bluuebunny/crossref_metadata_2025 huggingface dataset:
The nature of leukocyte shape changes in the pulmonary capillaries
Authors: Redenbach Darlene M. , English Dean , Hogg James C.
Published: December 2017

The size discrepancy between leukocytes [white blood cells (WBCs)] and pulmonary capillaries requires WBCs to deform. We investigated the persistence of this deformation on cells leaving the capillary bed and the role played by the cytoskeleton. Isolated rabbit lungs were perfused in situ via the pulmonary artery with effluent fractions collected from the left ventricle. Washout curves from cell counts in each fraction confirmed that WBCs are preferentially retained over erythrocytes. WBC deformation present on exit from the circulation was compared with that present after recovery in paired fractions, fixed either immediately or 60 min later. These cells were compared with cells recovered from the capillary in perfused fixative or fixed in peripheral blood. Our results show that leukocyte deformation persisted after the cells exited the pulmonary circulation. This deformation was associated with minimal submembranous F-actin staining, and microtubule distribution and cell polarization were unchanged. We conclude that cytoskeletal changes that occur during WBC deformation in the pulmonary capillaries are minimal and differ from those known to occur in actively migrating cells during chemotaxis.
Involvement of the ICE family of proteases in silica-induced apoptosis in human alveolar macrophages
Authors: Iyer Rashi , Holian Andrij
Published: December 2017

Exposure to silica dust can result in lung inflammation that may progress to fibrosis for which there is no effective clinical treatment. The mechanisms involved in the development of pulmonary silicosis have not been well defined; however, most current evidence implicates a central role for alveolar macrophages in this process. We have previously demonstrated that fibrotic agents, such as asbestos and silica, induce apoptosis in human alveolar macrophages. The goal of this study was to identify molecular events in the silica-induced apoptotic process to better understand the mechanism by which fibrotic agents may be inducing apoptosis in human alveolar macrophages. To elucidate the possible mechanism by which silica causes apoptosis, we investigated the involvement of the interleukin-converting enzyme (ICE) family of proteases. Human alveolar macrophages were treated with silica in vitro and were examined for the involvement of ICE, Ich-1L, and cpp32β in silica-induced apoptosis. Pretreatment of cells with 10 μM of the ICE inhibitor z-Val-Ala-Asp-fluoromethyl ketone and the cpp32β inhibitor Asp-Glu-Val-Asp-fluoromethyl ketone completely blocked silica-induced apoptosis. Additionally, an increased formation of the active p20 fragments of ICE and Ich-1Las well as degradation of the inactive zymogen form of cpp32β protein were observed in silica-treated human alveolar macrophages, indicating activation of these proteases. Furthermore, degradation of the nuclear protein poly(ADP-ribose) polymerase was observed within 2 h of silica treatment. These results suggest that silica-induced apoptosis involves activation of the ICE family of proteases and is the first step in elucidating the intracellular mechanism of particulate-induced apoptosis in human alveolar macrophages.
Ascorbate deficiency and oxidative stress in the alveolar type II cell
Authors: Brown Lou Ann S. , Harris Frank L. , Jones Dean P.
Published: December 2017

The objective of this study was to determine the impact of limited ascorbate (Asc) availability on type II cell sensitivity to oxidant stress. Guinea pigs were fed diets with or without Asc for 18 days, and type II cells were isolated. Although lung Asc was decreased by 90% in deficient animals (scorbutic), type II cell Asc was decreased by 50%. Upon treatment with 250 μM H2O2, the necrotic injury was twofold greater in scorbutic cells compared with control cells. With 100 μM H2O2treatment, apoptotic injury was twofold greater in scorbutic cells compared with control cells. Although there was less necrotic injury in cells exposed to 95% O2, the scorbutic cells were more sensitive than control cells. Asc pretreatment protected against necrosis and apoptosis. The Asc analog isoascorbate provided partial protection and suggested that part of the protection was not chemical detoxification but was Asc specific. We conclude that limited Asc availability resulted in a functional type II cell but a cell more sensitive to oxidant-induced injury.
Impairment of cation transport in A549 cells and rat alveolar epithelial cells by hypoxia
Authors: Mairbäurl Heimo , Wodopia Ralf , Eckes Sigrid , Schulz Susanne , Bärtsch Peter
Published: December 2017

A reduced cation reabsorption across the alveolar epithelium decreases water reabsorption from the alveoli and could diminish clearing accumulated fluid. To test whether hypoxia restricts cation transport in alveolar epithelial cells, cation uptake was measured in rat lung alveolar type II pneumocytes (AII cells) in primary culture and in A549 cells exposed to normoxia and hypoxia. In AII and A549 cells, hypoxia caused a[Formula: see text]-dependent inhibition of the Na-K pump, of Na-K-2Cl cotransport, and of total and amiloride-sensitive22Na uptake. Nifedipine failed to prevent hypoxia-induced transport inhibition in both cell types. In A549 cells, the inhibition of the Na-K pump and Na-K-2Cl cotransport occurred within ∼30 min of hypoxia, was stable >20 h, and was reversed by 2 h of reoxygenation. There was also a reduction in cell membrane-associated Na-K-ATPase and a decrease in Na-K-2Cl cotransport flux after full activation with calyculin A, indicating a decreased transport capacity. [14C]serine incorporation into cell proteins was reduced in hypoxic A549 cells, but inhibition of protein synthesis with cycloheximide did not reduce ion transport. In AII and A549 cells, ATP levels decreased slightly, and ADP and the ATP-to-ADP ratio were unchanged after 4 h of hypoxia. In A549 cells, lactate, intracellular Na, and intracellular K were unchanged. These results indicate that hypoxia inhibits apical Na entry pathways and the basolateral Na-K pump in A549 cells and rat AII pneumocytes in culture, indicating a hypoxia-induced reduction of transepithelial Na transport and water reabsorption by alveolar epithelium. If similar changes occur in vivo, the impaired cation transport across alveolar epithelial cells might contribute to the formation of hypoxic pulmonary edema.
Regulation of cGMP by soluble and particulate guanylyl cyclases in cultured human airway smooth muscle
Authors: Hamad Ahmed M. , Range Simon , Holland Elaine , Knox Alan J.
Published: December 2017

Although guanosine 3′,5′-cyclic monophosphate (cGMP) acts as a relaxant second messenger, the regulation of intracellular cGMP has not been comprehensively studied in human airway smooth muscle. We studied the production of cGMP by cultured human airway smooth muscle cells (HASMC) after stimulation with activators of soluble guanylyl cyclase [sodium nitroprusside (SNP) and S-nitroso- N-acetylpenicillamine (SNAP)] and particulate guanylyl cyclase [atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and Escherichia coli heat stable enterotoxin (STa)]. cGMP was measured by enzyme-linked immunosorbent assay. Both SNP (10−6to 10−3M) and SNAP (10−6to 10−3M) caused concentration-dependent elevation of cGMP in the presence of the nonselective phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (10−3M), with cGMP increasing 6- and 15-fold in response to SNP and SNAP, respectively, at the highest concentration tested (10−3M). The increases in cGMP in response to SNP (5 × 10−5M) and SNAP (10−5M) were inhibited by hemoglobin (Hb; 5 × 10−5M), a nitric oxide scavenger, and methylene blue (MB; 5 × 10−4M), an inhibitor of guanylyl cyclase. cGMP accumulation after SNAP was abolished by both Hb and MB. The response to SNP was inhibited by 79% with Hb and was abolished with MB. ANP, BNP, and CNP (10−9to 10−5M) + phosphoramidon (10−6M) caused a concentration-dependent elevation in cGMP with an order of potency ANP > BNP > CNP. cGMP formation in the presence of the highest concentration of the most potent natriuretic peptide (10−5M ANP) was two- to threefold greater than with the highest concentration of SNAP. The increase in cGMP seen with natriuretic peptides was similar in the presence or absence of phosphoramidon, a neutral endopeptidase (NEP) inhibitor, suggesting that NEP is not playing a role in modulating the effect of natriuretic peptides in HASMC. STa (400 IU/ml) had no effect on cGMP levels. SNAP- and ANP-induced cGMP accumulation was increased by the selective type V PDE inhibitors SKF-96231 and zaprinast, suggesting that type V PDE is responsible for cGMP breakdown in HASMC. These results suggest that cultured HASMC contain both soluble and particulate guanylyl cyclases. The order of potency of the natriuretic peptides ANP > BNP > CNP suggests that type A particulate membrane-bound guanylate cyclase predominates.
Rhinovirus stimulation of interleukin-8 in vivo and in vitro: role of NF-κB
Authors: Zhu Zhou , Tang Weiliang , Gwaltney Jack M. , Wu Yang , Elias Jack A.
Published: December 2017

Neutrophil infiltration is a well-documented early event in the pathogenesis of rhinovirus (RV) infections. To further understand the mechanisms responsible for this neutrophilia, we determined whether interleukin (IL)-8 was present at sites of experimental RV infection in vivo and characterized the mechanism(s) by which RV stimulates IL-8 production in vitro. IL-8 was readily detectable in the nasal washings of all normal volunteers and did not increase with sham nasal inoculation. In contrast, RV infection caused a significant additional increase in nasal IL-8, the levels of which peaked 48–72 h after virus inoculation. RV was a potent stimulator of IL-8 protein production by A549 epithelial-like cells, MRC-5 fibroblasts, and normal human bronchial epithelial cells in vitro. This induction was associated with a significant increase in IL-8 mRNA accumulation and gene transcription. RV also stimulated IL-8 promoter-driven luciferase activity. This stimulation was significantly decreased by mutation of the nuclear factor (NF)-IL-6 site and was completely abrogated by mutation of the NF-κB site in this promoter. In addition, NF-κB-DNA binding activity was rapidly induced in RV-infected cells. This inducible binding was made up of p65 and, to a lesser extent, p50 NF-κB moieties. These studies demonstrate that IL-8 is present in normal nasal secretions and that the levels of IL-8 are further increased after RV infection. They also demonstrate that RVs are potent stimulators of IL-8 production and that this induction is mediated, at least in part, by an NF-κB-dependent transcriptional activation pathway. IL-8 may contribute to the pathogenesis of RV infection, and NF-κB activation may be a central event in RV-induced pathologies.
Dexamethasone upregulates the Na-K-ATPase in rat alveolar epithelial cells
Authors: Barquin Nora , Ciccolella David E. , Ridge Karen M. , Sznajder J. Iasha
Published: December 2017

Previous studies in kidney, heart, and liver cells have demonstrated that dexamethasone regulates the expression of Na-K-ATPase. In the lungs, Na-K-ATPase has been reported in alveolar epithelial type II (ATII) cells and is thought to participate in active Na+transport and lung edema clearance. The aim of this study was to determine whether Na-K-ATPase would be regulated by dexamethasone in cultured rat ATII cells. Regulation of the Na-K-ATPase by dexamethasone could lead to a greater understanding of its role in active Na+transport and lung edema clearance. Rat ATII cells were isolated, plated for 24 h, and exposed to 10−7and 10−8M dexamethasone. These cells were harvested at 0, 3, 6, 12, and 24 h after dexamethasone exposure for determination of steady-state Na-K-ATPase mRNA transcript levels, protein expression, and function. The steady-state Na-K-ATPase β1-mRNA transcript levels increased in ATII cells 6, 12, and 24 h after dexamethasone exposure ( P < 0.05). However, the steady-state α1-mRNA transcript levels were unchanged. The protein expression for the α1- and β1-subunits increased in ATII cells exposed to dexamethasone compared with controls in association with a temporal increase in Na-K-ATPase function after dexamethasone exposure. These results suggest that dexamethasone regulates Na-K-ATPase in ATII cells possibly by transcriptional, translational, and posttranslational mechanisms.
Hypoxia stimulates human preproendothelin-1 promoter activity in transgenic mice
Authors: Aversa Catherine R. , Oparil Suzanne , Caro Jaime , Li Huaibin , Sun Shuang-Dan , Chen Yiu-Fai , Swerdel Mavis R. , Monticello Thomas M. , Durham Stephen K. , Minchenko Alexander , Lira Sergio A. , Webb Maria L.
Published: December 2017

Significant elevations in endothelin (ET)-1 levels accompany many diseases, but the underlying regulatory mechanisms are unclear. To investigate the in vivo regulation of human preproendothelin-1 (PPET-1), we examined the activity of the PPET-1 promoter in transgenic mice exposed to hypoxia. Mice expressing one of three PPET-1 promoter-luciferase (PPET-1/LUC) reporter transgenes (≈2.5 kb, 138 bp, or none of the 5′-flanking sequences of the PPET-1 gene) were generated. LUC expression was reduced in mice with a truncated 138-bp PPET-1 promoter. Exposure of mice bearing the 2.5-kb PPET-1/LUC transgene to hypoxia (10% O2for 24 h) increased LUC expression sixfold in pulmonary tissue but only twofold in other tissues. In situ hybridization revealed the strongest transgene expression in the pulmonary vasculature and bronchiolar epithelium. These data are consistent with the hypothesis that hypoxic induction of the PPET-1 gene leads to increased pulmonary production of ET-1 in diseases associated with low O2tension.
Heterogeneity of the composition and thickness of tracheal mucus in rats
Authors: Sims David E. , Horne Margaret M.
Published: December 2017

Inability to preserve airway mucus in situ has limited our understanding of its structure and function. This light- and transmission electron-microscopic study of rat tracheal mucus used a nonaqueous fixative that retains mucus (epiphase) over a lucent layer (hypophase). The fixative is a 1% solution of osmium tetroxide dissolved in a perfluorocarbon. The mean thickness of rat tracheal epiphase was 5 μm, with significant variation (0.1–50 μm) around the tracheal circumference. Tracheal mucus was thickest at the trachealis muscle region and contained cells, cellular debris, and a variable amount of surfactant and lipid, estimated at 4–16% of the total epiphase in five rats, with a mean composition of 9%. Lipid was observed on the surface of the epiphase, embedded within mucus, and at the epiphase-hypophase interface. Refined study of developmental, physiological, and pathological alterations to the airway coat may benefit from this approach.
Hemorrhagic shock induces G-CSF expression in bronchial epithelium
Authors: Hierholzer Christian , Kelly Edward , Tsukada Katsuhiko , Loeffert Eric , Watkins Simon , Billiar Timothy R. , Tweardy David J.
Published: December 2017

Hemorrhagic shock (HS) initiates a series of inflammatory processes that includes the activation of polymorphonuclear granulocytic neutrophils (PMN). We tested the hypothesis that HS induces granulocyte colony-stimulating factor (G-CSF), a cytokine that augments PMN effector functions, in the lungs of rats. Sprague-Dawley rats were subjected to compensated or decompensated HS followed by resuscitation and death at 4 or 8 h. Animals subjected to HS demonstrated acute lung injury with PMN infiltration, edema, and hypoxia. Using semiquantitative reverse transcriptase-polymerase chain reaction, we detected a 1.9- to 7.1-fold increase in G-CSF mRNA levels in the lung of animals subjected to HS compared with sham controls. Levels of G-CSF mRNA increased with increased duration of the ischemic phase of resuscitated shock. In situ hybridization revealed that bronchoepithelial cells were the major cellular site of G-CSF mRNA. Thus production of G-CSF mRNA by bronchoepithelial cells is dramatically increased in a rat model of HS that also demonstrated lung injury. Increased local G-CSF levels may contribute to PMN recruitment and activation and resultant lung injury in HS.
Expression and regulation of γ-glutamyl transpeptidase-related enzyme in tracheal cells
Authors: Potdar Pravin D. , Andrews Kaya L. , Nettesheim Paul , Ostrowski Lawrence E.
Published: December 2017

Glutathione plays an essential role in protecting the pulmonary system from toxic insults. γ-Glutamyl transpeptidase-related enzyme (GGT-rel) is a novel protein capable of cleaving the γ-glutamyl peptide bond of glutathione and of converting leukotriene C4 to leukotriene D4. A rat homologue of GGT-rel was identified and was found to be highly expressed in cultures of differentiating rat tracheal epithelial (RTE) cells. The 2.6-kb cDNA predicts a 572-amino acid protein with 79% identity to human GGT-rel. GGT-rel was weakly expressed in normal trachea but was strongly induced by epidermal growth factor in cultures of RTE cells. GGT-rel was also highly expressed in lung tumors induced by inhalation of isobutyl nitrite. These results demonstrate that GGT-rel 1) is expressed in normal tracheal cells, 2) can be induced by epidermal growth factor, and 3) is elevated after chemical exposure. The induction of high levels of GGT-rel may play an important role in protecting the lung from oxidative stress or other toxic insults.
Phosphorylation of the 27-kDa heat shock protein via p38 MAP kinase and MAPKAP kinase in smooth muscle
Authors: Larsen Janice K. , Yamboliev Ilia A. , Weber Lee A. , Gerthoffer William T.
Published: December 2017

The 27-kDa heat shock protein (HSP27) is expressed in a variety of tissues in the absence of stress and is thought to regulate actin filament dynamics, possibly by a phosphorylation/dephosphorylation mechanism. HSP27 has also been suggested to be involved in contraction of intestinal smooth muscle. We have investigated phosphorylation of HSP27 in airway smooth muscle in response to the muscarinic agonist carbachol. Carbachol increased32P incorporation into canine tracheal HSP27 and induced a shift in the distribution of charge isoforms on two-dimensional gels to more acidic, phosphorylated forms. The canine HSP27 amino acid sequence includes three serine residues corresponding to sites in human HSP27 known to be phosphorylated by mitogen-activated protein kinase-activated protein (MAPKAP) kinase-2. To determine whether muscarinic receptors are coupled to a “stress response” pathway in smooth muscle culminating in phosphorylation of HSP27, we assayed MAPKAP kinase-2 activity and tyrosine phosphorylation of p38 mitogen-activated protein (MAP) kinase, the enzyme thought to activate MAPKAP kinase-2. Recombinant canine HSP27 expressed in Escherichia coli was a substrate for MAPKAP kinase-2 in vitro as well as a substrate for endogenous smooth muscle HSP27 kinase, which was activated by carbachol. Carbachol also increased tyrosine phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinases, reduced activation of endogenous HSP27 kinase activity and blocked the shift in HSP27 charge isoforms to acidic forms. We suggest that HSP27 in airway smooth muscle, in addition to being a stress response protein, is phosphorylated by a receptor-initiated signaling cascade involving muscarinic receptors, tyrosine phosphorylation of p38 MAP kinase, and activation of MAPKAP kinase-2.
Modulating phosphatidic acid metabolism decreases oxidative injury in rat lungs
Authors: Guidot David M. , Bursten Stuart L. , Rice Glenn C. , Chaney Robert B. , Singer Jack W. , Repine Alexander J. , Hybertson Brooks M. , Repine John E.
Published: December 2017

We determined that lisofylline, a potent inhibitor of oleate- and linoleate-containing phosphatidic acid formation (half-maximal inhibitory concentration = 40 nM), prevented oxidant-mediated capillary leak in isolated rat lungs given interleukin-8 (IL-8) intratracheally and perfused with human neutrophils. Lung leak was prevented by lung, but not neutrophil, lisofylline pretreatment. Furthermore, although lisofylline inhibited IL-8-stimulated neutrophil production of phosphatidic acid in vitro, it did not prevent IL-8-stimulated neutrophil adherence, chemotaxis, or intracellular calcium mobilization or N-formyl-Met-Leu-Phe (fMLP)-stimulated oxidant production in vitro. Lisofylline also prevented acute capillary leak in isolated rat lungs perfused only with the oxidant generator purine-xanthine oxidase but did not scavenge[Formula: see text] or H2O2in vitro. Finally, lisofylline-mediated protection against lung leak in both models was associated with alterations in lung membrane free fatty acid acyl composition (as reflected by the decreased ratio [linoleate + oleate]/[palmitate]). We conclude that lisofylline prevented both neutrophil-dependent and neutrophil-independent oxidant-induced capillary leak in isolated rat lungs and that protection appears to be mediated by blocking intrinsic lung linoleoyl phosphatidic acid metabolism. We speculate that lisofylline, in addition to our previously reported effects on cytokine signaling by intrapulmonary mononuclear cells, alters intrinsic pulmonary capillary membrane composition and renders this barrier less vulnerable to oxidative damage.
Regulation of heme oxygenase-1 gene expression in vascular smooth muscle cells by nitric oxide
Authors: Hartsfield Cynthia L. , Alam Jawed , Cook Julia L. , Choi Augustine M. K.
Published: December 2017

Heme oxygenase (HO)-mediated heme degradation is the primary mechanism for production of cellular carbon monoxide (CO). Analogous to nitric oxide (NO), CO mediates physiological and cellular functions such as vasodilatation, stimulation of guanylate cyclase, and neuronal transmission. In view of accumulating data demonstrating a correlation between the activity of these two gaseous molecules and that the predominant source of CO is via HO catalysis, we hypothesized that NO regulates HO expression. We demonstrate that the NO donor spermine NONOate (SNN) increases steady-state levels of HO-1 mRNA in aortic vascular smooth muscle cells (aSMC) in both a time- and dose-dependent manner. The accumulation of HO-1 mRNA that correlated with increased HO-1 protein synthesis resulted from both an increased rate of gene transcription and a decreased rate of mRNA turnover. Inhibition of the NO-induced HO-1 mRNA expression by cycloheximide suggests that new protein synthesis is required for increased HO-1 gene expression. Induction of HO-1 expression by SNN occurs in a guanosine 3′,5′-cyclic monophosphate (cGMP)-independent manner because exposure of cells to 8-bromoguanosine 3′,5′-cyclic monophosphate, a cGMP analog, did not increase HO-1 mRNA levels, and pretreatment of cells with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a selective guanylate cyclase inhibitor, did not prevent SNN-induced HO-1 mRNA accumulation. The antioxidant N-acetyl-l-cysteine markedly inhibited SNN-induced HO-1 mRNA expression, whereas peroxynitrite did not induce HO-1 expression in aSMC. Interestingly, CO did not attenuate NO-induced HO-1 expression through an autocrine negative feedback mechanism as had been observed for hypoxia-induced HO-1 expression. These data provide evidence for an important regulatory network between NO and CO via HO-1.
Mucoglycoprotein hypersecretion in allergic rhinitis and cystic fibrosis
Authors: Yuta Atsushi , Ali Mushtaq , Sabol Marybeth , Gaumond Ethan , Baraniuk James N.
Published: December 2017

There is little information about specific changes in submucosal gland exocytosis in diseases such as allergic rhinitis (AR), nonallergic rhinitis (NAR), and cystic fibrosis (CF). Nasal lavage fluids were collected from normal, AR, NAR, and CF subjects. Concentrations of lysozyme, Alcian blue-staining mucoglycoconjugate material (AB+m), and human high-molecular-weight mucoglycoconjugates recognized by the 7F10 murine monoclonal antibody [7F10-immunoreactive mucoglycoconjugates (7F10-irm)] were measured. AB+m and 7F10-irm were characterized by Sepharose-2B column chromatography and glycosidase digestion. 7F10-irm was increased in CF (2.4-fold; P = 0.001) and AR (12.7-fold; P = 0.00007) subjects. AB+m was increased in CF (1.8-fold; P = 0.049) and AR (1.2-fold; P = 0.07) subjects. There were no changes in NAR subjects. On Sepharose-2B columns, AB+m peaks were at 1.3–3.0 × 106and 0.36–0.65 × 106Da. 7F10-irm showed four distinct peaks at 1.5, 1.2, 0.85, and 0.53 × 106Da that were nearly identical in both normal and CF samples. Sialic acid was present in both 7F10-irm and AB+m. 7F10-irm and AB+m are mutually exclusive sialylated mucoglycoproteins that are significantly induced in AR and CF but not in NAR.
Proliferation and repair of guinea pig tracheal epithelium after neuropeptide depletion and injury in vivo
Authors: Kim John S. , McKinnis Valerie S. , Adams Kimberly , White Steven R.
Published: December 2017

Neuropeptides stimulate airway epithelial cell proliferation and migration in vitro, but the role of neuropeptides in the repair of the epithelium after injury in vivo is not clear. We studied epithelial proliferation and repair in 83 male Hartley guinea pigs. Animals received capsaicin weekly for 3 wk to deplete airway neuropeptides. One week later, the dorsal aspect of the trachea was injured with a metal stylette. Animals were killed 1 h to 1 wk later, after which epithelial cell proliferation was assessed for the presence of proliferating cell nuclear antigen (PCNA). PCNA labeling was <3% in noninjured animals. PCNA labeling increased substantially in the first 72 h after injury in control animals but was significantly decreased in capsaicin-treated animals within and adjacent to the site of injury. PCNA labeling increased opposite to the injury site in both control and capsaicin animals over the first 72 h. We conclude that neuropeptide depletion significantly attenuates both epithelial cell proliferation and repair in the first 72 h after mechanical injury to the trachea. However, neuropeptide depletion did not slow the ultimate repair of tracheal mucosal injury. Proliferation of epithelial cells in response to injury occurs throughout the airway, even away from the injury site.
Retinoic acid and dexamethasone affect RAR-β and surfactant protein C mRNA in the MLE lung cell line
Authors: Grummer Mary A. , Zachman Richard D.
Published: December 2017

Lung development and surfactant biosynthesis are affected by retinoic acid (RA) and dexamethasone (Dex). Using a mouse lung epithelial cell line, we are exploring RA-Dex interactions through the study of RA and Dex effects on RA receptor (RAR) and surfactant protein (SP) C mRNA expression. RA increased expression of RAR-β (5.5 times) and SP-C (2 times) mRNA, with maximal effects at 24 h and at 10−6M. The RA induction was not inhibited by cycloheximide, suggesting RA affects transcription. With added actinomycin D, RA did not affect the disappearance rate of RAR-β mRNA, but SP-C mRNA degradation was slowed, indicating an effect on SP-C mRNA stability. Dex decreased RAR-β and SP-C expression to 75 and 70% of control values, respectively, with greatest effects at 48 h and at 10−7M. There was no effect of Dex on either RAR-β or SP-C mRNA disappearance with actinomycin D. However, cycloheximide prevented the effect of Dex. Despite Dex, RA increased both RAR-β and SP-C mRNA. This work suggests that RA and Dex affect RAR-β and SP-C genes by different mechanisms.
Human bronchial epithelial cells modulate collagen gel contraction by fibroblasts
Authors: Mio Tadashi , Liu Xiang-Der , Adachi Yuichi , Striz Ilja , Sköld C. Magnus , Romberger Debra J. , Spurzem John R. , Illig Mary G. , Ertl Ron , Rennard Stephen I.
Published: December 2017

Connective tissue contraction is an important aspect of both normal wound healing and fibrosis. This process may contribute to small airway narrowing associated with certain airway diseases. Fibroblast-mediated contraction of a three-dimensional collagen gel has been considered a model of tissue contraction. In this study, the ability of primary cultured human bronchial epithelial cells (HBEC) obtained by bronchial brushings to modulate fibroblast gel contraction was evaluated. Human lung fibroblasts (HFL1) were cast into type I collagen gels. The gels were floated both in dishes containing a monolayer of HBEC or in dishes without HBEC. Contraction assessed by measuring the area of gels was increased at all time points from 24 h up to 96 h of coculture. At 48 h, coculture of HBEC with fibroblasts resulted in significantly more contraction than fibroblasts alone (36.6 ± 1.2 vs. 20.4 ± 1.7%, P < 0.05). Lipopolysaccharide (LPS, 10 μg/ml) stimulation of the HBEC augmented the contraction (44.9 ± 1.0%, P < 0.05 vs. HBEC). In the presence of indomethacin, the augmentation by LPS was increased further (52.2 ± 4.3%, P< 0.05 vs. HBEC with LPS), suggesting that prostaglandins (PGs) are present and may inhibit contraction. Consistent with this, PGE was present in HBEC-conditioned medium. Bronchial epithelial cell conditioned medium had an effect similar to coculturing. SG-150 column chromatography revealed augmentive activity between 20 and 30 kDa and inhibitory activity between 10 and 20 kDa. Measurement by enzyme-linked immunosorbent assay confirmed the presence of the active form of transforming growth factor (TGF)-β2. The stimulatory activity of conditioned medium was blocked by adding anti-TGF-β antibody. These data demonstrate that, through the release of factors including TGF-β2which can augment and PGE which can inhibit, HBEC can modulate fibroblast-mediated collagen gel contraction. In this manner, HBEC may modulate fibroblast activities that determine the architecture of bronchial tissue.
Loss of lung mitochondrial aconitase activity due to hyperoxia in bronchopulmonary dysplasia in primates
Authors: Morton Ronald L. , Iklé David , White Carl W.
Published: December 2017

The premature primate exposed to hyperoxia provides a useful model of bronchopulmonary dysplasia. A critical target in hyperoxic injury is the mitochondrial matrix enzyme aconitase. We hypothesized that this enzyme’s activity would decline in the premature baboon lung during exposure to hyperoxia. Total aconitase activity was significantly decreased in the lungs of premature baboons of 140 days gestation with exposure to 100% oxygen for 6–10 days compared with as needed [pro re nada (PRN)] oxygen exposure and fetal controls ( P = 0.0001). In activity gels, lungs from 100% oxygen-exposed animals (6–10 days) showed a nearly complete loss of mitochondrial aconitase activity relative to lungs from animals exposed only to PRN oxygen. Decreased lung aconitase activity was not a nonspecific effect of hyperoxia, causing mitochondrial damage or loss, because the activity of the mitochondrial respiratory enzyme cytochrome oxidase was not different in lungs of 100% oxygen-exposed relative to PRN oxygen-exposed newborns. In 125-day-gestation premature primates (age 6–10 days), lung total aconitase activity was correlated with inspired oxygen tension ( r = 0.73 for fraction of inspired oxygen > 0.35), whereas, for animals of 140 days gestation, no such correlation was found. Thus the more premature animal’s lung was more susceptible to loss of aconitase.
Nicotine stimulates branching and expression of SP-A and SP-C mRNAs in embryonic mouse lung culture
Authors: Wuenschell Carol W. , Zhao Jingsong , Tefft J. Denise , Warburton David
Published: December 2017

Although the effects of maternal smoking on fetal growth and viability are overwhelmingly negative, there is a paradoxical enhancement of lung maturation as evidenced, in part, by a lower incidence of respiratory distress syndrome in infants of smoking mothers. Other epidemiologic and experimental evidence further support the view that a tobacco smoke constituent, possibly nicotine, affects the development of the lung in utero. We are studying the direct effects of nicotine on murine lung development using a serumless organ culture system. We have found that embryonic lungs explanted at 11 days gestation showed a 32% increase in branching after 4 days in culture in the presence of 1 μM nicotine and 7- to 15-fold increases in mRNAs encoding surfactant proteins A and C after 11 days. The effect of nicotine exposure on surfactant gene expression is apparently mediated by nicotinic acetylcholine receptors because it was blocked byd-tubocurarine. The nicotine-induced stimulation of surfactant gene expression could, in part, account for the effect of maternal smoking on the incidence of respiratory distress syndrome.
Grain dust-induced lung inflammation is reduced byRhodobacter sphaeroidesdiphosphoryl lipid A
Authors: Jagielo Paul J. , Quinn Timothy J. , Qureshi Nilofer , Schwartz David A.
Published: December 2017

To further determine the importance of endotoxin in grain dust-induced inflammation of the lower respiratory tract, we evaluated the efficacy of pentaacylated diphosphoryl lipid A derived from the lipopolysaccharide of Rhodobacter sphaeroides (RsDPLA) as a partial agonist of grain dust-induced airway inflammation. RsDPLA is a relatively inactive compound compared with lipid A derived from Escherichia coli (LPS) and has been demonstrated to act as a partial agonist of LPS-induced inflammation. To assess the potential stimulatory effect of RsDPLA in relation to LPS, we incubated THP-1 cells with RsDPLA (0.001–100 μg/ml), LPS (0.02 μg endotoxin activity/ml), or corn dust extract (CDE; 0.02 μg endotoxin activity/ml). Incubation with RsDPLA revealed a tumor necrosis factor (TNF)-α stimulatory effect at 100 μg/ml. In contrast, incubation with LPS or CDE resulted in TNF-α release at 0.02 μg/ml. Pretreatment of THP-1 cells with varying concentrations of RsDPLA before incubation with LPS or CDE (0.02 μg endotoxin activity/ml) resulted in a dose-dependent reduction in the LPS- or CDE-induced release of TNF-α with concentrations of RsDPLA of up to 10 μg/ml but not at 100 μg/ml. To further understand the role of endotoxin in grain dust-induced airway inflammation, we utilized the unique LPS inhibitory property of RsDPLA to determine the inflammatory response to inhaled CDE in mice in the presence of RsDPLA. Ten micrograms of RsDPLA intratracheally did not cause a significant inflammatory response compared with intratracheal saline. However, pretreatment of mice with 10 μg of RsDPLA intratracheally before exposure to CDE (5.4 and 0.2 μg/m3) or LPS (7.2 and 0.28 μg/m3) resulted in significant reductions in the lung lavage concentrations of total cells, neutrophils, and specific proinflammatory cytokines compared with mice pretreated with sterile saline. These results confirm the LPS-inhibitory effect of RsDPLA and support the role of endotoxin as the principal agent in grain dust causing airway inflammation.
Potential involvement of 4-hydroxynonenal in the response of human lung cells to ozone
Authors: Hamilton Raymond F. , Li Li , Eschenbacher William L. , Szweda Luke , Holian Andrij
Published: December 2017

Ozone is a photochemically generated pollutant that can cause acute pulmonary inflammation and induce cellular injury and may contribute to the development or exacerbation of chronic lung diseases. Despite much research, the mechanisms of ozone- and oxidant-induced cellular injury are still uncertain. Ozone and secondary free radicals have been reported to cause the formation of aldehydes in biological fluids. One of the most toxic aldehydes formed during oxidant-induced lipid peroxidation is 4-hydroxynonenal (HNE). HNE reacts primarily with Cys, Lys, and His amino acids, altering protein function and forming protein adducts. The purpose of this study was to determine whether HNE could account for the acute effects of ozone on lung cells. Human subjects were exposed to 0.4 parts/million ozone or air for 1 h with exercise (each subject served as his/her own control). Six hours after ozone exposure, cells obtained by airway lavage were examined for apoptotic cell injury, and cells from bronchoalveolar lavage were examined for apoptosis, presence of HNE adducts, and expression of stress proteins. Significant apoptosis was evident in airway lung cells after ozone exposure. Western analysis demonstrated an increase in a 32-kDa HNE protein adduct and a number of stress proteins, viz., 72-kDa heat shock protein and ferritin, in alveolar macrophages (AM) after ozone exposure. All of these effects could be replicated by in vitro exposure of AM to HNE. Consequently, the in vitro results and demonstration of HNE protein adducts after ozone exposure are consistent with a potential role for HNE in the cellular toxic effects of ozone.
Comparison of the uptake of fine and ultrafine TiO2 in a tracheal explant system
Authors: Churg A. , Stevens B. , Wright J. L.
Published: December 2017

To examine the relationship between particle uptake by pulmonary epithelial cells and particle size, we exposed rat tracheal explants to fine particles (FPs; 0.12 μm) or ultrafine particles (UFPs; 0.021 μm) of titanium dioxide for 3 or 7 days. By electron microscopy, particles were found in the epithelium at both time points, but in the subepithelial tissues, they were found only at 7 days. The volume proportion of both FPs and UFPs in the epithelium increased from 3 to 7 days; it was greater for UFPs at 3 days but was greater for FPs at 7 days. The volume proportion of particles in the subepithelium at 7 days was equal for both dusts, but the ratio of epithelial to subepithelial volume proportion was ∼2:1 for FPs and 1:1 for UFPs. Mean volume of individual particle aggregates was similar for both dusts at 3 days but was markedly smaller for FPs at 7 days. These observations suggest that the behavior of particles of different size is complex: UFPs persist in the tissues as relatively large aggregates, whereas the size of FP aggregates becomes smaller over time. UFPs appear to enter the epithelium faster, and once in the epithelium, a greater proportion of them is translocated to the subepithelial space compared with FPs. However, if it is assumed that the volume proportion is representative of particle number, the number of particles reaching the interstitial space is directly proportional to the number applied; i.e., overall, there is no preferential transport from lumen to interstitium by size.
Effect of dehydroepiandrosterone on hypoxic pulmonary vasoconstriction: a Ca2+-activated K+-channel opener
Authors: Farrukh Imad S. , Peng Wei , Orlinska Urszula , Hoidal John R.
Published: December 2017

In the present study, we investigated the effects of the naturally occurring hormone dehydroepiandrosterone (DHEA) on hypoxic pulmonary vasoconstriction (HPVC) in isolated ferret lungs and on K+ currents in isolated and cultured ferret pulmonary arterial smooth muscle cells (FPSMCs). Severe alveolar hypoxia (3% O2-5% CO2-92% N2) caused an initial increase in pulmonary arterial pressure (Ppa) that was followed by a reversal in pulmonary hypertension. Maintaining alveolar hypoxia caused a sustained secondary increase in Ppa. Pretreating the lungs with the K+-channel inhibitor tetraethylammonium (TEA) caused a small increase in baseline Ppa, potentiated HPVC, and prevented the reversal of HPVC during the sustained alveolar hypoxia. Treating the lungs with DHEA caused a near-complete reversal of HPVC in control lungs and in lungs that were pretreated with TEA. DHEA also reversed the KCl-induced increase in Ppa. In FPSMCs, DHEA caused an adenosine 3′,5′-cyclic monophosphate- and guanosine 3′,5′-cyclic monophosphate-independent increase in activity of the Ca2+-activated K+(KCa) current. In a cell-attached configuration, DHEA caused a mean shift of −22 mV in the voltage-dependent activation of the KCa channel. We conclude that DHEA is a novel KCa-channel opener of the pulmonary vasculature.
Tannin inhibits the cAMP-β-adrenergic receptor pathway in bovine tracheal epithelium
Authors: Cloutier Michelle M. , Schramm Craig M. , Guernsey Linda
Published: December 2017

Tannin, isolated from cotton bracts, inhibits chloride secretion in airway epithelium. In bovine tracheal epithelial cells, tannin (25 μg/ml) blunted isoproterenol (Iso)-stimulated adenosine 3′,5′-cyclic monophosphate (cAMP) accumulation. Inhibition was time and dose dependent, with 52 ± 5% (mean ± SE, n = 6) inhibition at 60 min and 82 ± 9% ( n = 3) inhibition at 8 h. Inhibition was reversible starting at 4 h. Low-molecular-mass tannin (1,000–5,000 Da) had no effect on Iso-stimulated cAMP accumulation, whereas N-acetylcysteine, which interacts with cysteine residues, blocked the effects of tannin on Iso-stimulated cAMP accumulation. Tannin exposure (25 μg/ml for 30 min) had no effect on the dissociation constant ( Kd) for [3H]dihydroalprenolol (DHA) (0.41 ± 0.03 nM, n = 3) but decreased maximal binding from 252 ± 32 to 162 ± 36 fmol/mg protein. Using single-point analysis and [3H]CGP-12177, we determined that tannin (25 μg/ml for 4 h) decreased surface β-adrenergic receptor density from 26.4 ± 4.3 ( n = 12) to 11.9 ± 3.0 fmol/mg protein and that the decrease was dose dependent. Agonist binding affinity by Iso displacement of DHA demonstrated a two-site model ( Kdvalues = 27 ± 9 and 2,700 ± 600 nM) and a ratio of high- to low-affinity receptors of 1:1. Tannin (25 μg/ml) steepened the curve and shifted it to the right, as did Gpp(NH)p. Gpp(NH)p had no further effect on the shape or position of the displacement curve in the presence of tannin. In contrast, when polymer length was decreased by oxidation, tannin had no effect on the DHA displacement curve. These data demonstrate that tannin reversibly desensitizes bovine tracheal epithelial cells to Iso, decreases β-adrenergic receptor density, and uncouples the receptor from its stimulatory G protein. These data also suggest that the polymer length of tannin and its interaction with cysteine residues are important for these effects. These studies provide additional evidence for the role of tannin in the occupational lung disease byssinosis.
Inhibition of airway liquid secretion and its effect on the physical properties of airway mucus
Authors: Trout Laura , King Malcolm , Feng Wei , Inglis Sarah K. , Ballard Stephen T.
Published: December 2017

The combination of both Cl−and[Formula: see text] secretion inhibitors causes an accumulation of mucins within the submucosal gland ducts of acetylcholine (ACh)-treated bronchi [S. K. Inglis, M. R. Corboz, A. E. Taylor, and S. T. Ballard. Am. J. Physiol. 272 ( Lung Cell. Mol. Physiol. 16): L372–L377, 1997], suggesting indirectly that these agents block airway gland liquid secretion. The present study tested the hypotheses that ACh-stimulated liquid secretion is driven by Cl−and [Formula: see text] secretion and that inhibition of this process leads to secretion of a dehydrated mucus with altered rheological properties. Excised distal bronchi from pigs were pretreated with either a combination of Cl−and[Formula: see text] secretion inhibitors (bumetanide, acetazolamide, dimethylamiloride, and 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid) or the dimethyl sulfoxide vehicle and were then treated with ACh to induce secretion. The rate of mucus liquid secretion was substantially reduced when the airways were pretreated with the anion secretion inhibitors. Mucus liquid from inhibitor-pretreated airways contained almost threefold more nonvolatile solids than the control liquid. Rheological analysis revealed that mucus liquid from inhibitor-pretreated airways expressed a significantly greater log G * (rigidity factor), whereas tangent δ (recoil factor) was significantly reduced. These results suggest that 1) ACh-induced liquid secretion in bronchi is driven by both Cl−and[Formula: see text] secretion and 2) inhibition of ACh-induced liquid secretion results in the secretion of mucus with a reduced water content and altered rheological properties.
Unaltered pulmonary capillary surface area in the presence of changing arterial resistance
Authors: Fisher Lyle E. , Cziraki Attila , Steinhart Curt M. , Catravas John D.
Published: December 2017

We hypothesized that capillary recruitment may not be solely dependent on extracapillary factors. To test this hypothesis, rabbits were anesthetized and placed on total cardiac bypass at a constant, physiological pulmonary blood flow. Vascular occlusion techniques were combined with measurement of the transpulmonary metabolism of an angiotensin-converting enzyme substrate, allowing the concomitant assessment of changes in segmental resistances and dynamically perfused capillary surface area. Intra-arterial serotonin infusion increased upstream pulmonary vascular resistances without affecting dynamically perfused capillary surface area. Intra-arterial isoproterenol infusion diminished serotonin-induced increased upstream resistances, also without affecting capillary surface area. These findings support the hypothesis that pulmonary capillary recruitment may not be solely dependent on extracapillary factors.
Respiratory acidosis in carbonic anhydrase II-deficient mice
Authors: Lien Yeong-Hau H. , Lai Li-Wen
Published: December 2017

To investigate the role of carbonic anhydrase (CA) II on pulmonary CO2exchange, we analyzed arterial blood gases from CA II-deficient and normal control mice. CA II-deficient mice had a low arterial blood pH (7.18 ± 0.06) and[Formula: see text] concentration ([[Formula: see text]]; 17.5 ± 1.9 meq/l) and a high [Formula: see text](47.4 ± 5.3 mmHg), consistent with mixed respiratory and metabolic acidosis. To eliminate the influence of metabolic acidosis on arterial blood gases, NaHCO3(4 mmol/kg body weight) was given intraperitoneally, and arterial blood gases were analyzed 4 h later. Normal mice had a small increase in pH and were able to maintain [Formula: see text] and [[Formula: see text]]. The metabolic acidosis in CA II-deficient mice was corrected ([[Formula: see text]], 22.9 ± 2.4 meq/l), and respiratory acidosis became more profound ([Formula: see text], 50.4 ± 2.4 mmHg). These results indicate that CA II-deficient mice have a partial respiratory compensation for metabolic acidosis. We conclude that CA II-deficient mice have a mixed respiratory and metabolic acidosis. It is most likely that CO2retention in these animals is due to CA II deficiency in both red blood cells and type II pneumocytes.
l-Arginine prevents lung neutrophil accumulation and preserves pulmonary endothelial function after endotoxin
Authors: Sheridan Brett C. , McIntyre Robert C. , Meldrum Daniel R. , Fullerton David A.
Published: December 2017

l-Arginine supplementation has been shown to restore endothelium-derived nitric oxide production in several pathological states. The purpose of this study was to examine the effect of administration of exogenousl-arginine on the endotoxin-induced lung neutrophil accumulation and impairment of endothelium-dependent guanosine 3′,5′-cyclic monophosphate (cGMP)-mediated pulmonary vasorelaxation in rats. Endothelium-dependent relaxation was tested by receptor-dependent [acetylcholine (ACh)] and receptor-independent (A-23187) pathways. Endothelium-independent relaxation was tested with sodium nitroprusside (SNP). In isolated pulmonary arterial rings, concentration-response curves were generated with ACh, A-23187, and SNP (10−9 to 10−6 M) 4 h after endotoxin (500 μg/kg ip) with and without prior administration ofl-arginine (300 mg/kg ip). Lung neutrophil accumulation was determined by myeloperoxidase (MPO) assay. After endotoxin, lung neutrophil accumulation was significantly increased (MPO activity, 3.8 ± 0.4 vs. 0.8 ± 0.1 units/g lung weight in control cells; P < 0.05), which was prevented byl-arginine treatment (MPO activity, 1.3 ± 0.3 units/g lung weight; P < 0.05 vs. endotoxin). Endotoxin produced a significant impairment of endothelium-dependent cGMP-mediated pulmonary vasorelaxation by receptor-dependent (ACh) and -independent (A-23187) pathways as well as of endothelium-independent relaxation (SNP). Prior treatment withl-arginine, but not withd-arginine, preserved endothelium-dependent vasorelaxation. Neitherl- nord-arginine influenced endotoxin-induced impairment of endothelium-independent, cGMP-mediated pulmonary vasorelaxation. We conclude that administration of exogenousl-arginine prevents endotoxin-induced lung neutrophil accumulation and attenuates its associated impairment of endothelium-dependent, cGMP-mediated pulmonary vasorelaxation.