BDNF mRNA expression is significantly upregulated in vestibular schwannomas and correlates with proliferative activity

Hearing loss and vestibular schwannoma: new insights into Schwann cells implication

Hearing loss (HL) is the most common and heterogeneous disorder of the sensory system, with a large morbidity in the worldwide population. Among cells of the acoustic nerve (VIII cranial nerve), in the cochlea are present the hair cells, the spiral ganglion neurons, the glia-like supporting cells, and the Schwann cells (SCs), which alterations have been considered cause of HL. Notably, a benign SC-derived tumor of the acoustic nerve, named vestibular schwannoma (VS), has been indicated as cause of HL. Importantly, SCs are the main glial cells ensheathing axons and forming myelin in the peripheral nerves. Following an injury, the SCs reprogram, expressing some stemness features. Despite the mechanisms and factors controlling their biological processes (i.e., proliferation, migration, differentiation, and myelination) have been largely unveiled, their role in VS and HL was poorly investigated. In this review, we enlighten some of the mechanisms at the base of SCs transformation, VS development, and progression, likely leading to HL, and we pose great attention on the environmental factors that, in principle, could contribute to HL onset or progression. Combining the biomolecular bench-side approach to the clinical bedside practice may be helpful for the diagnosis, prediction, and therapeutic approach in otology.

Tumor Microenvironment in Sporadic Vestibular Schwannoma: A Systematic, Narrative Review

Although diagnosis and treatment of vestibular schwannomas (VSs) improved in recent years, no factors have yet been identified as being capable of predicting tumor growth. Molecular rearrangements occur in neoplasms before any macroscopic morphological changes become visible, and the former are the underlying cause of disease behavior. Tumor microenvironment (TME) encompasses cellular and non-cellular elements interacting together, resulting in a complex and dynamic key of tumorigenesis, drug response, and treatment outcome. The aim of this systematic, narrative review was to assess the level of knowledge on TME implicated in the biology, behavior, and prognosis of sporadic VSs. A search (updated to November 2022) was run in Scopus, PubMed, and Web of Science electronic databases according to the PRISMA guidelines, retrieving 624 titles. After full-text evaluation and application of inclusion/exclusion criteria, 37 articles were included. VS microenvironment is determined by the interplay of a dynamic ecosystem of stromal and immune cells which produce and remodel extracellular matrix, vascular networks, and promote tumor growth. However, evidence is still conflicting. Further studies will enhance our understanding of VS biology by investigating TME-related biomarkers able to predict tumor growth and recognize immunological and molecular factors that could be potential therapeutic targets for medical treatment.

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.

Immunoexpression of BDNF, TrkB, and p75NTR receptors in peripheral neural lesions of the head and neck

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and neurotrophin receptors have been recognized as fundamental regulators of normal brain development, homeostasis, and plasticity. They have also been studied in the behavior of central nervous system tumors. Here, we studied the pattern of BDNF, TrkB and p75NTR immunoexpression in peripheral benign and malignant neural lesions in head and neck.

METHODS

This cross-sectional analytical study included 79 cases of head and neck neural lesions. Nineteen cases of traumatic neuromas (TN), 20 cases of granular cell tumors (GCT), 16 cases of neurofibromas (NF), 20 cases of schwannomas (SC), and 4 malignant peripheral nerve sheath tumor (MPNST) were submitted to immunohistochemistry with BDNF, TrkB, and p75NTR antibodies. A semi-quantitative analysis was performed.

RESULTS

The analysis of BDNF demonstrated a high percentage of positive cells in TN, GCT and SC with a decrease in cases of NF and MPNST. TrkB presented a lower significant immunoexpression in GCT in relation to the TN, NF, SC, and MPNST (P < .0001); and TN showed less percentage of positive cell compared to SC (P = .0017). Regarding p75NTR, the percentage of positive cell was significantly reduced in MPNST compared GCT (P = .009), NF (P = .0138) and SC (P = .0069). Also, a decrease in TN compared to GCT (P = .007) was observed.

CONCLUSIONS

Our results showed the immunoreactivity of BDNF, TrkB, and p75NTR in head and neck peripheral neural lesions. Reduction of BDNF and p75NTR in MPNST might suggest down-regulation during the acquisition of malignant phenotype.

Age-related schwannomatosis with potential exosome-mediated contribution to prostate hyperplasia: a case report and mini-review

A 72-year-old Caucasian man incurring a prostate hypertrophy presented with a right forearm nodule, the growth of which appeared to parallel the rise in his blood prostate-specific antigen (PSA) level. Echographic examination was consistent with a median-nerve schwannoma, and was confirmed upon magnetic resonance imaging (MRI). Excision of the nodule was readily performed without significant neural damage, and its schwannoma nature was confirmed upon immunohistochemistry analysis. Importantly, blood PSA dropped abruptly from ≈13 to ≈5 ng/ml within 2 months postschwannoma resection, a swift drastic reduction unachievable with oral dutasteride alone. However, 6 weeks later, a new nodule became apparent on the back of the left knee and was identified as a second schwannoma, thereby suggesting that its growth could have been stimulated by the resection of the first schwannoma, as previously described for vestibular schwannomas. The second schwannoma was in fact two: the bigger one was in the common fibular nerve and the smaller one in the tibial nerve. Both echography and MRI results were confirmed upon surgical resection of the bigger knee schwannoma. Although the third schwannoma has not yet been resected and formally characterized, we face a schwannomatosis case with an unexpected potential exosome-mediated stimulating effect on PSA secretion (PSA immunohistochemistry was negative on both schwannomas). On the other hand, preliminary genomic analysis showed a deficient balance for chromosome 22, the very chromosome carrying the three main genes involved in schwannomatosis. This age-related schwannomatosis case is thus discussed in light of the following: age-related DNA repair deficiency culminating in loss of chromosome/heterozygosity; CpG methylation/demethylation-based epigenetic aging; age-related functional decline of the immune system responsible for inefficient elimination of abnormal cells and subsequent tumorigenic cell turn-over; exosome-mediated pathologic intercellular communications; and prostate-invading brain neural progenitors as pathologic peripheral nervous system (PNS) cells.

Single Local Application of TGF-β Promotes a Proregenerative State Throughout a Chronically Injured Nerve

BACKGROUND

The lack of nerve regeneration and functional recovery occurs frequently when injuries involve large nerve trunks because insufficient mature axons reach their targets in the distal stump and because of the loss of neurotrophic support, primarily from Schwann cells (SCs).

OBJECTIVE

To investigate whether a single application of transforming growth factor-beta (TGF-β) plus forskolin or forskolin alone can promote and support axonal regeneration through the distal nerve stump.

METHODS

Using a delayed repair rat model of nerve injury, we transected the tibial nerve. After 8 wk, end-to-end repair was done and the repair site was treated with saline, forskolin, or TGF- β plus forskolin. After 6 wk, nerve sections consisting of the proximal stump, distal to the site of repair, and the most distal part of the nerve stump were removed for nerve histology, axon counts, and immunohistochemistry for activated SCs (S100), macrophages (CD68), cell proliferation (Ki67), p75NGFR, and apoptosis (activated caspase-3).

RESULTS

TGF-β plus forskolin significantly increased the numbers of axons regenerated distal to the repair site and the most distal nerve sections. Both treatments significantly increased the numbers of axons regenerated in the most distal nerve sections compared to saline treated. Both treatments exhibited extended expression of regeneration-associated marker proteins.

CONCLUSION

TGF-β plus forskolin treatment of chronically injured nerve improved axonal regeneration and increased expression of regeneration-associated proteins beyond the repair site. This suggests that a single application at the site of repair has mitogenic effects that extended distally and may potentially overcome the decrease in regenerated axon over long distance.

Risk Factors of Acoustic Neuroma: Systematic Review and Meta-Analysis

PURPOSE

Many epidemiological studies have investigated environmental risk factors for the development of acoustic neuroma. However, these results are controversial. We conducted a meta-analysis of case-control studies to identify any potential relationship between history of noise exposure, smoking, allergic diseases, and risk of acoustic neuroma.

MATERIALS AND METHODS

We searched PubMed to identify relevant articles. Two researchers evaluated the eligibility and extracted the data independently.

RESULTS

Eleven case-control studies were included in our meta-analysis. Acoustic neuroma was found to be associated with leisure noise exposure [odds ratio (OR)=1.33, 95% confidence interval (CI): 1.05-1.68], but not with occupational noise exposure and ever noise exposure (OR=1.20, 95% CI: 0.84-1.72 and OR=1.15, 95% CI: 0.80-1.65). The OR of acoustic neuroma for ever (versus never) smoking was 0.53 (95% CI: 0.30-0.94), while the subgroup analysis indicated ORs of 0.95 (95% CI: 0.81-1.10) and 0.49 (95% CI: 0.41-0.59) for ex-smoker and current smoker respectively. The ORs for asthma, eczema, and seasonal rhinitis were 0.98 (95% CI: 0.80-1.18), 0.91 (95% CI: 0.76-1.09), and 1.52 (95% CI: 0.90-2.54), respectively.

CONCLUSION

Our meta-analysis is suggestive of an elevated risk of acoustic neuroma among individuals who were ever exposed to leisure noise, but not to occupational noise. Our study also indicated a lower acoustic neuroma risk among ever and current cigarette smokers than never smokers, while there was no significant relationship for ex-smokers. No significant associations were found between acoustic neuroma and history of any allergic diseases, such as asthma, eczema, and seasonal rhinitis.

Preclinical validation of anti-nuclear factor-kappa B therapy to inhibit human vestibular schwannoma growth

Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells from the great auricular nerve were also treated with BAY11 and curcumin to assess toxicity. All three treatments significantly reduced proliferation in primary VS cultures and HEI-193 cells, with siRNA, 5 μM BAY11 and 50 μM curcumin reducing average proliferation (±standard error of mean) to 62.33% ± 10.59%, 14.3 ± 9.7%, and 23.0 ± 20.9% of control primary VS cells, respectively. These treatments also induced substantial cell death. Curcumin, unlike BAY11, also affected primary Schwann cells. This work highlights NF-κB as a key modulator in VS cell proliferation and survival and demonstrates therapeutic efficacy of directly targeting NF-κB in VS.

Primary intraocular ancient schwannoma: a case report and review of the literature

BACKGROUND

Schwannomas comprise 8% to 10% of all primary intracranial tumors. Primary intraorbital schwannomas are rare, accounting for 1% to 2% of all intracranial tumors. Schwannomas arise from Schwann cells in the myelin sheaths of sensory and cranial nerves.

METHODS

We present the case of a 56-year-old white man blind since 1970 who presented to an outside hospital for a painful right eye. Physicians identified no clinical or radiologic features of neurofibromatosis.

RESULTS

The patient underwent enucleation; the final pathologic diagnosis was ancient schwannoma.

CONCLUSION

We describe herein a case of intrascleral schwannoma with ancient changes arising within the globe of the right eye occupying the subretinal space and completely replacing the vitreous body.

BAY 61-3606, CDKi, and sodium butyrate treatments alter gene expression in human vestibular schwannomas and cause cell death in vitro

Background:

Disrupted kinase and signaling pathways are found in many human cancers and they are implicated in carcinogenesis. Therefore, kinases have been important targets for the development of cancer therapeutics. Human vestibular schwannomas (VS) are the third most common intracranial tumours which occur in the vestibular branch of VIII^th cranial nerve. Sodium butyrate (Na-Bu) is a potent histone deacetylase inhibitor (HDACi) and with therapeutic efficacy. Spleen tyrosine kinase (Syk) has been implicated in many immunological consequences and is a putative target for cancer treatment.

Aims and objectives:

The present study was undertaken in order to evaluate the effect Na-Bu, 2,4-Diamino-5-oxo-pyrimidine hydrochloride (CDKi), a broad spectrum kinase inhibitor and BAY 61-3606 (Syk inhibitor) on the survival of VS tumour tissues in vitro and their possible effects on cell survival/death and levels of a few key proteins in the treated cells as compared to the untreated cells.

Materials and methods

Fresh tumour tissues were collected randomly from 16 patients with sporadic, VS tumours, minced into pieces and maintained in primary cultures. Twenty four hours later these cells were exposed to Na-Bu, BAY 61-3606 or CDKi. Forty eight hours after exposure, the tissue lysates were analysed by western blotting for expression of pRb and other proteins involved in cell survival/death.

Summary and significance of the findings:

The tissue samples used were positive for S100A protein, the maker for schwann cells confirming the VS tumour samples. The three individual treatments led to morphological change, DNA fragmentation and cell death and significantly reduced level of total and phosphorylated forms of pRb protein and drastically reduced EGF-R protein. These treatments also modulated levels of other proteins involved in cell survival/death such as PI3K, Caspase 3, TGF-β1, JNK, ASK1, Shh, NF-κB, p21^cip1/waf1. The Untreated cells had uncleaved PARP-1 protein and the treated cells had cleaved PARP-1. The results show that the observed cell death in treated cells perhaps is mediated by modulation of the levels and processing of certain key proteins. The possible development of these components as therapeutics is discussed.

The microenvironment in the Hirschsprung's disease gut supports myenteric plexus growth

INTRODUCTION

The transplantation of neural crest derived stem cells (NCSC) is a potent alternative for the treatment of Hirschsprung's disease (HSCR). Cells to be transplanted should find an appropriate microenvironment to survive and differentiate. Influences of HSCR-smooth-muscle-protein extracts upon isolated myenteric plexus cells, dissociated dorsal root ganglia and NCSC were studied in vitro to investigate the quality of this microenvironment effects.

METHODS

Postnatal human gut from children undergoing colonic resection due to HSCR was divided in segments. Smooth muscle was dissected and homogenized. Glial-cell-line-derived-neurotrophic-factor (GDNF) and transforming-growth-factor-β-1 (TGFβ-1) concentration were measured in the homogenates from the individual segment using ELISA. Myenteric plexus and dissociated dorsal root ganglia (DRG) cultures, as well as NCSCs were exposed to protein extracts derived from ganglionic and aganglionic HSCR segments, and their effect upon neurite outgrowth, survival, and branching was evaluated.

RESULTS AND CONCLUSIONS

The amount of the factors varied considerably between the individual segments and also from patient to patient. Four major expression patterns could be detected. While all extracts tested lead to a significant increase in neurite outgrowth compared to the control, extracts from proximal segments tended to have more prominent effects. In one experiment, extracts from all individual segments of a single patient were tested. Neurite outgrowth, neuronal survival, and branching pattern varied from segment to segment, but all HSCR-muscle-protein extracts increased neuronal survival and network formation. Smooth muscle protein from aganglionic bowel supports the survival and outgrowth of myenteric neurons and NCSCs and is so an appropriate target for neural stem cell treatment.

Smooth muscle proteins from Hirschsprung's disease facilitates stem cell differentiation

BACKGROUND AND AIMS

The transplantation of neural crest derived stem cells (NCSC's) is a potent alternative for the treatment of Hirschsprung's disease (HSCR). Cells to be transplanted should find an appropriate microenvironment to survive and differentiate. To investigate the quality of this microenvironment, effects of HSCR-smooth-muscle-protein extracts upon NCSC's were studied in vitro.

METHODS

Postnatal human gut from children undergoing colonic resection due to HSCR was divided in segments. Smooth muscle was dissected and homogenized. Glial-cell-line-derived-neurotrophic-factor (GDNF) concentration was measured in the homogenates from the individual segment using ELISA. NCSC's were exposed to protein extracts derived from ganglionic and aganglionic HSCR segments, and their effect upon neurite outgrowth, survival and branching was evaluated.

RESULTS

The amount of the factors varied considerably between the proximal and distal segments, and also from patient to patient. While extracts from proximal segments tended to have more prominent effects, all HSCR-muscle-protein extracts increased neuronal survival and network formation.

CONCLUSION

Muscle protein from aganglionic bowel supports the survival and outgrowth of NCSC's and is so an appropriate target for neural stem cell treatment.