Mouse Pneumonectomy Model of Compensatory Lung Growth

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to ...

Cincinnati Children's Hospital Medical Center

Thy-1 is a cell surface glycoprotein present on normal lung fibroblasts but absent from the fibroblastic foci of idiopathic pulmonary fibrosis. Thy-1 correlates inversely with fibrogenic phenotypic characteristics and functions as a "fibrosis suppressor." Promoter region hypermethylation can silence Thy-1 expression in fibroblastic foci, suggesting that epigenetic regulation is important in programming the fibrotic phenotype. We examined whether histone modifications are important in regulating Thy-1 expression in lung fibroblasts. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) restored Thy-1 expression in Thy-1(-) cells in a time-dependent and concentration-dependent fashion and was associated with enrichment of histone acetylation. Chromatin immunoprecipitation demonstrated Thy-1 depletion of trimethylated H3K27 after 24 hours of TSA treatment, concurrent with enrichment of trimethylated H3K4 and acetylated H4. Bisulfite sequencing of the Thy-1 promoter region revealed demethylation of the previously hypermethylated CpG sites after treatment with TSA. Although Thy-1 was hypermethylated in Thy-1(-) lung fibroblasts, we observed that Thy-1(-) cells have lower global DNA methylation compared with Thy-1(+) lung fibroblasts, which was partially reversed by TSA treatment. TSA treatment up-regulates total methyltransferase activity in these cells. Our data indicate that Thy-1 silencing is regulated by histone modifications in addition to promoter hypermethylation in lung fibroblasts. Additionally, our findings indicate that alteration of histone modifications alters DNA methylation. Understanding the molecular hierarchy of events with respect to reactivation of transcription and reversal of histone modification will be critical to understand and modify the regulated expression of Thy-1, a tumor-supressor and fibrosis-suppressor gene.

Epigenetic regulation of thy-1 by histone deacetylase inhibitor in rat lung fibroblasts.

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Septic shock heterogeneity has important implications for clinical trial implementation and patient management. We previously addressed this heterogeneity by identifying three putative subclasses of children with septic shock based exclusively on a 100-gene expression signature. Here we attempted to prospectively validate the existence of these gene expression-based subclasses in a validation cohort.

Validation of a gene expression-based subclassification strategy for pediatric septic shock.

H&eacute;t&eacute;rog&eacute;n&eacute;it&eacute; de choc septique a des implications importantes pour la clinique mise en oeuvre du proc&egrave;s et de la gestion des patients. Nous avons pr&eacute;c&eacute;demment abord&eacute; cette h&eacute;t&eacute;rog&eacute;n&eacute;it&eacute; en identifiant trois sous-classes putatifs de l&#39;enfant avec choc septique bas&eacute; exclusivement sur une signature de l&#39;expression des g&egrave;nes-100. Ici nous avons tent&eacute; de valider prospectivement l&#39;existence de ces sous-classes ax&eacute;e sur l&#39;expression de g&egrave;ne dans une cohorte de validation.

Validation d&#39;une strat&eacute;gie de subclassification ax&eacute;e sur l&#39;expression g&eacute;nique p&eacute;diatrique choc septique.

Septischer Schock Heterogenit&auml;t hat wichtige Implikationen f&uuml;r klinische Proze&szlig; der Durchf&uuml;hrung und Patientenverwaltung. Wir beheben, dieser Heterogenit&auml;t zuvor drei vermeintliche Unterklassen von Kindern mit septischer Schock basiert ausschlie&szlig;lich auf einer 100-Genexpression-Signatur identifizieren. Hier haben wir versucht, die Existenz dieser gen ausdrucksbasierte Unterklassen in eine Validierung-Kohorte prospektiv validiert.

Validierung einer gen ausdrucksbasierte Skalpdefekte Strategie f&uuml;r p&auml;diatrische septischer Schock.

Eterogeneit&agrave; di shock settico ha importanti implicazioni per l&#39;implementazione di trial clinici e gestione dei pazienti. In precedenza abbiamo affrontato questa eterogeneit&agrave; identificando tre sottoclassi putative dei bambini con shock settico basato esclusivamente su una firma 100-gene expression. Qui abbiamo tentato di prospetticamente convalidare l&#39;esistenza di queste sottoclassi basato sull&#39;espressione genica in una coorte di convalida.

Convalida di una strategia di sottoclassificazione basato sull&#39;espressione del gene per shock settico pediatrico.

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Heterogeneidad de shock s&eacute;ptico tiene implicaciones importantes para la implementaci&oacute;n de ensayo cl&iacute;nico y tratamiento de los pacientes. Anteriormente, abordamos esta heterogeneidad mediante la identificaci&oacute;n de tres subclases putativas de los ni&ntilde;os con shock s&eacute;ptico basado exclusivamente en una firma de la expresi&oacute;n g&eacute;nica de 100. Aqu&iacute; intentamos prospectivamente validar la existencia de estas subclases basadas en la expresi&oacute;n de genes en una cohorte de validaci&oacute;n.

Validaci&oacute;n de una estrategia de subclasificaci&oacute;n basadas en la expresi&oacute;n de gene por shock s&eacute;ptico pedi&aacute;trico.

Thy-1 is a glycosylphosphytidylinositol-linked cell-surface glycoprotein present on a subset of lung fibroblasts, which plays an important role in postnatal alveolarization. In the present study, we define the role of Thy-1 in pulmonary lipofibroblast differentiation and in the regulation of lipid homeostasis via peroxisome proliferator-activated receptor-γ (PPARγ). Thy-1 was associated with interstitial cells containing lipid droplets in vivo. The transfection of Thy-1 into Thy-1 (-) fibroblasts increased triglyceride content, fatty-acid uptake, and the expression of the lipofibroblast marker adipocyte differentiation-related protein. Thy-1 (+) fibroblasts exhibited 2.4-fold higher PPARγ activity, and the inhibition or activation of PPARγ reduced and increased triglyceride content, respectively. Thy-1 (-) fibroblasts were not responsive to either of the PPARγ agonists ciglitazone or prostaglandin J(2), supporting the importance of Thy-1 in signaling via PPARγ. Thy-1 (+) fibroblasts expressed significantly higher concentrations of fatty-acid transporter protein-3 mRNA, and demonstrated higher rates of fatty-acid uptake and increased triglyceride content. The inhibition of fatty-acid transporter protein function reduced Thy-1 (+) fibroblast lipid content. The expression of Thy-1 in C57BL/6 lung fibroblasts increased during the neonatal period, coinciding with the onset of alveolarization. Thy-1 promoted lipofibroblast differentiation via the expression of PPARγ, stimulated lipid accumulation via fatty-acid esterification, and enhanced the fatty-acid uptake mediated by fatty-acid transporter proteins. Thy-1 is important in the regulation of lipofibroblast differentiation in the developing lung.

Thy-1 signals through PPARγ to promote lipofibroblast differentiation in the developing lung.

True pediatric emergencies are rare. Because resident work hours are restricted and national attention turns toward patient safety, teaching methods to improve physician performance and patient care are vital. We hypothesize that a critical-care simulation course will improve resident confidence and performance in critical-care situations.

Pediatric intensive care simulation course: a new paradigm in teaching.

Wntless (Wls), a gene highly conserved across the animal kingdom, encodes for a transmembrane protein that mediates Wnt ligand secretion. Wls is expressed in developing lung, wherein Wnt signaling is necessary for pulmonary morphogenesis. We hypothesize that Wls plays a critical role in modulating Wnt signaling during lung development and therefore affects processes critical for pulmonary morphogenesis. We generated conditional Wls mutant mice utilizing Shh-Cre and Dermo1-Cre mice to delete Wls in the embryonic respiratory epithelium and mesenchyme, respectively. Epithelial deletion of Wls disrupted lung branching morphogenesis, peripheral lung development and pulmonary endothelial differentiation. Epithelial Wls mutant mice died at birth due to respiratory failure caused by lung hypoplasia and pulmonary hemorrhage. In the lungs of these mice, VEGF and Tie2-angiopoietin signaling pathways, which mediate vascular development, were downregulated from early stages of development. In contrast, deletion of Wls in mesenchymal cells of the developing lung did not alter branching morphogenesis or early mesenchymal differentiation. In vitro assays support the concept that Wls acts in part via Wnt5a to regulate pulmonary vascular development. We conclude that epithelial Wls modulates Wnt ligand activities critical for pulmonary vascular differentiation and peripheral lung morphogenesis. These studies provide a new framework for understanding the molecular mechanisms underlying normal pulmonary vasculature formation and the dysmorphic pulmonary vasculature development associated with congenital lung disease.

Wntless is required for peripheral lung differentiation and pulmonary vascular development.

The formation of discrete elastin bands at the tips of secondary alveolar septa is important for normal alveolar development, but the mechanisms regulating the lung elastogenic program are incompletely understood. JNK suppress elastin synthesis in the aorta and is important in a host of developmental processes. We sought to determine whether JNK suppresses pulmonary fibroblast elastogenesis during lung development.

Brian M. Varisco

Division of Critical Care Medicine

Cincinnati Children's Hospital Medical Center

Mouse Pneumonectomy Model of Compensatory Lung Growth

Brian M. Varisco

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Division of Critical Care Medicine

Cincinnati Children's Hospital Medical Center

Mouse Pneumonectomy Model of Compensatory Lung Growth

Division of Critical Care Medicine