Activation of mas restores hyperoxia-induced loss of lung epithelial barrier function through inhibition of apoptosis

Abstract

Background: Neonatal therapy with a high concentration of oxygen (hyperoxia) is a known cause of bronchopulmonary dysplasia (BPD). BPD is characterized by increased pulmonary permeability and diffuse infiltration of various inflammatory cells. Disruption of the epithelial barrier may lead to altered pulmonary permeability and airways fluid accumulation. Mas receptor is a component of the renin angiotensin system and is the receptor for the protective endogenous peptide angiotensin 1-7. The activation of the Mas receptor was previously shown to have protective pulmonary responses. However, the effect of Mas receptor activation on epithelial barrier integrity has not been tested. Objective: To determine the effects of hyperoxia with or without Mas receptor activation on epithelial cell barrier integrity. Design/Methods: Human epithelial cell line A549 was cultured on transwell polycarbonate porous membrane to confluence and treated with 95% oxygen (hyperoxia) for 72 hours with or without the Mas receptor agonist (AVE0991), or the apoptotic inhibitors Z-VAD-FMK or aurintricarboxylic acid. The cells were then challenged with Rhodamine labeled bovine serum albumin (Rh-BSA) on one side of the membrane. Fluorescent quantitation of Rh-BSA (albumin flux) was performed on the media in the other side of the membrane 3 hours later and was compared with 21% oxygen (Normoxia) control group. A549 cells were also cultured with or without AVE0991 in hyperoxia or normoxia and used for nuclear fragmentation apoptosis assay using propidium iodide staining. Results: Hyperoxia induced an increase in albumin flux that was significantly prevented by AVE0991 treatment and by the apoptosis inhibitors. AVE0991 also significantly decreased the hyperoxia-induced nuclear fragmentation. Conclusion: These results suggest that hyperoxia causes a disruption in the epithelial barrier integrity, and that this disruption is inhibited by the Mas receptor agonist AVE0991 through inhibition of epithelial apoptosis. These results reveal a novel potential drug for BPD and pulmonary edema treatment.

Alpha-1 Antitrypsin Limits Neutrophil Extracellular Trap Disruption of Airway Epithelial Barrier Function

“…Airway epithelia have been described as relatively resistant to apoptosis, which when it occurs, disrupts barrier function (59,60). Multicaspase activation is suggested to be caused by NETs in an alveolar adenocarcinoma cell line, whereas we demonstrate that NETs induce apoptosis in primary human bronchial epithelia (61).…”

“…Airway epithelia are relatively resistant to apoptosis, but when it occurs, barrier function is disrupted leading to increased pulmonary injury (Abdul-Hafez, Mohamed & Uhal, 2019, White, 2011). NETs were previously demonstrated to cause multicaspase activation in an alveolar adenocarcinoma cell line and, herein, we demonstrate that NETs induce apoptosis in primary human bronchial epithelia (Saffarzadeh et al, 2012).…”

Claudin-18 expression under hyperoxia in neonatal lungs of bronchopulmonary dysplasia model rats

“…In various animal models of lung injury, decreased expression of claudin-18 has been considered a sign of lung barrier damage ( 28 – 31 ). Especially in a model of hyperoxia-induced BPD, claudin-18 has been shown to possibly be involved in early pulmonary edema development and late alveolar development ( 32 ).…”

Claudin-18 expression under hypoxia in neonatel lungs of brochopulmonary dysplasia model rats

“…In various animal models of lung injury, decreased claudin-18 expression has been considered a sign of lung barrier damage (Lee et al 2020;M et al 2020;Reynolds et al 2018;Weber et al 2019). Especially in a hyperoxia-induced BPD model, claudin-18 may be involved in early pulmonary edema development and late alveolar development (Abdul-Hafez et al 2019). La Femina et al (2014 studied the role of claudin-18 in lung development and barrier function in a claudin-18 (exon 2 and 3) knock-out (KO) mouse model.…”