significance. In particular, antibodies against double-stranded DNA play an important role in the pathogenesis of autoimmune diseases. Elucidation of structural mechanisms of an antigen recognition and interaction of anti-DNA antibodies provides a basis for understanding the role of DNA-containing immune complexes in human pathologies and for new treatments. Here we used Molecular Dynamic simulations of bimolecular complexes of a segment of dsDNA with a monoclonal anti-DNA antibody's Fab-fragment to obtain detailed structural and physical characteristics of the dynamic intermolecular interactions. Using a computationally modified crystal structure of a Fab-DNA complex (PDB: 3VW3), we studied in silico equilibrium Molecular Dynamics of the Fab-fragment associated with two homologous dsDNA fragments, containing or not containing dimerized thymine, a product of DNA photodamage. The Fab-fragment interactions with the thymine dimer-containing DNA was thermodynamically more stable than with the native DNA. The amino acid residues constituting a paratope and the complementary nucleotide epitopes for both Fab-DNA constructs were identified. Stacking and electrostatic interactions were shown to play the main role in the antibody-dsDNA contacts, while hydrogen bonds were less significant. The aggregate of data show that the chemically modified dsDNA (containing a covalent thymine dimer) has a higher affinity toward the antibody and forms a stronger immune complex. These findings provide a mechanistic insight into formation and properties of the pathogenic anti-DNA antibodies in autoimmune diseases, such as systemic lupus erythematosus, associated with skin photosensibilization and DNA photodamage.

Protective effects of ascorbic acid against the genetic and epigenetic alterations induced by 3,5-dimethylaminophenol in AA8 cells

Exposure to monocyclic aromatic alkylanilines (MAAs), namely 2,6-dimethylaniline (2,6-DMA), 3,5-dimethylaniline (3,5-DMA) and 3-ethylaniline (3-EA), was significantly and independently associated with bladder cancer incidence. 3,5-DMAP (3,5-dimethylaminophenol), a metabolite of 3,5-DMA, was shown to induce an imbalance in cytotoxicity cellular antioxidant/oxidant status, and DNA damage in mammalian cell lines. This study was designed to evaluate the protective effect of ascorbic acid (Asc) against the cytotoxicity, reactive oxygen species (ROS) production, genotoxicity and epigenetic changes induced by 3,5-DMAP in AA8 Chinese Hamster Ovary (CHO) cells. In different cellular fractions, 3,5-DMAP caused alterations in the enzyme activities orchestrating a cellular antioxidant balance, decreases in reduced glutathione levels and a cellular redox ratio as well as increases in lipid peroxidation and protein oxidation. We also suggest that the cellular stress caused by this particular alkylaniline leads to both genetic (Aprt mutagenesis) and epigenetic changes in histones 3 and 4 (H3 and H4). This may further cause molecular events triggering different pathological conditions and eventually cancer. In both cytoplasm and nucleus, Asc provided increases in 3,5-DMAP-reduced glutathione levels and cellular redox ratio and decreases in the lipid peroxidation and protein oxidation. Asc was also found to be protective against the genotoxic and epigenetic effects initiated by 3,5-DMAP. In addition, Asc supplied protection against the cell cycle (G1 phase) arrest induced by this particular alkylaniline metabolite.

Alpha-chlorofatty Acid and coronary artery or aorta calcium scores in women with systemic lupus erythematosus. A pilot study

OBJECTIVE

Alpha-chlorofatty acid (α-ClFA) is one product of myeloperoxidase activity in vivo during atherogenesis and may be a biomarker for cardiovascular disease (CVD). We investigated if serum α-ClFA is associated with subclinical CVD as measured by coronary artery and aorta calcium scores (CAC and AC, respectively) in women with and without systemic lupus erythematosus (SLE).

METHODS

This pilot project analyzed baseline data from 173 women with SLE and 186 women without SLE participating in a 5-year longitudinal investigation of the Study of Lupus Vascular and Bone Long-term Endpoints (SOLVABLE). Data collection included demographic information, CVD and SLE risk factors, and laboratory assessments. Alpha-ClFA was measured in stored serum by liquid chromatography-mass spectrometry. CAC and AC were measured by computed tomography. Outcome measures were CAC and AC present (CAC > 0 or AC > 0) versus absent (CAC = 0 or AC = 0). Associations between risk factors and CAC or AC were tested with descriptive statistics and multivariate analyses.

RESULTS

Women with SLE had higher α-ClFA levels than women without SLE (42.0 fmol/25 µl ± 37.3 vs 34.5 fmol/25 µl ± 21.9; p = 0.020). In analyses including individual CVD risk factors, having SLE was independently associated with the presence of CAC (OR 3.42, 95% CI 1.72 to 6.78) but not AC. Alpha-ClFA was not associated with the presence of CAC or AC in patients with SLE.

CONCLUSION

SLE, but not serum α-ClFA, was associated with the presence of CAC in this pilot project.

Recombinant domain V of β2-glycoprotein I inhibits the formation of atherogenic oxLDL/β2-glycoprotein I complexes

β2-glycoprotein I (β2-GPI) is a plasma protein that interacts with oxidized low-density lipoproteins (oxLDL) via β2-GPI domain V to form oxLDL/β2-GPI complexes, potential autoantigens promoting atherogenesis in patients with antiphospholipid syndrome (APS). Such a interaction would expose β2-GPI domain I or/and IV, structures recognized by anti-β2-GPI autoantibodies. IgG immune complexes with oxLDL/β2-GPI complexes can interact with macrophages via Fcγ receptor, causing oxLDL/β2-GPI endocytosis and foam cell formation, contributing to atherosclerosis. Here, we use recombinant domain V to study the interaction between oxLDL and β2-GPI and hypothesized that domain V would interfere with this interaction thereby reducing oxLDL macrophage uptake and foam cell formation. The β2-GPI domain V sequence was expressed by using the Pichia pastoris expression system to obtain recombinant domain V of β2-GPI (P.rβ2-GPI DV). ELISA tests demonstrated that P.rβ2-GPI DV interacted with oxLDL via 7-ketocholesteryl-9-carboxynonanoate (oxLig-1), a negatively charged lipid moiety of oxLDL. The ω-carboxyl residue of oxLig-1 is required for the interaction. Serologic tests showed a significant increase in oxLDL and oxLDL/β2-GPI levels in patients with APS (p < 0.05 compared to controls). P.rβ2-GPI DV was able to bind oxLDL in high affinity and competitively inhibited native β2-GPI (nβ2-GPI) binding to free oxLDL as well as to oxLDL from the oxLDL/β2-GPI complexes. These observations suggest that P.rβ2-GPI DV may be used to inhibit the formation of the oxLDL/β2-GPI complexes, a potential approach for reducing foam cell development and mitigating atherogenesis in patients with APS. The present work provides a new effective strategy to prevent the progression of atherothrombotic vascular complications in APS patients.

The association among antioxidant enzymes, autoantibodies, and disease severity score in systemic lupus erythematosus: comparison of neuropsychiatric and nonneuropsychiatric groups

Background. Antioxidative capacity plays an important role in the severity of systemic lupus erythematosus (SLE), which is characterized by autoantibodies. This study aimed to determine the relationship among autoantibody titers, antioxidative stress reserve, and severity of SLE. Methods. The autoantibody titers, clinical markers, antioxidant enzyme levels, and disease activity index (SLEDAI-2k) of 32 SLE patients and 16 healthy controls were compared. We also compared both the neuropsychiatric (NPSLE) and nonneuropsychiatric (non-NPSLE) groups. Results. Superoxide dismutase in red blood cells was significantly lower in the SLE than in the control group. CRP levels are significant higher in SLE patients than in control group (P = 0.034). Among the autoantibodies, anti-U1RNP (P = 0.008), a-Sm (P = 0.027), and anti-ribosomal p (P = 0.028) significantly negatively correlated with glutathione levels. There has no significant correlation between SLE disease activity indexes (SLEDAI) and levels of C3, C4, and antioxidant enzymes. Conclusions. Erythrocyte superoxide dismutase is significantly lower in both NPSLE and non-NPSLE groups. SLE patients have both higher CRP and autoantibodies level and decreased superoxide dismutase level than the healthy control group.

Autoantibodies to Peroxiredoxin I and IV in Patients with Systemic Autoimmune Diseases

Anti-oxidative enzymes protect living bodies from various oxidative stresses. In the systemic autoimmune diseases, autoantibodies to oxidized molecules and to anti-oxidative enzymes have been reported. To promote understanding of the relationships between autoimmunity and oxidative stress, we here investigate whether autoimmunity to the anti-oxidative peroxiredoxin (Prxs) enzymes exists in patients with systemic autoimmune diseases. Specifically, we detected autoantibodies to recombinant Prx I and Prx IV respectively by ELISA and western blotting. Next, clinical parameters were compared between the anti-Prx I or IV-positive and-negative patients. We found that 33% of the 92 patients with autoimmune diseases tested possessed autoantibodies to Prx I (57% in systemic lupus erythematosus (SLE), 19% in rheumatoid arthritis (RA), 5% in Behçet disease, and 46% in primary vasculitis syndrome). In contrast, autoantibodies to Prx IV were detected in only 17% of the same patients. No significant correlation was found between occurrence of the two autoantibodies. Clinically, possession of anti-Prx I autoantibodies correlated with lower serum levels of CH50, C3, and C4. Taken together, our data demonstrate the existence of autoantibodies to Prxs for the first time. The autoantibodies to Prx I may be involved in the pathophysiology of systemic autoimmune diseases such as SLE and vasculitis.

Alpha 1-antitrypsin activity is markedly decreased in Wegener's granulomatosis

Alpha 1-antitrypsin (A1AT) is the most abundant proteinase inhibitor in plasma and the main inhibitor of Proteinase 3, the target antigen of antineutrophil cytoplasmic antibodies (ANCAs) that predominant in Wegeners' granulomatosis. Α1AT deficiency correlated with ANCA-associated vasculitis. This study explores the trypsin inhibitory capacity (TIC), specific activity, and phenotypic deficiency of Α1AT in Wegener's granulomatosis. Twenty-seven WG patients were studied. ANCA was tested by IIF and ELISA. Serum a1-anti-trypsin levels were quantified in WG patients and healthy controls by immunoturbidimetric assay. Serum TIC was assessed by the enzymatic colorimetric assay. Phenotypes of A1AT were detected by Isoelectric Focusing. A1AT concentration was equivalent in patients and controls; however, serum TIC (P = 0.001) and specific activity of A1AT (P = 0.001) were dramatically lower in WG patients. Five patients had deficient phenotypes of A1AT: MZ (n = 3), MS (n = 1) and SS (n = 1). This was correlated with an increase in the prevalence of deficient phenotypes of A1AT in WG (P = 0.01). Trypsin inhibitory capacity and specific activity of A1AT were decreased in WG patients and may be involve in disease pathogenesis and can worsen the clinical manifestations. This A1AT deficiency probably resulted from oxidative inactivation and/or enzymatic degradation of A1AT. This could result in localized deficiency of A1AT in vessel wall interfaces and lead to severe disease.

Lipid anti-lipid antibody responses correlate with disease activity in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti-lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE.

Oxidative stress and fatigue in systemic lupus erythematosus

Objective: The objective of this study is to investigate the relationship of oxidative stress to fatigue in systemic lupus erythematosus (SLE). Methods: Patients with a confirmed diagnosis of SLE by ACR criteria and healthy controls completed validated questionnaires to assess depression and fatigue. Fatigue was measured with the Fatigue Severity Scale (FSS) and the Profile of Fatigue (Prof-F). Visual analogue scales (VAS) were also used to assess fatigue and pain. Depression was measured with the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma F2-isoprostane was measured with gas chromatography/mass spectroscopy to assess oxidative stress. Evaluation included medical record review, physical exam and calculation of body mass index (BMI), disease activity (SLEDAI) and damage (SLICC) in the SLE patients. Results: Seventy-one SLE patients with low disease activity (mean SLEDAI = 1.62 standard error (SE) 0.37, range 0–8) were compared to 51 controls. Fatigue-limiting physical activity (defined as FSS ≥ 4) was present in 56% of patients and 12% of controls. F2-isoprostane was higher in SLE patients with fatigue compared to not-fatigued SLE subjects ( p = .0076) who were otherwise similar in ethnicity, disease activity and cardiovascular risk factors. Plasma F2-isoprostane was strongly correlated with FSS and Profile of Somatic Fatigue (Prof-S) ( p < .0001), VAS fatigue ( p = .005), CES-D ( p = .008) and with BMI ( p = .0001.) In a multivariate model, F2-isoprostane was a significant predictor of FSS after adjustment for age, BMI, pain and depression ( p = .0002). Conclusion: Fatigue in SLE patients with low disease activity is associated with increased F2-isoprostane. F2-isoprostane could provide a useful biomarker to explore mitochondrial function and the regulation of oxidative pathways in patients with SLE in whom fatigue is a debilitating symptom.

Estimated Creatinine Clearance, Homocysteine and High Sensitivity-C-Reactive Protein Levels Determination for Early Prediction of Nephropathy and Atherosclerosis Risk In Type 2 Diabetic Patients

Type 2 diabetes mellitus (T2D) patients are increased risk for cardiovascular disease (CVD) and chronic kidney disease (CKD). Many studies had demonstrated that CKD is significantly associated with CVD. We aim to indicate the using estimated creatinine clearance (eCrCl), homocysteine (tHcy), and high sensitivity-C-reactive protein (hs-CRP) levels, may have an impact on the interpretation risk for nephropathy and CVD. eCrCl was using the Cockroft-Gault formula, eCrCl levels were stratified according to the Kidney Disease Outcome Quality Initiative definition. We measured serum tHcy, hs-CRP, and the other biochemical variables in 54 T2D patients compared with 40 age matched healthy controls (NDM). T2D patients were significantly lower eCrCl than NDM (P < 0.05). T2D patients also showed significantly higher in tHcy, hs-CRP, and MDA levels than NDM subjects (P < 0.05). The eCrCl was significantly correlated with tHcy and hs-CRP levels in T2D patients (r = -0.504, P < 0.001; r = -0.282, P = 0.047). eCrCl had an impact on interpretation for CKD, especially in T2D patients. Decrease eCrCl concomitant with increased in tHcy, hs-CRP, and MDA levels may present a higher risk for future diabetic nephropathy and CVD.

Nature and nurture of catalytic antibodies

Immunoglobulins (antibodies) frequently express constitutive functions. Two such functions are nucleophilic catalysis and the reversible binding to B-cell superantigens. Constitutive or "naturally-occurring" antibodies are produced spontaneously from germline genetic information. The antibody structural elements mediating the constitutive functions have originated over millions of years of phylogenic evolution, contrasting with antigen-driven, somatic sequence diversification of the complementarity determining regions (CDR) that underlies the better-known high affinity antigen binding function of antibodies. Often, the framework regions (FRs) play a dominant role in antibody constitutive functions. Catalytic antibody subsets with promiscuous, autoantigen-directed and microbe-directed specificities have been identified. Mucosal antibodies may be specialized to express high-level catalytic activity against microbes transmitted by the mucosal route, exemplified by constitutive production of IgA class antibodies in mucosal secretions that catalyze the cleavage of HIV gp120. Catalytic specificity can be gained by constitutive noncovalent superantigen binding at the FRs and by adaptive development of noncovalent classical antigen or superantigen binding, respectively, at the CDRs and FRs. Growing evidence suggests important functional roles for catalytic antibodies in homeostasis, autoimmune disease and protection against infection. Adaptive antibody responses to microbial superantigens are proscribed underphysiological circumstances. Covalent electrophilic immunogen binding to constitutively expressed nucleophilic sites in B-cell receptors bypasses the restriction on adaptive antibody production, and simultaneous occupancy of the CDR binding site by a stimulatory antigenic epitope can also overcome the downregulatory effect of superantigen binding at the FRs. These concepts may be useful for developing novel vaccines that capitalize and improve on constitutive antibody functions for protection against microbes.

Dyslipidaemia in rheumatological autoimmune diseases

Autoimmunity forms the basis of many rheumatological diseases, and may contribute not only to the classical clinical manifestations but also to the complications. Many of the autoimmune rheumatological diseases, including rheumatoid arthritis and systemic lupus erythematosus are associated with an excess cardiovascular morbidity and mortality. Much of this excess cardiovascular risk can be attributed to atherosclerotic disease. Atherosclerosis is a complex pathological process, with dyslipidaemia and inflammation fundamental to all stages of plaque evolution. The heightened inflammatory state seen in conjunction with many rheumatological diseases may accelerate plaque formation, both through direct effects on the arterial wall and indirectly through inflammation-mediated alterations in the lipid profile. Alongside these factors, antibodies produced as part of the autoimmune nature of these conditions may lead to alterations in the lipid profile and promote atherosclerosis. In this review, we discuss the association between several of the rheumatological autoimmune diseases and dyslipidaemia, and the potential cardiovascular impact this may confer.

Interaction between oxidative stress and high-density lipoprotein cholesterol is associated with severity of coronary artery calcification in rheumatoid arthritis

OBJECTIVE

To test the hypothesis that oxidative stress is increased in patients with rheumatoid arthritis (RA) due to increased inflammation and contributes to the pathogenesis of atherosclerosis.

METHODS

The independent association between urinary F₂-isoprostane excretion, a measure of oxidative stress, and RA was tested using multiple linear regression models in 169 patients with RA and 92 control subjects, frequency matched for age, race, and sex. The relationship between F₂-isoprostane excretion and coronary calcium, a marker of atherosclerosis, was examined in multivariable proportional odds logistic regression models that also assessed the interactions between oxidative stress and low-density lipoprotein and high-density lipoprotein (HDL) cholesterol.

RESULTS

F₂-isoprostane excretion was significantly higher in patients with RA (median 2.75 [interquartile range (IQR) 1.60-4.06] ng/mg creatinine) than in control subjects (median 1.86 [IQR 1.25-2.62] ng/mg creatinine; adjusted P = 0.006). In patients with RA, F₂-isoprostanes were positively correlated with body mass index (P < 0.001), but not with disease activity or mediators of inflammation such as the Disease Activity Score in 28 joints or serum tumor necrosis factor α, interleukin-6, and C-reactive protein concentrations in adjusted multivariable models (P > 0.05 for all). In patients with RA, F₂-isoprostanes significantly modified the effect of HDL cholesterol on coronary calcification (P = 0.02 for interaction) after adjustment for age, sex, and race. As F₂-isoprostane levels increased, HDL lost its protective effect against coronary calcification.

CONCLUSION

Oxidative stress measured as F₂-isoprostane excretion was higher in patients with RA than in control subjects. Among patients with RA, higher F₂-isoprostane excretion and HDL cholesterol concentrations interacted significantly and were positively associated with the severity of coronary calcification.

The embryotoxicity of sera from patients with autoimmune diseases on post-implantation rat embryos in culture persists during remission and is not related to oxidative stress

We evaluated the embryolethality and embryotoxicity of sera from patients suffering from autoimmune diseases during remission on post-implantation rat embryos cultured on these sera and determined the association between the patients' clinical history, high blood levels of specific antibodies, medications, and oxidative stress parameters. One hundred and eighty, 10.5-day-old rat embryos were cultured in their yolk sacs in 33 sera of systemic lupus erythematosus (SLE)/antiphospholipid syndrome (APS) patients, and compared with 84 embryos cultured in rat sera and 88 embryos cultured in control human sera. The sera proved to be lethal and embryotoxic but not teratogenic resulting in smaller yolk sacs and embryos, lower protein level and lower developmental score. Significantly less embryos cultured in 'toxic' SLE/APS sera had peak 2 of low molecular weight antioxidants (LMWA) wave, implying a delayed maturation of the antioxidant defense. Lower peak 1 of LMWA correlated with a history of recurrent abortions. Embryonic levels of superoxide dismutase (SOD) and catalase (CAT) did not correlate with sera toxicity, patients' clinical history or specific antibodies. We conclude that SLE/APS patients' clinical remission did not prevent death or developmental delay accompanied by later appearance of peak 2 of LMWA in post-implantation rat embryo cultures. The normal levels of the antioxidant enzymes evaluated may indicate that sera toxicity is not related to oxidative stress.

Accelerated atherosclerosis in systemic lupus erythematosus and other connective tissue diseases

Connective tissue diseases are associated with increased morbidity and mortality related to a higher rate of cardiovascular events and higher prevalence of subclinical atherosclerosis. Atherosclerosis is now considered a multifactorial process where autoimmunity and chronic inflammation play an important pathogenic role. In systemic autoimmune rheumatic diseases in general, and in systemic lupus erythematosus in particular, atherosclerosis cannot be explained by traditional cardiovascular risk factors alone. Cellular and humoral mechanisms, together with specific factors associated with the disease itself and/or its treatments, have been advocated to explain the acceleration of arterial wall organic damage in these patients. Endothelial dysfunction, carotid intima-media thickness and plaque evaluations provide accurate detection of atherosclerotic process at a preclinical stage, before appearance of clinical disease, allowing preventive measure introduction with the aim to modify the cardiovascular risk in subjects with systemic autoimmune rheumatic diseases.

Oxidized-LDL/beta(2)-glycoprotein I complexes are associated with disease severity and increased risk for adverse outcomes in patients with acute coronary syndromes

Oxidized low-density lipoprotein (oxLDL)/beta(2)-glycoprotein I (beta2GPI) complexes have been implicated in atherogenesis. oxLDL/beta2GPI complexes were measured in 339 patients with suspected acute coronary syndromes. Approximately 68% had angiographically documented coronary artery disease (CAD) and significantly higher mean + or - SD levels of oxLDL/beta2GPI (3.75 + or - 6.31 U/mL) than patients with normal coronary arteries (2.21 + or - 3.03 U/mL; P = .0026). Patients with severe CAD had significantly higher mean + or - SD levels of oxLDL/beta2GPI (8.71 + or - 12.87 U/mL) compared with the overall mean of 3.25 U/mL (P < .05) and a significantly higher rate (28.9%) of adverse events than the overall rate of 11.2% (P < .05). Patients with adverse events had higher mean + or - SD levels of oxLDL/beta2GPI (4.05 + or - 5.38 U/mL) than patients without adverse events (3.15 + or - 5.53; P = .029). The relative risk for adverse events in higher oxLDL/beta2GPI quartiles was 3.1 (95% confidence interval, 1.0-9.1; P = .06) for quartile 3 and 3.5 (95% confidence interval, 1.2-10.4; P = .02) for quartile 4. Our results support the concept that oxLDL/beta2GPI complexes are associated with severity of CAD and a 3.5-fold increased risk for adverse outcomes.

Diagnostic and prognostic biomarker discovery strategies for autoimmune disorders

Current clinical, laboratory or radiological parameters cannot accurately diagnose or predict disease outcomes in a range of autoimmune disorders. Biomarkers which can diagnose at an earlier time point, predict outcome or help guide therapeutic strategies in autoimmune diseases could improve clinical management of this broad group of debilitating disorders. Additionally, there is a growing need for a deeper understanding of multi-factorial autoimmune disorders. Proteomic platforms offering a multiplex approach are more likely to reflect the complexity of autoimmune disease processes. Findings from proteomic based studies of three distinct autoimmune diseases are presented and strategies compared. It is the authors' view that such approaches are likely to be fruitful in the movement of autoimmune disease treatment away from reactive decisions and towards a preventative stand point.

Oxidative stress and homocysteine metabolism in patients with lupus nephritis

The objective of this study was to compare oxidative status and homocysteinemia in patients with lupus nephritis (LN) and in controls. Total antioxidant capacity (TAC), reactive oxygen species (ROS), homocysteine and related vitamins were measured in 68 patients with LN and in 50 controls. LN patients had lower TAC (p = 0.05) and higher ROS and homocysteinemia (p = 0.01) than controls. TAC, significantly lower in active than in quiescent LN (p = 0.01), was correlated with albuminemia (p = 0.02), inversely with proteinuria (p = 0.01) and anti-DNA antibodies (p = 0.004). ROS values, higher both in active and in inactive LN, correlated with age (p = 0.02), C-reactive protein (CRP) (p = 0.0005) and inversely with prednisone dosage (p = 0.05). At multivariate analysis, CRP (p = 0.04) and age (p = 0.005) were independent ROS predictors. Homocysteine, higher in active than in quiescent LN (p = 0.016) and in patients with antiphospholipid antibodies (p=0.05), correlated with serum creatinine (p = 0.00001) and proteinuria (p = 0.015). At multivariate analysis serum creatinine (p = 0.006) and active nephritis (p = 0.003) were independent predictors of hyperhomocysteinemia. Patients with LN showed impaired oxidative status, even without clinical signs of renal activity. ROS production may be counterbalanced by adequate antioxidant capacity in some patients with quiescent LN. The association of hyperhomocysteinemia and antiphospholipid antibodies positivity may increase the risk of cardiovascular and/or thrombotic events in LN patients.

Immunogenic oxidized low-density lipoprotein/beta2-glycoprotein I complexes in the diagnostic management of atherosclerosis

Oxidized low-density lipoprotein (oxLDL) promotes atherosclerosis through a complex interaction of inflammatory and immunologic factors that lead to macrophage lipid uptake and foam cell formation. OxLDL interacts with beta2-glycoprotein I (beta2GPI) forming oxLDL/beta2GPI complexes. These complexes may be formed in the arterial intima during atherogenesis and released into the circulation. Autoantibodies against oxLDL/beta2GPI complexes have been demonstrated in patients with systemic lupus erythematosus and/or antiphospholipid syndrome, and shown to be significantly associated with arterial thrombosis. The observation that monoclonal autoantibodies against oxLDL/beta2GPI complexes significantly increased the oxLDL uptake by macrophages strongly suggests that such IgG autoantibodies are pro-atherogenic. In this article, we review the recent progress in our understanding of LDL oxidation, oxLDL/beta2GPI complex formation, and immune regulation of atherogenesis.

Evidence for chronically elevated serum protein oxidation in systemic lupus erythematosus patients

Serum protein oxidation levels in people with the autoimmune disease systemic lupus erythematosus (SLE) have previously been shown to (a) be elevated at a single time point and (b) correlate with disease activity. This study investigates whether this elevation is a chronic phenomenon, by analysis of multiple serum samples collected from 21 SLE patients and nine controls over a period of up to 38 months. Protein thiols were chronically decreased in SLE patients with stable or variable disease activity compared to controls, whilst protein-bound carbonyls and glycine were chronically increased. 2D-gel analysis of carbonyl distribution showed albumin and immunoglobulins to be particularly affected. In SLE patients with stable disease activity, higher long-term protein oxidation correlated with higher long-term disease activity. SLE patients with variable disease activity exhibited varying correlations between protein oxidation and disease activity markers. These results further support a role for oxidative stress in the pathogenesis of SLE.

Autoimmune-mediated atherothrombosis

Autoimmune vascular inflammation and oxidative stress (lipid peroxidation) are common in systemic autoimmune diseases and contribute to the oxidative modification of low-density lipoprotein (oxLDL) and oxLDL/beta2GPI complex formation. Circulating oxLDL/beta2GPI complexes have been detected in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The presence of antibodies to oxLDL/beta2GPI complexes indicates that these complexes are immunogenic, and the coexistence of complexes and antibodies has pointed to an active proatherogenic role in the development of autoimmune vascular complications. Immunohistochemical staining of atherosclerotic lesions suggest that these complexes are formed in the arterial wall and released into circulation. The in vitro macrophage uptake of oxLDL/beta2GPI complexes was significantly increased in the presence of antiphospholipid antibodies, either beta2GPI-dependent anticardiolipin or anti-beta2GPI antibodies, suggesting that macrophage Fcgamma receptors are involved in lipid intracellular influx and foam cell formation. These findings provide an explanation for the accelerated development of atherosclerosis seen in SLE and APS. The presence of circulating oxLDL/beta2GPI complexes and IgG antibodies to these complexes indicate significant vascular injury and oxidative stress as well as an active role in autoimmune-mediated atherothrombosis.

Anti-atherogenic and anti-inflammatory properties of high-density lipoprotein are affected by specific antibodies in systemic lupus erythematosus

OBJECTIVE

To determine whether antibodies against high-density lipoprotein (aHDL) and apolipoprotein A-I (aApo A-I) interfere with the anti-atherogenic functions of high-density lipoprotein (HDL) and relate to disease activity and damage in SLE.

METHODS

Seventy-seven SLE patients were compared with an age- and sex-frequency matched control group. Immunoglobulin G (IgG) aHDL, IgG aApoA-I, soluble vascular cell and intracellular cell adhesion molecules (VCAM-1 and ICAM-1, respectively) were measured by ELISA, paraoxonase (PON) activity by spectrophotometry, nitric oxide (NOx) metabolites by the Griess reaction, and total anti-oxidant capacity (TAC) by chemiluminescence.

RESULTS

Compared with controls, SLE patients showed higher titres of IgG aHDL (P < 0.0001) and IgG aApo A-I (P < 0.0001), lower PON activity (P < 0.0001), increased NOx (P < 0.0001), VCAM-1 (P < 0.0001) and ICAM-1 (P = 0.0008) and lower TAC (P = 0.0006). Titres of IgG aHDL positively correlated with IgG aApo A-I (r = 0.64, P < 0.0001), NOx (r = 0.32, P = 0.007), inversely correlated with PON activity (r = -0.34, P = 0.002) and TAC (r = -0.43, P = 0.0004) and were independently associated with ICAM-1 (t = 3.509, P = 0.001). IgG aApo A-I titres correlated positively with NO (r = 0.37, P = 0.007), inversely with PON activity (r = -0.31, P = 0.006), TAC (r = -0.47, P < 0.0001) and were independently associated with HDL (t = -2.747, P = 0.008) and VCAM-1 (t = 3.311, P = 0.002), the latter alongside NOx (T = 2.271, P = 0.02). Elevated titres of IgG aHDL and IgG aApo A-I and reduced PON activity related to increased disease score (BILAG) and damage index (SLICC/ACR DI).

CONCLUSION

In SLE, IgG aHDL and aApo A-I associate with disease activity and damage and interfere with the anti-oxidant and anti-inflammatory functions of HDL favouring atherogenesis.

High-density lipoproteins are abnormal in young women with uncomplicated systemic lupus erythematosus

Little is known about qualitative abnormalities of high-density lipoproteins (HDL) in systemic lupus erythematosus (SLE). We studied distribution and composition of HDL subclasses in 30 premenopausal women with uncomplicated SLE, and 18 controls matched for age and sex. Plasma and HDL lipids were determined by colorimetric enzymatic assays, HDL size distribution by native gradient polyacrylamide gel electrophoresis (PAGE) and apolipoproteins in HDL by sodium dodecyl sulphate denaturing PAGE. Compared with controls, SLE patients had significantly lower proportions of HDL2b (−14.7%) and higher proportions of HDL3b (+8.8%) and HDL3c (+23.3%). Cholesteryl ester (−18%) and apolipoprotein AI (−9%) were lower, whereas triglycerides (+32%) and apolipoprotein E (+27%) were higher in SLE HDL ( P < 0.05; for all). In the whole population, stepwise regression analysis showed that only insulin concentrations (R2 = 0.327) and plasma total apo AI (R2 = 0.114) accounted independently to the variance in HDL size. This study shows that HDL distribution and composition are abnormal in non-complicated SLE patients. These HDL abnormalities have been reported to be associated to impaired atheroprotective properties of HDL and prevalence of coronary heart disease. Therefore, they may contribute to the premature atherosclerosis observed in young women with SLE.

Skin autofluorescence is increased in systemic lupus erythematosus but is not reflected by elevated plasma levels of advanced glycation endproducts

OBJECTIVES

To examine whether skin advanced glycation endproducts (AGEs) accumulation, plasma levels of AGEs-N(epsilon)-carboxymethyllysine (CML) and N(epsilon)-carboxyethyllysine (CEL)-and serum levels of soluble receptor for AGEs (sRAGE) are elevated in SLE patients compared with controls, and whether these parameters are related to disease activity and endothelial cell (EC) activation.

METHODS

Ten SLE patients (9 women, age 34 +/- 13 yrs, mean +/- s.d.) and 10 age- and sex-matched controls were included. Patients were analysed during inactive as well as active disease. Skin AGE accumulation was estimated using ultraviolet-A (UV-A) light for measurement of autofluorescence obtained by Excitation-Emission matrix Scanner (AF-EEMS). Levels of CML and CEL were determined by tandem mass spectrometry. Levels of sRAGE and of soluble vascular cell adhesion molecule-1 (sVCAM-1) were determined by ELISAs.

RESULTS

Skin AF-EEMS was increased in SLE patients compared with controls (P < 0.05). Levels of CML and CEL were comparable between patients and controls and were not influenced by disease activity. sRAGE and sVCAM-1 levels were higher in quiescent SLE patients compared with controls (P < 0.05) and increased further during active disease (P < 0.05). In patients with quiescent disease and controls, sRAGE levels correlated to sVCAM-1 levels (r = 0.579, P = 0.007).

CONCLUSIONS

Skin AGEs and levels of sRAGE and sVCAM-1 were elevated in SLE patients, whereas levels of CML and CEL were comparable with controls. As sRAGE even further increased during endothelial activation, it might be hypothesized that sRAGE acts as a decoy receptor. Why this proposed mechanism is insufficient to prevent increased AGE accumulation in the skin of SLE patients has to be established.

[Oxidative stress and atherosclerosis]

Oxidative stress is a continuous level of oxidative damage in animal cells, which is caused by an overabundance of reactive oxygen species or a decline in antioxidant ability against them. Oxidative stress increases with individual risk factors of atherosclerosis such as obesity, hypertension, hyperlipidemia, diabetes and smoking. Thus, oxidative stress is considered to play a key role in the pathogenesis of atherosclerosis. This review discusses the relationship between oxidative stress and atherosclerosis based on findings from our research group. We have found that atherosclerotic lesions are formed in the aorta of mice fed a high-cholesterol and high-linoleic diet, in parallel with elevated serum lipid peroxide levels. This model is useful for primary screening of antiatherosclerotic agents with antioxidative activity. One notable factor in the development of atherosclerosis is oxidized low-density lipoprotein (OxLDL). In order to examine OxLDL levels in blood, we have developed anion-exchange HPLC methods using stepwise elution. Using these methods, we have found that OxLDL markedly increases in a rat model of metabolic syndrome, in animals exposed to cigarette smoke and in smokers in parallel with other oxidative stress markers. These oxidative stress markers have been attenuated by administration of several antioxidants. In addition, we have found that smoking accelerates atherogenesis in the aorta of apoE-deficient mice and this acceleration can be ameliorated by administration of vitamin E. These observations suggest that antioxidant supplementation may be an effective therapeutic strategy for metabolic syndrome and smoking-induced diseases in which elevated oxidative stress plays a pivotal role.

Antibodies toward high-density lipoprotein components inhibit paraoxonase activity in patients with systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) have an increased incidence of vascular disease, and oxidative stress is recognized as an important feature in this condition, despite the underlying mechanisms not being fully understood. In these patients, an interaction between lipoproteins and the immune system has been suggested, but most studies have only looked at antibodies against oxidized low-density lipoproteins. This study was undertaken to determine the presence of antibodies directed against high-density lipoproteins (HDL) and to identify a possible association between these antibodies and paraoxonase (PON), an antioxidant enzyme present in HDL. Plasma from 55 patients with SLE was collected and IgG aHDL and antiapolipoprotein A-I (aApo A-I) antibodies were assessed by enzyme-linked immunosorbent assay. Standardization of the method was performed in a control population of 150 healthy subjects. Plasma levels above 5 standard deviations of the mean of the control population were considered positive. PON activity was assessed by quantification of p-nitrophenol formation (micromol/mL/min). Patients with SLE had higher titers of aHDL (P < 0.0001) and aApo A-I (P < 0.0001) antibodies, and lower PON activity (P < 0.0001) than healthy controls. There was also a direct correlation between the titers of aHDL and aApo A-I antibodies (r = 0.61; P < 0.0001). PON activity was inversely correlated with aApo A-I (P = 0.0129) antibody levels. Anti-HDL and aApo A-I antibodies from patients with high titers were isolated and subsequently incubated with human HDL. These antibodies reduced PON activity up to a maximum of 70.2% and 78.4%, respectively. This study showed the presence of aHDL and aApo A-I antibodies in patients with SLE. These antibodies were associated with reduced PON activity in plasma, and the in vitro inhibition assay confirmed a direct inhibition of the enzyme activity.

Oxidative stress in systemic lupus erythematosus: relationship to disease activity and symptoms

Oxidative stress may play a role in the pathogenesis of systemic lupus erythematosus (SLE). We examined the hypothesis that oxidative stress was associated with indices of lupus disease activity and severity of symptoms. Urinary F2 isoprostane excretion, a validated marker of oxidative stress, was measured in 95 patients with SLE and 103 healthy controls. Outcome measures included SLEDAI and SLICC scores, the modified health assessment questionnaire, the fatigue severity scale (FSS), and visual analogue scales (VAS) for fatigue, pain and overall disease activity. F2 isoprostane excretion was compared in patients and controls, and its relationship with clinical variables in SLE examined. F2 isoprostane excretion did not differ significantly among patients with lupus (2.7 +/- 2.3 ng/mg Cr) and control subjects (2.2 +/- 1.4 ng/mg Cr) (P = 0.70). In patients with lupus, F2 isoprostane concentrations were independently associated with higher patient reported disease activity (VAS) (OR = 1.52, P = 0.01), fatigue (FSS, OR = 1.52, P = 0.03) and lower quality of life (OR = 0.73, P = 0.05), but not with objective markers or inflammation or disease activity. In conclusion, F2 isoprostane excretion is associated with patient-reported symptoms in SLE but not with measures of inflammation, SLEDAI or SLICC. Oxidative stress may contribute to debilitating symptoms such as fatigue in SLE.