Exosomal TNF-α mediates voltage-gated Na+ channels 1.6 overexpression and contributes to brain-tumor induced neuronal hyperexcitability.

Patients affected by glioma frequently suffer of epileptic discharges, however the causes of brain tumor-related epilepsy (BTRE) are still not completely understood. We investigated the mechanisms underlying BTRE by analyzing the effects of exosomes released by U87 glioma cells and by patient-derived glioma cells. Rat hippocampal neurons incubated for 24 h with these exosomes exhibited increased spontaneous firing, while their resting membrane potential shifted positively by 10-15 mV. Voltage clamp recordings demonstrated that the activation of the Na+ current shifted towards more hyperpolarized voltages by 10-15 mV. To understand the factors inducing hyperexcitability we focused on exosomal cytokines. Western Blot and ELISA assays show that TNF-α is present inside glioma-derived exosomes. Remarkably, incubation with TNF-α fully mimicked the phenotype induced by exosomes, with neurons firing continuously, while their resting membrane potential shifted positively. RT-PCR revealed that both exosomes and TNF-α induced over-expression of the voltage-gated Na channel Nav1.6, a low-threshold Na+ channel responsible for hyperexcitability. When neurons were preincubated with Infliximab, a specific TNF-α inhibitor, the hyperexcitability induced by exosomes and TNF-α were drastically reduced. We propose that Infliximab, an FDA approved drug to treat rheumatoid arthritis, could ameliorate the conditions of glioma patients suffering of BTRE.

The longevity-associated BPIFB4 gene supports cardiac function and vascularization in ageing cardiomyopathy.

AIMS: The ageing heart naturally incurs a progressive decline in function and perfusion that available treatments cannot halt. However, some exceptional individuals maintain good health until the very late stage of their life due to favourable gene-environment interaction. We have previously shown that carriers of a longevity-associated variant (LAV) of the BPIFB4 gene enjoy prolonged health spans and lesser cardiovascular complications. Moreover, supplementation of LAV-BPIFB4 via an adeno-associated viral vector improves cardiovascular performance in limb ischaemia, atherosclerosis, and diabetes models. Here, we asked whether the LAV-BPIFB4 gene could address the unmet therapeutic need to delay the heart's spontaneous ageing. METHODS AND RESULTS: Immunohistological studies showed a remarkable reduction in vessel coverage by pericytes in failing hearts explanted from elderly patients. This defect was attenuated in patients carrying the homozygous LAV-BPIFB4 genotype. Moreover, pericytes isolated from older hearts showed low levels of BPIFB4, depressed pro-angiogenic activity, and loss of ribosome biogenesis. LAV-BPIFB4 supplementation restored pericyte function and pericyte-endothelial cell interactions through a mechanism involving the nucleolar protein nucleolin. Conversely, BPIFB4 silencing in normal pericytes mimed the heart failure pericytes. Finally, gene therapy with LAV-BPIFB4 prevented cardiac deterioration in middle-aged mice and rescued cardiac function and myocardial perfusion in older mice by improving microvasculature density and pericyte coverage. CONCLUSIONS: We report the success of the LAV-BPIFB4 gene/protein in improving homeostatic processes in the heart's ageing. These findings open to using LAV-BPIFB4 to reverse the decline of heart performance in older people.

The dual action of glioma-derived exosomes on neuronal activity: synchronization and disruption of synchrony.

Seizures represent a frequent symptom in gliomas and significantly impact patient morbidity and quality of life. Although the pathogenesis of tumor-related seizures is not fully understood, accumulating evidence indicates a key role of the peritumoral microenvironment. Brain cancer cells interact with neurons by forming synapses with them and by releasing exosomes, cytokines, and other small molecules. Strong interactions among neurons often lead to the synchronization of their activity. In this paper, we used an in vitro model to investigate the role of exosomes released by glioma cell lines and by patient-derived glioma stem cells (GSCs). The addition of exosomes released by U87 glioma cells to neuronal cultures at day in vitro (DIV) 4, when neurons are not yet synchronous, induces synchronization. At DIV 7-12 neurons become highly synchronous, and the addition of the same exosomes disrupts synchrony. By combining Ca2+ imaging, electrical recordings from single neurons with patch-clamp electrodes, substrate-integrated microelectrode arrays, and immunohistochemistry, we show that synchronization and de-synchronization are caused by the combined effect of (i) the formation of new neuronal branches, associated with a higher expression of Arp3, (ii) the modification of synaptic efficiency, and (iii) a direct action of exosomes on the electrical properties of neurons, more evident at DIV 7-12 when the threshold for spike initiation is significantly reduced. At DIV 7-12 exosomes also selectively boost glutamatergic signaling by increasing the number of excitatory synapses. Remarkably, de-synchronization was also observed with exosomes released by glioma-associated stem cells (GASCs) from patients with low-grade glioma but not from patients with high-grade glioma, where a more variable outcome was observed. These results show that exosomes released from glioma modify the electrical properties of neuronal networks and that de-synchronization caused by exosomes from low-grade glioma can contribute to the neurological pathologies of patients with brain cancers.

The Longevity-Associated Variant of BPIFB4 Reduces Senescence in Glioma Cells and in Patients' Lymphocytes Favoring Chemotherapy Efficacy.

Glioblastoma (GBM) is the most common primary brain cancer with the median age at diagnosis around 64 years, thus pointing to aging as an important risk factor. Indeed, aging, by increasing the senescence burden, is configured as a negative prognostic factor for GBM stage. Furthermore, several anti-GBM therapies exist, such as temozolomide (TMZ) and etoposide (ETP), that unfortunately trigger senescence and the secretion of proinflammatory senescence-associated secretory phenotype (SASP) factors that are responsible for the improper burst of (i) tumorigenesis, (ii) cancer metastasis, (iii) immunosuppression, and (iv) tissue dysfunction. Thus, adjuvant therapies that limit senescence are urgently needed. The longevity-associated variant (LAV) of the bactericidal/permeability-increasing fold-containing family B member 4 (BPIFB4) gene previously demonstrated a modulatory activity in restoring age-related immune dysfunction and in balancing the low-grade inflammatory status of elderly people. Based on the above findings, we tested LAV-BPIFB4 senotherapeutic effects on senescent glioblastoma U87-MG cells and on T cells from GBM patients. We interrogated SA-ß-gal and HLA-E senescence markers, SASP factors, and proliferation and apoptosis assays. The results highlighted a LAV-BPIFB4 remodeling of the senescent phenotype of GBM cells, enhancement of their sensitivity to temozolomide and a selective reduction of the T cells' senescence from GBM patients. Overall, these findings candidate LAV-BPIFB4 as an adjuvant therapy for GBM.

Heart failure impairs the mechanotransduction properties of human cardiac pericytes.

The prominent impact that coronary microcirculation disease (CMD) exerts on heart failure symptoms and prognosis, even in the presence of macrovascular atherosclerosis, has been recently acknowledged. Experimental delivery of pericytes in non-revascularized myocardial infarction improves cardiac function by stimulating angiogenesis and myocardial perfusion. Aim of this work is to verify if pericytes (Pc) residing in ischemic failing human hearts display altered mechano-transduction properties and to assess which alterations of the mechano-sensing machinery are associated with the observed impaired response to mechanical cues. RESULTS: Microvascular rarefaction and defects of YAP/TAZ activation characterize failing human hearts. Although both donor (D-) and explanted (E-) heart derived cardiac Pc support angiogenesis, D-Pc exert this effect significantly better than E-Pc. The latter are characterized by reduced focal adhesion density, decreased activation of the focal adhesion kinase (FAK)/ Crk-associated substrate (CAS) pathway, low expression of caveolin-1, and defective transduction of extracellular stiffness into cytoskeletal stiffening, together with an impaired response to both fibronectin and lysophosphatidic acid. Importantly, Mitogen-activated protein kinase kinase inhibition restores YAP/TAZ nuclear translocation. CONCLUSION: Heart failure impairs Pc mechano-transduction properties, but this defect could be reversed pharmacologically.