Transepithelial ion transport is suppressed in hypoxic sinonasal epithelium

Lipopolysaccharide Causes Acquired CFTR Dysfunction in Murine Nasal Airways

OBJECTIVE

Cystic fibrosis (CF) is a clinical entity defined by aberrant chloride (Cl-) ion transport causing downstream effects on mucociliary clearance (MCC) in sinonasal epithelia. Inducible deficiencies in transepithelial Cl- transport via CF transmembrane conductance regulator (CFTR) has been theorized to be a driving process in recalcitrant chronic rhinosinusitis (CRS) in patients without CF. We have previously identified that brief exposures to bacterial lipopolysaccharide (LPS) in mammalian cells induces an acquired dysfunction of CFTR in vitro and in vivo. The objective of the current study is to evaluate whether LPS generates a model of acquired CFTR dysfunction murine nasal airways.

STUDY DESIGN

Basic science.

SETTING

Laboratory.

METHODS

CFTR+/+ murine nasal airways were irrigated with 2 µg/mL LPS or control vehicle twice daily for 1 week and transepithelial Cl- transport assessed with the nasal potential difference (NPD) assay. Histopathologic evaluation included the number of lymphoid aggregates, as well as the epithelial and subepithelial heights.

RESULTS

Transepithelial Cl- secretion by NPD was markedly reduced in mice exposed to LPS (in mV, -0.14 ± 7.7 vs control, -6.98 ± 7.15, P < .05), while amiloride-sensitive voltage was preserved (6.38 ± 5.09 vs control, 7.36 ± 2.87, P = .99). Histopathology demonstrated significantly higher lymphoid aggregates per high-power field (2.3 ± 0.9 vs 1.1 ± 0.7, control, P < .01) and increased epithelial height (in µm, 40.88 ± 13.9 vs control, 25.32 ± 6.26, P < .05).

CONCLUSION

Twice daily irrigation with LPS in murine nasal airways over 1 week led to acquired defects in transepithelial Cl- transport. This animal model provides an excellent means to test the contributions of acquired CFTR dysfunction to CRS and test CFTR correctors and potentiators that might improve MCC.

CFTR as a therapeutic target for severe lung infection

Lung infection is one of the leading causes of morbidity and mortality worldwide. Even with appropriate antibiotic and antiviral treatment, mortality in hospitalized patients often exceeds 10%, highlighting the need for the development of new therapeutic strategies. Of late, cystic fibrosis transmembrane conductance regulator (CFTR) is-in addition to its well-established roles in the lung airway and extrapulmonary organs-increasingly recognized as a key regulator of alveolar homeostasis and defense. In the alveolar epithelium, CFTR mediates alveolar fluid secretion and liquid homeostasis; in the microvascular endothelium, CFTR maintains vascular barrier function. CFTR also contributes to alveolar immunity. Yet, in lung infection, diverse molecular mechanisms reduce CFTR abundance and otherwise impair its function, promoting alveolar inflammation, edema, and cell death. Preservation or restoration of CFTR function by CFTR modulator drugs thus presents a promising avenue to combat lung infection in a pathogen-independent manner.

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.

Glutathione and bicarbonate nanoparticles improve mucociliary transport in cystic fibrosis epithelia

INTRODUCTION

Cystic fibrosis (CF) airway disease is characterized by thick mucus and impaired mucociliary transport (MCT). Loss of functional cystic fibrosis transmembrane receptor (CFTR) leads to acidification and oxidation of airway surface mucus. Replacing bicarbonate (HCO3 -) topically fails due to rapid reabsorption and neutralization, while the scavenging antioxidant, glutathione sulfhydryl (GSH), is also rapidly degraded. The objective of this study is to investigate GSH/NaHCO3 nanoparticles as novel strategy for CF airway disease.

METHODS

GSH/NaHCO3 poly (lactic-co-glycolic acid) nanoparticles were tested on primary CF (F508del/F508del) epithelial cultures to evaluate dose-release curves, surface pH, toxicity, and MCT indices using micro-optical coherence tomography. In vivo tests were performed in three rabbits to assess safety and toxicity. After 1 week of daily injections, histopathology, computed tomography (CT), and blood chemistries were performed and compared to three controls. Fluorescent nanoparticles were injected into a rabbit with maxillary sinusitis and explants visualized with confocal microscopy.

RESULTS

Sustained release of GSH and HCO3 - with no cellular toxicity was observed over 2 weeks. Apical surface pH gradually increased from 6.54 ± 0.13 (baseline) to 7.07 ± 0.10 (24 h) (p < 0.001) and 6.87 ± 0.05 at 14 days (p < 0.001). MCT, ciliary beat frequency, and periciliary liquid were significantly increased. When injected into the maxillary sinuses of rabbits, there were no changes to histology, CT, or blood chemistries. Nanoparticles penetrated rabbit sinusitis mucus on confocal microscopy.

CONCLUSION

Findings suggest that GSH/NaHCO3 - nanoparticles are a promising treatment option for viscous mucus in CF and other respiratory diseases of mucus obstruction such as chronic rhinosinusitis.

Hypoxia-inducible factor 1α activates the NLRP3 inflammasome to regulate epithelial differentiation in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is an upper airway inflammation disease associated with hypoxia-mediated inflammation. The effect of hypoxia-inducible factor 1α (HIF-1α) on NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in the pathogenesis of sinonasal mucosa is unclear.

OBJECTIVE

We investigated the effect and mechanism of HIF-1α on NLRP3 inflammasome activation in the primary human nasal epithelial cells (hNECs).

METHODS

We measured the expression levels of HIF-1α and the NLRP3 inflammasome in nasal biopsy samples and hNECs derived from negative controls (healthy) and patients with CRS with and without nasal polyps, then further analyzed the specific mechanism of HIF-1α regulation of the NLRP3 inflammasome and its effect on hNEC differentiation.

RESULTS

Increased mRNA and protein expression levels of HIF-1α and the NLRP3 inflammasome were found in all CRS biopsy samples. HIF-1α enhanced expression of phosphorylated NLRP3 (S295) in both HEK293T cells and hNECs; it also promoted recruitment of caspase-1 and apoptotic speck-like protein containing caspase recruitment domain (aka ASC) by NLRP3. HIF-1α also improved NLRP3's stability by preventing NLRP3 degradation caused by hypoxia-mediated inflammation. In addition, HIF-1α could also increase expression of Mucin5AC and decrease expression of α-tubulin by promoting activation of the NLRP3 inflammasome in hNECs. In addition, HIF-1α could also directly promote P63 expression in hNECs.

CONCLUSION

HIF-1α could potentially induce cilia loss and enhance the proliferation of goblet cells, possibly mediated by the regulation of NLRP3 phosphorylation in CRS inflammation.

Red ginseng aqueous extract improves mucociliary transport dysfunction and histopathology in CF rat airways

BACKGROUND

We previously discovered that Korean red ginseng aqueous extract (RGAE) potentiates the TMEM16A channel, improved mucociliary transport (MCT) parameters in CF nasal epithelia in vitro, and thus could serve as a therapeutic strategy to rescue the MCT defect in cystic fibrosis (CF) airways. The hypothesis of this study is that RGAE can improve epithelial Cl- secretion, MCT, and histopathology in an in-vivo CF rat model.

METHODS

Seventeen 4-month old CFTR-/- rats were randomly assigned to receive daily oral control (saline, n = 9) or RGAE (Ginsenosides 0.4mg/kg/daily, n = 8) for 4 weeks. Outcomes included nasal Cl- secretion measured with the nasal potential difference (NPD), functional microanatomy of the trachea using micro-optical coherence tomography, histopathology, and immunohistochemical staining for TMEM16a.

RESULTS

RGAE-treated CF rats had greater mean NPD polarization with UTP (control = -5.48 +/- 2.87 mV, RGAE = -9.49 +/- 2.99 mV, p < 0.05), indicating, at least in part, potentiation of UTP-mediated Cl- secretion through TMEM16A. All measured tracheal MCT parameters (airway surface liquid, periciliary liquid, ciliary beat frequency, MCT) were significantly increased in RGAE-treated CF rats with MCT exhibiting a 3-fold increase (control, 0.45+/-0.31 vs. RGAE, 1.45+/-0.66 mm/min, p < 0.01). Maxillary mucosa histopathology was markedly improved in RGAE-treated cohort (reduced intracellular mucus, goblet cells with no distention, and shorter epithelial height). TMEM16A expression was similar between groups.

CONCLUSION

RGAE improves TMEM16A-mediated transepithelial Cl- secretion, functional microanatomy, and histopathology in CF rats. Therapeutic strategies utilizing TMEM16A potentiators to treat CF airway disease are appropriate and provide a new avenue for mutation-independent therapies.

Chronic airway epithelial hypoxia exacerbates injury in muco-obstructive lung disease through mucus hyperconcentration

Unlike solid organs, human airway epithelia derive their oxygen from inspired air rather than the vasculature. Many pulmonary diseases are associated with intraluminal airway obstruction caused by aspirated foreign bodies, virus infection, tumors, or mucus plugs intrinsic to airway disease, including cystic fibrosis (CF). Consistent with requirements for luminal O2, airway epithelia surrounding mucus plugs in chronic obstructive pulmonary disease (COPD) lungs are hypoxic. Despite these observations, the effects of chronic hypoxia (CH) on airway epithelial host defense functions relevant to pulmonary disease have not been investigated. Molecular characterization of resected human lungs from individuals with a spectrum of muco-obstructive lung diseases (MOLDs) or COVID-19 identified molecular features of chronic hypoxia, including increased EGLN3 expression, in epithelia lining mucus-obstructed airways. In vitro experiments using cultured chronically hypoxic airway epithelia revealed conversion to a glycolytic metabolic state with maintenance of cellular architecture. Chronically hypoxic airway epithelia unexpectedly exhibited increased MUC5B mucin production and increased transepithelial Na+ and fluid absorption mediated by HIF1α/HIF2α-dependent up-regulation of β and γENaC (epithelial Na+ channel) subunit expression. The combination of increased Na+ absorption and MUC5B production generated hyperconcentrated mucus predicted to perpetuate obstruction. Single-cell and bulk RNA sequencing analyses of chronically hypoxic cultured airway epithelia revealed transcriptional changes involved in airway wall remodeling, destruction, and angiogenesis. These results were confirmed by RNA-in situ hybridization studies of lungs from individuals with MOLD. Our data suggest that chronic airway epithelial hypoxia may be central to the pathogenesis of persistent mucus accumulation in MOLDs and associated airway wall damage.

The role of hypoxia in the pathophysiology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal cavity characterized by excessive nasal mucus secretion and nasal congestion. The development of CRS is related to pathological mechanisms induced by hypoxia. Under hypoxic conditions, the stable expression of both Hypoxia inducible factor-1 (HIF-1) α and HIF-2α are involved in the immune response and inflammatory pathways of CRS. The imbalance in the composition of nasal microbiota may affect the hypoxic state of CRS and perpetuate existing inflammation. Hypoxia affects the differentiation of nasal epithelial cells such as ciliated cells and goblet cells, induces fibroblast proliferation, and leads to epithelial-mesenchymal transition (EMT) and tissue remodeling. Hypoxia also affects the proliferation and differentiation of macrophages, eosinophils, basophils, and mast cells in sinonasal mucosa, and thus influences the inflammatory state of CRS by regulating T cells and B cells. Given the multifactorial nature in which HIF is linked to CRS, this study aims to elucidate the effect of hypoxia on the pathogenic mechanisms of CRS.

Physiology and pathophysiology of human airway mucus

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Effects of Hypoxia on Respiratory Diseases: Perspective View of Epithelial Ion Transport

The balance of gas exchange and lung ventilation is essential for the maintenance of body homeostasis. There are many ion channels and transporters in respiratory epithelial cells, including epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator, and some transporters. These ion channels/transporters maintain the capacity of liquid layer on the surface of respiratory epithelial cells, and provide an immune barrier for the respiratory system to clear off foreign pathogens. However, in some harmful external environment and/or pathological conditions, the respiratory epithelium is prone to hypoxia, which would destroy the ion transport function of the epithelium and unbalance the homeostasis of internal environment, triggering a series of pathological reactions. Many respiratory diseases associated with hypoxia manifest an increased expression of hypoxia-inducible factor-1, which mediates the integrity of the epithelial barrier and affects epithelial ion transport function. It is important to study the relationship between hypoxia and ion transport function, whereas the mechanism of hypoxia-induced ion transport dysfunction in respiratory diseases is not clear. This review focuses on the relationship of hypoxia and respiratory diseases, as well as dysfunction of ion transport and tight junctions in respiratory epithelial cells under hypoxia.

TMEM16A as a potential treatment target for head and neck cancer

Transmembrane protein 16A (TMEM16A) forms a plasma membrane-localized Ca²⁺-activated Cl- channel. Its gene has been mapped to an area on chromosome 11q13, which is amplified in head and neck squamous cell carcinoma (HNSCC). In HNSCC, TMEM16A overexpression is associated with not only high tumor grade, metastasis, low survival, and poor prognosis, but also deterioration of clinical outcomes following platinum-based chemotherapy. Recent study revealed the interaction between TMEM16A and transforming growth factor-β (TGF-β) has an indirect crosstalk in clarifying the mechanism of TMEM16A-induced epithelial-mesenchymal transition. Moreover, human papillomavirus (HPV) infection can modulate TMEM16A expression along with epidermal growth factor receptor (EGFR), whose phosphorylation has been reported as a potential co-biomarker of HPV-positive cancers. Considering that EGFR forms a functional complex with TMEM16A and is a co-biomarker of HPV, there may be crosstalk between TMEM16A expression and HPV-induced HNSCC. EGFR activation can induce programmed death ligand 1 (PD-L1) synthesis via activation of the nuclear factor kappa B pathway and JAK/STAT3 pathway. Here, we describe an interplay among EGFR, PD-L1, and TMEM16A. Combination therapy using TMEM16A and PD-L1 inhibitors may improve the survival rate of HNSCC patients, especially those resistant to anti-EGFR inhibitor treatment. To the best of our knowledge, this is the first review to propose a biological validation that combines immune checkpoint inhibition with TMEM16A inhibition.

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.

Medical interventions for chronic rhinosinusitis in cystic fibrosis

BACKGROUND

Chronic rhinosinusitis frequently occurs in people with cystic fibrosis. Several medical interventions are available for treating chronic rhinosinusitis in people with cystic fibrosis; for example, different concentrations of nasal saline irrigations, topical or oral corticosteroids, antibiotics - including nebulized antibiotics - dornase alfa and modulators of the cystic fibrosis transmembrane conductance regulator (CFTR) (such as lumacaftor, ivacaftor or tezacaftor). However, the efficacy of these interventions is unclear. This is an update of a previously published review.

OBJECTIVES

The objective of this review is to compare the effects of different medical interventions in people diagnosed with cystic fibrosis and chronic rhinosinusitis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search of trials register: 09 September 2021. We also searched ongoing trials databases, other medical databases and the reference lists of relevant articles and reviews. Date of latest additional searches: 22 November 2021.

SELECTION CRITERIA

Randomized and quasi-randomized trials of different medical interventions compared to each other or to no intervention or to placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials identified for potential inclusion in the review. We planned to conduct data collection and analysis in accordance with Cochrane methods and to independently rate the quality of the evidence for each outcome using the GRADE guidelines.

MAIN RESULTS

We identified no trials that met the pre-defined inclusion criteria. The most recent searches identified 44 new references, none of which were eligible for inclusion in the current version of this review; 12 studies are listed as excluded and one as ongoing.

AUTHORS' CONCLUSIONS

We identified no eligible trials assessing the medical interventions in people with cystic fibrosis and chronic rhinosinusitis. High-quality trials are needed which should assess the efficacy of different treatment options detailed above for managing chronic rhinosinusitis, preventing pulmonary exacerbations and improving quality of life in people with cystic fibrosis.

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.

Polymodal Control of TMEM16x Channels and Scramblases

The TMEM16A/anoctamin-1 calcium-activated chloride channel (CaCC) contributes to a range of vital functions, such as the control of vascular tone and epithelial ion transport. The channel is a founding member of a family of 10 proteins (TMEM16x) with varied functions; some members (i.e., TMEM16A and TMEM16B) serve as CaCCs, while others are lipid scramblases, combine channel and scramblase function, or perform additional cellular roles. TMEM16x proteins are typically activated by agonist-induced Ca2+ release evoked by Gq-protein-coupled receptor (GqPCR) activation; thus, TMEM16x proteins link Ca2+-signalling with cell electrical activity and/or lipid transport. Recent studies demonstrate that a range of other cellular factors—including plasmalemmal lipids, pH, hypoxia, ATP and auxiliary proteins—also control the activity of the TMEM16A channel and its paralogues, suggesting that the TMEM16x proteins are effectively polymodal sensors of cellular homeostasis. Here, we review the molecular pathophysiology, structural biology, and mechanisms of regulation of TMEM16x proteins by multiple cellular factors.

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.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

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.

Medical interventions for chronic rhinosinusitis in cystic fibrosis

BACKGROUND

Chronic rhinosinusitis frequently occurs in people with cystic fibrosis. Several medical interventions are available for treating chronic rhinosinusitis in people with cystic fibrosis; for example, different concentrations of nasal saline irrigations, topical or oral corticosteroids, antibiotics - including nebulized antibiotics, dornase alfa and modulators of the cystic fibrosis transmembrane conductance regulator (CFTR) (such as lumacaftor, ivacaftor or tezacaftor). However, the efficacy of these interventions is unclear.

OBJECTIVES

The objective of this review is to compare the effects of different medical interventions in people diagnosed with cystic fibrosis and chronic rhinosinusitis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and hand searching of journals and conference abstract books. Date of last search of trials register: 22 May 2019.We also searched ongoing trials databases, other medical databases and the reference lists of relevant articles and reviews. Date of latest additional searches: 20 May 2019.

SELECTION CRITERIA

Randomized and quasi-randomized trials of different medical interventions compared to each other or to no intervention or to placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials identified for potential inclusion in the review. We planned to conduct data collection and analysis in accordance with Cochrane methods and to independently rate the quality of the evidence for each outcome using the GRADE guidelines.

MAIN RESULTS

We identified no trials that met the pre-defined inclusion criteria. The searches identified 47 trials, none of which were eligible for inclusion in the current version of this review.

AUTHORS' CONCLUSIONS

We identified no eligible trials assessing the medical interventions in people with cystic fibrosis and chronic rhinosinusitis. High-quality trials are needed which should assess the efficacy of different treatment options detailed above for managing chronic rhinosinusitis, preventing pulmonary exacerbations and improving quality of life in people with cystic fibrosis.

Effect of Cellulose Powder on Human Nasal Epithelial Cell Activity and Ciliary Beat Frequency

BACKGROUND

Cellulose powder (CP) has been reported as a safe and effective complementary treatment for allergic rhinitis (AR). Currently, CP has gained increasing application for clinical management worldwide, particularly in China. However, studies focusing on the effect of CP on normal human nasal epithelial cells (hNECs) and ciliary function are lacking. Here, we aimed to explore the adverse effects of CP on the activity and ciliary function of hNECs.

METHODS

We biopsied ethmoid sinus or middle turbinate tissues during surgical resection from control subjects who underwent endoscopic sinus surgery for diseases other than AR. Cells were isolated and passaged, followed by differentiation in an air-liquid interface (ALI). Flow cytometry and cell viability test (cell counting kit-8) were performed to detect the cytotoxicity of CP (effects on cell proliferation) on normal hNECs. By using the ALI culture model, we investigated the effects of CP on ciliary beat frequency (CBF).

RESULTS

There was a significant reduction in hNEC count at high concentrations of CP (2.5 mg/mL) at days 3 and 7 (both p < 0.05). As the concentration increased, cell death increased progressively from day 3 to day 7. However, these effects were not evident at low concentrations (0.25 mg/mL, p > 0.05). High-dose CP (2.5 mg) significantly reduced the CBF (p < 0.05). At lower concentrations (0.25-2.5 mg/mL), CP initially increased but subsequently reduced the CBF of hNECs compared with control group.

CONCLUSIONS

Cytotoxicity and the suppression of ciliary beat at high concentrations justify more prudent use of CP for the management of AR.

Acquired cystic fibrosis transmembrane conductance regulator dysfunction

Sinonasal respiratory epithelium is a highly regulated barrier that employs mucociliary clearance (MCC) as the airways first line of defense. The biological properties of the airway surface liquid (ASL), combined with coordinated ciliary beating, are critical components of the mucociliary apparatus. The ASL volume and viscosity is modulated, in part, by the cystic fibrosis transmembrane conductance regulator (CFTR). The CFTR is an anion transporter of chloride (Cl⁻) and bicarbonate (HCO₃⁻) that is located on the apical surface of respiratory epithelium and exocrine glandular epithelium. Improved understanding of how dysfunction or deficiency of CFTR influences the disease process in both genetically defined cystic fibrosis (CF) and acquired conditions has provided further insight into potential avenues of treatment. This review discusses the latest data regarding acquired CFTR deficiency and use of CFTR specific treatment strategies for CRS and other chronic airway diseases.

Submucosal gland mucus strand velocity is decreased in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) may be initiated by innately impaired host defense mechanisms that predispose the upper airways to infection. Recent evidence suggests tethering of submucosal gland mucus strands represents an inciting event within cystic fibrosis (CF) airways, occurring prior to onset of chronic infection. Submucosal gland hypertrophy and defective mucociliary clearance (MCC) are present in actively inflamed sinuses, but mucus strand velocity may also be affected as a secondary event, further contributing to chronic disease. The objective of this study is to assess whether mucus strand velocity is decreased in patients with CRS.

METHODS

Mucosal explants from patients with and without CRS were submerged in Ringer's solution mixed with fluorescent nanospheres. Methacholine was then added, and videos demonstrating strand growth and detachment were generated from a time-lapse of Z-stack images using a multiphoton confocal microscope. Dynamic mucus strands were identified and individual velocities quantified with the MTrackJ plug-in of ImageJ.

RESULTS

Fifteen patients met criteria for ex vivo analysis of mucus strand velocities (CRS, n = 9 vs controls, n = 6). Mucus strands were recorded (pixels/second) streaming from the submucosal gland openings. Average mucus strand velocities were significantly decreased in patients with CRS (1.53 ± 0.67 vs controls, 4.86 ± 1.68 pixels/second; p < 0.001).

CONCLUSION

This study is the first to report evidence of abnormal mucus strand velocity from submucosal glands in diseased sinonasal mucosa. Future pharmacologic studies targeting this critical component of MCC are warranted.

Characterization of primary rat nasal epithelial cultures in CFTR knockout rats as a model for CF sinus disease

OBJECTIVE

The objectives of the current experiments were to develop and characterize primary rat nasal epithelial cultures and evaluate their usefulness as a model of cystic fibrosis (CF) sinonasal transepithelial transport and CF transmembrane conductance regulator (CFTR) function.

STUDY DESIGN

Laboratory in vitro and animal studies.

METHODS

CFTR^+/+ and CFTR^-/- rat nasal septal epithelia (RNSE) were cultured on semipermeable supports at an air-liquid interface to confluence and full differentiation. Monolayers were mounted in Ussing chambers for pharmacologic manipulation of ion transport and compared to similar filters containing murine (MNSE) and human (HSNE) epithelia. Histology and scanning electron microscopy (SEM) were completed. Real-time polymerase chain reaction of CFTR^+/+ RNSE, MNSE, and HSNE was performed to evaluate relative CFTR gene expression.

RESULTS

Forskolin-stimulated anion transport (ΔIsc in μA/cm² ) was significantly greater in epithelia derived from CFTR^+/+ when compared to CFTR^-/- animals (100.9 ± 3.7 vs. 10.5 ± 0.9; P < 0.0001). Amiloride-sensitive I_SC was equivalent (-42.3 ± 2.8 vs. -46.1 ± 2.3; P = 0.524). No inhibition of CFTR-mediated chloride (Cl^- ) secretion was exhibited in CFTR^-/- epithelia with the addition of the specific CFTR inhibitor, CFTR_Inh -172. However, calcium-activated Cl^- secretion (UTP) was significantly increased in CFTR^-/- RNSE (CFTR^-/- -106.8 ± 1.6 vs. CFTR^+/+ -32.2 ± 3.1; P < 0.0001). All responses were larger in RNSE when compared to CFTR^+/+ and CFTR^-/- (or F508del/F508del) murine and human cells (P < 0.0001). Scanning electron microscopy demonstrated 80% to 90% ciliation in all RNSE cultures. There was no evidence of infection in CFTR^-/- rats at 4 months. CFTR expression was similar among species.

CONCLUSION

The successful development of the CFTR^-/- rat enables improved evaluation of CF sinus disease based on characteristic abnormalities of ion transport.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:E384-E391, 2017.

Hypoxia Sensing in Plants: On a Quest for Ion Channels as Putative Oxygen Sensors

Over 17 million km2 of land is affected by soil flooding every year, resulting in substantial yield losses and jeopardizing food security across the globe. A key step in resolving this problem and creating stress-tolerant cultivars is an understanding of the mechanisms by which plants sense low-oxygen stress. In this work, we review the current knowledge about the oxygen-sensing and signaling pathway in mammalian and plant systems and postulate the potential role of ion channels as putative oxygen sensors in plant roots. We first discuss the definition and requirements for the oxygen sensor and the difference between sensing and signaling. We then summarize the literature and identify several known candidates for oxygen sensing in the mammalian literature. This includes transient receptor potential (TRP) channels; K+-permeable channels (Kv, BK and TASK); Ca2+ channels (RyR and TPC); and various chemo- and reactive oxygen species (ROS)-dependent oxygen sensors. Identified key oxygen-sensing domains (PAS, GCS, GAF and PHD) in mammalian systems are used to predict the potential plant counterparts in Arabidopsis. Finally, the sequences of known mammalian ion channels with reported roles in oxygen sensing were employed to BLAST the Arabidopsis genome for the candidate genes. Several plasma membrane and tonoplast ion channels (such as TPC, AKT and KCO) and oxygen domain-containing proteins with predicted oxygen-sensing ability were identified and discussed. We propose a testable model for potential roles of ion channels in plant hypoxia sensing.

Assessment of acquired mucociliary clearance defects using micro-optical coherence tomography

BACKGROUND

Dehydration of airway surface liquid (ASL) disrupts normal mucociliary clearance (MCC) in sinonasal epithelium, which may lead to chronic rhinosinusitis (CRS). Abnormal chloride (Cl^- ) transport is one such mechanism that contributes to this disorder and can be acquired secondary to environmental perturbations, such as hypoxia at the tissue surface. The objective of this study was to assess the technological feasibility of the novel micro-optical coherence tomography (μOCT) imaging technique for investigating acquired MCC defects in cultured human sinonasal epithelial (HSNE) cells.

METHODS

Primary HSNE cell cultures were subjected to a 1% oxygen environment for 12 hours to induce acquired cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. Ion transport characteristics were assessed with pharmacologic manipulation in Ussing chambers. ASL, periciliary fluid (PCL), and ciliary beat frequency (CBF) were evaluated using μOCT.

RESULTS

Amiloride-sensitive transport (ΔI_SC ) was greater in cultures exposed to hypoxia (hypoxia: -13.2 ± 0.6 μA/cm² ; control: -6.5 ± 0.1 μA/cm² ; p < 0.01), whereas CFTR-mediated anion transport was significantly diminished (hypoxia: 28.6 ± 0.3 μA/cm² ; control: 36.2 ± 1.6 μA/cm² ; p < 0.01), consistent with acquired CFTR dysfunction and sodium hyperabsorption. Hypoxia diminished all markers of airway surface function microanatomy as observed with μOCT, including ASL (hypoxia: 5.0 ± 0.4 μm; control: 9.0 ± 0.9 μm; p < 0.01) and PCL depth (hypoxia: 2.5 ± 0.1 μm; control: 4.8 ± 0.3 μm; p < 0.01), and CBF (hypoxia: 8.7 ± 0.3 Hz; control: 10.2 ± 0.3 Hz; p < 0.01).

CONCLUSION

Hypoxia-induced defects in epithelial anion transport in HSNE led to predictable effects on markers of MCC measured with novel μOCT imaging. This imaging method represents a technological leap forward and is feasible for assessing acquired defects impacting the airway surface.

Systemic and Odontogenic Etiologies in Chronic Rhinosinusitis

Systemic and odontogenic etiologies of chronic rhinosinusitis, although rare, are an integral consideration in the comprehensive management of patients with sinonasal disease. Proper knowledge and timely recognition of each disease process, with referrals to appropriate consultants, will facilitate treatment, because many of these conditions require both local and systemic therapy. In some instances, medical therapy plays a pivotal role, with surgery being a supplemental treatment technique. We review the most commonly encountered systemic etiologies of chronic rhinosinusitis and odontogenic sinusitis, including clinical presentation, diagnosis, management, and treatment outcomes.

Inflammatory Disorders Associated with Allergy: Overview of Immunopathogenesis and Implications for Treatment

A number of chronic inflammatory diseases are associated with IgE-mediated immunologic hypersensitivity, including atopic dermatitis, chronic rhinosinusitis, and asthma. Pathogenetic studies of well-characterized patient groups has allowed investigators to more precisely define the molecular pathways involved in these diseases. Specific cytokines and chemokines, as well as other unique proteins, have now been identified in each of these common disorders and a number of medications are currently in development for inhibiting their actions. Continual refinement of our understanding of the pathogenesis of these diseases will undoubtedly yield increasingly precise, and potentially more effective, treatments.

Medical and Surgical Advancements in the Management of Cystic Fibrosis Chronic Rhinosinusitis

PURPOSE OF REVIEW

The purpose of this review is to provide otolaryngologists with the most up-to-date advancements in both the medical and surgical management of CF-related sinus disease.

RECENT FINDINGS

Recent studies have supported more aggressive CRS management, often with a combination of both medical and surgical therapies. Comprehensive treatment strategies have been shown to reduce hospital admissions secondary to pulmonary exacerbations in addition to improving CRS symptoms. Still, current management strategies are lacking in both high-level evidence and standardized guidelines.

SUMMARY

The unified airway model describes the bi-directional relationship between the upper and lower airways as a single functional unit and suggests that CRS may play a pivotal role in both the development and progression of lower airway disease. Current strategies for CF CRS focus primarily on amelioration of symptoms with antibiotics, nasal saline and/or topical medicated irrigations, and surgery. However, there are no definitive management guidelines and there remains a persistent need for additional studies. Nevertheless, otolaryngologists have a significant role in the overall management of CF, which requires a multi-disciplinary approach and a combination of both surgical and medical interventions for optimal outcomes of airway disease. Here we present a review of currently available literature and summarize medical and surgical therapies best suited for the management of CF-related sinus disease.

Single nucleotide polymorphisms related to cystic fibrosis in chronic rhinositus-a pilot study

BACKGROUND

The clinical association between cystic fibrosis (CF) and chronic rhinosinusitis (CRS) is well known. Studies have identified several non-CF transmembrane conductance regulator single nucleotide polymorphisms (SNPs) associated with disease severity in CF patients. We hypothesized that prevalence of these SNPs would be different between CRS patients and age/gender-matched non-CRS controls.

METHODS

This is a targeted SNP study of 1231 CRS patients identified through a large university hospital database who were compared with 8796 age- and gender-matched controls without a history of rhinitis, sinusitis, allergies, or asthma. Prevalence of 5 relevant SNPs was compared between groups, with p < 0.05 considered significant. Stratification by race and gender was performed among groups when statistically appropriate.

RESULTS

CRS patients exhibited a statistically significant (p = 0.036) lower prevalence of rs12883884 (associated with an ion transporter) compared with controls. This association was lost when patients were stratified by race. CRS patients manifested a greater prevalence of rs1403543 (chromosome 23) in both Caucasian and African American subgroups (p = 0.036 and p = 0.026, respectively). Statistical significance disappeared among Caucasians when stratified by gender, but persisted among African American women (p = 0.047). rs12188164 and rs12793173 were both more prevalent in African Americans with CRS than controls (p = 0.042 and p = 0.020, respectively). A trend was also observed for decreased prevalence of rs12883884 in CRS patients compared with controls in the African American subgroup (p = 0.086).

CONCLUSION

The identified SNPs were differentially prevalent in CRS compared with control groups, with some variability as a function of race and gender. Further research is required to confirm these findings and elucidate clinical significance.

Allergic Aspergillus Rhinosinusitis

Allergic fungal rhinosinusitis (AFRS) is a unique variety of chronic polypoid rhinosinusitis usually in atopic individuals, characterized by presence of eosinophilic mucin and fungal hyphae in paranasal sinuses without invasion into surrounding mucosa. It has emerged as an important disease involving a large population across the world with geographic variation in incidence and epidemiology. The disease is surrounded by controversies regarding its definition and etiopathogenesis. A working group on "Fungal Sinusitis" under the International Society for Human and Animal Mycology (ISHAM) addressed some of those issues, but many questions remain unanswered. The descriptions of "eosinophilic fungal rhinosinusitis" (EFRS), "eosinophilic mucin rhinosinusitis" (EMRS) and mucosal invasion by hyphae in few patients have increased the problem to delineate the disease. Various hypotheses exist for etiopathogenesis of AFRS with considerable overlap, though recent extensive studies have made certain in depth understanding. The diagnosis of AFRS is a multi-disciplinary approach including the imaging, histopathology, mycology and immunological investigations. Though there is no uniform management protocol for AFRS, surgical clearing of the sinuses with steroid therapy are commonly practiced. The role of antifungal agents, leukotriene antagonists and immunomodulators is still questionable. The present review covers the controversies, recent advances in pathogenesis, diagnosis, and management of AFRS.

New insights into upper airway innate immunity

BACKGROUND

Protecting the upper airway from microbial infection is an important function of the immune system. Proper detection of these pathogens is paramount for sinonasal epithelial cells to be able to prepare a defensive response. Toll-like receptors and, more recently, bitter taste receptors and sweet taste receptors have been implicated as sensors able to detect the presence of these pathogens and certain compounds that they secrete. Activation of these receptors also triggers innate immune responses to prevent or counteract infection, including mucociliary clearance and the production and secretion of antimicrobial compounds (e.g., defensins).

OBJECTIVE

To provide an overview of the current knowledge of the role of innate immunity in the upper airway, the mechanisms by which it is carried out, and its clinical relevance.

METHODS

A literature review of the existing knowledge of the role of innate immunity in the human sinonasal cavity was performed.

RESULTS

Clinical and basic science studies have shown that the physical epithelial cell barrier, mucociliary clearance, and antimicrobial compound secretion play pivotal innate immune roles in defending the sinonasal cavity from infection. Clinical findings have also linked dysfunction of these defense mechanisms with diseases, such as chronic rhinosinusitis and cystic fibrosis. Recent discoveries have elucidated the significance of bitter and sweet taste receptors in modulating immune responses in the upper airway.

CONCLUSION

Numerous innate immune mechanisms seem to work in a concerted fashion to keep the sinonasal cavity free of infection. Understanding sinonasal innate immune function and dysfunction in health and disease has important implications for patients with respiratory ailments, such as chronic rhinosinusitis and cystic fibrosis.

Innate immunity and chronic rhinosinusitis: What we have learned from animal models

OBJECTIVE

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial disease characterized by dysregulated inflammation. Abnormalities in innate immune function including sinonasal epithelial cell barrier function, mucociliary clearance, response to pathogen-associated molecular patterns (PAMPs) via pattern recognition receptors (PRRs), and the contribution of innate immune cells will be highlighted in this review.

DATA SOURCES

PubMed literature review.

REVIEW METHODS

A review of the literature was conducted to determine what we have learned from animal models in relation to innate immunity and chronic rhinosinusitis.

RESULTS

Dysregulation of innate immune mechanisms including sinonasal barrier function, mucociliary clearance, PAMPs, and innate immune cells such as eosinophils, mast cells, and innate lymphoid cells may contribute to CRS pathogenesis. Sinonasal inflammation has been studied using mouse, rat, rabbit, pig, and sheep explant or in vivo models. Study using these models has allowed for analysis of experimental therapeutics and furthered our understanding of the aforementioned aspects of the innate immune mechanism as it relates to sinonasal inflammation. These include augmenting mucociliary clearance through activation of the cystic fibrosis transmembrane conductance regulator (CFTR) and study of drug toxicity on ciliary beat frequency. Knockout models of Toll-like receptors (TLR) have demonstrated the critical role these PRRs play in allergic inflammation as loss of TLR2 and TLR4 leads to decreased lower airway inflammation. Mast cell deficient mice are less susceptible to ovalbumin-induced sinonasal inflammation.

CONCLUSION

Animal models have shed light as to the potential contribution of dysregulated innate immunity in chronic sinonasal inflammation.

Chronic rhinosinusitis pathogenesis

There are a variety of medical conditions associated with chronic sinonasal inflammation, including chronic rhinosinusitis (CRS) and cystic fibrosis. In particular, CRS can be divided into 2 major subgroups based on whether nasal polyps are present or absent. Unfortunately, clinical treatment strategies for patients with chronic sinonasal inflammation are limited, in part because the underlying mechanisms contributing to disease pathology are heterogeneous and not entirely known. It is hypothesized that alterations in mucociliary clearance, abnormalities in the sinonasal epithelial cell barrier, and tissue remodeling all contribute to the chronic inflammatory and tissue-deforming processes characteristic of CRS. Additionally, the host innate and adaptive immune responses are also significantly activated and might be involved in pathogenesis. Recent advancements in the understanding of CRS pathogenesis are highlighted in this review, with special focus placed on the roles of epithelial cells and the host immune response in patients with cystic fibrosis, CRS without nasal polyps, or CRS with nasal polyps.

Modulating Ca²⁺ signals: a common theme for TMEM16, Ist2, and TMC

Since the discovery of TMEM16A (anoctamin 1, ANO1) as Ca(2+)-activated Cl(-) channel, the protein was found to serve different physiological functions, depending on the type of tissue. Subsequent reports on other members of the anoctamin family demonstrated a broad range of yet poorly understood properties. Compromised anoctamin function is causing a wide range of diseases, such as hearing loss (ANO2), bleeding disorder (ANO6), ataxia and dystonia (ANO3, 10), persistent borrelia and mycobacteria infection (ANO10), skeletal syndromes like gnathodiaphyseal dysplasia and limb girdle muscle dystrophy (ANO5), and cancer (ANO1, 6, 7). Animal models demonstrate CF-like airway disease, asthma, and intestinal hyposecretion (ANO1). Although present data indicate that ANO1 is a Ca(2+)-activated Cl(-) channel, it remains unclear whether all anoctamins form plasma membrane-localized or intracellular chloride channels. We find Ca(2+)-activated Cl(-) currents appearing by expression of most anoctamin paralogs, including the Nectria haematococca homologue nhTMEM16 and the yeast homologue Ist2. As recent studies show a role of anoctamins, Ist2, and the related transmembrane channel-like (TMC) proteins for intracellular Ca(2+) signaling, we will discuss the role of these proteins in generating compartmentalized Ca(2+) signals, which may give a hint as to the broad range of cellular functions of anoctamins.

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).

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.

Management of the upper airway in cystic fibrosis

PURPOSE OF REVIEW

Upper airway disease engenders significant morbidity for patients with cystic fibrosis and is increasingly recognized as having a much greater role in pulmonary outcomes and quality of life than originally believed. Widespread disparate therapeutic strategies for cystic fibrosis chronic rhinosinusitis underscore the absence of a standardized treatment paradigm. This review outlines the most recent evidence-based trends in the management of upper airway disease in cystic fibrosis.

RECENT FINDINGS

The unified airway theory proposes that the sinuses are a focus of initial bacterial colonization which seeds the lower airway and may play a large role in maintaining lung infections. Mounting evidence suggests more aggressive treatment of the sinuses may confer significant improvement in pulmonary disease and quality of life outcomes in cystic fibrosis patients. However, there is a lack of high-level evidence regarding medical and surgical management of cystic fibrosis chronic rhinosinusitis that makes generalizations difficult.

SUMMARY

Well designed clinical trials with long-term follow-up concerning medical and surgical interventions for cystic fibrosis sinus disease are required to establish standardized treatment protocols, but increased interest in the sinuses as a bacterial reservoir for pulmonary infections has generated considerable attention.

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.

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.

Epidemiology and differential diagnosis of nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) is one of the most common chronic medical conditions, with a significant impact on patient quality of life. CRS is broadly classified into two groups: CRS with nasal polyposis (CRSwNP) and CRS without NP (CRSsNP). Clinically, the major subtypes of CRSwNP may be divided into eosinophilic chronic rhinosinusitis (e.g., allergic fungal rhinosinusitis and aspirin-exacerbated respiratory disease [AERD]) and nasal polyps associated with neutrophilic inflammation (e.g., cystic fibrosis [CF]). CF is characterized by mutation of the gene encoding the CF transmembrane conductance regulator. Functional endoscopic sinus surgery is usually required for most NP patients with increased frequency in patients with AERD. This study provides a review of the epidemiology and major classification of CRSwNP.

METHODS

A review was performed of the literature regarding different subtypes of CRSwNP.

RESULTS

Many definitions of CRSwNP exist and estimates of prevalence vary.

CONCLUSION

CRSwNP is a clinical syndrome with a heterogeneous inflammatory profile. Of the subtypes associated with eosinophilic inflammation, AERD remains the most recalcitrant to medical and surgical therapeutic interventions.

Anoctamin 1 dysregulation alters bronchial epithelial repair in cystic fibrosis

Cystic fibrosis (CF) airway epithelium is constantly subjected to injury events due to chronic infection and inflammation. Moreover, abnormalities in CF airway epithelium repair have been described and contribute to the lung function decline seen in CF patients. In the last past years, it has been proposed that anoctamin 1 (ANO1), a Ca(2+)-activated Cl(-) channel, might offset the CFTR deficiency but this protein has not been characterized in CF airways. Interestingly, recent evidence indicates a role for ANO1 in cell proliferation and tumor growth. Our aims were to study non-CF and CF bronchial epithelial repair and to determine whether ANO1 is involved in airway epithelial repair. Here, we showed, with human bronchial epithelial cell lines and primary cells, that both cell proliferation and migration during epithelial repair are delayed in CF compared to non-CF cells. We then demonstrated that ANO1 Cl(-) channel activity was significantly decreased in CF versus non-CF cells. To explain this decreased Cl(-) channel activity in CF context, we compared ANO1 expression in non-CF vs. CF bronchial epithelial cell lines and primary cells, in lung explants from wild-type vs. F508del mice and non-CF vs. CF patients. In all these models, ANO1 expression was markedly lower in CF compared to non-CF. Finally, we established that ANO1 inhibition or overexpression was associated respectively with decreases and increases in cell proliferation and migration. In summary, our study demonstrates involvement of ANO1 decreased activity and expression in abnormal CF airway epithelial repair and suggests that ANO1 correction may improve this process.

Cystic fibrosis chronic rhinosinusitis: a comprehensive review

BACKGROUND

Advances in the care of patients with cystic fibrosis (CF) have improved pulmonary outcomes and survival. In addition, rapid developments regarding the underlying genetic and molecular basis of the disease have led to numerous novel targets for treatment. However, clinical and basic scientific research focusing on therapeutic strategies for CF-associated chronic rhinosinusitis (CRS) lags behind the evidence-based approaches currently used for pulmonary disease.

METHODS

This review evaluates the available literature and provides an update concerning the pathophysiology, current treatment approaches, and future pharmaceutical tactics in the management of CRS in patients with CF.

RESULTS

Optimal medical and surgical strategies for CF CRS are lacking because of a dearth of well-performed clinical trials. Medical and surgical interventions are supported primarily by level 2 or 3 evidence and are aimed at improving clearance of mucus, infection, and inflammation. A number of novel therapeutics that target the basic defect in the cystic fibrosis transmembrane conductance regulator channel are currently under investigation. Ivacaftor, a corrector of the G551D mutation, was recently approved by the Food and Drug Administration. However, sinonasal outcomes using this and other novel drugs are pending.

CONCLUSION

CRS is a lifelong disease in CF patients that can lead to substantial morbidity and decreased quality of life. A multidisciplinary approach will be necessary to develop consistent and evidence-based treatment paradigms.

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.