Hepatic stellate cells orchestrate clearance of necrotic cells in a hypoxia-inducible factor-1α-dependent manner by modulating macrophage phenotype in mice

J Immunol. 2014 Apr 15;192(8):3847-3857. doi: 10.4049/jimmunol.1303195. Epub 2014 Mar 17.

Abstract

Hypoxia-inducible factor-1α (HIF-1α) is activated in hepatic stellate cells (HSCs) by hypoxia and regulates genes important for tissue repair. Whether HIF-1α is activated in HSCs after acute injury and contributes to liver regeneration, however, is not known. To investigate this, mice were generated with reduced levels of HIF-1α in HSCs by crossing HIF-1α floxed mice with mice that express Cre recombinase under control of the glial fibrillary acidic protein (GFAP) promoter (i.e., HIF-1α-GFAP Cre+ mice). These mice and control mice (i.e., HIF-1α-GFAP Cre- mice) were treated with a single dose of carbon tetrachloride, and liver injury and repair were assessed. After carbon tetrachloride, HIF-1α was activated in HSCs. Although liver injury was not different between the two strains of mice, during resolution of injury, clearance of necrotic cells was decreased in HIF-1α-GFAP Cre+ mice. In these mice, the persistence of necrotic cells stimulated a fibrotic response characterized by extensive collagen deposition. Hepatic accumulation of macrophages, which clear necrotic cells from the liver after carbon tetrachloride, was not affected by HIF-1α deletion in HSCs. Conversion of macrophages to M1-like, proinflammatory macrophages, which have increased phagocytic activity, however, was reduced in HIF-1α-GFAP Cre+ mice as indicated by a decrease in proinflammatory cytokines and a decrease in the percentage of Gr1(hi) macrophages. Collectively, these studies have identified a novel function for HSCs and HIF-1α in orchestrating the clearance of necrotic cells from the liver and demonstrated a key role for HSCs in modulating macrophage phenotype during acute liver injury.

Publication types

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

MeSH terms

  • Animals
  • Carbon Tetrachloride / pharmacology
  • Cell Proliferation
  • Chemical and Drug Induced Liver Injury / genetics
  • Chemical and Drug Induced Liver Injury / metabolism
  • Chemical and Drug Induced Liver Injury / pathology
  • Gene Deletion
  • Hepatic Stellate Cells / drug effects
  • Hepatic Stellate Cells / metabolism*
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Liver Cirrhosis / genetics
  • Liver Cirrhosis / metabolism
  • Liver Cirrhosis / pathology
  • Macrophages / immunology*
  • Macrophages / metabolism*
  • Macrophages / pathology
  • Mice
  • Mice, Transgenic
  • Necrosis
  • Neutrophils / immunology
  • Neutrophils / metabolism
  • Neutrophils / pathology
  • Phenotype*
  • Urokinase-Type Plasminogen Activator / genetics
  • Urokinase-Type Plasminogen Activator / metabolism

Substances

  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Carbon Tetrachloride
  • Urokinase-Type Plasminogen Activator