Background: The first step in SARS-CoV-2 infection is binding of the virus to angiotensin converting enzyme 2 (ACE2) on the airway epithelium. Asthma affects over 300 million people world-wide, many of whom may encounter SARS-CoV-2. Epidemiologic data suggests that asthmatics who get infected may be at increased risk of more severe disease. Our objective was to assess whether maintenance inhaled corticosteroids (ICS), a major treatment for asthma, is associated with airway ACE2 expression in asthmatics.
Up-regulation of ACE2, the SARS-CoV-2 receptor, in asthmatics on maintenance inhaled corticosteroids.
Specimen part, Treatment
View SamplesMotivation: Identification of eQTL, the genetic loci that contribute to heritable variation in gene expression, can be obstructed by factors that produce variation in expression profiles if these factors are unmeasured or hidden from direct analysis.
HEFT: eQTL analysis of many thousands of expressed genes while simultaneously controlling for hidden factors.
Disease, Race
View SamplesAirway remodelling in chronic obstructive pulmonary disease (COPD) originates, in part, from smoking-induced changes in airway basal stem/progenitor cells (BCs). Based on the knowledge that bone morphogenetic protein 4 (BMP4) influences epithelial progenitor function in the developing and adult mouse lung, we hypothesised that BMP4 signalling may regulate the biology of adult human airway BCs relevant to COPD.
Expression of the SARS-CoV-2 ACE2 Receptor in the Human Airway Epithelium.
Specimen part
View SamplesGamma-aminobutyric acid (GABA) is a multifunctional mediator that functions as a neurotransmitter in the central nervous system and a trophic factor during nervous system development, affecting proliferation, differentiation and cell death [1-3].GABA is synthesized from glutamate, catalyzed by GAD65 and GAD67, glutamic acid decarboxylase {Tillakaratne, Medina-Kauwe, et al. 1995 21 /id}{Owens & Kriegstein 2002 3 /id}{Watanabe, Maemura, et al. 2002 73 /id}. In the CNS transporters and catabolic enzymes work in a coordinated fashion to control the availability of GABA {Tillakaratne, Medina-Kauwe, et al. 1995 21 /id}{Owens & Kriegstein 2002 3 /id}{Watanabe, Maemura, et al. 2002 73 /id} It is now recognized that GABA also functions in a variety of organs outside of the CNS [1,3,4]. In the lung, a series of recent studies suggest that the GABAergic signaling system plays a role in the control of asthma related-airway constriction and mucin secretion [5-9]. In the context that goblet cell hyperplasia and mucin overproduction is associated with cigarette smoking [10-12], we hypothesized that components of the GABAergic system may also be altered in the airway epithelium of cigarette smokers. To assess this hypothesis, we evaluated the expression of the entire GABAergic system in the large and small airway epithelium of healthy nonsmokers and healthy smokers. The data demonstrates there is expression of genes for a complete GABAergic system in the airway epithelium. Interestingly, the expression of GAD67 was markedly modified by smoking, with increased expression in healthy smokers compared to healthy nonsmokers at the mRNA and protein levels. In the context that mucus overproduction is commonly associated with cigarette smoking, GAD67 may be a pharmacologic target for treatment of smoking-related disorders.
Smoking-mediated up-regulation of GAD67 expression in the human airway epithelium.
Sex, Age
View SamplesThe Wnt pathway plays a central role in controlling differentiation of epithelial tissues; when Wnt is on, differentiation is suppressed, but when Wnt is off, differentiation is allowed to proceed. Based on this concept, we hypothesized that expression of key genes in the Wnt pathway are suppressed in the human airway epithelium under the stress of cigarette smoking, a stress associated with dysregulation of the differentiated state of the airway epithelium. For this purpose, HG-U133 Plus 2.0 microarrays were used to assess the expression of Wnt-related genes in the small airway (10th-12th generation) epithelium (SAE) obtained via bronchoscopy and brushing of healthy nonsmokers (n=47), healthy smokers (n=58), and smokers with established COPD (n=22). With expression defined as present in >20% of samples, microarray analysis demonstrated that 35 of 57 known Wnt-related genes are expressed in the adult SAE. Wnt pathway downstream targets -catenin (p<0.05) and the transcription factor 7-like 1 were down-regulated in healthy smokers, and smokers with COPD, as were a number of Wnt target genes, including VEGFA, CCND1, MMP7, CLDN1, SOX9, RHOU (all p<0.05 compared to healthy nonsmokers). As a mechanism to explain this broad, smoking-induced suppression of the Wnt pathway, we assessed expression of the DKK and SFRP families, extracellular regulators that suppress the Wnt pathway. Among these, secreted frizzled-related protein 2 (SFRP2), was up-regulated 4.3-fold (p<0.0001) in healthy smokers and 4.9-fold (p<0.0001) in COPD smokers, an observation confirmed by TaqMan Real-time PCR. AT the protein levels, Western analysis demonstrated SFRP2 up-regulation, and immunohistochemistry demonstrated that the smoking-induced SFRP2 upregulation occurred in differentiated ciliated cells. Finally, cigarette smoke extract mediated up-regulation of SFRP2 and downregulation of Wnt target genes in airway epithelial cells in vitro. These observations are consistent with the hypothesis that the Wnt pathway plays a role in airway epithelial cell differentiation in the adult human airway epithelium, with smoking associated with down-regulation of Wnt pathway, contributing to the dysregulation of airway epithelial differentiation observed in the smoking-related airway disorders.
Down-regulation of the canonical Wnt β-catenin pathway in the airway epithelium of healthy smokers and smokers with COPD.
Sex, Age
View SamplesBackground: When exposed to specific stimuli, macrophages exhibit distinct activation programs, M1 and M2 polarization, that define macrophage function as inflammatory/immune effectors or anti-inflammatory/tissue remodeling cells, respectively. Due to their position on the lung epithelial surface, alveolar macrophages (AM) directly interact with environmental stimuli such as cigarette smoke, the major risk factor for the development of chronic obstructive pulmonary disease (COPD). Based on the current paradigm that, in response to smoking, AM contribute to both inflammatory and tissue remodeling processes in the lung relevant to the pathogenesis of COPD, we hypothesized that chronic exposure to cigarette smoking activates both the M1 and M2 polarization programs in AM. Methods and Findings: To assess this hypothesis, global transcriptional profiling with TaqMan confirmation and flow cytometry analysis was carried out on AM obtained by bronchoalveolar lavage of 24 healthy nonsmokers, 34 healthy smokers and 12 smokers with COPD to assess the expression of 41 M1 genes and 32 M2 genes in each group. Contrary to our expectations, while there was up-regulation of some genes typical for M2-related phenotypes, AM of healthy smokers exhibited substantial suppression of M1-related inflammatory/immune genes. These M1- and M2-related changes progressed with the development of smoking-induced lung disease, with AM of smokers with COPD exhibiting further down-regulation of M1-related genes accompanied with further up-regulation of some M2-related genes. Conclusion: The data demonstrates that the modifications of the AM transcriptome associated with smoking result in a unique phenotype characterized by reprogramming of AM towards M1-deactivated partially M2-polarized macrophages and suggests that, while AM likely contribute to smoking-induced tissue remodeling, the role of AM in the early pathogenesis of smoking-induced COPD in humans is not inflammatory. This concept is a departure from the conventional concept that AM-mediated inflammation participates in the early derangements of the lung induced by smoking, and suggests a novel paradigm for conceptualizing COPD and developing new approaches to prevent the development of smoking-induced lung disease.
Smoking-dependent reprogramming of alveolar macrophage polarization: implication for pathogenesis of chronic obstructive pulmonary disease.
Sex, Age
View SamplesThe toll-like receptors (TLRs) are important components of the respiratory epithelium host innate defense, enabling the airway surface to recognize and respond to a variety of insults in inhaled air. Based on the knowledge that smokers are more susceptible to pulmonary infection and the airway epithelium of smokers with chronic obstructive pulmonary disease (COPD) is characterized by bacterial colonization and acute exacerbation of airway infections, we assessed whether smoking alters the expression of TLRs in human small airway epithelium, the primary site of smoking-induced disease. Microarrays were used to survey the TLR family gene expression in small airway (10th-12th order) epithelium from healthy nonsmokers (n=60), healthy smokers (n=73) and smokers with COPD (n=36). Using the criteria of detection call of present in 50%, 6 of 10 TLRs (1, 2, 3, 4, 5 and 8) were expressed. Compared to nonsmokers, the most strikingly changed gene is TLR5, which down-regulated in healthy smokers (1.4-fold decrease, p<10-13) and in smokers with COPD (1.6-fold, p<10-14). TaqMan RT-PCR confirmed these observations. Bronchial biopsies immunofluorescence showed that TLR5 protein was expressed mainly on the apical side of the human airway epithelium and decreased in healthy smokers and smokers with COPD. In vitro studies showed that the level of TLR5 downstream genes, IL-6 and IL-8 were highly induced in TLR5 high-expressing cells compared to TLR5 low-expressing cells after flagellin exposure. In the context that TLR5 functions to recognize pathogens and activate innate immune responses, the smoking-induced down-regulation of TLR5 likely contributes to smoking-related susceptibility to airway infection.
Airway epithelial expression of TLR5 is downregulated in healthy smokers and smokers with chronic obstructive pulmonary disease.
Race
View SamplesTo help define the genes associated with mucus synthesis and secretion in the human small airway epithelium, we hypothesized that comparison of the transcriptomes of the small airway epithelium of individuals that express high vs low levels of MUC5AC, a major secretory mucin and the major component of airway mucus, could be used as a probe to identify the genes related to human small airway mucus production / secretion. Genome-wide comparison between healthy nonsmokers grouped as high MUC5AC expressors vs low MUC5AC expressors identified significantly up-regulated and down-regulated genes in the high vs low expressors. Based on the literature, genes in the up-regulated list were used to identify a 73 MUC5AC-associated core gene list with 9 categories: mucus components; mucus-producing cell differentiation-related transcription factor; mucus-producing cell differentiation-related pathway or mediator; post-translational modification of mucin; vesicle transport; endoplasmic reticulum stress-related; secretory granule-associated; mucus secretion-related regulator and mucus hypersecretory-related ion channel. The identification of the genes associated with increased small airway mucin production in humans should be useful in identifying therapeutic targets to treat small airway mucus hypersecretion.
Genes associated with MUC5AC expression in small airway epithelium of human smokers and non-smokers.
Specimen part, Race, Time
View SamplesEpidemiological studies have demonstrated that exposure to particulate matter (PM) ambient pollution has adverse effects on lung health, exacerbated by cigarette smoking. Fine airborne particles <2.5 m (PM2.5) are the most harmful of the urban pollutants, and the most closely linked to respiratory disease. Based on the knowledge that the small airway epithelium (SAE) plays a central role in pathogenesis of smoking-related lung disease, we hypothesized that elevated PM2.5 levels are associated with dysregulation of SAE gene expression.
Ambient Pollution-related Reprogramming of the Human Small Airway Epithelial Transcriptome.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Role of OSGIN1 in mediating smoking-induced autophagy in the human airway epithelium.
Specimen part, Race
View Samples