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Cardiac myofibroblast engulfment of dead cells facilitates recovery after myocardial infarction.

ABSTRACT: Myocardial infarction (MI) results in the generation of dead cells in the infarcted area. These cells are swiftly removed by phagocytes to minimize inflammation and limit expansion of the damaged area. However, the types of cells and molecules responsible for the engulfment of dead cells in the infarcted area remain largely unknown. In this study, we demonstrated that cardiac myofibroblasts, which execute tissue fibrosis by producing extracellular matrix proteins, efficiently engulf dead cells. Furthermore, we identified a population of cardiac myofibroblasts that appears in the heart after MI in humans and mice. We found that these cardiac myofibroblasts secrete milk fat globule-epidermal growth factor 8 (MFG-E8), which promotes apoptotic engulfment, and determined that serum response factor is important for MFG-E8 production in myofibroblasts. Following MFG-E8-mediated engulfment of apoptotic cells, myofibroblasts acquired antiinflammatory properties. MFG-E8 deficiency in mice led to the accumulation of unengulfed dead cells after MI, resulting in exacerbated inflammatory responses and a substantial decrease in survival. Moreover, MFG-E8 administration into infarcted hearts restored cardiac function and morphology. MFG-E8-producing myofibroblasts mainly originated from resident cardiac fibroblasts and cells that underwent endothelial-mesenchymal transition in the heart. Together, our results reveal previously unrecognized roles of myofibroblasts in regulating apoptotic engulfment and a fundamental importance of these cells in recovery from MI.

SUBMITTER: Nakaya M

PROVIDER: S-EPMC5199696 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Cardiac myofibroblast engulfment of dead cells facilitates recovery after myocardial infarction.

Nakaya Michio M Watari Kenji K Tajima Mitsuru M Nakaya Takeo T Matsuda Shoichi S Ohara Hiroki H Nishihara Hiroaki H Yamaguchi Hiroshi H Hashimoto Akiko A Nishida Mitsuho M Nagasaka Akiomi A Horii Yuma Y Ono Hiroki H Iribe Gentaro G Inoue Ryuji R Tsuda Makoto M Inoue Kazuhide K Tanaka Akira A Kuroda Masahiko M Nagata Shigekazu S Kurose Hitoshi H

The Journal of clinical investigation 20161205 1

Myocardial infarction (MI) results in the generation of dead cells in the infarcted area. These cells are swiftly removed by phagocytes to minimize inflammation and limit expansion of the damaged area. However, the types of cells and molecules responsible for the engulfment of dead cells in the infarcted area remain largely unknown. In this study, we demonstrated that cardiac myofibroblasts, which execute tissue fibrosis by producing extracellular matrix proteins, efficiently engulf dead cells. ...[more]

PMID: 27918308

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Project description:Pericytes have been implicated in regulation of inflammatory, reparative, fibrogenic and angiogenic responses in several different organs and pathologic conditions. Although the adult mammalian heart contains abundant pericytes, their fate and involvement in myocardial disease remains unknown. We used NG2Dsred;PDGFRaEGFP pericyte-fibroblast dual reporter mice and inducible NG2CreER mice to study the fate and phenotypic modulation of pericytes in a model of myocardial infarction. The transcriptomic profile of pericyte-derived fibroblasts was studied using PCR arrays. The transcriptomic profile of NG2 lineage cells (pericytes) was studied in control and infarcted hearts using single cell RNA-sequencing analysis. The role of TGF-b signaling in regulation of pericyte phenotype in vivo was investigated using pericyte-specific Tgfbr2 knockout mice. In vitro, the effects of TGF-b were studied in cultured human placental pericytes.In normal mouse hearts, NG2 and PDGFRa identified distinct non-overlapping populations of pericytes and fibroblasts respectively. Following myocardial infarction, a population of cells expressing both pericyte and fibroblast markers emerged. These cells expressed large amounts of extracellular matrix (ECM) genes. Lineage tracing demonstrated that in the infarcted region, a subpopulation of pericytes underwent fibroblast conversion. Single cell RNA-seq experiments demonstrated expansion and diversification of pericyte-derived cells in the infarct, associated with emergence of subpopulations exhibiting accentuated matrix gene synthesis. In vitro studies and the profile of pericyte-derived fibroblasts identified TGF-b as a potentially causative mediator in fibrogenic activation of infarct pericytes. However, pericyte-specific Tgfbr2 disruption had no significant effects on myofibroblast infiltration and collagen deposition in the infarct. Pericyte-specific TGF-b signaling was involved in vascular maturation, mediating formation of a mural cell coat investing infarct neovessels. These reparative effects of infarct pericytes protected the infarcted heart from dilative remodeling.

Dataset Information

Cardiac myofibroblast engulfment of dead cells facilitates recovery after myocardial infarction.

Publications

Cardiac myofibroblast engulfment of dead cells facilitates recovery after myocardial infarction.

Similar Datasets

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