DUOX1-mediated hydrogen peroxide release regulates sodium transport in H441 bronchiolar epithelial cells.

Aim: Dexamethasone has been shown to induce the formation of epithelial domes by bronchiolar H441 cells. It stimulates the expression of both amiloride inhibitable epithelial sodium channels (ENaC) and dual oxidase-1 (DUOX1). We therefore ask the question whether DUOX1 expression and production of submillimolar amounts of H O is instrumental for the sodium channel upregulation observed in H441 cells.

Characterization of three commercial ELISA kits for detection of BOHV-1 gE specific antibodies in serum and milk samples and applicability of bulk milk for determination of herd status.

Vaccination of animals with gE-deleted vaccine strains (gE- marker vaccines) and differential detection of vaccinated vs infected animals with antibody ELISA targeting the gE or the gB proteins have been proved to be useful tools in programs for control and eradication of the bovine herpesvirus 1 (BoHV-1) responsible for infectious bovine rhinotracheitis (IBR), a major pathogen of cattle. The diagnostic sensitivity (DSe) and specificity (DSp) of three commercial gE ELISA kits from IDEXX, IDVet and CIV-HIPRA were compared for serum and milk matrices. Limiting the analysis to 198 individual with concordant ELISA results in serum (91 naïve, 37 vaccinated and 70 infected) the DSe of gE kits was estimated to 0,97 for IDEXX, 0,93 for CIV-HIPRA and 0,53 for IDVet using milk samples and the DSp to 0,95 for IDEXX, 1,00 for IDVet and CIV-HIPRA.

Conditioned media from mesenchymal stromal cells restore sodium transport and preserve epithelial permeability in an in vitro model of acute alveolar injury.

Mesenchymal stromal cells (MSCs) or their media (MSC-M) were reported to reverse acute lung injury (ALI)-induced decrease of alveolar fluid clearance. To determine the mechanisms by which MSC-M exert their beneficial effects, an in vitro model of alveolar epithelial injury was created by exposing primary rat alveolar epithelial cells (AECs) to hypoxia (3% O2) plus cytomix, a combination of IL-1β, TNF-α, and IFN-γ. MSC-M were collected from human MSCs exposed for 12 h to either normoxia (MSC-M) or to hypoxia plus cytomix (HCYT-MSC-M).

Hypoxia-induced inhibition of epithelial Na(+) channels in the lung. Role of Nedd4-2 and the ubiquitin-proteasome pathway.

Transepithelial sodium transport via alveolar epithelial Na(+) channels (ENaC) and Na(+),K(+)-ATPase constitutes the driving force for removal of alveolar edema fluid. Alveolar hypoxia associated with pulmonary edema may impair ENaC activity and alveolar Na(+) absorption through a decrease of ENaC subunit expression at the apical membrane of alveolar epithelial cells (AECs). Here, we investigated the mechanism(s) involved in this process in vivo in the β-Liddle mouse strain mice carrying a truncation of β-ENaC C-terminus abolishing the interaction between β-ENaC and the ubiquitin protein-ligase Nedd4-2 that targets the channel for endocytosis and degradation and in vitro in rat AECs.

Activation of the heat shock response attenuates the interleukin 1β-mediated inhibition of the amiloride-sensitive alveolar epithelial ion transport.

Acute lung injury (ALI) is a clinical syndrome characterized by hypoxia, which is caused by the breakdown of the alveolar capillary barrier. Interleukin 1β (IL-1β), a cytokine released within the airspace in ALI, downregulates the α subunit of the epithelial sodium channel (αENaC) transcription and protein expression via p38 MAP kinase-dependent signaling. Although induction of the heat shock response can restore alveolar fluid clearance compromised by IL-1β following the onset of severe hemorrhagic shock in rats, the mechanisms are not fully understood.

IL-8 inhibits cAMP-stimulated alveolar epithelial fluid transport via a GRK2/PI3K-dependent mechanism.

Patients with acute lung injury (ALI) who retain maximal alveolar fluid clearance (AFC) have better clinical outcomes. Experimental and small clinical studies have shown that β2-adrenergic receptor (β2AR) agonists enhance AFC via a cAMP-dependent mechanism. However, two multicenter phase 3 clinical trials failed to show that β2AR agonists provide a survival advantage in patients with ALI.

KGF-2 targets alveolar epithelia and capillary endothelia to reduce high altitude pulmonary oedema in rats.

High altitude pulmonary oedema (HAPE) severely affects non-acclimatized individuals and is characterized by alveolar flooding with protein-rich oedema as a consequence of blood-gas barrier disruption. Limited choice for prophylactic treatment warrants effective therapy against HAPE. Keratinocyte growth factor-2 (KGF-2) has shown efficiency in preventing alveolar epithelial cell DNA damages in vitro.

PAI-1 is an essential component of the pulmonary host response during Pseudomonas aeruginosa pneumonia in mice.

Rationale: Elevated plasma and bronchoalveolar lavage fluid plasminogen activator inhibitor 1 (PAI-1) levels are associated with adverse clinical outcome in patients with pneumonia caused by Pseudomonas aeruginosa. However, whether PAI-1 plays a pathogenic role in the breakdown of the alveolar-capillary barrier caused by P aeruginosa is unknown.

Objectives: The role of PAI-1 in pulmonary host defence and survival during P aeruginosa pneumonia in mice was tested.

Cytoprotective-selective activated protein C attenuates Pseudomonas aeruginosa-induced lung injury in mice.

Inhibition of the small GTPase RhoA attenuates the development of pulmonary edema and restores positive alveolar fluid clearance in a murine model of Pseudomonas aeruginosa pneumonia. Activated protein C (aPC) blocks the development of an unfavorably low ratio of small GTPase Rac1/RhoA activity in lung endothelium through endothelial protein C receptor (EPCR)/protease-activated receptor-1 (PAR-1)-dependent signaling mechanisms that include transactivating the sphingosine-1-phosphate (S1P) pathway. However, whether aPC's cytoprotective effects can attenuate the development of pulmonary edema and death associated with P.

Mesenchymal stem cells for acute lung injury: preclinical evidence.

Several experimental studies have suggested that mesenchymal stem cells may have value for the treatment of clinical disorders, including myocardial infarction, diabetes, acute renal failure, sepsis, and acute lung injury. In preclinical studies, mesenchymal stem cells have been effective in reducing lung injury from endotoxin, live bacteria, bleomycin, and hyperoxia. In some studies, the cultured medium from mesenchymal stem cells has been as effective as the mesenchymal stem cells themselves.

Critical role of the small GTPase RhoA in the development of pulmonary edema induced by Pseudomonas aeruginosa in mice.

Background: Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe pneumonia in critically ill patients. We have reported previously that P. aeruginosa exotoxins S and T mediate in vitro the increase in protein permeability across lung endothelial cell monolayers via a RhoA-dependent mechanism.

Transforming growth factor beta1 inhibits cystic fibrosis transmembrane conductance regulator-dependent cAMP-stimulated alveolar epithelial fluid transport via a phosphatidylinositol 3-kinase-dependent mechanism.

Exogenous or endogenous beta(2)-adrenergic receptor agonists enhance alveolar epithelial fluid transport via a cAMP-dependent mechanism that protects the lungs from alveolar flooding in acute lung injury. However, impaired alveolar fluid clearance is present in most of the patients with acute lung injury and is associated with increased mortality, although the mechanisms responsible for this inhibition of the alveolar epithelial fluid transport are not completely understood. Here, we found that transforming growth factor beta1 (TGF-beta1), a critical mediator of acute lung injury, inhibits beta(2)-adrenergic receptor agonist-stimulated vectorial fluid and Cl(-) transport across primary rat and human alveolar epithelial type II cell monolayers.

Stress failure plays a major role in the development of high-altitude pulmonary oedema in rats.

Hypoxia and exertion are considered as the two main factors in the development of high-altitude pulmonary oedema (HAPE), however its pathophysiology remains unclear. Therefore, we established a model in which 32 Sprague-Dawley rats were randomly assigned to normoxic rest, hypoxic rest, normoxic exercise and hypoxic exercise. An altitude of 4,700 m was simulated using hypobaric hypoxia, while exercise consisted 48 h walk with 15-20 min breaks every 4 h.

Serotonin decreases alveolar epithelial fluid transport via a direct inhibition of the epithelial sodium channel.

Hypoxia and epithelial stretch that are commonly observed in patients with acute lung injury have been shown to promote the release of serotonin (5-hydroxytryptamine, 5-HT) in vitro. However, whether 5-HT contributes to the decrease of alveolar epithelial fluid transport, which is a hallmark of lung injury, is unknown. Thus, we investigated the effect of 5-HT on ion and fluid transport across the alveolar epithelium.

Electrophysiological characterization of rat type II pneumocytes in situ.

Optimal aeration of the lungs is dependent on an alveolar fluid clearance, a process that is governed by Na+ and Cl- transport. However, the specific contribution of various ion channels in different alveolar cell types under basal or stimulated conditions is not exactly known. We established a novel functional model of rat lung slices suitable for nystatin-perforated whole-cell patch-clamp experiments.

Halothane directly modifies Na+ and K+ channel activities in cultured human alveolar epithelial cells.

During inhalational anesthesia, halogenated gases are in direct contact with the alveolar epithelium, in which they may affect transepithelial ion and fluid transport. The effects of halogenated gases in vivo on epithelial Na+ and K+ channels, which participate in alveolar liquid clearance, remain unclear. In the present study, the effects of halothane (1, 2, and 4% atm) on ion-channel function in cultured human alveolar cells were investigated using the patch-clamp technique.

Differentiation of epithelial Na+ channel function. An in vitro model.

Confluent monolayers of epithelial cells grown on nonporous support form fluid-filled hemicysts called domes, which reflect active ion transport across the epithelium. Clara-like H441 lung adenocarcinoma cells grown on glass supports and exposed to 50 nM dexamethasone developed domes in a time-dependent fashion. Uplifting of small groups of cells occurred within 6-12 h, well formed domes appeared between 24 and 48 h, and after 7 days, individual domes started to merge.

Modulation of epithelial Na+ channel activity by long-chain n-3 fatty acids.

The epithelial sodium channel is found in apical membranes of a variety of native epithelial tissues, where it regulates sodium and fluid balance. In vivo, a number of hormones and other endogenous factors, including polyunsaturated fatty acids (PUFAs), regulate these channels. We tested the effects of essential n-3 and n-6 PUFAs on amiloride-sensitive sodium transport in A6 epithelial cells.