Immunologic aspects of otitis media

Serum Aspergillus fumigatus-Specific IgG as a Complementary Biomarker in Differentiating Endotypes of Chronic Rhinosinusitis: A Study on Its Role and Diagnostic Efficacy in Type 2 Inflammation

BACKGROUND

Aspergillus is one of the most common pathogens causing fungal allergy in the respiratory tract. Serum Aspergillus fumigatus-specific immunoglobulin G (Af-sIgG) levels have been used as a biomarker for the diagnosis and treatment response monitoring in airway allergic diseases such as allergic bronchopulmonary aspergillosis and allergic fungal rhinosinusitis. However, its role in common primary chronic rhinosinusitis (CRS) was unclear.

OBJECTIVE

This study aims to evaluate whether serum Af-sIgG level could serve as a biomarker for the disease presentation of primary CRS.

METHODS

We obtained serum Af-sIgG levels from patients diagnosed as bilateral primary CRS refractory to medical treatment and evaluated the correlations between serum Af-sIgG levels and disease severity in patients with type 2 (T2) and non-T2 CRS.

RESULTS

Patients with T2 CRS exhibited significantly higher serum Af-sIgG levels than non-T2 CRS patients. The cut-off value of serum Af-sIgG in T2 CRS was 20.9 mg/L, with an odds ratio of 3.8 (95% CI 1.17-12.20, P = .026). Furthermore, serum Af-sIgG levels were positively correlated with symptom scores evaluated by the Sino-Nasal Outcome Test-22 (SNOT-22) scores in T2 patients (P = .009). While stratified by SNOT-22 total scores, patients with severe disease had higher serum Af-sIgG levels only in T2 CRS (P = .034). In individual domains of SNOT-22 analysis, serum Af-sIgG levels showed a significant correlation with "ear/facial" symptom scores in the T2 group (P < .001).

CONCLUSIONS

Serum Af-sIgG levels may serve as a supplementary objective biomarker that correlates with identification and subjective measurements of T2 CRS, and may be associated with symptoms arising from Eustachian tube dysfunction.

[The pressure-equalizing function of the Eustachian tube : Evaluation in a hypo-/hyperbaric pressure chamber]

BACKGROUND

The Eustachian tube connects the tympanic cavity (cavum tympani) and the nasopharynx, and enables pressure equalization between the middle ear and ambient pressure. Functional pressure compensation is very important for flying and diving in particular, due to non-physiologically large pressure differences.

OBJECTIVE

Evaluation of the pressure-equalizing function of the Eustachian tube is still a clinical challenge. This review article evaluates the existing data.

METHODS

Based on a selective literature search, different methods for evaluation of tube function are presented and evaluated, with special reference to evaluation of the pressure-equalizing function in a hypo-/hyperbaric pressure chamber.

RESULTS

The pressure chamber enables the dynamics of active and passive pressure compensation to be provoked and also permits accurate measurement of pressures in the millibar range.

CONCLUSION

A pressure chamber seems to be suitable to evaluate Eustachian tube function and therapeutic approaches to tube dysfunction. Further studies are needed to assess the value of the pressure chamber in combination with other functional tests.

Characterizing the active opening of the eustachian tube in a hypobaric/hyperbaric pressure chamber

OBJECTIVE

Active and passive opening of the Eustachian tube (ET) enables direct aeration of the middle ear and a pressure balance between middle ear and the ambient pressure. The aim of this study was to characterize standard values for the opening pressure (ETOP), the opening frequency (ETOF), and the opening duration (ETOD) for active tubal openings (Valsalva maneuver, swallowing) in healthy participants.

DESIGN/PARTICIPANTS

In a hypobaric/hyperbaric pressure chamber, 30 healthy participants (19 women, 11 men; mean age, 25.57 ± 3.33 years) were exposed to a standardized profile of compression and decompression. The pressure values were recorded via continuous impedance measurement during the Valsalva maneuver and swallowing. Based on the data, standard curves were identified and the ETOP, ETOD, and ETOF were determined.

RESULTS

Recurring patterns of the pressure curve during active tube opening for the Valsalva maneuver and for active swallowing were characterized. The mean value for the Valsalva maneuver for ETOP was 41.21 ± 17.38 mbar; for the ETOD, it was 2.65 ± 1.87 seconds. In the active pressure compensation by swallowing, the mean value for the ETOP was 29.91 ± 13.07 mbar; and for the ETOD, it was 0.82 ± 0.53 seconds.

CONCLUSION

Standard values for the opening pressure of the tube and the tube opening duration for active tubal openings (Valsalva maneuver, swallowing) were described, and typical curve gradients for healthy subjects could be shown. This is another step toward analyzing the function of the tube in compression and decompression.

Divergent mucosal and systemic responses in children in response to acute otitis media

Acute otitis media (AOM), induced by respiratory bacteria, is a significant cause of children seeking medical attention worldwide. Some children are highly prone to AOMs, suffering three to four recurrent infections per year (prone). We previously determined that this population of children could have diminished anti-bacterial immune responses in peripheral blood that could fail to limit bacterial colonization in the nasopharynx (NP). Here, we examined local NP and middle ear (ME) responses and compared them to peripheral blood to examine whether the mucosa responses were similar to the peripheral blood responses. Moreover, we examined differences in effector cytokine responses between these two populations in the NP, ME and blood compartments at the onset of an AOM caused by either Streptococcus pneumoniae or non-typeable Haemophilus influenzae. We found that plasma effector cytokines patterned antigen-recall responses of CD4 T cells, with lower responses detected in prone children. ME cytokine levels did not mirror blood, but were more similar to the NP. Interferon (IFN)-γ and interleukin (IL)-17 in the NP were similar in prone and non-prone children, while IL-2 production was higher in prone children. The immune responses diverged in the mucosal and blood compartments at the onset of a bacterial ME infection, thus highlighting differences between local and systemic immune responses that could co-ordinate anti-bacterial immune responses in young children.

New insights into mechanism of Eustachian tube ventilation based on cine computed tomography images

There is debate concerning the mechanism of Eustachian tube (ET) ventilation. While a mechanism of complete opening has been advocated previously, sequential contraction of the levator veli palatini and medial pterygoid muscles followed by the tensor veli palatini and lateral pterygoid muscles may produce a transient sequential opening mechanism, allowing an air bolus to traverse the ET. This may explain confusion surrounding sonotubometry reports that not every swallow leads to sound passage in normal subjects. We hypothesize that the ET may not need to open completely when ventilating the middle ear; rather, a discrete air bolus can pass through it. Five normal and five disordered subjects underwent low-radiation dose cine computed tomography (CT) scans of the ET. Sixteen contiguous 2.5 mm slice locations were chosen through a 4 cm area in the nasopharynx that were parallel to and encompassed the entire ET. Twelve images were acquired at each slice over 4.8 s during swallowing and other tasks. Serial images were analyzed. An air bolus was observed passing through the ET in the normal subjects, but not the subject with ET dysfunction. Medial and lateral pterygoid contractions were also observed. A new hypothetical mechanism of transient sequential ET ventilation is presented. This is not a definitive conclusion, as the number of scans taken and maneuvers used was limited. Improved understanding of ET ventilation may facilitate management of middle ear disease as treatment evolves from ventilatory tube placement to ET manipulation.

Otitis media: viruses, bacteria, biofilms and vaccines

Otitis media typically presents as either acute otitis media (AOM), with symptoms including fever, otalgia, otorrhoea or irritability and short duration; or as otitis media with effusion (OME), which is often asymptomatic and characterised by accumulation of fluid in the middle ear.

Diagnostic certainty of otitis media is challenging, given the young age of patients and variability of symptoms.

Otitis media predominantly occurs as coincident to viral upper respiratory tract infections and/or bacterial infections.

Common viruses that cause upper respiratory tract infection are frequently associated with AOM and new‐onset OME. These include respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza and coronavirus.

Predominant bacteria that cause otitis media are Streptococcus pneumoniae, Moraxella catarrhalis, and non‐typeable Haemophilus influenzae.

Antibiotic therapy does not significantly benefit most patients with AOM, but long‐term prophylactic antibiotic therapy can reduce the risk of otitis media recurrence among children at high risk.

In Australia, 84% of AOM is treated with antibiotic therapy, which contributes to development of antibiotic resistance.

Vaccine development is a key future direction for reducing the world burden of otitis media, but requires polymicrobial formulation and ongoing monitoring and modification to ensure sustained reduction in disease burden.

Role of nasal allergy in chronic secretory otitis media

Nasal allergy seems to be one of the important causes of chronic secretory otitis media (SOM) in children and adults. Chronic SOM is unequivocally related to disturbed function of the eustachian tube, which facilitates communication of the middle ear with the nasopharynx, nasal cavity, and indirectly with paranasal sinuses. The most serious consequences of chronic SOM are decreased elasticity of the tympanic membrane and hearing impairment. Allergic reactions in the nasal mucosa leading to release of various mediators result in development of three types of nasal response characterized predominantly by nasal obstruction. Eustachian tube functions can be affected directly by the mediators released in the nasal mucosa or indirectly by the nasal obstruction. Nasal challenges with allergens performed by rhinomanometry, combined with tympanometry and eventually audiometry, may be a useful diagnostic supplement for this disorder.

Nasal prostaglandin challenge increases N2O exchange from blood to middle ear

Nasal inflammation (NI) resulting from allergy or virus infection is causally associated with otitis media. Impaired Eustachian tube (ET) function consequent to NI may mediate this relationship. Moreover, the functional demand placed upon the ET for gas supply may be increased by NI, a hypothesis tested here. A total of five experiments were done at a minimum 2-week interval on four monkeys. For each experiment, the monkey was anesthetized and acclimated for 60 min. Then, the monkey was breathed with a 40% N2O gas mixture for 60 min followed by air breathing for 100 min. Fifteen minutes into air breathing, the nose was challenged with one of the five substances: saline, PGD2, capsaicin, histamine or bradykinin. Throughout, middle ear (ME) pressures were recorded at 5-min intervals. All pressure-time curves had a similar form consisting of a curvilinear decrease during acclimation, a linear increase during N2O breathing and a linear decrease during air breathing. The rates of pressure increase were ear-specific and not different across experiments. Compared to saline, the rate of pressure decrease was greater for challenge with all the substances and significantly greater after PGD2 challenge. Like N2, N2O is an inert gas whose transmucosal exchange is perfusion-limited for the ME. The measured pressure change is linearly related to the volume gas exchange between ME and blood. Therefore, nasal challenge with PGD2 and perhaps the other substances increases transmucosal inert gas exchange. ME to blood N2 transfer rate determines the physiological demand placed upon the ET for gas supply. That demand is increased by nasal exposure to certain inflammatory mediators.

Birth characteristics and recurrent otitis media with effusion in young children

OBJECTIVE

To study the association between birth characteristics and the recurrence of otitis media with effusion (OME).

METHODS

Prospective cohort study on 136 children aged 2-7 years, who received tympanostomy tubes for bilateral otitis media with effusion. Checkups were planned 1 week after tube insertion and once every 3 months thereafter. An otologist examined the ear status to assess tube extrusion and otitis media with effusion recurrence. Outcome measure was the recurrence of otitis media with effusion within 6 months after documentation of spontaneous tube extrusion. Birth characteristics were investigated in relation with the recurrence of otitis media with effusion in 90 children with known clinical outcome.

RESULTS

No statistically significant associations were found between various birth characteristics and the recurrence of otitis media with effusion. Multivariate analyses showed positive but fairly weak associations between recurrence of otitis media with effusion and low birth weight (<2500 g) and/or low gestational age (<37 weeks) and/or a history of incubator care (odds ratio (OR) 1.95, 95% confidence interval (CI): 0.21-18.2), male sex (OR 1.85, 95% CI: 0.56-6.13) and maternal medication use during pregnancy (OR 4.80, 95% CI: 0.57-40.72). A remarkable finding was the asymmetrical distribution of certain birth characteristics within the group of children with recurrence of otitis media with effusion: children with unilateral recurrence had a relatively lower gestational age, lower birth weight, lower 'birth length to birth weight' ratio than the children with bilateral recurrence.

CONCLUSION

These findings suggest that determination of birth characteristics cannot help us in the treatment strategy for recurrent otitis media with effusion in childhood.

Morbilliviruses and human disease

Morbilliviruses are a group of viruses that belong to the family Paramyxoviridae. The most instantly recognizable member is measles virus (MV) and individuals acutely infected with the virus exhibit a wide range of clinical symptoms ranging from a characteristic mild self-limiting infection to death. Canine distemper virus (CDV) and rinderpest virus (RPV) cause a similar but distinctive pathology in dogs and cattle, respectively, and these, alongside experimental MV infection of primates, have been useful models for MV pathogenesis. Traditionally, viruses were identified because a distinctive disease was observed in man or animals; an infectious agent was subsequently isolated, cultured, and this could be used to recapitulate the disease in an experimentally infected host. Thus, satisfying Koch's postulates has been the norm. More recently, particularly due to the advent of exceedingly sensitive molecular biological assays, many researchers have looked for infectious agents in disease conditions for which a viral aetiology has not been previously established. For these cases, the modified Koch's postulates of Bradford Hill have been developed as criteria to link a virus to a specific disease. Only in a few cases have these conditions been fulfilled. Therefore, many viruses have over the years been definitely and tentatively linked to human diseases and in this respect the morbilliviruses are no different. In this review, human diseases associated with morbillivirus infection have been grouped into three broad categories: (1) those which are definitely caused by the infection; (2) those which may be exacerbated or facilitated by an infection; and (3) those which currently have limited, weak, unsubstantiated or no credible scientific evidence to support any link to a morbillivirus. Thus, an attempt has been made to clarify the published data and separate human diseases actually linked to morbilliviruses from those that are merely anecdotally associated.

The importance of allergy in the practice of otolaryngology

Allergy in the practice of otolaryngology is not confined to patients with typical hay fever symptoms. The otolaryngologist encounters allergy as a primary cause or secondary contributor to a number of otologic, rhinologic, and laryngologic syndromes and disorders. The practitioner of otolaryngology should be prepared to recognize these situations and to address them appropriately. Training and resources are available to help the physician wishing to achieve this capability, no matter the current level of understanding and expertise.