bluuebunny/crossref_metadata_2025 huggingface dataset:
Apolipoprotein ε genotype and sex influences skeletal muscle bioenergetic response to diet
Authors: Johnson Chelsea N , Lysaker Colton R , McCoin Colin S , Kemna Riley E , John Casey S. , Thyfault John P , Wilkins Heather M , Geiger Paige C , Morris Jill K
Published: January 2025

Background

Apolipoprotein ε4 (APOE4) is a major risk factor for Alzheimer’s disease (AD). APOE4 carriers display altered whole‐body metabolism, including increased blood glucose and inuslin. Although conditions affecting whole‐body metabolism like obesity and diabetes are AD risk factors, knowledge regarding the contribution of peripheral tissues to this effect is minimal. Skeletal muscle is an important regulator of whole‐body metabolism as a primary site for nutrient oxidation, yet it is unclear if APOE4 affects muscle metabolism. We sought to determine the impact of APOE4 on muscle bioenergetic function.

Method

Male and female APOE3 and APOE4 targeted‐replacement mice on a C57BL/6 background (n = 61) from Taconic were fed a high (HFD, 45% fat) or low‐fat diet (LFD, 10% fat) for 4 months before sacrifice. APOE3 mice served as controls because APOE3 does not modify AD risk. At 8‐9 months old, carbohydrate‐driven oxygen consumption in isolated quadriceps mitochondria was measured at basal, state 3 (ADP), state 3 + glutamate, and state 3S (succinate) on the Oroboros Oxygraph‐2k and the gastrocnemius proteome was analyzed on a timsTOF HT mass spectrometer. Mitochondrial‐related metabolic proteins were identified using MitoCarta3.0. Serum lactate was measured using an Abcam kit.

Result

APOE4 associated with differential expression of 49 proteins compared to APOE3 in LFD females only (q‐value <0.05), including reduced levels of proteins involved in oxidative phosphorylation. APOE4 did not affect mitochondrial respiration. HFD altered the expression of 469 proteins in APOE4 females and between 80‐101 proteins in other groups (q‐value <0.05). HFD upregulated proteins involved in lipid metabolism in all groups. HFD upregulated proteins involved in carbohydrate metabolism and increased mitochondrial respiration (basal, p = 0.062; state 3, p = 0.009; state 3 +glutamate, p = 0.032; state 3S, p = 0.17) in APOE4 females only. HFD reduced serum lactate in APOE3 males (p = 0.041), APOE4 males (p = 0.081) and APOE3 females (p = 0.112).

Conclusion

HFD‐driven upregulation of proteins involved in carbohydrate metabolism in APOE4 female muscle only likely supports increased carbohydrate oxidative capacity and may explain the lack of reduction in serum lactate in this group. Proteomic analysis of human muscle is ongoing to determine if this is reflected in humans.
C‐reactive protein as an inflammatory biomarker for early Alzheimer’s Disease pathogenesis
Authors: Dey Aditi , Kern Silke , Skoog Ingmar
Published: January 2025

Background

C‐reactive protein (CRP) is an inflammatory biomarker that has been associated with an increased risk of future cognitive decline, alongside other biomarkers such as β‐amyloid (Aβ). We sought to explore the relationship between CRP levels and the amyloid/tau/neurodegeneration (A/T/N) groups in elderly individuals with and without APOE‐ε4.

Method

From 1203 participants of the Gothenburg H70 Birth Cohort study, born in 1944, plasma CRP levels were collected among 300 participants (159 men & 141 women) who did not have dementia. Cerebrospinal fluid (CSF) levels were taken to create ATN groups and explore their correlation with plasma CRP levels. A linear model was created to analyze mean CRP levels in comparison to varying ATN groups. Additionally, the relationship between CRP levels and participant MMSE scores was analyzed.

Result

A negative linear trend was found (p‐value 0.014) with decreasing CRP (0.52 mg/L) in ATN groups with increasing levels of Aβ and p‐tau, meaning CRP decreased as Aβ and p‐tau crossed their respective concentration thresholds to be considered pathological. The A+T+N+ group had lower mean CRP levels than A‐T‐N‐, while the A‐T‐N+ group had higher CRP levels than A‐T‐N‐. Individuals with low Aβ had low CRP more often than those with normal Aβ. No significant difference was found between the mean CRP levels and participants’ MMSE scores (p‐value 0.4117).

Conclusion

In conclusion, the results from this study indicate an association between decreasing CRP levels and the progression of early AD pathogenesis. Though elevations in CRP may be a negative prognostic marker in other diseases, associated with brain aging and inflammation, the immune system might be altered depending on the stage of the disease with CRP levels elevated decades before disease onset, decreased years before and during the early stages of the disease, then finally increased again in more advanced stages of the disease. No relationship was found between CRP level and MMSE score.
Cognitive reserve influences symptom onset and longitudinal decline in Dominantly Inherited Alzheimer's Disease
Authors: Llibre‐Guerra Jorge J. , Lu Ruijin , Renton Alan E. , Gordon Brian A. , Benzinger Tammie L.S. , Aschenbrenner Andrew J. , Hassenstab Jason J. , Xiong Chengjie , Perrin Richard J. , Ibanez Laura , Goate Alison M. , Cruchaga Carlos , Morris John C. , Daniels Alisha , McDade Eric , Bateman Randall J.
Published: January 2025

Background

Cognitive reserve (CR) has emerged as a critical factor in understanding clinical‐cognitive heterogeneity in Alzheimer’s disease (AD). However, there is limited evidence of the effect of CR during asymptomatic phases of the disease, age at symptom onset (AAO) and longitudinal decline. In this study, we elucidate the impact of CR on AAO and decline rate using Dominantly Inherited Alzheimer’s Disease (DIAD) as a disease progression model.

Methods

DIAD participants were selected from the Dominantly Inherited Alzheimer Network (DIAN) study1. Using structural equation models, we utilized a residual approach to quantify CR. Variance in DIAN cognitive composite2 was decomposed into three latent components (Figure 1): demographic component (CogD), biomarker component (CogB), and reserve component (CogR). CogD refers to variance in the cognitive composite explained by demographic factors. CogB refers to the variance explained by AD biomarkers and markers of neurodegeneration. CogR represents the residual variance in the cognitive composite not explained by CogD or CogB. We examined the relationship between these components and clinical outcomes, including AAO, Clinical Dementia Rating®‐Sum of Boxes (CDR®‐SB), and transition from asymptomatic (CDR = 0) to symptomatic (CDR>0).

Results

319 participants (asymptomatic mutation carriers [aMC] n = 204, symptomatic MC [sMC] n = 115) were included in the analysis. Individuals with higher baseline CogR had greater odds ratio (OR) of remaining asymptomatic. For the aMC, after adjusting by mutation mean AAO3, one SD increase in the CogR component would multiply the OR of being CDR‐SB = 0 by 4.06 (95%CI 1.8‐8.9), while one SD increase in CogD and CogB component will multiply the OR by 2.6 (95%CI 1.1‐6.2) and 5.16 (95% CI 2.0‐13.3), respectively. For sMC, only the CogR and the CogB components were significant. One SD increase in CogR and CogB corresponds to 0.81 (95%CI 0.72‐0.92) and 0.60 (95%CI 0.50‐0.71) fold decrease in baseline CDR‐SB, respectively. Longitudinally, higher CogR values significantly predicted protection against conversion to CDR >0 and slower progression on CDR‐SB.

Conclusions

CR significantly modifies both AAO and rate of clinical decline in DIAD. These findings highlight CR as a factor in AD progression and suggest potential avenues for intervention by enhancing CR to delay onset.
Evaluation of the effects of a calcineurin inhibitor in experimental models of Alzheimer’s disease
Authors: Santos Sarah Tavares Araújo , Gomes Giovanni Freitas , Rocha Nádia Gomes , Oliveira Antônio Carlos Pinheiro
Published: January 2025

Background

Calcineurin, a protein involved in functions such as synaptic plasticity and neuronal survival, plays an important role in the pathophysiology of Alzheimer’s disease. This study, randomized, investigated the effects of FK506 (FK), a calcineurin inhibitor, on the behavioral, histological, and biochemical alterations observed in models of neurotoxicity induced by NMDA or Aβ and in a transgenic model for AD, in addition to the organotypic culture model stimulated with NMDA.

Methods

This study involved models for AD to experiment injecting NMDA or Aβ1‐42 into the hippocampus of male C57Bl/6 mice aged 8‐12 weeks to induce a neurotoxicity model, treating double‐transgenic APP/PS1 mice, expressing both mouse/human APP and mutant human PS1, with chronic FK506 for AD, in which, to enable NMDA or Aβ1‐42 microinjections, another experiment including a stereotaxic surgery was performed on the C57Bl/6 mice. FK506 doses and the pre‐treatment time were chosen based on prior related studies and its ability to cross the BBB. To obtain organotypic cultures, animals aged between 1 and 3 days were used. Their hippocampi were dissected in an ice‐cold culture and then stimulated with NMDA, which is neurotoxic, or PBS, having previously been inserted into a medium containing FK506 or a negative control. In addition, the microglia depletor clodronate disodium was added to the hippocampal slices. The exploratory open field task, the elevated plus maze (LCE), the interaction test (IS) and social memory and ORT were used to evaluate behavior. To complement the results, real‐time quantitative PCR and a statistical analysis of the data were carried out.

Results

FK506 played a protective role in cognitive impairment in both in vivo models and reduced FJC labeling and microgliosis in the Aβ model. FK506 also prevented the reduction of NeuN, a mature neuron marker, expression in organotypic cultures stimulated with NMDA. Furthermore, chronic treatment with FK506 protected against the behavioral alterations observed in LCE and IS. In addition, FK506 reduced microgliosis in the hippocampus of APP/PS1 animals.

Conclusion

Together, these results demonstrate the protective potential of FK506 against the pathology observed in AD models.
Associations of CSF Angiogenic Factors with Cerebrovascular Lesion in Alzheimer’s Disease
Authors: Lin Jun , Shi Jiong
Published: January 2025

Background

Mounting evidence suggests an increase in angiogenesis in the Alzheimer’s disease (AD) brain, but the role of this process in AD remains uncertain. The present study aims to explore the association between CSF angiogenic factors that promote angiogenesis and cerebrovascular lesions as well as neurodegeneration.

Method

The cross‐sectional study included 104 individuals with a CDR score of ≤ 0.5 and 96 individuals with a CDR score > 0.5. We measured 12 angiogenic factors using immunoassays. Cerebrovascular lesions were assessed through CSF PDGFRβ, Qalb, and WMH volume, while neurodegeneration was evaluated by cortical thickness and serum NFL. Cognitive function was measured using MMSE.

Result

Higher tau pathology showed associations with increased levels of CSF sVEGFRII, VEGF‐C, VEGF‐D, PLGF, Angiopoietin2, and Serpin E1. Although both Aβ pathology and tau pathology were associated with elevated levels of CSF sVEGFRI, sTIE2, and bFGF, the effects of Aβ pathology seemed to be influenced by tau pathology. Moreover, higher levels of sVEGFRII, sTIE2, PLGF, Serpin E1, IL8, and lower levels of VEGF‐C and uPA were linked to increased CSF PDGFRβ, Qalb, or WMH volume. Furthermore, higher levels of sVEGFRI, sTIE2, PLGF, Angiopoietin2, IL8, and lower levels of VEGF‐A and uPA were associated with reduced cortical thickness, increased serum NFL, and decreased MMSE scores.

Conclusion

Tau pathology may play a critical role in regulating the elevated CSF angiogenic factors, which could contribute to cerebrovascular lesions and neurodegeneration in AD. These results highlight the therapeutic potential of inhibiting hypervascularization or promoting the maturation of neonatal blood vessels in AD.
Prodromal stage in Lewy body dementia in a population of Argentina
Authors: Fernandez Maria Cecilia , Berrios Waleska , Campora Nuria , Golimstok Angel
Published: January 2025

Background

Prodromal stage of Lewy Body Dementia (LBD) is characterized by a set of symptoms that do not yet meet the criteria for dementia. These symptoms are caused by changes in the brain that have not yet reached the threshold for triggering the disease in its complete form.

Identifying the prodromal stage of neurodegenerative diseases is crucial for early treatment and prevention of progression to a clinical stage. This study aimed to determine the clinical profile in the prodromal stage of LBD in a population of Argentina.

Method

Over six months, we recruited subjects with dementia and a control group of individuals without neurocognitive disorder (NC). All participants underwent a comprehensive medical history, neuropsychological tests, and neuroimaging.

Dementia patients were divided into two groups: Group 1 consisted of patients with probable DLB according to the consensus criteria of McKeith et al. 2017. Group 2 consisted of patients with Major Neurocognitive Disorder due to Alzheimer’s Disease (AD) according to DSM V criteria.

To detect the presence of early clinical signs, we interviewed family members of patients based on central and supportive clinical signs according to Consortium‐DLB 2017 that may have been present up to 20 years before the dementia diagnosis.

Result

The study included 212 participants; 56 were classified as NC, 72 in Group 1, and 84 in Group 2. No significant differences were observed in sociodemographic factors. Notably, LBD patients exhibited a higher frequency of REM sleep behavior disorder (12.5%), visual hallucinations (9.7%), and syncope (9.7%) compared to the other groups, with statistical significance (p<0.01). Other variables did not show significant differences.

Conclusion

In this population with LBD, visual hallucinations, syncope, and REM sleep behavior disorder may occur more than 20 years before the onset of dementia and constitute signs of the prodromal stage. Encouraging the search for these symptoms is essential since they are not frequently questioned in patients with mild cognitive complaints.
Altered Hepatic and Cerebral Lipid Mediator Pathways in Alzheimer’s Disease
Authors: Zhou Sitong , Borkowski Kamil , Liang Nuanyi , Beach Thomas G. , Serrano Geidy E , Kim Kyoungmi , Hammock Bruce D. , Newman John W. , Jin Lee‐Way , Maezawa Izumi
Published: January 2025

Background

Inflammation is crucial in Alzheimer’s Disease (AD), where oxidized lipid derivatives of polyunsaturated fatty acids (PUFAs), i.e., oxylipins, are potent modulators. Soluble epoxide hydrolase (sEH), known for converting pro‐resolving epoxy‐fatty acids to pro‐inflammatory dihydroxy‐fatty acids (diols), is upregulated in the AD brain. Recent studies identify AD as a systemic disorder, but peripheral organs are understudied. Given the liver’s pivotal role in metabolizing lipids and circulating lipid mediators’ production, we tested the hypothesis that the inflammatory lipid mediator networks altered in the brain are also perturbed in the liver.

Method

AD diagnosis was based on the NIA‐AA guidelines. We analyzed lipid mediators in paired postmortem brain and liver tissues from 16 cognitive normal and 63 AD participants with short postmortem intervals (≤3 hours). Both alkali‐releasable and free oxylipins were measured using LC‐MS/MS‐based methods. Aberrant metabolites associated with AD were identified using analysis of covariance, adjusting for sex, age, BMI, and postmortem interval. Sex differences were explored.

Result

In both the brain and liver of AD participants, we found altered levels of alkali‐releasable ethanolamides, recognized for their neuroprotective and anti‐inflammatory properties. The most significant changes were observed in sEH activities within the AD liver, where pro‐inflammatory diols decreased in alkali‐releasable fractions. This reversely confirms the published results of increased free diols in AD plasma, as the esterified oxylipin pool serves as a reservoir for free oxylipins. These findings suggest that circulating metabolites of sEH and ethanolamides may predict AD pathogenesis. We also found that the decreased level of pro‐inflammatory 20‐HETE in the AD liver, which did not align with our expectations. Moreover, observations hinted at male proneness to inflammation.

Conclusion

Our data show significant alterations in lipid mediators in both the AD brain and liver, with liver exhibiting the most pronounced changes. This supports AD being a systemic disorder with the potential for liver to regulate brain function via lipid mediators and emphasizes the complexity of lipid metabolism in AD. Sex distinctions underscore the importance of considering it as a variable in future research. Additionally, it highlights the need to explore the biological implications of alkali‐releasable mediators.
Peripheral Signatures of Disease Heterogeneity
Authors: Higginbotham Lenora A
Published: January 2025

Background

There is currently an unmet need for novel accessible biomarkers that capture the complex and heterogenous pathophysiology of Alzheimer’s disease (AD). Over the past decade, the systems‐based multi‐omic approaches employed by the Accelerating Medicines Partnership in AD (AMP‐AD) have resulted in the identification of promising peripheral markers of disease heterogeneity. This scientific review will highlight these advances with a particular focus on the consortium’s successes in peripheral protein biomarker discovery in cerebrospinal fluid (CSF) and plasma.

Methods

The AMP‐AD consortium has applied a brain‐to‐biofluids approach to biomarker discovery designed to identify CSF and plasma markers that reflect the heterogeneous corticolimbic pathophysiology of AD. The successful identification of such biomarkers has relied on a combination of innovative multi‐omic techniques, sophisticated data integration strategies, and informative machine learning algorithms. Network‐based proteomic analysis has proven a powerful tool for advancing this brain‐to‐biofluids strategy.

Results

Network‐based proteomic analysis across hundreds of human brain tissues from AMP‐AD institutions has identified highly reproducible alterations in a variety of co‐expressed protein groups or “modules” in AD. These disease‐associated modules reflect diverse pathophysiology, including synaptic, metabolic, vascular, and inflammatory dysfunction. Integrative analyses have demonstrated that these brain‐based alterations are highly reflected in the AD CSF proteome. AMP‐AD researchers recently validated a 48‐marker brain‐derived CSF panel that can reliably predict cognitive trajectory, amyloid / tau status, and the evolution of neuroimaging markers. In a separate analysis, CSF levels of select matrisome heparin‐binding proteins originally identified in brain network studies discriminated autosomal dominant AD mutation carriers years prior to symptom onset as well or even better than traditional amyloid and tau measures. These matrisome markers have also demonstrated reliable disease‐associated alterations in heparin‐enriched plasma, highlighting their potential as AD blood‐based biomarkers. Finally, emerging research suggests the CSF and plasma marker profiles generated from these network‐based analyses can delineate biological subtypes of AD with distinct clinicopathological phenotypes.

Conclusions

Over the past decade, AMP‐AD has successfully leveraged brain‐to‐biofluid multi‐omic approaches to identify and validate promising peripheral biomarkers of AD. Network‐based proteomics has proven a valuable tool in furthering these biomarker efforts and advancing precision medicine within this complex and heterogeneous disease.
Cortical thinning and Cognition in Cerebral Small Vessel Disease
Authors: Kapasi Alifiya , Lamar Melissa , Wagner Maude , Evia Arnold M , Bennett David A. , Leurgans Sue E. , Arfanakis Konstantions , Schneider Julie A.
Published: January 2025

Background

Evidence is accumulating that cerebral small vessel disease may contribute to neurodegeneration. Brain arteriolosclerosis, a prominent type of small vessel disease in the aging brain, is associated with cognition. Using a previously developed published automated in‐vivo MRI classifier for arteriolosclerosis (ARTS), we examined cross‐sectionally the associations between ARTS, cortical thinning, and cognition.

Method

Data came from 1,023 older participants from 5 ongoing Rush Alzheimer’s Disease Center cohort studies. Participants underwent detailed annual cognitive evaluations and completed at least one in‐vivo 3T MRI scan and one cognitive evaluation during follow‐up. In addition to global cognitive measures and MRI‐derived measures for ARTS score, data including global and lobar cortical thinning composites calculated using FreeSurfer. Using the latest completed MRI scan and a close assessment of cognition, linear regression models were employed to examine the association of ARTS with cortical thinning (global and regional) and global cognition. Further, mediation analyses were used to examine whether cortical thinning mediates the relationship between ARTS and global cognition. Models were all adjusted for age, sex, education, vascular risk factors, and scanner site.

Result

Participants had an average age at 80 years (SD = 7) at last MRI scan, and 79% were women. Higher ARTS score was associated with global cortical thinning (estimate = ‐0.14; SE = 0.02, p<0.001), as well as regional cortical thinning in all four lobes (all p’s >0.017). Higher ARTS score was associated with lower global cognition (estimate = ‐0.49; SE = 0.10, p<0.001). In mediation analyses, cortical thinning accounted for 35% of the association between ARTS and global cognition.

Conclusion

In vivo MRI‐derived measures for cerebral arteriolosclerosis are associated with global and lobar cortical thinning. The association between ARTS and cognition is partially mediated by cortical thinning. Findings suggest that cerebral small vessel disease may contribute to neurodegeneration and, both directly and indirectly, to subsequent cognitive impairment.
Amygdala‐predominant α‐synuclein pathology accelerates CA1 neuron loss in Alzheimer’s disease
Authors: Gawor Klara , Tomé Sandra O. , Ospitalieri Simona , Ronisz Alicja , Vandenberghe Rik , Otto Markus , von Arnim Christine , Van Damme Philip , Vandenbulcke Mathieu , Blaschko Matthew , Thal Dietmar Rudolf
Published: January 2025

Background

In 43‐63% of symptomatic Alzheimer’s disease (AD) patients, there is an observed accumulation of misfolded alpha‐synuclein (αSyn). Two primary αSyn subtypes have been identified based on the underlying spreading pattern of this pathology: caudo‐rostral and amygdala‐predominant. Interactions between pathological TDP‐43, Tau, and αSyn can aggravate their spread and aggregation. The amygdala might serve as an incubation hub due to its early involvement in these pathologies. Here, we tested our hypothesis that the amygdala‐predominant αSyn pathology contributes to limbic degeneration, including the hippocampus, and increases the burden of other protein aggregates.

Methods

We conducted a neuropathological analysis of 291 autopsy brains from both demented and non‐demented elderly individuals. Neuronal density in the CA1 region of the hippocampus was quantified from hematoxylin‐stained slides. We semi‐quantitatively evaluated αSyn‐pathology severity in six brain regions, stratifying cases into two spreading patterns. In 99 AD cases, we also assessed limbic‐predominant age‐related TDP‐43 encephalopathy neuropathological changes (LATE‐NC) stages and the proportion of pTau affected neurons in CA1.

Results

We identified an association between amygdala‐predominant αSyn, but not caudo‐rostral, with decreased neuronal density in CA1 (P‐value<0.001). AD patients with amygdala‐predominant patterns showed higher LATE‐NC stages than those without αSyn (adj. P‐value = 0.015), while those with caudo‐rostral patterns had fewer neuritic plaques (adj. P‐value = 0.023) and pTau than pure AD (adj. P‐value = 0.038). Using structural equation modeling, we found that the relationship between αSyn and CA1 cell loss is indirect, mediated through hippocampal pTau and TDP‐43.

Conclusions

Our findings indicate that the amygdala‐specific αSyn pattern, but not the rostro‐caudal one, may indirectly contribute to hippocampal neurodegeneration by enhancing the aggregation and toxicity of TDP‐43 and pTau. Furthermore, our study reveals differences in neuropathological characteristics between AD patients with two spreading patterns. These findings underscore the significance of identifying co‐morbid pathologies in AD patients and the necessity for further research on distinct αSyn subtypes.
Molecular and Synaptic Signatures in Mouse Models of Late‐Onset Alzheimer’s Disease Independent of Amyloid and Tau Pathology
Authors: Oblak Adrian L
Published: January 2025

Background

MODEL‐AD (Model Organism Development and Evaluation for Late‐onset AD) is developing, characterizing, and distributing novel mouse models expressing humanized, clinically relevant genetic risk factors. Models expressing human‐relevant risk genetic risk factors are expected to better phenocopy LOAD than widely used transgenic models.

Method

Here, two genetic risk factors APOE4 and Trem2*R47H, were incorporated into C57BL/6J (B6) mice along with humanized amyloid‐beta to produce the LOAD2 model. LOAD2 and control mice were aged up to 24 months with some being provided in the absence or presence of normal chow or a high fat/high sugar diet (LOAD2 HFD) from two months of age. A phenotyping pipeline was employed to evaluate disease outcomes observed in human patients, including in vivo imaging, brain and blood biomarker and cytokine analyses, multi‐omics (transcriptomics and proteomics), neuropathology and behavior.

Result

By 18 months, unlike control mice (e.g., LOAD2 mice fed a control diet, CD), LOAD2 HFD mice presented subtle but significant loss of neurons in the cortex, elevated levels of insoluble AΒ42 in the brain, and increased plasma neurofilament light chain (NfL). Transcriptomics and proteomics showed changes in gene/proteins relating to a variety of disease‐relevant processes including lipid metabolism and synaptic function. In vivo imaging revealed an age‐dependent reduction in brain region volume (MRI) and neurovascular uncoupling (PET/CT). LOAD2 HFD mice also showed a learning deficit based on a Touchscreen cognitive assay.

Conclusion

Despite the absence of hallmark amyloid and Tau pathologies, collectively these data support the use of LOAD2 HFD mice reveal this model as important for preclinical studies that target other features of LOAD independent of amyloid and tau.
MODEL‐AD Pre‐Clinical Testing Core: A Precision Medicine Pipeline for Preclinical Testing of Alzheimer’s Disease Therapeutic Candidates
Authors: Territo Paul R
Published: January 2025

Background

Preclinical testing in animal models is a critical component of the drug discovery process. Over the past three decades hundreds of interventions have demonstrated preclinical efficacy for ameliorating cognitive impairments in animal models; however, none have translated to efficacy in Alzheimer’s disease (AD) clinical trials. This lack of translation suggests that there are issues with the animal models employed, the preclinical assays, and poor scientific rigor and reproducibility during execution. To overcome these limitations, the Preclinical Testing Core (PTC) of the Model Organism Development and Evaluation for Late‐onset AD (MODEL‐AD) consortium has established a rigorous screening strategy with go/no‐go decision points that permits unbiased assessments of therapeutic agents.

Method

For each compound selected for screening, a mouse model that is best matched to the drugs mechanism of action, and that has been comprehensively characterized by the MODEL‐AD consortium, will be enrolled. An initial screen evaluates drug identity, stability, formulation, pharmacokinetics (PK), and simulations to confirm appreciable brain exposure in the disease model at the pathologically relevant ages. These efforts inform on the dose regimen for long‐term studies, where secondary pharmacodynamics studies (PD) evaluates target engagement utilizing non‐invasive PET/CT and post‐mortem confirmation. Provided the compound meets the “go” criteria for these endpoints, evaluation for behavioral endpoints are conducted as well as post treatment transcriptomic and proteomic analyses.

Result

Validation of this pipeline using both small molecule and biologic tool compounds including the evaluation of verubecestat, levetiracetam, and aducanumab revealed the importance of critical quality control (QC) steps when executing preclinical studies. These include confirmation of the active pharmaceutical ingredient, PK, and PD in well powered studies powered to evaluate effects of sex and conducted according to the ARRIVE guidelines.

Conclusion

Based on our experience executing rigorous screening strategies with QC checkpoints provide insight to the challenges of conducting translational studies in animal models. The PTC pipeline, an NIA resource, is accessible to the research community for investigators to nominate compounds for testing (https://stopadportal.synapse.org/), thus enabling unbiased studies that support clinical translation.
Interactions with regulatory antibodies modulate CHIP E3 ubiquitin ligase‐driven tau clearance
Authors: Unnikrishnan Aparna , Connelly Emily J , Chung Dong hee , Nadel Cory M , Thwin Aye , Craik Charles S , Southworth Daniel
Published: January 2025

Background

The direct and chaperone‐associated interactions of E3 ubiquitin ligase CHIP with tau in Alzheimer’s disease and other tauopathies, regulates tau turnover, by directly linking it to ubiquitination and proteasomal degradation, as well as through suppression of tau aggregation. Modulation of these CHIP‐driven tau clearance mechanisms can be an effective treatment strategy. Antigen‐binding antibody fragments (Fabs) are potent tools that can highly‐selectively engage target proteins and act as functional probes or inhibitors. Development and characterization of Fabs that target unique 3D epitopes on CHIP can help in exploring their therapeutic potential, while enabling structural characterization and providing insights into CHIP‐driven tau clearance mechanisms.

Method

Recombinant Fabs were developed to conformation‐selectively bind CHIP, by bio‐panning and BLI binding assays. They were then functionally screened using SEC‐MALS, ubiquitination activity assay, binding assays, ThT fibrillation assays etc. Selected Fab interactions that potently regulated CHIP‐driven mechanisms were further characterized via Cryo‐EM high‐resolution structural studies.

Result

CHIP‐Fab complexes with distinct 3D binding epitopes and different functional regulatory effects were identified and studied. High‐resolution details of these Fab interaction sites on CHIP were obtained by Cryo‐EM 3D reconstruction and molecular modeling. Fab ‘2F1’ that forms a 2:2 complex with CHIP, potently inhibits its ubiquitination activity by directly blocking the required E2‐CHIP interactions. Fab ‘H1’ that forms both 1:2 and 2:2 complexes with CHIP, significantly improves its tau aggregation suppression and reveals distinct functional conformational states of CHIP. Fab ‘2D2’ forms a 1:2 complex with CHIP, blocks CHIP‐tau interactions and stabilizes the CHIP coiled‐coil domain dimerization interface.

Conclusion

Functional screening of Fabs that were generated to specifically target 3D epitopes on CHIP have revealed potent modes of CHIP functional modulation. Insights from the corresponding CHIP‐Fab complex structures help in better understanding the CHIP‐driven tau clearance mechanisms and in describing unique therapeutic target sites on CHIP.
Pathways of inhibitory interneuron dysregulation in 5XFAD mice
Authors: Chen Kevin S , Noureldein Mohamed , Rigan Diana M , Hayes John M , Savelieff Masha G , Feldman Eva L
Published: January 2025

Background

Inhibitory interneurons normally regulate neural networks underlying memory and cognition, but are disrupted in Alzheimer’s disease. Proper interneuron activity reduces amyloid‐beta, whereas hyperexcitability elevates amyloid levels. Still, the underlying pathologic processes mediating interneuron dysfunction remain unknown. Therefore, we employed a spatial transcriptomics approach to map transcriptomic profiles of interneurons in a temporal and spatial manner.

Method

Coronal hemibrain sections from early stage (12 wks) and late stage (30 wks) male mice (5XFAD) underwent fluorescence in situ hybridization to identify interneuron subtypes (parvalbumin‐expressing, PV+, or somatostatin‐expressing, SST+). Slides were submitted for GeoMx DSP spatial transcriptomics (2 duplicate slides per timepoint, n = 2 5XFAD and n = 2 WT per slide). Regions of interest (ROIs) were defined in hippocampal and cortical regions (Figure 1). UV‐liberated barcodes from each ROI, restricted to PV+ or SST+ interneurons, were collected by microcapillary and sequenced by the NanoString Max/Flex nCounter system. Differentially expressed genes (DEGs) were assessed by linear mixed‐effect model and the GeoMx analysis suite, and attribution to respective time points, cell type, and anatomic region were sequentially parsed.

Result

In early‐stage disease, 1,562 DEGs were uniquely expressed by PV+ interneurons and 2,284 DEGs were uniquely expressed by SST+ interneurons. Similarly, at late‐stage disease, 2,790 DEGs were expressed by PV+ interneurons and 2,346 DEGs were uniquely expressed by SST+ interneurons (Figure 2). Focusing on the CA1 region, previously implicated as having a central role in hippocampal dysfunction, interneurons again showed unique alterations. Early‐stage PV+ interneurons in CA1 uniquely expressed 310 DEGs, with “metabolic pathways” having the most DEGs (Figure 3). By contrast, early‐stage SST+ interneurons in CA1 uniquely expressed 422 DEGs, enriched in pathways canonically linked to “amyotrophic lateral sclerosis” and “Alzheimer disease.”

Conclusion

The most significant altered pathways within AD interneurons at the earliest stages of disease included neurodegeneration and metabolism pathways. Zero or few DEGs overlapped across all regions or neuronal subtypes. Thus, interneurons display distinct profiles and transcriptional changes by brain area at early‐ and late‐stage disease. These findings will inform future mechanistic experimentation, and suggest investigation into neural circuit dysfunction in AD will require consideration of anatomic subregion specificity.
Early molecular events of Autosomal Dominant Alzheimer’s Disease in marmosets with PSEN1 mutations
Authors: Bailey Lauren , Homanics Gregg E , Park Jung Eun , Schaeffer David J , Schaeffer Lauren K Hayrynen , Zhang Ting , Haber Annat , Spruce Catrina , Greenwood Anna , Murai Takeshi , Schultz Laura , Mongeau Lauren , Ha Seung‐Kwon , Oluoch Julia , Stein Brianne , Choi Sang‐Ho , Huhe Hasi , Thathiah Amantha , Strick Peter L , Carter Gregory W , Silva Afonso C , Rizzo Stacey J Sukoff
Published: January 2025

Background

Fundamental questions remain about the key mechanisms that initiate Alzheimer’s disease (AD) and the factors that promote its progression. Here we report the successful generation of the first genetically‐engineered marmosets that carry knock‐in (KI) point mutations in the presenilin‐1 (PSEN1) gene that can be studied from birth throughout lifespan.

Method

CRISPR/Cas9 was used to generate marmosets with C410Y or A426P point mutations in PSEN1. Founders and their germline offspring are comprehensively studied longitudinally using non‐invasive measures including behavior, biomarkers, neuroimaging, and multi‐omics signatures.

Result

Prior to adulthood, increases in plasma Aβ were observed in PSEN1 mutation carriers relative to non‐carriers. Analysis of brain revealed alterations in several enzyme‐substrate interactions within the gamma secretase complex prior to adulthood.

Conclusion

Marmosets carrying KI point mutations in PSEN1 provide the opportunity to study the earliest primate‐specific mechanisms that contribute to the molecular and cellular root causes of AD onset and progression.
Key role of ERβ in estrogenic regulation of neuronal mitochondrial function
Authors: Wang Tian , Mao Zisu , Chen Shuhua , Shang Yuan , McLean John W. , Stanton James Brett , Qi Guoyuan , Yin Fei , Brinton Roberta Diaz
Published: January 2025

Background

Estrogen is a master regulator of the bioenergetic system in the female brain, exerting broad control over metabolic processes from glucose transport to glycolysis, mitochondrial respiration, and ATP generation. The loss of estrogen during the perimenopausal transition is associated with decline in brain glucose metabolism and mitochondrial function which can contribute to the two‐fold greater lifetime risk of Alzheimer’s disease in postmenopausal women. While both ERα and ERβ have been reported to mediate E2 regulation of brain bioenergetic function, their cell‐type specific contribution to bioenergetic homeostasis has yet to be elucidated.

Method

Herein, we investigated the role of ERα and ERβ in E2 regulation of neuronal bioenergetics. We developed novel conditional estrogen receptor α and β knock‐down rat models by inserting two loxP sites upstream and downstream of exon 3 of Esr1 or Esr2 allele using Crispr/Cas9‐mediated genome engineering technique. Our novel ERαlox and ERβlox rat models enable inducible and brain cell‐type and region specific ERα and ERβ knockdown without disrupting normal development of estrogen dependent organs and systems. Using these models, ERα and ERβ dependent regulation on neuronal mitochondrial function was investigated in vivo and in vitro. Further, unbiased transcriptomic analysis was conducted to delineate ERα and ERβ specific signaling pathways modulating neuronal bioenergetic function.

Result

ERβ significantly regulated E2 activation of neuronal mitochondrial oxidative phosphorylation in vivo. Selective knockdown of neuronal ERβ resulted in significant decrease in hippocampal mitochondrial respiration and impaired OXPHOS complex activity. In contrast, ERα knockdown did not impact hippocampal mitochondrial respiration nor mitochondrial OXPHOS complex activity. These results were confirmed in primary embryonic ERα and ERβ knockdown neurons. Mechanistic investigation further revealed ERβ dependent transcriptomic regulation of TCA and OXPHOS genes. Importantly, ERβ knockdown resulted in increased UCP2 expression and decreased AKT and ERK signaling, leading to increased proton leak and decreased mitochondrial respiration.

Conclusion

ERβ exerts a pivotal role in maintaining neuronal mitochondrial function and bioenergetic homeostasis in female brain. Selectively activating ERβ could provide a precision medicine strategy to promote brain function in menopausal women while inhibiting breast tissue proliferation.
Caregiver, Parent with At‐Risk Children
Authors: Steel Tanya
Published: January 2025

My beloved husband, Robert Steel, died at 58 from MAPT FTD, a disease that stretches back through his family’s generations. Before we married he told me his father died of early‐onset Alzheimers and he was terrified he would inherit that disease. In his early 50s he began exhihibiting symptoms that I attributed to stress–his work as a respected high school teacher began to slip, he began to lose the ability to have a visual map in his head, he began to repeat stories, his behavior became more compulsive, forgot how he was related to a favorite cousin. He had to leave the teaching profession and I had to support our family, with my identical twins soon headed to college.

I took him to a reputed neurologist who said perhaps he was depressed. This diagnosis was repeated with other dementia specialists. One day he got into a car accident and left the scene, something that was the opposite of his character. From that day he seemed in a fog and almost unreachable. It was then that I got him diagnosed by Columbia Presbyterian’s Dr. Karen Marder, an FTD specialist. His Behavorial Variant FTD caused by the MAPT gene has likely affected many generations before him, many of whom died fairly young and often of mysterious circumstances.

Since that time, I have led a support group for AFTD, begun a book for caregivers of dementia patients, and become a founding member of Cure MAPT FTD. With my three decades of experience on television, panels, public speaking including four speeches at The White House with Mrs. Michelle Obama alongside, I am committed to using my communication skills to help cure this insidious disease. I will speak from the caregiver’s vantage point, discussing the difficulty FTD specifically presents for caregivers and patients–from finances to safety–what clinicians can do to better support both constituents, the frustration in the lack of MAPT‐specific trials, the importance in spreading awareness to thus help others gain quicker diagnosis, and the decision to not yet test my sons.
The loss‐of‐function variant in MFSD3 could play a crucial role in the pathogenesis of dementia with Lewy bodies
Authors: Kimura Tetsuaki , Suganuma Mutsumi , Sawamura Kayoko , Asanomi Yuya , Shimoda Nobuyoshi , Ogiso Noboru , Hosoyama Tohru , Niida Shumpei , Ozaki Kouichi , Shigemizu Daichi
Published: January 2025

Background

Dementia with Lewy bodies (DLB) is the second most common form of degenerative dementia in older people. The clinical feature of DLB includes cognitive impairment, visual hallucinations, parkinsonism, and fluctuating attention. Three genes, SNCA (‐synuclein), APOE (apolipoprotein E), and GBA (glucosylceramidase), have been convincingly demonstrated to be associated with DLB. Our previous studies reported that a variant in MFSD3 (rs143475431, c.888T>A:p.C296*) is associated with DLB in the Japanese population through whole‐genome sequencing and association studies. However, the precise mechanisms that this variant contributes to DLB development remains unclear.

Method

We introduced the MFSD3 p.C296* variant into a human neural stem cell line using the CRISPR/Cas9 system. Subsequently, the mutant cells were analyzed for cell proliferation rate using CyQUANT Cell Proliferation Assay Kit. The mutant cells were further induced to differentiate into neurons and astrocytes to assess their differentiation ability. Additionally, we generated the homologous Mfsd3 knockout (KO) mice using the CRISPR/Cas9 system. The neurogenesis was evaluated by the number of doublecortin positive cells in the hippocampus. The behavior of Mfsd3 KO and wild‐type mice was analyzed using IntelliCage.

Result

We revealed that the MFSD3 p.C296* variant was associated with decreased cell proliferation and reduced neurogenesis in the human neural stem cell line analyses. This decline in neurogenesis was also observed in the hippocampal dentate gyrus of Mfsd3 KO mice, and the Mfsd3 KO mice had smaller hippocampi compared to the wild‐type mice. Furthermore, Mfsd3 KO mice exhibited a reduced level of curiosity about the new environment.

Conclusion

Our results demonstrate that loss of function of MFSD3 affects neurons and the brain, as indicated by our studies using human neural stem cell lines and Mfsd3 KO mice. Further functional verification will contribute to elucidating the mechanism of DLB pathogenesis.
Neuropsychiatric Symptom Profile in Alzheimer’s Disease and Their Effects on Functional Decline
Authors: Zhu Carolyn W. , Schneider Lon S. S. , Aloysi Amy , Elder Gregory , Grossman Hillel , Neugroschl Judith A. , Schimming Corbett , Soleimani Laili , Sano Mary
Published: January 2025

Background

Neuropsychiatric symptoms (NPS) are core features of Alzheimer’s disease (AD) and have significant impact on patients, caregivers, and families. Worse NPS scores are associated with worse function and higher need for care. It is unclear if individual NPS symptoms may differentially affect functional decline and may be more effectively targeted to improve patient outcomes.

Method

Data are drawn from participants enrolled in the National Alzheimer’s Coordinating Center Uniform Data Set (9/2005‐11/2022). Participants were diagnosed with Mild Cognitive Impairment or AD at baseline, had a primary etiologic diagnosis of AD, and had at least one annual follow‐up visit (average follow‐up = 4 years). Participants’ function was measured using the Functional Assessment Questionnaire (FAQ). NPS were reported by ADC study clinicians using the “Clinician Judgment of Symptoms” (Form B9) evaluating whether each of the following symptoms manifested as a meaningful change in behavior (yes = 1, no = 0): apathy‐withdrawal, depressed mood, visual or auditory hallucinations, delusions, disinhibition, irritability, agitation, and anxiety. Dementia severity was measured using the CDR. Multivariable analyses of the effects of each NPS on decline in function were performed using linear mixed models. Covariates included baseline age, gender, race/ethnicity, education, referral source, number of visits, comorbidities, APOE genotype, and number of medications.

Result

Baseline sample characteristics (N = 9,358): mean age = 74±9, 47% male, 78% non‐Hispanic white, 11% black, 8% Hispanic, education = 15±4; 52% CDR = 0.5, 35% CDR = 1, and 13% CDR≥2; FAQ = 12±9. Baseline presence of NPS: apathy (34%), depressed mood (33%), anxiety (31%), irritability (28%), agitation (13%), disinhibition (10%), delusions (9%), and hallucinations (5%). Apathy was the most persistent of NPS with 37% of all participants had clinician endorsed apathy in ≥50% all of their visits, followed by depressed mood (28%), irritability (27%), anxiety (21%), agitation (14%), disinhibition (11%), delusions (9%), and hallucinations (5%). Functional decline was faster in those with persistent (≥50% of all visits) apathy, agitation, and delusions.

Conclusion

Different behavioral symptoms have differential effects on functional decline, a major driver of caregiver stress and institutionalization. Better understanding of these differential effects on function is crucial in designing trials for treatment in AD. Assessing for these behavioral symptoms should be a standard component of cognitive evaluations.