Cardiovascular disease is a leading cause of mortality in rheumatoid arthritis (RA). Endothelial dysfunction often precedes manifest atherosclerosis. We assessed endothelial dysfunction and atherosclerosis in RA in context with laboratory markers.
Fifty-two patients with RA and 40 matched healthy controls were studied. We assessed common carotid intima-media thickness (ccIMT) and flow- (FMD) and nitroglycerine-mediated vasodilation (NMD). We also assayed numerous immunological and metabolic laboratory markers.
FMD was significantly lower in RA (5.32% +/- 4.66%) compared to controls (8.30% +/- 3.96%) (p = 0.001). NMD was preserved in RA. ccIMT was significantly greater in patients with RA (0.63 +/- 0.14 mm) versus controls (0.54 +/- 0.15 mm) (p = 0.012). In patients with RA, ccIMT correlated with FMD% (R = -0.318, p = 0.022), age (R = 0.831, p < 0.001), and anti-dsDNA levels (R = 0.463, p = 0.006). FMD% correlated with serum interferon-gamma (IFN-gamma) levels (R = 0.516, p = 0.014). NMD% correlated inversely with the percentage of Th0 lymphocytes (R = -0.636, p = 0.006), serum immune complex (R = -0.692, p < 0.001), and IgM levels (R = -0.606, p = 0.003). Patients with RA were divided as "low" (< 0.65 mm) versus "high" (> 0.65 mm) ccIMT groups, and into "normal" (> 5%) versus "impaired" (< 5%) FMD% subsets. Low and high ccIMT groups differed significantly in age and serum interleukin 1 (IL-1) and anti-dsDNA levels. RA patients with normal versus impaired FMD% differed significantly in age, disease duration, and serum IFN-gamma levels. Lipoprotein(a) [Lp(a)] also correlated with rheumatoid factor (RF) and C-reactive protein (CRP); homocysteine (HCy) correlated with CRP and correlated inversely with folate and vitamin B12 production. Paraoxonase-1 (PON-1) activity correlated with serum tumor necrosis factor-alpha(TNF-alpha) and IL-6 levels.
This was a well characterized RA population, where FMD and ccIMT were impaired, indicating early endothelial dysfunction and accelerated atherosclerosis, respectively. RA-related autoimmune-inflammatory mechanisms and metabolic factors including anti-CCP, RF, CRP, circulating immune complexes, IgM, TNF-alpha, IL-6, Th0/Th1 ratio, HCy, folate, vitamin B12, and PON-1 may all be involved in the development of vascular disease in RA. Although ccIMT and FMD, as well as some laboratory factors, have been assessed by other investigators in RA-associated atherosclerosis, our results regarding the possible involvement of anti-CCP, anti-dsDNA, Lp(a), some cytokines, and PON-1 activity are novel. Early determination of FMD% and ccIMT may be useful to assess RA patients with high cardiovascular risk.