Anti beta-adrenergic receptor antibodies in chronic Chagas' Disease

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Abstract

Background and objectives Recent studies have demonstrated the presence of anti beta-adrenergic receptor antibodies in a third of the patients with idiopathic dilated cardiomyopathy. These antibodies have stimulating and inhibitor effects through which they might be involved in the pathogenesis of this myocardial disease . In 1976 Sterin-Borda and col . Indirectly discovered that ABA could be present in the serum and IgG of patients with Chagas' disease. Seeing as neither the prevalence of ABA nor their association to the clinical presentation forms of chronic Chagas cardiomyopathy were evaluated, the answer to these questions became the purpose of our study.

Methods and results

The serum of 48 patients with Chagas disease (8 with severe Chagas cardiomyopathy, 16 with "electric" Chagas cardiomyopathy and 24 without apparent cardiac impairment) and of 67 control patients (55 healthy subjects and 12 patients with heart disease other than Chagas' disease and idiopathic dilated cardiomyopathy) was analyzed . The presence of anti-beta-adrenergic receptor antibodies was detected by ELISA methods using synthetic peptides resulting from the aminoacid sequence in the type 1(aminoacid 183 to 208) and type 2 (aminoacid 172 to 197) beta-adrenergic receptors. Results were considered positive if serum optic density exceeded control mean optic density by more than 2 standard deviations . In the serum of 16 (23 .9 %) control patients anti beta-adrenergic receptor antibodies were detected, binding to type 1 (17.9 %) and/or type 2 (11 .9 %) peptides . No antibodies were detected in the remaining 51 (76 %) control patients . In contrast, the serum of only 22 (45 .8 %) patients with Chagas' disease were negative for anti beta-adrenergic receptor antibodies . Antibodies against type 1 and type 2 peptides were present in the serum of 23 (47 .9 %) and 16 (33 .3 %) disease patients, respectively. There were no significant differences amongst those with severe Chagas cardiomyopathy, "electric" Chagas cadiomyopathy and without apparent cardiopathy.

Conclusions

The results of this study show a high prevalence of anti beta-adrenergic receptor antibodies, predominantly against beta 1 adrenergic receptors, in chronic Chagas' disease . As it is not clear in which patients the anti beta-adrenergic receptor antibodies are functionally active, their role in the pathogenesis of Chagas cardiomyopathy remains unknown . Future investigations could determine the value of these antibodies in the diagnostic and therapeutic approach of Chagas' disease.