IL-12 is required for differentiation of pathogenic CD8+ T cell effectors that cause myocarditis

Abstract

Cardiac antigen-specific CD8 + T cells are involved in the autoimmune component of human myocarditis. Here, we studied the differentiation and migration of pathogenic CD8 + T cell effector cells in a new mouse model of autoimmune myocarditis. A transgenic mouse line was derived that expresses cardiac myocyte restricted membrane-bound ovalbumin (CMy-mOva). The endogenous adaptive immune system of CMy-mOva mice displays tolerance to ovalbumin. Adoptive transfer of naive CD8 + T cells from the ovalbumin-specific T cell receptor-transgenic (TCR-transgenic) OT-I strain induces myocarditis in CMy-mOva mice only after subsequent inoculation with ovalbuminexpressing vesicular stomatitis virus (VSV-Ova). OT-I effector T cells derived in vitro in the presence or absence of IL-12 were adoptively transferred into CMy-mOva mice, and the consequences were compared. Although IL-12 was not required for the generation of cytolytic and IFN-γ-producing effector T cells, only effectors primed in the presence of IL-12 infiltrated CMy-mOva hearts in significant numbers, causing lethal myocarditis. Furthermore, analysis of OT-I effectors collected from a mediastinal draining lymph node indicated that only effectors primed in vitro in the presence of IL-12 proliferated in vivo. These data demonstrate the importance of IL-12 in the differentiation of pathogenic CD8 + T cells that can cause myocarditis.

Autoimmune cardiac-specific T cell responses in dilated cardiomyopathy

“…However, a recent study in transgenic animals expressing ovalbumin under the control of the cardiac myosin heavy chain promoter showed a pathogenic role for CD8+ T cells [32]. Our results have shown enhanced CD4+ T cell proliferation and attenuated CD8+ T cell proliferation in response to whole cardiac myosin as well as to epitopes derived from cardiac α-myosin heavy chain [30].…”

Imaging Granzyme B Activity Assesses Immune-Mediated Myocarditis

“…Our previous investigation demonstrated maximal cardiac damage at 96 – 144 hours after transfer. 10 This study used conditions that yielded increased granzyme B expression and produced cardiac damage while minimizing mortality 5 days after transfer. In vivo FMT imaging of the time course of probe uptake, enzymatic cleavage, and clearance informed the choice of 24 hours post-injection to study the nanoprobe, a time that allows localization and activation while minimizing background signals.…”

“…10 In a survival study, CMy-Tg and WT mice received 2.0, 3.5, or 5.0 × 10 6 CD8 + OT-1 T cells. Their survival was monitored for 28 days.…”

“…The transgenic mouse strain CMy-mOva expresses ovalbumin (Ova) in cardiac myocytes. 10 Adoptive transfer of T cell receptor (TCR) transgenic Ova peptide (SIINFEKL)-specific CD8 + T cells to CMy-mOva transgenic (CMy-Tg) mice induces progressive myocarditis of varying severity, depending on the number of T cells transferred. 11 This type of experimental myocarditis involves a fundamental mechanism implicated in many kinds of human myocarditis.…”

Involvement of Endoplasmic Reticulum Stress–Mediated C/EBP Homologous Protein Activation in Coxsackievirus B3–Induced Acute Viral Myocarditis

“…The severity of myocarditis was assessed by a previously described using 0 to 4 scale, in which 0=no inflammation; 1=1-5 distinct mononuclear inflammatory foci with involvement of 5% or less of the cross-sectional area; 2=>5 distinct mononuclear inflammatory foci, or involvement of between 5% and 20% of the cross-sectional area; 3=diffuse mononuclear inflammation involving >20% of the area, without necrosis; and 4=diffuse inflammation with necrosis. 22 Immunohistochemical staining were performed using the following antibodies: F4/80 (1:50 dilution, Santa Cruz, Santa Cruz, CA), KDEL (1:200 dilution, Santa Cruz), CHOP (1:50 dilution, Santa Cruz), and CVB3 viral protein (VP1, 1:200, Novocastra, Buffalo Grove, IL). Image-Pro Plus (Media Cybernetics, Warrendale, PA) was applied to determine quantitative results (positive staining area/total area).…”