The role of immunomodulatory oligonucleotides in prevention of OVA-induced Eustachian tube dysfunction

Allergy in pathogenesis of Eustachian Tube Dysfunction

Eustachian tube dysfunction (ETD) is a condition where the Eustachian tube (ET) fails to function normally, resulting in symptoms such as aural fullness, tinnitus, autophony, and hearing loss. ETD can further lead to middle ear diseases such as otitis media effusion and adhesive otitis media, which is becoming more common in the field of otology. Although the pathogenesis of ETD remains unclear, recent animal studies and clinical experiments have found allergic reactions and allergic diseases are closely related to the occurrence of ETD. As the mucosa of the ET is continuous with that of the nasopharynx and tympanic cavity, it is reasonable to assume that the immunological basis of the ET itself is similar to that of respiratory allergic diseases. However, due to the special anatomical location and complex pathogenesis of the ET, there is still no unified diagnostic gold standard. Additionally, there is an ongoing debate regarding whether ETD can be classified as a distinct disease or even an allergic disease. Furthermore, the effectiveness of anti-allergic therapy in patients with ETD is yet to be fully understood. Therefore, this review elaborates on the possible mechanisms of allergic reactions in the occurrence and development of ETD, and explores the potential role of anti-allergic therapy in managing this condition, in order to provide new insights into the pathogenesis and prevention of ETD.

Medical Management for Eustachian Tube Dysfunction in Adults: A Systematic Review and Meta-Analysis

OBJECTIVE

Medical treatment for eustachian tube dysfunction (ETD) is varied, with physician preference driving treatment choice and limited guidance for these options. An evaluation of the efficacy of medical management (MM) for ETD is warranted.

METHODS

A systematic review of three databases (PubMed, Scopus, and Embase) was performed through December 2020. Adults treated nonsurgically for ETD were included. Exclusion criteria were as follows: patulous ETD, ETD deriving from craniofacial anomalies, or surgical treatment. Data were extracted independently by two reviewers according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A meta-analysis of continuous measures, proportions, and risk ratio was conducted.

RESULTS

Twelve articles were identified by systematic review, with either level 2 or 3 evidence. A meta-analysis of available data was performed on nine studies. A pooled cohort found 50.3% (95% confidence interval [CI], 41.7-59.0) of patients experienced symptomatic improvement with MM. ETDQ-7 scores improved in a clinically nonsignificant manner by -0.88 (95% CI, -1.12 to -0.64) following medical treatment. Further, MM benefited from subacute and chronic symptoms in 30% to 64% and 11% to 50% of cases, respectively. Intranasal corticosteroids (INCS) were not efficacious, improving only 11% to 18% of chronic cases. Therapies such as Politzer devices and Valsalva therapy had minimally beneficial results.

CONCLUSION

Our review did not find any level 1 evidence for MM of ETD in adults. Available evidence indicates INCS are ineffective for chronic symptoms and the efficacy of nonsurgical options for subacute ETD has yet to be determined. Further randomized controlled trials are needed to discern efficacy of single-agent medical therapies. Laryngoscope, 2021.

Synthetic agonists of Toll-like receptors 7, 8 and 9

TLRs (Toll-like receptors) are a family of innate immune receptors that induce protective immune responses against infections. Single-stranded viral RNA and bacterial DNA containing unmethylated CpG motifs are the ligands for TLR7 and TLR8 and 9 respectively. We have carried out extensive structure–activity relationship studies of DNA- and RNA-based compounds to elucidate the impact of nucleotide motifs and structures on these TLR-mediated immune responses. These studies have led us to design novel DNA- and RNA-based compounds, which act as potent agonists of TLR9 and TLR7 and 8 respectively. These novel synthetic agonists produce different immune response profiles depending on the structures and nucleotide motifs present in them. The ability to modulate TLR-mediated immune responses with these novel DNA- and RNA-based agonists in a desired fashion may allow targeting a broad range of diseases, including cancers, asthma, allergies and infections, alone or in combination with other therapeutic agents, and their use as adjuvants with vaccines. IMO-2055, our first lead candidate, is a TLR9 agonist that is currently in clinical evaluation in oncology patients. A second candidate, IMO-2125, is also a TLR9 agonist that has been shown to induce high and sustained levels of IFN (interferon) in non-human primates and is being evaluated in HepC-infected human subjects.

Immune modulatory oligonucleotides in prevention of nasal allergen-induced Eustachian tube dysfunction in rats

OBJECTIVES

Develop a model of nasal allergen-induced Eustachian tube dysfunction (ETD) in a rat and investigate the role of immune modulatory oligonucleotides (IMOs) in the prevention of nasal allergen-induced ETD.

STUDY DESIGN AND SETTING

Prospective, randomized study. Brown Norway rats were sensitized to ova albumin (OVA) and randomized to receive pretreatment with IMOs or phosphate-buffered saline. All animals were challenged intranasally with aerosolized OVA. Dynamic measures of Eustachian tube (ET) function were analyzed.

RESULTS

Animals that were OVA-sensitized and IMO-pretreated had significantly lower mean passive opening (95% confidence interval [95% CI] 15.0,19.4) and closing (95% CI 4.8,7.8) ET pressures compared with those of (95% CI 24.1,32.7) and (95% CI 12.1,18.8) OVA-sensitized untreated rats, respectively. In addition, the IMO-pretreated animals demonstrated the ability to actively clear a significantly higher proportion of negative pressure (95% CI 0.64,0.96) compared with the untreated animals (95% CI 0.09,0.39). IMO-pretreated animals also demonstrated significantly improved mean mucociliary clearance times in seconds (95% CI 115,195) than those in untreated animals (95% CI 308,668).

CONCLUSIONS

Pretreatment with IMOs prevented allergen-induced allergic inflammation around the Eustachian tube (ET) and resulted in improved ventilatory function of the ET compared with sensitized untreated animals. IMOs offer considerable promise in the management of nasal allergic disease as well as otitis media with effusion.

Immunostimulatory sequences in immunotherapy

PURPOSE OF REVIEW

To review the current literature regarding immunostimulatory sequences of DNA for immunotherapy with respect to signaling mechanisms, cytokine profiles, structural characteristics and the applicability and success of this strategy to treat allergic disease.

RECENT FINDINGS

The binding of synthetic DNA-based immunotherapy agents composed of unmethylated cytosine-guanine dinucleotides (CpG ODN) to toll-like receptors have been found to be species-specific. CpG ODNs are capable of inducing a shift in the cytokine profile and immune response that favors the Th1 pathway and suppresses the Th2 pathway. This makes using CpG ODNs a promising candidate for the treatment of allergic diseases, which are known to be mediated by Th2-based response. Current CpG ODN studies have demonstrated prevention and reversal of acute allergen inflammation, airway hyper-reactivity and remodeling. Early animal and human trials of CpG ODNs have shown them to be both well tolerated and effective.

SUMMARY

The use of immunostimulatory sequences in immunotherapy, although still in the early stages of development, has thus far been shown to be both well tolerated and effective, and offers the potential for a better tolerated, more rapid, more efficacious and longer-lasting therapy over current immunotherapy protocols.