Protein Aβ Research Articles

CRISPR-Cas9: A Promising Tool in Developing Alzheimer’s Disease Treatment

Alzheimer’s disease (AD) impacts millions of people worldwide, causing cognitive impairment that can get more and more severe as the patients age. Such a disease can also severely impact patients’ lives in the late stage. AD is a sporadic and familial disease. Beta-amyloid (Aβ) and hyperphosphorylated tau protein aggregates directly link to AD pathogenesis, leading to synaptic dysfunction and cognitive decline. When amyloid beta precursor protein (APP) has mutations on the genetic level, patients are likely to have familial AD. In addition, the presenilin (PSEN) gene is another target gene for AD research. Unfortunately, the existing therapies are still ineffective as they can only delay AD progression but cannot stop nor reverse it. Recently, CRISPR-Cas9 has emerged as a promising gene-editing tool in AD research. CRISPR-Cas9 is an outstanding tool compared with the first two generations of gene editing techniques, as CRISPR-Cas9 is cheaper and more efficient. It can create desired mutations in precise positions to target gene sequences, thus potentially manipulating the genes related to familial AD. By mitigating the overproduction of Aβ and tau protein aggregates, researchers aim to slow down or halt the disease progression. CRISPR-Cas9 has significant potential in constructing AD models, screening AD pathogenic genes, and developing targeted therapies for AD. Such a technique offers scientists a better understanding of AD pathogenesis and enlightens more efficient genetic therapies. This review systematically illustrates the CRISPR-Cas9 system and further explains its implementation in AD model constructions, pathogenic genes searching, and potential treatment for AD.

Research progress on the targets and therapies of Alzheimer’s disease

Alzheimer 's disease (AD) is a progressive neurodegenerative disease. Most of the patients have the following characteristics, such as abnormalities in memory, language, and behavioral ability. It is very common in dementia in the elderly. The pathological features are mainly the plaques formed by Aβ protein deposition and the neurofibrillary tangles. The causes of AD are complex, and there are many pathological hypotheses. The current clinical therapeutic drugs for AD are mainly cholinesterase inhibitors developed based on the cholinergic hypothesis and receptor antagonists targeting NMDA receptors. Although there are some research results on the targets based on other hypotheses, further research is needed for clinical application. Nevertheless, in recent years, there have been many new development directions, such as combination therapy. Multi-target combination therapy is expected to achieve better efficacy than traditional single-target therapy. This makes it even more important to develop drugs with different potential targets. This article introduces three current mainstream therapeutic targets and theories, and introduces the drugs based on them. At the same time, we also introduced 3 targets and therapies with good potential in the future, and introduced some current stage results and current drugs based on their research and development.

Next Generation Therapeutic Strategy for Treatment and Prevention of Alzheimer's Disease and Aging-Associated Cognitive Decline: Transient, Once-in-a-Lifetime-Only Depletion of Intraneuronal Aβ (iAβ) by Its Targeted Degradation via Augmentation of Intra-iAβ-Cleaving Activities of BACE1 and/or BACE2.

Although the long-standing Amyloid Cascade Hypothesis (ACH) has been largely discredited, its main attribute, the centrality of amyloid-beta (Aβ) in Alzheimer's disease (AD), remains the cornerstone of any potential interpretation of the disease: All known AD-causing mutations, without a single exception, affect, in one way or another, Aβ. The ACH2.0, a recently introduced theory of AD, preserves this attribute but otherwise differs fundamentally from the ACH. It posits that AD is a two-stage disorder where both stages are driven by intraneuronal (rather than extracellular) Aβ (iAβ) albeit of two distinctly different origins. The first asymptomatic stage is the decades-long accumulation of Aβ protein precursor (AβPP)-derived iAβ to the critical threshold. This triggers the activation of the self-sustaining AβPP-independent iAβ production pathway and the commencement of the second, symptomatic AD stage. Importantly, Aβ produced independently of AβPP is retained intraneuronally. It drives the AD pathology and perpetuates the operation of the pathway; continuous cycles of the iAβ-stimulated propagation of its own AβPP-independent production constitute an engine that drives AD, the AD Engine. It appears that the dynamics of AβPP-derived iAβ accumulation is the determining factor that either drives Aging-Associated Cognitive Decline (AACD) and triggers AD or confers the resistance to both. Within the ACH2.0 framework, the ACH-based drugs, designed to lower levels of extracellular Aβ, could be applicable in the prevention of AD and treatment of AACD because they reduce the rate of accumulation of AβPP-derived iAβ. The present study analyzes their utility and concludes that it is severely limited. Indeed, their short-term employment is ineffective, their long-term engagement is highly problematic, their implementation at the symptomatic stages of AD is futile, and their evaluation in conventional clinical trials for the prevention of AD is impractical at best, impossible at worst, and misleading in between. In contrast, the ACH2.0-guided Next Generation Therapeutic Strategy for the treatment and prevention of both AD and AACD, namely the depletion of iAβ via its transient, short-duration, targeted degradation by the novel ACH2.0-based drugs, has none of the shortcomings of the ACH-based drugs. It is potentially highly effective, easily evaluable in clinical trials, and opens up the possibility of once-in-a-lifetime-only therapeutic intervention for prevention and treatment of both conditions. It also identifies two plausible ACH2.0-based drugs: activators of physiologically occurring intra-iAβ-cleaving capabilities of BACE1 and/or BACE2.

Combination of Ternary Electrochemiluminescence System of BNQDs/AgMOG-K2S2O8 and Electrochemiluminescence Resonance Energy Transfer Strategy for Ultrasensitive Immunoassay of Amyloid-β Protein.

In this work, based on boron nitride quantum dots (BNQDs) as energy donors and MnO2@MWCNTs-COOH as energy receptors, we designed an efficient electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor for the detection of amyloid-β (Aβ42) protein, a biomarker of Alzheimer's disease (AD). First, the signal amplification of a ternary ECL system composed of BNQDs (as the ECL emitter), K2S2O8 (as the coreactant), and silver metal-organic gels (AgMOG, as the coreaction accelerator) was realized, and PDDA as stabilizer was added, a strong and stable initial ECL signal was obtained. AgMOG could not only support a large amount of BNQDs and Aβ42 capture antibody (Ab1) through Ag-N bond but also exhibit excellent ECL catalytic performance and enhance the luminescent intensity of BNQDs@PDDA-K2S2O8 system. In addition, due to the broad absorption spectrum of MnO2@MWCNTs-COOH and the extensive overlap with the ECL emission spectrum of BNQDs, the quenching probe Ab2-MnO2@MWCNTs-COOH could be introduced into the ternary system through a sandwich immune response. On this basis, the signal on-off ECL immunosensor was constructed to achieve the ultrasensitive detection of Aβ42 through signal transformation. Under the optimal conditions, the prepared ECL biosensor manifested a wide linear range (10 fg/mL-100 ng/mL) with a detection limit of 2.89 fg/mL and showed excellent stability, selectivity, and repeatability, which provided an effective strategy for the ultrasensitive detection of biomarkers in clinical analysis.

VEGF controls microglial phagocytic response to amyloid-β.

Microglial cells are well known to be implicated in the pathogenesis of Alzheimer's disease (AD), due to the impaired clearance of amyloid-β (Aβ) protein. In AD, Aβ accumulates in the brain parenchyma as soluble oligomers and protofibrils, and its aggregation process further give rise to amyloid plaques. Compelling evidence now indicate that Aβ oligomers (Aβo) are the most toxic forms responsible for neuronal and synaptic alterations. Recently, we showed that the Vascular Endothelial Growth Factor (VEGF) counteracts Aβo-induced synaptic alterations and that a peptide derived from VEGF is able to inhibit Aβ aggregation process. Moreover, VEGF has been reported to promote microglial chemotaxis to Aβ brain deposits. We therefore investigated whether VEGF could influence microglial phagocytic response to Aβ, using in vitro and ex vivo models of amyloid accumulation. We report here that VEGF increases Aβo phagocytosis by microglial cells and further characterized the molecular basis of the VEGF effect. VEGF is able to control α-secretase activity in microglial cells, resulting in the increased cleavage of the Triggering Receptor Expressed on Myeloid cells 2 (TREM2), a major microglial Aβ receptor. Consistently, the soluble form sTREM2 also increases Aβo phagocytosis by microglial cells. Taken together, these findings propose VEGF as a new regulator of Aβ clearance and suggest its potential role in rescuing compromised microglial function in AD.

Photostimulation of lymphatic clearance of β-amyloid from mouse brain: a new strategy for the therapy of Alzheimer’s disease

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder that poses a significant burden on socio-economic and healthcare systems worldwide. However, the currently available therapy of AD is limited, and new strategies are needed to enhance the clearance of β-amyloid (Aβ) protein and improve cognitive function. Photobiomodulation (PBM) is a non-invasive and effective therapeutic method that has shown promise in treating various brain diseases. Here, we demonstrate that 1267-nm PBM significantly alleviates cognitive decline in the 5xFAD mouse model of AD and is safe as it does not induce a significant increase in cortical temperature. Moreover, with the combination of 3D tissue optical clearing imaging and automatic brain region segmentation, we show that PBM-mediated reductions of Aβ plaques in different subregions of prefrontal cortex and the hippocampus are different. The PBM-induced lymphatic clearance of Aβ from the brain is associated with improvement of memory and cognitive functions in 5xFAD mice. Our results suggest that the modulation of meningeal lymphatic vessels (MLVs) should play an important role in promoting Aβ clearance. Collectively, this pilot study demonstrates that PBM can safely accelerate lymphatic clearance of Aβ from the brain of 5xFAD mice, promoting improvement of neurocognitive status of AD animals suggesting that PBM can be an effective and bedside therapy for AD.Graphical

Implementation of an ultra-sensitive microwell-based electrochemical sensor for the detection of Alzheimer’s disease

Alzheimer's Disease (AD) is one of the most common neurodegenerative disorders in elderly people. It is diagnosed by detecting amyloid beta (Aβ) protein in cerebrospinal fluid (CSF) obtained by lumbar puncture or through expensive positron emission tomography (PET) imaging. Although blood-based diagnosis of AD offers a less invasive and cost-effective alternative, the quantification of Aβ is technically challenging due to its low abundance in peripheral blood. To address this, we developed a compact yet highly sensitive microwell-based electrochemical sensor with a densely packed microelectrode array (20 by 20) for enhancing sensitivity. Employing microwells on the working and counter electrodes minimized the leakage current from the metallic conductors into the assay medium, refining the signal fidelity. We achieved a detection limit <10 fg/mL for Aβ by elevating the signal-to-noise ratio, thus capable of AD biomarker quantification. Moreover, the microwell structure maintained the performance irrespective of variations in bead number, indicative of the sensor's robustness. The sensor's efficacy was validated through the analysis of Aβ concentrations in plasma samples from 96 subjects, revealing a significant distinction between AD patients and healthy controls with an area under the receiver operating characteristic curve (AUC) of 0.85. Consequently, our novel microwell-based electrochemical biosensor represents a highly sensitive platform for detecting scant blood-based biomarkers, including Aβ, offering substantial potential for advancing AD diagnostics.

The Inhibition of Mitogen-Activated Protein Kinases (MAPKs) and NF-κB Underlies the Neuroprotective Capacity of a Cinnamon/Curcumin/Turmeric Spice Blend in Aβ-Exposed THP-1 Cells.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an increased level of β-amyloid (Aβ) protein deposition in the brain, yet the exact etiology remains elusive. Nowadays, treatments only target symptoms, thus the search for novel strategies is constantly stimulated, and looking to natural substances from the plant kingdom. The aim of this study was to investigate the neuroprotective effects of a spice blend composed of cinnamon bark and two different turmeric root extracts (CCSB) in Aβ-exposed THP-1 cells as a model of neuroinflammation. In abiotic assays, CCSB demonstrated an antioxidant capacity up to three times stronger than Trolox in the ORAC assay, and it reduced reactive oxygen species (ROS) induced by the amyloid fragment in THP-1 cells by up to 39.7%. Moreover, CCSB lowered the Aβ stimulated secretion of the pro-inflammatory cytokines IL-1β and IL-6 by up to 24.9% and 43.4%, respectively, along with their gene expression by up to 25.2% and 43.1%, respectively. The mechanism involved the mitogen-activated protein kinases ERK, JNK and p38, whose phosphorylation was reduced by up to 51.5%, 73.7%, and 58.2%, respectively. In addition, phosphorylation of p65, one of the five components forming NF-κB, was reduced by up to 86.1%. Our results suggest that CCSB can counteract the neuroinflammatory stimulus induced by Aβ-exposure in THP-1 cells, and therefore can be considered a potential candidate for AD management.

Network pharmacology analysis and experimental validation of Anemarrhenae Rhizoma in treating Alzheimer's disease.

To explore the mechanism of Anemarrhenae Rhizoma in treatment of Alzheimer's Disease (AD). The active ingredients and targets of Anemarrhenae Rhizoma for treatment of AD were screened with network pharmacology methods, the protein-protein interaction (PPI) network was constructed and the core targets were analyzed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriching analysis was performed. The peripheral blood lymphocytes were extracted and lymphoblastoid cell lines (LCL) were constructed and an in vitro cell model of LCL-SKNMC was established. MTT and CCK-8 methods were used to quantify SKNMC/LCL cells, 2 ´, 7 ´-dichlorodihydrofluorescein diacetate (DCFH-DA) probe was used to detect reactive oxygen species (ROS), and immunofluorescence staining was used to detect the generation of Aβ1-42 in a co-cultured model. Western blotting was used to detect protein expression in the co-culture model. The lifespan of N2 nematodes was observed under oxidative stress, normal state, and heat stress; ROS generated by N2 nematodes was detected by DCFH-DA probes. The paralysis time of CL4176 N2 nematodes was evaluated by paralysis assay, and Aβ deposition in the pharynx was detected by Thioflavin S staining. Through network pharmacology, 15 potential active ingredients and 103 drug-disease targets were identified. PPI analysis showed that the Anemarrhenae Rhizoma might play anti-AD roles through albumin, Akt1, tumor necrosis factor, epidermal growth factor receptor (EGFR), vascular endothelial growth factor A (VEGFA), mammalian target of rapamycin (mTOR), amyloid precursor protein (APP) and other related targets. KEGG analysis showed that the pharmacological effects of Anemarrhenae Rhizoma might involve the biological processes of Alzheimer's disease, endocrine resistance, insulin resistance; and neuroactive ligand-receptor interaction, phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway, calcium signaling pathway, AGE-RAGE signaling pathway in diabetes complications, neurotrophic factor signaling pathway and others. The in vitro cell experiments showed that Anemarrhenae Rhizoma was able to reduce the production of ROS and Aβ1-42 (both P<0.01), inhibit the expression of β-secretase 1 (BACE1), APP and Aβ1-42 proteins (all P<0.05), up-regulate the expression of p-PI3K/PI3K, p-AKT/AKT, p-GSK3β/GSK3β in SKNMC cells (all P<0.05). The in vivo studies further confirmed that Anemarrhenae Rhizoma prolonged the lifespan of C. elegans under stress and normal conditions, reduced the accumulation of ROS and the toxicity of Aβ deposition. Anemarrhenae Rhizoma may reduce the production of Aβ in AD and inhibit its induced oxidative stress, which may be achieved by regulating the PI3K/Akt/GSK-3β pathway.

Examining the microglial TSPO phenotype in Alzheimer’s disease

AbstractBackgroundNeuroinflammation is a key pathological feature of Alzheimer’s disease (AD), with microglia being the main inflammatory cell type in the CNS. In order to examine these cells in vivo, PET ligands targeting the microglial translocator protein (TSPO) have been developed. However, it remains unclear the specific target of these ligands, whether this is all microglia or a subset of cells. We aim to elucidate this by identifying the microglial phenotype most associated with TSPO in humans.MethodHuman post‐mortem sections of temporal lobe (TL) and cerebellum (Cb) from cases classified by Braak stage (0‐II, III‐IV, V‐VI; each n = 10) were immunostained for pan‐Aß, pTau, and microglial markers TSPO, Iba1 and HLA‐DR with protein load quantified. Double immunofluorescent staining was performed with TSPO and microglial markers HLA‐DR and CD68 with positive cells counted.ResultTL showed an increase in Aβ (P&lt;0.0001), pTau (P&lt;0.0001) and TSPO (P&lt;0.0001) protein load, but not Iba1 or HLA‐DR, with progressing Braak stage. Aβ (P = 0.0008) and Iba1 (P = 0.012) load increased in the Cb, but not pTau, TSPO or HLA‐DR. Of note, TSPO load in TL was associated with pTau. In both areas, no difference was found in number of HLA+ or CD68+ cells, though TL TSPO+ cell number increased significantly (P = 0.0347). There was no difference in the number of HLA‐DR+/TSPO+ or CD68+/TSPO+ cells with progressing Braak stage. However, significantly more CD68+/TSPO+ than HLA‐DR+/TSPO+ cells were detected in both the TL (P&lt;0.0001) and Cb (P = 0.009) regions.ConclusionThe results suggest that TSPO expression is related to late stage disease (pTau) and microglial phagocytosis (CD68), a function we have previously identified associated with the presence of dementia, cognitive decline and tau pathology. Further additional analysis with other microglial markers is currently ongoing.

Clinical Phenotypes of Alzheimer’s Disease: Pathological Correlates of Regional Cortical Volume

AbstractBackgroundRecent studies highlight distinct patterns of cortical atrophy in amnestic (typical) and non‐amnestic (atypical – behavioural, dysexecutive and visuospatial) clinical phenotypes of Alzheimer’s disease (AD). The current study aimed to assess regional phenotypic MRI patterns of cortical atrophy, and their association with Amyloid‐beta (Aβ), phosphorylated Tau (pTau), and axonal degeneration (NfL).MethodPostmortem In‐situ 3DT1 3T‐MRI data were collected for 28 AD (14 typical, 14 atypical) and 10 control brain donors. Images were segmented using QyScore® and regional volumes according to the AAL3 atlas were obtained. At subsequent autopsy, Eight brain regions from the right hemisphere were selected and immunostained for Aβ (4G8), pTau (AT8), and Neurofilament light (NfL), and quantified for area% load. Group comparisons and MRI volume‐pathology associations were analyzed using linear models with covariates age, gender, postmortem delay, and intracranial volume when applicable.ResultsWhen assessing regional cortical volumes, compared to controls, typical AD showed a more parietal‐temporal, while atypical AD showed a more a frontal‐temporal atrophy pattern (fig1).Typical and atypical phenotypes showed different pathological load across all selected regions in both Aβ and NFL (p = 0.032,p = 0.0007, respectively). Subsequent explorative assessment indicates a difference in regional pTau distribution between behavioural, dysexecutive and visuospatial subtypes, specifically in the occipital region (fig2).Addressing MRI‐pathology associations across all selected regions, we observed a positive association between cortical volume and Aβ in typical AD (β = 1.98,p = 0.026), while both pTau and NFL showed a negative association (β = ‐0.26,p = 0.004; β = ‐2.00,p = 0.001, respectively). In atypical AD, only NFL showed a significant negative association (β = ‐2.27,p&lt;0.001) with cortical volume. Regionally (fig3), only NfL associated with MRI volume; with the precuneus in both typical and atypical AD (β = ‐2.81,p = 0.044; β = ‐3.81,p = 0.011, respectively), and with posterior cingulate cortex volume in atypical AD (β = ‐3.24,p = 0.045).ConclusionThis study found varying atrophy patterns in AD phenotypes when compared to controls. Across all selected regions, typical AD showed volume‐pathology associations with Aβ, pTau and axonal damage, while atypical AD only showed associations with axonal damage, indicating a possible difference in volume‐pathology associations between phenotypes. Regionally, cortical volume was predominantly associated with axonal damage, rather than Aβ or pTau protein accumulation, in parietal regions.

A Novel Method for Detecting Protein Aggregates Using Plasmonic Sensing

AbstractBackgroundAmyloid‐beta (Aβ) protein aggregates have been implicated in the pathology of Alzheimer’s disease (AD). These aggregates are difficult to characterise due to their small size, requiring very sensitive techniques. Gold Nanoparticles (AuNPs) form plasmonic cavities when in close proximity to a gold surface. The cavity both enhances and scatters incident light, with a resonant wavelength strongly dependent on the size of the cavity. These plasmonic cavities were used to detect and size Aβ aggregates at ultra‐low concentration using darkfield spectroscopy.MethodsAuNPs were coated with the Aβ specific 6E10 capture antibody, incubated with a synthetic aggregate sample, and centrifuged to isolate the AuNPs. They were then placed on a gold surface, and darkfield scattering spectra were obtained. The peak scattering wavelengths for each AuNP were used to produce a histogram of gap sizes, and thus the size distribution of detected protein aggregates.ResultsSignificant differences were seen in resonant peak position between monomeric samples of Aβ and 24 hour aggregated samples. This allows for easy identification of protein monomer vs fibrillar aggregates. In the case of aggregates, some peaks in the darkfield scattering spectra also appeared strongly polarised, suggesting dimerisation of the AuNPs. This was not present for the case of monomeric sample.ConclusionsWith this novel technique it was possible to clearly distinguish between samples of Aβ monomer and aggregates. This approach can likely be expanded to find the range and proportion of aggregate sizes in serum samples to detect the onset of AD. The AuNP dimerisation when Aβ aggregates are present is also interesting, and may serve as further verification of the size or shape of these aggregates.

The Derivatives of Cromolyn Ameliorate the Abnormal Misfolding of Amyloid Proteins and Neuroinflammation in the Neural Cells.

The representative symptom of Alzheimer's Disease (AD) has mainly been mentioned to be misfolding of amyloid proteins, such as amyloid-beta (Aβ) and tau protein. In addition, the neurological pathology related to neuroinflammatory signaling has recently been raised as an important feature in AD. Currently, numerous drug candidates continue to be investigated to reduce symptoms of AD, including amyloid proteins misfolding and neuroinflammation. Our research aimed to identify the anti-AD effects of two chemical derivatives modified from cromoglicic acid, CNU 010 and CNU 011. CNU 010 and CNU 011 derived from cromoglicic acid were synthesized. The inhibitory effects of Aβ and tau were identified by thioflavin T assay. Moreover, western blots were conducted with derivates CNU 010 and CNU 011 to confirm the effects on inflammation. CNU 010 and CNU 011 significantly inhibited the aggregation of Aβ and tau proteins. Moreover, they reduced the expression levels of mitogen-activated protein (MAP) kinase and nuclear factor kappa-light-chain-enhancer of activated B cells (NF- κB) signaling proteins, which are representative early inflammatory signaling markers. Also, the inhibitory effects on the lipopolysaccharide (LPS)-induced cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) expression referring to late inflammation were confirmed. Our results showing multiple beneficial effects of cromolyn derivatives against abnormal aggregation of amyloid proteins and neuroinflammatory signaling provide evidence that CNU 010 and CNU 011 could be further developed as potential drug candidates for AD treatment.

Effects of enlarged perivascular space in Parkinson’s disease and related cognitive decline

AbstractBackgroundThe glymphatic system plays a key role in brain toxics clearance. Many studies demonstrated that disrupted glymphatic system is responsible for insufficient clearance of Aβ and tau protein in Alzheimer’s disease. Its contribution in Parkinson’s disease (PD) and related cognitive function decline has not been fully studied. Enlarged perivascular space (PVS) may be a sign of glymphatic function decline, hence leading to PD pathology and PD‐related cognitive function decline. Our objective was to study the PVS in PD and related cognitive function decline.MethodHigh‐resolution T1‐weighted and T2‐weighted MRI data were acquired from 60 PD patients and 58 age‐ and sex‐matched controls. The PVS from the centrum semiovale of the white matter (CS), striatum (ST) and midbrain (MB) of the basal ganglia were segmented using the enhanced images from T1‐ and T2‐weighted images. Total intracranial volumes (TIV) were obtained to account for individual head sizes. Montreal Assessment of Cognition (MoCA) was used to quantify cognitive function. MDS‐UPDRS III scores were obtained for motor function deficits. ANCOVA was used to compare PVS metrics between PD patients and controls adjusted for age, sex, and TIV. Multiple regression was used to corelate PVS metrics and MoCA in PD patients with age, sex, MDS‐UPDRS III score and TIV as covariates.ResultCompared to controls, PD patients had enlarged PVS in MB (p = 0.0028), but not in CS and ST. PVS metrics were strongly associated with age (p &lt; 0.0001 for CS, p &lt; 0.0001 for ST, and p = 0.0092 for MB), but only PVS in MB was associated sex (p = 0.0001). In PD patients, the MoCA was associated with the PVS in CS (p = 0.0132), MB (p = 0.0275) and total PVS (p = 0.0088) but only trending with PVS in ST (p = 0.0737). There is no association between MoCA and PVS metrics in controls.ConclusionOur findings suggested that PD patients have enlarged PVS in the midbrain, and their cognitive function is associated with enlarged PVS in both CS and MB. The enlarged PVS might be an etiological factor for PD pathology and related cognitive decline.

PSEN2 poison exon inclusion is common across brain regions in late‐onset Alzheimer’s disease

AbstractBackgroundPathogenic variants in APP, PSEN1 and PSEN2 can cause early‐onset familial Alzheimer’s disease (AD). The molecular events leading to AD in individuals with late‐onset sporadic AD are still unclear even though they share the same clinical and pathological features of AD.MethodUsing targeted PacBio long read isoform sequencing (Iso‐Seq), we recently reported the characterization of tens of thousands of complete PSEN1 and PSEN2 transcripts in the prefrontal cortex of individuals with sporadic AD, familial AD (carrying PSEN1 and PSEN2 pathogenic variants), and controls.ResultWe found several alternative splicing differences in PSEN2 that are significantly elevated in sporadic AD including inclusion of a human‐specific cryptic exon present in intron 9 of PSEN2 (termed exon 9B) present in 11.8% of full‐length reads in sporadic AD samples relative to 1.9% of controls (p = 0.002) and 3.4% of PSEN variant carriers (p = 0.005) as well as a 77bp intron retention product prior to exon 6. These PSEN2 splice products are predicted to generate a prematurely truncated PSEN2 protein and were confirmed in an independent RNA‐seq dataset of ∼80 AD cases and ∼80 controls from cerebellum tissue (Course et al., Brain 2022). To extend these findings we analyzed PSEN2 exon 9B isoform levels in parietal and temporal lobe tissue samples. We found exon 9B was significantly elevated in sporadic AD relative to controls in the parietal lobe (p = 0.02) as well as the temporal lobe (p = &lt;0.001). However, levels of exon 9B were independent of TDP‐43 pathology or MSUT2 protein levels, which is intriguing given their roles as RNA binding proteins implicated in AD. We are working to establish the consequence of exon 9B inclusion in APP processing, Aβ and PSEN2 protein products in addition to possible cell autonomous roles for PSEN2 splice variants in microglia by leveraging single cell sequencing data.ConclusionCollectively, our findings expand our understanding of PSEN2 splice variants in the development of late‐onset sporadic AD, which can point to novel therapeutic strategies for AD.

Epigenome‐wide association study of Aβ42/Aβ40 in a sample of U.S. middle‐aged twins

AbstractBackgroundDNA methylation may affect expression of genes that promote the accumulation of amyloid‐β (Aβ). Although prior studies suggest that DNA methylation correlates with Aβ in older adults (Levine et al. (2018). An epigenetic biomarker of aging for lifespan and healthspan. Aging, 10(4), 573.), Aβ begins to accumulate earlier than when clinical symptoms associated with Aβ are evident. The purpose of the current study is to present novel results on whether differentially methylated CpG sites (i.e., regions of DNA where methylation occurs) correlate with higher Aβ42/Aβ40 ratios across a sample of middle‐aged individuals.MethodData from 193 individual twins from the Louisville Twin Study were used in the current analysis. Genomic DNA was extracted from venipuncture blood samples, and bisulfite‐converted DNA samples were assessed with the Illumina Infinium EpicArray BeadChip. Quality control and analyses were performed in R using the minfi package, and gene ontology analyses were performed using the MissMethyl package. Aβ42/Aβ40 was estimated using a capture sandwich immunoassay methodology that measures AD biomarkers in whole‐blood plasma. Differential DNA methylation was estimated using multivariable linear regression with an empirical Bayes estimator.ResultEstimation of differential DNA methylation was adequate (λ = 1.38), although some Type I inflation of p‐values was observed among CpG sites with higher p‐values. Although no CpG sites reached genome‐wide statistical significance, the top four CpG sites suggested differential methylation ranging between 2.8–4.8% per unit increase in the ratio of Aβ42/Aβ40. The top gene sets associated with differential methylation were response to glucocorticoids, response to corticosteroids, and response to Aβ.ConclusionDespite no statistically significant CpG probes identified, likely due to the small sample size, the findings from the gene ontology analysis suggest that identification of epigenetic biomarkers may clarify the biological pathways through which the epigenome may regulate expression of Aβ proteins. As data collection is ongoing, we expect detected of genome‐wide significant probes with larger sample sizes.

Clinical Manifestations.

In the present study, we investigated differences in amyloid (Aβ) burden and personality traits in cognitively-select older adults compared to average-functioning older adults. Conscientiousness, in particular, has been linked to Alzheimer's Disease (AD) pathology, and we hypothesized that adults who were high in cognition would exhibit enhanced conscientiousness. Of additional interest was whether high functioning older adults in the Dallas Lifespan Brain Study would evidence reduced AD pathology. We tested 285 cognitively-normal participants (ages 55-90) and collected conscientiousness scores using the Revised NEO Personality Inventory (NEO-PI-R). Participants also underwent PET imaging with radiotracer AV-45, 18F-Florbetapir, a radiotracer that is used to measure Aβ protein in the brain. Mean cortical SUVR was computed across 8 cortical regions of interest, normalized to cerebellar gray matter. In addition, participants completed a cognitive battery, underwent an MRI scan, and completed self-reports for depression and fitness. We designated those participants scoring at or above the mean episodic memory of a middle-aged (ages 35-54) reference group, as "cognitively-select" (N = 69), and those scoring below the mean, as "cognitively-normal" (N = 216). Dependent variables of interest included global and regional amyloid (Aβ), cortical morphometry, depression, fitness, conscientiousness, and various cognitive measures. Cognitively select participants were younger (p = .043), more educated (p = .021), and had higher positive personality traits, including self-discipline (p = .01), openness to ideas (p = .013), and competence (p = .015), compared to cognitively-normal. Although the groups did not differ in global Aβ pathology load (p = .083), cognitively select exhibited less pathology in specific regions including lateral temporal areas (p = .049). Regression analysis controlling for sex, age, education, and MMSE, revealed a significant group by global Aβ interaction on fluid ability (p = .034), where greater Aβ load predicted lower scores in cognitively normal older adults only. These findings provide evidence that cognitively privileged adults show resistance to decline across many domains and demonstrate resilience to amyloid pathology. Discussion will focus on longitudinal change in amyloid accumulation, cortical thinning, and cognitive decline, as well as the concept of reserve.

P143: New therapies for Alzheimer’s dementia and its implications on healthcare system: are we ready?

Objective:The amyloid hypothesis suggests that errors in production, accumulation, or disposal of beta-amyloid are the primary causes of Alzheimer's disease (AD). Since this was hypothesized, there has been significant effort in developing treatments that prevent the build-up of amyloid beta (Aβ) plaques in the brain. A disease modifying therapy (DMT) changes the clinical progression of AD by interfering in its pathophysiological mechanisms.The aim of this article is to review the current literature regarding the role of new DMTs for Alzheimer’s dementia and assess the preparedness of health care systems to implement these treatment options.Methods:Review of the most recent literature regarding the role of new DMTs for Alzheimer’s dementia and the challenges faced by the health care system to implement these treatment options. The research was carried out through the PubMed and UptoDate databases, using the terms “amyloid hypothesis”, “Alzheimer”, “disease modifying treatments” and “dementia”.Results:Research has been focusing on developing monoclonal antibodies as potential DMTs that target Aβ. Aducanumab, a human antibody, or immunotherapy, is the only disease-modifying medication currently approved to treat AD. It targets the Aβ protein and helps to reduce amyloid plaques and is currently the only FDA approved medication to slow the progression of AD. Lecanemab, a humanized IgG1 monoclonal antibody, binds to Aβ soluble protofibrils with high affinity. Even though there is considerable optimism about its potential, lecanemab will probably be more useful to patients on early stages of the disease.Conclusion:DMTs administration obeys to certain needs such as a vacancy in Day Hospital for infusion and regular monitorization and for lumbar punction. It demands a complex network involving general practitioner, neurologist, psychiatrist, psychologist, and social services. It also involves a genetic study and complementary diagnosis exams such as PET (Positron emission tomography) scans and MRIs (Magnetic resonance imaging), which are expensive. There is an emerging need to develop enhanced and safer treatments.

Donepezil‐indolyl hybrids as multipotent cholinesterase/monoamine oxidase inhibitors for the potential treatment of Alzheimer’s disease

AbstractBackgroundNumerous laboratory and clinical studies have evidenced that MAO‐B inhibitors are a potential therapeutic approach for the treatment of AD. Thus, drugs used to inhibit activated MAO, including rasagiline, ladostigil and selegiline, may provide neuroprotection against AD by improving cognitive impairment, modulating the proteolytic cleavage of APP and decreasing levels of Aβ protein fragments that accumulate in the brain. Future clinical studies on MAO inhibitors for the treatment of AD may provide further insights into the mechanism of action of antioxidants as therapeutic agents for AD.MethodSeries of donepezil‐indolyl hybrids were prepared and characterized via highresolution mass spectrometry, 1H nuclear magnetic resonance and 13C nuclear magnetic resonance techniques. In vitro fluorometric assay (by Amplex® UltraRed reagent to detect hydrogen peroxide or peroxidase activity in biological samples or enzymes.) was used to investigate the activity of the synthesized compounds on both MAO‐A and MAO‐B isozymes as well as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by Ellman method with modifications.ResultThe biological evaluation of molecules 1‐30 showed that most of these compounds are potent, in the nanomolar range, and selective AChEI, with moderate and equipotent selectivity for MAO‐A and MAO‐B inhibition. In overall, compound 11, as a potent and selective dual AChEI, showing a moderate MAO inhibitory profile, can be considered as an attractive multipotent drug for further development on two key pharmacological targets playing key roles in the therapy of Alzheimer’s disease.ConclusionThe pharmacological profile of compound 11, as well as the fact that it is a readily available compound in a short synthetic sequence, in good chemical yields, prompts us to select it as a lead‐compound for further optimization in our current research programme targeted to the preparation of new molecules for the potential treatment of AD.

A Survey of Genetic Risk Factors for Alzheimer’s Disease

This paper surveys a number of discovered genetic risk factors for Alzheimer’s Disease (AD). AD is a neurodegenerative disease characterized by memory loss and cognitive decline. AD is distinguished by large depositions of amyloid-beta (Aβ) protein, known as plaques, in areas of the brain. No single gene has been identified to cause Alzheimer’s, but several risk factors have been identified. Genetic variants associated with the accumulation of Aβ that have been identified as genetic risk factors for AD include APOE-2, APOE-3, APOE-4, APP, PSEN 1, and PSEN 2. This paper discusses these risk factors, their prevalence, how their connection to AD was discovered, and their level of risk.