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Objective: Previously, only the HLA–DRB1 alleles have been assessed in rheumatoid arthritis (RA). The aim of the present study was to identify the key major histocompatibility complex (MHC) susceptibility factors showing a significant association with anti–carbamylated protein antibody–positive (anti‐CarP+) RA. Methods: Analyses were restricted to RA patients who were anti–cyclic citrullinated peptide antibody negative (anti‐CCP−), because the anti‐CCP status dominated the results otherwise. Therefore, we studied samples from 1,821 anti‐CCP− RA patients and 6,821 population controls from Spain, Sweden, and the Netherlands. The genotypes for ~8,000 MHC biallelic variants were assessed by dense genotyping and imputation. Their association with the anti‐CarP status in RA patients was tested with logistic regression and combined with inverse‐variance meta‐analysis. Significance of the associations was assessed according to a study‐specific threshold of P < 2.0 × 10−5. Results: The HLA–B*08 allele and its correlated amino acid variant Asp‐9 showed a significant association with anti‐CarP+/anti‐CCP− RA (P < 3.78 × 10−7; I2 = 0). This association was specific when assessed relative to 3 comparator groups: population controls, anti‐CarP−/anti‐CCP− RA patients, and anti‐CCP− RA patients who were positive for other anti–citrullinated protein antibodies. Based on these findings, anti‐CarP+/anti‐CCP− RA patients could be separated from other antibody‐defined subsets of RA patients in whom an association with the HLA–B*08 allele has been previously demonstrated. No other MHC variant remained associated with anti‐CarP+/anti‐CCP− RA after accounting for the presence of the HLA–B*08 allele. Specifically, the reported association of HLA–DRB1*03 was observed at a level comparable to that reported previously, but it was attributable to linkage disequilibrium. Conclusion: These results identify HLA–B*08 carrying Asp‐9 as the MHC locus showing the strongest association with anti‐CarP+/anti‐CCP− RA. This knowledge may help clarify the role of the HLA in susceptibility to specific subsets of RA, by shaping the spectrum of RA autoantibodies. [ABSTRACT FROM AUTHOR]

Objectives: Adiponectin is an adipokine that plays a relevant role in the development of metabolic syndrome (MetS), a complication that increases the risk of cardiovascular (CV) disease in patients with rheumatoid arthritis (RA). Accordingly, we assessed for the first time the short-term effect of anti-IL-6 receptor tocilizumab (TCZ) administration on adiponectin serum levels in RA patients and explored the potential association of adiponectin levels with MetS features, other CV risk factors and demographic and clinical characteristics of these patients., Methods: Adiponectin serum levels were evaluated in 50 non-diabetic RA patients, undergoing TCZ treatment, immediately prior to (pre-infusion) and 60 minutes after the end of a TCZ intravenous infusion (post-infusion)., Results: No significant differences in adiponectin levels pre- and post-TCZ infusion were found in RA patients (p=0.69). Patients with obesity exhibited decreased basal levels of adiponectin with respect to those non-obese (p=0.03). Additionally, a negative association of adiponectin basal levels with body mass index, insulin, insulin/glucose index, C-peptide and leptin levels (p<0.01; p=0.02; p=0.03; p=0.03 and p=0.01, respectively), as well as a positive correlation with HDL-cholesterol levels (p<0.001) was seen., Conclusions: Our results support the claim that low adiponectin may contribute to the development of MetS and, consequently, CV disease in RA. Anti-IL-6 therapy does not seem to exert a short-term effect on adiponectin levels.

Objectives: 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., Methods: 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)., Results: 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)., Conclusions: 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.