| Recently, functional TSH-R was demonstrated in human heart and in cultured mouse cardiomyocytes (47). Furthermore, a case of Graves' disease in a 25-yr-old man, who developed cardiomyopathy with severe heart failure, was reported. Pathological examination of the myocardial biopsies showed fibroblast infiltration and degenerative changes. After the cardiomyopathy subsided the patient developed goitre and ophthalmopathy, suggesting a common pathogenesis for the cardiomyopathy and orbitopathy (48). Using the reverse transcriptase- polymerase chain reaction and DNA sequencing, TSH-R mRNA was identified in the patients' heart. These findings question the traditional concept of TSH and TSH- R antibodies (Ab) as exclusively acting on thyroid tissue. Already, the possible actions of TSH-R Ab on specific TSH-R in orbital tissue provide interesting evidence for a mechanism in ophthalmopathy associated with Graves' disease (49). Thus, binding of TSH-R Ab to cardiac TSH-R may be directly involved in this pathology. Taken together, these data indicate that autoimmunity against the TSH-R may contribute to both the cardiomyopathy and ophthalmopathy in similar cases of Graves' disease. |
