Endotoxin-induced lung alveolar cell injury causes brain cell damage

Abstract

Sepsis is the most common cause of acute respiratory distress syndrome, a severe lung inflammatory disorder with an elevated morbidity and mortality. Sepsis and acute respiratory distress syndrome involve the release of inflammatory mediators to the systemic circulation, propagating the cellular and molecular response and affecting distal organs, including the brain. Since it has been reported that sepsis and acute respiratory distress syndrome contribute to brain dysfunction, we investigated the brain-lung crosstalk using a combined experimental in vitro airway epithelial and brain cell injury model. Conditioned medium collected from an in vitro lipopolysaccharide-induced airway epithelial cell injury model using human A549 alveolar cells was subsequently added at increasing concentrations (no conditioned, 2%, 5%, 10%, 15%, 25%, and 50%) to a rat mixed brain cell culture containing both astrocytes and neurons. Samples from culture media and cells from mixed brain cultures were collected before treatment, and at 6 and 24 h for analysis. Conditioned medium at 15% significantly increased apoptosis in brain cell cultures 24 h after treatment, whereas 25% and 50% significantly increased both necrosis and apoptosis. Levels of brain damage markers S100 calcium binding protein B and neuron-specific enolase, interleukin-6, macrophage inflammatory protein-2, as well as matrix metalloproteinase-9 increased significantly after treating brain cells with !2% conditioned medium. Our findings demonstrated that human epithelial pulmonary cells stimulated with bacterial lipopolysaccharide release inflammatory mediators that are able to induce a translational clinically relevant and harmful response in brain cells. These results support a brain-lung crosstalk during sepsis and sepsis-induced acute respiratory distress syndrome.

Inhibition of endotoxin-induced airway epithelial cell injury by a novel family of pyrrol derivates

“…Second, we did not use primary alveolar epithelial cells; however, there is a plethora of published studies validating the use of human BEAS-2B and A549 cells as an acceptable model of epithelial cell injury and for studying the LPS-induced effects in the airway epithelium. [11][12][13][14][15][16]25,[28][29][30][31][32][33][34][35] Third, further studies are needed to elucidate whether there are other mechanisms by which the pyrrol compound DTA0118 elicits its anti-inflammatory and antiapoptotic activities. Fourth, TLR4, Ikβα, and β-actin were not adjusted for the cell number.…”

“…We chose A549 and BEAS-2B cell lines as representative human alveolar and bronchial epithelial cells because they have been implicated in the pathogenesis of sepsis-induced ARDS. [11][12][13][14][15][16] One of the most important determinants of lung severity is the magnitude of injury to the epithelial barrier. 2 Epithelial cells generate cytokines, chemokines, and antimicrobial peptides in response to inflammatory stimuli, 25,26 and airway epithelium controls lung inflammation and injury through NF-κB.…”

“…2 Epithelial cells generate cytokines, chemokines, and antimicrobial peptides in response to inflammatory stimuli, 25,26 and airway epithelium controls lung inflammation and injury through NF-κB. 27 Numerous experimental studies have used human A549 alveolar and BEAS-2B bronchial epithelial cell lines to examine the acute lung inflammatory response induced by LPS, as an acceptable, validated, and suitable in vitro airway epithelial injury model based on the initial steps of the development of sepsis and ARDS [11][12][13][14][15][16]25,[28][29][30] and continue being extensively used. [31][32][33][34][35] We selected E. coli LPS because it has been used in most endotoxin-induced lung injury models 36,37 and LPS is a key pathogen recognition molecule for sepsis 27 that induces apoptosis in lung cells.…”

“…Based on a well-established protocol of the National Cancer Institute of the United States, 9 we used a validated screening strategy to identify potential therapeutic molecules by examining the effects of a novel family of tri-and tetrasubstituted pyrrols, which were previously studied by our group. 10 In the present study, we report the marked anti-inflammatory and antiapoptotic properties of a compound termed by us as DTA0118 in a well-established in vitro LPSinduced airway epithelial cell injury model, [11][12][13][14][15][16] based on the initial steps of the development of sepsis and sepsis-induced ARDS, using human alveolar A549 and human bronchial BEAS-2B cells. We used rhein and emodin, two anthracenederived anthraquinones with proven activity against the effects of LPS, 17 as reference compounds.…”

Regulatory mechanism of NOV/CCN3 in the inflammation and apoptosis of lung epithelial alveolar cells upon lipopolysaccharide stimulation

“…Proteins involved in transcriptional regulation, such as nuclear factor (NF)-κB and transforming growth factor (TGF)-β, have been implicated in the development and progression of ALI and ARDS (17)(18)(19)(20)(21). Human A549 alveolar epithelial cells have been widely used as an epithelial cell injury model to examine lipopolysaccharide (LPS)-induced acute lung inflammatory response (22)(23)(24)(25)(26)(27)(28). The objective of this study was to reveal the potential role and underlying mechanism of CCN3 in lung dysfunction from the perspective of inflammation and apoptosis using siRNA-mediated transfection approach.…”