Primary Nasal Epithelial Cell Cultures Research Articles

Rare presence and function of neuroendocrine cells in the nasal mucosa.

There is growing evidence that neurogenic inflammation contributes to the pathophysiology of upper airway diseases, with nasal hyperreactivity (NHR) being a key symptom. The rare neuroendocrine cells (NECs) in the epithelium have been linked to the pathophysiology of bronchial and intestinal hyperreactivity, however their presence in the nasal mucosa and their potential role in NHR remains unclear. Therefore, we studied the presence of NECs in the nasal epithelium of controls, allergic rhinitis patients and chronic rhinosinusitis with nasal polyps patients, and their link to NHR. The expression of typical NECs markers, CHGA, ASCL1 and CGRP, were evaluated on gene and protein level in human samples using real-time quantitative PCR (RT-qPCR), western blot, immunohistochemistry fluorescence staining, RNA scope assay, flow cytometry and single cell RNA-sequencing. Furthermore, the change in peak nasal inspiratory flow after cold dry air provocation and visual analogue scale scores were used to evaluate NHR or disease severity, respectively. Limited gene expression of the NECs markers CHGA and ASCL1 was measured in patients with upper airway diseases and controls. Gene expression of these markers did not correlate with NHR severity nor disease severity. In vitro, CHGA and ASCL1 expression was also evaluated in primary nasal epithelial cell cultures from patients with upper airway disease and controls using RT-qPCR and western blot. Both on gene and protein level only limited CHGA and ASCL1 expression was found. Additionally, NECs were studied in nasal biopsies of patients with upper airway diseases and controls using immunohistochemistry fluorescence staining, RNA scope and flow cytometry. Unlike in ileum samples, CHGA could not be detected in nasal biopsies of patients with upper airway diseases and control subjects. Lastly, single cell RNA-sequencing of upper airway tissue could not identify a NEC cluster. In summary, in contrast to the bronchi and gut, there is only limited evidence for the presence of NECs in the nasal mucosa, and without correlation with NHR, thereby questioning the relevance of NECs in upper airway pathology.

Primary Nasal Epithelial Cells as a Surrogate Cell Culture Model for Type-II Alveolar Cells to Study ABCA-3 Deficiency.

ATP Binding Cassette Subfamily A Member 3 (ABCA-3) is a lipid transporter protein highly expressed in type-II alveolar (AT-II) cells. Mutations in ABCA3 can result in severe respiratory disease in infants and children. To study ABCA-3 deficiency in vitro, primary AT-II cells would be the cell culture of choice although sample accessibility is limited. Our aim was to investigate the suitability of primary nasal epithelial cells, as a surrogate culture model for AT-II cells, to study ABCA-3 deficiency. Expression of ABCA3, and surfactant protein genes, SFTPB and SFTPC, was detected in primary nasal epithelial cells but at a significantly lower level than in AT-II cells. ABCA-3, SP-B, and SP-C were detected by immunofluorescence microscopy in primary nasal epithelial cells. However, SP-B and SP-C were undetectable in primary nasal epithelial cells using western blotting. Structurally imperfect lamellar bodies were observed in primary nasal epithelial cells using transmission electron microscopy. Functional assessment of the ABCA-3 protein demonstrated that higher concentrations of doxorubicin reduced cell viability in ABCA-3 deficient nasal epithelial cells compared to controls in an assay-dependent manner. Our results indicate that there may be a role for primary nasal epithelial cell cultures to model ABCA-3 deficiency in vitro, although additional cell culture models that more effectively recapitulate the AT-II phenotype may be required.

Early life innate immune responses to RSV in cystic fibrosis airway epithelium

Respiratory syncytial virus (RSV) infection is the major cause of severe lower respiratory tract disease in young infants. Evidence suggests that cystic fibrosis (CF) is associated with significant morbidity following RSV infection. We and others previously demonstrated that airway epithelium is the primary target of RSV infection. However, little is known about the impact of RSV infection on CF airway epithelium. To address this, we established and characterised well-differentiated primary nasal epithelial cell cultures (WD-PNECs) from recently diagnosed CF infants to study RSV cytopathogenesis in CF airway epithelium. CF WD-PNECs were successfully generated from 11 infants and characterised by light and fluorescent microscopy. CF WD-PNECs secreted thick dry apical mucous, consistent with in vivo observations. Extensive cilia coverage was also evident, although cilia beat frequencies appeared lower than those evident in WD-PNECs from healthy neonates. Quantification of goblet and ciliated cells in the CF WD-PNEC cultures were similar to those of healthy cultures. Viral growth kinetics were similar for CF WD-PNECs and healthy WD- PNECs, with peak virus titres evident at 72–96 hpi. CXCL8/IL-8 and CXCL10/IP-10 secretions were upregulated following RSV infection of CF WD-PNECs, while IL-6 secretions did not change. Interestingly, our data suggested that duoxa2 and duox2 expression post-infection were reduced in WD-PNECs from CF compared to healthy infants. Our data suggest that this model provides an exciting opportunity to elucidate the cytopathogenic, inflammatory and molecular consequences of RSV infection of airway epithelium derived from very young CF infants.

Alternative Method for Primary Nasal Epithelial Cell Culture Using Intranasal Brushing and Feasibility for the Study of Epithelial Functions in Allergic Rhinitis

Alternative Method for Primary Nasal Epithelial Cell Culture Using Intranasal Brushing and Feasibility for the Study of Epithelial Functions in Allergic Rhinitis

Alternative Method for Primary Nasal Epithelial Cell Culture Using Intranasal Brushing and Feasibility for the Study of Epithelial Functions in Allergic Rhinitis.

PurposeAlthough differentiated normal human nasal epithelial (NHNE) cells can be used to study the role of human nasal epithelium, there is a need for effective culture models of nasal epithelium in sinonasal disease status, including allergic rhinitis (AR). We aimed to examine the feasibility of intranasal brushing for culture of nasal epithelial cells in AR patients and to verify the hypothesis that allergic nasal epithelial (ARNE) cells differ in histologic and physiologic characteristics.MethodsWe established a system for isolating (via intranasal brushing) and culturing (with air-liquid interface, ALI) nasal epithelial cells from healthy volunteers (n=8) and AR patients (n=8). We used this system to compare the histologic findings and physiologic characteristics of NHNE and ARNE.ResultsThe histology results showed that fully differentiated ALI culture was obtained at least 14 days after confluence and that both ciliated and secretory cells were well differentiated in ALI culture using nasal brushing. The histology results of ARNE culture were significantly different from NHNE. The number of ciliated cells was lower, and secretory cells were more dominant in ARNE cell culture compared to NHNE cells. We also observed, by electron microscopy, loose tight junctions and short cilia in cultured ARNE cells. In addition, the mRNA level of TSLP which was one of the epithelial-derived allergic cytokines was significantly higher, and the expressions of genes involved in ciliogenesis were lower in cultured ARNE cells without allergen stimulation.ConclusionsOur findings suggest that ALI culture of ARNE cells using intranasal brushing may be an alternative method for epithelial cell culture in AR patients and that cultured ARNE cells will be useful for in vitro studies of the mechanisms at play during AR because they maintain unique allergic characteristics.

Inflammatory and cytotoxic effects of acrolein, nicotine, acetylaldehyde and cigarette smoke extract on human nasal epithelial cells

BackgroundCigarette smoke induces a pro-inflammatory response in airway epithelial cells but it is not clear which of the various chemicals contained within cigarette smoke (CS) should be regarded as predominantly responsible for these effects. We hypothesised that acrolein, nicotine and acetylaldehyde, important chemicals contained within volatile cigarette smoke in terms of inducing inflammation and causing addiction, have immunomodulatory effects in primary nasal epithelial cell cultures (PNECs).MethodsPNECs from 19 healthy subjects were grown in submerged cultures and were incubated with acrolein, nicotine or acetylaldehyde prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide (PA LPS). Experiments were repeated using cigarette smoke extract (CSE) for comparison. IL-8 was measured by ELISA, activation of NF-κB by ELISA and Western blotting, and caspase-3 activity by Western blotting. Apoptosis was evaluated using Annexin-V staining and the terminal transferase-mediated dUTP nick end-labeling (TUNEL) method.ResultsCSE was pro-inflammatory after a 24 h exposure and 42% of cells were apoptotic or necrotic after this exposure time. Acrolein was pro-inflammatory for the PNEC cultures (30 μM exposure for 4 h inducing a 2.0 fold increase in IL-8 release) and also increased IL-8 release after stimulation with PA LPS. In contrast, nicotine had anti-inflammatory properties (0.6 fold IL-8 release after 50 μM exposure to nicotine for 24 h), and acetylaldehyde was without effect. Acrolein and nicotine had cellular stimulatory and anti-inflammatory effects respectively, as determined by NF-κB activation. Both chemicals increased levels of cleaved caspase 3 and induced cell death.ConclusionsAcrolein is pro-inflammatory and nicotine anti-inflammatory in PNEC cultures. CSE induces cell death predominantly by apoptotic mechanisms.

P‐glycoprotein functions as an immunomodulator in healthy human primary nasal epithelial cells

P-glycoprotein (P-gp) is an adenosine triphosphate (ATP)-dependent efflux pump that confers chemotherapeutic resistance in cancer cells. Recent studies suggest that P-gp may also function as an immunomodulator through regulation of cytokine transport. Sinonasal epithelial cells have been recognized as drivers of local innate and adaptive immunity and are known to overexpress P-gp in the setting of inflammation. The objective of this study is to therefore determine whether P-gp participates in the regulation of cytokine secretion in sinonasal epithelial cells. Primary nasal epithelial cell cultures (PNECCs) were cultivated from 5 healthy patients. Membranous P-gp was quantified through quantitative fluorescent immunohistochemistry (Q-FIHC) and confirmed by enzyme-linked immunosorbent assay (ELISA). Sensitivity to inhibition was determined using a rhodamine 123 accumulation assay. Baseline and lipopolysaccharide (LPS)-stimulated cytokine secretion of interleukin 6 (IL-6), IL-8, granulocyte macrophage colony stimulating factor (GM-CSF), and thymic stromal lymphopoietin (TSLP) were quantified by ELISA and compared to LPS stimulated secretion in the setting of P-gp-specific inhibition. Differences in P-gp expression and cytokine secretion were compared using 2-tailed Student t tests with post hoc testing using the Bonferroni procedure. Membranous P-gp is detectable in PNECCs and upregulated following LPS exposure. P-gp is sensitive to inhibition by both PSC 833 and verapamil in a dose-dependent fashion. LPS stimulated secretion of normalized IL-6 (mean, 95% confidence interval [CI]) (79.67, 42.26-117.07), GM-CSF (39.92, 7.90-71.94), and TSLP (6.65, 5.35-7.96) was significantly reduced following P-gp inhibition (37.60, 11.54-63.65, p = 0.023; 7.64, 2.25-13.03, p = 0.044; and 5.13, 4.44-5.82, p = 0.038; respectively). P-gp is functionally active in PNECCs. P-gp participates in modulation of epithelial secretion of LPS stimulated IL-6, GM-CSF, and TSLP.

Antimicrobial peptides in nasal secretion and mucosa with respect to Staphylococcus aureus colonization in chronic rhinosinusitis with nasal polyps

Objective: Nasal carriage of Staphylococcus aureus in patients with chronic rhinosinusitis with nasal polyps (NP) is hypothesized to have pathophysiological impact on the disease. Antimicrobial peptides (AMP), especially human beta-defensin-3 (hBD-3) and LL-37, are an important part of the multifactorial defence against microorganisms in barrier organs like the nasal mucosa. The interaction of S. aureus colonization and AMP in nasal secretions and mucosa of NP were investigated in this study. Patients and methods: AMP were quantified in nasal secretions of 13 normal controls (NC) and 12 NP patients, each with and without S. aureus colonization, by ELISA. Immunohistochemistry was used to investigate the cellular sources of AMP in the nasal mucosa. To explore the AMP response of primary nasal epithelial cell cultures (NEC) towards S. aureus stimulation, a functional assay was established. Results: AMP could be demonstrated in nasal secretions of all groups without differences in hBD-3 concentrations comparing S. aureus carriers vs. non-carriers. In NC, higher LL-37 concentrations were observed in S. aureus colonized as compared to non-colonized patients. This effect was not detectable in NP patients. Epithelial cells, submucosal glands and cells of the connective tissue could be identified as sources of AMP by immunohistochemistry. An AMP response of NEC towards S. aureus stimulation was detected in all groups. Conclusion: In NP patients, LL-37 response towards S. aureus colonization is disturbed while the ability of NEC to respond on S. aureus challenge is preserved. This deregulation of the nasal barrier could be involved in the multifactorial pathophysiology of NP.

PAR‐2 activation regulates IL‐8 and GRO‐α synthesis by NF‐κB, but not RANTES, IL‐6, eotaxin or TARC expression in nasal epithelium

The effects of protease-activated receptor-2 (PAR-2) stimulation on inflammation mechanisms of chronic rhinosinusitis (CRS) are still unknown. PAR-2 receptor expression was investigated by immunohistochemistry and Taqman mRNA analysis in the mucosa of different rhinosinusitis entities. In primary nasal epithelial cell cultures, the function of PAR-2 and its ability to produce CXC, CC chemokines, and IL-6 were measured by calcium mobilization and stimulation tests. Inhibition tests were performed using cortisone, serine protease inhibitors, cysteine protease inhibitors, Pertussis toxin (PTX) and nuclear transcription factor (NF-kappaB) inhibition (BAY 11-7085). Signal transduction pathways were analysed by electromobility shift assays (EMSA) and NF-kappaB binding studies. The expression of PAR-2 was found to be increased in CRS specimens. The activation of PAR by trypsin or PAR-2-specific activating peptide (AP) caused an increase in cytosolic calcium, as well as the release of the CXC chemokines IL-8 and growth-related oncogene (GRO)-alpha, but not the release of CC chemokines or IL-6. AP-induced CXC chemokine was sensitive to PTX and activation of NF-kappaB was inhibited by BAY11-7085. Furthermore, a serine protease inhibitor significantly inhibited chemokine synthesis stimulated by trypsin and culture supernatants of staphylococci, whereas steroids and cysteine protease inhibitors had little effect. PAR-2 plays a role in serine protease-mediated regulation - staphylococcal and non-staphylococcal origin - of IL-8 and GRO-alpha in nasal epithelial cells, but not in the regulation of CC chemokines. PAR-2 may therefore be involved in the pathophysiology of CRS and NP at different sites of activation, namely (i) proteases, (ii) the PAR-2 receptor itself or (iii) the application of novel agents that block NF-kappaB/IkappaB-alpha signalling.

A Comparison of Experimental Methods in Molecular Chronic Rhinosinusitis Research

Research into the molecular pathogenesis of chronic rhinosinusitis (CRS) requires the collection and analysis of sinonasal tissue. Recent gene expression studies have used either surgical tissue specimens or isolated epithelial cell preparations. Here, we compare cultures of nasal epithelial cells, nasal brush biopsy, and whole ethmoid mucosa with respect to expression of innate immune genes. Ethmoid mucosa was collected intraoperatively from 12 CRS and control patients. This tissue either was processed whole for mRNA extraction or was used to generate primary nasal epithelial cell cultures. After 6 weeks, epithelial cells in culture were assessed for multiple innate immune proteins by flow cytometry. In parallel, middle meatal brush biopsy specimens were obtained from the same patients and studied acutely in a similar fashion by flow cytometry. Expression of innate immune genes was determined in whole tissue samples by real-time polymerase chain reaction. Flow cytometry revealed that brush biopsy specimens contain 75% epithelial cells, whereas primary nasal epithelial cell cultures were pure. Epithelial cells derived from individual subjects expressed very similar levels of innate immune markers whether studied acutely or after 6 weeks in culture. Whole tissue mRNA levels were variable and not correlated to epithelial expression. The choice of experimental methodology can greatly influence the results and interpretation of CRS research. Primary nasal epithelial cells maintain their innate immune receptor expression profile when grown in prolonged culture in vitro. These findings imply that alterations in innate immune gene expression in CRS may be intrinsic to the epithelial cells, even outside of their in vivo microenvironment.

Proinflammatory Effects of Staphylococcus Aureus Exotoxin B on Nasal Epithelial Cells

The aim of this study was to evaluate the effects of Staphylococcus aureus exotoxin B (SE-B) on proinflammatory cytokine/chemokine releases in primary nasal epithelial cell cultures (NECC) of subjects with and without chronic rhinosinusitis (CRS). NECC (CRS: n = 14; n = 11) were stimulated with SE-B. Protein concentrations of interleukin-(IL)-1beta, IL-6, and IL-8 levels were measured in NECC supernatants by ELISA before (T0) and after 24 hr stimulation with SE-B (T1). T0: supernatants of the NECC of CRS patients contained significant lower levels of IL-8 (2.1 ng/ml) compared to CONTROLS (IL-8: 6.2 ng/ml; P < 0.01). T1: SE-B induced a significant increase of IL-6 in NECC (P < 0.001). IL-1beta was not detectable. This is the first study evaluating the effects of exotoxins on NECC. SE-B showed proinflammatory effects on NECC. Our data suggest that resident NECC are involved in immunological responses to Staphylococcus aureus toxins, supplementing the so-called "superantigen hypothesis" in CRS.

Acidic pH Hyperpolarizes Nasal Potential Difference

Nasal potential difference (NPD) has served as a non-invasive diagnostic method for cystic fibrosis (CF) a disease of chloride channel expression and function in secretory epithelia. Investigators have also used NPD to demonstrate ion transport abnormalities in newborns with respiratory distress. Standard perfusates for diagnostic NPD studies include the use of amiloride, replacement of chloride with gluconate, cAMP agonists, and nucleotides such as ATP. The pH of these perfusates may also be relevant to NPD studies as we have previously shown that the respiratory epithelia in mammals express CLC-2, which is a pH sensitive chloride channel. We hypothesized that acidic pH might activate chloride secretion in vivo if CLC-2 is present in human respiratory epithelia. Our objective was to determine the effect of acidic pH on NPD measurements and the frequency of expression of CLC-2 in normal subjects. Healthy adults were recruited and CLC-2 protein expression was detected in 20 of 29 primary nasal epithelial cell cultures. Acidic pH stimulated NPD responses in 33% of subjects. These findings suggest that pH sensitive alternative pathways are available for modulation in human respiratory epithelia and that NPD protocols should standardize pH of perfusates.

Staphylococcus enterotoxin a increases proinflammatory cytokine release of nasal epithelial cells

Problem: Staphylococcus aureus enterotoxins (SE) are discussed as etiologic factors in chronic rhinosinusitis (CRS). The aim of this study was to evaluate the effects of SE-type-A (SEA) stimulation on proinflammatory cytokine/chemokine release in a primary nasal epithelial cell culture model. Methods: Mucosa specimens of 14 subjects with CRS and 11 subjects undergoing septal surgery without CRS (controls) were used to isolate and culture nasal epithelial cells. Nasal epithelial cell cultures were stimulated under controlled conditions. Protein concentrations of interleukin-(IL)-6 and IL-8 were measured by ELISA prior (T0) and after the 24h stimulation with SEA (T1). Data were analyzed by using ANOVA for repeated measurements (within subject factor “stimulation,” for T0 vs T1; and between subject factor “group,” for CRS vs controls). Results: At T0, controls contained significant higher levels of IL-6 (56.2 pg/mL) and IL-8 (7.09 ng/mL) compared to CRS (IL-6 20.0 pg/mL; IL-8: 3.5 ng/mL; P < 0.05). After stimulation with SEA a significant increase of IL-8 ( P = 0.024) and IL-6 ( P < 0.1) was observed in both groups. The factor “group” had no significant effect on the cytokine release. Conclusion: Cultured nasal epithelial cells from CRS patients released significant lower levels of IL-6 and IL-8 compared to healthy controls in vitro. IL-6 (antibody production) and IL-8 (neutrophil chemotaxis) are thought to be expressed by nasal epithelial cells for mucosal protection. Transferred to the in vivo situation, our data suggest that lower releases of these IL-6 and IL-8 from epithelia in CRS may result in an impaired defense of nasal mucosa. SEA increases IL-6 and IL-8 expression significantly without statistical differences between the study groups. Therefore it seems unlikely that the pathophysiological role of SEA for CRS is mediated by epithelial cells alone. Significance: This is the first study evaluating the effects of enterotoxins on nasal epithelia. Our findings are helpful for a better understanding of the role of the most common cultured pathogen in the nose. Support: This study was supported by the Deutsche Forschungsgemeinschaft (DFG) within Collaborative Research Center 419 (SFB419) of the University of Cologne.

Induction of the epidermal growth factor receptor and its ligands in nasal epithelium by ozone

Background Ozone is a photochemical oxidant pollutant that is an important public health hazard. Although the inflammatory response that occurs in response to ozone inhalation is well characterized, the mechanisms underlying epithelial cell activation are not well understood. Objective Because the epidermal growth factor receptor (EGFR) is a central regulator of epithelial function, we tested the hypothesis that nasal epithelial cells respond to ozone-induced oxidant stress by modulating expression of the EGFR and its ligands, EGF and transforming growth factor–alpha (TGF-α). Methods Normal volunteers were exposed to air or 400 parts per billion ozone for 2 hours, and then nasal biopsy specimens were harvested 6 hours later for immunohistochemical analysis of EGFR, EGF, and TGF-α. Nasal epithelial cell cultures were exposed in vitro to ozone or TNF-α; mediator release was measured by ELISA and cellular EGFR expression by immunoblotting and fluorescence-activated cell sorting analysis. Results Epithelial expression of the EGFR, EGF, and TGF-α were all significantly ( P < .05) increased in the nasal biopsy specimens after ozone exposure, and there was a significant positive correlation between EGFR expression and the increase in neutrophil numbers in the nasal epithelium ( P = .001, rho = 0.87). In vitro exposure of primary nasal epithelial cell cultures to ozone had no effect on EGFR expression, even though IL-8 release was enhanced. In contrast, exposure to TNF-α caused EGFR levels to increase significantly. Conclusion These data suggest that the ozone-induced increase in EGFR expression observed in vivo is indirect, perhaps mediated by neutrophil-derived TNF-α.