HEARING LOSS & CYTOKINES
Laryngoscope Investig Otolaryngol. 2016 Oct;1(5):110-115. Epub 2016 Sep 21.
AAO: Autoimmune and Autoinflammatory (Disease) in Otology: What is New in Immune-Mediated Hearing Loss.
Autoinflammatory diseases are a family of immune-mediated, rare diseases, some of which, exhibit sensorineural hearing loss (SNHL), suggesting potentially similar mechanisms of molecular pathogenesis between autoinflammatory-mediated hearing loss and autoimmune inner ear disease (AIED) may exist. The purpose of this review is to compare the clinical features of autoimmune and autoinflammatory diseases that affect hearing, discuss the limitations of our knowledge, and highlight potential new disease mechanisms and therapeutics.
Pubmed Literature Review; Google Scholar Literature review.
A focused comparison of AIED with a number of autoinflammatory diseases that manifest with sensorineural hearing loss was performed. The pathogenesis of these diseases is reviewed in the context of the innate and adaptive immune system, cytokine expression and genetic polymorphisms.
AIED, since first described by Cogan and Lehnhardt and first clinically characterized by McCabe, has remained an enigmatic disease, with limited advances in both new diagnostics and new therapeutics. Since the discovery of autoinflammatory diseases, a number of systemic autoimmune diseases have either been re-classed as autoinflammatory diseases or identified to have features of autoinflammatory disease.
AIED has clinical features of both autoimmune and autoinflammatory disease. It is critical that autoinflammatory diseases be correctly identified, as failure to do so may result in systemic amyloidosis and kidney damage.
Otol Neurotol. 2016 Aug;37(7):e203-8. doi: 10.1097/MAO.0000000000001095.
Tumor Necrosis Factor-induced Decrease of Cochlear Blood Flow Can Be Reversed by Etanercept or JTE-013.
This study aimed to quantify the effects of tumor necrosis factor (TNF) inhibitor Etanercept and sphingosine-1-phosphate receptor 2 antagonist JTE-013 on cochlear blood flow in guinea pigs after TNF-induced decrease.
Sudden sensorineural hearing loss is a common cause for disability and reduced quality of life. Good understanding of the pathophysiology and strong evidence-based therapy concepts are still missing. In various inner ear disorders, inflammation and impairment of cochlear blood flow (CBF) have been considered factors in the pathophysiology. A central mediator of inflammation and microcirculation in the cochlea is TNF. S1P acts downstream in one TNF pathway.
Cochlea lateral wall vessels were exposed surgically and assessed by intravital microscopy in guinea pigs in vivo. Twenty-eight animals were randomly distributed into four groups of seven each. Exposed vessels were superfused by TNF (5.0 ng/ml) and afterward repeatedly either by Etanercept (1.0 μg/ml), JTE-013 (10 μmol/L), or vehicle (0.9 % NaCl solution or ethanol: phosphate-buffered saline buffer, respectively).
After decreasing CBF with TNF (p <0.001, two-way RM ANOVA), both treatments reversed CBF, compared with vehicle (p <0.001, two-way RM ANOVA). The comparison of the vehicle groups showed no difference (p = 0.969, two-way RM ANOVA), while there was also no difference between the treatment groups (p = 0.850, two-way RM ANOVA).
Both Etanercept and JTE-013 reverse the decreasing effect of TNF on cochlear blood flow and, therefore, TNF and the S1P-signalling pathway might be targets for treatment of microcirculation-related hearing loss.
Aging Cell. 2016 Apr;15(2):301-8. doi: 10.1111/acel.12437. Epub 2016 Jan 21.
Activation of TRAIL-DR5 pathway promotes sensorineural degeneration in the inner ear.
Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated levels of serum TNF-α are associated with human sensorineural hearing loss via poorly understood mechanisms. We demonstrate, for the first time, expression of TNF-related apoptosis-inducing ligand (TRAIL) and its signaling death receptor 5 (DR5) in the murine inner ear and show that exogenous TRAIL can trigger hair cell and neuronal degeneration, which can be partly prevented with DR5-blocking antibodies.
Sci Rep. 2015 Dec 22;5:18599. doi: 10.1038/srep18599.
Secreted Factors from Human Vestibular Schwannomas Can Cause Cochlear Damage.
Vestibular schwannomas (VSs) are the most common tumours of the cerebellopontine angle. Ninety-five percent of people with VS present with sensorineural hearing loss (SNHL); the mechanism of this SNHL is currently unknown. To establish the first model to study the role of VS-secreted factors in causing SNHL, murine cochlear explant cultures were treated with human tumour secretions from thirteen different unilateral, sporadic VSs of subjects demonstrating varied degrees of ipsilateral SNHL. The extent of cochlear explant damage due to secretion application roughly correlated with the subjects' degree of SNHL. Secretions from tumours associated with most substantial SNHL resulted in most significant hair cell loss and neuronal fibre disorganization. Secretions from VSs associated with good hearing or from healthy human nerves led to either no effect or solely fibre disorganization. Our results are the first to demonstrate that secreted factors from VSs can lead to cochlear damage. Further, we identified tumour necrosis factor alpha (TNFα) as an ototoxic molecule and fibroblast growth factor 2 (FGF2) as an otoprotective molecule in VS secretions. Antibody-mediated TNFα neutralization in VS secretions partially prevented hair cell loss due to the secretions. Taken together, we have identified a new mechanism responsible for SNHL due to VSs.
Laryngoscope. 2015 Jan;125(1):E28-32. doi: 10.1002/lary.24743. Epub 2014 Oct 27.
A case-control study on proinflammatory genetic polymorphisms on sudden sensorineural hearing loss.
Sudden sensorineural hearing loss (SSNHL) is strictly related to inner ear vascular injuries and recently to some atherosclerotic risk factors. The pathogenic role of inflammatory molecules in atherosclerosis is well established. However, there is little knowledge about the potential role of inflammatory cytokines and adhesion molecules on SSNHL etiology.
The aim of this study was to evaluate the role of proinflammatory genetic polymorphisms of the MCP-1 (CCL2), E-selectin, and interleukin (IL)-6 gene in SSNHL patients.
We evaluated the frequency and distribution of selected single nucleotide polymorphisms of the MCP-1 (CCL2), E-selectin, and IL-6 gene in 87 SSNHL patients and 107 healthy controls.
Our results did not show significant difference between the compared groups for MCP-1 and E-selectin genes, whereas a significant difference was reported for the IL-6 gene (P < .0001).
The main finding of our study is that the 174G/G polymorphism (with a wider distribution of wt/wt genotype in SSNHL patients than in the healthy controls) of the IL-6 gene is significantly associated with the risk of SSNHL, which is consistent with a previous finding on serum levels of IL-6 in SSNHL. It is possible that the variant acts as a triggering agent of different lipidemia-related phenotypes. Both the -174G/G polymorphism and elevated IL-6 levels in SSNHL patients could suggest that IL-6 plays a role in the inner ear involvement by atherosclerotic inflammatory events.
Pediatr Rheumatol Online J. 2015 Nov 4;13(1):43. doi: 10.1186/s12969-015-0041-9.
Early detection of sensorineural hearing loss in Muckle-Wells-syndrome.
Muckle-Wells-syndrome (MWS) is an autoinflammatory disease characterized by systemic and organ-specific inflammation due to excessive interleukin (IL)-1 release. Inner ear inflammation results in irreversible sensorineural hearing loss, if untreated. Early recognition and therapy may prevent deafness. The aims of the study were to characterize the spectrum of hearing loss, optimize the otologic assessment for early disease and determine responsiveness to anti-IL-1-therapy regarding hearing.
A single center prospective cohort study of children and adults with MWS was performed. Standardized clinical, laboratory and otologic assessments including standard pure tone audiometry, additional high tone thresholds, vestibular organ testing, tinnitus evaluation and functional disability classes were determined serially. Pure-tone-average models were developed and evaluated. Risk factors for hearingloss and the impact of anti-IL-1 treatment were determined.
A total of 23 patients with genetically confirmed MWS were included, of whom 63 % were females; 52 % were children. At baseline all patients had active MWS; 91 % reported clinically impaired hearing with 74 % having an abnormal standard assessment (0.5-4 kHz). In contrast, high frequency pure tone averages (HF-PTA) were abnormal in all symptomatic patients including those with early hearingloss (sensitivity 100 %). Females were at highest risk for hearing loss even after adjustment for age (p = 0.008). Treatment with IL-1 blockade resulted in improved or stable hearing in 91 % of patients.
Early inner ear inflammation in MWS primarily affects the high frequencies, beyond the range of standard otologic assessment tools. The HF-PTA is a sensitive tool to detect imminent hearing loss and monitor treatment response.
Biomed Res Int. 2014;2014:856019. doi: 10.1155/2014/856019. Epub 2014 Apr 22.
Exogenous IL-4-expressing bone marrow mesenchymal stem cells for the treatment of autoimmune sensorineural hearing loss in a guinea pig model.
Bone marrow mesenchymal stem cells (BMSCs) expressing recombinant IL-4 have the potential to remediate inflammatory diseases. We thus investigated whether BMSCs expressing exogenous IL-4 could alleviate autoimmune sensorineural hearing loss. BMSCs isolated from guinea pigs were transfected with recombinant lentivirus expressing IL-4. A total of 33 animals were divided into three groups. Group A received scala tympani injection of IL-4-expressing BMSCs, and Group B received control vector-expressing BMSCs, and Group C received phosphate-buffered saline. The distribution of implanted BMSCs in the inner ears was assessed by immunohistochemistry and fluorescence microscopy. Auditory brain-stem response (ABR) was monitored to evaluate the auditory changes. Following BMSCs transplantation, the threshold levels of ABR wave III decreased in Groups A and B and significant differences were observed between these two groups (P < 0.05). Transplanted BMSCs distributed in the scala tympani and scala vestibuli. In some ears with hearing loss, there was a decrease in the number of spiral ganglion cells and varying degrees of endolymphatic hydrops or floccule. Following transplantation, the lentivirus-infected BMSCs migrated to the inner ear and produced IL-4. Our results demonstrate that, upon transplantation, BMSCs and BMSCs expressing recombinant IL-4 have the ability to remediate the inflammatory injury in autoimmune inner ear diseases.