Conditional reprogramming of pediatric airway epithelial cells: A new human model to investigate early-life respiratory disorders

BACKGROUND

Airway epithelial cells (AEC) are quite difficult to access in newborns and infants. It is critically important to develop robust life-extended models to conduct translational studies in this age group. We propose the use of a recently described cell culture technology (conditionally reprogrammed cells-CRC) to generate continuous primary cell cultures from nasal and bronchial AEC of young children.

METHODS

We collected nasal and/or bronchial AEC from a total of 23 subjects of different ages including newborns/infants/toddlers (0-2 years; N = 9), school-age children (4-11 years; N = 6), and a group of adolescent/adult donors (N = 8). For CRC generation, we used conditioned medium from mitotically inactivated 3T3 fibroblasts and Rho-associated kinase (ROCK) inhibitor (Y-27632). Antiviral immune responses were studied using 25 key antiviral genes and protein production of type III epithelial interferon (IFN λ1) after double-stranded (ds) RNA exposure.

RESULTS

CRC derived from primary AEC of neonates/infants and young children exhibited: (i) augmented proliferative capacity and life extension, (ii) preserved airway epithelial phenotype after multiple passages, (iii) robust immune responses characterized by the expression of innate antiviral genes and parallel nasal/bronchial production of IFN λ1 after exposure to dsRNA, and (iv) induction of airway epithelial inflammatory and remodeling responses to dsRNA (eg, CXCL8 and MMP9).

CONCLUSION

Conditional reprogramming of AEC from young children is a feasible and powerful translational approach to investigate early-life airway epithelial immune responses in humans.

Nasopharyngeal microbiome in premature infants and stability during rhinovirus infection

RATIONALE

The nasopharyngeal (NP) microbiota of newborns and infants plays a key role in modulating airway inflammation and respiratory symptoms during viral infections. Premature (PM) birth modifies the early NP environment and is a major risk factor for severe viral respiratory infections. However, it is currently unknown if the NP microbiota of PM infants is altered relative to full-term (FT) individuals.

OBJECTIVES

To characterize the NP microbiota differences in preterm and FT infants during rhinovirus (RV) infection.

METHODS

We determined the NP microbiota of infants 6 months to ≤2 years of age born FT (n=6) or severely PM<32 weeks gestation (n=7). We compared microbiota composition in healthy NP samples and performed a longitudinal analysis during naturally occurring RV infections to contrast the microbiota dynamics in PM versus FT infants.

RESULTS

We observed significant differences in the NP bacterial community of PM versus FT. NP from PM infants had higher within-group dissimilarity (heterogeneity) relative to FT infants. Bacterial composition of NP samples from PM infants showed increased Proteobacteria and decreased in Firmicutes. There were also differences in the major taxonomic groups identified, including Streptococcus, Moraxella, and Haemophilus. Longitudinal data showed that these prematurity-related microbiota features persisted during RV infection.

CONCLUSIONS

PM is associated with NP microbiota changes beyond the neonatal stage. PM infants have an NP microbiota with high heterogeneity relative to FT infants. These prematurity-related microbiota features persisted during RV infection, suggesting that the NP microbiota of PM may play an important role in modulating airway inflammatory and immune responses in this vulnerable group.

Age-Related Effect of Viral-Induced Wheezing in Severe Prematurity

Premature children are prone to severe viral respiratory infections in early life, but the age at which susceptibility peaks and disappears for each pathogen is unclear. Methods: A retrospective analysis was performed of the age distribution and clinical features of acute viral respiratory infections in full-term and premature children, aged zero to seven years. Results: The study comprised of a total of 630 hospitalizations (n = 580 children). Sixty-seven percent of these hospitalizations occurred in children born full-term (>37 weeks), 12% in preterm (32-37 weeks) and 21% in severely premature children (<32 weeks). The most common viruses identified were rhinovirus (RV; 60%) and respiratory syncytial virus (RSV; 17%). Age-distribution analysis of each virus identified that severely premature children had a higher relative frequency of RV and RSV in their first three years, relative to preterm or full-term children. Additionally, the probability of RV- or RSV-induced wheezing was higher overall in severely premature children less than three years old. Conclusions: Our results indicate that the vulnerability to viral infections in children born severely premature is more specific for RV and RSV and persists during the first three years of age. Further studies are needed to elucidate the age-dependent molecular mechanisms that underlie why premature infants develop RV- and RSV-induced wheezing in early life.

Airway Secretory microRNAome Changes during Rhinovirus Infection in Early Childhood

BACKGROUND

Innate immune responses are fine-tuned by small noncoding RNA molecules termed microRNAs (miRs) that modify gene expression in response to the environment. During acute infections, miRs can be secreted in extracellular vesicles (EV) to facilitate cell-to-cell genetic communication. The purpose of this study was to characterize the baseline population of miRs secreted in EVs in the airways of young children (airway secretory microRNAome) and examine the changes during rhinovirus (RV) infection, the most common cause of asthma exacerbations and the most important early risk factor for the development of asthma beyond childhood.

METHODS

Nasal airway secretions were obtained from children (≤3 yrs. old) during PCR-confirmed RV infections (n = 10) and age-matched controls (n = 10). Nasal EVs were isolated with polymer-based precipitation and global miR profiles generated using NanoString microarrays. We validated our in vivo airway secretory miR data in an in vitro airway epithelium model using apical secretions from primary human bronchial epithelial cells (HBEC) differentiated at air-liquid interface (ALI). Bioinformatics tools were used to determine the unified (nasal and bronchial) signature airway secretory miRNAome and changes during RV infection in children.

RESULTS

Multiscale analysis identified four signature miRs comprising the baseline airway secretory miRNAome: hsa-miR-630, hsa-miR-302d-3p, hsa- miR-320e, hsa-miR-612. We identified hsa-miR-155 as the main change in the baseline miRNAome during RV infection in young children. We investigated the potential biological relevance of the airway secretion of hsa-mir-155 using in silico models derived from gene datasets of experimental in vivo human RV infection. These analyses confirmed that hsa-miR-155 targetome is an overrepresented pathway in the upper airways of individuals infected with RV.

CONCLUSIONS

Comparative analysis of the airway secretory microRNAome in children indicates that RV infection is associated with airway secretion of EVs containing miR-155, which is predicted in silico to regulate antiviral immunity. Further characterization of the airway secretory microRNAome during health and disease may lead to completely new strategies to treat and monitor respiratory conditions in all ages.

A novel dissociative steroid VBP15 reduces MUC5AC gene expression in airway epithelial cells but lacks the GRE mediated transcriptional properties of dexamethasone

Overproduction of secretory mucins contributes to morbidity/mortality in inflammatory lung diseases. Inflammatory mediators directly increase expression of mucin genes, but few drugs have been shown to directly repress mucin gene expression. IL-1β upregulates the MUC5AC mucin gene in part via the transcription factors NFκB while the glucocorticoid Dexamethasone (Dex) transcriptionally represses MUC5AC expression by Dex-activated GR binding to two GRE cis-sites in the MUC5AC promoter in lung epithelial cells. VBP compounds (ReveraGen BioPharma) maintain anti-inflammatory activity through inhibition of NFκB but exhibit reduced GRE-mediated transcriptional properties associated with adverse side-effects and thus have potential to minimize harmful side effects of long-term steroid therapy in inflammatory lung diseases. We investigated VBP15 efficacy as an anti-mucin agent in two types of airway epithelial cells and analyzed the transcription factor activity and promoter binding associated with VBP15-induced MUC5AC repression. VBP15 reduced MUC5AC mRNA abundance in a dose- and time-dependent manner similar to Dex in the presence or absence of IL-1β in A549 and differentiated human bronchial epithelial cells. Repression was abrogated in the presence of RU486, demonstrating a requirement for GR in the VBP15-induced repression of MUC5AC. Inhibition of NFκB activity resulted in reduced baseline expression of MUC5AC indicating that constitutive activity maintains MUC5AC production. Chromatin immunoprecipitation analysis demonstrated lack of GR and of p65 (NFκB) binding to composite GRE domains in the MUC5AC promoter following VBP15 exposure of cells, in contrast to Dex. These data demonstrate that VBP15 is a novel anti-mucin agent that mediates the reduction of MUC5AC gene expression differently than the classical glucocorticoid, Dex.

Proteomic Characterization of Middle Ear Fluid Confirms Neutrophil Extracellular Traps as a Predominant Innate Immune Response in Chronic Otitis Media

BACKGROUND

Chronic Otitis Media (COM) is characterized by middle ear effusion (MEE) and conductive hearing loss. MEE reflect mucus hypersecretion, but global proteomic profiling of the mucosal components are limited.

OBJECTIVE

This study aimed at characterizing the proteome of MEEs from children with COM with the goal of elucidating important innate immune responses.

METHOD

MEEs were collected from children (n = 49) with COM undergoing myringotomy. Mass spectrometry was employed for proteomic profiling in nine samples. Independent samples were further analyzed by cytokine multiplex assay, immunoblotting, neutrophil elastase activity, next generation DNA sequencing, and/or immunofluorescence analysis.

RESULTS

109 unique and common proteins were identified by MS. A majority were innate immune molecules, along with typically intracellular proteins such as histones and actin. 19.5% percent of all mapped peptide counts were from proteins known to be released by neutrophils. Immunofluorescence and immunoblotting demonstrated the presence of neutrophil extracellular traps (NETs) in every MEE, along with MUC5B colocalization. DNA found in effusions revealed unfragmented DNA of human origin.

CONCLUSION

Proteomic analysis of MEEs revealed a predominantly neutrophilic innate mucosal response in which MUC5B is associated with NET DNA. NETs are a primary macromolecular constituent of human COM middle ear effusions.

Middle Ear Response of Muc5ac and Muc5b Mucins to Nontypeable Haemophilus influenzae

IMPORTANCE

Chronic otitis media with effusion is characterized by middle ear secretion of mucin glycoproteins, predominantly MUC5B; MUC5AC, the other secretory mucin studied frequently, has also been identified in the middle ear. Emerging evidence suggests a dichotomous role for these mucins in innate immune responses. We hypothesized that MUC5AC is an acute responder and MUC5B is expressed at later time points, reflecting a chronic situation.

OBJECTIVE

To determine middle ear regulation of MUC5B and MUC5AC following in vitro bacterial and cytokine exposure.

DESIGN, SETTING, AND SAMPLES

An in vitro cell-based model of mucin gene regulation was conducted in a basic science laboratory at a tertiary pediatric hospital. The study was conducted from July 1, 2014, to June 30, 2015; data analysis was performed in July 2015.

INTERVENTIONS

Nontypeable Haemophilus influenzae (NTHi) lysates were generated and used to stimulate mouse middle ear epithelial cells (mMEECs) for 2 hours during 3 weeks.

MAIN OUTCOMES AND MEASURES

Real-time quantitative polymerase chain reaction, luciferase assays, Western blot assay, and immunofluorescence techniques were performed to determine Muc5ac and Muc5b expression over time, Cxcl2 chemokine response, and nuclear factor-κB activation. Luciferase reporter assays were performed to evaluate specific promoter responses after NTHi exposure.

RESULTS

Nontypeable H influenzae lysates (200 μg/mL) drove differential mucin gene activation, with Muc5ac being induced up to 2.04 fold at 24 hours and 2.79 fold at 96 hours (P < .05) and Muc5b being induced only at more long-term points: 1.61 fold at 96 hours, 1.41 fold at 1 week, and 1.53 fold at 3 weeks (P < .05). Although NTHi lysates induced robust, early nuclear factor-κB nuclear translocation with nuclear factor-κB-dependent induction of Cxlc2 expression, the lysates had minimal to no effect on Muc5ac and Muc5b promoter activity. However, in contrast to NTHi lysates, CXCL2 induced significant transcription of both Muc5b and Muc5ac as early as 24 hours.

CONCLUSIONS AND RELEVANCE

Nontypeable H influenzae lysates activate differential mucin gene activation in mMEECs. Although Muc5ac is an early response mucin gene, Muc5b appears to react as a chronic response mucin.

Human Metapneumovirus Infection is Associated with Severe Respiratory Disease in Preschool Children with History of Prematurity

BACKGROUND

Human metapneumovirus (HMPV) is a recently discovered respiratory pathogen of the family Paramyxoviridae, the same family as that of respiratory syncytial virus (RSV). Premature children are at high risk of severe RSV infections, however, it is unclear whether HMPV infection is more severe in hospitalized children with a history of severe prematurity.

METHODS

We conducted a retrospective analysis of the clinical respiratory presentation of all polymerase chain reaction-confirmed HMPV infections in preschool-age children (≤5 years) with and without history of severe prematurity (<32 weeks gestation). Respiratory distress scores were developed to examine the clinical severity of HMPV infections. Demographic and clinical variables were obtained from reviewing electronic medical records.

RESULTS

A total of 571 preschool children were identified using polymerase chain reaction-confirmed viral respiratory tract infection during the study period. HMPV was identified as a causative organism in 63 cases (11%). Fifty-eight (n = 58) preschool-age children with HMPV infection were included in this study after excluding those with significant comorbidities. Our data demonstrated that 32.7% of children admitted with HMPV had a history of severe prematurity. Preschool children with a history of prematurity had more severe HMPV disease as illustrated by longer hospitalizations, new or increased need for supplemental O2, and higher severity scores independently of age, ethnicity, and history of asthma.

CONCLUSION

Our study suggests that HMPV infection causes significant disease burden among preschool children with a history of prematurity leading to severe respiratory infections and increasing health care resource utilization due to prolonged hospitalizations.

Premature infants have impaired airway antiviral IFNγ responses to human metapneumovirus compared to respiratory syncytial virus

BACKGROUND

It is unknown why human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) cause severe respiratory infection in children, particularly in premature infants. Our aim was to investigate if there are defective airway antiviral responses to these viruses in young children with history of prematurity.

METHODS

Nasal airway secretions were collected from 140 children ≤ 3 y old without detectable virus (n = 80) or with PCR-confirmed HMPV or RSV infection (n = 60). Nasal protein levels of IFNγ, CCL5/RANTES, IL-10, IL-4, and IL-17 were determined using a multiplex magnetic bead immunoassay.

RESULTS

Full-term children with HMPV and RSV infection had increased levels of nasal airway IFNγ, CCL5, and IL-10 along with an elevation in Th1 (IFNγ)/Th2 (IL-4) ratios, which is expected during antiviral responses. In contrast, HMPV-infected premature children (< 32 wk gestation) did not exhibit increased Th1/Th2 ratios or elevated nasal airway secretion of IFNγ, CCL5, and IL-10 relative to uninfected controls.

CONCLUSION

Our study is the first to demonstrate that premature infants have defective IFNγ, CCL5/RANTES, and IL-10 airway responses during HMPV infection and provides novel insights about the potential reason why HMPV causes severe respiratory disease in children with history of prematurity.

Quantitative proteomics reveals an altered cystic fibrosis in vitro bronchial epithelial secretome

Alterations in epithelial secretions and mucociliary clearance contribute to chronic bacterial infection in cystic fibrosis (CF) lung disease, but whether CF lungs are unchanged in the absence of infection remains controversial. A proteomic comparison of airway secretions from subjects with CF and control subjects shows alterations in key biological processes, including immune response and proteolytic activity, but it is unclear if these are due to mutant CF transmembrane conductance regulator (CFTR) and/or chronic infection. We hypothesized that the CF lung apical secretome is altered under constitutive conditions in the absence of inflammatory cells and pathogens. To test this, we performed quantitative proteomics of in vitro apical secretions from air-liquid interface cultures of three life-extended CF (ΔF508/ΔF508) and three non-CF human bronchial epithelial cells after labeling of CF cells by stable isotope labeling with amino acids in cell culture. Mass spectrometry analysis identified and quantitated 666 proteins across samples, of which 70 exhibited differential enrichment or depletion in CF secretions (±1.5-fold change; P < 0.05). The key molecular functions were innate immunity (24%), cytoskeleton/extracellular matrix organization (24%), and protease/antiprotease activity (17%). Oxidative proteins and classical complement pathway proteins that are altered in CF secretions in vivo were not altered in vitro. Specific differentially increased proteins-MUC5AC and MUC5B mucins, fibronectin, and matrix metalloproteinase-9-were validated by antibody-based assays. Overall, the in vitro CF secretome data are indicative of a constitutive airway epithelium with altered innate immunity, suggesting that downstream consequences of mutant CFTR set the stage for chronic inflammation and infection in CF airways.

Development of glandular models from human nasal progenitor cells

Hyperplasia/hypertrophy of submucosal glands contributes to mucus overproduction in chronic diseases of the upper and lower respiratory tracts, especially in adult and pediatric chronic rhinosinusitis. Mechanisms that lead to glandular hyperplasia/hypertrophy are markedly understudied, reflecting a lack of in vitro model systems wherein airway epithelial progenitor cells differentiate into glandular cells. In this study, we developed and compared several in vitro three-dimensional systems using human nasal epithelial basal cells (HNEBCs) cultured by different methods on two types of extracellular matrices. We demonstrate that HNEBCs cultured on Matrigel (Corning, Tewksbury, MA) form glandular acini-like structures, whereas HNEBCs embedded in a collagen type I matrix form a network of tubules. Fibroblast-conditioned medium increases tubule formation in collagen type I. In contrast, HNEBCs cocultured with fibroblasts self-aggregate into organotypic structures with tubules and acini. These observations provide morphological evidence that HNEBCs are pluripotent and retain the capacity to differentiate into structures resembling specific structural components of submucosal glands depending on the extracellular matrices and culture conditions. The resultant models should prove useful in targeting cross-talk between epithelial cells and fibroblasts to decipher molecular mechanisms and specific signals responsible for the development of glandular hyperplasia/hypertrophy, which in turn may lead to new therapeutic strategies for chronic rhinosinusitis and other inflammatory respiratory diseases characterized by glandular hyperplasia/hypertrophy.

Rhinovirus-induced airway cytokines and respiratory morbidity in severely premature children

BACKGROUND

Rhinovirus (RV) has been linked to the pathogenesis of asthma. Prematurity is a risk factor for severe RV infection in early life, but is unknown if RV elicits enhanced pro-asthmatic airway cytokine responses in premature infants. This study investigated whether young children born severely premature (<32 wks gestation) exhibit airway secretion of Th2 and Th17 cytokines during natural RV infections and whether RV-induced Th2-Th17 responses are linked to more respiratory morbidity in premature children during the first 2 yrs of life.

METHODS

We measured Th2 and Th17 nasal airway cytokines in a retrospective cohort of young children aged 0-2 yrs with PCR-confirmed RV infection or non-detectable virus. Protein levels of IL-4, IL-13, TSLP, and IL-17 were determined with multiplex immunoassays. Demographic and clinical variables were obtained by electronic medical record (EMR) review.

RESULTS

The study comprised 214 children born full term (n = 108), preterm (n = 44) or severely premature (n = 62). Natural RV infection in severely premature children was associated with elevated airway secretion of Th2 (IL-4 and IL-13) and Th17 (IL-17) cytokines, particularly in subjects with history of bronchopulmonary dysplasia. Severely premature children with high RV-induced airway IL-4 had recurrent respiratory hospitalizations (median 3.65 hosp/yr; IQR 2.8-4.8) and were more likely to have at least one pediatric intensive care unit admission during the first 2 yrs of life (OR 8.72; 95% CI 1.3-58.7; p = 0.02).

CONCLUSIONS

Severely premature children have increased airway secretion of Th2 and Th17 cytokines during RV infections, which is associated with more respiratory morbidity in the first 2 yrs of life.

Directional secretory response of double stranded RNA-induced thymic stromal lymphopoetin (TSLP) and CCL11/eotaxin-1 in human asthmatic airways

BACKGROUND

Thymic stromal lymphoproetin (TSLP) is a cytokine secreted by the airway epithelium in response to respiratory viruses and it is known to promote allergic Th2 responses in asthma. This study investigated whether virally-induced secretion of TSLP is directional in nature (apical vs. basolateral) and/or if there are TSLP-mediated effects occurring at both sides of the bronchial epithelial barrier in the asthmatic state.

METHODS

Primary human bronchial epithelial cells (HBEC) from control (n = 3) and asthmatic (n = 3) donors were differentiated into polarized respiratory tract epithelium under air-liquid interface (ALI) conditions and treated apically with dsRNA (viral surrogate) or TSLP. Sub-epithelial effects of TSLP were examined in human airway smooth muscle cells (HASMC) from normal (n = 3) and asthmatic (n = 3) donors. Clinical experiments examined nasal airway secretions obtained from asthmatic children during naturally occurring rhinovirus-induced exacerbations (n = 20) vs. non-asthmatic uninfected controls (n = 20). Protein levels of TSLP, CCL11/eotaxin-1, CCL17/TARC, CCL22/MDC, TNF-α and CXCL8 were determined with a multiplex magnetic bead assay.

RESULTS

Our data demonstrate that: 1) Asthmatic HBEC exhibit an exaggerated apical, but not basal, secretion of TSLP after dsRNA exposure; 2) TSLP exposure induces unidirectional (apical) secretion of CCL11/eotaxin-1 in asthmatic HBEC and enhanced CCL11/eotaxin-1 secretion in asthmatic HASMC; 3) Rhinovirus-induced asthma exacerbations in children are associated with in vivo airway secretion of TSLP and CCL11/eotaxin-1.

CONCLUSIONS

There are virally-induced TSLP-driven secretory immune responses at both sides of the bronchial epithelial barrier characterized by enhanced CCL11/eotaxin-1 secretion in asthmatic airways. These results suggest a new model of TSLP-mediated eosinophilic responses in the asthmatic airway during viral-induced exacerbations.

Mitotic asynchrony induces transforming growth factor-β1 secretion from airway epithelium

We recently proposed that mitotic asynchrony in repairing tissue may underlie chronic inflammation and fibrosis, where immune cell infiltration is secondary to proinflammatory cross-talk among asynchronously repairing adjacent tissues. Building on our previous finding that mitotic asynchrony is associated with proinflammatory/fibrotic cytokine secretion (e.g., transforming growth factor [TGF]-β1), here we provide evidence supporting cause-and-effect. Under normal conditions, primary airway epithelial basal cell populations undergo mitosis synchronously and do not secrete proinflammatory or profibrotic cytokines. However, when pairs of nonasthmatic cultures were mitotically synchronized at 12 hours off-set and then combined, the mixed cell populations secreted elevated levels of TGF-β1. This shows that mitotic asynchrony is not only associated with but is also causative of TGF-β1 secretion. The secreted cytokines and other mediators from asthmatic cells were not the cause of asynchronous regeneration; synchronously mitotic nonasthmatic epithelia exposed to conditioned media from asthmatic cells did not show changes in mitotic synchrony. We also tested if resynchronization of regenerating asthmatic airway epithelia reduces TGF-β1 secretion and found that pulse-dosed dexamethasone, simvastatin, and aphidicolin were all effective. We therefore propose a new model for chronic inflammatory and fibrotic conditions where an underlying factor is mitotic asynchrony.

Directional secretomes reflect polarity-specific functions in an in vitro model of human bronchial epithelium

The polarity of the conducting airway epithelium is responsible for its directional secretion. This is an essential characteristic of lung integrity and function that dictates interactions between the external environment (apical) and subepithelial structures (basolateral). Defining the directional secretomes in the in vitro human bronchial epithelial (HBE) differentiated model could bring valuable insights into lung biology and pulmonary diseases. Normal primary HBE cells (n = 3) were differentiated into respiratory tract epithelium. Apical and basolateral secretions (24 h) were processed for proteome profiling and pathway analysis. A total of 243 proteins were identified in secretions from all HBE cultures combined. Of these, 51% were classified as secreted proteins, including true secreted proteins (36%) and exosomal proteins (15%). Close examination revealed consistent secretion of 69 apical proteins and 13 basolateral proteins and differential secretion of 25 proteins across all donors. Expression of Annexin A4 in apical secretions and Desmoglein-2 in basolateral secretions was validated using Western blot or ELISA in triplicate independent experiments. To the best of our knowledge, this is the first study defining apical and basolateral secretomes in the in vitro differentiated HBE model. The data demonstrate that epithelial polarity directs protein secretion with different patterns of biological processes to the apical and basolateral surfaces that are consistent with normal bronchial epithelium homeostatic functions. Applying this in vitro directional secretome model to lung diseases may elucidate their molecular pathophysiology and help define potential therapeutic targets.

IL-1β induction of MUC5AC gene expression is mediated by CREB and NF-κB and repressed by dexamethasone

Chronic airway diseases are characterized by inflammation and mucus overproduction. The MUC5AC mucin gene is upregulated by the proinflammatory cytokine interleukin-1 β (IL-1β) via activation of cAMP response element-binding protein (CREB) in the NCI-H292 cancer cell line and nuclear factor-κB (NF-κB) in the HBE1 transformed cell line, with each transcription factor binding to a cognate cis site in the proximal or distal region, respectively, of the MUC5AC promoter. We utilized primary differentiated human bronchial epithelial (HBE) and A549 lung adenocarcinoma cells to further investigate the contributions of CREB and NF-κB subunits to the IL-1β-induced upregulation of MUC5AC. Data show that ligand binding of IL-1β to the IL-1β receptor is required to increase MUC5AC mRNA abundance. Chromatin immunoprecipitation analyses show direct binding of CREB to the previously identified cAMP response element site and binding of p65 and p50 subunits to a novel NF-κB site in a mucin-regulatory domain in the proximal promoter and to a previously identified NF-κB site in the distal promoter. P50 binds to both NF-κB sites at 1 h following IL-1β exposure, but is replaced at 2 h by p65 in A549 cells and by a p50/p65 heterodimer in HBE cells. Thus IL-1β activates multiple domains in the MUC5AC promoter but exhibits some cell-specific responses, highlighting the complexity of MUC5AC transcriptional regulation. Data show that dexamethasone, a glucocorticoid that transcriptionally represses MUC5AC gene expression under constitutive conditions, also represses IL-1β-mediated upregulation of MUC5AC gene expression. A further understanding of mechanisms mediating MUC5AC regulation should lead to a honing of therapeutic approaches for the treatment of mucus overproduction in inflammatory lung diseases.

VBP15, a glucocorticoid analogue, is effective at reducing allergic lung inflammation in mice

Asthma is a chronic inflammatory condition of the lower respiratory tract associated with airway hyperreactivity and mucus obstruction in which a majority of cases are due to an allergic response to environmental allergens. Glucocorticoids such as prednisone have been standard treatment for many inflammatory diseases for the past 60 years. However, despite their effectiveness, long-term treatment is often limited by adverse side effects believed to be caused by glucocorticoid receptor-mediated gene transcription. This has led to the pursuit of compounds that retain the anti-inflammatory properties yet lack the adverse side effects associated with traditional glucocorticoids. We have developed a novel series of steroidal analogues (VBP compounds) that have been previously shown to maintain anti-inflammatory properties such as NFκB-inhibition without inducing glucocorticoid receptor-mediated gene transcription. This study was undertaken to determine the effectiveness of the lead compound, VBP15, in a mouse model of allergic lung inflammation. We show that VBP15 is as effective as the traditional glucocorticoid, prednisolone, at reducing three major hallmarks of lung inflammation—NFκB activity, leukocyte degranulation, and pro-inflammatory cytokine release from human bronchial epithelial cells obtained from patients with asthma. Moreover, we found that VBP15 is capable of reducing inflammation of the lung in vivo to an extent similar to that of prednisone. We found that prednisolone–but not VBP15 shortens the tibia in mice upon a 5 week treatment regimen suggesting effective dissociation of side effects from efficacy. These findings suggest that VBP15 may represent a potent and safer alternative to traditional glucocorticoids in the treatment of asthma and other inflammatory diseases.

The human secretome atlas initiative: implications in health and disease conditions

Proteomic analysis of human body fluids is highly challenging, therefore many researchers are redirecting efforts toward secretome profiling. The goal is to define potential biomarkers and therapeutic targets in the secretome that can be traced back in accessible human body fluids. However, currently there is a lack of secretome profiles of normal human primary cells making it difficult to assess the biological meaning of current findings. In this study we sought to establish secretome profiles of human primary cells obtained from healthy donors with the goal of building a human secretome atlas. Such an atlas can be used as a reference for discovery of potential disease associated biomarkers and eventually novel therapeutic targets. As a preliminary study, secretome profiles were established for six different types of human primary cell cultures and checked for overlaps with the three major human body fluids including plasma, cerebrospinal fluid and urine. About 67% of the 1054 identified proteins in the secretome of these primary cells occurred in at least one body fluid. Furthermore, comparison of the secretome profiles of two human glioblastoma cell lines to this new human secretome atlas enabled unambiguous identification of potential brain tumor biomarkers. These biomarkers can be easily monitored in different body fluids using stable isotope labeled standard proteins. The long term goal of this study is to establish a comprehensive online human secretome atlas for future use as a reference for any disease related secretome study. This article is part of a Special Issue entitled: An Updated Secretome.

Glucocorticoid receptor and histone deacetylase-2 mediate dexamethasone-induced repression of MUC5AC gene expression

Airway occlusion in obstructive airway diseases is caused in part by the overproduction of secretory mucin glycoproteins through the up-regulation of mucin (MUC) genes by inflammatory mediators. Some pharmacological agents, including the glucocorticoid dexamethasone (Dex), repress mucin concentrations in lung epithelial cancer cells. Here, we show that Dex reduces the expression of MUC5AC, a major airway mucin gene, in primary differentiated normal human bronchial epithelial (NHBE) cells in a dose-dependent and time-dependent manner, and that the Dex-induced repression is mediated by the glucocorticoid receptor (GR) and two glucocorticoid response elements (GREs) in the MUC5AC promoter. The pre-exposure of cells to RU486, a GR antagonist, and mutations in either the GRE3 or GRE5 cis-sites abolished the Dex-induced repression. Chromatin immunoprecipitation (ChIP) assays showed a rapid temporal recruitment of GR to the GRE3 and GRE5 cis-elements in the MUC5AC promoter in NHBE and in A549 cells. Immunofluorescence showed nuclear colocalization of GR and histone deacetylase-2 (HDAC2) in MUC5AC-expressing NHBE cells. ChIP also showed a rapid temporal recruitment of HDAC2 to the GRE3 and GRE5 cis-elements in the MUC5AC promoter in both cell types. The knockdown of HDAC2 by HDAC2-specific short interfering RNA prevented the Dex-induced repression of MUC5AC in NHBE and A549 cells. These data demonstrate that GR and HDAC2 are recruited to the GRE3 and GRE5 cis-sites in the MUC5AC promoter and mediate the Dex-induced cis repression of MUC5AC gene expression. A better understanding of the mechanisms whereby glucocorticoids repress MUC5AC gene expression may be useful in formulating therapeutic interventions in chronic lung diseases.

Δ-9,11 modification of glucocorticoids dissociates nuclear factor-κB inhibitory efficacy from glucocorticoid response element-associated side effects

Glucocorticoids are standard of care for many inflammatory conditions, but chronic use is associated with a broad array of side effects. This has led to a search for dissociative glucocorticoids--drugs able to retain or improve efficacy associated with transrepression [nuclear factor-κB (NF-κB) inhibition] but with the loss of side effects associated with transactivation (receptor-mediated transcriptional activation through glucocorticoid response element gene promoter elements). We investigated a glucocorticoid derivative with a Δ-9,11 modification as a dissociative steroid. The Δ-9,11 analog showed potent inhibition of tumor necrosis factor-α-induced NF-κB signaling in cell reporter assays, and this transrepression activity was blocked by 17β-hydroxy-11β-[4-dimethylamino phenyl]-17α-[1-propynyl]estra-4,9-dien-3-one (RU-486), showing the requirement for the glucocorticoid receptor (GR). The Δ-9,11 analog induced the nuclear translocation of GR but showed the loss of transactivation as assayed by GR-luciferase constructs as well as mRNA profiles of treated cells. The Δ-9,11 analog was tested for efficacy and side effects in two mouse models of muscular dystrophy: mdx (dystrophin deficiency), and SJL (dysferlin deficiency). Daily oral delivery of the Δ-9,11 analog showed a reduction of muscle inflammation and improvements in multiple muscle function assays yet no reductions in body weight or spleen size, suggesting the loss of key side effects. Our data demonstrate that a Δ-9,11 analog dissociates the GR-mediated transcriptional activities from anti-inflammatory activities. Accordingly, Δ-9,11 analogs may hold promise as a source of safer therapeutic agents for chronic inflammatory disorders.

Localization of inflammatory mediators in pediatric sinus mucosa

OBJECTIVES

Microarray analyses of sinus mucosa in pediatric patients with chronic rhinosinusitis (CRS) have recently demonstrated increased messenger RNA expression of the inflammatory chemokines CXCL5 and CXCL13 and of the innate immune mediators β-defensin 1 (DEFB1), serum amyloid A2 (SAA2), and serpin B4. The objectives of this study were to determine whether these gene products were expressed at the protein level in pediatric sinus mucosa and to determine their localization.

DESIGN

Immunohistochemical analysis was used to identify protein expression and cellular localization of CXCL5, CXCL13, DEFB1, SAA2, and serpin B4. Coimmunofluorescence staining of inflammatory cells was performed to further evaluate expression of CXCL5 and CXCL13.

SETTING

Pediatric tertiary care facility.

PATIENTS

Fifteen children with CRS who underwent endoscopic sinus surgery and 8 children who underwent craniofacial or neurosurgical procedures for abnormalities other than sinusitis.

MAIN OUTCOME MEASURES

Protein expression and cellular localization of CXCL5, CXCL13, DEFB1, SAA2, and serpin B4 in pediatric sinus mucosa.

RESULTS

Ciliated and basal cells in the pseudostratified epithelium stained positively for the 5 mediators examined in both cohorts. Except for serpin B4, goblet cells did not stain for any mediators in either cohort. Glandular cells stained positively for all 5 mediators in both cohorts. Coimmunofluorescence staining of inflammatory cells showed that CXCL13 was expressed in macrophages, T and B cells but not in neutrophils. CXCL5 was detected only in T cells.

CONCLUSIONS

CXCL5, CXCL13, DEFB1, SAA2, and serpin B4 were expressed at the protein level in the sinus mucosa of controls and pediatric patients with CRS and exhibited cell-specific localization. These mediators, not typically associated with pediatric CRS, may be involved in the inflammatory response and mucus hypersecretion seen in pediatric CRS.

MUC7 polymorphisms are associated with a decreased risk of a diagnosis of asthma in an African American population

PURPOSE

Mucin glycoproteins contribute to lung pathophysiology in asthma. The protein backbone of mucin glycoproteins is encoded by specific MUC genes, which exhibit a high degree of polymorphisms that generate a variable number of tandem repeat (VNTR) domains. MUC7 typically encodes for 6 VNTRs, each with 23 amino acids. In a northern European cohort, a polymorphism encoding MUC7*5 (5-VNTR) is in 100% linkage disequilibrium with the single nucleotide polymorphism rs9982010 and associated with a decreased risk of being asthmatic and having better lung function. African Americans have a 5- to 10-fold increase in incidence of asthma relative to whites, who are believed to be partially associated with higher genetic susceptibility. Occurrence of the rs9982010 and MUC7 allelic frequencies was evaluated in inner-city African Americans to test their association with a diagnosis of asthma.

METHODS

Genomic DNA, collected from a cohort of African American asthmatic subjects, was used to detect the MUC7 VNTR polymorphisms and to analyze the rs9982010 single nucleotide polymorphism.

RESULTS

A logistic regression analysis showed that the MUC7*5-VNTR allele decreased the likelihood of a diagnosis of asthma (odds ratio, 0.173 [95% confidence interval, 0.041-0.737]; P < 0.018) and is not in a strong linkage disequilibrium with the rs9982010 (r = 0.03; odds ratio, 66; confidence interval, 5.913-736.72). A novel MUC7*4-VNTR polymorphism, identified in an African American nonasthmatic individual, was linked to a structural rearrangement of the VNTR domain.

CONCLUSIONS

These data extend the association of MUC7*5 allelic polymorphisms and asthma to inner-city African Americans.

Histologic characteristics and mucin immunohistochemistry of cystic fibrosis sinus mucosa

OBJECTIVES

To evaluate the histologic characteristics of paranasal sinus mucosa of a disease control population and children with chronic rhinosinusitis and cystic fibrosis (CRS/CF) (1) to determine whether goblet cell (GC) hyperplasia and/or submucosal gland (SMG) hyperplasia occur in pediatric CRS/CF and (2) to compare expression and localization of MUC5AC and MUC5B mucins in the sinus mucosa of both cohorts.

DESIGN

Histologic and morphometric analyses of paranasal sinus mucosa were used to quantify the number of GCs and mucin-expressing cells. Digital imaging was used to evaluate the SMG area. Immunohistochemistry was performed to identify the cellular localization of MUC5AC and MUC5B mucins, and confocal microscopy was used to determine whether MUC5AC and MUC5B mucins were expressed in the same secretory cells.

SETTING

Children's National Medical Center, Washington, DC.

PARTICIPANTS

Twenty-one children with CRS/CF who underwent endoscopic sinus surgical procedures and 18 children who underwent craniofacial resection or neurosurgical procedures for abnormalities other than sinusitis.

RESULTS

A statistically significant increased area (4.4-fold) of SMGs was detected in the sinus mucosa of patients with CRS/CF compared with the controls (P = .02). Neither GC hyperplasia nor increased expression of MUC5AC was observed in the CRS/CF group. MUC5AC was expressed only in a subpopulation of GCs in both cohorts, and MUC5B was expressed in a subpopulation of GCs as well as in SMGs. There was a positive trend toward increased glandular MUC5B expression in the CRS/CF cohort. Colocalization of MUC5AC and MUC5B expression was observed in a subset of GCs.

CONCLUSIONS

Significant SMG hyperplasia and a trend toward increased glandular MUC5B expression exist in children with CRS/CF. This suggests that SMG hyperplasia and glandular MUC5B mucin contribute to mucus overproduction in the sinus mucosa of this population.

Human bronchial epithelial cells differentiate to 3D glandular acini on basement membrane matrix

To create a model system that investigates mechanisms resulting in hyperplasia and hypertrophy of respiratory tract submucosal glands, we developed an in vitro three-dimensional (3D) system wherein normal human bronchial epithelial (HBE) cells differentiated into glandular acini when grown on a basement membrane matrix. The differentiation of primary HBE cells into glandular acini was monitored temporally by light microscopy. Apoptosis-induced lumen formation was observed by immunofluorescence analysis. The acinar cells expressed and secreted MUC5B mucin (marker for glandular mucous cells) and lysozyme, lactoferrin, and zinc-α2-glycoprotein (markers for glandular serous cells) at Day 22. β-Tubulin IV, a marker for ciliated cells, was not detected. Expression of mucous and serous cell markers in HBE glandular acini demonstrated that HBE cells grown on a basement membrane matrix differentiated into acini that exhibit molecular characteristics of respiratory tract glandular acinar cells. Inhibition studies with neutralizing antibodies resulted in a marked decrease in size of the spheroids at Day 7, demonstrating that laminin (a major component of the basement membrane matrix), the cell surface receptor integrin α6, and the cell junction marker E-cadherin have functional roles in HBE acinar morphogenesis. No significant variability was detected in the average size of glandular acini formed by HBE cells from two normal individuals. These results demonstrated that this in vitro model system is reproducible, stable, and potentially useful for studies of glandular differentiation and hyperplasia.

Asthmatic airway epithelium is intrinsically inflammatory and mitotically dyssynchronous

Asthma is an inflammatory condition for which anti-inflammatory glucocorticoids are the standard of care. However, similar efficacy has not been shown for agents targeting inflammatory cells and pathways. This suggests a noninflammatory cell contributor (e.g., epithelium) to asthmatic inflammation. Herein, we sought to define the intrinsic and glucocorticoid-affected properties of asthmatic airway epithelium compared with normal epithelium. Human primary differentiated normal and asthmatic airway epithelia were cultured in glucocorticoid-free medium beginning at -48 hours. They were pulsed with dexamethasone (20 nM) or vehicle for 2 hours at -26, -2, +22, and +46 hours. Cultures were mechanically scrape-wounded at 0 hours and exposed continuously to bromodeoxyuridine (BrdU). Cytokine secretions were analyzed using cytometric bead assays. Wound regeneration/mitosis was analyzed by microscopy and flow cytometry. Quiescent normal (n = 3) and asthmatic (n = 6) epithelia showed similar minimal inflammatory cytokine secretion and mitotic indices. After wounding, asthmatic epithelia secreted more basolateral TGF-β1, IL-10, IL-13, and IL-1β (P < 0.05) and regenerated less efficiently than normal epithelia (+48 h wound area reduction = [mean ± SEM] 50.2 ± 7.5% versus 78.6 ± 7.7%; P = 0.02). Asthmatic epithelia showed 40% fewer BrdU(+) cells at +48 hours (0.32 ± 0.05% versus 0.56 ± 0.07% of total cells; P = 0.03), and those cells were more dyssynchronously distributed along the cell cycle (52 ± 10, 25 ± 4, 23 ± 7% for G1/G0, S, and G2/M, respectively) than normal epithelia (71 ± 1, 12 ± 2, and 17 ± 2% for G1/G0, S, and G2/M, respectively). Dexamethasone pulses improved asthmatic epithelial inflammation and regeneration/mitosis. In summary, we show that inflammatory/fibrogenic cytokine secretions are correlated with dyssynchronous mitosis upon injury. Intermittent glucocorticoids simultaneously decreased epithelial cytokine secretions and resynchronized mitosis. These data, generated in an airway model lacking inflammatory cells, support the concept that epithelium contributes to asthmatic inflammation.

Glandular gene expression of sinus mucosa in chronic rhinosinusitis with and without cystic fibrosis

Secretory cells in submucosal glands (SMGs) secrete antibacterial proteins and mucin glycoproteins into the apical lumen of the respiratory tract, and these are critical for innate immune mucosal integrity. Glandular hyperplasia is manifested in diseases with obstructive respiratory pathologies associated with mucous hypersecretion, and is predominant in the sinus mucosa of patients with chronic rhinosinusitis (CRS), cystic fibrosis (CF), and clinical symptoms of CRS. To gain insights into the molecular basis of SMG hyperplasia in CRS, gene expression microarray analyses were performed to identify the differences in global and specific gene expression in the sinus mucosa of control, CRS, and CRS/CF patients. A marked up-regulation of 11 glandular-associated genes in CRS and CRS/CF sinus mucosa was evident. The RNA and protein expressions of the four most highly up-regulated genes (DSG3, KRT14, PTHLH, and OTX2) were evaluated. An increased expression of DSG3, KRT14, and PTHLH was demonstrated at the mRNA and protein levels in both CRS and CRS/CF sinus mucosa, whereas the increased expression of OTX2 was evident only for CRS/CF sinus mucosa, implicating OTX2 as a CF-specific gene. Immunofluorescence analysis localized DSG3, PTHLH, and OTX2 to serous cells, and KRT14 to myoepithelial cells, in SMGs. Because glandular hyperplasia is a central histologic feature of CRS, the identification of overexpressed glandular genes in the sinus mucosa lays the groundwork for future studies of glandular hyperplasia, and may ultimately lead to the development of novel treatments for mucous hypersecretion in patients with CRS.

Increased poly(ADP-ribose) polymerase (PARP)-1 expression and activity are associated with inflammation but not goblet cell metaplasia in murine models of allergen-induced airway inflammation

Inflammation plays a key role in lung injury and in the pathogenesis of asthma. Two murine models of allergic airway inflammation-sensitization and challenge to ovalbumin (OVA) and intratracheal exposure to interleukin-13 (IL13)-were used to evaluate the expression of poly(ADP-ribose) polymerase-1 (PARP-1) in allergic airway inflammation. Inflammation is prominent in OVA-induced allergic asthma, but this inflammation is greatly reduced by a PARP-1 inhibitor and almost eliminated when PARP-1 knockout mice are subjected to the OVA model. The present study temporally evaluated PARP-1 protein expression, localization, and activity, as well as inflammation and goblet cell metaplasia (GCM), in murine lungs following a single OVA challenge or IL13 exposure. Following OVA challenge PARP-1 protein expression and activity were greatly increased, being maximal at 3 to 5 days following OVA exposure and beginning to decrease by day 8. These changes correlated with the timing and degree of inflammation and GCM. In contrast, PARP-1 protein or activity did not change following single IL13 exposure, though GCM was manifested without inflammation. This study demonstrates that both PARP-1 protein and activity are increased by allergen-activated inflammatory mediators, excluding IL13, and that PARP-1 increase does not appear necessary for GCM, one of the characteristic markers of allergic airway inflammation in murine models.

MUC5B Is the predominant mucin glycoprotein in chronic otitis media fluid

Chronic otitis media (COM), e.g. "glue" ear is characterized by middle ear effusion and conductive hearing loss. Although mucous glycoproteins (mucins), which contribute to increased effusion viscosity, have been analyzed in ear tissue specimens, no studies have been reported that characterize the molecular identity of secreted mucin proteins present in actual middle ear fluid. For this study, effusions from children with COM undergoing myringotomy at Children's National Medical Center, Washington, DC were collected. These were solubilized and gel fractionated, and the protein content was identified using a liquid chromatography tandem mass spectrometry (LC-MS/MS) proteomics approach. Western blot analyses with mucin specific antibodies and densitometry were performed to validate the mass spectrometry findings. LC-MS/MS results identified mucin MUC5B by >26 unique peptides in six of six middle ear effusion samples, whereas mucin MUC5AC was only identified in one of six middle ear effusions. These findings were validated by Western blot performed on the same six and on an additional 11 separate samples where densitometry revealed on average a 6.4-fold increased signal in MUC5B when compared with MUC5AC (p = 0.0009). In summary, although both MUC5AC and MUC5B mucins are detected in middle ear effusions, MUC5B seems to be predominant mucin present in COM secretions.

Cigarette smoke alters tissue inhibitor of metalloproteinase 1 and matrix metalloproteinase 9 levels in the basolateral secretions of human asthmatic bronchial epithelium in vitro

BACKGROUND

Asthma, a major cause of chronic lung disease worldwide, has increased in prevalence in all age and ethnic groups, particularly in urban areas where cigarette smoking is common. Cigarette smoke (CS) significantly impacts the development of asthma and is strongly associated with increased asthma-related morbidity.

PURPOSE

To evaluate bioinformatic analyses predicting that CS would alter expression of tissue inhibitor of metalloproteinase (TIMP) 1 and matrix metalloproteinase (MMP) 9 in asthmatic epithelium.

METHODS

Primary differentiated normal (n = 4) and asthmatic (n = 4) human respiratory epithelia on collagen-coated Transwells at air-liquid interface were exposed for 1 hour to CS condensate (CSC) or hydrogen peroxide (H2O2). Tissue inhibitor of metalloproteinase 1 and MMP-9 protein levels were measured at 24 hours by enzyme-linked immunosorbent assay in cell lysates and in apical and basolateral secretions.

RESULTS

Tissue inhibitor of metalloproteinase 1 and MMP-9 levels in the apical secretions of normal and asthmatic epithelia were unchanged after exposure to CSC and H2O2. However, CSC increased TIMP-1 levels in the basolateral secretions of both normal and asthmatic epithelia, but decreased MMP-9 levels only in asthmatic basolateral secretions, resulting in a 2.5-fold lower MMP-9/TIMP-1 ratio that corresponded to decreased MMP-9 activity in CS-exposed asthmatic basolateral secretions.

CONCLUSIONS

These data validate our prior bioinformatic analyses predicting that TIMP-1 plays a role in the stress response to CS and indicate that asthmatics exposed to CS may be more susceptible to MMP-9-mediated airway remodeling. This is in agreement with the current paradigm that a reduction in the MMP-9/TIMP-1 ratio is a milieu that favors subepithelial airway remodeling in chronic asthma.

Delineation of a gene network underlying the pulmonary response to oxidative stress in asthma

Cigarette smoke exposure induces a respiratory epithelial response that is mediated in part by oxidative stress. The contribution of oxidative stress to cigarette smoke-induced responses in asthmatic respiratory epithelium is not well understood. We sought to increase this understanding by employing data integration and systems biology approaches to publicly available microarray data deposited over the last several years. In this study, we analyzed 14 publicly available asthma- or tobacco-relevant data series and found 4 (2 mice and 2 human) that fulfilled adequate signal/noise thresholds using unsupervised clustering and F test statistics. Using significance filters and a 4-way Venn diagram approach, we identified 26 overlapping genes in the epithelial transcriptional stress response to cigarette smoke and asthma. This test set corresponded to a 26-member gene/protein network containing 18 members that were highly regulated in a fifth data series of direct lung oxidative stress. Of those network members, 2 stood out (ie, tissue inhibitor of metalloproteinase 1 and thrombospondin 1) owing to central location within the network and marked up-regulation sustained at later times in response to oxidative stress. These analyses identified key relationships and primary hypothetical targets for future studies of cigarette smoke-induced oxidative stress in asthma.

Delineation of a gene network underlying the pulmonary response to oxidative stress in asthma

Cigarette smoke exposure induces a respiratory epithelial response that is mediated in part by oxidative stress. The contribution of oxidative stress to cigarette smoke-induced responses in asthmatic respiratory epithelium is not well understood. We sought to increase this understanding by employing data integration and systems biology approaches to publicly available microarray data deposited over the last several years. In this study, we analyzed 14 publicly available asthma- or tobacco-relevant data series and found 4 (2 mice and 2 human) that fulfilled adequate signal/noise thresholds using unsupervised clustering and F test statistics. Using significance filters and a 4-way Venn diagram approach, we identified 26 overlapping genes in the epithelial transcriptional stress response to cigarette smoke and asthma. This test set corresponded to a 26-member gene/protein network containing 18 members that were highly regulated in a fifth data series of direct lung oxidative stress. Of those network members, 2 stood out (ie, tissue inhibitor of metalloproteinase 1 and thrombospondin 1) owing to central location within the network and marked up-regulation sustained at later times in response to oxidative stress. These analyses identified key relationships and primary hypothetical targets for future studies of cigarette smoke-induced oxidative stress in asthma.

Expression profiling of inflammatory mediators in pediatric sinus mucosa

OBJECTIVE

To evaluate gene expression by microarray analyses of inflammatory mediators in the sinus mucosa of children with and without chronic rhinosinusitis (CRS).

DESIGN

Prospective molecular genetics analysis.

SETTING

Children's National Medical Center, Washington, DC.

SUBJECTS

Eleven patients with CRS who underwent endoscopic sinus surgery and 10 control children who underwent craniofacial resection or neurosurgical procedures.

MAIN OUTCOME MEASURES

Gene expression levels of sinus tissue from 6 patients with CRS and 6 controls and messenger RNA expression levels of upregulated inflammatory/immune response genes, as well as cytokines of interest, determined by quantitative reverse transcription-polymerase chain reaction.

RESULTS

Gene expression using the Plier algorithm yielded the most consistent grouping of samples: 96 genes were significantly upregulated more than 2-fold, and 123 genes were downregulated by at least 50% in the CRS sinus tissues compared with controls (P < .05). GeneSpring analysis demonstrated significant changes in several ontology categories in the CRS samples, including inflammatory/immune response genes. The chemokines CXCL13 and CXCL5, serum amyloid A, serpin B4, and defensin beta1 were highly upregulated (> or =5-fold). Increased expression of these genes was validated by quantitative reverse transcription-polymerase chain reaction in an independent set of tissues. Expression levels of interleukins 5, 6, and 8 were similar in both cohorts; these results were validated by reverse transcription-polymerase chain reaction.

CONCLUSIONS

Microarray analyses of sinus mucosa in children with CRS showed an increased expression of inflammatory genes involved in innate and adaptive immune systems. This technology can be successfully used to identify genes implicated in the pathogenesis of pediatric CRS.

Localization and expression of MUC5B and MUC7 mucins in pediatric sinus mucosa

OBJECTIVES

The purpose of this study was to analyze the secretory cell population and distribution of MUC5B and MUC7 mucins in the sinus mucosa of pediatric patients with and without chronic rhinosinusitis (CRS).

METHODS

Sinus mucosal specimens were collected at surgery in a pediatric tertiary care facility. Histologic, immunohistochemical, and morphometric analyses were performed on sinus mucosa of 20 children with CRS and 7 children without CRS.

RESULTS

A significant increase in the area of submucosal glands was evident in the sinus mucosa of children with CRS as compared to controls. MUC5B and MUC7 mucins were expressed in the submucosal glands, as well as in goblet cells, in the sinus mucosa of both populations. No differences in MUC5B or MUC7 expression were observed when mucin expression was normalized to glandular area.

CONCLUSIONS

Children with CRS have an increased number of submucosal glands, indicating that glandular mucins contribute to mucus overproduction in CRS. MUC5B and MUC7 mucins, which have previously been considered only glandular mucins, are also expressed in goblet cells in the sinus mucosa.

Immunohistochemical analyses of MUC5AC mucin expression in sinus mucosa of children with sinusitis and controls

OBJECTIVES

The purpose of this study was to analyze MUC5AC protein expression in sinus mucosal specimens of children with and without chronic sinusitis.

METHODS

Morphometric, histologic, and immunohistochemical analyses were carried out on sinus mucosa of 7 children with chronic sinusitis and 6 children without sinusitis.

RESULTS

MUC5AC protein was expressed in a subset of goblet cells in the surface epithelium, but not in the submucosal glands in either pediatric population. The number of goblet cells that expressed MUC5AC mucin was not significantly different in patients with and without chronic sinusitis. All specimens had similar numbers of goblet cells in the surface epithelium.

CONCLUSIONS

The data demonstrate that neither goblet cell hyperplasia nor increased MUC5AC expression occurs in the sinus mucosa of children with chronic sinusitis. This suggests that in contrast to asthma, in which goblet cell hyperplasia is present in the lower respiratory tract, mucus hypersecretion in pediatric chronic sinusitis may involve other secretory cells, eg, submucosal glandular cells, and mucins secreted by these glandular cells.

Regulation of mucin genes in chronic inflammatory airway diseases

In this review, we summarize work over the past 15 years on mucin gene expression and regulation in the lung, as well as how mucin gene expression is altered in chronic lung diseases. This field owes a great debt to Carol Basbaum for her pioneering work in dissecting signaling pathways regulating mucin gene expression and for her tremendous energy in promoting the importance of understanding the basic pathogenic mechanisms that drive mucus overproduction in cystic fibrosis, chronic obstructive pulmonary disease, and asthma.

Dexamethasone-mediated repression of MUC5AC gene expression in human lung epithelial cells

Glucocorticoids regulate gene expression via binding of the ligand-activated glucocorticoid receptor (GR) to glucocorticoid-responsive elements (GRE) in target gene promoters. The MUC5AC gene, which encodes the protein backbone of an abundant secreted airway mucin, has several putative GRE cis-elements in its 5' sequence. Mechanism(s) whereby glucocorticoids regulate mucin genes have not previously been described. In this study, the glucocorticoid dexamethasone (Dex) decreased MUC5AC mRNA abundance in A549 and NCI-H292 cell lines and primary differentiated normal bronchial epithelial cells by 50-80%, suggesting a common mechanism of MUC5AC gene repression in human lung epithelial cells. Kinetic analyses showed that MUC5AC mRNA was not significantly decreased until 6 h after Dex exposure, and that nuclear translocation of GR was biphasic, suggesting that Dex-mediated cis-repression of MUC5AC gene expression was a delayed response of GR translocation. Transfection analyses demonstrated that Dex transcriptionally repressed the MUC5AC promoter. Electrophoretic mobility shift assays with wild-type and mutant oligonucleotide probes showed that GR bound to two GRE cis-sites (nucleotides -930 to -912 and -369 to -351) in the MUC5AC promoter. Analyses of mutated MUC5AC promoter constructs demonstrated that NF-kappaB cis-sites were not involved in Dex-mediated repression of MUC5AC. Dex did not alter mRNA stability of MUC5AC transcripts. Taken together, the data indicate that Dex transcriptionally mediates repression of MUC5AC gene expression in human lung epithelial cells at quiescent states after binding of GR to one or more GRE cis-elements in the MUC5AC promoter.

Temporal analysis of goblet cells and mucin gene expression in murine models of allergic asthma

In murine models of allergic asthma, mice repeatedly exposed to allergens or interleukin (IL)13 have numerous goblet cells in their airway epithelium, in contrast to healthy naïve mice. This study evaluated whether a single airway exposure of ovalbumin or IL13 would produce goblet cell metaplasia. Following ovalbumin challenge, airway goblet cells were present by 1 day, increased further by day 2 and day 3, and decreased by day 8. Following IL13 exposure, some goblet cells were detected at 6 hours and increased by 18 and 48 hours. Goblet transition cells, which are morphologically but not histologically similar to goblet cells, were observed at 6 and 18 hours following IL13 exposure and day 1 following ovalbumin challenge. Increased Muc5ac and Muc2 mRNA expression occurred following ovalbumin or IL13, but not saline, exposure. Mucin transcripts were localized to goblet cells in the surface airway epithelium. Muc5ac protein was expressed in some goblet transition and goblet cells. Overall, these data demonstrated that a single airway exposure to ovalbumin or IL13 is sufficient to generate goblet cell metaplasia and thus increase mucin gene expression in two strains of mice.

Model systems for investigating mucin gene expression in airway diseases

Overproduction of mucus and of mucin glycoproteins and goblet cell hyperplasia occurs in chronic obstructive airway diseases, including asthma and cystic fibrosis. Mucus overproduction results from alterations in several cellular processes, including altered regulation of airway mucin genes on exposure to environmental and infectious agents and to inflammatory mediators. Seven of the nine identified MUC genes (which encode the protein backbone of mucins) are normally expressed in human respiratory tract tissues. Several inflammatory mediators have now been shown to regulate expression of MUC2, MUC5AC, and MUC5B genes. Importantly, mucin gene expression can be regulated both transcriptionally and posttranscriptionally. Current information on airway mucin gene expression is summarized in this review along with an overview of airway epithelial model systems. In vitro model systems include airway epithelial carcinoma cell lines and primary normal human bronchial epithelial (NHBE) cells. In vivo systems include human respiratory tract tissues and rodent airways. Our laboratory has begun to investigate the role of cytokines on mucin gene expression in vitro and in vivo and on goblet cell metaplasia in vivo. Because cytokines can alter cell proliferation, we characterized the effect of interleukin (IL)-4 and IL-13 on the proliferation of NHBE cells and three human lung carcinoma cell lines--A549, NCI-H292, and Calu-3--that are frequently used for analyses of airway mucin gene expression. Both IL-4 and IL-13 had cell-specific effects. They increased proliferation moderately (1.2-3.0-fold) in NHBE and Calu-3 cells, but markedly inhibited proliferation of A549 cells in a dose-dependent manner. IL-4 increased proliferation of NCI-H292 cells moderately, although IL-13 had no significant effect. We also examined the role of IL-13 and IL-4 on MUC5AC messenger RNA (mRNA) expression in A549, Calu-3, and H292 cell lines and did not observe any significant effect. However, we recently showed an increase in Muc-5ac mRNA and protein expression in a murine model of ovalbumin-induced allergic asthma and in murine airways when IL-13 was delivered intranasally (Alimam, N.Z., et al. Am J. Respir. Cell Mol. Biol. 22:253--260). Thus, we speculate that IL-13 plays a role in the differentiation of murine airway epithelial cells into goblet cells, which then express Muc-5ac mRNA. A detailed analysis of the role of cytokines in airway cell differentiation and mucin gene expression both in vitro and in vivo is required to elucidate the roles of mucins in airway health and diseases. Identification of Muc-5ac as a major gene and gene product in goblet cell metaplasia should facilitate delineation of the molecular mechanisms underlying the induction and reversal of airway goblet cell metaplasia and goblet cell hyperplasia.

Muc-5/5ac mucin messenger RNA and protein expression is a marker of goblet cell metaplasia in murine airways

Airway inflammation, hyperreactivity, increased number of goblet cells, and mucus overproduction characterize asthma. Respiratory challenge with ovalbumin (OVA) of sensitized mice has been shown by several laboratories to cause pulmonary pathology similar to that observed in human allergic asthma. Recently, interleukin (IL)-13 has been shown to be a central mediator in this process. Because the airways of healthy mice have few, if any, mucus-producing cells, an increase in the number of these cells likely reflects induction of mucin-gene expression. The purpose of this study was to identify mucin genes induced as a result of airway goblet-cell metaplasia (GCM) in mice sensitized and challenged with OVA or in mice treated with IL-13 alone. BALB/c mice were sensitized by intraperitoneal injection (Days 0, 4, 7, 11, and 14) and intranasal instillation (Day 14) of 100 microg of OVA in saline, and then challenged by intranasal instillation (Days 25, 26, and 27) of the same. IL-13-treated mice received 5 microg of IL-13 by intranasal instillation on three consecutive days. Control mice were given saline alone. All mice were studied 24 h after the last challenge. Histologic analysis of the lungs revealed both a striking peribronchial and perivascular lymphocytic and eosinophilic inflammation and airway GCM in OVA-treated mice, and also airway GCM without inflammation in IL-13-treated mice. Northern blot analysis of lung RNA demonstrated (1) expression of Muc-5/5ac messenger RNA (mRNA) in OVA-treated and IL-13-treated mice, but not in control mice; (2) expression of Muc-1 mRNA at comparable levels in all mice regardless of treatment; and (3) no expression of Muc-2 or Muc-3 mRNA in control or treated mice. Western blot analysis demonstrated the expression of Muc-5/5ac protein (both apomucin and glycosylated mucin) in lung lysates of OVA-treated (but not control) mice, and also the expression of Muc-5/5ac mucins in the bronchoalveolar lavage fluid of OVA-treated and IL-13-treated mice. These findings demonstrate that airway GCM is associated with the induction of pulmonary expression of Muc-5/5ac mRNA and mucin in murine models of allergic asthma.

Neutrophil elastase increases MUC5AC mRNA and protein expression in respiratory epithelial cells

Chronic neutrophil-predominant inflammation and hypersecretion of mucus are common pathophysiological features of cystic fibrosis, chronic bronchitis, and viral- or pollution-triggered asthma. Neutrophils release elastase, a serine protease, that causes increased mucin production and secretion. The molecular mechanisms of elastase-induced mucin production are unknown. We hypothesized that as part of this mechanism, elastase upregulates expression of a major respiratory mucin gene, MUC5AC. A549, a human lung carcinoma cell line that expresses MUC5AC mRNA and protein, and normal human bronchial epithelial cells in an air-liquid interface culture were stimulated with neutrophil elastase. Neutrophil elastase increased MUC5AC mRNA levels in a time-dependent manner in both cell culture systems. Neutrophil elastase treatment also increased MUC5AC protein levels in A549 cells. The mechanism of MUC5AC gene regulation by elastase was determined in A549 cells. The induction of MUC5AC gene expression required serine protease activity; other classes of proteases had no effect on MUC5AC gene expression. Neutrophil elastase increased MUC5AC mRNA levels by enhancing mRNA stability. This is the first report of mucin gene regulation by this mechanism.

Respiratory carcinoma cell lines. MUC genes and glycoconjugates

Lung carcinoma cell lines are being used in many laboratories to study various airway epithelial functions, including mucin gene expression. To identify model systems for investigating regulation of MUC5/5AC gene expression and secretion of MUC5/5AC mucins in airway epithelial cells, we evaluated the expression of several mucin genes in six carcinoma cell lines of respiratory tract origin. RNA was extracted from A549, Calu-3, NCI H292, Calu-6, RPMI 2650, and A-427 cells; MUC1, MUC2, MUC4, MUC5/5AC, and MUC5B messenger RNA (mRNA) expression was determined. By Northern analyses, all cell lines expressed MUC1 mRNA, whereas MUC2 mRNA was not detectable in any of the cell lines. RPMI 2650 cell lines expressed only MUC1 mRNA. NCI-H292 cells expressed MUC4 and low levels of MUC5/5AC mRNA. Calu-3 and A549 cells expressed MUC5/5AC mRNA; A549 cells also expressed MUC5B mRNA. Glycoconjugates secreted by lung carcinoma cells were also examined. By wheat germ lectin analysis, Calu-3, H292, and A549 cells secreted high molecular weight glycoproteins having N-acetylglucosamine and/or sialic acid moieties. Western blot analyses with an anti-MUC5:TR-3A antibody demonstrated that Calu-3 and A549 cells secreted MUC5/5AC mucins. All six carcinoma cell lines secreted large, radiolabeled, sulfated macromolecules; the majority were proteoglycans that were digested by hyaluronidase. However, Calu-3 cells also secreted sulfated high molecular-weight glycoproteins that were immunoprecipitated by anti-MUC5:TR-3A antibody. These studies demonstrated that Calu-3 and A549 cell lines expressed high and moderate amounts of MUC5/5AC mRNA and MUC5/5AC mucins, whereas H292 cells expressed lesser amounts. These cell lines should prove useful for studies of MUC5/5AC gene expression and MUC5/5AC biosynthesis, trafficking, and secretions in airway epithelial cells.

Mucin gene expression (MUC1, MUC2, and MUC5/5AC) in nasal epithelial cells of cystic fibrosis, allergic rhinitis, and normal individuals

The early pathogenic events in cystic fibrosis (CF) include colonization of Pseudomonas in the lung, airway inflammation, and mucus hypersecretion with airway obstruction. The primary mechanisms leading to chronic infection and inflammation are not well understood. One possible explanation for this cascade of events is increased or altered expression of one or more mucin (MUC) genes by CF cells in the respiratory tract. We compared expression levels of three mucin genes, MUC1, MUC2, and MUC5/5AC, known to be expressed in the respiratory tract of CF, allergic rhinitis, and normal individuals. Mucin transcript levels in nasal epithelial cells free from inflammation were quantitated by an MUC mRNA slot-blot method. This study revealed three major findings: (1) MUC5/5AC mRNA was expressed at five- to tenfold greater levels than MUC2 or MUC1 for all subjects. (2) MUC2 mRNA levels were similar among all subject groups. (3) In CF subjects, there was a trend toward reduced MUC5/5AC expression. When normalized to the levels of MUC2 expression in individual specimens, MUC5/5AC expression was reduced significantly in CF cells compared with normal cells. These data suggest that mucin gene expression is altered in noninflamed CF nasal cells.

Factitious post traumatic stress disorder: a case report

A 24-year-old man presented with a convincing history of Post Traumatic Stress Disorder (PTSD). He claimed to be the victim of a widely publicized 'human bomb' attack by the IRA in Northern Ireland when he was serving with the armed forces. Psychometric tests for PTSD confirmed his symptoms. A subsequent check of public and military records demonstrated that he was a serviceman at that time, but showed conclusively that he could not have been present at the terrorist incident.