ABSTRACT
In the version of this article initially published, the equal contribution of the third author was omitted. The footnote links for that author should be "Sara Nejat1,11" and the correct statement is as follows: "11These authors contributed equally: Sarah A. Dick, Jillian A. Macklin, Sara Nejat." The error has been corrected in the HTML and PDF versions of the article.
ABSTRACT
Macrophages promote both injury and repair after myocardial infarction, but discriminating functions within mixed populations remains challenging. Here we used fate mapping, parabiosis and single-cell transcriptomics to demonstrate that at steady state, TIMD4+LYVE1+MHC-IIloCCR2- resident cardiac macrophages self-renew with negligible blood monocyte input. Monocytes partially replaced resident TIMD4-LYVE1-MHC-IIhiCCR2- macrophages and fully replaced TIMD4-LYVE1-MHC-IIhiCCR2+ macrophages, revealing a hierarchy of monocyte contribution to functionally distinct macrophage subsets. Ischemic injury reduced TIMD4+ and TIMD4- resident macrophage abundance, whereas CCR2+ monocyte-derived macrophages adopted multiple cell fates within infarcted tissue, including those nearly indistinguishable from resident macrophages. Recruited macrophages did not express TIMD4, highlighting the ability of TIMD4 to track a subset of resident macrophages in the absence of fate mapping. Despite this similarity, inducible depletion of resident macrophages using a Cx3cr1-based system led to impaired cardiac function and promoted adverse remodeling primarily within the peri-infarct zone, revealing a nonredundant, cardioprotective role of resident cardiac macrophages.
Subject(s)
Macrophages/physiology , Myocardial Infarction/immunology , Myocardium/pathology , Animals , CX3C Chemokine Receptor 1/metabolism , Cell Differentiation , Cell Lineage , Cell Self Renewal , Gene Expression Profiling , Histocompatibility Antigens Class II/metabolism , Membrane Proteins/metabolism , Mice , Mice, Transgenic , Parabiosis , Receptors, CCR2/genetics , Receptors, CCR2/metabolism , Single-Cell Analysis , Ventricular Remodeling , Vesicular Transport Proteins/metabolismABSTRACT
Innate and adaptive immune cells modulate heart failure pathogenesis during viral myocarditis, yet their identities and functions remain poorly defined. We utilized a combination of genetic fate mapping, parabiotic, transcriptional, and functional analyses and demonstrated that the heart contained two major conventional dendritic cell (cDC) subsets, CD103+ and CD11b+, which differentially relied on local proliferation and precursor recruitment to maintain their tissue residency. Following viral infection of the myocardium, cDCs accumulated in the heart coincident with monocyte infiltration and loss of resident reparative embryonic-derived cardiac macrophages. cDC depletion abrogated antigen-specific CD8+ T cell proliferative expansion, transforming subclinical cardiac injury to overt heart failure. These effects were mediated by CD103+ cDCs, which are dependent on the transcription factor BATF3 for their development. Collectively, our findings identified resident cardiac cDC subsets, defined their origins, and revealed an essential role for CD103+ cDCs in antigen-specific T cell responses during subclinical viral myocarditis.
