Dataset Information

Impact of low and high tidal volumes on the rat alveolar epithelial type II cell proteome.

ABSTRACT:

Rationale

Mechanical ventilation with high tidal volumes leads to increased permeability, generation of inflammatory mediators, and damage to alveolar epithelial cells (ATII).

Objectives

To identify changes in the ATII proteome after two different ventilation strategies in rats.

Methods

Rats (n = 6) were ventilated for 5 hours with high- and low tidal volumes (VTs) (high VT: 20 ml/kg; low VT: 6 ml/kg). Pooled nonventilated rats served as control animals. ATII cells were isolated and lysed, and proteins were tryptically cleaved into peptides. Cellular protein content was evaluated by peptide labeling of the ventilated groups with (18)O. Samples were fractionated by cation exchange chromatography and identified using electrospray tandem mass spectrometry. Proteins identified by 15 or more peptides were statistically compared using t tests corrected for the false discovery rate.

Measurements and main results

High Vt resulted in a significant increase in airspace neutrophils without an increase in extravascular lung water. Compared with low-VT samples, high-VT samples showed a 32% decrease in the inositol 1,4,5-trisphosphate 3 receptor (p < 0.01), a 34% decrease in Na(+), K(+)-ATPase (p < 0.01), and a significantly decreased content in ATP synthase chains. Even low-VT samples displayed significant changes, including a 66% decrease in heat shock protein 90-beta (p < 0.01) and a 67% increase in mitochondrial pyruvate carboxylase (p < 0.01). Significant differences were found in membrane, acute phase, structural, and mitochondrial proteins.

Conclusions

After short-term exposure to high-VT ventilation, significant reductions in membrane receptors, ion channel proteins, enzymes of the mitochondrial energy system, and structural proteins in ATII cells were present. The data supports the two-hit concept that an unfavorable ventilatory strategy may make the lung more vulnerable to an additional insult.

SUBMITTER: Hirsch J

PROVIDER: S-EPMC1899270 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature

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Publications

Impact of low and high tidal volumes on the rat alveolar epithelial type II cell proteome.

Hirsch Jan J Hansen Kirk C KC Sapru Anil A Frank James A JA Chalkley Robert J RJ Fang Xiaohui X Trinidad Jonathan C JC Baker Peter P Burlingame Alma L AL Matthay Michael A MA

American journal of respiratory and critical care medicine 20070315 10

<h4>Rationale</h4>Mechanical ventilation with high tidal volumes leads to increased permeability, generation of inflammatory mediators, and damage to alveolar epithelial cells (ATII).<h4>Objectives</h4>To identify changes in the ATII proteome after two different ventilation strategies in rats.<h4>Methods</h4>Rats (n = 6) were ventilated for 5 hours with high- and low tidal volumes (VTs) (high VT: 20 ml/kg; low VT: 6 ml/kg). Pooled nonventilated rats served as control animals. ATII cells were iso ...[more]

PMID: 17363773

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Project description:ObjectiveHepatic ischemia-reperfusion can be associated with acute lung injury. Alveolar epithelial type II cells (ATII) play an important role in maintaining lung homeostasis in acute lung injury.DesignTo study potentially new mechanisms of hepatic ischemia-reperfusion-induced lung injury, we examined how liver ischemia-reperfusion altered the proteome of ATII.SettingLaboratory investigation.SubjectsSpontaneously breathing male Zucker rats.InterventionsRats were anesthetized with isoflurane. The vascular supply to the left and medial lobe of the liver was clamped for 75 mins and then reperfused. Sham-operated rats were used as controls. After 8 hrs, rats were killed.Measurements and main resultsBronchoalveolar lavage and differential cell counts were performed, and tumor necrosis factor-alpha and cytokine-induced neutrophil chemotactic factor-1 in plasma were determined by enzyme-linked immunosorbent assay. ATII were isolated, lysed, tryptically digested, and labeled using isobaric tags (iTRAQ). The samples were fractionated by cation exchange chromatography, separated by high-performance liquid-chromatography, and identified using electrospray tandem mass spectrometry. Spectra were interrogated and quantified using ProteinProspector. Quantitative proteomics provided quantitative data for 94 and 97 proteins in the two groups. Significant changes in ATII protein content included 30% to 40% increases in adenosine triphosphate synthases, adenosine triphosphate/adenosine diphosphate translocase, and catalase (all p < .001). Following liver ischemia-reperfusion, there was also a significant increase in the percentage of neutrophils in bronchoalveolar lavage (48% +/- 26%) compared with sham-operated controls (5% +/- 3%) (p < .01), and plasma tumor necrosis factor-alpha levels were also significantly increased.ConclusionsThe proteins identified by quantitative proteomics indicated significant changes in moderators of cell metabolism and host defense in ATII. These findings provide new insights into possible mechanisms responsible for hepatic ischemia-reperfusion-related acute lung injury and suggest that ATII cells in the lung sense and respond to hepatic injury.

Project description:Ventilator-induced lung injury (VILI) impacts clinical outcomes in acute respiratory distress syndrome (ARDS), which is characterized by neutrophil-mediated inflammation and loss of alveolar barrier function. Recent epidemiological studies suggest that smoking may be a risk factor for the development of ARDS. Because alveolar type II cells are central to maintaining the alveolar epithelial barrier during oxidative stress, mediated in part by neutrophilic inflammation and mechanical ventilation, we hypothesized that exposure to cigarette smoke and mechanical strain have interactive effects leading to the activation of and damage to alveolar type II cells.To determine if cigarette smoke increases susceptibility to VILI in vivo, a clinically relevant rat model was established. Rats were exposed to three research cigarettes per day for two weeks. After this period, some rats were mechanically ventilated for 4 hours. Bronchoalveolar lavage (BAL) and differential cell count was done and alveolar type II cells were isolated. Proteomic analysis was performed on the isolated alveolar type II cells to discover alterations in cellular pathways at the protein level that might contribute to injury. Effects on levels of proteins in pathways associated with innate immunity, oxidative stress and apoptosis were evaluated in alveolar type II cell lysates by enzyme-linked immunosorbent assay. Statistical comparisons were performed by t-tests, and the results were corrected for multiple comparisons using the false discovery rate.Tobacco smoke exposure increased airspace neutrophil influx in response to mechanical ventilation. The combined exposure to cigarette smoke and mechanical ventilation significantly increased BAL neutrophil count and protein content. Neutrophils were significantly higher after smoke exposure and ventilation than after ventilation alone. DNA fragments were significantly elevated in alveolar type II cells. Smoke exposure did not significantly alter other protein-level markers of cell activation, including Toll-like receptor 4; caspases 3, 8 and 9; and heat shock protein 70.Cigarette smoke exposure may impact ventilator-associated alveolar epithelial injury by augmenting neutrophil influx. We found that cigarette smoke had less effect on other pathways previously associated with VILI, including innate immunity, oxidative stress and apoptosis.

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Dataset Information

Impact of low and high tidal volumes on the rat alveolar epithelial type II cell proteome.

Rationale

Objectives

Methods

Measurements and main results

Conclusions

Publications

Impact of low and high tidal volumes on the rat alveolar epithelial type II cell proteome.

Similar Datasets

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