Nasal epithelial cells can act as a physiological surrogate for paediatric asthma studies

Upper Airway Alarmin Cytokine Expression in Asthma of Different Severities

Background: The secretion of alarmin cytokines by epithelial cells, including thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33, initiates inflammatory cascades in asthma. However, alarmin cytokine expression in the upper airways in asthma remains largely unknown. Methods: We recruited 40 participants with asthma into four groups as per the Global Initiative for Asthma (GINA) steps (10 in each group of GINA 1/2, 3, 4, and 5). Cells were derived from nasal, buccal, and throat brushings. Intracellular cytokine expression (TSLP, IL-25, and IL-33) was assessed by flow cytometry in cytokeratin 8+ (Ck8+) epithelial cells immediately following collection. Results: TSLP was significantly increased (p < 0.001) in GINA 5 patients across nasal, buccal, and throat Ck8+ epithelial cells, while IL-25 was elevated in nasal and throat samples (p < 0.003), and IL-33 levels were variable, compared with GINA 1-4 patients. Individual GINA subgroup comparison showed that TSLP levels in nasal samples from GINA 5 patients were significantly (p = 0.03) elevated but did not differ between patients with and without nasal comorbidities. IL-25 and IL-33 (obtained from nasal, buccal, and throat samples) were not significantly different in individual groups. Conclusions: Our study demonstrates for the first time that Ck8+ nasal epithelial cells from GINA 5 asthma patients express elevated levels of TSLP.

Emissions from plastic incineration induce inflammation, oxidative stress, and impaired bioenergetics in primary human respiratory epithelial cells

Inhalation exposure to plastic incineration emissions (PIEs) is a problem of increasing human relevance, as plastic production and waste creation have drastically increased since mainstream integration during the 20th century. We investigated the effects of PIEs on human nasal epithelial cells (HNECs) to understand if such exposures cause damage and dysfunction to respiratory epithelia. Primary HNECs from male and female donors were cultured at air-liquid interface (ALI), and 16HBE cells were cultured on coverslips. Smoke condensates were generated from incineration of plastic at flaming (640°C) and smoldering (500°C) temperatures, and cells were subsequently exposed to these materials at 5-50 μg/cm2 concentrations. HNECs were assessed for mitochondrial dysfunction and 16HBE cells for glutathione oxidation in real-time analyses. HNEC culture supernatants and total RNA were collected at 4-h postexposure for cytokine and gene expression analysis, and results show that PIEs can acutely induce inflammation, oxidative stress, and mitochondrial dysfunction in HNECs, and that incineration temperature modifies biological responses. Specifically, condensates from flaming and smoldering PIEs significantly increased HNEC secretion of cytokines IL-8, IL-1β, and IL-13, as well as expression of xenobiotic metabolism pathways and genes such as CYP1A1 and CYP1B1 at 5 and 20 μg/cm2 concentrations. Only 50 μg/cm2 flaming PIEs significantly increased glutathione oxidation in 16HBEs, and decreased respiration and ATP production in HNEC mitochondria. Impact Statement: Our data reveal the impact of incineration temperatures on biological outcomes associated with PIE exposures, emphasizing the importance of temperature as a factor when evaluating respiratory disease associated with PIEs exposure.

How to use an in vitro approach to characterize the toxicity of airborne compounds

As part of the development of new approach methodologies (NAMs), numerous in vitro methods are being developed to characterize the potential toxicity of inhalable xenobiotics (gases, volatile organic compounds, polycyclic aromatic hydrocarbons, particulate matter, nanoparticles). However, the materials and methods employed are extremely diverse, and no single method is currently in use. Method standardization and validation would raise trust in the results and enable them to be compared. This four-part review lists and compares biological models and exposure methodologies before describing measurable biomarkers of exposure or effect. The first section emphasizes the importance of developing alternative methods to reduce, if not replace, animal testing (3R principle). The biological models presented are mostly to cultures of epithelial cells from the respiratory system, as the lungs are the first organ to come into contact with air pollutants. Monocultures or cocultures of primary cells or cell lines, as well as 3D organotypic cultures such as organoids, spheroids and reconstituted tissues, but also the organ(s) model on a chip are examples. The exposure methods for these biological models applicable to airborne compounds are submerged, intermittent, continuous either static or dynamic. Finally, within the restrictions of these models (i.e. relative tiny quantities, adhering cells), the mechanisms of toxicity and the phenotypic markers most commonly examined in models exposed at the air-liquid interface (ALI) are outlined.

Development and validation of asthma risk prediction models using co-expression gene modules and machine learning methods

Asthma is a heterogeneous respiratory disease characterized by airway inflammation and obstruction. Despite recent advances, the genetic regulation of asthma pathogenesis is still largely unknown. Gene expression profiling techniques are well suited to study complex diseases including asthma. In this study, differentially expressed genes (DEGs) followed by weighted gene co-expression network analysis (WGCNA) and machine learning techniques using dataset generated from airway epithelial cells (AECs) and nasal epithelial cells (NECs) were used to identify candidate genes and pathways and to develop asthma classification and predictive models. The models were validated using bronchial epithelial cells (BECs), airway smooth muscle (ASM) and whole blood (WB) datasets. DEG and WGCNA followed by least absolute shrinkage and selection operator (LASSO) method identified 30 and 34 gene signatures and these gene signatures with support vector machine (SVM) discriminated asthmatic subjects from controls in AECs (Area under the curve: AUC = 1) and NECs (AUC = 1), respectively. We further validated AECs derived gene-signature in BECs (AUC = 0.72), ASM (AUC = 0.74) and WB (AUC = 0.66). Similarly, NECs derived gene-signature were validated in BECs (AUC = 0.75), ASM (AUC = 0.82) and WB (AUC = 0.69). Both AECs and NECs based gene-signatures showed a strong diagnostic performance with high sensitivity and specificity. Functional annotation of gene-signatures from AECs and NECs were enriched in pathways associated with IL-13, PI3K/AKT and apoptosis signaling. Several asthma related genes were prioritized including SERPINB2 and CTSC genes, which showed functional relevance in multiple tissue/cell types and related to asthma pathogenesis. Taken together, epithelium gene signature-based model could serve as robust surrogate model for hard-to-get tissues including BECs to improve the molecular etiology of asthma.

Angiotensin converting enzyme 2 activation improves allergic rhinitis and suppresses Th2 cytokine release

OBJECTIVE

Allergic rhinitis (AR) is primarily regulated by type I hypersensitivity, with Th2 and immunoglobulin E (IgE) playing essential roles. This study aimed to determine whether angiotensin converting enzyme (ACE)2 could participate in the regulation of AR.

METHODS

Nasal mucosal tissues of AR patients were collected to determine ACE2 levels. Following AR mouse models were established, ACE2 levels in nasal mucosa were determined. Then the influences of diminazene aceturate (ACE2 agonist) on AR symptoms, pathology, specific antibodies, histamine, and interleukins (ILs) release in vivo were evaluated. Afterward, human nasal mucosa epithelial cells were exposed to IL-13, and the impacts of ACE2 overexpression on the secretion of pro-inflammatory factors in vitro were assessed.

RESULTS

ACE2 levels significantly declined in nasal mucosa both in patients and mouse models (p < .001). Diminazene aceturate treatment elevated the ACE2 level in mice (p < .01), accompanied by reduced frequency of nasal spray and nasal friction, decreased eosinophils and goblet cells (p < .001) according to histopathological staining. Furthermore, lgE, lgG1, histamine, and IL levels in mice were also decreased (p < .05). In vitro experiments revealed that ACE2 overexpression suppressed the secretion of pro-inflammatory factors (p < .001).

CONCLUSION

Together, ACE2 activation can alleviate the symptoms of AR in mice and inhibit the release of Th2 cytokines. Activating ACE2 is a promising therapeutic approach for AR.

Temporal Whole-Transcriptomic Analysis of Characterized In Vitro and Ex Vivo Primary Nasal Epithelia

Air-liquid interface (ALI) cell culture of primary airway progenitors enables the differentiation and recapitulation of a pseudostratified epithelium in vitro, providing a highly useful tool for researching respiratory health and disease. Previous studies into gene expression in ALI-cultures compared to ex vivo nasal brushings have been limited in the number of time-points and/or the number of genes studied. In this study physiological and global transcriptomic changes were assessed in an extended in vitro 63-day human healthy nasal epithelium ALI-culture period and compared to ex vivo nasal brushing samples. Ex vivo nasal brushing samples formed distinct transcriptome clusters to in vitro ALI-cultured nasal epithelia, with from day 14 onwards ALI samples best matching the ex vivo samples. Immune response regulation genes were not expressed in the in vitro ALI-culture compared to the ex vivo nasal brushing samples, likely because the in vitro cultures lack an airway microbiome, lack airborne particles stimulation, or did not host an immune cell component. This highlights the need for more advanced co-cultures with immune cell representation to better reflect the physiological state. During the first week of ALI-culture genes related to metabolism and proliferation were increased. By the end of week 1 epithelial cell barrier function plateaued and multiciliated cell differentiation started, although widespread ciliation was not complete until day 28. These results highlight that time-points at which ALI-cultures are harvested for research studies needs to be carefully considered to suit the purpose of investigation (transcriptomic and/or functional analysis).

Distinct Secretion of MUC5AC and MUC5B in Upper and Lower Chronic Airway Diseases

The human airway is protected by a defensive mucus barrier. The most prominent components of mucus are the mucin glycoproteins MUC5AC and MUC5B. They are produced by goblet cells and submucosal gland cells in the upper and lower airways. Hyperplasia of these cells and hypersecretion of MUC5AC and MUC5B characterize chronic inflammatory diseases of the upper and lower airways. Recent studies have revealed that MUC5AC and MUC5B are expressed at specific sites in the respiratory tract through different molecular mechanisms and have distinct functions. Morphometric and histochemical studies have also examined the roles of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in different chronic airway diseases individually. The individual study of goblet cells, submucosal gland cells, MUC5AC, and MUC5B in airway diseases would be helpful for precisely diagnosing chronic inflammatory diseases of the airway and establishing optimal treatments. This review focuses on the distinct secretion of MUC5AC and MUC5B and their producing cells in chronic inflammatory diseases of the upper and lower airway.

Susceptibility of Human Airway Tissue Models Derived From Different Anatomical Sites to Bordetella pertussis and Its Virulence Factor Adenylate Cyclase Toxin

To study the interaction of human pathogens with their host target structures, human tissue models based on primary cells are considered suitable. Complex tissue models of the human airways have been used as infection models for various viral and bacterial pathogens. The Gram-negative bacterium Bordetella pertussis is of relevant clinical interest since whooping cough has developed into a resurgent infectious disease. In the present study, we created three-dimensional tissue models of the human ciliated nasal and tracheo-bronchial mucosa. We compared the innate immune response of these models towards the B. pertussis virulence factor adenylate cyclase toxin (CyaA) and its enzymatically inactive but fully pore-forming toxoid CyaA-AC^-. Applying molecular biological, histological, and microbiological assays, we found that 1 µg/ml CyaA elevated the intracellular cAMP level but did not disturb the epithelial barrier integrity of nasal and tracheo-bronchial airway mucosa tissue models. Interestingly, CyaA significantly increased interleukin 6, interleukin 8, and human beta defensin 2 secretion in nasal tissue models, whereas tracheo-bronchial tissue models were not significantly affected compared to the controls. Subsequently, we investigated the interaction of B. pertussis with both differentiated primary nasal and tracheo-bronchial tissue models and demonstrated bacterial adherence and invasion without observing host cell type-specific significant differences. Even though the nasal and the tracheo-bronchial mucosa appear similar from a histological perspective, they are differentially susceptible to B. pertussis CyaA in vitro. Our finding that nasal tissue models showed an increased innate immune response towards the B. pertussis virulence factor CyaA compared to tracheo-bronchial tissue models may reflect the key role of the nasal airway mucosa as the first line of defense against airborne pathogens.

Residential PM2.5 exposure and the nasal methylome in children

RATIONALE

PM_2.5-induced adverse effects on respiratory health may be driven by epigenetic modifications in airway cells. The potential impact of exposure duration on epigenetic alterations in the airways is not yet known.

OBJECTIVES

We aimed to study associations of fine particulate matter PM_2.5 exposure with DNA methylation in nasal cells.

METHODS

We conducted nasal epigenome-wide association analyses within 503 children from Project Viva (mean age 12.9 y), and examined various exposure durations (1-day, 1-week, 1-month, 3-months and 1-year) prior to nasal sampling. We used residential addresses to estimate average daily PM_2.5 at 1 km resolution. We collected nasal swabs from the anterior nares and measured DNA methylation (DNAm) using the Illumina MethylationEPIC BeadChip. We tested 719,075 high quality autosomal CpGs using CpG-by-CpG and regional DNAm analyses controlling for multiple comparisons, and adjusted for maternal education, household smokers, child sex, race/ethnicity, BMI z-score, age, season at sample collection and cell-type heterogeneity. We further corrected for bias and genomic inflation. We tested for replication in a cohort from the Netherlands (PIAMA).

RESULTS

In adjusted analyses, we found 362 CpGs associated with 1-year PM_2.5 (FDR < 0.05), 20 CpGs passing Bonferroni correction (P < 7.0x10^-8) and 10 Differentially Methylated Regions (DMRs). In 445 PIAMA participants (mean age 16.3 years) 11 of 203 available CpGs replicated at P < 0.05. We observed differential DNAm at/near genes implicated in cell cycle, immune and inflammatory responses. There were no CpGs or regions associated with PM_2.5 levels at 1-day, 1-week, or 1-month prior to sample collection, although 2 CpGs were associated with past 3-month PM_2.5.

CONCLUSION

We observed wide-spread DNAm variability associated with average past year PM_2.5 exposure but we did not detect associations with shorter-term exposure. Our results suggest that nasal DNAm marks reflect chronic air pollution exposure.

Nasal Epithelial Cell-Based Models for Individualized Study in Cystic Fibrosis

The emergence of highly effective CFTR modulator therapy has led to significant improvements in health care for most patients with cystic fibrosis (CF). For some, however, these therapies remain inaccessible due to the rarity of their individual CFTR variants, or due to a lack of biologic activity of the available therapies for certain variants. One proposed method of addressing this gap is the use of primary human cell-based models, which allow preclinical therapeutic testing and physiologic assessment of relevant tissue at the individual level. Nasal cells represent one such tissue source and have emerged as a powerful model for individual disease study. The ex vivo culture of nasal cells has evolved over time, and modern nasal cell models are beginning to be utilized to predict patient outcomes. This review will discuss both historical and current state-of-the art use of nasal cells for study in CF, with a particular focus on the use of such models to inform personalized patient care.

New Laboratory Protocol to Determine the Oxidative Stress Profile of Human Nasal Epithelial Cells Using Flow Cytometry

Several studies have shown the importance of oxidative stress (OS) in respiratory disease pathogenesis. It has been reported that the nasal epithelium may act as a surrogate for the bronchial epithelium in several respiratory diseases involving OS. However, the sample yields obtained from nasal biopsies are modest, limiting the number of parameters that can be determined. Flow cytometry has been widely used to evaluate cellular OS profiles. It has the advantage that analyses can be performed using a small amount of sample. Therefore, we aimed to set up a new method based on flow cytometry to assess the oxidative profile of human nasal epithelial cells which could be used in research on respiratory diseases. Levels of total nitric oxide, superoxide anion, peroxynitrite, and intracellular peroxides were measured. Reduced thiol levels, such as antioxidant-reduced glutathione and oxidative damaged lipids and proteins, were also analysed. The intracellular calcium levels, plasma membrane potential, apoptosis, and percentage of live cells were also studied. Finally, a strategy to evaluate the mitochondrial function, including mitochondrial hydrogen peroxide, superoxide anion, mitochondrial mass, and membrane potential, was set up. Using small amounts of sample and a non-invasive sampling technique, the described method enables the measurement of a comprehensive set of OS parameters in nasal epithelial cells, which could be useful in research on respiratory diseases.

From Submerged Cultures to 3D Cell Culture Models: Evolution of Nasal Epithelial Cells in Asthma Research and Virus Infection

Understanding the response to viral infection in the context of respiratory diseases is of significant importance. Recently, there has been more focus on the role of the nasal epithelium in disease modeling. Here, we provide an overview of different submerged, organotypic 3D and spheroid cell culture models of nasal epithelial cells, which were used to study asthma and allergy with a special focus on virus infection. In detail, this review summarizes the importance, benefits, and disadvantages of patient-derived cell culture models of nasal- and bronchial epithelial cells, including a comparison of these cell culture models and a discussion on why investigators should consider using nasal epithelial cells in their research. Exposure experiments, simple virus transduction analyses as well as genetic studies can be performed in these models, which may provide first insights into the complexity of molecular signatures and may open new doors for drug discovery and biomarker research.

Downregulation of miR-96-5p Inhibits mTOR/NF-κb Signaling Pathway via DEPTOR in Allergic Rhinitis

BACKGROUND

This study aims to investigate the regulatory effect of microRNA-96-5p (miR-96-5p) in the pathophysiological process of allergic rhinitis (AR).

METHODS

Nasal mucosal tissue samples were collected from AR patients and healthy controls. An in vitro AR model was established by stimulating human nasal epithelial cells (HNECs) with interleukin (IL)-13. The expressions of target genes and proteins were measured by qPCR, Western blot, or ELISA. Dual-luciferase reporter assay and pull-down assay were performed to confirm the interaction between miR-96-5p and DEP domain-containing mammalian target of rapamycin-interacting protein (DEPTOR).

RESULTS

The level of miR-96-5p was increased while the expression of DEPTOR was decreased in AR patients. The expressions of proinflammatory cytokines were markedly increased and the mammalian target of rapamycin (mTOR)/NF-κB pathway was activated in HNECs following IL-13 stimulation. miR-96-5p downregulation alleviated the stimulated function by IL-13. DEPTOR was the target of miR-96-5p. Knockdown of DEPTOR reversed the function of miR-96-5p inhibitor on IL-13-stimulated HNECs.

CONCLUSIONS

The current study showed that miR-96-5p and DEPTOR were aberrantly expressed in AR nasal mucosa. miR-96-5p knockdown inhibited the production of inflammatory cytokines and the activation of mTOR/NF-κB pathway via targeting DEPTOR. These findings suggested that miR-96-5p might be used as a diagnostic marker and therapeutic target for the treatment of AR.

The Utility of Resolving Asthma Molecular Signatures Using Tissue-Specific Transcriptome Data

An integrative analysis focused on multi-tissue transcriptomics has not been done for asthma. Tissue-specific DEGs remain undetected in many multi-tissue analyses, which influences identification of disease-relevant pathways and potential drug candidates. Transcriptome data from 609 cases and 196 controls, generated using airway epithelium, bronchial, nasal, airway macrophages, distal lung fibroblasts, proximal lung fibroblasts, CD4+ lymphocytes, CD8+ lymphocytes from whole blood and induced sputum samples, were retrieved from Gene Expression Omnibus (GEO). Differentially regulated asthma-relevant genes identified from each sample type were used to identify (a) tissue-specific and tissue-shared asthma pathways, (b) their connection to GWAS-identified disease genes to identify candidate tissue for functional studies, (c) to select surrogate sample for invasive tissues, and finally (d) to identify potential drug candidates via connectivity map analysis. We found that inter-tissue similarity in gene expression was more pronounced at pathway/functional level than at gene level with highest similarity between bronchial epithelial cells and lung fibroblasts, and lowest between airway epithelium and whole blood samples. Although public-domain gene expression data are limited by inadequately annotated per-sample demographic and clinical information which limited the analysis, our tissue-resolved analysis clearly demonstrated relative importance of unique and shared asthma pathways, At the pathway level, IL-1b signaling and ERK signaling were significant in many tissue types, while Insulin-like growth factor and TGF-beta signaling were relevant in only airway epithelial tissue. IL-12 (in macrophages) and Immunoglobulin signaling (in lymphocytes) and chemokines (in nasal epithelium) were the highest expressed pathways. Overall, the IL-1 signaling genes (inflammatory) were relevant in the airway compartment, while pro-Th2 genes including IL-13 and STAT6 were more relevant in fibroblasts, lymphocytes, macrophages and bronchial biopsies. These genes were also associated with asthma in the GWAS catalog. Support Vector Machine showed that DEGs based on macrophages and epithelial cells have the highest and lowest discriminatory accuracy, respectively. Drug (entinostat, BMS-345541) and genetic perturbagens (KLF6, BCL10, INFB1 and BAMBI) negatively connected to disease at multi-tissue level could potentially repurposed for treating asthma. Collectively, our study indicates that the DEGs, perturbagens and disease are connected differentially depending on tissue/cell types. While most of the existing literature describes asthma transcriptome data from individual sample types, the present work demonstrates the utility of multi-tissue transcriptome data. Future studies should focus on collecting transcriptomic data from multiple tissues, age and race groups, genetic background, disease subtypes and on the availability of better-annotated data in the public domain.

House Dust Mite Exposure Causes Increased Susceptibility of Nasal Epithelial Cells to Adenovirus Infection

Adenovirus (AdV) infections in the respiratory tract may cause asthma exacerbation and allergic predisposition, and the house dust mite (HDM) may aggravate virus-induced asthma exacerbations. However, the underlying mechanisms of whether and how AdV affects asthmatic patients remains unclear. To address this question, we investigated nasal epithelial cells (NAEPCs) derived from a pediatric exacerbation study cohort for experimental analyses. We analyzed twenty-one different green-fluorescent protein- and luciferase-tagged AdV types in submerged 2D and organotypic 3D cell culture models. Transduction experiments revealed robust transduction of AdV type 5 (AdV5) in NAEPCs, which was associated with an increased uptake of AdV5 in the presence of HDM. In healthy and asthmatic NAEPCs exposed to HDM before infection, we observed a time- and dose-dependent increase of AdV5 uptake associated with upregulation of entry receptors for AdV5. Furthermore, electron microscopic and histologic analyses of 3D cell cultures revealed an impairment of the respiratory cilia after HDM exposition. This ex vivo pilot study shows the impact of AdV infection and HDM exposition in a primary cell culture model for asthma.

Epithelial-macrophage-dendritic cell interactions impact alarmins expression in asthma and COPD

In the respiratory system macrophages and dendritic cells collaborate as sentinels against foreign particulate antigens. The study used a triple-cell co-culture model, utilizing nasal epithelial cells, along with: monocyte derived macrophages (moMφs), and monocyte derived DCs (moDCs). Cell cultures from 15 controls, 14 asthma and 11 COPD patients were stimulated with IL-13 and poly I:C for 24 h. Co-cultivation of epithelial cells with moMφs and moDCs increased TSLP level only in asthma and the effect of IL-13 and poly I:C stimulation differed in all groups. Asthma epithelial cells expressed higher level of receptors TSLPR, ST2 and IL-17RA than controls and increased number of ST2 + ciliated and IL17RA + secretory cells. Cytokine expression in respiratory epithelium may be influenced by structural and immunological cell interaction. TSLP pathway may be associated with secretory, while IL-33 with ciliated cells. The impaired function of respiratory epithelium may impact cell-to-cell interactions in asthma.

Strong correlation between air-liquid interface cultures and in vivo transcriptomics of nasal brush biopsy

Air-liquid interface (ALI) cultures are ex vivo models that are used extensively to study the epithelium of patients with chronic respiratory diseases. However, the in vitro conditions impose a milieu different from that encountered in the patient in vivo, and the degree to which this alters gene expression remains unclear. In this study we employed RNA sequencing to compare the transcriptome of fresh brushings of nasal epithelial cells with that of ALI-cultured epithelial cells from the same patients. We observed a strong correlation between cells cultured at the ALI and cells obtained from the brushed nasal epithelia: 96% of expressed genes showed similar expression profiles, although there was greater similarity between the brushed samples. We observed that while the ALI model provides an excellent representation of the in vivo airway epithelial transcriptome for mechanistic studies, several pathways are affected by the change in milieu.

A thymic stromal lymphopoietin polymorphism may provide protection from asthma by altering gene expression

BACKGROUND

Genome-wide association studies have identified associations of the single nucleotide polymorphism rs1837253 in the thymic stromal lymphopoietin (TSLP) gene with asthma, allergic disease and eosinophilia. The TSLP gene encodes two isoforms, long and short, and previous studies have indicated functional differences between these two isoforms.

OBJECTIVE

We investigated the expression of these TSLP isoforms in response to a pro-inflammatory signal, and the role of the rs1837253 genotype in gene isoform regulation.

METHODS

We cultured nasal epithelial cells of asthmatic and non-asthmatic subjects and evaluated poly(I:C)-induced TSLP protein secretion using multiplex protein assays and gene expression profiles of the TSLP isoforms, and related genes using real-time qPCR. We correlated these profiles with rs1837253 genotype.

RESULTS

Asthmatic nasal epithelial cells exhibited increased TSLP protein secretion compared with nasal epithelial cells from healthy controls. The long TSLP isoform was more responsive to poly(I:C) stimulation. Additionally, the minor T allele of rs1837253 was less inducible than the major C allele, suggesting differential regulation; this may explain the "protective" effects of the T allele in asthma.

CONCLUSION

Our results provide important insights into the differential regulation and function of TSLP isoforms, including the role of TSLP rs1837253 polymorphisms in allergic inflammatory processes.

CLINICAL RELEVANCE

The key finding on the influence of TSLP genetic variation on disease expression/endotype could provide basis for investigation into targeted biologics for anti-TSLP therapies.

An optimized, robust and reproducible protocol to generate well-differentiated primary nasal epithelial models from extremely premature infants

Extremely premature infants are prone to severe respiratory infections, and the mechanisms underlying this exceptional susceptibility are largely unknown. Nasal epithelial cells (NEC) represent the first-line of defense and adult-derived ALI cell culture models show promising results in mimicking in vivo physiology. Therefore, the aim of this study was to develop a robust and reliable protocol for generating well-differentiated cell culture models from NECs of extremely premature infants. Nasal brushing was performed in 13 extremely premature infants at term corrected age and in 11 healthy adult controls to obtain NECs for differentiation at air-liquid interface (ALI). Differentiation was verified using imaging and functional analysis. Successful isolation and differentiation was achieved for 5 (38.5%) preterm and 5 (45.5%) adult samples. Preterm and adult ALI-cultures both showed well-differentiated morphology and ciliary function, however, preterm cultures required significantly longer cultivation times for acquiring full differentiation (44 ± 3.92 vs. 23 ± 1.83 days; p < 0.0001). Moreover, we observed that recent respiratory support may impair successful NECs isolation. Herewithin, we describe a safe, reliable and reproducible method to generate well-differentiated ALI-models from NECs of extremely premature infants. These models provide a valuable foundation for further studies regarding immunological and inflammatory responses and respiratory disorders in extremely premature infants.

Rhinovirus-16 induced temporal interferon responses in nasal epithelium links with viral clearance and symptoms

BACKGROUND

The temporal in vivo response of epithelial cells to a viral challenge and its association with viral clearance and clinical outcomes has been largely unexplored in asthma.

OBJECTIVE

To determine gene expression profiles over time in nasal epithelial cells (NECs) challenged in vivo with rhinovirus-16 (RV16) and compare to nasal symptoms and viral clearance.

METHODS

Patients with stable mild to moderate asthma (n = 20) were challenged intranasally with RV16. Nasal brush samples for RNA sequencing were taken 7 days prior to infection and 3, 6 and 14 days post-infection, and blood samples 4 days prior to infection and day 6 post-infection. Viral load was measured in nasal lavage fluid at day 3, 6 and 14.

RESULTS

Top differentially (>2.5-fold increase) expressed gene sets in NECs post-RV16 at days 3 and 6, compared with baseline, were interferon alpha and gamma response genes. Patients clearing the virus within 6 days (early resolvers) had a significantly increased interferon response at day 6, whereas those having cleared the virus by day 14 (late resolvers) had significantly increased responses at day 3, 6 and 14. Interestingly, patients not having cleared the virus by day 14 (non-resolvers) had no enhanced interferon responses at any of these days. The daily Cold Symptom Scores (CSS) peaked at days 3 to 5 and correlated positively with interferon response genes at day 3 (R = 0.48), but not at other time-points. Interferon response genes were also enhanced in blood at day 6 after RV16 challenge.

CONCLUSION AND CLINICAL RELEVANCE

This study shows that viral load and clearance varies markedly over time in mild to moderate asthma patients exposed to a fixed RV16 dose. The host's nasal interferon response to RV16 at day 3 is associated with upper respiratory tract symptoms. The temporal interferon response in nasal epithelium associates with viral clearance in the nasal compartment.

Airway Epithelial Derived Cytokines and Chemokines and Their Role in the Immune Response to Respiratory Syncytial Virus Infection

The airway epithelium is the primary target of respiratory syncytial virus infection. It is an important component of the antiviral immune response. It contributes to the recruitment and activation of innate immune cells from the periphery through the secretion of cytokines and chemokines. This paper provides a broad review of the cytokines and chemokines secreted from human airway epithelial cell models during respiratory syncytial virus (RSV) infection based on a comprehensive literature review. Epithelium-derived chemokines constitute most inflammatory mediators secreted from the epithelium during RSV infection. This suggests chemo-attraction of peripheral immune cells, such as monocytes, neutrophils, eosinophils, and natural killer cells as a key function of the epithelium. The reports of epithelium-derived cytokines are limited. Recent research has started to identify novel cytokines, the functions of which remain largely unknown in the wider context of the RSV immune response. It is argued that the correct choice of in vitro models used for investigations of epithelial immune functions during RSV infection could facilitate greater progress in this field.

Development of a Novel ex vivo Nasal Epithelial Cell Model Supporting Colonization With Human Nasal Microbiota

The nasal mucosa provides first line defense against inhaled pathogens while creating a unique microenvironment for bacterial communities. Studying the impact of microbiota in the nasal cavity has been difficult due to limitations with current models including explant cultures, primary cells, or neoplastic cell lines. Most notably, none have been shown to support reproducible colonization by bacterial communities from human donors. Therefore, to conduct controlled studies of the human nasal ecosystem, we have developed a novel ex vivo mucosal model that supports bacterial colonization of a cultured host mucosa created by immortalized human nasal epithelial cells (NEC). For this model, immortalized NEC established from 5 male and 5 female donors were cultured with an air-interfaced, apical surface on a porous transwell membrane. NEC were grown from nasal turbinate tissues harvested from willed bodies or from discarded tissue collected during sinonasal procedures. Immortalized cells were evaluated through molecular verification of cell type, histological confirmation of tissue differentiation including formation of tight junctions, NEC multilayer viability, metabolism, physiology and imaging of the luminal surface by scanning electron microscopy. Results showed proper differentiation and multilayer formation at seven to 10 days after air interface that was maintained for up to 3 weeks. The optimized mucosal cultures created an environment necessary to sustain colonization by nasal microbiomes (NMBs) that were collected from healthy volunteers, cryogenically preserved and characterized with customized quantitative polymerase chain reaction (qPCR) arrays. Polymicrobial communities of nasal bacteria associated with healthy and inflamed states were consistently reproduced in matured NEC co-cultures by transplant of NMBs from multiple community types. The cultured NMBs were stable after an initial period of bacterial replication and equilibration. This novel ex vivo culture system is the first model that supports controlled cultivation of NMBs, allowing for lab-based causation studies and further experimentation to explore the complexities of host-microbe and microbe-microbe interactions.

A novel in vitro model of primary human pediatric lung epithelial cells

BACKGROUND

Current in vitro human lung epithelial cell models derived from adult tissues may not accurately represent all attributes that define homeostatic and disease mechanisms relevant to the pediatric lung.

METHODS

We report methods for growing and differentiating primary Pediatric Human Lung Epithelial (PHLE) cells from organ donor infant lung tissues. We use immunohistochemistry, flow cytometry, quantitative RT-PCR, and single cell RNA sequencing (scRNAseq) analysis to characterize the cellular and transcriptional heterogeneity of PHLE cells.

RESULTS

PHLE cells can be expanded in culture up to passage 6, with a doubling time of ~4 days, and retain attributes of highly enriched epithelial cells. PHLE cells can form resistant monolayers, and undergo differentiation when placed at air-liquid interface. When grown at Air-Liquid Interface (ALI), PHLE cells expressed markers of airway epithelial cell lineages. scRNAseq suggests the cultures contained 4 main sub-phenotypes defined by expression of FOXJ1, KRT5, MUC5B, and SFTPB. These cells are available to the research community through the Developing Lung Molecular Atlas Program Human Tissue Core.

CONCLUSION

Our data demonstrate that PHLE cells provide a novel in vitro human cell model that represents the pediatric airway epithelium, which can be used to study perinatal developmental and pediatric disease mechanisms.

A 3D Human Airway Model Enables Prediction of Respiratory Toxicity of Inhaled Drugs In Vitro

Respiratory tract toxicity represents a significant cause of attrition of inhaled drug candidates targeting respiratory diseases. One of the key issues to allow early detection of respiratory toxicities is the lack of reliable and predictive in vitro systems. Here, the relevance and value of a physiologically relevant 3D human airway in vitro model (MucilAir) were explored by repeated administration of a set of compounds with (n = 8) or without (n = 7) respiratory toxicity following inhalation in vivo. Predictability for respiratory toxicity was evaluated by readout of cytotoxicity, barrier integrity, viability, morphology, ciliary beating frequency, mucociliary clearance and cytokine release. Interestingly, the data show that in vivo toxicity can be predicted in vitro by studying cell barrier integrity by transepithelial electrical resistance (TEER), and cell viability determined by the Resazurin method. Both read-outs had 88% sensitivity and 100% specificity, respectively, while the former was more accurate with receiver operating characteristic (ROC) AUC of 0.98 (p = .0018) compared with ROC AUC of 0.90 (p = .0092). The loss of cell barrier integrity could mainly, but not fully, be attributed to a loss of cell coverage in 6 out of 7 compounds with reduced TEER. Notably, these effects occurred only at 400 µM, at concentration levels significantly above primary target cell potency, suggesting that greater attention to high local lung concentrations should be taken into account in safety assessment of inhaled drugs. Thus, prediction of respiratory toxicity in 3D human airway in vitro models may result in improved animal welfare and reduced attrition in inhaled drug discovery projects.

Characterisation of morphological differences in well-differentiated nasal epithelial cell cultures from preterm and term infants at birth and one-year

BACKGROUND

Innate immune responses of airway epithelium are important defences against respiratory pathogens and allergens. Newborn infants are at greater risk of severe respiratory infections compared to older infants, while premature infants are at greater risk than full term infants. However, very little is known regarding human neonatal airway epithelium immune responses and whether age-related morphological and/or innate immune changes contribute to the development of airway disease.

METHODS

We collected nasal epithelial cells from 41 newborn infants (23 term, 18 preterm) within 5 days of birth. Repeat sampling was achieved for 24 infants (13 term, 11 preterm) at a median age of 12.5 months. Morphologically- and physiologically-authentic well-differentiated primary paediatric nasal epithelial cell (WD-PNEC) cultures were generated and characterised using light microscopy and immunofluorescence.

RESULTS

WD-PNEC cultures were established for 15/23 (65%) term and 13/18 (72%) preterm samples at birth, and 9/13 (69%) term and 8/11 (73%) preterm samples at one-year. Newborn and infant WD-PNEC cultures demonstrated extensive cilia coverage, mucous production and tight junction integrity. Newborn WD-PNECs took significantly longer to reach full differentiation and were noted to have much greater proportions of goblet cells compared to one-year repeat WD-PNECs. No differences were evident in ciliated/goblet cell proportions between term- and preterm-derived WD-PNECs at birth or one-year old.

CONCLUSION

We describe the successful generation of newborn-derived WD-PNEC cultures and their revival from frozen. We also compared the characteristics of WD-PNECs derived from infants born at term with those born prematurely at birth and at one-year-old. The development of WD-PNEC cultures from newborn infants provides a powerful and exciting opportunity to study the development of airway epithelium morphology, physiology, and innate immune responses to environmental or infectious insults from birth.

Brushed nasal epithelial cells are a surrogate for bronchial epithelial CFTR studies

Recent advances in the management of cystic fibrosis (CF) target underlying defects in the CF transmembrane conductance regulator (CFTR) protein, but efficacy analyses remain limited to specific genotype-based subgroups. Patient-derived model systems may therefore aid in expanding access to these drugs. Brushed human nasal epithelial cells (HNEs) are an attractive tissue source, but it remains unclear how faithfully they recapitulate human bronchial epithelial cell (HBE) CFTR activity. We examined this gap using paired, brushed HNE/HBE samples from pediatric CF subjects with a wide variety of CFTR mutations cultured at the air-liquid interface. Growth and structural characteristics for the two cell types were similar, including differentiation into mature respiratory epithelia. In electrophysiologic analysis, no correlation was identified between nasal and bronchial cultures in baseline resistance or epithelial sodium channel (ENaC) activity. Conversely, robust correlation was demonstrated between nasal and bronchial cultures in both stimulated and inhibited CFTR activity. There was close correlation in modulator-induced change in CFTR activity, and CFTR activity in both cell types correlated with in vivo sweat chloride measurements. These data confirm that brushed HNE cell cultures recapitulate the functional CFTR characteristics of HBEs with fidelity and are therefore an appropriate noninvasive HBE surrogate for individualized CFTR analysis.

Pulmonary epithelial barrier and immunological functions at birth and in early life - key determinants of the development of asthma? A description of the protocol for the Breathing Together study

Background.  Childhood asthma is a common complex condition whose aetiology is thought to involve gene-environment interactions in early life occurring at the airway epithelium, associated with immune dysmaturation.  It is not clear if abnormal airway epithelium cell (AEC) and cellular immune system functions associated with asthma are primary or secondary.  To explore this, we will (i) recruit a birth cohort and observe the evolution of respiratory symptoms; (ii) recruit children with and without asthma symptoms; and (iii) use existing data from children in established STELAR birth cohorts.    Novel pathways identified in the birth cohort will be sought in the children with established disease.  Our over-arching hypothesis is that epithelium function is abnormal at birth in babies who subsequently develop asthma and progression is driven by abnormal interactions between the epithelium, genetic factors, the developing immune system, and the microbiome in the first years of life.

Methods.  One thousand babies will be recruited and nasal AEC collected at 5-10 days after birth for culture.  Transcriptomes in AEC and blood leukocytes and the upper airway microbiome will be determined in babies and again at one and three years of age. In a subset of 100 individuals, AEC transcriptomes and microbiomes will also be assessed at three and six months.  Individuals will be assigned a wheeze category at age three years.  In a cross sectional study, 300 asthmatic and healthy children aged 1 to 16 years will have nasal and bronchial AEC collected for culture and transcriptome analysis, leukocyte transcriptome analysis, and upper and lower airway microbiomes ascertained.  Genetic variants associated with asthma symptoms will be confirmed in the STELAR cohorts. 

Conclusions.  This study is the first to comprehensively study the temporal relationship between aberrant AEC and immune cell function and asthma symptoms in the context of early gene-microbiome interactions.

Comparison of paired human nasal and bronchial airway epithelial cell responses to rhinovirus infection and IL-13 treatment

BACKGROUND

Because of its advantage as a minimally invasive procedure, nasal brushings have been increasingly used and proposed as a valuable approach to study lower airway diseases in lieu of bronchial epithelial cells. However, there is limited or conflicting evidence pertaining to whether nasal samples can be surrogates to bronchial samples. The goal of the present study is to test whether nasal epithelial cells have similar antiviral and inflammatory responses to IL-13 treatment and rhinovirus infection, a condition mimicking virally induced asthma exacerbation. Nasal and bronchial airway epithelial cells taken from the same patient were cultured under submerged and air-liquid interface (ALI) culture in the absence or presence of rhinovirus and IL-13 treatment. Inflammatory cytokines IP-10 and eotaxin-3, antiviral gene Mx1 and viral levels were measured.

RESULTS

In the absence of IL-13 treatment, nasal and bronchial cells showed a similar IP-10 response in both ALI and submerged cultures. Under the ALI culture, short term (e.g., 3 days) IL-13 treatment had a minimal effect on viral and Mx1 levels in both cell types. However, prolonged (e.g., 14 days) IL-13 treatments in both cell types decreased viral load and Mx1 expression. Under the submerged culture, IL-13 treatment in both cell types has minimal effects on viral load, IP-10 and Mx1. IL-13-induced eotaxin-3 production was similar in both types of cells under either submerged or ALI culture, which was not affected by viral infection.

CONCLUSIONS

Our data suggest that nasal epithelial cells could serve as a surrogate to bronchial epithelial cells in future studies aimed at defining the role of type 2 cytokine IL-13 in regulating pro-inflammatory and antiviral responses.

Prenatal fine particulate exposure associated with reduced childhood lung function and nasal epithelia GSTP1 hypermethylation: Sex-specific effects

Background

In utero exposure to particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) has been linked to child lung function. Overlapping evidence suggests that child sex and exposure timing may modify effects and associations may be mediated through glutathione S-transferase P1 (GSTP1) methylation.

Methods

We prospectively examined associations among prenatal PM_2.5 exposure and child lung function and GSTP1 methylation in an urban pregnancy cohort study. We employed a validated satellite-based spatiotemporally resolved prediction model to estimate daily prenatal PM_2.5 exposure over gestation. We used Baysian distributed lag interaction models (BDLIMs) to identify sensitive windows for prenatal PM_2.5 exposure on child lung function and nasal epithelia GSTP1 methylation at age 7 years, and to examine effect modification by child sex.

Results

BDLIMs identified a sensitive window for prenatal PM_2.5 exposure at 35–40 weeks gestation [cumulative effect estimate (CEE) = − 0.10, 95%CI = − 0.19 to − 0.01, per μg/m³ increase in PM_2.5] and at 36–40 weeks (CEE = − 0.12, 95%CI = − 0.20 to − 0.01) on FEV₁ and FVC, respectively, in boys. BDLIMs also identified a sensitive window of exposure at 37–40 weeks gestation between higher prenatal PM_2.5 exposure and increased GSTP1 percent methylation. The association between higher GSTP1 percent methylation and decreased FEV1 was borderline significant in the sample as a whole (β = − 0.37, SE = 0.20, p = 0.06) and in boys in stratified analyses (β = − 0.56, SE = 0.29, p = 0.05).

Conclusions

Prenatal PM_2.5 exposure in late pregnancy was associated with impaired early childhood lung function and hypermethylation of GSTPI in DNA isolated from nasal epithelial cells. There was a trend towards higher GSTP1 percent methylation being associated with reduced FEV1. All findings were most evident among boys.

Generation of Human Nasal Epithelial Cell Spheroids for Individualized Cystic Fibrosis Transmembrane Conductance Regulator Study

While the introduction of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulator drugs has revolutionized care in Cystic Fibrosis (CF), the genotype-directed therapy model currently in use has several limitations. First, rare or understudied mutation groups are excluded from definitive clinical trials. Moreover, as additional modulator drugs enter the market, it will become difficult to optimize the modulator choices for an individual subject. Both of these issues are addressed with the use of patient-derived, individualized preclinical model systems of CFTR function and modulation. Human nasal epithelial cells (HNEs) are an easily accessible source of respiratory tissue for such a model. Herein, we describe the generation of a three-dimensional spheroid model of CFTR function and modulation using primary HNEs. HNEs are isolated from subjects in a minimally invasive fashion, expanded in conditional reprogramming conditions, and seeded into the spheroid culture. Within 2 weeks of seeding, spheroid cultures generate HNE spheroids that can be stimulated with 3',5'-cyclic adenosine monophosphate (cAMP)-generating agonists to activate CFTR function. Spheroid swelling is then quantified as a proxy of CFTR activity. HNE spheroids capitalize on the minimally invasive, yet respiratory origin of nasal cells to generate an accessible, personalized model relevant to an epithelium reflecting disease morbidity and mortality. Compared to the air-liquid interface HNE cultures, spheroids are relatively quick to mature, which reduces the overall contamination rate. In its current form, the model is limited by low throughput, though this is offset by the relative ease of tissue acquisition. HNE spheroids can be used to reliably quantify and characterize CFTR activity at the individual level. An ongoing study to tie this quantification to in vivo drug response will determine if HNE spheroids are a true preclinical predictor of patient response to CFTR modulation.

Using Drugs to Probe the Variability of Trans-Epithelial Airway Resistance

Background

Precision medicine aims to combat the variability of the therapeutic response to a given medicine by delivering the right medicine to the right patient. However, the application of precision medicine is predicated on a prior quantitation of the variance of the reference range of normality. Airway pathophysiology provides a good example due to a very variable first line of defence against airborne assault. Humans differ in their susceptibility to inhaled pollutants and pathogens in part due to the magnitude of trans-epithelial resistance that determines the degree of epithelial penetration to the submucosal space. This initial ‘set-point’ may drive a sentinel event in airway disease pathogenesis. Epithelia differentiated in vitro from airway biopsies are commonly used to model trans-epithelial resistance but the ‘reference range of normality’ remains problematic. We investigated the range of electrophysiological characteristics of human airway epithelia grown at air-liquid interface in vitro from healthy volunteers focusing on the inter- and intra-subject variability both at baseline and after sequential exposure to drugs modulating ion transport.

Methodology/Principal Findings

Brushed nasal airway epithelial cells were differentiated at air-liquid interface generating 137 pseudostratified ciliated epithelia from 18 donors. A positively-skewed baseline range exists for trans-epithelial resistance (Min/Max: 309/2963 Ω·cm²), trans-epithelial voltage (-62.3/-1.8 mV) and calculated equivalent current (-125.0/-3.2 μA/cm²; all non-normal, P<0.001). A minority of healthy humans manifest a dramatic amiloride sensitivity to voltage and trans-epithelial resistance that is further discriminated by prior modulation of cAMP-stimulated chloride transport.

Conclusions/Significance

Healthy epithelia show log-order differences in their ion transport characteristics, likely reflective of their initial set-points of basal trans-epithelial resistance and sodium transport. Our data may guide the choice of the background set point in subjects with airway diseases and frame the reference range for the future delivery of precision airway medicine.

Primary airway epithelial cell culture and asthma in children-lessons learnt and yet to come

Until recently the airway epithelial cell (AEC) was considered a simple barrier that prevented entry of inhaled matter into the lung parenchyma. The AEC is now recognized as having an important role in the inflammatory response of the respiratory system to inhaled exposures, and abnormalities of these responses are thought to be important to asthma pathogenesis. This review first explores how the challenges of studying nasal and bronchial AECs in children have been addressed and then summarizes the results of studies of primary AEC function in children with and without asthma. There is good evidence that nasal AECs may be a suitable surrogate for the study of certain aspects of bronchial AEC function, although bronchial AECs remain the gold standard for asthma research. There are consistent differences between children with and without asthma for nasal and bronchial AEC mediator release following exposure to a range of pro-inflammatory stimulants including interleukins (IL)-1β, IL-4, and IL-13. However, there are inconsistencies between studies, e.g., release of IL-6, an important pro-inflammatory cytokine, is not increased in children with asthma relative to controls in all studies. Future work should expand current understanding of the "upstream" signalling pathways in AEC, study AEC from children before the onset of asthma symptoms and in vitro models should be developed that replicate the in vivo status more completely, e.g., co-culture with dendritic cells. AECs are difficult to obtain from children and collaboration between centers is expected to yield meaningful advances in asthma understanding and ultimately help deliver novel therapies.

Exhaled nitric oxide and nasal tryptase are associated with wheeze, rhinitis and nasal allergy in primary school children

Rhinitis and asthma are the most common respiratory diseases in children. We assessed whether airway inflammation markers were associated with nasal allergies and self-reported symptoms of wheeze and rhinitis in 130 children 6-12 year old in an epidemiological context. Independent of sex and age, the fraction of exhaled nitric oxide (FeNO) and nasal mast cell (MC) activation (tryptase ≥ 5 ng/mL) were positively associated with wheeze, rhinitis and with nasal allergy. Nasal eosinophil cationic protein (ECP) and exhaled breath condensate (EBC) markers (pH, 8-isoprostane, interleukin-1β) were not associated with symptoms or with nasal allergy. In conclusion, FeNO and nasal tryptase reflect allergic inflammation in the respiratory system.