Background:Adiponectin is an adipokine with anti-inflammatory, anti-atherosclerotic and cardioprotective effects that also contributes to the pathogenesis of metabolic syndrome (MetS) [1]. MetS is frequently observed in patients with rheumatoid arthritis (RA), increasing the risk of cardiovascular (CV) morbidity and mortality in these patients [1-3]. A recent study of our group disclosed a short-term effect of anti-IL-6 therapy on serum levels of leptin (another adipokine with pro-inflammatory functions, related with MetS and CV disease) in RA patients [4]. Accordingly, it is plausible to think that such treatment may also have an effect in adiponectin levels.Objectives:To determine the short-term effect of the anti-IL-6 receptor tocilizumab (TCZ) administration on circulating adiponectin serum levels in patients with RA, as well as the potential association of adiponectin with demographic and clinical features of these patients.Methods:50 consecutive Spanish patients undergoing periodic treatment with TCZ who fulfilled the 2010 classification criteria for RA [5] were recruited. Adiponectin serum levels were assessed in samples obtained immediately prior to (pre-infusion) and 60 minutes after the end of a TCZ intravenous infusion (post-infusion) by a commercial Enzyme-Linked ImmunoSorbent Assay (ELISA) kit.Results:Similar serum levels of adiponectin were found following the TCZ infusion (mean ± standard deviation: 23.01 ± 18.58 µg/mL versus 22.35 ± 17.84 µg/mL, pre- and post-infusion, respectively, p=0.69). Additionally, there was a negative correlation between adiponectin basal levels and body mass index (r=-0.45, p<0.01), insulin (r=-0.33, p=0.02), insulin/glucose index (r=-0.32, p=0.03) and C-peptide levels (r=-0.32, p=0.03) of RA patients, whereas a strong positive correlation was observed with HDL-cholesterol levels (r=0.51, p<0.01). Moreover, basal levels of adiponectin were significantly lower in obese patients when compared to those with normal weight (p=0.03).Conclusion:Our study suggests that anti-IL-6 therapy has no short-term effect on adiponectin serum levels in patients with RA. Furthermore, our results support that low adiponectin levels are associated with MetS features and, therefore, with CV disease in RA.References:[1]Biochem Pharmacol. 2019;165:196-206; [2] Clin Exp Rheumatol. 2008;26:596-603; [3] Mediators Inflamm. 2013;2013:710928; [4] Clin Exp Rheumatol 2020;38:1201-1205; [5] Arthritis Rheum. 2010;62:2569-2581.Acknowledgements:Personal funds:SR-M: RD16/0012/0009 (ISCIII-ERDF); VP-C: PREVAL 18/01 (IDIVAL); OG: GPC IN607B2019/10 (GAIN); RL-M: Miguel Servet type I programme CP16/00033 (ISCIII-ESF).Disclosure of Interests:Sara Remuzgo-Martínez: None declared, Verónica Pulito-Cueto: None declared, Fernanda Genre: None declared, Jaime Calvo: None declared, Elena Aurrecoechea: None declared, Irene Llorente: None declared, Ana Triguero-Martinez: None declared, Ricardo Blanco Speakers bureau: Abbvie, Pfizer, Roche, Bristol-Myers, Janssen and MSD, Consultant of: Abbvie, Pfizer, Roche, Bristol-Myers, Janssen and MSD, Grant/research support from: Abbvie, MSD and Roche, Javier Llorca: None declared, M E Ruiz: None declared, Natalia Rivera: None declared, Oreste Gualillo: None declared, Raquel López-Mejías: None declared, Santos Castañeda: None declared, Miguel A González-Gay Speakers bureau: Pfizer, Abbvie, MSD, Grant/research support from: Pfizer, Abbvie, MSD.