Erlotinib regulates short-term memory, tau/Aß pathology, and astrogliosis in mouse models of AD.

Introduction: Erlotinib is an epidermal growth factor receptor (EGFR) inhibitor that is approved by the FDA to treat non-small cell lung cancer (NSCLC). Several membrane receptors, including EGFR, interact with amyloid ß (Aß), raising the possibility that erlotinib could have therapeutic effects on Alzheimer's disease (AD). However, the effects of erlotinib on Aß/tau-related pathology and cognitive function in mouse models of AD and its mechanisms of action have not been examined in detail. Methods: To investigate the effects of erlotinib on cognitive function and AD pathology, 3 to 6-month-old PS19 mice and 3 to 3.5-month-old 5xFAD mice and WT mice were injected with vehicle (5% DMSO + 10% PEG + 20% Tween80 + 65% D.W.) or erlotinib (20 mg/kg, i.p.) daily for 14 or 21 days. Then, behavioral tests, Golgi staining, immunofluorescence staining, western blotting ELISA, and real-time PCR were conducted. Results and discussion: We found that erlotinib significantly enhanced short-term spatial memory and dendritic spine formation in 6-month-old P301S tau transgenic (PS19) mice. Importantly, erlotinib administration reduced tau phosphorylation at Ser202/Thr205 (AT8) and Thr231 (AT180) and further aggregation of tau into paired helical fragments (PHFs) and neurofibrillary tangles (NFTs) in 3-month-old and/or 6-month-old PS19 mice by suppressing the expression of the tau kinase DYRK1A. Moreover, erlotinib treatment decreased astrogliosis in 6-month-old PS19 mice and reduced proinflammatory responses in primary astrocytes (PACs) from PS19 mice. In 3- to 3.5-month-old 5xFAD mice, erlotinib treatment improved short-term spatial memory and hippocampal dendritic spine number and diminished Aß plaque deposition and tau hyperphosphorylation. Furthermore, erlotinib-treated 5xFAD mice exhibited significant downregulation of astrocyte activation, and treating PACs from 5xFAD mice with erlotinib markedly reduced cxcl10 (reactive astrocyte marker) and gbp2 (A1 astrocyte marker) mRNA levels and proinflammatory cytokine mRNA and protein levels. Taken together, our results suggest that erlotinib regulates tau/Aß-induced AD pathology, cognitive function, and Aß/tau-evoked astrogliosis and therefore could be a potent therapeutic drug for ameliorating AD symptoms.

Astragaloside IV confronts amyloid-beta-induced astrocyte senescence via hsp90aa1.

Cell senescence is intensively related to aging and neurodegenerative diseases. This study aimed to explore the effect and targets of Astragaloside IV against amyloid-beta-induced astrocyte senescence. Oligomerized amyloid-beta was prepared to culture with human astrocytes. The effects of Astragaloside IV were assessed based on SA-ß-gal staining analysis, senescence markers (p53, p16INK4, and p21WAF1), neurotrophic growth factor levels (qRT-PCR), and cell proliferation (CCK-8 kit). The targets for Astragaloside IV were predicted, and hsp90aa1 protein was verified using molecular docking. After hsp90aa1 overexpression, the effects of Astragaloside IV on amyloid-beta-induced astrocytes were assessed. Treatment of human amyloid-beta-induced astrocytes with Astragaloside IV can decrease the percentage of SA-ß-gal positive cells, downregulate the p53, p16INK4, and p21WAF1 levels, and increase the levels of neurotrophic growth factors (IGF-1 and NGF mRNA) and cell proliferation. Based on target prediction, hsp90aa1 was found to be a potential target of Astragaloside IV. Moreover, cellular experiments demonstrated that exogenously enhanced expression of hsp90aa1 overexpression suppressed the protective effect of Astragaloside IV on amyloid-beta-induced human astrocytes. The results presented here demonstrate that Astragaloside IV could confront amyloid-beta-induced astrocyte senescence via hsp90aa1, possibly opening new therapeutic avenues.

Nilotinib as a Prospective Treatment for Alzheimer's Disease: Effect on Proteins Involved in Neurodegeneration and Neuronal Homeostasis.

Nilotinib, a tyrosine kinase inhibitor that targets the Abelson tyrosine kinase (c-Abl) signaling pathway, is FDA-approved to treat chronic myeloid leukemia. Nilotinib has properties indicative of a possible utility in neuroprotection that have prompted exploration of repurposing the drug for the treatment of Alzheimer's disease (AD) and Parkinson's disease (PD). AD is a progressive age-related neurodegenerative disorder characterized by the deposition of extracellular amyloid-ß plaques and intracellular neurofibrillary tangles. It is incurable and affects approximately 50 million patients worldwide. Nilotinib reduces c-Abl phosphorylation, amyloid-ß levels, and dopaminergic neuron degeneration in preclinical AD models. This study explores the effects of nilotinib on amyloid processing and mitochondrial functioning in the SH-SY5Y human neuroblastoma cell line. SH-SY5Y cells were exposed to nilotinib (1, 5, and 10 µM). Real-time PCR and immunoblot analysis were performed to quantify the expression of genes pertaining to amyloid-ß processing and neuronal health. Nilotinib did not significantly change APP, BACE1, or ADAM10 mRNA levels. However, BACE1 protein was significantly increased at 1 µM, and ADAM10 was increased at 10 µM nilotinib without affecting APP protein expression. Further, nilotinib treatment did not affect the expression of genes associated with neuronal health and mitochondrial functioning. Taken together, our findings do not support the efficacy of nilotinib treatment for neuroprotection.

Proteomic insights into early-stage Alzheimer's disease: Identifying key neuronal proteins impacted by amyloid beta oligomers in an in vitro model.

Alzheimer's disease (AD) remains a pressing global health concern, necessitating comprehensive investigations into its underlying molecular mechanisms. While the late-stage pathophysiology of this disease is well understood, it is crucial to examine the role of amyloid beta oligomers (Aßo), which form in the brain during the early stages of disease development. These toxic oligomers could affect neuronal viability and generate oxidative stress in the brain. In this study, we exposed SHSY-5Y cells to Aßo. The increase in intracellular reactive oxygen species and apoptosis observed in Aßo-treated cells mimics the early stages of AD. Comprehensive proteomic profiling identified 2966 differentially expressed proteins, with 123 significantly modulated. Utilizing the NeuroPro database, we identified 80 confirmed AD-related proteins and 43 novel candidates. Seven AD-related proteins with a NeuroPro score ≥ 5 were shortlisted. Furthermore, these proteins are found to be associated with Aß plaques in AD brains. VGF, LTF, PARP1, and MAOA have been implicated in various mechanisms underlying AD, including synaptic plasticity, iron homeostasis, DNA repair, and neurotransmitter degradation. Our study also revealed the involvement of less-explored proteins like MYH9, CISD1, and SNRNP70, which play critical roles in cytoskeletal dynamics, mitochondrial function, and RNA splicing, respectively. These findings underscore the complex pathophysiology of AD, highlighting potential biomarkers and therapeutic targets for early intervention. The present study advances the understanding of Aßo-induced oxidative stress and neuronal damage, providing a foundation for future research into early-stage AD diagnosis and subsequent treatment strategies.

Frequent Alzheimer's disease neuropathological change in patients with glioblastoma.

Background: The incidence of brain cancer and neurodegenerative diseases is increasing with a demographic shift towards aging populations. Biological parallels have been observed between glioblastoma and Alzheimer's disease (AD), which converge on accelerated brain aging. Here, we aimed to map the cooccurrence of AD neuropathological change (ADNC) in the tumor-adjacent cortex of patients with glioblastoma. Methods: Immunohistochemical screening of AD markers amyloid beta (Abeta), amyloid precursor protein (APP), and hyperphosphorylated tau (pTau) was conducted in 420 tumor samples of 205 patients. For each cortex area, we quantified ADNC, neurons, tumor cells, and microglia. Results: Fifty-two percent of patients (N = 106/205) showed ADNC (Abeta and pTau, Abeta or pTau) in the tumor-adjacent cortex, with histological patterns widely consistent with AD. ADNC was positively correlated with patient age and varied spatially according to Thal phases and Braak stages. It decreased with increasing tumor cell infiltration (P < .0001) and was independent of frequent expression of APP in neuronal cell bodies (N = 182/205) and in tumor necrosis-related axonal spheroids (N = 195/205; P = .46). Microglia response was most present in tumor cell infiltration plus ADNC, being further modulated by patient age and sex. ADNC did not impact patient survival in the present cohort. Conclusions: Our findings highlight the frequent presence of ADNC in the glioblastoma vicinity, which was linked to patient age and tumor location. The cooccurrence of AD and glioblastoma seemed stochastic without clear spatial relation. ADNC did not impact patient survival in our cohort.

The Impact of High-Dose Fish Oil Supplementation on Mfsd2a, Aqp4, and Amyloid-ß Expression in Retinal Blood Vessels of 5xFAD Alzheimer's Mouse Model.

In patients with Alzheimer's disease (AD) and in animal models, the increased accumulation of amyloid ß (Aß) in retinal blood vessels strongly correlates with brain amyloid deposits and cognitive decline. The accumulation of Aß in blood vessels may result from impaired transcytosis and a dysfunctional ocular glymphatic system in AD. High-dose fish oil (FO) supplementation has been shown to significantly change the expression of major facilitator superfamily domain-containing protein 2a (Mfsd2a), a key regulator of transcytosis, and Aquaporin 4 (Aqp4), an essential component of the glymphatic system in the retinas of WT mice. We examined the expression of Mfsd2a and Aqp4 in the retinas of 4-month-old 5xFAD female mice supplemented with high-dose FO for three weeks. There was a significant increase in Mfsd2a expression in 5xFAD retinas supplemented with FO compared to control 5xFAD mice. Additionally, the increase in Aqp4 expression observed in 4-month-old 5xFAD retinas, indicative of an impaired glymphatic system, was significantly decreased. Simultaneously, Aß accumulation in 5xFAD retinal blood vessels was reduced following FO supplementation. These findings suggest that high-dose FO supplementation could serve as an adjunct in developing new treatments aimed at improving the regulation of transcytosis or the function of the glymphatic system in the AD retina.

Emoxypine succinate modulates behavioral and molecular responses in zebrafish model of iron Overload-Induced neuroinflammation via CDK5/GSK3- ß and NLRP3 inflammasome pathway.

Excessive iron accumulation in the brain plays a significant role in neurodegenerative processes, contributing to the pathogenesis of Alzheimer's disease (AD). AD, a prominent neurological disorder affecting the central nervous system, is characterized by the accumulation of beta-amyloid (Aß) and tau phosphorylation. This accumulation leads to the subsequent development of cognitive impairments, particularly in learning and memory functions. This study investigates the neuroprotective effects of emoxypine succinate in a zebrafish model of iron overload-induced neurodegeneration. Iron was administered to the zebrafish for 28 days to induce neurodegeneration. Following induction, Emoxypine succinate was employed as a treatment intervention for 14 days (concentrations of 4 mg/L, 8 mg/L, and 12 mg/L). Following the end of the treatment, behavioral tests (Y maze test, Novel tank test) were conducted on the zebrafish, and the biochemical (MDA, Catalase, SOD, GSH) and molecular parameters (AchE, Iron levels, IL-1ß, TNF-α, CDK-5, GSK-3ß, and NLRP3) of the zebrafish brain were also assessed. In the novel tank test, emoxypine succinate-treated groups exhibited significantly increased time in the upper zone (p < 0.001), higher distance travelled (p < 0.001), and shorter latency to the top (p < 0.001) compared to the negative control. Similarly, the Y-maze test revealed improved time in the novel arm (p < 0.001) and total distance travelled (p < 0.001) in treated groups versus the negative control. Assessment of oxidative stress parameters demonstrated significant reductions in oxidative stress in emoxypine succinate-treated groups. Furthermore, AChE activity decreased significantly (p < 0.001), and brain iron levels decreased substantially (p < 0.001) in treated groups, indicating positive therapeutic outcomes. Molecular analysis showed a significant reduction in pro-inflammatory markers like IL-1ß, TNF-α, CDK-5, GSK-3ß, and NLRP3 (p < 0.001). This comprehensive study highlights the potential efficacy of emoxypine succinate in mitigating neurodegeneration associated with iron dysregulation.

Simple improvements in vector design afford substantial gains in AAV delivery of aggregation-slowing Aß variants.

Adeno-associated virus (AAV) gene therapy for neurological disease has gained traction due to stunning advances in capsid evolution for CNS targeting. With AAV brain delivery now in focus, conventional improvements in viral expression vectors offer a complementary route for optimizing gene delivery. We previously introduced a novel AAV gene therapy to slow amyloid aggregation in the brain based on neuronal release of an Aß sequence variant that inhibited fibrilization of wild-type Aß. Here we explore three coding elements of the virally delivered DNA plasmid in an effort to maximize the production of therapeutic peptide in the brain. We demonstrate that simply replacing the Gaussia luciferase signal peptide with the mouse immunoglobulin heavy chain signal peptide increased release of variant Aß by ∼5-fold. Sequence modifications within the expressed minigene further increased peptide release by promoting γ-secretase cleavage. Addition of a cytosolic fusion tag compatible with γ-secretase interaction allowed viral transduction to be tracked by immunostaining, independent from the variant Aß peptide. Collectively these construct modifications increased neuronal production of therapeutic peptide by 10-fold upon intracranial AAV injection of neonatal mice. These findings demonstrate that modest changes in expression vector design can yield substantial gains in AAV efficiency for therapeutic applications.

Utility of cerebrovascular imaging biomarkers to detect cerebral amyloidosis.

INTRODUCTION: The relationship between cerebrovascular disease (CVD) and amyloid beta (Aß) in Alzheimer's disease (AD) is understudied. We hypothesized that magnetic resonance imaging (MRI)-based CVD biomarkers-including cerebral microbleeds (CMBs), lacunar infarction, and white matter hyperintensities (WMHs)-would correlate with Aß positivity on positron emission tomography (Aß-PET). METHODS: We cross-sectionally analyzed data from the Alzheimer's Disease Neuroimaging Initiative (ADNI, N = 1352). Logistic regression was used to calculate odds ratios (ORs), with Aß-PET positivity as the standard-of-truth. RESULTS: Following adjustment, WMHs (OR = 1.25) and superficial CMBs (OR = 1.45) remained positively associated with Aß-PET positivity (p < 0.001). Deep CMBs and lacunes exhibited a varied relationship with Aß-PET in cognitive subgroups. The combined diagnostic model, which included CVD biomarkers and other accessible measures, significantly predicted Aß-PET (pseudo-R2 = 0.41). DISCUSSION: The study highlights the translational value of CVD biomarkers in diagnosing AD, and underscores the need for more research on their inclusion in diagnostic criteria. CLINICALTRIALS: gov: ADNI-2 (NCT01231971), ADNI-3 (NCT02854033). HIGHLIGHTS: Cerebrovascular biomarkers linked to amyloid beta (Aß) in Alzheimer's disease (AD). White matter hyperintensities and cerebral microbleeds reliably predict Aß-PET positivity. Relationships with Aß-PET vary by cognitive stage. Novel accessible model predicts Aß-PET status. Study supports multimodal diagnostic approaches.

Testing the causal impact of amyloidosis on total Tau using a genetically informative sample of adult male twins.

INTRODUCTION: The amyloid cascade hypothesis predicts that amyloid-beta (Aß) aggregation drives tau tangle accumulation. We tested competing causal and non-causal hypotheses regarding the direction of causation between Aß40 and Aß42 and total Tau (t-Tau) plasma biomarkers. METHODS: Plasma Aß40, Aß42, t-Tau, and neurofilament light chain (NFL) were measured in 1,035 men (mean = 67.0 years) using Simoa immunoassays. Genetically informative twin modeling tested the direction of causation between Aßs and t-Tau. RESULTS: No clear evidence that Aß40 or Aß42 directly causes changes in t-Tau was observed; the alternative causal hypotheses also fit the data well. In contrast, exploratory analyses suggested a causal impact of the Aß biomarkers on NFL. Separately, reciprocal causation was observed between t-Tau and NFL. DISCUSSION: Plasma Aß40 or Aß42 do not appear to have a direct causal impact on t-Tau. In contrast, Aß aggregation may causally impact NFL in cognitively unimpaired men in their late 60s.

Elevated C-Reactive Protein in Older Men With Chronic Pain: Association With Plasma Amyloid Levels and Hippocampal Volume.

BACKGROUND: Chronic pain leads to tau accumulation and hippocampal atrophy, which may be moderated through inflammation. In older men, we examined associations of chronic pain with Alzheimer's disease (AD)-related plasma biomarkers and hippocampal volume as moderated by systemic inflammation. METHODS: Participants were men without dementia. Chronic pain was defined as moderate-to-severe pain in 2+ study waves at average ages 56, 62, and 68. At age 68, we measured plasma amyloid-beta (Aß42, n = 871), Aß40 (n = 887), total tau (t-tau, n = 841), and neurofilament light chain (NfL, n = 915), and serum high-sensitivity C-reactive protein (hs-CRP, n = 968), a marker of systemic inflammation. A subgroup underwent structural MRI to measure hippocampal volume (n = 385). Analyses adjusted for medical morbidities, depressive symptoms, and opioid use. RESULTS: Chronic pain was related to higher Aß40 (ß = 0.25, p = .009), but hs-CRP was unrelated to AD-related biomarkers (ps > .05). There was a significant interaction such that older men with both chronic pain and higher levels of hs-CRP had higher levels of Aß42 (ß = 0.36, p = .001) and Aß40 (ß = 0.29, p = .003). Chronic pain and hs-CRP did not interact to predict levels of Aß42/Aß40, t-tau, or NfL. Furthermore, there were significant interactions such that Aß42 and Aß40 were associated with lower hippocampal volume, particularly when levels of hs-CRP were elevated (hs-CRP × Aß42: ß = -0.19, p = .002; hs-CRP × Aß40: ß = -0.21, p = .001), regardless of chronic pain status. CONCLUSIONS: Chronic pain was associated with higher plasma Aß, especially when hs-CRP was also elevated. Higher hs-CRP and Aß levels were both related to smaller hippocampal volumes. Chronic pain, when accompanied by systemic inflammation, may elevate the risk of neurodegeneration in AD-vulnerable regions.

Intracerebral inoculation of healthy non-transgenic rats with a single aliquot of oligomeric amyloid-ß (1-42) profoundly and progressively alters brain function throughout life.

One of the puzzling aspects of sporadic Alzheimer's disease (AD) is how it commences. Changes in one key brain peptide, amyloid-beta (Aß), accompany disease progression, but whether this comprises a trigger or a consequence of AD is still a topic of debate. It is clear however that the cerebral presence of oligomeric Aß (1-42) is a key factor in early AD-pathogenesis. Furthermore, treatment of rodent brains with oligomeric Aß (1-42) either in vitro or in vivo, acutely impairs hippocampal synaptic plasticity, creating a link between Aß-pathology and learning impairments. Here, we show that a once-off inoculation of the brains of healthy adult rats with oligomeric Aß (1-42) exerts debilitating effects on the long-term viability of the hippocampus, one of the primary targets of AD. Changes are progressive: months after treatment, synaptic plasticity, neuronal firing and spatial learning are impaired and expression of plasticity-related proteins are changed, in the absence of amyloid plaques. Early changes relate to activation of microglia, whereas later changes are associated with a reconstruction of astroglial morphology. These data suggest that a disruption of Aß homeostasis may suffice to trigger an irreversible cascade, underlying progressive loss of hippocampal function, that parallels the early stages of AD.

Anthocyanin-Rich Fraction of Black Rice Bran Extract Protects against Amyloid ß-Induced Oxidative Stress, Endoplasmic Reticulum Stress, and Neuronal Apoptosis in SK-N-SH Cells.

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the aging population. An accumulation of amyloid plaques and neurofibrillary tangles causes degeneration of neurons, leading to neuronal cell death. The anthocyanin-rich fraction of black rice (Oryza sativa L. variety "Luem Pua") bran (AFBRB), extracted using a solution of ethanol and water and fractionated using Amberlite XAD7HP column chromatography, contains a high anthocyanin content (585 mg of cyanidin-3-O-glucoside and 24 mg of peonidin-3-O-glucoside per gram of the rich extract), which has been found to reduce neurodegeneration. This study focused on the neuroprotective effects of AFBRB in Aß25-35-induced toxicity in the human neuroblastoma cell line (SK-N-SH). SK-N-SH was exposed to Aß25-35 (10 µM) to induce an AD cell model in vitro. Pretreatment with AFBRB (0.1, 1, or 10 µg/mL) or C3G (20 µM) was conducted for 2 h prior to the treatment with Aß25-35 (10 µM) for an additional 24 h. The results indicate that AFBRB can protect against the cytotoxic effect of Aß25-35 through attenuation of intracellular ROS production, downregulation of the expression of the proteins Bax, cytochrome c, cleaved caspase-9, and cleaved caspase-3, upregulation of the expression of Bcl-2 in the mitochondrial death pathway, and reduction in the expression of the three major markers of ER stress pathways in similar ways. Interestingly, we found that pretreatment with AFBRB significantly alleviated Aß-induced oxidative stress, ER stress, and apoptosis in SK-N-SH cells. This suggests that AFBRB might be a potential therapeutic agent in preventing neurodegenerative diseases.

Neurodegenerative biomarkers in different chambers of the eye relative to plasma: an agreement validation study.

BACKGROUND: Protein biomarkers have been broadly investigated in cerebrospinal fluid and blood for the detection of neurodegenerative diseases, yet a clinically useful diagnostic test to detect early, pre-symptomatic Alzheimer's disease (AD) remains elusive. We conducted this study to quantify Aß40, Aß42, total Tau (t-Tau), hyperphosphorylated Tau (ptau181), glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) in eye fluids relative to blood. METHODS: In this cross-sectional study we collected vitreous humor, aqueous humor, tear fluid and plasma in patients undergoing surgery for eye disease. All six biomarkers were quantitatively measured by digital immunoassay. Spearman and Bland-Altman correlation analyses were performed to assess the agreement of levels between ocular fluids and plasma. RESULTS: Seventy-nine adults underwent pars-plana vitrectomy in at least one eye. Of the 79, there were 77 vitreous, 67 blood, 56 tear fluid, and 51 aqueous samples. All six biomarkers were quantified in each bio-sample, except GFAP and NfL in tear fluid due to low sample volume. All six biomarkers were elevated in vitreous humor compared to plasma samples. T-Tau, ptau181, GFAP and NfL were higher in aqueous than in plasma, and t-Tau and ptau181 concentrations were higher in tear fluid than in plasma. Significant correlations were found between Aß40 in plasma and tears (r = 0.5; p = 0.019), t-Tau in plasma and vitreous (r = 0.4; p = 0.004), NfL in plasma and vitreous (r = 0.3; p = 0.006) and plasma and aqueous (r = 0.5; p = 0.004). No significant associations were found for Aß42, ptau181 and GFAP among ocular fluids relative to plasma. Bland-Altman analysis showed aqueous humor had the closest agreement to plasma across all biomarkers. Biomarker levels in ocular fluids revealed statistically significant associations between vitreous and aqueous for t-Tau (r = 0.5; p = 0.001), GFAP (r = 0.6; p < 0.001) and NfL (r = 0.7; p < 0.001). CONCLUSION: AD biomarkers are detectable in greater quantities in eye fluids than in plasma and show correlations with levels in plasma. Future studies are needed to assess the utility of ocular fluid biomarkers as diagnostic and prognostic markers for AD, especially in those at risk with eye disease.

Amyloid beta 1-40 and 1-42 fibril ratios and maturation level cause conformational differences with minimal impact on autophagy and cytotoxicity.

The amyloid ß (Aß) peptide has a central role in Alzheimer's disease (AD) pathology. The peptide length can vary between 37 and 49 amino acids, with Aß1-42 being considered the most disease-related length. However, Aß1-40 is also found in Aß plaques and has shown to form intertwined fibrils with Aß1-42. The peptides have previously also shown to form different fibril conformations, proposed to be related to disease phenotype. To conduct more representative in vitro experiments, it is vital to uncover the impact of different fibril conformations on neurons. Hence, we fibrillized different Aß1-40:42 ratios in concentrations of 100:0, 90:10, 75:25, 50:50, 25:75, 10:90 and 0:100 for either 24 h (early fibrils) or 7 days (aged fibrils). These were then characterized based on fibril width, LCO-staining and antibody-staining. We further challenged differentiated neuronal-like SH-SY5Y human cells with the different fibrils and measured Aß content, cytotoxicity and autophagy function at three different time-points: 3, 24, and 72 h. Our results revealed that both Aß1-40:42 ratio and fibril maturation affect conformation of fibrils. We further show the impact of these conformation changes on the affinity to commonly used Aß antibodies, primarily affecting Aß1-40 rich aggregates. In addition, we demonstrate uptake of the aggregates by neuronally differentiated human cells, where aggregates with higher Aß1-42 ratios generally caused higher cellular levels of Aß. These differences in Aß abundance did not cause changes in cytotoxicity nor in autophagy activation. Our results show the importance to consider conformational differences of Aß fibrils, as this can have fundamental impact on Aß antibody detection. Overall, these insights underline the need for further exploration of the impact of conformationally different fibrils and the need to reliably produce disease relevant Aß aggregates.

Distinct regional vulnerability to Aß and iron accumulation in post mortem AD brains.

INTRODUCTION: The paramagnetic iron, diamagnetic amyloid beta (Aß) plaques and their interaction are crucial in Alzheimer's disease (AD) pathogenesis, complicating non-invasive magnetic resonance imaging for prodromal AD detection. METHODS: We used a state-of-the-art sub-voxel quantitative susceptibility mapping method to simultaneously measure Aß and iron levels in post mortem human brains, validated by histology. Further transcriptomic analysis using Allen Human Brain Atlas elucidated the underlying biological processes. RESULTS: Regional increased paramagnetic and diamagnetic susceptibility were observed in medial prefrontal, medial parietal, and para-hippocampal cortices associated with iron deposition (R = 0.836, p = 0.003) and Aß accumulation (R = 0.853, p = 0.002) in AD brains. Higher levels of gene expression relating to cell cycle, post-translational protein modifications, and cellular response to stress were observed. DISCUSSION: These findings provide quantitative insights into the variable vulnerability of cortical regions to higher levels of Aß aggregation, iron overload, and subsequent neurodegeneration, indicating changes preceding clinical symptoms. HIGHLIGHTS: The vulnerability of distinct brain regions to amyloid beta (Aß) and iron accumulation varies. Histological validation was performed on stained sections of ex-vivo human brains. Regional variations in susceptibility were linked to gene expression profiles. Iron and Aß levels in ex-vivo brains were simultaneously quantified.

Fluorescence-Based Monitoring of Early-Stage Aggregation of Amyloid-ß, Amylin Peptide, Tau, and α-Synuclein Proteins.

Early-stage aggregates of amyloid-forming proteins, specifically soluble oligomers, are implicated in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Protein aggregation is typically monitored by fluorescence using the amyloid-binding fluorophore thioflavin T (ThT). Thioflavin T interacts, however, preferentially with fibrillar amyloid structures rather than with soluble, early-stage aggregates. In contrast, the two fluorophores, aminonaphthalene 2-cyanoacrylate-spiropyran (AN-SP) and triazole-containing boron-dipyrromethene (taBODIPY), were reported to bind preferentially to early-stage aggregates of amyloidogenic proteins. The present study compares ThT with AN-SP and taBODIPY with regard to their ability to monitor early stages of aggregation of four different amyloid-forming proteins, including amyloid-ß (Aß), tau protein, amylin, and α-synuclein. The results show that the three fluorophores vary in their suitability to monitor the early aggregation of different amyloid-forming proteins. For instance, in the presence of Aß and amylin, the fluorescence intensity of AN-SP increased at an earlier stage of aggregation than the fluorescence of ThT, albeit with only a small fluorescence increase in the case of AN-SP. In contrast, in the presence of tau and amylin, the fluorescence intensity of taBODIPY increased at an earlier stage of aggregation than the fluorescence of ThT. Finally, α-synuclein aggregation could only be monitored by ThT fluorescence; neither AN-SP nor taBODIPY showed a significant increase in fluorescence over the course of aggregation of α-synuclein. These results demonstrate the ability of AN-SP and taBODIPY to monitor the formation of early-stage aggregates from specific amyloid-forming proteins at an early stage of aggregation, although moderate increases in fluorescence intensity, relatively large uncertainties in fluorescence values, and limited solubility of both fluorophores limit their usefulness for some amyloid proteins. The capability to monitor early aggregation of some amyloid proteins, such as amylin, might accelerate the discovery of aggregation inhibitors to minimize the formation of toxic oligomeric species for potential therapeutic use.

Lupeol protect against LPS-induced neuroinflammation and amyloid beta in adult mouse hippocampus.

Neuroinflammation includes the activation of immune glial cells in the central nervous system, release pro-inflammatory cytokines, which disrupt normal neural function and contribute to various neurological disorders, including Alzheimer's disease (AD), Parkinson's disease, multiple sclerosis, and stroke. AD is characterized by various factors including amyloidogenesis, synaptic dysfunction, memory impairment and neuroinflammation. Lipopolysaccharide (LPS) constitutes a vital element of membrane of the gram-negative bacterial cell, triggering vigorous neuroinflammation and facilitating neurodegeneration. Lupeol, a naturally occurring pentacyclic triterpene, has demonstrated several pharmacological properties, notably its anti-inflammatory activity. In this study, we evaluated the anti-inflammatory and anti-Alzheimer activity of lupeol in lipopolysaccharide (LPS)-injected mice model. LPS (250ug/kg) was administered intraperitoneally to C57BL/6 N male mice for 1 week to induce neuroinflammation and cognitive impairment. For biochemical analysis, acetylcholinesterase (AChE) assay, western blotting and confocal microscopy were performed. AChE, western blot and immunofluorescence results showed that lupeol treatment (50 mg/kg) along with LPS administration significantly inhibited the LPS-induced activation of neuroinflammatory mediators and cytokines like nuclear factor (NF-κB), tumor necrosis factor (TNF-α), cyclooxygenase (COX-2) and interleukin (IL-1ß). Furthermore, we found that LPS-induced systemic inflammation lead to Alzheimer's symptoms as LPS treatment enhances level of amyloid beta (Aß), amyloid precursor protein (APP), Beta-site APP cleaving enzyme (BACE-1) and hyperphosphorylated Tau (p-Tau). Lupeol treatment reversed the LPS-induced elevated level of Aß, APP, BACE-1 and p-Tau in the hippocampus, showing anti-Alzheimer's properties. It is also determined that lupeol prevented LPS-induced synaptic dysfunction via enhanced expression of pre-and post-synaptic markers like SNAP-23, synaptophysin and PSD-95. Overall, our study shows that lupeol prevents memory impairment and synaptic dysfunction via inhibition of neuroinflammatory processes. Hence, we suggest that lupeol might be a useful therapeutic agent in prevention of neuroinflammation-induced neurological disorders like AD.

Huperzine A Regulates the Physiological Homeostasis of Amyloid Precursor Protein Proteolysis and Tau Protein Conformation-A Computational and Experimental Investigation.

The beneficial actions of the natural compound Huperzine A (Hup A) against age-associated learning and memory deficits promote this compound as a nootropic agent. Alzheimer's disease (AD) pathophysiology is characterized by the accumulation of amyloid beta (Aß). Toxic Aß oligomers account for the cognitive dysfunctions much before the pathological lesions are manifested in the brain. In the present study, we investigated the effects of Hup A on amyloid precursor protein (APP) proteolysis in SH-SY5Y neuroblastoma cells. Hup A downregulated the expression of ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) and presenilin 1 (PS1) levels but augmented the levels of A disintegrin and metalloproteinase 10 (ADAM10) with significant decrement in the Aß levels. We herein report for the first time an in silico molecular docking analysis that revealed that Hup A binds to the functionally active site of BACE1. We further analyzed the effect of Hup A on glycogen synthase kinase-3 ß (GSK3ß) and phosphorylation status of tau. In this scenario, based on the current observations, we propose that Hup A is a potent regulator of APP processing and capable of modulating tau homeostasis under physiological conditions holding immense potential in preventing and treating AD like disorders.

Linking Cerebral Malaria Pathogenesis to APOE-Mediated Amyloidosis: Observations and Hypothesis.

Although most children with cerebral malaria fully recover, more than a fifth of the survivors develop post-discharge neurodevelopmental sequelae suggestive of advanced neuronal injury. However, the cerebral molecular processes initiating neurological dysfunction in cerebral malaria are still debatable. In this article, we explore available data and hypothesise that cerebral malaria might be linked to APOE-mediated amyloidosis, one of the pathological processes associated with Alzheimer's disease. If our hypothesis is tested and found to be true, it could have far-reaching implications for what we know about cerebral malaria pathogenesis.