The Immunology of Cardiovascular Homeostasis and Pathology
Macrophages are principally recognized as an important cell type for removal of tissue debris and as sentinels for tissue damage and foreign antigens. However, macrophages also participate in a diverse range of biological processes including angiogenesis, fibrosis, immune modulation, cell survival, and stem cell mobilization. Cardiac tissue macrophages (cTMs) are a heterogeneous population of phagocytic cells with distinct ontogenetic, phenotypic, and functional characteristics. While our understanding of cTMs has increased substantially over the last 5 years, large gaps in our knowledge regarding the cell biology of cTMs exist, in particular, the development of their unique phenotype and their roles in cardiac homeostasis and tissue stress. This review aims to discuss the current knowledge regarding cTMs and identify key questions that must be addressed to gain a better understanding of the role of cTMs in tissue development, homeostasis, and disease.