Intrinsic Biochemical and Functional Differences in Bronchial Epithelial Cells of Children with Asthma
Convincing evidence of epithelial damage and aberrant repair exists in adult asthmatic airways, even in the absence of inflammation. However, comparable studies in children have been limited by access and availability of clinical samples.
To determine whether bronchial epithelial cells from children with asthma are inherently distinct from those obtained from children without asthma.
Epithelial cells were obtained by nonbronchoscopic bronchial brushing of children with mild asthma (n = 7), atopic children without asthma (n = 9), and healthy children (n = 12). Cells were subject to morphologic, biochemical, molecular, and functional assessment. Responses were also compared with commercially available epithelial cultures and the transformed cell line 16HBE140.
All epithelial cells exhibited a "cobblestone" morphology, which was maintained throughout culture and repeated passage. Expression of cytokeratin 19 varied, with disease phenotype being greatest in healthy nonatopics and lowest in asthmatics. In contrast, expression of cytokeratin 5/14 was greatest in asthmatic samples and least in healthy nonatopic samples. Asthmatic epithelial cells also spontaneously produced significantly greater amounts of interleukin (IL)-6, prostaglandin E2, and epidermal growth factor, and equivalent amounts of IL-1beta and soluble intracellular adhesion molecule-1, but significantly lower amounts of transforming growth factor beta1. This profile was maintained through successive passages. Asthmatic epithelial cells also exhibited greater rates of proliferation than nonasthmatic cells.
This study has shown that epithelial cells from children with mild asthma are intrinsically different both biochemically and functionally compared with epithelial cells from children without asthma. Importantly, these differences are maintained over successive passages, suggesting that they are not dependent on an in vivo environment.
Available from: Anthony Kicic
- "The described differences between these two could be explained by the preliminary data of altered cytokeratin expression. We have previously described a similar cytokeratin profile in asthmatic pAEC , suggesting that pAEC CF may also be less well differentiated compared to healthy cells. We are currently exploring this further in order to assess if this is intrinsic or a result of constant injury. "
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ABSTRACT: Aim of the study:
The bronchial brushing technique presents an opportunity to establish a gold standard in vitro model of Cystic Fibrosis (CF) airway disease. However, unique obstacles exist when establishing CF airway epithelial cells (pAECCF). We aimed to identify determinants of culture success through retrospective analysis of a program of routinely brushing children with CF.
Materials and methods:
Anaesthetised children (CF and non-CF) had airway samples taken which were immediately processed for cell culture. Airway data for the CF cohort was obtained from clinical records and the AREST CF database.
Of 260 brushings processed for culture, 114 (43.8%) pAECCF successfully cultured to passage one (P1) and 63 (24.2% of total) progressed to passage two (P2). However, >80% of non-CF specimens (pAECnon-CF) cultured to P2 from similar cell numbers. Within the CF cohort, specimens successfully cultured to P2 had a higher initial cell count and lower proportion of severe CF mutation phenotype than those that did not proliferate beyond initial seeding. Elevated airway IL-8 concentration was also negatively associated with culture establishment. Contamination by opportunistic pathogens was observed in 81 (31.2% of total) cultures and brushings from children with lower respiratory tract infections were more likely to co-culture contaminating flora.
Lower passage rates of pAECCF cultures uniquely contrasts with pAECnon-CF despite similar cell numbers. An equivalent establishment rate of CF nasal epithelium reported elsewhere, significant associations to CFTR mutation phenotype, elevated airway IL-8 and opportunistic pathogens all suggest this is likely related to the CF disease milieu.
Experimental Lung Research 09/2014; 40(9). DOI:10.3109/01902148.2014.946631 · 1.41 Impact Factor
Available from: Anthony Kicic
- "There is now substantial evidence that the airway epithelium of subjects who have asthma is abnormal, including increased expression of epithelial growth factor receptor (EGFR) at denuded and damaged sites , , , , , altered expression of adhesion proteins E-cadherin and zonula occluden-1  and elevated numbers of basal cells marked by cytokeratin-5 , . Cultured asthmatic epithelial cells have also been shown to be more vulnerable to oxidant-induced stress and display aberrant expression of heat-shock proteins and proinflammatory transcription factors , , , , . Thus, it is important to identify if airway epithelial-specific DNA methylation patterns are altered with diseased epithelium in order to fully understand the disease process. "
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ABSTRACT: Allergic inflammation is commonly observed in a number of conditions that are associated with atopy including asthma, eczema and rhinitis. However, the genetic, environmental or epigenetic factors involved in these conditions are likely to be different. Epigenetic modifications, such as DNA methylation, can be influenced by the environment and result in changes to gene expression.
To characterize the DNA methylation pattern of airway epithelial cells (AECs) compared to peripheral blood mononuclear cells (PBMCs) and to discern differences in methylation within each cell type amongst healthy, atopic and asthmatic subjects.
PBMCs and AECs from bronchial brushings were obtained from children undergoing elective surgery for non-respiratory conditions. The children were categorized as atopic, atopic asthmatic, non-atopic asthmatic or healthy controls. Extracted DNA was bisulfite treated and 1505 CpG loci across 807 genes were analyzed using the Illumina GoldenGate Methylation Cancer Panel I. Gene expression for a subset of genes was performed using RT-PCR.
We demonstrate a signature set of CpG sites that are differentially methylated in AECs as compared to PBMCs regardless of disease phenotype. Of these, 13 CpG sites were specific to healthy controls, 8 sites were only found in atopics, and 6 CpGs were unique to asthmatics. We found no differences in the methylation status of PBMCs between disease phenotypes. In AECs derived from asthmatics compared to atopics, 8 differentially methylated sites were identified including CpGs in STAT5A and CRIP1. We demonstrate STAT5A gene expression is decreased whereas CRIP1 gene expression is elevated in the AECs from asthmatic compared to both healthy and atopic subjects.
We characterized a cell specific DNA methylation signature for AECs compared to PBMCs regardless of asthmatic or atopic status. Our data highlight the importance of understanding DNA methylation in the epithelium when studying the epithelial contribution to asthma.
PLoS ONE 09/2012; 7(9):e44213. DOI:10.1371/journal.pone.0044213 · 3.23 Impact Factor
Available from: Pieter Borger
- "Asthmatics patients often present clusters of epithelial cells (Creola bodies) in sputum and have increased numbers of epithelial cells in bronchoalveolar lavage fluid, which may result from the loss of airway epithelium observed in biopsy specimens [46, 47]. Upregulation of epidermal growth factor receptors (EGFRs), impaired proliferation reduced expression of proliferative markers and upregulation of the cyclin inhibitor, nuclear p21Waf1/Cip1 indicated that the epithelium is chronically injured and the repair mechanism is impaired in asthma [48, 49]. Furthermore, the epithelium of asthmatic patients is more fragile and the tight junctions are weakened [3, 50], in consequence, the airway epithelium enters into a chronic “wound scenario” . "
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ABSTRACT: Asthma and chronic obstructive pulmonary disease (COPD) are the two most prominent chronic inflammatory lung diseases with increasing prevalence. Both diseases are associated with mild or severe remodeling of the airways. In this review, we postulate that the pathologies of asthma and COPD may result from inadequate responses and/or a deregulated balance of a group of cell differentiation regulating factors, the CCAAT/Enhancer Binding Proteins (C/EBPs). In addition, we will argue that the exposure to environmental factors, such as house dust mite and cigarette smoke, changes the response of C/EBPs and are different in diseased cells. These novel insights may lead to a better understanding of the etiology of the diseases and may provide new aspects for therapies.
The Open Respiratory Medicine Journal 04/2012; 6(1):1-13. DOI:10.2174/1874306401206010001
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