Background: Atherosclerosis is a chronic inflammatory disease, with interleukin 6 (IL-6) as a major player in inflammation cascade. IL-6 blockade may reduce cardiovascular risk, but current treatments to block IL-6 also induce dyslipidemia, a finding with an uncertain prognosis.

Methods and results: We aimed to determine the endothelial function responses to the IL-6-blocking agent tocilizumab, anti-tumor necrosis factor α, and synthetic disease-modifying antirheumatic drug therapies in patients with rheumatoid arthritis in a 16-week prospective study. Sixty consecutive patients with rheumatoid arthritis were enrolled. Tocilizumab and anti-tumor necrosis factor α therapy were started in 18 patients each while 24 patients were treated with synthetic disease-modifying antirheumatic drugs. Forty patients completed the 16-week follow-up period. The main outcome was flow-mediated dilation percentage variation before and after therapy. In the tocilizumab group, flow-mediated dilation percentage variation increased statistically significantly from a pre-treatment mean of (3.43% [95% CI, 1.28-5.58] to 5.96% [95% CI, 3.95-7.97]; P=0.03). Corresponding changes were 4.78% (95% CI, 2.13-7.42) to 6.75% (95% CI, 4.10-9.39) (P=0.09) and 2.87% (95% CI, -2.17 to 7.91) to 4.84% (95% CI, 2.61-7.07) (P=0.21) in the anti-tumor necrosis factor α and the synthetic disease-modifying antirheumatic drug groups, respectively (both not statistically significant). Total cholesterol increased significantly in the tocilizumab group from 197.5 (95% CI, 177.59-217.36) to 232.3 (201.62-263.09) (P=0.003) and in the synthetic disease-modifying antirheumatic drug group from 185.8 (95% CI, 169.76-201.81) to 202.8 (95% CI, 176.81-228.76) (P=0.04), but not in the anti-tumor necrosis factor α group. High-density lipoprotein did not change significantly in any group.

Conclusions: Endothelial function is improved by tocilizumab in a high-risk population, even as it increases total cholesterol and low-density lipoprotein levels.