Elevated levels of small, low-density lipoprotein with high affinity for arterial matrix components in patients with rheumatoid arthritis: possible contribution of phospholipase A2 to this atherogenic profile

Abstract

Objective: This work studied the presence of inflammatory and atherogenic lipoprotein markers that could explain the high incidence of cardiovascular disease (CVD) reported in rheumatoid arthritis (RA) patients.

Methods: Inflammatory markers were 1) soluble adhesion molecules (intercellular adhesion molecule [ICAM] and vascular cell adhesion molecule [VCAM]), 2) C-reactive protein (CRP), 3) fibrinogen (Fb), 4) cytokines (interferon-gamma [IFNgamma], tumor necrosis factor alpha [TNFalpha]), and 5) secretory group IIA phospholipase A2 (sPLA2-IIA). Atherogenic lipoprotein markers were 1) the size distribution of plasma lipoprotein subclasses, and 2) the binding affinity of low-density lipoprotein (LDL) to chondroitin 6-sulfate glycosaminoglycan (GAG).

Results: RA patients (n = 31) and matched controls (n = 28) had similar plasma concentrations of total cholesterol, triglycerides, Apo B, Apo A-I, very low-density lipoprotein, intermediate-density lipoprotein, and high-density lipoprotein (HDL). RA patients had significantly higher plasma levels of sPLA2-IIA, ICAM, CRP, Fb, TNFalpha, and IFNgamma compared with controls. RA patients also had significantly higher levels of small, dense LDL-1 (P < 0.05) and lower levels of small HDL-2 particles (P < 0.001) compared with controls. In addition, LDL from RA patients had a significantly higher binding affinity (Kd) to GAG (mean +/- SD Kd 204+/-22.4 nM Apo B) than did LDL from control subjects (Kd 312+/-36 nM Apo B) (P < 0.05). This Kd value showed a significant negative correlation with the plasma levels of LDL-1 (r = -0.566, P < or = 0.004). In RA patients, a significant positive correlation was obtained between sPLA2-IIA and CRP, ICAM, and LDL-1. HDL-2 showed a negative correlation with sPLA2-IIA.

Conclusion: These atherogenic lipoprotein factors combined with the presence of chronic inflammation may contribute to the high CVD-related mortality in RA patients.