Investigation into CardiacMyhc-α 334–352-Specific TCR Transgenic Mice Reveals a Role for Cytotoxic CD4 T Cells in the Development of Cardiac Autoimmunity

Authors

Meghna Sur, University of Nebraska-LincolnFollow
Mahima T. Rasquinha, University of Nebraska - LincolnFollow
Kiruthiga Mone, University of Nebraska-LincolnFollow
Chandirasegaran Massilamany, University of Nebraska- Lincoln, CRISPR Therapeutics
Ninaad Lasrado, University of Nebraska-Lincoln, Harvard Medical School
Channabasavaiah B. Gurumurthy, University of Nebraska Medical CenterFollow
Raymond A. Sobel, Stanford University
Jay Reddy, University of Nebraska - LincolnFollow

Document Type

Article

Date of this Version

1-26-2024

Citation

Sur, M.; Rasquinha, M.T.; Mone, K.; Massilamany, C.; Lasrado, N.; Gurumurthy, C.; Sobel, R.A.; Reddy, J. Investigation into Cardiac Myhc-α 334–352-Specific TCR TransgenicMice Reveals a Role for Cytotoxic CD4 T Cells in the Development of Cardiac Autoimmunity. Cells 2024, 13, 234. https://doi.org/ 10.3390/cells13030234

Comments

Open access.

Abstract

Myocarditis is one of the major causes of heart failure in children and young adults and can lead to dilated cardiomyopathy. Lymphocytic myocarditis could result from autoreactive CD4+ and CD8+ T cells, but defining antigen specificity in disease pathogenesis is challenging. To address this issue, we generated T cell receptor (TCR) transgenic (Tg) C57BL/6J mice specific to cardiac myosin heavy chain (Myhc)-α 334–352 and found that Myhc-α-specific TCRs were expressed in both CD4⁺ and CD8⁺ T cells. To investigate if the phenotype is more pronounced in a myocarditis-susceptible genetic background, we backcrossed with A/J mice. At the fourth generation of backcrossing, we observed that Tg T cells from naïve mice responded to Myhc-α 334–352, as evaluated by proliferation assay and carboxyfluorescein succinimidyl ester staining. The T cell responses included significant production of mainly pro-inflammatory cytokines, namely interferon (IFN)-γ, interleukin-17, and granulocyte macrophage-colony stimulating factor. While the naïve Tg mice had isolated myocardial lesions, immunization with Myhc-α 334–352 led to mild myocarditis, suggesting that further backcrossing to increase the percentage of A/J genome close to 99.99% might show a more severe disease phenotype. Further investigations led us to note that CD4⁺ T cells displayed the phenotype of cytotoxic T cells (CTLs) akin to those of conventional CD8⁺ CTLs, as determined by the expression of CD107a, IFN-γ, granzyme B natural killer cell receptor (NKG)2A, NKG2D, cytotoxic and regulatory T cell molecules, and eomesodermin. Taken together, the transgenic system described in this report may be a helpful tool to distinguish the roles of cytotoxic cardiac antigen-specific CD4⁺ T cells vs. those of CD8⁺ T cells in the pathogenesis of myocarditis.