bluuebunny/crossref_metadata_2025 huggingface dataset:
M. tuberculosisinduction of matrix metalloproteinase-9: the role of mannose and receptor-mediated mechanisms
Authors: Rivera-Marrero Carlos A. , Schuyler William , Roser Susanne , Ritzenthaler Jeffrey D. , Newburn Sarah A. , Roman Jesse
Published: March 2015

Mycobacterium tuberculosis(Mtb) infection induces the expression of matrix metalloproteinase-9 (MMP-9) in mouse lungs. In cultured human monocytic cells, Mtb bacilli and the cell wall glycolipid lipoarabinomannan (LAM) stimulate high levels of MMP-9 activity. Here, we explore the cellular mechanisms involved in the induction of MMP-9 by Mtb. We show that infection of THP-1 cells with Mtb caused a fivefold increase in MMP-9 mRNA that was associated with increased MMP-9 activity. MMP-9 induction was dependent on microtubule polymerization and protein kinase activation and was associated with increased DNA binding by the transcription factor activator protein-1 (AP-1), which appeared to be important for MMP-9 expression. We then explored the surface molecules potentially involved in Mtb induction of MMP-9, focusing on ligands of the mannose and β-glucan receptors. MMP-9 activity was induced by the mannose receptor ligands mannan, zymosan, and LAM, whereas the β-glucan receptor ligand laminarin was not effective. The most active inducers of MMP-9 activity were the particulate ligand zymosan and LAM. Pretreatment of cells with an anti-mannose receptor monoclonal antibody, but not anti-complement receptor 3, decreased the induction of MMP-9 activity by Mtb bacilli. Together, these results suggest that MMP-9 induction by Mtb occurs by receptor-mediated signaling mechanisms involving the binding of mannosylated ligands to mannose receptors, the modulation by cytoskeletal elements such as microtubules, the activation of protein kinases, and transcriptional activation by AP-1.
Unbalanced collagenases/TIMP-1 expression and epithelial apoptosis in experimental lung fibrosis
Authors: Ruiz Victor , Ordóñez Rosa Ma. , Berumen Jaime , Ramírez Remedios , Uhal Bruce , Becerril Carina , Pardo Annie , Selman Moisés
Published: March 2015

In this study, we examined the sequential expression of several matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and growth factors as well as the presence of apoptosis in a model of pulmonary fibrosis induced in rats with paraquat and hyperoxia. Animals showing neither clinical nor morphological changes with this double aggression were classified as “resistant”. Rats were killed at 1, 2, 3, and 6 wk, and lungs were used for collagen content, gene expression by real-time PCR, gelatinolytic activity by zymography, apoptosis by in situ DNA fragmentation, and protein localization by immunohistochemistry. Our results showed a significant decrease of collagenases MMP-8 and MMP-13, with an increase of TIMP-1 and transforming growth factor-β. Immunoreactive TIMP-1 was increased in experimental rats and primarily localized in alveolar macrophages. Expression of gelatinases MMP-2 and MMP-9 mRNAs was not affected, but lung zymography revealed an increase in progelatinase B, progelatinase A, and its active form. Epithelial apoptosis was evident from the first week, whereas at later periods, interstitial cell apoptosis was also noticed. Resistant animals behave as controls. These findings suggest that an imbalance between collagenases and TIMPs, excessive gelatinolytic activity, and epithelial apoptosis participate in the fibrotic response in this experimental model.
Duroquinone reduction during passage through the pulmonary circulation
Authors: Audi Said H. , Bongard Robert D. , Dawson Christopher A. , Siegel David , Roerig David L. , Merker Marilyn P.
Published: March 2015

The lungs can substantially influence the redox status of redox-active plasma constituents. Our objective was to examine aspects of the kinetics and mechanisms that determine pulmonary disposition of redox-active compounds during passage through the pulmonary circulation. Experiments were carried out on rat and mouse lungs with 2,3,5,6-tetramethyl-1,4-benzoquinone [duroquinone (DQ)] as a model amphipathic quinone reductase substrate. We measured DQ and durohydroquinone (DQH2) concentrations in the lung venous effluent after injecting, or while infusing, DQ or DQH2into the pulmonary arterial inflow. The maximum net rates of DQ reduction to DQH2in the rat and mouse lungs were ∼4.9 and 2.5 μmol · min-1· g dry lung wt-1, respectively. The net rate was apparently the result of freely permeating access of DQ and DQH2to tissue sites of redox reactions, dominated by dicumarol-sensitive DQ reduction to DQH2and cyanide-sensitive DQH2reoxidation back to DQ. The dicumarol sensitivity along with immunodetectable expression of NAD(P)H-quinone oxidoreductase 1 (NQO1) in the rat lung tissue suggest cytoplasmic NQO1 as the dominant site of DQ reduction. The effect of cyanide on DQH2oxidation suggests that the dominant site of oxidation is complex III of the mitochondrial electron transport chain. If one envisions DQ as a model compound for examining the disposition of amphipathic NQO1 substrates in the lungs, the results are consistent with a role for lung NQO1 in determining the redox status of such compounds in the circulation. For DQ, the effect is conversion of a redox-cycling, oxygen-activating quinone into a stable hydroquinone.
A p38 MAPK inhibitor, FR-167653, ameliorates murine bleomycin-induced pulmonary fibrosis
Authors: Matsuoka Hiroto , Arai Toru , Mori Masahide , Goya Sho , Kida Hiroshi , Morishita Hiroshi , Fujiwara Hiroshi , Tachibana Isao , Osaki Tadashi , Hayashi Seiji
Published: March 2015

To elucidate the pathophysiology of pulmonary fibrosis, we investigated the involvement of p38 mitogen-activated protein kinase (MAPK), which is one of the major signal transduction pathways of proinflammatory cytokines, in a murine model of bleomycin-induced lung fibrosis. p38 MAPK and its substrate, activating transcription factor (ATF)-2, in bronchoalveolar lavage fluid cells were phosphorylated by intratracheal exposure of bleomycin, and the phosphorylation of ATF-2 was inhibited by subcutaneous administration of a specific inhibitor of p38 MAPK, FR-167653. FR-167653 also inhibited augmented expression of tumor necrosis factor -α, connective tissue growth factor, and apoptosis of lung cells induced by bleomycin administration. Moreover, daily subcutaneous administration of FR-167653 (from 1 day before to 14 days after bleomycin administration) ameliorated pulmonary fibrosis and pulmonary cachexia induced by bleomycin. These findings demonstrated that p38 MAPK is involved in bleomycin-induced pulmonary fibrosis, and its inhibitor, FR-167653, may be a feasible therapeutic agent.
Human surfactant protein B promoter in transgenic mice: temporal, spatial, and stimulus-responsive regulation
Authors: Strayer Marlene , Savani Rashmin C. , Gonzales Linda W. , Zaman Aisha , Cui Zheng , Veszelovszky Edina , Wood Emily , Ho Ye-Shih , Ballard Philip L.
Published: March 2015

Surfactant protein B (SP-B) is a developmentally and hormonally regulated lung protein that is required for normal surfactant function. We generated transgenic mice carrying the human SP-B promoter (−1,039/+431 bp) linked to chloramphenicol acetyltransferase (CAT). CAT activity was high in lung and immunoreactive protein localized to alveolar type II and bronchiolar epithelial cells. In addition, thyroid, trachea, and intestine demonstrated CAT activity, and each of these tissues also expressed low levels of SP-B mRNA. Developmental expression of CAT activity and SP-B mRNA in fetal lung were similar and both increased during explant culture. SP-B mRNA but not CAT activity decreased during culture of adult lung, and both were reduced by transforming growth factor (TGF)-β1. Treatment of adult mice with intratracheal bleomycin caused similar time-dependent decreases in lung SP-B mRNA and CAT activity. These findings indicate that the human SP-B promoter fragment directs tissue- and lung cell-specific transgene expression and contains cis-acting elements involved in regulated expression during development, fetal lung explant culture, and responsiveness to TGF-β and bleomycin-induced lung injury.
Clearance of surfactant lipids by neutrophils and macrophages isolated from the acutely inflamed lung
Authors: Quintero Omar A. , Wright Jo Rae
Published: March 2015

Pulmonary surfactant reduces surface tension at the lung air-liquid interface and defends the host against infection. Several lines of evidence show that surfactant levels are altered in animal models and patients with inflammatory or infectious lung diseases. We tested the hypothesis that cells responding to lung injury alter surfactant levels through increased phospholipid clearance. Acute lung injury was induced by intratracheal administration of lipopolysaccharide (LPS; Escherichia coli026:B6) into rats. LPS exposure resulted in a 12-fold increase in the number of cells isolated by lavage, the majority of which were neutrophils. Isolated macrophages and neutrophils from LPS-treated lungs internalized and degraded lipids in vitro, and LPS injury stimulated uptake by macrophages twofold. We estimate that lipid clearance by lavage cells in LPS-treated lungs could be enhanced 6- to 13-fold with both activated macrophages and increased numbers of neutrophils contributing to the process. These data show that the increased number of cells in the alveolar space after acute lung injury may lead to alterations in surfactant pools via enhanced clearance and degradation of lipids.
Evidence for extracellular superoxide dismutase as a mediator of hemorrhage-induced lung injury
Authors: Bowler Russell P. , Arcaroli John , Abraham Edward , Patel Manisha , Chang Ling-Yi , Crapo James D.
Published: March 2015

Hemorrhage results in excessive production of superoxide that is associated with severe lung injury. We examined whether the superoxide dismutase (SOD) mimetic manganese(III) mesotetrakis (di- N-ethylimidazole) porphyrin (AEOL 10150) could attenuate this lung injury and whether extracellular (EC)-SOD-deficient mice would have increased hemorrhage-induced lung injury. Compared with wild-type mice, EC-SOD-deficient mice had increased lung neutrophil accumulation, a 3.9-fold increase in myeloperoxidase activity, a 1.5-fold increase in nuclear factor (NF)-κB activation, and a 1.5-fold increase in lipid peroxidation 1 h after hemorrhage. Pretreatment with AEOL 10150 did not attenuate neutrophil accumulation but significantly reduced NF-κB activation and lipid peroxidation in both wild-type and EC-SOD-deficient mice. The increase in hemorrhage-induced neutrophil accumulation in the lungs of EC-SOD-deficient mice suggests that EC-SOD might play a role in mediating neutrophil recruitment to the lung.
CD4+T cell-dependent airway mucus production occurs in response to IL-5 expression in lung
Authors: Justice J. Paul , Crosby J. , Borchers M. T. , Tomkinson A. , Lee J. J. , Lee N. A.
Published: March 2015

The potential role of airway interleukin-5 (IL-5) expression in eliciting mucus production was demonstrated in a pulmonary IL-5 transgenic mouse model (NJ.1726) in which naive transgenic mice display comparable levels of airway mucus relative to allergen-sensitized and -challenged wild-type mice. The intrinsic mucus accumulation of NJ.1726 was abolished in compound transgenic-gene knockout mice deficient of either CD4+cells [NJ.1726/CD4(−/−)] or αβ T cell receptor-positive (TCR+) cells [NJ.1726/αβ TCR(−/−)]. In addition, mucus production in naive NJ.1726 was inhibited by >90% after administration of the soluble anti-IL-4 receptor α-subunit antagonist. The loss of mucus production in NJ.1726/CD4(−/−), NJ.1726/αβ TCR(−/−), and anti-IL-4 receptor α-subunit antagonist-treated mice occurred notwithstanding the significant pulmonary eosinophilia and expansion of airway B cells induced by ectopic IL-5 expression. Furthermore, the loss of mucus accumulation occurred in these mice despite elevated levels of airway and peripheral IL-5, indicating that IL-5 does not directly induce goblet cell metaplasia and mucus production. Thus pulmonary expression of IL-5 alone is capable of inducing CD4+T cell-dependent goblet cell metaplasia, apparently mediated by IL-4 receptor α-subunit-ligand interactions, and represents a previously unrecognized novel pathway for augmenting allergen-induced mucus production.
Role of platelet-derived growth factor in vascular remodeling during pulmonary hypertension in the ovine fetus
Authors: Balasubramaniam Vivek , Le Cras Timothy D. , Ivy D. Dunbar , Grover Theresa R. , Kinsella John P. , Abman Steven H.
Published: March 2015

Platelet-derived growth factor (PDGF) is a potent smooth muscle cell mitogen that may contribute to smooth muscle hyperplasia during the development of chronic pulmonary hypertension (PH). We studied changes in PDGFα- and β-receptor and ligand expression in lambs with chronic intrauterine PH induced by partial ligation of the ductus arteriosus (DA) at gestational age 124–128 days (term = 147 days). Western blot analysis performed on whole lung homogenates from PH animals after 8 days of DA ligation showed a twofold increase in PDGFα- and β-receptor proteins compared with age-matched controls ( P < 0.05). Lung PDGF-A and -B mRNA expression did not differ between PH and control animals. We treated PH animals with NX1975, an aptamer that selectively inhibits PDGF-B, by infusion into the left pulmonary artery for 7 days after DA ligation. NX1975 reduced the development of muscular thickening of small pulmonary arteries by 47% ( P < 0.05) and right ventricular hypertrophy (RVH) by 66% ( P < 0.02). Lung PDGFα- and β-receptor expression is increased in perinatal PH, and NX1975 reduces the increase in wall thickness of small pulmonary arteries and RVH in this model. We speculate that PDGF signaling contributes to structural vascular remodeling in perinatal PH and that selective PDGF inhibition may provide a novel therapeutic strategy for the treatment of chronic PH.
MEK-1/2 inhibition reduces branching morphogenesis and causes mesenchymal cell apoptosis in fetal rat lungs
Authors: Kling David E. , Lorenzo Hans K. , Trbovich Alexander M. , Kinane T. Bernard , Donahoe Patricia K. , Schnitzer Jay J.
Published: March 2015

The roles of the mitogen-activated protein (MAP) kinases extracellular signal-regulated kinases-1 and -2 (ERK-1/2) in fetal lung development have not been extensively characterized. To determine if ERK-1/2 signaling plays a role in fetal lung branching morphogenesis, U-0126, an inhibitor of the upstream kinase MAP ERK kinase (MEK), was added to fetal lung explants in vitro. Morphometry as measured by branching, area, perimeter, and complexity were significantly reduced in U-0126-treated lungs. At the same time, U-0126 treatment reduced ERK-1/2, slightly increased p38 kinase, but did not change c-Jun NH2-terminal kinase activities, indicating that U-0126 specifically inhibited the ERK-1/2 enzymes. These changes were associated with increased apoptosis as measured by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and immunofluorescent labeling of anti-active caspase-3 in the mesenchyme of explants after U-0126 treatment compared with the control. Mitosis characterized by immunolocalization of proliferating cell nuclear antigen was found predominantly in the epithelium and was reduced in U-0126-treated explants. Thus U-0126 causes specific inhibition of ERK-1/2 signaling, diminished branching morphogenesis, characterized by increased mesenchymal apoptosis, and decreased epithelial proliferation in fetal lung explants.
Serine protease inhibitors modulate chemotactic cytokine production by human lung fibroblasts in vitro
Authors: Numanami Hiroki , Koyama Sekiya , Sato Esturo , Haniuda Masayuki , Nelson Dan K. , Hoyt Jeffrey C. , Freels Jon L. , Habib Michael P. , Robbins Richard A.
Published: March 2015

Chemotactic chemokines can be released from lung fibroblasts in response to interleukin (IL)-1β and tumor necrosis factor (TNF)-α. An imbalance between proteases and antiproteases has been observed at inflammatory sites, and, therefore, protease inhibitors might modulate fibroblast release of chemotactic cytokines. To test this hypothesis, serine protease inhibitors (FK-706, α1-antitrypsin, or Nα- p-tosyl-l-lysine chloromethyl ketone) were evaluated for their capacity to attenuate the release of neutrophil chemotactic activity (NCA) or monocyte chemotactic activity (MCA) from human fetal lung fibroblasts (HFL-1). Similarly, the release of the chemoattractants IL-8, granulocyte colony-stimulating factor, monocyte chemoattractant protein-1, macrophage colony-stimulating factor, and granulocyte/macrophage colony-stimulating factor, from HFL-1, were evaluated in response to IL-1β and TNF-α. NCA, MCA, and chemotactic cytokines were attenuated by FK-706. However, matrix metalloproteinase inhibitors were without effect, and cysteine protease inhibitors only slightly attenuated chemotactic or cytokine release. These data suggest that IL-1β and TNF-α may stimulate lung fibroblasts to release NCA and MCA by a protease-dependent mechanism and that serine protease inhibitors may attenuate the release.
PU.1 regulation of human alveolar macrophage differentiation requires granulocyte-macrophage colony-stimulating factor
Authors: Bonfield Tracey L. , Raychaudhuri Baisakhi , Malur Anagha , Abraham Susamma , Trapnell Bruce C. , Kavuru Mani S. , Thomassen Mary Jane
Published: March 2015

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is critically implicated in lung homeostasis in the GM-CSF knockout mouse model. These animals develop an isolated lung lesion reminiscent of pulmonary alveolar proteinosis (PAP) seen in humans. The development of the adult form of human alveolar proteinosis is not due to the absence of a GM-CSF gene or receptor defect but to the development of an anti-GM-CSF autoimmunity. The role of GM-CSF in the development of PAP is unknown. Studies in the GM-CSF knockout mouse have shown that lack of PU.1 protein expression in alveolar macrophages is correlated with decreased maturation, differentiation, and surfactant catabolism. This study investigates PU.1 expression in vitro and in vivo in human PAP alveolar macrophages as well as the regulation of PU.1 by GM-CSF. We show for the first time that PU.1 mRNA expression in PAP bronchoalveolar lavage cells is deficient compared with healthy controls. PU.1-dependent terminal differentiation markers CD32 (FCγII), mannose receptor, and macrophage colony-stimulating factor receptor (M-CSFR) are decreased in PAP alveolar macrophages. In vitro studies demonstrate that exogenous GMCSF treatment upregulated PU.1 and M-CSFR gene expression in PAP alveolar macrophages. Finally, in vivo studies showed that PAP patients treated with GM-CSF therapy have higher levels of PU.1 and M-CSFR expression in alveolar macrophages compared with healthy control and PAP patients before GM-CSF therapy. These observations suggest that PU.1 is critical in the terminal differentiation of human alveolar macrophages.
Modulation of sodium transport in fetal alveolar epithelial cells by oxygen and corticosterone
Authors: Thome Ulrich H. , Davis Ian C. , Nguyen Susie Vo , Shelton Brent Jay , Matalon Sadis
Published: March 2015

Regulation of active Na+transport across fetal distal lung epithelial cells (FDLE) by corticosterone (CST), corticotropin-releasing hormone (CRH), and oxygen tension may be crucial for postnatal adaptation. FDLE isolated from 19-day rat fetuses (term: 22 days) were grown on permeable supports to confluent monolayers (duration 3 days) in 2.5, 5, 12, or 20% O2with 5% CO2-balance N2and mounted in Ussing chambers for measurement of short-circuit currents ( Isc). FDLE monolayers grown in 20% O2had significantly higher levels of total Iscand of their amiloride-sensitive ( Iamil) and ouabain-sensitive ( Iouab) components than hypoxic cells. Values (μA/cm2± SE) for 2.5–5% O2and 20% O2were, respectively, Isc5.3 ± 0.2 vs. 8.4 ± 0.3 ( P < 0.001), Iamil3.4 ± 0.2 vs. 4.3 ± 0.2 ( P < 0.01), and Iouab3.4 ± 0.6 vs. 9.1 ± 0.6 ( P < 0.001). Addition of CST but not CRH to the culture medium at any O2concentration increased Iamil. FDLE cells grown at 5% O2expressed significantly lower levels of α-, β-, and γ-epithelial Na+channel (ENaC), and of the α1-Na+-K+-ATPase, as determined by Western blotting. We conclude that higher O2concentrations increased total vectorial Na+transport, and the function of Na+-K+-ATPase and apical amiloride-sensitive Na+conductance, whereas CST only increased ENaC function.
Transcription factor USF2 is developmentally regulated in fetal lung and acts together with USF1 to induceSP-Agene expression
Authors: Gao Erwei , Wang Ying , Alcorn Joseph L. , Mendelson Carole R.
Published: March 2015

Expression of the pulmonary surfactant protein A ( SP-A) gene is lung specific, developmentally regulated, and enhanced by hormones and factors that increase cAMP. We previously identified two E-box-like enhancers termed distal binding element (DBE) and proximal binding element (PBE) in the 5′-flanking region of the rabbit (r) SP-A gene that are essential for cAMP induction of rSP-A promoter activity (Gao E, Alcorn JL, and Mendelson CR. J Biol Chem 268: 19697–19709, 1993). We also found that DBE and PBE serve as binding sites for the basic helix-loop-helix-leucine zipper transcription factor, upstream stimulatory factor-1 (USF1) (Gao E, Wang Y, Alcorn JL, and Mendelson CR. J Biol Chem 272: 23398–23406, 1997). In the present study, PBE was used to screen a rabbit fetal lung cDNA expression library; a cDNA insert encoding the structurally related rabbit upstream stimulatory factor-2 (rUSF2) was isolated. The levels of rUSF2 mRNA reach peak levels in fetal rabbit lung at 28 days of gestation, in concert with the time of maximal induction of SP-A gene transcription. In yeast two-hybrid analysis, rUSF2 was found to preferentially form heterodimers, compared with homodimers, with rUSF1. Binding complexes of nuclear proteins isolated from fetal rabbit lung type II cells with the DBE and PBE were supershifted by anti-rUSF2 antibodies. Binding activity was enriched in nuclear proteins from type II cells compared with fibroblasts. Overexpression of rUSF2 in transfected lung A549 cells increased rSP-A promoter activity and acted synergistically with rUSF1. We suggest that heterodimers of USF2 and USF1 bound to two E-box elements in the SP-A gene 5′-flanking region serve a key role in developmental and hormonal regulation of SP-A gene expression in pulmonary type II cells.
Pathophysiological roles of interleukin-8/CXCL8 in pulmonary diseases
Authors: Mukaida Naofumi
Published: March 2015

Fifteen years have passed since the first description of interleukin (IL)-8/CXCL8 as a potent neutrophil chemotactic factor. Accumulating evidence has demonstrated that various types of cells can produce a large amount of IL-8/CXCL8 in response to a wide variety of stimuli, including proinflammatory cytokines, microbes and their products, and environmental changes such as hypoxia, reperfusion, and hyperoxia. Numerous observations have established IL-8/CXCL8 as a key mediator in neutrophil-mediated acute inflammation due to its potent actions on neutrophils. However, several lines of evidence indicate that IL-8/CXCL8 has a wide range of actions on various types of cells, including lymphocytes, monocytes, endothelial cells, and fibroblasts, besides neutrophils. The discovery of these biological functions suggests that IL-8/CXCL8 has crucial roles in various pathological conditions such as chronic inflammation and cancer. Here, an overview of its protein structure, mechanisms of production, and receptor system will be discussed as well as the pathophysiological roles of IL-8/CXCL8 in various types of lung pathologies.
Absorption of intact albumin across rat alveolar epithelial cell monolayers
Authors: Kim Kwang-Jin , Matsukawa Yasuhisa , Yamahara Hiroshi , Kalra Vijay K. , Lee Vincent H. L. , Crandall Edward D.
Published: March 2015

Transport characteristics of intact albumin were investigated using primary cultured rat alveolar epithelial cell monolayers. The apical-to-basolateral ( ab) flux of intact fluorescein isothiocyanate (FITC)-labeled albumin (F-Alb) is greater than basolateral-to-apical ( ba) flux at the same upstream [F-Alb]. Net absorption of intact F-Alb occurs with half-maximal concentration of ∼1.6 μM and maximal transport rate of ∼0.15 fmol · cm−2· s−1. At 15 and 4°C, both ab and ba F-Alb fluxes are not different from zero, collapsing net absorption. The presence of excess unlabeled albumin (but not other macromolecule species) in either the apical or basolateral fluid significantly reduces both ab and ba unidirectional F-Alb fluxes. Photoaffinity labeling of apical cell membranes revealed an ∼60-kDa protein that exhibits specificity for albumin. These data indicate that net absorption of intact albumin takes place via saturable receptor-mediated transcellular endocytotic processes recognizing albumin, but not other macromolecules, that may play an important role in alveolar homeostasis in the mammalian lung.
Glucocorticoids aggravate hyperoxia-induced lung injury through decreased nuclear factor-κB activity
Authors: Barazzone-Argiroffo Constance , Pagano Alessandra , Juge Cristiana , Métrailler Isabelle , Rochat Anne , Vesin Christian , Donati Yves
Published: March 2015

We previously reported that exposure of mice to hyperoxia is characterized by extensive lung cell necrosis and apoptosis, mild inflammatory response, and elevated circulating levels of corticosterone. Administration of hydroxycortisone acetate during hyperoxia aggravated lung injury. Using adrenalectomized (ADX) and sham-operated (sham) mice, we studied the role of the glucocorticoids in hyperoxia-induced lung injury. Lung damage was attenuated in ADX mice as measured by lung weight and protein and cell content in bronchoalveolar lavage and as seen by light microscopy. Mortality was delayed by 10 h. Nuclear factor-κB (NF-κB) activity was significantly decreased in lungs of sham mice exposed to hyperoxia but was preserved in ADX mice. There was a correlation between NF-κB activity in ADX mice and decreased levels of IκBα. In contrast, activator protein-1 activity increased similarly in both groups of mice. Levels of interleukin-6 (IL-6), a transcriptional target of NF-κB, were higher in bronchoalveolar lavage and serum of ADX than sham mice. However, the protective effect of ADX was not mediated by IL-6, because administration of recombinant human IL-6 to sham mice did not prevent lung damage. These results demonstrate that the adrenal response aggravates alveolar injury and is likely to be mediated by the decrease of NF-κB function involved in cell survival.
Retinoic acid receptor-α regulates pulmonary alveolus formation in mice after, but not during, perinatal period
Authors: De Carlo Massaro Gloria , Massaro Donald , Chambon Pierre
Published: March 2015

The formation of pulmonary alveoli in mice and rats by subdivision of alveolar saccules that constitute the newborn's gas-exchange region ends by approximately postnatal day 14. However, alveoli continue to form after age 14 days until age ∼40 days by means other than septation of the saccules present at birth. With the use of morphometric procedures and retinoic acid receptor (RAR)-α+/+ and RAR-α−/−mice, we now show the volume of individual alveoli (v̄a), the number of alveoli (Na), and alveolar surface area (Sa) are the same in 14-day-old RAR-α+/+ and RAR-α−/− mice. However, at age 50 days, v̄a is larger, and Na and Sa are smaller, in RAR-α−/− than in RAR-α+/+ mice, although total lung volume is the same in both groups. These findings, and prior data showing RAR-β is an endogenous inhibitor of alveolus formation during, but not after, the perinatal period, indicate there are developmental period-specific regulators of alveolus formation and that total lung volume and alveolar dimensions may have different regulators.
Inhibition of apoptosis in pulmonary endothelial cells by altered pH, mitochondrial function, and ATP supply
Authors: Terminella C. , Tollefson K. , Kroczynski J. , Pelli J. , Cutaia M.
Published: March 2015

We investigated the effect of altered extracellular pH, mitochondrial function, and ATP content on development of apoptosis in human pulmonary artery endothelial cells after treatment with staurosporine (STS). STS produced a concentration- and time-dependent increase in caspase-3 activity in pH 7.4 medium that reached a peak at 6 h. The increase in caspase activity was associated with significant DNA fragmentation. Fluorescent imaging of treated monolayers in pH 7.4 medium with Hoechst-33342-propidium iodide demonstrated a large percentage of apoptotic cells (∼40%) with no evidence of necrosis. Caspase activity, DNA fragmentation, and percentage of apoptotic cells were reduced after STS treatment in acidic media (pH 7.0 and 6.6). The Ca2+chelator 1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid-AM inhibited STS-induced apoptosis, whereas the rise in intracellular Ca2+concentration in STS-treated cells in pH 7.4 medium was reduced in pH 7.0 medium. These results suggest that one mechanism for inhibitory effects of acidosis may be a pH-induced alteration in Ca2+signaling. Treatment with STS in the presence of oligomycin (10 μM), an inhibitor of the mitochondrial F0F1-ATPase, in glucose-free media abolished caspase activation and DNA fragmentation in association with severe ATP depletion (∼2% of control cells). Imaging demonstrated a change in the mode of cell death from apoptosis to necrosis under these conditions. This change was linked to the level of ATP depletion, because STS treatment in the absence of glucose or the presence of oligomycin in media with glucose still leads to apoptosis in the presence of only moderate ATP depletion. These results demonstrate that pH, mitochondrial function, and ATP supply are important variables that regulate STS-induced apoptosis in human pulmonary artery endothelial cells.
Role of VEGF-B in the lung during development of chronic hypoxic pulmonary hypertension
Authors: Louzier Vanessa , Raffestin Bernadette , Leroux Aude , Branellec Didier , Caillaud Jean Michel , Levame Micheline , Eddahibi Saadia , Adnot Serge
Published: March 2015

Angiogenic factors exert protective effects on the lung. To investigate the effect of VEGF-B, a factor coexpressed in the lung with VEGF-A, we assessed chronic hypoxic pulmonary hypertension in VEGF-B knockout mice (VEGF-B−/−) and in rats with lung overexpression of VEGF-B induced by adenovirus transfer. No significant difference in pulmonary hemodynamics, right ventricular hypertrophy, distal vessel muscularization, or vascular density was found between VEGF-B−/− and control mice after 3 wk of hypoxia. When overexpressed, VEGF-B167 or VEGF-B186 had protective effects similar to those of human VEGF-A165. Lung endothelial nitric oxide synthase (eNOS) expression was increased by 5 days of hypoxia or VEGF-A adenovirus vector (Ad.VEGF-A) overexpression, whereas VEGF-B167 or VEGF-B186had no effect. With hypoxia or normoxia, the wet-to-dry lung weight ratio was increased 5 days after Ad.VEGF-A administration compared with control (Ad.nul), Ad.VEGF-B167, or Ad.VEGF-B186. Endogenous VEGF-B does not counteract the development of hypoxic pulmonary hypertension. However, when overexpressed in the lung, VEGF-B can be as potent as VEGF-A in attenuating pulmonary hypertension, although it has no effect on eNOS expression or vascular permeability.
Diaphragm defects occur in a CDH hernia model independently of myogenesis and lung formation
Authors: Babiuk Randal P. , Greer John J.
Published: March 2015

Congenital diaphragmatic hernia (CDH) is a significant clinical problem in which a portion of the diaphragmatic musculature fails to form, resulting in a hole in the diaphragm. Here we use animal models of CDH to test two hypotheses regarding the pathogenesis. First, the origin of the defect results from the malformation of the amuscular mesenchymal component of the primordial diaphragm rather than with the process of myogenesis. Second, the defect in the primordial diaphragmatic tissue is not secondary to defects in the developing lung. In c- met(−/−) mouse embryos, in which diaphragm muscle fibers do not form because of a defect in muscle precursor migration, the amuscular substratum forms fully. We show that a defect characteristic of CDH can be induced in the amuscular membrane. In Fgf10(−/−) mouse embryos that have lung agenesis we show that the primordial diaphragm does not depend on signals from lung tissue for proper development and that diaphragmatic malformation is a primary defect in CDH. These data suggest that the pathogenesis of CDH involves mechanisms fundamentally different from previously proposed hypotheses.
Alveolar lipoproteinosis in an acid sphingomyelinase-deficient mouse model of Niemann-Pick disease
Authors: Ikegami Machiko , Dhami Rajwinder , Schuchman Edward H.
Published: March 2015

Types A and B Niemann-Pick disease (NPD) are lipid storage disorders caused by the deficient activity of acid sphingomyelinase (ASM). In humans, NPD is associated with the dysfunction of numerous organs including the lung. Gene targeting of the ASM gene in transgenic mice produced an animal model with features typical of NPD, including pulmonary inflammation. To assess mechanisms by which ASM perturbed lung function, we studied lung morphology, surfactant content, and metabolism in ASM-deficient mice in vivo. Pulmonary inflammation, with increased cellular infiltrates and the accumulation of alveolar material, was associated with alterations in surfactant content. Saturated phosphatidylcholine (SatPC) content was increased twofold, and sphingomyelin content was increased 5.5-fold in lungs of the ASM knockout (ASMKO) mice. Additional sphingomyelin enhanced the sensitivity of surfactant inhibition by plasma proteins. Clearance of SatPC from the lungs of ASMKO mice was decreased. Catabolism of SatPC by alveolar macrophages from the ASMKO mouse was significantly decreased, likely accounting for decreased pulmonary SatPC in vivo. In summary, ASM is required for normal surfactant catabolism by alveolar macrophages in vivo. Alterations in surfactant composition, including increased sphingomyelin content, contributed to the abnormal surfactant function observed in the ASM-deficient mouse.
Retinoic acid attenuates O2-induced inhibition of lung septation
Authors: Veness-Meehan Kathleen A. , Pierce Richard A. , Moats-Staats Billie M. , Stiles Alan D.
Published: March 2015

Exposure of the newborn lung to hyperoxia is associated with impaired alveolar development. In newborn rats exposed to hyperoxia and studied at day 14 of life, retinoic acid (RA) treatment improved survival and increased lung collagen but did not improve alveolar development. To determine whether RA treatment during exposure to hyperoxia results in late improvement in alveolarization, we treated newborn rats with RA and hyperoxia from day 3 to day 14 and then weaned O2to room air by day 20, and studied the animals on day 42. O2-exposed animals had larger mean lung volumes, larger alveoli, and decreased gas-exchange tissue relative to air-exposed animals, whereas RA-treated O2-exposed animals were not statistically different from air-exposed controls. Relative to control animals, elastin staining at day 14 was decreased in hyperoxia-exposed lung independent of RA treatment, and, at day 42, elastin staining was similar in all treatment groups. At day 14, elastin gene expression was similar in all treatment groups, whereas at day 42 lung previously exposed to hyperoxia showed increased elastin signal independent of RA treatment. These results indicate that RA treatment during hyperoxia exposure promotes septal formation without evidence of effects on elastin gene expression after 4 wk of recovery.
Cell-specific involvement of HNF-1β in α1-antitrypsin gene expression in human respiratory epithelial cells
Authors: Hu Chaobin , Perlmutter David H.
Published: March 2015

The synergistic action of hepatocyte nuclear factor (HNF)-1α and HNF-4 plays an important role in expression of the α1-antitrypsin (α1-AT) gene in human hepatic and intestinal epithelial cells. Recent studies have indicated that the α1-AT gene is also expressed in human pulmonary alveolar epithelial cells, a potentially important local site of the lung antiprotease defense. In this study, we examined the possibility that α1-AT gene expression in a human pulmonary epithelial cell line H441 was also directed by the synergistic action of HNF-1α and HNF-4 and/or by the action of HNF-3, which has been shown to play a dominant role in gene expression in H441 cells. The results show that α1-AT gene expression in H441 cells is predominantly driven by HNF-1β, even though HNF-1β has no effect on α1-AT gene expression in human hepatic Hep G2 and human intestinal epithelial Caco-2 cell lines. Expression of α1-AT and HNF-1β was also demonstrated in primary cultures of human respiratory epithelial cells. HNF-4 has no effect on α1-AT gene expression in H441 cells, even when it is cotransfected with HNF-1β or HNF-1α. HNF-3 by itself has little effect on α1-AT gene expression in H441, Hep G2, or Caco-2 cells but tends to have an upregulating effect when cotransfected with HNF-1 in Hep G2 and Caco-2 cells. These results indicate the unique involvement of HNF-1β in α1-AT gene expression in a cell line and primary cultures derived from human respiratory epithelium.
Bleomycin-induced apoptosis of alveolar epithelial cells requires angiotensin synthesis de novo
Authors: Li Xiaopeng , Zhang Huiying , Soledad-Conrad Valerie , Zhuang Jiaju , Uhal Bruce D.
Published: March 2015

Primary cultures of rat type II alveolar epithelial cells (AECs) or human AEC-derived A549 cells, when exposed to bleomycin (Bleo), exhibited concentration-dependent apoptosis detected by altered nuclear morphology, fragmentation of DNA, activation of caspase-3, and net cell loss over time. In both cell culture models, exposure to Bleo caused time-dependent increases in angiotensinogen (ANGEN) mRNA. Antisense oligonucleotides against ANGEN mRNA inhibited Bleo-induced apoptosis of rat AEC or A549 cells by 83 and 84%, respectively ( P < 0.01 and P < 0.05), and prevented Bleo-induced net cell loss. Apoptosis of rat AECs or A549 cells in response to Bleo was inhibited 91% by the ANG-converting enzyme inhibitor captopril or 82%, respectively, by neutralizing antibodies specific for ANG II (both P < 0.01). Antagonists of ANG receptor AT1 (losartan, L-158809, or saralasin), but not an AT2-selective blocker (PD-123319), inhibited Bleo-induced apoptosis of either rat AECs (79%, P < 0.01) or A549 cells (83%, P < 0.01) and also reduced the activity of caspase-3 by 52% ( P < 0.05). These data indicate that Bleo, like FasL or TNF-α, induces transactivation of ANG synthesis de novo that is required for AEC apoptosis. They also support the theory that ANG system antagonists have potential for the blockade of AEC apoptosis in situ.
Adhesion-dependent interactions between eosinophils and cholinergic nerves
Authors: Kingham Paul J. , McLean W. Graham , Sawatzky Deborah A. , Walsh Marie Therese , Costello Richard W.
Published: March 2015

Eosinophils adhere to airway cholinergic nerves and influence nerve cell function by releasing granule proteins onto inhibitory neuronal M2 muscarinic receptors. This study investigated the mechanism of eosinophil degranulation by cholinergic nerves. Eosinophils were cocultured with IMR32 cholinergic nerve cells, and eosinophil peroxidase (EPO) or leukotriene C4 (LTC4) release was measured. Coculture of eosinophils with nerves significantly increased EPO and LTC4 release compared with eosinophils alone. IMR32 cells, like parasympathetic nerves, express the adhesion molecules vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 (ICAM-1). Inhibition of these adhesion molecules alone or in combination significantly inhibited eosinophil degranulation. IMR32 cells also significantly augmented the eosinophil degranulation produced by formyl-Met-Leu-Phe. Eosinophil adhesion to IMR32 cells resulted in an ICAM-1-mediated production of reactive oxygen species via a neuronal NADPH oxidase, inhibition of which significantly inhibited eosinophil degranulation. Additionally, eosinophil adhesion increased the release of ACh from IMR32 cells. These neuroinflammatory cell interactions may be relevant in a variety of inflammatory and neurological conditions.
Anoxia-induced apoptosis occurs through a mitochondria-dependent pathway in lung epithelial cells
Authors: Santore Matthew T. , McClintock David S. , Lee Vivian Y. , Budinger G. R. Scott , Chandel Navdeep S.
Published: March 2015

The intracellular signaling pathways that control O2 deprivation (anoxia)-induced apoptosis have not been fully defined in lung epithelial cells. We show here that the lung epithelial cell line A549 releases cytochrome c and activates caspase-9 followed by DNA fragmentation and plasma membrane breakage in response to anoxia. The antiapoptotic protein Bcl-XL prevented the anoxia-induced cell death by inhibiting the release of cytochrome c and caspase-9 activation. A549 cells devoid of mitochondrial DNA (ρ°-cells) and lacking a functional electron transport chain were resistant to anoxia-induced apoptosis. A549 cells preconditioned with either hypoxia (1.5% O2) or tumor necrosis factor-α, which activated the transcription factors hypoxia-inducible factor-1 or nuclear factor-κB, respectively, did not provide protection from anoxia-induced cell death. These results indicate that A549 cells require a functional electron transport chain and the release of cytochrome c for anoxia-induced apoptosis.
Intracellular redox status affects transplasma membrane electron transport in pulmonary arterial endothelial cells
Authors: Merker Marilyn P. , Bongard Robert D. , Kettenhofen Nicholas J. , Okamoto Yoshiyuki , Dawson Christopher A.
Published: March 2015

Pulmonary arterial endothelial cells possess transplasma membrane electron transport (TPMET) systems that transfer intracellular reducing equivalents to extracellular electron acceptors. As one aspect of determining cellular mechanisms involved in one such TPMET system in pulmonary arterial endothelial cells in culture, glycolysis was inhibited by treatment with iodoacetate (IOA) or by replacing the glucose in the cell medium with 2-deoxy-d-glucose (2-DG). TPMET activity was measured as the rate of reduction of the extracellular electron acceptor polymer toluidine blue O polyacrylamide. Intracellular concentrations of NADH, NAD+, NADPH, and NADP+were determined by high-performance liquid chromatography of KOH cell extracts. IOA decreased TPMET activity to 47% of control activity concomitant with a decrease in the NADH/NAD+ratio to 34% of the control level, without a significant change in the NADPH/NADP+ratio. 2-DG decreased TPMET activity to 53% of control and decreased both NADH/NAD+and NADPH/NADP+ratios to 51% and 55%, respectively, of control levels. When lactate was included in the medium along with the inhibitors, the effects of IOA and 2-DG on both TPMET activity and the NADPH/NADP+ratios were prevented. The results suggest that cellular redox status is a determinant of pulmonary arterial endothelial cell TPMET activity, with TPMET activity more highly correlated with the poise of the NADH/NAD+redox pair.
Bone morphogenetic proteins induce apoptosis in human pulmonary vascular smooth muscle cells
Authors: Zhang Shen , Fantozzi Ivana , Tigno Donna D. , Yi Eunhee S. , Platoshyn Oleksandr , Thistlethwaite Patricia A. , Kriett Jolene M. , Yung Gordon , Rubin Lewis J. , Yuan Jason X.-J.
Published: March 2015

Pulmonary vascular medial hypertrophy in primary pulmonary hypertension (PPH) is mainly caused by increased proliferation and decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Mutations of the bone morphogenetic protein (BMP) receptor type II (BMP-RII) gene have been implicated in patients with familial and sporadic PPH. The objective of this study was to elucidate the apoptotic effects of BMPs on normal human PASMCs and to examine whether BMP-induced effects are altered in PASMCs from PPH patients. Using RT-PCR, we detected six isoforms of BMPs (BMP-1 through -6) and three subunits of BMP receptors (BMP-RIa, -RIb, and -RII) in PASMCs. Treatment of normal PASMCs with BMP-2 or -7 (100-200 nM, 24-48 h) markedly increased the percentage of cells undergoing apoptosis. The BMP-2-mediated apoptosis in normal PASMCs was associated with a transient activation or phosphorylation of Smad1 and a marked downregulation of the antiapoptotic protein Bcl-2. In PASMCs from PPH patients, the BMP-2- or BMP-7-induced apoptosis was significantly inhibited compared with PASMCs from patients with secondary pulmonary hypertension. These results suggest that the antiproliferative effect of BMPs is partially due to induction of PASMC apoptosis, which serves as a critical mechanism to maintain normal cell number in the pulmonary vasculature. Inhibition of BMP-induced PASMC apoptosis in PPH patients may play an important role in the development of pulmonary vascular medial hypertrophy in these patients.
Mechanical stretch induces MMP-2 release and activation in lung endothelium: role of EMMPRIN
Authors: Haseneen Nadia A. , Vaday Gayle G. , Zucker Stanley , Foda Hussein D.
Published: March 2015

High-volume mechanical ventilation leads to ventilator-induced lung injury. This type of lung injury is accompanied by an increased release and activation of matrix metalloproteinases (MMPs). To investigate the mechanism leading to the increased MMP release, we systematically studied the effect of mechanical stretch on human microvascular endothelial cells isolated from the lung. We exposed cells grown on collagen 1 BioFlex plates to sinusoidal cyclic stretch at 0.5 Hz using the Flexercell system with 17–18% elongation of cells. After 4 days of cell stretching, conditioned media and cell lysate were collected and analyzed by gelatin, casein, and reverse zymograms as well as Western blotting. RT-PCR of mRNA extracted from stretched cells was performed. Our results show that 1) cyclic stretch led to increased release and activation of MMP-2 and MMP-1; 2) the activation of MMP-2 was accompanied by an increase in membrane type-1 MMP (MT1-MMP) and inhibited by a hydroxamic acid-derived inhibitor of MMPs (Prinomastat, AG3340); and 3) the MMP-2 release and activation were preceded by an increase in production of extracellular MMP inducer (EMMPRIN). These results suggest that cyclic mechanical stretch leads to MMP-2 activation through an MT1-MMP mechanism. EMMPRIN may play an important role in the release and activation of MMPs during lung injury.
Release of biologically active TGF-β1 by alveolar epithelial cells results in pulmonary fibrosis
Authors: Xu Ying Dong , Hua Jiesong , Mui Alice , O'Connor Robert , Grotendorst Gary , Khalil Nasreen
Published: March 2015

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal fibrotic lung disease. Transforming growth factor (TGF)-β1 is present in a biologically active conformation in the epithelial cells lining lesions with advanced IPF. To determine the role of aberrant expression of biologically active TGF-β1 by alveolar epithelial cells (AECs), the AECs of explanted normal rat lungs were transfected with the TGF-β1 gene using the retrovirus pMX-L-s223,225-TGF-β1. In situ hybridization using a digoxigenin-labeled cDNA of the puromycin resistance gene contained in the pMX demonstrated that pMX-L-s233,225-TGF-β1 was selectively transfected into AECs of the explants. Conditioned media overlying explants obtained 7 days after being treated with pMX-L-s223,225-TGF-β1 contained 14.5 ± 3.15 pg/ml of active TGF-β1. With the use of Masson's trichrome staining of explant sections obtained 14 days after transfection, there were lesions similar to those in IPF, characterized by type II AEC hyperplasia, interstitial thickening, extensive increase in interstitial and subepithelial collagen, an increase in the number of fibroblasts, and areas resembling fibroblast buds. Collagens I, III, IV, and V and fibronectin were increased in explants treated with pMX-L-s223,225-TGF-β1. The findings in the current study suggest that IPF may be a disorder of epithelial cells and not inflammatory cells.