The cardiac cytoskeleton and the extracellular matrix play an essential role for 
maintaining cellular integrity and function of the myocardium. The network of 
microtubules and intermediate filaments are disrupted by the inflammatory 
reaction which depends on resident cells (myocytes, fibroblasts, endothel cells) 
and on systemic cells (granulocytes, macrophages, monocytes, lymphocytes). 
Changes in the cardiac cytoskeleton and the extracellular matrix may affect 
contractile function, since the cytoskeleton organizes the intra- and 
intercellular architecture. The inflammation in heart disease and the induction 
of fibrosis are mediated by cytokines and growth factors derived from fibroblast 
activation and from the B- and T-cell activity. A possible connecting link for 
the induction of fibrosis is the presentation of the myocardial antigens to the 
immune system and its subsequent cellular and humoral autoreactive response 
(Figure 1). Different autoantibodies to sarcolemmal and myolemmal antigens, to 
laminin, to extracellular matrix proteins, to the collagens and to myofibrils 
were demonstrated both in endomyocardial biopsy and as circulating 
autoantibodies in the peripheral blood. The pathophysiological role of the 
cytoskeleton and the extracellular matrix are well defined for beta-tubulin, 
fibronectin, laminin, desmin, vimentin, vinculin and collagen: beta-tubulin is 
increased or altered in dilated cardiomyopathy (DCM). Fibronectin appears in 
irregular forms in DCM as well. Ultrastructural analysis showed an increased 
content of laminin in basement membranes. In addition anti-laminin antibodies 
were found in 73% of patients with myocarditis and in 78% of patients with DCM. 
Desmin (z-bands) are partly destroyed in DCM. Anti-desmin antibody titers as 
indicators of a possible secondary immune response are found high in patients 
with acute myocarditis declining during reconvalescence and are also elevated in 
DCM. The vimentin of the endothelial cells and the vinculin of the sarcolemmal 
membrane and the intercalated discs have been demonstrated to be irregularly 
shaped and increased in content in DCM whereas in myocarditis their appearance 
and content is still unknown. The intracellular content of collagen type 5 is 
increased in DCM and in myocarditis. The presence of autoantibodies to 
components of the cytoskeleton and the extracellular matrix in myocarditis and 
perimyocarditis is well-described. Antibodies to the myolemma and the sarcolemma 
are found in almost all patients with perimyocarditis in the serum or bound in 
the biopsy. Some of them have been known cytolytic in vitro to isolated heart 
cells. In pericarditis a shift to antibodies to the extracellular matrix, 
collagen and intermediate filaments is observed among the circulating 
antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)