Extracellular vesicles derived from human vestibular schwannomas associated with poor hearing damage cochlear cells.

BACKGROUND: Vestibular schwannoma (VS) is a tumor of the vestibular nerve that transmits balance information from the inner ear to the brain. Sensorineural hearing loss occurs in 95% of patients with these tumors, but the cause of this loss is not well understood. We posit a role of VS-secreted extracellular vesicles (EVs) as a major contributing factor in cochlear nerve damage. METHODS: Using differential centrifugation, we isolated EVs from VS cell line HEI-193 and primary cultured human VS cells from patients with good hearing or poor hearing. The EVs were characterized using a Nanosight device and transmission electron microscopy and by extracting their RNA content. The EVs' effects on cultured murine spiral ganglion cells and organotypic cochlear cultures were studied using a transwell dual-culture system and by direct labeling of EVs with PKH-67 dye. EV-induced changes in cochlear cells were quantified using confocal immunohistochemistry. Transfection of VS cells with a green fluorescent protein-containing plasmid was confirmed with reverse transcription PCR. RESULTS: Human VS cells, from patients with poor hearing, produced EVs that could damage both cultured murine cochlear sensory cells and neurons. In contrast, EVs derived from VS cells from patients with good hearing did not damage the cultured cochlear cells. CONCLUSIONS: This is the first report on EVs derived from VSs and on the capacity of EVs from VSs from patients with hearing loss to selectively damage cochlear cells, thereby identifying a potential novel mechanism of VS-associated sensorineural hearing loss.

Activation of TRAIL-DR5 pathway promotes sensorineural degeneration in the inner ear.

Tumor necrosis factor (TNF) family cytokines are important mediators of inflammation. Elevated levels of serum TNF-α are associated with human sensorineural hearing loss via poorly understood mechanisms. We demonstrate, for the first time, expression of TNF-related apoptosis-inducing ligand (TRAIL) and its signaling death receptor 5 (DR5) in the murine inner ear and show that exogenous TRAIL can trigger hair cell and neuronal degeneration, which can be partly prevented with DR5-blocking antibodies.

Secreted Factors from Human Vestibular Schwannomas Can Cause Cochlear Damage.

Vestibular schwannomas (VSs) are the most common tumours of the cerebellopontine angle. Ninety-five percent of people with VS present with sensorineural hearing loss (SNHL); the mechanism of this SNHL is currently unknown. To establish the first model to study the role of VS-secreted factors in causing SNHL, murine cochlear explant cultures were treated with human tumour secretions from thirteen different unilateral, sporadic VSs of subjects demonstrating varied degrees of ipsilateral SNHL. The extent of cochlear explant damage due to secretion application roughly correlated with the subjects' degree of SNHL. Secretions from tumours associated with most substantial SNHL resulted in most significant hair cell loss and neuronal fibre disorganization. Secretions from VSs associated with good hearing or from healthy human nerves led to either no effect or solely fibre disorganization. Our results are the first to demonstrate that secreted factors from VSs can lead to cochlear damage. Further, we identified tumour necrosis factor alpha (TNFα) as an ototoxic molecule and fibroblast growth factor 2 (FGF2) as an otoprotective molecule in VS secretions. Antibody-mediated TNFα neutralization in VS secretions partially prevented hair cell loss due to the secretions. Taken together, we have identified a new mechanism responsible for SNHL due to VSs.

Multi-centric prospective evaluation of rk39 rapid test and direct agglutination test for the diagnosis of visceral leishmaniasis in Brazil.

The diagnosis of visceral leishmaniasis (VL) is still a major problem in Brazil and several other countries where the disease is endemic. The use of an easy-to-use and interpret, sensitive, and specific method that requires no complex infrastructure or specialized professionals, such as direct agglutination test (DAT) and the rK39-based rapid immunochromatographic test may enhance the diagnosis of disease. This study evaluated the performance of a rapid test (DiaMed- IT-LEISH®) and the DAT for the diagnosis of VL in 213 parasitologically confirmed cases and 119 controls with clinical suspicion of VL and confirmation of another etiology. The sensitivities and specificities of the rapid test were 93% and 97%, respectively and those of the DAT were 90% and 96%, respectively. The positive predictive values of the rapid test and the DAT were 98% and 97%, respectively and the negative predictive values were 89% and 84%, respectively. The Kappa index showed agreement between both methods classified as substantial (0.77). This study showed that the DAT and the rapid test can be used to diagnose VL in Brazil, following a pilot study for implementation of the rapid test in the health services.