Swimming short fibrous nasal drops achieving intraventricular administration.

Adequate drug delivery across the blood-brain barrier (BBB) is a critical factor in treating central nervous system (CNS) disorders. Inspired by swimming fish and the microstructure of the nasal cavity, this study is the first to develop swimming short fibrous nasal drops that can directly target the nasal mucosa and swim in the nasal cavity, which can effectively deliver drugs to the brain. Briefly, swimming short fibrous nasal drops with charged controlled drug release were fabricated by electrospinning, homogenization, the π-π conjugation between indole group of fibers, the benzene ring of leucine-rich repeat kinase 2 (LRRK2) inhibitor along with charge-dipole interaction between positively charged poly-lysine (PLL) and negatively charged surface of fibers; this enabled these fibers to stick to nasal mucosa, prolonged the residence time on mucosa, and prevented rapid mucociliary clearance. In vitro, swimming short fibrous nasal drops were biocompatible and inhibited microglial activation by releasing an LRRK2 inhibitor. In vivo, luciferase-labelled swimming short fibrous nasal drops delivered an LRRK2 inhibitor to the brain through the nasal mucosa, alleviating cognitive dysfunction caused by sepsis-associated encephalopathy by inhibiting microglial inflammation and improving synaptic plasticity. Thus, swimming short fibrous nasal drops is a promising strategy for the treatment of CNS diseases.

Effect of lumacaftor-ivacaftor on mucociliary clearance and clinical outcomes in cystic fibrosis: Results from the PROSPECT MCC sub-study.

CFTR function is required for normal mucociliary clearance (MCC) and cough-assisted clearance (CC). Lumacaftor-ivacaftor is approved for use in people with cystic fibrosis (CF) carrying two copies of F508del-CFTR. In this observational study performed at four study sites, we characterized the effect of lumacaftor-ivacaftor on mucociliary and cough clearance and related this to other clinical and research endpoints after one month of treatment. Twenty-five adolescents and adults were enrolled. No effect on whole lung MCC was observed, but CC was significantly increased. Sweat chloride improved by 18 mEq/L in this group, indicating a modest restoration of CFTR activity, but no demonstrable change in FEV1 or lung clearance index was observed. We speculate that the modest effect of lumacaftor-ivacaftor on CFTR function was insufficient to yield an improvement in MCC.

The relationship between Covid-19 and mucociliary clearance.

BACKGROUND: The effect of Covid-19 infection on nasal mucociliary clearance (MCC) is unknown. AIMS/OBJECTIVES: The aim of this study is to investigate the relationship between Covid-19 and nasal MCC in terms of smoking, Covid-19 symptoms and treatment. METHODS: Thirty-six patients who were hospitalized in the pandemic ward due to Covid-19 and 36 volunteers (Covid-19 negative test result) who presented to the otolaryngology outpatient clinic with non-nasal symptoms were included in this study. The Saccharin test was performed in both groups to evaluate nasal MCC. RESULTS: The patients and control groups were not significantly different in terms of age and gender. The nasal MCC time was significantly higher in the patient group compared to the control group (19.18 ± 10.84 min and 13.78 ± 8.18 min, p = .003). CONCLUSIONS AND SIGNIFICANCE: In this study, we found that Covid-19 prolonged nasal MCC time regardless of age. We suggest that corticosteroids should be included in the treatment of Covid-19, both with its symptom reduction and its positive effect on MCC duration.

Combined agonists act synergistically to increase mucociliary clearance in a cystic fibrosis airway model.

Mucus clearance, a primary innate defense mechanism of airways, is defective in patients with cystic fibrosis (CF) and CF animals. In previous work, the combination of a low dose of the cholinergic agonist, carbachol with forskolin or a ß adrenergic agonist, isoproterenol synergistically increased mucociliary clearance velocity (MCCV) in ferret tracheas. Importantly, the present study shows that synergistic MCCV can also be produced in CF ferrets, with increases ~ 55% of WT. Synergistic MCCV was also produced in pigs. The combined agonists increased MCCV by increasing surface fluid via multiple mechanisms: increased fluid secretion from submucosal glands, increased anion secretion across surface epithelia and decreased Na+ absorption. To avoid bronchoconstriction, the cAMP agonist was applied 30 min before carbachol. This approach to increasing mucus clearance warrants testing for safety and efficacy in humans as a potential therapeutic for muco-obstructive diseases.

Ivacaftor partially corrects airway inflammation in a humanized G551D rat.

Animal models have been highly informative for understanding the pathogenesis and progression of cystic fibrosis (CF) lung disease. In particular, the CF rat models recently developed have addressed mechanistic causes of the airway mucus defect characteristic of CF, and how these may change when cystic fibrosis transmembrane conductance regulator (CFTR) activity is restored using new modulator therapies. We hypothesized that inflammatory changes to the airway would develop spontaneously and progressively, and that these changes would be resolved with modulator therapy. To test this, we used a humanized-CFTR rat expressing the G551D variant that responds to the CFTR modulator ivacaftor. Markers typically found in the CF lung were assessed, including neutrophil influx, small airway histopathology, and inflammatory cytokine concentration. Young hG551D rats did not express inflammatory cytokines at baseline but did upregulate these in response to inflammatory trigger. As the hG551D rats aged, histopathology worsened, accompanied by neutrophil influx into the airway and increasing concentrations of TNF-α, IL-1α, and IL-6 in the airways. Ivacaftor administration reduced concentrations of these cytokines when administered to the rats at baseline but was less effective in the rats that had also received inflammatory stimulus. Therefore, we conclude that administration of ivacaftor resulted in an incomplete resolution of inflammation when rats received an external trigger, suggesting that CFTR activation may not be enough to resolve inflammation in the lungs of patients with CF.

Effect of adjunctive sodium hyaluronate versus surfactant nasal irrigation on mucociliary clearance in allergic rhinitis: a single-blind, randomised, controlled study.

OBJECTIVE: To investigate the effects of nasal irrigation with sodium hyaluronate and surfactant solutions on mucociliary clearance time in patients with mild persistent allergic rhinitis. METHODS: A total of 120 patients diagnosed with mild persistent allergic rhinitis were enrolled in this prospective study. The patients were allocated randomly to the surfactant, sodium hyaluronate or isotonic saline (as a control) nasal irrigation group. The mucociliary clearance times and improvements in mucociliary clearance times were compared. RESULTS: Improvements in mean mucociliary clearance time were significantly greater in the surfactant and sodium hyaluronate groups than in the control group (p < 0.01). The mean post-treatment mucociliary clearance time of the surfactant group was significantly lower than that of the control (p < 0.001) and sodium hyaluronate groups (p = 0.03). CONCLUSION: Surfactant and sodium hyaluronate nasal irrigation solutions may both be used as adjunctive treatments for allergic rhinitis. Surfactant nasal irrigation resulted in better mucociliary clearance times.

Differential effect of anesthetics on mucociliary clearance in vivo in mice.

Respiratory mucociliary clearance (MCC) is a key defense mechanism that functions to entrap and transport inhaled pollutants, particulates, and pathogens away from the lungs. Previous work has identified a number of anesthetics to have cilia depressive effects in vitro. Wild-type C57BL/6 J mice received intra-tracheal installation of 99mTc-Sulfur colloid, and were imaged using a dual-modality SPECT/CT system at 0 and 6 h to measure baseline MCC (n = 8). Mice were challenged for one hour with inhalational 1.5% isoflurane, or intraperitoneal ketamine (100 mg/kg)/xylazine (20 mg/kg), ketamine (0.5 mg/kg)/dexmedetomidine (50 mg/kg), fentanyl (0.2 mg/kg)/1.5% isoflurane, propofol (120 mg/Kg), or fentanyl/midazolam/dexmedetomidine (0.025 mg/kg/2.5 mg/kg/0.25 mg/kg) prior to MCC assessment. The baseline MCC was 6.4%, and was significantly reduced to 3.7% (p = 0.04) and 3.0% (p = 0.01) by ketamine/xylazine and ketamine/dexmedetomidine challenge respectively. Importantly, combinations of drugs containing fentanyl, and propofol in isolation did not significantly depress MCC. Although no change in cilia length or percent ciliation was expected, we tried to correlate ex-vivo tracheal cilia ciliary beat frequency and cilia-generated flow velocities with MCC and found no correlation. Our results indicate that anesthetics containing ketamine (ketamine/xylazine and ketamine/dexmedetomidine) significantly depress MCC, while combinations containing fentanyl (fentanyl/isoflurane, fentanyl/midazolam/dexmedetomidine) and propofol do not. Our method for assessing MCC is reproducible and has utility for studying the effects of other drug combinations.

Prediction of nasal spray drug absorption influenced by mucociliary clearance.

Evaluation of nasal spray drug absorption has been challenging because deposited particles are consistently transported away by mucociliary clearance during diffusing through the mucus layer. This study developed a novel approach combining Computational Fluid Dynamics (CFD) techniques with a 1-D mucus diffusion model to better predict nasal spray drug absorption. This integrated CFD-diffusion approach comprised a preliminary simulation of nasal airflow, spray particle injection, followed by analysis of mucociliary clearance and drug solute diffusion through the mucus layer. The spray particle deposition distribution was validated experimentally and numerically, and the mucus velocity field was validated by comparing with previous studies. Total and regional drug absorption for solute radius in the range of 1 - 110nm were investigated. The total drug absorption contributed by the spray particle deposition was calculated. The absorption contribution from particles that deposited on the anterior region was found to increase significantly as the solute radius became larger (diffusion became slower). This was because the particles were consistently moved out of the anterior region, and the delayed absorption ensured more solute to be absorbed by the posterior regions covered with respiratory epithelium. Future improvements in the spray drug absorption model were discussed. The results of this study are aimed at working towards a CFD-based integrated model for evaluating nasal spray bioequivalence.

Role of α-Tocopherol Acetate on Nasal Respiratory Functions: Mucociliary Clearance and Rhinomanometric Evaluations in Primary Atrophic Rhinitis.

Primary atrophic rhinitis is a disease of the nose and of paranasalsinuses characterized by a progressive loss of function of nasal and paranasal mucosa caused by a gradual destruction of ciliary mucosalepithelium with atrophy of serous-mucous glands and loss of bonestructures.The aim of this study was to evaluate the therapeutic effects of topic α-tochopherol acetate (vitamin E) in patients with primary atrophicrhinitis based on subjective and objective data.We analyzed 44 patients with dry nose sensation and endoscopic evidence of atrophic nasal mucosa. We analyzed endoscopic mucosascore, anterior rhinomanometry, and nasal mucociliary clearance before and after 6 months of topic treatment with α-tochopherol acetate. For statistical analysis, we used paired samples t test (95% confidence interval [CI], P < .05) for rhinomanometric and muciliary transit time evaluations and analysis of variance 1-way test (95% CI, P < .05) for endoscopic evaluation. All patients showed an improvement in "dry nose" sensation and inperception of nasal airflow. Rhinomanometric examination showed increase of nasal airflow at follow-up (P < .05); nasal mucociliaryclearance showed a reduction in mean transit time (P < .05); and endoscopic evaluation showed significative improvement of hydration of nasalmucosa and significative decreasing nasal crusts and mucusaccumulation (P < .05). Medical treatment for primary atrophic rhinitis is not clearly documented in the literature; in this research, it was demonstrated that α-ochopherol acetate could be a possible treatment for atrophic rhinitis.

Evaluation of Nasal Mucociliary Clearance, Nasal Obstruction Symptom Evaluation, and Epistaxis Severity Score in Isotretinoin Treatment.

OBJECTIVES: The study aims to investigate the possible side effects of isotretinoin use on the nasal mucosa with objective methods in the treatment of acne vulgaris. METHODS: Before the treatment, nasal mucociliary clearance time (MCT) was measured in all patients. Also all patients were asked to complete the questionnaires about the nasal dryness (visual analog scale [VAS]), nasal obstruction (Nasal Obstruction Symptom Evaluation [NOSE]), and presence of epistaxis (Epistaxis Severity Score [ESS]). Both MCT and questionnaires were reevaluated in patients who completed the treatment. RESULTS: The results of 101 patients were evaluated. Before treatment, mean duration of nasal mucociliary clearance (NMC) was 9.55 ± 1.30 minutes, nasal dryness (VAS) value was 2.7 ± 0.7, NOSE score was 2.1 ± 1.1, and ESS score was 1.2 ± 0.7; after treatment, the duration of NMC was 13.80 ± 2.29 minutes, VAS value was 3.3 ± 1.1, NOSE score was 3.2 ± 1.3, and ESS score was 2.1 ± 1.2 (P = .018, .150, .027, .011, respectively). CONCLUSION: The nasal mucosa is adversely affected in patients due to regular use of isotretinoin in the acne treatment, anamnesis should be checked in all nasal surgeries, and routine ear nose throat control should be recommended for these patients.

The effect of chemotherapy on olfactory function and mucociliary clearance.

OBJECTIVES: Olfactory sensory neurons and the olfactory mucosa are both important for optimal olfactory function. The potential nasal mucosal toxicity of chemotherapy regimens has not been assessed yet. The aim of this study was to objectively investigate the effect of chemotherapy on mucociliary clearance and olfactory function and to evaluate whether this effect differs between different chemotherapy regimens and age groups. PATIENTS AND METHODS: The study included consecutive patients admitted for the treatment of a variety of primary tumors (except head and neck and brain malignancies). Patients were evaluated for olfaction and mucociliary clearance before and immediately after completing the last session of chemotherapy cycles, according to the therapeutic protocol. For objective evaluation, the saccharine test was used for mucociliary clearance and the Sniffin' Sticks test for olfactory function. Of the 46 initial patients, 30 completed the study. Groups were formed according to the chemotherapy regimen (four groups: CA (doxorubicin + cyclophosphamide), Folfox (oxaliplatin +5-FU + folinic acid), DCF (docetaxel + cisplatin +5-FU), and GC (gemcitabine + cisplatin)) and according to age (two groups: < 55 years and > 55 years). RESULTS: In the overall analyses, significant deterioration was noted in both mucociliary clearance time and smell scores (olfactory threshold (OT), olfactory discrimination (OD), olfactory identification (OI), and the composite threshold-discrimination-identification (TDI) score). The changes in these scores showed no significant differences between chemotherapy groups. The decrease in OT and global TDI scores was more severe in the younger age group. CONCLUSIONS: Chemotherapy impairs both the mucociliary clearance and olfactory function in cancer patients. This might reflect the collective negative effect of chemotherapy on olfactory function, not only through the neurocytotoxic effect but also the cytotoxic effect on the nasal mucosa. In addition, the reduction in olfactory threshold and total olfactory function scores was seen to be more profound in younger patients, which could have been due to higher initial scores.

Compartment-specific transcriptomics of ozone-exposed murine lungs reveals sex- and cell type-associated perturbations relevant to mucoinflammatory lung diseases.

Ozone is known to cause lung injury, and resident cells of the respiratory tract (i.e., epithelial cells and macrophages) respond to inhaled ozone in a variety of ways that affect their survival, morphology, and functioning. However, a complete understanding of the sex-associated and the cell type-specific gene expression changes in response to ozone exposure is still limited. Through transcriptome profiling, we aimed to analyze gene expression alterations and associated enrichment of biological pathways in three distinct cell type-enriched compartments of ozone-exposed murine lungs. We subchronically exposed adult male and female mice to 0.8 ppm ozone or filtered air. RNA-Seq was performed on airway epithelium-enriched airways, parenchyma, and purified airspace macrophages. Differential gene expression and biological pathway analyses were performed and supported by cellular and immunohistochemical analyses. While a majority of differentially expressed genes (DEGs) in ozone-exposed versus air-exposed groups were common between both sexes, sex-specific DEGs were also identified in all of the three tissue compartments. As compared with ozone-exposed males, ozone-exposed females had significant alterations in gene expression in three compartments. Pathways relevant to cell division and DNA repair were enriched in the ozone-exposed airways, indicating ozone-induced airway injury and repair, which was further supported by immunohistochemical analyses. In addition to cell division and DNA repair pathways, inflammatory pathways were also enriched within the parenchyma, supporting contribution by both epithelial and immune cells. Further, immune response and cytokine-cytokine receptor interactions were enriched in macrophages, indicating ozone-induced macrophage activation. Finally, our analyses also revealed the overall upregulation of mucoinflammation- and mucous cell metaplasia-associated pathways following ozone exposure.

Purinergic receptors in airway hydration.

Airway epithelial purinergic receptors control key components of the mucociliary clearance (MCC), the dominant component of pulmonary host defense. In healthy airways, the periciliary liquid (PCL) is optimally hydrated, thus acting as an efficient lubricant layer over which the mucus layer moves by ciliary force. When the hydration of the airway surface decreases, the mucus becomes hyperconcentrated, the PCL collapses, and the "thickened" mucus layer adheres to cell surfaces, causing plaque/plug formation. Mucus accumulation is a major contributing factor to the progression of chronic obstructive lung diseases such as cystic fibrosis (CF) and chronic bronchitis (CB). Mucus hydration is regulated by finely tuned mechanisms of luminal Cl- secretion and Na+ absorption with concomitant osmotically driven water flow. These activities are regulated by airway surface liquid (ASL) concentrations of adenosine and ATP, acting on airway epithelial A2B and P2Y2 receptors, respectively. The goal of this article is to provide an overview of our understanding of the role of purinergic receptors in the regulation of airway epithelial ion/fluid transport and the mechanisms of nucleotide release and metabolic activities that contribute to airway surface hydration in healthy and chronically obstructed airways.

Airway cholinergic history modifies mucus secretion properties to subsequent cholinergic challenge in diminished chloride and bicarbonate conditions.

NEW FINDINGS: What is the central question of this study? What is the impact of airway cholinergic history on the properties of airway mucus secretion in a cystic fibrosis-like environment? What is the main finding and its importance? Prior cholinergic challenge slightly modifies the characteristics of mucus secretion in response to a second cholinergic challenge in a diminished bicarbonate and chloride transport environment. Such modifications might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease. ABSTRACT: Viral infections precipitate exacerbations in many airway diseases, including asthma and cystic fibrosis. Although viral infections increase cholinergic transmission, few studies have examined how cholinergic history modifies subsequent cholinergic responses in the airway. In our previous work, we found that airway resistance in response to a second cholinergic challenge was increased in young pigs with a history of airway cholinergic stimulation. Given that mucus secretion is regulated by the cholinergic nervous system and that abnormal airway mucus contributes to exacerbations of airway disease, we hypothesized that prior cholinergic challenge would also modify subsequent mucus responses to a secondary cholinergic challenge. Using our established cholinergic challenge-rechallenge model in pigs, we atomized the cholinergic agonist bethanechol or saline control to pig airways. Forty-eight hours later, we removed tracheas and measured mucus secretion properties in response to a second cholinergic stimulation. The second cholinergic stimulation was conducted in conditions of diminished chloride and bicarbonate transport to mimic a cystic fibrosis-like environment. In pigs previously challenged with bethanechol, a second cholinergic stimulation produced a mild increase in sheet-like mucus films; these films were scarcely observed in animals originally challenged with saline control. The subtle increase in mucus films was not associated with changes in mucociliary transport. These data suggest that prior cholinergic history might modify mucus secretion characteristics with subsequent stimulation in certain environmental conditions or disease states. Such modifications and/or more repetitive stimulation might lead to retention of mucus on the airway surface, thereby potentiating exacerbations of airway disease.

Lack of Kcnn4 improves mucociliary clearance in muco-obstructive lung disease.

Airway mucociliary clearance (MCC) is the main mechanism of lung defense keeping airways free of infection and mucus obstruction. Airway surface liquid volume, ciliary beating, and mucus are central for proper MCC and critically regulated by sodium absorption and anion secretion. Impaired MCC is a key feature of muco-obstructive diseases. The calcium-activated potassium channel KCa.3.1, encoded by Kcnn4, participates in ion secretion, and studies showed that its activation increases Na+ absorption in airway epithelia, suggesting that KCa3.1-induced hyperpolarization was sufficient to drive Na+ absorption. However, its role in airway epithelium is not fully understood. We aimed to elucidate the role of KCa3.1 in MCC using a genetically engineered mouse. KCa3.1 inhibition reduced Na+ absorption in mouse and human airway epithelium. Furthermore, the genetic deletion of Kcnn4 enhanced cilia beating frequency and MCC ex vivo and in vivo. Kcnn4 silencing in the Scnn1b-transgenic mouse (Scnn1btg/+), a model of muco-obstructive lung disease triggered by increased epithelial Na+ absorption, improved MCC, reduced Na+ absorption, and did not change the amount of mucus but did reduce mucus adhesion, neutrophil infiltration, and emphysema. Our data support that KCa3.1 inhibition attenuated muco-obstructive disease in the Scnn1btg/+ mice. K+ channel modulation may be a therapeutic strategy to treat muco-obstructive lung diseases.

A four week trial of hypertonic saline in children with mild cystic fibrosis lung disease: Effect on mucociliary clearance and clinical outcomes.

BACKGROUND: Hypertonic saline (HS) is commonly prescribed for children with cystic fibrosis (CF) despite the absence of strong data indicating clinical efficacy in a population with mild lung disease. We hypothesized that HS treatment would result in a sustained improvement in mucociliary clearance (MCC) in children with CF who had minimal lung disease, thus providing evidence for a biologically relevant effect that also may be associated with clinical improvements. METHODS: We performed a randomized, placebo controlled, double blind study of 6% versus 0.12% sodium chloride, delivered three-times daily with an eFlow nebulizer for 4 weeks. MCC was measured using gamma scintigraphy at baseline, 2-hours after the first study treatment, and ~12-hours after the final dose (at day 28). Spirometry, respiratory symptoms (CFQ-R), and safety were also assessed. RESULTS: Study treatments were generally well tolerated and safe. HS (6% sodium chloride) resulted in a significant, sustained improvement from baseline in whole lung clearance after 4 weeks of therapy (p = 0.014), despite absence of a prolonged single-dose effect after the initial dose. This sustained change (12 hrs after prior dose) was significantly greater when compared to placebo (0.12% sodium chloride) treatment (p = 0.016). Improvements in spirometry with HS did not reach statistical significance but correlated with MCC changes. CONCLUSIONS: The observed sustained improvement in MCC with HS suggests that this treatment may yield health benefits, even in relatively mildly affected children with CF. Highlighting this physiologic finding is important due to the lack of meaningful, validated endpoints in this population.

Influence of silica particles on mucociliary structure and MUC5B expression in airways of C57BL/6 mice.

Purpose: Impaired mucociliary clearance is an initial characteristic of recurrent cough, respiratory infection and chronic respiratory diseases. It has been demonstrated that prolonged inhalation of respirable silica particles results in a variety of pulmonary diseases, but whether the mucociliary system is involved in this process is unclear. This study aims to evaluate the effects of silica particles on mucociliary structure and MUC5B production in respiratory tract.Materials and Methods: C57BL/6 mice were administered with 2.5 mg silica particles through a single intratracheal instillation. The changes of mucociliary structure and MUC5B expression in trachea was evaluated by HE and AB-PAS staining, transmission electron microscopy and immunohistochemistry on days 1, 7, 28 and 84 post-exposure.Results: The mucociliary structure of airway epithelium was obviously impaired by silica particles, showing disordered, shortened or partially lost cilia on the surface, increased mucus in mucous layer and submucosal glands from day 7 to day 84. A variety of ultrastructural abnormalities were discovered in silica-exposed airway cilia, including absence of central pair microtubules, disorganized microtubules and clusters of axoneme on day 1 and 7. The numbers of ciliary axonemes and basal bodies in ciliated epithelial cells were significantly decreased, whereas the proportion of abnormal axonemes was gradually increased with exposure to silica particles (P < 0.05). In addition, silica particles significantly decreased MUC5B expression on the surface of airway epithelium on day 28 and 84, but obviously increased its production in submucosal glands from day 1 to day 84 (P < 0.01).Conclusions: Silica particles could lead to ultrastructural defects in airway cilia, mucus hypersecretion and altered MUC5B expression in trachea, indicating that impaired mucociliary structure and altered MUC5B production might participate in the development of silica-related respiratory diseases.

Novel Therapy of Bicarbonate, Glutathione, and Ascorbic Acid Improves Cystic Fibrosis Mucus Transport.

Defective airway mucus clearance is a defining characteristic of cystic fibrosis lung disease, and improvements to current mucolytic strategies are needed. Novel approaches targeting a range of contributing mechanisms are in various stages of preclinical and clinical development. ARINA-1 is a new nebulized product comprised of ascorbic acid, glutathione, and bicarbonate. Using microoptical coherence tomography, we tested the effect of ARINA-1 on central features of mucociliary clearance in F508del/F508del primary human bronchial epithelial cells to assess its potential as a mucoactive therapy in cystic fibrosis. We found that ARINA-1 significantly augmented mucociliary transport rates, both alone and with CFTR (cystic fibrosis transmembrane conductance regulator) modulator therapy, whereas airway hydration and ciliary beating were largely unchanged compared with PBS vehicle control. Analysis of mucus reflectivity and particle-tracking microrheology indicated that ARINA-1 restores mucus clearance by principally reducing mucus layer viscosity. The combination of bicarbonate and glutathione elicited increases in mucociliary transport rate comparable to those seen with ARINA-1, indicating the importance of this interaction to the impact of ARINA-1 on mucus transport; this effect was not recapitulated with bicarbonate alone or bicarbonate combined with ascorbic acid. Assessment of CFTR chloride transport revealed an increase in CFTR-mediated chloride secretion in response to ARINA-1 in CFBE41o- cells expressing wild-type CFTR, driven by CFTR activity stimulation by ascorbate. This response was absent in CFBE41o- F508del cells treated with VX-809 and primary human bronchial epithelial cells, implicating CFTR-independent mechanisms for the effect of ARINA-1 on cystic fibrosis mucus. Together, these studies indicate that ARINA-1 is a novel potential therapy for the treatment of impaired mucus clearance in cystic fibrosis.

Acid exposure disrupts mucus secretion and impairs mucociliary transport in neonatal piglet airways.

Tenacious mucus produced by tracheal and bronchial submucosal glands is a defining feature of several airway diseases, including cystic fibrosis (CF). Airway acidification as a driving force of CF airway pathology has been controversial. Here we tested the hypothesis that transient airway acidification produces pathologic mucus and impairs mucociliary transport. We studied pigs challenged with intra-airway acid. Acid had a minimal effect on mucus properties under basal conditions. However, cholinergic stimulation in acid-challenged pigs revealed retention of mucin 5B (MUC5B) in the submucosal glands, decreased concentrations of MUC5B in the lung lavage fluid, and airway obstruction. To more closely mimic a CF-like environment, we also examined mucus secretion and transport following cholinergic stimulation under diminished bicarbonate and chloride transport conditions ex vivo. Under these conditions, airways from acid-challenged pigs displayed extensive mucus films and decreased mucociliary transport. Pretreatment with diminazene aceturate, a small molecule with ability to inhibit acid detection through blockade of the acid-sensing ion channel (ASIC) at the doses provided, did not prevent acid-induced pathologic mucus or transport defects but did mitigate airway obstruction. These findings suggest that transient airway acidification early in life has significant impacts on mucus secretion and transport properties. Furthermore, they highlight diminazene aceturate as an agent that might be beneficial in alleviating airway obstruction.

The effects of sildenafil on ciliary beat frequency in patients with pulmonary non-tuberculous mycobacteria disease: phase I/II trial.

RATIONALE: Pulmonary non-tuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Abnormal mucociliary clearance and abnormal nasal nitric oxide (nNO) have been associated with PNTM disease in other patient cohorts. Mucociliary clearance can be affected by NO-cyclic guanosine monophosphate signalling and, therefore, modulation of the pathway may be possible with phosphodiesterase inhibitors such as sildenafil as a novel therapeutic approach. OBJECTIVE: To define ex vivo characteristics of PNTM disease affected by sildenafil. METHODS: Subjects with PNTM infections were recruited into an open-label dose-escalation trial of sildenafil. Laboratory measurements and mucociliary measurements-ciliary beat frequency, nNO and 24-hour sputum production-were collected throughout the study period. Patients received sildenafil daily during the study period, with escalation from 20 to 40 mg three times per day. MEASUREMENTS AND MAIN RESULTS: Increased ciliary beat frequency occurred after a single dose of 40 mg sildenafil and after extended dosing of 40 mg sildenafil. The increase ciliary beat frequency was not seen with 20 mg sildenafil dosing. There were no changes in sputum production, nNO production, Quality of Life-Bronchiectasis-NTM module (QOL-B-NTM) questionnaire or the St George's Respiratory Questionnaire during the study period. CONCLUSION: Sildenafil, 40 mg, increased ciliary beat frequency acutely as well as with extended administration.