Elevated circulating asymmetric dimethylarginine levels in rheumatoid arthritis: a systematic review and meta-analysis

Mutations in microRNA-128-2-3p identified with amplification-free hybridization assay

We describe a quantitative detection method for mutated microRNA in human plasma samples. Specific oligonucleotides designed from a Peyrard-Bishop model allowed accurate prediction of target:probe recognition affinity and specificity. Our amplification-free tandem bead-based hybridization assay had limit of detection of 2.2 pM. Thereby, the assay allowed identification of single-nucleotide polymorphism mismatch profiles in clinically relevant microRNA-128-2-3p, showing terminal mutations that correlate positively with inflammatory colitis and colorectal cancer.

Elevated VCAM-1, MCP-1 and ADMA serum levels related to pulmonary fibrosis of interstitial lung disease associated with rheumatoid arthritis

Introduction: Early diagnosis of interstitial lung disease (ILD) associated with rheumatoid arthritis (RA) constitutes a challenge for the clinicians. Pulmonary vasculopathy is relevant in the development of interstitial lung disease. Accordingly, we aimed to explore the role of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1) and asymmetric dimethylarginine (ADMA), key molecules in the vasculopathy, as potential biomarkers of pulmonary fibrosis in RA-ILD⁺. Methods: We included 21 RA-ILD⁺ patients and two comparative groups: 25 RA-ILD^- patients and 21 idiopathic pulmonary fibrosis (IPF) patients. Serum levels of the molecules were determined by ELISA, and mRNA expression was quantified by qPCR. Results: VCAM-1, MCP-1 and ADMA serum levels were increased in RA-ILD⁺ patients in relation to RA-ILD^- and IPF patients. Additionally, RA-ILD⁺ patients exhibited increased CCL2 (gene encoding MCP-1) and decreased PRMT1 (gene related to ADMA synthesis) mRNA expression in relation to RA-ILD^- patients. A lower expression of VCAM1, CCL2, and PRMT1 was observed in RA-ILD⁺ patients when compared with those with IPF. Furthermore, MCP-1 serum levels and PRMT1 mRNA expression were positively correlated with RA duration, and ADMA serum levels were positively associated with C-reactive protein in RA-ILD⁺ patients. Conclusion: Our study suggests that VCAM-1, MCP-1 and ADMA could be considered as useful biomarkers to identify ILD in RA patients, as well as to discriminate RA-ILD⁺ from IPF, contributing to the early diagnosis of RA-ILD⁺.

Asymmetric Dimethylarginine: a Key Player in the Pathophysiology of Endothelial Dysfunction, Vascular Inflammation and Atherosclerosis in Rheumatoid Arthritis?

Patients with rheumatoid arthritis (RA), a chronic and disabling autoimmune condition that is characterized by articular and extra-articular manifestations and a pro-inflammatory and pro-oxidant state, suffer from premature atherosclerosis and excessive cardiovascular disease burden. A key step in the pathogenesis of atherosclerosis is impaired synthesis of the endogenous messenger nitric oxide (NO) by endothelial cells which, in turn, alters local homeostatic mechanisms and favors vascular damage and plaque deposition. While the exact mechanisms of endothelial dysfunction in RA remain to be established, there is good evidence that RA patients have relatively high circulating concentrations of the methylated arginine asymmetric dimethylarginine (ADMA), a potent endogenous inhibitor of endothelial NO synthase (eNOS). This review discusses the biological and pathophysiological role of ADMA, the interplay between ADMA, inflammation and oxidative stress, and the available evidence on the adverse impact of ADMA on endothelial function and atherosclerosis and potential ADMA-lowering therapies in RA patients.

Endothelial Dysfunction in Patients with Rheumatoid Arthritis: the Role of Hypertension

PURPOSE OF REVIEW

To review the data on the role of endothelial dysfunction and the impact of hypertension as a potent mediator of cardiovascular disease in patients with rheumatoid arthritis (RA).

RECENT FINDINGS

RA represents the most common autoimmune rheumatic disorder and is characterized by chronic systemic inflammation predisposing to cardiovascular complications. Cardiovascular mortality is increased among patients with RA and represents the leading cause of death. Although the exact prevalence is debated, hypertension is increased in RA. Hypertension acts synergistically with chronic inflammation and accounts, at least partially, for the increased cardiovascular morbidity in this group of patients. Endothelial dysfunction is considered a primary process in the pathogenesis of hypertension and cardiovascular diseases and contributes significantly to the development and progression of the associated micro- and macrovascular complications. Even though several studies in patients with RA have shown the presence of endothelial dysfunction with traditional methods, novel biochemical and vascular methods for the evaluation of endothelial dysfunction have been scarcely applied. In addition, it remains unclear whether and to which extent endothelial dysfunction in RA is present regardless of concomitant hypertension, even in well-controlled patients. Hypertension, endothelial dysfunction, and chronic systemic inflammation appear as a mutually reinforcing triad aggravating cardiovascular risk in patients with RA. Detection of endothelial dysfunction in patients with RA in the early stages further aiming at the development of novel therapeutic targets might contribute to prevention of cardiovascular complications and remains under investigation.

Genetic regulation of dimethylarginines and endothelial dysfunction in rheumatoid arthritis

Rheumatoid Arthritis (RA) confers an increased cardiovascular disease (CVD) risk which accounts for much of the premature morbidity and mortality observed in this population. Alterations in vascular function and morphology leading to increased atherosclerotic burden are considered the main drivers of CVD in RA individuals with systemic inflammation playing a key role in the dysregulation of endothelial homeostasis and initiation of vascular injury. Dimethylarginines are endogenous inhibitors of nitric oxide (NO) synthase and have emerged as novel, independent biomarkers of CVD in a wide range of conditions associated with vascular pathology. In RA several reports have demonstrated abnormal dimethylarginine metabolism attributable to various factors such as systemic inflammation, decreased degradation or upregulated synthesis. Although a causal relationship between dimethylarginines and vascular damage in RA has not been established, the tight interrelations between inflammation, dimethylarginines and endothelial dysfunction suggest that determination of dimethylarginine regulators may shed more light in the pathophysiology of the atherosclerotic process in RA and may also provide new therapeutic targets. The Alanine-Glyoxylate Aminotransferase 2 (AGTX2)-dependent pathway is a relatively recently discovered alternative pathway of dimethylarginine catabolism and its role on RA-related atherosclerotic disease is yet to be established. As factors affecting dimethylarginine concentrations linked to CVD risk and endothelial dysfunction are of prominent clinical relevance in RA, we present preliminary evidence that gene variants of AGTX-2 may influence dimethylarginine levels in RA patients and provide the rationale for larger studies in this field.