Analysis of tumor microenvironment composition in vestibular schwannomas: insights into NF2-associated and sporadic variations and their clinical correlations.

Objective: Vestibular schwannomas (VS), benign tumors stemming from the eighth cranial nerve's Schwann cells, are associated with Merlin gene mutations, inflammation, and the tumor microenvironment (TME), influencing tumor initiation, maintenance, and potential neural dysfunction. Understanding TME composition holds promise for systemic therapeutic interventions, particularly for NF2-related schwannomatosis. Methodology: A retrospective analysis of paraffin-embedded tissue from 40 patients (2013-2020), evenly divided by neurofibromatosis type 2 status, with further stratification based on magnetic resonance imaging (MRI) progression and hearing function. Immunohistochemistry assessed TME components, including T-cell markers (CD4, CD8, CD25), NK cells (CD7), and macrophages (CD14, CD68, CD163, CCR2). Fiji software facilitated image analysis. Results: T-cell markers (CD4, CD8, CD7) exhibited low expression in VS, with no significant NF2-associated vs. sporadic distinctions. Macrophage-related markers (CD14, CD68, CD163, CCR2) showed significantly higher expression (CD14: p = 0.0187, CD68: p < 0.0001, CD163: p = 0.0006, CCR2: p < 0.0001). CCR2 and CD163 significantly differed between NF2-associated and sporadic VS. iNOS, an M1-macrophage marker, was downregulated. CD25, a regulatory T-cell marker, correlated significantly with tumor growth dynamics (p = 0.016). Discussion: Immune cells, notably monocytes and macrophages, crucially contribute to VS pathogenesis in both NF2-associated and sporadic cases. Significant differences in CCR2 and CD163 expression suggest distinct immune responses. Regulatory T-cells may serve as growth dynamic markers. These findings highlight immune cells as potential biomarkers and therapeutic targets for managing VS.

Development of a vestibular schwannoma tumor slice model for pharmacological testing.

BACKGROUND: Our goal was to develop a 3D tumor slice model, replicating the individual tumor microenvironment and for individual pharmaceutical testing in vestibular schwannomas with and without relation to NF2. METHODS: Tissue samples from 16 VS patients (14 sporadic, 2 NF2-related) were prospectively analyzed. Slices of 350 µm thickness were cultured in vitro, and the 3D tumor slice model underwent thorough evaluation for culturing time, microenvironment characteristics, morphology, apoptosis, and proliferation rates. Common drugs - Lapatinib (10 µM), Nilotinib (20 µM), and Bevacizumab (10 µg/ml) - known for their responses in VS were used for treatment. Treatment responses were assessed using CC3 as an apoptosis marker and Ki67 as a proliferation marker. Standard 2D cell culture models of the same tumors served as controls. RESULTS: The 3D tumor slice model accurately mimicked VS ex vivo, maintaining stability for three months. Cell count within the model was approximately tenfold higher than in standard cell culture, and the tumor microenvironment remained stable for 46 days. Pharmacological testing was feasible for up to three weeks, revealing interindividual differences in treatment response to Lapatinib and intraindividual variability in response to Lapatinib and Nilotinib. The observed effects were less pronounced in tumor slices than in standard cell culture, indicating the model's proximity to in vivo tumor biology and enhanced realism. Bevacizumab had limited impact in both models. CONCLUSION: This study introduces a 3D tumor slice model for sporadic and NF2-related VS, demonstrating stability for up to 3 months, replication of the schwannoma microenvironment, and utility for individualized pharmacological testing.

[Neurofibromatosis]. / Neurofibromatose.

BACKGROUND & FOCUS: While the Neurofibromatoses have been observed and classified by their phenotypes for several centuries, their great variability constitutes a considerable challenge in diagnostics and therapy selection. This article focuses on highlighting the three most frequent sub-types NF1, NF2 and NF3. METHODS: All three NF types are outlined by the following measures: the history of their clinical detection, the typical appearance, the underlying genetic constitution and its consequences, the official diagnostic criteria, the mandatory diagnostic steps and finally the treatment opportunities and specific risks. RESULTS: About 50% of NF patients have a positive family history and the other 50% are the first symptomatic generations and suffer from new mutations. A considerable (unknown) number of patients do not exhibit a complete genetic NF constitution, but have a so-called mosaic sub-form with only a limited number of cells being genetically affected and prone to tumorous changes. The neurofibromatoses are neuro-cutaneous diseases with manifestations at the skin and nervous system, except for NF 3, where the skin and eyes are never affected. Skin and eye manifestations, especially pigmentation disturbances, mostly started early in childhood and adolescence. The underlying genetic constitutions, on chromosome 17 in NF1 and on chromosome 22 in NF2 and NF3, cause a defect in tumor suppressor genes and lead to excessive proliferation of Schwann cells. Major features are tumors of the peripheral nerves, including cranial and spinal nerves leading to tumors with considerable nerve, brain and spinal cord compression and resulting in pain, sensory and motor deficits. A further variable disease feature may be neuropathy with neuropathic pain, related to tumor formation or even independent of it.Although benign by histopathology and growing rather slowly, those tumors often cause progressive neurological deficit and loss of function. Loss of function may be prevented by adequate timing of therapy such as nerve decompression by microsurgical tumor resection or reduction, medication with immunotherapy or radiotherapy in selected cases. To date it is unknown why some tumors remained silent and stable while others progress and show periods of accelerated growth.As a consequence, NF patients need to be accompanied by a specialized interdisciplinary NF team at long-term, with a clear-cut standardized protocol for clinical and imaging controls along with counseling and support in decision-making.Further, NF patients may suffer from reactive depression due to the danger of losing essential neural functions, such as vision or audition or movement. And especially NF1 patients show characteristics of ADHS and other cognitive compromise in at least 50% of cases. CONCLUSIONS: As the neurofibromatosis belong to the so-called rare diseases, all patients with a suspicion or diagnosis of NF should get the opportunity to present to an interdisciplinary NF Center, mostly situated at University Hospitals, where competent counseling on the individual disease phenotype may be provided. Here the patients will be informed on the necessary diagnostic steps, their frequency as well as on practical steps in case of acute deterioration. Most NF centers are run by neurosurgeons or neurologists or pediatricians, working in a network with geneticists, neuro-radiologists, ophthalmologists, dermatologists, plastic and general surgeons, psychologists, psychiatrists and social work experts. They participate regularly in neuro-oncological tumor and sarcoma tumor boards, skull base tumor centers, comprehensive hearing centers, and deliver all the treatment opportunities provided by certified brain tumor centers, among those the inclusion in special diagnostic and treatment studies or the contact information to patient support groups.