Interleukin-6 positively correlates with cardiovascular disease predictor algorithms and biomarker in rheumatoid arthritis patients

Chronic inflammation is believed as the main culprit of the link between cardiovascular disease (CVD) and rheumatoid arthritis (RA). Interleukin-6 (IL-6) is a pro-inflammatory cytokine with a key role in RA pathophysiology and also correlates with joint destruction and disease activity. This study evaluates the association between IL-6 plasma level and cardiac biomarker NT-proBNP, HS-CRP, CVD predictor algorithms, Framingham Risk Score (FRS) and Systematic Coronary Risk Evaluation (SCORE), as well as with CXCL9 and its receptor, CXCR3 in RA patients compared to the controls. Sixty RA patients (30 early and 30 late) and 30 healthy persons were included in this study. IL-6 and NT-proBNP plasma levels were measured by the ELISA. Also, HS-CRP plasma levels were quantified using the immunoturbidimetric assay. The CVD risk was assessed by the FRS and SCORE. IL-6 plasma levels were significantly higher in the early and late RA patients compared to the controls (p < 0.001). There was a positive correlation between IL-6 with DAS-28 (p = 0.007, r = 0.346), BPS (p = 0.002, r = 0.396), BPD (p = 0.046, r = 0.259), SCORE (p < 0.001, r = 0.472), and FRS (p < 0.001, r = 0.553), and a negative association with HDL (p = 0.037, r = -0.270), in the patients. Also, IL-6 plasma level positively correlated with HS-CRP (p = 0.021, r = 0.297) and NT-proBNP (p = 0.045, r = 0.260) in the patients. Furthermore, a positive association was found between IL-6 plasma levels and CXCL9 (p = 0.002, r = 0.386), and CXCR3 (p = 0.018, r = 0.304) in the patients. Given the interesting association between IL-6 with various variables of CVD, IL-6 may be considered a biomarker for assessing the risk for future cardiovascular events in RA patients.