Background: Various cytokines are involved in the pathogenesis of sarcoidosis, but their expression in the myocardium has not been documented for cardiac sarcoidosis.
Methods and results: Myocardial tissue was obtained from 12 patients with cardiac sarcoidosis at the time of left ventriculoplasty, biopsy or autopsy. mRNA expression of various inflammatory cytokines was analyzed using quantitative real-time polymerase chain reaction, as well as by immunohistochemistry. Ten patients with dilated cardiomyopathy (DCM) served as controls. Enhanced expression of interleukin (IL)-1alpha, IL-2, IL-12 p40 and interferon (IFN)-gamma mRNA was limited to the myocardium of cardiac sarcoidosis patients. Expression of IL-1beta, IL-8, IL-10, IL-15 and TNF-alpha occurred in both cardiac sarcoidosis and DCM patients, but IL-4 and IL-5 were not detected in either disease. Immunohistochemistry of the myocardial tissue of sarcoidosis revealed positive staining for IL-12 and IFN-gamma. IL-12 was localized in multinucleated giant cells and macrophages of the sarcoid granulomas, whereas IFN-gamma was detected in lymphocytes and vascular endothelial cells.
Conclusions: Type 1 helper T-cell cytokines may be involved in the pathogenesis of cardiac sarcoidosis.