Phospholipase C-ε Signaling Mediates Endothelial Cell Inflammation and Barrier Disruption in Acute Lung Injury

Am J Physiol Lung Cell Mol Physiol. 2016 Aug 1;311(2):L517-24. doi: 10.1152/ajplung.00069.2016. Epub 2016 Jul 1.

Abstract

Phospholipase C-ε (PLC-ε) is a unique PLC isoform that can be regulated by multiple signaling inputs from both Ras family GTPases and heterotrimeric G proteins and has primary sites of expression in the heart and lung. Whereas the role of PLC-ε in cardiac function and pathology has been documented, its relevance in acute lung injury (ALI) is unclear. We used PLC-ε(-/-) mice to address the role of PLC-ε in regulating lung vascular inflammation and injury in an aerosolized bacterial LPS inhalation mouse model of ALI. PLC-ε(-/-) mice showed a marked decrease in LPS-induced proinflammatory mediators (ICAM-1, VCAM-1, TNF-α, IL-1β, IL-6, macrophage inflammatory protein 2, keratinocyte-derived cytokine, monocyte chemoattractant protein 1, and granulocyte-macrophage colony-stimulating factor), lung neutrophil infiltration and microvascular leakage, and loss of VE-cadherin compared with PLC-ε(+/+) mice. These data identify PLC-ε as a critical determinant of proinflammatory and leaky phenotype of the lung. To test the possibility that PLC-ε activity in endothelial cells (EC) could contribute to ALI, we determined its role in EC inflammation and barrier disruption. RNAi knockdown of PLC-ε inhibited NF-κB activity in response to diverse proinflammatory stimuli, thrombin, LPS, TNF-α, and the nonreceptor agonist phorbol 13-myristate 12-acetate (phorbol esters) in EC. Depletion of PLC-ε also inhibited thrombin-induced expression of NF-κB target gene, VCAM-1. Importantly, PLC-ε knockdown also protected against thrombin-induced EC barrier disruption by inhibiting the loss of VE-cadherin at adherens junctions and formation of actin stress fibers. These data identify PLC-ε as a novel regulator of EC inflammation and permeability and show a hitherto unknown role of PLC-ε in the pathogenesis of ALI.

Keywords: adhesion molecules; endothelial cells; lung inflammation; signal transduction; transcription factors.

Publication types

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

MeSH terms

  • Acute Lung Injury / enzymology*
  • Acute Lung Injury / immunology
  • Acute Lung Injury / pathology
  • Animals
  • Antigens, CD / metabolism
  • Cadherins / metabolism
  • Capillary Permeability
  • Cells, Cultured
  • Endothelium, Vascular / enzymology
  • Endothelium, Vascular / pathology
  • Humans
  • Lung / blood supply
  • Lung / pathology
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NF-kappa B / metabolism
  • Phosphoinositide Phospholipase C / physiology*
  • Signal Transduction
  • Stress Fibers / metabolism
  • Vasculitis / enzymology

Substances

  • Antigens, CD
  • Cadherins
  • NF-kappa B
  • cadherin 5
  • Phosphoinositide Phospholipase C
  • phospholipase C epsilon