Contributions of TRPV1, endovanilloids, and endoplasmic reticulum stress in lung cell death in vitro and lung injury

Am J Physiol Lung Cell Mol Physiol. 2012 Jan 1;302(1):L111-9. doi: 10.1152/ajplung.00231.2011. Epub 2011 Sep 23.

Abstract

Endogenous agonists of transient receptor potential vanilloid-1 (TRPV1) (endovanilloids) are implicated as mediators of lung injury during inflammation. This study tested the hypothesis that endovanilloids produced following lipopolysaccharide (LPS) treatment activate TRPV1 and cause endoplasmic reticulum stress/GADD153 expression in lung cells, representing a mechanistic component of lung injury. The TRPV1 agonist nonivamide induced GADD153 expression and caused cytotoxicity in immortalized and primary human bronchial, bronchiolar/alveolar, and microvascular endothelial cells, proportional to TRPV1 mRNA expression. In CF-1 mice, Trpv1 mRNA was most abundant in the alveoli, and intratracheal nonivamide treatment promoted Gadd153 expression in the alveolar region. Treatment of CF-1 mice with LPS increased Gadd153 in the lung, lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, and lung wet-to-dry weight ratio. Cotreating mice with LPS and the TRPV1 antagonist LJO-328 reduced Gadd153 induction and LDH in BAL but did not inhibit increases in lung wet-to-dry ratio. In Trpv1(-/-) mice treated with LPS, Gadd153 induction and LDH in BAL were reduced relative to wild-type mice, and the wet-to-dry weight ratios of lungs from both wild-type and Trpv1(-/-) mice decreased. Organic extracts of blood collected from LPS-treated mice were more cytotoxic to TRPV1-overexpressing cells compared with BEAS-2B cells and extracts from control mice, however, most pure endovanilloids did not produce cytotoxicity in a characteristic TRPV1-dependent manner. Collectively, these data indicate a role for TRPV1, and endogenous TRPV1 agonists, in ER stress and cytotoxicity in lung cells but demonstrate that ER stress and cytotoxicity are not essential for pulmonary edema.

Publication types

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

MeSH terms

  • Animals
  • Bronchi / metabolism
  • Bronchoalveolar Lavage Fluid / chemistry
  • Capsaicin / analogs & derivatives
  • Capsaicin / pharmacology
  • Cell Death
  • Cell Line
  • Cell Line, Transformed
  • Cells, Cultured
  • Endoplasmic Reticulum Stress / genetics*
  • Humans
  • Inflammation / metabolism
  • L-Lactate Dehydrogenase / metabolism
  • Lipopolysaccharides / pharmacology
  • Lung Injury / physiopathology*
  • Lung* / cytology
  • Lung* / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pulmonary Alveoli / metabolism*
  • Pulmonary Edema / metabolism
  • TRPV Cation Channels / agonists*
  • TRPV Cation Channels / genetics
  • Transcription Factor CHOP / genetics
  • Transcription Factor CHOP / metabolism

Substances

  • Ddit3 protein, mouse
  • Lipopolysaccharides
  • TRPV Cation Channels
  • TRPV1 protein, mouse
  • Transcription Factor CHOP
  • L-Lactate Dehydrogenase
  • Capsaicin
  • nonivamide