Mature iPSC-derived astrocytes of an ALS/FTD patient carrying the TDP43A90V mutation display a mild reactive state and release polyP toxic to motoneurons.

Astrocytes play a critical role in the maintenance of a healthy central nervous system and astrocyte dysfunction has been implicated in various neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). There is compelling evidence that mouse and human ALS and ALS/FTD astrocytes can reduce the number of healthy wild-type motoneurons (MNs) in co-cultures or after treatment with astrocyte conditioned media (ACM), independently of their genotype. A growing number of studies have shown that soluble toxic factor(s) in the ACM cause non-cell autonomous MN death, including our recent identification of inorganic polyphosphate (polyP) that is excessively released from mouse primary astrocytes (SOD1, TARDBP, and C9ORF72) and human induced pluripotent stem cells (iPSC)-derived astrocytes (TARDBP) to kill MNs. However, others have reported that astrocytes carrying mutant TDP43 do not produce detectable MN toxicity. This controversy is likely to arise from the findings that human iPSC-derived astrocytes exhibit a rather immature and/or reactive phenotype in a number of studies. Here, we have succeeded in generating a highly homogenous population of functional quiescent mature astrocytes from control subject iPSCs. Using identical conditions, we also generated mature astrocytes from an ALS/FTD patient carrying the TDP43A90V mutation. These mutant TDP43 patient-derived astrocytes exhibit key pathological hallmarks, including enhanced cytoplasmic TDP-43 and polyP levels. Additionally, mutant TDP43 astrocytes displayed a mild reactive signature and an aberrant function as they were unable to promote synaptogenesis of hippocampal neurons. The polyP-dependent neurotoxic nature of the TDP43A90V mutation was further confirmed as neutralization of polyP in ACM derived from mutant TDP43 astrocytes prevented MN death. Our results establish that human astrocytes carrying the TDP43A90V mutation exhibit a cell-autonomous pathological signature, hence providing an experimental model to decipher the molecular mechanisms underlying the generation of the neurotoxic phenotype.

Scaling the Andean Shilajit: A Novel Neuroprotective Agent for Alzheimer's Disease.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder without a cure, despite the enormous number of investigations and therapeutic approaches. AD is a consequence of microglial responses to "damage signals", such as aggregated tau oligomers, which trigger a neuro-inflammatory reaction, promoting the misfolding of cytoskeleton structure. Since AD is the most prevalent cause of dementia in the elderly (>60 years old), new treatments are essential to improve the well-being of affected subjects. The pharmaceutical industry has not developed new drugs with efficacy for controlling AD. In this context, major attention has been given to nutraceuticals and novel bioactive compounds, such as molecules from the Andean Shilajit (AnSh), obtained from the Andes of Chile. Primary cultures of rat hippocampal neurons and mouse neuroblastoma cells were evaluated to examine the functional and neuroprotective role of different AnSh fractions. Our findings show that AnSh fractions increase the number and length of neuronal processes at a differential dose. All fractions were viable in neurons. The AnSh fractions inhibit tau self-aggregation after 10 days of treatment. Finally, we identified two candidate molecules in M3 fractions assayed by UPLC/MS. Our research points to a novel AnSh-derived fraction that is helpful in AD. Intensive work toward elucidation of the molecular mechanisms is being carried out. AnSh is an alternative for AD treatment or as a coadjuvant for an effective treatment.

Uso de aspirina en prevención primaria cardiovascular: es tiempo de cambiar el paradigma / Aspirin use for primary cardiovascular prevention: time for a paradigm shift

La Aspirina es una droga ampliamente utilizada con un protagonismo indiscutido en el escenario de la prevención secundaria. Sin embargo, el rol de este medicamento en prevención primaria es aún motivo de discusión. Los primeros ensayos que evaluaron la Aspirina en prevención primaria sugerían reducciones en el infarto agudo al miocardio y el accidente cerebrovascular -aunque no en la mortalidad- con un riesgo no despreciable de hemorragia mayor. Esto llevó a diversas sociedades científicas a recomendar su prescripción sólo en aquellos individuos con alto riesgo de eventos cardiovasculares. Desde el año 2018 en adelante, surgen diversos ensayos aleatorizados que han cuestionado estas indicaciones, mostrando beneficios clínicos muy discretos o ausentes. El objetivo de esta revisión es realizar un análisis histórico de la evidencia sobre el rol de la Aspirina en prevención primaria y resumir las recomendaciones actuales en este escenario.

Aspirin is widely used with a clear role in secondary prevention of cardiovascular diseases. However, its benefit in primary prevention is still a matter of discussion. The first trials evaluating Aspirin for primary prevention suggested reductions in acute myocardial infarction and stroke (although not in mortality) but with a non-negligible risk of major bleeding. This led to aspirin being recommended by various scientific societies, albeit limited to individuals at high risk of cardiovascular events. Since 2018 various randomized trials in primary prevention showed minimal or no beneficial effects of aspirin thus questioning its indication for this purpose. The aim of this review is to make an historical analysis of the evidence for the role of Aspirin in primary prevention and suggest modified recommendations for these subjects.

Inflammation: A Major Target for Compounds to Control Alzheimer's Disease.

Several hypotheses have been postulated to explain how Alzheimer's disease is triggered, but none of them provide a unified view of its pathogenesis. The dominant hypothesis based on build-ups of the amyloid-ß peptide has been around for longer than three decades; however, up to today, numerous clinical trials based on the amyloid postulates have been attempted, but all of them have failed. Clearly, the revisited tau hypothesis provides a better explanation of the clinical observations of patients, but it needs to integrate the cumulative observations on the onset of this disease. In this context, the neuroimmuno modulation theory, based on the involvement of inflammatory events in the central nervous system, accounts for all these observations. In this review we intend to emphasize the idea that neuroinflammation is a main target for the search of new therapeutic strategies to control Alzheimer's disease. Beyond mono-targeting approaches using synthetic drugs that control only specific pathophysiological events, emerging therapeutics views based on multi targeting compounds appear to provide a new pathway for Alzheimer's disease treatment.

N-Acetyl Cysteine and Catechin-Derived Polyphenols: A Path Toward Multi-Target Compounds Against Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a multifactorial disease, that involves neuroinflammatory processes in which microglial cells respond to "damage signals". The latter includes oligomeric tau, iron, oxidative free radicals, and other molecules that promotes neuroinflammation in the brain, promoting neuronal death and cognitive impairment. Since AD is the first cause of dementia in the elderly, and its pharmacotherapy has limited efficacy, novel treatments are critical to improve the quality of life of AD patients. Multitarget therapy based on nutraceuticals has been proposed as a promising intervention based on evidence from clinical trials. Several studies have shown that epicatechin-derived polyphenols from tea improve cognitive performance; also, the polyphenol molecule N-acetylcysteine (NAC) promotes neuroprotection. OBJECTIVE: To develop an approach for a rational design of leading compounds against AD, based on specific semisynthetic epicatechin and catechin derivatives. METHODS: We evaluated tau aggregation in vitro and neuritogenesis by confocal microscopy in mouse neuroblastoma cells (N2a), after exposing cells to either epicatechin-pyrogallol (EPIC-PYR), catechin-pyrogallol (CAT-PYR), catechin-phloroglucinol (CAT-PhG), and NAC. RESULTS: We found that EPIC-PYR, CAT-PYR, and CAT-PhG inhibit human tau aggregation and significantly increase neuritogenesis in a dose-dependent manner. Interestingly, modification with a phloroglucinol group yielded the most potent molecule of those evaluated, suggesting that the phloroglucinol group may enhance neuroprotective activity of the catechin-derived compounds. Also, as observed with cathechins, NAC promotes neuritogenesis and inhibits tau self-aggregation, possibly through a different pathway. CONCLUSION: EPIC-PYR, CAT-PYR, CAT-PhG, and NAC increased the number of neurites in Na2 cell line and inhibits tau-self aggregation in vitro.

CDK5: A Unique CDK and Its Multiple Roles in the Nervous System.

The cyclin-dependent kinase 5 (CDK5) is known as an exceptional component of the CDK family, due to its characteristic regulatory pathways and its atypical roles in comparison to the classical cyclins. Despite its functional uniqueness, CDK5 shares a great part of its structural similarity with other members of the cyclin-dependent kinase family. After its discovery 26 years ago, a progressive set of cellular functions has been associated with this protein kinase, ranging from neuronal migration, axonal guidance, and synaptic plasticity in diverse stages of brain development, including specific and complex cognitive functions. More than 30 substrates for CDK5 have been found in different cellular pathways. Together with its essential physiological roles, a major discovery was the finding twenty years ago that CDK5 participates in neurodegenerative diseases responsible for tau hyperphosphorylations, and, as a consequence, it becomes a neurotoxic factor. This review focuses on the wide roles of CDK5 in the central nervous system, its implications in neurodegeneration, and provides an integrative insight of its involvement in pain modulation, Alzheimer's disease, and other contexts.

Alzheimer´s Disease in the Perspective of Neuroimmunology.

BACKGROUND: Alzheimer's Disease (AD) is a severe neurodegenerative disorder that includes the occurrence of behavioral disorders as well as memory and cognitive impairment as major symptoms. AD affects around 12% of the aged population in the world. Considerable research efforts have pointed to the role of innate immunity as the main culprit in the pathogenesis of AD. In this context, and according to with our neuroimmunomodulation theory, microglial activation modifies the cross-talks between microglia and neurons. We postulated that glial activation triggered by "damage signals" activates a pathological molecular cascade that finally leads to hyperphosphorylation and oligomerization of the tau protein. Interestingly, these modifications correlate with the gradual cognitive impairment of patients with the AD. Microglial activation is determined by the nature and strength of the stimulus. In the AD, a continuous activation state of microglia appears to generate neuronal injury and neurodegeneration, producing the outflow of pathological tau from the inner of neurons to the extraneuronal space. Released tau, together with the contribution of ApoE4 protein, would then produce reactivation of microglia, thus inducing a positive feedback that stimulates the vicious cycle in neurodegeneration. CONCLUSION: Nevertheless, from the pathophysiological perspective AD is significantly more than a loss of memory. In the initial stages of AD pathogenesis, variations in the dopaminergic pathway along with serotonin diminution play an important role. This may explain why depression is associated with the onset of AD. All these pathophysiological events take place together with immunomodulatory changes that trigger tau oligomerization in the course of neurofibrillary tangles formation. Interestingly, mood disorders appear to be followed by neuroinflammatory processes and structural/functional alterations that lead to cognitive impairment in the context of AD.

Behavioral and Neuropsychiatric Disorders in Alzheimer's Disease.

Alzheimer's disease (AD) is the most frequent type of dementia in the elderly, severely affecting functional and executive skills of subjects suffering from this disease. Moreover, the distress of caregivers as well as the social implications constitute a critical issue for families. Furthermore, cognitive impairment, along with behavioral disorders and neuropsychiatric symptoms are characteristics of AD. Although these are present with variations in prevalence, intensity, and progression, an important core of them is visible before cognitive impairment, especially depression and apathy, which affect at least 50% of patients. The most updated literature shows that depression and/or behavioral and neuropsychiatric symptoms (BNS) are part of the initial phase of the disease rather than just a risk factor. Thus, mood disorders are associated with anomalies in specific brain regions that disturb the normal balance of neurotransmission. This in turn is linked with an inflammatory pathway that leads to microglial activation and aggregated neurofibrillary tangle formation, finally triggering neuronal loss, according to our neuroimmunomodulation theory. Altogether, inflammation and tau aggregation are observed in preclinical stages, preceding the BNS of patients, which in turn are exhibited earlier than cognitive and functional impairment detected in AD. This review is focused on the latest insights of cellular and molecular processes associated with BNS in asymptomatic early-onset stages of AD. An important medical research focus is to improve quality of life of patients, through prevention and treatments of AD, and the study of behavioral disorders and early event in AD pathogenesis has a major impact.

Neuroimmune Tau Mechanisms: Their Role in the Progression of Neuronal Degeneration.

Progressive neurodegenerative pathologies in aged populations are an issue of major concern worldwide. The microtubule-associated protein tau is able to self-aggregate to form abnormal supramolecular structures that include small oligomers up to complex polymers. Tauopathies correspond to a group of diseases that share tau pathology as a common etiological agent. Since microglial cells play a preponderant role in innate immunity and are the main source of proinflammatory factors in the central nervous system (CNS), the alterations in the cross-talks between microglia and neuronal cells are the main focus of studies concerning the origins of tauopathies. According to evidence from a series of studies, these changes generate a feedback mechanism reactivating microglia and provoking constant cellular damage. Thus, the previously summarized mechanisms could explain the onset and progression of different tauopathies and their functional/behavioral effects, opening the window towards an understanding of the molecular basis of anomalous tau interactions. Despite clinical and pathological differences, increasing experimental evidence indicates an overlap between tauopathies and synucleinopathies, considering that neuroinflammatory events are involved and the existence of protein misfolding. Neurofibrillary tangles of pathological tau (NFT) and Lewy bodies appear to coexist in certain brain areas. Thus, the co-occurrence of synucleinopathies with tauopathies is evidenced by several investigations, in which NFT were found in the substantia nigra of patients with Parkinson's disease, suggesting that the pathologies share some common features at the level of neuroinflammatory events.

Reactive oxygen species trigger motoneuron death in non-cell-autonomous models of ALS through activation of c-Abl signaling.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which pathogenesis and death of motor neurons are triggered by non-cell-autonomous mechanisms. We showed earlier that exposing primary rat spinal cord cultures to conditioned media derived from primary mouse astrocyte conditioned media (ACM) that express human SOD1(G93A) (ACM-hSOD1(G93A)) quickly enhances Nav channel-mediated excitability and calcium influx, generates intracellular reactive oxygen species (ROS), and leads to death of motoneurons within days. Here we examined the role of mitochondrial structure and physiology and of the activation of c-Abl, a tyrosine kinase that induces apoptosis. We show that ACM-hSOD1(G93A), but not ACM-hSOD1(WT), increases c-Abl activity in motoneurons, interneurons and glial cells, starting at 60 min; the c-Abl inhibitor STI571 (imatinib) prevents this ACM-hSOD1(G93A)-mediated motoneuron death. Interestingly, similar results were obtained with ACM derived from astrocytes expressing SOD1(G86R) or TDP43(A315T). We further find that co-application of ACM-SOD1(G93A) with blockers of Nav channels (spermidine, mexiletine, or riluzole) or anti-oxidants (Trolox, esculetin, or tiron) effectively prevent c-Abl activation and motoneuron death. In addition, ACM-SOD1(G93A) induces alterations in the morphology of neuronal mitochondria that are related with their membrane depolarization. Finally, we find that blocking the opening of the mitochondrial permeability transition pore with cyclosporine A, or inhibiting mitochondrial calcium uptake with Ru360, reduces ROS production and c-Abl activation. Together, our data point to a sequence of events in which a toxic factor(s) released by ALS-expressing astrocytes rapidly induces hyper-excitability, which in turn increases calcium influx and affects mitochondrial structure and physiology. ROS production, mediated at least in part through mitochondrial alterations, trigger c-Abl signaling and lead to motoneuron death.

Astrocytes expressing mutant SOD1 and TDP43 trigger motoneuron death that is mediated via sodium channels and nitroxidative stress.

Amyotrophic lateral sclerosis (ALS) is a fatal paralytic disorder caused by dysfunction and degeneration of motor neurons. Multiple disease-causing mutations, including in the genes for SOD1 and TDP-43, have been identified in ALS. Astrocytes expressing mutant SOD1 are strongly implicated in the pathogenesis of ALS: we have shown that media conditioned by astrocytes carrying mutant SOD1(G93A) contains toxic factor(s) that kill motoneurons by activating voltage-sensitive sodium (Na v ) channels. In contrast, a recent study suggests that astrocytes expressing mutated TDP43 contribute to ALS pathology, but do so via cell-autonomous processes and lack non-cell-autonomous toxicity. Here we investigate whether astrocytes that express diverse ALS-causing mutations release toxic factor(s) that induce motoneuron death, and if so, whether they do so via a common pathogenic pathway. We exposed primary cultures of wild-type spinal cord cells to conditioned medium derived from astrocytes (ACM) that express SOD1 (ACM-SOD1(G93A) and ACM-SOD1(G86R)) or TDP43 (ACM-TDP43(A315T)) mutants; we show that such exposure rapidly (within 30-60 min) increases dichlorofluorescein (DCF) fluorescence (indicative of nitroxidative stress) and leads to extensive motoneuron-specific death within a few days. Co-application of the diverse ACMs with anti-oxidants Trolox or esculetin (but not with resveratrol) strongly improves motoneuron survival. We also find that co-incubation of the cultures in the ACMs with Na v channel blockers (including mexiletine, spermidine, or riluzole) prevents both intracellular nitroxidative stress and motoneuron death. Together, our data document that two completely unrelated ALS models lead to the death of motoneuron via non-cell-autonomous processes, and show that astrocytes expressing mutations in SOD1 and TDP43 trigger such cell death through a common pathogenic pathway that involves nitroxidative stress, induced at least in part by Na v channel activity.