Tracheal Surface Research Articles

Carbenoxolone and triterpenoids inhibited mucin secretion from airway epithelial cells

This study investigated whether carbenoxolone, oleanolic acid and ursolic acid affect ATP-induced mucin secretion from cultured airway epithelial cells. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using (3)H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on (3)H-mucin secretion. The possible cytotoxicity of each agent was investigated with a lactate dehydrogenase assay. The results were as follows: (1) carbenoxolone, oleanolic acid and ursolic acid significantly inhibited the secretion of airway mucin induced by ATP; (2) none of the compounds showed significant cytotoxicity at any concentration. This result suggests that carbenoxolone, oleanolic acid and ursolic acid can regulate 'mucin secretion induced by ATP'--phenomenon simulating mucus overproduction from inflamed airway epithelial cells--y directly acting on airway mucin-secreting cells.

MUC16 is produced in tracheal surface epithelium and submucosal glands and is present in secretions from normal human airway and cultured bronchial epithelial cells

The gel-forming MUC5AC and MUC5B mucins have been identified as major components of human airway mucus but it is not known whether additional mucin species, possibly with other functions, are also present. MUC16 mucin is a well-known serum marker for ovarian cancer, but the molecule has also been found on the ocular surface and in cervical secretions suggesting that it may play a role on the normal mucosal surface. In this investigation, the LUM16-2 antiserum (raised against a sequence in the N-terminal repeat domain) recognized MUC16 in goblet and submucosal gland mucous cells as well as on the epithelial surface of human tracheal tissue suggesting that the mucin originates from secretory cells. MUC16 mucin was present in ‘normal’ respiratory tract mucus as well as in secretions from normal human bronchial epithelial (NHBE) cells. MUC16 from NHBE cells was a high-molecular-mass, monomeric mucin which gave rise to large glycopeptides after proteolysis. N- and C-terminal fragments of the molecule were separated on gel electrophoresis showing that the MUC16 apoprotein undergoes a cleavage between these domains, possibly in the SEA domain as demonstrated for other transmembrane mucins; MUC1 and MUC3. After metabolic labeling of NHBE cells, most of the secreted monomeric, high-molecular-mass [ 35S]sulphate-labelled molecules were immunoprecipitated with the OC125 antibody indicating that MUC16 is the major [ 35S]sulphate-labelled mucin in NHBE cell secretions.

An MMP liberates the Ninjurin A ectodomain to signal a lossof cell adhesion

Matrix metalloproteinases (MMPs) are important for developmental tissue remodeling and for the inflammatory response. Although the vertebrate MMP family is large and functionally redundant, the fruitfly Drosophila melanogaster has only two MMPs, both essential genes. Our previous work demonstrated that Mmp1 is required for growth of the tracheal system, and we suggested that the mutant phenotype resulted from aberrant persistence of cell adhesion to the extracellular matrix. Here we report the identification of NijA, a transmembrane protein whose vertebrate homologs regulate cell adhesion, as a two-hybrid binding partner for Mmp1. The binding of Mmp1 and NijA was confirmed by coimmunoprecipitation of endogenous proteins from flies, and the endogenous proteins were found to colocalize at the tracheal cell surface in larvae. When NijA is expressed in S2 cells, they lose adhesion to surfaces; this adhesion-loss phenotype is dependent on the expression and catalytic activity of Mmp1. Our data indicate that Mmp1 releases the N-terminal extracellular domain of NijA. This liberated ectodomain promotes the loss of cell adhesion in a cell-nonautonomous manner. We suggest that tracheal cell adhesion is regulated by a novel mechanism utilizing an MMP and a ninjurin family member.

Comparison of tracheal tube cuff diameters with internal transverse diameters of the trachea in children

In this study, we evaluated the ratio of the cuff diameters of the Microcuff paediatric tracheal tube (Microcuff PET, Weinheim, Germany) to fluoroscopically measured internal transverse tracheal diameters in children from birth to adolescence. With Institutional Ethics Committee approval and parental consent, we measured the internal transverse tracheal diameters from fluoroscopy images in children undergoing cardiac catheterization requiring general anaesthesia with oro-tracheal intubation. Minimal tracheal sealing pressures were assessed at standardized respirator settings. Internal transverse tracheal diameters were compared with cuff diameters at 20 cmH2O cuff pressure. Linear regression analysis was employed to assess the correlation of tracheal diameters with age, height and weight, and to assess the correlation of the cuff/tracheal diameter ratio with sealing pressures. For all tests, P < 0.05 was considered to be statistically significant. One hundred and forty-five patients were studied (62 girls; 83 boys). Transverse tracheal diameters correlated well with age (r = 0.890; P < 0.0001), height (r = 0.900; P < 0.0001) and weight (r = 0.882; P < 0.0001). Tracheal sealing pressures ranged from 4 to 18 cmH2O. The ratio of the tracheal tube cuff diameter to the internal transverse tracheal diameter ranged from 1.06 in tubes with internal diameters of 6.0 and 4.5 mm to 2.01 in a tube with an internal diameter of 3.5 mm (median, 1.43), and did not correlate with tracheal sealing pressures (r = 0.021, P = 0.7999). The residual diameters of the Microcuff paediatric tracheal tube cuffs were sufficient to cover the measured internal transverse tracheal diameters of children from birth to adolescence. This allowed the internal tracheal mucosal surface to be draped and the trachea to be sealed at very low cuff pressures.

Mechanisms of mucin production by rhinovirus infection in cultured human airway epithelial cells

Mucus hypersecretion relates to exacerbations of bronchial asthma and chronic obstructive pulmonary disease (COPD) caused by rhinovirus (RV) infection. We examined the mechanisms of RV infection-induced mucin production in human tracheal surface epithelial cells and submucosal gland cells. RV14 up-regulated the mRNA expression of MUC2, MUC3, MUC5AC, MUC5B and MUC6, and increased MUC5AC and total mucin concentration in supernatants and lysates of the surface cells. An inhibitor of the nuclear factor kappaB caffeic acid phenylethyl ester, inhibitors of selective p44/42 mitogen-activated protein kinase-kinase PD98059 and U0126, and a selective Src inhibitor PP1 attenuated MUC5AC mRNA expression, and secretion and production of MUC5AC and total mucin glycoprotein in the surface cells. In the gland cells, RV14 also increased mRNA expression of MUC2, MUC5AC, MUC5B and MUC7, and the inhibitors attenuated the secretion of total mucin glycoprotein. Src-related p44/42 mitogen-activated protein kinase pathway may be associated with RV-induced mucin hypersecretion in human airways.

Hyperacidity of secreted fluid from submucosal glands in early cystic fibrosis

Prior studies have shown that fluid secretions from airway submucosal glands in cystic fibrosis (CF) are reduced and hyperviscous, possibly contributing to the pathogenesis of CF airway disease. Because the CF transmembrane conductance regulator (CFTR) protein can transport both chloride and bicarbonate, we investigated whether gland fluid pH is abnormal in early CF, using nasal biopsies from pediatric subjects having minimal CF lung disease. Gland fluid pH, measured in freshly secreted droplets under oil stained with BCECF-dextran, was 6.57 +/- 0.09 (mean +/- SE) in biopsies from six CF subjects, significantly lower than 7.18 +/- 0.06 in eight non-CF biopsies (P < 0.01). To rule out the possibility that the apparent gland fluid hyperacidity in CF results from modification of fluid pH by the airway surface, a microcannulation method was used to measure pH in fluid exiting gland orifices. In pig trachea and human bronchi, gland fluid pH was reduced by up to 0.45 units by CFTR inhibitors, but was not affected by amiloride. Acid base transport in the surface epithelium of pig trachea was studied from pH changes in 300-nl fluid droplets deposited onto the oil-covered airway surface. The droplets had specified ionic composition/pH and/or contained transporter activators/inhibitors. We found evidence for CFTR-dependent bicarbonate transport by the tracheal surface epithelium as well as ATP/histamine-stimulated proton secretion, but not for sodium/proton or chloride/bicarbonate exchange. These results provide evidence for intrinsic hyperacidity in CF gland fluid secretions, which may contribute to CF airway pathology.

Ultrastructural Changes of the Tracheal Epithelium after Vaccination of Day-Old Chickens with the La Sota Strain of Newcastle Disease Virus

The progression of tracheal lesions induced by vaccination of day-old specific pathogen-free chicks with the La Sota strain of Newcastle disease virus (NDV) was examined by relating surface changes as observed by scanning electron microscopy with subcellular changes seen by transmission electron microscopy. NDV infection resulted in hypertrophy of goblet cells, their rupture, and the formation of excess mucus. Activation of goblet cells peaked within 4 days postvaccination. Afterward, the activation levels gradually decreased. At the level of the ciliated cells, a marked increase in the proportion of nonciliated to ciliated cells and later an almost complete deciliation of the tracheal surface were observed because a simple squamous to cuboidal epithelium replaced the original pseudostratified epithelium. Fifteen days postvaccination, all epithelial damage was restored. Because the observed vaccination-induced lesions are detrimental to epithelial integrity and function as a barrier against invading microorganisms, they might explain at the ultrastructural level the secondary complications of vaccination with the La Sota strain against NDV.

Regenerative Medicine of the Trachea: The First Human Case

The objective of the present study was to demonstrate regenerative medicine of the tracheal tissue by using an in situ tissue engineering technique for airway reconstruction. Based on the previous successful experimental animal studies, the current regenerative technique was applied to repair of the trachea of a 78-year-old woman with thyroid cancer. A Marlex mesh tube covered by collagen sponge was used as a tissue scaffold. The operative intervention included right hemithyroidectomy, resection of the trachea, and tracheoplasty using the scaffold. The right half of three rings of the trachea was resected, and the scaffold material was sutured to the defect of the trachea. After 2 weeks, the mesh collagen structure of the artificial material could be seen with endoscopy in most of the implanted area. The artificial material was covered with epithelial growth after 2 months. Epithelialization continued to cover the artificial material completely for 2 years without any complications. The current regenerative technique avoided tracheotomy, a second operation, and deformity. Good epithelialization has been observed on the tracheal luminal surface without any complications for 2 years. Although long-term observation is required, regenerative medicine of the tracheal tissue appears feasible for airway reconstruction.

Effects of Ursolic Acid, Betulin and Sulfur-Containing Compounds on Mucin Release from Airway Goblet Cells

In this study, we investigated whether ursolic acid, betulin and 2 kinds of sulfur-containing compounds--NAC and MESNA--affect mucin release from airway goblet cells and compared the possible activities of these agents with the inhibitory action on mucin release by PLL and the stimulatory action by ATP. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using 3H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on 3H-mucin release. The results were as follows: ursolic acid, betulin, MESNA and NAC increased mucin release (40-50 % above control) at the highest concentrations (10(-5) M-10(-3) M). We conclude that ursolic acid and betulin can stimulate mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further investigated for the possible use as mucoregulators in the treatment of chronic airway diseases.

Effects of dexamethasone on Muc5ac mucin production by primary airway goblet cells.

Mucus hypersecretion associated with airway inflammation is reduced by glucocorticoids. Two mechanisms of glucocorticoid-mediated inhibition of mucus production have been proposed, direct inhibition of mucus production by airway epithelial cells and indirectly through inhibition of proinflammatory mediators that stimulate mucus production. In this study, we examined the effect of dexamethasone (DEX) on mRNA expression and synthesis of MUC5AC by A549 human lung adenocarcinoma cells as well as Muc5ac and total high-molecular-weight (HMW) mucins by primary rat tracheal surface epithelial (RTSE) cells. Our results showed that in primary RTSE cells, DEX 1) dose dependently suppressed Muc5ac mRNA levels, but the levels of cellular Muc5ac protein and HMW mucins were unaffected; 2) did not affect constitutive or UTP-stimulated mucin secretion; 3) enhanced the translation of Muc5ac; and 4) increased the stability of intracellular Muc5ac protein by a mechanism other than the inhibition of the proteasomal degradation. In A549 cells, however, DEX suppressed both MUC5AC mRNA levels and MUC5AC protein secretion in a dose-dependent manner. We conclude that whereas DEX inhibits the levels of Muc5ac mRNA in primary RTSE cells, the levels of Muc5ac protein remain unchanged as a consequence of increases in both translation and protein stability. Interestingly, some of the effects of DEX were opposite in a cell line.

Effects of betaine, coumarin and flavonoids on mucin release from cultured hamster tracheal surface epithelial cells.

Betaine, coumarin, hesperidin and kaempferol are the components derived from Lycium chinense, Angelicae decursiva, Poncirus trifoliata and Polygonatum odoratum, respectively. These plants have been used for the treatment of respiratory diseases in oriental medicine and their respective components were reported to have various biological effects. In this study, we investigated whether these natural products affect mucin release from cultured hamster tracheal surface epithelial cells and compared the possible activities of these agents with the inhibitory action on mucin release by poly-L-lysine and the stimulatory action by adenosine triphosphate. Confluent primary hamster tracheal surface epithelial cells were metabolically radiolabeled using (3)H-glucosamine for 24 h and treated for 30 min in the presence of varying concentrations of each agent to assess the effects on (3)H-mucin release. The results were as follows: (i) Coumarin and kaempferol did not affect mucin release significantly; (ii) Betaine and hesperidin increased mucin release at the highest concentration; (iii) Poly-L-lysine inhibited and adenosine triphosphate increased mucin release. We conclude that betaine and hesperidin can increase mucin release by direct acting on airway mucin-secreting cells and suggest these agents be further studied for the possible use as mild expectorants during the treatment of chronic airway diseases.

Infection of the turkey embryonic trachea with Mycoplasma meleagridis

Mycoplasma meleagridis was used to infect turkey embryos and tracheal explants. In the embryonic trachea, there was a decrease in the number of cilia and the sloughing of epithelial cells. In the tracheal explants, thedeciliation was more severe and erosion of the tracheal surface was also evident; additionally, the cells of the trachea showed prominent perforation. These results indicate that M. meleagridis infection can result in damageto cells and to the surface of the trachea, which may have pathological consequences.

Effects of baicalein, berberine, curcumin and hesperidin on mucin release from airway goblet cells.

Baicalein, berberine, curcumin and hesperidin are the major components derived from Scutellaria baicalensis, Coptis japonica, Curcuma longa and Poncirus trifoliata, respectively. These plants have been used for the treatment of diverse chronic inflammatory diseases including respiratory disease in oriental medicine and their respective major components were reported to have various biological effects including anti-inflammatory activity. In the present study, we investigated whether these four natural products affect mucin release from airway goblet cells and compared the possible activities of these agents with the inhibitory action on mucin release by PLL and the stimulatory action by ATP. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using 3H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on 3H-mucin release. The results were as follows: (i) baicalein did not affect mucin release significantly; (ii) berberine, curcumin and hesperidin increased mucin release at the highest concentration (10 - 4 M); (iii) PLL inhibited and ATP increased mucin release. We conclude that berberine, curcumin and hesperidin can increase mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further studied for possible use as mild expectorants during the treatment of chronic airway diseases. Abbreviations. PLL:poly- L-lysine ATP:adenosine triphosphate HTSE:hamster tracheal surface epithelial DMSO:dimethylsulfoxide IL-12:interleukin-12 PBS:phosphate-buffered saline

Effects of activation of polymorphonuclear leukocytes on airway goblet cell mucin release in a co-culture system.

Effects of activated PMN on airway goblet cell mucin release were investigated using a co-culture system in which both tracheal surface epithelial (TSE) cells and PMN from hamsters were present. TSE cells were metabolically labeled using (3)H-glucosamine and chased in the presence of PMN under various experimental designs. PMN were obtained from the bronchoalveolar lavage fluid of hamsters following intratracheal instillation of E. coli endotoxin. The amount of (3)H-mucin was measured by Sepharose CL-4B gel-filtration column chromatography. (i). activation of 10(6) PMN by fMLP (0.1 microM) and cytochalasin B (0.1 microM) resulted in production of both the estrolytic ("elastolytic") activity and superoxide, (ii). activation of PMN in the co-culture stimulated mucin release from TSE cells followed by a significant degradation of the released mucins, both of which were blocked in a dose-dependent fashion by pretreatment with alpha1-protease inhibitor, and (iii). generation of varying concentrations of superoxide in the TSE cell culture did not affect mucin release from TSE cells. In the co-culture system, activation of PMN results in release and degradation of mucins, both of which are almost entirely accounted for by serine proteases but not other cellular products such as superoxide.

Scanning electron microscopic studies of Mycoplasma gallisepticum infection in embryonic tracheae.

Mycoplasma gallisepticum (MG) was used to infect chicken embryos, and scanning electron microscopy was used to examine the morphologic changes in the tracheae. Tracheae harvested from embryos infected with MG for 5 days showed extensive deciliation, surface erosion, and inflammatory cell infiltration. Embryonic tracheal explants infected with MG for 6 hr showed the same deciliation and surface erosion. The damage to the tracheal surface caused by MG at the embryonic stage might play a role in the pathogenesis of MG infection.

Effects of polycationic peptides on mucin release from airway goblet cells: relationship between polymer size and activity.

Various sizes of poly-L-lysine (PLL) and poly-L-arginine (PLA) were tested for their possible effects on airway goblet cell mucin release using primary hamster tracheal surface epithelial (HTSE) cells in an attempt to identify the smallest size of the polycationic peptide to suppress mucin release without cytotoxicity. HTSE cells were metabolically labeled using 3H-glucosamine and chased in the presence of varying concentrations of various sizes of the polycationic peptides. The amount of 3H-mucin in the spent media was measured by Sepharose CL-4B gel-filtration column chromatography. Possible cytotoxicity of the peptides was assessed by measuring the release of lactic dehydrogenase (LDH) during the treatment period. (1) PLL (MW 78,000) inhibited whereas PLA (MW 92,000) stimulated mucin release. However, these peptides were cytotoxic at the effective concentrations; (2) Both PLL (MW 9,600) and PLA (MW 8,900) could inhibit mucin release in a dose dependent manner without cytotoxicity; (3) Both PLL and PLA were effective in suppressing mucin release in 20-mer but not in either 10-mer or 5-mer; (4) 14-mers of both PLL and PLA also inhibited mucin release without cytotoxicity; (5) PLL and poly-D-lysine (PDL) of 14-mer were equipotent in its ability to suppress mucin release. Both PLL and PLA are cytotoxic at 'high' molecular weights, but have an ability to suppress mucin release without cytotoxicity at 'low' molecular weights. 14-mer seems to be the small, effective size, if not the smallest, for both PLL and PLA to suppress mucin release without cytotoxicity. The inhibitory effect of these polycationic peptides seems to be determined by the presence and the absolute number of positive charges and also to be independent of optical isomerism.

Indices of antioxidant status in rats subjected to wood smoke inhalation and/or thermal injury

The present study investigated antioxidant status in lavage fluid, lung, liver, heart and kidney in a rat model to simulate an inhalation injury as might be encountered by firefighters and burn victims. Anesthetized rats received either a 20% total body surface area (TBSA) full thickness scald or a sham burn. After a 5 h recovery period, half of the animals in the burn or sham burn groups were exposed to cooled western bark (fir and pine) smoke for 16.25 min. The remaining rats in each group breathed room air. At 1, 12, 24, 48 and 96 h after exposure to the smoke, five rats from each of the four groups were euthanatized and lungs were lavaged by infusing three 5 ml aliquots of normal saline for evaluation of airway cellular content and lung wet to dry weight ratios to estimate lung water content. A second series of five rats/group per time point were euthanatized at the above times and lung, liver, kidney and heart were removed for evaluation of tissue antioxidant enzyme activities and for thiobarbituric acid reactive substances (TBARS) concentrations, as well as for lung histology. Smoke exposure resulted in average plasma carboxyhemoglobin (COHb) of 19±2% in the two smoke exposed groups and produced areas of erosion of the tracheal surface, resulting in loss of epithelium and exposed basement membrane. Lung water content was not significantly different among the four groups during the 96-h experimental period. Lung TBARS levels were 2–3-fold higher at 12 h in smoke exposed rats compared with controls. These levels peaked at 24 h and remained significantly elevated at 48 h compared to controls. TBARS were also elevated in liver, but not in heart or kidney in response to burn or combined injury. Minor effects on lung antioxidant enzyme activities were observed after smoke inhalation. These data suggest that smoke inhalation, independent of burn injury, induces an oxidant stress that persists for at least the first 48 h after smoke exposure.

Pharmacologically induced relaxation of tracheal smooth muscle is increased in hyperoxia-exposed 15-day-old rats.

Hyperoxia increases maximum airway contractility in newborn guinea pigs and immature rats. Studies examining the mechanisms of hyperoxia-induced airway hyperresponsiveness have focused on contractile mechanisms, although excessive airway narrowing could be due to impaired relaxation. Our objective was to determine the effects of hyperoxia on airway structure and relaxing properties in juvenile rats exposed to an inspired fraction of oxygen (FiO(2)) of 0.5 within 24 hr of birth for 15 days, compared to a control group of air-exposed rats. We studied the 1) tracheal smooth muscle surface area; and 2) in vitro relaxation in precontracted (carbachol, 1.10(-3) M) isolated tracheal rings to increasing cumulative concentrations (10(-8) to 10(-4) M) of salbutamol. There was no significant difference in the amount of smooth muscle between the hyperoxia and air-exposed groups. Maximal relaxation of the isolated trachea to salbutamol was greater in the hyperoxia group than in the air-exposed group when normalized to smooth muscle surface area (-12.69 +/- 3.51 g/mm(2) vs. - 8.49 +/- 1.67 g/mm(2); P (MANOVA) < 0.05) or expressed as maximal relaxation induced by 10(-3) M theophylline (61% vs. 28%; P < 0.05). In conclusion, salbutamol-induced relaxation is enhanced (and not impaired) in newborn rats exposed to prolonged moderate hyperoxia.

Airway changes in children with mucopolysaccharidoses.

To assess the CT findings of the airway in children with mucopolysaccharidoses (MPS). The study included 13 patients (9 boys, 4 girls; age range 2-17 years; mean age 9.2 years) with MPS: 6 with Hunter syndrome, 3 with Maroteaux-Lamy syndrome, 2 with Sanfilippo syndrome, 1 with Hurler/Scheie syndrome and 1 with Morquio syndrome. CT of the airways was done in the axial section with 3-mm collimation from the oropharynx at the level of C3 to the base of the lung. The shape of the vocal cords and trachea at the level of T1 was evaluated. The tracheal surface area (TSA) at the level of T1 was measured both in patients and in age-matched subjects. CT showed an abnormality of the vocal cords in 7 of the 13 patients. Six patients had an abnormal shape and 7 had an inhomogenous density. The abnormalities included elliptical (5 of 6) and star-shaped (1 of 6) cords. Eight of 13 tracheas were also abnormal, either U-shaped (6 of 8) or worm-shaped (2 of 8). The TSA was significantly smaller in patients (79.6+/-28.9 mm2) than in control subjects (138.1+/-50.1 mm2). The TSA of those < or =9 years was 61.4+/-15.2 mm2 as compared with 99.9+/-23.5 mm2 for the control group. The TSA of patients > or =11 years was 107.1+/-25.3 mm2 as compared with 187.6+/-32.0 mm2 for the control group. Significant changes in the shape of the vocal cords and trachea in patients with MPS were found. The most common abnormal configuration of trachea was the U-shape. The TSA was smaller in patients with MPS than in controls. The airway changes may be due to abnormal submucosal storage of substances such as keratan or dermatan sulfate.

Airway changes in children with mucopolysaccharidoses. CT evaluation

To assess the CT findings of the airway in children with mucopolysaccharidoses (MPS). The study included 13 patients (9 boys, 4 girls; age range 2-17 years; mean age 9.2 years) with MPS: 6 with Hunter syndrome, 3 with Maroteaux-Lamy syndrome, 2 with Sanfilippo syndrome, 1 with Hurler/Scheie syndrome and 1 with Morquio syndrome. CT of the airways was done in the axial section with 3-mm collimation from the oropharynx at the level of C3 to the base of the lung. The shape of the vocal cords and trachea at the level of T1 was evaluated. The tracheal surface area (TSA) at the level of T1 was measured both in patients and in age-matched subjects. CT showed an abnormality of the vocal cords in 7 of the 13 patients. Six patients had an abnormal shape and 7 had an inhomogenous density. The abnormalities included elliptical (5 of 6) and star-shaped (1 of 6) cords. Eight of 13 tracheas were also abnormal, either U-shaped (6 of 8) or worm-shaped (2 of 8). The TSA was significantly smaller in patients (79.6+/-28.9 mm2) than in control subjects (138.1+/-50.1 mm2). The TSA of those < or =9 years was 61.4+/-15.2 mm2 as compared with 99.9+/-23.5 mm2 for the control group. The TSA of patients > or =11 years was 107.1+/-25.3 mm2 as compared with 187.6+/-32.0 mm2 for the control group. Significant changes in the shape of the vocal cords and trachea in patients with MPS were found. The most common abnormal configuration of trachea was the U-shape. The TSA was smaller in patients with MPS than in controls. The airway changes may be due to abnormal submucosal storage of substances such as keratan or dermatan sulfate.