elastin and Hyperoxia

Hyperoxia at resuscitation increases oxidative stress, and even brief exposure to high oxygen concentrations during stabilization may trigger organ injury with adverse long-term outcomes in premature infants. We studied the long-term effects of short-term perinatal oxygen exposure on cell cycle gene expression and lung growth in adult mice.. We randomized mice litters at birth to 21, 40, or 100%O. The principal component analysis demonstrated a high degree of correlation for cell cycle gene expression among the three oxygen groups. Lung elastin was significantly lower in the 100%O. Short-term exposure to high oxygen concentrations lead to subtle changes in lung development that may affect alveolarization. The changes are related explicitly to secondary crest formation that may result in alteration in lung elastin. Resuscitation with high oxygen concentrations may have a significant impact on lung development and long-term outcomes such as BPD in premature infants.

Topics: Animals; Elastin; Female; Hyperoxia; Lung; Mice; Oxidative Stress; Oxygen; Pregnancy

The incidence and mortality rates of bronchopulmonary dysplasia (BPD) remain very high. Therefore, novel therapies are imminently needed to improve the outcome of this disease. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) show promising therapeutic effects on oxygen-induced model of BPD. In our experiment, UC-MSCs were intratracheally delivered into the newborn rats exposed to hyperoxia, a well-established BPD model. This study demonstrated that UC-MSCs reduce elastin expression stimulated by 90% O

Topics: Animals; Animals, Newborn; Bronchopulmonary Dysplasia; Cells, Cultured; Cord Blood Stem Cell Transplantation; Elastin; Humans; Hyperbaric Oxygenation; Hyperoxia; Lung; Lung Injury; Mesenchymal Stem Cell Transplantation; Rats; Rats, Sprague-Dawley; Treatment Outcome

Antenatal inflammation and preterm birth are associated with the development of airway diseases such as wheezing and asthma. Utilizing a newborn mouse model, we assessed the effects of maternal inflammation and postnatal hyperoxia on the neonatal airway.. Pregnant C57/Bl6 dams were injected with lipopolysaccharide (LPS) or saline on embryonic day 16. Offspring were placed in room air or hyperoxia (50% O2) for 7 d and then returned to normoxia. Airway mechanics, histology, and laser capture micro-dissection (LCM) were performed.. At postnatal day 21, maternal LPS- and 50% O2-exposed pups exhibited increased resistance and decreased compliance compared to 21% O2 pups; however their effects were not synergistic. LPS and hyperoxia each increased the thickness of airway smooth muscle (ASM), but not the airway epithelial layer. Structural changes were largely limited to the conducting airways. Upregulation of inflammatory markers in the lung was observed at birth. LCM revealed increased collagen-3, transforming growth factor β, and connective tissue growth factor expression with LPS and hyperoxia within the ASM layer.. These novel studies provide functional, structural, and molecular evidence that antenatal inflammation is detrimental to the developing airway. Exposure to moderate hyperoxia does not exacerbate LPS effects on the airway.

Topics: Airway Remodeling; Animals; Animals, Newborn; Body Weight; Collagen; Disease Models, Animal; Dose-Response Relationship, Drug; Elastin; Female; Hyperoxia; Inflammation; Lipopolysaccharides; Lung; Methacholine Chloride; Mice; Mice, Inbred C57BL; Oxygen; Pregnancy; Pregnancy, Animal; Respiration; Respiratory System

Exposure of neonatal mice to hyperoxia results in pulmonary vascular remodeling and aberrant phosphodiesterase type 5 (PDE5) signaling. Although glucocorticoids are frequently utilized in the NICU, little is known about their effects on the developing pulmonary vasculature and on PDE5. We sought to determine the effects of hydrocortisone (HC) on pulmonary vascular development and on PDE5 in a neonatal mouse model of hyperoxic lung injury.. C57BL/6 mice were placed in 21% O2 or 75% O2 within 24 h of birth and received HC (1, 5, or 10 mg/kg subcutaneously every other day) or vehicle. At 14 d, right ventricular hypertrophy (RVH), medial wall thickness (MWT), lung morphometry, and pulmonary artery (PA) PDE5 activity were assessed. PDE5 activity was measured in isolated pulmonary artery smooth muscle cells exposed to 21 or 95% O2 ± 100 nmol/l HC for 24 h.. Hyperoxia resulted in alveolar simplification, RVH, increased MWT, and increased PA PDE5 activity. HC decreased hyperoxia-induced RVH and attenuated MWT. HC had dose-dependent effects on alveolar simplification. HC decreased hyperoxia-induced PDE5 activity both in vivo and in vitro.. HC decreases hyperoxia-induced pulmonary vascular remodeling and attenuates PDE5 activity. These findings suggest that HC may protect against hyperoxic injury in the developing pulmonary vasculature.

Topics: Animals; Cyclic Nucleotide Phosphodiesterases, Type 5; Dose-Response Relationship, Drug; Elastin; Glucocorticoids; Humans; Hydrocortisone; Hyperoxia; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Lung; Lung Injury; Mice; Mice, Inbred C57BL; Pulmonary Alveoli; Pulmonary Artery; Signal Transduction

Although high-mobility group box-1 (HMGB1) levels in tracheal aspirates are associated with the pathological features of bronchopulmonary dysplasia (BPD), the role of HMGB1 in the terminal stage of abnormal alveologenesis has not yet been understood. In this study, we addressed the role of HMGB1 in the elastogenesis disruption in the lungs of newborn mice with BPD. We found that elevations of whole lung HMGB1 level were associated with impaired alveolar development and aberrant elastin production in 85% O2-exposed lungs. HMGB1 neutralizing antibody attenuated the structural disintegration developed in hyperoxia-damaged lungs. Furthermore, HMGB1 inhibition rescued the neutrophil influx in hyperoxia-injured lung and partially abolished the mRNA level of the proinflammatory mediators, interleukin (IL)-1β and transforming growth factor (TGF)-β1. These data suggested that pulmonary HMGB1 plays an important role in the disruption of elastogenesis in the terminal stage of lung development through reduced pulmonary inflammatory response.

Topics: Animals; Animals, Newborn; Antibodies, Neutralizing; Bronchopulmonary Dysplasia; Disease Models, Animal; Elastin; Gene Expression Regulation, Developmental; HMGB1 Protein; Humans; Hyperoxia; Interleukin-1beta; Mice; Mice, Inbred C57BL; Neutrophils; Oxygen; Pulmonary Alveoli; Transforming Growth Factor beta1

Preterm infants are at high risk for long-term abnormalities in cardiopulmonary function. Our objectives were to determine the long-term effects of hypoxia or hyperoxia on cardiopulmonary development and function in an immature animal model. Newborn C57BL/6 mice were exposed to air, hypoxia (12% oxygen), or hyperoxia (85% oxygen) from Postnatal Day 2-14, and then returned to air for 10 weeks (n = 2 litters per condition; > 10/group). Echocardiography, blood pressure, lung function, and lung development were evaluated at 12-14 weeks of age. Lungs from hyperoxia- or hypoxia-exposed mice were larger and more compliant (compliance: air, 0.034 ± 0.001 ml/cm H2O; hypoxia, 0.049 ± 0.002 ml/cm H2O; hyperoxia, 0.053 ± 0.002 ml/cm H2O; P < 0.001 air versus others). Increased airway reactivity, reduced bronchial M2 receptor staining, and increased bronchial α-smooth muscle actin content were noted in hyperoxia-exposed mice (maximal total lung resistance with methacholine: air, 1.89 ± 0.17 cm H2O ⋅ s/ml; hypoxia, 1.52 ± 0.34 cm H2O ⋅ s/ml; hyperoxia, 4.19 ± 0.77 cm H2O ⋅ s/ml; P < 0.004 air versus hyperoxia). Hyperoxia- or hypoxia-exposed mice had larger and fewer alveoli (mean linear intercept: air, 40.2 ± 0. 0.8 μm; hypoxia, 76.4 ± 2.4 μm; hyperoxia, 95.6 ± 4.6 μm; P < 0.001 air versus others; radial alveolar count [n]: air, 11.1 ± 0.4; hypoxia, 5.7 ± 0.3; hyperoxia, 5.6 ± 0.3; P < 0.001 air versus others). Hyperoxia-exposed adult mice had left ventricular dysfunction without systemic hypertension. In conclusion, exposure of newborn mice to hyperoxia or hypoxia leads to cardiopulmonary abnormalities in adult life, similar to that described in ex-preterm infants. This animal model may help to identify underlying mechanisms and to develop therapeutic strategies for pulmonary morbidity in former preterm infants.

Topics: Actins; Age Factors; Animals; Animals, Newborn; Blood Pressure; Bronchial Hyperreactivity; Bronchoconstriction; Cardiovascular System; Collagen; Disease Models, Animal; Elastin; Hyperoxia; Hypoxia; Lung; Lung Compliance; Mice, Inbred C57BL; Receptor, Muscarinic M2; Time Factors; Ventricular Dysfunction, Left; Ventricular Function, Left

Excessive localization of elastin from septal tips to alveolar walls is a key feature of bronchopulmonary dysplasia (BPD). The abnormal accumulation of lung elastin, involving the structural and functional interaction of a series of proteins, remains poorly understood. To further investigate the mechanisms accounting for the abnormal accumulation of elastin in the lungs of newborn mice with BPD, we evaluate elastin distribution and its interaction with proteins involved in its aberrant localization, such as integrin αv, fibulin-5 and transforming growth factor β1 (TGF-β1), in lungs of newborn mice exposed to 60% O2 for 21 days. Lung histology revealed aberrant elastin production and impaired lung septation in O2-exposed lungs, while tropoelastin, integrin αv, fibulin-1, fibulin-2 and fibulin-4 gene expression were elevated. Dual staining image analysis of lung sections revealed that co-localization of integrin αv and elastin increased following O2 exposure with elastin distributed throughout the walls of air spaces rather than at septal tips. Furthermore, integrin αv appeared to be induced initially. Concurrently, increased fibulin-5 and TGF-β1 (which may regulate elastic fiber assembly) expression was detected, which may explain the altered lung elastin deposition and defective septation that are observed during BPD. These data support the hypothesis that excessive and aberrant αv integrin expression was initially induced by hyperoxia; αv integrin then interacted with and recruited elastin. These alterations were accompanied by fibulin-5 deposition and TGF-β1 activation, which may impede normal matrix remodeling, thereby contributing to the pathological pulmonary features of BPD.

Topics: Animals; Animals, Newborn; Elastin; Extracellular Matrix Proteins; Gene Expression Profiling; Hyperoxia; Integrin alphaV; Lung; Mice, Inbred C57BL; Oxygen; Pulmonary Alveoli; Recombinant Proteins; Time Factors; Transforming Growth Factor beta1; Tropoelastin

Maturation of the lung extracellular matrix (ECM) plays an important role in the formation of alveolar gas exchange units. A key step in ECM maturation is cross-linking of collagen and elastin, which imparts stability and functionality to the ECM. During aberrant late lung development in bronchopulmonary dysplasia (BPD) patients and animal models of BPD, alveolarization is blocked, and the function of ECM cross-linking enzymes is deregulated, suggesting that perturbed ECM cross-linking may impact alveolarization. In a hyperoxia (85% O2)-based mouse model of BPD, blunted alveolarization was accompanied by alterations to lung collagen and elastin levels and cross-linking. Total collagen levels were increased (by 63%). The abundance of dihydroxylysinonorleucine collagen cross-links and the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio were increased by 11 and 18%, respectively, suggestive of a profibrotic state. In contrast, insoluble elastin levels and the abundance of the elastin cross-links desmosine and isodesmosine in insoluble elastin were decreased by 35, 30, and 21%, respectively. The lung collagen-to-elastin ratio was threefold increased. Treatment of hyperoxia-exposed newborn mice with the lysyl oxidase inhibitor β-aminopropionitrile partially restored normal collagen levels, normalized the dihydroxylysinonorleucine-to-hydroxylysinonorleucine ratio, partially normalized desmosine and isodesmosine cross-links in insoluble elastin, and partially restored elastin foci structure in the developing septa. However, β-aminopropionitrile administration concomitant with hyperoxia exposure did not improve alveolarization, evident from unchanged alveolar surface area and alveoli number, and worsened septal thickening (increased by 12%). These data demonstrate that collagen and elastin cross-linking are perturbed during the arrested alveolarization of developing mouse lungs exposed to hyperoxia.

Topics: Aminopropionitrile; Animals; Bronchopulmonary Dysplasia; Collagen; Elastin; Extracellular Matrix; Hyperoxia; Lung; Mice; Protein Processing, Post-Translational; Protein-Lysine 6-Oxidase

IL-1β creates persistent pulmonary inflammation accompanied by elevated transforming growth factor β (TGF-β levels and is associated with abnormal elastogenesis, which is observed in bronchopulmonary dysplasia (BPD). Although progress has been made in this field, the mechanisms underlying this process remain only partially understood.. We assessed aberrant elastin localization-associated signaling in mouse pups exposed to 85% O2 treated with either IL-1Ra or 1D11, using morphometric analyses, quantitative RT-PCR, immunostaining, and ELISA. We also evaluated the derivation of elastin-producing cells using dual marker tracking. The regulatory mechanisms of IL-1β were investigated in vitro in lung epithelial and mesenchymal cells.. Elevated levels of IL-1β, αvβ6 and TGF-β1 were each associated with aberrant elastin production in O2-exposed lungs. IL-1Ra abolished TGF-β1 activation and αvβ6 upregulation, which occurred as a result of exposure to hyperoxia, whereas 1D11 had no discernible effect on the expression of either αvβ6 or IL-1β even following O2-exposure, suggesting that IL-1β was initially induced. Additionally, double staining revealed the presence of epithelium-derived elastin-producing cells, which was confirmed via in vitro IL-1β stress-induced epithelial-mesenchymal transformation (EMT) morphological and molecular marker changes, which may explain the altered lung elastin deposition and defective septation observed in BPD.. These data support the hypothesis that IL-1β was initially induced by hyperoxia; αvβ6 subsequently interacted with and activated TGF-β1, acting as an epithelial/mesenchymal signaling molecule that contributed to excessive alveolar elastogenesis, the primary pathological feature of BPD.

Topics: Animals; Antigens, Neoplasm; Cell Line; Down-Regulation; Elastin; Epithelial Cells; Epithelial-Mesenchymal Transition; Fibroblasts; Gene Expression Profiling; Gene Expression Regulation; Hyperoxia; Integrins; Interleukin 1 Receptor Antagonist Protein; Interleukin-1beta; Mice, Inbred C57BL; Morphogenesis; Phenotype; Pulmonary Alveoli; Rats; Signal Transduction; Smad Proteins; Transforming Growth Factor beta

Curcumin, a potent anti-inflammatory and antioxidant agent, modulates peroxisome proliferator-activated receptor-γ signaling, a key molecule in the etiology of bronchopulmonary dysplasia (BPD). We have previously shown curcumin's acute protection against neonatal hyperoxia-induced lung injury. However, its longer-term protection against BPD is not known. Hypothesizing that concurrent treatment with curcumin protects the developing lung against hyperoxia-induced lung injury long-term, we determined if curcumin protects against hyperoxic neonatal rat lung injury for the first 5 days of life, as determined at postnatal day (PND) 21. One-day-old rat pups were exposed to either 21 or 95% O₂ for 5 days with or without curcumin treatment (5 mg/kg) administered intraperitoneally one time daily, following which the pups grew up to PND21 in room air. At PND21 lung development was determined, including gross and cellular structural and functional effects, and molecular mediators of inflammatory injury. To gain mechanistic insights, embryonic day 19 fetal rat lung fibroblasts were examined for markers of apoptosis and MAP kinase activation following in vitro exposure to hyperoxia for 24 h in the presence or absence of curcumin (5 μM). Curcumin effectively blocked hyperoxia-induced lung injury based on systematic analysis of markers for lung injury (apoptosis, Bcl-2/Bax, collagen III, fibronectin, vimentin, calponin, and elastin-related genes) and lung morphology (radial alveolar count and alveolar septal thickness). Mechanistically, curcumin prevented the hyperoxia-induced increases in cleaved caspase-3 and the phosphorylation of Erk1/2. Molecular effects of curcumin, both structural and cytoprotective, suggest that its actions against hyperoxia-induced lung injury are mediated via Erk1/2 activation and that it is a potential intervention against BPD.

Topics: Animals; Apoptosis; Biomarkers; Cell Proliferation; Curcumin; Elastin; Enzyme Activation; Female; Fibroblasts; Fibronectins; Gene Expression Regulation; Hyperoxia; Lung; MAP Kinase Signaling System; Mesoderm; Protective Agents; Pulmonary Alveoli; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta; Triglycerides

Matrix metalloprotease-9 (MMP-9) is increased in lung injury following hyperoxia exposure in neonatal mice, in association with impaired alveolar development. We studied the role of MMP-9 in the mechanism of hyperoxia-induced functional and histological changes in neonatal mouse lung. Reduced alveolarization with remodeling of ECM is a major morbidity component of oxidant injury in developing lung. MMP-9 mediates oxidant injury in developing lung causing altered lung remodeling. Five-day-old neonatal wild-type (WT) and MMP-9 (-/-) mice were exposed to hyperoxia for 8 days. The lungs were inflation fixed, and sections were examined for morphometry. The mean linear intercept and alveolar counts were evaluated. Immunohistochemistry for MMP-9 and elastin was performed. MMP-2, MMP-9, type I collagen, and tropoelastin were measured by Western blot analysis. Lung quasistatic compliance was studied in anaesthetized mice. MMP-2 and MMP-9 were significantly increased in lungs of WT mice exposed to hyperoxia compared with controls. Immunohistochemistry showed an increase in MMP-9 in mesenchyme and alveolar epithelium of hyperoxic lungs. The lungs of hyperoxia-exposed WT mice had less gas exchange surface area and were less compliant compared with room air-exposed WT and hyperoxia-exposed MMP-9 (-/-) mice. Type I collagen and tropoelastin were increased in hyperoxia-exposed WT with aberrant elastin staining. These changes were ameliorated in hyperoxia-exposed MMP-9 (-/-) mice. MMP-9 plays an important role in the structural changes consequent to oxygen-induced lung injury. Blocking MMP-9 activity may lead to novel therapeutic approaches in preventing bronchopulmonary dysplasia.

Topics: Animals; Animals, Newborn; Body Weight; Elastin; Hyperoxia; Lung; Matrix Metalloproteinase 9; Mice; Pulmonary Alveoli; Respiratory Distress Syndrome; Respiratory Function Tests

Pulmonary injury is associated with the disruption of alveologenesis in the developing lung and causes bronchopulmonary dysplasia (BPD) in prematurely born infants. Transforming growth factor (TGF)-beta is an important regulator of cellular differentiation and early lung development, and its levels are increased in newborn lung injury. Although overexpression of TGF-beta in the lungs of newborn animals causes pathological features that are consistent with BPD, the role of endogenous TGF-beta in the inhibition of the terminal stage of lung development is incompletely understood. In this investigation, the hypothesis that O(2)-induced injury of the maturing lung is associated with TGF-beta-mediated disruption of alveologenesis and microvascular development was tested using a murine model of BPD. Here we report that treatment of developing mouse lungs with TGF-beta-neutralizing antibodies attenuates the increase in pulmonary cell phospho-Smad2 nuclear localization, which is indicative of augmented TGF-beta signaling, associated with pulmonary injury induced by chronic inhalation of 85% oxygen. Importantly, the neutralization of the abnormal TGF-beta activity improves quantitative morphometric indicators of alveologenesis, extracellular matrix assembly, and microvascular development in the injured developing lung. Furthermore, exposure to anti-TGF-beta antibodies is associated with improved somatic growth in hyperoxic mouse pups and not with an increase in pulmonary inflammation. These studies indicate that excessive pulmonary TGF-beta signaling in the injured newborn lung has an important role in the disruption of the terminal stage of lung development. In addition, they suggest that anti-TGF-beta antibodies may be an effective therapy for preventing some important developmental diseases of the newborn lung.

Topics: Animals; Animals, Newborn; Antibodies; Cell Nucleus; Elastin; Female; Hyperoxia; Lung Diseases; Mice; Mice, Inbred C57BL; Neovascularization, Physiologic; Neutralization Tests; Phosphoproteins; Protein Isoforms; Protein Transport; Pulmonary Alveoli; Smad2 Protein; Transforming Growth Factor beta

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that adversely affects long-term pulmonary function as well as neurodevelopmental outcomes of preterm infants. Elastolytic proteases have been implicated in the pathogenesis of BPD. Cathepsin S (cat S) is a cysteine protease with potent elastolytic activity. Increased levels and activity of cat S have been detected in a baboon model of BPD.. To investigate whether deficiency of cat S alters the course of hyperoxia-induced neonatal lung injury in mice.. Newborn wild-type and cat S-deficient mice were exposed to 80% oxygen for 14 days. Histologic and morphometric analysis were performed and bronchoalveolar lavage protein and cells were analyzed. Lung elastin was assessed by real-time polymerase chain reaction, in situ hybridization, desmosine analysis, and Hart's stain. Distribution of myofibroblasts was analyzed by immunofluorescence. Hydroxyproline content of lung tissues was measured.. Hyperoxia-exposed cat S-deficient mice were protected from growth restriction and had improved alveolarization, decreased septal wall thickness, lower number of macrophages, and lower protein concentration in bronchoalveolar lavage fluid. alpha-Smooth muscle actin-expressing myofibroblasts accounted for at least some of the increased interstitial cellularity in hyperoxia-exposed mouse lungs and were significantly less in cat S-deficient lungs. Lung hydroxyproline content was increased in hyperoxia-exposed wild-type, but not in cat S-deficient lungs. Desmosine content was significantly reduced in both genotypes with hyperoxia.. Cathepsin S deficiency improves alveolarization, and attenuates macrophage influx and fibroproliferative changes in hyperoxia-induced neonatal mouse lung injury.

Topics: Animals; Animals, Newborn; Bronchoalveolar Lavage Fluid; Bronchopulmonary Dysplasia; Cathepsins; Collagen; Desmosine; Disease Models, Animal; Elastin; Humans; Hydroxyproline; Hyperoxia; Infant, Newborn; Lung; Lung Injury; Macrophages, Alveolar; Mice; Proteins; Pulmonary Alveoli; RNA, Messenger

Exposure of newborn rats to hyperoxia impairs alveolarization. Nitric oxide (NO) may prevent this evolution. Angiogenesis and factors involved in this process, but also other growth factors (GFs) involved in alveolar development, are likely potential therapeutic targets for NO. We studied the effects of the NO donor, [Z]-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)aminio]diazen-1-ium-1, 2-diolate, also termed DETANONOate (D-NO), on hyperoxia-induced changes in key regulatory factors of alveolar development in neonatal rats, and its possible preventive effect on the physiologic consequences of hyperoxia. Newborn rat pups were randomized at birth to hyperoxia (> 95% O2) or room air exposure for 6 or 10 d, while receiving D-NO or its diluent. On Day 6, several GFs and their receptors were studied at pre- and/or post-translational levels. Elastin transcript determination on Day 6, and elastin deposition in tissue and morphometric analysis of the lungs on Day 10, were also performed. Hyperoxia decreased the expression of vascular endothelial growth factor (VEGF) receptor (VEGFR) 2, fibroblast growth factor (FGF)-18, and FGF receptors (FGFRs) FGFR3 and FGFR4, increased mortality, and impaired alveolarization and capillary growth. D-NO treatment of hyperoxia-exposed pups restored the expression level of FGF18 and FGFR4, induced an increase of both VEGF mRNA and protein, enhanced elastin expression, and partially restored elastin deposition in alveolar walls. Although, under the present conditions, D-NO failed to prevent the physiologic consequences of hyperoxia in terms of survival and lung alveolarization, our findings demonstrate molecular effects of NO on GFs involved in alveolar development that may have contributed to the protective effects previously reported for NO.

Topics: Animals; Animals, Newborn; Elastin; Fibroblast Growth Factors; Gene Expression Regulation, Developmental; Hyperoxia; Lung; Nitric Oxide Donors; Nitroso Compounds; Platelet-Derived Growth Factor; Rats; Rats, Sprague-Dawley; Receptors, Fibroblast Growth Factor; RNA, Messenger; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2

Fibulin-5, previously known as DANCE and EVEC, is a secreted extracellular matrix protein that functions as a scaffold for elastin fiber assembly and as a ligand for integrins alphavbeta3, alphavbeta5, and alpha9beta1. Fibulin-5 is developmentally regulated in the lung, and lung air space enlargement develops in mice deficient in fibulin-5. Fibulin-5 is also induced in adult lung following lung injury by hyperoxia. To further examine the role of fibulin-5 during repair of lung injury, we assessed fibulin-5 expression during elastase-induced emphysema in C57/b mice. Mice were treated with either saline or elastase via the trachea, and the lung was examined 20 days after treatment. Fibulin-5 mRNA was induced almost fourfold, whereas elastin mRNA was minimally elevated. Immunohistochemistry studies showed that fibulin-5 was induced in cells within the alveolar wall following elastase treatment. Western analysis demonstrates that fibulin-5 was strongly expressed in isolated primary lung interstitial fibroblasts. Fibulin-5 protein was localized to the fibroblast cell layer in culture, and brief elastase treatment degraded the protein. Intact fibulin-5 did not accumulate in the culture media. Treatment of fibroblasts with the proinflammatory cytokine interleukin-1beta abolished fibulin-5 mRNA expression. Our results indicate that fibulin-5 is coordinately expressed and regulated with elastin in lung fibroblasts and may serve a key role during lung injury and repair.

Topics: Amino Acid Sequence; Animals; Cells, Cultured; Elastin; Extracellular Matrix Proteins; Fibroblasts; Gene Expression Regulation; Hyperoxia; Integrins; Ligands; Lung; Lung Injury; Mice; Mice, Inbred C57BL; Mice, Knockout; Pancreatic Elastase; Peptide Fragments; Rats; Recombinant Proteins; RNA, Messenger; Transcription, Genetic