Disease severity impacts the relationship of apelin with arterial function in patients with rheumatoid arthritis

Apelin can improve arterial function by enhancing the expression of endothelial nitric oxide synthase but this effect depends markedly on endothelial integrity. We hypothesized that inflammation influences the potential impact of apelin on arterial function in rheumatoid arthritis (RA). We assessed the associations of apelin concentrations with arterial stiffness (pulse wave velocity), wave reflection (augmentation index, reflected wave pressure, and reflection magnitude), and pressure pulsatility (central systolic pressure (CSP), central pulse pressure (CPP), peripheral pulse pressure (PPP), pulse pressure amplification (PPamp), and forward wave pressure (Pf)) among 170 RA patients without cardiovascular disease. In multivariable regression models, apelin concentrations were not independently associated with arterial function measures (p ≥ 0.15) in all patients. Inflammation markers were not consistently associated with apelin levels but joint deformity counts, Disease Activity Score in 28 joints (DAS28), and erythrocyte sedimentation rate (ESR) impacted apelin-pressure pulsatility relations (interaction p ≤ 0.05). In stratified analysis, apelin was associated with CSP (partial r = - 0.33, p = 0.01), CPP (partial r = - 0.26, p = 0.04), PPamp (partial r = 0.27, p = 0.03), and Pf (partial r = - 0.33, p = 0.01) in patients without but not with joint deformities; apelin was related to CSP (partial r = - 0.24, p = 0.05) in those with a DAS28 joint < 2.8 (median value) (partial r = - 0.24, p = 0.05) but not ≥ 2.8, and to CSP (partial r = - 0.36, p = 0.003) in those with an erythrocyte sedimentation rate < 13 mm/h (median value) but not ≥ 13 mm/h. Apelin is associated with reduced pressure pulsatility in RA patients without but not with a high inflammatory burden. A loss of apelin protective effects on arterial function may contribute to the link between RA severity and cardiovascular risk.