Transient receptor potential vanilloid type 4 channel expression in chronic rhinosinusitis

SPECC1 as a pan-cancer biomarker: unraveling its role in drug sensitivity and resistance mechanisms

Previous studies have shown a relationship between SPECC1 and the prognosis of breast cancer, indicating a potential function for SPECC1 in the initiation and progression of cancer. However, the role played by SPECC1 in other tumors is not yet known. Therefore, we used bioinformatics techniques to conduct a thorough investigation into the possible mechanism of SPECC1 in pan-cancer, analyzing data reported in the literature as well as databases such as GTEx and CCLE, cBioportal, TCGA, and UCSC XENA. Comparing the results with matching normal tissues, the majority of cancers, including pancreatic adenocarcinoma (PAAD) and breast invasive carcinoma (BRCA), exhibited higher levels of SPECC1, while hepatocellular carcinoma (HCC) showed lower expression levels. SPECC1 was also found to be genetically mutated in endometrial cancer, sarcoma, and esophageal cancer. The prognosis of lung adenocarcinoma, kidney papillary cell carcinoma, and breast cancer is highly correlated with dysregulation of SPECC1 expression. This work helps guide clinical therapy by highlighting the sensitivity of tumor-treating medicines and the prognostic importance of SPECC1 in various malignancies. KEGG pathway enrichment analysis revealed focused adhesion, collagen-containing extracellular matrix (collagen), and the primary enrichment domains for SPECC1-related genes. These findings were obtained through gene annotation (GO) examination of SPECC1 expression. Primary mediators of the cytokine-cytokine receptor interaction include PICOC1-associated genes, cell-substrate junction genes, and extracellular matrix containing collagen. PICOC1-associated genes primarily mediate the PI3K-AKT signaling pathway. Drug sensitivity assay showed that SPECC1 high-expressing cell lines were more sensitive to docetaxel, doxorubicin, etc. In conclusion, the current study shows how SPECC1 is expressed in different cancers and how this expression relates to the prognosis of the tumor. It also revealed the mutations and copy number variations of SPECC1 in various tumors and its potential involvement in cellular pathway regulatory networks and cytological processes. This study examines the relationship between immune genes, cellular infiltration, and immunological scores in the tumor microenvironment, which explain the severity of the disease. This study looks at the response of SPEC1 expression to anticancer therapy. Explains the prognostic significance and drug response of SPECC-1.

Safety and Pharmacokinetics of a Ciprofloxacin and Azithromycin Stent for Chronic Rhinosinusitis

OBJECTIVES

Previously, we developed a novel double-coated sinus stent containing ciprofloxacin (inner layer) and azithromycin (outer layer) (CASS), but released drug concentrations were found to be insufficient for clinical usage. Our objectives are to improve drug release of CASS and assess safety and pharmacokinetics in rabbits.

METHODS

Dip coating was used to create the CASS with 2 mg ciprofloxacin and 5 mg azithromycin. A uniformed double coating was assessed with scanning electron microscopy (SEM), and the release patterns of both drugs and lactate dehydrogenase (LDH) assay were evaluated over 14 days in vitro. Safety, tolerability, and pharmacokinetics of the CASS were tested in rabbits through insertion into the maxillary sinus and evaluated with nasal endoscopy, CT scans, histology, blood counts and chemistries, and in vivo drug release.

RESULTS

SEM confirmed the uniformity of the dual coating of ciprofloxacin and azithromycin, and thickness (μm) was found to be 14.7 ± 2.4 and 28.1 ± 4.6, respectively. The inner coated ciprofloxacin showed a sustained release over 14 days (release %) when soaked in saline solution (day 7, 86.2 ± 3.4 vs. day 14,99.2 ± 5.1). In vivo analysis showed that after 12 days, 78.92 ± 7.67% of CP and 84.12 ± 0.45% of AZ were released into the sinus. There were no significant differences in body weight, white blood cell counts, and radiographic changes before and after CASS placement. No significant histological changes were observed compared to the contralateral control side.

CONCLUSION

Findings suggest that the CASS is an effective method for delivering therapeutic levels of antibiotics. Further studies are needed to validate efficacy in a preclinical sinusitis model.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:3953-3959, 2024.

Hypoxia-induced cystic fibrosis transmembrane conductance regulator dysfunction is a universal mechanism underlying reduced mucociliary transport in sinusitis

INTRODUCTION

Hypoxia due to sinus obstruction is a major pathogenic mechanism leading to sinusitis. The objective of the current study is to define the electrophysiologic characteristics of hypoxia in vitro and in vivo.

METHODS

Cystic fibrosis bronchoepithelial cells expressing wild-type cystic fibrosis transmembrane conductance regulator (CFTR) and human sinonasal epithelial cells were exposed to 1% or atmospheric O2 for 24 h. Time-dependent production of cytoplasmic free radicals was measured. Cells were subjected to Ussing chamber and patch clamp technique where CFTR currents were recorded in whole-cell and cell-attached mode for single channel studies. Indices of mucociliary transport (MCT) were measured using micro-optical coherence tomography. In a rabbit hypoxic maxillary sinus model, tissue oxygenation, relative mRNA expression of HIF-1α, pH, sinus potential difference (SPD), and MCT were determined.

RESULTS

Ussing chamber (p < 0.05), whole-cell (p < 0.001), and single channel patch-clamp (p < 0.0001) showed significant inhibition of Cl- currents in hypoxic cells. Cytoplasmic free radicals showed time-dependent elevation peaking at 4 h (p < 0.0001). Airway surface liquid (p < 0.0001), periciliary liquid (p < 0.001), and MCT (p < 0.01) were diminished. Co-incubation with the free radical scavenger glutathione negated the impact of hypoxia on single channel currents and MCT markers. In sinusitis rabbits, mucosa exhibited low tissue oxygenation (p < 0.0001), increased HIF1α mRNA (p < 0.05), reduced pH (p < 0.01), and decreased MCT (p < 0.001). SPD measurements demonstrated markedly diminished transepithelial Cl- transport (p < 0.0001).

CONCLUSION

Hypoxia induces severe CFTR dysfunction via free radical production causing reduced MCT in vitro and in vivo. Improved oxygenation is critical to reducing the impact of persistent mucociliary dysfunction.

Transient Receptor Potential Vanilloid (TRPV4) channel inhibition: A novel promising approach for the treatment of lung diseases

Research on transient receptor potential vanilloid-4 (TRPV4) can provide a promising potential therapeutic target in the development of novel medicines for lung disorders. TRPV4 expresses in lung tissue and plays an important role in the maintenance of respiratory homeostatic function. TRPV4 is upregulated in life-threatening respiratory diseases like pulmonary hypertension, asthma, cystic fibrosis, and chronic obstructive pulmonary diseases. TRPV4 is linked to several proteins that have physiological functions and are sensitive to a wide variety of stimuli, such as mechanical stimulation, changes in temperature, and hypotonicity, and responds to a variety of proteins and lipid mediators, including anandamide (AA), the arachidonic acid metabolite, 5,6-epoxyeicosatrienoic acid (5,6-EET), a plant dimeric diterpenoid called bisandrographolide A (BAA), and the phorbol ester 4-alpha-phorbol-12,13-didecanoate (4α-PDD). This study focused on relevant research evidence of TRPV4 in lung disorders and its agonist and antagonist effects. TRPV4 can be a possible target of discovered molecules that exerts high therapeutic potential in the treatment of respiratory diseases by inhibiting TRPV4.

Ivacaftor restores delayed mucociliary transport caused by Pseudomonas aeruginosa-induced acquired cystic fibrosis transmembrane conductance regulator dysfunction in rabbit nasal epithelia

BACKGROUND

Abnormal chloride (Cl^- ) transport dehydrates airway surface liquid (ASL) in sinonasal epithelium leading to mucus stasis and chronic rhinosinusitis. As an experimental epithelium, rabbit tissue provides an excellent representation of human sinus disease, and the rabbit sinusitis model is both established and well suited for therapeutic interventions in vivo. Our objective in this study was to evaluate whether ivacaftor reverses the consequences of Pseudomonas aeruginosa-induced acquired cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction.

METHODS

Rabbit nasal cavities were assessed for responsiveness to ivacaftor in vivo (by nasal potential difference [NPD] assay). Rabbit nasal epithelial (RNE) cultures were incubated with an ultrafiltrate of P aeruginosa (PAO1 strain) for 4 hours and tested for acquired CFTR dysfunction. Markers of mucociliary function, including airway surface liquid depth (ASL), periciliary liquid depth (PCL), ciliary beat frequency (CBF), and mucociliary transport (MCT), were measured by micro-optical coherence tomography (μOCT) after PAO1 and/or ivacaftor incubation.

RESULTS

Ivacaftor resulted in a significant mean NPD polarization of 21.8 ± 2.1 mV, which was significantly greater than that seen in the low Cl^- control (12.9 ± 1.3; p = 0.01). PAO1 exposure induced a state of acquired CFTR dysfunction in rabbit nasal epithelium as measured by forskolin-stimulated short-circuit current (I_SC ) (control, 37.0 ± 1.1 μA/cm² ; PAO1, 24.4 ± 1.1 μA/cm² ; p < 0.001). RNE cultures exposed to PAO1 had inhibited mucociliary function, whereas coincubation with ivacaftor restored mucociliary clearance, as measured by μOCT.

CONCLUSION

In rabbit nasal epithelium, ivacaftor robustly stimulates CFTR-mediated Cl^- secretion and normalizes ASL and CBF in PAO1-induced acquired CFTR dysfunction. Preclinical testing of CFTR potentiators as therapy for P aeruginosa rabbit sinusitis is planned.

Epithelial and sensory mechanisms of nasal hyperreactivity

"Nasal hyperreactivity" is a key feature in various phenotypes of upper airway diseases, whereby reactions of the nasal epithelium to diverse chemical and physical stimuli are exacerbated. In this review, we illustrate how nasal hyperreactivity can result from at least three types of mechanisms: (1) impaired barrier function, (2) hypersensitivity to external and endogenous stimuli, and (3) potentiation of efferent systems. We describe the known molecular basis of hyperreactivity related to the functional impairment of epithelial cells and somatosensory innervation, and indicate that the thermal, chemical, and mechanical sensors determining hyperreactivity in humans remain to be identified. We delineate research directions that may provide new insights into nasal hyperreactivity associated with rhinitis/rhinosinusitis pathophysiology and therapeutics. The elucidation of the molecular mechanisms underlying nasal hyperreactivity is essential for the treatment of rhinitis according to the precepts of precision medicine.

In vitro evaluation of a novel oxygen-generating biomaterial for chronic rhinosinusitis therapy

BACKGROUND

Hypoxia due to closure at the ostiomeatal complex is widely considered one of the major pathogenic mechanisms leading to chronic inflammation in chronic rhinosinusitis (CRS). The objective of this study was to develop and characterize an oxygen-generating biomaterial (OGB) as an innovative treatment strategy for CRS.

METHODS

An OGB was fabricated by coating hydrophobic beeswax (BW, 15mg or 30mg) on the surface of calcium peroxide - catalase complex (CPO-CA, 30mg) and characterized using scanning electron microscopy (SEM). In vitro releases of both oxygen and hydrogen peroxide (H₂ O₂ ) were spectrophotometrically quantified, and cytotoxicity in human sinonasal epithelial cells (HSNECs) was evaluated. The influence of OGB on transepithelial Cl^- secretion was also determined by pharmacologically manipulating HSNECs, cultured under hypoxic conditions, in Ussing chambers.

RESULTS

Three groups of OGBs: (1) CPO only; (2) CPO coated with CA and BW (1:1 ratio, CPO-CA(1)-BW(1)); and (3) CPO coated with CA and BW (1:0.5 ratio, CPO-CA(1)-BW(0.5) were analyzed for accumulated oxygen release over 7 days: highest release (mmol/mg) was observed in CPO-CA(1)-BW(1) = 0.11 ± 0.003, followed by CPO-CA(1)-BW(0.5) = 0.08 ± 0.010, and CPO = 0.05 ± 0.004 (p < 0.0001). H₂ O₂ production (mM) was significantly higher in CPO (1.87 ± 0.50) compared to CPO-CA (1)-BW(1) (0.00 ± 0.00) (p < 0.001) after 24 h. CPO-CA(1)-BW(1) showed significantly reduced cytotoxicity and increased Cl^- transport compared to the CPO group.

CONCLUSION

A novel OGB (CPO-CA-BW complex) exhibited sustained oxygen release over 7 days without significant cytotoxicity after 24 h in vitro. Preclinical studies evaluating the efficacy of OGB in CRS are warranted, especially for potential therapy in an obstruction-based CRS model.

The Roles of Transient Receptor Potential Vanilloid 1 and 4 in Pneumococcal Nasal Colonization and Subsequent Development of Invasive Disease

Transient receptor potential (TRP) channels, neuronal stimulations widely known to be associated with thermal responses, pain induction, and osmoregulation, have been shown in recent studies to have underlying mechanisms associated with inflammatory responses. The role of TRP channels on inflammatory milieu during bacterial infections has been widely demonstrated. It may vary among types of channels/pathogens, however, and it is not known how TRP channels function during pneumococcal infections. Streptococcus pneumoniae can cause severe infections such as pneumonia, bacteremia, and meningitis, with systemic inflammatory responses. This study examines the role of TRP channels (TRPV1 and TRPV4) for pneumococcal nasal colonization and subsequent development of invasive pneumococcal disease in a mouse model. Both TRPV1 and TRPV4 channels were shown to be related to regulation of the development of pneumococcal diseases. In particular, the influx of neutrophils (polymorphonuclear cells) in the nasal cavity and the bactericidal activity were significantly suppressed among TRPV4 knockout mice. This may lead to severe pneumococcal pneumonia, resulting in dissemination of the bacteria to various organs and causing high mortality during influenza virus coinfection. Regulating host immune responses by TRP channels could be a novel strategy against pathogenic microorganisms causing strong local/systemic inflammation.

LPS decreases CFTR open probability and mucociliary transport through generation of reactive oxygen species

Lipopolysaccharide (LPS) serves as the interface between gram-negative bacteria (GNB) and the innate immune response in respiratory epithelial cells (REC). Herein, we describe a novel biological role of LPS that permits GNB to persist in the respiratory tract through inducing CFTR and mucociliary dysfunction. LPS reduced cystic fibrosis transmembrane conductance regulater (CFTR)-mediated short-circuit current in mammalian REC in Ussing chambers and nearly abrogated CFTR single channel activity (defined as forskolin-activated Cl^- currents) in patch clamp studies, effects of which were blocked with toll-like receptor (TLR)-4 inhibitor. Unitary conductance and single-channel amplitude of CFTR were unaffected, but open probability and number of active channels were markedly decreased. LPS increased cytoplasmic and mitochondrial reactive oxygen species resulting in CFTR carbonylation. All effects of exposure were eliminated when reduced glutathione was added in the medium along with LPS. Functional microanatomy parameters, including mucociliary transport, in human sinonasal epithelial cells in vitro were also decreased, but restored with co-incubation with glutathione or TLR-4 inhibitor. In vivo measurements, following application of LPS in the nasal cavities showed significant decreases in transepithelial Cl^- secretion as measured by nasal potential difference (NPD) – an effect that was nullified with glutathione and TLR-4 inhibitor. These data provide definitive evidence that LPS-generated reactive intermediates downregulate CFTR function in vitro and in vivo which results in cystic fibrosis-type disease. Findings have implications for therapeutic approaches intent on stimulating Cl^- secretion and/or reducing oxidative stress to decrease the sequelae of GNB airway colonization and infection.

A TRiP Through the Roles of Transient Receptor Potential Cation Channels in Type 2 Upper Airway Inflammation

PURPOSE OF REVIEW

Despite their high prevalence, the pathophysiology of allergic rhinitis (AR) and chronic rhinosinusitis (CRS) remains unclear. Recently, transient receptor potential (TRP) cation channels emerged as important players in type 2 upper airway inflammatory disorders. In this review, we aim to discuss known and yet to be explored roles of TRP channels in the pathophysiology of AR and CRS with nasal polyps.

RECENT FINDINGS

TRP channels participate in a plethora of cellular functions and are expressed on T cells, mast cells, respiratory epithelial cells, and sensory neurons of the upper airways. In chronic upper airway inflammation, TRP vanilloid 1 is mostly studied in relation to nasal hyperreactivity. Several other TRP channels such as TRP vanilloid 4, TRP ankyrin 1, TRP melastatin channels, and TRP canonical channels also have important functions, rendering them potential targets for therapy. The role of TRP channels in type 2 inflammatory upper airway diseases is steadily being uncovered and increasingly recognized. Modulation of TRP channels may offer therapeutic perspectives.

Differential Chloride Secretory Capacity in Transepithelial Ion Transport Properties in Chronic Rhinosinusitis

BACKGROUND

Epithelial ion transport regulates hydration of airway mucosal surfaces, and thus promotes effective mucociliary clearance (MCC). Decreased transepithelial Cl^- transport may contribute to epithelial dysfunction by abrogating MCC and increasing mucus viscosity in chronic rhinosinusitis (CRS). The objective of the current study is to evaluate Cl^- channel transport properties from cultures of human sinonasal epithelia.

METHODS

Human sinonasal epithelia (HSNE) from patients undergoing sinus surgery were cultured at an air-liquid interface to confluence and full differentiation. The epithelial monolayers were mounted in Ussing Chambers to investigate pharmacological manipulation of ion transport. Epithelial Na⁺ channel (via Amiloride), CFTR (via forskolin), and Ca²⁺-activated Cl^- channel (CaCC, via UTP) transport were investigated among three different patient groups: Control, CRS and CRS with polyposis. CFTR mRNA levels were evaluated with quantitative RT-PCR.

RESULTS

HSNE cultures from 18 patients (Control = 9, CRS = 6, CRS with polyposis = 3) were evaluated in 142 experiments. Summary data from the 18 patients demonstrated that stimulated CFTR-mediated anion transport (Δ I_SC) was significantly lower with CRS (7.58+/-2.24 µA/cm²) compared to control (25.86+/-3.44 µA/cm²) and CRS with polyposis (20.16+/-4.0 µA/cm²) (p = 0.004). No statistically significant difference was found for CaCC anion transport between groups (p = 0.39). Significantly decreased mRNA (relative expression) was noted in CRS cultures (CRS = 40.83+/-1.76 vs. control = 116.2+/-24.27, p = 0.03).

CONCLUSIONS

A substantial decrease in the Cl^- secretory capacity of HSNE monolayers was demonstrated in CRS subjects. Data suggest that CFTR may contribute more to abnormal ion transport in CRS than CaCC.

TRPV4-Mediated Epithelial Junction Disruption in Allergic Rhinitis Triggered by House Dust Mites

BACKGROUND

Epithelial barrier disruption is a crucial feature of allergic rhinitis (AR). Previous reports have indicated the role of transient receptor potential vanilloid (TRPV) 4 in regulating the intercellular junctions in various cells. However, the role of TRPV4 and its regulation by T helper 2 cell cytokines in the epithelial cells of patients with AR remains unclear.

OBJECTIVE

We aimed to elucidate the expression of TRPV4 in nasal epithelial cells and its cytokine-induced regulation, and to reveal its role in house dust mite-induced junction disruption in AR.

METHODS

The expression of TRPV4 in nasal epithelial cells was measured using real-time polymerase chain reaction, western blot, and immunohistochemical assays, and the expression levels were compared between the patients with AR and healthy controls. Altered expression of TRPV4 was induced in cultured nasal epithelial cells by stimulation of interleukin (IL) 4, IL-13, and tumor necrosis factor alpha. In addition, expression of E-cadherin and zonula occludens 1 was induced in Der p 1-stimulated epithelial cells by treatment with either a TRPV4 agonist (GSK1016790A) or a TRPV4 antagonist (RN1734).

RESULTS

TRPV4 expression was increased in epithelial cells harvested from the affected turbinates compared to those from the normal turbinates. The stimulation of cultured epithelial cells with IL-4 and IL-13 resulted in TRPV4 upregulation. Additionally, E-cadherin and zonula occludens 1 expression levels decreased in the cultured epithelial cells treated with GSK1016790A after stimulation with Der p 1, whereas Der p 1 stimulation alone showed no effect on junctional protein expression.

CONCLUSIONS

Increased TRPV4 expression occurred in epithelial cells harvested from patients with AR and epithelial cells stimulated by Th2 cytokines. Decreased junctional protein expression in epithelial cells after the stimulation by house dust mite allergen with TRPV4 agonist indicates a possible role of TRPV4 in the pathogenesis of allergen-induced epithelial barrier disruption in AR.

Azithromycin and ciprofloxacin inhibit interleukin-8 secretion without disrupting human sinonasal epithelial integrity in vitro

BACKGROUND

We recently developed a ciprofloxacin and azithromycin sinus stent (CASS) to target recalcitrant infections in chronic rhinosinusitis (CRS). The objective of this study was to evaluate the anti-inflammatory activity of azithromycin released from the CASS and assess the impact on the integrity and function of primary human sinonasal epithelial cells (HSNECs).

METHODS

Pseudomonas aeruginosa lipopolysaccharide (LPS)-stimulated HSNECs were treated with azithromycin and/or ciprofloxacin at concentrations attainable from CASS release. Interleukin-8 (IL-8) secretion was quantified by enzyme-linked immunosorbent assay (ELISA). Epithelial integrity (transepithelial resistance [TEER], paracellular permeability [fluorescein isothiocyanate-labeled dextran], lactate dehydrogenase [LDH] assays) and function (ciliary beat frequency [CBF]) were also evaluated.

RESULTS

Azithromycin significantly reduced secreted IL-8 from P. aeruginosa LPS-stimulated HSNECs at all concentrations tested (mean ± standard deviation; control = 5.77 ± 0.39 ng/mL, azithromycin [6 μg/mL] = 4.58 ± 0.40 ng/mL, azithromycin [60 µg/mL] = 4.31 ± 0.06, azithromycin [180 µg/mL] = 4.27 ± 0.26 ng/mL, p < 0.05). Co-incubation with azithromycin (6 µg/mL) and ciprofloxacin (2.4 µg/mL) in LPS-stimulated HSNECs also displayed a significant reduction in secreted IL-8 when compared to P. aeruginosa LPS alone (co-treatment = 4.61 ± 0.29 ng/mL, P. aeruginosa LPS = 7.35 ± 0.89 ng/mL, p < 0.01). The drugs did not negatively impact TEER, paracellular permeability, LDH release, or CBF, indicating retention of cell integrity and function.

CONCLUSION

Azithromycin decreased P. aeruginosa LPS IL-8 production in HSNECs at drug concentrations attainable with sustained release of azithromycin from the CASS. In addition to antibacterial activity, anti-inflammatory properties of the CASS should provide further benefit for patients with recalcitrant CRS.

Resveratrol and ivacaftor are additive G551D CFTR-channel potentiators: therapeutic implications for cystic fibrosis sinus disease

BACKGROUND

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene result in defective Cl^- transport and cause chronic bacterial infections in the upper and lower airways of cystic fibrosis (CF) patients. Ivacaftor is a CFTR potentiator that improves Cl^- transport in CF patients with at least 1 copy of the G551D mutation. Resveratrol is also a potent CFTR potentiator that increases determinants of mucociliary transport. The objective of this study is to determine whether resveratrol and ivacaftor improve Cl^- secretion in G551D CFTR over either agent alone.

METHODS

Fisher rat thyroid cells (FRT) transfected with G551D CFTR and human sinonasal epithelial cells (HSNE) containing the CFTR G551D mutation were subjected to pharmacologic manipulation of transepithelial ion transport in Ussing chambers. Activity was further evaluated using whole-cell patch clamp methods in G551D FRT cells.

RESULTS

In G551D FRT cells, resveratrol (100 μM) and ivacaftor (10 μM) significantly increased Cl^- transport (change in short-circuit current, δI_SC = μA/cm² ) compared with single-agent and dimethylsulfoxide vehicle controls (resveratrol + ivacaftor 4.97 ± 0.57 vs ivacaftor 0.74 ± 0.12 vs resveratrol 2.96 ± 0.52 vs control 0.74 ± 0.12; p < 0.001). Maximal Cl^- secretion (20 μM forskolin) was also significantly enhanced (p < 0.0001). Activity was confirmed in G551D HSNE (resveratrol + ivacaftor 4.48 ± 0.39 vs ivacaftor 1.05 ± 0.11 vs. resveratrol 0.84 ± 0.3 vs control, 0.0 ± 0.02; p < 0.001), and whole-cell patch clamp analysis in G551D FRT cells (resveratrol + ivacaftor -2535 ± 179.3 pA vs ivacaftor -1408.9 ± 101.3 pA vs resveratrol; -766.2 ± 71.2 pA; p < 0.0001).

CONCLUSION

Additive improvement in G551D CFTR-mediated Cl^- secretion suggests that resveratrol could enhance ivacaftor therapy in these patients and improve CF-related rhinosinusitis.

Silica nanoparticles inhibit the cation channel TRPV4 in airway epithelial cells

BACKGROUND

Silica nanoparticles (SiNPs) have numerous beneficial properties and are extensively used in cosmetics and food industries as anti-caking, densifying and hydrophobic agents. However, the increasing exposure levels experienced by the general population and the ability of SiNPs to penetrate cells and tissues have raised concerns about possible toxic effects of this material. Although SiNPs are known to affect the function of the airway epithelium, the molecular targets of these particles remain largely unknown. Given that SiNPs interact with the plasma membrane of epithelial cells we hypothesized that they may affect the function of Transient Receptor Potential Vanilloid 4 (TRPV4), a cation-permeable channel that regulates epithelial barrier function. The main aims of this study were to evaluate the effects of SiNPs on the activation of TRPV4 and to determine whether these alter the positive modulatory action of this channel on the ciliary beat frequency in airway epithelial cells.

RESULTS

Using fluorometric measurements of intracellular Ca²⁺ concentration ([Ca²⁺]_i) we found that SiNPs inhibit activation of TRPV4 by the synthetic agonist GSK1016790A in cultured human airway epithelial cells 16HBE and in primary cultured mouse tracheobronchial epithelial cells. Inhibition of TRPV4 by SiNPs was confirmed in intracellular Ca²⁺ imaging and whole-cell patch-clamp experiments performed in HEK293T cells over-expressing this channel. In addition to these effects, SiNPs were found to induce a significant increase in basal [Ca²⁺]_i, but in a TRPV4-independent manner. SiNPs enhanced the activation of the capsaicin receptor TRPV1, demonstrating that these particles have a specific inhibitory action on TRPV4 activation. Finally, we found that SiNPs abrogate the increase in ciliary beat frequency induced by TRPV4 activation in mouse airway epithelial cells.

CONCLUSIONS

Our results show that SiNPs inhibit TRPV4 activation, and that this effect may impair the positive modulatory action of the stimulation of this channel on the ciliary function in airway epithelial cells. These findings unveil the cation channel TRPV4 as a primary molecular target of SiNPs.

Protective and antifungal properties of Nanodisk-Amphotericin B over commercially available Amphotericin B

Objective

Amphotericin B (AMB), a potent antifungal agent, has been employed as topical and systemic therapy for sinonasal fungal infections. A novel formulation of nanodisc (ND) containing super aggregated AMB (ND-AMB) for the treatment of fungal infections has been recently developed to provide greater protection from AMB toxicity than current, clinically approved lipid-based formulations. The objective of the current study was to evaluate the safety and potency of ND-AMB for sinonasal delivery using an in vitro model.

Methods

Human sinonasal tissue was harvested during endoscopic sinus surgery and grown at air–liquid interface until well-differentiated. Cultures were exposed to ND-AMB vs AMB and changes in K⁺ permeability and resistance were measured and recorded via Ussing chamber assay. Ciliary beat frequency (CBF) was analyzed in parallel as well as cytotoxic assay. Potency was assessed using real-time PCR measurement of the Aspergillus fumigatus 18S rRNA.

Results

Ussing chamber studies revealed K⁺ currents that increased rapidly within 30 s of adding AMB (10 μg/mL) to the apical side, indicating apical membranes had become permeable to K⁺ ions. In contrast, negligible induction of K⁺ current was obtained following addition of ND-AMB [AMB = (107.7 ± 15.9) μA/cm² AMB vs ND-AMB = (2.3 ± 0.7) μA/cm² ND-AMB; P = 0.005]. ND-AMB also protected nasal epithelial cells from cytotoxicity of AMB (P < 0.05). There was no difference in ciliary beat frequency between the two groups (P = 0.96). The expression of A. fumigatus 18S rRNA with exposure of lower dose of ND-AMB was significantly lower compared to that with AMB (P < 0.05).

Conclusions

Data from the present study suggests ND-AMB protects human nasal epithelia membranes from AMB toxicity by protecting against apical cell K⁺ permeability while maintaining uncompromised antifungal property compared to AMB. ND-AMB could provide a novel topical therapy for sinonasal fungal diseases.

Cystic fibrosis transmembrane conductance regulator activation by the solvent ethanol: implications for topical drug delivery

BACKGROUND

Decreased cystic fibrosis transmembrane conductance regulator (CFTR)-mediated chloride (Cl) secretion across mucosal surfaces contributes to the development of airway disease by depleting airway surface liquid, increasing mucus viscosity and adhesion, and consequently hindering mucociliary clearance. We serendipitously discovered during testing of drugs solubilized in low concentrations ethanol (0.25%, 43 mM) that the control vehicle produced robust activation of CFTR-mediated Cl(-) transport. The objective of the current study is to investigate low concentrations of ethanol for effects on Cl(-) secretion and ciliary beat frequency (CBF).

METHODS

Wild-type (WT) and transgenic CFTR(-/-) primary murine nasoseptal epithelial (MNSE) cultures and WT and F508del/F508del human sinonasal epithelial (HSNE) cultures were subjected to transepithelial ion transport measurements using pharmacologic manipulation in Ussing chambers. CBF activation was also monitored. Murine nasal potential difference (NPD) was measured in vivo.

RESULTS

Ussing chamber tracings revealed ethanol activated CFTR-mediated Cl transport in a dose-dependent fashion in WT MNSE (n = 4, p < 0.05) and HSNE (n = 4, p < 0.05). Ethanol also significantly increased CBF (fold change) in WT MNSE cultures in a dose-dependent fashion (phosphate-buffered saline [PBS], 1.33 ± 0.04; 0.25% ethanol, 1.37 ± 0.09; 0.5% ethanol, 1.53 ± 0.06 [p < 0.05]; 1% ethanol, 1.62 ± 0.1 [p < 0.05]). Lack of stimulation in CFTR(-/-) and F508del/F508del cultures indicated activity was dependent on the presence of intact functional CFTR. Ethanol perfusion (0.5%) resulted in a significant -3.5-mV mean NPD polarization when compared to control solution (p < 0.05).

CONCLUSION

The observation that brief exposure of ethanol stimulated Cl(-) secretion via CFTR-mediated pathways indicates its possible use as topical aerosol delivered alone or in combination with other CFTR activators for diseases of dysfunctional mucociliary clearance (MCC) in chronic rhinosinusitis (CRS).

Neural Abnormalities in Nonallergic Rhinitis

Sensory nerve endings within the airway epithelial cells and the solitary chemoreceptor cells, synapsing with sensory nerves, respond to airborne irritants. Transient receptor potential (TRP) channels (A1 and V1 subtypes, specifically) on these nerve endings initiate local antidromic reflexes resulting in the release of neuropeptides such as substance P and calcitonin G-related peptides. These neuropeptides dilate epithelial submucosal blood vessels and may therefore increase transudation across these vessels resulting in submucosal edema, congestion, and rhinitis. Altered expression or activity of these TRP channels can therefore influence responsiveness to irritants. Besides these pathogenic mechanisms, additional mechanisms such as dysautonomia resulting in diminished sympathetic activity and comparative parasympathetic overactivity have also been suggested as a probable mechanism. Therapeutic effectiveness for this condition has been demonstrated through desensitization of TRPV1 channels with typical agonists such as capsaicin. Other agents effective in treating nonallergic rhinitis (NAR) such as azelastine have been demonstrated to exhibit TRPV1 channel activity through the modulation of Ca(2+) signaling on sensory neurons and in nasal epithelial cells. Roles of antimuscarinic agents such as tiotropium in NAR have been suggested by associations of muscarinic cholinergic receptors with TRPV1. The associations between these channels have also been suggested as mechanisms of airway hyperreactivity in asthma. The concept of the united airway disease hypothesis suggests a significant association between rhinitis and asthma. This concept is supported by the development of late-onset asthma in about 10-40 % of NAR patients who also exhibit a greater severity in their asthma. The factors and mechanisms associating NAR with nonallergic asthma are currently unknown. Nonetheless, free immunoglobulin light chains and microRNA alteration as mediators of these inflammatory conditions may play key roles in this association.

Chlorogenic Acid Activates CFTR-Mediated Cl- Secretion in Mice and Humans: Therapeutic Implications for Chronic Rhinosinusitis

OBJECTIVES

Salubrious effects of the green coffee bean are purportedly secondary to high concentrations of chlorogenic acid. Chlorogenic acid has a molecular structure similar to bioflavonoids that activate transepithelial Cl(-) transport in sinonasal epithelia. In contrast to flavonoids, the drug is freely soluble in water. The objective of this study is to evaluate the Cl(-) secretory capability of chlorogenic acid and its potential as a therapeutic activator of mucus clearance in sinus disease.

STUDY DESIGN

Basic research.

SETTING

Laboratory.

SUBJECTS AND METHODS

Chlorogenic acid was tested on primary murine nasal septal epithelial (MNSE) (CFTR(+/+) and transgenic CFTR(-/-)) and human sinonasal epithelial (HSNE) (CFTR(+/+) and F508del/F508del) cultures under pharmacologic conditions in Ussing chambers to evaluate effects on transepithelial Cl(-) transport. Cellular cyclic adenosine monophosphate (cAMP), phosphorylation of the CFTR regulatory domain (R-D), and CFTR mRNA transcription were also measured.

RESULTS

Chlorogenic acid stimulated transepithelial Cl(-) secretion (change in short-circuit current [ΔISC = µA/cm(2)]) in MNSE (13.1 ± 0.9 vs 0.1 ± 0.1; P < .05) and HSNE (34.3 ± 0.9 vs 0.0 ± 0.1; P < .05). The drug had a long duration until peak effect at 15 to 30 minutes after application. Significant inhibition with INH-172 as well as absent stimulation in cultures lacking functional CFTR suggest effects are dependent on CFTR-mediated pathways. However, the absence of elevated cellular cAMP and phosphorylation the CFTR R-D indicates chlorogenic acid does not work through a PKA-dependent mechanism.

CONCLUSION

Chlorogenic acid is a water-soluble agent that promotes CFTR-mediated Cl(-) transport in mouse and human sinonasal epithelium. Translating activators of mucociliary transport to clinical use provides a new therapeutic approach to sinus disease. Further in vivo evaluation is planned.

Resveratrol ameliorates abnormalities of fluid and electrolyte secretion in a hypoxia-Induced model of acquired CFTR deficiency

OBJECTIVE/HYPOTHESIS

Ineffective mucociliary clearance (MCC) is a common pathophysiologic process that underlies airway inflammation and infection. A dominant fluid and electrolyte secretory pathway in the nasal airways is governed by the cystic fibrosis transmembrane conductance regulator (CFTR). Decreased transepithelial Cl(-) transport secondary to an acquired CFTR deficiency may exacerbate respiratory epithelial dysfunction by diminishing MCC and increasing mucus viscosity. The objectives of the present study are to 1) develop a model of acquired CFTR deficiency in sinonasal epithelium using hypoxia, 2) investigate whether the polyphenol resveratrol promotes CFTR-mediated anion transport, 3) explore resveratrol mechanism of action and determine therapeutic suitability for overcoming acquired CFTR defects, and 4) test the drug in the hypoxic model of acquired CFTR deficiency in preparation for a clinical trial in human sinus disease. We hypothesize that hypoxia will induce depletion of airway surface liquid (ASL) secondary to acquired CFTR deficiency and that resveratrol will restore transepithelial Cl(-) secretion and recover ASL hydration.

STUDY DESIGN

Basic science.

METHODS

Murine nasal septal (MNSE) and human sinonasal epithelial (HSNE) cultures were incubated under hypoxic conditions (1% O2 , 5% CO2 ) and transepithelial ion transport (change in short-circuit current = ΔISC ) evaluated in Ussing chambers. Resveratrol was tested using primary cells and HEK293 cells expressing human CFTR by Ussing chamber and patch clamp techniques under both phosphorylating and nonphosphorylating conditions. CFTR activation was evaluated in human explants and by murine in vivo (nasal potential difference) assessment. Cellular cyclic adenosine monophosphate (cAMP) (ELISA) and subsequent CFTR regulatory domain (R-D) phosphorylation (gel-shift assay) were also evaluated. Effects of hypoxia and resveratrol on ASL were tested using confocal laser scanning microscopy (CLSM) and micro-optical coherence tomography (µOCT).

RESULTS

Hypoxia significantly decreased ΔISC (in µA/cm(2) ) attributable to CFTR at 12 and 24 hours of exposure in both MNSE (13.55 ± 0.46 [12 hours]; 12.75 ± 0.07 [24 hours] vs. 19.23 ± 0.18 [control]; P < 0.05) and HSNE (19.55 ± 0.56 [12 hours]; 17.67 ± 1.13 [24 hours] vs. 25.49 ± 1.48 [control]; P < 0.05). We have shown that resveratrol (100 μM) enhanced CFTR-dependent Cl(-) secretion in HSNE to an extent comparable to the recently Food and Drug Administration-approved CFTR potentiator, ivacaftor. Cl(-) transport across human sinonasal explants (78.42 ± 1.75 vs. 1.75 ± 1.5 [control]; P < 0.05) and in vivo murine nasal epithelium (-4 ± 1.8 vs. -0.8 ± 1.7 mV [control]; P < 0.05) were also significantly increased by the drug. No increase in cAMP or CFTR R-D phosphorylation was detected. Inside-out patches showed increased CFTR open probability (NPo/N (N = channel number]) compared to controls in both MNSE (0.329 ± 0.116 vs. 0.119 ± 0.059 [control]; P < 0.05) and HEK293 cells (0.22 ± 0.048 vs. 0.125 ± 0.07 [control]; P < 0.05). ASL thickness was decreased under hypoxic conditions when measured by CLSM (4.19 ± 0.44 vs. 6.88 ± 0.67 [control]; P < 0.05). A 30-minute apical application of resveratrol increased ASL depth in normal epithelium (8.08 ± 1.68 vs. 6.11 ± 0.47 [control]; P < 0.05). Furthermore, hypoxia-induced abnormalities of fluid and electrolyte secretion in sinonasal epithelium were restored with resveratrol treatment (5.55 ± 0.74 vs. 3.13 ± 0.17 [control]; P < 0.05).

CONCLUSIONS

CFTR activation with a leading edge Cl(-) secretagogue such as resveratrol represents an innovative approach to overcoming acquired CFTR defects in sinus and nasal airway disease. This exciting new strategy bears further testing in non-CF individuals with chronic rhinosinusitis.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 125:S1-S13, 2015.

Sinupret activates CFTR and TMEM16A-dependent transepithelial chloride transport and improves indicators of mucociliary clearance

Introduction

We have previously demonstrated that Sinupret, an established treatment prescribed widely in Europe for respiratory ailments including rhinosinusitis, promotes transepithelial chloride (Cl⁻) secretion in vitro and in vivo. The present study was designed to evaluate other indicators of mucociliary clearance (MCC) including ciliary beat frequency (CBF) and airway surface liquid (ASL) depth, but also investigate the mechanisms that underlie activity of this bioflavonoid.

Methods

Primary murine nasal septal epithelial (MNSE) [wild type (WT) and transgenic CFTR^−/−], human sinonasal epithelial (HSNE), WT CFTR-expressing CFBE and TMEM16A-expressing HEK cultures were utilized for the present experiments. CBF and ASL depth measurements were performed. Mechanisms underlying transepithelial Cl⁻ transport were determined using pharmacologic manipulation in Ussing chambers, Fura-2 intracellular calcium [Ca²⁺]_i imaging, cAMP signaling, regulatory domain (R-D) phosphorylation of CFTR, and excised inside out and whole cell patch clamp analysis.

Results

Sinupret-mediated Cl⁻ secretion [ΔI_SC(µA/cm²)] was pronounced in WT MNSE (20.7+/−0.9 vs. 5.6+/−0.9(control), p<0.05), CFTR^−/− MNSE (10.1+/−1.0 vs. 0.9+/−0.3(control), p<0.05) and HSNE (20.7+/−0.3 vs. 6.4+/−0.9(control), p<0.05). The formulation activated Ca²⁺ signaling and TMEM16A channels, but also increased CFTR channel open probability (Po) without stimulating PKA-dependent pathways responsible for phosphorylation of the CFTR R-domain and resultant Cl⁻ secretion. Sinupret also enhanced CBF and ASL depth.

Conclusion

Sinupret stimulates CBF, promotes transepithelial Cl⁻ secretion, and increases ASL depth in a manner likely to enhance MCC. Our findings suggest that direct stimulation of CFTR, together with activation of Ca²⁺-dependent TMEM16A secretion account for the majority of anion transport attributable to Sinupret. These studies provide further rationale for using robust Cl⁻ secretagogue based therapies as an emerging treatment modality for common respiratory diseases of MCC including acute and chronic bronchitis and CRS.

Porcine nasal epithelial cultures for studies of cystic fibrosis sinusitis

BACKGROUND

Transgenic cystic fibrosis (CF) murine models do not develop spontaneous lung or sinus disease, 2 major causes of morbidity in human CF patients. Because of these limitations, transgenic cystic fibrosis transmembrane conductance regulator (CFTR)(-/-) pigs have been developed and are currently being characterized. These CF animal models have phenotypes closely resembling that of human CF subjects. The objectives of the current study were to develop primary porcine nasal epithelial (PNE) cultures and evaluate their usefulness as a means to investigate sinonasal transepithelial transport and CFTR function.

METHODS

PNE derived from the septum or turbinates of CFTR(+/+) and CFTR(-/-) pigs were cultured at an air-liquid interface to confluence and full differentiation. Epithelial monolayers were mounted in Ussing chambers to investigate pharmacologic manipulation of ion transport. Ciliary beat frequency (CBF) and scanning electron microscopy of monolayers were used to indicate degree of ciliation and cell differentiation.

RESULTS

Stimulation of CFTR-mediated anion transport (ΔIsc in μA/cm(2) ) was significantly greater in epithelia derived from the septum when compared to turbinates (33.04 ± 1.17 vs 18.9 ± 0.73; p < 0.05). Cyclic adenosine monophosphate (cAMP)-activated Cl(-) secretion was absent in CFTR(-/-) and present in CFTR(+/+) epithelia. Calcium-activated Cl(-) (CaCC) secretion was increased in CF; however, overall Cl(-) transport through CaCCs was very low. Degree of ciliation (90%) and CBF were similar between groups.

CONCLUSION

Septal PNE exhibit a robust ion transport phenotype and indicate CFTR(-/-) sinus disease could be attributable to diminished alternative pathways for Cl(-) transport. Overall, PNE have similarities to human respiratory epithelia not demonstrated in murine cells and represent useful in vitro models for studying CF sinus disease.

The TRPV4 channel

The widely distributed TRPV4 cationic channel participates in the transduction of both physical (osmotic, mechanical, and heat) and chemical (endogenous, plant-derived, and synthetic ligands) stimuli. In this chapter we will review TRPV4 expression, biophysics, structure, regulation, and interacting partners as well as physiological and pathological insights obtained in TRPV4 animal models and human genetic studies.

Polyhydrated ionogen with MgBr2 accelerates in vitro respiratory epithelial healing

BACKGROUND

Remucoslization of the sinonasal cavity after sinus surgery is critical for successful outcomes. Recently, a novel antiprotease and antifibroblast compound, polyhydrated ionogen (PHI) with MgBr2, showed improved wound healing in a rabbit maxillary sinus mucosal wound model. We set out to determine if this effect was reproducible in an in vitro respiratory epithelial culture system.

METHODS

Fully differentiated mature murine nasal septal air-liquid interface cultures were injured by creating a full-thickness 400-mM-wide scratch through the monolayer. Cultures were then treated with nothing, saline, or PHI with MgBr2 for 1 hour on the apical surface. Twenty-four hours after the injury cultures were fixed and processed for immunofluorescence with type IV beta-tubulin and Hoechst stain.

RESULTS

Initial injury resulted in a wound of 394 micromolar (377-411 micromoler; 95% CI; n = 8). After 24 hours with no intervention the wound closed to 161 micromolar (138-184 micromolar; 95% CI; n = 9) and treatment with saline resulted in a residual gap of 88 micromolar (60-116 micromolar; 95% CI; n = 9; p < 0.05) and treatment with PHI with MgBr2 resulted in a gap of only 30 micromolar (14-46 micromolar; 95% CI; n = 9; p < 0.05).

CONCLUSION

Poor healing of the sinonasal mucosa after surgery with loss of ciliary function results in adverse clinical outcomes. In an in vitro sinonasal respiratory epithelial injury model, a one-time treatment with PHI with MgBr2 showed significantly improved wound healing compared with saline or nothing. This is a viable model to further investigate the mechanism by which PHI with MgBr2 improves sinonasal remucosolization.

Comparison of cystic fibrosis transmembrane conductance regulator (CFTR) and ciliary beat frequency activation by the CFTR Modulators Genistein, VRT-532, and UCCF-152 in primary sinonasal epithelial cultures

IMPORTANCE

Pharmacologic activation of mucociliary clearance (MCC) represents an emerging therapeutic strategy for patients with chronic rhinosinusitis, even in the absence of congenital mutations of the CFTR gene. Drug discovery efforts have identified small molecules that activate the cystic fibrosis transmembrane conductance regulator (CFTR), including potentiators under development for treatment of cystic fibrosis.

OBJECTIVE

To evaluate the properties of CFTR modulators and their effects on ciliary beat frequency (CBF) in human sinonasal epithelium (HSNE).

DESIGN

Primary HSNE cultures (wild type and F508del/F508del) were used to compare stimulation of CFTR-mediated Cl- conductance and CBF by the CFTR modulators genistein, VRT-532, and UCCF-152.

MAIN OUTCOMES AND MEASURES

Increase in CFTR-dependent anion transport and CBF.

RESULTS

HSNE cultures were analyzed using pharmacologic manipulation of ion transport (change in short-circuit current [∆ISC]) and high-speed digital imaging (CBF). Activation of CFTR-dependent anion transport was significantly different among agonists (P < .001), with genistein exerting the greatest effect (mean [SD] ∆ISC, genistein, 23.1 [1.8] μA/cm2² > VRT-532, 8.1 [1.0] μA/cm² > UCCF-152, 3.4 [1.4] μA/cm² > control, 0.7 [0.2] μA/cm²; Tukey-Kramer P < .05) in the absence of forskolin. Genistein and UCCF-152 augmented CBF (under submerged conditions) significantly better (Tukey-Kramer P < .05) than cells treated with VRT-532 or dimethyl sulfoxide vehicle control (mean [SD] fold change over baseline, genistein, 1.63 [0.06]; UCCF-152, 1.56 [0.06]; VRT-532, 1.38 [0.08]; control, 1.27 [0.02]). Activation of CBF was blunted in F508del/F508del HSNE cultures.

CONCLUSIONS AND RELEVANCE

The degree of CBF stimulation was not dependent on the magnitude of Cl- secretion, suggesting that different mechanisms of action may underlie MCC activation by these small molecule potentiators. Agents that activate both CFTR-dependent ISC and CBF are particularly attractive as therapeutics because they may address 2 independent pathways that contribute to deficient MCC in chronic rhinosinusitis.

Resveratrol enhances airway surface liquid depth in sinonasal epithelium by increasing cystic fibrosis transmembrane conductance regulator open probability

BACKGROUND

Chronic rhinosinusitis engenders enormous morbidity in the general population, and is often refractory to medical intervention. Compounds that augment mucociliary clearance in airway epithelia represent a novel treatment strategy for diseases of mucus stasis. A dominant fluid and electrolyte secretory pathway in the nasal airways is governed by the cystic fibrosis transmembrane conductance regulator (CFTR). The objectives of the present study were to test resveratrol, a strong potentiator of CFTR channel open probability, in preparation for a clinical trial of mucociliary activators in human sinus disease.

METHODS

Primary sinonasal epithelial cells, immortalized bronchoepithelial cells (wild type and F508del CFTR), and HEK293 cells expressing exogenous human CFTR were investigated by Ussing chamber as well as patch clamp technique under non-phosphorylating conditions. Effects on airway surface liquid depth were measured using confocal laser scanning microscopy. Impact on CFTR gene expression was measured by quantitative reverse transcriptase polymerase chain reaction.

RESULTS

Resveratrol is a robust CFTR channel potentiator in numerous mammalian species. The compound also activated temperature corrected F508del CFTR and enhanced CFTR-dependent chloride secretion in human sinus epithelium ex vivo to an extent comparable to the recently approved CFTR potentiator, ivacaftor. Using inside out patches from apical membranes of murine cells, resveratrol stimulated an ~8 picosiemens chloride channel consistent with CFTR. This observation was confirmed in HEK293 cells expressing exogenous CFTR. Treatment of sinonasal epithelium resulted in a significant increase in airway surface liquid depth (in µm: 8.08+/-1.68 vs. 6.11+/-0.47,control,p<0.05). There was no increase CFTR mRNA.

CONCLUSION

Resveratrol is a potent chloride secretagogue from the mucosal surface of sinonasal epithelium, and hydrates airway surface liquid by increasing CFTR channel open probability. The foundation for a clinical trial utilizing resveratrol as a therapeutic intervention to increase mucociliary transport and airway surface liquid hydration in sinus disease is strongly supported by these findings.

TRP channels

TRP channels constitute a large superfamily of cation channel forming proteins, all related to the gene product of the transient receptor potential (trp) locus in Drosophila. In mammals, 28 different TRP channel genes have been identified, which exhibit a large variety of functional properties and play diverse cellular and physiological roles. In this article, we provide a brief and systematic summary of expression, function, and (patho)physiological role of the mammalian TRP channels.

TRPV4-mediated calcium influx and ciliary activity in human native airway epithelial cells

The transient receptor potential vanilloid 4 (TRPV4) is a calcium permeable ion channel expressed in airway epithelial cells. Based on studies of cell lines and animals, TRPV4 has been suggested to play a role in the regulation of ciliary beat frequency (CBF). Whether the same is true for human ciliated epithelial cells is not known. Therefore, the aim was to examine the expression and function of TRPV4 in human native nasal epithelial cells. Expression of TRPV4 mRNA in nasal epithelial cells and in the cell lines BEAS2B and 16HBE was confirmed by quantitative real-time PCR. A marked apical TRPV4 immunoreactivity was observed in nasal epithelial cells using immunocytochemistry. Responses to pharmacological modulation of TRPV4 were assessed with calcium imaging and CBF measurements. The TRPV4 agonist GSK1016790A produced concentration-dependent calcium responses in TRPV4-expressing HEK293, BEAS2B and 16HBE cells, and the TRPV4 antagonist HC067047 caused a rightward shift of the GSK1016790A concentration-response curves. Nasal epithelial cells responded to the TRPV4 agonist GSK1016790A with increased intracellular calcium signals and increased CBF, followed by cessation of ciliary beating and cell death. These effects were prevented or inhibited by the TRPV4 antagonist HC067047, the TRP channel blocker ruthenium red or removal of extracellular calcium. We conclude that TRPV4 is expressed in human primary nasal epithelial cells and modulates epithelial calcium levels and CBF. Thus, TRPV4 may participate in mucociliary clearance and airway protection. However, exaggerated activation of TRPV4 may result in epithelial cell death.

Quercetin increases cystic fibrosis transmembrane conductance regulator-mediated chloride transport and ciliary beat frequency: therapeutic implications for chronic rhinosinusitis

BACKGROUND

Increasing epithelial chloride (Cl(-)) secretion in the upper airways represents a putative method for promoting mucociliary clearance through augmentation of airway surface liquid depth. Several naturally occurring flavonoid compounds, including quercetin, have shown the capacity to increase transepithelial Cl(-) transport. Quercetin exhibits well-known antioxidant and anti-inflammatory activity and is now recognized as a potent activator of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel activity in a fashion largely independent of cyclic adenosine monophosphate signaling. The present study investigates whether this compound activates Cl(-) secretion and ciliary beat frequency (CBF) in well-characterized culture models of sinonasal epithelium.

METHODS

Cystic fibrosis and non-cystic fibrosis primary human sinonasal epithelial (HSNE) and murine nasal septal epithelial (MNSE) cultures were studied for transepithelial ion transport in Ussing chambers under voltage clamp conditions and CBF was performed using pharmacologic manipulation.

RESULTS

Change in short circuit current (DeltaI(SC), expressed as microamperes per squared centimeter) in response to quercetin were significantly greater than controls in both MNSE (23.23 ± 5.44 versus 2.47 ± 1.62; p < 0.0001) and HSNE (-8.72 ± 1.88 versus -1.88 ± 0.66; p < 0.01) cultures. CBF was significantly increased in quercetin-treated cells (expressed as fold change over baseline) in wild type (1.65 ± 0.13 versus 1.23 ± 0.05 [control]; p < 0.01), but not CFTR(-/-) (1.65 ± 0.29 versus 1.48 ± 0.38; p = 0.23).

CONCLUSION

Quercetin significantly increased transepithelial Cl(-) transport and CBF in MNSE and HSNE cultures. Future studies investigating quercetin as a means to promote mucociliary transport in individuals with rhinosinusitis are warranted.

Cystic fibrosis transmembrane conductance regulator modulation by the tobacco smoke toxin acrolein

OBJECTIVES/HYPOTHESIS

Evidence indicates that decreased mucociliary clearance (MCC) is a major contributing feature to chronic rhinosinusitis. Tobacco-smoke exposure is thought to inhibit transepithelial Cl(-) secretion, a major determinant of airway surface liquid hydration and MCC. The objective of the current study was to evaluate the effects of acrolein exposure (a prominent tobacco smoke toxin) on vectorial Cl(-) transport through the major apical anion channel cystic fibrosis transmembrane conductance regulator (CFTR) in sinonasal epithelium.

STUDY DESIGN

In vitro investigation.

METHODS

Primary murine nasal septal epithelia (MNSE; wild-type and transgenic CFTR(-/-)) cultures were exposed to acrolein in Ussing chambers and the effects on Cl(-) secretion investigated using pharmacologic manipulation. Cellular cyclic adenosine monophosphate (cAMP) signaling and cytotoxicity were also investigated.

RESULTS

Acrolein stimulated Cl(-) secretion (ΔI(SC) - change in short-circuit current in μA/cm(2)) at concentrations similar to smoker's airways (100 μM, 15.8 ± 2.2 vs. 2.4 ± 0.8 [control]; P < .0001), suppressed forskolin-stimulated C- transport at 300 μM (13.3 ± 1.2 vs. 19.9 ± 1.0; P < .01), and completely abolished all transport at 500 μM (-1.1 ± 1.6). Stimulated Cl(-) secretion was solely reliant upon the presence of CFTR (confirmed in transgenic CFTR(-/-) MNSE), but independent of cAMP signaling. Inhibition at higher concentrations was not secondary to cellular cytotoxicity.

CONCLUSIONS

The present study demonstrates that acrolein has complex but pronounced interaction with the major apical Cl(-) transport mechanism that uses CFTR. Further investigations are required to determine acrolein's impact as a tobacco smoke constituent on mucociliary transport.

Transepithelial ion transport is suppressed in hypoxic sinonasal epithelium

OBJECTIVES/HYPOTHESIS

Sinonasal respiratory epithelial mucociliary clearance is dependent on the transepithelial transport of ions such as Cl(-) . The objectives of the present study were to investigate the role of oxygen restriction in 1) Cl(-) transport across primary sinonasal epithelial monolayers, 2) expression of the apical Cl(-) channels cystic fibrosis transmembrane conductance regulator (CFTR) and transmembrane protein 16A (TMEM16A), and 3) the pathogenesis of chronic rhinosinusitis.

STUDY DESIGN

In vitro investigation.

METHODS

Murine nasal septal epithelial (MNSE), wild type, and human sinonasal epithelial (HSNE) cultures were incubated under hypoxic conditions (1% O(2) , 5% CO(2) ). Cultures were mounted in Ussing chambers for ion transport measurements. CFTR and TMEM16A expression were measured using quantitative reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

The change in short-circuit current (ΔI(SC) in microamperes per square centimeter) attributable to CFTR (forskolin-stimulated) was significantly decreased due to a 12-hour hypoxia exposure in both MNSE (13.55 ± 0.46 vs. 19.23 ± 0.18) and HSNE (19.55 ± 0.56 vs. 25.49 ± 1.48 [control]; P < .05). TMEM16A (uridine triphosphate-stimulated transport) was inhibited by 48 hours of hypoxic exposure in MNSE (15.92 ± 2.87 vs. 51.44 ± 3.71 [control]; P < .05) and by 12 hours of hypoxic exposure in HSNE (16.75 ± 0.68 vs. 24.15 ± 1.35 [control]). Quantitative RT-PCR (reported as relative mRNA levels ± standard deviation) demonstrated significant reductions in both CFTR and TMEM16A mRNA expression in MNSE and HSNE owing to airway epithelial hypoxia.

CONCLUSIONS

Sinonasal epithelial CFTR and TMEM16A-mediated Cl(-) transport and mRNA expression were robustly decreased in an oxygen-restricted environment. These findings indicate that persistent hypoxia may lead to acquired defects in sinonasal Cl(-) transport in a fashion likely to confer mucociliary dysfunction in chronic rhinosinusitis.

Resveratrol has salutary effects on mucociliary transport and inflammation in sinonasal epithelium

OBJECTIVE/HYPOTHESIS

Therapeutic agents that enhance mucociliary transport (via stimulation of transepithelial Cl- secretion) and inhibit inflammation could provide considerable advantages over conventional treatments for chronic rhinosinusitis (CRS). The objectives of the present study were to investigate whether the polyphenolic compound resveratrol promotes transepithelial Cl- transport and inhibits KC/IL-8 secretion in sinonasal epithelium.

STUDY DESIGN

In vitro and in vivo study.

METHODS

Transepithelial Cl- transport was investigated in primary murine nasal septal (MNSE) and human sinonasal epithelial (HSNE) cultures. In vivo activity was also measured using the murine nasal potential difference assay. CFTR R-domain phosphorylation and cAMP levels were examined as a test of cAMP/PKA-dependent activation. In vitro LPS-induced KC/IL-8 secretion was quantified and compared to a panel of intranasal steroids.

RESULTS

Resveratrol(100 μM) significantly increased CFTR-mediated Cl- transport (change in short-circuit current, ΔI(SC) ) in both MNSE (13.51 ± 0.77 vs. 4.4 ± 0.66 [control]; P < .05) and HSNE (12.28 ± 1.08 vs. 0.69 ± 0.32 [control]; P < .05). Cl- secretion across in vivo murine nasal epithelium was also enhanced (-4 ± 1.8 vs. -0.8 ± 1.7mV [control], P < .05). There was no increase in cellular cAMP or CFTR R-domain phosphorylation detected. Resveratrol also significantly inhibited KC/IL-8 secretion in a dose-dependent fashion (pg/mL) in MNSE (181 ± 39[100 μM) vs. 94 ± 16 [200 μM] vs. 16 ± 22 [500 μM] vs. 1195 ± 355 [LPS control]; P < .001). The compound robustly abrogated KC/IL-8 secretion when compared to ciclesonide (765 ± 139), triamcinolone (561 ± 124), and budesonide (742 ± 428), but had similar activity to fluticasone proprionate (65 ± 47). Similar effects were demonstrated in HSNE (975 ± 244 [100 μM] vs. 1825 ± 144 [LPS control]; P < .001) with inhibition comparable to fluticasone proprionate (785 ± 277).

CONCLUSIONS

These in vitro and in vivo findings indicate resveratrol is a potent Cl- secretagogue and anti-inflammatory agent. Future clinical trials for CRS are warranted.

Hesperidin stimulates cystic fibrosis transmembrane conductance regulator-mediated chloride secretion and ciliary beat frequency in sinonasal epithelium

OBJECTIVE

Pharmacologic agents designed to promote mucociliary clearance (MCC) in chronic rhinosinusitis (CRS) represent a novel therapeutic strategy. The objectives of the present study were to investigate whether the natural bioflavonoid hesperidin 1) increases transepithelial chloride (Cl(-)) secretion in vitro and in vivo, 2) enhances ciliary beat frequency (CBF), and 3) exerts its mechanistic effects through cAMP/PKA-dependent pathways.

STUDY DESIGN

In vitro and in vivo study.

SETTING

Laboratory.

SUBJECTS AND METHODS

Transepithelial Cl(-) transport (Ussing chamber) and CBF were investigated in primary murine nasal septal (MNSE) and human sinonasal epithelial (HSNE) cultures. In vivo activity was measured using the murine nasal potential difference (NPD) assay, cystic fibrosis transmembrane conductance regulator (CFTR) R-domain phosphorylation, and cAMP levels were investigated to rule out a cAMP/PKA-dependent mechanism of activation.

RESULTS

Hesperidin significantly increased CFTR-mediated Cl(-) transport (change in short-circuit current, DeltaI(SC)) in both MNSE (13.51 +/- 0.77 vs 4.4 +/- 0.66 [control]; P < 0.05) and HSNE (12.28 +/- 1.08 vs 0.69 +/- 0.32 [control]; P < 0.05). Cl(-) transport across in vivo murine nasal epithelium was also significantly enhanced with hesperidin (-2.3 +/- 1.0 vs -0.8 +/- 0.8 mV [control], P < 0.05). There was no increase in cellular cAMP or phosphorylation of the CFTR R-domain. Hesperidin significantly increased CBF (ratio of pretreatment to post-treatment) with both basal (1.31 +/- 0.07 vs 0.93 +/- 0.06 [control]; P < 0.05), apical (1.72 +/- 0.09 vs 1.40 +/- 0.07 [control]; P < 0.05), and basal + apical delivery (2.26 +/- 0.18 vs 1.60 +/- 0.21, respectively; P < 0.05).

CONCLUSION

Our in vitro and in vivo investigations provide strong support for future testing of this robust Cl(-) secretagogue and CBF activator in human clinical trials for CRS.

Exposure to cigarette smoke condensate reduces calcium activated chloride channel transport in primary sinonasal epithelial cultures

OBJECTIVES/HYPOTHESIS

The cystic fibrosis transmembrane conductance regulator (CFTR) serves as a predominant Cl(-) transport conduit in airway epithelium and is inhibited by cigarette smoke in vitro and in vivo. Activation of secondary Cl(-) transport pathways through calcium-activated Cl(-) channels (CaCC) has been postulated as a mechanism to bypass defects in CFTR-mediated transport. Because it is not known whether CaCCs are also inhibited by tobacco exposure, the current study was designed to investigate the effect of cigarette smoke condensate (CSC) on CaCC transport.

STUDY DESIGN

In vitro study.

METHODS

Well-characterized primary murine nasal septal epithelial (MNSE) and human sinonasal epithelial (HSNE) cultures were exposed to CSC in Ussing chambers. We monitored CaCC short-circuit current through stimulation of P2Y purinergic receptors with uridine triphosphate or adenosine triphosphate and selective inhibition of the CFTR-dependent secretory pathway. Characterization of CaCC current was also accomplished in primary airway cells derived from transgenic CFTR(-/-) (knockout) murine models.

RESULTS

Change in CaCC-mediated current (DeltaI(SC) representing transepithelial Ca-mediated Cl(-) secretion in muA/cm(2)) was significantly decreased in CSC-exposed wild type MNSE when compared to controls (32.8 +/- 4.6 vs. 47.5 +/- 2.3; respectively; P < .02). A similar effect was demonstrated in CFTR(-/-) MNSE cultures (33.4 +/- 2.8 vs. 38.6 +/- 2.0; P < .05>. HSNE cultures also had a significant reduction in I(SC) (16.1 +/- 0.6 vs. 22.7 +/- 0; P = .008).

CONCLUSIONS

CSC affects multiple pathways fundamental to airway ion transport, including both cyclic adenosine monophosphate and calcium activated Cl(-) transport. Inhibition of Cl(-) transport may contribute to common diseases of the airways, such as chronic rhinosinusitis and chronic obstructive pulmonary disease.

The bioflavonoid compound, sinupret, stimulates transepithelial chloride transport in vitro and in vivo

OBJECTIVES/HYPOTHESIS

Dehydration of airway surface liquid (ASL) disrupts normal mucociliary clearance in sinonasal epithelium leading to chronic rhinosinusitis. Abnormal chloride (Cl(-)) transport is one mechanism that contributes to this disorder, as demonstrated by the disease cystic fibrosis. Identifying safe compounds that stimulate transepithelial Cl(-) transport is critical to improving hydration of the ASL and promoting mucociliary transport. Sinupret (Bionorica, LLC, San Clemente, CA), a combination of naturally occurring bioflavonoids, is a widely used treatment for respiratory ailments in Europe. However, the effects of Sinupret on target respiratory epithelium have yet to be fully investigated. The present study evaluated the mechanisms underlying this bioflavonoid therapeutic on transepithelial Cl(-) transport in respiratory epithelium.

STUDY DESIGN

In vitro and in vivo investigation.

METHODS

Well characterized murine nasal septal epithelial (MNSE) cultures, and murine nasal potential difference (NPD) techniques were used to evaluate the effects of Sinupret on Cl(-) secretion.

RESULTS

The change in Sinupret-stimulated current (Delta I(SC) expressed as microA/cm(2)) in MNSE, representing Cl(-) secretion, was significantly increased when compared to controls (19.04 + or - 1.67 microA/cm(2) vs. 1.8 + or - 0.35 microA/cm(2), respectively; P = .00005). Transepithelial Cl(-) transport measured in the murine NPD in vivo assay (n = 42) was also significantly enhanced when compared to controls (-0.8 mV vs. -0.9 mV; P = .0004). Importantly, Sinupret-stimulated Cl(-) transport was substantially more robust in vivo than forskolin, a compound among the strongest known cystic fibrosis transmembrane conductance regulator activators (-3.8 mV vs. -1.65 mV; P = .01).

CONCLUSIONS

Sinupret strongly activates transepithelial Cl(-) secretion through a mechanism known to hydrate the ASL of respiratory epithelium. This is one means by which the medication is likely to exert therapeutic benefit.

Cigarette smoke condensate inhibits transepithelial chloride transport and ciliary beat frequency

OBJECTIVES/HYPOTHESIS

Although the pathophysiology leading to rhinosinusitis is complex, evidence indicates that decreased mucociliary clearance (MCC) is a major contributing feature. Normal respiratory epithelial MCC is an important host defense mechanism that is dependent on proper ciliary beating and the biological properties of the airway surface liquid (ASL). The role that tobacco smoke exposure plays as an inhibitor of MCC has yet to be elucidated. The present study investigates the consequences of cigarette smoke exposure on ciliary function and transepithelial chloride (Cl(-)) secretion, a major determinant of ASL.

STUDY DESIGN

In vitro investigation.

METHODS

Well-characterized primary murine nasal septal epithelial (MNSE) and human sinonasal epithelial (HSNE) cultures were exposed to cigarette smoke condensate (CSC) and compared to control cultures. Effects on ciliary beat frequency (CBF) and Cl(-) secretion were investigated using pharmacologic manipulation.

RESULTS

Change in forskolin-stimulated current (DeltaI(SC)), representing transepithelial Cl(-) secretion, was significantly decreased in CSC exposed MNSE (14.97 +/- 1.2 microA/cm(2) vs. control, 19.1 +/- 1.56 microA/cm(2) [P = .04]) and HSNE (2.68 +/- 0.79 muA/cm(2) vs. control, 10.8 +/- 1.73 microA/cm(2)) cultures (P = .001). Forskolin-stimulated CBF was also significantly reduced when acutely exposed to CSC (5.64 +/- 0.06 Hz vs. control 7.15 +/- 0.18 Hz).

CONCLUSIONS

The present study provides direct evidence that tobacco smoke diminishes two major components of MCC. This links tobacco smoke as a potential contributing and/or exacerbating factor in exposed individuals with chronic rhinosinusitis.

The vanilloid transient receptor potential channel TRPV4: from structure to disease

The Transient Receptor Potential Vanilloid 4 channel, TRPV4, is a Ca(2+) and Mg(2+) permeable non-selective cation channel involved in many different cellular functions. It is activated by a variety of physical and chemical stimuli, including heat, mechano-stimuli, endogenous substances such as arachidonic acid and its cytochrome P450-derived metabolites (epoxyeicosatrienoic acids), endocannabinoids (anandamide and 2-arachidonoylglycerol), as well as synthetic alpha-phorbol derivatives. Recently, TRPV4 has been characterized as an important player modulating osteoclast differentiation in bone remodelling and as a urothelial mechanosensor that controls normal voiding. Several TRPV4 gain-of-function mutations are shown to cause autosomal-dominant bone dysplasias such as brachyolmia and Koszlowski disease. In this review we comprehensively describe the structural, biophysical and (patho)physiological properties of the TRPV4 channel and we summarize the current knowledge about the role of TRPV4 in the pathogenesis of several diseases.

Effect of L-ascorbate on chloride transport in freshly excised sinonasal epithelia

BACKGROUND

Chronic rhinosinusitis (CRS) occurs at high frequency in patients with cystic fibrosis, suggesting that the cystic fibrosis transmembrane conductance regulator (CFTR) chloride (Cl) ion channel might be involved in the development of chronic sinusitis in the general population. CFTR Cl ion transport controls the hydration of mucosal surfaces and promotes effective mucociliary clearance. Altered ion transport and, hence, disrupted mucociliary function, could play a role in the pathogenesis of sinus disease. L-ascorbate is a metabolically active component of the nasal and tracheobronchial airway lining fluids and appears to serve as an important biological effector of CFTR-mediated chloride secretion. The purpose of this study was to determine the effects of L-ascorbate on Cl ion transport in freshly excised sinonasal epithelia from normal controls and patients with CRS.

METHODS

Four different types of sinonasal tissue (normal sinus mucosa, sinus mucosa from CRS, normal nasal mucosa, nasal mucosa from CRS) were obtained during endoscopic sinus surgery and mounted on sliders with open areas of 0.03-0.71 cm2 between Ussing hemichambers. Short-circuit current (Isc) was continuously recorded, and a serosa-to-mucosa-directed Cl gradient was applied to increase the electrochemical driving force.

RESULTS

L-ascorbate (500 microM) stimulated Cl currents (DeltaI(Cl), microA/cm2) across sinonasal epithelia from normal and CRS patients. The Cl secretory response to L-ascorbate was effectively blocked by the Cl ion transport inhibitors glibenclamide and bumetanide. A maximal dose of L-ascorbate (at 1 mM) stimulated 53-70% of Cl currents elicited by the cAMP agonist forskolin. CRS sinonasal tissue was characterized by impaired Cl secretory responses to L-ascorbate that were reduced by 33% in sinus epithelial tissue and by 70% in nasal epithelial tissue when compared with normal subjects. In nasal epithelial tissue from normal subjects, Cl secretion was approximately twofold increased when compared with sinus epithelial tissue. In contrast, nasal versus sinus epithelial tissue from CRS patients showed no differences.

CONCLUSION

Topical administration of L-ascorbate to freshly excised sinus and nasal mucosa enhances chloride secretion. Given that decreased CFTR-mediated Cl secretion may contribute to the development of CRS, L-ascorbate may offer potential as a therapeutic agent for the improvement of mucociliary clearance.

Comparison of vectorial ion transport in primary murine airway and human sinonasal air-liquid interface cultures, models for studies of cystic fibrosis, and other airway diseases

BACKGROUND

The purpose of this study was to compare vectorial ion transport within murine trachea, murine nasal septa, and human sinonasal cultured epithelium. Our hypothesis is that murine septal epithelium, rather than trachea, will more closely mimic the electrophysiology properties of human sinonasal epithelium.

METHODS

Epithelium from murine trachea, murine septa, and human sinonasal tissue were cultured at an air-liquid interface to confluence and full differentiation. A limited number of homozygous dF508 epithelia were also cultured. Monolayers were mounted in modified Ussing chambers to investigate pharmacologic manipulation of ion transport.

RESULTS

The change in forskolin-stimulated current (delta-I(SC), expressed as micro-A/cm(2)) in murine septal (n = 19; 16.84 +/- 2.09) and human sinonasal (n = 18; 12.15 +/- 1.93) cultures was significantly increased over murine tracheal cultures (n = 15; 6.75 +/- 1.35; p = 0.035 and 0.0005, respectively). Forskolin-stimulated I(SC) was inhibited by the specific cystic fibrosis transmembrane regulator (CFTR) inhibitor INH-172 (5 microM). No forskolin-stimulated I(SC) was shown in cultures of dF508 homozygous murine septal epithelium (n = 3). Murine septal I(SC) was largely inhibited by amiloride (12.03 +/- 0.66), whereas human sinonasal cultures had a very limited response (0.70 +/- 0.47; p < 0.0001). The contribution of CFTR to stimulated chloride current as measured by INH-172 was highly significantly different between all groups (murine septa, 19.51 +/- 1.28; human sinonasal, 11.12 +/- 1.58; murine trachea, 4.85 +/- 0.49; p < 0.0001).

CONCLUSION

Human sinonasal and murine septal epithelial cultures represent a useful model for studying CFTR activity and may provide significant advantages over lower airway tissues for investigating upper and lower respiratory pathophysiology.