Early-life exposure to cigarette smoke primes lung function and DNA methylation changes at Cyp1a1 upon exposure later in life.

Prenatal and early-life exposure to cigarette smoke (CS) has repeatedly been shown to induce stable, long-term changes in DNA methylation (DNAm) in offspring. It has been hypothesized that these changes might be functionally related to the known outcomes of prenatal and early-life CS exposure, which include impaired lung development, altered lung function, and increased risk of asthma and wheeze. However, to date, few studies have examined DNAm changes induced by prenatal CS in tissues of the lung, and even fewer have attempted to examine the specific influences of prenatal versus early postnatal exposures. Here, we have established a mouse model of CS exposure which isolates the effects of prenatal and early postnatal CS exposures in early life. We have used this model to measure the effects of prenatal and/or postnatal CS exposures on lung function and immune cell infiltration as well as DNAm and expression of Cyp1a1, a candidate gene previously observed to demonstrate DNAm differences on CS exposure in humans. Our study revealed that exposure to CS prenatally and in the early postnatal period causes long-lasting differences in offspring lung function, gene expression, and lung Cyp1a1 DNAm, which wane over time but are reestablished on reexposure to CS in adulthood. This study creates a testable mouse model that can be used to investigate the effects of prenatal and early postnatal CS exposures and will contribute to the design of intervention strategies to mediate these detrimental effects.NEW & NOTEWORTHY Here, we isolated effects of prenatal from early postnatal cigarette smoke and showed that exposure to cigarette smoke early in life causes changes in offspring DNA methylation at Cyp1a1 that last through early adulthood but not into late adulthood. We also showed that smoking in adulthood reestablished these DNA methylation patterns at Cyp1a1, suggesting that a mechanism other than DNA methylation results in long-term memory associated with early-life cigarette smoke exposures at this gene.

MicroRNA-200b deficiency is not sufficient to increase susceptibility to allergen-induced airway inflammation and dysfunction in mice.

MicroRNA-200b (miR-200b) has emerged as a therapeutic option for reducing inflammation and airway dysfunction in asthma. miR-200b belongs to a family of miRNAs that regulate epithelial-to-mesenchymal (EMT) transition and IL-33 abundance. In asthma, miR-200b abundance is reduced in the airways and is correlated with disease severity. In addition, prophylactic treatment with a miR-200b mimetic reduces airway inflammation and airway dysfunction in a mouse model. However, it is unclear whether miR-200b deficiency is sufficient to drive airway dysfunction and airway inflammation in asthma. Here, we show that male and female mice deficient in miR-200b do not display heightened airway inflammation or alterations in lung function that are characteristic of asthma. Following sensitization with house dust mite (HDM), female miR-200b knockout (KO) mice have elevated total lung resistance and male miR-200b KO have increased airway resistance. However, neither male nor female miR-200b mice display any changes in methacholine sensitivity or responsiveness and do not have enhanced HDM-induced airway inflammation. Collectively, these findings suggest that loss of miR-200b does not drive airway inflammation and airway dysfunction in mice. Thus, although treatment with exogenous miR-200b may ameliorate inflammation in asthma, deficiency of miR-200b is not likely driving pathobiology in asthma.NEW & NOTEWORTHY MicroRNA-200b regulates the abundance of key asthma-related genes. However, loss of miR-200b does not potentiate allergic asthma in a mouse model, suggesting that miR-200b deficiency may not be sufficient to drive of asthma pathogenesis.

Yes-associated protein is dysregulated during nitrofen-induced hypoplastic lung development due to congenital diaphragmatic hernia.

BACKGROUND: Congenital diaphragmatic hernia (CDH) is a birth defect associated with abnormal lung development. Yes-associated protein (YAP) is a core kinase of the Hippo pathway, which controls organ size during development. The absence of YAP protein during lung development results in hypoplastic lungs comparable to the lung phenotype in CDH (Mahoney, Dev Cell 30(2):137-150, 2014). We aimed to describe the expression of YAP during normal and nitrofen-induced abnormal lung development. METHODS: Intra-gastric administration of dams with 100 mg of nitrofen was used to induce CDH and abnormal lung development in the embryos. Immunofluorescence was performed to visualize the localization of YAP and p-YAP during lung development (E15, E18, E21). Western Blotting was used to determine the abundance of YAP and p-YAP in E21 control and nitrofen-induced hypoplastic CDH lungs. RESULTS: Immunofluorescence demonstrated cytoplasmic localization of YAP protein in airway epithelial and mesenchymal cells of nitrofen-induced hypoplastic lungs compared to nuclear localization in control lungs. Western Blotting showed a decrease (p = 0.0188) in abundance of YAP (active form) and increase in p-YAP (inactive form) in hypoplastic lungs compared to control lungs. CONCLUSION: Our results demonstrate that YAP protein is mostly phosphorylated, inactive, and expressed in the cytoplasm at the later stages of nitrofen-induced hypoplastic lung development indicating that the alteration in regulation of YAP can be associated with the pathogenesis of abnormal lung development in experimental CDH.

Maternal diabetes promotes offspring lung dysfunction and inflammation in a sex-dependent manner.

Exposure to maternal diabetes is increasingly recognized as a risk factor for chronic respiratory disease in children. It is currently unclear; however, whether maternal diabetes affects the lung health of male and female offspring equally. This study characterizes the sex-specific impact of a murine model of diet-induced gestational diabetes (GDM) on offspring lung function and airway inflammation. Female adult mice are fed a high-fat (45% kcal) diet for 6 wk prior to mating. Control offspring are from mothers fed a low-fat (10% kcal) diet. Offspring were weaned and fed a chow diet until 10 wk of age, at which point lung function was measured and lung lavage was collected. Male, but not female, offspring exposed to GDM had increased lung compliance and reduced lung resistance at baseline. Female offspring exposed to GDM displayed increased methacholine reactivity and elevated levels of proinflammatory cytokines [e.g., interleukin (IL)-1ß, IL-5, and CXCL1] in lung lavage. Female GDM offspring also displayed elevated abundance of matrix metalloproteinases (MMP) within their airways, namely, MMP-3 and MMP-8. These results indicate disparate effects of maternal diabetes on lung health and airway inflammation of male and female offspring exposed to GDM. Female mice may be at greater risk of inflammatory lung conditions, such as asthma, whereas male offspring display changes that more closely align with models of chronic obstructive pulmonary disease. In conclusion, there are important sex-based differences in the impact of maternal diabetes on offspring lung health that could signal differences in future disease risk.

Epithelial cell-adhesion protein cadherin 26 is dysregulated in congenital diaphragmatic hernia and congenital pulmonary airway malformation.

BACKGROUND: Congenital diaphragmatic hernia (CDH) and congenital pulmonary airway malformation (CPAM) are two inborn pathologies of the lung of unknown origin. Alterations of gene expression in airway epithelial cells are involved in the pathobiology of both diseases. We previously found decreased expression of the epithelial cell adhesion protein cadherin 26 (CDH26) in hypoplastic mice lungs. Here, our objective was to describe the expression and localization of CDH26 in hypoplastic CDH lungs and hyperproliferative CPAM tissues. METHODS: After ethical approval, we used human lung tissues from CDH and CPAM cases and age-matched control samples from a previously established biobank. Furthermore, lungs from the nitrofen rat model of CDH were included in the study. We performed immunohistochemistry and western blot analysis with antibodies against CDH26 to examine protein localization and abundance. Statistical analysis was performed using Mann-Whitney U test with significance set at p < 0.05. RESULTS: We observed an overexpression of CDH26 within the epithelium of cystic CPAM lesions compared to normal airways within the same lung and compared to control lungs. Western blot demonstrated a downregulation of CDH26 in the nitrofen rat model of CDH compared to healthy controls. Immunohistochemistry could not show consistent differences between CDH and control in human and rat lungs. In the studied human lung samples, CDH26 was localized to the apical part of the airway epithelial cells. CONCLUSION: CDH26 is differentially expressed in human CPAM lung tissues and may be downregulated in nitrofen-induced hypoplastic rat lungs compared to control lungs. Disruption of CDH26 associated pathways in lung development may be involved in the pathogenesis of lung hypoplasia or cystic lung disease.

Establishment of a biobank for human lung tissues of congenital diaphragmatic hernia and congenital pulmonary airway malformation.

BACKGROUND: Human tissue samples are an invaluable and little available source of information for translational studies of congenital lung diseases such as Congenital Diaphragmatic Hernia (CDH) or Congenital Pulmonary Airway Malformation (CPAM). PURPOSE: We aimed to establish a human lung tissue biobank of CDH and CPAM patients together with age-matched controls, coupled with a clinical database. METHODS: Pathology records from autopsies or surgical specimens for CDH and CPAM cases between 1980 and 2017 were reviewed. For surviving individuals, clinical patient data was obtained from corresponding pediatric surgery reports. Formalin-fixed, paraffin-embedded tissues of patients and age-matched controls were systematically stored for further translational studies. RNA integrity was determined on selected CDH blocks. RESULTS: A total of 16 CDH and 18 CPAM and age-matched control lung tissue blocks were included in our biobank. Ages ranged from 22 to 41 weeks of gestation (GA) in CDH (33.9 ±â€¯6.35 weeks) and 26 weeks (GA) and 12 years in CPAM (2.3 ±â€¯3.7 y). RNA isolation from CDH and control blocks yielded good RNA quality (OD 260/280 ratio: 2.01-2.09, OD 260/230 ratio: 2.04-2.09). CONCLUSION: We established a unique human biobank for CDH and CPAM tissues. The combination with clinical patient data will allow us to design future translational studies to improve our understanding of the disease pathogenesis of these congenital malformations.