Abstract
Post-operative atrial fibrillation (AF) remains a common cause of morbidity. Increasing evidence indicates that inflammation and atrial fibrosis contribute to the pathogenesis of this condition. Interleukin (IL)-17A, a potent pro-inflammatory cytokine, has been implicated in the development of a number of cardiovascular diseases. However, its role in post-operative AF remains unknown. In the present study, sterile pericarditis (SP) was induced in rats by the epicardial application of sterile talc. AF was induced by transesophageal burst pacing. Western blot analysis was applied to quantify the expression of IL-17A. Quantitative PCR was used to detect the mRNA expression of IL-17A, IL-6, IL-1β, transforming growth factor-β1 (TGF-β1), collagen type 1 (Col-1), collagen type 3 (Col-3) and α-smooth muscle actin (α-SMA). Gelatin zymography and reverse gelatin zymography were used to quantify the levels of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs). Histological analyses were performed to determine the extent of tissue inflammation and fibrosis. The rats with SP presented with a shorter refractoriness, a higher incidence and duration of AF, an enhanced susceptibility to developing AF, increased mRNA levels of AF-related pro-inflammatory cytokines (IL-6, IL-1β and TGF-β1), as well as marked atrial inflammation and fibrosis. The atrial IL-17A levels were elevated and correlated with the probability of developing AF. Treatment with anti-IL-17A monoclonal antibody decreased the levels of atrial IL-17A, prolonged refraction and markedly suppressed the development of AF. Simultaneously, inflammation and fibrosis were alleviated, which was further demonstrated by a decreased expression of AF-related pro-inflammatory cytokines, a downregulation in fibrosis-related mRNA expression (Col-1, Col-3 and α-SMA) and by the decreased activity of MMP-2/9 and TIMPs. Thus, the findings of our study indicate that IL-17A may play a pathogenic role in post-operative AF by inducing inflammation and fibrosis in rats with SP.