Otitis media with effusion: components which contribute to the viscous properties

Negative Cross-Talk between TLR2/4-Independent AMPKα1 and TLR2/4-Dependent JNK Regulates S. pneumoniae-Induced Mucosal Innate Immune Response

Streptococcus pneumoniae is major cause of otitis media (OM) and life-threatening pneumonia. Overproduction of mucin, the major component of mucus, plays a critical role in the pathogenesis of both OM and pneumonia. However, the molecular mechanisms underlying the tight regulation of mucin upregulation in the mucosal epithelium by S. pneumoniae infection remain largely unknown. In this study, we show that S. pneumoniae pneumolysin (PLY) activates AMP-activated protein kinase α1 (AMPKα1), the master regulator of energy homeostasis, which is required for S. pneumoniae-induced mucin MUC5AC upregulation in vitro and in vivo. Moreover, we found that PLY activates AMPKα1 via cholesterol-dependent membrane binding of PLY and subsequent activation of the Ca2+- Ca2+/calmodulin-dependent kinase kinase β (CaMKKβ) and Cdc42-mixed-lineage protein kinase 3 (MLK3) signaling axis in a TLR2/4-independent manner. AMPKα1 positively regulates PLY-induced MUC5AC expression via negative cross-talk with TLR2/4-dependent activation of MAPK JNK, the negative regulator of MUC5AC expression. Moreover, pharmacological inhibition of AMPKα1 suppressed MUC5AC induction in the S. pneumoniae-induced OM mouse model, thereby demonstrating its therapeutic potential in suppressing mucus overproduction in OM. Taken together, our data unveil a novel mechanism by which negative cross-talk between TLR2/4-independent activation of AMPKα1 and TLR2/4-dependent activation of JNK tightly regulates the S. pneumoniae PLY-induced host mucosal innate immune response.

Assessment of Pediatric Middle Ear Effusions With Wideband Tympanometry

OBJECTIVE

To determine if wideband tympanometry (WBT) can differentiate types of middle ear effusion (MEE): serous, mucoid, and purulent.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary care children's hospital.

METHODS

Children who met American Academy of Otolaryngology-Head and Neck Surgery's guidelines for ventilation tube insertion had WBT after anesthesia induction but before tympanotomy. MEE was categorized into 1 of 4 comparison groups: serous effusion, mucoid effusion, purulent effusion, or no effusion. WBT measurements were averaged to 16 one-third octave frequency bands, and comparison of the absorbance patterns for each MEE type was performed through a linear mixed effects model.

RESULTS

A total of 118 children (211 ears) were included: 47 females (39.8%) and 71 males (60.2%). The mean age was 2.73 years (95% CI, 2.25-3.22); mean weight, 14.35 kg (95% CI, 12.85-15.85); and mean Z score, 1.13 (95% CI, -0.64 to 2.33). Effusions included 61 mucoid (28.9%), 30 purulent (14.2%), and 14 serous (6.6%), with 106 (50.2%) having no effusion. No significant differences were found for sex, race, age, weight, or Z score among the 4 types of effusion (P < .05). WBT showed a significant difference in median absorption among the effusion groups (P < .001), with a medium effect size of 0.35.

CONCLUSIONS

WBT has potential use to differentiate types of MEE and should be studied further as a tool for investigating how the natural history and management of serous and mucoid effusions may differ.

The relationship between the tympanostomy tube extrusion time and viscosity

OBJECTIVE

The purpose of the study was to assess the correlation between the tympanostomy tube extrusion time and the viscosity of the middle ear fluid.

METHODS

Thirty-three patients who were scheduled for a tympanostomy tube (TT) insertion were included in the study. During the paracentesis procedure, fluid from the middle ear was obtained, and the viscosity was measured with a viscometer. Patients with effusion values below and above the median viscosity value of 439 cP (cP) were assigned to Group 1 and Group 2, respectively. After the surgery, the patients were followed up monthly until the tubes were observed to be extruded.

RESULTS

The analysis of the correlation between the tube extrusion time and the viscosity was statistically insignificant (p > 0.05). The mean tube extrusion time of Group 1 (12.65 ± 4.152 months) was slightly lower than that of Group 2 (13.81 ± 4.43 months); however, the difference was not statistically significant.

CONCLUSION

The tube extrusion time can be longer or shorter and is independent of the effusion viscosity. Further studies are needed to clarify the factors that affect the TT extrusion time.

TRIAL REGISTRATION NUMBER

NCT03848026.

Expression of endoplasmic reticulum stress-related mRNA in otitis media with effusion

OBJECTIVES

The endoplasmic reticulum (ER) is an intracellular organelle involved in the synthesis and secretion of proteins. The ER stress response, which protects cells from cytotoxic proteins such as unfolded proteins, is related to several diseases including inflammation. In this study, we investigated the effect of ER stress on the pathophysiology of otitis media with effusion (OME).

METHODS

Thirty-nine pediatric patients who were diagnosed with OME and underwent ventilation tube insertion were enrolled in this study. Exudate from the middle ear cavity was collected through ventilation insertion, and ER stress gene expression was analyzed via real-time polymerase chain reactions(PCR).

RESULTS

There were no significant differences in ER stress-related mRNA expression between effusion culture-positive and culture-negative groups (p > 0.05). Expression of the C/EBP-homologous protein (CHOP) was higher in the otitis-prone group than in the non-otitis-prone group (p < 0.05). The most common type of fluid was mucoid, and inositol-requiring enzyme 1α expression was higher in serous fluid than in mucoid, mucopurulent, or purulent fluid (p < 0.05).

CONCLUSIONS

Endoplasmic reticulum stress-related responses are activated in pediatric OME patients, and specific ER-stress related pathways are related to both the characteristics of fluid and the frequency of OME. Thus, ER stress-related responses affect the pathophysiology of OME in pediatric OME patients.

Cellular content plays a crucial role in Non-typeable Haemophilus influenzae infection of preinflamed Junbo mouse middle ear

Non-typeable Haemophilus influenzae (NTHi) is a major pathogen causing acute otitis media (AOM). The relationship between the cellular content of the middle ear fluid (MEF) during AOM and infection of NTHi is poorly understood. Using the Junbo mouse, a characterised NTHi infection model, we analysed the cellular content of MEF and correlated the data with NTHi titres. The MEF of the Junbo mouse was heterogeneous between ears and was graded from 1 to 5; 1 being highly serous/clear and 5 being heavily viscous/opaque. At seven-day post-intranasal inoculation, NTHi was not found in grade-1 or 2 fluids, and the proportion of MEF that supported NTHi increased with the grade. Analyses by flow cytometry indicated that the cellular content was highest in grade-4 and 5 fluids, with a greater proportion of necrotic cells and a low-live cell count. NTHi infection of the middle ear increased the cell count and led to infiltration of immune cells and changes in the cytokine and chemokine levels. Following NTHi inoculation, high-grade infected MEFs had greater neutrophil infiltration whereas monocyte infiltration was significantly higher in serous noninfected low-grade fluids. These data underline a role for immune cells, specifically monocytes and neutrophils, and cell necrosis in NTHi infection of the Junbo mouse middle ear.

Differential diagnosis of otitis media with effusion using label-free Raman spectroscopy: A pilot study

Otitis media with effusion (OME) is an important and common condition affecting hearing in pediatric patients characterized by the presence of fluid in the middle ear space. The fluid is normally described as serous or mucoid based on differences in the fluid viscosity. The differential diagnosis of two OMEs, namely serous and mucoid is of significant clinical value because while the former is self-limiting, surgical procedure is commonly required for the latter. However, accurate identification of fluid types remains a challenging target unattainable with current clinical modalities due to unavailability of nonperturbative molecular tools. Here, we report an emerging spectroscopy approach featuring Raman scattering and multivariate analysis of spectral patterns to discern serous and mucoid fluids, obtained from pediatric patients undergoing myringotomy and tube placement, by providing information of differentially expressed molecules with high specificity. We demonstrate the feasibility of Raman spectroscopy-based approach to categorize middle ear effusion based on the characteristic spectral markers, notably of mucin, with classification accuracy of 91% and 93% for serous and mucoid, respectively. Our findings pave the way for further development of such a tool for fully noninvasive application that will lead to objective and accurate diagnosis thereby reducing unnecessary visits and surgical procedures.

Association of Gel-Forming Mucins and Aquaporin Gene Expression With Hearing Loss, Effusion Viscosity, and Inflammation in Otitis Media With Effusion

Importance

Persistent, viscous middle ear effusion in pediatric otitis media (OM) contributes to increased likelihood of anesthesia and surgery, conductive hearing loss, and subsequent developmental delays. Biomarkers of effusion viscosity and hearing loss have not yet been identified despite the potential that such markers hold for targeted therapy and screening.

Objective

To investigate the association of gel-forming mucins and aquaporin 5 (AQP5) gene expression with inflammation, effusion viscosity, and hearing loss in pediatric OM with effusion (OME).

Design, Setting, and Participants

Case-control study of 31 pediatric patients (aged 6 months to 12 years) with OME undergoing tympanostomy tube placement and control individuals (aged 1 to 10 years) undergoing surgery for cochlear implantation from February 1, 2013, through November 30, 2014. Those with 1 or more episodes of OM in the previous 12 months, immunologic abnormality, anatomical or physiologic ear defect, OM-associated syndrome (ie, Down syndrome, cleft palate), chronic mastoiditis, or history of cholesteatoma were excluded from the study. All patients with OME and 1 control were recruited from Children's Hospital of Wisconsin, Milwaukee. The remainder of the controls were recruited from Sick Kids Hospital in Toronto, Ontario, Canada.

Main Outcomes and Measures

Two to 3 middle ear biopsy specimens, effusions, and preoperative audiometric data (obtained <3 weeks before surgery) were collected from patients; only biopsy specimens were collected from controls. Expression of the mucin 2 (MUC2), mucin 5AC (MUC5AC), mucin 5B (MUC5B), and AQP5 genes were assayed in middle ear biopsy specimens by quantitative polymerase chain reaction. One middle ear biopsy specimen was sectioned for histopathologic analysis. Reduced specific viscosity of effusions was assayed using rheometry.

Results

Of the 31 study participants, 24 patients had OME (mean [SD] age, 50.4 [31.9] months; 15 [62.5%] male; 16 [66.7%] white) and 7 acted as controls (mean [SD] age, 32.6 [24.4] months; 2 [26.6%] male; 6 [85.7%] white). Mucins and AQP5 gene expression were significantly higher in patients with OME relative to controls (MUC2: ratio, 127.6 [95% CI, 33.7-482.7]; MUC5AC: ratio, 3748.8 [95% CI, 558.1-25 178.4]; MUC5B: ratio, 471.1 [95% CI, 130.7-1697.4]; AQP5: ratio, 2.4 [95% CI, 1.1-5.6]). A 2-fold increase in MUC5B correlated with increased hearing loss (air-bone gap: 7.45 dB [95% CI, 2.65-12.24 dB]; sound field: 6.66 dB [95% CI, 6.63-6.69 dB]), effusion viscosity (2.75 mL/mg; 95% CI, 0.89-4.62 mL/mg), middle ear epithelial thickness (3.5 μm; 95% CI, 1.96-5.13 μm), and neutrophil infiltration (odds ratio, 1.7; 95% CI, 1.07-2.72). A 2-fold increase in AQP5 correlated with increased effusion viscosity (1.94 mL/mg; 95% CI, 0.08-3.80 mL/mg).

Conclusions and Relevance

Further exploration of the role of MUC5B in the pathophysiology of OME holds promise for development of novel, targeted therapies to reduce effusion viscosity, facilitation of effusion clearance, and prevention of disease chronicity and hearing loss in patients with OME.

The pathogens profile in children with otitis media with effusion and adenoid hypertrophy

Objectives

To evaluate the presence of viruses and bacteria in middle ear and adenoids of patients with and without otitis media with effusion (OME).

Methods

Adenoid samples and middle ear washes (MEW) were obtained from children with OME associated with adenoid hypertrophy undergoing adenoidectomy and tympanostomy, and compared to those obtained from patients undergoing cochlear implant surgery, as a control group. Specific DNA or RNA of 9 respiratory viruses (rhinovirus, influenza virus, picornavirus, syncytial respiratory virus, metapneumovirus, coronavirus, enterovirus, adenovirus and bocavirus) and 5 bacteria (S. pneumoniae, H. influenzae, M. catarrhalis, P. aeruginosa and S. aureus) were extracted and quantified by real-time PCR.

Results

37 OME and 14 cochlear implant children were included in the study. At the adenoid, virus and bacteria were similarly detected in both OME and control patients. At the middle ear washes, however, a higher prevalence of bacteria was observed in patients with OME (p = 0.01). S. pneumoniae (p = 0.01) and M. catarrhalis (p = 0.022) were the bacteria responsible for this difference. Although total virus detection was not statistically different from controls at the middle ear washes (p = 0.065), adenovirus was detected in higher proportions in adenoid samples of OME patients than controls (p = 0.019).

Conclusions

Despite both OME and control patients presented similar rates of viruses and bacteria at the adenoid, children with OME presented higher prevalence of S. pneumonia, M. catarrhalis in middle ear and adenovirus in adenoids when compared to controls. These findings could suggest that these pathogens could contribute to the fluid persistence in the middle ear.

Proteomic Characterization of Middle Ear Fluid Confirms Neutrophil Extracellular Traps as a Predominant Innate Immune Response in Chronic Otitis Media

BACKGROUND

Chronic Otitis Media (COM) is characterized by middle ear effusion (MEE) and conductive hearing loss. MEE reflect mucus hypersecretion, but global proteomic profiling of the mucosal components are limited.

OBJECTIVE

This study aimed at characterizing the proteome of MEEs from children with COM with the goal of elucidating important innate immune responses.

METHOD

MEEs were collected from children (n = 49) with COM undergoing myringotomy. Mass spectrometry was employed for proteomic profiling in nine samples. Independent samples were further analyzed by cytokine multiplex assay, immunoblotting, neutrophil elastase activity, next generation DNA sequencing, and/or immunofluorescence analysis.

RESULTS

109 unique and common proteins were identified by MS. A majority were innate immune molecules, along with typically intracellular proteins such as histones and actin. 19.5% percent of all mapped peptide counts were from proteins known to be released by neutrophils. Immunofluorescence and immunoblotting demonstrated the presence of neutrophil extracellular traps (NETs) in every MEE, along with MUC5B colocalization. DNA found in effusions revealed unfragmented DNA of human origin.

CONCLUSION

Proteomic analysis of MEEs revealed a predominantly neutrophilic innate mucosal response in which MUC5B is associated with NET DNA. NETs are a primary macromolecular constituent of human COM middle ear effusions.

Predictions of middle-ear and passive cochlear mechanics using a finite element model of the pediatric ear

A finite element (FE) model was developed based on histological sections of a temporal bone of a 4-year-old child to simulate middle-ear and cochlear function in ears with normal hearing and otitis media. This pediatric model of the normal ear, consisting of an ear canal, middle ear, and spiral cochlea, was first validated with published energy absorbance (EA) measurements in young children with normal ears. The model was used to simulate EA in an ear with middle-ear effusion, whose results were compared to clinical EA measurements. The spiral cochlea component of the model was constructed under the assumption that the mechanics were passive. The FE model predicted middle-ear transfer functions between the ear canal and cochlea. Effects of ear structure and mechanical properties of soft tissues were compared in model predictions for the pediatric and adult ears. EA responses are predicted to differ between adult and pediatric ears due to differences in the stiffness and damping of soft tissues within the ear, and any residual geometrical differences between the adult ear and pediatric ear at age 4 years. The results have significance for predicting effects of otitis media in children.

Investigating the pressure-reducing effect of wound dressings

OBJECTIVE

Currently, polyurethane foam dressings are commercially available from many manufacturers. However, the pressure-reducing effect is expected to differ by the formulation and combination of the main and secondary ingredients and by manufacturing method. In this study, we investigated the effects of pressure reduction using dressing materials with various structural characteristics, including polyurethane foam dressings based on the engineering point of view, focusing on the dry state.

METHOD

Pressure was measured in a model that simulated compression on the sacral region in a decubitus position. Pressure was measured for different dressings: ten products, consisting of five types of material (polyurethane foam, hydropolymeric, Hydrofiber, hydrocolloid, and low-adherent absorbent).

RESULTS

All dressings used in this study showed significantly reduced pressure. ALLEVYN Non-Adhesive had the lowest pressure at 35.833 ± 1.155 mmHg, and DuoDERM Extra Thin CGF had the highest pressure at 66.867 ± 1.060 mmHg. The pressure of the control was 74.667 ± 1.405 mmHg. The other dressings were: ALLEVYN Adhesive: 44.233 ± 0.777 mmHg; ALLEVYN Gentle Border: 46.967 ± 1.537mmHg; Mepilex Border: 53.867 ± 0.231 mmHg; Biatain Silicone: 56.000 ± 0.520 mmHg; TIELLE: 57.267 ± 3.403 mmHg;Versiva XC: 65.900 ± 0.800 mmHg; DuoDERM CGF: 57.267 ± 1.007 mmHg; and Melolin: 53.433 ± 1.973 mmHg.

CONCLUSION

The pressure-reducing effect of dressing differs not only by material type but also by product. That is, the pressure-reducing effect can differ even if the dressings are of the same material type, such as polyurethane foam. Our study investigated only the effect of materials and structural characteristics on the cushion of dressings in the dry state. Therefore, further investigation is needed to confirm the effect of pressure reduction by dressing to meet the conditions in the clinic.

More than one disease process in chronic sinusitis based on mucin fragmentation patterns and amino Acid analysis

Objective. To characterise fragmentation patterns and amino acid composition of MUC2 and MUC5AC in chronic sinusitis. Methods. Antigenic identity of purified sinus mucins was determined by ELISA. Fragmentation patterns of a MUC5AC rich sample mucin were analysed by Sepharose CL-2B gel chromatography. Samples, divided into one MUC2 rich and one MUC5AC rich group, were subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and their amino acid contents were analysed. Results. Reduction, trypsin digestion, and papain digestion produced progressively smaller mucin species. On SDS-PAGE, digested MUC5AC rich mucin produced four distinct products. Amino acid analysis was characteristic of mucins with high serine, threonine, and proline contents and reduction and proteolysis increased relative proportions of these amino acids. MUC5AC rich mucins contained more protein than MUC2 rich mucins. Conclusion. Sinus mucin fragmentation produced mucin subunits and glycopeptide units of smaller molecular sizes which are likely to have lower viscoelastic properties. Applying this in vivo could alter mucus physical properties and biologic functions. Amino acid contents of MUC2 and MUC5AC mucins are different. This could be contributing to biological properties and functions of sinus mucins. These data suggest that there may be different pathological processes occurring at the cellular level on chronic sinusitis.

Experimental and modeling study of human tympanic membrane motion in the presence of middle ear liquid

Vibration of the tympanic membrane (TM) has been measured at the umbo using laser Doppler vibrometry and analyzed with finite element (FE) models of the human ear. Recently, full-field TM surface motion has been reported using scanning laser Doppler vibrometry, holographic interferometry, and optical coherence tomography. Technologies for imaging human TM motion have the potential to lead to using a dedicated clinical diagnosis tool for identification of middle ear diseases. However, the effect of middle ear fluid (liquid) on TM surface motion is still not clear. In this study, a scanning laser Doppler vibrometer was used to measure the full-field surface motion of the TM from four human temporal bones. TM displacements were measured under normal and disease-mimicking conditions with different middle ear liquid levels over frequencies ranging from 0.2 to 8 kHz. An FE model of the human ear, including the ear canal, middle ear, and spiral cochlea was used to simulate the motion of the TM in normal and disease-mimicking conditions. The results from both experiments and FE model show that a simple deflection shape with one or two major displacement peak regions of the TM in normal ear was observed at low frequencies (1 kHz and below) while complicated ring-like pattern of the deflection shapes appeared at higher frequencies (4 kHz and above). The liquid in middle ear mainly affected TM deflection shapes at the frequencies higher than 1 kHz.

Mechanisms of tympanic membrane and incus mobility loss in acute otitis media model of guinea pig

Acute otitis media (AOM) is a rapid infection of middle ear due to bacterial or viral invasion. The infection commonly leads to negative pressure and purulent effusion in the middle ear. To identify how these changes affect tympanic membrane (TM) mobility or sound transmission through the middle ear, we hypothesize that pressure, effusion, and structural changes of the middle ear are the main mechanisms of conductive hearing loss in AOM. To test the hypothesis, a guinea pig AOM model was created by injection of Streptococcus pneumoniae. Three days post inoculation, vibration of the TM at umbo in response to input sound in the ear canal was measured at three experimental stages: intact, pressure-released, and effusion-drained AOM ears. The vibration of the incus tip was also measured after the effusion was removed. Results demonstrate that displacement of the TM increased mainly at low frequencies when pressure was released. As the effusion was removed, the TM mobility increased further but did not reach the level of the normal ear at low frequencies. This was caused by middle ear structural changes or adhesions on ossicles in AOM. The structural changes also affected movement of the incus at low and high frequencies. The results provide new evidence for understanding the mechanism of conductive hearing loss in AOM.

Middle ear fluid characteristics in pediatric otitis media with effusion

OBJECTIVE

Persistent otitis media with effusion is caused by poor clearance of middle ear fluid usually following an episode of acute otitis media. This fluid is thought to be viscous and poorly transportable by cilia. Because a subset of children require multiple myringotomy and tube placements for recurrent disease, we hypothesized that children requiring repeated procedures would have effusion fluid that was more viscous and less transportable than those having their first procedure.

DESIGN

Prospective clinical study.

SETTING

Tertiary care center.

PATIENTS AND INTERVENTIONS

Middle ear secretions were collected at the time of myringotomy and tube insertion in 36 children accrued sequentially. Twenty-six of these children were having their first procedure and 10 had previously undergone myringotomy and tube placement.

MAIN OUTCOME MEASURES

The secretions were evaluated for in vitro mucociliary transportability, and dynamic rheology in a magnetic microrheometer.

RESULTS

Children with the need for repeated procedures had effusions with lower mucociliary transportability, and overall higher mean measures of surface mechanical impedance/frictional adhesion, but these did not reach statistical significance. Mucopurulent effusions had significantly greater transportability than both the mucoid and serous effusions in both groups.

CONCLUSIONS

Persistent or recurrent otitis media with effusion is associated with poorly transportable middle ear fluid, which may have higher frictional adhesion. The best mucociliary transportability was measured in mucopurulent effusions.

Substance P and vasoactive intestinal peptide levels in middle ear effusions of children

CONCLUSION

This is the first report demonstrating high levels of substance P (SP) that inversely correlate with vasoactive intestinal peptide (VIP) levels in middle ear effusions (MEEs) of patients with otitis media with effusion (OME). Increased SP and decreased VIP levels might play a role in the pathogenesis of chronic OME.

OBJECTIVE

The etiology of OME is multifactorial, and neurogenic inflammation may play a significant role. SP and VIP levels were not evaluated previously in MEEs of children with OME.

METHODS

Fifty patients aged 2-12 years (mean age 5.24 ± 2.64) were included in the study. MEEs were classified as mucoid or serous based on the gross appearance. SP and VIP levels were determined using ELISA.

RESULTS

High levels of SP were detected in MEEs. In addition SP levels were significantly higher in serous samples (2910.55 ± 307.96 vs 2218.55 ± 262.30 pg/ml). There were also age-dependent changes, such that SP levels were significantly higher in children aged 2-3 years compared with those who were 4-5 and 6-12 years old. VIP levels were undetectable in 30% of patients and the mean level of VIP was 50.91 ± 16.01 pg/ml in serous middle ear effusions and 54.86 ± 15.91 pg/ml in mucoid MEEs.

Phosphodiesterase 4B mediates extracellular signal-regulated kinase-dependent up-regulation of mucin MUC5AC protein by Streptococcus pneumoniae by inhibiting cAMP-protein kinase A-dependent MKP-1 phosphatase pathway

Otitis media (OM) is the most common childhood bacterial infection and the major cause of conductive hearing loss in children. Mucus overproduction is a hallmark of OM. Streptococcus pneumoniae is the most common gram-positive bacterial pathogen causing OM. Among many mucin genes, MUC5AC has been found to be greatly up-regulated in the middle ear mucosa of human patients with OM. We previously reported that S. pneumoniae up-regulates MUC5AC expression in a MAPK ERK-dependent manner. We also found that MAPK phosphatase-1 (MKP-1) negatively regulates S. pneumoniae-induced ERK-dependent MUC5AC up-regulation. Therapeutic strategies for up-regulating the expression of negative regulators such as MKP-1 may have significant therapeutic potential for treating mucus overproduction in OM. However, the underlying molecular mechanism by which MKP-1 expression is negatively regulated during S. pneumoniae infection is unknown. In this study we show that phosphodiesterase 4B (PDE4B) mediates S. pneumoniae-induced MUC5AC up-regulation by inhibiting the expression of a negative regulator MKP-1, which in turn leads to enhanced MAPK ERK activation and subsequent up-regulation of MUC5AC. PDE4B inhibits MKP-1 expression in a cAMP-PKA-dependent manner. PDE4-specific inhibitor rolipram inhibits S. pneumoniae-induced MUC5AC up-regulation both in vitro and in vivo. Moreover, we show that PDE4B plays a critical role in MUC5AC induction. Finally, topical and post-infection administration of rolipram into the middle ear potently inhibited S. pneumoniae-induced MUC5AC up-regulation. Collectively, these data demonstrate that PDE4B mediates ERK-dependent up-regulation of mucin MUC5AC by S. pneumoniae by inhibiting cAMP-PKA-dependent MKP-1 pathway. This study may lead to novel therapeutic strategy for inhibiting mucus overproduction.

PKCθ synergizes with TLR-dependent TRAF6 signaling pathway to upregulate MUC5AC mucin via CARMA1

CARD-containing MAGUK protein 1 (CARMA1) plays a crucial role in regulating adaptive immune responses upon T-cell receptor (TCR) activation in T cells. Its role in regulating host mucosal innate immune response such as upregulation of mucin remains unknown. Here we show that CARMA1 acts as a key signaling mediator for synergistic upregulation of MUC5AC mucin by bacterium nontypeable Haemophilus influenzae (NTHi) and phorbol ester PMA in respiratory epithelial cells. NTHi-induced TLR-dependent TRAF6-MKK3-p38 MAPK signaling pathway synergizes with PKCθ-MEK-ERK signaling pathway. CARMA1 plays a crucial role in mediating this synergistic effect via TRAF6, thereby resulting in synergistic upregulation of MUC5AC mucin. Thus our study unveils a novel role for CARMA1 in mediating host mucosal innate immune response.

The role of vascular endothelial growth factor in pediatric otitis media with effusion

OBJECTIVES

Vascular endothelial growth factor (VEGF) is a potent and critical inducer of angiogenesis and vascular permeability, and has been shown to play an important role in inflammatory events, together with hypoxia and inflammatory cytokines. VEGF messenger ribonucleic acid (mRNA) is expressed in the middle ear in an experimental animal model of otitis media with effusion (OME) and in patients with OME. However, the protein levels of VEGF in middle ear effusions (MEEs) are unknown and the role of VEGF in the pathogenesis of OME is unclear. The goals of this study were to determine the VEGF levels in MEEs and to investigate the role of VEGF in production of MEEs by comparing these levels with those of interleukin-8 (IL-8), endotoxin, and albumin.

METHODS

Forty-six MEEs obtained from 33 children (24 boys, 9 girls) were used in the study. The mean age of the subjects was 6.3 years old (range, 1-12 years old). The patients underwent myringotomy and/or insertion of a ventilation tube for treatment of OME. After myringotomy, MEEs were collected with a Juhn Tym-Tap. The samples were divided into serous and mucoid types based on observation by the naked eye. After measuring the weight of the MEE, the sample was diluted with phosphate-buffered saline and frozen until use. The concentrations of VEGF and IL-8 in the MEEs were determined by enzyme-linked immunosorbent assays, endotoxin concentrations were measured by the Limulus Amebocyte Lysate test, and albumin levels were determined using an immunoturbidimetric assay.

RESULTS

VEGF, endotoxin, IL-8, and albumin were detected in 100%, 89%, 98%, and 100% of the 46 MEEs, respectively. The concentrations of VEGF, endotoxin, and IL-8 were significantly higher in mucoid MEEs than in serous MEEs (p<0.01), whereas there was no significant difference in the albumin concentration between mucoid and serous MEEs. The VEGF levels were positively correlated with those of endotoxin (R(2)=0.17, p<0.05) and albumin (R(2)=0.65, p<0.01) in mucoid MEEs, but not in serous MEEs.

CONCLUSIONS

Our results suggest that VEGF is produced in response to bacterial components such as endotoxin in the middle ear cavity and is associated with production of mucoid MEEs by increasing serum exudation and mucosal secretion.

MUC5B Is the predominant mucin glycoprotein in chronic otitis media fluid

Chronic otitis media (COM), e.g. "glue" ear is characterized by middle ear effusion and conductive hearing loss. Although mucous glycoproteins (mucins), which contribute to increased effusion viscosity, have been analyzed in ear tissue specimens, no studies have been reported that characterize the molecular identity of secreted mucin proteins present in actual middle ear fluid. For this study, effusions from children with COM undergoing myringotomy at Children's National Medical Center, Washington, DC were collected. These were solubilized and gel fractionated, and the protein content was identified using a liquid chromatography tandem mass spectrometry (LC-MS/MS) proteomics approach. Western blot analyses with mucin specific antibodies and densitometry were performed to validate the mass spectrometry findings. LC-MS/MS results identified mucin MUC5B by >26 unique peptides in six of six middle ear effusion samples, whereas mucin MUC5AC was only identified in one of six middle ear effusions. These findings were validated by Western blot performed on the same six and on an additional 11 separate samples where densitometry revealed on average a 6.4-fold increased signal in MUC5B when compared with MUC5AC (p = 0.0009). In summary, although both MUC5AC and MUC5B mucins are detected in middle ear effusions, MUC5B seems to be predominant mucin present in COM secretions.

Extending the chinchilla middle ear epithelial model for mucin gene investigation

OBJECTIVES

To investigate the expression of recently identified human mucin genes in an in vivo model of the chinchilla middle ear epithelium (CMEE).

METHODS

CMEE was harvested, RNA was extracted and primers were designed for RT-PCR to assess for expression of mucin genes Muc6, Muc17 and Muc18. Further sequencing of these genes was also accomplished.

RESULTS

Mucin genes Muc6, Muc17 and Muc18 was assessed and found to be identical to the expression in human and mouse MEE.

CONCLUSION

This study further characterizes mucin gene expression in the CMEE and provides additional sequence data for chinchilla middle ear genes. The concordance of this gene expression data to that of both the human and mouse models further demonstrates the utility of this animal model in OM investigations.

Factors affecting the extrusion rate of ventilation tubes

Objectives

The objective of this study was to determine the various factors that affect the extrusion rate of ventilation tubes (VTs), including the nature of the middle ear effusion.

Methods

A retrospective chart review of 82 pediatric patients (177 ears) who received VT insertion surgery under general anesthesia was carried out to evaluate the relationship between various factors and the VT extrusion rate. The factors we analyzed included age, gender, the adenoid size, the amount and content of the middle ear effusion after myringotomy, bleeding events, associated adenoidectomy and the findings of the tympanic membrane status, the tympanometry and the audiometry of the air bone gap.

Results

The mean extrusion time was 254 days (range, 11 to 809 days). The patients with no history of previous VT insertion had a longer extrusion time (mean, 279 days) than did the patients who had undergone previous VT insertion (mean, 203 days). The patients with serous effusion had the shortest extrusion time (mean, 190 days) as compared to those patients with glue (273 days) and pus (295 days) effusions. Other factors had no statistical significant relationship with the extrusion time.

Conclusion

The mean VT extrusion time was 254 days. The VT extrusion time was significantly related to the characteristics of the middle ear effusion and a history of previous VT insertion. Thus, the nature of middle ear effusion can provide a clinical clue to predict the VT extrusion time.

Mucin gene 19 (MUC19) expression and response to inflammatory cytokines in middle ear epithelium

Mucin gene 19 (MUC19) has been identified as a major gel-forming mucin in the human middle ear (ME). The objectives of this investigation were to characterize the expression and assess the regulation of MUC19 in the ME cell culture models utilized in the study of otitis media (OM). Findings demonstrate that MUC19 is expressed in both human immortalized cell culture (HMEEC) and chinchilla primary epithelial culture (CMEEC). ME exposure to inflammatory cytokines TNF-alpha, IL-1beta, IL-6 and IL-8 up-regulate MUC19 transcription, most robustly after exposure to TNF-alpha. Kinetic experiments suggest a relative early response in MUC19 transcription and a down-regulation after prolonged exposure. Glycoprotein production was increased in response to the increased transcription as well. Similar to other mucin genes in the ME, MUC19 is differentially regulated after exposure to inflammatory cytokines. The large size, gel-forming properties and up-regulation in response to important inflammatory cytokines of MUC19 suggest that it has significant potential to play a role in both physiology and pathophysiology of the ME.

Gene expression differences in infected and noninfected middle ear complementary DNA libraries

OBJECTIVES

To investigate genetic differences in middle ear mucosa (MEM) with nontypeable Haemophilus influenzae (NTHi) infection. Genetic upregulation and downregulation occurs in MEM during otitis media (OM) pathogenesis. A comprehensive assessment of these genetic differences using the techniques of complementary DNA (cDNA) library creation has not been performed.

DESIGN

The cDNA libraries were constructed from NTHi-infected and noninfected chinchilla MEM. Random clones were picked, sequenced bidirectionally, and submitted to the National Center for Biotechnology Information (NCBI) Expressed Sequence Tags database, where they were assigned accession numbers. These numbers were used with the basic local alignment search tool (BLAST) to align clones against the nonredundant nucleotide database at NCBI.

RESULTS

Analysis with the Web-based statistical program FatiGO identified several biological processes with significant differences in numbers of represented genes. Processes involved in immune, stress, and wound responses were more prevalent in the NTHi-infected library. S100 calcium-binding protein A9 (S100A9); secretory leukoprotease inhibitor (SLPI); beta(2)-microglobulin (B2M); ferritin, heavy-chain polypeptide 1 (FTH1); and S100 calcium-binding protein A8 (S100A8) were expressed at significantly higher levels in the NTHi-infected library. Calcium-binding proteins S100A9 and S100A8 serve as markers for inflammation and have antibacterial effects. Secretory leukoprotease inhibitor is an antibacterial protein that inhibits stimuli-induced MUC1, MUC2, and MUC5AC production.

CONCLUSIONS

A number of genes demonstrate changes during the pathogenesis of OM, including SLPI, which has an impact on mucin gene expression; this expression is known to be an important regulator in OM. The techniques described herein provide a framework for future investigations to more thoroughly understand molecular changes in the middle ear, which will likely be important in developing new therapeutic and intervention strategies.

The role of inflammatory mediators in the pathogenesis of otitis media and sequelae

This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K⁺ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued.

Activities of matrix metalloproteinases and tissue inhibitor of metalloproteinase-2 in idiopathic hemotympanum and otitis media with effusion

CONCLUSION

The expression profile of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-2 (TIMP-2) was specific to the type of middle ear effusion. Further studies are necessary for elucidating its correlation with the sequelae of otitis media with effusion (OME) and idiopathic hemotympanum.

OBJECTIVES

We aimed to investigate the relative activities of gelatinases (MMP-2 and -9), stromelysin-1 (MMP-3), and matrilysin-1 (MMP-7), as well as measuring TIMP-2 levels in the serous and mucous effusions of OME and hemorrhagic effusion of the idiopathic hemotympanum.

MATERIALS AND METHODS

Middle ear effusions were collected from patients with OME and idiopathic hemotympanum, and were classified as mucoid, serous, or hemorrhagic. MMP activity in the effusion samples was examined by gelatin and casein zymography. Levels of TIMP-2 were measured by ELISA. Human temporal bone sections, with and without otitis media (OM), were examined histologically.

RESULTS

One case showed tympanic membrane thinning in the OM group, but none in the control group. While MMP-2 was present in all effusions, the active form of MMP-2 was found only in mucous effusions. MMP-3 and MMP-7 activity was detected only in the mucous effusions. MMP-9 exhibited activity in all effusions, with the highest levels in mucous effusions. TIMP-2 levels were markedly elevated in serous effusions.

Mucin gene expression in human middle ear epithelium

OBJECTIVES

To investigate the expression of recently identified human mucin genes in human middle ear epithelial (MEE) specimens from in vivo middle ear (ME) tissue and to compare this mucin gene expression with mucin gene expression in an immortalized cell culture in vitro source of human MEE.

METHODS

Human MEE was harvested as in vivo specimens, and human MEE cell cultures were established for in vitro experimentation. RNA was extracted from MEE and primers designed for reverse-transcription polymerase chain reaction to assess for mucin gene MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6, MUC7, MUC8, MUC9, MUC11, MUC12, MUC13, MUC15, MUC16, MUC18, MUC19, and MUC20 expression. Mucin gene expression in the in vivo and in vitro ME tissue was compared against tissues with known expression of the mucin genes in question.

RESULTS

Mucin genes MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, MUC8, MUC9, MUC11, MUC13, MUC15, MUC16, MUC18, MUC19, and MUC20 were identified and expressed in both the in vivo and in vitro samples of MEE. Mucin genes MUC6, MUC12, and MUC17 were not identified in either tissue samples.

CONCLUSION

Many of the mucin genes that have been recently identified are expressed in human MEE. These genes are expressed in a similar manner in both in vivo and in vitro models. Understanding the mechanisms in which these genes regulate the physiology and pathophysiology of MEE will provide a more thorough understanding of the molecular mechanics of the MEE and disease conditions such as otitis media.

Synergistic induction of MUC5AC mucin by nontypeable Haemophilus influenzae and Streptococcus pneumoniae

Mucin overproduction is a hallmark of chronic respiratory diseases (CRD) such as chronic obstructive pulmonary disease and asthma, and otitis media. Despite the fact that nontypeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae are co-existing under these disease conditions, little is known about how NTHi and S. pneumoniae induce mucin overproduction. Here we show that NTHi and S. pneumoniae, when present together, synergistically induce MUC5AC mucin transcription. TLR2/4-MyD88-TAK1 signaling cascade transmits signal to regulate the synergistic induction of MUC5AC. The activation of MKK3/6-p38 and ERK MAPK pathways are required for the synergistic induction of MUC5AC. Moreover, S. pneumoniae synergizes with NTHi to induce MUC5AC expression via AP-1-dependent mechanism. Thus, our studies provide direct evidence for the synergistic induction of MUC5AC in mixed infections and bring novel insights into our understanding of molecular mechanisms underlying polymicrobial infections in CRD and OM.

Factors of the blockage of ventilation tubes in the immediate postoperative period

Postoperative ventilation tube (VT) blockage is relatively common with a reported incidence of 0.0-13.1%. The purpose of this study was to evaluate the factors that contribute to postoperative VT blockage. A retrospective chart review was carried out to compare rates of VT blockage within 2 weeks postsurgery. Analyzed factors included: otic drop, nature, and amount of middle ear (ME) effusion, presence of ME mucosa edema or granulation, bleeding during surgery, number of prior VT insertion, and the status of the tympanic membrane (TM). One hundred and twenty-eight ears from 79 patients were enrolled in this study. Eleven VTs (8.6%) were obstructed within 2 weeks postsurgery. Ears using ciprobay and tarivid otic drops showed a significantly higher rate of tube blockage (14.1%) compared to ears that were not exposed to otic drops (1.8%). Glue effusion caused the highest rates (14.8%) of tube blockage compared to mucoid (9.6%) and serous (3.0%) effusions. The amount of effusion, the presence of mucosal edema or granulation, bleeding during surgery, number of prior VT insertions and the status of the TM were not associated with postoperative VT blockage. The results of this study suggest that the routine use of antibiotic-containing otic drops after the insertion of VT may not be useful. Viscosity of the effusion appears to have an effect on the postoperative VT blockage. Thus, more attention should be focused on the ears with glue or mucoid effusions after surgery.

Opposing roles of PAK2 and PAK4 in synergistic induction of MUC5AC mucin by bacterium NTHi and EGF

Mucin, a major component of mucus, plays a critical role in host mucosal defense response by participating in mucociliary clearance. However, if overproduced, overproduced mucus leads to airway mucus obstruction and conductive hearing loss. Despite extensive studies that focus on investigating how MUC5AC mucin is regulated by one inducer at a time, how MUC5AC is synergistically regulated by multiple factors remains unknown. Here we provide direct evidence for the first time that bacterial pathogen NTHi and human growth factor EGF synergize with each other to potently up-regulate MUC5AC mucin transcription. Moreover, activation of both p38 and ERK is required for synergistic induction of MUC5AC by NTHi and EGF. Finally, PAK2 and PAK4 are differentially involved in this synergistic induction of MUC5AC by acting upstream of p38 and ERK. Our studies bring novel insights into our understanding of synergistic regulation of MUC5AC mucin by both pathological and physiological inducers.

A Novel Role for IκB Kinase (IKK) α and IKKβ in ERK-Dependent Up-Regulation ofMUC5ACMucin Transcription byStreptococcus pneumoniae

Epithelial cells represent the first line of host innate defense against invading microbes by elaborating a range of molecules involved in pathogen clearance. In particular, epithelial mucins facilitate the mucociliary clearance by physically trapping inhaled microbes. Up-regulation of mucin production thus represents an important host innate defense response against invading microbes. How mucin is induced in upper respiratory Streptococcus pneumoniae infections is unknown. In this study, we show that pneumolysin is required for up-regulation of MUC5AC mucin via TLR4-dependent activation of ERK in human epithelial cells in vitro and in mice in vivo. Interestingly, a "second wave" of ERK activation appears to be important in mediating MUC5AC induction. Moreover, IkappaB kinase (IKK) alpha and IKKbeta are distinctly involved in MUC5AC induction via an ERK1-dependent, but IkappaBalpha-p65- and p100-p52-independent, mechanism, thereby revealing novel roles for IKKs in mediating up-regulation of MUC5AC mucin by S. pneumoniae.

Clinical and biochemical factors that affect DPOAE expressions in children with middle ear effusion

OBJECTIVES

To evaluate the clinical and biochemical characteristics of middle ear effusion (MEE) that affect distortion product otoacoustic emissions (DPOAE) responsiveness and to investigate the possible role of DPOAE as a tool to know the characteristics of MEE preoperatively.

STUDY DESIGN AND SETTING

Prospective analysis of children with MEE effusion in a tertiary referral center. DPOAE results were compared with other audiologic tests, the character, amount of MEE, the amount of total protein, and TNF-alpha in the effusion.

RESULTS

The negative DPOAE with MEE group had much more thick mucous fluid in their middle ears than that of positive DPOAE with MEE group. The levels of total protein and TNF-alpha in MEE were significantly higher in the negative DPOAE group than those of the positive DPOAE group (P < 0.01).

CONCLUSIONS AND SIGNIFICANCE

The measurement of DPOAE in the children with MEE may predict the amount and the characteristics of MEE, which may help to decide the treatment methods.

Th1/Th2 and Regulatory Cytokines in Adults With Otitis Media With Effusion

OBJECTIVE

Otitis media with effusion is one of the most common and intractable ear diseases. However, the role of Th1, Th2, and immunoregulatory cytokines on the pathogenesis of the disease in adult patients remains to be determined. The aim of this study is to disclose the cytokine expression in middle ear effusions (MEEs) in adults and to compare the profile on the basis of the presence of allergic rhinitis and the type of effusions.

STUDY DESIGN

A prospective controlled clinical study.

PATIENTS

MEEs were collected from 80 adult subjects. The concentration of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, and interferon (IFN)-gamma in MEEs were determined by using enzyme-linked immunosorbent assay.

RESULTS

IL-2, IL-4, IL-5, IL-10, IL-12, and IFN-gamma in MEEs were detected in 60 (75.0%), 33 (41.3%), 42 (52.5%), 14 (17.5%), 80 (100%), and 66 (82.5%) samples, respectively. Among these cytokines, only the concentration of IL-4 in the allergic rhinitis-positive group was significantly higher than that in the allergic rhinitis-negative group. On the other hand, IL-2, IL-12, and IFN-gamma were detected, regardless of the presence of allergic rhinitis, and the concentration of these cytokines correlated with each other. The correlation between the concentration of IL-4 and IL-5 was also detected. In addition, both the incidence rate and the concentration of IL-10 in MEEs were significantly higher in the mucoid type compared with those in the serous type effusions.

CONCLUSION

Regardless of allergic status, IL-12 may play a critical role in the pathogenesis of otitis media with effusion by affecting the production of IL-2 and IFN-gamma. In addition, IL-4 may have some impact on the immunologic condition in adults with allergic rhinitis. IL-10 potentially affects the viscosity of MEEs.

Mucin gene cDNA sequence characterization in chinchilla middle ear epithelium

OBJECTIVES

To identify mucin genes in chinchilla middle ear epithelium and characterize complimentary deoxyribonucleic acid (cDNA) sequences to facilitate further investigations into mucin physiology and pathophysiology on a molecular level using the chinchilla model.

METHODS

Chinchilla mucin gene exploration and cDNA characterization was accomplished using reverse transcriptase-polymerase chain reactions (RT-PCR). Forward and reverse primer pairs were designed using consensus sequences available for human and rodent species. Chinchilla middle ear epithelium was harvested and primary cell cultures (CMEEC) were established. The CMEEC were explored for the expression of chinchilla mucin genes 1, 2, 4 and 5AC (cMuc1, cMuc2, cMuc4 and cMuc5AC). Identified cDNA amplicons for each of these genes was sequenced and homology compared to previously published human and rodent sequences.

RESULTS

CMEEC express all four of the mucin genes cMuc1, cMuc2, cMuc4 and cMuc5AC. cDNA amplicons for each of the genes were able to be sequenced with lengths ranging from 66 to 362 base pairs. Each of the chinchilla cDNA sequences expressed significant homology with published human and rodent cDNA for these mucin genes. A cDNA sequence for the housekeeping gene, beta-actin, was also identified.

CONCLUSIONS

Chinchilla middle ear epithelium grown in culture expresses the mucin genes 1, 2, 4 and 5AC, which have been identified as important in mucin regulation in the middle ear. cDNA sequences corresponding to these mucin genes were identified and may serve as important molecular tools in future studies of otitis media using the chinchilla model.

Clinical manifestations and risk factors of children receiving triple ventilating tube insertions for treatment of recurrent otitis media with effusion

OBJECTIVE

Our goal was to determine risk factors for children receiving additional ventilating tube insertions after initial tube insertion and to determine the changes of clinical manifestations in children who have undergone 3 ventilating tube insertion procedures.

STUDY DESIGN

We retrospectively analyzed medical and operation records of 423 young patients who had ventilating tube insertion because of chronic otitis media with effusion from January 1993 to December 1998. The single-operation group included patients who had 1 ventilating tube insertion only, and the triple-operation group included patients who received ventilating tube insertion 3 times because of recurring chronic otitis media with effusion.

RESULTS

At the first operation, there were significant differences between the single- and triple-operation groups in mean age, the proportion who received a concurrent adenoidectomy, the mean indwelling period of the first ventilating tube, the proportion who developed postoperative otorrhea within 1 month, and the proportion who had early extrusion of the ventilating tube within 3 months of surgery. In the triple-operation group, the accumulated number of adenoidectomies, the indwelling period of the ventilating tube, and the time interval before subsequent ventilating tube insertion after ventilating tube extrusion significantly increased as ventilating tube insertion procedures were performed repeatedly. Although there was no difference when compared with the single-operation group, the proportion of glue-like effusion significantly decreased as ventilating tube insertion procedures were performed repeatedly. There were no significant differences between the single- and triple-operation groups in male/female ratio, site of ventilating tube insertion, and the proportion of patients with glue-like effusion at the first ventilating tube insertion.

CONCLUSIONS

The probability of receiving additional ventilating tube insertion because of recurrent otitis media with effusion significantly increased in younger patients at the time of first ventilating tube insertion. The concurrent adenoidectomy, duration of the ventilating tube, postoperative otorrhea within 1 month, and early extrusion of the ventilating tube also influenced the probability of additional ventilating tube insertion.

Signaling pathways in interleukin-1beta-mediated middle ear mucin secretion

OBJECTIVES

The objectives of this study were to investigate the role of the phosphatidylcholine-specific phospholipase C (PC-PLC), protein kinase C (PKC), and nitric oxide synthase (NOS) pathways during upregulation of mucin secretion by middle ear epithelium after exposure to interleukin-1beta and to examine the ability of a specific interleukin-1 receptor antagonist (IL-1betara) to block this increased secretion.

MATERIALS AND METHODS

Primary chinchilla middle ear epithelial cultures were established and exposed to IL-1beta. Specific inhibitors of calmodulin, PC-PLC, PKC, and NOS pathways were used to investigate the potential role of these pathways leading to increased epithelial mucin secretion after exposure to IL-1beta. Mucin secretion was characterized by exclusion chromatography and liquid scintillation.

RESULTS

Epithelial cultures exposed to IL-1beta demonstrate an increase in mucin secretion that is blocked by specific inhibitors of PC-PLC, PKC, and NOS, but not by inhibitors of calmodulin. In addition, mucin secretion stimulated by IL-1beta was reversible with use of a specific IL-1betara.

CONCLUSIONS

IL-1beta stimulates mucin secretion from middle ear epithelium and its effects can be reversed by IL-1betara. PC-PLC, PKC, and NOS pathways play a role in the increased secretion of mucin in middle ear epithelial cells after exposure to IL-1beta.

The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion

Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME.

Accuracy of Tympanometric Middle Ear Pressure Determination in Secretory Otitis Media: Dose-Dependent Overestimation Related to the Viscosity and Amount of Middle Ear Fluid

HYPOTHESIS

Tympanometric measurements of middle ear pressure in children with secretory otitis media are overestimated in a dose-response manner because of increased hysteresis explained by the viscosity and amount of middle ear fluid.

BACKGROUND

Tympanometric middle ear pressure is important in evaluating children with secretory otitis media. These measurements are influenced by hysteresis appearing as a peak pressure difference in bidirectional tympanometry. This represents an inaccuracy of 0.5 x peak pressure difference, which is only 5 to 25 daPa in normal ears. However, previous experiments found increased hysteresis, suggesting an inaccuracy of 225 daPa in secretory otitis media ears.

MATERIALS AND METHODS

In 56 patients with secretory otitis media, bidirectional tympanometry was performed; Type B curves were excluded. The middle ear fluid was semiquantified subsequently at surgery according to viscosity (serous, seromucoid, or mucoid) and amount (small, medium, or large). A control group included 28 normal children. Peak pressure difference was calculated by the difference between middle ear pressure determined by a positive and negative pressure sweep.

RESULTS

Mean peak pressure difference was 10 and 69 daPa in the normal and secretory otitis media groups, respectively (p <0.001). However, peak pressure difference ranged to 205 daPa in the secretory otitis media group and showed a significant positive correlation to viscosity and amount of the fluid (both p <0.0001).

CONCLUSION

Peak pressure difference is significantly increased in secretory otitis media because of additional damping explained by the viscosity and amount of the fluid. The mean error was 5 daPa in normal ears and 35 daPa in secretory otitis media ears, but ranged to greater than 100 daPa. These results were only a low estimate of the inaccuracy, because patients with Type B tympanograms could not be included, and errors of more than 100 daPa can be anticipated.

Nontypeable Haemophilus influenzae lipoprotein P6 induces MUC5AC mucin transcription via TLR2-TAK1-dependent p38 MAPK-AP1 and IKKbeta-IkappaBalpha-NF-kappaB signaling pathways

Mucin overproduction is a hallmark of nontypeable Haemophilus influenzae (NTHi) infections. The molecular mechanisms underlying up-regulation of mucin in NTHi infections especially during the initial phase remain unknown. Here we show that P6, a 16-kDa outer membrane lipoprotein well conserved in NTHi, up-regulates MUC5AC mucin gene transcription in vitro and in vivo. Moreover, P6 induces MUC5AC transcription via TLR2-MyD88-IRAK1-TRAF6-TAK1-dependent p38 MAPK-AP1 and IKKbeta-IkappaBalpha-NF-kappaB signaling pathways. This study may bring new insights into the molecular pathogenesis of NTHi-induced infections and lead to novel therapeutic intervention for inhibiting mucin overproduction in patients with NTHi infections.

Middle ear epithelial mucin production in response to interleukin-6 exposure in vitro

OBJECTIVES

To investigate the role of the inflammatory cytokine interleukin-6 (IL-6) in the regulation of mucin secretion by middle ear epithelia.

MATERIALS AND METHODS

Primary chinchilla middle ear epithelial cultures were established and exposed to IL-6 in a dose- and time-dependent manner. Mucin secretion was characterized by exclusion chromatography and liquid scintillation.

RESULTS

Epithelial cultures exposed to increasing doses of IL-6 demonstrated greater amounts of mucin secretion (p=0.018). Additionally, cultures exposed to IL-6 at 50 ng/ml showed significant increased secretion of mucin over control in time-dependent experiments at 6-, 15- and 24-h time points (p=0.003).

CONCLUSIONS

IL-6 upregulates mucin secretion from cultured middle ear epithelial cells in a dose- and time-dependent manner. Elucidating the effect of specific cytokines on the regulation of mucin secretion is vital to understanding the pathophysiology of otitis media and the development of novel therapeutic strategies.

Effect of nitric oxide on mucin production in experimental otitis media

OBJECTIVE

The purpose of this study was to determine the role of nitric oxide (NO) in the pathogenesis of mucoid otitis media (OM) in lipopolysaccharide (LPS)-induced OM.

METHODS

OM was induced in chinchillas by injecting S-nitroso-N-acetylpenicillamine (SNAP), LPS, and LPS + SNAP into the superior bullae. Auditory brainstem response thresholds were measured every 24 hours. Samples of middle ear fluid were collected and analyzed for mucin by the periodic acid-Schiff method. At the end of each experiment, temporal bones were harvested for histopathologic study.

RESULTS

Mucin concentration was greatest in the LPS + the SNAP group and least in the SNAP-alone group. Auditory brainstem response threshold was highest in the LPS group and lowest in the SNAP group, although not significantly. Histopathology showed the greatest mucosal thickening and inflammation in the LPS + SNAP group.

CONCLUSION

The addition of NO in LPS-induced OM increased the mucin concentration in middle ear fluid and increased mucosal thickness and inflammation in middle ear mucosa.

SIGNIFICANCE

In the OM disease process, NO may contribute to the pathogenesis of mucoid OM.

Transforming growth factor-beta-Smad signaling pathway negatively regulates nontypeable Haemophilus influenzae-induced MUC5AC mucin transcription via mitogen-activated protein kinase (MAPK) phosphatase-1-dependent inhibition of p38 MAPK

In contrast to the extensive studies on the role of transforming growth factor-beta (TGF-beta) in regulating cell proliferation, differentiation, and apoptosis over the past decade, relatively little is known about the exact role of TGF-beta signaling in regulating host response in infectious diseases. Most of the recent studies have suggested that TGF-beta inhibits macrophage activation during infections with pathogens such as Trypanosoma cruzi and Leishmania, thereby favoring virulence. In certain situations, however, there is also evidence that TGF-beta has been correlated with enhanced resistance to microbes such as Candida albicans, thus benefiting the host. Despite these distinct observations that mainly focused on macrophages, little is known about how TGF-beta regulates host primary innate defensive responses, such as up-regulation of mucin, in the airway epithelial cells. Moreover, how the TGF-beta-Smad signaling pathway negatively regulates p38 mitogen-activated protein kinase (MAPK), a key pathway mediating host response to bacteria, still remains largely unknown. Here we show that nontypeable Haemophilus influenzae, a major human bacterial pathogen of otitis media and chronic obstructive pulmonary diseases, strongly induces up-regulation of MUC5AC mucin via activation of the Toll-like receptor 2-MyD88-dependent p38 path-way. Activation of TGF-beta-Smad signaling, however, leads to down-regulation of p38 by inducing MAPK phophatase-1, thereby acting as a negative regulator for MUC5AC induction. These studies may bring new insights into the novel role of TGF-beta signaling in attenuating host primary innate defensive responses and enhance our understanding of the signaling mechanism underlying the cross-talk between TGF-beta-Smad signaling pathway and the p38 MAPK pathway.

Middle ear epithelial mucin production in response to interleukin 1β exposure in vitro

OBJECTIVES: To investigate the role of the inflammatory cytokine interleukin-1β (IL-1β) in the regulation of mucin secretion by middle ear epithelia.

STUDY DESIGN AND SETTING: Primary chinchilla middle ear epithelial cultures were established and exposed to IL-1β in a dose- and time-dependent manner. Mucin secretion was characterized by exclusion chromatography and liquid scintillation.

RESULTS: Epithelial cultures exposed to increasing doses of IL-1β demonstrated greater amounts of mucin secretion ( P = 0.007). Additionally, cultures exposed to IL-1β at 50 ng/mL showed increased secretion of mucin over control noticeable at 6 hours, but significant at the 15- and 24-hour time points ( P > .0001 for each).

CONCLUSIONS: IL-1β upregulates mucin secretion from cultured middle ear epithelial cells in a dose-and time-dependent manner.

SIGNIFICANCE: Elucidating the effect of specific cytokines on the regulation of mucin secretion is vital to understanding the pathophysiology of otitis media and the development of novel therapeutic strategies.

Influence of prednisolone on the secretion of mucin from the HT29-MTX cell line

Glucocorticoids have been used in the treatment of otitis media with effusion with promising but inconsistent results. The HT29-MTX cell line is a completely differentiated and almost exclusively mucus-secreting goblet cell line. To assess the potential of steroids in suppressing mucin secretion, we have studied the response of this cell culture to prednisolone. Confluent cell cultures were trypsinized, subcultured in six-well plates and incubated with five doses of prednisolone from 10-3 M to 10-11 M and over a varying time course from 6 to 36 h. Analysis was performed using a monoclonal mouse antibody to human gastric mucin by dot-blot ELISA. Prednisolone caused a consistent reduction in mucin production from this cell line. Increasing concentrations of prednisolone resulted in increasing suppression of MUC5AC secretion. There is a dose-dependent suppression of mucin secretion by prednisolone, with a maximum effect of 21% over control seen at the highest steroid concentration used.

Transforming growth factor-beta -Smad signaling pathway cooperates with NF-kappa B to mediate nontypeable Haemophilus influenzae-induced MUC2 mucin transcription

Transforming growth factor-beta (TGF-beta) and related factors are multifunctional cytokines that regulate diverse cellular processes, including proliferation, differentiation, apoptosis, and immune response. The involvement of TGF-beta receptor-mediated signaling in bacteria-induced up-regulation of mucin, a primary innate defensive response for mammalian airways, however, still remains unknown. Here, we report that the bacterium nontypeable Haemophilus influenzae (NTHi), an important human respiratory pathogen, utilizes the TGF-beta-Smad signaling pathway together with the TLR2-MyD88-TAK1-NIK-IKKbeta/gamma-IkappaBalpha pathway to mediate NF-kappaB-dependent MUC2 mucin transcription. The NTHi-induced TGF-beta receptor Type II phosphorylation occurred at as early as 5 min. Pretreatment of NTHi with TGF-beta neutralization antibody reduced up-regulation of MUC2 transcription. Moreover, functional cooperation of NF-kappaB p65/p50 with Smad3/4 appears to positively mediate NF-kappaB-dependent MUC2 transcription. These data are the first to demonstrate the involvement of TGF-beta receptor-mediated signaling in bacteria-induced up-regulation of mucin transcription, bring insights into the novel role of TGF-beta signaling in bacterial pathogenesis, and may lead to new therapeutic intervention of NTHi infections.

In vitro study of IL-8 and goblet cells: possible role of IL-8 in the aetiology of otitis media with effusion

One of the main characteristics of otitis media with effusion (OME) is the differentiation of basal cells into goblet cells with subsequent proliferation in a modified respiratory epithelium leading to the formation of mucin-rich effusion in the middle ear cleft. In order to determine the effect of pro-inflammatory cytokines identified in OME, e.g. IL-1beta, tumour necrosis factor (TNF)-alpha, IL-6 and IL-8, on goblet cells, and to clarify the role of IL-8 in particular, we used the human goblet cell line HT29-MTX, which secretes two OME-related mucins: MUC5AC and MUC5B. IL-1beta and TNF-alpha stimulated the secretion of IL-8 in HT29-MTX goblet cells. Dose- (2-200 ng/ml) and time- (0-5 days) response studies of IL-8-induced mucin secretion were carried out. IL-8 upregulated the secretion of MUC5AC and MUC5B mucins in a concentration-dependent manner, with a maximum response at an IL-8 concentration of 20 ng/ml. IL-8 (20 ng/ml)-mediated mucin secretion persisted for up to 5 days, with a peak response 72 h after the addition of cytokine. These results suggest that: (i) goblet cells are target cells for the pro-inflammatory cytokines IL-1beta, TNF-alpha and IL-8 and can contribute to the pathogenesis of OME by increasing both the concentration of IL-8 and the secretion of mucin; and (ii) IL-8 stimulates prolonged mucin secretion from goblet cells and may be involved in the maintenance of the disease in the chronic stage.