Aims: To quantify and functionally characterize the intramyocardial T-cells in endomyocardial biopsies (EMBs) from patients presenting with acute myocarditis (AMC) and dilated cardiomyopathy (DCM).
Methods and results: Expression of genes characterizing Th1 [interferon (IFN)γ, Tbet-1, Eomesodermin, interleukin (IL)-27], Th2 (IL-4, IL-5, GATA3), Th17 (IL-17), regulatory [regulatory T-cells (Treg); FoxP3, TGFβ, IL-10], anergic (GRAIL), and cytotoxic T-cells (CTLs: Perforin, Granulysin, Granzyme A), as well as of functional T-cell receptor Vbeta (TRBV) families were investigated in EMBs from AMC patients (n= 58) and DCM patients (n= 34) by pre-amplified real-time reverse transcription-polymerase chain reaction. These data were compared with EMBs from n= 19 controls. Expression of CD3d, CD3z, and TRBC (T-cell receptor beta constant region) were associated with the immunohistological diagnosis of inflammatory cardiomyopathy (DCMi). In EMBs from DCM patients with increased CD3d expression, significantly increased markers of Th1 (IFNγ, T-bet, Eomesodermin), regulatory T-cells (Treg; FoxP3, TGFβ), and cytotoxic T-cells (CTLs: Perforin, Granulysin, Granzyme A) were present, while no differential polarization of T-cells was found in EMBs form AMC patients. A differential dominance of distinct functional TRBV families was associated with different cardiotropic viruses: TRBV 11 and 24 with Parvovirus B19; TRBV4, 10 and 28 with human herpes virus type 6; and TRBV14 for Coxsackie virus, respectively.
Conclusions: The T-cell infiltrates in human DCMi are characterized by differential expression of functional T-cell markers indicating Th1, Treg, and CTLs, while no major role could be confirmed for Th17. The virus-associated differential TRBV dominance suggests an antiviral specificity of virus-induced T-cell responses in human DCMi.