Shusheng Tai

A mechanism of airway injury in an epithelial model of mucociliary clearance

We studied the action of sodium metabisulphite on mucociliary transport in a frog palate epithelial injury model, hypothesizing that it may be useful for the study of mechanisms of airway injury. Sodium metabisulphite (MB) releases SO2 on contact with water. SO2 is a pollutant in automobile fumes and may play a role in the exacerbation of airway disease symptoms. We first investigated its effect on mucociliary clearance. MB 10-1 M, increased mucociliary clearance time (MCT) by 254.5 ± 57.3% of control values, (p < 0.001, n = 7). MB 10-4 and 10-2 M did not interfere with mucus clearance time compared to control values. In MB-treated frog palates, MCT did not return to control values after one hour (control, 97.3 ± 6.3% vs. MB, 140.9 ± 46.3%, p < 0.001, n = 7). Scanning EM images of epithelial tissue were morphometrically analyzed and showed a 25 ± 12% loss of ciliated cells in MB palates compared to controls with an intact ciliary blanket. Intact cells or groups of ciliated cells were found in scanning EM micrographs of mucus from MB-treated palates. This was associated with increased matrix metalloproteinase (MMP-9) activity in epithelial tissue and mucus. We suggest that the loss of ciliated cells as a result of MMP-9 activation prevented full recovery of MCT after MB 10-1 M. The mechanism of action may be on epithelial cell-cell or cell-matrix attachments leading to cell loss and a disruption of MCT. Further studies are warranted to determine whether this is an inflammatory mediated response or the result of a direct action on epithelial cells and what role this mechanism may play in the progression to chronic airway diseases with impaired mucociliary clearance.

Adaptation of an amphibian mucociliary clearance model to evaluate early effects of tobacco smoke exposure.

RationaleInhaled side-stream tobacco smoke brings in all of its harmful components impairing mechanisms that protect the airways and lungs. Chronic respiratory health consequences are a complex multi-step silent process. By the time clinical manifestations require medical attention, several structural and functional changes have already occurred. The respiratory system has to undergo an iterative process of injury, healing and remodeling with every exposure.MethodsTo have a better understanding of the initial changes that take place when first exposed to environmental tobacco smoke, we have developed an exposure model, using the frog palate that closely represents the features of obstructive airways where ciliary dysfunction and mucus hypersecretion occur.ResultsMucus transport was significantly reduced, even after exposure to the smoke of one cigarette (p < 0.05) and even further with 4-cigarettes exposure (p < 0.001). Morphometric and ultrastructural studies by SEM show extensive areas of tissue disruption. Gelatinase zymography shows activation of MMP9 in mucus from palates exposed to tobacco smoke.ConclusionsThe clearance of mucus on the frog palate is significantly reduced after exposure to environmental tobacco smoke. Cilia and the extracellular matrix are anatomically disrupted. Tobacco smoke triggers an increased activity of matrix metalloproteinases associated with a substantial defoliation of ciliated epithelium. These studies enhance the knowledge of the changes in the mucociliary apparatus that occur initially after exposure to environmental tobacco smoke, with the goal of understanding how these changes relate to the genesis of chronic airway pathologies in humans.

Additive Effect of Dornase Alfa and Nacystelyn on Transportability and Viscoelasticity of Cystic Fibrosis Sputum

OBJECTIVE To investigate the effect of dornase alfa (DA), Nacystelyn (NAL) and their combination on mucociliary transportability and mucus viscoelasticity of cystic fibrosis (CF) sputum, and to assess whether the combination possesses an additive effect. DESIGN Determination of transportability in frog palate and viscoelasticity in vitro. SETTING Research laboratory at a medical centre. PATIENTS Sputa from 15 patients with CF, chronically infected with Pseudomonas aeruginosa, were studied. INTERVENTIONS Sputum samples were incubated without any drug solution as a control, and with normal saline, DA, NAL and a mixture of DA and NAL in concentrations approximating those achieved in clinical practice. RESULTS Normal saline (10% volume) by itself had a small effect on CF sputum transportability with a mean increase of 9%, and on viscoelasticity with a mean of decrease of 0.22 log units, respectively, compared with control (incubation without saline). DA (200 nM) further increased the transportability by a mean of 35% versus saline and decreased viscoelasticity by a mean of 0.30 log units. NAL (100 M) increased the transportability by a mean of 32% and decreased viscoelasticity by a mean of 0.22 log units from the levels achieved with saline. The mixture of DA plus NAL at one-half of the above concentration of each agent produced an additional increase in the transportability, by a mean of 18%, and a further decrease in viscoelasticity, by a mean of 0.25 log units, compared with DA or NAL as a single treatment. CONCLUSIONS The combination of DA and NAL exhibits an additive effect for both the viscoelasticity and transportability of CF sputum samples. The two agents appear to act well together in breaking down the bonding due to extracellular DNA and mucins. Clinical studies should be undertaken to see whether the additive combination at lower concentration produces the anticipated benefits of improved airway clearance and fewer side effects.

Effect of needle puncture and electro-acupuncture on mucociliary clearance in anesthetized quails

BackgroundAcupuncture therapy for obstructive respiratory diseases has been effectively used in clinical practice and the acupuncture points or acupoints of Zhongfu and Tiantu are commonly-used acupoints to treat patients with the diseases. Since the impaired mucociliary clearance is among the most important features of airway inflammation in most obstructive respiratory diseases, the effect of needle puncture and electro-acupuncture at the specific acupoints on tracheal mucociliary clearance was investigated in anesthetized quails.MethodsMucociliary transport velocity on tracheal mucosa was measured through observing the optimal pathway, and fucose and protein contents in tracheal lavages were determined with biochemical methods. In the therapeutic group, needle puncture or electro-acupuncture stimulation to the acupoints was applied without or with constant current output in 2 mA and at frequency of 100 Hz for 60 minutes. In the sham group, electro-acupuncture stimulation to Liangmen was applied.ResultsOur present experiments demonstrated that the electro-acupuncture stimulation to Zhongfu and Tiantu significantly increased tracheal mucociliary transport velocity and decreased the content of protein in the tracheal lavage, compared with the control group. Moreover, either needle puncture or electro-acupuncture stimulation to Zhongfu and Tiantu significantly reverted the human neutrophil elastase-induced decrease in tracheal mucociliary transport velocity and human neutrophil elastase -induced increase in the contents of fucose and protein in the tracheal lavage, compared with the control group.ConclusionThese results suggest that either needle puncture or electro-acupuncture stimulation to the effective acupoints significantly improves both airway mucociliary clearance and the airway surface liquid and that the improvements maybe ascribed to both the special function of the points and the substantial stimulation of electricity.

Evaluation of a Mucoactive Herbal Drug, Radix Ophiopogonis, in a Pathogenic Quail Model

We investigated the effect of Radix Ophiopogonis on airway mucociliary clearance and mucus secretion in anesthetized quails. The oral administration of 10 g/kg of Radix Ophiopogonis significantly increased tracheal mucociliary transport velocity (MTV). Moreover, either 10 g/kg or 3 g/kg of Radix Ophiopogonis markedly attenuated the human neutrophil elastase (HNE)-induced decrease in MTV. Furthermore, we found that 10 g/kg of Radix Ophiopogonis significantly abolished the HNE-induced increases in fucose and protein contents of tracheal lavage, whereas Radix Ophiopogonis at the same dose only significantly decreased the protein content in the control group. These results suggest that Radix Ophiopogonis improves airway mucociliary clearance and that the improvement may, at least in part, be ascribed to the amelioration of airway mucus secretion.