IL-17 stimulates differentiation of human anti-inflammatory macrophages and phagocytosis of apoptotic neutrophils in response to IL-10 and glucocorticoids

J Immunol. 2013 May 15;190(10):5237-46. doi: 10.4049/jimmunol.1203017. Epub 2013 Apr 17.

Abstract

Exposure of human monocytes/macrophages to anti-inflammatory agents, such as IL-10 or glucocorticoids, can lead to two separate fates: either Fas/CD95-mediated apoptosis or differentiation into regulatory and efferocytic M2c (CD14(bright)CD16(+)CD163(+)Mer tyrosine kinase(+)) macrophages. We found that the prevalent effect depends on the type of Th cytokine environment and on the stage of monocyte-to-macrophage differentiation. In particular, the presence of IFN-γ (Th1 inflammation) or the prolonged exposure to IL-4 (chronic Th2 inflammation) promotes apoptosis of monocytes/macrophages and causes resistance to M2c differentiation, thus provoking impaired clearance of apoptotic neutrophils, uncontrolled accumulation of apoptotic cells, and persistent inflammation. In contrast, the presence of IL-17 (Th17 environment) prevents monocyte/macrophage apoptosis and elicits intense M2c differentiation, thus ensuring efficient clearance of apoptotic neutrophils and restoration of anti-inflammatory conditions. Additionally, the Th environment affects the expression of two distinct Mer tyrosine kinase isoforms: IL-4 downregulates the membrane isoform but induces an intracellular and Gas6-dependent isoform, whereas IFN-γ downregulates both and IL-17 upregulates both. Our data support an unexpected role for IL-17 in orchestrating resolution of innate inflammation, whereas IFN-γ and IL-4 emerge as major determinants of IL-10 and glucocorticoid resistance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Inflammatory Agents / pharmacology
  • Apoptosis
  • Cell Differentiation*
  • Cells, Cultured
  • Glucocorticoids / pharmacology
  • Humans
  • Inflammation / immunology
  • Inflammation / metabolism
  • Interferon-gamma / immunology*
  • Interleukin-10 / metabolism
  • Interleukin-10 / pharmacology
  • Interleukin-17 / immunology
  • Interleukin-17 / metabolism*
  • Interleukin-17 / pharmacology
  • Interleukin-4 / immunology
  • Macrophages / cytology*
  • Macrophages / immunology*
  • Macrophages / metabolism
  • Monocytes / metabolism
  • Neutrophils / cytology
  • Neutrophils / immunology*
  • Neutrophils / metabolism
  • Phagocytosis*
  • Protein Isoforms
  • fas Receptor / metabolism

Substances

  • Anti-Inflammatory Agents
  • Glucocorticoids
  • Interleukin-17
  • Protein Isoforms
  • fas Receptor
  • Interleukin-10
  • Interleukin-4
  • Interferon-gamma