Autophagy induced by DAMPs facilitates the inflammation response in lungs undergoing ischemia-reperfusion injury through promoting TRAF6 ubiquitination

Cell Death Differ. 2017 Apr;24(4):683-693. doi: 10.1038/cdd.2017.1. Epub 2017 Feb 3.

Abstract

Lung ischemia-reperfusion (I/R) injury remains one of the most common complications after various cardiopulmonary surgeries. The inflammation response triggered by the released damage-associated molecular patterns (DAMPs) aggravates lung tissue damage. However, little is known about the role of autophagy in the pathogenesis of lung I/R injury. Here, we report that a variety of inflammation-related and autophagy-associated genes are rapidly upregulated, which facilitate the inflammation response in a minipig lung I/R injury model. Left lung I/R injury triggered inflammatory cytokine production and activated the autophagy flux as evidenced in crude lung tissues and alveolar macrophages. This was associated with the release of DAMPs, such as high mobility group protein B1 (HMGB1) and heat shock protein 60 (HSP60). Indeed, treatment with recombinant HMGB1 or HSP60 induced autophagy in alveolar macrophages, whereas autophagy inhibition by knockdown of ATG7 or BECN1 markedly reduced DAMP-triggered production of inflammatory cytokines including IL-1β, TNF and IL12 in alveolar macrophages. This appeared to be because of decreased activation of MAPK and NF-κB signaling. Furthermore, knockdown of ATG7 or BECN1 inhibited Lys63 (K63)-linked ubiquitination of TNF receptor-associated factor 6 (TRAF6) in DAMP-treated alveolar macrophages. Consistently, treatment with 3-MA inhibited K63-linked ubiquitination of TRAF6 in I/R-injured lung tissues in vivo. Collectively, these results indicate that autophagy triggered by DAMPs during lung I/R injury amplifies the inflammatory response through enhancing K63-linked ubiquitination of TRAF6 and activation of the downstream MAPK and NF-κB signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Animals
  • Autophagy* / drug effects
  • Beclin-1 / antagonists & inhibitors
  • Beclin-1 / genetics
  • Beclin-1 / metabolism
  • Bronchoalveolar Lavage Fluid / chemistry
  • Bronchoalveolar Lavage Fluid / cytology
  • Cells, Cultured
  • Chaperonin 60 / genetics
  • Chaperonin 60 / metabolism
  • HMGB1 Protein / genetics
  • HMGB1 Protein / metabolism
  • Inflammation
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • Lung / metabolism
  • Lung / pathology*
  • Macrophages, Alveolar / cytology
  • Macrophages, Alveolar / drug effects
  • Macrophages, Alveolar / metabolism
  • Reperfusion Injury / metabolism
  • Reperfusion Injury / pathology*
  • Signal Transduction / drug effects
  • Swine
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism
  • Ubiquitination / drug effects

Substances

  • Beclin-1
  • Chaperonin 60
  • HMGB1 Protein
  • Interleukin-6
  • TNF Receptor-Associated Factor 6
  • Tumor Necrosis Factor-alpha
  • 3-methyladenine
  • Adenine