Alzheimer9s disease (AD) is characterized by progressive cognitive decline, increasingly attributed to neuronal dysfunction induced by amyloid-β oligomers (AβOs). Although the impact of AβOs on neurons has been extensively studied, only recently have the possible effects of AβOs on astrocytes begun to be investigated. Given the key roles of astrocytes in synapse formation, plasticity, and function, we sought to investigate the impact of AβOs on astrocytes, and to determine whether this impact is related to the deleterious actions of AβOs on synapses. We found that AβOs interact with astrocytes, cause astrocyte activation and trigger abnormal generation of reactive oxygen species, which is accompanied by impairment of astrocyte neuroprotective potential in vitro. We further show that both murine and human astrocyte conditioned media (CM) increase synapse density, reduce AβOs binding, and prevent AβO-induced synapse loss in cultured hippocampal neurons. Both a neutralizing anti-transforming growth factor-β1 (TGF-β1) antibody and siRNA-mediated knockdown of TGF-β1, previously identified as an important synaptogenic factor secreted by astrocytes, abrogated the protective action of astrocyte CM against AβO-induced synapse loss. Notably, TGF-β1 prevented hippocampal dendritic spine loss and memory impairment in mice that received an intracerebroventricular infusion of AβOs. Results suggest that astrocyte-derived TGF-β1 is part of an endogenous mechanism that protects synapses against AβOs. By demonstrating that AβOs decrease astrocyte ability to protect synapses, our results unravel a new mechanism underlying the synaptotoxic action of AβOs in AD. SIGNIFICANCE STATEMENT Alzheimer9s disease is characterized by progressive cognitive decline, mainly attributed to synaptotoxicity of the amyloid-β oligomers (AβOs). Here, we investigated the impact of AβOs in astrocytes, a less known subject. We show that astrocytes prevent synapse loss induced by AβOs, via production of transforming growth factor-β1 (TGF-β1). We found that AβOs trigger morphological and functional alterations in astrocytes, and impair their neuroprotective potential. Notably, TGF-β1 reduced hippocampal dendritic spine loss and memory impairment in mice that received intracerebroventricular infusions of AβOs. Our results describe a new mechanism underlying the toxicity of AβOs and indicate novel therapeutic targets for Alzheimer9s disease, mainly focused on TGF-β1 and astrocytes.

AMP-activated kinase (AMPK) is a key player in energy sensing and metabolic reprogramming under cellular energy restriction. Several studies have linked impaired AMPK function to peripheral metabolic diseases such as diabetes. However, the impact of neurological disorders, such as Alzheimer disease (AD), on AMPK function and downstream effects of altered AMPK activity on neuronal metabolism have been investigated only recently. Here, we report the impact of Aβ oligomers (AβOs), synaptotoxins that accumulate in AD brains, on neuronal AMPK activity. Short-term exposure of cultured rat hippocampal neurons or ex vivo human cortical slices to AβOs transiently decreased intracellular ATP levels and AMPK activity, as evaluated by its phosphorylation at threonine residue 172 (AMPK-Thr(P)¹⁷²). The AβO-dependent reduction in AMPK-Thr(P)¹⁷² levels was mediated by glutamate receptors of the N-methyl-d-aspartate (NMDA) subtype and resulted in removal of glucose transporters (GLUTs) from the surfaces of dendritic processes in hippocampal neurons. Importantly, insulin prevented the AβO-induced inhibition of AMPK. Our results establish a novel toxic impact of AβOs on neuronal metabolism and suggest that AβO-induced, NMDA receptor-mediated AMPK inhibition may play a key role in early brain metabolic defects in AD.

Glioblastoma (GBM) is the most common primary brain tumor and the most aggressive glial tumor. This tumor is highly heterogeneous, angiogenic, and insensitive to radio- and chemotherapy. Here we have investigated the progression of GBM produced by the injection of human GBM cells into the brain parenchyma of immunocompetent mice.

Background: Cerebral cavernous malformations (CCM) are clusters of dilated sinusoidal channels lined by a single layer of endothelium. In contradistinction to arteriovenous malformations, these lesions do not have smooth muscle or elastin in their lining and they are angiographically occult, and the MRI is the most sensitive test for CCM detection. CCM are one of the most prevalent vascular malformations of the central nervous system, affecting about 0.4-0.6% of the general population. The main complication of this malformation is the risk of bleeding, which may cause neurological deficits that affect the quality of life (QoL) in patients. When symtomatic, they may be surgically treated for relieving the mass effect and seizures refractory to drug uses, hemorrhage and drug-refractory epilepsy. Patient-reported outcome (PRO) may be a strategy that can be used to evaluate QoL of CCM population and was used in a sample of non-operated patients. Methods: An observational, cross-sectional analysis to evaluate the PRO using the SF-36 and EuroQol 5 dimensions (EQ-5D) questionnaires of QoL added to functional metrics using the Karnofsky Performance Status (KPS) in 49 patients not submitted to intervention and with long-term follow-up. Results: During the 364 person-years of follow-up, there was an average of individual follow-up of 7.42 years. The mean age was 46.8 years (18-84) - 57% of them were female, 71% had superficial lesions, and 65% had the familial form. Comparisons of SF-36 dimensions with KPS graded <100 had a worse score only in terms of the pain (p = 0.04), vitality (p = 0.001), and general state of health (p = 0.03) domains. The domain mental health was worse in patients without surgical indication (p = 0.032). The functional capacity domain had the highest overall grading in the group. The EQ-5D dimensions of mobility (p = 0.03) and pain/discomfort (p = 0.001) were the ones with lower score compared to KPS <100. Conclusion: The study is the first to evaluate, with validated tools, the PRO of non-operated CCM patients and has demonstrated in a selected group of patients that it was possible to achieve long-term clinical stability, thereby maintaining QoL and functional neurological outcome.

Human retroelements (HERVs) are retroviral origin sequences fixed in the human genome. HERVs induction is associated with neurogenesis, cellular development, immune activation, and neurological disorders. Arboviruses are often associated with the development of encephalitis. The interplay between these viruses and HERVs has not been fully elucidated. In this work, we analyzed RNAseq data derived from infected human primary astrocytes by Zika (ZikV), Mayaro (MayV), Oropouche (OroV) and Chikungunya (ChikV) viruses, and evaluated the modulation of HERVs and their nearby genes. Our data show common HERVs expression modulation by both alphaviruses, suggesting conserved evolutionary routes of transcription regulation. A total of 15 HERVs were co-modulated by the four arboviruses, including the highly upregulated HERV4_4q22. Data on the upregulation of genes nearby to these elements in ChikV, MayV and OroV infections were also obtained, and interaction networks were built. The upregulation of 14 genes common among all viruses was observed in the networks, and 93 genes between MayV and ChikV. These genes are related to cellular processes such as cellular replication, cytoskeleton, cell vesicle traffic and antiviral response. Together, our results support the role of HERVs induction in the transcription regulation process of genes during arboviral infections.