Cytokine Expression in Experimental Chronic Otitis Media With Effusion in Mice

Maeda, Kazuhiko; Hirano, Takashi; Ichimiya, Issei; Kurono, Yuichi; Suzuki, Masashi; Mogi, Goro

doi:10.1097/01.mlg.0000147930.29261.51

Cited by 25 publications

(20 citation statements)

References 21 publications

(38 reference statements)

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“…TNF-a is produced mainly by macrophages or mast cells and is, among others, responsible for neutrophil migration (Maeda et al, 2004). Along with various other functions, IL-1b contributes to permanent pathological changes in the middle ear, mucosal damage, bone erosion, fibrosis and hearing loss.…”

Section: Discussionmentioning

confidence: 99%

Development of a non-invasive murine infection model for acute otitis media

et al. 2009

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Otitis media (OM) is one of the most frequent diseases in childhood, and Streptococcus pneumoniae is among the main causative bacterial agents. Since current experimental models used to study the bacterial pathogenesis of OM have several limitations, such as the invasiveness of the experimental procedures, we developed a non-invasive murine OM model. In our model, adapted from a previously developed rat OM model, a pressure cabin is used in which a 40 kPa pressure increase is applied to translocate pneumococci from the nasopharyngeal cavity into both mouse middle ears. Wild-type pneumococci were found to persist in the middle ear cavity for 144 h after infection, with a maximum bacterial load at 96 h. Inflammation was confirmed at 96 and 144 h post-infection by IL-1b and TNF-a cytokine analysis and histopathology. Subsequently, we investigated the contribution of two surface-associated pneumococcal proteins, the streptococcal lipoprotein rotamase A (SlrA) and the putative proteinase maturation protein A (PpmA), to experimental OM in our model. Pneumococci lacking the slrA gene, but not those lacking the ppmA gene, were significantly reduced in virulence in the OM model. Importantly, pneumococci lacking both genes were significantly more attenuated than the DslrA single mutant. This additive effect suggests that SlrA and PpmA exert complementary functions during experimental OM. In conclusion, we have developed a highly reproducible and non-invasive murine infection model for pneumococcal OM using a pressure cabin, which is very suitable to study pneumococcal pathogenesis and virulence in vivo.

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Section: Discussionmentioning

confidence: 99%

Development of a non-invasive murine infection model for acute otitis media

et al. 2009

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“…Strain 76 of NTHi, which was isolated from the nasopharynx of a patient with OME at Oita University, was used for the middle ear challenge, and the bacterial suspension was injected into the right tympanic cavity, as described previously (11). NTHi was grown on chocolate agar at 37°C under 5% CO 2 for 16 h. The bacterial concentration was determined by optical density at a wavelength of 600 nm, and then a bacterial suspension was prepared to a concentration of 1.0 ϫ 10 9 CFU/ml in phosphatebuffered saline (PBS) and stored on ice.…”

Section: Methodsmentioning

confidence: 99%

“…A micropipette was inserted into one of the holes, and 10 l (1.0 ϫ 10 7 CFU) of live NTHi suspension was inoculated slowly. Mice without both ET blockage and NTHi inoculation served as controls based on our previous study (11). The mice were monitored otomicroscopically to confirm the presence of MEE and tympanic membrane changes.…”

Section: Methodsmentioning

confidence: 99%

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Accumulation of Regulatory T Cells and Chronic Inflammation in the Middle Ear in a Mouse Model of Chronic Otitis Media with Effusion Induced by Combined Eustachian Tube Blockage and Nontypeable Haemophilus influenzae Infection

et al. 2016

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Nontypeable Haemophilus influenzae (NTHi) is associated with chronic otitis media (COM). In this study, we generated a murine model of COM by using eustachian tube (ET) obstruction and NTHi (10 7 CFU) inoculation into the tympanic bulla, and we investigated the relationship between regulatory T cells (Treg) and chronic inflammation in the middle ear. Middle ear effusions (MEEs) and middle ear mucosae (MEM) were collected at days 3 and 14 and at 1 and 2 months after inoculation. Untreated mice served as controls. MEEs were used for bacterial counts and to measure the concentrations of cytokines. MEM were collected for histological evaluation and flow cytometric analysis. Inflammation of the MEM was prolonged throughout this study, and the incidence of NTHi culture-positive MEE was 38% at 2 months after inoculation. The levels of interleukin-1␤ (IL-␤), tumor necrosis factor alpha, IL-10, and transforming growth factor ␤ were increased in the middle ear for up to 2 months after inoculation. CD4؉ CD25 ؉ FoxP3 ؉ Treg accumulated in the middle ear, and the percentage of Treg in the MEM increased for up to 2 months after inoculation. Treg depletion induced a 99.9% reduction of bacterial counts in MEEs and also significantly reduced the ratio of NTHi culture-positive MEE. The levels of these cytokines were also reduced in MEEs. In summary, we developed a murine model of COM, and our findings indicate that Treg confer infectious tolerance to NTHi in the middle ear. Chronic otitis media (COM), including OM with effusion (OME) and recurrent OM, is characterized by clinical evidence of OM and resolution of middle ear effusion (MEE) between episodes. OME represents a spectrum of chronic disease states, ranging from serous to mucoid OM, and is associated with hearing loss, delayed speech development, permanent middle ear damage, and mucosal changes (1). Although COM remains a common problem in pediatric populations, its etiology and pathogenesis are not fully understood. Eustachian tube (ET) dysfunction is considered to be the underlying pathophysiologic event leading to most cases of OME in children. The most frequent causes of ET dysfunction include upper respiratory infections, adenoid tissue hypertrophy, and cleft palate (2, 3). In bacterial infection of COM, the majority of cases are caused by Gram-negative bacteria, whereas in acute OM, Gram-positive bacteria are also frequently isolated (4). Lipopolysaccharides are a component of Gram-negative bacteria that have been detected in human MEEs (5), and their levels are significantly higher in children with chronic OME than in children with acute OME (6). Lipopolysaccharides alone have also been shown to induce mucosal inflammation with the accumulation of effusion in the middle ears of animal models (7,8). Only 30% of MEEs from COM children yielded an unequivocally positive culture for aerobic bacteria (9). According to previous reports, components from Gram-negative bacteria are thought to induce COM in humans. However, recently, COM was reportedly associated with a persi...

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“…The middle ear has few resident leukocytes, and an infection in the organ results in an influx of neutrophils, macrophages, and lymphocytes (9)(10)(11). Neutrophils have traditionally been considered to play a protective role in OM (12,13).…”

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confidence: 99%

Antibodies Mediate Formation of Neutrophil Extracellular Traps in the Middle Ear and Facilitate Secondary Pneumococcal Otitis Media

et al. 2014

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g Otitis media (OM) (a middle ear infection) is a common childhood illness that can leave some children with permanent hearing loss. OM can arise following infection with a variety of different pathogens, including a coinfection with influenza A virus (IAV) and Streptococcus pneumoniae (the pneumococcus). We and others have demonstrated that coinfection with IAV facilitates the replication of pneumococci in the middle ear. Specifically, we used a mouse model of OM to show that IAV facilitates the outgrowth of S. pneumoniae in the middle ear by inducing middle ear inflammation. Here, we seek to understand how the host inflammatory response facilitates bacterial outgrowth in the middle ear. Using B cell-deficient infant mice, we show that antibodies play a crucial role in facilitating pneumococcal replication. We subsequently show that this is due to antibody-dependent neutrophil extracellular trap (NET) formation in the middle ear, which, instead of clearing the infection, allows the bacteria to replicate. We further demonstrate the importance of these NETs as a potential therapeutic target through the transtympanic administration of a DNase, which effectively reduces the bacterial load in the middle ear. Taken together, these data provide novel insight into how pneumococci are able to replicate in the middle ear cavity and induce disease.

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Cytokine Expression in Experimental Chronic Otitis Media With Effusion in Mice

Cited by 25 publications

References 21 publications

Development of a non-invasive murine infection model for acute otitis media

Development of a non-invasive murine infection model for acute otitis media

Accumulation of Regulatory T Cells and Chronic Inflammation in the Middle Ear in a Mouse Model of Chronic Otitis Media with Effusion Induced by Combined Eustachian Tube Blockage and Nontypeable Haemophilus influenzae Infection

Antibodies Mediate Formation of Neutrophil Extracellular Traps in the Middle Ear and Facilitate Secondary Pneumococcal Otitis Media

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