DEFORMATION-INDUCED PLASMA MEMBRANE STRESS FAILURE

We are testing the hypothesis that changes in alveolar basement membrane area that accompany large volume mechanical ventilation, impart potentially injurious stresses on the alveolar epithelial and capillary endothelial cells that adhere to it. As a consequence, these cells are intermittently wounded. While deformation induced plasma membrane stress failure (wounding) need not result in cell death (plasma membrane breaks usually reseal), it does cause upregulation of genes involved in pro-inflammatory signaling.

Primary alveolar epithelial cells or transformed cell lines are cultured on matrix bonded malleable membranes and stretched at different rates and amplitudes. Resulting changes in membrane surface area and cell shape can be defined using Laser Confocal Microscopy. Matrix deformation induced wounding of plasma membranes is associated with the cytoplasmic entry and retention of large fluorescent molecules such as FITC Dextran (green) or Propridium Iodide (red).

Alveolar cell wounding can also be demonstrated in intact lungs. To the right is a Laser Confocal Image of a rat lung that had been mechanically ventilated at injurious settings while being perfused with a Propridium Iodide containing solution. Nuclei of injured cells emit red fluorescence.

Selected Publications

1. Vlahakis NE, Schroeder MA, Limper AH, Hubmayr RD. Stretch induces cytokine release by alveolar epithelial cells in vitro. Am J Physiol (Lung Cell Molec Physiol) 1999; 277:L167-L173
2. Vlahakis NE, Hubmayr RD. Plasma membrane stress failure in alveolar epithelial cells (invited mini review). J Appl Physiol 2000; 89:2490-2496
3. Stroetz RW, Vlahakis NE, Walters BJ, Schroeder MA, Hubmayr RD. Validation of a new live cell strain system: Characterization of plasma membrane stress failure. J Appl Physiol 90: 2361-2370, 2001
4. Gajic O, Lee J, Doerr CH, Berrios JC, Myers JL, Hubmayr RD. Ventilator-induced cell wounding and repair in the intact lung. Am. J. Respir. Crit. Care Med. 167: 1057-1063, 2003
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5. Vlahakis NE, Hubmayr RD. Response of alveolar cells to mechanical stress. Current Opinion in Critical Care, 2003; 9:2-8