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Lack of phosphoinositide 3-kinase-gamma attenuates ventilator-induced lung injury

Vincenzo Lionetti1, Alberto Lisi, Enrico Patrucco

  • 1Dipartimento di Anestesiologia e Rianimazione, Ospedale S. Giovanni Battista-Molinette, Università di Torino, Torino, Italy.

Critical Care Medicine
|December 24, 2005
PubMed
Abstract

Insights

Silencing phosphoinositide-3-kinase gamma (PI3Kgamma) in mice attenuated ventilator-induced lung injury. This protective effect was linked to increased pulmonary apoptosis rather than reduced inflammation.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pulmonary Medicine

Background:

  • G protein-coupled receptors influence inflammatory responses and cell survival in ventilator-induced lung injury (VILI).
  • Phosphoinositide-3-kinase gamma (PI3Kgamma) is a key regulator of inflammation and cell survival pathways, including protein kinase B (Akt) and extracellular signal regulated kinases 1/2 (ERK1/2).

Purpose of the Study:

  • To investigate the specific role of PI3Kgamma in the development of ventilator-induced lung injury.
  • To determine whether PI3Kgamma modulates inflammatory responses or cell survival mechanisms during VILI.

Main Methods:

  • A prospective, randomized experimental study was conducted in a university animal research laboratory.
  • Wild-type, PI3Kgamma knockout, and kinase-dead PI3Kgamma mice were subjected to three ventilatory strategies (no stretch, low stretch, high stretch) in an isolated lung injury model.
  • Lung compliance, histological changes, inflammatory markers, apoptosis, and signaling pathway activation (Akt, ERK1/2) were assessed.

Main Results:

  • High stretch ventilation exacerbated lung injury, with reduced compliance and increased hyaline membrane formation and epithelial detachment in PI3Kgamma knockout mice compared to wild-type.
  • While inflammatory cytokine levels did not differ, apoptotic indices and caspase-3 activity were significantly higher in PI3Kgamma knockout mice.
  • PI3Kgamma knockout mice exhibited apoptotic changes in alveolar cells, whereas wild-type mice showed necrosis under high stretch. Phosphorylation of Akt and ERK1/2 was more pronounced in PI3Kgamma knockout mice.

Conclusions:

  • Silencing PI3Kgamma attenuates the functional and morphological damage associated with ventilator-induced lung injury.
  • This protective effect appears to be mediated by enhanced pulmonary apoptosis, independent of direct inhibition of cytokine release.
  • PI3Kgamma plays a critical role in VILI pathogenesis, influencing cell fate through apoptosis and necrosis pathways.

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