1,721,000 research outputs found
Metabotropic glutamate receptor 5 as a target for the modulation of the reactive astrocyte phenotype in the SOD1G93A mouse model of amyotrophic lateral sclerosis.
No full textAmyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder due to upper and lower motor neurons (MNs) death. Recognized as a non-cell autonomous disease, ALS is also characterized by damage and degeneration of glial cells, such as astrocytes, microglia, and oligodendrocytes. In particular, astrocytes acquire a reactive and toxic phenotype defined by an abnormal proliferation and by the release of neurotoxic factors.
One major cause for MN degeneration in ALS is represented by the glutamate-mediated excitotoxicity, due to the alteration of glutamate transmission mechanisms, including glutamate receptor function. In this context, the Group I metabotropic glutamate receptor 5 (mGluR5) has been proposed to play an important role in ALS, since it is largely overexpressed during disease progression and is involved in the altered neuronal and glial cellular processes. We previously demonstrated that mGluR5 produces abnormal glutamate release in the spinal cord of the SOD1G93A mouse model of ALS and that halving its expression has a positive impact on in-vivo disease progression, including motor neuron survival, astrogliosis and microgliosis.
We here investigated the consequences of reducing the mGluR5 expression in SOD1G93A mice on the reactive phenotype of spinal cord astrocytes cultured from late symptomatic (120 days old) SOD1G93A, age matched WT and SOD1G93AGrm5-/+ mice. SOD1G93A astrocytes displayed a higher cytoplasmic calcium concentration respect to WT cells and knocking down of mGluR5 reduced calcium level, both under basal and 3,5-DHPG-stimulated conditions. GFAP and S100β, two markers of astrogliosis, were increased in SOD1G93A astrocytes, whereas their overexpression was reduced in SOD1G93AGrm5-/+ cells. The same positive effect was obtained in the case of NLRP3, a marker strictly related to inflammation, which was upregulated in SOD1G93A astrocytes and less expressed in double mutant astrocytes. The partial ablation of mGluR5 also resulted in a lower cellular presence of misfolded SOD1. Both the expression and secretion of pro-inflammatory cytokines were strongly reduced in SOD1G93AGrm5-/+ respect to SOD1G93A astrocytes. The uncoupling between oxygen consumption and ATP synthesis and the impairment of mitochondria function, present in SOD1G93A astrocytes, were recovered in double mutant astrocytes. Notably, the viability of spinal MNs co-cultured with SOD1G93AGrm5-/+ astrocytes was significantly increased respect to MNs co-cultured with SOD1G93A astrocytes. The acute in-vitro treatment of SOD1G93A astrocytes with an antisense nucleotide (ASO) specific for mGluR5 decreased the mRNA and protein expression of mGluR5 in these cells and led to the reduction of GFAP and S100β. The in-vitro pharmacological treatment with the negative allosteric modulator of mGluR5, CTEP, also reduced the expression of GFAP and S100β in SOD1G93A astrocytes.
Altogether, these results indicate that mGluR5 ablation has a positive impact on astrocytes in SOD1G93A mice, supporting the idea that the in-vivo amelioration of the disease progression, registered after mGluR5 genetical or pharmacological silencing, involve astrocyte phenotype improvement. As a whole, it may be outlined that mGluR5 may represent a potential therapeutic target able to preserve MNs from death, also by modulating the reactive astroglia phenotype in ALS.
Due to the active contribution of microglia to ALS pathogenesis, the effect of mGluR5 partial ablation in SOD1G93A mice on the balance between the pro- and anti-inflammatory profile of microglia acutely purified from the brain and spinal cord of WT, Grm5-/+, SOD1G93A and SOD1G93AGrm5-/+ mice has been investigated at the early (90 days) and late symptomatic (120 days) stages of ALS by detecting the mRNA and protein levels of some relevant markers involved in neuroinflammation, such as IL-1β, CD86, iNOS, TNF-α (pro-inflammatory), Arginase 1, IL-10, CD206 and IL-4 (anti-inflammatory). Experiments are in progress to complete this part of the project
The Impact of the Exposome on Alzheimer’s Disease: The Influence of Nutrition
No full textAlzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline, memory loss, and behavioural changes. While genetic predispositions and pathological processes have been the traditional focus, this review highlights the fundamental role of environmental factors, particularly nutrition, within the exposome framework in modulating the risk and progression of AD. The exposome, which includes the totality of environmental exposures in an individual’s lifetime, provides a comprehensive approach to understanding the complex aetiology of AD. In this review, we explore the impact of dietary factors and cyclic nucleotide pathways (cAMP/cGMP) on AD, emphasizing the potential of dietary interventions as therapeutic strategies. We investigate key aspects of how nutrition affects the accumulation of β-amyloid, the aggregation of tau proteins, and neuroinflammation. We also examine the impact of specific nutrients on cognitive performance and the risk of AD. Additionally, we discuss the potential of nutraceuticals with anti-phosphodiesterase activity and the role of various animal models of AD (such as 5xFAD, 3xTg-AD, Tg2576, and APP/PS1 mice) in demonstrating the effects of dietary interventions on disease onset and progression
The Key Role of Astrocytes in Amyotrophic Lateral Sclerosis and Their Commitment to Glutamate Excitotoxicity
No full textIn the last two decades, there has been increasing evidence supporting non-neuronal cells as active contributors to neurodegenerative disorders. Among glial cells, astrocytes play a pivotal role in driving amyotrophic lateral sclerosis (ALS) progression, leading the scientific community to focus on the “astrocytic signature” in ALS. Here, we summarized the main pathological mechanisms characterizing astrocyte contribution to MN damage and ALS progression, such as neuroinflammation, mitochondrial dysfunction, oxidative stress, energy metabolism impairment, miRNAs and extracellular vesicles contribution, autophagy dysfunction, protein misfolding, and altered neurotrophic factor release. Since glutamate excitotoxicity is one of the most relevant ALS features, we focused on the specific contribution of ALS astrocytes in this aspect, highlighting the known or potential molecular mechanisms by which astrocytes participate in increasing the extracellular glutamate level in ALS and, conversely, undergo the toxic effect of the excessive glutamate. In this scenario, astrocytes can behave as “producers” and “targets” of the high extracellular glutamate levels, going through changes that can affect themselves and, in turn, the neuronal and non-neuronal surrounding cells, thus actively impacting the ALS course. Moreover, this review aims to point out knowledge gaps that deserve further investigation
The negative allosteric modulator CTEP ameliorates the reactive phenotype of iastrocytes from patients affected by Amyotrophic Lateral Sclerosis
No full textGenetic and pharmacological effects by blocking mGlu5 receptor in the SOD1G93A mouse model of amyotrophic lateral sclerosis
No full textNon-cell autonomous autophagy in amyotrophic lateral sclerosis: A new promising target?
No full text: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative non-cell-autonomous disease with no cure, thus research is intensely focused on identifying pharmacological targets. Several studies aimed to clarify the pathogenic mechanisms and involvement in various cell types. A crucial factor in ALS is autophagy, which plays a key role in degrading intracellular protein aggregates. The connection between ALS and autophagy is reinforced by the fact that several genes mutated in ALS are linked to fundamental aspects of autophagy. The blockage of the autophagic flux was observed in ALS motor neurons, where it occurs earlier than in glia. However, the inconsistent effects of autophagy modulators in preclinical and clinical studies indicate the need for a deeper understanding of the role of autophagy in other cell types, such as astrocytes, microglia, and oligodendrocytes. Astrocytes and microglia are significantly impacted by autophagy dysregulation, contributing to neurodegeneration in both mouse and human-derived models. Autophagy is overactivated early in the disease, even before symptoms appear. This overactivation is influenced by the timing and specific tissue involved. It can alter cells' immunophenotype, favouring proinflammatory responses and affecting the cellular environment and autophagy in the surrounding cells. In contrast, oligodendrocytes show mild autophagic alterations. Additionally, sex hormones may affect proper autophagy function and ALS progression. The lack of information on how sex influences autophagy in glia highlights the need for more nuanced investigation into this mechanism. Future research should focus on these aspects, paving the way for personalised pharmacological approaches that consider the roles of cell types, time of intervention, and sex
Tri-Phenyl-Phosphonium-Based Nano Vesicles: A New In Vitro Nanomolar-Active Weapon to Eradicate PLX-Resistant Melanoma Cells
No full textCutaneous metastatic melanoma (CMM) is the most aggressive form of skin cancer, with characteristics including a poor prognosis, chemotherapy-induced secondary tumorigenesis, and the emergence of drug resistance. Our recent study demonstrated that triphenyl phosphonium (TPP)-based nanovesicles (BPPB), which have amphiphilic properties, exert potent ROS-dependent anticancer effect against PLX4032 (PLX)-sensitive MeOV BRAFV600E and MeTRAV BRAFV600D mutant cell lines, evidencing more marked efficacy on MeOV cells. Here, taking advantage of this in vitro model, the antitumoral effect of BPPB was tested on PLX-resistant (PLX-R) MeOV BRAFV600E and MeTRAV BRAFV600D mutant cell lines to find a new potential strategy to fight melanoma therapy resistance. Specifically, we investigated both its effects on cell viability in dose- and time-dependent experiments and those on ROS generation. Our results show that BPPB exerted strong antiproliferative effects, regardless of their acquired resistance of cells to PLX, that correlated with ROS overproduction for 24 h treatments only. Moreover, in terms of cell viability, PLX-R MeTRAV cells demonstrated a remarkably higher tolerance to 24 h BPPB treatment than PLX-R MeOV. On the contrary, BPPB exposure for longer periods induced similar responses in both cell lines (IC50 = 87.8–106.5 nM on MeOV and 81.0–140.6 nM on MeTRAV). Notably, BPPB cytotoxicity on non-tumorigenic human keratinocytes (HaCaT) was low, thus establishing that BPPB is appreciably selective for CMM cells, allowing for selectivity index values (SIs) up to 11.58. Furthermore, the BPPB concentration causing 50% hemolysis (HC50) was found to be 16–173 and 4–192-fold higher than the IC50 calculated for PLX-R MeOV and MeTRAV cells, respectively. Correlation studies established that BPPB exerts cytotoxic effects on PLX-R MeOV and MeTRAV cells by a time-dependent mechanism, while a concentration-dependent mechanism was observed only at 24 h of exposure. Finally, a ROS-dependent mechanism can be assumed only in PLX-R MeTRAV cells in 72 h treatment
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