Participation of Mammalian Target of Rapamycin Complex 1 in Toll-like Receptor 2- And 4-induced Neutrophil Activation and Acute Lung Injury

Am J Respir Cell Mol Biol. 2009 Aug;41(2):237-45. doi: 10.1165/rcmb.2008-0290OC. Epub 2009 Jan 8.

Abstract

mTOR complex 1 (mTORC1) plays a central role in cell growth and cellular responses to metabolic stress. Although mTORC1 has been shown to be activated after Toll-like receptor (TLR)-4 engagement, there is little information concerning the role that mTORC1 may play in modulating neutrophil function and neutrophil-dependent inflammatory events, such as acute lung injury. To examine these issues, we determined the effects of rapamycin-induced inhibition of mTORC1 on TLR2- and TLR4-induced neutrophil activation. mTORC1 was dose- and time-dependently activated in murine bone marrow neutrophils cultured with the TLR4 ligand, LPS, or the TLR2 ligand, Pam(3) Cys-Ser-(Lys)(4) (PAM). Incubation of PAM- or LPS-stimulated neutrophils with rapamycin inhibited expression of TNF-alpha and IL-6, but not IkappaB-alpha degradation or nuclear translocation of NF-kappaB. Exposure of PAM or LPS-stimulated neutrophils to rapamycin inhibited phosphorylation of serine 276 in the NF-kappaB p65 subunit, a phosphorylation event required for optimal transcriptional activity of NF-kappaB. Rapamycin pretreatment inhibited PAM- or LPS-induced mTORC1 activation in the lungs. Administration of rapamycin also decreased the severity of lung injury after intratracheal LPS or PAM administration, as determined by diminished neutrophil accumulation in the lungs, reduced interstitial pulmonary edema, and diminished levels of TNF-alpha and IL-6 in bronchoalveolar lavage fluid. These results indicate that mTORC1 activation is essential in TLR2- and TLR4-induced neutrophil activation, as well as in the development and severity of acute lung injury.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Lung Injury / immunology*
  • Animals
  • Carrier Proteins / metabolism
  • Cell Cycle Proteins
  • Cells, Cultured
  • Eukaryotic Initiation Factors
  • Immunosuppressive Agents / metabolism
  • Interleukin-6 / genetics
  • Interleukin-6 / immunology
  • Ligands
  • Male
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Mice, Inbred C57BL
  • Multiprotein Complexes
  • Neutrophil Activation / immunology*
  • Neutrophils / immunology*
  • Phosphoproteins / metabolism
  • Proteins
  • Ribosomal Protein S6 / metabolism
  • Signal Transduction / physiology
  • Sirolimus / metabolism
  • TOR Serine-Threonine Kinases
  • Toll-Like Receptor 2 / immunology*
  • Toll-Like Receptor 4 / immunology*
  • Transcription Factor RelA / genetics
  • Transcription Factor RelA / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / immunology

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • Eif4ebp1 protein, mouse
  • Eukaryotic Initiation Factors
  • Immunosuppressive Agents
  • Interleukin-6
  • Ligands
  • Multiprotein Complexes
  • Phosphoproteins
  • Proteins
  • Rela protein, mouse
  • Ribosomal Protein S6
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Transcription Factor RelA
  • Transcription Factors
  • Tumor Necrosis Factor-alpha
  • ribosomal protein S6, mouse
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1
  • Sirolimus