A scavenging system against internal pathogens promoted by the circulating protein apoptosis inhibitor of macrophage (AIM)

Semin Immunopathol. 2018 Nov;40(6):567-575. doi: 10.1007/s00281-018-0717-6. Epub 2018 Oct 11.


An internal system designed to ward off and remove unnecessary or hazardous materials is intrinsic to animals. In addition to exogenous pathogens, a number of self-molecules, such as apoptotic or necrotic dead cells, their debris, and the oxides or peroxides of their cellular components, are recognized as extraneous substances. It is essential to eliminate these internal pathogens as quickly as possible because their accumulation can cause chronic inflammation as well as autoimmune responses, possibly leading to onset or progression of certain diseases. Apoptosis inhibitor of macrophage (AIM, also called CD5L) is a circulating protein that is a member of the scavenger receptor cysteine-rich superfamily, and we recently found that during acute kidney injury, AIM associates with intraluminal dead cell debris accumulated in renal proximal tubules and enhances clearance of luminal obstructions, thereby facilitating repair. Thus, AIM acts as a marker for phagocytes so that they can efficiently recognize and engulf the debris as their targets. In this chapter, we give an overview of the professional and non-professional phagocytes, and how soluble scavenging molecules such as AIM contribute to improvement of diseases by stimulating phagocytic activity.

Keywords: Acute kidney injury; Apoptosis inhibitor of macrophage; Macrophage; Non-professional phagocyte; Phagocytosis; Scavenger receptor.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Acute Kidney Injury / etiology
  • Acute Kidney Injury / metabolism
  • Acute Kidney Injury / pathology
  • Animals
  • Apoptosis Regulatory Proteins
  • Biomarkers
  • Disease Susceptibility
  • Humans
  • Inhibitor of Apoptosis Proteins / blood
  • Inhibitor of Apoptosis Proteins / metabolism*
  • Ligands
  • Macrophages / immunology*
  • Macrophages / metabolism*
  • Phagocytes / immunology
  • Phagocytes / metabolism
  • Phagocytosis
  • Receptors, Scavenger / metabolism*
  • Scavenger Receptors, Class B / metabolism


  • Apoptosis Regulatory Proteins
  • Biomarkers
  • CD5L protein, human
  • Inhibitor of Apoptosis Proteins
  • Ligands
  • Receptors, Scavenger
  • Scavenger Receptors, Class B