An Abundant Tissue Macrophage Population in the Adult Murine Heart with a Distinct Alternatively-Activated Macrophage Profile

by Alexander R. Pinto, Rosa Paolicelli, Ekaterina Salimova, Janko Gospocic, Esfir Slonimsky, Daniel Bilbao-Cortes, James W. Godwin, Nadia A. Rosenthal

Cardiac tissue macrophages (cTMs) are a previously uncharacterised cell type that we have identified and characterise here as an abundant GFP⁺ population within the adult Cx3cr1GFP/+ knock-in mouse heart. They comprise the predominant myeloid cell population in the myocardium, and are found throughout myocardial interstitial spaces interacting directly with capillary endothelial cells and cardiomyocytes. Flow cytometry-based immunophenotyping shows that cTMs exhibit canonical macrophage markers. Gene expression analysis shows that cTMs (CD45⁺CD11b⁺GFP⁺) are distinct from mononuclear CD45⁺CD11b⁺GFP⁺ cells sorted from the spleen and brain of adult Cx3cr1GFP/+ mice. Gene expression profiling reveals that cTMs closely resemble alternatively-activated anti-inflammatory M2 macrophages, expressing a number of M2 markers, including Mrc1, CD163, and Lyve-1. While cTMs perform normal tissue macrophage homeostatic functions, they also exhibit a distinct phenotype, involving secretion of salutary factors (including IGF-1) and immune modulation. In summary, the characterisation of cTMs at the cellular and molecular level defines a potentially important role for these cells in cardiac homeostasis.

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Syndicated from:PLoS ONE

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