Opposing roles of RAGE and Myd88 signaling in extensive liver resection

FASEB J. 2012 Feb;26(2):882-93. doi: 10.1096/fj.11-192997. Epub 2011 Nov 10.

Abstract

In extensive liver resection secondary to primary or metastatic liver tumors, or in living donor liver transplantation, strategies to quell deleterious inflammatory responses and facilitate regeneration are essential. The receptor for advanced glycation endproducts (RAGE) and myeloid differentiating factor 88 (Myd88) are implicated in the inflammatory response. To establish the contributions of RAGE vs. Myd88 signaling in extensive liver resection, we probed the effect of RAGE and/or Myd88, the latter primarily a key transducer of major toll-like receptors and also implicated in interleukin-1 (Il1) signaling, in a murine model of extensive (85%) hepatectomy. We report that, although Myd88 is thoroughly essential for survival via regulation of NF-κB and TNF-α, deletion of RAGE significantly improved survival compared to wild-type, Myd88-null, or RAGE-null/Myd88-null mice. RAGE opposes Myd88 signaling at multiple levels: by suppression of p65 levels, thereby reducing activation of NF-κB and consequent production of cyclin D1, and by suppression of Il6-mediated phosphorylation of Stat3, thereby down-regulating Pim1 and suppressing the hyperplastic response. Further, RAGE-dependent suppression of glyoxalase1, a detoxification pathway for pre-AGEs, enhances AGE levels and suppresses Il6 action. We conclude that blockade of RAGE may rescue liver remnants from the multiple signals that preclude adaptive proliferation triggered primarily by Myd88 signaling pathways.

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Cell Proliferation
  • Glycation End Products, Advanced / metabolism
  • Hepatectomy
  • Hepatocytes / cytology
  • Hepatocytes / metabolism
  • Immunity, Innate
  • Liver Regeneration / genetics
  • Liver Regeneration / immunology
  • Liver Regeneration / physiology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myeloid Differentiation Factor 88 / deficiency
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / physiology*
  • NF-kappa B / metabolism
  • Proto-Oncogene Proteins c-pim-1 / genetics
  • Proto-Oncogene Proteins c-pim-1 / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptor for Advanced Glycation End Products
  • Receptors, Immunologic / deficiency
  • Receptors, Immunologic / genetics
  • Receptors, Immunologic / physiology*
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism
  • Up-Regulation

Substances

  • Glycation End Products, Advanced
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • RNA, Messenger
  • Receptor for Advanced Glycation End Products
  • Receptors, Immunologic
  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Pim1 protein, mouse
  • Proto-Oncogene Proteins c-pim-1