Interleukin-6: Cardiovascular Aspects of Long-Term Cytokine Suppression in Patients with Rheumatoid Arthritis

In recent years, many atherogenesis researchers have focused on the role of inflammatory cytokines in the development of cardiovascular disease (CVD). Interleukin-6 (IL-6) cytokine is independently associated with higher CVD risk in patients with rheumatoid arthritis (RA). The effect of IL-6 inhibitors on the cardiovascular system in RA patients remains poorly understood, especially with its long-term use. This study investigates the effect of therapy with IL-6 receptor blocker tocilizumab (TCZ) on the dynamics of cardiovascular risk (CVR), modifiable risk factors (RFs), carotid artery (CA) structural changes, and the incidence of cardiovascular complications (CVCs) in RA patients during a 265-week follow-up period. Forty-five patients with active RA (DAS28-ESR 6.2 (5.5;6.8) with ineffectiveness and/or intolerance to disease-modifying antirheumatic drugs (DMARDs) were included in this study. During long-term therapy with TCZ in RA patients, no increase in CVR and no significant structural changes in CA were observed. No significant changes in the blood lipid spectrum were observed in patients without statin therapy. In the group of patients receiving statins, there was a 43% increase in high-density lipoprotein cholesterol (HDL-C), a 15% reduction in total cholesterol levels, and a 56% decrease in the atherogenicity index (p < 0.01 in all cases). Associations were found between ∆ total cholesterol and ∆ C-reactive protein (CRP) (R = 0.36, p = 0.04), ∆ low-density lipoprotein cholesterol (LDL-C), and ∆-CRP (R = 0.42, p = 0.03) in RA patients receiving statins. Initially, the thickness of the intima-media complex of carotid arteries (cIMT) positively moderately correlated with age (R = 0.7; p < 0.01), BMI (R = 0.37; p < 0.01), and systolic blood pressure (R = 0.64; p < 0.01); however, it weakly correlated with the lipid spectrum parameters: total cholesterol (R = 0.29; p < 0.01) and LDL-C (R = 0.33; p < 0.01). No new associations of cIMT by the end of the follow-up period, as well as the relationship of cIMT value with RA activity and therapy, were revealed. Patients with carotid ASPs showed an oppositely directed relationship between total cholesterol and sVCAM-1 at baseline (R = -0.25, p = 0.01) and at the end of this study (R = 0.29, p < 0.01). The incidence of cardiovascular events was 0.53 per 100 patient-years during the 265-week period of TCZ therapy.