Interleukin-1 receptor antagonist is associated with both lipid metabolism and inflammation in rheumatoid arthritis.

Abstract

BACKGROUND: There is a relationship between cardiovascular morbidity, inflammatory activity, and changes in the lipid profile in rheumatoid arthritis (RA), although the mechanisms are not fully elaborated. Recent know-ledge that white adipose tissue (WAT) is a producer of immunologically and metabolically active substances gives another perspective to study. OBJECTIVE: To evaluate the relationship between interleukin-1 receptor antagonist (IL-1Ra) and variables associated with WAT and inflammation in RA. METHODS: Anthropometric, inflammatory and metabolic variables were assessed in 23 women with RA and 23 matched controls. Spearman, partial correlation and factor analyses were performed. RESULTS: Inflammatory markers were increased in patients. In both groups, IL-1Ra correlated with leptin independent of age and BMI. IL-1Ra also correlated with haptoglobin and apolipoprotein (Apo) B in patients and with soluble TNF receptor (sTNFR) 1 in controls. In factor analysis, three latent factors were identified among patients. The first loaded on IL-1Ra, leptin, BMI, ApoB and body fat content (BF%), the second loaded on IL1-Ra and sTNF-receptors and the third showed inverse loadings on ApoA-I together with loadings on ESR, haptoglobin, orosomucoid, BF% and BMI. CONCLUSION: IL-1Ra was associated with markers of inflammation and with fat-related factors in RA patients, suggesting a dualistic relationship of IL-1Ra in RA. IL-1Ra correlated independently with leptin in both patients and controls, indicating a relationship between inflammation and leptin.