Bone Erosion is Associated with Reduction of Circulating Endothelial Progenitor Cells and Endothelial Dysfunction in Rheumatoid Arthritis.

Objective: To identify factors influencing endothelial progenitor cell (EPC) counts in patients with rheumatoid arthritis (RA). Methods: The number of circulating CD34+/VEGFR2+ EPCs was measured in 126 RA patients and 46 non-RA controls. Endothelial function was assessed by brachial flow-mediated dilation (FMD). Serum CXCL12 concentration was determined using an enzyme-linked immunosorbent assay. EPCs and FMD were measured at baseline and after 24 weeks of anti-tumor necrosis factor-α (TNF-α) therapy in 29 patients with active RA. Results: Circulating EPC counts were significantly lower in RA patients than non-RA controls. In multivariate analysis, older age, reduced high-density lipoprotein-cholesterol, and higher bone erosion score were independent risk factors of reduced EPC counts in RA patients. Serum CXCL12 level correlated negatively with EPC counts, but positively with bone erosion score. FMD was impaired in RA patients, and decreased FMD in RA was closely associated with a higher bone erosion score and reduced EPC counts. In addition, EPC counts were restored by anti-TNF-α therapy, and this increase was paralleled by improvement in FMD. Interestingly, restoration of EPC counts was attenuated in patients with a higher bone erosion score compared with those with a lower bone erosion score, despite a similar improvement in disease activity. Conclusions: Circulating EPC counts in RA patients are reduced and inversely correlated with serum CXCL12 levels. Reduced EPC counts are closely associated not only with bone erosion but also with endothelial dysfunction. © 2013 American College of Rheumatology.