T Cells With Similar T-Cell Receptor ß-Chain Complementarity-Determining Region 3 Motifs Infiltrate Inflammatory Lesions of Synthetic Peptides Inducing Rat Autoimmune Myocarditis

From the First Department of Internal Medicine (H.H., T. Inomata, Y.O., S.H., Y.O., M.K., Y.A.), Niigata University School of Medicine, Niigata, Japan, and the Department of Internal Medicine (T. Izumi), Kitasato University School of Medicine, Sagamihara, Japan.

Correspondence to Haruo Hanawa, MD, First Department of Internal Medicine, Niigata University School of Medicine, Asahi-machi 1-754, Niigata 951, Japan.

Abstract—Experimental autoimmune myocarditis (EAM) resembles the giant cell myocarditis seen in humans, and recurrent forms lead to dilated cardiomyopathy. EAM has been shown to be a T cell–mediated autoimmune myocarditis. We have previously shown that cDNA encoding Vß complementarity-determining region (CDR) 3 from heart– and pericardial space–infiltrating T cells in EAM induced by rod cardiac myosin contains more restricted sequences than that from normal spleen T cells. Recently, it has become apparent that several epitopes of EAM exist in rod cardiac myosin; therefore, T cells infiltrating into lesions may recognize certain epitopes in EAM induced by rod cardiac myosin. In this study, we examined heart– and pericardial space–infiltrating T-cell clonotypes in EAM induced by synthetic peptides of cardiac myosin. EAM was produced by immunization with synthetic peptides corresponding to N-terminally acetylated amino acids 1539 to 1555 of rat cardiac myosin heavy chain. Five of 12 rats receiving synthetic peptides developed macroscopic signs of myocarditis. To examine T-cell receptor (TCR) Vß expression and CDR3 of the TCR ß chain of lesion-infiltrating T cells in EAM, total RNA was isolated from heart, pericardial effusion, spleen, lymph node, and peripheral blood. TCR Vß expression of the T cells infiltrating the lesions revealed a predominance of Vß4. On the basis of single-strand conformation polymorphism analysis for CDR3 of the TCR Vß4 chain, heart– and pericardial space–infiltrating T cells were considered to be oligoclonal, whereas spleen, lymph node, and peripheral blood in a rat with EAM and spleen in a native rat were considered to be polyclonal. In the same rat, clonotypes of heart-infiltrating T cells were almost the same as those of pericardial space–infiltrating T cells. Furthermore, on sequence analysis for CDR3 of the TCR Vß4 chain, the amino acid motifs were similar among T cells infiltrating into lesions of different EAM rats. In the present study, TCR ß chains of heart– and pericardial space–infiltrating T cells in EAM induced by synthesized peptide consisting of 17 amino acids were examined. Vß4+ T cells with similar Vß CDR3 motifs that infiltrate the heart and pericardial space may recognize the same epitope.

Key Words: myocarditis • T-cell receptor • epitope • cardiomyopathy • immune system