dimethylarginine and Arthritis--Rheumatoid

Rheumatoid arthritis (RA) is associated with high rates of cardiovascular events mainly due to coronary and cerebrovascular atherosclerotic disease. Asymmetric (ADMA) and symmetric (SDMA) dimethylarginines are endogenous inhibitors of nitric oxide synthase and have been repeatedly linked with adverse cardiovascular outcomes in the general population and various disease settings. Alanine-glyoxylate aminotransferase 2 (AGTX2) is considered an alternative metabolic pathway contributing to the clearance of dimethylarginines in humans. The aim of the current study was to investigate the effect of specific AGXT-2 gene polymorphisms on circulating levels of ADMA or SDMA in patients with RA. Serum ADMA and SDMA levels were measured in 201 individuals with RA [median age: 67 years (IQR: 59-73), 155 females]. Two single nucleotide polymorphisms (SNPs) in the AGXT-2 gene-rs37369 and rs28305-were genotyped. Distributions of SDMA and ADMA were skewed, hence comparisons across the gene polymorphisms were performed using Kruskal-Wallis tests, and summarized using medians and interquartile ranges. Univariable analysis did not demonstrate a significant difference in the levels of SDMA or ADMA amongst the different genotypic groups of either rs37369AGXT2 (p = 0.800, 0.977) or rs28305AGXT2 (p = 0.463, 0.634). In multivariable analyses, ADMA levels were found to be significantly associated with erythrocyte sedimentation rate and estimated glomerular filtration rate, whilst SDMA levels were significantly associated with estimated glomerular filtration rate and quantitative insulin sensitivity check index. After adjustments for these factors, the relationship between the AGXT2 gene variants and both ADMA and SDMA remained non-significant. Our study in a well-characterized RA population did not show an association between serum concentrations of dimethylarginines and genetic variants of the AGXT2 gene.

Topics: Aged; Arginine; Arthritis, Rheumatoid; Female; Humans; Male; Middle Aged; Polymorphism, Single Nucleotide; Transaminases

To examine associations between asymmetric (ADMA), symmetric dimethylarginine (SDMA) and ADMA:SDMA ratio with assessments of endothelial function and coronary artery perfusion in RA patients.. ADMA and SDMA levels were measured in 197 RA individuals [144 (77.4%) females, median age: 66 years (quartiles: 59-73)]. Patients underwent assessments of microvascular endothelium-dependent and endothelium-independent function, macrovascular endothelium-dependent and endothelium-independent function and vascular morphology (pulse wave analysis, carotid intima-media thickness (cIMT), and carotid plaque). Coronary perfusion was assessed by subendocardial viability ratio (SEVR).. SEVR correlated with SDMA (r = 0.172, p = 0.026) and ADMA:SDMA (r = -0.160, p = 0.041) in univariable analysis, but not in multivariable analysis accounting for confounding factors. Neither ADMA:SDMA ratio nor SDMA were significantly correlated with microvascular or macrovascular endothelial function, or with arterial stiffness and cIMT. Within subgroup of patients (n = 26) with high inflammatory markers, a post-hoc analysis showed that SDMA and the ADMA:SDMA ratio were significantly associated with endothelium-dependent microvascular function in univariable analysis, with Pearson's r correlation coefficients of -0.440 (p = 0.031) and 0.511 (p = 0.011), respectively. Similar finding were established between ADMA:SDMA ratio and arterial stiffness in univariable analysis, with Pearson's r of 0.493, (p = 0.024).. Dimethylarginines were not found to be significantly associated with several assessments of vascular function and morphology in patients with RA, however, post-hoc analysis indicates that there may be associations in patients with raised inflammatory markers. Our results suggest that dysregulated NO metabolism may not be the sole mechanism for the development of preclinical atherosclerosis in RA.

Topics: Aged; Arginine; Arthritis, Rheumatoid; Atherosclerosis; Carotid Artery Diseases; Carotid Intima-Media Thickness; Endothelium, Vascular; Female; Humans; Immunoenzyme Techniques; Microvessels; Middle Aged; Models, Biological; Prospective Studies; Pulse Wave Analysis; Ultrasonography

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by systemic inflammation of the joints and extra-articular tissues. The incidence of cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with RA. Despite the development of new therapeutics targeting the articular manifestations, the relief of the cardiovascular burden is still an unmet medical need during the management of RA. So, the early prognosis of RA-associated CVD plays a crucial role in improving the clinical outcomes of RA patients. Recently, circulating dimethylarginines have gained attention as potential biomarkers for CVDs. Here, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for simultaneous quantification of creatinine, arginine, and dimethylarginines in human serum within 2 mins by isotope dilution mass spectrometry. This method employed a protein precipitation method for rapid sample preparation, trichloroacetic acid (TCA)-based ion pairing chromatography for fast analyte separation, and multiple reaction monitoring (MRM) with stable isotope-labeled internal standards (ISs) for simultaneous quantitation. To assure the quality, our method was validated against the FDA guidelines for lower limit of quantitation (0.2 µM), linearity (square of coefficient correlation>0.99), precision (intra-&inter-assay imprecision < 10 %), accuracy (intra-&inter-assay inaccuracy < 10 %), sample preparation recovery (recovery ≥ 90 %), stability (instability < 10 %), matrix effect (signal suppression < 55 %), and carryover ( < 0.01 %). Afterward, we applied the validated method to a retrospective cross-sectional study. We aimed to evaluate the utility of serological dimethylarginines as potential cardiovascular biomarkers in the development of RA-associated CVD. Our results revealed that the serological ratio of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), an indicator of physiological arginine methylation status, was significantly elevated in patients with RA. This finding might provide value in detecting CVD to improve clinical outcomes in RA management.

Topics: Arginine; Arthritis, Rheumatoid; Biomarkers; Cardiovascular Diseases; Chromatography, Liquid; Cross-Sectional Studies; Humans; Retrospective Studies; Tandem Mass Spectrometry

Symmetric (SDMA) and asymmetric (ADMA) dimethylarginines have emerged as novel biomarkers of cardiovascular disease (CVD) in several disease settings associated with atherosclerosis. Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by high CVD mortality and morbidity. ADMA and SDMA levels are abnormal in RA patients, but their correlation with assessments of endothelial function and structure remains unknown. We aimed to investigate whether SDMA and ADMA are associated with carotid intima media thickness (cIMT) and arterial stiffness as well as non-invasive assessments of in vivo micro- and macrovascular endothelial function in RA patients with high systemic inflammatory load.. ADMA and SDMA levels were measured using immunoassays in 197 RA individuals. Twenty-six of these [23 (86.4%) females, median age 70, quartiles (60, 73)] were identified as having high inflammatory markers [erythrocyte sedimentation rate (ESR) >25 mm/hr and C-reactive protein (CRP) > 5 mg/L], and were compared to the remainder of the cohort. Patients underwent assessments of microvascular endothelium-dependent and endothelium-independent function [laser Doppler imaging with iontophoresis of acetylcholine (Ach) and sodium-nitroprusside (SNP) respectively], macrovascular endothelium-dependent and endothelium-independent function (flow-mediated dilatation and glyceryl-trinitrate-mediated dilation respectively), and vascular morphology [pulse wave analysis, and carotid intima media thickness (cIMT)].. Significant interactions with inflammation were detected in the associations between ACh and both SDMA (p = 0.014) and ADMA:SDMA ratio (p = 0.027), as well as between SNP and SDMA (p = 0.042) and between arterial stiffness and ADMA:SDMA (p = 0.036), with the associations being stronger in the patients with high inflammatory markers in each case.. Besides their emerging role as markers of endothelial dysfunction SDMA and ADMA may promote endothelial injury in RA as mediators of the adverse effects of systemic inflammation on micro- and macrovasculature respectively in patients with active disease.

Topics: Aged; Arginine; Arthritis, Rheumatoid; Carotid Artery Diseases; Carotid Intima-Media Thickness; Cohort Studies; Endothelium, Vascular; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoassay; Inflammation; Laser-Doppler Flowmetry; Male; Middle Aged; Pulse Wave Analysis; Receptor Cross-Talk; Vascular Stiffness

 Endothelial dysfunction and accumulation of asymmetric dimethylarginine (ADMA) have been identified as independent predictors of future cardiovascular events in patients with coronary artery disease..  The aim of the study was to investigate the factors that determine increased accumulation of ADMA, an endogenous inhibitor of nitric oxide synthesis, in patients with rheumatoid arthritis (RA)..  We studied 46 consecutive patients with RA (39 women, 7 men; mean age, 57 years [range, 23-75 years]) with active disease (mean Disease Activity Score 28 [DAS28], 5.2), without clinically overt cardiovascular disease and 50 controls matched for age, sex, hypertension, blood cholesterol, and glucose. We assessed the plasma levels of ADMA, symmetric dimethylarginine (SDMA), L‑arginine, and the marker of oxidative stress, 8‑iso‑prostaglandin F2α (8‑iso‑PGF2α). .  ADMA and SDMA levels were significantly higher in the RA group than in controls (0.58 ±0.081 vs. 0.46 ±0.045 μmol/l, P <0.0001; 0.45 ±0.07 vs. 0.36 ±0.046 μmol/l, P <0.0001; respectively). ADMA levels in the RA group correlated positively with fibrinogen (r = 0.70, P <0.00001), C‑reactive protein (CRP; r = 0.88, P <0.00001), DAS28 (r = 0.44, P = 0.002) and Health Assessment Questionnaire scores (r = 0.39, P = 0.008), but not with age, renal function, or the medications used. 8‑iso‑PGF2α correlated positively with ADMA (r = 0.82), SDMA (r = 0.72), CRP (r = 0.76), fibrinogen (r = 0.57) (all, P <0.0001) and DAS28 (r = 0.44, P = 0.003). Regression analysis models showed that CRP was the only independent predictor of 8‑iso‑PGF2α and ADMA levels in RA..  Our study is the first to show positive associations between plasma ADMA levels and the production of 8‑isoprostanes and CRP in RA.

Topics: Adult; Aged; Arginine; Arthritis, Rheumatoid; Biomarkers; Female; Humans; Inflammation; Male; Middle Aged; Nitric Oxide; Oxidative Stress; Young Adult

Topics: Amidohydrolases; Arginine; Arthritis, Rheumatoid; Case-Control Studies; Enzyme Activation; Humans; Oxidation-Reduction; Spondylarthritis

We have recently demonstrated elevated plasma levels of an endogenous nitric oxide synthase inhibitor, asymmetric dimethyl-L-arginine (ADMA), and its association with carotid atherosclerosis in rheumatoid arthritis (RA). Both an elevated risk of myocardial infarction and increased levels of anticitrullinated protein antibodies (ACPAs), specific for RA, had been shown to precede the onset of clinical RA symptoms. Therefore, our aim was to verify the hypothesis that ADMA accumulation might accompany raised ACPAs titers in RA of short duration (< or = 3 years). Twenty patients (16 women, 4 men; mean age, 45 +/- 12 years; mean disease duration, 2.3 +/- 0.5 years) with active RA despite chronic disease-modifying antirheumatic medication, free of cardiovascular disease or atherosclerotic risk factors, were studied. Plasma levels of ADMA and its stereoisomer, symmetric dimethyl-L-arginine (SDMA), were assayed by liquid chromatography/tandem mass spectrometry. The ACPAs were measured by a second-generation enzyme-linked immunosorbent assay. In addition to routine biochemical assays, plasma concentrations of tumor necrosis factor alpha, monocyte chemoattractant protein-1, and vascular cell adhesion molecule-1 soluble form were analyzed with respective enzyme-linked immunosorbent assays. A significant positive correlation between levels of ACPAs and ADMA (r = .60, P = .005), but not SDMA (r = -.02, P = .9), was found. Neither ADMA nor SDMA was correlated to any of the clinical or biochemical parameters reflecting disease activity and inflammatory activation. Thus, excessive ADMA accumulation accompanies elevated ACPAs levels in patients with RA of short duration free of cardiovascular disease or risk factors.

Topics: Antibodies; Arginine; Arthritis, Rheumatoid; Blood Proteins; Citrulline; Humans; Nitric Oxide; Time Factors

Anti-Sm antibodies, identified in 1966 by Tan and Kunkel, are highly specific serological markers for systemic lupus erythrematosus (SLE). Anti-Sm reactivity is found in 5-30% of SLE patients, depending on the autoantibody detection system and the racial background of the SLE population. The Sm autoantigen complex comprises at least nine different polypeptides. All of these core proteins can serve as targets of the anti-Sm B-cell response, but most frequently the B and D polypeptides are involved. Because the BB'Sm proteins share cross-reactive epitopes (PPPGMRPP) with U1 specific ribonucleoproteins, which are more frequently targeted by antibodies that are present in patients with mixed connective tissue disease, the SmD polypeptides are regarded as the Sm autoantigens that are most specific to SLE. It was recently shown that the polypeptides D1, D3 and BB' contain symmetrical dimethylarginine, which is a component of a major autoepitope within the carboxyl-terminus of SmD1. In one of those studies, a synthetic dimethylated peptide of SmD1 (amino acids 95-119) exhibited significantly increased immunoreactivity as compared with unmodified SmD1 peptide. Using immobilized peptides, we confirmed that the dimethylated arginine residues play an essential role in the formation of major SmD1 and SmD3 autoepitopes. Moreover, we demonstrated that one particular peptide of SmD3 represents a more sensitive and more reliable substrate for the detection of a subclass of anti-Sm antibodies. Twenty-eight out of 176 (15.9%) SLE patients but only one out of 449 (0.2%) control individuals tested positive for the anti-SmD3 peptide (SMP) antibodies in a new ELISA system. These data indicate that anti-SMP antibodies are exclusively present in sera from SLE patients. Thus, anti-SMP detection using ELISA represents a new serological marker with which to diagnose and discriminate between systemic autoimmune disorders.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Antinuclear; Antibody Specificity; Antigen-Antibody Reactions; Arginine; Arthritis, Rheumatoid; Autoantigens; Autoimmune Diseases; Cross Reactions; Dermatomyositis; DNA; Enzyme-Linked Immunosorbent Assay; Epitope Mapping; Epitopes; Epstein-Barr Virus Nuclear Antigens; Female; Humans; Lupus Erythematosus, Systemic; Male; Middle Aged; Mixed Connective Tissue Disease; Polymyositis; Reference Standards; Ribonucleoproteins, Small Nuclear; Scleroderma, Systemic; Sensitivity and Specificity; Sjogren's Syndrome; snRNP Core Proteins