Inhibition of protein kinase C delta attenuates allergic airway inflammation through suppression of PI3K/Akt/mTOR/HIF-1 alpha/VEGF pathway

PLoS One. 2013 Nov 29;8(11):e81773. doi: 10.1371/journal.pone.0081773. eCollection 2013.

Abstract

Vascular endothelial growth factor (VEGF) is supposed to contribute to the pathogenesis of allergic airway disease. VEGF expression is regulated by a variety of stimuli such as nitric oxide, growth factors, and hypoxia-inducible factor-1 alpha (HIF-1α). Recently, inhibition of the mammalian target of rapamycin (mTOR) has been shown to alleviate cardinal asthmatic features, including airway hyperresponsiveness, eosinophilic inflammation, and increased vascular permeability in asthma models. Based on these observations, we have investigated whether mTOR is associated with HIF-1α-mediated VEGF expression in allergic asthma. In studies with the mTOR inhibitor rapamycin, we have elucidated the stimulatory role of a mTOR-HIF-1α-VEGF axis in allergic response. Next, the mechanisms by which mTOR is activated to modulate this response have been evaluated. mTOR is known to be regulated by phosphoinositide 3-kinase (PI3K)/Akt or protein kinase C-delta (PKC δ) in various cell types. Consistent with these, our results have revealed that suppression of PKC δ by rottlerin leads to the inhibition of PI3K/Akt activity and the subsequent blockade of a mTOR-HIF-1α-VEGF module, thereby attenuating typical asthmatic attack in a murine model. Thus, the present data indicate that PKC δ is necessary for the modulation of the PI3K/Akt/mTOR signaling cascade, resulting in a tight regulation of HIF-1α activity and VEGF expression. In conclusion, PKC δ may represent a valuable target for innovative therapeutic treatment of allergic airway disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Asthma / complications*
  • Asthma / drug therapy*
  • Asthma / metabolism
  • Asthma / pathology
  • Bronchoalveolar Lavage Fluid
  • Cell Line
  • Cytokines / metabolism
  • Female
  • Gene Expression Regulation / drug effects
  • Humans
  • Hypersensitivity / complications*
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Lung / drug effects
  • Lung / immunology
  • Lung / metabolism
  • Lung / pathology
  • Mice
  • Ovalbumin / adverse effects
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoproteins / metabolism
  • Protein Kinase C-delta / antagonists & inhibitors*
  • Protein Kinase C-delta / deficiency
  • Protein Kinase C-delta / genetics
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinase Inhibitors / therapeutic use
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Signal Transduction / drug effects*
  • TOR Serine-Threonine Kinases / metabolism
  • Th2 Cells / drug effects
  • Th2 Cells / metabolism
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Cytokines
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Phosphoproteins
  • Protein Kinase Inhibitors
  • RNA, Small Interfering
  • Vascular Endothelial Growth Factor A
  • Ovalbumin
  • Phosphatidylinositol 3-Kinases
  • TOR Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Protein Kinase C-delta

Grant support

This paper was supported by the National Natural Science Foundation of China (81060003, 81260665, and 81160176; http://www.nsfc.gov.cn/Portal0/default152.htm) and by research funds of Chonbuk National University in 2012. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.