An observational study of endothelial function in early arthritis

Relevance of circulating markers of endothelial activation for cardiovascular risk assessment in rheumatoid arthritis: a narrative review

Rheumatoid arthritis (RA) is associated with excessive cardiovascular mortality secondary to premature atherosclerosis, in which endothelial activation (EA) plays a central role. EA is characterized by loss of vascular integrity, expression of leucocyte adhesion molecules, transition from antithrombotic to prothrombotic phenotype, cytokines production, shedding of membrane microparticles and recruitment of endothelial progenitor cells. As EA is an early event in atherogenesis, circulating markers of EA are putative markers of vascular pathology and cardiovascular (CV) risk. After a presentation of biology of EA, the present review analyzed the available data regarding changes in EA markers in RA in link with the vascular pathology and CV events, discussed their relevance as biomarkers of CV risk and proposed future directions.

Anti-inflammatory protective effect of ADAMTS-13 in murine arthritis models

BACKGROUND

Patients with rheumatoid arthritis (RA) have frequent thrombotic events with endothelial dysfunction. Von Willebrand factor (VWF) has been shown to bind neutrophil extracellular traps (NETs) and NETs are part of RA etiology.

OBJECTIVES

This study aims to elucidate whether this prothrombotic status exacerbates inflammation in arthritis. Here we focus on the involvement of A Disintegrin And Metalloprotease with ThromboSpondin type 1 motif, member 13 (ADAMTS-13), an enzyme cleaving VWF and its effect on NET deposition and RA development.

METHODS

We evaluated the influence of the Adamts13 gene and recombinant human ADAMTS-13 (rhADAMTS-13) on arthritis in the mouse models of collagen-induced arthritis (CIA). We also assessed VWF and NETs in synovial tissue.

RESULTS

Several Adamts13-/- mice developed arthritis, while Adamts13+/+ siblings did not. Synovial tissue from Adamts13-/- showed accumulation of NETs. Treatment of DBA/1 J mice, an arthritis-susceptible strain, with well-tolerated doses of rhADAMT13 reduced arthritis incidence and alleviated the severity of arthritis. Mice treated with rhADAMT13 presented less serum interleukin 6 and less bone erosion determined by micro-computed tomography. The effects on arthritis severity were observed both when administering rhADAMTS-13 prophylactically and also when given after arthritis has developed. In both conditions, rhADAMTS-13 reduced VWF and NET deposition on proliferated synovial tissue evaluated by immunoblotting.

CONCLUSIONS

Our results demonstrate the inhibitory role of Adamts13 in murine arthritis and the effectiveness of rhADAMTS-13 treatment. Additionally, this study suggests that deposition of VWF in the synovium and subsequent pathogenic NET retention promotes arthritis. Treatment with rhADAMTS-13 provides a potential therapeutic approach targeting inflammation and pro-thrombotic state in arthritis.

A prospective, longitudinal monocentric study on laser Doppler imaging of microcirculation: comparison with macrovascular pathophysiology and effect of adalimumab treatment in early rheumatoid arthritis

Increased cardiovascular (CV) morbidity and mortality have been found in rheumatoid arthritis (RA). Tumour necrosis factor α (TNF-α) inhibitors may improve vascular function. In the first part of this study, we determined microcirculation during postoocclusive reactive hyperemia (PORH) representing endothelial function. In a nonselected population (n = 46) we measured flow-mediated vasodilation (FMD) of the brachial artery and laser Doppler flow (LDF) by ultrasound. Among LDF parameters, we determined TH1 (time to half before hyperemia), TH2 (time to half after hyperemia), Tmax (time to maximum) and total hyperemic area (AH). We measured von Willebrand antigen (vWF:Ag) by ELISA. In the second part of the study, we assessed the effects of adalimumab treatment on microcirculatory parameters in 8 early RA patients at 0, 2, 4, 8 and 12 weeks. We found significant positive correlations between FMD and LDF Tmax (R = 0.456, p = 0.002), FMD and TH2 (R = 0.435, p = 0.004), and negative correlation between vWF:Ag and Tmax (R = - 0.4, p = 0.009) and between vWF:Ag and TH2 (R = - 0.446, p = 0.003). Upon adalimumab therapy in early RA, TH2 times improved in comparison to baseline (TH2_baseline = 26.9 s vs. TH2_4weeks = 34.7 s, p = 0,032), and this effect prolonged until the end of treatment (TH2_8weeks = 40.5, p = 0.026; TH2_12weeks = 32.1, p = 0.013). After 8 weeks of treatment, significant improvement was found in AHa (AH_baseline = 1599 Perfusion Units [PU] vs. AH_8weeks = 2724 PU, p = 0.045). The PORH test carried out with LDF is a sensitive option to measure endothelial dysfunction. TH1 and TH2 may be acceptable and reproducible markers. In our pilot study, treatment with adalimumab exerted favorable effects on disease activity, endothelial dysfunction and microcirculation in early RA patients.

Application of Non-invasive Imaging in Inflammatory Disease Conditions to Evaluate Subclinical Coronary Artery Disease

PURPOSE OF REVIEW

Traditional risk models, such as the Framingham risk score, fail to capture the increased cardiovascular disease risk seen in patients with chronic inflammatory diseases. This review will cover imaging modalities and their emerging applications in assessing subclinical cardiovascular disease for both research and clinical care in patients with chronic inflammatory diseases.

RECENT FINDINGS

Multiple imaging modalities have been studied to assess for subclinical cardiovascular disease via functional/physiologic, inflammatory, and anatomic assessment in patients with chronic inflammatory diseases. The use of imaging to evaluate subclinical cardiovascular disease in patients with chronic inflammatory diseases has the potential to capture early sub-clinical atherosclerosis, to improve risk stratification of future cardiovascular events, and to guide effective disease management.

Microvascular endothelial dysfunction in rheumatoid arthritis

The systemic autoimmune disease rheumatoid arthritis (RA) is characterized by increased cardiovascular mortality and morbidity and is an independent cardiovascular risk factor. Cardiovascular diseases (CVDs) result from accelerated atherogenesis, which is a consequence of endothelial dysfunction in the early stages of the disease. Endothelial dysfunction is a functional and reversible alteration of endothelial cells and leads to a shift in the properties of the endothelium towards reduced vasodilation, a pro-inflammatory state, and proliferative and prothrombotic properties. In RA, endothelial dysfunction can occur in the large vessels (such as the conduit arteries) and in the small vessels of the microvasculature, which supply oxygen and nutrients to the tissue and control inflammation, repair and fluid exchange with the surrounding tissues. Growing evidence suggests that microvascular endothelial dysfunction contributes to CVD development, as it precedes and predicts the development of conduit artery atherosclerosis and associated risk factors. As such, numerous studies have investigated microvascular endothelial dysfunction in RA, including its link with disease activity, disease duration and inflammation, the effect of treatments on endothelial function, and possible circulating biomarkers of microvascular endothelial dysfunction. Such findings could have important implications in the cardiovascular risk management of patients with RA.

The fact not to ignore: Mean blood pressure is the main predictor of increased arterial stiffness in patients with systemic rheumatic diseases

PURPOSE

We aimed to evaluate the association between carotid-radial pulse wave velocity (PWV), augmentation index (AIx), and flow-mediated dilatation (FMD) of the brachial artery and factors potentially influencing them in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc).

MATERIAL AND METHODS

316 patients diagnosed with RA (32%), SLE (20%), SSc (16%) and 156 controls (32%) were included in the study. Parameters of arterial stiffness AIx and PWV were obtained using applanation tonometry. FMD reflecting endothelial function was measured by ultrasound.

RESULTS

AIx was increased in all three diseases (p<0.0001), but no differences were found between rheumatic diseases. In most of the RA cases PWV values were abnormal (on average by 0.52m/sec higher than in controls), while in SSc patients FMD values were diminished (p=0.006). Mean blood pressure (MBP) was the most consistent predictive factor in all three diseases, influencing both PWV and AIx, although patient age was also important in variation of AIx. The disease activity score (DAS28) was relevant only in RA patients. Furthermore, SLE disease activity index in SLE or Rodnan skin thickness score had no statistical significance in SSc and inflammatory markers.

CONCLUSIONS

Both, PWV and AIx are dependent on MBP and age DAS28 may affect AIx in RA patients, while other disease or inflammatory markers are unlikely to have any effect. MBP is one of the main cardiovascular risk factors affecting the arterial stiffness in RA, SLE and SSc patients therefore controlling MBP in systemic rheumatic disease patients is mandatory.

Endothelial Dysfunction in Rheumatoid Arthritis: Mechanistic Insights and Correlation with Circulating Markers of Systemic Inflammation

Objectives

To determine mechanisms involved in endothelial dysfunction (ED) during the course of arthritis and to investigate the link between cytokines, chemokines and osteoprotegerin.

Approach and Results

Experiments were conducted on aortic rings at day 4 (preclinical), day 11 (onset of disease), day 33 (acute disease) and day 90 (chronic disease) after adjuvant-induced arthritis (AIA) in Lewis rats. At day 4, the unique vascular abnormality was a reduced norepinephrine-induced constriction. At day 11, endothelial function assessed by the relaxation to acetylcholine was normal despite increased cyclo-oxygenase-2 activity (COX-2) and overproduction of superoxide anions that was compensated by increased nitric oxide synthase (NOS) activity. At day 33, ED apparition coincides with the normalization of NOS activity. At day 90, ED was only observed in rats with a persisting imbalance between endothelial NOS and COX-2 pathways and higher plasma levels of IL-1β and TNFα. Plasma levels of IL-1β, TNFα and MIP-1α negatively correlated with Ach-induced relaxation throughout the course of AIA.

Conclusions

Our data identified increased endothelial NOS activity as an important compensatory response that opposes the ED in the early arthritis. Thereafter, a cross-talk between endothelial COX-2/NOS pathways appears as an important element for the occurrence of ED. Our results encourage determining the clinical value of IL-1β, TNFα and MIP-1α as biomarkers of ED in RA.

Collagen-induced arthritis increases inducible nitric oxide synthase not only in aorta but also in the cardiac and renal microcirculation of mice

Rheumatoid arthritis (RA) may promote endothelial dysfunction. This phenomenon requires further investigation, especially in collagen-induced arthritis (CIA), as it is considered the experimental model most similar to RA. The objectives of this study were to identify CIA-induced changes in noradrenaline (NE) and acetylcholine (ACh) responses in mice aortas that may suggest endothelial dysfunction in these animals. Moreover, we characterize CIA-induced modifications in inducible nitric oxide synthase (iNOS) expression in the aortas and cardiac and renal tissues taken from these mice that may be related to possible endothelial dysfunction. Male DBA/1J mice were immunized with 100 μg of emulsified bovine collagen type II (CII) plus complete Freund's adjuvant. Twenty-one days later, these animals received a boost of an additional 100 μg plus incomplete Freund's adjuvant. Fifteen days after the onset of the disease, aortic rings from CIA and control mice were challenged with NE and ACh in an organ bath. In these animals, iNOS was detected through immunohistochemical analysis of aorta, heart and kidneys. Plasma nitrite concentration was determined using the Griess reaction. CIA did not change NE or ACh responses in mice aorta but apparently increased the iNOS expression not only in aorta, but also in cardiac and renal microcirculation. In parallel, CIA reduced nitrite plasma concentration. In mice, CIA appears to increase the presence of iNOS in aorta, as well as in heart and in kidney microcirculation. This iNOS increase occurs apparently in parallel to a reduction of the bioavailability of NO. This phenomenon does not appear to change NE or ACh responses in aorta.

Inhibition of each module of connective tissue growth factor as a potential therapeutic target for rheumatoid arthritis

We previously reported the importance of connective tissue growth factor (CTGF) in rheumatoid arthritis (RA). CTGF contains four distinct modules connected in tandem, namely insulin-like growth factor-binding protein (IGFBP)-like, von Willebrand factor (vWF) type C repeat, thrombospondin type 1 (TSP-1) repeat, and carboxyl-terminal (CT) modules. The relationships between each of these modules of CTGF and RA remain unknown. Here, we analyzed how inhibition of each CTGF module affects the pathophysiology of RA. We conducted stimulation and suppression experiments on synovial cells (MH7A) obtained from patients with RA. Moreover, we examined angiogenesis by means of a tube-formation assay performed using human umbilical vein endothelial cells (HUVECs), and we used tartrate-resistant acid phosphatase (TRAP) staining to analyze osteoclastogenesis. Our results showed that M-CSF/RANKL-mediated osteoclastogenesis was enhanced when CTGF was added, but the effect of CTGF was neutralized by mAbs against CTGF modules 1-4. Furthermore, CTGF treatment of HUVECs induced formation of tubular networks, which resulted in acceleration of the angiogenesis of RA synoviocytes, and quantification showed that this tubular-network formation was also disrupted by anti-CTGF module 1-4 mAbs. Lastly, TNF-α enhanced the expression of CTGF and matrix metalloproteinase-3 (MMP3) in MH7A cells, and this enhancement was potently neutralized by mAbs against CTGF modules 1, 3 and 4. Thus, our results indicate that not only a mAb against CTGF but also mAbs against each specific module of CTGF might serve as potential therapeutic agents in the treatment of RA.

Chronic arthritis and cardiovascular disease: altered blood parameters give rise to a prothrombotic propensity

OBJECTIVE

Rheumatoid arthritis, and to a lesser extent ankylosing spondylitis and psoriatic arthritis, associates with increased morbidity and mortality due to cardiovascular complications. We hypothesized that the increased risk of cardiovascular disease is reflected by changes in blood parameters that are compatible with a prothrombotic propensity. To substantiate this notion, we performed an extensive literature search identifying such parameters.

METHODS

A search through PubMed (1970-2013) was done to find primary articles with the following search terms: rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis or synovial fluid. These were combined with keywords reflecting processes of atherothrombosis: atherosclerosis, cardiovascular disease, coagulation, endothelial, fibrinolysis, mean platelet volume, microparticle, platelet, platelet count and mass, thrombosis, and thrombus.

RESULTS

The published studies point to a multitude of blood-related processes that can contribute to a prothrombotic propensity in chronic inflammatory diseases. These include an increase in platelet mass; low-level platelet activation, enforced by interaction with leukocytes and the formation of proinflammatory cytokines; a locally activated endothelium; and an increased coagulant activity. Patient treatment with methotrexate or TNF-α blockers appears to result in normalization of several of these prothrombotic parameters.

CONCLUSION

This analysis provides a first identification of the mechanisms by which inflammatory arthritis can aggravate cardiovascular disease.

Endothelial dysfunction in chronic inflammatory diseases

Chronic inflammatory diseases are associated with accelerated atherosclerosis and increased risk of cardiovascular diseases (CVD). As the pathogenesis of atherosclerosis is increasingly recognized as an inflammatory process, similarities between atherosclerosis and systemic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel diseases, lupus, psoriasis, spondyloarthritis and others have become a topic of interest. Endothelial dysfunction represents a key step in the initiation and maintenance of atherosclerosis and may serve as a marker for future risk of cardiovascular events. Patients with chronic inflammatory diseases manifest endothelial dysfunction, often early in the course of the disease. Therefore, mechanisms linking systemic inflammatory diseases and atherosclerosis may be best understood at the level of the endothelium. Multiple factors, including circulating inflammatory cytokines, TNF-α (tumor necrosis factor-α), reactive oxygen species, oxidized LDL (low density lipoprotein), autoantibodies and traditional risk factors directly and indirectly activate endothelial cells, leading to impaired vascular relaxation, increased leukocyte adhesion, increased endothelial permeability and generation of a pro-thrombotic state. Pharmacologic agents directed against TNF-α-mediated inflammation may decrease the risk of endothelial dysfunction and cardiovascular disease in these patients. Understanding the precise mechanisms driving endothelial dysfunction in patients with systemic inflammatory diseases may help elucidate the pathogenesis of atherosclerosis in the general population.

Differential associations of inflammatory and endothelial biomarkers with disease activity in rheumatoid arthritis of short duration

Objectives. To estimate endothelial dysfunction in patients with rheumatoid arthritis (RA) of short duration in relation to disease activity based on the assessment of 28 joints (DAS28). Methods. We studied 29 patients (22 women, mean age 41 (SD, 9) years) with RA of short duration and 29 healthy controls. The RA subjects were divided into those with low (DAS28: 2.6–5.1, n = 18) or high (DAS28 > 5.1, n = 11) disease activity. Exclusion criteria included clinically overt atherosclerosis and other coexistent diseases. Biochemical markers of inflammatory activation and endothelial dysfunction were measured. Results. There were no significant intergroup differences in the majority of classical cardiovascular risk factors. High-sensitivity C-reactive protein, tumor necrosis factor-α, and interleukin-6 were increased in RA subjects. Compared to the controls, levels of soluble vascular cell adhesion molecule-1, von Willebrand factor, and pentraxin-3 were significantly elevated in RA subjects with low disease activity, exhibiting no further significant rises in those with high disease activity. Asymmetric dimethyl-L-arginine, soluble E-selectin, monocyte chemotactic protein-1, and osteoprotegerin were increased only in RA patients with high disease activity. Conclusions. Our findings might suggest a dissociation of pathways governing generalized and joint-specific inflammatory reactions from those involved in endothelial activation and inflammation within the vascular wall.

Endothelial dysfunction in joint disease

Inflammatory joint diseases and autoimmune diseases with joint manifestations are associated with premature and accelerated atherogenesis. Patients with rheumatoid arthritis (RA) have a 5- to 10-year decrease in life expectancy compared to the general population, and those exhibiting extraarticular manifestations have the greatest excess mortality. RA is now established as an independent cardiovascular risk factor. Complex interactions linking conventional cardiovascular risk factors, systemic inflammation, and vascular function may explain the increased cardiovascular risk among RA patients. Endothelial dysfunction is now recognized as both the key step in early atherogenesis and a contributor to atheroma plaque progression at later stages. Endothelial dysfunction is defined as impaired endothelium-dependent blood-vessel dilation in response to a stimulus. The underlying mechanisms remain speculative. Over the last decade, a role for endothelial dysfunction in the cardiovascular complications of inflammatory joint disease has been hypothesized and several maintenance drugs targeting this phenomenon have been tested, with promising results.

Contractile, but not endothelial, dysfunction in early inflammatory arthritis: a possible role for matrix metalloproteinase-9

BACKGROUND AND PURPOSE

Excess morbidity/mortality in rheumatoid arthritis (RA) is associated with increased incidence of cardiovascular disease. In this 'proof-of-concept' study, vascular function was characterized in the murine collagen-induced arthritis (mCIA) model, the benchmark choice for evaluation of the pathological processes and assessment of new therapies.

EXPERIMENTAL APPROACH

Mice in the very early stages of arthritis development [and appropriate naïve (non-immunized) age-matched controls] were used in the study. Blood pressure was measured using tail cuff plethysmography. Vascular function in rings of isolated aorta was studied with isometric tension myography. Levels of NO metabolites (NO(x)), MMP-9 protein and IL-1β in plasma and MMP-9 protein in aortic homogenates were quantified.

KEY RESULTS

Impaired vascular contractile responses in arthritis were unaffected by ex vivo inhibition of NOS (endothelial/neuronal and inducible) or COX activities. Endothelium-dependent and -independent relaxation, plasma NO(x) and blood pressure were unaffected by arthritis. Plasma and aortic homogenate MMP-9 protein levels were increased significantly in arthritis. Incubation of aortic tissues from naïve control animals with exogenous MMP-9 impaired subsequent contractile responses, mirroring that observed in arthritis. A role for IL-1β in perpetuating contractile dysfunction and increasing aortic MMP-9 was excluded.

CONCLUSIONS AND IMPLICATIONS

These data identify for the first time a relationship between early arthritis and contractile dysfunction and a possible role for MMP-9 therein, in the absence of overt endothelial dysfunction or increased NO production. As such, MMP-9 may constitute a significant target for early intervention in RA patients with a view to decreasing risk of cardiovascular disease.

Saposin C coupled lipid nanovesicles specifically target arthritic mouse joints for optical imaging of disease severity

Rheumatoid arthritis is a chronic inflammatory disease affecting approximately 1% of the population and is characterized by cartilage and bone destruction ultimately leading to loss of joint function. Early detection and intervention of disease provides the best hope for successful treatment and preservation of joint mobility and function. Reliable and non-invasive techniques that accurately measure arthritic disease onset and progression are lacking. We recently developed a novel agent, SapC-DOPS, which is composed of the membrane-associated lysosomal protein saposin C (SapC) incorporated into 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) lipid nanovesicles. SapC-DOPS has a high fusogenic affinity for phosphatidylserine-enriched microdomains on surfaces of target cell membranes. Incorporation of a far-red fluorophore, CellVue Maroon (CVM), into the nanovesicles allows for in vivo non-invasive visualization of the agent in targeted tissue. Given that phosphatidylserine is present only on the inner leaflet of healthy plasma membranes but is “flipped” to the outer leaflet upon cell damage, we hypothesized that SapC-DOPS would target tissue damage associated with inflammatory arthritis due to local surface-exposure of phosphatidylserine. Optical imaging with SapC-DOPS-CVM in two distinct models of arthritis, serum-transfer arthritis (e.g., K/BxN) and collagen-induced arthritis (CIA) revealed robust SapC-DOPS-CVM specific localization to arthritic paws and joints in live animals. Importantly, intensity of localized fluorescent signal correlated with macroscopic arthritic disease severity and increased with disease progression. Flow cytometry of cells extracted from arthritic joints demonstrated that SapC-DOPS-CVM localized to an average of 7–8% of total joint cells and primarily to CD11b+Gr-1+ cells. Results from the current studies strongly support the application of SapC-DOPS-CVM for advanced clinical and research applications including: detecting early arthritis onset, assessing disease progression real-time in live subjects, and providing novel information regarding cell types that may mediate arthritis progression within joints.