Surgical outcomes of overlapping lateral pharyngoplasty with or without coblator tongue base resection for obstructive sleep apnea.

PURPOSE: Considerable number of patients with obstructive sleep apnea (OSA) failed to respond to positive airway pressure therapy and so turned to surgical procedures. A wide variety of surgical procedures have been developed and advanced, according to obstruction and target site through nasal cavity to trachea. We introduced our overlapping lateral pharyngoplasty (OLP) technique as a surgical option for OSA and evaluated its surgical outcomes both with and without endoscope-guided coblator tongue base resection (CobTBR). METHODS: Sixty-five patients underwent either OLP alone or OLP combined with CobTBR to treat OSA at academic tertiary center. Twenty-nine patients underwent postoperative polysomnography and were divided into two groups, as an OLP group and an OLP combined CobTBR group. Various parameters from physical examinations and polysomnographic results were compared and analyzed. RESULTS: Most enrolled patients improved on various polysomnographic parameters, including AHI and oxygen levels. In the OLP group, 91.7% of patients showed a surgical response and the overall success rate was 66.7%. Mean AHI improved significantly from 36.3 to 14.8. In the OLP + CobTBR group, all patients showed improvement in AHI and the surgical response rate was 100%. The overall success rate was 70.6% and mean AHI improved from 38.8 to 13.1. In both groups, various parameters such as RDI, lowest O2 saturation, mean O2 saturation, oxygen desaturation index, supine AHI, and ESS significantly improved after surgery. CONCLUSION: Our OLP technique appears to be safe and effective among OSA patients. Multi-level OLP surgery combined with CobTBR can be a good surgical strategy for patients experiencing retroglossal obstruction.

Protease-activated receptor 2-dependent fluid secretion from airway submucosal glands by house dust mite extract.

BACKGROUND: The submucosal gland (SMG) is important in the control of airway surface fluid. Protease-activated receptor (PAR) 2 contributes to the pathophysiology of allergies in response to nonspecific allergens bearing proteases and anion secretion. House dust mites (HDMs) have abundant proteases that can activate PAR2, but little is known about the direct effect of HDM on SMG secretion. OBJECTIVE: The aim of this study was to investigate the effect of HDMs on glandular secretion and its mechanism in allergic patients, patients with chronic rhinosinusitis (CRS), or both. METHODS: Inferior nasal turbinates were harvested from 55 patients and classified into 4 groups (the control, allergic rhinitis [AR], CRS, and AR+CRS groups). A microscope attached to a digital camera was used to quantify mucus bubbles from individual SMGs while stimulated with HDM extract, PAR2-activating peptide, and carbachol. PAR2 expression in the SMG was determined by means of immunostaining with anti-PAR2 mAb. RESULTS: HDM induced a significantly higher secretion rate and number of responding glands in the AR and AR+CRS groups than in the control group. Interestingly, patients in the CRS group, who had no HDM-specific IgE antibody, showed a higher response than the control group, and its response was suppressed by a PAR2-selective antagonist. The responses to PAR2-activating peptide were similar to those to HDM, and their secretion rates positively correlated with HDM responses. PAR2 was highly expressed in all 3 disease groups with immunostaining. CONCLUSIONS: HDM allergens can induce glandular secretion in patients with AR, CRS, or both, and PAR2 represents a possible mechanism for nonspecific hyperreactivity in inflammatory airway diseases.

Radiologic characteristics of sinonasal fungus ball: an analysis of 119 cases.

BACKGROUND: It is important to differentiate sinonasal fungus ball from non-fungal sinusitis and other forms of fungal sinusitis in order to determine the optimal treatment. In particular, a sinonasal fungus ball, a non-invasive fungal sinusitis, can be characterized by radiologic findings before surgery. PURPOSE: To differentiate a sinonasal fungus ball from other types of sinusitis and determine optimal treatment on the basis of radiologic findings before surgery. MATERIAL AND METHODS: We studied 119 patients with clinically and pathologically proven sinonasal fungus balls. Their condition was evaluated radiologically with contrast-enhanced CT (99 patients), non-contrast CT (18 patients) and/or MRI (17 patients) prior to sinonasal surgery. RESULTS: Calcifications were found in 78 of 116 (67.2%) patients who underwent CT scans for fungus ball. As opposed to non-contrast CT scans, contrast CT scans revealed hyperattenuating fungal ball in 82.8% and enhanced inflamed mucosa in 65.5% of the patients, respectively. On MRI, most sinonasal fungal balls showed iso- or hypointensity on T1-weighted images and marked hypointensity on T2-weighted images. Inflamed mucosal membranes were noted and appeared as hypointense on T1-weighted images (64.7%) and hyperintense on T2-weighted images (88.2%). CONCLUSION: When there are no calcifications visible on the CT scan, a hyperattenuating fungal ball located in the central area of the sinus with mucosal thickening on enhanced CT scans is an important feature of a non-invasive sinonasal fungus ball. On MRI, a sinonasal fungus ball has typical features of a marked hypointense fungus ball with a hyperintense mucosal membrane in T2-weighted images. A contrast-enhanced CT scan or MRI provides sufficient information for the preoperative differentiation of a sinonasal fungus ball from other forms of sinusitis.

Epicatechin gallate suppresses oxidative stress-induced MUC5AC overexpression by interaction with epidermal growth factor receptor.

The goal of this study was to investigate the effect of epicatechin gallate (ECG), a component of green tea polyphenols, on the signal pathway for oxidative stress-induced intracellular reactive oxygen species (ROS) generation and MUC5AC overexpression in normal human nasal epithelial (NHNE) cells. Passage-2 NHNE cells were used, and ECG was administered before stimulation with exogenous hydrogen peroxide (H(2)O(2)). MUC5AC gene and protein levels were measured by real-time PCR and dot blot analysis. Western blot analysis and immunocytofluorescence study were performed for detecting the activity of epidermal growth factor receptor (EGFR). Exogenous H(2)O(2) increases intracellular ROS generation, leading to the overexpression of MUC5AC. The phosphorylation and internalization of EGFR were associated with this ROS generation. ECG decreased the phosphorylation and internalization of EGFR at the cell surface of NHNE cells, resulting in the attenuation of exogenous H(2)O(2)-induced intracellular ROS generation and MUC5AC overexpression. ECG may be a therapeutic material against oxidative stress-induced ROS generation and mucus hypersecretion in airways.

Sphenoid sinus pneumatization and its relation to bulging of surrounding neurovascular structures.

OBJECTIVES: We investigated the bulging and dehiscence of neurovascular structures in the sphenoid sinus and their relationships to the pneumatization of the sphenoid sinus. METHODS: One hundred sagittally hemisected cadaveric heads were examined. The degree of pneumatization of the sphenoid sinus was determined. Bulging and dehiscence of the internal carotid artery (ICA), optic nerve, maxillary nerve, and vidian nerve were examined, and the distances between these structures and the anterior or superior wall of the sphenoid sinus were measured. Additionally, the degree of bony thickness over these structures was determined. RESULTS: The prevalences of bulging of the optic nerve, segments 1 and 3 of the ICA, and the maxillary and vidian nerves were 56%, 34%, 65%, 41%, and 52%, respectively. The greater the degree of pneumatization, the more frequently did the structures bulge into the sphenoid sinus. The optic nerve was found to be in close proximity to the anterior and superior walls of the sphenoid sinus. The bone over the surrounding structures was very thin, especially for the complete sellar type. CONCLUSIONS: The prevalence of bulging of the optic nerve, the ICA, and the maxillary and vidian nerves increased in proportion to the degree of sphenoid sinus pneumatization.

Regulator of G-protein signaling 4 suppresses LPS-induced MUC5AC overproduction in the airway.

Mucus overproduction and airway obstruction are common features in airway mucosal inflammation. The mechanism by which LPS induces MUC5AC overexpression, however, has not been fully explored. The aims of this study were twofold: first, to examine the ATP-dependent mechanism by which LPS induces MUC5AC gene expression, and second, to identify specific molecules that could suppress LPS-induced MUC5AC expression at a G-protein-coupled receptor level. Here, we suggest that LPS from Pseudomonas aeruginosa induces MUC5AC overproduction by both an ATP-dependent pathway and an ATP-independent pathway. In addition, we showed that Regulator of G-protein signaling (RGS) 4 plays as a suppressor for ATP-induced MUC5AC expression by interacting with G alpha q in a GTP-dependent manner in vivo. These results give additional insights into the molecular mechanism of negative regulation of mucin overproduction and enhance our understanding of mucus hypersecretion during airway mucosal inflammation.

The role of Nox4 in oxidative stress-induced MUC5AC overexpression in human airway epithelial cells.

Mucus hypersecretion is a prominent manifestation in patients with chronic inflammatory airway diseases, and MUC5AC is a major airway mucin. It is well known that reactive oxygen species (ROS) may be involved in the pathogenesis of various inflammatory airway diseases. The purpose of this study was to identify which secreted mucin genes are induced by exogenous hydrogen peroxide and the mechanism by which these genes are up-regulated in normal human nasal epithelial (NHNE) cells. Exogenous H(2)O(2) induced the ligand-independent activation of epidermal growth factor receptors (EGFR) and the subsequent activation of ERK1 mitogen-activated protein kinase, resulting in the induction of intracellular ROS generation. Through this signal pathway, exogenous H(2)O(2) markedly induced overexpression of the MUC5AC gene alone. In addition, Nox4, a subtype of nonphagocytic NADPH oxidase, was found to play a key role in intracellular ROS generation and exogenous H(2)O(2)-induced MUC5AC gene expression in NHNE cells.

Epigallocatechin-3-gallate inhibits interleukin-1beta-induced MUC5AC gene expression and MUC5AC secretion in normal human nasal epithelial cells.

It has been reported that the proinflammatory cytokine interleukin-1beta (IL-1beta) induces mucus hypersecretion in normal human nasal epithelial (NHNE) cells and that the MAP kinase pathway may be an important signal pathway in IL-1beta-induced MUC5AC gene expression. Green tea (Camellia sinensis) polyphenols are potent anti-inflammatory agents and have been shown to inhibit inflammation in tumor cell lines and cultured respiratory epithelial cells. In this study, we examined the effect of (-)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol, on IL-1beta-induced MUC5AC gene expression and secretion in NHNE cells. After cells had been treated with IL-1beta (10 ng/ml) and pretreated with EGCG (10, 50 and 100 microM), mRNA expression of MUC5AC was determined by real-time polymerase chain reaction. The suppression of each signal pathway protein was determined by Western blot analysis after treatment with IL-1beta and EGCG, respectively. IL-1beta increased MUC5AC gene expression and MUC5AC secretion. EGCG markedly suppressed IL-1beta-induced MUC5AC gene expression and MUC5AC secretion via suppression of the phosphorylation of ERK MAP kinase, MSK1, and transcription factor, cAMP response element-binding protein. IL-1beta increased the number of cells staining positive with MUC5AC antibodies, and EGCG treatment decreased this number. Our data suggest that EGCG may be an effective inhibitor of IL-1beta-induced mucus hypersecretion.

Airway reconstruction with carrier-free cell sheets composed of autologous nasal squamous epithelium.

OBJECTIVES/HYPOTHESIS: Although skin has been the most effective graft material for reconstructing the airway lumen, the use of squamous epithelium has many problems. If autologous airway squamous epithelium could differentiate into mucociliary epithelium after in vivo grafting, it could be an answer to these problems. In this study, we wanted to examine whether carrier-free nasal epithelial cell sheets composed of autologous squamous epithelium could be used as a substitute for skin in airway luminal reconstruction in three maxillectomy patients. STUDY DESIGN: In vitro biochemical experiments with in vivo applications. METHODS: We cultured nasal squamous epithelium from three maxillary cancer patients prior to maxillectomy. These squamous cell sheets were grafted on the forearm free flap, and, after maxillectomy, the surgical defect was reconstructed with a prefabricated myocutaneous radial forearm free flap with the cultured nasal squamous epithelium. At 1 and 3 month intervals after the reconstructive surgery, the cultured cell grafted area was investigated with histologic phenotype, comparing the skin grafted area. RESULTS: The autologous nasal squamous epithelial cell sheet differentiated into mucociliary epithelium without the crust or mucus stagnation that is usually observed in cases in which skin graft is used for airway reconstruction. CONCLUSIONS: We suggest that autologous cultured nasal squamous epithelium, which differentiates into mucociliary epithelium after in vivo grafting, can be used as a clinically relevant substitute for skin graft in airway luminal reconstruction.

15-Lipoxygenase-1 induced by interleukin-4 mediates apoptosis in oral cavity cancer cells.

It is unknown whether IL-4 induces apoptosis in oral cavity cancer (OCC) cells and, if so, what the mediator of this apoptosis is. Therefore, this study investigated whether apoptosis of OCC cells is induced by IL-4 and whether 15-lipoxygenase-1 (15-LO-1), induced by IL-4, is the mediator of this apoptosis. SCC 1483 oral cavity cancer cells were used in these experiments, and flow cytometry and PARP cleavage were used to examine apoptosis. At an IL-4 dosage that inhibited 50% of cell proliferation, apoptosis was observed, and this apoptosis was inhibited by 2.2 microM caffeic acid (CA). 15-LO-1 mRNA expression was observed beginning at 8 h after treatment with IL-4, and apoptosis increased after 24 h treatment with IL-4. In this apoptosis, the caspase cascade was not involved. In summary, IL-4 induced apoptosis in SCC 1483 OCC cells, and 15-LO-1, induced by IL-4, may mediate this apoptotic pathway.

Expression and regulation of PLUNC in human nasal epithelium.

CONCLUSIONS: We demonstrated that PLUNC (palate, lung, and nasal epithelium clone) is secreted from nasal epithelial cells and is not influenced by differentiation or proinflammatory mediators. The functional role of PLUNC in the human airway has yet to be elucidated. OBJECTIVES: The localization and regulation of PLUNC protein in human nasal epithelium was investigated. First, we located epithelial cells expressing PLUNC protein in human nasal mucosa. Secondly, we sought to identify PLUNC protein in either human nasal secretions from healthy volunteers or apical secretions from cultured human nasal epithelial cells. Lastly, we investigated whether epithelial differentiation and proinflammatory cytokines influence the expression of PLUNC in human nasal epithelial cells. MATERIALS AND METHODS: Immunohistochemical staining for PLUNC was conducted on nasal turbinate specimens. Western blot analysis was conducted on nasal secretions from healthy volunteers, apical secretion from cultured human nasal epithelium, and on normal-appearing posterior ethmoid mucosa, inferior turbinate, and nasal polyp specimens. Reverse transcription-PCR (RT-PCR) of PLUNC was performed with mRNA from cultured human nasal epithelium cells treated with either interleukin-1beta or tumor necrosis factor-alpha. RESULTS: PLUNC was expressed in ciliated cells of surface epithelium and serous cells of the submucosal gland in the human nasal mucosa, and was also found in the nasal secretions of healthy volunteers and apical secretions of cultured human nasal epithelial cells. The degree of mucociliary differentiation and proinflammatory mediators did not influence the expression of PLUNC gene and protein in nasal epithelium.

Use of PLGA scaffold for mucociliary epithelium transfer in airway reconstruction: a preliminary study.

CONCLUSION: A PLGA biodegradable membrane can be used as a scaffold for mucociliary epithelium transfer. OBJECTIVES: The aim of this study was to examine the usefulness of the PLGA membrane as a biodegradable scaffold for mucociliary epithelium transfer in order for it to be used as a substitute for a skin graft for restoring mucosal defects in the airway. METHODS: A PLGA biodegradable membrane was synthesized using the immersion precipitation method, and morphologic characterization was carried out using scanning electron microscopy (SEM). The degradation test was performed by soaking the PLGA membrane in a culture medium, and the morphological changes were observed by SEM. Human nasal basal epithelial (HNBE) cells were cultured on the newly synthesized PLGA membrane, and the morphological changes were analyzed using SEM. The MUC5AC and MUC8 mRNA levels were analyzed by RT-PCR. RESULTS: The PLGA membrane for the mucociliary epithelium transfer was successfully fabricated. It had a 24 mm diameter, a 50 microm thickness, and many pores with diameters of approximately 3 microm. The PLGA membrane began to degrade from 7 days after it was soaked in the culture medium. It rapidly degraded from 3 weeks and severe destruction of the pore structure was noted from 4 to 6 weeks of soaking. The HNBE cells were well differentiated into the mucociliary epithelium on the PLGA membrane both phenotypically and genotypically.

Association of serum 25-hydroxyvitamin D with serum IgE levels in Korean adults.

OBJECTIVE: Studies about the association between vitamin D and allergic disease and the immune-modulatory function of vitamin D have increased in the recent years. However, not enough studies have been conducted for concrete conclusion about the association vitamin D and allergy. We investigate the association between serum immunoglobulin E (IgE) and serum 25-hydroxyvitamin D (25(OH)D) levels in Korean adults. METHODS: We used data of 1969 subjects from the 2010 Korean National Health and Nutrition Examination Survey. Total IgE, Dermatophagoides farinae (Df)-specific IgE, and serum 25(OH)D levels were analyzed. Other variables included sex, age, body mass index, smoking history, and economic status. Adjusted regression analysis was used to examine the independent association of 25(OH)D with serum IgE levels. RESULTS: When we divided all subjects into four groups according to the serum 25(OH)D level: Q1 (lowest), Q2, Q3, and Q4 (highest), the median TIgE level increased with higher quartiles in the Kruskal-Wallis test (p<0.001). Also, the prevalence of Df sensitization was highest in Q4. Serum vitamin D was positively associated with logarithmic transformed total IgE with base of 10 (LogTIgE) (coefficient (B), 0.011; 95% confidence interval, 0.001-0.021). Furthermore, a positive association between 25(OH)D and LogTIgE was found only in men with Df sensitization, but not in men without Df sensitization and women with/without Df sensitization. However, the mean serum 25(OH)D level was significantly lower in participants who were clinically diagnosed with asthma or atopic dermatitis than participants without a history of asthma or atopic dermatitis, respectively. CONCLUSION: Serum 25(OH)D levels were positively associated with total IgE levels. Furthermore, the association between serum 25(OH)D and total IgE levels could vary depending on sex or allergic sensitization. But, the mean serum 25(OH)D level was lower in participants with asthma or atopic dermatitis history than participants without history of asthma or atopic dermatitis. Prospective further studies will be required to verify this discrepancy.

Endoscope-guided coblator tongue base resection using an endoscope-holding system for obstructive sleep apnea.

BACKGROUND: Multilevel obstruction in obstructive sleep apnea commonly includes retroglossal obstruction. To improve surgical success rates, tongue volume reduction with posterior midline glossectomy and/or lingual tonsillectomy is widely performed. METHODS: Nasotracheal intubation was utilized, and the combined tongue procedure was performed as a final step after palatal surgery. The tongue was pulled maximally by a retraction suture and a McIVOR (Karl Storz, Tuttlingen, Germany) or Davis mouth gag (Karl Storz,Tuttlingen, Germany), and a medium-length tongue blade was applied to expose the tongue base. A 70-degree rigid endoscope was fixed by the holding system and introduced into the oral cavity. Endoscope-guided coblator tongue base resection was then performed. RESULTS: The surgeon could use both hands for the surgery, enabling a more delicate resection of tongue base tissue. CONCLUSION: This technique was acceptable and can be successfully used in patients with a large tongue, in whom exposing the tongue base for surgery is difficult.

Lowest Oxyhemoglobin Saturation May Be an Independent Factor Influencing Auditory Function in Severe Obstructive Sleep Apnea.

STUDY OBJECTIVES: The aims of this study were to determine if a correlation exists between the level of hypoxia induced by severe obstructive sleep apnea syndrome (OSAS) and the level of auditory dysfunction when verifying such a relationship using polysomnography (PSG). METHODS: A retrospective review of 41 patients with severe OSAS was performed. Independent risk factors for hearing impairment included parameters of PSG, which were analyzed in two hearing groups at a level ≥ 40 decibels (dB). RESULTS: Oxyhemoglobin saturation, especially the lowest oxyhemoglobin saturation level, showed lower thresholds in the hearing impairment group than in the control group (p = 0.039 at NREM stage; p = 0.029 at REM stage; p = 0.001 at total sleep stage). After adjusting for other risk factors, the sole variable that remained significant was lowest oxyhemoglobin saturation (total; p = 0.046). In the correlation analysis, a decreasing lowest oxyhemoglobin saturation (from all subjects, n = 41) correlated with a greater mean hearing threshold (R(2) = 0.297; p < 0.001). CONCLUSION: Our results indicated that lowest oxyhemoglobin saturation in PSG is the only variable correlated with the hearing threshold. This finding could be predictive of possible hearing alternation in patients with severe OSAS. COMMENTARY: A commentary on this article appears in this issue on page 641.

Improved outcomes after low-concentration hypochlorous acid nasal irrigation in pediatric chronic sinusitis.

OBJECTIVES/HYPOTHESIS: We aimed to evaluate the effectiveness of low-concentration hypochlorous acid (HOCl) nasal irrigation compared to isotonic normal saline for pediatric chronic rhinosinusitis. STUDY DESIGN: This was a randomized, prospective, active-controlled study. METHODS: This study investigated the effectiveness of 4 weeks of low-concentration hypochlorous irrigation by analyzing five categorized subjective symptoms and x-ray findings in pediatric patients with rhinosinusitis. Thirty-seven patients were enrolled, and 26 patients successfully completed the study. RESULTS: Total symptom scores significantly improved with both HOCl and normal saline nasal irrigation, but there was no difference between the two groups. X-ray scores also improved in both groups; improvement was much greater in the HOCl group than the placebo group. CONCLUSIONS: Nasal irrigation with HOCl is an effective adjuvant treatment compared to isotonic normal saline for pediatric sinusitis. LEVEL OF EVIDENCE: 1b.

Expression of 15-lipoxygenase-1 in human nasal epithelium: its implication in mucociliary differentiation.

15-lipoxygenase-1 (15-LO-1) is involved in the differentiation of human tracheobronchial epithelial cells. Here, we investigated the relation between 15-LO-1 expression and the differentiation of human nasal epithelium. In retinoic acid (RA)-sufficient culture media, 15-LO-1 expression in normal human nasal epithelial cell time-dependently increased, but its expression was undetectable in RA-deficient culture media. Moreover, in RA-deficient culture media, IL-4 at 1 ng/ml concentration time-dependently induced 15-LO-1 expression. In addition, MUC8 gene expression, a marker of mucociliary differentiation, was up-regulated by 15-LO-1, which was itself induced by IL-4. In murine nasal mucosa, the expression of leukocyte type-12-LO, a functional equivalent of 15-LO-1, reduced after postnatal day 7. Our findings suggest that 15-LO-1 is related to the differentiation of human nasal epithelium, and that it may mediate the mucociliary differentiation of human nasal epithelium.

Ginkgo biloba extract (EGb 761) induces apoptosis by the activation of caspase-3 in oral cavity cancer cells.

We have investigated whether Ginkgo biloba extract (EGb 761) induces apoptosis of oral cavity cancer cells and attempted to characterize the apoptotic pathway activated by EGb 761. The inhibition of SCC 1483 oral cavity cancer cells proliferation was noted from 250 micro/ml of EGb 761. Apoptosis was observed after 24 h of incubation with 250 microg/ml EGb 761 and occurred in a time- and dose-dependent manner. Apoptosis was confirmed by DNA fragmentation and PARP cleavage. Co-treatment with the caspase inhibitor (z-VAD-fmk) inhibited apoptosis and PARP cleavage induced by EGb 761. Caspase-3 activity was upregulated by EGb 761 but reduced to the control level by co-treating with z-VAD-fmk. In summary, EGb 761 induces apoptosis of oral cavity cancer cells and caspase-3 is activated in this apoptosis. Therefore, EGb 761 may be considered as a possible chemopreventive agent against oral cavity cancer.

Optic nerve injury secondary to endoscopic sinus surgery: an analysis of three cases.

Major orbital complications after the endoscopic sinus surgeries are rare and of these, optic nerve injury is one of the most serious. This study was to undertaken to analyze 3 cases of optic nerve injury after endoscopic sinus surgery. The three cases included one patient with a loss of visual acuity and visual field defect, and two patients with total blindness. In all cases, no improvement of visual acuity was observed despite treatment. It is important to frequently check the location and direction of the endoscope during surgery to avoid optic nerve injury. In addition, surgeons must have a precise knowledge of the detailed anatomy through cadaver dissections, an ability to interpret the PNS CT scan and experienced procedural surgical skills.

Effect of hypo-, iso- and hypertonic saline irrigation on secretory mucins and morphology of cultured human nasal epithelial cells.

CONCLUSION: We speculate that isotonic saline is the most physiological irrigation solution in terms of mucus secretion and the cellular morphology of nasal epithelial cells. OBJECTIVE: To determine the most physiologic and effective saline concentration for nasal irrigation in terms of mucus secretion and cellular morphology by using normal human nasal epithelial cells treated with hypo-, iso- and hypertonic saline. MATERIAL AND METHODS: Fully differentiated passage-2 normal human nasal epithelial cells were treated with pure water and with 0.3% (hypotonic), 0.9% (isotonic) and 3% (hypertonic) saline solutions. mRNA expression levels of MUC5AC and MUC5B, which are known to be major airway mucins, were analyzed after 30 min using reverse transcriptase polymerase chain reaction. Total mucin and MUC5AC and MUC5B mucin secretions were analyzed using dot-blotting. Cellular morphology was observed with light microscopy after hematoxylin-eosin staining and with scanning electron microscopy. RESULTS: MUC5AC and MUC5B mRNA levels did not change after treatment with pure water and various concentrations of saline. Total mucin and MUC5AC mucin secretions only increased following pure water treatment, while MUC5B mucin secretion increased with pure water, hypo- and hypertonic saline treatment. Morphologic analysis revealed that pure water severely damaged normal human nasal epithelial cells and that only isotonic saline did not affect their morphology.