Objectives: Patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) have increased IL-1β levels. IL-1β and other pro-inflammatory cytokines have a modulating activity on cardiac ion channels and have been associated with increased arrhythmic risk in rheumatoid arthritis patients. Likewise, adult patients with connective tissue diseases (CTDs) may have prolonged QTc intervals associated with the presence of anti-Ro/SSA antibodies. Our objective was to evaluate the presence of serum IL-1β in subjects with CTDs, in relation to the presence of anti-Ro/SSA antibodies and QTc interval duration.
Methods: 12-lead electrocardiograms (ECG) were performed and blood was withdrawn, measuring electrolytes, IL-1β anti-Ro/SSA antibodies by ELISA in 73 patients with CTDs.
Results: 55 patients were anti-Ro/SSA positive and 18 were anti-Ro/SSA negative. Patients with anti-Ro/SSA positive antibodies had a significantly greater median IL-1β serum level: 7.29 (range: 0.17-17.3 pg/ml) compared to patients with anti-Ro/SSA negative antibodies whose median was: 1.67 (range 0.55-4.12 pg/ml) p<0.001. The mean QTc interval values obtained in both groups were not significantly different (417.7±23.1 vs. 414.7±21.2, p=0.63). The QTc interval was prolonged in 11 (20%) patients, who were all anti-Ro/SSA positive versus 0 (0 %) in anti-Ro/SSA negative patients p=0.05. Median IL-1β levels were: 8.7 (range: 2.69-15.1 pg/ml) in patients with prolonged QTc interval versus median: 5.0 (range: 0.17-17.3 pg/ml) in those with normal QTc interval values (<440ms) p=0.006.
Conclusions: IL-1β is elevated in patients with CTDs that have both anti-Ro/SSA antibodies and prolonged QTc intervals.