Genome-wide association meta-analysis identifies 48 risk variants and highlights the role of the stria vascularis in hearing loss.

Hearing loss is one of the top contributors to years lived with disability and is a risk factor for dementia. Molecular evidence on the cellular origins of hearing loss in humans is growing. Here, we performed a genome-wide association meta-analysis of clinically diagnosed and self-reported hearing impairment on 723,266 individuals and identified 48 significant loci, 10 of which are novel. A large proportion of associations comprised missense variants, half of which lie within known familial hearing loss loci. We used single-cell RNA-sequencing data from mouse cochlea and brain and mapped common-variant genomic results to spindle, root, and basal cells from the stria vascularis, a structure in the cochlea necessary for normal hearing. Our findings indicate the importance of the stria vascularis in the mechanism of hearing impairment, providing future paths for developing targets for therapeutic intervention in hearing loss.

Variability in Cochlear Implantation Outcomes in a Large German Cohort With a Genetic Etiology of Hearing Loss.

OBJECTIVES: The variability in outcomes of cochlear implantation is largely unexplained, and clinical factors are not sufficient for predicting performance. Genetic factors have been suggested to impact outcomes, but the clinical and genetic heterogeneity of hereditary hearing loss makes it difficult to determine and interpret postoperative performance. It is hypothesized that genetic mutations that affect the neuronal components of the cochlea and auditory pathway, targeted by the cochlear implant (CI), may lead to poor performance. A large cohort of CI recipients was studied to verify this hypothesis. DESIGN: This study included a large German cohort of CI recipients (n = 123 implanted ears; n = 76 probands) with a definitive genetic etiology of hearing loss according to the American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP) guidelines and documented postoperative audiological outcomes. All patients underwent preoperative clinical and audiological examinations. Postoperative CI outcome measures were based on at least 1 year of postoperative audiological follow-up for patients with postlingual hearing loss onset (>6 years) and 5 years for children with congenital or pre/perilingual hearing loss onset (≤6 years). Genetic analysis was performed based on three different methods that included single-gene screening, custom-designed hearing loss gene panel sequencing, targeting known syndromic and nonsyndromic hearing loss genes, and whole-genome sequencing. RESULTS: The genetic diagnosis of the 76 probands in the genetic cohort involved 35 genes and 61 different clinically relevant (pathogenic, likely pathogenic) variants. With regard to implanted ears (n = 123), the six most frequently affected genes affecting nearly one-half of implanted ears were GJB2 (21%; n = 26), TMPRSS3 (7%; n = 9), MYO15A (7%; n = 8), SLC26A4 (5%; n = 6), and LOXHD1 and USH2A (each 4%; n = 5). CI recipients with pathogenic variants that influence the sensory nonneural structures performed at or above the median level of speech performance of all ears at 70% [monosyllable word recognition score in quiet at 65 decibels sound pressure level (SPL)]. When gene expression categories were compared to demographic and clinical categories (total number of compared categories: n = 30), mutations in genes expressed in the spiral ganglion emerged as a significant factor more negatively affecting cochlear implantation outcomes than all clinical parameters. An ANOVA of a reduced set of genetic and clinical categories (n = 10) identified five detrimental factors leading to poorer performance with highly significant effects ( p < 0.001), accounting for a total of 11.8% of the observed variance. The single strongest category was neural gene expression accounting for 3.1% of the variance. CONCLUSIONS: The analysis of the relationship between the molecular genetic diagnoses of a hereditary etiology of hearing loss and cochlear implantation outcomes in a large German cohort of CI recipients revealed significant variabilities. Poor performance was observed with genetic mutations that affected the neural components of the cochlea, supporting the "spiral ganglion hypothesis."

Closing the Gap between the Auditory Nerve and Cochlear Implant Electrodes: Which Neurotrophin Cocktail Performs Best for Axonal Outgrowth and Is Electrical Stimulation Beneficial?

Neurotrophins promote neurite outgrowth of auditory neurons and may help closing the gap to cochlear implant (CI) electrodes to enhance electrical hearing. The best concentrations and mix of neurotrophins for this nerve regrowth are unknown. Whether electrical stimulation (ES) during outgrowth is beneficial or may direct axons is another open question. Auditory neuron explant cultures of distinct cochlear turns of 6-7 days old mice were cultured for four days. We tested different concentrations and combinations of BDNF and NT-3 and quantified the numbers and lengths of neurites with an advanced automated analysis. A custom-made 24-well electrical stimulator based on two bulk CIs served to test different ES strategies. Quantification of receptors trkB, trkC, p75NTR, and histological analysis helped to analyze effects. We found 25 ng/mL BDNF to perform best, especially in basal neurons, a negative influence of NT-3 in combined BDNF/NT-3 scenarios, and tonotopic changes in trk and p75NTR receptor stainings. ES largely impeded neurite outgrowth and glia ensheathment in an amplitude-dependent way. Apical neurons showed slight benefits in neurite numbers and length with ES at 10 and 500 µA. We recommend BDNF as a potent drug to enhance the man-machine interface, but CIs should be better activated after nerve regrowth.

Diagnostic Yield of Targeted Hearing Loss Gene Panel Sequencing in a Large German Cohort With a Balanced Age Distribution from a Single Diagnostic Center: An Eight-year Study.

OBJECTIVES: Hereditary hearing loss exhibits high degrees of genetic and clinical heterogeneity. To elucidate the population-specific and age-related genetic and clinical spectra of hereditary hearing loss, we investigated the sequencing data of causally associated hearing loss genes in a large cohort of hearing-impaired probands with a balanced age distribution from a single center in Southwest Germany. DESIGN: Genetic testing was applied to 305 hearing-impaired probands/families with a suspected genetic hearing loss etiology and a balanced age distribution over a period of 8 years (2011-2018). These individuals were representative of the regional population according to age and sex distributions. The genetic testing workflow consisted of single-gene screening (n = 21) and custom-designed hearing loss gene panel sequencing (n = 284) targeting known nonsyndromic and syndromic hearing loss genes in a diagnostic setup. Retrospective reanalysis of sequencing data was conducted by applying the current American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines. RESULTS: A genetic diagnosis was established for 75 (25%) of the probands that involved 75 causal variants in 35 genes, including 16 novel causal variants and 9 medically significant variant reclassifications. Nearly half of the solved cases (47%; n = 35) were related to variants in the five most frequently affected genes: GJB2 (25%), MYO15A, WFS1, SLC26A4, and COL11A1 (all 5%). Nearly one-quarter of the cases (23%; n = 17) were associated with variants in seven additional genes (TMPRSS3, COL4A3, LOXHD1, EDNRB, MYO6, TECTA, and USH2A). The remaining one-third of single cases (33%; n = 25) were linked to variants in 25 distinct genes. Diagnostic rates and gene distribution were highly dependent on phenotypic characteristics. A positive family history of autosomal-recessive inheritance in combination with early onset and higher grades of hearing loss significantly increased the solve rate up to 60%, while late onset and lower grades of hearing loss yielded significantly fewer diagnoses. Regarding genetic diagnoses, autosomal-dominant genes accounted for 37%, autosomal-recessive genes for 60%, and X-linked genes for 3% of the solved cases. Syndromic/nonsyndromic hearing loss mimic genes were affected in 27% of the genetic diagnoses. CONCLUSIONS: The genetic epidemiology of the largest German cohort subjected to comprehensive targeted sequencing for hereditary hearing loss to date revealed broad causal gene and variant spectra in this population. Targeted hearing loss gene panel analysis proved to be an effective tool for ensuring an appropriate diagnostic yield in a routine clinical setting including the identification of novel variants and medically significant reclassifications. Solve rates were highly sensitive to phenotypic characteristics. The unique population-adapted and balanced age distribution of the cohort favoring late hearing loss onset uncovered a markedly large contribution of autosomal-dominant genes to the diagnoses which may be a representative for other age balanced cohorts in other populations.

Aberrant COL11A1 splicing causes prelingual autosomal dominant nonsyndromic hearing loss in the DFNA37 locus.

Alpha-chain collagen molecules encoded by genes that include COL11A1 are essential for skeletal, ocular, and auditory function. COL11A1 variants have been reported in syndromes involving these organ systems. However, a description of the complete clinical spectrum is lacking, as evidenced by a recent association of autosomal dominant nonsyndromic hearing loss due to a splice-altering variant in COL11A1, mapping the DFNA37 locus. Here, we describe two German families presenting prelingual autosomal dominant nonsyndromic hearing loss with novel COL11A1 heterozygous splice-altering variants (c.652-1G>C and c.4338+2T>C) that were molecularly characterized. Interestingly, the c.652-1G>C variant affects the same intron 4 canonical splice site originally reported in the DFNA37 family (c.652-2A>C) but elicits a different splicing outcome. Furthermore, the c.4338+2T>C variant originated de novo. We provide clinical and molecular genetic evidence to unambiguously confirm that COL11A1 splice-altering variants cause DFNA37 hearing loss and affirm that COL11A1 be included in the genetic testing of patients with nonsyndromic deafness.

Age-related hearing loss pertaining to potassium ion channels in the cochlea and auditory pathway.

Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly and constitutes the third highest risk factor for dementia. Lifetime noise exposure, genetic predispositions for degeneration, and metabolic stress are assumed to be the major causes of ARHL. Both noise-induced and hereditary progressive hearing have been linked to decreased cell surface expression and impaired conductance of the potassium ion channel KV7.4 (KCNQ4) in outer hair cells, inspiring future therapies to maintain or prevent the decline of potassium ion channel surface expression to reduce ARHL. In concert with KV7.4 in outer hair cells, KV7.1 (KCNQ1) in the stria vascularis, calcium-activated potassium channels BK (KCNMA1) and SK2 (KCNN2) in hair cells and efferent fiber synapses, and KV3.1 (KCNC1) in the spiral ganglia and ascending auditory circuits share an upregulated expression or subcellular targeting during final differentiation at hearing onset. They also share a distinctive fragility for noise exposure and age-dependent shortfalls in energy supply required for sustained surface expression. Here, we review and discuss the possible contribution of select potassium ion channels in the cochlea and auditory pathway to ARHL. We postulate genes, proteins, or modulators that contribute to sustained ion currents or proper surface expressions of potassium channels under challenging conditions as key for future therapies of ARHL.

ENT Residents Benefit from a Structured Operation Planning Approach in the Training of Functional Endoscopic Sinus Surgery.

Background and Objectives: Preoperative planning utilizing computed tomographies (CT) is of utmost importance in functional endoscopic sinus surgery (FESS). Frequently, no uniform documentation and planning structures are available to residents in training. Consequently, overall completeness and quality of operation planning may vary greatly. The objective of the present study was to evaluate the impact of a structured operation planning (SOP) approach on the report quality and user convenience during a 4-day sinus surgery course. Materials and Methods: Fifteen participant were requested to plan a FESS procedure based on a CT scan of the paranasal sinuses that exhibited common pathological features, in a conventional manner, using a free text. Afterwards, the participants reevaluated the same scans by means of a specifically designed structured reporting template. Two experienced ENT surgeons assessed the collected conventional operation planning (COP) and SOP methods independently with regard to time requirements, overall quality, and legibility. User convenience data were collected by utilizing visual analogue scales. Results: A significantly greater time expenditure was associated with SOPs (183 s vs. 297 s, p = 0.0003). Yet, legibility (100% vs. 72%, p < 0.0001) and overall completeness (61.3% vs. 22.7%, p < 0.0001) of SOPs was significantly superior to COPs. Additionally, description of highly relevant variants in anatomy and pathologies were outlined in greater detail. User convenience data delineated a significant preference for SOPs (VAS 7.9 vs. 6.9, p = 0.0185). Conclusions: CT-based planning of FESS procedures by residents in training using a structured approach is more time-consuming while producing a superior report quality in terms of detailedness and readability. Consequently, SOP can be considered as a valuable tool in the process of preoperative evaluations, especially within residency.

A Big Data Perspective on the Genomics of Hearing Loss. / Big data in der Diagnostik genetischer Schwerhörigkeit.

The completion of the human genome, the most fundamental example of big data in science and medicine, is the remarkable product of multidisciplinary collaboration and is regarded as one of the largest and most successful undertakings in human history. Unravelling the human genome means not only identifying the sequence of its more than 3.2 billion nucleotide bases, but also understanding disease-associated variations and applying this knowledge to patient-tailored precision medicine approaches. Genomics has moved at a remarkable pace, with much of the propelling forces behind this credited to technological developments in sequencing, computing, and bioinformatics, that have given rise to the term "big genomics data." The analysis of genetics data in a disease context involves the use of several big data resources that take the form of clinical genetics data repositories, in silico prediction tools, and allele frequency databases. These exceptional developments have cultivated high-throughput sequencing technologies that are capable of producing affordable high-quality data ranging from targeted gene panels to exomes and genomes. These new advancements have revolutionized the diagnostic paradigm of hereditary diseases including genetic hearing loss.Dissecting hereditary hearing loss is exceptionally challenging due to extensive genetic and clinical heterogeneity. There are presently over 150 genes involved in non-syndromic and common syndromic forms of hearing loss. The mutational spectrum of a single hearing loss associated-gene can have several tens to hundreds of pathogenic variants. Moreover, variant interpretation of novel variants can pose a challenge when conflicting information is deposited in valuable databases. Harnessing the power that comes from detailed and structured phenotypic information has proven promising for some forms of hearing loss, but may not be possible for all genetic forms due to highly variable clinical presentations. New knowledge in both diagnostic and scientific realms continues to rapidly accumulate. This overwhelming amount of information represents an increasing challenge for medical specialists. As a result, specialist medical care may evolve to take on new tasks and facilitate the interface between the human genetic diagnostic laboratory and the patient. These tasks include genetic counselling and the inclusion of genetics results in patient care.This overview is intended to serve as a reference to otolaryngologists who wish to gain an introduction to the molecular genetics of hearing loss. Key concepts of molecular genetic diagnostics will be presented. The complex processes underlying the identification and interpretation of genetic variants in particular would be inconceivable without the enormous amount of data available. In this respect, "big data" is an indispensable prerequisite for filtering genetic data in specific individual cases and making it clear and useful, especially for clinicians in contact with patients.

Expression of trans-membrane serine protease 3 (TMPRSS3) in the human organ of Corti.

TMPRSS3 (Trans-membrane Serine Protease 3) is a type II trans-membrane serine protease that has proteolytic activity essential for hearing. Mutations in the gene cause non-syndromic autosomal recessive deafness (DFNB8/10) in humans. Knowledge about its cellular distribution in the human inner ear may increase our understanding of its physiological role and involvement in deafness, ultimately leading to therapeutic interventions. In this study, we used super-resolution structured illumination microscopy for the first time together with transmission electron microscopy to localize the TMPRSS3 protein in the human organ of Corti. Archival human cochleae were dissected out during petroclival meningioma surgery. Microscopy with Zeiss LSM710 microscope achieved a lateral resolution of approximately 80 nm. TMPRSS3 was found to be associated with actin in both inner and outer hair cells. TMPRSS3 was located in cell surface-associated cytoskeletal bodies (surfoskelosomes) in inner and outer pillar cells and Deiters cells and in subcuticular organelles in outer hair cells. Our results suggest that TMPRSS3 proteolysis is linked to hair cell sterociliary mechanics and to the actin/microtubule networks that support cell motility and integrity.

Long-Term Outcomes of Vibroplasty Coupler Implantations to Treat Mixed/Conductive Hearing Loss.

OBJECTIVE: To evaluate the long-term safety and performance of four different vibroplasty couplers (round window, oval window, CliP and Bell coupler) in combination with an active middle ear implant. METHODS: This was a multicentre, prospective, long-term study including 5 German hospitals. Thirty adult subjects suffering from conductive or mixed hearing loss were initially enrolled for the study, 24 of these were included in the final analysis with up to 36 months of postsurgical follow-up data. Bone conduction and air conduction were measured pre- and postoperatively to evalu ate safety. Postoperative aided sound field thresholds and Freiburger monosyllable word recognition scores were compared to unaided pre-implantation results to confirm performance. Additional speech tests compared postoperative unaided with aided results. To determine patient satisfaction, an established quality-of-life questionnaire developed for conventional hearing aid usage was administered to all subjects. RESULTS: Mean postoperative bone conduction thresholds remained stable throughout the whole study period. Mean functional gain for all couplers investigated was 38.5 ± 11.4 dB HL (12 months) and 38.8 ± 12.5 dB HL (36 months). Mean word recognition scores at 65 dB SPL increased from 2.9% in the unaided by 64.2% to 67.1% in the aided situation. The mean postoperative speech reception in quiet (or 50% understanding of words in sentences) shows a speech intelligibility improvement at 36 months of 17.8 ± 12.4 dB SPL over the unaided condition. The signal-to-noise ratio (SNR) improved by 5.9 ± 7.2 dB SNR over the unaided condition. High subjective device satisfaction was reflected by the International Inventory for Hearing Aids scored very positively. CONCLUSION: A significant improvement was seen with all couplers, and audiological performance did not significantly differ between 12 and 36 months after surgery.

Off the ear with no loss in speech understanding: comparing the RONDO and the OPUS 2 cochlear implant audio processors.

The RONDO is a single-unit cochlear implant audio processor, which omits the need for a behind-the-ear (BTE) audio processor. The primary aim was to compare speech perception results in quiet and in noise with the RONDO and the OPUS 2, a BTE audio processor. Secondary aims were to determine subjects' self-assessed levels of sound quality and gather subjective feedback on RONDO use. All speech perception tests were performed with the RONDO and the OPUS 2 behind-the-ear audio processor at 3 test intervals. Subjects were required to use the RONDO between test intervals. Subjects were tested at upgrade from the OPUS 2 to the RONDO and at 1 and 6 months after upgrade. Speech perception was determined using the Freiburg Monosyllables in quiet test and the Oldenburg Sentence Test (OLSA) in noise. Subjective perception was determined using the Hearing Implant Sound Quality Index (HISQUI19), and a RONDO device-specific questionnaire. 50 subjects participated in the study. Neither speech perception scores nor self-perceived sound quality scores were significantly different at any interval between the RONDO and the OPUS 2. Subjects reported high levels of satisfaction with the RONDO. The RONDO provides comparable speech perception to the OPUS 2 while providing users with high levels of satisfaction and comfort without increasing health risk. The RONDO is a suitable and safe alternative to traditional BTE audio processors.

Multicenter Clinical Trial of Vibroplasty Couplers to Treat Mixed/Conductive Hearing Loss: First Results.

OBJECTIVE: To evaluate the safety and effectiveness of round window (RW), oval window (OW), CliP and Bell couplers for use with an active middle ear implant. METHODS: This is a multicenter, long-term, prospective trial with consecutive enrollment, involving 6 university hospitals in Germany. Bone conduction, air conduction, implant-aided warble-tone thresholds and Freiburger monosyllable word recognition scores were compared with unaided preimplantation results in 28 moderate-to-profound hearing-impaired patients after 12 months of follow-up. All patients had previously undergone failed reconstruction surgeries (up to 5 or more). In a subset of patients, additional speech tests at 12 months postoperatively were used to compare the aided with the unaided condition after implantation with the processor switched off. An established quality-of-life questionnaire for hearing aids was used to determine patient satisfaction. RESULTS: Postoperative bone conduction remained stable. Mean functional gain for all couplers was 37 dB HL (RW = 42 dB, OW = 35 dB, Bell = 38 dB, CliP = 27 dB). The mean postoperative Freiburger monosyllable score was 71% at 65 dB SPL. The postimplantation mean SRT50 (speech reception in quiet for 50% understanding of words in sentences) improved on average by 23 dB over unaided testing and signal-to-noise ratios also improved in all patients. The International Outcome Inventory for Hearing Aids (IOI-HA)quality-of-life questionnaire was scored very positively by all patients. CONCLUSION: A significant improvement was seen with all couplers, and patients were satisfied with the device at 12 months postoperatively. These results demonstrate that an active implant is an advantage in achieving good hearing benefit in patients with prior failed reconstruction surgery.

[Surgery with laryngotracheal stenosis. Rib cartilage interposition for airway reconstruction]. / Chirurgie bei laryngotrachealen Stenosen. Rippenknorpel interponat zur Atemwegsrekonstruktion.

The surgical management of this problem is a major challenge with various optional surgical procedures. The Chinese authors show in their retrospective analysis the success of laryngotracheal reconstruction (LTR) by cartilage interposition and facial cutaneous flap in patients with complex laryngotracheal stenoses and / or anterior cervical defect.

Expression of poly(ADP-ribose) glycohydrolase in wild-type and PARG-110 knock-out retina.

Poly(ADP-ribose) (PAR) turnover is required for many cellular processes, and highly relevant for cell death and survival. This post-translational protein modification is regulated by the synthesizing enzyme poly(ADP)ribose-polymerase (PARP) and the degrading enzyme poly(ADP-ribose) glycohydrolase (PARG). Previously, PARP activity was found to be involved in photoreceptor degeneration in the rd1 mouse and in rd1-like conditions PARP-1 was the main PARP family member contributing to photoreceptor cell death. Despite the manifest role of PARP and PAR accumulation in photoreceptor cell death, the influence of PAR degradation on photoreceptor viability was still unknown. Here, we investigated the role of PARG in photoreceptor degeneration using the PARG-110 knock out mouse and report for the first time on PARG expression in wild-type and knock-out retina.

Real-world evidence for the effectiveness and safety of dupilumab in patients with CRSwNP after 1 year of therapy.

Objectives: For nearly 3 years, the monoclonal antibody dupilumab has been approved in Germany for the treatment of patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Although efficacy has been demonstrated in large double-blind, placebo-controlled clinical trials, few reports of real-world data on this therapy have been published to date. Methods: Patients with an indication for treatment with dupilumab for CRSwNP were included in the study and followed up every 3 months for a period of 1 year. At the baseline visit, demographic data, medical history, comorbidities, nasal polyp score, disease-related quality of life (SNOT-22), nasal congestion, and sense of smell (VAS and Sniffin Sticks test) were recorded. In addition, total blood eosinophil counts and serum total IgE were measured. During follow-up, all of the described parameters and possible adverse events were recorded. Results: Eighty-one patients were enrolled in the study, of whom 68 patients were still receiving dupilumab after 1 year of follow-up. Eight patients discontinued therapy, with only 1 patient discontinuing due to severe side effects. The Polyp score decreased substantially during follow-up, and parameters for disease-related quality of life and sense of smell increased significantly. Total IgE levels decreased significantly, and eosinophils leveled off at baseline after an initial increase after three months of therapy. No clinical data could be identified to a priori predict a treatment response. Conclusions: Dupilumab shows effectiveness and safety in the treatment of CRSwNP under real-world conditions. More research on systemic biomarkers and clinical parameters to predict treatment response is necessary.

Germline findings in patients with advanced malignancies screened with paired blood-tumour testing for personalised treatment approaches.

BACKGROUND: Sequencing of tumour tissue with comprehensive gene panels is increasingly used to guide treatment in precision oncology. Analysis of tumour-normal pairs allows in contrast to tumour-only assessment direct discrimination between somatic and germline alterations, which might have important implications not only for the patients but also their families. METHODS: We performed tumour normal sequencing with a large gene panel in 1048 patients with advanced cancer to support treatment decision. Sequencing results were correlated with clinical and family data. RESULTS: We identified 156 likely pathogenic or pathogenic (LP/P) germline variants in cancer predisposition genes (CPGs) in 144 cases (13.7%). Of all patients, 8.8% had a LP/P variant in autosomal-dominant cancer predisposition genes (AD-CPGs), most of them being genes with high or moderate penetrance (ATM, BRCA2, CHEK2 and BRCA1). In 48 cases, the P/LP variant matched the expected tumour spectrum. A second variant in tumour tissue was found in 31 patients with AD-CPG variants. Low frequency mutations in either TP53, ATM or DNMT3A in the normal sample indicated clonal haematopoiesis in five cases. CONCLUSIONS: Tumour-normal testing for personalised treatment identifies germline LP/P variants in a relevant proportion of patients with cancer. The majority of them would not have been referred to genetic counselling based on family history. Indirect functional readouts of tumour-normal sequencing can provide novel links between CPGs and unexpected cancers. The interpretation of increasingly complex datasets in precision oncology is challenging and concepts of interdisciplinary personalised cancer prevention are needed to support patients and their families.

TOFIMS mass spectrometry-based immunopeptidomics refines tumor antigen identification.

T cell recognition of human leukocyte antigen (HLA)-presented tumor-associated peptides is central for cancer immune surveillance. Mass spectrometry (MS)-based immunopeptidomics represents the only unbiased method for the direct identification and characterization of naturally presented tumor-associated peptides, a key prerequisite for the development of T cell-based immunotherapies. This study reports on the implementation of ion mobility separation-based time-of-flight (TOFIMS) MS for next-generation immunopeptidomics, enabling high-speed and sensitive detection of HLA-presented peptides. Applying TOFIMS-based immunopeptidomics, a novel extensive benignTOFIMS dataset was generated from 94 primary benign samples of solid tissue and hematological origin, which enabled the expansion of benign reference immunopeptidome databases with > 150,000 HLA-presented peptides, the refinement of previously described tumor antigens, as well as the identification of frequently presented self antigens and not yet described tumor antigens comprising low abundant mutation-derived neoepitopes that might serve as targets for future cancer immunotherapy development.

Co-localisation of K(ir)4.1 and AQP4 in rat and human cochleae reveals a gap in water channel expression at the transduction sites of endocochlear K(+) recycling routes.

Sensory transduction in the cochlea depends on perilymphatic-endolymphatic potassium (K(+)) recycling. It has been suggested that the epithelial supporting cells (SCs) of the cochlear duct may form the intracellular K(+) recycling pathway. Thus, they must be endowed with molecular mechanisms that facilitate K(+) uptake and release, along with concomitant osmotically driven water movements. As yet, no molecules have been described that would allow for volume-equilibrated transepithelial K(+) fluxes across the SCs. This study describes the subcellular co-localisation of the K(ir)4.1 K(+) channel (K(ir)4.1) and the aquaporin-4 water channel (AQP4) in SCs, on the basis of immunohistochemical double-labelling experiments in rat and human cochleae. The results of this study reveal the expression of K(ir)4.1 in the basal or basolateral membranes of the SCs in the sensory domain of the organ of Corti that are adjacent to hair cells and in the non-sensory domains of the inner and outer sulci that abut large extracellular fluid spaces. The SCs of the inner sulcus (interdental cells, inner sulcus cells) and the outer sulcus (Hensen's cells, outer sulcus cells) display the co-localisation of K(ir)4.1 and AQP4 expression. However, the SCs in the sensory domain of the organ of Corti reveal a gap in the expression of AQP4. The outer pillar cell is devoid of both K(ir)4.1 and AQP4. The subcellular co-localisation of K(ir)4.1 and AQP4 in the SCs of the cochlea described in this study resembles that of the astroglia of the central nervous system and the glial Mueller cells in the retina.

The ototoxic effect of locally applied kanamycin and furosemide in guinea pigs.

BACKGROUND: Hearing impairment is a growing social and economic issue. New technical or biological approaches aiming hearing rehabilitation or regeneration require animal testing. Therefore, a reproducible and safe model for hearing-impaired animals is essential. NEW METHOD: Intratympanic injection of kanamycin and furosemide was administered for BFA bunt pigmented guinea pigs for either 1 or 2 h. Hearing loss was regularly measured with compound action potential response to click and tone burst stimuli for up to 26 weeks. Hair cell loss and the density of spiral ganglion neurons were histologically analyzed. RESULTS: One week after the exposure, complete hearing loss was observed in 34 ears from the 36 ears treated for 2 h and remained stable during the follow-up. Histology revealed near complete hair cell loss and secondary degeneration of spiral ganglion neurons. COMPARISON WITH EXISTING METHODS: Animal deafening is usually achieved by systemic application of aminoglycoside antibiotics or chemotherapy drugs, although side effects such as nephrotoxicity may occur which can be avoided by local application. With our procedure, unilateral hearing loss model can also be established. CONCLUSIONS: The single intratympanic application of a solution of 200 mg/ml kanamycin and 50 mg/ml furosemide is a stable and reliable deafening method.

Neural substrates of tinnitus severity.

Subjective chronic tinnitus is a prevalent auditory perception characterized by an absence of a corresponding acoustic source. It is often accompanied by hearing deficits and may lead to various psychological problems including sleep disorder, depression and anxiety. To investigate the differential neuronal profile of patients with severe and less severe chronic tinnitus, 34 tinnitus patients were distributed in two groups and their EEG resting state activity was compared. Using standardized Low Resolution Electromagnetic Tomography (sLORETA) a significant and substantial frontal increase in theta wave activity was found in the group with severe tinnitus (p = .013). The correlated severity of depression and anxiety had no influence on the electrophysiological metric. These results support a tinnitus-related global network change in which prefrontal areas are part of a network which exerts a top-down influence on the auditory cortices. The demonstrated slowing of oscillations in the responsible network may constitute a neuronal marker for the prefrontal brain network lacking the capacity to inhibit overexcitation. The magnitude of this influence is linked to the subjective strength of the tinnitus distress.