Effects of free radicals on ciliary movement in the human nasal epithelial cells

An Adverse Outcome Pathway for Decreased Lung Function Focusing on Mechanisms of Impaired Mucociliary Clearance Following Inhalation Exposure

Adverse outcome pathways (AOPs) help to organize available mechanistic information related to an adverse outcome into key events (KEs) spanning all organizational levels of a biological system(s). AOPs, therefore, aid in the biological understanding of a particular pathogenesis and also help with linking exposures to eventual toxic effects. In the regulatory context, knowledge of disease mechanisms can help design testing strategies using in vitro methods that can measure or predict KEs relevant to the biological effect of interest. The AOP described here evaluates the major processes known to be involved in regulating efficient mucociliary clearance (MCC) following exposures causing oxidative stress. MCC is a key aspect of the innate immune defense against airborne pathogens and inhaled chemicals and is governed by the concerted action of its functional components, the cilia and airway surface liquid (ASL). The AOP network described here consists of sequences of KEs that culminate in the modulation of ciliary beat frequency and ASL height as well as mucus viscosity and hence, impairment of MCC, which in turn leads to decreased lung function.

Redox regulation of motile cilia in airway disease

Motile cilia on airway cells are necessary for clearance of mucus-trapped particles out of the lung. Ciliated airway epithelial cells are uniquely exposed to oxidants through trapping of particles, debris and pathogens in mucus and the direct exposure to inhaled oxidant gases. Dynein ATPases, the motors driving ciliary motility, are sensitive to the local redox environment within each cilium. Several redox-sensitive cilia-localized proteins modulate dynein activity and include Protein Kinase A, Protein Kinase C, and Protein Phosphatase 1. Moreover, cilia are rich in known redox regulatory proteins and thioredoxin domain-containing proteins that are critical in maintaining a balanced redox environment. Importantly, a nonsense mutation in TXNDC3, which contains a thioredoxin motif, has recently been identified as disease-causing in Primary Ciliary Dyskinesia, a hereditary motile cilia disease resulting in impaired mucociliary clearance. Here we review current understanding of the role(s) oxidant species play in modifying airway ciliary function. We focus on oxidants generated in the airways, cilia redox targets that modulate ciliary beating and imbalances in redox state that impact health and disease. Finally, we review disease models such as smoking, asthma, alcohol drinking, and infections as well as the direct application of oxidants that implicate redox balance as a modulator of cilia motility.

The Role of Oxidants and Antioxidants in Otitis Media with Effusion in Children

OBJECTIVE: Determine the possible role of oxidants and antioxidants in the pathogenesis of otitis media with effusion in children.

STUDY DESIGN AND SETTING: Randomized controlled trial, tertiary referral center. The study group was made up of children with otitis media with effusion who were to undergo bilateral ventilation tube insertion and adenoidectomy. The control group was comprised of otherwise healthy children. The blood levels of antioxidants (retinol, β-carotene, (α-tocopherol, laycopene, ascorbic acid, superoxide dismutase, glutathione peroxidase, GSH) and oxidation products (malondialdehyde) were determined before and 1 month after the operation in the study group and once only in the control group. These substances were also measured in the adenoid tissue and middle ear fluids.

RESULTS: In the study group, the blood levels of antioxidants and oxidants before and after the operation were significantly different when compared with the control group ( P < 0.05). In the study group, the blood antioxidant levels increased and oxidant levels decreased significantly after the operation ( P < 0.05). The levels after the operation never reached those of the control group.

CONCLUSIONS AND SIGNIFICANCE: Oxidants and antioxidants played a significant role in the pathogenesis of otitis media with effusion in children. These children are under significant oxidative stress. Insertion of a ventilation tube and adenoidectomy significantly decreased the oxidative stress in these patients, but could not normalize it completely. Additional studies are necessary in the clinical use of antioxidants in otitis media with effusion.

The effect of drugs and other compounds on the ciliary beat frequency of human respiratory epithelium

BACKGROUND

Cilia in the human respiratory tract play a critical role in clearing mucus and debris from the airways. Their function can be affected by a number of drugs or other substances, many of which alter ciliary beat frequency (CBF). This has implications for diseases of the respiratory tract and nasal drug delivery. This article is a systematic review of the literature that examines 229 substances and their effect on CBF.

METHODS

MEDLINE was the primary database used for data collection. Eligibility criteria based on experimental design were established, and 152 studies were ultimately selected. Each individual trial for the substances tested was noted whenever possible, including concentration, time course, specific effect on CBF, and source of tissue.

RESULTS

There was a high degree of heterogeneity between the various experiments examined in this article. Substances and their general effects (increase, no effect, decrease) were grouped into six categories: antimicrobials and antivirals, pharmacologics, human biological products, organisms and toxins, drug excipients, and natural compounds/other manipulations.

CONCLUSION

Organisms, toxins, and drug excipients tend to show a cilioinhibitory effect, whereas substances in all other categories had mixed effects. All studies examined were in vitro experiments, and application of the results in vivo is confounded by several factors. The data presented in this article should be useful in future respiratory research and examination of compounds for therapeutic and drug delivery purposes.

Effects of thymoquinone and montelukast on sinonasal ciliary beat frequency

BACKGROUND

Herbal remedies predate written history and continue to be used more frequently than conventional pharmaceutical medications. Thymoquinone (TQ) is a traditional herb that has been used for its anti-inflammatory, antioxidant, and chemopreventive effects. Montelukast is a conventional medication used to treat allergic rhinitis and asthma. The aim of this research was to evaluate the effects of TQ and montelukast on human respiratory epithelium specifically addressing effects on cilia beat frequency (CBF).

METHODS

Well-differentiated human sinonasal epithelial cultures, grown at an air-liquid interface were treated with varying concentrations of TQ and montelukast. Changes in CBF were determined using the Sissons-Ammons Video Analysis system.

RESULTS

When applied to the basolateral surface, TQ showed a statistically significant dose-dependent increase in CBF with maximal stimulation at 30 minutes. Effects of montelukast on CBF showed both time and dose dependence with maximal stimulatory effect measured at 6 hours.

CONCLUSION

The results of our study indicate that TQ and montelukast have dose-dependent effects on CBF, extending their mechanism of action in respiratory diseases.

Advanced oxidation protein product level in children with chronic otitis media with effusion

OBJECTIVE

To determine the level of advanced oxidation protein products (AOPPs) in children with chronic otitis media with effusion (COME), in an effort to elucidate the multifactorial etiology of this disease.

METHODS

This study involved 25 COME patients and 30 healthy children (control group) recruited from the Ear, Nose and Throat (ENT) and Pediatric Departments, respectively, of the Haseki Research and Training Hospital. In the COME group, blood samples were collected before a middle ear operation, and middle ear fluid was sampled during the operation. Blood samples were also obtained from the control subjects. AOPP levels in the plasma and effusion fluid were measured by the spectrophotometric method.

RESULTS

In the COME group, the mean AOPP levels in plasma and effusion fluid were 168.08 μmol/l and 412.75 μmol/l, respectively. In the control group, the mean plasma AOPP level was 141.54 μmol/l. The plasma AOPP levels did not significantly differ between the COME and control groups (p>0.05). In the COME group, however, the effusion fluid AOPP level (412.75 ± 204.54 μmol/l) was significantly higher than the plasma AOPP level (168.08 ± 68.45 μmol/l; p<0.01).

CONCLUSION

We found that AOPP levels were elevated in the effusion fluid, but not in the plasma, of COME patients. Thus, COME was associated with protein oxidation abnormalities. Oxidative stress may play a role in the etiopathogenesis of COME, and AOPPs may be used as markers of oxidative stress; however, further studies are required to confirm these findings.

Serum myeloperoxidase activity, total antioxidant capacity and nitric oxide levels in patients with chronic otitis media

It has been suggested that oxidative stress may play an important role in the pathogenesis of chronic otitis media (COM), but the role of oxidative stress in the pathogenesis of COM has not yet been fully explored. Therefore, the aim of this study was to investigate serum myeloperoxidase (MPO) activity, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), total antioxidant capacity (TAC) and nitric oxide (NO) in patients with COM. Sixty-one patients with COM and 30 controls were enrolled in the present study. Patients were divided into two groups according to the presence (n = 21) or absence (n = 40) of cholesteatoma. Serum MPO activity and 4-HNE, MDA and NO levels were significantly higher in patients with COM than controls (for all, p < 0.001), while TAC levels were significantly lower (for all, p < 0.001). Serum MPO activity and MDA, 4-HNE and NO levels were significantly higher in patients with cholesteatoma than in those without cholesteatoma, while TAC levels were significantly lower; but the difference between groups was not statistically significant (p > 0.05). Increased oxidative stress seems to be associated with decreased antioxidant levels in patients with COM. Thus, increased oxidative stress may play a role in the pathogenesis of COM. It is believed that the administration of antioxidant vitamins such as A, C and E may be useful in preventing and treating COM.

Comparative monitoring of oral theophylline treatment in blood serum, saliva, and nasal mucus

BACKGROUND

Theophylline, used in the treatment for various pulmonary pathologies, is usually given orally with drug levels measured primarily in blood serum and occasionally in saliva. Although theophylline treatment is now not commonly used it has been effective to correct smell loss (hyposmia). This is important because 21 million people in the United States exhibit hyposmia and oral theophylline has corrected hyposmia in about 50% of these patients. This result suggests that oral theophylline may result in the drug not only appearing in the serum but also in nasal mucus, thereby playing a role in correcting hyposmia. No prior report of theophylline in nasal mucus has been made and no comparison of levels in nasal mucus, blood serum, or saliva has been previously reported.

PURPOSE

The aim was to determine, after oral theophylline treatment, if it is present in nasal mucus and, if present, to compare the levels with those in serum and saliva.

METHODS

Oral theophylline was given to 23 hyposmic patients at daily doses of 200, 300, 400, 600, and 800 mg for periods of 2-10 months. During each period, blood serum, saliva, and nasal mucus were collected and theophylline measured in each fluid.

RESULTS

Theophylline was found in nasal mucus and in saliva and blood serum at each drug dose in each patient to whom it was given. The mean level of theophylline in nasal mucus was 74% that of serum; mean level in saliva was 67% of serum; mean level in nasal mucus was 111% that in saliva.

CONCLUSIONS

Theophylline is present in nasal mucus after oral administration. Levels in nasal mucus reflect blood and saliva levels in a consistent manner and offer a simple convenient noninvasive method to monitor theophylline doses of the oral drug.

Recurrent Acute Rhinosinusitis: A Single Blind Clinical Study of N-Acetylcysteine vs Ambroxol Associated to Corticosteroid Therapy

The aim of rhinosinusitis treatment is to restore sinusal eutrophism and to normalize ventilation and mucociliary transport. Frequently the improvement of sinusal physiological conditions is associated with a reduction of infections and pulmonary symptoms. The treatment of these diseases often requires the combination of medical and surgical strategies. In particular, the aim of the medical therapy is multiple: to treat the infection (with antibiotics), to reduce the mucosal swelling (with corticosteroids) and to improve mucus drainage (with mucolytics or muco-regulators). The use of atomized nasal douche, as a washing of the nasal fossas, is chosen because of its local action minimizing systemic adverse effects. The surgical treatment is secondary to medical failure, and it is focused on clearing the sinusal ostia in the sphenoethmoidal recess and the osteomeatal complex. In case of recurrent sinonasal diseases the importance of the surgical operation is represented by the fact that the medical treatment better reaches the target in the sinusal space. This study is focused on the primary medical treatment of acute recurrent rhinosinusitis. The patients who immediately needed surgical treatment were excluded from the study (because of the presence of an anatomical obstruction of the osteomeatal complex and/or the sphenoethmoidal recess, hence non-susceptible to improvement by medical therapy alone), and these patients were immediately addressed to undergo a CT scan examination in order to be involved in a future surgical programme. The medical treatment for those forms which do not require antibiotics (i.e. when infections are not involved), is based on the use of topical corticosteroids. While there are controversies on the real efficacy of adding mucolytic agents to the steroids, they are commonly prescribed in clinical practice, with the rationale of reducing viscosity and improving clearance of mucus in order to help the restoration of the physiological sinus conditions. The primary aim of the medical treatment is to reduce the number of acute episodes and thus to increase the time between the exacerbations, allowing a good quality of life without necessitating surgical procedure.

The effect of passive smoking and breast feeding on serum antioxidant vitamin (A, C, E) levels in infants

AIM

Toxic substances in tobacco smoke are known to have negative effects on the antioxidant capacity of human body. In order to investigate the effect of passive smoking on serum antioxidant levels in infants, serum vitamin A, E, C levels and urinary cotinine/creatinine levels were measured in 254 infants at the age of 6 months.

METHODS

The information about infants' nutrition and exposure to tobacco smoke was obtained from the mothers by the help of a questionnaire. The infants were grouped according to both smoking status of mother and urinary cotinine/creatinine levels.

RESULTS

The mean serum vitamin A, C and E levels of infants of smoking mothers were significantly lower than those of non-smoking mothers (p < 0.05). Vitamin A, E and C levels were negatively correlated with urinary cotinine/creatinine levels (p < 0.05, r: -0.61, -0.42, -0.53, respectively). Multivariate analysis revealed independent factors determining the serum vitamin A, E and C levels of infants as maternal smoking and breast feeding (p < 0.05).

CONCLUSION

Tobacco smoke exposure of infants significantly decreases their serum antioxidant vitamin A, C and E levels. However, breast feeding may help to prevent the decrement of antioxidant vitamin levels of passive smoking infants.

Apical oxidative hyaluronan degradation stimulates airway ciliary beating via RHAMM and RON

Hyaluronan (HA) is synthesized in high-molecular-weight form at the apical pole of airway epithelial cells, covering the luminal surface. When human airway epithelial cells grown and redifferentiated at the air-liquid interface (ALI) were exposed to xanthine/xanthine oxidase (X/XO), ciliary beat frequency (CBF) increased. This effect was blocked by superoxide dismutase (SOD) and catalase. Inhibition of hyaluronan synthesis inhibited the CBF response to X/XO, while addition of exogenous HA amplified it. A functionally blocking antibody to the receptor for hyaluronic acid-mediated motility (RHAMM) reduced the CBF response to X/XO. Since RHAMM has no transmembrane domain and thus cannot signal on its own, the association of RHAMM with recepteur d'origine nantais (RON), a member of the hepatocyte growth factor receptor family, was explored. Immunohistochemistry of human airway epithelium showed co-localization of RHAMM and RON at the apex of ciliated cells. Physical association of RHAMM and RON was confirmed with co-immunoprecipitations. Macrophage-stimulating protein (MSP), an agonist of RON, stimulated CBF. Genistein, a nonspecific tyrosine kinase inhibitor, and MSP beta chain (beta-MSP), a specific RON inhibitor, blocked the X/XO-induced CBF increase. HA present in the apical secretions of human airway epithelial cells was shown to degrade upon exposure to X/XO, a process inhibited by SOD. Low-molecular-weight HA fragments stimulated CBF, an effect blocked by anti-RHAMM antibody and genistein. These data suggest that high molecular form HA is broken down by reactive oxygen species to form low-molecular-weight fragments that signal via RHAMM and RON to stimulate CBF.

Ultrastructural nasal pathology in children chronically and sequentially exposed to air pollutants

Southwest Metropolitan Mexico City (SWMMC) children are repeatedly exposed to a complex mixture of air pollutants, including ozone, particulate matter, and aldehydes. Nasal biopsies taken from these children exhibit a wide range of histopathologic alterations: marked changes in ciliated and goblet cell populations, basal cell hyperplasia, squamous metaplasia, and mild dysplasias. We studied the ultrastructural features of 15 nasal biopsies obtained from clinically healthy children 4 to 15 yr of age, growing up in SWMMC. The results were compared with nasal biopsies from 11 children growing up in Veracruz and exposed to low pollutant levels. Ultrathin sections of nasal biopsies revealed an unremarkable mucociliary epithelium in control children, whereas SWMMC children showed an epithelium comprised of variable numbers of basal, ciliated, goblet, and squamous metaplastic as well as intermediate cells. Nascent ciliated cells, as evidenced by the presence of migratory kinetosomes, were common, as were ciliary abnormalities, including absent central microtubules, supernumerary central and peripheral tubules, ciliary microtubular discontinuities, and compound cilia. Dyskinesia associated with these abnormal cilia was suggested by the altered orientation of the central microtubules in closely adjacent cilia. A transudate was evident between epithelial cells, suggesting potential deficiencies in epithelial junction integrity. Particulate matter was present in heterolysosomal bodies in epithelial cells and it was also deposited in intercellular spaces. The severe structural alteration of the nasal epithelium together with the prominent acquired ciliary defects are likely the result of chronic airway injury in which ozone, particulate matter, and aldehydes are thought to play a crucial role. The nasal epithelium in SWMMC children is fundamentally disordered, and their mucociliary defense mechanisms are no longer intact. A compromised nasal epithelium has less ability to protect the lower respiratory tract and may potentially leave the distal acinar airways more vulnerable to reactive gases. Impairment of mucociliary clearance has the potential to increase the contact time between deposited mutagenic particulate matter and the epithelial surface, thus increasing the risk for nasal carcinogenesis. Chronic exposures to air pollutants affect the whole respiratory tract; the nasal epithelium is an accessible and valuable sentinel to monitor exposures to toxic or carcinogenic substances.