Role In Mucociliary Clearance Research Articles

Effect of Uneven Microclimates in Poultry Yards on the Respiratory System of Poultry

The respiratory system of birds is maximally adapted to the high efficiency of air exchange necessary to maintain an increased level of metabolic processes. The mucus of the respiratory tract plays an important role in mucociliary clearance, in the normal state of the respiratory system, without allergic and inflammatory reactions, an increase in the amount of mucus and the structures that produce it can be interpreted as a positive fact, but too much mucus can be a response to mucosal irritation and contributes to airway obstruction. As a result of two studies repeating each other, the dependence of the state of the tracheal wall in Ross-308 cross broilers on air circulation in industrial premises was confirmed. Ensuring the circulation of air flows in poultry rearing halls has a positive effect on the histological and histochemical structure of the trachea. In the first experiment, this is reliably evidenced by an increase in the thickness of the epithelial layer by 1.3 times (by 23.3%) and the height of the cilia by 3.1 times (by 67.5%). In the second experiment, this is confirmed by an increase in the height of the epithelium by 40% and the height of the cilia layer by 70%. In addition, the histological picture of the mucosa corresponds to the norm, there are no violations of the integrity of the epithelium, the cilia are smooth, without deformations and creases. With the provision of air circulation in closed rooms in the first experiment, the thickness of the tracheal mucosa decreases by 2.6 times (by 61.9%), and its own plate by 2.9 times (by 65.4%). In the second experiment, no such pattern was found in the own plate, but destructive changes in the tracheal mucosa, an increase in the number of glycoproteins and proteoglycans in the experimental groups confirm the influence of the ventilation factor.

MUC5B Mutation Causes Mucociliary Dysfunction and Primary Ciliary Dyskinesia Like Illness in a Saudi Girl: A Case Report

1.1. Background: MUC5B is a major gel forming mucin in the lung that plays a key role in mucociliary clearance and host defense that is secreted from proximal submucosal glands and distal airway secretory cells. The MUC5B promoter variant is associated with enhanced expression of the MUC5B transcript in lung tissue from unaffected subjects and patients with idiopathic pulmonary fibrosis (IPF). In patients with IPF, excess MUC5B protein is especially observed in epithelial cells in the respiratory bronchiole and honeycomb cysts, regions of lung involved in lung fibrosis. However, it remains unclear how MUC5B leads to the development of IPF in adult. In mice, MUC5B is required for mucociliary clearance and for controlling inflammation after microbial exposure. The consequences of its loss in humans are unclear, however MUC5B homozygous variant has recently been reported in two affected siblings.

Serratiopeptidase, A Serine Protease Anti-Inflammatory, Fibrinolytic, and Mucolytic Drug, Can Be a Useful Adjuvant for Management in COVID-19.

Serratiopeptidase, A Serine Protease Anti-Inflammatory, Fibrinolytic, and Mucolytic Drug, Can Be a Useful Adjuvant for Management in COVID-19.

Super-Resolution Microscopy and FIB-SEM Imaging Reveal Parental Centriole-Derived, Hybrid Cilium in Mammalian Multiciliated Cells.

Motile cilia are cellular beating machines that play a critical role in mucociliary clearance, cerebrospinal fluid movement, and fertility. In the airways, hundreds of motile cilia present on the surface of a multiciliated epithelia cell beat coordinately to protect the epithelium from bacteria, viruses, and harmful particulates. During multiciliated cell differentiation, motile cilia are templated from basal bodies, each extending a basal foot-an appendage linking motile cilia together to ensure coordinated beating. Here, we demonstrate that among the many motile cilia of a multiciliated cell, a hybrid cilium with structural features of both primary and motile cilia is harbored. The hybrid cilium is conserved in mammalian multiciliated cells, originates from parental centrioles, and its cellular position is biased and dependent on ciliary beating. Furthermore, we show that the hybrid cilium emerges independently of other motile cilia and functions in regulating basal body alignment.

Comparative studies on the histological characteristics of equine nasomaxillary aperture and paranasal sinus mucosa considering topographic and age-related differences

BackgroundHorses may acquire a range of paranasal sinus diseases. Clinical studies show slight differences regarding anatomical regions and age. Histopathological examination of tissue samples could play an important role in the diagnostic process. Therefore, detailed knowledge of the histological appearance of the paranasal sinus mucosa (PSM) and the nasomaxillary aperture mucosa (NAM) is essential. The objective of this study was to determine topographic and age-related differences within the healthy equine PSM. In addition, we aimed to gain detailed knowledge of the histological appearance of the NAM in comparison to the PSM.ResultsThe PSM had an average height of 75.72 ± 44.48 μm with a two-row pseudostratified columnar epithelium of 13.52 ± 4.78 μm. The parameters mucosal height, epithelial height and number of goblet cells revealed significant dependency of the sample site and age group. The maxillary and dorsal conchal sinus showed the highest values for these parameters. In terms of age, younger horses showed a significantly higher total mucosal height in contrast to a significantly lower epithelial height than older horses. Positive correlation was seen between the epithelial height and number of goblet cells. The NAM had an average height of 820.27 ± 653.21 μm. Its pseudostratified epithelium was usually arranged in three rows and had an average height of 44.9 ± 12.78 μm. The number of goblet cells in the NAM was five times higher than in the PSM. Serous glands were found in only 4% of the PSM samples and 100% of the NAM samples.ConclusionsThere are significant histological differences between different paranasal sinus sites and between different groups of age. This may be related to an altered susceptibility for certain pathologies. The striking difference in the histological appearance of the NAM compared to the PSM could be due to an enhanced role in mucociliary clearance. Further studies are necessary to improve the understanding of mucosal function in specific paranasal sinus compartments and mucosal changes generated by different diseases.

Multiscale mechanics of mucociliary clearance in the lung.

Mucociliary clearance (MCC) is one of the most important defence mechanisms of the human respiratory system. Its failure is implicated in many chronic and debilitating airway diseases. However, due to the complexity of lung organization, we currently lack full understanding on the relationship between these regional differences in anatomy and biology and MCC functioning. For example, it is unknown whether the regional variability of airway geometry, cell biology and ciliary mechanics play a functional role in MCC. It therefore remains unclear whether the regional preference seen in some airway diseases could originate from local MCC dysfunction. Though great insights have been gained into the genetic basis of cilia ultrastructural defects in airway ciliopathies, the scaling to regional MCC function and subsequent clinical phenotype remains unpredictable. Understanding the multiscale mechanics of MCC would help elucidate genotype-phenotype relationships and enable better diagnostic tools and treatment options. Here, we review the hierarchical and variable organization of ciliated airway epithelium in human lungs and discuss how this organization relates to MCC function. We then discuss the relevancy of these structure-function relationships to current topics in lung disease research. Finally, we examine how state-of-the-art computational approaches can help address existing open questions. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.

The C-terminal dimerization domain of the respiratory mucin MUC5B functions in mucin stability and intracellular packaging before secretion

Mucin 5B (MUC5B) has an essential role in mucociliary clearance that protects the pulmonary airways. Accordingly, knowledge of MUC5B structure and its interactions with itself and other proteins is critical to better understand airway mucus biology and improve the management of lung diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). The role of an N-terminal multimerization domain in the supramolecular organization of MUC5B has been previously described, but less is known about its C-terminal dimerization domain. Here, using cryogenic electron microscopy (cryo-EM) and small-angle X-ray scattering (SAXS) analyses of recombinant disulfide-linked dimeric MUC5B dimerization domain we identified an asymmetric, elongated twisted structure, with a double globular base. We found that the dimerization domain is more resistant to disruption than the multimerization domain suggesting the twisted structure of the dimerization domain confers additional stability to MUC5B polymers. Size-exclusion chromatography-multiangle light scattering (SEC-MALS), SPR-based biophysical analyses and microscale thermophoresis of the dimerization domain disclosed no further assembly, but did reveal reversible, calcium-dependent interactions between the dimerization and multimerization domains that were most active at acidic pH, suggesting that these domains have a role in MUC5B intragranular organization. In summary, our results suggest a role for the C-terminal dimerization domain of MUC5B in compaction of mucin chains during granular packaging via interactions with the N-terminal multimerization domain. Our findings further suggest that the less stable multimerization domain provides a potential target for mucin depolymerization to remove mucus plugs in COPD and other lung pathologies.

Cigarette whole smoke solutions disturb mucin homeostasis in a human in vitro airway tissue model

Many cigarette smoke-associated airway diseases involve alterations in mucin homeostasis. With the rationale that relevant tissue responses can be measured to evaluate the adverse health effects of tobacco products, we assessed changes in mucin secretion and the density and size of goblet cells in an in vitro human air-liquid-interface (ALI) airway tissue model after exposure to a tobacco smoke solution. Cultures were exposed daily for up to five consecutive days to a whole smoke solution (WSS) prepared by machine smoking Marlboro Red or Marlboro Silver cigarettes using the Canadian Intense (CI) protocol. Both WSSs induced concentration- and time-related hypersecretion of mucins 5AC and 5B, accompanied by up-regulation of the respective mucin genes. Mucin secretion returned to baseline levels following a 14-day recovery period. Mucin-secreting goblet cells exhibited increased cell density and decreased size after 5 daily treatments then recovered to their normal size, but with decreased cell density, 14 days after the last treatment. The beating frequency of ciliated cells, which plays a key role in mucociliary clearance, was increased by 5 daily treatments with the CI WSSs then reverted to baseline levels following a 7-day recovery. Taken together, our results indicate that ALI cultures can be used to measure the modulation of mucin production, secretion, and clearance, disturbances that are manifested in tobacco smoke-related diseases, such as chronic obstructive pulmonary disease. Measuring tissue responses directly relevant to the respiratory toxicity of cigarette smoke may provide useful information in support of science-based regulatory decisions.

Directed Induction of Functional Multi-ciliated Cells in Proximal Airway Epithelial Spheroids from Human Pluripotent Stem Cells.

SummaryMulti-ciliated airway cells (MCACs) play a role in mucociliary clearance of the lung. However, the efficient induction of functional MCACs from human pluripotent stem cells has not yet been reported. Using carboxypeptidase M (CPM) as a surface marker of NKX2-1+-ventralized anterior foregut endoderm cells (VAFECs), we report a three-dimensional differentiation protocol for generating proximal airway epithelial progenitor cell spheroids from CPM+ VAFECs. These spheroids could be induced to generate MCACs and other airway lineage cells without alveolar epithelial cells. Furthermore, the directed induction of MCACs and of pulmonary neuroendocrine lineage cells was promoted by adding DAPT, a Notch pathway inhibitor. The induced MCACs demonstrated motile cilia with a “9 + 2” microtubule arrangement and dynein arms capable of beating and generating flow for mucociliary transport. This method is expected to be useful for future studies on human airway disease modeling and regenerative medicine.

Update in Cystic Fibrosis 2014.

The clinical face of cystic fibrosis (CF) has significantly changed over the 25 years since its basic genetic defect was discovered (1). Increasing numbers of patients are diagnosed at newborn screening, and soon the majority of the CF population will be adult patients (2). With the 2012 approval of the first cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy, ivacaftor, the CF community has been able to experience the clinical and biological impact of this therapeutic approach in a small subset of patients with the G551D mutation (3). The findings are very encouraging and push investigators and clinicians to move forward with the development of additional modulators to improve the health of the majority of patients in the future. As a result, worldwide scientific collaborations have contributed to advances in therapeutics with the eventual goal of early intervention before the onset of symptoms. At the same time, the research community continues to elucidate the fundamental mechanisms of disease. In this article, we highlight some of the important scientific developments of 2014 with a focus on CFTR function and its complex role in mucociliary clearance (MCC), microbiology, and inflammation of the airway. In addition, advances in novel therapeutics and clinical outcomes are reviewed, with discussion of how those advances are impacting the field. CFTR Function and Its Role in MCC

Vinpocetine inhibits Streptococcus pneumoniae-induced upregulation of mucin MUC5AC expression via induction of MKP-1 phosphatase in the pathogenesis of otitis media.

Mucin overproduction is a hallmark of otitis media (OM). Streptococcus pneumoniae is one of the most common bacterial pathogens causing OM. Mucin MUC5AC plays an important role in mucociliary clearance of bacterial pathogens. However, if uncontrolled, excessive mucus contributes significantly to conductive hearing loss. Currently, there is a lack of effective therapeutic agents that suppress mucus overproduction. In this study, we show that a currently existing antistroke drug, vinpocetine, a derivative of the alkaloid vincamine, inhibited S. pneumoniae-induced mucin MUC5AC upregulation in cultured middle ear epithelial cells and in the middle ear of mice. Moreover, vinpocetine inhibited MUC5AC upregulation by inhibiting the MAPK ERK pathway in an MKP-1-dependent manner. Importantly, ototopical administration of vinpocetine postinfection inhibited MUC5AC expression and middle ear inflammation induced by S. pneumoniae and reduced hearing loss and pneumococcal loads in a well-established mouse model of OM. Thus, these studies identified vinpocetine as a potential therapeutic agent for inhibiting mucus production in the pathogenesis of OM.

Infection by Toxoplasma gondii, a severe parasite in neonates and AIDS patients, causes impaired anion secretion in airway epithelia

The airway epithelia initiate and modulate the inflammatory responses to various pathogens. The cystic fibrosis transmembrane conductance regulator-mediated Cl(-) secretion system plays a key role in mucociliary clearance of inhaled pathogens. We have explored the effects of Toxoplasma gondii, an opportunistic intracellular protozoan parasite, on Cl(-) secretion of the mouse tracheal epithelia. In this study, ATP-induced Cl(-) secretion indicated the presence of a biphasic short-circuit current (Isc) response, which was mediated by a Ca(2+)-activated Cl(-) channel (CaCC) and the cystic fibrosis transmembrane conductance regulator. However, the ATP-evoked Cl(-) secretion in T. gondii-infected mouse tracheal epithelia and the elevation of [Ca(2+)]i in T. gondii-infected human airway epithelial cells were suppressed. Quantitative reverse transcription-PCR revealed that the mRNA expression level of the P2Y2 receptor (P2Y2-R) increased significantly in T. gondii-infected mouse tracheal cells. This revealed the influence that pathological changes in P2Y2-R had on the downstream signal, suggesting that P2Y2-R was involved in the mechanism underlying T. gondii infection in airways. These results link T. gondii infection as well as other pathogen infections to Cl(-) secretion, via P2Y2-R, which may provide new insights for the treatment of pneumonia caused by pathogens including T. gondii.

Epinephrine stimulation of anion secretion in the Calu-3 serous cell model

Calu-3 is a well-differentiated human bronchial cell line with the characteristics of the serous cells of airway submucosal glands. The submucosal glands play a major role in mucociliary clearance because they secrete electrolytes that facilitate airway hydration. Given the significance of both long- and short-term β-adrenergic receptor agonists in the treatment of respiratory diseases, it is important to determine the role of these receptors and their ligands in normal physiological function. The present studies were designed to characterize the effect of epinephrine, the naturally occurring β-adrenergic receptor agonist, on electrolyte transport of the airway serous cells. Interestingly, epinephrine stimulated two anion secretory channels, the cystic fibrosis transmembrane conductance regulator and a Ca(2+)-activated Cl(-) channel, with the characteristics of transmembrane protein 16A, thereby potentially altering mucociliary clearance via multiple channels. Consistent with the dual channel activation, epinephrine treatment resulted in increases in both intracellular cAMP and Ca(2+). Furthermore, the present results extend previous reports indicating that the two anion channels are functionally linked.

Intranasal sodium hyaluronate on the nasal cytology of patients with allergic and nonallergic rhinitis

Rhinitis is an extremely common medical problem characterized by nasal congestion, clear rhinorrhea, sneezing, and itching. Hyaluronate is an endogenous compound that has an important role in mucociliary clearance by the epithelial surface of the nasal passages and in mucosal surface healing and repair. The objective of this work was to determine the effects of intranasal administration of sodium hyaluronate on nasal cytology in patients with allergic and nonallergic rhinitis. In a single-center, randomized, blinded trial, 78 patients received intranasal mometasone and oral desloratadine plus either intranasal sodium hyaluronate or saline for 1 month. Nasal cytology was performed and the change from baseline in the numbers of neutrophils, eosinophils, mast cells, lymphocytes, and infective species was determined. Other outcomes included changes in symptoms and the endoscopic appearance of the nasal mucosa, and tolerability. Patients receiving sodium hyaluronate experienced a significant decrease in the median neutrophil count seen on nasal cytology compared with controls (p = 0.001). Sodium hyaluronate was associated with significant improvements in sneezing, rhinorrhea, and nasal congestion, and on exudate seen on endoscopy at 1 month compared with baseline. Intranasal sodium hyaluronate received better tolerability scores than saline over the 1-month treatment period. The addition of sodium hyaluronate to intranasal corticosteroid and systemic antihistamine reduced the neutrophil count seen on nasal cytology in patients with allergic and nonallergic rhinitis and improved several clinical and endoscopic parameters while being well tolerated. These data provide encouraging evidence of the efficacy of sodium hyaluronate in the treatment of this common disease.

Swept under the carpet? The role of mucociliary clearance in ventilator-induced lung injury

Swept under the carpet? The role of mucociliary clearance in ventilator-induced lung injury

Mucus and the mare: How little we know

Uterine infections are a major cause of infertility, but the role of mucus in equine uterine defense is not well understood. Mucociliary currents play an important role in protecting mucous membranes, including the upper and lower respiratory tracts of mammals, and are required for feeding and oxygenation of many aquatic invertebrates. Although phagocytosis has long been considered the first line of uterine defense in the mare, there are concerns about its efficacy in the uterine lumen. Additional local defenses, such as mucociliary currents, have therefore been proposed. The uterine epithelium exhibits alternating mucus-secreting and ciliated cells supporting a mucopolysaccharide blanket, features shared with mucociliary membranes throughout the animal kingdom. Gross uterine anatomy, such as continuity of uterine and cervical folds, may indicate adaptations to mucociliary clearance. In addition, ciliated cells obtained in uterine lavages often display motility. Disruptions of mucociliary clearance play major roles in pathogenesis of mucosal infections in humans, including pneumonia, chronic sinusitis, and otitis media. Establishing drainage is a major goal of therapy in treatment of chronic sinusitis, hastening return of mucociliary function. Similar disruptions may occur in equine uterine infections, associated with accumulations of uterine fluid, loss of endometrial folds, and cervical trauma. Possible clinical implications of mucociliary clearance in the mare are discussed, however the role of mucociliary clearance in the mare remains speculative.

Surfactant and its Role in Chronic Sinusitis

Although numerous studies have focused on the nature and defensive role of surfactant in the lower airways, relatively little is known about its role in the upper airways. Decreased levels of the main component of surfactant--phospholipids--have been implicated in atrophic rhinitis. The lamellar body arrangement of phospholipids has now been demonstrated in both normal and diseased sinus tissue, resulting in the implication that these structures may play a crucial role in mucociliary clearance against inhaled pathogens, as well as in the regulation of mucous viscosity. Furthermore, they may be secreted from sinonasal ciliated epithelium. Surfactant proteins (SPs) make up a relatively smaller proportion of surfactant, but appear to have an important role in innate immunity. Altered levels of SPs have been observed in a number of respiratory tract diseases. These SPs may prove to play a significant role in chronic sinusitis. Demonstrated expression of SP-A and SP-D in diseased and normal sinus tissue may mean that these SPs are excreted into the airway-lining fluid of the sinuses. Additionally, initial contact and interaction between pathogens and SP-A and SP-D may occur relatively early after inhalation and deposition into the mucus of the respiratory tract. These findings may lead to potential therapeutic options for difficult-to-treat sinus disease in the future.

Identification and membrane localization of electrogenic sodium bicarbonate cotransporters in Calu-3 cells

Cystic fibrosis (CF) is a severely life-shortening genetic disease resulting from mutations in the gene for the cystic fibrosis transmembrane conductance regulator (CFTR). Impaired bicarbonate secretion is a key component of CF-related pancreatic disease, but the role of impaired bicarbonate secretion in CF lung disease is less well understood. The submucosal glands of the conducting airways produce and secrete a complex airway surface liquid that lines the airway epithelium and plays a significant role in mucociliary clearance. The serous cell is the predominant cell type of the submucosal gland and a predominant site of CFTR expression. Calu-3 cells are a model of airway submucosal gland serous cells that demonstrates vectorial bicarbonate secretion in response to elevations in cAMP. Based on previously published measurements of unidirectional ion flux, pharmacological inhibition of short-circuit current and ion substitution studies, one can hypothesize the existence of an electrogenic sodium bicarbonate cotransporter (NBC) in the basolateral membrane of Calu-3 cells that mediates bicarbonate entry from the interstitium. To test this hypothesis, we performed reverse-transcriptase PCR, western blotting, and surface biotinylation to identify and localize electrogenic NBCs in Calu-3 cells. Our data demonstrate that both pNBC1 and NBC4 mRNAs can be identified and that their protein products are expressed at the basolateral membrane of polarized Calu-3 cells. These data suggest that these transporters contribute to regulated bicarbonate secretion across Calu-3 cells and perhaps human airway submucosal glands.

Circadian rhythms in ciliary beat frequency of human bronchial epithelial cells, in vitro

Introduction Studies of ciliated airway epithelial cells have suggested that these play a vital role in mucociliary clearance and consequently in maintenance of airways integrity. Studies of the mechanism/s underlying this process have demonstrated that efficient mucus clearance is dependent on the total number of cilia and the coordination and frequency of their beat, of which the latter is significantly influenced by neurohormones and neurotransmitters (1). Sanderson and Dirksen ( 2 ) a n d Tamaoki and colleagues (3) have investigated the mechanism/s influencing the ciliary beat frequency of rabbit tracheal epithelium explants, in vitro, and suggested that two independent mechanisms, one utilizing calcium and the other utilizing cAMP, may be operative. Whilst studies of plasma concentrations of agents such as cAMP and epinephrine, which modulate ciliary activity, have suggested that these may be influenced by circadian rhythms (4,5), to date there are no such reports of the influence of circadian rhythms on ciliary activity of human bronchial epithelial cells. Investigations of ciliary activity of cultured human bronchial epithelial cells, in our laboratory, have suggested that the ciliary beat frequency of these cells may also be influenced by circadian rhythms, since this was attenuated in the early morning hours each day, irrespective of the experimental condition under investigation (6,7). In view of these findings, the aim of the present study was to elucidate whether ciliary beat frequency (CBF) of human bronchial epithelial cells, in vitro, was influenced by circadian rhythms and to see if changes in CBF correlated with changes in generation of cAMP in these cultures.

The effects of salmeterol and salbutamol on ciliary beat frequency of cultured human bronchial epithelial cells, in vitro

Studies investigating mechanisms of mucociliary clearance have suggested that β 2-adrenergic agents may significantly influence ciliary activity of epithelial cells and therefore play a vital role in the maintenance of functional integrity of the airways. We have cultured human bronchial epithelial cells, from surgical explants and investigated the effects of salbutamol and salmeterol, in a time- and dose-dependent manner, on the ciliary beat frequency (CBF) of these cells. Prior to and at several times after exposure to either salbutamol (10 −8 to 10 −3 m) or salmeterol (10 −8 to 10 −4 m), the epithelial cells were monitored for CBF and on the basis of data obtained from these studies, the effect of 10 −6 m propranolol was investigated in the presence of optimal concentrations of salbutamol and salmeterol. Salbutamol was optimally active at a concentration of 10 −4 m and caused a transient but significant increase in the CBF from baseline level of 8.6 ± 0.4 to 9.6 ± 0.5 Hz ( P < 0.05), after 2 h incubation. In contrast, salmeterol was maximally active at a concentration of 10 −6 m and caused a significantly rapid and prolonged increase in CBF from a baseline value of 9.2 ± 0.4 to 10.9 ± 0.6 Hz ( P < 0.02) and 10.6 ± 0.8 Hz ( P < 0.05) after 15 min and 24 h incubation, respectively. Propranolol (10 −6 m) abrogated the salbutamol- but not the salmeterol-induced increases in CBF. Analysis of cultures for cAMP demonstrated that both salbutamol and salmeterol led to a significant release of cAMP into the culture medium and increased the amounts of CAMP from a baseline value of 4.5 ± 0.7 fmol/μg protein to 137.4 ± 38.7 and 151.8 ± 49.1 fmol/μg protein, respectively, after 24 h incubation ( P < 0.001). Propranolol significantly attenuated both the salbutamol- and salmeterol-induced release of cAMP ( P < 0.001 and P < 0.01, respectively). These results suggest that salmeterol may be of particular significance in the management of airway disease due to its role in mucociliary clearance, in addition to bronchodilation.