IL-1 beta reduces cardiac lymphatic muscle contraction via COX-2 and PGE(2) induction: Potential role in myocarditis

摘要

The role of lymphatic vessels in myocarditis is largely unknown, while it has been shown to play a key role in other inflammatory diseases. We aimed to investigate the role of lymphatic vessels in myocarditis using in vivo model induced with Theiler's murine encephalomyelitis virus (TMEV) and in vitro model with rat cardiac lymphatic muscle cells (RCLMC). In the TMEV model, we found that upregulation of a set of inflammatory mediator genes, including interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha and COX-2 were associated with disease activity. Thus, using in vitro collagen gel contraction assays, we decided to clarify the role(s) of these mediators by testing contractility of RCLMC in response to IL-1 beta and TNF-alpha individually and in combination, in the presence or absence of: IL-1 receptor antagonist (Anakinra); cyclooxygenase (COX) inhibitors inhibitors (TFAP, diclofenac and DuP-697). IL-1 beta impaired RCLMC contractility dose-dependently, while co-incubation with both IL-1 beta and TNF-a exhibited synergistic effects in decreasing RCLMC contractility with increased COX-2 expression. Anakinra maintained RCLMC contractility; Anakinra blocked the mobilization of COX-2 induced by IL-1 beta with or without TNF-alpha. COX-2 inhibition blocked the IL-1 beta-mediated decrease in RCLMC contractility. Mechanistically, we found that IL-1 beta increased prostaglandin (PG) E2 release dose-dependently, while Anakinra blocked IL-1 beta mediated PGE(2) release. Using prostaglandin E receptor 4 (EP4) receptor antagonist, we demonstrated that EP4 receptor blockade maintained RCLMC contractility following IL-1 beta exposure. Our results indicate that IL-1 beta reduces RCLMC contractility via COX-2/PGE2 signaling with synergistic cooperation by TNF-alpha. These pathways may help provoke inflammatory mediator accumulation within the heart, driving progression from acute myocarditis into dilated cardiomyopathy.