Comparison of Alveolar Epithelial Markers of Lung Injury, sRAGE vs SPD, as Markers of Pulmonary and Non-Pulmonary Organ Dysfunction

Background The role of tumor necrosis factor (TNF)-α small interfering (si)RNA alveolar epithelial cell (AEC)-targeting nanoparticles in lung injury is unclear. Methods Sixty C57BL/6J mice with sepsis were divided into normal, control, sham, 25 mg/kg, 50 mg/kg, and 100 mg/kg siRNA AEC-targeting nanoparticles groups (n = 10 per group). The wet:dry lung weight ratio, and hematoxylin and eosin staining, western blotting, and enzyme-linked immunosorbent assays for inflammatory factors were conducted to compare differences among groups. Results The wet:dry ratio was significantly lower in control and sham groups than other groups. TNF-α siRNA AEC-targeting nanoparticles significantly reduced the number of eosinophils, with significantly lower numbers in the 50 mg/kg group than in 25 mg/kg and 100 mg/kg groups. The nanoparticles also significantly reduced the expression of TNF-α, B-cell lymphoma-2, caspase 3, interleukin (IL)-1β, and IL-6, with TNF-α expression being significantly lower in the 50 mg/kg group than in 25 mg/kg and 100 mg/kg groups. Conclusion TNF-α siRNA AEC-targeting nanoparticles appear to be effective at improving lung injury-related sepsis, and 50 mg/kg may be a preferred dose option for administration.

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Dexmedetomidine alleviates pulmonary edema through the epithelial sodium channel (ENaC) via the PI3K/Akt/Nedd4-2 pathway in LPS-induced acute lung injury

Immunologic Research ◽

10.1007/s12026-021-09176-6 ◽

2021 ◽

Author(s):

Yuanxu Jiang ◽

Mingzhu Xia ◽

Jing Xu ◽

Qiang Huang ◽

Zhongliang Dai ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Sodium Channel ◽

Pulmonary Edema ◽

Cell Injury ◽

A549 Cells ◽

Alveolar Epithelial ◽

Phosphorylated Akt ◽

Epithelial Sodium Channel Enac

AbstractDexmedetomidine (Dex), a highly selective α2-adrenergic receptor (α2AR) agonist, has an anti-inflammatory property and can alleviate pulmonary edema in lipopolysaccharide (LPS)-induced acute lung injury (ALI), but the mechanism is still unclear. In this study, we attempted to investigate the effect of Dex on alveolar epithelial sodium channel (ENaC) in the modulation of alveolar fluid clearance (AFC) and the underlying mechanism. Lipopolysaccharide (LPS) was used to induce acute lung injury (ALI) in rats and alveolar epithelial cell injury in A549 cells. In vivo, Dex markedly reduced pulmonary edema induced by LPS through promoting AFC, prevented LPS-induced downregulation of α-, β-, and γ-ENaC expression, attenuated inflammatory cell infiltration in lung tissue, reduced the concentrations of TNF-α, IL-1β, and IL-6, and increased concentrations of IL-10 in bronchoalveolar lavage fluid (BALF). In A549 cells stimulated with LPS, Dex attenuated LPS-mediated cell injury and the downregulation of α-, β-, and γ-ENaC expression. However, all of these effects were blocked by the PI3K inhibitor LY294002, suggesting that the protective role of Dex is PI3K-dependent. Additionally, Dex increased the expression of phosphorylated Akt and reduced the expression of Nedd4-2, while LY294002 reversed the effect of Dex in vivo and in vitro. Furthermore, insulin-like growth factor (IGF)-1, a PI3K agonists, promoted the expression of phosphorylated Akt and reduced the expression of Nedd4-2 in LPS-stimulated A549 cells, indicating that Dex worked through PI3K, and Akt and Nedd4-2 are downstream of PI3K. In conclusion, Dex alleviates pulmonary edema by suppressing inflammatory response in LPS-induced ALI, and the mechanism is partly related to the upregulation of ENaC expression via the PI3K/Akt/Nedd4-2 signaling pathway.

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K2P2.1 (TREK-1) potassium channel activation protects against hyperoxia-induced lung injury

Scientific Reports ◽

10.1038/s41598-020-78886-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tatiana Zyrianova ◽

Benjamin Lopez ◽

Riccardo Olcese ◽

John Belperio ◽

Christopher M. Waters ◽

...

Keyword(s):

Lung Injury ◽

Lung Compliance ◽

Alveolar Epithelial Cells ◽

Pharmacological Intervention ◽

Alveolar Epithelial ◽

Protein Levels ◽

Cell Counts ◽

Novel Approach ◽

Intracellular Ca ◽

Cell Depolarization

AbstractNo targeted therapies exist to counteract Hyperoxia (HO)-induced Acute Lung Injury (HALI). We previously found that HO downregulates alveolar K2P2.1 (TREK-1) K+ channels, which results in worsening lung injury. This decrease in TREK-1 levels leaves a subset of channels amendable to pharmacological intervention. Therefore, we hypothesized that TREK-1 activation protects against HALI. We treated HO-exposed mice and primary alveolar epithelial cells (AECs) with the novel TREK-1 activators ML335 and BL1249, and quantified physiological, histological, and biochemical lung injury markers. We determined the effects of these drugs on epithelial TREK-1 currents, plasma membrane potential (Em), and intracellular Ca2+ (iCa) concentrations using fluorometric assays, and blocked voltage-gated Ca2+ channels (CaV) as a downstream mechanism of cytokine secretion. Once-daily, intra-tracheal injections of HO-exposed mice with ML335 or BL1249 improved lung compliance, histological lung injury scores, broncho-alveolar lavage protein levels and cell counts, and IL-6 and IP-10 concentrations. TREK-1 activation also decreased IL-6, IP-10, and CCL-2 secretion from primary AECs. Mechanistically, ML335 and BL1249 induced TREK-1 currents in AECs, counteracted HO-induced cell depolarization, and lowered iCa2+ concentrations. In addition, CCL-2 secretion was decreased after L-type CaV inhibition. Therefore, Em stabilization with TREK-1 activators may represent a novel approach to counteract HALI.

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H2O2 inhibits alveolar epithelial wound repair in vitro by induction of apoptosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00177.2003 ◽

2004 ◽

Vol 287 (2) ◽

pp. L448-L453 ◽

Cited By ~ 55

Author(s):

Thomas Geiser ◽

Masanobu Ishigaki ◽

Coretta van Leer ◽

Michael A. Matthay ◽

V. Courtney Broaddus

Keyword(s):

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Cell Viability ◽

Wound Repair ◽

Wound Edge ◽

Alveolar Epithelial ◽

Induction Of Apoptosis

Reactive oxygen species (ROS) are released into the alveolar space and contribute to alveolar epithelial damage in patients with acute lung injury. However, the role of ROS in alveolar repair is not known. We studied the effect of ROS in our in vitro wound healing model using either human A549 alveolar epithelial cells or primary distal lung epithelial cells. We found that H2O2 inhibited alveolar epithelial repair in a concentration-dependent manner. At similar concentrations, H2O2 also induced apoptosis, an effect seen particularly at the edge of the wound, leading us to hypothesize that apoptosis contributes to H2O2-induced inhibition of wound repair. To learn the role of apoptosis, we blocked caspases with the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp (zVAD). In the presence of H2O2, zVAD inhibited apoptosis, particularly at the wound edge and, most importantly, maintained alveolar epithelial wound repair. In H2O2-exposed cells, zVAD also maintained cell viability as judged by improved cell spreading and/or migration at the wound edge and by a more normal mitochondrial potential difference compared with cells not treated with zVAD. In conclusion, H2O2 inhibits alveolar epithelial wound repair in large part by induction of apoptosis. Inhibition of apoptosis can maintain wound repair and cell viability in the face of ROS. Inhibiting apoptosis may be a promising new approach to improve repair of the alveolar epithelium in patients with acute lung injury.

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Claudin-4 augments alveolar epithelial barrier function and is induced in acute lung injury

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00043.2009 ◽

2009 ◽

Vol 297 (2) ◽

pp. L219-L227 ◽

Cited By ~ 99

Author(s):

Charlie Wray ◽

Ying Mao ◽

Jue Pan ◽

Anita Chandrasena ◽

Frank Piasta ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Tight Junction ◽

Pulmonary Edema ◽

Barrier Function ◽

Mapk Pathway ◽

Paracellular Transport ◽

Epithelial Barrier ◽

Altered Expression ◽

Alveolar Epithelial

Intact alveolar barrier function is associated with better outcomes in acute lung injury patients; however, the regulation of alveolar epithelial paracellular transport during lung injury has not been extensively investigated. This study was undertaken to determine whether changes in tight junction claudin expression affect alveolar epithelial barrier properties and to determine the mechanisms of altered expression. In anesthetized mice exposed to ventilator-induced lung injury, claudin-4 was specifically induced among tight junction structural proteins. Real-time PCR showed an eightfold increase in claudin-4 expression in the lung injury model. To examine the role of this protein in barrier regulation, claudin-4 function was inhibited with small interfering RNA (siRNA) and a blocking peptide derived from the binding domain of Clostridium perfringens enterotoxin (CPEBD). Inhibition of claudin-4 decreased transepithelial electrical resistance but did not alter macromolecule permeability in primary rat and human epithelial cells. In mice, CPEBD decreased air space fluid clearance >33% and resulted in pulmonary edema during moderate tidal volume ventilation that did not induce edema in control peptide-treated mice. In vitro phorbol ester induced a ninefold increase in claudin-4 expression that was dependent on PKC activation and the JNK MAPK pathway. These data establish that changes in alveolar epithelial claudin expression influence paracellular transport, alveolar fluid clearance rates, and susceptibility to pulmonary edema. We hypothesize that increased claudin-4 expression early in acute lung injury represents a mechanism to limit pulmonary edema and that the regulation of alveolar epithelial claudin expression may be a novel target for acute lung injury therapy.

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Effects of Antibiotic Therapy on Pseudomonas aeruginosa-Induced Lung Injury in a Rat Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.43.10.2389 ◽

1999 ◽

Vol 43 (10) ◽

pp. 2389-2394 ◽

Cited By ~ 7

Author(s):

Erika J. Ernst ◽

Satoru Hashimoto ◽

Joseph Guglielmo ◽

Teiji Sawa ◽

Jean-Francois Pittet ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Acute Lung Injury ◽

Lung Injury ◽

Rat Model ◽

In Vivo Model ◽

Antibiotic Administration ◽

Lung Water ◽

Alveolar Epithelial ◽

The Right

ABSTRACT The effect of antibiotics on the acute lung injury induced by virulent Pseudomonas aeruginosa PA103 was quantitatively analyzed in a rat model. Lung injury was induced by the instillation of PA103 directly into the right lower lobes of the lungs of anesthetized rats. The alveolar epithelial injury, extravascular lung water, and total plasma equivalents were measured as separate, independent parameters of acute lung injury. Four hours after the instillation of PA103, all the parameters were increased linearly depending on the dose of P. aeruginosa. Next, we examined the effects of intravenously administered antibiotics on the parameters of acute lung injury in d-galactosamine-sensitized rats. One hour after the rats received 107 CFU of PA103, an intravenous bolus injection of aztreonam (60 mg/kg) or imipenem-cilastatin (30 mg/kg) was administered. Despite an MIC indicating resistance, imipenem-cilastatin improved all the measurements of lung injury; in contrast, aztreonam, which had an MIC indicating sensitivity, did not improve any of the lung injury parameters. The antibiotics did not generate different quantities of plasma endotoxin; therefore, endotoxin did not appear to explain the differences in lung injury. This in vivo model is useful to quantitatively compare the efficacies of parenteral antibiotic administration on Pseudomonas airspace infections.

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