Welcome to the AD/PD™ 2021 Interactive Program
The congress will officially run on Central European Time (CET) - Barcelona Time
To convert the congress times to your local time Click Here
Icons Legend: ![]()
- Live Session | 
- On Demand Session | 
- On Demand with Live Q&A
The viewing of sessions, cannot be accessed from this conference calendar. All sessions are accessible via the Main Lobby.
FOLLOWING THE LIVE DISCUSSION, THE RECORDING WILL BE AVAILABLE IN THE ON-DEMAND SECTION OF THE AUDITORIUM.
PROTEIN KINASE C ETA IS ACTIVATED IN REACTIVE ASTROCYTES AND NEGATIVELY REGULATES INFLAMMATION IN AN ALZHEIMER’S DISEASE MOUSE MODEL
Abstract
Aims
Alzheimer's disease (AD) is the primary cause of age-related dementia which is characterized by synaptic loss, the accumulation of β-amyloid peptides, and neurofibrillary tangles, glial activation, and neuroinflammation. Even though Protein kinase C (PKC) was implicated in AD, its role in astrocyte activation was not elucidated. This research aimed to study the role of PKC-eta (PKCη), an astrocyte-specific stress-activated and anti-apoptotic kinase, in reactive astrocytes.
Methods
Using the 5XFAD mouse model of AD, the expression and activation of PKCη in intact brain tissue and primary astrocyte cultures were studied using immunofluorescence and immunoblot analysis. The function of PKCη was studied using a specific peptide inhibitor (ηPS) and the cytokine levels were profiled using ELISA.
Results
We demonstrate that PKCη staining is highly enriched in cortical astrocytes in a disease-dependent manner and in the vicinity of Ab plaques. Moreover, activation of PKCη, as indicated by its increased phosphorylation levels, is identified mainly in cortical astrocytes derived from adult 5XFAD mice and was associated with elevated levels of reactive astrocytic markers and upregulation of the pro-inflammatory cytokine interleukin 6 (IL-6) compared to littermate controls. Notably, inhibiting the kinase activity of PKCη, using a specific peptide inhibitor, markedly increased the levels of secreted IL-6 from primary astrocytes when subjected to inflammatory stimulation (e.g., TNFα, IL-1). Similar phenomenon of increased IL-6 secretion was also observed upon inhibition of either the mammalian target of rapamycin (mTOR) or the protein phosphatase 2A (PP2A).
Conclusions
Our findings suggest that PKCη functions as a regulator of neuroinflammation in AD.
NEUROTOXIC ASTROCYTES SECRETED GLYPICAN-4 DRIVES ALZHEIMER’S TAU PATHOLOGY
Abstract
Aims
Human APOE is expressed as three genetic variants: APOE2, APOE3, and APOE4. Among the three APOE isoforms, APOE4 is the most crucial genetic risk factor for late-onset Alzheimer’s disease (AD). Carrying a single APOE4 allele increases AD risk 2- to 4-fold and carrying two APOE4 alleles increases AD risk about 8- to 12-fold. However, the mechanism through which APOE4 induces AD risk remains unknown.
Methods
By using a primary neuronal culture from the human tauopathy mouse model P301S, we first investigated which APOE variant is crucial for tau protein phosphorylation. To determine the molecular pathway that underlies in APOE4-mediated tau pathology, we screened a list of astrocytes secreted proteins in primary neuronal culture, and found that Glypican-4 (GPC-4) robustly induced tau pathology. Using astrocytes culture, we studied how GPC-4 is regulated in activated A1 astrocytes. We then investigated the role of GPC-4 in APOE4 induced AD pathology in neuronal cultures and invivo tau mouse models.
Results
GPC-4 is highly expressed in APOE4 AD patients and regulated by microglial factors via NF-κB signaling pathway. The astrocyte-secreted GPC-4 induced both tau accumulation and spreading in vitro and in vivo. Further, GPC-4 is required for APOE4-mediated surface trafficking of low-density lipoprotein receptor-related protein 1 (LRP1) and tau propagation. GPC-4 activates unfolded protein response (UPR) pathway IRE1α, and pharmacological inhibition of IRE1α with KIRA6 blocks GPC-4 induced tau propagation.
Conclusions
Together, our data comprehensively demonstrate that the APOE4-induced AD risk is directly mediated by GPC-4, and that perturbing GPC-4 induced IRE1α pathway has therapeutic opportunities.
NEURONAL AND ASTROCYTIC EXTRACELLULAR VESICLE BIOMARKERS IN BLOOD REFLECT BRAIN PATHOLOGY IN MOUSE MODELS OF ALZHEIMER'S DISEASE
Abstract
Aims
Circulating neuronal extracellular vesicles (NEVs) of Alzheimer’s disease (AD) patients show high Tau and Amyloid-beta (Aβ) levels, whereas their astrocytic EVs (AEVs) contain high complement levels. We sought to examine the association between blood neural EV and brain tissue levels of AD pathogenic proteins in AD mouse models.
Methods
We immunocaptured NEVs and AEVs from plasma collected from fifteen wild type (WT), four 2xTg-AD, nine 5xFAD, and fifteen 3xTg-AD mice and assessed biomarker relationships with brain tissue levels.
Results
NEVs had higher total (tTau) and p181-Tau in 3xTg-AD compared to WT mice (tTau, P=0.001; p181-Tau, P=0.002). For all groups of mice (Fig. 1a-b), NEV levels of tTau correlated significantly with those in cerebral cortex (r=0.7, p<0.0001) and hippocampus (r=0.5, P=0.0005) and NEV levels of p181-Tau with those in cerebral cortex (r=0.6, P<0.0001) and hippocampus (r=0.7, P<0.0001). NEVs from 5xFAD compared to other mice had higher Abeta42 (P<0.005). NEV Abeta42 had strong correlations with Abeta42 in cortex (r=0.6, P=0.001) and hippocampus (r=0.7, P<0.0001; Fig. 1c). AEV C1q was elevated in 3xTg-AD compared to WT mice (P=0.005); AEV C1q had strong correlations with C1q in cortex (r=0.9, P<0.0001) and hippocampus (r=0.7, P<0.0001; Fig. 1d).
Conclusions
Biomarkers in blood NEVs and AEVs reflect their brain levels across multiple AD mouse models supporting their potential use as “liquid biopsy” for AD.
AN OXIDATIVE METABOLISM IS REQUIRED FOR MICROGLIAL ACTIVATION IN ALZHEIMER’S DISEASE
Abstract
Aims
Microglial contribution to Alzheimer’s Disease (AD) is far from being elucidated. Whereas a chronic microglial activation has been described in mouse models, dysfunctional microglial have also been reported in human samples, where there are other comorbidities. We aim to study microglial phenotype and metabolism to stablish their role in AD
Methods
Active microglia from aged WT, APP751SL/+ and MAPTp.P301S/+ (TAU) were sorted and microarray studies were performed. Electron microscopy was performed to evaluate mitochondria elongation. To measure mitochondrial respiration, SeahorseXF experiments were performed in primary microglia cells. For systemic hypoxia, APP/PS1 and TAU mice were exposed to 9% O2 for 21 days. Human samples were used for immunohistochemistry and biochemical characterization.
Results
Active microglia from aged AD mouse models showed an inflammatory and neurodegenerative-related phenotype. A TREM2-dependent upregulation of the oxidative metabolism was also observed, accompanied by an activation of the mTOR pathway, an increase in mitochondrial complexes biogenesis and a mitochondrial elongation. Paradoxically, activation of HIF1a, an antagonistic pathway of the OXPHOS, was also observed in Abeta plaque-associated microglia (AbAM). Under systemic hypoxia, a reduction in microgliosis was observed in TAU and APP mice, leading to a reduction of AbAM. In AD human brain, we observed an accumulation of HIF1a and the presence of nude plaques accompanied by dystrophic neurites in a hypoxia-prone brain area.
Conclusions
Microglia chronic activation requires an aerobic metabolism in AD models and human samples. Modifiable factors, such as oxygen availability, cause microglial dysfunction by disrupting their mitochondrial metabolism.
EFFECT OF APOE ALLELES ON THE GLIAL TRANSCRIPTOME IN NORMAL AGING AND ALZHEIMER’S DISEASE
Abstract
Aims
Recently, APOEε4 has been implicated in aging and other neurodegenerative diseases suggesting broader Aβ-independent mechanisms, among them glial responses. To understand these mechanisms, we aimed to investigate the differental effect of APOE alleles on the microglia and astrocyte transcriptome in the absence and presence of neuritic plaques (NPs).
Methods
We analyzed bulk brain RNA-seq data from two large brain-banks to evaluate expression of microglia- and astrocyte-predominant genes across APOE alleles. Follow on experiments in APOE knock-in mice were used to test the observation that APOE genotype is closely associated with selected inflammatory responses.
Results
In control subjects with no NPs, we identified a cluster of microglia-predominant genes that are up-regulated in APOEε4 carriers and down-regulated in APOEε2 carriers, relative to APOEε3 homozygotes. This microglia-APOE cluster is enriched in phagocytosis —including TREM2 and TYROBP— and pro-inflammatory genes. Many of these genes were also up-regulated in APOEε4 carriers versus APOEε3 homozygotes across CERAD stages independently of pathology, further confirming that this is a genotype effect, not just pathology-driven. Conversely, APOE-linked changes in astrocyte-predominant genes were modest and involved lipid metabolism and extracellular matrix. The APOE allele association was validated in APOE knock-in mice upon a lipopolysaccharide challenge, but not at baseline.
Conclusions
APOEε4 and APOEε2 have opposite effects on the microglial transcriptome in the human brain, independent of their known effects on Aβ plaques. APOE knock-in mice may recapitulate human APOE-linked glial gene expression patterns only upon microglia stimulation. Our study supports the relevance of the APOE-TREM2-TYROBP axis in microglial responses in normal aging.
MODULATION OF NEUROINFLAMMATION BY CANNABIGEROL
Abstract
Aims
Glial inflammation is associated with the pathology of neuroinflammatory diseases like Alzheimer's disease (AD). Microglia and astrocytes become activated and release neurotoxic factors that eventually lead to neuronal damage. The cannabis plant produces different cannabinoids and cannabigerol serves as the precursor molecule for the most abundant phytocannabinoids. Increasing evidence suggests that cannabigerol (CBG) may contribute to glial inflammation associated with neurodegenerative diseases Aim: In this study we examined the effect of CBG in regulation of glial inflammation in vivo and in vitro.
Methods
BV2 microglial cells were used. nitric oxide (NO) and cytokines were measured by griess reaction and ELISA respectively. In vivo model of Neuroinflammation was used.
Results
Exposure of lipopolysaccharide (LPS)-induced BV2 microglia to CBG dose dependently attenuated glial NO and tumor necrosis factor-a (TNF- alpha) synthesis by 66% and 30% respectively. 24 h treatment of BV2 cells with LPS resulted in robust increase in inducible nitric oxide synthase (iNOS ) levels. Cannabigerol, significantly reduced LPS-induced iNOS expression. Rimonabant (CB1 receptor antagonist) but not AM630 (CB2 receptor antagonist) blocked the inhibitory effect of CBG on LPS-induced NO production by BV2 microglia. CBG compared to control reduced significantly clinical scores of Multiple Sclerosis mice model.
Conclusions
We provide evidence that treatment of microglia with cannabigerol may serve as an efficient option as it results in the attenuation of microglial inflammation and oxidative stress. This research was supported by the Ministry of Agriculture and Rural developement (2017-2020).
EXPERIMENTAL COLITIS PROMOTES SUSTAINED CD8 TCELL-DEPENDENT NEUROINFLAMMATION AND PARKINSONIAN NEUROPATHOLOGY IN MICE
Abstract
Aims
Genetic and epidemiological evidence implicate inflammatory bowel disease in Parkinson's disease risk. We sought to investigate similarities between IBD and PD using human blood and colonic biopsy samples and the direct effects of gut inflammation on dopaminergic neurodegeneration in mice.
Methods
We used biochemical and immunological approaches to interrogate IBD and PD patient blood and colonic biopsies and used a mouse model of experimental colitis to investigate the extent of dysfunction induced in dopaminergic neurons in the brain and the mechanisms involved.
Results
We found high levels of NFκB p65 in colonic biopsies and other inflammatory mediators and reduced levels of Regulator of G-Protein Signaling-10 (RGS10) – a GAP identified previously by our group as a negative regulator of NFκB in myeloid cells. To evaluate directly whether this inflammatory profile could impact and/or increase vulnerability of dopaminergic pathways, we employed a RGS10-null mouse model challenged with experimental colitis. In male mice, colitis caused sustained CD8+ T-cell infiltration and interferon gamma gene expression in the brain which perturbed dopaminergic markers causing significant dopamine depletion. In both sexes, colitis potentiated effects of sub-threshold doses of the dopaminergic neurotoxicant MPTP. RGS10 deficiency increased baseline intestinal inflammation, colitis severity, and dopaminergic neuropathology. Consistent with a direct role in mediating inflammation-induced death, peripheral CD8+ T-cell depletion prevented colitis-induced reductions in dopaminergic markers.
Conclusions
These novel findings elucidate mechanisms by which gastrointestinal inflammation confers neurological vulnerability to PD in a sex-specific manner and suggest potential new avenues for immunomodulatory therapeutic interventions to delay or prevent progression of PD pathology responsible for motor symptoms.
PARTICULATE MATTER EXPOSURE EXACERBATES Aβ PLAQUE DEPOSITION AND GLIOSIS IN APP/PS1 MICE
Abstract
Aims
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques, neuroinflammation, and neuronal death. There are several well-established genetic and environmental factors hypothesized to contribute to AD pathology and progression. One such factor is air pollution. However, the molecular mechanisms by which air pollution exacerbates AD are not well understood. This study was designed to explore the effects of particulate matter exposure on AD-related brain changes using the APP/PS1 transgenic model of the disease.
Methods
Male C57BL/6;C3H wild type and APP/PS1mice, were exposed to either filtered air (FA) or particulate matter sized under 2.5 μm (PM2.5) for 6 h/day, 5 days/week for 3 months, and brains were collected. Immunohistochemistry for Aβ, GFAP, Iba1, and CD68 was performed on fixed brain sections. Aβ ELISAs and cytokine arrays were performed on frozen hippocampal and cortical lysates, respectively.
Results
The Aβ plaque load was significantly increased in the hippocampus of PM2.5 exposed APP/PS1 mice compared to their respective FA controls. Additionally, in the PM2.5 exposed APP/PS1 group, increased astrocytosis and microgliosis were observed as indicated by elevated GFAP, Iba1, and CD68 immunoreactivities. The cytokines TNF-α, IL-6, IL-1β, IFN-γ, and MIP-3α were also elevated in the cortices of PM2.5 exposed APP/PS1 mice compared to FA controls.
Conclusions
Our data suggest that chronic particulate matter exposure exacerbates AD by increasing Aβ plaque load, gliosis, and brain inflammatory status.