Losartan prevents tumor-induced hearing loss and augments radiation efficacy in NF2 schwannoma rodent models

Losartan May Not Prevent Vestibular Schwannoma Growth or Related Hearing Loss During Observation

OBJECTIVE

To evaluate the impact of losartan on vestibular schwannoma (VS) growth and related hearing loss during observation.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Sporadic VS patients undergoing initial observation with at least two magnetic resonance imaging and audiologic examinations.

INTERVENTION

Losartan.

MAIN OUTCOME MEASURES

Endpoints included VS growth, quantitative audiologic changes, survival free of tumor growth, and survival free of nonserviceable hearing. Patient characteristics and endpoints were compared by losartan use.

RESULTS

Seventy-nine patients were included, of which 33% were taking losartan. Tumor growth was observed in 50% of patients in the losartan group and 36% in the non-losartan group (p = 0.329). Survival analysis failed to show a significant difference in the hazard rate of VS growth between groups (hazard ratio, 1.38; 95% confidence interval, 0.70-2.70; p = 0.346). Throughout observation, mean decreases in normalized pure-tone average were 5.5 and 9.3 dB in the losartan and non-losartan groups, respectively (p = 0.908). Mean decreases in normalized word recognition score were 11.0 and 16.6% in the losartan and non-losartan groups, respectively (p = 0.757). Nonserviceable hearing developed in 19% of patients in the losartan group and 28% in the non-losartan group (p = 0.734). Survival analysis did not demonstrate a significant difference in the hazard rate of developing nonserviceable hearing between groups (hazard ratio, 1.71; 95% confidence interval, 0.56-5.21; p = 0.337).

CONCLUSIONS

Losartan use may not reduce the risk of VS growth or hearing loss during observation. A randomized trial would be ideal to further identify the true effect on growth and hearing.

Inhibiting AGTR1 reduces AML burden and protects the heart from cardiotoxicity in mouse models

Clinical treatment of acute myeloid leukemia (AML) largely relies on intensive chemotherapy. However, the application of chemotherapy is often hindered by cardiotoxicity. Patient sequence data revealed that angiotensin II receptor type 1 (AGTR1) is a shared target between AML and cardiovascular disease (CVD). We found that inhibiting AGTR1 sensitized AML to chemotherapy and protected the heart against chemotherapy-induced cardiotoxicity in a human AML cell-transplanted mouse model. These effects were regulated by the AGTR1-Notch1 axis in AML cells and cardiomyocytes from mice. In mouse cardiomyocytes, AGTR1 was hyperactivated by AML and chemotherapy. AML leukemogenesis increased the expression of the angiotensin-converting enzyme and led to increased production of angiotensin II, the ligand of AGTR1, in an MLL-AF9-driven AML mouse model. In this model, the AGTR1-Notch1 axis regulated a variety of genes involved with cell stemness and chemotherapy resistance. AML cell stemness was reduced after Agtr1a deletion in the mouse AML cell transplant model. Mechanistically, Agtr1a deletion decreased γ-secretase formation, which is required for transmembrane Notch1 cleavage and release of the Notch1 intracellular domain into the nucleus. Using multiomics, we identified AGTR1-Notch1 signaling downstream genes and found decreased binding between these gene sequences with Notch1 and chromatin enhancers, as well as increased binding with silencers. These findings describe an AML/CVD association that may be used to improve AML treatment.

Integrating Ataxia Evaluation into Tumor-Induced Hearing Loss Model to Comprehensively Study NF2-Related Schwannomatosis

NF2-related Schwannomatosis (NF2-SWN) is a disease that needs new solutions. The hallmark of NF2-SWN, a dominantly inherited neoplasia syndrome, is bilateral vestibular schwannomas (VSs), which progressively enlarge, leading to sensorineural hearing loss, tinnitus, facial weakness, and pain that translates to social impairment and clinical depression. Standard treatments for growing VSs include surgery and radiation therapy (RT); however, both carry the risk of further nerve damage that can result in deafness and facial palsy. The resultant suffering and debility, in combination with the paucity of therapeutic options, make the effective treatment of NF2-SWN a major unmet medical need. A better understanding of these mechanisms is essential to developing novel therapeutic targets to control tumor growth and improve patients' quality of life. Previously, we developed the first orthotopic cerebellopontine angle mouse model of VSs, which faithfully mimics tumor-induced hearing loss. In this model, we observed that mice exhibit symptoms of ataxia and vestibular dysfunction. Therefore, we further developed a panel of five tests suitable for the mouse VS model and investigated how tumor growth and treatment affect gait, coordination, and motor function. Using this panel of ataxia tests, we demonstrated that both ataxia and motor function deteriorated concomitantly with tumor progression. We further demonstrated that (i) treatment with anti-VEGF resulted in tumor size reduction, mitigated ataxia, and improved rotarod performance; (ii) treatment with crizotinib stabilized tumor growth and led to improvements in both ataxia and rotarod performance; and (iii) treatment with losartan did not impact tumor growth nor ameliorate ataxia or motor function. Our studies demonstrated that these methods, paired with hearing tests, enable a comprehensive evaluation of tumor-induced neurological deficits and facilitate the assessment of the effectiveness of novel therapeutics to improve NF2 treatments.

Normalizing granuloma vasculature and matrix improves drug delivery and reduces bacterial burden in tuberculosis-infected rabbits

Host-directed therapies (HDTs) represent an emerging approach for bacterial clearance during tuberculosis (TB) infection. While most HDTs are designed and implemented for immuno-modulation, other host targets-such as nonimmune stromal components found in pulmonary granulomas-may prove equally viable. Building on our previous work characterizing and normalizing the aberrant granuloma-associated vasculature, here we demonstrate that FDA-approved therapies (bevacizumab and losartan, respectively) can be repurposed as HDTs to normalize blood vessels and extracellular matrix (ECM), improve drug delivery, and reduce bacterial loads in TB granulomas. Granulomas feature an overabundance of ECM and compressed blood vessels, both of which are effectively reduced by losartan treatment in the rabbit model of TB. Combining both HDTs promotes secretion of proinflammatory cytokines and improves anti-TB drug delivery. Finally, alone and in combination with second-line antitubercular agents (moxifloxacin or bedaquiline), these HDTs significantly reduce bacterial burden. RNA sequencing analysis of HDT-treated lung and granuloma tissues implicates up-regulated antimicrobial peptide and proinflammatory gene expression by ciliated epithelial airway cells as a putative mechanism of the observed antitubercular benefits in the absence of chemotherapy. These findings demonstrate that bevacizumab and losartan are well-tolerated stroma-targeting HDTs, normalize the granuloma microenvironment, and improve TB outcomes, providing the rationale to clinically test this combination in TB patients.

Immune Profiling of Secreted Factors from Human Vestibular Schwannoma Cells and Tumor-associated Macrophages

OBJECTIVES

This study compared the immune-related secretory capacity of human vestibular schwannoma (VS) and tumor-assisted macrophages (TAMs) with their normal counterparts (Schwann cells [SC] and peripheral blood monocyte-derived macrophages [Mo-MFs], respectively), and examined relationships with presurgical hearing and tumor size.

METHODS

VS tumors (n = 16), auditory nerve (n = 1), blood (n = 9), and great auricular nerves (n = 3) were used. SCs (S100B+ ) and TAMs (CD68+ ) were isolated from VS tissue for culture. The secreted levels of 65 immune-related factors were measured and compared using unpaired t-tests with Welch correction (schwannoma vs. SCs) or Mann-Whitney tests (TAMs and Mo-MFs). Associations between factor concentration and word recognition (WR), pure-tone average (PTA), and tumor size were evaluated with Spearman correlation.

RESULTS

Secreted factors with significantly higher concentrations in schwannoma versus SC supernatants included IL-2 and BAFF, whereas MMP-1, IL-6, FGF-2, VEGF-A, MIP-3α, and GRO-α concentrations were significantly higher in TAMs versus Mo-MFs (all p < 0.05). Worse WR was significantly associated with higher secretion of fractalkine, eotaxin-3, CD30, and IL-16 by VS cells; IP-10, eotaxin-3, multiple interleukins, GM-CSF, SCF, and CD30 by TAMs; and TNF-α and MIP-1α by Mo-MFs (all p < 0.05). Worse PTA was significantly correlated with higher secretion of IL-16 by VS cells (p < 0.05). Larger tumor size was significantly correlated with higher secretion of eotaxin by VS cells, and of IL-7, IL-21, and LIF by TAMs (all p = 0.017).

CONCLUSIONS

Differential secretion of immune-related factors was observed in schwannoma versus normal SCs and in TAMs versus Mo-MFs, some of which were correlated with worse hearing and larger VS tumors.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:S1-S14, 2024.

Soft and stretchable organic bioelectronics for continuous intraoperative neurophysiological monitoring during microsurgery

In microneurosurgery, it is crucial to maintain the structural and functional integrity of the nerve through continuous intraoperative identification of neural anatomy. To this end, here we report the development of a translatable system leveraging soft and stretchable organic-electronic materials for continuous intraoperative neurophysiological monitoring. The system uses conducting polymer electrodes with low impedance and low modulus to record near-field action potentials continuously during microsurgeries, offers higher signal-to-noise ratios and reduced invasiveness when compared with handheld clinical probes for intraoperative neurophysiological monitoring and can be multiplexed, allowing for the precise localization of the target nerve in the absence of anatomical landmarks. Compared with commercial metal electrodes, the neurophysiological monitoring system allowed for enhanced post-operative prognoses after tumour-resection surgeries in rats. Continuous recording of near-field action potentials during microsurgeries may allow for the precise identification of neural anatomy through the entire procedure.

Management of Bevacizumab-Induced Proteinuria Using an Angiotensin Receptor Blocker (ARB) in a Neurofibromatosis Type 2 (NF-2) Patient With Vestibular Schwannoma

Neurofibromatosis type 2 (NF-2) is a genetic condition that by definition includes bilateral vestibular schwannoma, a non-malignant lesion also known as acoustic neuroma. Patients often develop hearing impairment and hearing loss as a result of the involvement of the vestibulocochlear nerve bilaterally as well as attempts at surgical repair. A common treatment for NF-2-mediated schwannoma is the antiangiogenic agent, bevacizumab. In many cases, patients require prolonged and even lifelong treatment with bevacizumab to control schwannoma growth. However, long-term use of bevacizumab can be associated with multiple side effects including hypertension and proteinuria including nephrotic syndrome (>3g of protein excreted in the urine in 24 hours). In these situations, the challenge with discontinuing prolonged bevacizumab can be rapid tumor growth and worsening hearing loss. Pre-clinical data suggests that hearing loss can be prevented following treatment with the angiotensin receptor blocker (ARB), losartan, in an animal model of NF-2. ARBs are already established in nephrology guidelines to treat proteinuria and hypertension. Here, we present a patient with NF-2 who developed nephrotic syndrome while on bevacizumab. Attempts to discontinue bevacizumab resulted in near-immediate hearing loss. Treatment with the ARB telmisartan together with bevacizumab resulted in improved hearing, reduced proteinuria, and controlled hypertension.

Angiotensin II receptor inhibition ameliorates liver fibrosis and enhances hepatocellular carcinoma infiltration by effector T cells

Although viral hepatocellular carcinoma (HCC) is declining, nonviral HCC, which often is the end stage of nonalcoholic or alcoholic steatohepatitis (NASH, ASH), is on an upward trajectory. Immune checkpoint inhibitors (ICIs) that block the T cell inhibitory receptor PD-1 were approved for treatment of all HCC types. However, only a minority of HCC patients show a robust and sustained response to PD-1 blockade, calling for improved understanding of factors that negatively impact response rate and duration and the discovery of new adjuvant treatments that enhance ICI responsiveness. Using a mouse model of NASH-driven HCC, we identified peritumoral fibrosis as a potential obstacle to T cell-mediated tumor regression and postulated that antifibrotic medications may increase ICI responsiveness. We now show that the angiotensin II receptor inhibitor losartan, a commonly prescribed and safe antihypertensive drug, reduced liver and peritumoral fibrosis and substantially enhanced anti-PD-1-induced tumor regression. Although losartan did not potentiate T cell reinvigoration, it substantially enhanced HCC infiltration by effector CD8+ T cells compared to PD-1 blockade alone. The beneficial effects of losartan correlated with blunted TGF-β receptor signaling, reduced collagen deposition, and depletion of immunosuppressive fibroblasts.

Targeted Therapies in the Treatment of Vestibular Schwannomas: Current State and New Horizons

Vestibular schwannomas continue to cause hearing loss, facial nerve paralysis, imbalance, and tinnitus. These symptoms are compounded by germline neurofibromatosis type 2 (NF2) gene loss and multiple intracranial and spinal cord tumors associated with NF2-related schwannomatosis. The current treatments of observation, microsurgical resection, or stereotactic radiation may prevent catastrophic brainstem compression but are all associated with the loss of cranial nerve function, particularly hearing loss. Novel targeted treatment options to stop tumor progression include small molecule inhibitors, immunotherapy, anti-inflammatory drugs, radio-sensitizing and sclerosing agents, and gene therapy.

The NLRP3 inflammasome as a target for sensorineural hearing loss

Sensorineural hearing loss is the most common type of hearing loss in adults and occurs due to damage of the inner ear caused by a range of factors including ageing, excessive noise, toxins, and cancer. Auto-inflammatory disease is also a cause of hearing loss and there is evidence that inflammation could contribute to hearing loss in other conditions. Within the inner ear there are resident macrophage cells that respond to insults and whose activation correlates with damage. The NLRP3 inflammasome is a multi-molecular pro-inflammatory protein complex that forms in activated macrophages and may contribute to hearing loss. The aim of this article is to discuss the evidence for the NLRP3 inflammasome and associated cytokines as potential therapeutic targets for sensorineural hearing loss in conditions ranging from auto-inflammatory disease to tumour-induced hearing loss in vestibular schwannoma.

Angiotensin II receptor inhibition ameliorates liver fibrosis and enhances hepatocellular carcinoma infiltration by effector T cells

Although viral hepatocellular carcinoma (HCC) is declining, non-viral HCC, which often is the end-stage of non-alcoholic or alcoholic steatohepatitis (NASH, ASH), is on an upward trajectory. Immune checkpoint inhibitors (ICI) that block the T cell inhibitory receptor PD-1 were approved for treatment of all HCC types. However, only a small portion of HCC patients show a robust and sustained response to PD-1 blockade, calling for improved understanding of factors that negatively impact response rate and duration and the discovery of new adjuvant treatments that enhance ICI responsiveness. Using a mouse model of NASH-driven HCC, we identified peritumoral fibrosis as a potential obstacle to T cell mediated tumor regression and postulated that anti-fibrotic medications may increase ICI responsiveness. We now show that the angiotensin II receptor inhibitor losartan, a commonly prescribed and safe antihypertensive drug, reduced liver and peritumoral fibrosis and substantially enhanced anti-PD-1 induced tumor regression. Although losartan did not potentiate T cell reinvigoration, it substantially enhanced HCC infiltration by effector CD8 ⁺ T cells compared to PD-1 blockade alone. The beneficial effects of losartan correlated with inhibition of TGF-β receptor signaling, collagen deposition and depletion of immunosuppressive fibroblasts.

Significance

Immune checkpoint inhibitors are used in HCC treatment but overall response rates for single agent PD-1/PD-L1 blockers have remained stubbornly low. Using a mouse model of NASH-driven HCC, we show that co-treatment with the safe and inexpensive angiotensin II receptor inhibitor losartan substantially enhanced anti-PD-1 triggered HCC regression. Although losartan did not influence the reinvigoration of exhausted CD8 ⁺ T cells it considerably enhanced their intratumoral invasion, which we postulated to be compromised by peritumoral fibrosis. Indeed, the beneficial effect of losartan correlated with inhibition of TGF-β signaling and collagen deposition, and depletion of immunosuppressive fibroblasts. Losartan should be evaluated for its adjuvant activity in HCC patients undergoing PD-1/PD-L1 blocking therapy.

Continuously perfusable, customisable, and matrix-free vasculature on a chip platform

Creating vascularised cellular environments in vitro is a current challenge in tissue engineering and a bottleneck towards developing functional stem cell-derived microtissues for regenerative medicine and basic investigations. Here we have developed a new workflow to manufacture vasculature on chip (VoC) systems efficiently, quickly, and inexpensively. We have employed 3D printing for fast-prototyping of bespoke VoC and coupled them with a refined organotypic culture system (OVAA) to grow patent capillaries in vitro using tissue-specific endothelial and stromal cells. Furthermore, we have designed and implemented a pocket-size flow driver to establish physiologic perfusive flow throughout our VoC-OVAA with minimal medium use and waste. Using our platform, we have created vascularised microtissues and perfused them at physiologic flow rates for extended time (>2 weeks) observing flow-dependent vascular remodelling. Overall, we present for the first time a scalable and customisable system to grow vascularised and perfusable microtissues, a key initial step to grow mature and functional tissues in vitro. We envision that this technology will empower fast prototyping and validation of increasingly biomimetic in vitro systems, including interconnected multi-tissue systems.

Antisense oligonucleotides targeting exon 11 are able to partially rescue the NF2-related schwannomatosis phenotype in vitro

NF2-related schwannomatosis (NF2-related SWN) is an autosomal dominant condition caused by loss of function variants in the NF2 gene, which codes for the protein Merlin and is characterized by the development of multiple tumors of the nervous system. The clinical presentation of the disease is variable and related to the type of the inherited germline variant. Here, we tested if phosphorodiamidate morpholino oligomers (PMOs) could be used to correct the splice signaling caused by variants at ±13 within the intron-exon boundary region and showed that the PMOs designed for these variants do not constitute a therapeutic approach. Furthermore, we evaluated the use of PMOs to decrease the severity of the effects of NF2 truncating variants with the aim of generating milder hypomorphic isoforms in vitro through the induction of the in-frame deletion of the exon-carrying variant. We were able to specifically induce the skipping of exons 4, 8, and 11 maintaining the NF2 gene reading frame at cDNA level. Only the skipping of exon 11 produced a hypomorphic Merlin (Merlin-e11), which is able to partially rescue the observed phenotype in primary fibroblast cultures from NF2-related SWN patients, being encouraging for the treatment of patients harboring truncating variants located in exon 11.

Synergy of Losartan and chemotherapy for patients with cholangiocarcinoma: A propensity score-matched analysis

Background

Cholangiocarcinoma (CCA) is a malignant tumor originating from bile duct epithelial cells that no obvious clinical symptoms and specific clinical manifestations are shown in the early stage of CCA.

Methods

Propensity score matching (PSM) is a quasi-experimental method in which this study used. Patients were enrolled from Department of General surgery, First Affiliated Hospital of Jinzhou Medical University from March 1, 2010, to December 30, 2019. Totally 170 patients with CCA were enrolled in this study.

Results

We performed a 1:2 PSM study and found that patients with losartan group showed both comparable median OS (overall survival) and TTR (time to recurrence) to those in the patients without losartan group before PSM. However, after matching, patients with losartan group showed favorable median OS and TTR than those in the patients without losartan group. Then we performed Cox proportional hazards models and found that patients with losartan was an independent factor after multivariable analysis for patients with CCA. Furtherly, we sequenced serial cfDNA were performed in 10 patients with losartan and 9 patients without losartan who received adjuvant chemotherapy after tumor resection. These results showed that the treatment of losartan was related with tumor microenvironment and could be potentially useful to combine the immunotherapy for patients with CCA.

Conclusion

In conclusion, this study demonstrated that the treatment of losartan could increase the efficacy of adjuvant chemotherapy and identified as an independent survival predictor for patients with CCA. Moreover, losartan could be potentially useful to combine the immunotherapy for patients with CCA.

Qu-Du-San-Jie decoction induces growth inhibition and vascular normalization in NF2-associated vestibular schwannoma

Background: Neurofibromatosis type 2 (NF2) is a rare genetic syndrome that predisposes individuals to develop bilateral vestibular schwannomas (VSs) causing a high risk of life-threatening neurological complications. Traditional treatment options for NF2-associated VS usually cause neurological damage, and to date, there are no FDA-approved pharmacotherapies for NF2. The aim of this study was to evaluate the antitumor efficacy of Qu-Du-San-Jie (QDSJ) decoction, a traditional Chinese medicine formula, on NF2-associated VS and to investigate the potential underlying mechanisms.

Methods: Ultra high-performance liquid chromatography-mass spectroscopy (UHPLC-MS) analysis was performed to identify the components of QDSJ and their targets. To determine the relationships between the putative targets of QDSJ and the differential genes of NF2-associated VS, the drug-disease crossover genes were screened using the UHPLC-MS data combined with our previous gene expression profiling data. The differentially expressed genes were imported into the STRING database to generate a PPI network. Differentially expressed gene targets and pathways were identified using GO and KEGG pathway enrichment analyses. The in vitro and in vivo drug efficacy of QDSJ decoction was tested using a patient-derived schwannoma cell line and a patient-derived xenograft mouse model, respectively. H&amp;E staining, immunochemistry, and immunofluorescence staining were used to evaluate the cell proliferation and tumor vessels.

Results: A total of 133 compounds were identified in QDSJ decoction using UHPLC-MS analysis. Network pharmacology showed that the regulation of necroptosis, apoptosis, cell cycle, angiogenesis, adherens junction, and neuroactive ligand-receptor interaction could be associated with the efficacy of QDSJ in treating NF2-associated VS. Treatment with QDSJ induced necrotic cell death and apoptosis of schwannoma cells in vitro and suppressed the tumor growth in vivo. Histopathological analysis revealed areas of cell necrosis and enlarged tumor blood vessels in the QDSJ-treated tumors. The numbers of cells positive for Cyclin D1 and Ki-67 were significantly reduced in QDSJ-treated tumors compared to control tumors. Immunofluorescence staining of CD31 and αSMA showed a decreased number and density of tumor vessels and normalized vessel structure in QDSJ-treated tumors.

Conclusion: Our study demonstrates that QDSJ decoction shows significant antitumor activity against NF2-associated schwannoma and is a possible candidate for future clinical trials.

Understanding the Molecular Mechanism of Vestibular Schwannoma for Hearing Preservation Surgery: Otologists’ Perspective from Bedside to Bench

Vestibular schwannoma is a clinically benign schwannoma that arises from the vestibulocochlear nerve that causes sensorineural hearing loss. This tumor is clinically and oncologically regarded as a benign tumor as it does not metastasize or invade surrounding tissues. Despite being a benign tumor, its management is difficult and controversial due to the potential serious complications, such as irreversible sensorineural hearing loss, of current interventions. Therefore, preventing hearing loss due to the natural course of the disease and complications of surgery is a challenging issue for an otologist. Improvements have been reported recently in the treatment of vestibular schwannomas. These include advances in intraoperative monitoring systems for vestibular schwannoma surgery where the risk of hearing loss as a complication is decreased. Precise genomic analysis of the tumor would be helpful in determining the characteristics of the tumor for each patient, leading to a better hearing prognosis. These procedures are expected to help improve the treatment of vestibular schwannomas. This review summarizes recent advances in vestibular schwannoma management and treatment, especially in hearing preservation. In addition, recent advances in the understanding of the molecular mechanisms underlying vestibular schwannomas and how these advances can be applied in clinical practice are outlined and discussed, respectively. Moreover, the future directions from the bedside to the bench side are presented from the perspective of otologists.

Novel patient-derived xenograft and cell line models for therapeutic screening in NF2-associated schwannoma

Treatment of schwannomas in patients with neurofibromatosis type 2 (NF2) is extremely unsatisfactory, and innovative therapeutic approaches are urgently needed. However, the lack of clinically relevant NF2-associated schwannoma models has severely hampered drug discovery in this rare disease. Here, we report the first establishment and characterization of patient-derived xenograft (PDX) and cell line models of NF2-associated schwannoma, which recapitulate the morphological and histopathological features of patient tumors, retain patient NF2 mutations, and maintain gene expression profiles resembling patient tumor profiles with the preservation of multiple key signaling pathways commonly dysregulated in human schwannomas. Using gene expression profiling, we identified elevated PI3K/AKT/mTOR networks in human NF2-associated vestibular schwannomas. Using high-throughput screening of 157 inhibitors targeting the PI3K/AKT/mTOR pathways in vitro, we identified a dozen inhibitors (such as BEZ235, LY2090314, and AZD8055) with significant growth-suppressive effects. Interestingly, we observed that three cell lines displayed differential therapeutic responses to PI3K/AKT/mTOR inhibitors. Furthermore, we demonstrated two orally bioavailable inhibitors AZD8055 and PQR309 suppressed NF2-associated schwannoma growth both in vitro and in vivo. In conclusion, our novel patient-derived models of NF2-associated schwannoma closely mimic the phenotypes and genotypes of patient tumors, making them reliable preclinical tools for testing novel personalized therapies. This article is protected by copyright. All rights reserved.

Sporadic Vestibular Schwannoma Size and Location Do not Correlate With the Severity of Hearing Loss at Initial Presentation

Vestibular schwannoma (VS) is a non-malignant intracranial neoplasm arising from the vestibular branch of the 8th cranial nerve; sensorineural hearing loss (SNHL) is the most common associated symptom. Understanding whether VS imaging characteristics at the time of VS diagnosis can be associated with severity of VS-induced SNHL can impact patient counseling and define promising areas for future research. Patients diagnosed with VS at Massachusetts Eye and Ear (MEE) from 1994 through 2018 were analyzed if magnetic resonance imaging at VS presentation and sequential audiometry were available. Results were compared with original studies available in PubMed, written in English, on VS imaging characteristics and their impact on hearing in patients. A total of 477 patients with unilateral VS from the MEE database demonstrated no significant correlation between any features of tumor imaging at the time of VS diagnosis, such as VS size, impaction or location, and any hearing loss metric. Twenty-three published studies on the impact of VS imaging characteristics on patient hearing met inclusion criteria, with six solely involving NF2 patients and three including both sporadic and NF2-related VS patients. Fifteen studies reported a significant relationship between SNHL and at least one VS imaging characteristic; however, these trends were universally limited to NF2 patients or involved small patient populations, and were not reproduced in larger studies. Taken together, SNHL in sporadic VS patients is not readily associated solely with any tumor imaging characteristics. This finding motivates future studies to define how VS microenvironment and secreted molecules influence VS-induced SNHL.

Molecular and Clinical Significance of Fibroblast Growth Factor 2 in Development and Regeneration of the Auditory System

The fibroblast growth factor 2 (FGF2) is a member of the FGF family which is involved in key biological processes including development, cellular proliferation, wound healing, and angiogenesis. Although the utility of the FGF family as therapeutic agents has attracted attention, and FGF2 has been studied in several clinical contexts, there remains an incomplete understanding of the molecular and clinical function of FGF2 in the auditory system. In this review, we highlight the role of FGF2 in inner ear development and hearing protection and present relevant clinical studies for tympanic membrane (TM) repair. We conclude by discussing the future implications of FGF2 as a potential therapeutic agent.

Potential Molecular Biomarkers of Vestibular Schwannoma Growth: Progress and Prospects

Vestibular schwannomas (VSs, also known as acoustic neuromas) are relatively rare benign brain tumors stem from the Schwann cells of the eighth cranial nerve. Tumor growth is the paramount factor for neurosurgeons to decide whether to choose aggressive treatment approach or careful follow-up with regular magnetic resonance imaging (MRI), as surgery and radiation can introduce significant trauma and affect neurological function, while tumor enlargement during long-term follow-up will compress the adjacent nerves and tissues, causing progressive hearing loss, tinnitus and vertigo. Recently, with the deepening research of VS biology, some proteins that regulate merlin conformation changes, inflammatory cytokines, miRNAs, tissue proteins and cerebrospinal fluid (CSF) components have been proposed to be closely related to tumor volume increase. In this review, we discuss advances in the study of biomarkers that associated with VS growth, providing a reference for exploring the growth course of VS and determining the optimal treatment strategy for each patient.