No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Abstract
We investigated the expression of plasminogen activator inhibitor-1 (PAI-1) in A549 cells under cyclic mechanical stretch using cytomechanics. A cell stretch loading device was used to simulate mechanical ventilation conditions towards the in vitro cultured A549 cells, with stress loads of 10% and 20% and frequency of 0.3 Hz for 4, 12, and 24 h. Polymerase chain reaction and western blotting were then performed to measure the expression of PAI-1mRNA and protein; annexin V/propidium iodide flow cytometry was performed to detect apoptosis; an enzyme linked immunosorbent assay was performed to detect the expression of interleukin-8 in the supernatant; and electron microscopy was performed to observe changes in cell morphology. The expression of PAI-1mRNA and protein, cell early apoptosis rate, and interleukin-8 expression in the supernatant in each 20% stretch subgroup were increased compared to the corresponding control group, and cell damage was more obvious by electron microscopy observation. Mechanical stretch may damage A549 cells and upregulate PAI-1 expression.
ResearchGate has not been able to resolve any citations for this publication.
Mechanical ventilation (MV) can cause ventilator-induced lung injury (VILI). The innate immune response mediates this iatrogenic inflammatory condition. The receptor for advanced glycation end products (RAGE) is a multiligand receptor that can amplify immune and inflammatory responses. We hypothesized that RAGE signaling contributes to the pro-inflammatory state induced by MV.
RAGE expression was analyzed in lung brush and lavage cells obtained from ventilated patients and lung tissue of ventilated mice. Healthy wild-type (WT) and RAGE knockout (KO) mice were ventilated with relatively low (approximately 7.5 ml/kg) or high (approximately 15 ml/kg) tidal volume. Positive end-expiratory pressure was set at 2 cm H2O during both MV strategies. Also, WT and RAGE KO mice with lipopolysaccharide (LPS)-induced lung injury were ventilated with the above described ventilation strategies. In separate experiments, the contribution of soluble RAGE, a RAGE isoform that may function as a decoy receptor, in ventilated RAGE KO mice was investigated. Lung wet-to-dry ratio, cell and neutrophil influx, cytokine and chemokine concentrations, total protein levels, soluble RAGE, and high-mobility group box 1 (HMGB1) presence in lung lavage fluid were analyzed.
MV was associated with increased RAGE mRNA levels in both human lung brush samples and lung tissue of healthy mice. In healthy high tidal volume-ventilated mice, RAGE deficiency limited inflammatory cell influx. Other VILI parameters were not affected. In our second set of experiments where we compared RAGE KO and WT mice in a 2-hit model, we observed higher pulmonary cytokine and chemokine levels in RAGE KO mice undergoing LPS/high tidal volume MV as compared to WT mice. Third, in WT mice undergoing the LPS/high tidal volume MV, we observed HMGB1 presence in lung lavage fluid. Moreover, MV increased levels of soluble RAGE in lung lavage fluid, with the highest levels found in LPS/high tidal volume-ventilated mice. Administration of soluble RAGE to LPS/high tidal volume-ventilated RAGE KO mice attenuated the production of inflammatory mediators.
RAGE was not a crucial contributor to the pro-inflammatory state induced by MV. However, the presence of sRAGE limited the production of pro-inflammatory mediators in our 2-hit model of LPS and high tidal volume MV.