Amyloid-beta Peptide Levels Research Articles

Circulating levels of amyloid-beta (1-40) peptide associate with cardiometabolic traits and risk for metabolic dysfunction-associated steatotic liver disease

Abstract Background and Aims The ageing-associated amyloid-beta 1-40 peptide (Αbeta40) has recently emerged as a blood-based biomarker of cardiovascular disease (CVD). Its levels predict future cardiovascular death and MACE in patients with established CVD. The clinical value of Abeta40 in patients with metabolic syndrome who do not concomitantly have clinically overt CVD or other end-organ damage remains poorly understood. At the present study we investigated the clinical value of plasma Αbeta40 in patients with pre- or established metabolic syndrome who are at risk for metabolic dysfunction-associated steatotic liver disease (MASLD). Methods Αbeta40 was measured in plasma by enzyme-linked immunosorbent assay and cardiometabolic traits were determined in a mixed population (n=888) of patients with established (n=243) and pre- or without metabolic syndrome (n=645) who did not have clinical signs of established cardiometabolic disease (heart failure, coronary artery disease, MASLD, chronic kidney disease). The endpoint of the study was the association of Abeta40 with cardiometabolic indices and risk (BARD score) for MASLD. Odds ratio (OR) was calculated by ordinal regression analysis for the increasing incidence of metabolic syndrome components per increasing Abeta40 (1-SD) after adjustment for age, sex, smoking status and hyperlipidemia. Results Abeta40 levels are associated with the presence of metabolic syndrome and with higher odds for increasing incidence of metabolic syndrome components after adjustment for sex, age, smoking status, hypertension and dyslipidemia. Increased Abeta40 plasma levels were associated with decreased HDL-C levels (OR: 1.004, 95% CI:1.000-1.009, P=0.049) and increased triglyceride levels (OR: 1.007, 95%CI: 1.001-1.012, P=0.033) after adjustment for traditional cardiovascular risk factors (age, sex, smoking status, hypertension and hyperlipidemia). Among the total population (n=888), we identified n=473 subjects with increased MASLD risk if any of the following was present: hepatic steatosis index≥36 or fatty liver index≥60 or Fib-4 index≥2.67 or NAFLD score≥0.675. Among patients with high-risk for MASLD, patients with increased BARD score had significantly higher Abeta40 levels (median Abeta40 concentration in patients with BARD score≥2 vs. patients with BARD score<2: 54.9 pg/ml (IQR=38.25) vs. 41.9 pg/m (IQR=30.35), P=0.012). Increased Abeta40 levels were associated with increased odds for AST/ALT≥0.8 ratio and increased odds for BARD score≥2 after adjustment for age, sex, smoking status, hypertension and hyperlipidemia. Conclusion Our findings suggest that Abeta40 peptide is associated with cardiometabolic traits and risk for MASLD. Whether Abeta40 may emerge as an early cardiometabolic prognostic biomarker, future longitudinal studies are warranted to determine the prognostic value of Abeta40 for the development of cardiometabolic diseases in patients with metabolic syndrome.

Mediating role of obstructive sleep apnea in altering slow-wave activity and elevating Alzheimer’s disease risk: Pilot study from a northern Taiwan cohort

ObjectivesObstructive sleep apnea is associated with alterations in slow-wave activity during sleep, potentially increasing the risk of Alzheimer’s disease. This study investigated the associations between obstructive sleep apnea manifestations such as respiratory events, hypoxia, arousal, slow-wave patterns, and neurochemical biomarker levels. MethodsIndividuals with suspected obstructive sleep apnea underwent polysomnography. Sleep disorder indices, oxygen metrics, and slow-wave activity data were obtained from the polysomnography, and blood samples were taken the following morning to determine the plasma levels of total tau (T-Tau) and amyloid beta-peptide 42 (Aβ42) by using an ultrasensitive immunomagnetic reduction assay. Subsequently, the participants were categorized into groups with low and high Alzheimer’s disease risk on the basis of their computed product Aβ42 × T-Tau. Intergroup differences and the associations and mediation effects between sleep-related parameters and neurochemical biomarkers were analyzed. ResultsForty-two participants were enrolled, with 21 assigned to each of the low- and high-risk groups. High-risk individuals had a higher apnea–hypopnea index, oxygen desaturation index (≥3%, ODI-3%), fraction of total sleep time with oxygen desaturation (SpO2-90% TST), and arousal index and greater peak-to-peak amplitude and slope in slow-wave activity, with a correspondingly shorter duration, than did low-risk individuals. Furthermore, indices such as the apnea–hypopnea index, ODI-3% and SpO2-90% TST were found to indirectly affect slow-wave activity, thereby raising the Aβ42 × T-Tau level. ConclusionsObstructive sleep apnea manifestations, such as respiratory events and hypoxia, may influence slow-wave sleep activity (functioning as intermediaries) and may be linked to elevated neurochemical biomarker levels. However, a longitudinal study is necessary to determine causal relationships among these factors. Statement of significanceThis research aims to bridge gaps in understanding how obstructive sleep apnea is associated with an elevated risk of Alzheimer’s disease, providing valuable knowledge for sleep and cognitive health.

Circulating levels of amyloid-beta (1-40) peptide associate with cardiometabolic traits and risk for metabolic dysfunction

Circulating levels of amyloid-beta (1-40) peptide associate with cardiometabolic traits and risk for metabolic dysfunction

Circulating levels of amyloid-beta (1-40) peptide associate with cardiometabolic traits and risk for metabolic dysfunction-associated steatotic liver disease

Abstract Funding Acknowledgements None. Background and Aims The ageing-associated amyloid-beta 1-40 peptide (Αbeta40) has recently emerged as a blood-based biomarker of cardiovascular disease (CVD). Its levels predict future cardiovascular death and major adverse cardiovascular events in patients with established CVD. The value of Abeta40 in patients with metabolic syndrome who do not concomitantly have clinically overt CVD or other end-organ damage remains poorly understood. At the present study we investigated the value of plasma Αbeta40 in patients with pre- or established metabolic syndrome who are at risk for metabolic dysfunction-associated steatotic liver disease (MASLD). Methods Αbeta40 was measured in plasma by enzyme-linked immunosorbent assay and cardiometabolic traits were determined in a mixed population (n=888) of patients with established (n=243) and pre- or without metabolic syndrome (n=645) who did not have clinical signs of established cardiometabolic disease. The endpoint of the study was the association of Abeta40 with cardiometabolic indices and risk (BARD score) for MASLD. Odds ratio (OR) was calculated by ordinal regression analysis for the increasing incidence of metabolic syndrome components per increasing Abeta40 (1-SD) after adjustment for age, sex, smoking status and hyperlipidemia. Results Abeta40 levels are associated with the presence of metabolic syndrome and with higher odds for increasing incidence of metabolic syndrome components (prediabetes, low HDL-C levels, high triglyceride levels, increased waist circumference and high-risk for MASLD) after adjustment for sex, age, smoking status, hypertension and dyslipidemia. Increased Abeta40 plasma levels were associated with decreased HDL-C levels and increased triglyceride levels after adjustment for traditional cardiovascular risk factors (age, sex, smoking status, hypertension and hyperlipidemia). Among the total population (n=888), we identified n=473 subjects with increased MASLD risk if any of the following was present: hepatic steatosis index≥36 or fatty liver index≥60 or Fib-4 index≥2.67 or NAFLD score≥0.675. Among patients with high-risk for MASLD, patients with increased BARD score had significantly higher Abeta40 levels (median Abeta40 concentration in patients with BARD score≥2 vs. patients with BARD score<2: 54.9 pg/ml (IQR=38.25) vs. 41.9 pg/m (IQR=30.35), P=0.012). Increased Abeta40 levels were associated with increased odds for AST/ALT≥0.8 ratio (OR:1.017, 95% CI: 1.006-1.028, P=0.003) and increased odds for BARD score≥2 after adjustment for age, sex, smoking status, hypertension and hyperlipidemia. Conclusion Our findings suggest that Abeta40 peptide is associated with cardiometabolic traits and risk for MASLD. Whether Abeta40 may emerge as an early cardiometabolic prognostic biomarker, future longitudinal studies are warranted to determine the prognostic value of Abeta40 for the development of cardiometabolic diseases in patients with metabolic syndrome.

Neurodevelopmental disorders and microcephaly: how apoptosis, the cell cycle, tau and amyloid-β precursor protein APPly.

Recent studies promote new interest in the intersectionality between autism spectrum disorder (ASD) and Alzheimer's Disease. We have reported high levels of Amyloid-β Precursor Protein (APP) and secreted APP-alpha (sAPP) and low levels of amyloid-beta (Aβ) peptides 1-40 and 1-42 (Aβ40, Aβ42) in plasma and brain tissue from children with ASD. A higher incidence of microcephaly (head circumference less than the 3rd percentile) associates with ASD compared to head size in individuals with typical development. The role of Aβ peptides as contributors to acquired microcephaly in ASD is proposed. Aβ may lead to microcephaly via disruption of neurogenesis, elongation of the G1/S cell cycle, and arrested cell cycle promoting apoptosis. As the APP gene exists on Chromosome 21, excess Aβ peptides occur in Trisomy 21-T21 (Down's Syndrome). Microcephaly and some forms of ASD associate with T21, and therefore potential mechanisms underlying these associations will be examined in this review. Aβ peptides' role in other neurodevelopmental disorders that feature ASD and acquired microcephaly are reviewed, including dup 15q11.2-q13, Angelman and Rett syndrome.

A cost-effective aptasensor capable of early diagnosis and monitoring of Alzheimer's disease with the rapid analysis of beta-amyloid peptide 1–40

A cost-effective biosensor with guanine chemiluminescence detection capable of sensing trace levels of beta-amyloid peptide 1–40 was developed for the early diagnosis and accurate monitoring of Alzheimer's disease (AD).

Associations between risk of Alzheimer's disease and obstructive sleep apnea, intermittent hypoxia, and arousal responses: A pilot study.

Obstructive sleep apnea (OSA) may increase the risk of Alzheimer's disease (AD). However, potential associations among sleep-disordered breathing, hypoxia, and OSA-induced arousal responses should be investigated. This study determined differences in sleep parameters and investigated the relationship between such parameters and the risk of AD. Patients with suspected OSA were recruited and underwent in-lab polysomnography (PSG). Subsequently, blood samples were collected from participants. Patients' plasma levels of total tau (T-Tau) and amyloid beta-peptide 42 (Aβ42) were measured using an ultrasensitive immunomagnetic reduction assay. Next, the participants were categorized into low- and high-risk groups on the basis of the computed product (Aβ42 × T-Tau, the cutoff for AD risk). PSG parameters were analyzed and compared. We included 36 patients in this study, of whom 18 and 18 were assigned to the low- and high-risk groups, respectively. The average apnea-hypopnea index (AHI), apnea, hypopnea index [during rapid eye movement (REM) and non-REM (NREM) sleep], and oxygen desaturation index (≥3%, ODI-3%) values of the high-risk group were significantly higher than those of the low-risk group. Similarly, the mean arousal index and respiratory arousal index (R-ArI) of the high-risk group were significantly higher than those of the low-risk group. Sleep-disordered breathing indices, oxygen desaturation, and arousal responses were significantly associated with an increased risk of AD. Positive associations were observed among the AHI, ODI-3%, R-ArI, and computed product. Recurrent sleep-disordered breathing, intermittent hypoxia, and arousal responses, including those occurring during the NREM stage, were associated with AD risk. However, a longitudinal study should be conducted to investigate the causal relationships among these factors.

Antagonization of OX1 Receptor Potentiates CB2 Receptor Function in Microglia from APPSw/Ind Mice Model.

Microdialysis assays demonstrated a possible role of orexin in the regulation of amyloid beta peptide (Aß) levels in the hippocampal interstitial fluid in the APP transgenic model. CB2R is overexpressed in activated microglia, showing a neuroprotective effect. These two receptors may interact, forming CB2-OX1-Hets and becoming a new target to combat Alzheimer's disease. Aims: Demonstrate the potential role of CB2-OX1-Hets expression and function in microglia from animal models of Alzheimer's disease. Receptor heteromer expression was detected by immunocytochemistry, bioluminescence resonance energy transfer (BRET) and proximity ligation assay (PLA) in transfected HEK-293T cells and microglia primary cultures. Quantitation of signal transduction events in a heterologous system and in microglia cells was performed using the AlphaScreen® SureFire® kit, western blot, the GCaMP6 calcium sensor and the Lance Ultra cAMP kit (PerkinElmer). The formation of CB2-OX1 receptor complexes in transfected HEK-293T cells has been demonstrated. The tetrameric complex is constituted by one CB2R homodimer, one OX1R homodimer and two G proteins, a Gi and a Gq. The use of TAT interfering peptides showed that the CB2-OX1 receptor complex interface is TM4-TM5. At the functional level it has been observed that the OX1R antagonist, SB334867, potentiates the action induced by CB2R agonist JWH133. This effect is observed in transfected HEK-293T cells and microglia, and it is stronger in the Alzheimer's disease (AD) animal model APPSw/Ind where the expression of the complex assessed by the proximity ligation assay indicates an increase in the number of complexes compared to resting microglia. The CB2-OX1 receptor complex is overexpressed in microglia from AD animal models where OX1R antagonists potentiate the neuroprotective actions of CB2R activation. Taken together, these results point to OX1R antagonists as drugs with therapeutic potential to combat AD. Data access statement: Raw data will be provided by the corresponding author upon reasonable requirement.

Blood circulating miR-28-5p and let-7d-5p associate with premature ageing in Down syndrome

Persons with Down syndrome (DS) undergo a premature ageing with early onset of age-related diseases. The main endpoint of this study was the identification of blood circulating microRNAs (c-miRs) signatures characterizing DS ageing process. A discovery phase based on array was performed in plasma samples obtained from 3 young (31 ± 2 years-old) and 3 elderly DS persons (66 ± 2 years-old). Then, a validation phase was carried out for relevant miRs by RT-qPCR in an enlarged cohort of 43 DS individuals (from 19 up to 68 years-old). A group of 30 non-trisomic subjects, as representative of physiological ageing, was compared. In particular miR-628–5p, miR-152–3p, miR-28–5p, and let-7d-5p showed a lower level in younger DS persons (age ≤ 50 years) respect to the age-matched controls. Among those, miR-28–5p and let-7d-5p were found significantly decreased in physiological ageing ( oldest group ), thus they emerged as possible biomarkers of premature ageing in DS. Moreover, measuring blood levels of beta amyloid peptides, Aβ-42 was assessed at the lowest levels in physiological ageing and correlated with miR-28–5p and let-7d-5p in DS, while Aβ-40 correlated with miR-628–5p in the same cohort. New perspectives in terms of biomarkers are discussed.

Effects of subchronic dietary exposure to the engineered nanomaterials SiO2 and CeO2 in C57BL/6J and 5xFAD Alzheimer model mice

BackgroundThere is an increasing concern about the neurotoxicity of engineered nanomaterials (NMs). To investigate the effects of subchronic oral exposures to SiO2 and CeO2 NMs on Alzheimer’s disease (AD)-like pathology, 5xFAD transgenic mice and their C57BL/6J littermates were fed ad libitum for 3 or 14 weeks with control food pellets, or pellets dosed with these respective NMs at 0.1% or 1% (w/w). Behaviour effects were evaluated by X-maze, string suspension, balance beam and open field tests. Brains were analysed for plaque load, beta-amyloid peptide levels, markers of oxidative stress and neuroinflammation.ResultsNo marked behavioural impairments were observed in the mice exposed to SiO2 or CeO2 and neither treatment resulted in accelerated plaque formation, increased oxidative stress or inflammation. In contrast, the 5xFAD mice exposed to 1% CeO2 for 14 weeks showed significantly lower hippocampal Aβ plaque load and improved locomotor activity compared to the corresponding controls.ConclusionsThe findings from the present study suggest that long-term oral exposure to SiO2 or CeO2 NMs has no neurotoxic and AD-promoting effects. The reduced plaque burden observed in the mice following dietary CeO2 exposure warrants further investigation to establish the underlying mechanism, given the easy applicability of this administration method.

MT5-MMP promotes neuroinflammation, neuronal excitability and A\u03b2 production in primary neuron/astrocyte cultures from the 5xFAD mouse model of Alzheimer\u2019s disease

BackgroundMembrane-type matrix metalloproteinase 5 (MT5-MMP) deficiency in the 5xFAD mouse model of Alzheimer's disease (AD) reduces brain neuroinflammation and amyloidosis, and prevents deficits in synaptic activity and cognition in prodromal stages of the disease. In addition, MT5-MMP deficiency prevents interleukin-1 beta (IL-1β)-mediated inflammation in the peripheral nervous system. In this context, we hypothesized that the MT5-MMP/IL-1β tandem could regulate nascent AD pathogenic events in developing neural cells shortly after the onset of transgene activation.MethodsTo test this hypothesis, we used 11–14 day in vitro primary cortical cultures from wild type, MT5-MMP−/−, 5xFAD and 5xFAD/MT5-MMP−/− mice, and evaluated the impact of MT5-MMP deficiency and IL-1β treatment for 24 h, by performing whole cell patch-clamp recordings, RT-qPCR, western blot, gel zymography, ELISA, immunocytochemistry and adeno-associated virus (AAV)-mediated transduction.Results5xFAD cells showed higher levels of MT5-MMP than wild type, concomitant with higher basal levels of inflammatory mediators. Moreover, MT5-MMP-deficient cultures had strong decrease of the inflammatory response to IL-1β, as well as decreased stability of recombinant IL-1β. The levels of amyloid beta peptide (Aβ) were similar in 5xFAD and wild-type cultures, and IL-1β treatment did not affect Aβ levels. Instead, the absence of MT5-MMP significantly reduced Aβ by more than 40% while sparing APP metabolism, suggesting altogether no functional crosstalk between IL-1β and APP/Aβ, as well as independent control of their levels by MT5-MMP. The lack of MT5-MMP strongly downregulated the AAV-induced neuronal accumulation of the C-terminal APP fragment, C99, and subsequently that of Aβ. Finally, MT5-MMP deficiency prevented basal hyperexcitability observed in 5xFAD neurons, but not hyperexcitability induced by IL-1β treatment.ConclusionsNeuroinflammation and hyperexcitability precede Aβ accumulation in developing neural cells with nascent expression of AD transgenes. MT5-MMP deletion is able to tune down basal neuronal inflammation and hyperexcitability, as well as APP/Aβ metabolism. In addition, MT5-MMP deficiency prevents IL-1β-mediated effects in brain cells, except hyperexcitability. Overall, this work reinforces the idea that MT5-MMP is at the crossroads of pathogenic AD pathways that are already incipiently activated in developing neural cells, and that targeting MT5-MMP opens interesting therapeutic prospects.

Developing human cellular models to understand biological mechanisms linked to AD genetic risk

Mechanisms underlying late-onset sporadic Alzheimer's disease are genetically and biologically diverse. There is an outstanding need to identify modifiable cellular pathways associated with loci that increase AD risk. Furthermore, these pathways likely function differently in the diverse cell types of the CNS. Human induced pluripotent stem cells (hiPSCs) are an attractive model to address these challenges. hiPSCs can be differentiated to multiple cell types in two and three-dimensional formats. Using living human cells, novel cellular phenotypes can be uncovered and employed in therapeutic screens.We have applied this methodology to understand the role of the AD risk gene, SORL1 in endo-lysosomal trafficking in human neurons and microglia. SORL1 is a well-established AD risk gene and functions as an endosomal sorting receptor, known for regulating APP processing. Our data suggests multiple roles for SORL1 in endolysosomal trafficking beyond regulating amyloid beta peptide levels in neurons. We generated hiPSC lines with SORL1 AD-associated variants as well as loss of SORL1 function.In neurons and microglia derived from hiPSCs, we document changes in endosome morphology, sequestration of neurotrophin and synaptic receptors in early and recycling endosomes, impairments in phagocytosis and mis-trafficking of substrates to lysosomes. We also demonstrate that treatment with small molecules that enhance endosomal trafficking are able to ameliorate some of these phenotypes.Collectively are data shows that distinct cellular phenotypes can be modeled by manipulation of an AD risk genes and that strategies enhancing endosomal trafficking should be considered as therapeutic targets for AD.

Association of tear fluid amyloid and tau levels with disease severity and neurodegeneration

There has been increasing interest in finding non-invasive biomarkers for neurodegenerative diseases such as Alzheimer’s disease (AD). This observational study investigated AD-specific biomarkers in tear fluid. Tear fluid was collected from a total of 65 subjects, including 23 patients with subjective cognitive decline (SCD), 22 patients with mild cognitive impairment (MCI), 11 dementia patients and 9 healthy controls (HC). Levels of amyloid-beta peptides (AB38, AB40, AB42), total-tau (t-tau) and phosphorylated-tau (p-tau) were determined using multiplex immunoassays. Levels of AB40 and t-tau were detectable in the vast majority (> 94%) of tear fluid samples. Cerebrospinal fluid (CSF) was available from a subset of patients. In this group, tear t-tau levels were significantly higher in people with dementia compared to SCD patients. Tear t-tau levels were elevated in patients with neurodegeneration (classified according to the A/T/N system) compared to patients without neurodegeneration. Negative correlations were found between CSF AB42 and CSF t-tau, and between CSF AB42 and tear t-tau. In summary, this study shows the potential of tau proteins in tear fluid to be associated with disease severity and neurodegeneration.

Impact of increased APP gene dose in Down syndrome and the Dp16 mouse model.

People with Down syndrome (DS) are predisposed to Alzheimer's disease (AD). The amyloid hypothesis informs studies of AD. InAD-DS, but not sporadic AD, increasedAPPcopy number is necessary, defining theAPPgene dose hypothesis. Whichamyloid precursor protein (APP)products contributeneeds to be determined. Brain levels of full-length protein (fl-hAPP), C-terminal fragments (hCTFs), and amyloid beta (Aβ) peptides were measured in DS, AD-DS, non-demented controls (ND), and sporadic AD cases. TheAPPgene-dose hypothesis was evaluated in the Dp16 model. DS and AD-DS differed from ND and AD for allAPPproducts. In AD-DS,Aβ42 and Aβ40 levels exceededAD.APPproducts were increased in the Dp16 model; increasedAPPgene dose was necessary for loss of vulnerable neurons, tau pathology, and activation of astrocytes and microglia. Increases inAPPproducts other than Aβ distinguished AD-DS from AD. Deciphering AD-DS pathogenesis necessitates deciphering whichAPPproducts contribute and how.

The Tragedy of Alzheimer's Disease: Towards Better Management via Resveratrol-Loaded Oral Bilosomes.

Alzheimer’s disease (AD) is a neurodegenerative disease where oxidative stress plays a major role as a key pathologic factor. The study aims to develop resveratrol (RES)-loaded bilosomes for oral use, aiming to enhance RES bioavailability. RES-loaded bilosomes were prepared using the thin-film hydration technique. The effect of different formulation variables viz. the number of extrusion cycles, drug concentration and the effect of pH of the medium and cholesterol addition on the physicochemical properties of the prepared bilosomes was investigated. Results revealed the successful entrapment of RES into bilosomes. An optimized formula was selected, showing the lowest particle size (189 ± 2.14), acceptable PDI (0.116) and entrapment efficiency (76.2 ± 1.36). In vivo studies on a streptozotocin-induced animal model of AD showed the preeminence of bilosomes over traditional drug suspension to enhance mice memory via Y-maze and Morris water maze tests. Moreover, mice treated with the optimized formula exhibited decreased COX2, IL-6, amyloid-beta peptide and Tau protein levels compared to the drug suspension. Immuno-histochemical analysis revealed a significant decrease of glial fibrillary acidic protein values and microglial cell count in mice treated with bilosomes. Finally, it could be advocated that RES-loaded bilosomes could be a promising drug delivery system to control AD.

Knock-Down of HDAC2 in Human Induced Pluripotent Stem Cell Derived Neurons Improves Neuronal Mitochondrial Dynamics, Neuronal Maturation and Reduces Amyloid Beta Peptides.

Histone deacetylase 2 (HDAC2) is a major HDAC protein in the adult brain and has been shown to regulate many neuronal genes. The aberrant expression of HDAC2 and subsequent dysregulation of neuronal gene expression is implicated in neurodegeneration and brain aging. Human induced pluripotent stem cell-derived neurons (hiPSC-Ns) are widely used models for studying neurodegenerative disease mechanisms, but the role of HDAC2 in hiPSC-N differentiation and maturation has not been explored. In this study, we show that levels of HDAC2 progressively decrease as hiPSCs are differentiated towards neurons. This suppression of HDAC2 inversely corresponds to an increase in neuron-specific isoforms of Endophilin-B1, a multifunctional protein involved in mitochondrial dynamics. Expression of neuron-specific isoforms of Endophilin-B1 is accompanied by concomitant expression of a neuron-specific alternative splicing factor, SRRM4. Manipulation of HDAC2 and Endophilin-B1 using lentiviral approaches shows that the knock-down of HDAC2 or the overexpression of a neuron-specific Endophilin-B1 isoform promotes mitochondrial elongation and protects against cytotoxic stress in hiPSC-Ns, while HDAC2 knock-down specifically influences genes regulating mitochondrial dynamics and synaptogenesis. Furthermore, HDAC2 knock-down promotes enhanced mitochondrial respiration and reduces levels of neurotoxic amyloid beta peptides. Collectively, our study demonstrates a role for HDAC2 in hiPSC-neuronal differentiation, highlights neuron-specific isoforms of Endophilin-B1 as a marker of differentiating hiPSC-Ns and demonstrates that HDAC2 regulates key neuronal and mitochondrial pathways in hiPSC-Ns.

Pre-symptomatic Caspase-1 inhibitor delays cognitive decline in a mouse model of Alzheimer disease and aging

Early therapeutic interventions are essential to prevent Alzheimer Disease (AD). The association of several inflammation-related genetic markers with AD and the early activation of pro-inflammatory pathways in AD suggest inflammation as a plausible therapeutic target. Inflammatory Caspase-1 has a significant impact on AD-like pathophysiology and Caspase-1 inhibitor, VX-765, reverses cognitive deficits in AD mouse models. Here, a one-month pre-symptomatic treatment of Swedish/Indiana mutant amyloid precursor protein (APPSw/Ind) J20 and wild-type mice with VX-765 delays both APPSw/Ind- and age-induced episodic and spatial memory deficits. VX-765 delays inflammation without considerably affecting soluble and aggregated amyloid beta peptide (Aβ) levels. Episodic memory scores correlate negatively with microglial activation. These results suggest that Caspase-1-mediated inflammation occurs early in the disease and raise hope that VX-765, a previously Food and Drug Administration-approved drug for human CNS clinical trials, may be a useful drug to prevent the onset of cognitive deficits and brain inflammation in AD.

Cerebrospinal fluid phospho-tau T217 outperforms T181 as a biomarker for the differential diagnosis of Alzheimer\u2019s disease and PET amyloid-positive patient identification

BackgroundCerebrospinal fluid biomarker profiles characterized by decreased amyloid-beta peptide levels and increased total and phosphorylated tau levels at threonine 181 (pT181) are currently used to discriminate between Alzheimer’s disease and other neurodegenerative diseases. However, these changes are not entirely specific to Alzheimer’s disease, and it is noteworthy that other phosphorylated isoforms of tau, possibly more specific for the disease process, have been described in the brain parenchyma of patients. The precise detection of these isoforms in biological fluids remains however a challenge.MethodsIn the present study, we used the latest quantitative mass spectrometry approach, which achieves a sensitive detection in cerebrospinal fluid biomarker of two phosphorylated tau isoforms, pT181 and pT217, and first analyzed a cohort of probable Alzheimer’s disease patients and patients with other neurological disorders, including tauopathies, and a set of cognitively normal controls. We then checked the validity of our results on a second cohort comprising cognitively normal individuals and patients with mild cognitive impairments and AD stratified in terms of their amyloid status based on PiB-PET imaging methods.ResultsIn the first cohort, pT217 but not pT181 differentiated between Alzheimer’s disease patients and those with other neurodegenerative diseases and control subjects much more specificity and sensitivity than pT181. T217 phosphorylation was increased by 6.0-fold in patients with Alzheimer’s disease whereas T181 phosphorylation was only increased by 1.3-fold, when compared with control subjects. These results were confirmed in the case of a second cohort, in which the pT217 cerebrospinal fluid levels marked out amyloid-positive patients with a sensitivity and a specificity of more than 90% (AUC 0.961; CI 0.874 to 0.995). The pT217 concentrations were also highly correlated with the PiB-PET values (correlation coefficient 0.72; P < 0.001).ConclusionsIncreased cerebrospinal fluid pT217 levels, more than those of pT181, are highly specific biomarkers for detecting both the preclinical and advanced forms of Alzheimer’s disease. This finding should greatly improve the diagnosis of Alzheimer’s disease, along with the correlations found to exist between pT217 levels and PiB-PET data. It also suggests that pT217 is a promising potential target for therapeutic applications and that a link exists between amyloid and tau pathology.

Profile of Pathogenic Proteins and MicroRNAs in Plasma-derived Extracellular Vesicles in Alzheimer’s Disease: A Pilot Study

Protein and miRNA enrichment within extracellular vesicles (EVs) isolated from patients with Alzheimer’s disease (AD) has been shown to have putative diagnostic value. However, whether a combination of both will be more advantageous is unknown. EVs were enriched from serum samples obtained from patients with sporadic AD (n = 13), mild cognitive impairment (MCI) (n = 10), vascular dementia (VaD) (n = 10), and healthy controls (HC) (n = 10). Expression of protein levels of beta-amyloid peptide (Aβ1–42), total tau, P-T181-tau, and P-S396-tau and 18 microRNAs (miRNAs) in the EVs was performed by ELISA and qRT-PCR, respectively. Results were validated in an independent cohort of 18 subjects each by qRT-PCR assays. EV protein expression of Aβ1–42, total-tau, P-T181-tau and P-S396-tau, were significantly different among AD, MCI and VaD. Hsa-miR-1306-5p, hsa-miR-342-3p, and hsa-15b-3p were all significantly downregulated in patients with AD compared to HC (P < 0.05), only hsa-miR-1306-5p expression was differentially expressed between AD, MCI, and VaD samples. Similarly, whereas all 14 miRNAs were significantly upregulated in patients with AD compared to HC, only hsa-miR-93-5p, hsa-miR-424-5p, and hsa-miR-3065-5p were differentially expressed when AD samples were compared to MCI and VaD samples. Even though the sample size was small, the results of the current pilot study indicates that hsa-miR-1306-5p, hsa-miR-93-5p, hsa-miR-424-5p, and hsa-miR-3065-5p, and expression of P-S396-tau in EVs might provide a combinatorial protein and miRNA signature to differentiate between HC, patients with MCI or VaD from patient with sporadic AD.

EphA4 loss improves social memory performance and alters dendritic spine morphology without changes in amyloid pathology in a mouse model of Alzheimer\u2019s disease

BackgroundEphA4 is a receptor of the ephrin system regulating spine morphology and plasticity in the brain. These processes are pivotal in the pathophysiology of Alzheimer’s disease (AD), characterized by synapse dysfunction and loss, and the progressive loss of memory and other cognitive functions. Reduced EphA4 signaling has been shown to rescue beta-amyloid-induced dendritic spine loss and long-term potentiation (LTP) deficits in cultured hippocampal slices and primary hippocampal cultures. In this study, we investigated whether EphA4 ablation might preserve synapse function and ameliorate cognitive performance in the APPPS1 transgenic mouse model of AD.MethodsA postnatal genetic ablation of EphA4 in the forebrain was established in the APPPS1 mouse model of AD, followed by a battery of cognitive tests at 9 months of age to investigate cognitive function upon EphA4 loss. A Golgi-Cox staining was used to explore alterations in dendritic spine density and morphology in the CA1 region of the hippocampus.ResultsUpon EphA4 loss in APPPS1 mice, we observed improved social memory in the preference for social novelty test without affecting other cognitive functions. Dendritic spine analysis revealed altered synapse morphology as characterized by increased dendritic spine length and head width. These modifications were independent of hippocampal plaque load and beta-amyloid peptide levels since these were similar in mice with normal versus reduced levels of EphA4.ConclusionLoss of EphA4 improved social memory in a mouse model of Alzheimer’s disease in association with alterations in spine morphology.