Evaluation of neuroinflammation as modulator of tau aggregation in response to repetitive mild traumatic brain injury

The pathological misfolding and aggregation of hyper-phosphorylated tau (ptau) protein in neurofibrillary tangles (NFTs) is the main hallmark of a group of neurodegenerative diseases called tauopathies. These include important disorders such as Alzheimer’s Disease (AD) and chronic traumatic encephalopathy (CTE). Mounting evidence supports that the aggregation and deposition of misfolded proteins is an early event in the development of AD and CTE. Several studies uphold traumatic brain injury (TBI) as an important risk factor for both disorders, since there is a relationship between TBI severity and frequency, and the vulnerability to develop dementia. Importantly, individuals affected by TBI show elevated levels of ptau in cerebrospinal fluid and NFTs in specific brain areas. Although previous studies on tau mice subjected to TBI show increased ptau burden, the mechanisms underlying this phenomenon have not been explored. Besides, previous research neither recapitulate the effects of repetitive mild TBI (rmTBI), reported to lead to long-lasting neurological consequences. Acute and chronic inflammation are intimately associated to TBI events, but its role on tau aggregation over time remains unknown. Here, we analyze the neuroinflammatory response, at both short- and long-term, in transgenic tau mice after rmTBI. Our data suggest that rmTBI triggers microglia and astroglia activation and that they may be involved in the increase observed on tau pathology in concussed mice. This could indicate that neuroinflammation could have an active role in the increased risk to develop tauopathies after brain concussion.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Late-life depression is able to accelerate learning and memory impairment in a mouse model of Alzheimer´s disease

Clinical studies suggest that depression could be considered an important risk factor for the future development of cognitive impairment and Alzheimer's disease (AD). In fact, there is a strong association between late-life depression and AD. The age of AD onset has been shown to be accelerated in patients with mild cognitive impairment (MCI) with a history of depression, and women appear to be particularly more vulnerable to this condition. In addition, individuals with MCI who present depressive symptoms have an elevated burden of amyloid-beta (Aβ), the main toxic protein associated with Alzheimer's pathology, and a higher risk of developing AD compared to non-depressed MCI patients. Although it has been described that some transgenic models of AD can develop signs similar to depression in advanced stages, the induction of Alzheimer's pathology due to a depressive process has not been studied under experimental conditions to emulate late-life depression as a risk factor for AD. The objective of this study is to determine, by inducing unpredictable mild chronic stress (CUMS) in tau transgenic P301S mice, whether depression is a cause, rather than a consequence, of AD development. The results of our study indicate that the induction of CUMS in transgenic animals induces phenotypic changes related to a depressive state. Behavioral and histological studies suggest that depression-like induction can worse AD pathology. The findings generated in this project could provide evidence of depression as a risk factor for AD

Preventive and Therapeutic Reduction of Amyloid Deposition and Behavioral Impairments in a Model of Alzheimer’s Disease by Whole Blood Exchange

Alzheimer\u27s disease (AD) is the major form of dementia in the elderly population. The main neuropathological changes in AD patients are neuronal death, synaptic alterations, brain inflammation, and the presence of cerebral protein aggregates in the form of amyloid plaques and neurofibrillary tangles. Compelling evidence suggests that the misfolding, aggregation, and cerebral deposition of amyloid-beta (Aβ) plays a central role in the disease. Thus, prevention and removal of misfolded protein aggregates is considered a promising strategy to treat AD. In the present study, we describe that the development of cerebral amyloid plaques in a transgenic mice model of AD (Tg2576) was significantly reduced by 40-80% through exchanging whole blood with normal blood from wild type mice having the same genetic background. Importantly, such reduction resulted in improvement in spatial memory performance in aged Tg2576 mice. The exact mechanism by which blood exchange reduces amyloid pathology and improves memory is presently unknown, but measurements of Aβ in plasma soon after blood exchange suggest that mobilization of Aβ from the brain to blood may be implicated. Our results suggest that a target for AD therapy may exist in the peripheral circulation, which could open a novel disease-modifying intervention for AD

18F-THK5351 PET imaging, neuropathology and clinical progression in a tau mouse model

Aims: Alzheimer’s disease (AD) and other associated dementias remain a consistent and unruly problem for the aging population and health. The neuropathology of AD is characterized by the extracellular deposition of beta-amyloid protein (Aβ) and the formation of intraneuronal neurofibrillary tangles (NFT) composed of hyperphosphorylated tau (ptau), along with neuroinflammation and neuronal loss that ultimately induces to noticeable cognitive impairments. Abnormal ptau leads to the formation of insoluble, beta-sheet rich amyloid aggregates in tauopathies such as AD. Positron emission tomography (PET) imaging is a promising avenue that may identify tau aggregates in vivo cross-sectionally and longitudinally in various dementia conditions. Methods: The goal of this study is to characterize the longitudinal assessment of the tau tracer 18F-THK5351 by in vivo tau PET imaging concomitantly to behavior and tau pathology by histology and biochemistry from 6 to 12 months of age in tau transgenic P301S mice, a mouse model of tauopathies. Results: Our results demonstrate an augmentation of overall gross brain tau pathology by in vivo PET imaging in P301S mice compared to age-matched wild-type (WT) animals accompanied by P301S-model associated pathological tau and phenotypic and behavioral deficits. Conclusions: This longitudinal study provides new insights on the relationship between imaging diagnostic tools, the in vivo neuropathological temporal pattern and the clinical signs observed in animal models of AD that could benefit early disease diagnosis.This work was partially funded by Department of Defense Peer Reviewed Alzheimer’s Research Program Convergence Science. Research Award grant AZ160106 and Alzheimer’s Association New Investigator Research Grant NIRG-394284 to IMG. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Xylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: Root respiration increases with clonal size

Xylem and soil CO2 fluxes in coppiced oak forests increase with clonal size suggesting larger expenditures of energy for root respiration. An imbalance between root demand and shoot production of carbohydrates may contribute to the degradation of abandoned coppices

Monitoring the Formation of Amyloid Oligomers Using Photoluminescence Anisotropy

The formation of oligomeric soluble aggregates is related to the toxicity of amyloid peptides and proteins. In this manuscript, we report the use of a ruthenium polypyridyl complex ([Ru(bpy)2(dpqp)]2+) to track the formation of amyloid oligomers at different times using photoluminescence anisotropy. This technique is sensitive to the rotational correlation time of the molecule under study, which is consequently related to the size of the molecule. [Ru(bpy)2(dpqp)]2+ presents anisotropy values of zero when free in solution (due to its rapid rotation and long lifetime) but larger values as the size and concentration of amyloid-β (Aβ) oligomers increase. Our assays show that Aβ forms oligomers immediately after the assay is started, reaching a steady state at ∼48 h. SDS–PAGE, DLS, and TEM were used to confirm and characterize the formation of oligomers. Our experiments show that the rate of formation for Aβ oligomers is temperature dependent, with faster rates as the temperature of the assay is increased. The probe was also effective in monitoring the formation of α-synuclein oligomers at different timesAAM thanks the Welch Foundation (Grant C-1743) and JM thanks AEI (SAF2017-89890-R), ERC (DYNAP-677786) and HFSP (RGY0066/2017) for financial supportS

Pranlukast Antagonizes CD49f and Reduces Sternness in Triple-Negative Breast Cancer Cells

Introduction: Cancer stem cells (CSCs) drive the initiation, maintenance, and therapy response of breast tumors. CD49f is expressed in breast CSCs and functions in the maintenance of stemness. Thus, blockade of CD49f is a potential therapeutic approach for targeting breast CSCs. In the present study, we aimed to repurpose drugs as CD49f antagonists. Materials and Methods: We performed consensus molecular docking using a subdomain of CD49f that is critical for heterodimerization and a collection of pharmochemicals clini-cally tested. Molecular dynamics simulations were employed to further characterize drug-target binding. Using MDA-MB-231 cells, we evaluated the effects of potential CD49f antagonists on 1) cell adhesion to laminin; 2) mammosphere formation; and 3) cell viability. We analyzed the effects of the drug with better CSC-selectivity on the activation of CD49f-downstream signaling by Western blot (WB) and co-immunoprecipitation. Expressions of the stem cell markers CD44 and SOX2 were analyzed by flow cytometry and WB, respectively. Transactivation of SOX2 promoter was evaluated by luciferase reporter assays. Changes in the number of CSCs were assessed by limiting-dilution xenotransplantation. Results: Pranlukast, a drug used to treat asthma, bound to CD49f in silico and inhibited the adhesion of CD49f+ MDA-MB-231 cells to laminin, indicating that it antagonizes CD49f-containing integrins. Molecular dynamics analysis showed that pranlukast binding induces con-formational changes in CD49f that affect its interaction with β1-integrin subunit and constrained the conformational dynamics of the heterodimer. Pranlukast decreased the clonogenicity of breast cancer cells on mammosphere formation assay but had no impact on the viability of bulk tumor cells. Brief exposure of MDA-MB-231 cells to pranlukast altered CD49f-dependent signaling, reducing focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K) activation. Further, pranlukast-treated cells showed decreased CD44 and SOX2 expression, SOX2 promoter transacti-vation, and in vivo tumorigenicity, supporting that this drug reduces the frequency of CSC. Conclusion: Our results support the function of pranlukast as a CD49f antagonist that reduces the CSC population in triple-negative breast cancer cells. The pharmacokinetics and toxicology of this drug have already been established, rendering a potential adjuvant therapy for breast cancer patients

Determinants of Progression and Regression of Subclinical Atherosclerosis Over 6 Years.

BACKGROUND Atherosclerosis is a systemic disease that frequently begins early in life. However, knowledge about the temporal disease dynamics (ie, progression or regression) of human subclinical atherosclerosis and their determinants is scarce. OBJECTIVES This study sought to investigate early subclinical atherosclerosis disease dynamics within a cohort of middle-aged, asymptomatic individuals by using multiterritorial 3-dimensional vascular ultrasound (3DVUS) imaging. METHODS A total of 3,471 participants from the PESA (Progression of Early Subclinical Atherosclerosis) cohort study (baseline age 40-55 years; 36% female) underwent 3 serial 3DVUS imaging assessments of peripheral arteries at 3-year intervals. Subclinical atherosclerosis was quantified as global plaque volume (mm3) (bilateral carotid and femoral plaque burden). Multivariable logistic regression models for progression and regression were developed using stepwise forward variable selection. RESULTS Baseline to 6-year subclinical atherosclerosis progression occurred in 32.7% of the cohort (17.5% presenting with incident disease and 15.2% progressing from prevalent disease at enrollment). Regression was observed in 8.0% of those patients with baseline disease. The effects of higher low-density lipoprotein cholesterol (LDL-C) and elevated systolic blood pressure (SBP) on 6-year subclinical atherosclerosis progression risk were more pronounced among participants in the youngest age stratum (Pinteraction = 0.04 and 0.02, respectively). CONCLUSIONS Over 6 years, subclinical atherosclerosis progressed in one-third of middle-age asymptomatic subjects. Atherosclerosis regression is possible in early stages of the disease. The impact of LDL-C and SBP on subclinical atherosclerosis progression was more pronounced in younger participants, a finding suggesting that the prevention of atherosclerosis and its progression could be enhanced by tighter risk factor control at younger ages, with a likely long-term impact on reducing the risk of clinical events. (Progression of Early Subclinical Atherosclerosis [PESA; also PESA-CNIC-Santander]; NCT01410318).S

Microtubule stabilization reduces amyloid pathology and improves synaptic/memory deficits in APP/PS1 mice

Aims: Cognitive decline in Alzheimer's disease (AD) is highly related to synaptic/neuronal loss. Tau hyperphosphorylation destabilizes microtubules leading to axonal transport failure and generation of dystrophic neurites, thus contributing to synaptic dysfunction. The effect of microtubule stabilization on amyloid-beta pathology has not been assessed in vivo yet. This study evaluated the effect of the microtubule-stabilizing agent, Epothilone D (EpoD) in the pathology of an amyloidogenic mouse model. Methods: APP751SL/PS1M146L mice (3-month-old) were treated weekly with intraperitoneal injections of EpoD (2 mg/kg) or vehicle for 3 months. For memory performance, animals were tested on the objectrecognition, Y-maze and Morris water maze. Hippocampal proteinopathies were quantified by image analysis after immunostaining. Somatostatin (SOM)-numerical density was calculated by stereology. APPswe-N2a cells were treated with EpoD 100nM for 12/24 hours. Protein levels were analysed by Western/dot-blot. Results: EpoD-treated mice improved their performance of cognitive tests, while hippocampal phospho-tau and Ab (especially oligomers) accumulation decreased, together with synaptic/neuritic pathology. Remarkably, EpoD exerted a neuroprotective effect on SOM-interneurons, a highly AD-vulnerable GABAergic subpopulation. Conclusions: EpoD improved microtubule dynamics and axonal transport in an AD-like context, reducing tau and Ab accumulation and promoting neuronal and cognitive protection, underlining the cross-talk between cytoskeleton pathology and proteinopathy. Therefore, microtubule-stabilizing drugs could be candidates for slowing AD at both tau and Ab pathologies.Supported by PI18/01557 (to AG) and PI18/01556 (to JV) grants from ISCiii of Spain, co-financed by FEDER funds (European Union), CIBERNED collaborative grant (to AG and JV), and by PPIT.UMA.B1.2017/26 grant (to RSV). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Amyloid-b seeding and propagation processes in a hAb-KI model of Alzheimer's disease

Recent evidence indicates that Aβ can misfold and aggregate into seeds that structurally corrupt native proteins, mimicking a prion-like process. Several studies using FAD animal models have demonstrated that intracerebral infusion of brain extracts from APP-transgenic mice or AD patients induce Aβ deposition and cerebral amyloid angiopathy. To carry out most of these Aβ-seeding studies, APP-transgenic animal have been used. Nevertheless, it remains to be elucidated whether Aβ deposition can be induced by Aβ-seeds in a sporadic AD model that does not overexpress APP and produces wild type human Aβ. We used an innovative model to better understand the amyloidogenic events that occur in sporadic AD. This hAβ-KI model, expresses wild-type human Aβ under the control of the endogenous mouse APP gene. Aβ-seeds from AD patients (stage C) from the AD Research Center (UCI) were administered into 7-8-month-old hAβ-KI and as positive controls 3xTg-AD mice were employed. We demonstrated that amyloid seeds can stimulate Aβ aggregations in 3xTg-AD and hAβ-KI models. We found that Aβ aggregates occur earlier in the 3xTg-AD vs hAβ-KI and that a longer term of treatment is necessary to accelerate diffusible Aβ pathology in the hAβ-KI mice. Thereferoe, this hAβ-KI model represents an important step towards the development of next-generation animal models that will provide better predictive outcomes for human patients. Grants support: UCI MIND Pilot project (DBV), Ministry of Science PID2019-108911RA-100 (DBV), U54 AG054349 (FML), Institute of Health Carlos III PI18/01557 (AG) co-financed by FEDER funds (European Union), NIH/NIA Grant P50 AG16573 (UCI-ADRC).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech