Organized Chaos: Deciphering Immune Cell Heterogeneity’s Role in Inflammation in the Heart

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  Figure 1. Immune cell heterogeneity in cardiovascular homeostasis and disease. (A) The Goldilocks zone post-myocardial infarction (MI) is defined by the balance of immune cells needed for cardiac healing. Excessive or prolonged inflammation may lead to increased cardiac rupture due to disproportionate collagen deposition, infarct expansion through phagocytosis of healthy cardiomyocytes, or increased dilation of the left ventricle, which leads to an increased risk of developing heart failure. (B) During homeostasis, yolk-sac derived resident cardiac macrophages are the dominant immune cell type, with evidence that dendritic cells, neutrophils, and T-cells are also present, but in low abundance. Post-MI, resident cardiac macrophages are replaced by monocyte-derived macrophages, which have a pro-inflammatory phenotype. There is also an increase in dendritic cell activation (e.g., CD209) and abundance. Neutrophil abundance increases while function changes over time in the infarcted myocardium, and an increase in effector T-cell subsets is seen. In models of pressure overload (PO), resident and recruited macrophages, play a role in fibrotic development through activation of other cell types.…