IL-12 is required for differentiation of pathogenic CD8+ T cell effectors that cause myocarditis
Nir Grabie, Michael W. Delfs, Jason R. Westrich, Victoria A. Love, George Stavrakis, Ferhaan Ahmad, Christine E. Seidman, Jonathan G. Seidman, Andrew H. Lichtman
Nir Grabie, Michael W. Delfs, Jason R. Westrich, Victoria A. Love, George Stavrakis, Ferhaan Ahmad, Christine E. Seidman, Jonathan G. Seidman, Andrew H. Lichtman
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Article Autoimmunity

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 ovalbumin-expressing 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.

Authors

Nir Grabie, Michael W. Delfs, Jason R. Westrich, Victoria A. Love, George Stavrakis, Ferhaan Ahmad, Christine E. Seidman, Jonathan G. Seidman, Andrew H. Lichtman

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Phenotype of OT-I effector cells differentiated in vitro in the absence ...
Phenotype of OT-I effector cells differentiated in vitro in the absence or presence of exogenous IL-12. Culture conditions are described in Methods. T cells were harvested from the differentiation cultures without added IL-12 (OT-I0) or with exogenously added 10 ng/ml IL-12 (OT-IIL-12) on day 5 for analysis. (a) Thy1.1, CD25, and CD44 expression by flow cytometry. PE, phycoerythrin; FITC, Fluorescein isothiocyanate. (b) Chemokine receptor expression by real-time RT-PCR; data represent means ± SEM of three separate experiments. *P = 0.037 and **P = 0.004 (t test). (c) IFN-γ secretion upon restimulation with immobilized anti-CD3 and anti-CD28. (d) Cytolytic activity against SIINFEKL-pulsed EL4 cells by a flow cytometric assay. E:T, effector:target. The data in (a), (c), and (d) are from one typical experiment out of four performed.