Age-dependent changes in pattern recognition receptor and cytokine mRNA expression in children with otitis media with effusion

Surfactant proteins and innate immunity of otitis media

Otitis media (OM) is the most common disease among young children and one of the most frequent reasons to visit the pediatrician. Development of OM requires nasopharyngeal colonization by a pathogen which must gain access to the tympanic cavity through the eustachian tube (ET) along with being able to overcome the defense mechanisms of the immune system and middle ear mucosa. OM can be caused by viral or bacterial infection. The three main bacterial pathogens are Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis. Innate immunity is important in OM resolution as the disease occurs in very young children before the development of specific immunity. Elements of innate immunity include natural barriers and pattern recognition receptors such as Toll like receptors (TLRs), and Nod like receptors (NLRs). Surfactant proteins A (SP-A) and D (SP-D) act as pattern recognition receptors and are found in the lung and many other tissues including the ET and the middle ear where they probably function in host defense. Surfactant has a potential for use in the treatment of OM due to surface tension lowering function in the ET, and the possible immune functions of SP-D and SP-A in the middle ear and ET.

The Roles of NOD-like Receptors in Innate Immunity in Otitis Media

Acute otitis media (AOM) can persist or lead to various complications in individuals in which the innate immune system is impaired. In this context, impaired expression of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR), an intracellular pathogen-recognition receptor (PRR), is involved in the etiology of OM in humans and animals, affecting its development, severity, chronicity, recurrence, and associated complications. To assess this relationship, we reviewed literature reports relating NLR expression patterns with the pathophysiology and clinical features of OM in the larger context of impaired innate immunity. We summarized the results of published studies on the expression of NLRs in animals and humans in acute otitis media (AOM), otitis media with effusion (OME), chronic otitis media (COM) with cholesteatoma, and COM without cholesteatoma. NLRs were expressed mainly in association with bacterial infection in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. In addition, expression of NLRs was affected by the presence or absence of bacteria, fluid characteristics, disease recurrence, tissue type, and repeated surgery. Various factors of the innate immune system are involved in the pathogenesis of OM in the middle ear. NLRs are expressed in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. Impaired NLR expression induced the development, chronicity and recurrence of OM and exacerbated associated complications, indicating that NLRs have important roles in the pathogenesis of OM.

Innate Immunity in the Middle Ear Mucosa

Otitis media (OM) encompasses a spectrum of clinical presentations ranging from the readily identifiable Acute OM (AOM), which is characterised by otalgia and fever, to chronic otitis media with effusion (COME) where impaired hearing due to middle ear effusion may be the only clinical symptom. Chronic suppurative OM (CSOM) presents as a more severe form of OM, involving perforation of the tympanic membrane. The pathogenesis of OM in these varied clinical presentations is unclear but activation of the innate inflammatory responses to viral and/or bacterial infection of the upper respiratory tract performs an integral role. This localised inflammatory response can persist even after pathogens are cleared from the middle ear, eustachian tubes and, in the case of respiratory viruses, even the nasal compartment. Children prone to OM may experience an over exuberant inflammatory response that underlies the development of chronic forms of OM and their sequelae, including hearing impairment. Treatments for chronic effusive forms of OM are limited, with current therapeutic guidelines recommending a "watch and wait" strategy rather than active treatment with antibiotics, corticosteroids or other anti-inflammatory drugs. Overall, there is a clear need for more targeted and effective treatments that either prevent or reduce the hyper-inflammatory response associated with chronic forms of OM. Improved treatment options rely upon an in-depth understanding of OM pathogenesis, particularly the role of the host innate immune response during acute OM. In this paper, we review the current literature regarding the innate immune response within the middle ear to bacterial and viral otopathogens alone, and as co-infections. This is an important consideration, as the role of respiratory viruses as primary pathogens in OM is not yet fully understood. Furthermore, increased reporting from PCR-based diagnostics, indicates that viral/bacterial co-infections in the middle ear are more common than bacterial infections alone. Increasingly, the mechanisms by which viral/bacterial co-infections may drive or maintain complex innate immune responses and inflammation during OM as a chronic response require investigation. Improved understanding of the pathogenesis of chronic OM, including host innate immune response within the middle ear is vital for development of improved diagnostic and treatment options for our children.

Evaluation of Caspase-1, Interleukin-1β, and Interleukin-18, in the Middle Ear Effusion in Children With Otitis Media With Effusion

Objectives: The present study aimed to assess the expression of caspase-1 and caspase-1-dependent processing of cytokines, such as interleukin (IL)-1β and IL-18, in the middle ear effusion of children with otitis media with effusion (OME) in order to identify the potential role of inflammasomes in OME. Methods: This study included 29 children scheduled for myringotomy with the insertion of tympanostomy tubes due to OME. Middle ear effusion (MEE) was collected during the surgery. Caspase-1, IL-1β, and IL-18 were assayed using enzyme-linked immunosorbent assay kits. The levels were compared between those with mucoid and serous MEE and those with and without a history of ventilation tube insertion. Results: Caspase-1, IL-1β, and IL-18 were detected in all samples. The caspase-1, IL-1β, and IL-18 levels did not significantly differ between mucoid samples and serous samples. No statistical significances were discovered in caspase-1, IL-1β, and IL-18 levels between with and without a history of ventilation tube groups. There was a significant negative correlation between IL-1β and IL-18 and the duration of OME (p < 0.05). However, no significant correlation was found between caspase-1 and disease duration. Conclusions: Inflammasomes may participate in the inflammatory process of OME. IL-1β and IL-18 levels in the MEE decreased over time.

Lower Beclin-1 mRNA Levels in Pediatric Compared With Adult Patients With Otitis Media With Effusion

OBJECTIVES

The role of autophagy in the pathophysiology of otitis media with effusion (OME) remains unclear, particularly regarding the difference between pediatric and adult patients. The present study analyzed the expression levels of autophagy-associated mRNAs in effusion fluids obtained from pediatric and adult patients with OME.

MATERIALS AND METHODS

Middle ear fluid samples were collected from 76 pediatric patients and 41 adult patients with OME, and the levels of mRNAs encoding autophagy-related genes were measured using real-time reverse transcription-polymerase chain reaction. The relationships between the levels of autophagy-associated mRNAs and the frequency of ventilation tube insertion, the characteristics of middle ear fluid, and the results of bacterial culture were analyzed.

RESULTS

Autophagy-associated mRNAs were present in the effusion fluid of all patients. The level of Beclin-1 mRNA was significantly lower in pediatric than in adult patients, regardless of the frequency of surgery or fluid characteristics (p < 0.05).

CONCLUSION

Autophagy-associated mRNAs were expressed in effusion fluids of both pediatric and adult patients with OME. However, the level of Beclin-1 mRNA was significantly lower in the effusion fluid of pediatric than adult patients.

The expression and correlation of Hsp 70 and Hsp 27 in serous middle ear effusion fluids of pediatric patients-a preliminary study

OBJECTIVES

Several cytokines and innate immune-associated molecules are present in middle ear effusions, but damage-associated molecular patterns (DAMPs) in middle ear effusion have not been studied. Therefore, we evaluated the role of heat shock proteins (Hsps) in the development of otitis media with effusion (OME).

METHODS

Serous middle ear effusions from 22 pediatric patients who were diagnosed with OME and underwent ventilation tube insertion from June 2015 to March 2017 were evaluated in our study. The levels of Hsp 90, 70, 27, IL-8, and TNF-α in effusion fluids were evaluated by enzyme-linked immunosorbent assays. The associations between the levels of these molecules and the degree of tympanic membrane inflammation were statistically evaluated. Finally, the relationships among these molecules were also evaluated.

RESULTS

Hsp 70 and Hsp 27 were detected in all middle ear effusions, but Hsp 90 was detected in only five effusion fluid samples. IL-8 was also detected in all middle ear effusions, but TNF-α was detected in only four effusion fluid samples. When we compared the degree of tympanic membrane inflammation with the levels of Hsp 70, Hsp 27, and IL-8, which were detected in all effusion fluids, we could not find statistical significance. However, Hsp 70, Hsp 27, and IL-8 were significantly associated with each other (p < 0.05).

CONCLUSIONS

Hsp 70 and Hsp 27 were expressed in middle ear effusions. Furthermore, the levels of Hsp 70 and Hsp 27 were positively correlated with each other, and were also positively associated with the neutrophil chemoattractant, IL-8. Our findings suggested that Hsp 70 and Hsp 27 might be involved in the pathophysiology of pediatric OME.

Panel 8: Report on Recent Advances in Molecular and Cellular Biochemistry

Objectives To update the medical literature on recent cellular and molecular advances in otitis media disease models with a principal focus on developments in the past 5 years. We also aim to explain recent translational advances in cellular and molecular biology that have influenced our understanding and management of otitis media. Data Sources PubMed-indexed peer-reviewed articles. Review Methods A comprehensive review of the literature was conducted with the term otitis media and the following search terms: molecular biology, cell biology, innate immunity, oxidative stress, mucins, molecular diagnostics. Included articles were published in the English language from January 1, 2010, to July 31, 2015. Implications for Practice The molecular understanding of otitis media disease progression has rapidly advanced over the last 5 years. The roles of inflammation, mucins, and cell signaling mechanisms have been elucidated and defined. Advances in the field provide a plethora of opportunities for innovative molecular targeting in the development of novel therapeutic strategies for otitis media.

Panel 5: Immunology

Objective

To perform a state-of-the-art review of the literature from January 2012 through May 2015 on studies that advanced our knowledge of the innate and adaptive immunology related to otitis media. This review also proposes future directions for research in this area.

Data Sources

PubMed database of the National Library of Medicine.

Review Methods

Three subpanels comprising experts in the field focused on sections relevant to cytokines, innate immunity, and adaptive immunity. The review focused on animal, cell line, and human studies and was critical in relation to the recommendations from the previous publication and for determination of the proposed goals and priorities. The panel met at the 18th International Symposium on Recent Advances in Otitis Media in June 2015 to consolidate its prior search results and discuss, plan, and refine the review. The panel approved the final draft.

Conclusion

From 2012 to 2014, tremendous progresses in immunology of otitis media were established—especially in the areas of innate immunity associated with the pathogenesis of otitis media.

Implications for Practice

The advances of the past 4 years formed the basis for a series of short- and long-term research goals in an effort to guide the field. Accomplishing these goals will provide opportunities for the development of novel interventions, including new ways to better treat and prevent otitis media, especially for recurrent otitis media.

Increased IL-17 and 22 mRNA expression in pediatric patients with otitis media with effusion

OBJECTIVES

Middle ear effusion has been reported to be associated with immune responses in patients with otitis media with effusion (OME). Although various cytokines are involved in immunologic responses in patients with OME, no study to date has assessed the involvement of the pro-inflammatory cytokines interleukin (IL)-17 and IL-22. This study analyzed the levels of expression of IL-17 and IL-22 in the middle ear effusion of patients with OME.

METHODS

Patients aged <11 years who were diagnosed with chronic OME and underwent ventilation tube insertion from May 2013 to August 2015 were enrolled. Effusion fluid samples were obtained during surgery and levels of IL-17 and IL-22 mRNAs assessed by real-time PCR. IL-17 and IL-22 mRNA levels were compared in patients with effusion fluid positive and negative for bacteria; in patients with and without accompanying diseases, recurrent disease, and re-operation; and relative to fluid characteristics.

RESULTS

The study cohort included 70 pediatric patients, 46 boys and 24 girls, of mean age 4.31 ± 2.11 years. The levels of IL-17 and IL-22 mRNA were higher in patients with than without sinusitis, but only IL-22 mRNA levels differed significantly (p < 0.05). The level of IL-17 mRNA was significantly higher in patients who did than did not undergo T&A (p < 0.05). The level of IL-22 expression was significantly higher in mucoid and purulent middle ear fluid samples than in serous fluid samples (p < 0.05).

CONCLUSION

IL-17 and IL-22 mRNAs are involved in the pathophysiology of OME and are significantly higher in subjects with than without accompanying diseases.

Clinical Practice Guideline: Otitis Media with Effusion (Update)

OBJECTIVE

This update of a 2004 guideline codeveloped by the American Academy of Otolaryngology-Head and Neck Surgery Foundation, the American Academy of Pediatrics, and the American Academy of Family Physicians, provides evidence-based recommendations to manage otitis media with effusion (OME), defined as the presence of fluid in the middle ear without signs or symptoms of acute ear infection. Changes from the prior guideline include consumer advocates added to the update group, evidence from 4 new clinical practice guidelines, 20 new systematic reviews, and 49 randomized control trials, enhanced emphasis on patient education and shared decision making, a new algorithm to clarify action statement relationships, and new and expanded recommendations for the diagnosis and management of OME.

PURPOSE

The purpose of this multidisciplinary guideline is to identify quality improvement opportunities in managing OME and to create explicit and actionable recommendations to implement these opportunities in clinical practice. Specifically, the goals are to improve diagnostic accuracy, identify children who are most susceptible to developmental sequelae from OME, and educate clinicians and patients regarding the favorable natural history of most OME and the clinical benefits for medical therapy (eg, steroids, antihistamines, decongestants). Additional goals relate to OME surveillance, hearing and language evaluation, and management of OME detected by newborn screening. The target patient for the guideline is a child aged 2 months through 12 years with OME, with or without developmental disabilities or underlying conditions that predispose to OME and its sequelae. The guideline is intended for all clinicians who are likely to diagnose and manage children with OME, and it applies to any setting in which OME would be identified, monitored, or managed. This guideline, however, does not apply to patients <2 months or >12 years old.

ACTION STATEMENTS

The update group made strong recommendations that clinicians (1) should document the presence of middle ear effusion with pneumatic otoscopy when diagnosing OME in a child; (2) should perform pneumatic otoscopy to assess for OME in a child with otalgia, hearing loss, or both; (3) should obtain tympanometry in children with suspected OME for whom the diagnosis is uncertain after performing (or attempting) pneumatic otoscopy; (4) should manage the child with OME who is not at risk with watchful waiting for 3 months from the date of effusion onset (if known) or 3 months from the date of diagnosis (if onset is unknown); (5) should recommend against using intranasal or systemic steroids for treating OME; (6) should recommend against using systemic antibiotics for treating OME; and (7) should recommend against using antihistamines, decongestants, or both for treating OME.The update group made recommendations that clinicians (1) should document in the medical record counseling of parents of infants with OME who fail a newborn screening regarding the importance of follow-up to ensure that hearing is normal when OME resolves and to exclude an underlying sensorineural hearing loss; (2) should determine if a child with OME is at increased risk for speech, language, or learning problems from middle ear effusion because of baseline sensory, physical, cognitive, or behavioral factors; (3) should evaluate at-risk children for OME at the time of diagnosis of an at-risk condition and at 12 to 18 months of age (if diagnosed as being at risk prior to this time); (4) should not routinely screen children for OME who are not at risk and do not have symptoms that may be attributable to OME, such as hearing difficulties, balance (vestibular) problems, poor school performance, behavioral problems, or ear discomfort; (5) should educate children with OME and their families regarding the natural history of OME, need for follow-up, and the possible sequelae; (6) should obtain an age-appropriate hearing test if OME persists for 3 months or longer OR for OME of any duration in an at-risk child; (7) should counsel families of children with bilateral OME and documented hearing loss about the potential impact on speech and language development; (8) should reevaluate, at 3- to 6-month intervals, children with chronic OME until the effusion is no longer present, significant hearing loss is identified, or structural abnormalities of the eardrum or middle ear are suspected; (9) should recommend tympanostomy tubes when surgery is performed for OME in a child <4 years old; adenoidectomy should not be performed unless a distinct indication exists (nasal obstruction, chronic adenoiditis); (10) should recommend tympanostomy tubes, adenoidectomy, or both when surgery is performed for OME in a child ≥4 years old; and (11) should document resolution of OME, improved hearing, or improved quality of life when managing a child with OME.

Innate Immunity: Orchestrating Inflammation and Resolution of Otitis Media

Otitis media (OM) is a common disease in young children, accounting for more office visits and surgeries than any other pediatric condition. It is associated with an estimated cost of five billion dollars annually in the USA. Moreover, chronic and recurrent middle ear (ME) disease leads to hearing loss during critical periods of language acquisition and learning leading to delays in reaching developmental milestones and risking permanent damage to the ME and inner ear in severe cases. Therefore, research to understand the disease pathogenesis and identify new therapeutics is important. Although OM is a multifactorial disease, targeting the molecular mechanisms that drive inflammation and OM resolution is critical. In this review, we discuss the current evidence suggesting that innate immune receptors and effectors play key roles in OM by mediating both the ME inflammatory responses and recovery.

Expression of CXCL4 and aquaporin 3 and 10 mRNAs in patients with otitis media with effusion

PURPOSE

Bacterial infections in children with underdeveloped Eustachian tubes are a major cause of otitis media with effusion (OEM), and persistent effusion in the middle ear in these patients is a major cause of surgical intervention. CXCL4 is associated with bacterial infection, and aquaporins 3 and 10 are associated with water metabolism. This study assessed the expression of mRNAs encoding CXCL-4 and aquaporins 3 and 10 in the effusion of pediatric OME patients, and the association of this expression with clinical manifestations.

METHODS

Levels of CXCL4 and aquaporin 3 and 10 mRNA were assayed by real-time RT-PCR in the middle ear effusion of 38 pediatric patients with OME requiring ventilation tube insertion. The relationships of these mRNA levels with the presence of bacteria; concomitant diseases such as allergic rhinitis, sinusitis, and adenoid disease; recurrence of OME; and number of ventilation tube insertions were evaluated.

RESULTS

CXCL4 and aquaporin 3 and 10 mRNAs were expressed in middle ear effusion of all OME patients. CXCL-4 mRNA levels were significantly lower when bacteria were present and in patients with concomitant diseases (p<0.05 each). Levels of all three mRNAs were unrelated to OME recurrence or number of ventilation tube insertions (p>0.05 each). The levels of CXCL4 and aquaporin 10 mRNAs were significantly correlated (p<0.05).

CONCLUSION

Expression of CXCL4 and aquaporin 3 and 10 mRNAs in middle ear effusion is associated with the pathophysiology of OME. CXCL4 mRNA levels are significantly lower in patients with than without concomitant diseases or bacterial infections.