The expression of heat shock protein 60 in patients with dilated cardiomyophathy

Objective: Heat shock proteins (hsps) have been shown to be important antigens in a number of autoimmune diseases. We have previously shown the presence of autoantibodies against hsp60 in a high proportion of patients with dilated cardiomyopathy (DCM). This study set out to investigate the expression of hsp60 in the myocardium of 30 patients with DCM and a control group of 30 normal donors. Design: The expression of hsp60 was quantitated at the protein and mRNA level by Western blotting and RT-PCR, respectively, and its distribution was investigated by immunocytochemistry. Results: Quantitation of hsp60 showed a 5-fold increase in the DCM hearts over that in the donor hearts. By immunocytochemistry 13 patients with DCM showed increased positive staining localised to the connective tissue. Semi-quantitative RT-PCR analysis of hsp60 showed a significantly increased amount of hsp60 at the mRNA level in the DCM hearts than in the controls. Conclusions: These results unequivocally demonstrate a raised level of expression of endogenous hsp60 in the myocardium of patients with DCM. The increased expression of hsp60 in the myocardium of patients with DCM may render such cells susceptible to react with circulating autoantibodies to hsp60 and hsp65 found in a high proportion of patients with this disease. Received: 15 July 1998, Returned for revision: 10 September 1998, Revision received: 30 September 1998, Accepted: 16 October 1998