Interleukin-1 in myocardium and coronary arteries of patients with dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (DCM) is characterised by a severe dysfunction of the heart muscle resulting in terminal heart failure. Its pathogenesis is believed to be multifactorial involving genetic predisposition, viral infection and autoimmunity, but little is known in detail, and there is no curative treatment except transplantation. Interleukin-1 (IL-1) mediates inflammatory responses to infection and injury. It can be produced by several widely-distributed cell types, including macrophages, and is thought to depress myocyte contractility by stimulating nitric oxide synthase. To investigate whether this pro-inflammatory cytokine may be a pathogenic mediator in DCM, IL-1β mRNA and protein were evaluated in coronary arteries and myocardium from patients undergoing cardiac transplantation for DCM. IL-1β mRNA was detected by PCR of cDNA and northern blots of mRNA in coronary arteries and myocardium from patients with DCM, By comparison, samples from patients with ischaemic heart disease (IHD) contained much less 1L-1β mRNA. In contrast, mRNA for other cytokines (TNFα, IL-6, IL-10, PDGFA) were similar in both pathologies. In DCM, IL-1β mRNA and protein were localised to infiltrating macrophages in interstitial regions between myocytes, some of the myocytes themselves, and endothelial cells of vessels in the wall of the arteries. These results suggest that local production of the pro-inflammatory cytokine, IL-1β may play a part in the pathogenesis of DCM.