COLLAGEN SUBTYPES AND MATRIX METALLOPROTEINASE IN IDIOPATHIC RESTRICTIVE CARDIOMYOPATHY

Background: Idiopathic restrictive cardiomyopathy is a rare disease ch aracterized by diastolic dysfunction, and the pathogenesis of the stif f heart remains unclear. The purpose of this study was to analyze the subpopulation of collagen fibers and determine the expression of matri x metallopreteinase in restrictive cardiomyopathy. Methods and Results : In endomyocardial biopsy specimens obtained from seven patients with restrictive cardiomyopathy, collagen fiber types I, III, and IV, and matrix metalloproteinase-l and two were observed by light and electron microscopy, using monoclonal antibodies. Type I collagen was less pro minent in the interstitium, whereas the immunoreactivity for type III collagen was marked. The immunoreactivity against matrix metalloprotei nase-l was observed along with types I and III collagen fibers and in the cytoplasm of some fibrocytes/ fibroblasts. The matrix metalloprote inase-l tended to increase when the reactivity against types I and m c ollagen was prominent. Both type IV collagen and matrix metalloprotein ase-2 were observed along arterial waits and the basement membrane of cardiocytes. Conclusions: Increased type m collagen may play an import ant role as the cause of left ventricular stiffness in restrictive car diomyopathy. The matrix metalloproteinase appeared to be involved in a cascade of collagen synthesis and the remodeling of the heart in pati ents with restrictive cardiomyopathy. (C) 1998 Elsevier Science Irelan d Ltd.