Activation of the endoplasmic reticulum stress response by the amyloid-beta 1–40 peptide in brain endothelial cells

Neurovascular dysfunction arising from endothelial cell damage is an early pathogenic event that contributes to the neurodegenerative process occurring in Alzheimer's disease (AD). Since the mechanisms underlying endothelial dysfunction are not fully elucidated, this study was aimed to explore the hypothesis that brain endothelial cell death is induced upon the sustained activation of the endoplasmic reticulum (ER) stress response by amyloid-beta (Aβ) peptide, which deposits in the cerebral vessels in many AD patients and transgenic mice. Incubation of rat brain endothelial cells (RBE4 cell line) with Aβ1–40 increased the levels of several markers of ER stress-induced unfolded protein response (UPR), in a time-dependent manner, and affected the Ca2 + homeostasis due to the release of Ca2 + from this intracellular store. Finally, Aβ1–40 was shown to activate both mitochondria-dependent and -independent apoptotic cell death pathways. Enhanced release of cytochrome c from mitochondria and activation of the downstream caspase-9 were observed in cells treated with Aβ1–40 concomitantly with caspase-12 activation. Furthermore, Aβ1–40 activated the apoptosis effectors' caspase-3 and promoted the translocation of apoptosis-inducing factor (AIF) to the nucleus demonstrating the involvement of caspase-dependent and -independent mechanisms during Aβ-induced endothelial cell death. In conclusion, our data demonstrate that ER stress plays a significant role in Aβ1–40-induced apoptotic cell death in brain endothelial cells suggesting that ER stress-targeted therapeutic strategies might be useful in AD to counteract vascular defects and ultimately neurodegeneration

CORIOLUS VERSICOLOR BIOMASS INCREASES HIPPOCAMPAL DENTATE GYRUS NEWLY-GENERATED NEURONS COMPLEXITY IN MICE

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Susceptibility of Malassezia pachydermatis to azole antifungal agents evaluated by a new broth microdilution method

Malassezia pachydermatis   is considered an opportunistic pathogen of the outer ear duct in dogs and cats. This yeast can also be found in the skin, rectum, anal sacks and vagina. Eighty-two samples of this yeast isolated from dogs with the symptoms of external otitis from the Porto Alegre region were tested for their susceptibility to antifungal agents using the Broth Microdilution Method. The testing antifungal agents were Ketoconazole, Fluconazole and Itraconazole. Experimental essays determined that Sabouraud dextrose broth supplemented with 1% Tween 80 was the most appropriate medium for culture, for a ten-fold dilutions for the inocula, and 48 hours as the interval of readings. The ranges of the Minimal Inhibitory Concentrations (MICs) for the 82 samples were (a) Ketoconazole, from 0.015 to 0.25 mg/mL (mean of 0.08 mg/mL), (b) Fluconazole, from 1 to 32 mg/mL (mean of 9.22 mg/mL), and (c) Itraconazole, from 0.007 to 0.125 mg/mL (mean of 0.05 mg/mL). The isolates of M. pachydermatis showed an excellent level of susceptibility to antifungal azole agents, with all strains being susceptible to Itraconazole, and with only 2.4 % and 3.7% being resistant to Fluconazole and Kketoconazole, respectively. The use of the broth microdilution method allows the assessment of the susceptibility of large numbers of samples from M. pachydermatis isolates to the most common antifungal agents. The proposed procedure is easy to perform and considerably inexpensive compared with other existing tests, which makes this a method of choice for laboratorial use. A standardization of procedures currently used in veterinary mycology laboratories is required. Consistent results among laboratories could greatly benefit the establishment of proper comparisons between studies on antifungal susceptibility and therapeutic trials

Coriolus versicolor biomass increases dendritic arborization of newly-generated neurons in mouse hippocampal dentate gyrus

Brain cognitive reserve refers to the ability of the brain to manage different challenges that arise throughout life, making it resilient to neuropathology. Hippocampal adult neurogenesis has been considered to be a relevant contributor for brain cognitive reserve and brain plasticity. Coriolus versicolor (CV), a common healthful mushroom, has been receiving increasing attention by its antitumoral, anti-inflammatory, antioxidant, antibacterial, and immunomodulatory properties, including in the hippocampus. Herein, we evaluated whether CV biomass oral administration for 2.5 months enhances hippocampal neurogenic reserve under normal/physiological conditions, by quantifying hippocampal dentate gyrus (DG) granular cell layer (GCL) and subgranular zone (SGZ) volumes, proliferation, number and dendritic complexity features of hippocampal newly-generated neurons. We also analyzed β-catenin levels in DG newly-generated immature neurons, because it plays a major role in neurogenesis. Although no differences were observed in the volume of GCL and SGZ layers, in proliferation and in the number of newly-generated neurons of controls and CV-administered mice, we found that CV administration promotes a significant increase in dendritic length and branching and total dendritic volume of immature neurons, suggesting a positive effect of oral CV administration in the hippocampal neurogenic reserve. We also observed that β-catenin levels are increased both in the nucleus and cytoplasm of DG immature neurons, suggesting that Wnt/β-catenin signalling may play an important role in the CV positive effect on the differentiation of these cells. These data unveil a so far unexplored neurogenic potential of CV supplementation, which emerges as a possible preventive strategy for different neurological conditions.This work was supported by Mycology Research Laboratories, Ltd. This work was financed by the European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under projects CENTRO-01-0145-FEDER-000012-HealthyAging2020 and CENTRO-01-0145-FEDER-000008 - BrainHealth 2020, and through the COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation and Portuguese national funds via FCT – Fundação para a Ciência e a Tecnologia, under project POCI-01-0145-FEDER-007440 and Strategic Project 2015- UID/NEU/04539/2013. EF and SIM are holders of FCT postdoctoral grant (SFRH/BPD/86551/2012 and SFRH/BPD/99219/2013, respectively). J.V. salary was supported by an Ikerbasque Research Fellow grant

miRNA-31 Improves Cognition and Abolishes Amyloid-beta Pathology by Targeting APP and BACE1 in an Animal Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia worldwide, characterized by progressive memory impairment, behavioral changes, and, ultimately, loss of consciousness and death. Recently, microRNA (miRNA) dysfunction has been associated with increased production and impaired clearance of amyloid-β (Aβ) peptides, whose accumulation is one of the most well-known pathophysiological markers of this disease. In this study, we identified several miRNAs capable of targeting key proteins of the amyloidogenic pathway. The expression of one of these miRNAs, miR-31, previously found to be decreased in AD patients, was able to simultaneously reduce the levels of APP and Bace1 mRNA in the hippocampus of 17-month-old AD triple-transgenic (3xTg-AD) female mice, leading to a significant improvement of memory deficits and a reduction in anxiety and cognitive inflexibility. In addition, lentiviral-mediated miR-31 expression significantly ameliorated AD neuropathology in this model, drastically reducing Aβ deposition in both the hippocampus and subiculum. Furthermore, the increase of miR-31 levels was enough to reduce the accumulation of glutamate vesicles in the hippocampus to levels found in non-transgenic age-matched animals. Overall, our results suggest that miR-31-mediated modulation of APP and BACE1 can become a therapeutic option in the treatment of AD.This work was financed by the European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under the project CENTRO-01-0145-FEDER-000008: BrainHealth 2020 and through the COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation and Portuguese national funds via FCT - Fundação para a Ciência e a Tecnologia, under the project POCI- 01-0145-FEDER-007440 (reference UID/NEU/04539/2013). This work was also supported by the FCT Investigator Programme (IF/ 00694/2013 to J.P.), the Marie Curie Carrier Integration Grant (PCIG13-GA-2013-618525 to J.P.), HEALTHYAGING 2020 (CENTRO-01-0145-FEDER-000012 to A.T.B.-V.), and Bial Foundation Grant 264/16. A.T.B.-V., J.G., and A.L.C. are recipients of fellowships from the FCT (Grants PTDC/BIM-MEC/0651/2012, SFRH/ BPD/120611/2016, and SFRH/BPD/108312/2015)

Regulation of hippocampal postnatal and adult neurogenesis by adenosine A 2A receptor: Interaction with brain-derived neurotrophic factor

21 páginas, 7 figuras.Adenosine A2A receptor (A2A R) activation modulates several brain processes, ranging from neuronal maturation to synaptic plasticity. Most of these actions occur through the modulation of the actions of the neurotrophin brain-derived neurotrophic factor (BDNF). In this work, we studied the role of A2A Rs in regulating postnatal and adult neurogenesis in the rat hippocampal dentate gyrus (DG). Here, we show that A2A R activation with CGS 21680 promoted neural stem cell self-renewal, protected committed neuronal cells from cell death and contributed to a higher density of immature and mature neuronal cells, particularly glutamatergic neurons. Moreover, A2A R endogenous activation was found to be essential for BDNF-mediated increase in cell proliferation and neuronal differentiation. Our findings contribute to further understand the role of adenosinergic signaling in the brain and may have an impact in the development of strategies for brain repair under pathological conditions.Fundaç~ao para a Ciência e a Tecnologia, Grant/Award Numbers: IF/01227/2015, SFRH/BD/74662/2010, IMM/CT/35-2018, SFRH/BD/128280/2017, SFRH/BD/129710/2017; H2020-WIDESPREAD-05-2020-Twinning (EpiEpinet) under grant agreement No, Grant/Award Number: 9524; Ministerio de Ciencia e Innovaci on, Grant/Award Number: PID2019-111225RB-I00; Spanish MICIU, Grant/Award Number: SAF2015-70433-R; Generalitat Valenciana, Grant/Award Number: PROMETEO/2018/055; COST Action, Grant/Award Number: BM1402Peer reviewe

Ataxin-3 phosphorylation decreases neuronal defects in spinocerebellar ataxia type 3 models

Different neurodegenerative diseases are caused by aberrant elongation of repeated glutamine sequences normally found in particular human proteins. Although the proteins involved are ubiquitously distributed in human tissues, toxicity targets only defined neuronal populations. Changes caused by an expanded polyglutamine protein are possibly influenced by endogenous cellular mechanisms, which may be harnessed to produce neuroprotection. Here, we show that ataxin-3, the protein involved in spinocerebellar ataxia type 3, also known as Machado-Joseph disease, causes dendritic and synapse loss in cultured neurons when expanded. We report that S12 of ataxin-3 is phosphorylated in neurons and that mutating this residue so as to mimic a constitutive phosphorylated state counters the neuromorphologic defects observed. In rats stereotaxically injected with expanded ataxin-3–encoding lentiviral vectors, mutation of serine 12 reduces aggregation, neuronal loss, and synapse loss. Our results suggest that S12 plays a role in the pathogenic pathways mediated by polyglutamine-expanded ataxin-3 and that phosphorylation of this residue protects against toxicity

Mild-to-Moderate Kidney Dysfunction and Cardiovascular Disease: Observational and Mendelian Randomization Analyses

BACKGROUND: End-stage renal disease is associated with a high risk of cardiovascular events. It is unknown, however, whether mild-to-moderate kidney dysfunction is causally related to coronary heart disease (CHD) and stroke. METHODS: Observational analyses were conducted using individual-level data from 4 population data sources (Emerging Risk Factors Collaboration, EPIC-CVD [European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease Study], Million Veteran Program, and UK Biobank), comprising 648 135 participants with no history of cardiovascular disease or diabetes at baseline, yielding 42 858 and 15 693 incident CHD and stroke events, respectively, during 6.8 million personyears of follow-up. Using a genetic risk score of 218 variants for estimated glomerular filtration rate (eGFR), we conducted Mendelian randomization analyses involving 413 718 participants (25917 CHD and 8622 strokes) in EPIC-CVD, Million Veteran Program, and UK Biobank. RESULTS: There were U-shaped observational associations of creatinine-based eGFR with CHD and stroke, with higher risk in participants with eG FR values 105 mL.min(-1).1.73 m(-2), compared with those with eG FR between 60 and 105 mL.min(-1).1.73 m(-2). Mendelian randomization analyses for CHD showed an association among participants with eGFR 105 mL.min(-1).1.73 m(-2). Results were not materially different after adjustment for factors associated with the eGFR genetic risk score, such as lipoprotein(a), triglycerides, hemoglobin Alc, and blood pressure. Mendelian randomization results for stroke were nonsignificant but broadly similar to those for CHD. CONCLUSIONS: In people without manifest cardiovascular disease or diabetes, mild-to-moderate kidney dysfunction is causally related to risk of CHD, highlighting the potential value of preventive approaches that preserve and modulate kidney function

Chronic hyperglycemia impairs hippocampal neurogenesis and memory in an Alzheimer's disease mouse model

During aging, lifestyle-related factors shape the brain's response to insults and modulate the progression of neurodegenerative pathologies such as Alzheimer's disease (AD). This is the case for chronic hyperglycemia associated with type 2 diabetes, which reduces the brain's ability to handle the neurodegenerative burden associated with AD. However, the mechanisms behind the effects of chronic hyperglycemia in the context of AD are not fully understood. Here, we show that newly generated neurons in the hippocampal dentate gyrus of triple transgenic AD (3xTg-AD) mice present increased dendritic arborization and a number of synaptic puncta, which may constitute a compensatory mechanism allowing the animals to cope with a lower neurogenesis rate. Contrariwise, chronic hyperglycemia decreases the complexity and differentiation of 3xTg-AD newborn neurons and reduces the levels of β-catenin, a key intrinsic modulator of neuronal maturation. Moreover, synaptic facilitation is depressed in hyperglycemic 3xTg-AD mice, accompanying the defective hippocampal-dependent memory. Our data suggest that hyperglycemia evokes cellular and functional alterations that accelerate the onset of AD-related symptoms, namely memory impairment