Identification of a cytochrome P4502E1/Bid/C1q-dependent axis mediating inflammation in adipose tissue after chronic ethanol feeding to mice

J Biol Chem. 2011 Oct 14;286(41):35989-35997. doi: 10.1074/jbc.M111.254201. Epub 2011 Aug 19.

Abstract

Chronic, heavy alcohol exposure results in inflammation in adipose tissue, insulin resistance, and liver injury. Here we have identified a CYP2E1/Bid/C1q-dependent pathway that is activated in response to chronic ethanol and is required for the development of inflammation in adipose tissue. Ethanol feeding for 25 days to wild-type (C57BL/6J) mice increased expression of multiple markers of adipose tissue inflammation relative to pair-fed controls independent of increased body weight or adipocyte size. Ethanol feeding increased the expression of CYP2E1 in adipocytes, but not stromal vascular cells, in adipose tissue and Cyp2e1(-/-) mice were protected from adipose tissue inflammation in response to ethanol. Ethanol feeding also increased the number of TUNEL-positive nuclei in adipose tissue of wild-type mice but not in Cyp2e1(-/-) or Bid (-/-) mice. Apoptosis contributed to adipose inflammation, as the expression of multiple inflammatory markers was decreased in mice lacking the Bid-dependent apoptotic pathway. The complement protein C1q binds to apoptotic cells, facilitating their clearance and activating complement. Making use of C1q-deficient mice, we found that activation of complement via C1q provided the critical link between CYP2E1/Bid-dependent apoptosis and onset of adipose tissue inflammation in response to chronic ethanol. In summary, chronic ethanol increases CYP2E1 activity in adipose, leading to Bid-mediated apoptosis and activation of complement via C1q, finally resulting in adipose tissue inflammation. Taken together, these data identify a novel mechanism for the development of adipose tissue inflammation that likely contributes to the pathophysiological effects of ethanol.

Publication types

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

MeSH terms

  • Adipocytes / metabolism*
  • Adipocytes / pathology
  • Adipose Tissue / metabolism*
  • Adipose Tissue / pathology
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • BH3 Interacting Domain Death Agonist Protein / genetics
  • BH3 Interacting Domain Death Agonist Protein / metabolism*
  • Central Nervous System Depressants / adverse effects*
  • Central Nervous System Depressants / pharmacokinetics
  • Complement C1q / genetics
  • Complement C1q / metabolism*
  • Cytochrome P-450 CYP2E1 / genetics
  • Cytochrome P-450 CYP2E1 / metabolism*
  • Ethanol / adverse effects*
  • Ethanol / pharmacology
  • Female
  • Inflammation / chemically induced
  • Inflammation / genetics
  • Inflammation / metabolism
  • Inflammation / pathology
  • Mice
  • Mice, Knockout

Substances

  • BH3 Interacting Domain Death Agonist Protein
  • Bid protein, mouse
  • Central Nervous System Depressants
  • Ethanol
  • Complement C1q
  • Cytochrome P-450 CYP2E1