Myocardial Immune Cells: The Basis of Cardiac Immunology

Abstract

The mammalian heart is characterized by the presence of striated myocytes, which allow continuous rhythmic contraction from early embryonic development until the last moments of life. However, the myocardium contains a significant contingent of leukocytes from every major class. This leukocyte pool includes both resident and nonresident immune cells. Over recent decades, it has become increasingly apparent that the heart is intimately sensitive to immune signaling and that myocardial leukocytes exhibit an array of critical functions, both in homeostasis and in the context of cardiac adaptation to injury. Here, we systematically review current knowledge of all major leukocyte classes in the heart, discussing their functions in health and disease. We also highlight the connection between the myocardium, immune cells, lymphoid organs, and both local and systemic immune responses.

A murine model ofTrypanosoma brucei-induced myocarditis and cardiac dysfunction

“…Of the different macrophage subsets, the CCR2 hi MHC-II hi population experienced the largest increase. This subset represents pro-inflammatory, monocyte-derived macrophages, indicating that T. brucei infection causes an influx of pro-inflammatory macrophages into the heart 41,42 . There was also a significant elevation of both CD8+ T cells and natural killer (NK) cells, even though cell-mediated immunity is relatively ineffective at responding to T. brucei , which is an extracellular parasite 43,4441,42 .…”

“…In agreement with our histopathological finding of myocarditis, we found that most intracardiac immune cell populations were elevated, especially CD4+ and CD8+ T cells, macrophages, and NK cells. The most highly elevated macrophage subset was the CCR2 hi MHC-II hi population, which represents pro-inflammatory, monocyte-derived macrophages 41,42 . Such pro-inflammatory macrophages are necessary for an effective immune response to T. brucei 40 .…”

Myocardial B cells have specific gene expression and predicted interactions in Dilated Cardiomyopathy and Arrhythmogenic Right Ventricular Cardiomyopathy

“…The immune system has been highlighted as a key potential player in the development of heart failure [1][2][3][4] . The role of macrophages, monocytes, and T cells in the context of heart failure has been extensively studied in both human and animal models of cardiomyopathy 1 .…”

“…The immune system has been highlighted as a key potential player in the development of heart failure [1][2][3][4] . The role of macrophages, monocytes, and T cells in the context of heart failure has been extensively studied in both human and animal models of cardiomyopathy 1 . In recent years, there has been increasing interest in understanding the role that B cells play in cardiomyopathy, but the available data is limited 5 .…”

B-Cell Immune Checkpoints Come of Age in Cardio-oncology

“…2 Mice with congenitally absent B-cells also have smaller cross-sectional myocardial fibers than wild-type mice, though the basis for these observations has yet to be conclusively defined. 1…”