IL-6 in Systemic Lupus Erythematosus: At the Intersection of Disease Activity and Cardiovascular Risk

Background/Objectives: Interleukin-6 (IL-6) is a pro-inflammatory cytokine implicated in the pathogenesis of SLE. Beyond its role in disease activity, IL-6 has also been associated with increased cardiovascular risk, potentially promoting endothelial dysfunction, atherosclerosis, and thromboinflammation. Our study aimed to investigate the associations between IL-6 levels, disease manifestations, organ damage, cardiovascular comorbidities, and treatment regimens in a cohort of SLE patients. Methods: A total of 88 SLE patients were recruited from the Rheumatology Clinic of the Clinical Rehabilitation Hospital, Iași. Disease activity was assessed using the SLE Disease Activity Index (SLEDAI) and irreversible organ damage with the SLICC/ACR Damage Index. Serum IL-6 levels were measured by ELISA. Statistical analyses included Mann-Whitney U tests and Spearman correlation coefficients. Results: Among 88 SLE patients (89.8% female, mean age 51.9 ± 14.8 years), 68.2% presented irreversible organ damage, most frequently cardiovascular (26.1%). Regarding disease manifestations, IL-6 was non-significantly elevated in patients with arthritis, rash, and low complement levels. Serum concentrations also tended to increase with disease severity, being higher in severe compared to moderate activity, and in moderate versus mild activity. Significant associations were found between IL-6 and hypertension (p = 0.027), aortic atherosclerosis (p = 0.034), menopausal status (p = 0.015), and hypercholesterolemia (p = 0.034). No significant differences were observed across treatment subgroups. Conclusions: IL-6 showed limited correlation with SLE clinical activity but was significantly elevated in patients with selected cardiovascular comorbidities. These findings suggest a potential contribution of IL-6 to cardiovascular risk in SLE, warranting further investigation in larger cohorts.