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

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.

Optical Coherence Tomography as a Tool for Imaging the Sinonasal Mucosa in Patients: A Systematic Review

Objectives: To summarize the current applications and potential uses of optical coherence tomography (OCT), a noninvasive imaging modality that uses near-infrared light to produce cross-sectional, high-resolution images of biologic tissues, for evaluating the sinonasal mucosa in patients. Methods: Original articles utilizing OCT to image the sinonasal mucosa in patients were identified from the PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases using the search phrase: "Optical Coherence Tomography" AND (sinonasal OR intranasal OR sinus OR nose OR sinusitis OR rhinitis OR olfactory). Strength of evidence, quality of evidence, and risk of bias were measured using validated scales. Study results were qualitatively assessed. Results: Out of 1662 original records identified through database searching, 9 studies were included in the systematic review. Levels of evidence ranged from III to IV and quality of evidence ranged from moderate to very low. Endoscopic OCT systems as well as OCT systems integrated with surgical microscopes were described in the literature. Applications of OCT for imaging the sinonasal mucosa included identifying morphological patterns unique to individual diseases, detecting mucosal structural changes after medical therapies and procedures, and evaluating mucociliary clearance. Conclusions: Most studies investigating OCT imaging of the sinonasal mucosa featured small sample sizes and lacked control groups. While OCT imaging could be a useful adjunct for diagnosing sinonasal disorders and monitoring response to treatment in the future, additional high-quality studies are necessary to determine if the use of OCT imaging can lead to improved diagnostic accuracy and health outcomes for patients with sinonasal pathologies.

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.

Low molecular weight hyaluronan inhibits lung epithelial ion channels by activating the calcium-sensing receptor

Herein, we tested the hypothesis that low molecular weight hyaluronan (LMW-HA) inhibits lung epithelial ions transport in-vivo, ex-vivo, and in-vitro by activating the calcium-sensing receptor (CaSR). Twenty-four hours post intranasal instillation of 50-150 µg/ml LMW-HA to C57BL/6 mice, there was a 75% inhibition of alveolar fluid clearance (AFC), a threefold increase in the epithelial lining fluid (ELF) depth, and a 20% increase in lung wet/dry (W/D) ratio. Incubation of human and mouse precision cut lung slices with 150 µg/ml LMW-HA reduced the activity and the open probability (Po) of epithelial sodium channel (ENaC) in alveolar epithelial type 2 (ATII) cells, and in mouse tracheal epithelial cells (MTEC) monolayers as early as 4 h. The Cl- current through cystic fibrosis transmembrane conductance regulator (CFTR) and the activity of Na,K-ATPase were both inhibited by more than 66% at 24 h. The inhibitory effects of LMW-HA on ion channels were reversed by 1 µM NPS-2143, or 150 µg/ml high molecular weight hyaluronan (HMW-HA). In HEK-293 cells expressing the calcium-sensitive Cl- channel TMEM16-A, CaSR was required for the activation of the Cl- current by LMW-HA. This is the first demonstration of lung ions and water transport inhibition by LMW-HA, and its mediation through the activation of CaSR.

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.

A Comparison of Near-Infrared Imaging and Computerized Tomography Scan for Detecting Maxillary Sinusitis

OBJECTIVE

To investigate the use of near-infrared (NIR) imaging as a tool for outpatient clinicians to quickly and accurately assess for maxillary sinusitis and to characterize its accuracy compared to computerized tomography (CT) scan.

METHODS

In a prospective investigational study, NIR and CT images from 65 patients who presented to a tertiary care rhinology clinic were compared to determine the sensitivity and specificity of NIR as an imaging modality.

RESULTS

The sensitivity and specificity of NIR imaging in distinguishing normal versus maxillary sinus disease was found to be 90% and 84%, normal versus mild maxillary sinus disease to be 76% and 91%, and mild versus severe maxillary sinus disease to be 96% and 81%, respectively. The average pixel intensity was also calculated and compared to the modified Lund-Mackay scores from CT scans to assess the ability of NIR imaging to stratify the severity of maxillary sinus disease. Average pixel intensity over a region of interest was significantly different (P < .001) between normal, mild, and severe disease, as well as when comparing normal versus mild (P < .001, 95% CI 42.22-105.39), normal versus severe (P < .001, 95% CI 119.43-174.14), and mild versus severe (P < .001, 95% CI 41.39-104.56) maxillary sinus disease.

CONCLUSION

Based on this data, NIR shows promise as a tool for identifying patients with potential maxillary sinus disease as well as providing information on severity of disease that may guide administration of appropriate treatments.

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.

The effect of Ramadan fasting on nasal mucociliary activity and peak nasal inspiratory flow

PURPOSE

In this study, we aimed to investigate the effect of Ramadan fasting (RF) on nasal mucociliary clearance (MCC) and peak nasal inspiratory flow (PNIF).

METHODS

Sixty-two (41 male and 21 female) healthy subjects who stated that they would fast continuously during the month of Ramadan were included in this prospective study. Day 0 (baseline), 1st day (after one day of RF), and 29th (after 29 days of RF) nasal mucociliary clearance time (MCT) with saccharine test and PNIF values were determined. Subject weights (SW) were measured on Day 0 and Day 29. The obtained data were analyzed statistically.

RESULTS

The mean of SW on day 0 was 78.53 ± 10.95 kg, and the mean of SW on Day 29 was 78.69 ± 10.87 kg. There was no significant difference in terms of SW (p = 0.251, p > 0.05). A significant difference was found between the MCT and PNIF values measured on different study days (p < 0.05). The MCT values for Day 29 were significantly higher than the values for other days (p < 0.05). There was no significant difference between the MCT values on the first day and the baseline (p = 0.891, p > 0.05). The PNIF values for Day 29 were significantly higher than the values for other days (p < 0.05). The PNIF values on the first day were significantly higher than the baseline (p = 0.008, p < 0.05).

CONCLUSION

The present study showed that RF leads to MCT prolongation and PNIF increase. Ramadan fasting causes deterioration in nasal airway defense and improvement in nasal respiration.

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.

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.

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.

Antibiotic eluting sinus stents

OBJECTIVES

Chronic rhinosinusitis (CRS) is a multifactorial disease affecting up to 16% of the United States population and disproportionately affecting the cystic fibrosis (CF) patient population. Despite treating the underlying infection, the use of systemic antibiotics has shown little efficacy in alleviation of symptom burden. This review seeks to discuss recent research on novel antibiotic eluting stent therapy in vitro and within animal models as well as the factors that contribute to its efficacy.

DATA SOURCES

PubMed literature review.

REVIEW METHODS

A review of all published literature related to antibiotic eluting sinus stents was conducted to integrate and summarize this innovative approach to chronic sinus infections.

RESULTS

Placement of the ciprofloxacin sinus stent (CSS) and ciprofloxacin-ivacaftor sinus stent (CISS) exhibited improvement in endoscopic and radiographic findings in rabbit CRS models. While the CSS showed an overall trend toward improvement in microscopic findings and a reduction in biofilm mass, there remained a significant quantity of planktonic bacteria due to antibiotic depletion from an initial burst release in the first 48 hours of stent placement. The CISS and ciprofloxacin-azithromycin sinus stents (CASSs) exhibited controlled antibiotic release over the study period leading to greatly reduced planktonic bacterial load and biofilm mass. In vitro studies indicate that CASS may be just as efficacious at reducing biofilm mass.

CONCLUSION

Antibiotic eluting sinus stents show significant promise as a novel therapeutic strategy for CRS. The CISS may have particular promise for the CF patient population by addressing both the infectious and genetic components of disease. Animal studies demonstrate significant promise for translation into human studies. Human clinical trials are warranted to determine the efficacy of antibiotic sinus stents in human patients.

LEVEL OF EVIDENCE

NA.

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.

The Effects of the Anti-aging Protein Klotho on Mucociliary Clearance

α-klotho (KL) is an anti-aging protein and has been shown to exert anti-inflammatory and anti-oxidative effects in the lung and pulmonary diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. The current study investigated the direct effect of KL on the bronchial epithelium in regards to mucociliary clearance parameters. Primary human bronchial and murine tracheal epithelial cells, cultured, and differentiated at the air liquid interface (ALI), were treated with recombinant KL or infected with a lentiviral vector expressing KL. Airway surface liquid (ASL) volume, airway ion channel activities, and expression levels were analyzed. These experiments were paired with ex vivo analyses of mucociliary clearance in murine tracheas from klotho deficient mice and their wild type littermates. Our results showed that klotho deficiency led to impaired mucociliary clearance with a reduction in ASL volume in vitro and ex vivo. Overexpression or exogenous KL increased ASL volume, which was paralleled by increased activation of the large-conductance, Ca2+-activated, voltage-dependent potassium channel (BK) without effect on the cystic fibrosis transmembrane conductance regulator (CFTR). Furthermore, KL overexpression downregulated IL-8 levels and attenuated TGF-β-mediated downregulation of LRRC26, the γ subunit of BK, necessary for its function in non-excitable cells. In summary, we show that KL regulates mucociliary function by increasing ASL volume in the airways possibly due to underlying BK activation. The KL mediated BK channel activation may be a potentially important target to design therapeutic strategies in inflammatory airway diseases when ASL volume is decreased.

Controlled delivery of ciprofloxacin and ivacaftor via sinus stent in a preclinical model of Pseudomonas sinusitis

BACKGROUND

Pseudomonas aeruginosa is common in chronic rhinosinusitus (CRS) and frequently resistant to antibiotic treatment. We recently described the ciprofloxacin and ivacaftor-releasing biodegradable sinus stent (CISS)-a drug-delivery system that administers ciprofloxacin and the mucociliary activator (ivacaftor) at high local concentrations with prolonged mucosal contact time and sustained delivery. The objective of this study is to evaluate the efficacy of the CISS in a rabbit model of P aeruginosa (PAO1 strain) sinusitis.

METHODS

Ciprofloxacin/ivacaftor (double layer) was coated on biodegradable poly-D/L-lactic acid (PLLA). A total of 10 sinus stents (5 bare PLLA stent controls, 5 CISSs) were placed unilaterally in rabbit maxillary sinuses via dorsal sinusotomy after inducing infection for 1 week with PAO1. Animals were assessed 3 weeks after stent insertion with sinus culture, nasal endoscopy, computed tomography scan, histopathology, and in-vivo sinus potential difference (SPD) assay.

RESULTS

Rabbits treated with CISS had significant reductions in computed tomography (∆ Kerschner scale: control, 0.55 ± 0.92; CISS, -5.92 ± 1.69; p = 0.024) and endoscopy (control, 4.0 ± 0.0; CISS, 1.875 ± 0.74; p = 0.003) scores. A 2-log reduction of PAO1 was observed (control, -2.14 ± 0.77; CISS, 1.84 ± 1.52; p = 0.047). SPD revealed significantly increased Cl^- transport in the CISS group compared with the control group (Cl^- -free + forskolin ΔPD: control, -4.23 ± 1.04 mV; CISS, -18.36 ± 6.31 mV; p = 0.026). Finally, marked improvements were noted in the histology of the mucosa and submucosa in treated animals.

CONCLUSION

The CISS had robust clinical efficacy in treating P aeruginosa rabbit sinusitis. The innovative design of double-layered drug coating on the surface of the biodegradable stent may provide therapeutic advantages over current treatment strategies for P aeruginosa sinusitis.

Functional Anatomic Imaging of the Airway Surface

The airway surface functional microanatomy, including the ciliated airway epithelium and overlying mucus layer, is a critical component of the mucociliary escalator apparatus, an innate immune defense that helps to maintain a clean environment in the respiratory tract. Many genetic and acquired respiratory diseases have underlying pathophysiological mechanisms in which constituents of the airway surface functional microanatomy are defective. For example, in cystic fibrosis, mutations in the cystic fibrosis transmembrane conductance regulator gene, which normally produces a secretory anion channel protein, result in defective anion secretion and consequent dehydrated and acidic mucosal layer overlying the airway epithelium. This thick, viscous mucus results in depressed ciliary beating and delayed mucociliary transport, trapping bacteria and other pathogens, compromising host defenses and ultimately propagating disease progression. Thus, developing tools capable of studying the airway surface microanatomy has been critical to better understanding key pathophysiological mechanisms, and may become useful tools to monitor treatment outcomes. Here, we discuss functional imaging tools to study the airway surface functional microanatomy, and how their application has contributed to an improved understanding of airway disease pathophysiology.

Prevalence of chronic rhinosinusitis in bronchiectasis patients suspected of ciliary dyskinesia

BACKGROUND

Mucociliary clearance is a main defense mechanism of the airway and is impaired in ciliary dyskinesia. The objective of this study was to evaluate the prevalence of chronic rhinosinusitis (CRS) and its characteristics in bronchiectasis patients suspected of harboring ciliary dyskinesia.

METHODS

Bronchiectasis patients referred to a rhinology clinic for nasal brush biopsy (NBB) were included in this study. NBB was performed using a curettage technique whereby ciliated epithelial cells were obtained from the surface of the inferior nasal turbinate. Results of transmission electron microscopy findings, primary ciliary dyskinesia (PCD) gene (35 genes) analyses (Invitae), and sinus computed tomography (CT) scans were reviewed.

RESULTS

Twenty-three patients (age, 54 ± 2.9 years) were referred for NBB between 2015 and 2018. Thirteen patients (56.5%) met the criteria for diagnosis of CRS. Nineteen patients had ciliary ultrastructural defects. The most common finding was compound cilia (n = 11, 47.8%). Five patients (21.7%) had central microtubule defects (CMD) with higher forced expiratory volume in 1 second (FEV₁ ) at the time of referral than those without CMD (CMD⁺ , 91 ± 3.7%; CMD^- , 73.5 ± 5.7%; p = 0.023). Of 15 subjects with a PCD gene panel, 67% (9 of 15) carried at least 1 gene associated with PCD. Only 1 patient reached diagnosis of PCD. Approximately 50% of non-PCD carriers had a smoking history (p < 0.05). Lund-Mackay scores did not significantly differ between PCD and non-PCD carriers (p = 0.72).

CONCLUSION

Nearly half of bronchiectasis patients referred for NBB had concurrent CRS. The presence of ciliary abnormalities was not amplified in bronchiectasis patients with CRS compared to those without CRS. Extrinsic factors may be related to ciliary structural abnormalities in non-PCD gene carriers.

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.

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.

Sinus Microanatomy and Microbiota in a Rabbit Model of Rhinosinusitis

Background: Rabbits are useful for preclinical studies of sinusitis because of similar physiologic features to humans. The objective of this study is to develop a rabbit model of sinusitis that permits assessment of microanatomy and sampling for evaluating shifts in the sinus microbiota during the development of sinusitis and to test how the mucociliary clearance (MCC) defect might lead to dysbiosis and chronic rhinosinusitis (CRS).

Methods: Generation of CRS was accomplished with an insertion of a sterile sponge into the left middle meatus of New Zealand white rabbits (n = 9) for 2 weeks. After sponge removal, 4 rabbits were observed for another 10 weeks and evaluated for CRS using endoscopy, microCT, visualization of the functional micro-anatomy by micro-optical coherence tomography (μOCT), and histopathological analysis of the sinus mucosa. Samples were taken from the left middle meatus and submitted for microbiome analysis.

Results: CT demonstrated opacification of all left sinuses at 2 weeks in all rabbits (n = 9), which persisted in animals followed for another 12 weeks (n = 4). Histology at week 2 showed mostly neutrophils. On week 14, significant infiltration of plasma cells and lymphocytes was noted with increased submucosal glands compared to controls (p = 0.02). Functional microanatomy at 2 weeks showed diminished periciliary layer (PCL) depth (p < 0.0001) and mucus transport (p = 0.0044) compared to controls despite a thick mucus layer. By 12 weeks, the thickened mucus layer was resolved but PCL depletion persisted in addition to decreased ciliary beat frequency (CBF; p < 0.0001). The mucin fermenting microbes (Lactobacillales, Bacteroidales) dominated on week 2 and there was a significant shift to potential pathogens (e.g., Pseudomonas, Burkholderia) by week 14 compared to both controls and the acute phase (p < 0.05).

Conclusion: We anticipate this reproducible model will provide a means for identifying underlying mechanisms of airway-surface liquid (ASL) depletion and fundamental changes in sinus microbial communities that contribute to the development of CRS. The rabbit model of sinusitis exhibited diminished PCL depth with delayed mucus transport and significant alterations and shift in the sinus microbiome during the development of chronic inflammation.

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.

Frequency-constrained robust principal component analysis: a sparse representation approach to segmentation of dynamic features in optical coherence tomography imaging

Sparse representation theory is an exciting area of research with recent applications in medical imaging and detection, segmentation, and quantitative analysis of biological processes. We present a variant on the robust-principal component analysis (RPCA) algorithm, called frequency constrained RPCA (FC-RPCA), for selectively segmenting dynamic phenomena that exhibit spectra within a user-defined range of frequencies. The algorithm lacks subjective parameter tuning and demonstrates robust segmentation in datasets containing multiple motion sources and high amplitude noise. When tested on 17 ex-vivo, time lapse optical coherence tomography (OCT) B-scans of human ciliated epithelium, segmentation accuracies ranged between 91-99% and consistently out-performed traditional RPCA.