Research Highlights: Macrophages Pick-up “Trash” from Heart Muscles

By Noah Smith – Own work, CC BY-SA 4.0,

Original Article:

  • Cardiomyocytes are the cells responsible for generating contractile force in the intact heart.
  • Cardiomyocytes are subjected to the intense mechanical stress and metabolic demands of the beating heart.
  • Cardiomyocytes are long-lived and rarely renewed.
  • It is unclear whether these cardiomyocytes manage to preserve homeostasis on their own.
  • Researchers discovered that macrophages lodged within the health heart tissue, actively took material, including mitochondria, derived from cardiomyocytes.
  • Cardiomyocytes ejected dysfunctional mitochondria and other cargo in dedicated membranous particles reminiscent of neural exophers.
  • The ejection process is driven by the cardiomyocyte’s autophagy machinery that was enhanced during cardiac stress.
  • Autophagy is the natural, regulated mechanism of the cell that removes unnecessary or dysfunctional cellular components.
  • Depletion of cardiac macrophages or deficiency in the phagocytic receptor Mertk resulted in defective elimination of mitochondria from the myocardial tissue, activation of the inflammasome, impaired autophagy, accumulation of anomalous mitochondria in cardiomyocytes, metabolic alterations, and ventricular dysfunction.
  • Inflammasome refers to the multiprotein intracellular complex that detects pathogens and sterile stressors, and that activates the highly pro-inflammatory cytokines.
  • The conclusion identify an immune-tissue pair in the murine heart that enables transfer of unfit material to preserve metabolic stability and organ function.


Klionsky DJ (August 2008). “Autophagy revisited: a conversation with Christian de Duve”Autophagy. 4 (6): 740–3. doi:10.4161/auto.6398PMID 18567941.

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