Interleukin-8 gene expression in middle ear effusions

Allergy in pathogenesis of Eustachian Tube Dysfunction

Eustachian tube dysfunction (ETD) is a condition where the Eustachian tube (ET) fails to function normally, resulting in symptoms such as aural fullness, tinnitus, autophony, and hearing loss. ETD can further lead to middle ear diseases such as otitis media effusion and adhesive otitis media, which is becoming more common in the field of otology. Although the pathogenesis of ETD remains unclear, recent animal studies and clinical experiments have found allergic reactions and allergic diseases are closely related to the occurrence of ETD. As the mucosa of the ET is continuous with that of the nasopharynx and tympanic cavity, it is reasonable to assume that the immunological basis of the ET itself is similar to that of respiratory allergic diseases. However, due to the special anatomical location and complex pathogenesis of the ET, there is still no unified diagnostic gold standard. Additionally, there is an ongoing debate regarding whether ETD can be classified as a distinct disease or even an allergic disease. Furthermore, the effectiveness of anti-allergic therapy in patients with ETD is yet to be fully understood. Therefore, this review elaborates on the possible mechanisms of allergic reactions in the occurrence and development of ETD, and explores the potential role of anti-allergic therapy in managing this condition, in order to provide new insights into the pathogenesis and prevention of ETD.

IL-1α, IL-6 and IL-8 serum values in patients with chronic suppurative otitis media

Inflammatory mediators play an important role in the pathogenesis of otitis media by initiating and maintaining an inflammatory response to infection. The presence of inflammatory mediators may be one of the reasons, in some patients, for acute otitis media transforming into chronic otitis media. The present study included 60 patients admitted to the Clinical Rehabilitation Hospital, Iasi, Romania, for surgery. The control group comprised 30 healthy individuals. Serum levels of interleukin 1α (IL-1α), interleukin 6 (IL-6) and interleukin 8 (IL-8) were measured prior to surgery and were compared among patients with chronic suppurative otitis media (CSOM), cholesteatoma and cholesteatoma recidivism and the control group. High serum levels of interleukins were recorded in all the groups compared to the healthy control group. IL-6 and IL-8 had the highest value in patients with CSOM and IL-1α had the highest value in patients with cholesteatoma recidivism. Thus, we can consider that inflammatory mediators play a central role in the pathogenesis of CSOM and cholesteatoma by maintaining a systemic and local inflammatory response.

Aetiology and pathology of otitis media with effusion in adult life

OBJECTIVES

To gather and analyse information concerning the aetiology and pathology of otitis media with effusion in adults.

METHOD

A review of the English language literature from 1970 to the present was conducted.

RESULTS

The available evidence suggests that otitis media with effusion in adult life is best viewed as a syndrome with a number of causes, including: infiltration of the eustachian tube by nasopharyngeal carcinoma and other local malignancies; changes in the middle ear and eustachian tube induced by radiotherapy; and systemic disease.

CONCLUSION

There is now a body of evidence specifically related to the aetiology and pathology of otitis media with effusion in adult life. However, further research is required to fill in the gaps in our knowledge and understanding of this condition.

Evaluation of 15 functional candidate genes for association with chronic otitis media with effusion and/or recurrent otitis media (COME/ROM)

DNA sequence variants in genes involved in the innate immune response and secondary response to infection may confer susceptibility to chronic otitis media with effusion and/or recurrent otitis media (COME/ROM). We evaluated single nucleotide polymorphisms (SNPs) in 15 functional candidate genes. A total of 99 SNPs were successfully genotyped on the Sequenom platform in 142 families (618 subjects) from the Minnesota COME/ROM Family Study. Data were analyzed for association with COME/ROM using the Generalized Disequilibrium Test (GDT). Sex and age at exam were adjusted as covariates, relatedness was accounted for, and genotype differences from all phenotypically discordant relative pairs were utilized to measure the evidence of association between COME/ROM and each SNP. SNP rs2735733 in the region of the mucin 5, subtypes A/C gene (MUC5AC) exhibited nominal evidence for association with COME/ROM (P = 0.002). Two additional SNPs from this region had P values<0.05. Other variants exhibiting associations with COME/ROM at P<0.05 included the SCN1B SNP rs8100085 (P = 0.013), SFTPD SNP rs1051246 (P = 0.039) and TLR4 SNP rs2770146 (P = 0.038). However, none of these associations replicated in an independent sample of COME/ROM families. The candidate gene variants examined do not appear to make a major contribution to COME/ROM susceptibility, despite a priori evidence from functional or animal model studies for a role in COME/ROM pathology.

Cigarette smoke activates NFκB-mediated Tnf-α release from mouse middle ear cells

OBJECTIVES/HYPOTHESIS

: Cigarette smoke exposure is a significant risk factor in the development of otitis media. NF-κB is a transcription factor known to mediate cigarette smoke effects in multiple cell types. We hypothesized that stimulation of murine middle ear epithelial cells (MEEC) with cigarette smoke condensate (CSC) activates NF-κB resulting in upregulation of proinflammatory cytokines.

STUDY DESIGN

: In vitro model of cultured murine middle ear epithelial cells.

METHODS

: Time course CSC stimulation of MEEC was performed. Antibody microarrays were then utilized to simultaneously measure 40 inflammatory cytokines. Enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcriptase-polymerase chain reaction were performed to validate and further evaluate array results. Luciferase reporter assays were performed to evaluate NF-κB activation with CSC in MEEC. Chromatin immunoprecipitation (ChIP) assays were performed to determine whether CSC induces NF-κB interaction with the Tnf-α promoter.

RESULTS

: Multiple cytokines showed significant increases with CSC exposure. ELISA studies demonstrated that Tnf-α secretion increased the most. CSC stimulation likewise increased Tnf-α mRNA abundance and induced promoter activity 4.8-fold in a Tnf-α reporter plasmid. Reporter assays demonstrated 4.84-fold activation of NF-κB with CSC. ChIP assays demonstrated NF-κB binding to canonical κB sites in the Tnf-α promoter with CSC stimulation.

CONCLUSIONS

: CSC activates NF-κB in MEEC. Furthermore, this activation results in CSC induced Tnf-α promoter activation, gene expression, and levels in cell secretions. Laryngoscope, 120:2508-2515, 2010.

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.

Interleukin-8 secretion of human epithelial and monocytic cell lines induced by middle ear pathogens

Otitis media with effusion (OME) is one of the most common diseases in children. Alloiococcus otitidis, a new gram-positive bacterial species, was isolated from the middle ear fluid of children with OME; however, the pathogenic role of this bacteria is yet unknown. In this study, the ability of cultured epithelial cell lines (Hep-2 and Hela) and monocytic cell lines (THP-1 and U 937) to secrete chemokine interleukin-8 (IL-8) in response to the A. otitidis organism and three bacterial organisms mainly detected from middle ear fluid in OME, and bacterial cell components was investigated. When stimulated with four viable bacterial cells, epithelial cells and monocytes secreted IL-8 in a time-dependent manner. The monocytes produced significantly higher levels of IL-8 than the epithelial cells. Compared with that by viable bacterial cells, IL-8 secretion by stimulated epithelial cells and monocytes was reduced when the bacteria were heated and treated with glutaraldehyde. With bacterial stimulations, cell treatment of interferon-gamma caused monocytes to increase the induction of IL-8 production, however, the induction of monocyte differentiation caused monocytes to reduce the induction of IL-8 production. Furthermore, epithelial cells and monocytes stimulated by four viable bacterial organisms physically separated from cultured cells reduced the induction of IL-8 compared with directly stimulated cells, and monocytes stimulated with soluble extracts prepared from A. otitidis organisms produced IL-8 in a dose-dependent manner. These results suggest that part of the IL-8 stimulation of the A. otitidis organism may exist in a diffusable factor released by the bacteria or soluble components of the bacteria itself.

Soluble L-selectin and interleukin-8 in otitis media with effusion

OBJECTIVE

adhesion of leukocytes to vascular endothelium and their invasion into local tissues are important steps in inflammation. L-selectin plays a crucial role in leukocyte rolling and adhesion on endothelial cell surface. Interleukin-8 (IL-8) is a potent chemotactic substance toward neutrophils and lymphocytes-T and mediate their migration to local inflammation. The levels of soluble L-selectin (sL-selectin) and IL-8 were measured in middle ear effusions (MEE) from children with otitis media (OM) to estimate their role in pathogenesis of inflammation in middle ear.

METHODS

MEE were collected from 113 ears of 62 children during routine myringotomy. The entire specimen was diluted with phosphate-buffered saline (PBS) to 2 ml and centrifugated at 1500 rpm for 15 min to separate cellular components. Supernatants of MEE were stored frozen at -20 degrees C for sL-selectin and at -80 degrees C for IL-8 assessment. The concentration of sL-selectin and IL-8 were estimated with ELISA and compared with total protein concentration measured by Bradford assay.

RESULTS

MEEs from children with chronic mucous otitis media contained significantly higher mean concentrations of IL-8 559.4 pg/mg total protein (TP) (+/-535.6) in comparison with normal serum 17.79 pg/mg TP (+/-10.9), serous OM 40.3 pg/mg TP (+/-28.1) and purulent OM 104.4 pg/mg TP (+/-128.6). High concentration of IL-8 was found in MEE from the children with early recurrence of OMS. The levels of sL-selectin were higher in purulent effusions 77.2 ng/mg TP (+/-67.4) than those of chronic mucoid 27.6 ng/mg TP (+/-36.7) and serous OM 26.3 ng/mg TP (+/-27.1).

CONCLUSION

the results support a hypothesis that IL-8 can be responsible for prolongation of inflammatory process in middle ear, therefore long-term treatment and observation of children with the high levels of IL-8 in MEE may be necessary. Elevated level of sL-selectin in acute OM suggests the involvement of L-selectin in the acute phase of OM.

Otitis media: the chinchilla model

Streptococcus pneumoniae infection and disease have been modeled in several animal species including infant and adult mice, infant and adult rats, infant Rhesus monkeys, and adolescent and adult chinchillas. Most are models of sepsis arising from intravenous or intraperitoneal inoculation of bacteria, and a few were designed to study disease arising from intranasal infection. Chinchillas provide the only animal model of middle ear pneumococcal infection in which the disease can be produced by very small inocula injected into the middle ear (ME) or intranasally, and in which the disease remains localized to the ME in most cases. This model, developed at the University of Minnesota in 1975, has been used to study pneumococcal pathogenesis at a mucosal site, immunogenicity and efficacy of pneumococcal capsular polysaccharide (PS) vaccine antigens, and the kinetics and efficacy of antimicrobial drugs. Pathogenesis experiments in the chinchilla model have revealed variation in ME virulence among different pneumococcal serotypes, enhancement of ME infection during concurrent intranasal influenza A virus infections, and natural resolution of pneumococcal otitis media (OM) without intervention. Research has explored the relative contribution of pneumococcal and host products to ME inflammation. Pneumococcal cell wall components and pneumolysin have been studied in the model. Host inflammatory responses studied in the chinchilla ME include polymorphonuclear leukocyte oxidative products, hydrolytic enzymes, cytokine and eicosanoid metabolites, and ME epithelial cell adhesion and mucous glycoprotein production. Both clinical (tympanic membrane appearance) and histopathology (ME, Eustachian tube, inner ear) endpoints can be quantified. Immunologic and inflammatory studies have been facilitated by the production of affinity-purified antichinchilla immunoglobulin G (IgG), IgM, and secretory IgA polyclonal antibody reagents, and the identification of cross-reactivity between human and chinchilla cytokines, and between guinea pig and chinchilla C3. Alteration of ME mucosa by pneumococcal neuraminidase and alteration of ME epithelial cell (MEEC) surface carbohydrates during intranasal pneumococcal infection have been demonstrated. Pathogenesis studies have been aided by cultured chinchilla MEEC systems, in which the ability of platelet activating factor and interleukin (IL)-1 beta to stimulate epithelial mucous glycoprotein synthesis has recently been demonstrated. Because chronic OM with effusion is characterized by presence of large amounts of mucous glycoprotein in the ME, pneumococcus may have an important role in both acute and chronic ME disease. Both unconjugated PS and PS-protein-conjugated vaccines are immunogenic after intramuscular administration without adjuvant in chinchillas. Passive protection studies with human hyperimmune immunoglobulin demonstrated that anti-PS IgG alone is capable of protecting the chinchilla ME from direct ME challenge with pneumococci. Active PS immunization studies demonstrated protection following direct ME and intranasal pneumococcal challenge with and without concurrent influenza A virus infection. An attenuated influenza A virus vaccine also showed protection for pneumococcal OM. Antimicrobial treatment of acute OM has been based almost exclusively on empirical drug use and clinical trials without a foundation of ME pharmacokinetics. Studies in the chinchilla model have started to bring a rational basis to drug selection and dosing. Microassays have been developed using high-pressure liquid chromatography for many relevant drugs. Studies have explored the in vivo ME response in pneumococcal OM to antimicrobial drugs at supra- and sub-minimum inhibitory concentration (MIC), the effect of concurrent influenza A virus infection on ME drug penetration, and the effect of treatment on sensorineural hearing loss produced by pneumococcal OM.

Interleukin 8 in middle ear fluid during acute otitis media: correlation with aetiology and bacterial eradication

OBJECTIVES

To study the concentration of interleukin 8 (IL-8) in the middle ear fluid of children with acute otitis media and the association between IL-8 concentrations, aetiology of acute otitis media, and bacteriological sterilisation.

STUDY DESIGN

Middle ear fluid was obtained by tympanocentesis at enrollment (day 1) and on day 4-5 in 81 children aged 3-36 months with acute otitis media who received antibiotic treatment. IL-8 concentrations were measured by enzyme linked immunosorbent assay.

RESULTS

101 samples were obtained on day 1 and 47 samples on day 4-5. 94 pathogens were isolated in 79 of 101 samples obtained on day 1: 56 Haemophilus influenzae, 35 Streptococcus pneumoniae, 2 Moraxella catarrhalis, and 1 Streptococcus pyogenes. Among 40 paired, initially culture positive samples, sterilisation was achieved on day 4-5 in 22 but not in 18 (13 H influenzae, 2 S pneumoniae, and 3 H influenzae and S pneumoniae concomitantly). IL-8 was detected in 96 of 101 and 46 of 47 samples obtained on days 1 and 4-5, respectively. Mean (SD) IL-8 concentration on day 1 was significantly higher in culture positive than in negative samples (12,636 (23,317) v 5,920 (7,080) pg/ml). In paired samples, IL-8 concentration fell in 12 of 22 ears in which sterilisation was achieved and in 9 of 21 ears with persistent or new infection. Mean (SD) IL-8 concentrations on day 4-5 were significantly higher in culture positive than in negative samples (15,420 (15,418) v 6,695 (5,092) pg/ml).

CONCLUSIONS

Higher IL-8 concentrations are found in culture positive middle ear fluid in acute otitis media. Bacterial eradication is associated with a fall in these concentrations.

Cytokine-mediated bone resorption is cytochrome P-450 dependent. Student Research Award 1998

Localized bone loss leads to much of the morbidity of chronic otitis media. Although the cellular events of bone remodeling have been well established, their regulation remains poorly understood. Various cytokines, including tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma, used alone and in combination, are powerful inducers of bone resorption. One of the modulators of cytokine-induced bone resorption is nitric oxide (NO), a product of the action of NO synthase (NOS) on L -arginine to form NO. Cytochrome P-450, an enzyme that is similar to NOS both structurally and functionally, may also have a role in NO production in various cellular systems. The goal of this study was to elucidate a possible role of cytochrome P-450 in bone. In this study cytokine-induced bone resorption was blocked with cimetidine and clotrimazole, which are selective inhibitors of the cytochrome P-450 IIIA family and 7-ethoxyresorufin, a nonspecific cytochrome P-450 inhibitor. A concomitant reduction of NO was also observed. This effect may be explained by cytochrome P-450 being a preferred alternative pathway or providing an essential cofactor to NOS in bone.

Course of IL-1beta, IL-6, IL-8, and TNF-alpha in the middle ear fluid of the guinea pig otitis media model induced by nonviable Haemophilus influenzae

To characterize the local response in acute otitis media, courses of interleukin (IL)-1beta, IL-6, IL-8, and tumor necrosis factor (TNF)alpha in middle ear fluid (MEF) of the guinea pig otitis media model induced by nonviable Haemophilus influenzae were investigated with enzyme-linked immunosorbent assay (ELISA) kits. The IL-1beta concentration in H. influenzae-inoculated ears peaked 24 hours after inoculation. The IL-8 concentration was significantly higher in H. influenzae-inoculated ears than in controls 48 and 96 hours after inoculation. The TNF-alpha concentration in H. influenzae-inoculated ears had an initial peak 6 hours after inoculation and had significant late increases 48 and 96 hours after inoculation. The results suggest that IL-1beta and TNF-alpha were produced by middle ear mucosa in the early stage of the experiment by stimulation of bacterial inoculation, which caused subsequent inflammatory cell accumulation, and that IL-8 and TNF-alpha were produced in the late stage by accumulating inflammatory cells.

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.

Cytokine gene expression in nasal polyps

Nasal polyps are the most common mass lesion of the nasal cavity. Various pathogenetic mechanisms have been proposed. However, the cause is still largely unknown, and treatment methods have not been changed for several hundred years. In order to investigate the role of cytokines in the pathogenesis of nasal polyps, expression of cytokine messenger RNAs (mRNAs) in nasal polyps was investigated. We performed reverse transcriptase-polymerase chain reaction and Southern blot to examine gene expression of the cytokines interleukin (IL)-1 beta, IL-6, IL-8, transforming growth factor (TGF)-beta, IL-4, IL-5, and interferon (IFN)-gamma and compared the results with the gene expressions of these cytokines in normal nasal mucosa. Nasal polyp tissues were obtained from 14 patients undergoing polypectomy for nasal obstruction. Among them, 4 patients suffered from associated perennial allergic rhinitis. The mRNAs of IL-4 and IL-5 (Th2 cytokines) as well as IFN-gamma (Th1 cytokine) were expressed in all of the nasal polyps obtained from the 14 patients, irrespective of the presence or absence of allergy, while 2, 0, and 4 of 6 normal turbinate mucosae expressed IL-4, IL-5, and IFN-gamma mRNAs, respectively. The mRNAs of IL-1 beta, IL-6, IL-8, and TGF-beta were expressed in 6, 1, 2, and 3 of 6 normal turbinate mucosae, respectively, while the mRNAs of these cytokines were expressed in all of the 14 polyp tissues except IL-6 mRNA, which was expressed in 13 nasal polyp tissues. There were no differences in the mean density ratios of each cytokine band on Southern blot between polyp tissues with allergy and those without allergy. These results suggest that many cytokines are produced in nasal polyps, that they may play important roles in the pathogenesis of nasal polyps, and that allergy per se may not play a fundamental role in the pathogenesis of nasal polyps.

Gammadelta T cell receptor repertoire in middle ear effusions in children

In order to elucidate the immune response in otitis media with effusion, polymerase chain reaction was employed to examine gammadelta T cell receptor repertoire in the middle ear effusions of patients with otitis media with effusion. RNAs were extracted from 13 middle ear effusions of 10 children with otitis media with effusion. Vgamma2 was the most frequently used Vgamma gene. As for Vdelta gene usage, Vdelta2 amplification gave the strongest signal in 10 out of 13 samples. The results suggest that gammadelta T cells bearing Vgamma2/Vdelta2 T cell receptors accumulate in the middle ear effusions in children, and that these T cells may respond to certain bacteria or bacterial products in the middle ear.

Murine model of interleukin-8-induced otitis media

Interleukin-8 (IL-8), a potent inflammatory mediator that is thought to control leukocyte recruitment and activation during inflammatory reactions, has been implicated in a variety of inflammatory diseases. Recent studies in our laboratory have demonstrated the presence of IL-8 in chronically inflamed human middle ear effusions. These data have led us to hypothesize that IL-8 is responsible for the leukocyte recruitment seen in otitis media. Because the effect of IL-8 on the middle ear mucosa has not been investigated and therefore its role in middle ear inflammation is not known, we investigated the ability of IL-8 to directly induce inflammation in the murine middle ear. For these studies, ICR mice were used to test the hypothesis that IL-8 could directly induce inflammation in the middle ear. Murine middle ears received 8-mL transtympanic injections of human IL-8 (25 mg/mL) in saline, heat-killed Streptococcus pneumoniae (1 x 10(8)/mL), or normal saline. Temporal bones were removed at 1, 4, 8, 24, and 48 hours, decalcified, and processed for histologic examination. Noninjected murine temporal bones served as controls. Normal saline-injected ears demonstrated little to no change as compared with temporal bones from noninjected ears. IL-8-injected ears histologically demonstrated thickening of the epithelial layer and subepithelial space (SES), with inflammatory cell infiltration in the SES peaking at 4 to 8 hours and resolving by 48 hours. Bacteria-injected ears demonstrated findings similar to, although not as extensive as, those found in IL-8-injected ears (i.e., inflammatory reactions peaked at 8 to 24 hours and resolved by 72 hours). Our results demonstrate that IL-8 is a potent inducer of middle ear inflammation and support the concept that IL-8 may be one of the key cytokines responsible for the leukocyte accumulation and activation seen in otitis media.

In vivo induction and regulation of interleukin-8-like chemokine GRO/CINC-1 in rat middle ear

Interleukin-8 possesses chemotactic-activating properties toward neutrophils, and may contribute to the pathogenesis of middle ear inflammation. GRO/CINC-1 is a rat chemokine with structural and functional homology to human interleukin-8, the induction and regulation of which in the middle ear cavity in vivo remains to be established. The production of GRO/CINC-1 in middle ear lavage and gene expression in the middle mucosa was investigated using topical inoculation with lipopolysaccharide (LPS) in the rat in vivo model. GRO/CINC-1 in middle ear lavage showed time- and dose-dependent production under LPS stimulation. The peak of the GRO/CINC-1 production was reached by 4 h after LPS 1 h exposure, whereas the level of production subsequently returned to the level without LPS stimulation at 8 h after LPS stimulation. The topical corticosteroid perfusion in the middle ear after LPS stimulation significantly reduced the production of GRO/CINC-1 in the middle ear cavity compared with that without corticosteroid. At the time of peak production, the expression of GRO/CINC-1 mRNA, evaluated using the polymerase chain reaction, was considerable in the middle ear mucosa. This investigation of the characteristics of interleukin-8-like cytokine in the middle ear cavity using a rat in vivo model has extended the functional concept of chemokines at the initial stage in otitis media.

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

Interleukin-8 (IL-8), a potent neutrophilic chemoattractant and inflammatory cytokine, is present in middle ear effusions (MEEs) of children with otitis media and is thought to be responsible for the accumulation of neutrophils in MEEs. We hypothesized that IL-8 concentration predicts the total number and proportion of neutrophils in MEEs. IL-8 concentration and total and differential cell counts were measured in MEEs of children undergoing tympanostomy tube placement for otitis media. IL-8 was present in 80 (98%) of 82 effusions. The mean +/- SEM value for IL-8 was 7342 +/- 847 pg/mL. The mean +/- SEM count and percentage of neutrophils were 1.34 x 10(6) +/- 3.44 x 10(5) and 70.6 +/- 3.1%, respectively. IL-8 concentrations correlated positively with the total number (r = +0.30; P = 0.02) and percentage of neutrophils (r = +0.32; P = 0.01) in the effusion. Additionally, purulent effusions had greater IL-8 concentrations (P = 0.003) and greater neutrophil count (P = 0.03) than mucoid or serous effusions. We conclude that IL-8 is consistently present in MEEs of children and IL-8 concentration predicts the total number and proportion of neutrophils. Furthermore, IL-8 concentration and the total number of neutrophils correlate positively with the type of effusion. These results support the hypothesis that IL-8 recruits neutrophils to the middle ear in MEEs.

Nitric oxide mediates mucin secretion in endotoxin-induced otitis media with effusion

The mechanisms that regulate mucin release in chronic otitis media with effusion, a leading cause of hearing loss in children, remain largely unknown. We developed an animal model using Sprague-Dawley rats to determine the factors responsible for mucin production in chronic otitis media with effusion. N-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of nitric oxide synthase, was used to investigate the role of nitric oxide in mucin secretion by the middle ear epithelium. All rats underwent eustachian tube obstruction. In the first set of rats, the middle ear was then injected transtympanically with 35 microl of either 300 mOsm Krebs-Ringer bicarbonate buffer (control group) or 1 mg/ml lipopolysaccharide in Krebs-Ringer (experimental group 1). In a second set of rats, the middle ear space was injected with lipopolysaccharide and then infused at a continuous rate for 7 days with either Krebs-Ringer (experimental group 2) or 1 mmol/L L-NAME in Krebs-Ringer (experimental group 3) through an osmotic infusion pump. After 7 days the volume of effusion and the quantity of mucin collected were significantly greater in lipopolysaccharide-exposed ears than in controls. In addition, antimucin immunostaining demonstrated mucous cell hyperplasia in response to lipopolysaccharide. The lipopolysaccharide-induced production of mucin and mucous cell hyperplasia was inhibited in ears treated with lipopolysaccharide and L-NAME. These results suggest that nitric oxide is a mediator in the pathway of mucin secretion in chronic otitis media with effusion.

Increase in expression of IL-4 and IL-5 mRNA in the nasal mucosa of patients with perennial allergic rhinitis during natural allergen exposure

To understand the role of cytokines in allergic nasal disease in humans, we designed this study to investigate the expression of cytokine mRNA in the nasal mucosa of 10 control subjects and 10 patients with perennial allergic rhinitis using a reverse transcription-polymerase chain reaction (RT-PCR) for IL-4, IL-5 (Th2 cytokines), and IFN-gamma (Th1 cytokine). Both IL-4 and IL-5 mRNAs were expressed in a significantly larger number of patients with allergic rhinitis than in control subjects. When the levels of expression of cytokines and beta-actin mRNA were quantitated, the mean density ratios (cytokine/beta-actin) for IL-4 and IL-5 were higher in patients with allergic rhinitis than in control subjects. In contrast, there were no differences in the number of subjects who showed expression of IFN-gamma mRNA, or in mean density ratios for IFN-gamma between the two groups. This study suggests that both IL-4 and IL-5 mRNAs are expressed almost universally in the nasal mucosa of patients with perennial allergic rhinitis during natural allergen exposure and also that Th2-type cytokines play a crucial role in the development of allergic nasal diseases in vivo.

Inflammatory cytokine expression on nasal polyps developed in allergic and infectious rhinitis

To investigate the expression of cytokine mRNAs in nasal polyps and the role of allergy in the pathogenesis of nasal polyposis, we studied the expression of IL-4, IL-5, and IFN-gamma mRNAs using the RT-PCR and Southern blot. Nasal polyp specimens were obtained from 14 patients with infectious rhinitis and 5 patients with perennial allergic rhinitis. Turbinate mucosa specimens were obtained from 10 patients with allergic rhinitis and from 10 healthy subjects as controls. IL-4, IL-5 and IFN-gamma mRNA were expressed in most specimens of allergic turbinate mucosa. The expression of these cytokines was less frequent in normal healthy turbinate mucosa. The density ratios of IL-4, IL-5 and IFN-gamma to beta-actin were individually determined in both polyp and turbinate tissues. The density ratio for each cytokine was relatively higher in polyp tissues than in healthy turbinate mucosa; however, there was no significant difference in the density ratios determined for polyps associated with allergic rhinitis as compared with polyps associated with infectious rhinitis. These findings indicate that nasal polyposis may differ from allergic rhinitis in the mechanism by which IL-4 and IL-5 are increased. It is concluded that allergy may have an insignificant role in the development of nasal polyps.

Roles of autolysin and pneumolysin in middle ear inflammation caused by a type 3 Streptococcus pneumoniae strain in the chinchilla otitis media model

Streptococcus pneumoniae cell wall and pneumolysin are important contributors to pneumococcal pathogenicity in some animal models. To further explore these factors in middle ear inflammation caused by pneumococci, penicillin-induced inflammatory acceleration was studied by using three closely related pneumococcal strains: a wild-type 3 strain (WT3), its pneumolysin-negative derivative (P-1), and into autolysin-negative derivative (A-1). Both middle ears of chinchillas were inoculated with one of the three pneumococcal strains. During the first 12 h, all three strains grew in vivo at the same rate, and all three strains induced similar inflammatory cell responses in middle ear fluid (MEF). Procaine penicillin G was given as 12 h to one-half of the animals in each group, and all treated chinchillas had sterile MEF at 24 h. Penicillin significantly accelerated MEF inflammatory cell influx into WT3-and P-1-infected ears at 18 and 24 h in comparison with the rate for penicillin-treated A-1-infected ears. Inflammatory cell influx was slightly, but not significantly, greater after treatment of WT3 infection than after treatment of P-1 infection. Interleukin (IL)-1beta and IL-6, but not IL-8, concentrations in MEF at 24 h reflected the penicillin effect on MEF inflammatory cells; however, differences between treatment groups were not significant. Results suggest that pneumococcal otitis media pathogenesis is triggered principally by the inflammatory effects of intact and lytic cell wall products in the middle ear, with at most a modes additional pneumolysin effect. Investigation strategies that limit the release of these products or neutralize them warrant further investigation.

Analysis of T cell receptor beta chain repertoire in middle ear effusions

In order to elucidate the immune response in otitis media with effusion (OME), the polymerase chain reaction was employed to examine T cells in middle ear effusions in patients with OME for utilization of T cell receptor (TCR) variable region genes. Specimens of RNA were extracted from 13 ears of 12 patients (9 children and 3 adults). Oligonucleotide primers specific for individual TCR Vbeta gene families were used to amplify TCR gene products in each sample. Although the number of Vbeta families utilized by each sample varied from 1 family to 21, a few significant trends emerged. Eleven ears out of 13 expressed Vbeta7, which was the most frequently utilized (84.6%) Vbeta family among the 24 Vbeta families. In 5 of the 13 samples, the number of Vbeta families utilized was restricted to 1, which was Vbeta7 in all 5 samples. This result indicates the possibility that Vbeta7-bearing T cells in the middle ear are responding to a certain common antigen in some cases of OME.