Systemic cytokine response profiles associated with respiratory virus-induced acute otitis media

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.

Otitis media

Otitis media (OM) or middle ear inflammation is a spectrum of diseases, including acute otitis media (AOM), otitis media with effusion (OME; 'glue ear') and chronic suppurative otitis media (CSOM). OM is among the most common diseases in young children worldwide. Although OM may resolve spontaneously without complications, it can be associated with hearing loss and life-long sequelae. In developing countries, CSOM is a leading cause of hearing loss. OM can be of bacterial or viral origin; during 'colds', viruses can ascend through the Eustachian tube to the middle ear and pave the way for bacterial otopathogens that reside in the nasopharynx. Diagnosis depends on typical signs and symptoms, such as acute ear pain and bulging of the tympanic membrane (eardrum) for AOM and hearing loss for OME; diagnostic modalities include (pneumatic) otoscopy, tympanometry and audiometry. Symptomatic management of ear pain and fever is the mainstay of AOM treatment, reserving antibiotics for children with severe, persistent or recurrent infections. Management of OME largely consists of watchful waiting, with ventilation (tympanostomy) tubes primarily for children with chronic effusions and hearing loss, developmental delays or learning difficulties. The role of hearing aids to alleviate symptoms of hearing loss in the management of OME needs further study. Insertion of ventilation tubes and adenoidectomy are common operations for recurrent AOM to prevent recurrences, but their effectiveness is still debated. Despite reports of a decline in the incidence of OM over the past decade, attributed to the implementation of clinical guidelines that promote accurate diagnosis and judicious use of antibiotics and to pneumococcal conjugate vaccination, OM continues to be a leading cause for medical consultation, antibiotic prescription and surgery in high-income countries.

Effect of systemic clarithromycin and prednisolone on histamine-induced otitis media in guinea pigs

CONCLUSION

The results of the study showed that clarithromycin has anti-inflammatory and antioxidant effects and, when it is combined with prednisolone, those effects gain strength.

OBJECTIVES

The present study aims to investigate the effects that the antioxidant and anti-inflammatory activities of clarithromycin and/or prednisolone have on experimental otitis media in effusion-induced guinea-pigs.

METHOD AND RESULTS

In this study, 35-male guinea pigs were randomly divided into five-groups. For the experimental otitis media, intra-tympanic histamine (0.1 ml) was injected into the guinea pigs in all of the groups except the control group. Then, 24-h after the intra-tympanic injections, clarithromycin (15 mg/kg/day) and/or prednisolone (1 mg/kg/day) were applied intraperitoneally to the guinea-pigs for 7-days. The biochemical analysis showed an increase in antioxidant capacity and a decrease in oxidant status and malondialdehyde (MDA) levels in the clarithromycin group and the prednisolone group and especially in the clarithromycin+prednisolone group, as compared to the experimental group (p < 0.05). In the cytokine analysis, lower levels of interleukin (IL)-6 and IL-17A and higher IL-10 were found in the clarithromycin, prednisolone, and clarithromycin+prednisolone groups than in the experimental group (p < 0.05). Furthermore, the histologic analyses showed histopathologic changes in the middle ear mucosa of the experimental group, but comparatively fewer-histopathologic changes were observed in the clarithromycin, prednisolone, and clarithromycin+prednisolone groups.

Cytokine, chemokine, and Toll-like receptor expression in middle ear fluids of children with acute otitis media

OBJECTIVES/HYPOTHESIS

Acute otitis media (AOM) is a common bacterial infection in childhood that causes an inflammatory response in the middle ear. Leukocytes produce different inflammatory molecules in vitro when stimulated with Gram-positive and Gram-negative bacteria. The major causes of AOM are Streptococcus pneumoniae, nontypeable Haemophilus influenza, and Moraxella catarrhalis. We sought to assess differences in cytokines, chemokines, and expression of Toll-like receptors (TLRs) at onset of AOM based on bacterial culture results.

STUDY DESIGN

Middle ear fluid (MEF) from 66 children with AOM was studied.

METHODS

Innate immune genes, cytokines (interleukin [IL]-6, IL-8, IL-10, IL1-β; tumor necrosis factor-α), chemokines (CCL2, CCL3, CCL4, CCR5, CXCR3), and Toll-like receptors (TLR2, TLR4, TLR9) expression was measured using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) from MEF collected in vivo by tympanocentesis.

RESULTS

Culture-positive MEF had higher levels of all cytokines and chemokines (9-300-fold) as compared to MEF that was culture negative. Polymerase chain reaction (PCR)-positive/culture-negative MEF for otopathogens showed significant differences (P < .01) in TLR2, TLR4, and TLR9 expression (6-31-fold), but cytokine and chemokine levels were similar compared to PCR-negative/culture-negative MEF. No significant differences were found in the cytokine/chemokine/TLR levels among the bacterial otopathogen species. However, higher levels of TLRs, and all the cytokine and chemokines were detected when more than one bacterial species was present compared to single otopathogens.

CONCLUSIONS

Expression levels of proinflammatory cytokines/chemokines and TLRs are elevated in AOM children with a bacterial otopathogen, and are dependent on the number of bacterial species identified.

Polymorphisms in IL-6, IL-10, TNF-α, IFN-γ and TGF-β1 genes and susceptibility to acute otitis media in early infancy

BACKGROUND

Genetic susceptibility has a major role in the pathogenesis of acute otitis media (AOM). In the present study, we investigated the variability of 5 cytokine genotypes as related to susceptibility and outcome of AOM in early infancy.

METHODS

Single nucleotide polymorphisms in IL-6 (-174 G→C), IL-10 (-592 C→A, -819 C→T and -1082 G→A), TNF-α (-308 G→A), IFN-γ (+874 A→T) and TGF-β1 (codon 10 C→T; codon 25 G→C) genes were investigated and related to clinical course and outcome in 96 infants younger than 9 months with AOM.

RESULTS

Compared with wild genotypes, IL-10 (-592, -819 and -1082) and TGF-β1 (codon 10) genotypes carrying the alternative allele were related to more AOM episodes (P < 0.0001, P < 0.0001, P < 0.0001 and P = 0.002, respectively) and the need for tympanostomy tubes. Furthermore, IL-10 (-1082) and TGF-β1 (codon 10) genotypes carrying the alternative allele were related to later onset of first AOM episode than wild-type genotypes (P = 0.007 and P = 0.039, respectively). No relationship was found about AOM complications.

CONCLUSIONS

Our findings suggest that IL-10 and TGF-β1 genotypes are related to the age of AOM onset, multiple AOM episodes and insertion of tympanostomy tubes, pointing to the involvement of anti-inflammatory cytokines in AOM during infancy.

Panel 5: Microbiology and immunology panel

OBJECTIVE

The objective is to perform a comprehensive review of the literature from January 2007 through June 2011 on the virology, bacteriology, and immunology related to otitis media.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

Three subpanels with co-chairs comprising experts in the virology, bacteriology, and immunology of otitis media were formed. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a second draft was created. The entire panel met at the 10th International Symposium on Recent Advances in Otitis Media in June 2011 and discussed the review and refined the content further. A final draft was created, circulated, and approved by the panel.

CONCLUSION

Excellent progress has been made in the past 4 years in advancing an understanding of the microbiology and immunology of otitis media. Advances include laboratory-based basic studies, cell-based assays, work in animal models, and clinical studies.

IMPLICATIONS FOR PRACTICE

The advances of the past 4 years formed the basis of a series of short-term 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.

Inflammation in the middle ear of children with recurrent or chronic otitis media is associated with bacterial load

BACKGROUND

Viral upper respiratory tract infections have been described as an important factor in the development of otitis media (OM), although it is unclear whether they facilitate bacterial OM or can directly cause OM. To clarify the role of viral infections in OM, we compared the relative contribution of viruses and bacteria with the induction of inflammatory cytokine responses in the middle ear of children suffering from OM.

METHODS

Children up to 5 years of age, with recurrent or chronic episodes of OM and scheduled for ventilation tube insertion were enrolled in a prospective study. Middle ear fluids (n = 116) were collected during surgery, and quantitative polymerase chain reaction was performed to detect bacterial and viral otopathogens, that is, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and 15 respiratory viruses. Finally, concentrations of the inflammatory mediators interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17a and tumor necrosis factor-α were determined.

RESULTS

Middle ear fluids were clustered into 4 groups, based on the detection of viruses (28%), bacteria (27%), both bacteria and viruses (27%) or no otopathogens (19%). Bacterial detection was associated with significantly elevated concentrations of cytokines compared with middle ear fluids without bacteria (P < 0.001 for all cytokines tested) in a bacterial load-dependent and species-dependent manner. In contrast, the presence of viruses was not associated with changes in cytokine values, and no synergistic effect between viral-bacterial coinfections was observed.

CONCLUSIONS

The presence of bacteria, but not viruses, is associated with an increased inflammatory response in the middle ear of children with recurrent or chronic OM.

Respiratory syncytial virus infection increases regulated on activation normal T cell expressed and secreted and monocyte chemotactic protein 1 levels in serum of patients with asthma and in human monocyte cultures

BACKGROUND

Respiratory syncytial virus (RSV) infection is associated to episodic exacerbations of asthma involving alveolar macrophages and chemokine production.

OBJECTIVE

The aim of this study was to determine the circulating levels of monocyte chemotactic protein 1 (MCP-1), regulated on activation normal T cell expressed and secreted (RANTES), and substance P (SP) in patients with and without asthma with acute respiratory RSV infection and the chemokine profile in RSV- infected monocyte cultures from normal individuals and individuals with asthma.

METHODS

In this regard, 31 adult patients with acute respiratory infection (15 patients with asthma) were studied. MCP-1, RANTES and SP were measured in serum and in supernatants from monocyte cultures by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Increased levels of MCP-1 and RANTES were observed in serum from patients with asthma related to RSV infection. RSV-infected monocyte cultures from healthy individuals showed increased content of those chemokines, and monocyte cultures from patients with asthma showed increased expression of MCP-1.

CONCLUSION

These data show that RSV infection induces increased circulating level of chemokines in patients with asthma, and this finding could be mediated in part by the interaction virus-monocyte.

Development of a human whole blood assay for prediction of cytokine release similar to anti-CD28 superagonists using multiplex cytokine and hierarchical cluster analysis

Anti-CD28 superagonist (SA) mediated cytokine release syndrome (CRS), an adverse event resulting in systemic release of cytokines, is an emergent issue in drug development. CRS is of potential concern for all monoclonal antibodies (mAbs) particularly those directed against cell surface targets on lymphocytes. Concern regarding patient safety requires development of novel methods to predict these adverse reactions. Due to the inability of animal studies to predict CRS, we have developed a whole blood in vitro screen to support First in Human studies and assess the potential for mAbs to cause anti-CD28 SA-like CRS. For this purpose we have immobilized marketed mAbs, whose potential for causing CRS and milder infusion reactions is known, on Protein A beads and used these beads to stimulate cytokine release. After culture, supernatants are harvested and frozen for later multiplex analysis of cytokines using Searchlight™ technology. We have employed hierarchicalluster analysis (HCA) to allow comparison of 12 different cytokine levels across numerous donors, treatments, and experiments. Results conclusively distinguish test mAb responses from an anti-CD28 superagonist mAb response. As part of a global analysis of preclinical data, the results of this assay can facilitate entry into First in Human clinical trials, help with selection of starting doses and may allow more rapid dose escalation using smaller cohorts.

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.

Otitis media: a genome-wide linkage scan with evidence of susceptibility loci within the 17q12 and 10q22.3 regions

Background

Otitis media (OM) is a common worldwide pediatric health care problem that is known to be influenced by genetics. The objective of our study was to use linkage analysis to map possible OM susceptibility genes.

Methods

Using a stringent diagnostic model in which only those who underwent tympanostomy tube insertion at least once for recurrent/persistent OM are considered affected, we have carried out a genome-wide linkage scan using the 10K Affymetrix SNP panel. We genotyped 403 Caucasian families containing 1,431 genotyped individuals and 377 genotyped affected sib pairs, and 26 African American families containing 75 genotyped individuals and 27 genotyped affected sib pairs. After careful quality control, non-parametric linkage analysis was carried out using 8,802 SNPs.

Results

In the Caucasian-only data set, our most significant linkage peak is on chromosome 17q12 at rs226088 with a p-value of 0.00007. Other peaks of potential interest are on 10q22.3 (0.00181 at rs1878001), 7q33 (0.00105 at rs958408), 6p25.1 (0.00261 at rs554653), and 4p15.2 (0.00301 at rs2133507). In the combined Caucasian and African American dataset, the 10q22.3 peak becomes more significant, with a minimal p-value of 0.00026 at rs719871. Family-based association testing reveals signals near previously implicated genes: 513 kb from SFTPA2 (10q22.3), 48 kb from IFNG (12q14), and 870 kb from TNF (6p21.3).

Conclusion

Our scan does not provide evidence for linkage in the previously reported regions of 10q26.3 and 19q13.43. Our best-supported linkage regions may contain susceptibility genes that influence the risk for recurrent/persistent OM. Plausible candidates in 17q12 include AP2B1, CCL5, and a cluster of other CCL genes, and in 10q22.3, SFTPA2.