Mechanical ventilation uncouples synthesis and assembly of elastin and increases apoptosis in lungs of newborn mice.

2008 ◽  
Vol 294 (1) ◽  
pp. L3-L14 ◽  
Author(s):  
Richard D. Bland ◽  
Robert Ertsey ◽  
Lucia M. Mokres ◽  
Liwen Xu ◽  
Berit E. Jacobson ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lysyl Oxidase ◽  
Prolonged Mechanical Ventilation ◽  
Elastic Fiber ◽  
Elastase Activity ◽  
Fiber Density ◽  
Newborn Mice ◽  
Fiber Assembly ◽  
Expression Of Genes ◽  
Fibrillin 1

Prolonged mechanical ventilation (MV) with O2-rich gas inhibits lung growth and causes excess, disordered accumulation of lung elastin in preterm infants, often resulting in chronic lung disease (CLD). Using newborn mice, in which alveolarization occurs postnatally, we designed studies to determine how MV with either 40% O2or air might lead to dysregulated elastin production and impaired lung septation. MV of newborn mice for 8 h with either 40% O2or air increased lung mRNA for tropoelastin and lysyl oxidase, relative to unventilated controls, without increasing lung expression of genes that regulate elastic fiber assembly (lysyl oxidase-like-1, fibrillin-1, fibrillin-2, fibulin-5, emilin-1). Serine elastase activity in lung increased fourfold after MV with 40% O2, but not with air. We then extended MV with 40% O2to 24 h and found that lung content of tropoelastin protein doubled, whereas lung content of elastin assembly proteins did not change (lysyl oxidases, fibrillins) or decreased (fibulin-5, emilin-1). Quantitative image analysis of lung sections showed that elastic fiber density increased by 50% after MV for 24 h, with elastin distributed throughout the walls of air spaces, rather than at septal tips, as in control lungs. Dysregulation of elastin was associated with a threefold increase in lung cell apoptosis (TUNEL and caspase-3 assays), which might account for the increased air space size previously reported in this model. Our findings of increased elastin synthesis, coupled with increased elastase activity and reduced lung abundance of proteins that regulate elastic fiber assembly, could explain altered lung elastin deposition, increased apoptosis, and defective septation, as observed in CLD.

scholarly journals Lung matrix and vascular remodeling in mechanically ventilated elastin haploinsufficient newborn mice

2015 ◽  
Vol 308 (5) ◽  
pp. L464-L478 ◽  
Author(s):  
Anne Hilgendorff ◽  
Kakoli Parai ◽  
Robert Ertsey ◽  
Edwin Navarro ◽  
Noopur Jain ◽  
...  
Keyword(s):  
Lysyl Oxidase ◽  
Elastic Fiber ◽  
Growth Arrest ◽  
Subsequent Development ◽  
Fiber Formation ◽  
Lung Growth ◽  
Elastase Activity ◽  
Newborn Mice ◽  
Fibrillin 1 ◽  
Lung Capillaries

Elastin plays a pivotal role in lung development. We therefore queried if elastin haploinsufficient newborn mice ( Eln+/−) would exhibit abnormal lung structure and function related to modified extracellular matrix (ECM) composition. Because mechanical ventilation (MV) has been linked to dysregulated elastic fiber formation in the newborn lung, we also asked if elastin haploinsufficiency would accentuate lung growth arrest seen after prolonged MV of neonatal mice. We studied 5-day-old wild-type ( Eln+/+) and Eln+/− littermates at baseline and after MV with air for 8–24 h. Lungs of unventilated Eln+/− mice contained ∼50% less elastin and ∼100% more collagen-1 and lysyl oxidase compared with Eln+/+ pups. Eln+/− lungs contained fewer capillaries than Eln+/+ lungs, without discernible differences in alveolar structure. In response to MV, lung tropoelastin and elastase activity increased in Eln+/+ neonates, whereas tropoelastin decreased and elastase activity was unchanged in Eln+/− mice. Fibrillin-1 protein increased in lungs of both groups during MV, more in Eln+/− than in Eln+/+ pups. In both groups, MV caused capillary loss, with larger and fewer alveoli compared with unventilated controls. Respiratory system elastance, which was less in unventilated Eln+/− compared with Eln+/+ mice, was similar in both groups after MV. These results suggest that elastin haploinsufficiency adversely impacts pulmonary angiogenesis and that MV dysregulates elastic fiber integrity, with further loss of lung capillaries, lung growth arrest, and impaired respiratory function in both Eln+/+ and Eln+/− mice. Paucity of lung capillaries in Eln+/− newborns might help explain subsequent development of pulmonary hypertension previously reported in adult Eln+/− mice.

Mechanical ventilation with 40% oxygen reduces pulmonary expression of genes that regulate lung development and impairs alveolar septation in newborn mice

2007 ◽  
Vol 293 (5) ◽  
pp. L1099-L1110 ◽  
Author(s):  
Richard D. Bland ◽  
Lucia M. Mokres ◽  
Robert Ertsey ◽  
Berit E. Jacobson ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Development ◽  
Structural Changes ◽  
Structural Defects ◽  
Normal Lung ◽  
Myeloperoxidase Activity ◽  
Newborn Mice ◽  
Tenascin C ◽  
Expression Of Genes ◽  
Old Mice

Mechanical ventilation with 40% oxygen reduces pulmonary expression of genes that regulate lung development and impairs alveolar septation in newborn mice. Am J Physiol Lung Cell Mol Physiol 293: , 2007. First published August 17, 2007; — Mechanical ventilation (MV) with O2-rich gas offers life-saving treatment for extremely premature infants with respiratory failure but often leads to neonatal chronic lung disease (CLD), characterized by defective formation of alveoli and blood vessels in the developing lung. We discovered that MV of 2- to 4-day-old mice with 40% O2 for 8 h, compared with unventilated control pups, reduced lung expression of genes that regulate lung septation and angiogenesis (VEGF-A and its receptor, VEGF-R2; PDGF-A; and tenascin-C). MV with air for 8 h yielded similar results for PDGF-A and tenascin-C but did not alter lung mRNA expression of VEGF or VEGF-R2. MV of 4- to 6-day-old mice with 40% O2 for 24 h reduced lung protein abundance of VEGF-A, VEGF-R2, PDGF-A, and tenascin-C and resulted in lung structural abnormalities consistent with evolving CLD. After MV with 40% O2 for 24 h, lung volume was similar to unventilated controls, whereas distal air space size, assessed morphometrically, was greater in lungs of ventilated pups, indicative of impaired septation. Immunostaining for vimentin, which is expressed in myofibroblasts, was reduced in distal lung after 24 h of MV with 40% O2. These molecular, cellular, and structural changes occurred without detectable lung inflammation as evaluated by histology and assays for proinflammatory cytokines, myeloperoxidase activity, and water content in lung. Thus lengthy MV of newborn mice with O2-rich gas reduces lung expression of genes and proteins that are critical for normal lung growth and development. These changes yielded lung structural defects similar to those observed in evolving CLD.

scholarly journals Developmental expression of fibrillin genes suggests heterogeneity of extracellular microfibrils.

1995 ◽  
Vol 129 (4) ◽  
pp. 1165-1176 ◽  
Author(s):  
H Zhang ◽  
W Hu ◽  
F Ramirez
Keyword(s):  
Spatial Organization ◽  
Developmental Stages ◽  
Elastic Fiber ◽  
Biomechanical Properties ◽  
Developmental Expression ◽  
Elastic Fibers ◽  
Fiber Assembly ◽  
Structural Support ◽  
Functional Relationships ◽  
Fibrillin 1

Extracellular microfibrils, alone or in association with elastin, confer critical biomechanical properties on a variety of connective tissues. Little is known about the composition of the microfibrils or the factors responsible for their spatial organization into tissue-specific macroaggregates. Recent work has revealed the existence of two structurally related microfibrillar components, termed fibrillin-1 and fibrillin-2. The functional relationships between these glycoproteins and between them and other components of the microfibrils and elastic fibers are obscure. As a first step toward elucidating these important points, we compared the expression pattern of the fibrillin genes during mammalian embryogenesis. The results revealed that the two genes are differentially expressed, in terms of both developmental stages and tissue distribution. In the majority of cases, fibrillin-2 transcripts appear earlier and accumulate for a shorter period of time than fibrillin-1 transcripts. Synthesis of fibrillin-1 correlates with late morphogenesis and the appearance of well-defined organ structures; fibrillin-2 synthesis, on the other hand, coincides with early morphogenesis and, in particular, with the beginning of elastogenesis. The findings lend indirect support to our original hypothesis stating that fibrillins contribute to the compositional and functional heterogeneity of the microfibrils. The available evidence is also consistent with the notion that the fibrillins might have distinct, but related roles in microfibril physiology. Accordingly, we propose that fibrillin-1 provides mostly force-bearing structural support, whereas fibrillin-2 predominantly regulates the early process of elastic fiber assembly.

scholarly journals Interaction of Tropoelastin with the Amino-terminal Domains of Fibrillin-1 and Fibrillin-2 Suggests a Role for the Fibrillins in Elastic Fiber Assembly

2000 ◽  
Vol 275 (32) ◽  
pp. 24400-24406 ◽  
Author(s):  
Timothy M. Trask ◽  
Barbara Crippes Trask ◽  
Timothy M. Ritty ◽  
William R. Abrams ◽  
Joel Rosenbloom ◽  
...  
Keyword(s):  
Elastic Fiber ◽  
Fiber Assembly ◽  
Amino Terminal ◽  
Fibrillin 1 ◽  
Terminal Domains

scholarly journals Macrophage-derived IL-6 trans-signaling as a novel target in the pathogenesis of bronchopulmonary dysplasia

2021 ◽  
pp. 2002248
Author(s):  
Dharmesh Hirani ◽  
Cristina M. Alvira ◽  
Soula Danopoulos ◽  
Carlos Milla ◽  
Michele Donato ◽  
...  
Keyword(s):  
Bronchopulmonary Dysplasia ◽  
Elastic Fiber ◽  
Fiber Formation ◽  
Lung Growth ◽  
Newborn Mice ◽  
Fiber Assembly ◽  
Alveolar Epithelial ◽  
Increased Risk ◽  
Novel Target

RationalePremature infants exposed to oxygen are at risk for bronchopulmonary dysplasia (BPD), which is characterised by lung growth arrest. Inflammation is important, but the mechanisms remain elusive. Here, we investigated inflammatory pathways and therapeutic targets in severe clinical and experimental BPD.Methods and ResultsFirst, transcriptomic analysis with in-silico cellular deconvolution identified a lung-intrinsic M1-like-driven cytokine pattern in newborn mice after hyperoxia. These findings were confirmed by gene expression of macrophage-regulating chemokines (Ccl2, Ccl7, Cxcl5) and markers (Il6, Il17A, Mmp12). Second, hyperoxia-activated IL-6/STAT3 signaling was measured in vivo and related to loss of alveolar epithelial type II cells (ATII) as well as increased mesenchymal marker. Il6 null mice exhibited preserved ATII survival, reduced myofibroblasts and improved elastic fiber assembly, thus enabling lung growth and protecting lung function. Pharmacological inhibition of global IL-6 signaling and IL-6 trans-signaling promoted alveolarisation and ATII survival after hyperoxia. Third, hyperoxia triggered M1-like polarisation, possibly via Klf4; hyperoxia-conditioned medium of macrophages and IL-6 impaired ATII proliferation. Finally, clinical data demonstrate elevated macrophage-related plasma cytokines as potential biomarkers that identify infants receiving oxygen at increased risk of developing BPD. Moreover, macrophage-derived IL6 and active STAT3 were related to loss of epithelial cells in BPD lungs.ConclusionWe present a novel IL-6-mediated mechanism by which hyperoxia activates macrophages in immature lungs, impairs ATII homeostasis, and disrupts elastic fiber formation, thereby inhibiting lung growth. The data provide evidence that IL-6 trans-signaling could offer an innovative pharmacological target to enable lung growth in severe neonatal chronic lung disease.

scholarly journals Microfibril-associated Glycoprotein-2 Interacts with Fibrillin-1 and Fibrillin-2 Suggesting a Role for MAGP-2 in Elastic Fiber Assembly

2002 ◽  
Vol 277 (38) ◽  
pp. 35044-35049 ◽  
Author(s):  
Akiyo S. Penner ◽  
Matthew J. Rock ◽  
Cay M. Kielty ◽  
J. Michael Shipley
Keyword(s):  
Elastic Fiber ◽  
Fiber Assembly ◽  
Fibrillin 1

scholarly journals Prolonged mechanical ventilation with air induces apoptosis and causes failure of alveolar septation and angiogenesis in lungs of newborn mice

2010 ◽  
Vol 298 (1) ◽  
pp. L23-L35 ◽  
Author(s):  
Lucia M. Mokres ◽  
Kakoli Parai ◽  
Anne Hilgendorff ◽  
Robert Ertsey ◽  
Cristina M. Alvira ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Transforming Growth Factor ◽  
Prolonged Mechanical Ventilation ◽  
Fold Increase ◽  
Cyclic Stretch ◽  
Vegf Receptor ◽  
Tgfβ Signaling ◽  
Newborn Mice ◽  
Vegf Signaling ◽  
The Impact

Defective lung septation and angiogenesis, quintessential features of neonatal chronic lung disease (CLD), typically result from lengthy exposure of developing lungs to mechanical ventilation (MV) and hyperoxia. Previous studies showed fewer alveoli and microvessels, with reduced VEGF and increased transforming growth factor-β (TGFβ) signaling, and excess, scattered elastin in lungs of premature infants and lambs with CLD vs. normal controls. MV of newborn mice with 40% O2for 24 h yielded similar lung structural abnormalities linked to impaired VEGF signaling, dysregulated elastin production, and increased apoptosis. These studies could not determine the relative importance of cyclic stretch vs. hyperoxia in causing these lung growth abnormalities. We therefore studied the impact of MV for 24 h with air on alveolar septation (quantitative lung histology), angiogenesis [CD31 quantitative-immunohistochemistry (IHC), immunoblots], apoptosis [TdT-mediated dUTP nick end labeling (TUNEL), active caspase-3 assays], VEGF signaling [VEGF-A, VEGF receptor 1 (VEGF-R1), VEGF-R2 immunoblots], TGFβ activation [phosphorylated Smad2 (pSmad2) quantitative-IHC], and elastin production (tropoelastin immunoblots, quantitative image analysis of Hart's stained sections) in lungs of 6-day-old mice. Compared with unventilated controls, MV caused a 3-fold increase in alveolar area, ∼50% reduction in alveolar number and endothelial surface area, >5-fold increase in apoptosis, >50% decrease in lung VEGF-R2 protein, 4-fold increase of pSmad2 protein, and >50% increase in lung elastin, which was distributed throughout alveolar walls rather than at septal tips. This study is the first to show that prolonged MV of developing lungs, without associated hyperoxia, can inhibit alveolar septation and angiogenesis and increase apoptosis and lung elastin, findings that could reflect stretch-induced changes in VEGF and TGFβ signaling, as reported in CLD.

scholarly journals Fibulin-5/DANCE has an elastogenic organizer activity that is abrogated by proteolytic cleavage in vivo

2007 ◽  
Vol 176 (7) ◽  
pp. 1061-1071 ◽  
Author(s):  
Maretoshi Hirai ◽  
Tetsuya Ohbayashi ◽  
Masahito Horiguchi ◽  
Katsuya Okawa ◽  
Akari Hagiwara ◽  
...  
Keyword(s):  
Lysyl Oxidase ◽  
Elastic Fiber ◽  
Elastic Fibers ◽  
Cross Linking ◽  
Fiber Assembly ◽  
Organizer Activity ◽  
Serum Dependent ◽  
Serum Free Conditions ◽  
Deficient Mice

Elastic fibers are required for the elasticity and integrity of various organs. We and others previously showed that fibulin-5 (also called developing arteries and neural crest EGF-like [DANCE] or embryonic vascular EGF-like repeat–containing protein [EVEC]) is indispensable for elastogenesis by studying fibulin-5–deficient mice, which recapitulate human aging phenotypes caused by disorganized elastic fibers (Nakamura, T., P.R. Lozano, Y. Ikeda, Y. Iwanaga, A. Hinek, S. Minamisawa, C.F. Cheng, K. Kobuke, N. Dalton, Y. Takada, et al. 2002. Nature. 415:171–175; Yanagisawa, H., E.C. Davis, B.C. Starcher, T. Ouchi, M. Yanagisawa, J.A. Richardson, and E.N. Olson. 2002. Nature. 415:168–171). However, the molecular mechanism by which fiblin-5 contributes to elastogenesis remains unknown. We report that fibulin-5 protein potently induces elastic fiber assembly and maturation by organizing tropoelastin and cross-linking enzymes onto microfibrils. Deposition of fibulin-5 on microfibrils promotes coacervation and alignment of tropoelastins on microfibrils, and also facilitates cross-linking of tropoelastin by tethering lysyl oxidase-like 1, 2, and 4 enzymes. Notably, recombinant fibulin-5 protein induced elastogenesis even in serum-free conditions, although elastogenesis in cell culture has been believed to be serum-dependent. Moreover, the amount of full-length fibulin-5 diminishes with age, while truncated fibulin-5, which cannot promote elastogenesis, increases. These data suggest that fibulin-5 could be a novel therapeutic target for elastic fiber regeneration.

scholarly journals Comparative gene array analyses of severe elastic fiber defects in late embryonic and newborn mouse aorta

2018 ◽  
Vol 50 (11) ◽  
pp. 988-1001 ◽  
Author(s):  
Marius Catalin Staiculescu ◽  
Austin J. Cocciolone ◽  
Jesse D. Procknow ◽  
Jungsil Kim ◽  
Jessica E. Wagenseil
Keyword(s):  
Developmental Stage ◽  
Lysyl Oxidase ◽  
Elastic Fiber ◽  
Gene Array ◽  
Aortic Aneurysms ◽  
Elastic Fibers ◽  
Newborn Mouse ◽  
Newborn Mice ◽  
Mouse Aorta ◽  
Array Analyses

Elastic fibers provide reversible elasticity to the large arteries and are assembled during development when hemodynamic forces are increasing. Mutations in elastic fiber genes are associated with cardiovascular disease. Mice lacking expression of the elastic fiber genes elastin ( Eln−/−), fibulin-4 ( Efemp2−/−), or lysyl oxidase ( Lox−/−) die at birth with severe cardiovascular malformations. All three genetic knockout models have elastic fiber defects, aortic wall thickening, and arterial tortuosity. However, Eln−/− mice develop arterial stenoses, while Efemp2−/− and Lox−/− mice develop ascending aortic aneurysms. We performed comparative gene array analyses of these three genetic models for two vascular locations and developmental stages to determine differentially expressed genes and pathways that may explain the common and divergent phenotypes. We first examined arterial morphology and wall structure in newborn mice to confirm that the lack of elastin, fibulin-4, or lysyl oxidase expression provided the expected phenotypes. We then compared gene expression levels for each genetic model by three-way ANOVA for genotype, vascular location, and developmental stage. We found three genes upregulated by genotype in all three models, Col8a1, Igfbp2, and Thbs1, indicative of a common response to severe elastic fiber defects in developing mouse aorta. Genes that are differentially regulated by vascular location or developmental stage in all three models suggest mechanisms for location or stage-specific disease pathology. Comparison of signaling pathways enriched in all three models shows upregulation of integrins and matrix proteins involved in early wound healing, but not of mature matrix molecules such as elastic fiber proteins or fibrillar collagens.

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