Characterization of mucins in human middle ear and Eustachian tube

Mucins are important glycoproteins in the mucociliary transport system of the middle ear and Eustachian tube. Little is known about mucin expression within this system under physiological and pathological conditions. This study demonstrated the expression of MUC5B, MUC5AC, MUC4, and MUC1 in the human Eustachian tube, whereas only MUC5B mucin expression was demonstrated in noninflamed middle ears. MUC5B and MUC4 mucin genes were upregulated 4.2- and 6-fold, respectively, in middle ears with chronic otitis media (COM) or mucoid otitis media (MOM). This upregulation of mucin genes was accompanied by an increase of MUC5B- and MUC4-producing cells in the middle ear mucosa. Electron microscopy of the secretions from COM and MOM showed the presence of chainlike polymeric mucin. These data indicate that the epithelium of the middle ear and Eustachian tube expresses distinct mucin profiles and that MUC5B and MUC4 mucins are highly produced and secreted in the diseased middle ear. These mucins may form thick mucous effusion in the middle ear cavity and compromise the function of the middle ear.     

儿童腺样体肥大程度与分泌性中耳炎发生的相关性研究(英文)

目的:探讨儿童腺样体肥大程度与分泌性中耳炎发生及预后的相关性,指导临床医师对分泌性中耳炎作出早期诊断和治疗。方法:239例住院手术切除腺样体的儿童,常规行鼻咽侧位片、声导抗检查;部分伴耳部症状、声导抗显示C型曲线或查体可疑鼓室积液征者行颞骨CT检查或术中行鼓室穿刺。经统计学分析,比较分泌性中耳炎与腺样体肥大程度及咽鼓管咽口情况的相关性。结果:在239例腺样体肥大儿童中,经鼓室穿刺证实合并分泌性中耳炎者34例(63耳,14.2%),其中鼓室曲线呈B型者33耳(52.4%),C型(-200 dapa)者10耳(15.9%),C型(-200 dapa)者20耳(31.7%)。结果表明分泌性中耳炎的发生与腺样体肥大程度及咽鼓管园枕受压迫的程度呈正相关。结论:声导抗检查不能作为分泌性中耳炎诊断的金标准,必要时可行颞骨CT明确诊断;对腺样体肥大伴分泌性中耳炎的儿童鼻内镜下腺样体切除为其主要疗法,配合鼓室穿刺多可治愈,对反复发作的分泌性中耳炎行鼓室置管术,避免术后并发症的发生。     

Expression and localization of lung surfactant protein B in Eustachian tube epithelium

Surfactant protein (SP) B is an essential component of the pulmonary surfactant complex, which participates in reducing the surface tension across the alveolar air-liquid interface. The Eustachian tube (ET) connects the upper respiratory tract to the middle ear, serving as an intermittent airway between the pharynx and the middle ear. Recently, we described the expression of SP-A and SP-D in the ET, suggesting their role in middle ear host defense. Our present aim was to detect whether the expression of SP-B is evident in the porcine ET. With Northern blot analysis, RT-PCR, and in situ hybridizations, SP-B mRNA was identified and localized in the ET epithelium. The cellular localization of SP-B was revealed with immunohistochemistry, electron microscopy, and immunoelectron microscopy. The protein was found in the secretory granules of epithelial cells and also attached to the microvilli at the luminal side of these cells. The SP-B immunoreactivity of aggregates isolated from ET lavage fluid was similar to that isolated from bronchoalveolar lavage fluid. We conclude that there are specialized cells in the ET epithelium expressing and secreting SP-B and propose that SP-B may facilitate normal opening of the tube and mucociliary transport.     

Otitis Media in Sperm-Associated Antigen 6 (Spag6)-Deficient Mice

Mammalian SPAG6 protein is localized to the axoneme central apparatus, and it is required for normal flagella and cilia motility. Recent studies demonstrated that the protein also regulates ciliogenesis and cilia polarity in the epithelial cells of brain ventricles and trachea. Motile cilia are also present in the epithelial cells of the middle ear and Eustachian tubes, where the ciliary system participates in the movement of serous fluid and mucus in the middle ear. Cilia defects are associated with otitis media (OM), presumably due to an inability to efficiently transport fluid, mucus and particles including microorganisms. We investigated the potential role of SPAG6 in the middle ear and Eustachian tubes by studying mice with a targeted mutation in the Spag6 gene. SPAG6 is expressed in the ciliated cells of middle ear epithelial cells. The orientation of the ciliary basal feet was random in the middle ear epithelial cells of Spag6-deficient mice, and there was an associated disrupted localization of the planar cell polarity (PCP) protein, FZD6. These features are associated with disordered cilia orientation, confirmed by scanning electron microscopy, which leads to uncoordinated cilia beating. The Spag6 mutant mice were also prone to develop OM. However, there were no significant differences in bacterial populations, epithelial goblet cell density, mucin expression and Eustachian tube angle between the mutant and wild-type mice, suggesting that OM was due to accumulation of fluid and mucus secondary to the ciliary dysfunction. Our studies demonstrate a role for Spag6 in the pathogenesis of OM in mice, possibly through its role in the regulation of cilia/basal body polarity through the PCP-dependent mechanisms in the middle ear and Eustachian tubes.     

Treatment of Middle Ear Ventilation Disorders: Sheep as Animal Model for Stenting the Human Eustachian Tube – A Cadaver Study

Eustachian tube disorders can lead to chronic otitis media with consecutive conductive hearing loss. To improve treatment and to develop new types of implants such as stents, an adequate experimental animal model is required. As the middle ear of sheep is known to be comparable to the human middle ear, the dimensions of the Eustachian tube in two strains of sheep were investigated. The Eustachian tube and middle ear of half heads of heathland and blackface sheep were filled with silicone rubber, blended with barium sulfate to induce X-ray visibility. Images were taken by digital volume tomography. The tubes were segmented, and a three-dimensional model of every Eustachian tube was generated. The lengths, diameters and shapes were determined. Additionally, the feasibility of endoscopic stent implantation and fixation was tested in cadaver experiments. The length of the tube between ostium pharyngeum and the isthmus and the diameters were comparable to published values for the human tube. The tube was easily accessible through the nose, and then stents could be implanted and fixed at the isthmus. The sheep appears to be a promising model for testing new stent treatments for middle ear ventilation disorders.     

The epithelium of the middle ear in the guinea pig

Summary An electron microscopic study of aldehyde and osmium fixed normal guinea pig middle ear epithelium was made. Numerous branching microvilli occur between the cilia of the ciliated cells. The granules of the secretory cells are always surrounded by a membrane, and they vary in their content of electron dense substance. Half desmosomes are frequent in basal cells. The squamous epithelial cells of the bulla contain few microvilli and pinocytoric invaginations. In the basal part of the squamous epithelium dilations of the intercellular clefts often occur. The luminal part of the intercellular clefts are closed by multiple tight junctions.     

Ectopic mineralization in the middle ear and chronic otitis media with effusion caused by RPL38 deficiency in the Tail-short (Ts) mouse

Inflammation of the middle ear cavity (otitis media) and the abnormal deposition of bone at the otic capsule are common causes of conductive hearing impairment in children and adults. Although a host of environmental factors can contribute to these conditions, a genetic predisposition has an important role as well. Here, we analyze the Tail-short (Ts) mouse, which harbors a spontaneous semi-dominant mutation that causes skeletal defects and hearing loss. By genetic means, we show that the Ts phenotypes arise from an 18-kb deletion/insertion of the Rpl38 gene, encoding a ribosomal protein of the large subunit. We show that Ts mutants exhibit significantly elevated auditory-brain stem response thresholds and reduced distortion-product otoacoustic emissions, in the presence of normal endocochlear potentials and typical inner ear histology suggestive of a conductive hearing impairment. We locate the cause of the hearing impairment to the middle ear, demonstrating over-ossification at the round window ridge, ectopic deposition of cholesterol crystals in the middle ear cavity, enlarged Eustachian tube, and chronic otitis media with effusion all beginning at around 3 weeks after birth. Using specific antisera, we demonstrate that Rpl38 is an ～8-kDa protein that is predominantly expressed in mature erythrocytes. Finally, using an Rpl38 cDNA transgene, we rescue the Ts phenotypes. Together, these data present a previously uncharacterized combination of interrelated middle ear pathologies and suggest Rpl38 deficiency as a model to dissect the causative relationships between neo-ossification, cholesterol crystal deposition, and Eustachian tubes in the etiology of otitis media.     

Development of mucociliary transport in the postnatal ferret trachea.

Little is known of the developmental aspects of mucociliary transport. Previous studies have documented that newborn ferret trachea has very few ciliated cells but numerous immature secretory cells in the epithelium and only rudimentary submucosal glands. Rapid and complete maturation occurs in the first postnatal month. This study examines mucociliary transport during this period of rapid maturation. We made direct observations of particle movement across the epithelium of ferret tracheas. No mucus transport could be demonstrated on the first day of life. Transport was discernible, although sporadic and slow, by 7 days and reached adult levels (10.7 +/- 3.7 mm/min) by 28 postnatal days. The emergence of transport capability correlated well with previously described developmental changes in ciliation, mucus secretion, and ion permeability and transport. Threshold mucus transport occurred at 1 wk of age when 20-25% of the surface cells are ciliated. The neonatal ferret appears to be a useful model for assessing integrated epithelial structure-function relationships that are important not only during early development but also during repair after airway injury involving deciliation.     

Surfactant proteins A and D in Eustachian tube epithelium

Surfactant protein (SP) A and SP-D are collectins that have roles in host defense. The Eustachian tube (ET) maintains the patency between the upper airways and the middle ear. Dysfunction of local mucosal immunity in ET may predispose infants to recurrent otitis media. We recently described preliminary evidence of the expression of SP-A and SP-D in the ET. Our present aim was to establish the sites of SP-A and SP-D expression within the epithelium of the ET in vivo. With in situ hybridization, electron microscopy, and immunoelectron microscopy, the cells responsible for SP-A and SP-D expression and storage were identified. SP-A expression was localized within the ET epithelium, and the protein was found in the electron-dense granules of microvillar epithelial cells. Being concentrated in the epithelial lining, only a few cells revealed intracellular SP-D, and it was not associated with granules. The SP-A and SP-D immunoreactivities in ET lavage fluid, as shown by Western blot analyses, were similar to those in bronchoalveolar lavage fluid. We propose that there are specialized cells in the ET epithelium expressing and secreting SP-A and SP-D. SP-A and SP-D may be important for antibody-independent protection of the middle ear against infections.     

The presence of a lipoma in the Eustachian tube: a case report

ABSTRACT: INTRODUCTION: The incidence of lipoma in the Eustachian tube is very rare, and to the best of our knowledge, has not been reported in the literature. Tumors that form in the cartilaginous portion of the Eustachian tube can be successfully removed by an endoscopic approach. CASE PRESENTATION: We report an incidentally-detected lipoma of the Eustachian tube in a 34-year-old Asian woman with a six-year history of persistent otitis media in her right ear. Our patient underwent surgery five years ago for the possibility of a choanal polyp, but her ear symptoms continued to be problematic following the surgery. Our patient was examined at our hospital, and computed tomography revealed a well-defined, hypodense, non-enhancing lesion involving the right Eustachian tube, measuring 1.6x2.4cm. The mass was excised using an endoscopic approach, and was found to originate from the cartilaginous portion of the Eustachian tube. The tumor was sent for histopathologic evaluation. The postoperative course went smoothly, and our patient recovered during follow-up over the next five months. CONCLUSION: Lipoma of the Eustachian tube is very rare compared with other tumors. Improved radiologic modalities aid the diagnosis of this benign tumor. Endoscopic removal of the tumor is possible and has helped in early recovery.     

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.     

地氯雷他定联合地塞米松鼓室内注射对分泌性中耳炎患者咽鼓管功能的影响

目的:观察地氯雷他定联合地塞米松鼓室内注射治疗分泌性中耳炎的效果及对咽鼓管功能的影响。方法:选择我院2013年6月-2014年6月收治的分泌性中耳炎患者116例,随机分为两组,对照组采用地塞米松鼓室内注射治疗,观察组在此基础上加服地氯雷他定。观察并比较两组临床疗效及咽鼓管功能的恢复情况。结果:治疗后,两组咽鼓管功能不良率较治疗前明显降低(P0.05),观察组咽鼓管功能恢复率高于对照组,观察组治疗前后气骨导差差值明显大于对照组(P0.05),观察组在治疗后1周及1月的总有效率均高于对照组(P0.05)。结论:地氯雷他定联合地塞米松鼓室内注射可减少渗出和中耳积液潴留,有效改善分泌性中耳炎患者的咽鼓管功能,促进听力恢复。     

Studies on the ultrastructure of the Fallopian tube: Part II. Changes in the secretory cells of the rabbit Fallopian tube during ovum transport

The ultrastructural changes that occur in the ciliated cells of the tubal epithelium of the adult rabbit during ovum transport were previously reported. In this communication, the changes that occur in the secretory cells of the tube under identical conditions are described. Estrous and pregnant rabbits were used. 14-70 hours postcoitum the size and shape of the microvilli of the ampullar cells differed from the isthmic ones. The prominence of the microvilli was roughly correlated with the possible arrival of the ovum in any part of the tube. The secretory granules in the cells of the ampulla were more electron dense than those in the isthmus. With the progress of the post ovulatory period, the secretory granules changed in nature and location. During the postovulatory period, the secretory process in both parts of the tube indicate a "merocrine" type of secretion. A cilium was occasionally present in the luminal epithelium of a secretory cell. Hybrid cells may arise when a cell malfunctions while receiving a set of messages from the nucleus at the time appropriate for cell differentiation.     

The multifunctional host defense peptide SPLUNC1 is critical for homeostasis of the mammalian upper airway

Otitis media (OM) is a highly prevalent pediatric disease caused by normal flora of the nasopharynx that ascend the Eustachian tube and enter the middle ear. As OM is a disease of opportunity, it is critical to gain an increased understanding of immune system components that are operational in the upper airway and aid in prevention of this disease. SPLUNC1 is an antimicrobial host defense peptide that is hypothesized to contribute to the health of the airway both through bactericidal and non-bactericidal mechanisms. We used small interfering RNA (siRNA) technology to knock down expression of the chinchilla ortholog of human SPLUNC1 (cSPLUNC1) to begin to determine the role that this protein played in prevention of OM. We showed that knock down of cSPLUNC1 expression did not impact survival of nontypeable Haemophilus influenzae, a predominant causative agent of OM, in the chinchilla middle ear under the conditions tested. In contrast, expression of cSPLUNC1 was essential for maintenance of middle ear pressure and efficient mucociliary clearance, key defense mechanisms of the tubotympanum. Collectively, our data have provided the first in vivo evidence that cSPLUNC1 functions to maintain homeostasis of the upper airway and, thereby, is critical for protection of the middle ear.     

On the structure of the pulmonate osphradium

Summary The osphradium of Planorbarius consists of a blindly-ending ciliated canal, formed by an infolding of the mantle epithelium, and a basal ganglion of nerve cells which is comparable in complexity with ganglia of the central nervous system. The distribution of cell types in the osphradial epithelium is specialised so that three regions can be recognised; the ciliated, the secretory and the sensory regions. The basal sensory region of the canal epithelium consists of ciliated cells and is innervated by sensory neurones of the osphradial ganglion. The middle secretory region contains mainly of mucus-secreting cells and the epithelium adjacent to the osphradial aperture of ciliated cells and secretory cells of a second type. The sensory neurones of the osphradial ganglion are bipolar or of a modified monopolar type. Other monopolar neurones, similar to those common in the central nervous system are of non-sensory function. The osphradium of Paludina, although of typical prosobranch form, possesses ciliated pits similar to the single canal of Planorbarius, which may indicate a shared modality of receptor function. A definite function cannot be ascribed to the pulmonate osphradium based on morphological evidence alone.     

Intermediate epithelium lining the mouse auditory tube

In the newborn mouse, the auditory tube is lined throughout the pharyngeal orifice to the tympanic orifice with ciliated columnar epithelium. In the adult mouse, the tube is divided into membranous and cartilaginous parts. The membranous part is covered by the ciliated columnar epithelium, while the cartilaginous part by varying types of epithelium ranging from ciliated columnar to stratified squamous type. It is suggested that the varying types of epithelium correspond to the 'intermediate epithelium', and that ciliated columnar epithelium transforms in part to stratified squamous epithelium by passing through the intermediate epithelium.     

Heterogeneity of glycoconjugates in the secretory cells of the chinchilla middle ear and eustachian tubal epithelia: a lectin-gold cytochemical study

The present study was conducted to characterize and localize the glycoconjugates in the tubotympanum (auditory or eustachian tube and middle ear cavity) of chinchilla on an ultrastructural level, using lectin-gold complexes with six different lectins: BPA, ConA, RCA-1, WGA, LFA, and SNA. A comparison of the affinity of these lectins demonstrated the heterogeneity of secretory cells. The glandular serous cells and epithelial dark granulated cells produced "serum"-type glycoprotein. The glandular mucous cells and goblet cells produced dominantly "mucin"-type glycoprotein in the light granules, but "serum"-type glycoprotein in the dark cores. The labeling of LFA and SNA showed that sialic acids existed mainly in the mucinous granules of secretory cells and ciliated epithelium glycocalyx, and in the mucous blanket. The results also suggested that the dominant linkage of sialic acids of mucin is a Neu5Ac(alpha 2-6)Gal/GalNAc sequence. Furthermore, the data obtained from ConA and BPA suggested that initial O-glycosylation of mucin took place in the cis side of the Golgi apparatus and that initial N-glycosylation of the serum occurred in the rough endoplasmic reticulum.     

Newt lungs: a versatile system for the study of mucociliary transport

Lungs of the newt, Taricha granulosa, provide a versatile system for studying mucociliary transport. The mucociliary epithelium is restricted to a ventral strip of epithelium which extends the entire length of the lung. The transport process can be studied in the isolated lung or in a variety of functional components derived from it. These components include: (1) isolated sheets of the mucociliary epithelium, (2) flattened epithelial sheets grown in long term primary culture, (3) dissociated ciliated and mucous cells, (4) functional, demembranated ciliary tufts, and (5) isolated populations of discrete, demembranated axonemes. The latter two models can be reactivated with MgATP and made to beat at frequencies comparable to those measured in intact cells. Featuring large cells (25-30 microns in diameter) and cilia (12-13 microns in length) in comparison to other mucus-transporting systems, coupled with the ability to perform 'physiological' experiments at ambient temperatures, newt lungs afford a convenient system to study mechanisms involved in the control of ciliary beat frequency, waveform and coordination at several levels of organization.