Transgenic Mouse Model Of Alzheimer's Disease Research Articles

Effect of bioactive extracts from Eucalyptus globulus leaves in experimental models of Alzheimer's disease.

Current therapies for Alzheimer's disease (AD) do not delay its progression, therefore, novel disease-modifying strategies are urgently needed. Recently, an increasing number of compounds from natural origin with protective properties against AD have been identified. Mixtures or extracts obtained from natural products containing several bioactive compounds have multifunctional properties and have drawn the attention because multiple AD pathways can be simultaneously modulated. This study evaluated the in vitro and in vivo effect of the essential oil (EO) obtained from the hydrodistillation of Eucalyptus globulus leaves, and an extract obtained from the hydrodistillation residual water (HRW). It was observed that EO and HRW have anti-inflammatory effect in brain immune cells modeling AD, namely lipopolysaccharide (LPS)- and amyloid-beta (Aβ)-stimulated microglia. In cell models that mimic AD-related neuronal dysfunction, HRW attenuated Aβ secretion and Aβ-induced mitochondrial dysfunction. Since the HRW's major components did not cross the blood-brain barrier, both EO and HRW were administered to the APP/PS1 transgenic AD mouse model by an intranasal route, which reduced cortical and hippocampal Aβ levels, and to rescue memory deficits and anxiety-like behaviors. Finally, HRW and EO were found to regulate cholesterol levels in aged mice after intranasal administration, suggesting that these extracts can reduce hypercholesterolemia and avoid risk for AD development. Overall, findings support a protective role of E. globulus extracts against AD‑like pathology and cognitive impairment highlighting the underlying mechanisms. These extracts obtained from underused forest biomass could be useful to develop nutraceutical supplements helpful to avoid AD risk and to prevent its progression.

Pharmacological inhibition of PLK2 kinase activity mitigates cognitive decline but aggravates APP pathology in a sex-dependent manner in APP/PS1 mouse model of Alzheimer's disease

Converging evidence from clinical and experimental studies suggest the potential significance of Polo-like kinase 2 (PLK2) in regulating the phosphorylation and toxicity of the Alzheimer's disease (AD)-related protein, amyloid precursor protein (APP). These findings have prompted various experimental trials aimed at inhibiting PLK2 kinase activity in different transgenic mouse models of AD. While positive impacts on cognitive decline were reported in these studies, the cellular effects remained controversial. In the present study, we sought to assess the cognitive and cellular consequences of chronic PLK2 inhibitor treatment in the APP/PS1 transgenic mouse model of AD. First, we confirmed that inhibiting PLK2 prevented cognitive decline in a sex-dependent manner, particularly by enhancing working memory in male APP/PS1 mice. Surprisingly, cellular analysis revealed that treatment with PLK2 inhibitor increased the load of amyloid plaques and elevated levels of soluble amyloid β (Aβ) 40 and Aβ42 in the cortex, as well as insoluble Aβ42 in the hippocampus of female mice, without affecting APP pathology in males. These results underscore the potential of PLK2 inhibition to mitigate cognitive symptoms in males. However, paradoxically, it intensifies amyloid pathology in females by enhancing APP amyloidogenic processing, creating a controversial aspect to its therapeutic impact. Overall, these data highlight the sex-dependent nature of the effects of PLK2 inhibition, which may also be influenced by the genetic background of the transgenic mouse model utilized.

Blocking α1 Adrenergic Receptor as a Novel Target for Treating Alzheimer's Disease.

While amyloidopathy and tauopathy have been recognized as hallmarks in Alzheimer's disease (AD) brain, recently, increasing lines of evidence have supported the pathological roles of cerebrovascular changes in the pathogenesis and progression of AD. Restoring or ameliorating the impaired cerebrovascular function during the early phase of the disease may yield benefits against the cognitive decline in AD. In the present study, we evaluated the potential therapeutic effects of nicergoline [NG, a well-known α1 adrenergic receptor (ADR) blocker and vasodilator] against AD through ameliorating vascular abnormalities. Our in vitro data revealed that NG could reverse β-amyloid1-42 (Aβ1-42)-induced PKC/ERK1/2 activation, the downstream pathway of α1-ADR activation, in α1-ADR-overexpressed N2a cells. NG also blocked Aβ1-42- or phenylephrine-induced constrictions in isolated rat arteries. All these in vitro data may suggest ADR-dependent impacts of Aβ on vascular function and the reversal effect of NG. In addition, the ameliorating impacts of NG treatment on cerebral vasoconstriction, vasoremodeling, and cognitive decline were investigated in vivo in a PSAPP transgenic AD mouse model. Consistent with in vitro findings, the chronic treatment of NG significantly ameliorated the cerebrovascular dysfunctions and Aβ plaque depositions in the brain. Moreover, an improved cognitive performance was also observed. Taken together, our findings supported the beneficial effects of NG on AD through adrenergic-related mechanisms and highlighted the therapeutic potential of α1-adrenergic vasomodulators against AD pathologies.

Network Medicine Approach Unravels Endophenotype Signature in Alzheimer's Disease through Large-Scale Comparative Proteomics Analysis: Vascular Dysfunction as a Prime Example.

Alzheimer's disease (AD) is the most common neurodegenerative disease burdening public health. We proposed a network-based infrastructure to identify protein signatures for five AD pathological endophenotypes: amyloidosis, tauopathy, vascular dysfunction, lysosomal dysfunction, and neuroinflammation. We analyzed 23 proteomic data sets from AD patients and transgenic mouse models, using network proximity to measure associations between endophenotype modules and differentially expressed proteins (DEPs) in the integrated AD proteome. We focused on the vascular dysfunction signature with 21 DEPs by integrating RNA-seq, single-cell transcriptomics, GWAS, and literature. Experiments on APP/PS1 and MCAO models highlighted three proteins (SEPT5, SNAP25, STXBP1) as novel AD biomarker candidates. This study demonstrates a network medicine framework for deciphering endophenotype signatures in AD.

A longitudinal MRI analysis reveals altered brain connectivity and microstructural changes in a transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by progressive cognitive decline and neuropathological changes, yet the underlying neurobiological mechanisms remain elusive. Here, we employed a multimodal longitudinal neuroimaging approach, using anatomical and functional sequences on a high field magnetic resonance imaging (MRI) preclinical scanner, to investigate alterations in brain connectivity and white matter microstructure in a transgenic mouse model of AD (J20) when compared to wild-type (WT) littermates. Functional connectivity analysis revealed distinct network disruptions in J20 mice, primarily involving connections between posterior and anterior brain regions; importantly, a significant interaction between group and age highlighted an exacerbation of these connectivity changes with advancing age in J20 mice. In addition, significant reductions in fractional anisotropy (FA) were observed in the corpus callosum of J20 mice compared to WT, indicative of microstructural alterations consistent with white matter pathology. The observed alterations in brain connectivity and microstructure provide valuable insights into the spatiotemporal processes underlying AD-related decline and underscore the utility of multimodal neuroimaging in elucidating the neurobiological substrates of AD pathology in animal models.

Higher sodium in older individuals or after stroke/reperfusion, but not in migraine or Alzheimer’s disease – a study in different preclinical models

Sodium serves as one of the primary cations in the central nervous system, playing a crucial role in maintaining normal brain function. In this study, we investigated alterations in sodium concentrations in the brain and/or cerebrospinal fluid across multiple models, including an aging model, a stroke model, a nitroglycerin (NTG)-induced rat migraine model, a familial hemiplegic migraine type 2 (FHM2) mouse model, and a transgenic mouse model of Alzheimer’s disease (AD). Our results reveal that older rats exhibited higher sodium concentrations in cerebrospinal fluid (CSF), plasma, and various brain regions compared to their younger counterparts. Additionally, findings from the stroke model demonstrated a significant increase in sodium in the ischemic/reperfused region, accompanied by a decrease in potassium and an elevated sodium/potassium ratio. However, we did not detect significant changes in sodium in the NTG-induced rat migraine model or the FHM2 mouse model. Furthermore, AD transgenic mice showed no significant differences in sodium levels compared to wild-type mice in CSF, plasma, or the hippocampus. These results underscore the nuanced regulation of sodium homeostasis in various neurological conditions and aging, providing valuable insights into potential mechanisms underlying these alterations.

Sex-specific hypothalamic neuropathology and glucose metabolism in an amyloidosis transgenic mouse model of Alzheimer’s disease

BackgroundAmyloid toxicity and glucose metabolic disorders are key pathological features during the progression of Alzheimer’s disease (AD). While the hypothalamus plays a crucial role in regulating systemic energy balance, the distribution of amyloid plaques in the preoptic, anterior, tuberal, and mammillary regions of the hypothalamus in AD mice, particularly across both sexes, remains largely unclear. Our ongoing research aims to explore hypothalamic neuropathology and glucose metabolic disturbances in a well-described APP/PS1 mouse model of AD.ResultsImmunocytochemical staining revealed that Old-AD-Female mice exhibited a greater hypothalamic Amyloid β (Aβ) burden than their Old-AD-Male counterparts, with the mammillary bodies showing the most severe accumulation. Analysis of ionized calcium binding adaptor molecule 1 (IBA1) immunoreactivity and Iba1 mRNA indicated differential microgliosis based on sex, while tanycytic territory and ZO-1 tight junction protein expression remained stable in AD mice. Moreover, sex-specific peripheral glucose metabolic parameters (random and fasting blood glucose) seemed to be exacerbated by age. Old AD mice of both sexes exhibited limited hypothalamic activation (c-Fos + cells) in response to blood glucose fluctuations. Hypothalamic Glut 1 expression decreased in young but increased in old female AD mice compared with age-matched male AD mice. Pearson correlation analysis further supported a negative correlation between hypothalamic Aβ load and random blood glucose in old AD groups of both genders, shedding light on the mechanisms underlying this amyloidosis mouse model.ConclusionAged APP/PS1 mice exhibit sex-specific hypothalamic neuropathology and differential glucose metabolism, highlighting distinct pathological mechanisms within each gender.

S-Nitrosylation of p39 promotes its degradation and contributes to synaptic dysfunction induced by β-amyloid peptide

Alzheimer’s disease (AD), characterized by cognitive decline, is increasingly recognized as a disorder marked by synaptic loss and dysfunction. Despite this understanding, the underlying pathophysiological mechanisms contributing to synaptic impairment remain largely unknown. In this study, we elucidate a previously undiscovered signaling pathway wherein the S-nitrosylation of the Cdk5 activator p39, a post-translational modification involving the addition of nitric oxide to protein cysteine residues, plays a crucial role in synaptic dysfunction associated with AD. Our investigation reveals heightened p39 S-nitrosylation in the brain of an amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic mouse model of AD. Additionally, soluble amyloid-β oligomers (Aβ), implicated in synaptic loss in AD, induce p39 S-nitrosylation in cultured neurons. Notably, we uncover that p39 protein level is regulated by S-nitrosylation, with nitric oxide S-nitrosylating p39 at Cys265 and subsequently promoting its degradation. Furthermore, our study demonstrates that S-nitrosylation of p39 at Cys265 significantly contributes to amyloid-β (Aβ) peptide-induced dendrite retraction and spine loss. Collectively, our findings highlight S-nitrosylation of p39 as a novel aberrant redox protein modification involved in the pathogenesis of AD, suggesting its potential as a therapeutic target for the disease.

Cannabinoid type 2 receptor deficiency leads to Aβ-induced cognitive impairment through promoting microglial sensitivity to Aβ in the prefrontal cortex in mice

AimsThis study is to investigate the effects of Cannabinoid type 2 receptor (CB2R) deficiency on microglia and cognitive function in both Aβ1–42-injected CB2R knockout mice and a transgenic mouse model of Alzheimer’s disease (AD) in brain. MethodsAfter hippocampal injection with Aβ1–42 oligomers in CB2R knockout mice with and without CB2R agonist treatment and in transgenic APP/PS1 mice with CB2R deletion, the novel object recognition (NOR) and Morris water maze (MWM) tests were performed to assess the animal behavior performance. Immunofluorescence staining was conducted to detect the microglial morphology and activation status. The expression of proinflammation and anti-inflammation cytokines were determined by qRT-PCR. ResultsCB2R deficiency significantly aggravated cognitive impairment in both Aβ1–42-induced and transgenic APP/PS1 animal model in NOR. In Aβ-injected mice lacking CB2R and transgenic APP/PS1 mice with CB2R deletion, microglia in the prefrontal cortex exhibited enhanced immunoreactivity with altered morphology. Furthermore, transformation of activated microglial phenotype in the prefrontal cortex was reduced in Aβ1–42-injected CB2R knockout mice after CB2R agonist treatment. The CB2R deficiency significantly increased the expression of proinflammatory cytokines in the prefrontal cortex, while it was observed in the hippocampus in both Aβ1–42-injected and transgenic APP/PS1 AD mouse model. Furthermore, CB2R deficiency increased concentrations of soluble Aβ 40 in the prefrontal cortex, but did not affect plaques deposition. ConclusionCB2R deletion led to enhanced neuroinflammatory responses via direct upregulating microglia activation in the prefrontal cortex during the early symptomatic phase of AD mice. CB2R modulates prefrontal cortical neuroinflammation, which is essential for regulating cognitive functions such as recognition memory at the early stage of AD.

Chronic administration of prebiotics and probiotics ameliorates pathophysiological hallmarks of Alzheimer's disease in a APP/PS1 transgenic mouse model.

Introduction: The gut microbiota (MB), although one of the main producers of Aβ in the body, in physiological conditions contributes to the maintainance of a healthy brain. Dysbiosis, the dysbalance between Gram-negative and Gram-positive bacteria in the MB increases Aβ production, contributing to the accumulation of Aβ plaques in the brain, the main histopathological hallmark of Alzheimer's disease (AD). Administration of prebiotics and probiotics, maintaining or recovering gut-MB composition, could represent a nutraceutical strategy to prevent or reduce AD sympthomathology. Aim of this research was to evaluate whether treatment with pre- and probiotics could modify the histopathological signs of neurodegeneration in hippocampal CA1 and CA3 areas of a transgenic mouse model of AD (APP/PS1 mice). The hippocampus is one of the brain regions involved in AD. Methods: Tg mice and Wt littermates (Wt-T and Tg-T) were fed daily for 6months from 2months of age with a diet supplemented with prebiotics (a multi-extract of fibers and plant complexes, containing inulin/fruit-oligosaccharides) and probiotics (a 50%-50% mixture of Lactobacillus rhamnosus and Lactobacillus paracasei). Controls were Wt and Tg mice fed with a standard diet. Brain sections were immunostained for Aβ plaques, neurons, astrocytes, microglia, and inflammatory proteins that were evaluated qualitatively and quantitatively by immunofluorescence, confocal microscopy and digital imaging with ImageJ software. Results: Quantitative analyses demonstrated that: 1) The treatment with pre- and probiotics significantly decreased Aβ plaques in CA3, while in CA1 the reduction was not significant; 2) Neuronal damage in CA1 Stratum Pyramidalis was significantly prevented in Tg-T mice; no damage was found in CA3; 3) In both CA1 and CA3 the treatment significantly increased astrocytes density, and GFAP and IBA1 expression, especially around plaques; 4) Microglia reacted differently in CA1 and CA3: in CA3 of Tg-T mice there was a significant increase of CD68+ phagocytic microglia (ball-and-chain phenomic) and of CX3CR1 compared with CA1. Discussion: The higher microglia reactivity could be responsible for their more efficient scavenging activity towards Aβ plaques in CA3 in comparison to CA1. Treatment with pre- and probiotics, modifying many of the physiopathological hallmarks of AD, could be considered an effective nutraceutical strategy against AD symptomatology.

The impacts of sex and the 5xFAD model of Alzheimer's disease on the sleep and spatial learning responses to feeding time.

The relationships between the feeding rhythm, sleep and cognition in Alzheimer's disease (AD) are incompletely understood, but meal time could provide an easy-to-implement method of curtailing disease-associated disruptions in sleep and cognition. Furthermore, known sex differences in AD incidence could relate to sex differences in circadian rhythm/sleep/cognition interactions. The 5xFAD transgenic mouse model of AD and non-transgenic wild-type controls were studied. Both female and male mice were used. Food access was restricted each day to either the 12-h light phase (light-fed groups) or the 12-h dark phase (dark-fed groups). Sleep (electroencephalographic/electromyographic) recording and cognitive behavior measures were collected. The 5xFAD genotype reduces NREM and REM as well as the number of sleep spindles. In wild-type mice, light-fed groups had disrupted vigilance state amounts, characteristics, and rhythms relative to dark-fed groups. These feeding time differences were reduced in 5xFAD mice. Sex modulates these effects. 5xFAD mice display poorer spatial memory that, in female mice, is curtailed by dark phase feeding. Similarly, female 5xFAD mice have decreased anxiety-associated behavior. These emotional and cognitive measures are correlated with REM amount. Our study demonstrates that the timing of feeding can alter many aspects of wake, NREM and REM. Unexpectedly, 5xFAD mice are less sensitive to these feeding time effects. 5xFAD mice demonstrate deficits in cognition which are correlated with REM, suggesting that this circadian-timed aspect of sleep may link feeding time and cognition. Sex plays an important role in regulating the impact of feeding time on sleep and cognition in both wild-type and 5xFAD mice, with females showing a greater cognitive response to feeding time than males.

Synbiotic therapy with Clostridium sporogenes and xylan promotes gut-derived indole-3-propionic acid and improves cognitive impairments in an Alzheimer's disease mouse model.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized primarily by cognitive impairment. Recent investigations have highlighted the potential of nutritional interventions that target the gut-brain axis, such as probiotics and prebiotics, in forestalling the onset of AD. In this study, whole-genome sequencing was employed to identify xylan as the optimal carbon source for the tryptophan metabolism regulating probiotic Clostridium sporogenes (C. sporogenes). Subsequent in vivo studies demonstrated that administration of a synbiotic formulation comprising C. sporogenes (1 × 1010 CFU per day) and xylan (1%, w/w) over a duration of 30 days markedly enhanced cognitive performance and spatial memory faculties in the 5xFAD transgenic AD mouse model. The synbiotic treatment significantly reduced amyloid-β (Aβ) accumulation in the cortex and hippocampus of the brain. Importantly, synbiotic therapy substantially restored the synaptic ultrastructure in AD mice and suppressed neuroinflammatory responses. Moreover, the intervention escalated levels of the microbial metabolite indole-3-propionic acid (IPA) and augmented the relative prevalence of IPA-synthesizing bacteria, Lachnospira and Clostridium, while reducing the dominant bacteria in AD, such as Aquabacterium, Corynebacterium, and Romboutsia. Notably, synbiotic treatment also prevented the disruption of gut barrier integrity. Correlation analysis indicated a strong positive association between gut microbiota-generated IPA levels and behavioral changes. In conclusion, this study demonstrates that synbiotic supplementation significantly improves cognitive and intellectual deficits in 5xFAD mice, which could be partly attributed to enhanced IPA production by gut microbiota. These findings provide a theoretical basis for considering synbiotic therapy as a novel microbiota-targeted approach for the treatment of metabolic and neurodegenerative diseases.

Alpha-lipoic acid alleviates cognitive deficits in transgenic APP23/PS45 mice through a mitophagy-mediated increase in ADAM10 α-secretase cleavage of APP

BackgroundAlpha-lipoic acid (ALA) has a neuroprotective effect on neurodegenerative diseases. In the clinic, ALA can improve cognitive impairments in patients with Alzheimer’s disease (AD) and other dementias. Animal studies have confirmed the anti-amyloidosis effect of ALA, but its underlying mechanism remains unclear. In particular, the role of ALA in amyloid-β precursor protein (APP) metabolism has not been fully elucidated.ObjectiveTo investigate whether ALA can reduce the amyloidogenic effect of APP in a transgenic mouse model of AD, and to study the mechanism underlying this effect.MethodsALA was infused into 2-month-old APP23/PS45 transgenic mice for 4 consecutive months and their cognitive function and AD-like pathology were then evaluated. An ALA drug concentration gradient was applied to 20E2 cells in vitro to evaluate its effect on the expression of APP proteolytic enzymes and metabolites. The mechanism by which ALA affects APP processing was studied using GI254023X, an inhibitor of A Disintegrin and Metalloproteinase 10 (ADAM10), as well as the mitochondrial toxic drug carbonyl cyanide m-chlorophenylhydrazone (CCCP).ResultsAdministration of ALA ameliorated amyloid plaque neuropathology in the brain tissue of APP23/PS45 mice and reduced learning and memory impairment. ALA also increased the expression of ADAM10 in 20E2 cells and the non-amyloidogenic processing of APP to produce the 83 amino acid C-terminal fragment (C83). In addition to activating autophagy, ALA also significantly promoted mitophagy. BNIP3L-knockdown reduced the mat/pro ratio of ADAM10. By using CCCP, ALA was found to regulate BNIP3L-mediated mitophagy, thereby promoting the α-cleavage of APP.ConclusionsThe enhanced α-secretase cleavage of APP by ADAM10 is the primary mechanism through which ALA ameliorates the cognitive deficits in APP23/PS45 transgenic mice. BNIP3L-mediated mitophagy contributes to the anti-amyloid properties of ALA by facilitating the maturation of ADAM10. This study provides novel experimental evidence for the treatment of AD with ALA.Graphical abstract

Reduced platelet activation and thrombus formation in male transgenic model mice of Alzheimer's disease suggests early sex-specific differences in platelet pathophysiology

Alzheimer's disease (AD) is the most common form of dementia and characterized by extracellular amyloid-β (Aβ) plaques, intracellular neurofibrillary tau tangles and neurodegeneration. Over 80 % of AD patients also exhibit cerebral amyloid angiopathy (CAA). CAA is a cerebrovascular disease caused by deposition of Aβ in the walls of cerebral blood vessels leading to vessel damage and impairment of normal blood flow. To date, different studies suggest that platelet function, including activation, adhesion and aggregation, is altered in AD due to vascular Aβ deposition. For example, the transgenic AD model mice APP23 mice that exhibit CAA and parenchymal Aβ plaques, show pre-activated platelets in the blood circulation and increased platelet integrin activation leading to a pro-thrombotic phenotype in these mice late stages of AD. However, it is still an open question whether or not platelets exhibit changes in their activation profile before they are exposed to vascular Aβ deposits. Therefore, the present study examined platelets from middle-aged transgenic APP23 mice at the age of 8–10 months. At this age, APP23 mice show amyloid plaques in the brain parenchyma but not in the vasculature. Our analyses show that these APP23 mice have unaltered platelet numbers and size, and unaltered surface expression of glycoproteins. However, the number of dense granules in transgenic platelets was increased while the release was unaltered. Male, but not female APP23 mice, exhibited reduced platelet activation after stimulation of the thrombin receptor PAR4 and decreased thrombus stability on collagen under flow conditions ex vivo compared to control mice. In an arterial thrombosis model in vivo, male APP23 mice showed attenuated occlusion of the injured artery compared to controls. These findings provide clear evidence for early changes in platelet activation and thrombus formation in male mice before development of overt CAA. Furthermore, reduced platelet activation and thrombus formation suggest sex-specific differences in platelet physiology in AD that has to be considered in future studies of platelets and their role in AD.

Apolipoprotein E polymorphisms and female fertility in a transgenic mouse model of Alzheimer’s disease

Apolipoprotein E (APOE) is a major cholesterol carrier responsible for lipid transport and injury repair in the brain. The human APOE gene (h-APOE) has 3 naturally occurring alleles: ε3, the common allele; ε4, which increases Alzheimer’s disease (AD) risk up to 15-fold; and ε2, the rare allele which protects against AD. Although APOE4 has negative effects on neurocognition in old age, its persistence in the population suggests a survival advantage. We investigated the relationship between APOE genotypes and fertility in EFAD mice, a transgenic mouse model expressing h-APOE. We show that APOE4 transgenic mice had the highest level of reproductive performance, followed by APOE3 and APOE2. Intriguingly, APOE3 pregnancies had more fetal resorptions and reduced fetal weights relative to APOE4 pregnancies. In conclusion, APOE genotypes impact fertility and pregnancy outcomes in female mice, in concordance with findings in human populations. These mouse models may help elucidate how h-APOE4 promotes reproductive fitness at the cost of AD in later life.

Modulation of Amyloid and Tau Aggregation to Alleviate Cognitive Impairment in a Transgenic Mouse Model of Alzheimer's Disease.

Aggregation of misfolded amyloid-β (Aβ) and hyperphosphorylated tau proteins to plaques and tangles, respectively, is the major drug target of Alzheimer's disease (AD), as the former is an onset biomarker and the latter is associated with neurodegeneration. Thus, we report a small molecule drug candidate, DN5355, with a dual-targeting function toward aggregates of both Aβ and tau. DN5355 was selected through a series of four screenings assessing 52 chemicals for their functions to inhibit and reverse the aggregation of Aβ and tau by utilizing thioflavin T. When orally administered to AD transgenic mouse model 5XFAD, DN5355 significantly reduced cerebral Aβ plaques and hyperphosphorylated tau tangles. In Y-maze spontaneous alteration and contextual fear conditioning tests, 5XFAD mice showed amelioration of cognitive deficits upon the oral administration of DN5355.

A small-molecule microtubule-stabilizing agent safely reduces Aβ plaque and tau pathology in transgenic mouse models of Alzheimer's disease.

Intraneuronal inclusions composed of tau protein are found in Alzheimer's disease (AD) and other tauopathies. Tau normally binds microtubules (MTs), and its disengagement from MTs and misfolding in AD is thought to result in MT abnormalities. We previously identified triazolopyrimidine-containing MT-stabilizing compounds that provided benefit in AD mouse models and herein describe the characterization and efficacy testing of an optimized candidate, CNDR-51997. CNDR-51997 underwent pharmacokinetic, pharmacodynamic, safety pharmacology, and mouse tolerability testing. In addition, the compound was examined for efficacy in 5XFAD amyloid beta (Aβ) plaque mice and PS19 tauopathy mice. CNDR-51997 significantly reduced Aβ plaques in 5XFAD mice and tau pathology in PS19 mice, with the latter also showing attenuated axonal dystrophy and gliosis. CNDR-51997 was well tolerated at doses that exceeded efficacy doses, with a good safety pharmacology profile. CNDR-51997 may be a candidate for advancement as a potential therapeutic agent for AD and/or other tauopathies. Highlights There is evidence of microtubule alterations (MT) in Alzheimer's disease (AD) brain and in mouse models of AD pathology. Intermittent dosing with an optimized, brain-penetrant MT-stabilizing small-molecule, CNDR-51997, reduced both Aβ plaque and tau inclusion pathology in established mouse models of AD. CNDR-51997 attenuated axonal dystrophy and gliosis in a tauopathy mouse model, with a strong trend toward reduced hippocampal neuron loss. CNDR-51997 is well tolerated in mice at doses that are meaningfully greater than required for efficacy in AD mouse models, and the compound has a good safety pharmacology profile.

Combining supervised and unsupervised analyses to quantify behavioral phenotypes and validate therapeutic efficacy in a triple transgenic mouse model of Alzheimer's disease.

Behavioral testing is an essential tool for evaluating cognitive function and dysfunction in preclinical research models. This is of special importance in the study of neurological disorders such as Alzheimer's disease. However, the reproducibility of classic behavioral assays is frequently compromised by interstudy variation, leading to ambiguous conclusions about the behavioral markers characterizing the disease. Here, we identify age- and genotype-driven differences between 3xTg-AD and non-transgenic control mice using a low-cost, highly customizable behavioral assay that requires little human intervention. Through behavioral phenotyping combining both supervised and unsupervised behavioral classification methods, we are able to validate the preventative effects of the immunosuppressant cyclosporine A in a rodent model of Alzheimer's disease, as well as the partially ameliorating effects of candidate drugs nebivolol and cabozantinib.

Microglial activation-sensitive gadolinium complex as a potential MRI contrast agent for Alzheimer’s disease diagnosis

Numerous studies have developed gadolinium (Gd)-based contrast agents (GBCAs) for in-vivo magnetic resonance imaging (MRI) with the aim of diagnosing Alzheimer’s disease (AD). Nevertheless, GBCAs that are capable of identifying microglial activation, a critical early indicator of AD pathology, for in-vivo diagnosis remain scarce. In response to this, we synthesized a novel GBCA, Gd-DO3A-Va, designed specifically to detect microglial activation using MRI. This innovative GBCA, which was conjugated with vanillic acid, demonstrated a high selectivity for microglial activation by targeting Toll-like receptor 4 (TLR4). The use of Gd-DO3A-Va in in-vivo imaging successfully highlighted microglial activation in a transgenic AD mouse model. In particular, the use of Gd-DO3A-Va for contrast-enhanced T1-weighted MRI enabled the detection of microglial activation within the hippocampus and cortex, regions notably affected by AD. The observed enhancements in the MR contrast correlated well with immunohistological evidence of microglial activation. Consequently, Gd-DO3A-Va represents a highly promising GBCA for the identification of microglial activation, providing a novel pathway for the molecular diagnosis of AD.

Human tau N-terminal domain-specific monoclonal antibodies: screening and application in blood detection

The antibodies to the microtubule-associated protein tau play a role in basic and clinical studies of Alzheimer's disease (AD) and other tauopathies. With the recombinant human tau441 as the immunogen, the hybridoma cell strains secreting the anti-human tau N-terminal domain (NTD-tau) monoclonal antibodies were generated by cell fusion and screened by limiting dilution. The purified monoclonal antibodies were obtained by inducing the mouse ascites and affinity chromatography. The sensitivity and specificity of the monoclonal antibodies were examined by indirect ELISA and Western blotting, respectively. A double antibody sandwich ELISA method for detecting human tau protein was established and optimized. The results showed that the positive cloning rate of hybridoma cells was 83.6%. A stable cell line producing ZD8F7 antibodies was established, and the antibody titer in the supernatant of the cell line was 1:16 000. The antibody titer in the ascitic fluid was higher than 1:256 000; and the titer of purified ZD8F7 monoclonal antibodies was higher than 1:128 000. The epitope analysis showed that the ZD8F7 antibody recognized tau21-37 amino acid in the N-terminal domain. The Western blotting results showed that the ZD8F7 antibody recognized the recombinant human tau protein of 50-70 kDa and the human tau protein of 50 kDa in the brain tissue of transgenic AD model mice (APP/PS1/tau). With ZD8F7 as a capture antibody, a quantitative detection method for human tau protein was established, which showed a linear range of 7.8-500.0 pg/mL and could identify human tau protein in the brain tissue of AD transgenic mice and human plasma but not recognize the mouse tau protein. In conclusion, the human NTD-tau-specific monoclonal antibody and the double antibody sandwich ELISA method established in this study are highly sensitive and can serve as a powerful tool for the detection of tau protein in neurodegenerative diseases.