Abstract 2970: Tenascin-C is a Novel Marker of Ongoing Inflammation in Idiopathic Dilated Cardiomyopathy
Introduction: Although recent advances of medical treatment have greatly improved the prognosis of patients with idiopathic dilated cardiomyopathy (DCM), some cases still remain difficult to be treated. Furthermore, growing evidences suggest that DCM patients with persistent inflammation have a poor clinical outcome. Therefore, precise diagnosis of inflammatory activity is critical for the appropriate therapy. Tenascin-C (TNC) is an extracellular matrix glycoprotein which plays important roles in tissue remodeling in various heart diseases such as acute myocardial infarction and acute myocarditis.
Hypothesis: We assessed the hypothesis that expression of TNC is upregulated in the myocardium from DCM patients with active inflammation.
Methods: Expression of TNC was immunohistochemically analyzed in the myocardium obtained at left ventriculoplasty from 64 patients (50 ± 13 years, 56 men and 8 women) who had been clinically diagnosed as DCM and were selected to undergo the surgery. TNC expression in each sample was evaluated with special reference to myocardial inflammatory cell infiltrates and the presence of enterovirus genome.
Results: The ratio of TNC positive area to the whole myocardium was generally not so high of approximately 1%, but enhanced TNC expression (more than 3.5%) was noted in 7 cases with inflammatory cardiomyopathy. With careful observation throughout the myocardium of these cases, various phases of inflammatory lesions including active inflammatory cell infiltration with myocardial cell necrosis, granulation tissue, and healed scar were found. Intense TNC expression was observed in the area of active inflammation with abundant cell accumulation. TNC immuno-reactivity was also seen in the organized granulation tissue at resolving phase, but not in the scar at healed phase. In this study, the number of infiltrated inflammatory cells was positively correlated with TNC expression (r = 0.57, p = 0.0001) and the presence of enterovirus genome (r = 0.50, p < 0.05).
Conclusions: These findings imply that TNC expression indicates local interstitial remodeling associated with ongoing myocardial inflammation in DCM hearts. It might be a possible marker in distinguishing inflammatory cardiomyopathy from other type of DCM.