Immunohistological analysis of eotaxin and RANTES in the model animal of eosinophilic otitis media

Intractable otitis media - Pathogenesis and treatment of Eosinophilic otitis media (EOM) and otitis media with Antineutrophil cytoplasmic antibody (ANCA) -associated vasculitis (OMAAV)

Intractable otitis media is resistant to antimicrobial therapy, tympanostomy ventilation tube insertion, and surgery. In children, intractable acute otitis media, pathological tympanic membrane due to prolonged otitis media with effusion (OME), tympanic membrane atelectasis, and adhesive otitis media are common. Contrarily, in adults, otitis media caused by drug-resistant pathogens, tuberculous otitis media, cholesterol granuloma, malignant otitis externa (skull base osteomyelitis), eosinophilic otitis media (EOM), and otitis media with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (OMAAV) are common and require differentiation. Among them, EOM is increasing along with eosinophilic upper respiratory tract diseases, such as bronchial asthma and eosinophilic chronic rhinosinusitis (ECRS), a subgroup of chronic rhinosinusitis with nasal polyps (CRSwNP). EOM is associated with adult-onset bronchial asthma and is characterized by viscous middle ear effusion and middle ear mucosa thickness with eosinophilic infiltration, which requires treatment with glucocorticoids according to disease activity and symptoms. Recently, OMAAV was proposed because of the similarities in clinical features and therapeutic effects. The clinical course of OMAAV is characterized by a relatively rapid increase in the bone conductive hearing threshold, which progresses over 1-2 months, without response to antimicrobial agents or tympanostomy ventilation tube insertion, and in some cases, is complicated by facial paralysis and hypertrophic pachymeningitis. This new concept may explain the pathogenesis and clinical presentation of many cases of intractable otitis media, the cause of which was previously unknown. Although making a diagnosis of OMAAV is relatively easy based on the clinical course, such as vascular dilatation of the tympanic membrane and positive ANCA titer, it is often difficult because the ANCA titer becomes negative with previous administration of glucocorticoids. In adults with intractable otitis media, ANCA titers must be measured before glucocorticoid administration. Treatment consisted of remission induction therapy with a combination of glucocorticoids and immunosuppressive drugs.

Eosinophilic Otitis Media: Modern Aspects of Pathogenesis, Clinical Features, Diagnosis and Treatment

Eosinophilic otitis media (EOM) is an inflammatory chronic disease of the middle ear, characterized by the presence of a particularly viscous effusion with a high content of protein toxins of eosinophilic origin in the middle ear cavity. The pathology has relationship with bronchial asthma, allergic rhinitis and chronic rhinosinusitis with nasal polyps. EOM is characterized by a sluggish course, a tendency to relapse, which can lead to a gradual hearing decrease up to complete deafness. In this paper, we reviewed the international literature with special attention to pathogenesis and treatment management.

CD11c(+) dendritic cells coexpressing thymic stromal lymphopoietin receptor in animal model of eosinophilic otitis media

Background

Eosinophilic otitis media (EOM) is an intractable middle ear disease often associated with eosinophilic inflammatory airway conditions. Recently, dendritic cells (DCs) have been indicated as an essential component of Th2 allergic inflammation, such as bronchial asthma. DCs are activated by thymic stromal lymphopoietin (TSLP), an epithelial cell-derived cytokine. However, the relationship between TSLP and DCs in EOM remains unknown.

Objective

This study aimed to investigate the relationship between DCs and TSLP and to determine the involvement of DCs in EOM in an animal model.

Methods

Hartley guinea pigs were used as the animal model. Daily ovalbumin (OVA) stimulation of the middle ear was performed for 7 or 14 days. The temporal bone was dissected on the last day of stimulation, and paraffin-embedded sections were prepared. Immunostaining and immunofluorostaining for TSLP receptor (TSLPR) and CD11c, a surface marker of DCs, were performed.

Results

We found CD11c-immunopositive cells in the submucosal area of the middle ear epithelium, particularly around the eustachian tube. TSLPR-immunopositive cells exhibited a similar distribution as CD11c-positive cells.

Conclusion

CD11c positive DCs coexpressing TSLPR were recruited after OVA challenge which might activate Th2 allergic reaction.

Panel 7 - Pathogenesis of otitis media - a review of the literature between 2015 and 2019

OBJECTIVE

To perform a comprehensive review of the literature from July 2015 to June 2019 on the pathogenesis of otitis media. Bacteria, viruses and the role of the microbiome as well as the host response are discussed. Directions for future research are also suggested.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

PubMed was searched for any papers pertaining to OM pathogenesis between July 2015 and June 2019. If in English, abstracts were assessed individually for their relevance and included in the report. Members of the panel drafted the report based on these searches and on new data presented at the 20th International Symposium on Recent Advances in Otitis Media.

CONCLUSIONS

The main themes that arose in OM pathogenesis were around the need for symptomatic viral infections to develop disease. Different populations potentially having different mechanisms of pathogenesis. Novel bacterial otopathogens are emerging and need to be monitored. Animal models need to continue to be developed and used to understand disease pathogenesis.

IMPLICATIONS FOR PRACTICE

The findings in the pathogenesis panel have several implications for both research and clinical practice. The most urgent areas appear to be to continue monitoring the emergence of novel otopathogens, and the need to develop prevention and preventative therapies that do not rely on antibiotics and protect against the development of the initial OM episode.

The expression of thymic stromal lymphopoietin in patients and animal models with eosinophilic otitis media

OBJECTIVE

In the present study, we aimed to clarify the expression of thymic stromal lymphopoietin (TSLP), a key trigger of Th2-type allergic disease, in the middle ear mucosa of eosinophilic otitis media (EOM).

METHODS

An immunohistological study of TSLP was conducted in patients with EOM and in animal models of EOM constructed by intraperitoneal and intratympanic injection of ovalbumin for 7 and 14 days. In addition, the messenger RNA (mRNA) expression of TSLP in the middle ear mucosa of the animal models was analyzed using real-time PCR, and was compared with that of the control animals.

RESULTS

Immunoreactivities for TSLP were observed in the middle ear mucosa around the tympanic ostium of the eustachian tube of patients with EOM. In the animal model, strong immunoreactivity for TSLP was also observed in the eustachian tube epithelium, and mRNA expression of TSLP in the seven-day stimulated animals was significantly higher than that in the controls.

CONCLUSION

The present study indicates that the presence of epithelium-derived TSLP in the eustachian tubes plays an important role in the onset of EOM.