Osteogenic Circulating Endothelial Progenitor Cells are Associated with Vascular Aging of the Large Arteries in Rheumatoid Arthritis.

Background and Aim: Rheumatoid arthritis is associated with both abnormal bone metabolism and accelerated vascular aging but a mechanistic link was lacking. This study aims to investigate the role of osteocalcin (OCN)-expressing circulating endothelial progenitor cells (EPCs) in vascular aging, as determined by arterial calcifications in rheumatoid arthritis. Methods: We performed flow cytometry studies in 145 consecutive patients with rheumatoid arthritis to determine osteogenic circulating levels of OCN-positive (OCN+) CD34+KDR+ and OCN+CD34+ versus conventional early EPC CD34+CD133+KDR+. Total calcium load of the thoracic aorta (ascending plus descending) and the carotid arteries were assessed by non-contrast computed tomography (CT) and contrast CT angiography. Results: Osteogenic EPCs OCN+CD34+KDR+ (P = 0.002) and OCN+CD34+ (P = 0.001), together with clinical parameters of age, history of hypertension, systolic blood pressure, serum levels of triglycerides, HbA1c and creatinine, use of leflunomide and brachial-ankle pulse-wave velocity (all P < 0.05), were associated with the clustered presence of aortic and carotid calcification. Multivariable analyses revealed that circulating OCN+CD34+KDR+ (B = 14.4 [95% CI 4.0 to 24.8], P = 0.007) and OCN+CD34+ (B = 9.6 [95% CI 4.9 to 14.3], P < 0.001) remained independently associated with increased aortic calcium load. OCN+CD34+ EPC (B = 0.8 [95% CI 0.1 to 1.5], P = 0.023), but not OCN+CD34+KDR+ EPC (B = 1.2 [95% CI -0.2 to 2.6], P = 0.09), was further independently associated with carotid calcium load. In comparison, conventional early EPC CD34+CD133+KDR+ had no significant association with aortic or carotid calcium load (P = 0.46 and 0.88, respectively). Conclusion: Circulating level of osteogenic EPC is associated with increased vascular aging in terms of calcification of the large arteries in patients with rheumatoid arthritis. The findings may suggest a role of the bone-vascular axis underlying vascular aging in rheumatic diseases. Further research is needed to characterize the mechanistic links and basis of these observations.

Cumulative Rheumatic Inflammation Modulates the Bone-Vascular Axis and Risk of Coronary Calcification.

Background Rheumatic diseases are related to both abnormal bone turnover and atherogenesis, but a mechanistic link was missing. Methods and Results We investigated the effect of cumulative rheumatic inflammation ( CRI ) on risk of coronary calcification in a retrospective cohort of 145 rheumatoid arthritis patients. A time-adjusted aggregate CRI score was derived by conglomerating all quarterly biomarker encounters of serum C-reactive protein over 60 months immediately preceding computed tomography coronary angiography. Flow cytometry was performed to measure the osteocalcin-positive ( OCN +) CD 34+ KDR + and OCN + CD 34+ circulating endothelial progenitor cells ( EPCs ). Conventional early circulating EPCs CD 34+ CD 133+ KDR + was determined. Coronary calcification was defined as any Agatston score >0. 50% of patients (n=72/145) had coronary calcification. CRI score was associated with presence of coronary calcification ( P=0.004) (multivariable-adjusted: highest versus lowest quartile: odds ratio=5.6 [95% CI 1.1-28.9], P=0.041). Receiver operating characteristics curve revealed divergent behavior of OCN -expressing circulating EPCs ( OCN + CD 34+ EPCs : area under the curve=0.60, P=0.034; OCN + CD 34+ KDR + EPCs : area under the curve=0.59, P=0.053, positive predictors) versus conventional early EPCs ( CD 34+ CD 133+ KDR +: area under the curve=0.60, P=0.034, negative predictor) for coronary calcification, which persisted after multivariable adjustments ( OCN + CD 34+ KDR + [>75th percentile]: odds ratio=7.2 [95% CI 1.8-27.9], P=0.005; OCN + CD 34+ EPCs [>75th percentile]: odds ratio=6.0 [95% CI 1.5-23.3], P=0.010; CD 34+ CD 133+ KDR + [>75th percentile: odds ratio=0.3 [95% CI 0.1-1.0], P=0.053). Intriguingly, the CRI score was associated with increased OCN + CD 34+ EPCs (highest versus lowest quartile: B=+25.6 [95% CI 0.8-50.5] [×103/mL peripheral blood], P=0.043), but reduced CD 34+ CD 133+ KDR + EPCs (highest versus lowest quartile: B=-16.2 [95% CI -31.5 to -0.9], P=0.038). Conclusions Preceding 60 months of CRI is associated with increased risk of coronary calcification and altered OCN expression in circulating EPCs .

Osteogenic circulating endothelial progenitor cells are linked to electrocardiographic conduction abnormalities in rheumatic patients.

BACKGROUND: Osteogenic circulating endothelial progenitor cells (EPC) play a pathogenic role in cardiovascular system degeneration through promulgating vasculature calcification, but its role in conduction disorders as part of the cardiovascular degenerative continuum remained unknown. AIM: To investigate the role of osteocalcin (OCN)-expressing circulating EPCs in cardiac conduction disorders in the unique clinical sample of rheumatoid arthritis (RA) susceptible to both abnormal bone metabolism and cardiac conduction disorders. METHODS: We performed flow cytometry studies in 134 consecutive asymptomatic patients with rheumatoid arthritis to derive osteogenic circulating OCN-positive (OCN+) CD34+KDR+ vs. CD34+CD133+KDR+ conventional EPC. Study endpoint was the prespecified combined endpoint of electrocardiographic conduction abnormalities. RESULTS: Total prevalence of cardiac conduction abnormality was 9% (n = 12). All patients except one had normal sinus rhythm. One patient had atrial fibrillation. No patient had advanced atrioventricular (AV) block. Prevalence of first-degree heart block (>200 ms), widened QRS duration (>120 ms) and right bundle branch block were 6.7%, 2.1%, and 2.2% respectively. Circulating osteogenic OCN+ CD34+ KDR+ EPCs were significantly higher among patients with cardiac conduction abnormalities (p = 0.039). Elevated OCN+ CD34+ KDR+ EPCs> 75th percentile was associated with higher prevalence of cardiac conduction abnormalities (58.3% vs. 20.02%, p = 0.003). Adjusted for potential confounders, elevated OCN+ CD34+ KDR+ EPCs> 75th percentile remained independently associated with increased risk of cardiac conduction abnormalities (OR = 4.4 [95%CI 1.2-16.4], p = 0.028). No significant relation was found between conventional EPCs CD34+CD133+KDR+ and conduction abnormalities (p = 0.36). CONCLUSIONS: Elevated osteogenic OCN+ CD34+ KDR+ EPCs are independently associated with the presence of electrocardiographic conduction abnormalities in patients with rheumatoid arthritis, unveiling a potential novel pathophysiological mechanism.