Disease modifying effects of the amyloid-beta protofibril-selective antibody mAb158 in aged Tg2576 transgenic mice.

Amyloid beta (Aß) peptides, which aggregate to form neocortical plaques in Alzheimer's disease, exist in states that range from soluble monomers and oligomers/protofibrils to insoluble fibrillar amyloid. The present study evaluated the effects of mAb158, a mouse monoclonal antibody version of lecanemab that preferentially binds to soluble Aß protofibrils, in aged transgenic mice (Tg2576) with Aß pathology. Female Tg2576 mice (12 months old) received weekly intraperitoneal mAb158 (35 mg/kg) or vehicle for 4 weeks or for 18 weeks, with or without a subsequent 12-week off-treatment period. Aß protofibril levels were significantly lower in mAb158-treated animals at both 4 and 18 weeks, while longer treatment duration (18 weeks) was required to observe significantly lower Aß42 levels in insoluble brain fractions and lower Aß plaque load. Following the off-treatment period, comparison of the vehicle- and mAb158-treated mice demonstrated that the Aß protofibril levels, insoluble Aß42 levels and Aß plaque load remained significantly lower in mAb158-treated animals, as compared with age-matched controls. However, there was a significant increase of brain accumulation of both the Aß protofibril levels, insoluble Aß42 levels and Aß plaque load after treatment cessation. Thus, repeated mAb158 treatment of aged Tg2576 mice first reduced Aß protofibril levels within 4 weeks of treatment, which then was followed by a reduction of amyloid plaque pathology within 18 weeks of treatment. These effects were maintained 12 weeks after the final dose, indicating that mAb158 had a disease-modifying effect on the Aß pathology in this mouse model. In addition, brain accumulation of both Aß protofibril levels and amyloid pathology progressed after discontinuation of the treatment which supports the importance of continued treatment with mAb158 to maintain the effects on Aß pathology.

Change in Cerebrospinal Fluid Tau Microtubule Binding Region Detects Symptom Onset, Cognitive Decline, Tangles, and Atrophy in Dominantly Inherited Alzheimer's Disease.

OBJECTIVE: Identifying cerebrospinal fluid measures of the microtubule binding region of tau (MTBR-tau) species that reflect tau aggregation could provide fluid biomarkers that track Alzheimer's disease related neurofibrillary tau pathological changes. We examined the cerebrospinal fluid (CSF) MTBR-tau species in dominantly inherited Alzheimer's disease (DIAD) mutation carriers to assess the association with Alzheimer's disease (AD) biomarkers and clinical symptoms. METHODS: Cross-sectional and longitudinal CSF from 229 DIAD mutation carriers and 130 mutation non-carriers had sequential characterization of N-terminal/mid-domain phosphorylated tau (p-tau) followed by MTBR-tau species and tau positron emission tomography (tau PET), other soluble tau and amyloid biomarkers, comprehensive clinical and cognitive assessments, and brain magnetic resonance imaging of atrophy. RESULTS: CSF MTBR-tau species located within the putative "border" region and one species corresponding to the "core" region of aggregates in neurofibrillary tangles (NFTs) increased during the presymptomatic stage and decreased during the symptomatic stage. The "border" MTBR-tau species were associated with amyloid pathology and CSF p-tau; whereas the "core" MTBR-tau species were associated stronger with tau PET and CSF measures of neurodegeneration. The ratio of the border to the core species provided a continuous measure of increasing amounts that tracked clinical progression and NFTs. INTERPRETATION: Changes in CSF soluble MTBR-tau species preceded the onset of dementia, tau tangle increase, and atrophy in DIAD. The ratio of 4R-specific MTBR-tau (border) to the NFT (core) MTBR-tau species corresponds to the pathology of NFTs in DIAD and change with disease progression. The dynamics between different MTBR-tau species in the CSF may serve as a marker of tau-related disease progression and target engagement of anti-tau therapeutics. ANN NEUROL 2023;93:1158-1172.

Sediment temperature characteristics and their relation to distribution patterns of two sentinel crab species in intertidal flats in western Japan.

In the context of global climate change, monitoring focused on temperature and benthic animals in intertidal flats and the development of metrics to assess climate change and ecosystem responses are essential for a sustainable society. However, few studies have assessed the relationship between intertidal sediment temperature and the distribution of benthic animals. To address this gap, in the present study, intertidal sediment temperatures were observed in 12 intertidal flats in 11 survey areas over 335 days, from October 2, 2019, to August 31, 2020, using water temperature data loggers. The characteristics of intertidal sediment temperatures were variable among the survey areas, and a correlation analysis suggested that such characteristics are possibly influenced by various spatial-scale factors, such as geographical, basin, and habitat scales. Furthermore, two sentinel crab species, Macrophthalmus japonicus and Macrophthalmus banzai were collected, and the number of wintering individuals of each species was estimated based on their carapace width to analyze the changes in abundances of the two species in each survey area. The results show that the number of days with daily minimum temperature ≥ 19 °C was the factor that influenced the abundance rate, suggesting that M. japonicus and M. banzai populations may decrease and increase, respectively, according to future climate change in Japan. Our findings emphasize the importance of long-term monitoring of sediment temperatures and benthic animals in intertidal flats to evaluate the influence of future climate change.

Development and application of a second-generation multilingual tool for invasion risk screening of non-native terrestrial plants.

Under the increasing threat to native ecosystems posed by non-native species invasions, there is an urgent need for decision support tools that can more effectively identify non-native species likely to become invasive. As part of the screening (first step) component in non-native species risk analysis, decision support tools have been developed for aquatic and terrestrial organisms. Amongst these tools is the Weed Risk Assessment (WRA) for screening non-native plants. The WRA has provided the foundations for developing the first-generation WRA-type Invasiveness Screening Kit (ISK) tools applicable to a range of aquatic species, and more recently for the second-generation ISK tools applicable to all aquatic organisms (including plants) and terrestrial animals. Given the most extensive usage of the latter toolkits, this study describes the development and application of the Terrestrial Plant Species Invasiveness Screening Kit (TPS-ISK). As a second-generation ISK tool, the TPS-ISK is a multilingual turnkey application that provides several advantages relative to the WRA: (i) compliance with the minimum standards against which a protocol should be evaluated for invasion process and management approaches; (ii) enhanced questionnaire comprehensiveness including a climate change component; (iii) provision of a level of confidence; (iv) error-free computation of risk scores; (v) multilingual support; (vi) possibility for across-study comparisons of screening outcomes; (vii) a powerful graphical user interface; (viii) seamless software deployment and accessibility with improved data exchange. The TPS-ISK successfully risk-ranked five representative sample species for the main taxonomic groups supported by the tool and ten angiosperms previously screened with the WRA for Turkey. The almost 20-year continuous development and evolution of the ISK tools, as opposed to the WRA, closely meet the increasing demand by scientists and decision-makers for a reliable, comprehensive, updatable and easily deployable decision support tool. For terrestrial plant screening, these requirements are therefore met by the newly developed TPS-ISK.

A combined physiologically-based pharmacokinetic and quantitative systems pharmacology model for modeling amyloid aggregation in Alzheimer's disease.

Antibody-mediated removal of aggregated ß-amyloid (Aß) is the current, most clinically advanced potential disease-modifying treatment approach for Alzheimer's disease. We describe a quantitative systems pharmacology (QSP) approach of the dynamics of Aß monomers, oligomers, protofibrils, and plaque using a detailed microscopic model of Aß40 and Aß42 aggregation and clearance of aggregated Aß by activated microglia cells, which is enhanced by the interaction of antibody-bound Aß. The model allows for the prediction of Aß positron emission tomography (PET) imaging load as measured by a standardized uptake value ratio. A physiology-based pharmacokinetic model is seamlessly integrated to describe target exposure of monoclonal antibodies and simulate dynamics of cerebrospinal fluid (CSF) and plasma biomarkers, including CSF Aß42 and plasma Aß42 /Aß40 ratio biomarkers. Apolipoprotein E genotype is implemented as a difference in microglia clearance. By incorporating antibody-bound, plaque-mediated macrophage activation in the perivascular compartment, the model also predicts the incidence of amyloid-related imaging abnormalities with edema (ARIA-E). The QSP platform is calibrated with pharmacological and clinical information on aducanumab, bapineuzumab, crenezumab, gantenerumab, lecanemab, and solanezumab, predicting adequately the change in PET imaging measured amyloid load and the changes in the plasma Aß42 /Aß40 ratio while slightly overestimating the change in CSF Aß42 . ARIA-E is well predicted for all antibodies except bapineuzumab. This QSP model could support the clinical trial design of different amyloid-modulating interventions, define optimal titration and maintenance schedules, and provide a first step to understand the variability of biomarker response in clinical practice.

CSF MTBR-tau243 is a specific biomarker of tau tangle pathology in Alzheimer's disease.

Aggregated insoluble tau is one of two defining features of Alzheimer's disease. Because clinical symptoms are strongly correlated with tau aggregates, drug development and clinical diagnosis need cost-effective and accessible specific fluid biomarkers of tau aggregates; however, recent studies suggest that the fluid biomarkers currently available cannot specifically track tau aggregates. We show that the microtubule-binding region (MTBR) of tau containing the residue 243 (MTBR-tau243) is a new cerebrospinal fluid (CSF) biomarker specific for insoluble tau aggregates and compared it to multiple other phosphorylated tau measures (p-tau181, p-tau205, p-tau217 and p-tau231) in two independent cohorts (BioFINDER-2, n = 448; and Knight Alzheimer Disease Research Center, n = 219). MTBR-tau243 was most strongly associated with tau-positron emission tomography (PET) and cognition, whereas showing the lowest association with amyloid-PET. In combination with p-tau205, MTBR-tau243 explained most of the total variance in tau-PET burden (0.58 ≤ R2 ≤ 0.75) and the performance in predicting cognitive measures (0.34 ≤ R2 ≤ 0.48) approached that of tau-PET (0.44 ≤ R2 ≤ 0.52). MTBR-tau243 levels longitudinally increased with insoluble tau aggregates, unlike CSF p-tau species. CSF MTBR-tau243 is a specific biomarker of tau aggregate pathology, which may be utilized in interventional trials and in the diagnosis of patients. Based on these findings, we propose to revise the A/T/(N) criteria to include MTBR-tau243 as representing insoluble tau aggregates ('T').

Population pharmacokinetic-pharmacodynamic analyses of amyloid positron emission tomography and plasma biomarkers for lecanemab in subjects with early Alzheimer's disease.

Lecanemab is a humanized immunoglobulin G1 monoclonal antibody that selectively binds to soluble Aß aggregate species, while demonstrating low affinity for Aß monomer. This article describes the population pharmacokinetic (PK) and PK/pharmacodynamic (PD) analyses for amyloid plaques, as measured using positron emission tomography (PET), and biomarkers of amyloid pathology as evidenced by Aß42/40 ratio and plasma p-tau181 following i.v. administration of lecanemab in subjects with early Alzheimer's disease. Lecanemab PKs were well-characterized with a two-compartment model with first-order elimination. Final PK model contained covariate effects of anti-drug antibody positive status, sex, body weight, and albumin on clearance. The time course of amyloid PET standard uptake ratio (SUVr), plasma Aß42/40 ratio, and p-tau181 were described using indirect response models with lecanemab exposure as a maximum effect function stimulating the reduction of SUVr, and as a linear function increasing Aß42/40 ratio and decreasing p-tau181 formation rates. PK/PD simulations show that 10 mg/kg biweekly dosing results in larger and faster decrease in SUVr and p-tau181 and increase in Aß42/40 ratio as compared to 10 mg/kg monthly dose. Furthermore, the PK/PD simulations showed that after treatment discontinuation the brain amyloid re-accumulation to baseline levels is slow with a recovery half-life of ~4 years, whereas plasma Aß42/40 ratio and p-tau181 return to baseline levels faster than amyloid. Given the relationship between changes in amyloid PET SUVr and soluble biomarkers, the developed PK/PD models can be used to inform lecanemab dose regimens in future clinical studies.

Lecanemab in patients with early Alzheimer's disease: detailed results on biomarker, cognitive, and clinical effects from the randomized and open-label extension of the phase 2 proof-of-concept study.

BACKGROUND: Lecanemab, a humanized IgG1 monoclonal antibody that targets soluble aggregated Aß species (protofibrils), has demonstrated robust brain fibrillar amyloid reduction and slowing of clinical decline in early AD. The objective of this analysis is to report results from study 201 blinded period (core), the open-label extension (OLE), and gap period (between core and OLE) supporting the effectiveness of lecanemab. METHODS: The lecanemab study 201 core was a double-blind, randomized, placebo-controlled study of 856 patients randomized to one of five dose regimens or placebo. An OLE of study 201 was initiated to allow patients to receive open-label lecanemab 10mg/kg biweekly for up to 24 months, with an intervening off-treatment period (gap period) ranging from 9 to 59 months (mean 24 months). RESULTS: At 12 and 18 months of treatment in the core, lecanemab 10 mg/kg biweekly demonstrated dose-dependent reductions of brain amyloid measured PET and corresponding changes in plasma biomarkers and slowing of cognitive decline. The rates of clinical progression during the gap were similar in lecanemab and placebo subjects, with clinical treatment differences maintained after discontinued dosing over an average of 24 months in the gap period. During the gap, plasma Aß42/40 ratio and p-tau181 levels began to return towards pre-randomization levels more quickly than amyloid PET. At OLE baseline, treatment differences vs placebo at 18 months in the randomized period were maintained across 3 clinical assessments. In the OLE, lecanemab 10 mg/kg biweekly treatment produced dose-dependent reductions in amyloid PET SUVr, improvements in plasma Aß42/40 ratio, and reductions in plasma p-tau181. CONCLUSIONS: Lecanemab treatment resulted in significant reduction in amyloid plaques and a slowing of clinical decline. Data indicate that rapid and pronounced amyloid reduction correlates with clinical benefit and potential disease-modifying effects, as well as the potential to use plasma biomarkers to monitor for lecanemab treatment effects. TRIAL REGISTRATION: ClinicalTrials.gov NCT01767311 .

Fully automated and highly specific plasma ß-amyloid immunoassays predict ß-amyloid status defined by amyloid positron emission tomography with high accuracy.

BACKGROUND: Clinicians, researchers, and patients alike would greatly benefit from more accessible and inexpensive biomarkers for neural ß-amyloid (Aß). We aimed to assess the performance of fully automated plasma Aß immunoassays, which correlate significantly with immunoprecipitation mass spectrometry assays, in predicting brain Aß status as determined by visual read assessment of amyloid positron emission tomography (PET). METHODS: The plasma Aß42/Aß40 ratio was measured using a fully automated immunoassay platform (HISCL series) in two clinical studies (discovery and validation studies). The discovery and validation sample sets were retrospectively and randomly selected from participants with early Alzheimer's disease (AD) identified during screening for the elenbecestat Phase 3 program. RESULTS: We included 197 participants in the discovery study (mean [SD] age 71.1 [8.5] years; 112 females) and 200 in the validation study (age 70.8 [7.9] years; 99 females). The plasma Aß42/Aß40 ratio predicted amyloid PET visual read status with areas under the receiver operating characteristic curves of 0.941 (95% confidence interval [CI] 0.910-0.973) and 0.868 (95% CI 0.816-0.920) in the discovery and validation studies, respectively. In the discovery study, a cutoff value of 0.102 was determined based on maximizing the Youden Index, and the sensitivity and specificity were calculated to be 96.0% (95% CI 90.1-98.9%) and 83.5% (95% CI 74.6-90.3%), respectively. Using the same cutoff value, the sensitivity and specificity in the validation study were calculated to be 88.0% (95% CI 80.0-93.6%) and 72.0% (95% CI 62.1-80.5%), respectively. CONCLUSIONS: The plasma Aß42/Aß40 ratio measured using the HISCL series achieved high accuracy in predicting amyloid PET status. Since our blood-based immunoassay system is less invasive and more accessible than amyloid PET and cerebrospinal fluid testing, it may contribute to the diagnosis of AD in routine clinical practice.

Assessment of a Plasma Amyloid Probability Score to Estimate Amyloid Positron Emission Tomography Findings Among Adults With Cognitive Impairment.

Importance: The diagnostic evaluation for Alzheimer disease may be improved by a blood-based diagnostic test identifying presence of brain amyloid plaque pathology. Objective: To determine the clinical performance associated with a diagnostic algorithm incorporating plasma amyloid-ß (Aß) 42:40 ratio, patient age, and apoE proteotype to identify brain amyloid status. Design, Setting, and Participants: This cohort study includes analysis from 2 independent cross-sectional cohort studies: the discovery cohort of the Plasma Test for Amyloidosis Risk Screening (PARIS) study, a prospective add-on to the Imaging Dementia-Evidence for Amyloid Scanning study, including 249 patients from 2018 to 2019, and MissionAD, a dataset of 437 biobanked patient samples obtained at screenings during 2016 to 2019. Data were analyzed from May to November 2020. Exposures: Amyloid detected in blood and by positron emission tomography (PET) imaging. Main Outcomes and Measures: The main outcome was the diagnostic performance of plasma Aß42:40 ratio, together with apoE proteotype and age, for identifying amyloid PET status, assessed by accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). Results: All 686 participants (mean [SD] age 73.2 [6.3] years; 368 [53.6%] men; 378 participants [55.1%] with amyloid PET findings) had symptoms of mild cognitive impairment or mild dementia. The AUC of plasma Aß42:40 ratio for PARIS was 0.79 (95% CI, 0.73-0.85) and 0.86 (95% CI, 0.82-0.89) for MissionAD. Ratio cutoffs for Aß42:40 based on the Youden index were similar between cohorts (PARIS: 0.089; MissionAD: 0.092). A logistic regression model (LRM) incorporating Aß42:40 ratio, apoE proteotype, and age improved diagnostic performance within each cohort (PARIS: AUC, 0.86 [95% CI, 0.81-0.91]; MissionAD: AUC, 0.89 [95% CI, 0.86-0.92]), and overall accuracy was 78% (95% CI, 72%-83%) for PARIS and 83% (95% CI, 79%-86%) for MissionAD. The model developed on the prospectively collected samples from PARIS performed well on the MissionAD samples (AUC, 0.88 [95% CI, 0.84-0.91]; accuracy, 78% [95% CI, 74%-82%]). Training the LRM on combined cohorts yielded an AUC of 0.88 (95% CI, 0.85-0.91) and accuracy of 81% (95% CI, 78%-84%). The output of this LRM is the Amyloid Probability Score (APS). For clinical use, 2 APS cutoff values were established yielding 3 categories, with low, intermediate, and high likelihood of brain amyloid plaque pathology. Conclusions and Relevance: These findings suggest that this blood biomarker test could allow for distinguishing individuals with brain amyloid-positive PET findings from individuals with amyloid-negative PET findings and serve as an aid for Alzheimer disease diagnosis.

A randomized, double-blind, phase 2b proof-of-concept clinical trial in early Alzheimer's disease with lecanemab, an anti-Aß protofibril antibody.

BACKGROUND: Lecanemab (BAN2401), an IgG1 monoclonal antibody, preferentially targets soluble aggregated amyloid beta (Aß), with activity across oligomers, protofibrils, and insoluble fibrils. BAN2401-G000-201, a randomized double-blind clinical trial, utilized a Bayesian design with response-adaptive randomization to assess 3 doses across 2 regimens of lecanemab versus placebo in early Alzheimer's disease, mild cognitive impairment due to Alzheimer's disease (AD) and mild AD dementia. METHODS: BAN2401-G000-201 aimed to establish the effective dose 90% (ED90), defined as the simplest dose that achieves ≥90% of the maximum treatment effect. The primary endpoint was Bayesian analysis of 12-month clinical change on the Alzheimer's Disease Composite Score (ADCOMS) for the ED90 dose, which required an 80% probability of ≥25% clinical reduction in decline versus placebo. Key secondary endpoints included 18-month Bayesian and frequentist analyses of brain amyloid reduction using positron emission tomography; clinical decline on ADCOMS, Clinical Dementia Rating-Sum-of-Boxes (CDR-SB), and Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog14); changes in CSF core biomarkers; and total hippocampal volume (HV) using volumetric magnetic resonance imaging. RESULTS: A total of 854 randomized subjects were treated (lecanemab, 609; placebo, 245). At 12 months, the 10-mg/kg biweekly ED90 dose showed a 64% probability to be better than placebo by 25% on ADCOMS, which missed the 80% threshold for the primary outcome. At 18 months, 10-mg/kg biweekly lecanemab reduced brain amyloid (-0.306 SUVr units) while showing a drug-placebo difference in favor of active treatment by 27% and 30% on ADCOMS, 56% and 47% on ADAS-Cog14, and 33% and 26% on CDR-SB versus placebo according to Bayesian and frequentist analyses, respectively. CSF biomarkers were supportive of a treatment effect. Lecanemab was well-tolerated with 9.9% incidence of amyloid-related imaging abnormalities-edema/effusion at 10 mg/kg biweekly. CONCLUSIONS: BAN2401-G000-201 did not meet the 12-month primary endpoint. However, prespecified 18-month Bayesian and frequentist analyses demonstrated reduction in brain amyloid accompanied by a consistent reduction of clinical decline across several clinical and biomarker endpoints. A phase 3 study (Clarity AD) in early Alzheimer's disease is underway. TRIAL REGISTRATION: Clinical Trials.gov NCT01767311 .

The ß-Secretase BACE1 in Alzheimer's Disease.

BACE1 (beta-site amyloid precursor protein cleaving enzyme 1) was initially cloned and characterized in 1999. It is required for the generation of all monomeric forms of amyloid-ß (Aß), including Aß42, which aggregates into bioactive conformational species and likely initiates toxicity in Alzheimer's disease (AD). BACE1 concentrations and rates of activity are increased in AD brains and body fluids, thereby supporting the hypothesis that BACE1 plays a critical role in AD pathophysiology. Therefore, BACE1 is a prime drug target for slowing down Aß production in early AD. Besides the amyloidogenic pathway, BACE1 has other substrates that may be important for synaptic plasticity and synaptic homeostasis. Indeed, germline and adult conditional BACE1 knockout mice display complex neurological phenotypes. Despite BACE1 inhibitor clinical trials conducted so far being discontinued for futility or safety reasons, BACE1 remains a well-validated therapeutic target for AD. A safe and efficacious compound with high substrate selectivity as well as a more accurate dose regimen, patient population, and disease stage may yet be found. Further research should focus on the role of Aß and BACE1 in physiological processes and key pathophysiological mechanisms of AD. The functions of BACE1 and the homologue BACE2, as well as the biology of Aß in neurons and glia, deserve further investigation. Cellular and molecular studies of BACE1 and BACE2 knockout mice coupled with biomarker-based human research will help elucidate the biological functions of these important enzymes and identify their substrates and downstream effects. Such studies will have critical implications for BACE1 inhibition as a therapeutic approach for AD.

A systematic RNAi screen reveals involvement of endocytic pathway in neuronal dysfunction in alpha-synuclein transgenic C. elegans.

Mutations or multiplications in alpha-synuclein gene cause familial forms of Parkinson disease or dementia with Lewy bodies (LB), and the deposition of wild-type alpha-synuclein as LB occurs as a hallmark lesion of these disorders, collectively referred to as synucleinopathies, implicating alpha-synuclein in the pathogenesis of synucleinopathy. To identify modifier genes of alpha-synuclein-induced neurotoxicity, we conducted an RNAi screen in transgenic C. elegans (Tg worms) that overexpress human alpha-synuclein in a pan-neuronal manner. To enhance the RNAi effect in neurons, we crossed alpha-synuclein Tg worms with an RNAi-enhanced mutant eri-1 strain. We tested RNAi of 1673 genes related to nervous system or synaptic functions, and identified 10 genes that, upon knockdown, caused severe growth/motor abnormalities selectively in alpha-synuclein Tg worms. Among these were four genes (i.e. apa-2, aps-2, eps-8 and rab-7) related to the endocytic pathway, including two subunits of AP-2 complex. Consistent with the results by RNAi, crossing alpha-synuclein Tg worms with an aps-2 mutant resulted in severe growth arrest and motor dysfunction. alpha-Synuclein Tg worms displayed a decreased touch sensitivity upon RNAi of genes involved in synaptic vesicle endocytosis, and they also showed impaired neuromuscular transmission, suggesting that overexpression of alpha-synuclein caused a failure in uptake or recycling of synaptic vesicles. Furthermore, knockdown of apa-2, an AP-2 subunit, caused an accumulation of phosphorylated alpha-synuclein in neuronal cell bodies, mimicking synucleinopathy. Collectively, these findings raise a novel pathogenic link between endocytic pathway and alpha-synuclein-induced neurotoxicity in synucleinopathy.

Habitat suitability maps for juvenile tri-spine horseshoe crabs in Japanese intertidal zones: A model approach using unmanned aerial vehicles and the Structure from Motion technique.

The tri-spine horseshoe crab, Tachypleus tridentatus, is a threatened species that inhabits coastal areas from South to East Asia. A Conservation management system is urgently required for managing its nursery habitats, i.e., intertidal flats, especially in Japan. Habitat suitability maps are useful in drafting conservation plans; however, they have rarely been prepared for juvenile T. tridentatus. In this study, we examined the possibility of constructing robust habitat suitability models (HSMs) for juveniles based on topographical data acquired using unmanned aerial vehicles and the Structure from Motion (UAV-SfM) technique. The distribution data of the juveniles in the Tsuyazaki and Imazu intertidal flats from 2017 to 2019 were determined. The data were divided into a training dataset for HSM construction and three test datasets for model evaluation. High accuracy digital surface models were built for each region using the UAV-SfM technique. Normalized elevation was assessed by converting the topographical models that consider the tidal range in each region, and the slope was calculated based on these models. Using the training data, HSMs of the juveniles were constructed with normalized elevation and slope as the predictor variables. The HSMs were evaluated using the test data. The results showed that HSMs exhibited acceptable discrimination performance for each region. Habitat suitability maps were built for the juveniles in each region, and the suitable areas were estimated to be approximately 6.1 ha of the total 19.5 ha in Tuyazaki, and 3.7 ha of the total 7.9 ha area in Imazu. In conclusion, our findings support the usefulness of the UAV-SfM technique in constructing HSMs for juvenile T. tridentatus. The monitoring of suitable habitat areas for the juveniles using the UAV-SfM technique is expected to reduce survey costs, as it can be conducted with fewer investigators over vast intertidal zones within a short period of time.

Network dysfunction in α-synuclein transgenic mice and human Lewy body dementia.

OBJECTIVE: Dementia with Lewy bodies (DLB) is associated with the accumulation of wild-type human α-synuclein (SYN) in neurons and with prominent slowing of brain oscillations on electroencephalography (EEG). However, it remains uncertain whether the EEG abnormalities are actually caused by SYN. METHODS: To determine whether SYN can cause neural network abnormalities, we performed EEG recordings and analyzed the expression of neuronal activity-dependent gene products in SYN transgenic mice. We also carried out comparative analyses in humans with DLB. RESULTS: We demonstrate that neuronal expression of SYN in transgenic mice causes a left shift in spectral power that closely resembles the EEG slowing observed in DLB patients. Surprisingly, SYN mice also had seizures and showed molecular hippocampal alterations indicative of aberrant network excitability, including calbindin depletion in the dentate gyrus. In postmortem brain tissues from DLB patients, we found reduced levels of calbindin mRNA in the dentate gyrus. Furthermore, nearly one quarter of DLB patients showed myoclonus, a clinical sign of aberrant network excitability that was associated with an earlier age of onset of cognitive impairments. In SYN mice, partial suppression of epileptiform activity did not alter their shift in spectral power. Furthermore, epileptiform activity in human amyloid precursor protein transgenic mice was not associated with a left shift in spectral power. INTERPRETATION: We conclude that neuronal accumulation of SYN slows brain oscillations and, in parallel, causes aberrant network excitability that can escalate into seizure activity. The potential role of aberrant network excitability in DLB merits further investigation.

Phosphorylation of alpha-synuclein characteristic of synucleinopathy lesions is recapitulated in alpha-synuclein transgenic Drosophila.

alpha-Synuclein is a major component of Lewy bodies in the brains of patients with Parkinson's disease (PD) as well as of neuronal/glial inclusions in a subset of neurodegenerative disorders collectively termed synucleinopathies. Here we studied by immunohistochemistry the accumulation of alpha-synuclein in transgenic (TG) Drosophila overexpressing wild-type (WT) or familial PD-linked mutant (i.e. A30P and A53T) alpha-synuclein in neurons, with special reference to the phosphorylation at Ser129, that is characteristic of human synucleinopathy lesions. Progressive accumulation of human alpha-synuclein was widely observed in the cell bodies and neurites of major neuronal nuclei in TG Drosophila brains, and phosphorylation of alpha-synuclein at Ser129 was detected in a limited subset of neurons approximately 1 week after alpha-synuclein immunoreactivity was first detected. Phosphorylated alpha-synuclein was most abundant in A53T mutant, followed by A30P and WT Drosophila. These results suggest that accumulation and phosphorylation of alpha-synuclein is recapitulated in neurons of alpha-synuclein transgenic Drosophila, that underscores the relevance of this model to human synucleinopatheis.

Human P301L-mutant tau expression in mouse entorhinal-hippocampal network causes tau aggregation and presynaptic pathology but no cognitive deficits.

Accumulation of hyperphosphorylated tau in the entorhinal cortex (EC) is one of the earliest pathological hallmarks in patients with Alzheimer's disease (AD). It can occur before significant Aß deposition and appears to "spread" into anatomically connected brain regions. To determine whether this early-stage pathology is sufficient to cause disease progression and cognitive decline in experimental models, we overexpressed mutant human tau (hTauP301L) predominantly in layer II/III neurons of the mouse EC. Cognitive functions remained normal in mice at 4, 8, 12 and 16 months of age, despite early and extensive tau accumulation in the EC. Perforant path (PP) axon terminals within the dentate gyrus (DG) contained abnormal conformations of tau even in young EC-hTau mice, and phosphorylated tau increased with age in both the EC and PP. In old mice, ultrastructural alterations in presynaptic terminals were observed at PP-to-granule cell synapses. Phosphorylated tau was more abundant in presynaptic than postsynaptic elements. Human and pathological tau was also detected within hippocampal neurons of this mouse model. Thus, hTauP301L accumulation predominantly in the EC and related presynaptic pathology in hippocampal circuits was not sufficient to cause robust cognitive deficits within the age range analyzed here.

Tau reduction does not prevent motor deficits in two mouse models of Parkinson's disease.

Many neurodegenerative diseases are increasing in prevalence and cannot be prevented or cured. If they shared common pathogenic mechanisms, treatments targeting such mechanisms might be of benefit in multiple conditions. The tau protein has been implicated in the pathogenesis of diverse neurodegenerative disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). Tau reduction prevents cognitive deficits, behavioral abnormalities and other pathological changes in multiple AD mouse models. Here we examined whether tau reduction also prevents motor deficits and pathological alterations in two mouse models of PD, generated by unilateral striatal injection of 6-hydroxydopamine (6-OHDA) or transgene-mediated neuronal expression of human wildtype α-synuclein. Both models were evaluated on Tau(+/+), Tau(+/-) and Tau(-/-) backgrounds in a variety of motor tests. Tau reduction did not prevent motor deficits caused by 6-OHDA and slightly worsened one of them. Tau reduction also did not prevent 6-OHDA-induced loss of dopaminergic terminals in the striatum. Similarly, tau reduction did not prevent motor deficits in α-synuclein transgenic mice. Our results suggest that tau has distinct roles in the pathogeneses of AD and PD and that tau reduction may not be of benefit in the latter condition.

Proteomics of Caenorhabditis elegans over-expressing human alpha-synuclein analyzed by fluorogenic derivatization-liquid chromatography/tandem mass spectrometry: identification of actin and several ribosomal proteins as negative markers at early Parkinson's disease stages.

It has been known that the over-expression of alpha-synuclein, the main protein of Lewy bodies in Parkinson's disease (PD), leads to neurodegeneration in PD models. In this study, the changes in protein expression between the transgenic over-expressing human alpha-synuclein wild type (alpha-synWT) and the control Caenorhabditis elegans were elucidated by fluorogenic derivatization-liquid chromatography/tandem mass spectrometry (FD-LC-MS/MS) proteome analysis, which is a highly selective, sensitive, repeatable and quantitative method for protein identification. Because the alpha-synuclein wild-type worms showed moderate levels of dopamine loss without overt behavioral abnormalities, it was suggested that the changes in proteins in the alpha-synWT are related in the sequence of the formation of Lewy bodies. Among more than 400 protein peaks detected, actin and several ribosomal proteins were identified for the first time as negative markers at early PD stages. Actin was suggested to be one of the important targets in the elucidation of the etiology of neuronal diseases such as PD or other synucleinopathies.