Effect of TGF-β1 on eosinophils to induce cysteinyl leukotriene E4 production in aspirin-exacerbated respiratory disease

Cysteinyl leukotriene (cysLT) overproduction and eosinophil activation are hallmarks of aspirin-exacerbated respiratory disease (AERD). However, pathogenic mechanisms of AERD remain to be clarified. Here, we aimed to find the significance of transforming growth factor beta 1 (TGF-β1) in association with cysteinyl leukotriene E4 (LTE4) production, leading to eosinophil degranulation. To evaluate levels of serum TGF-β1, first cohort enrolled AERD (n = 336), ATA (n = 442) patients and healthy control subjects (HCs, n = 253). In addition, second cohort recruited AERD (n = 34) and ATA (n = 25) patients to investigate a relation between levels of serum TGF-β1 and urinary LTE4. The function of TGF-β1 in LTE4 production was further demonstrated by ex vivo (human peripheral eosinophils) or in vivo (BALB/c mice) experiment. As a result, the levels of serum TGF-β1 were significantly higher in AERD patients than in ATA patients or HCs (P = .001; respectively). Moreover, levels of serum TGF-β1 and urinary LTE4 had a positive correlation (r = 0.273, P = .037). In the presence of TGF-β1, leukotriene C4 synthase (LTC4S) expression was enhanced in peripheral eosinophils to produce LTE4, which sequentially induced eosinophil degranulation via the p38 pathway. When mice were treated with TGF-β1, significantly induced eosinophilia with increased LTE4 production in the lung tissues were noted. These findings suggest that higher levels of TGF-β1 in AERD patients may contribute to LTE4 production via enhancing LTC4S expression which induces eosinophil degranulation, accelerating airway inflammation.

Complete Tracheal Ring Deformity. A Translational Genomics Approach to Pathogenesis

Rationale: Complete tracheal ring deformity (CTRD) is a rare congenital abnormality of unknown etiology characterized by circumferentially continuous or nearly continuous cartilaginous tracheal rings, variable degrees of tracheal stenosis and/or shortening, and/or pulmonary arterial sling anomaly.Objectives: To test the hypothesis that CTRD is caused by inherited or de novo mutations in genes required for normal tracheal development.Methods: CTRD and normal tracheal tissues were examined microscopically to define the tracheal abnormalities present in CTRD. Whole-exome sequencing was performed in children with CTRD and their biological parents ("trio analysis") to identify gene variants in patients with CTRD. Mutations were confirmed by Sanger sequencing, and their potential impact on structure and/or function of encoded proteins was examined using human gene mutation databases. Relevance was further examined by comparison with the effects of targeted deletion of murine homologs important to tracheal development in mice.Measurements and Main Results: The trachealis muscle was absent in all of five patients with CTRD. Exome analysis identified six de novo, three recessive, and multiple compound-heterozygous or rare hemizygous variants in children with CTRD. De novo variants were identified in SHH (Sonic Hedgehog), and inherited variants were identified in HSPG2 (perlecan), ROR2 (receptor tyrosine kinase-like orphan receptor 2), and WLS (Wntless), genes involved in morphogenetic pathways known to mediate tracheoesophageal development in mice.Conclusions: The results of the present study demonstrate that absence of the trachealis muscle is associated with CTRD. Variants predicted to cause disease were identified in genes encoding Hedgehog and Wnt signaling pathway molecules, which are critical to cartilage formation and normal upper airway development in mice.

Fetal lung transcriptome patterns in an ex vivo compression model of diaphragmatic hernia

BACKGROUND

The purpose of this study was to employ a novel ex vivo lung model of congenital diaphragmatic hernia (CDH) to determine how a mechanical compression affects early pulmonary development.

METHODS

Day-15 whole fetal rat lungs (n = 6-12/group) from nitrofen-exposed and normal (vehicle only) dams were explanted and cultured ex vivo in compression microdevices (0.2 or 0.4 kPa) for 16 h to mimic physiologic compression forces that occur in CDH in vivo. Lungs were evaluated with significance set at P < 0.05.

RESULTS

Nitrofen-exposed lungs were hypoplastic and expressed lower levels of surfactant protein C at baseline. Although compression alone did not alter the α-smooth muscle actin (ACTA2) expression in normal lungs, nitrofen-exposed lungs had significantly increased ACTA2 transcripts (0.2 kPa: 2.04 ± 0.15; 0.4 kPa: 2.22 ± 0.11; both P < 0.001). Nitrofen-exposed lungs also showed further reductions in surfactant protein C expression at 0.2 and 0.4 kPa (0.53 ± 0.04, P < 0.01; 0.69 ± 0.23, P < 0.001; respectively). Whereas normal lungs exposed to 0.2 and 0.4 kPa showed significant increases in periostin (POSTN), a mechanical stress-response molecule (1.79 ± 0.10 and 2.12 ± 0.39, respectively; both P < 0.001), nitrofen-exposed lungs had a significant decrease in POSTN expression (0.4 kPa: 0.67 ± 0.15, P < 0.001), which was confirmed by immunohistochemistry.

CONCLUSIONS

Collectively, these pilot data in a model of CDH lung hypoplasia suggest a primary aberration in response to mechanical stress within the nitrofen lung, characterized by an upregulation of ACTA2 and a downregulation in SPFTC and POSTN. This ex vivo compression system may serve as a novel research platform to better understand the mechanobiology and complex regulation of matricellular dynamics during CDH fetal lung development.

Novel Molecular and Phenotypic Insights into Congenital Lung Malformations

RATIONALE

Disruption of normal pulmonary development is a leading cause of morbidity and mortality in infants. Congenital lung malformations are a unique model to study the molecular pathogenesis of isolated structural birth defects, as they are often surgically resected.

OBJECTIVES

To provide insight into the molecular pathogenesis of congenital lung malformations through analysis of cell-type and gene expression changes in these lesions.

METHODS

Clinical data, and lung tissue for DNA, RNA, and histology, were obtained from 58 infants undergoing surgical resection of a congenital lung lesion. Transcriptome-wide gene expression analysis was performed on paired affected and unaffected samples from a subset of infants (n = 14). A three-dimensional organoid culture model was used to assess isolated congenital lung malformation epithelium (n = 3).

MEASUREMENTS AND MAIN RESULTS

Congenital lung lesions express higher levels of airway epithelial related genes, and dysregulated expression of genes related to the Ras and PI3K-AKT-mTOR (phosphatidylinositol 3-kinase-AKT-mammalian target of rapamycin) signaling pathways. Immunofluorescence confirmed differentiated airway epithelial cell types throughout all major subtypes of congenital lung lesions, and three-dimensional cell culture demonstrated a cell-autonomous defect in the epithelium of these lesions.

CONCLUSIONS

This study provides the first comprehensive analysis of the congenital lung malformation transcriptome and suggests that disruptions in Ras or PI3K-AKT-mTOR signaling may contribute to the pathology through an epithelial cell-autonomous defect.

A complete corticotropin releasing factor system localized in human fetal lung

OBJECTIVE

The Corticotropin Releasing Factor (CRF) system (neuropeptides CRF, Ucn I, II, III and binding sites CRFR1, CRFR2, CRF-BP) is responsible for stress regulation and the homeostasis of an organism. Herein we study the CRF system in human normal and pathological fetal lungs.

DESIGN

Lung tissues from 46 archival human fetuses were divided into Group A (normal), Group B (chromosomal abnormalities) and Group C (congenital disorders). Presence of elements of the CRF system was evaluated using immunohistochemistry and was correlated to pathology, lung developmental stage and clinicopathological characteristics.

RESULTS

Immunoreactivity for all antigens was found in both epithelial and mesenchymal lung cells of the bronchi and alveoli. Ucn I and CRFR1 were more frequently present in Group A. Ucns were more frequently localized at the pseudoglandular stage. There was a positive correlation between the presence of the CRF neuropeptides and between CRFR1 and CRF. Two fetuses with lung malformations showed low or no detectable presence of the CRF system.

CONCLUSIONS

We report the presence of a complete CRF system in human fetal lungs correlating its developmental stage and several pathologies. Our results are in agreement with findings in experimental animal models, implicating the CRF system in fetal lung development, its action being more significant in the early stages.

Neurodegeneration in drop-dead mutant drosophila melanogaster is associated with the respiratory system but not with Hypoxia

Mutations in the gene drop-dead (drd) cause diverse phenotypes in adult Drosophila melanogaster including early lethality, neurodegeneration, tracheal defects, gut dysfunction, reduced body mass, and female sterility. Despite the identification of the drd gene itself, the causes of early lethality and neurodegeneration in the mutant flies remain unknown. To determine the pattern of drd expression associated with the neurodegenerative phenotype, knockdown of drd with various Gal4 drivers was performed. Early adult lethality and neurodegeneration were observed upon knockdown of drd in the tracheal system with two independent insertions of the breathless-Gal4 driver and upon knockdown in the tracheal system and elsewhere with the DJ717-Gal4 driver. Surprisingly, rescue of drd expression exclusively in the tracheae in otherwise mutant flies rescued the neurodegenerative phenotype but not adult lethality. Gut dysfunction, as measured by defecation rate, was not rescued in these flies, and gut function appeared normal upon tracheal-specific knockdown of drd. Finally, the hypothesis that tracheal dysfunction in drd mutants results in hypoxia was tested. Hypoxia-sensitive reporter transgenes (LDH-Gal4 and LDH-LacZ) were placed on a drd mutant background, but enhanced expression of these reporters was not observed. In addition, manipulation of drd expression in the tracheae did not affect expression of the hypoxia-induced genes LDH, tango, and similar. Overall, these results indicate that there are at least two causes of adult lethality in drd mutants, that gut dysfunction and neurodegeneration are independent phenotypes, and that neurodegeneration is associated with tracheal expression of drd but not with hypoxia.

Heritability of abnormalities in cardiopulmonary coupling in sleep apnea: use of an electrocardiogram-based technique

RATIONALE

Studies of the genetics of obstructive sleep apnea may be facilitated by identifying intermediate traits with high heritability that quantify etiological pathways, such as those related to respiratory control. Electrocardiogram (ECG)-based sleep spectrograms, measuring the coupling between respiratory modulation of ECG QRS-wave amplitude and heart rate variability, may provide measures of sleep state and ventilatory dynamics during sleep. We evaluated the familial aggregation of distinctive spectrographic biomarkers of unstable sleep, related to elevated-low frequency cardiopulmonary coupling (e-LFC), to assess their utility in genetic studies.

METHODS

622 participants from 137 families from the Cleveland Family Study underwent standardized polysomnography (PSG). From the ECG signal on the PSG, the interbeat interval time series and the corresponding ECG-derived respiratory signal were extracted, and the low frequency (0.01-0.1 Hz) component of their coupling was computed using a fully automated method. Narrow sense heritability of e-LFC was calculated using variance component methods.

RESULTS

A spectral marker of abnormal low frequency cardiopulmonary coupling (e-LFC) demonstrated moderate correlation with apnea hypopnea index (AHI; r = 0.35, P < 0.0001). The heritability estimate for e-LFC, after adjusting for age and sex was 0.32 (P < 10-5) and remained unchanged after additionally adjusting for body mass index or AHI. In biological relatives of those with sleep apnea, a related marker of e-LFC was more prevalent than in controls (P = 0.05).

CONCLUSIONS

Approximately 30% of the variability of e-LFC, measured from a continuous ECG during sleep, is explained by familial factors other than BMI. ECG-based spectrographic measures of cardiopulmonary coupling may provide novel phenotypes for characterizing subgroups of individuals with different propensities and genetic etiologies for sleep apnea or for other conditions associated with sleep fragmentation.

Expression of epidermal growth factor receptor, but not K-RAS mutations, is present in congenital cystic airway malformation/congenital pulmonary airway malformation

Congenital cystic airway malformation/congenital pulmonary airway malformation (CCAM/CPAM) of the lung is a rare but well-described malformative lesion of pulmonary parenchyma characterized by the abnormal maturation of airways along with an increase in terminal respiratory structures, resulting in cysts of variable sizes. Five types have been classified based on morphological analysis. Although the etiology of the lesion is still unclear, recent data suggest that bronchial atresia is a predisposing/associated anomaly. A described association between type 1 CCAM/CPAM and bronchioloalveolar carcinoma suggests that type 1 CCAM/CPAM may predispose to malignant transformation by as yet unidentified tumorigenic mechanisms. Here we studied epidermal growth factor receptor (EGFR) and K-RAS oncogene, 2 biological markers closely associated with tumorigenesis and altered in many types of tumors, including lung carcinomas. For this purpose, we used immunohistochemistry and gene sequencing in paraffin-embedded tissue. Our results demonstrate expression of EGFR in types 1 and 3 CCAM/CPAM, with a distinctive distribution and intensity, compared with that of type 2. Of special interest, mucinous areas in 2 cases of type 1 CCAM/CPAM lacked EGFR expression, whereas adjacent epithelial cystic linings were strongly positive. This supports the hypothesis that mucinous differentiation in CCAM/CPAM, always present in cases with malignant transformation, could be related to other molecular pathways. The K-RAS gene was screened for mutations usually found in lung carcinomas; however, no mutations were present in any of the studied samples. These findings support the notion that EGFR may play an important role in the pathogenesis and phenotype of CCAM/CPAM.

Lung development and implications for hypoplasia found in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is associated with various degrees of pulmonary hypoplasia and severe persistent pulmonary hypertension in the newborn. These conditions have significant implications for the outcome for the patient. Defects in early lung development are likely to be central to the generation of hypoplasia. A number of mouse models with defects in pathways that are central to lung development were found to have CDH. Understanding all aspects of early lung development will provide fresh insight into the pathogenesis of CDH and its associated conditions.

Mecp2 deficiency disrupts norepinephrine and respiratory systems in mice

Rett syndrome is a severe X-linked neurological disorder in which most patients have mutations in the methyl-CpG binding protein 2 (MECP2) gene and suffer from bioaminergic deficiencies and life-threatening breathing disturbances. We used in vivo plethysmography, in vitro electrophysiology, neuropharmacology, immunohistochemistry, and biochemistry to characterize the consequences of the MECP2 mutation on breathing in wild-type (wt) and Mecp2-deficient (Mecp2-/y) mice. At birth, Mecp2-/y mice showed normal breathing and a normal number of medullary neurons that express tyrosine hydroxylase (TH neurons). At approximately 1 month of age, most Mecp2-/y mice showed respiratory cycles of variable duration; meanwhile, their medulla contained a significantly reduced number of TH neurons and norepinephrine (NE) content, even in Mecp2-/y mice that showed a normal breathing pattern. Between 1 and 2 months of age, all unanesthetized Mecp2-/y mice showed breathing disturbances that worsened until fatal respiratory arrest at approximately 2 months of age. During their last week of life, Mecp2-/y mice had a slow and erratic breathing pattern with a highly variable cycle period and frequent apneas. In addition, their medulla had a drastically reduced number of TH neurons, NE content, and serotonin (5-HT) content. In vitro experiments using transverse brainstem slices of mice between 2 and 3 weeks of age revealed that the rhythm produced by the isolated respiratory network was irregular in Mecp2-/y mice but could be stabilized with exogenous NE. We hypothesize that breathing disturbances in Mecp2-/y mice, and probably Rett patients, originate in part from a deficiency in noradrenergic and serotonergic modulation of the medullary respiratory network.

Spectrum of pediatric developmental and genetic renal lesions and associated congenital malformations--an autopsy study from north India

Pediatric developmental and genetic renal lesions are a known cause of mortality in the perinatal/neonatal period. These lesions are associated with a wide range of extrarenal congenital malformations that influence the outcome of the patients. In this autopsy study, we have analyzed the spectrum of pediatric developmental and genetic renal lesions and their associated congenital malformations. A total of 4,099 autopsies (20 weeks of gestation to 1 year of life) were reviewed, of which 158 cases (3.85%) of pediatric developmental (143 cases) and genetic renal lesions (15 cases) were found. Autosomal recessive polycystic kidney disease was the commonest genetic lesion. Primitive ducts with cuffing of immature mesenchyme--the sine qua non of renal dysplasia--was found in all cases of dysplasia. Associated congenital malformations were seen in all cases and thus a thorough search for them is mandatory. Ductal plate malformation was found in all cases of autosomal recessive polycystic kidney disease and in 1 case of bilateral multicystic dysplasia.

Pulmonary abnormalities due to ABCA1 deficiency in mice

Mice gene targeted for ATP-binding cassette transporter A1 (ABCA1; Abca1−/−) have been shown to have low-serum high-density lipoprotein and abnormal lung morphology. We examined alterations in the structure and function of lungs from −/− mice (DBA1/J). Electron microscopy of the diseased mouse lung revealed areas of focal disease confirming previous results ( 47 ). Lipid analysis of the lung tissue of −/− mice showed a 1.2- and 1.4-fold elevation in total phospholipid (PL) and saturated phosphatidylcholine, respectively, and a marked 50% enrichment in total cholesterol content predominately due to a 17.5-fold increase in cholesteryl ester compared with wild type (WT). Lung surfactant in the −/− mice was characterized by alveolar proteinosis (161%), a slight increase in total PL (124%), and a marked increase in free cholesterol (155%) compared with WT. Alveolar macrophages were enriched in cholesterol (4.8-fold) due to elevations in free cholesterol (2.4-fold) and in cholesteryl ester (14.8-fold) compared with WT macrophages. More PL mass was cleared from the alveolar space of −/− mice lungs, measured using intratracheal installation of3H-PL liposomes. Compared with WT mice, the Abca1−/−mice demonstrated respiratory distress with rapid, shallow breathing. Thus the lungs of mice lacking ABCA1 protein demonstrated abnormal morphology and physiology, with alveolar proteinosis and cholesterol enrichment of tissue, surfactant, and macrophages. The results indicate that the activity of ABCA1 is important for the maintenance of normal lung lipid composition, structure, and function.

Embryological origins and development of the rat diaphragm

Textbooks of embryology provide a standard set of drawings and text reflecting the traditional interpretation of phrenic nerve and diaphragm development based on anatomical dissections of embryonic tissue. Here, we revisit this issue, taking advantage of immunohistochemical markers for muscle precursors in conjunction with mouse mutants to perform a systematic examination of phrenic-diaphragm embryogenesis. This includes examining the spatiotemporal relationship of phrenic axon outgrowth and muscle precursors during different stages of myogenesis. Additionally, mutant mice lacking c-met receptors were used to visualize the mesenchymal substratum of the developing diaphragm in the absence of myogenic cells. We found no evidence for contributions to the diaphragm musculature from the lateral body wall, septum transversum, or esophageal mesenchyme, as standard dogma would state. Nor did the data support the hypothesis that the crural diaphragm is of distinct embryological origins. Rather, we found that myogenic cells and axons destined to form the neuromuscular component of the diaphragm coalesce within the pleuroperitoneal fold (PPF). It is the expansion of these components of the PPF that leads to the formation of the diaphragm. Furthermore, we extended these studies to examine the developing diaphragm in an animal model of congenital diaphragmatic hernia (CDH). We find that malformation of the PPF mesenchymal substratum leads to the defect characteristic of CDH. In summary, the data demonstrates that a significant revision of narratives describing normal and pathological development of the diaphragm is warranted.

De novo complete trisomy 5p: clinical report and FISH studies

We describe a de novo trisomy 5p in a 1-year-old severely retarded boy. The complete short arm of chromosome 5 segregated as an additional marker chromosome in all metaphases. The marker was identified as 5p by conventional cytogenetic techniques (GTG, GBG, CBG) and molecular cytogenetic techniques (whole chromosome-painting probe, probes for the cri-du-chat region and the centromere, and additionally high-resolution multicolor banding using a chromosome 5-specific DNA probe cocktail). The clinical findings were similar to the established trisomy 5p phenotype including macrocephaly, facial abnormalities, tracheobronchial defects with subsequent respiratory infections, hypotonia, and psychomotor retardation. To the best of our knowledge this is the first description of an isolated complete 5p trisomy without involvement of the aberrant chromosome in any structural chromosomal rearrangements.

Early postnatal lethality in Hoxa-5 mutant mice is attributable to respiratory tract defects

To uncover roles for the Hoxa-5 gene during embryogenesis, we have focused on identifying structural and functional defects in organ systems underlying the perinatal lethality in Hoxa-5 homozygous mutants. Analysis of the mutant phenotype shows that Hoxa-5 is essential for normal organogenesis and function of the respiratory tract. In homozygous newborn mutants, improper tracheal and lung morphogenesis can lead to tracheal occlusion, and to respiratory distress associated with a marked decrease in the production of surfactant proteins. Collectively, these defects likely underlie the pronounced mortality of homozygous mutant pups. Furthermore, the loss of Hoxa-5 function results in altered TTF-1, HNF-3 beta, and N-myc gene expression in the pulmonary epithelium. Since expression of Hoxa-5 is confined to the mesenchymal component of the developing trachea and lung, the effects observed in epithelial cells may result from a disruption of normal epithelial-mesenchymal interactions.