Physiological stresses (heat, hemodynamics, genetic mutations, oxidative injury and myocardial ischemia) produce pathological states in which protein damage and misfolded protein structures are a common denominator. The specialized proteins family of antistress proteins - molecular chaperons (HSPs) - are responsible for correct protein folding, dissociating protein aggregates and transport of newly synthesized polypeptides to the target organelles for final packaging, degradation or repair. They are inducible at different cell processes such as cell division, apoptosis, signal transduction, cell differentiation and hormonal stimulation. HSPs are involved in numerous diseases including cardiovascular pathologies, revealing changes of expression and cell localization. We studied the possible changes in expression level of abundant mitochondrial chaperon Hsp60 and main human cytochrome P450 monooxygenase (2E1 isoform) at dilated cardiomyopathy (DCM) progression at the end stage of heart failure using Western blot analysis. The ischemic and normal humans' hearts were studied as control samples. We observed the decrease of Hsp60 level in cytoplasmic fraction of DCM- and ischemia-affected hearts' left ventricular and significant increase of Hsp60 in mitochondrial fractions of all hearts investigated. At the same time we detected the increase of P450 2E1 expression level in ischemic and dilated hearts' cytoplasmic fractions in comparison with normal myocardium and no detectable changes in microsomal fractions of hearts investigated which could be linked with increased level of oxidative injury for DCM heart muscle. In addition, all the changes described are accompanied by significant decrease of ATPase activity of myosin purified from DCM-affected heart in comparison with normal and ischemic myocardia as well. The data obtained allow us to propose a working hypothesis of functional link between antistress (HSPs) and antioxidative (cytochromes) systems at DCM progression.

Recently, it has been suggested that some heat shock proteins such as Hsp70 and Hsp60 are involved in autoimmune diseases including cardiospecific ones. In this work we focused on the involvement of another wellknown heat shock protein, Hsp90, and its novel co-chaperone,Sgt1, in dilated cardiomyopathy (DCM). We found that the level of autoantibodies against these two proteins was significantly higher in patients with DCM and ischemic heart disease than in sera of healthy donors. We have also analyzed the expression level and subcellular localization of Hsp90 and Sgt1 in diseased myocardia. Using Western blot we found changes in subcellular localization of Hsp90 in the left ventricle of DCM hearts while the total level of this protein remained unchanged. Regarding the Sgt1 protein, we found an increased level in DCM and no changes in subcellular localization. Taken together, our data suggest that Hsp90 and Sgt1 might be involved in the progression of heart failure and might serve as markers for cardiomyopathies of different origin.

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Experimental model of autoimmune myosin-induced injury of BALB/c mouse myocardium, similar to human dilated cardiomyopathy (DCM), has been developed. The immunisation by myosin, purified from DCM-affected human heart initiated the following DCM-like myocardial damage: myocytolysis, cardiosclerosis, thinning of left ventricular wall, changes in cardiac actomyosin ATP-ase activity and increase of anti-myosin autoantibodies level.

The autoantibodies directed against actin and myosine have been detected in the blood sera of patients with dilated cardiomyopathy (DCMP) at the level that was sufficiently higher than in healthy donors. While comparing of the immunogeneicity of these pro teins we have stated that myosine from affected by DCMP myocardium have been more immunogenic then from normal one. In the case of actin the immunogeneicity have been higher for the protein from normal myocard. The investigations of actin by limited proteolysis may suggest that the differencies in immune properties are not connected with primary structure but with structures of higher levels.