Anti-IL-6 therapy reduces leptin serum levels in patients with rheumatoid arthritis

Leptin is an adipokine that participates in the regulation of the immune and inflammatory response. Chronic systemic inflammation contributes to the development of cardiovascular (CV) disease in rheumatoid arthritis (RA). In this study, we aimed to assess the short-term effect of the anti-IL-6 receptor tocilizumab (TCZ) administration on circulating leptin concentrations in patients with RA, as well as the potential association of leptin with CV risk factors and demographic and clinical characteristics of these patients.

We recruited 50 consecutive non-diabetic patients with RA undergoing periodic treatment with TCZ. Leptin serum levels were determined by a commercial immunoassay kit in samples obtained immediately prior to (pre-infusion) and 60 minutes after the end of a TCZ intravenous infusion (post-infusion).

A significant reduction of leptin levels was observed following the TCZ infusion (9.24±7.98 ng/mL vs. 7.92±7.32 ng/mL, pre- and post-infusion, respectively, p=0.002). Additionally, there was a strong positive correlation between body mass index of RA patients and basal levels of leptin (r=0.56; p=0.0001). Moreover, high basal levels of leptin in RA patients were associated with female sex (p=0.006), obesity (p<0.001) and rheumatoid factor negative status (p=0.006).

Our study disclosed a short-term effect of anti-IL-6 therapy on leptin serum levels in RA patients. Decreased leptin levels may explain the beneficial effect of anti-IL-6 blockade on CV disease associated to RA.