Interleukin-8 concentration predicts the neutrophil count in middle ear effusion

Immunomodulatory Response of the Middle Ear Epithelial Cells in Otitis Media

HYPOTHESIS

The middle ear (ME) epithelium transforms because of changed immunomodulation during infection.

INTRODUCTION

The epithelial cells of the tympanic cavity represent the first line of defense in the context of otitis media. They can convert from a typical mucosal site into a respiratory epithelium and vice versa. Our goal is to depict the specific immune response of epithelial cells after infection at the molecular level.

METHODS

The investigations were carried out on healthy and inflamed ME tissue, removed during surgical interventions in mouse and human models, and in a human in-vitro cell model in human ME epithelial cell line. We determined the epithelial localization of the protein expression of Toll- and NOD-like immune receptors and their associated signaling molecules using immunohistochemistry. In addition, we examined growth behavior and gene expression due to direct stimulation and inhibition.

RESULTS

We found clinically and immunobiologically confirmed transformation of the inflamed ME epithelium depending on their origin, as well as differences in the distribution of Toll-like receptors and nucleotide-binding oligomerization domain-like receptors in the epithelial cell lining. Dysregulated gene and protein expression of the inflammatory and apoptotic genes could be modulated by stimulation and inhibition in the epithelial cells.

CONCLUSIONS

The local ME mucosal tissue is believed to modulate downstream immune activity after pathogen invasion via intrinsic cellular mechanism. Using translation approaches to target these molecular pathways may offer more reliable clinical resolution of otitis media in the future.

Immunomodulation as a Protective Strategy in Chronic Otitis Media

Introduction

Major features of the pathogenesis in otitis media, the most common disease in childhood, include hyperplasia of the middle ear mucosa and infiltration by leukocytes, both of which typically resolve upon bacterial clearance via apoptosis. Activation of innate immune receptors during the inflammatory process leads to the activation of intracellular transcription factors (such as NF-κB, AP-1), which regulate both the inflammatory response and tissue growth. We investigated these leading signaling pathways in otitis media using mouse models, human samples, and human middle ear epithelial cell (HMEEC) lines for therapeutic immunomodulation.

Methods

A stable otitis media model in wild-type mice and immunodeficient KO-mice, as well as human tissue samples from chronic otitis media, skin from the external auditory canal and middle ear mucosa removed from patients undergoing ear surgery, were studied. Gene and protein expression of innate immune signaling molecules were evaluated using microarray, qPCR and IHC. In situ apoptosis detection determined the apoptotic rate. The influence of bacterial infection on immunomodulating molecules (TNFα, MDP, Tri-DAP, SB203580, Cycloheximide) in HMEEC was evaluated. HMEEC cells were examined after bacterial stimulation/inhibition for gene expression and cellular growth.

Results

Persistent mucosal hyperplasia of the middle ear mucosa in chronic otitis media resulted from gene and protein expression of inflammatory and apoptotic genes, including NODs, TNFα, Casp3 and cleaved Casp3. In clinical chronic middle ear samples, these molecules were modulated after a specific stimulation. They also induced a hyposensitive response after bacterial/NOD-/TLR-pathway double stimulation of HMEEC cells in vitro. Hence, they might be suitable targets for immunological therapeutic approaches.

Conclusion

Uncontrolled middle ear mucosal hyperplasia is triggered by TLRs/NLRs immunoreceptor activation of downstream inflammatory and apoptotic molecules.

Differences in innate immune response gene regulation in the middle ear of children who are otitis prone and in those not otitis prone

OBJECTIVE

Acute otitis media (AOM) causes an inflammatory response in the middle ear. We assessed differences in innate immune responses involved in bacterial defense at onset of AOM in children who were stringently defined as otitis prone (sOP) and children not otitis prone (NOP).

STUDY DESIGN

Innate immune genes analysis from middle ear fluid (MEF) samples of children.

METHODS

Genes of toll-like receptors (TLR), nod-like and retinoic acid-inducible gene-I-like receptors, downstream effectors important for inflammation and apoptosis, including cytokines and chemokines, were studied from MEF samples by using a real-time polymerase chain reaction array. Protein levels of differentially regulated genes were measured by Luminex.

RESULTS

Gene expression in MEF among children who were sOP was significantly different in upregulation of interleukin 8, secretory leukocyte peptidase inhibitor, and chemokine (C-C motif) ligand 3, and in downregulation of interferon regulatory factor 7 and its related signaling molecules interferon alpha, Toll-like receptor adaptor molecule 2, chemokine (C-C motif) ligand 5, and mitogen-activated protein kinase 8 compared with children who were NOP. Differences in innate gene regulation were similar when AOM was caused by Streptococcus pneumoniae or nontypeable Haemophilus influenzae.

CONCLUSION

Innate-immune response genes are differentially regulated in children who were sOP compared with children with NOP.

Otitis media with effusion: an effort to understand and clarify the uncertainties

Otitis media with effusion--defined as the accumulation of middle-ear effusion behind an intact tympanic membrane without signs or symptoms of acute infection--is one of the most common causes of hearing loss in children in developed countries, potentially leading to language deficits. Although treatment of chronic or relapsing otitis media with effusion is considered imperative, none of the preventative or nonsurgical management measures currently available have proven effective. Tympanostomy tube placement remains the recommended treatment option for high-risk children or for cases of unresponsive otitis media with effusion. This can be attributed to the uncertainties surrounding its pathogenesis. Multiple factors and several possible pathogenetic models have been proposed to explain the production and persistence of middle-ear effusion; only a few of them are supported by sufficient evidence. In this review, the authors will present current knowledge on the pathogenesis, consequences, diagnosis and management of otitis media with effusion. An effort will be made to clarify those aspects sufficiently supported by evidence-based studies, and to underline those that remain unfounded.

Lower nasopharyngeal epithelial cell repair and diminished innate inflammation responses contribute to the onset of acute otitis media in otitis-prone children

About 30 % of young children experience excessive, frequent episodes of middle ear infection and are classified as acute otitis media prone (OP). Streptococcus pneumoniae (Spn) is a predominant otopathogen in OP and non-OP (NOP) children. The pathogenesis of middle ear infection involves otopathogen nasopharyngeal (NP) colonization followed by an upper respiratory viral infection that modifies the NP environment to allow a sufficient inoculum of bacteria to reflux via the Eustachian tube into the middle ear space. Here, we analyzed the NP mucosal repair response between age-matched stringently defined OP (sOP) and NOP children who progressed to middle ear infection caused by Spn. We found lower epidermal growth factor, epidermal growth factor receptor, and angiogenin cytokine concentrations in nasal washes of sOP compared with NOP children. Despite higher expression of TLR2/4 transcript expression in nasal epithelium and in polymorphonuclear cells present in nasal secretions in sOP children, sOP children had lower expression of proinflammatory cytokines such as IL-6 and IL-8 in the NP. Chemotaxis-associated cytokine expression at onset of AOM in sOP children was also lower compared with NOP children, possibly indicating a lower capacity to signal the innate immune system. We conclude that lower epithelial cell repair responses during viral infection in the NP combined with diminished innate inflammatory responses potentiate Spn pathogenesis in the sOP child.

Lipopolysaccharide induces proinflammatory cytokines and chemokines in experimental otitis media through the prostaglandin D2 receptor (DP)-dependent pathway

Otitis media is one of the most common and intractable ear diseases, and is the major cause of hearing loss, especially in children. Multiple factors affect the onset or development of otitis media. Prostaglandin D₂ is the major prostanoid involved in infection and allergy. However, the role of prostaglandin D₂ and prostaglandin D2 receptors on the pathogenesis of otitis media remains to be determined. Recent studies show that D prostanoid receptor (DP) and chemoattractant receptor-homologous molecule expressed on T helper type 2 (Th2) cells (CRTH2) are major prostaglandin D₂ receptors. In this study, homozygous DP single gene-deficient (DP⁻(/)⁻) mice, CRTH2 single gene-deficient (CRTH2⁻(/)⁻) mice and DP/CRTH2 double gene-deficient (DP⁻(/)⁻ CRTH2⁻(/)⁻) mice were used to investigate the role of prostaglandin D₂ and its receptors in otitis media. We demonstrate that prostaglandin D₂ is induced by lipopolysaccharide (LPS), a major component of Gram-negative bacteria, and that transtympanic injection of prostaglandin D₂ up-regulates macrophage inflammatory protein 2 (MIP-2), interleukin (IL)-1β and IL-6 in the middle ear. We also show that middle ear inflammatory reactions, including infiltration of inflammatory cells and expression of MIP-2, IL-1β and IL-6 induced by LPS, are reduced significantly in DP⁻(/)⁻ mice and DP⁻(/)⁻ CRTH2⁻(/)⁻ mice. CRTH2⁻(/)⁻ mice display inflammatory reactions similar to wild-type mice. These findings indicate that prostaglandin D₂ may play significant roles in LPS-induced experimental otitis media via DP.

Interferon-gamma in suppurative otitis media: significance of otorrhoea type and disease outcome

BACKGROUND

Interferon-gamma has been reported to have an immunoregulatory role in otitis media with effusion. However, such a role remains to be determined in acute suppurative otitis media.

AIM

To determine the levels of interferon-gamma in middle-ear secretion in children with acute suppurative otitis media, and to determine the significance of interferon-gamma to the nature of otorrhoea and the outcome of otitis media.

SETTINGS AND DESIGN

Prospective, longitudinal follow up of patients selected from community and tertiary health centres.

METHODS

We selected children with acute suppurative otitis media, diagnosed as otorrhoea of less than three months' duration. Middle-ear secretions were collected by pipetting and stored at -80 degrees C. Interferon-gamma was assayed using enzyme-linked immunosorbent assay. The patients were treated and followed up for nine to 12 months, to separate those with resolved acute suppurative otitis media from those with chronic suppurative otitis media.

RESULT

The study initially included 358 cases of acute suppurative otitis media. Nine-month follow up was achieved in 304 patients (85 percent). Of these patients, acute suppurative otitis media resolved in 187 (61 percent), while chronic suppurative otitis media was evident in 117 (39 percent). The children with completed follow up comprised 173 boys and 131 girls, aged between four months and nine years (mean age 6.6 years; standard deviation 1.32). These children had purulent otorrhoea in 171 cases (56 percent) and mucoid otorrhoea in 133 cases (44 percent). The children's middle-ear secretion interferon-gamma concentrations ranged from 12 to 126 pg/ml. The mean middle-ear secretion interferon-gamma concentration was 27.2 pg/ml (standard deviation 8.8) in patients whose acute suppurative otitis media resolved, and 73.1 pg/ml (standard deviation 9.5) in those progressing to chronic suppurative otitis media. In children with purulent otitis media, the mean middle-ear secretion interferon-gamma concentration was 43.5 pg/ml (standard deviation 15.6); in those with mucoid otitis media, it was 74.3 pg/ml (standard deviation 19.1). Univariate analysis revealed significant differences in middle-ear secretion interferon-gamma concentration, comparing resolved acute suppurative otitis media and chronic suppurative otitis media cases (p = 0.00), and comparing purulent and mucoid otitis media cases (p = 0.00). Pearson correlation testing revealed significant inverse correlation between interferon-gamma concentration and middle-ear secretion immunoglobulin G concentration (p = 0.01), immunoglobulin E concentration (p = 0.03) and immunoglobulin A concentration (p = 0.00).

CONCLUSION

A high concentration of interferon-gamma in middle-ear secretions promotes chronicity of suppurative otitis media. Further research in this area may lead to the development of agents which assist the control of suppurative otitis media chronicity.

Mouse models for human otitis media

Otitis media (OM) remains the most common childhood disease and its annual costs exceed $5 billion. Its potential for permanent hearing impairment also emphasizes the need to better understand and manage this disease. The pathogenesis of OM is multifactorial and includes infectious pathogens, anatomy, immunologic status, genetic predisposition, and environment. Recent progress in mouse model development is helping to elucidate the respective roles of these factors and to significantly contribute toward efforts of OM prevention and control. Genetic predisposition is recognized as an important factor in OM and increasing numbers of mouse models are helping to uncover the potential genetic bases for human OM. Furthermore, the completion of the mouse genome sequence has offered a powerful set of tools for investigating gene function and is generating a rich resource of mouse mutants for studying the genetic factors underlying OM.

Gastric pepsin in middle ear fluid of children with otitis media: clinical implications

Gastroesophageal reflux and extraesophageal reflux have been postulated to be involved in the pathogenesis of otitis media. This is supported by recent studies revealing the presence of gastric pepsin in the middle ear space of children with otitis media but not in control patients without otitis media. Reflux's role in otitis media appears to be most pronounced in younger children and those with purulent effusions.

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.

Expression of inflammatory mediators in the otitis media induced by Helicobacter pylori antigen in mice

Helicobacter pylori is a Gram-negative bacterium that is recognized as one of the key factors in gastric diseases such as gastritis, peptic ulcer and gastric cancer. Recent studies have shown relationships between H. pylori and extra-digestive diseases, and the presence of H. pylori in the middle ear and upper respiratory tract has been reported. However, the role of H. pylori in middle ear disease remains unclear. The present study demonstrated that H. pylori whole-cell protein directly induces macrophage migration inhibitory factor, macrophage inflammatory protein 2, interleukin 1 beta and tumor necrosis factor alpha in middle ear epithelium in mice, and severe proliferation of inflammatory cells was observed in middle ear cavity inoculated with H. pylori whole-cell protein. In addition, trans-tympanic injection of macrophage migration inhibitory factor up-regulated expression of macrophage inflammatory protein 2 in the middle ear. These findings indicate that H. pylori infection causes immunological inflammation in middle ear epithelium, and H. pylori may play a significant role in otitis media.

The role of extraesophageal reflux in otitis media in infants and children

OBJECTIVES/HYPOTHESIS

Gastroesophageal reflux disease (GERD) is common in children, and extraesophageal reflux disease (EORD) has been implicated in the pathophysiology of otitis media (OM). We sought to 1) determine the incidence of pepsin/pepsinogen presence in the middle ear cleft of a large sample of pediatric patients undergoing myringotomy with tube placement for OM; 2) compare this with a control population of pediatric patients undergoing middle ear surgery (cochlear implantation) with no documented history of OM; 3) analyze potential risk factors for OM in children with EORD demonstrated by the presence of pepsin in the middle ear cleft; and 4) determine if pepsin positivity at the time of myringotomy with tube placement predisposes to posttympanostomy tube otorrhea.

STUDY DESIGN AND METHODS

STUDY GROUP

prospective samples of 509 pediatric patients (n = 893 ear samples) undergoing myringotomy with tube placement for recurrent acute OM and/or otitis media with effusion in a tertiary care pediatric hospital with longitudinal follow-up of posttympanostomy tube otorrhea.

CONTROL GROUP

prospective samples of 64 pediatric patients (n = 74 ears) with negative history of OM undergoing cochlear implantation at one of the three tertiary care pediatric hospitals. A previously validated, highly sensitive and specific modified enzymatic assay was used to detect the presence of pepsin in the middle ear aspirates of study and control patients. Risk factors for OM and potentially associated conditions, including GERD, allergy, and asthma were analyzed for the study group through review of the electronic medical record and correlated topresence of pepsin in the middle ear space. Study patients were followed longitudinally postoperatively to determine the incidence of posttympanostomy tube otorrhea.

RESULTS

The incidence of pepsin in the middle ear cleft of the study group was 20% of patients and 14% of ears, which is significantly higher than 1.4% of control patients and 1.5% of control ears (P < .05). Study patients younger than 1 year had a higher rate of purulent effusions and pepsin in the middle ear cleft (P < .05). Patients with pepsin in the middle ear cleft were more likely to have an effusion at the time of surgery than patients without pepsin in the middle ear cleft (P < .05). There was no statistical association found between the presence of pepsin and clinical history of GERD, allergy, asthma, or posttympanostomy tube otorrhea.

CONCLUSIONS

Pepsin is detectable in the middle ear cleft of 20% of pediatric patients with OM undergoing tympanostomy tube placement, compared with 1.4% of controls; recovery of pepsin in the middle ear space of pediatric patients with OM is an independent risk factor for OM. Patients under 1 year of age have a higher incidence of purulent effusions and pepsin-positive effusions. Clinical history of GERD, allergy, and asthma do not seem to correlate with evidence of EORD reaching the middle ear cleft. The presence of pepsin in the middle ear space at the time of tube placement does not seem to predispose to posttympanostomy tube otorrhea.

Mouse models as a tool to unravel the genetic basis for human otitis media

The pathogenesis of otitis media (OM) is multifactorial and includes infection, anatomical factors, immunologic status, genetic predisposition, and environmental factors. OM remains the most common cause of hearing impairment in childhood. Genetic predisposition is increasingly recognized as an important factor. The completion of the mouse genome sequence has offered a powerful basket of tools for investigating gene function and can expect to generate a rich resource of mouse mutants for the elucidation of genetic factors underlying OM. We review the literature and discuss recent progresses in developing mouse models and using mouse models to uncover the genetic basis for human OM.

The role of nuclear factor-kappa B in interleukin-8 expression by human adenoidal fibroblasts

OBJECTIVES/HYPOTHESIS

The production of cytokines by adenoids is known to be associated with inflammation of nasopharynx and the pathogenesis of otitis media with effusion. However, the role of adenoids in producing inflammatory cytokines such as interleukin-8 (IL-8) is not yet clear. In the present study, expression of IL-8 in adenoidal fibroblasts was investigated at the level of transcription factors. Further, the effects of clarithromycin, a 14-member ring macrolide, on IL-8 gene expression and nuclear factor-kappa B (NF-kappa B) activation in adenoidal fibroblasts were evaluated.

STUDY DESIGN

In vitro study for the production of inflammatory cytokine from human adenoidal fibroblasts.

METHODS

Adenoidal fibroblasts were incubated with nontypeable Haemophilus influenzae endotoxin or interleukin-1 beta. Then the expression of IL-8 and the influence of NF-kappa B inhibitor and clarithromycin were evaluated. Interleukin-8 protein production was assessed by ELISA, and IL-8 messenger RNA production was measured by Northern blot analysis and reverse transcriptase-polymerase chain reaction. Activation of NF-kappa B and inhibition of its activation were determined by electrophoretic mobility shift assay.

RESULTS

The expression of both IL-8 protein and messenger RNA in adenoidal fibroblasts was enhanced by Haemophilus influenzae endotoxin and interleukin-1 beta and was positively correlated with increases in NF-kappa B activity. Treatment of cells with the NF-kappa B inhibitor N-tosyl-(L)-phenylalanine chloromethyl ketone, as well as with clarithromycin, reduced expression of IL-8 and NF-kappa B activity in a dose-dependent manner.

CONCLUSIONS

Results suggest that adenoidal fibroblasts produce IL-8 in response to endotoxin through NF-kappa B activation. The inhibitory effects of clarithromycin on NF-kappa B activation and IL-8 production in adenoidal fibroblasts might explain, in part, the mechanism of this drug in improving otitis media with effusion.

NF-kappaB in cultivated middle ear epithelium

OBJECTIVE

Otitis media with effusion (OME) may develop into a chronic course in some patients. In the majority of cases lipopolysaccharide (LPS) is detected in the middle ear fluid being capable of initiating and maintaining the inflammatory process associated with the disease. In addition, various extracellular signs of the inflammatory cascade are present, such as cytokines and ICAM-1 receptors. However, the underlying regulatory mechanisms situated intracellularily are sparsely recognized. NF-kappaB is a ubiquitously transcription factor complexed to its inhibitor within the cytoplasm. In response to stimuli, e.g. LPS or cytokines, NF-kappaB becomes activated and is translocated to the nucleus. At this level it induces transcription of various genes and subsequent expression of mRNA encoding for many immunoglobulins and cytokines, e.g. interleukin 8 (IL-8) which may be responsible for prolonging and maintaining the inflammatory process.

METHODS

To evaluate if NF-kappaB is present in middle ear epithelium including to identify possible stimulating factors in vitro studies using rabbit middle ear epithelial cells (meec) were undertaken. Both normal cells and LPS exposed cells were studied. ELISA techniques were applied to detect NF-kappaB, ICAM-1 receptors and IL-8. All measurements were adjusted to the concentration of total cell protein (TP).

RESULTS

NF-kappaB was detected in the normal middle ear epithelium in concentrations between 16.8 and 28.6 ng/microg TP. In response to LPS the NF-kappaB content increased with 25-33%. This enhancement became more pronounced with longer duration of the LPS exposition. A relatively distinct expression of ICAM-1 preceded the NF-kappaB increase, after which the ICAM-1 measurements declined. IL-8 was hardly measurable in normal cells. The IL-8 concentrations were higher in LPS exposed cultures. The time related curve demonstrated a diphasic shape with an early and a late maximum.

CONCLUSION

The chronic inflammation seen in some OME patients may be due to LPS activating ICAM-1 receptors and NF-kappaB followed by release of IL-8. An autocrine pathway may be established through activation of TNF alpha and IL-1beta. Thus, elucidation of alternative pathways in the inflammatory cascade and elimination of LPS, alternatively inhibition of NF-kappaB and/or IL-8, should be an issue for future investigation.

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.

Cytolytic complement activity in otitis media with effusion

Otitis media with effusion (OME) is a chronic inflammation persisting in the middle ear cavity of at least 8 weeks duration. Middle ear effusion (MEE; n = 38), samples from children suffering from OME were investigated for their direct cytolytic activity or an ability to enhance complement lysis of unsensitized bystander cells. Thirteen of the 38 MEEs had direct endogenous haemolytic activity and 27 samples had an ability to enhance serum-initiated lysis. Using an enzyme immunoassay, high levels of terminal complement complexes (TCC) were detected in the MEE samples (mean 34.1 microg/ml, range 5--89 microg/ml). This indicated strong local complement activation that had progressed to the terminal stage. As one potential factor promoting complement activation we identified both monomeric and trimeric properdin in MEE by Western blotting. By stabilizing C3 and C5 convertases properdin accelerates the alternative and terminal pathways of complement. On the other hand, the membrane attack complex (MAC) inhibitor CD59, which was found to be extensively shed into the MEE in a functionally active form, may control excessive cytotoxicity of the MEE. In conclusion, intense complement activation, up to the terminal level, maintains ongoing inflammation in the middle ear cavity and can pose a threat to the local epithelium.

Serous or mucoid effusion in the course of secretory otitis media: influence of ion transport modulation

OBJECTIVE

Secretory otitis media is defined by a chronic effusion in the middle ear cavities, behind an intact tympanic membrane without acute infection. In the course of secretory otitis media, the effusion is sometimes thick (or mucoid) and other times thin (or serous). For several authors, these differences might be related to different inflammatory levels rather than to distinct pathophysiological mechanisms. The purpose of this study was to determine whether the modulation of ion transport by inflammation could account for the differences observed in the aspect of ME effusion.

METHODS

Hydrogen peroxide (H2O2), used as an inflammation model was tested on a middle ear cell line (MESV) in culture.

RESULTS

Results show that low and high concentrations of H2O2 have opposite effects on ion (and then water) absorption by the middle ear epithelium.

CONCLUSION

the modulation of ion and water absorption by inflammation could modify the mucins concentration in the effusion, and explain observed viscosity differences in the course of secretory otitis media.

The aetiology of otitis media with effusion: a review

Otitis media with effusion (OME) is the most common cause of deafness in children in the developed world. In this article we aim to present an overview of current research developments on the aetiology of OME and the resulting implications for treatment. In the model we describe, the primary event is inflammation of the middle ear mucosa, usually due to the presence of bacteria. This leads to the release of inflammatory mediators, which cause secretion of a mucin-rich effusion by up-regulating mucin genes. Prolonged stimulation of the inflammatory response and poor mucociliary clearance lead to persistence of the middle ear fluid, giving rise to the clinical presentation of OME. We describe OME in the following sequence: the initial production of the effusion, the composition of the effusion produced, and factors impairing clearance of the effusion.

Middle ear fluid cytokine and inflammatory cell kinetics in the chinchilla otitis media model

Streptococcus pneumoniae is the most frequent microbe causing middle ear infection. The pathophysiology of pneumococcal otitis media has been characterized by measurement of local inflammatory mediators such as inflammatory cells, lysozyme, oxidative metabolic products, and inflammatory cytokines. The role of cytokines in bacterial infection has been elucidated with animal models, and interleukin (IL)-1beta, IL-6, and IL-8 and tumor necrosis factor alpha (TNF-alpha) are recognized as being important local mediators in acute inflammation. We characterized middle ear inflammatory responses in the chinchilla otitis media model after injecting a very small number of viable pneumococci into the middle ear, similar to the natural course of infection. Middle ear fluid (MEF) concentrations of IL-1beta, IL-6, IL-8, and TNF-alpha were measured by using anti-human cytokine enzyme-linked immunosorbent assay reagents. IL-1beta showed the earliest peak, at 6 h after inoculation, whereas IL-6, IL-8, and TNF-alpha concentrations were increasing 72 h after pneumococcal inoculation. IL-6, IL-8, and TNF-alpha but not IL-1beta concentrations correlated significantly with total inflammatory cell numbers in MEF, and all four cytokines correlated significantly with MEF neutrophil concentration. Several intercytokine correlations were significant. Cytokines, therefore, participate in the early middle ear inflammatory response to S. pneumoniae.