Citations

AbstractBackgroundCerebral small vessel disease (cSVD), as defined by neuroimaging characteristics such as white matter hyperintensities (WMHs), cerebral microhemorrhages (CMHs), and lacunar infarcts, is highly prevalent and has been associated with dementia risk and other clinical sequelae. Although risk factors for cSVD have been identified, little is known about the biological processes and molecular mediators that influence cSVD development and progression.MethodsWithin the Atherosclerosis Risk in Communities (ARIC) study, we used SomaScan Multiplexed Proteomic technology to relate 4,877 plasma proteins to concurrently measured MRI‐defined cSVD characteristics, including WMHs, CMHs, and lacunar infarcts, in late‐life (n=1508; mean age: 76). Candidate protein associations with WMH volume were replicated in the Cardiovascular Health Study (n=765; mean age: 73) and Baltimore Longitudinal Study of Aging (n=902; mean age: 66). Cohort‐specific effect estimates were pooled using a fixed‐effect, inverse variance weighted meta‐analysis. Within 4228 non‐demented older adults in ARIC, we examined the association of WMH‐associated proteins with eight‐year dementia risk (641 incident dementia cases) using multivariate Cox proportional hazard models. All multivariate regression models were adjusted for demographic, kidney function, and cardiovascular risk variables.ResultsThis proteome‐wide analysis of older adults identified 13 WMH‐associated plasma proteins involved in synaptic function, endothelial integrity, and angiogenesis (Figures 1a, 2a). Nine of these proteins replicated in one or more external cohort (Figures 1b, 2b) and two proteins, oligodendrocyte myelin glycoprotein (OMG) and neuronal pentraxin receptor (NPTXR), remained associated with late‐life WMH volume when measured nearly two decades earlier during midlife (Figures 1c, 2c). Eight of the 13 WMH‐associated proteins were associated with lacunar infarcts, 6 with subcortical CMHs, and 4 with lobar CMHs (Figures 1d, 2d). Although none of the genes coding for WMH‐associated proteins have been nominated by WMH GWAS, 7 of these genes have been previously linked to cardiometabolic traits known to influence cSVD, such as blood pressure and cholesterol (Figures 1e, 2e). Finally, 11 candidate proteins were associated with incident dementia, underscoring their clinical relevance (Figures 1f, 2f).ConclusionsThis large‐scale proteomic analysis within longitudinal community‐based samples identified several plasma proteins, including OMG and NPTXR, as top candidate biomarkers for elevated WMH volume and its clinical manifestations.

AbstractBackgroundNeuron‐derived extracellular vesicles (NDEVs) are a valuable resource for understanding brain conditions and discovering neurodegenerative diseases biomarkers, notably Alzheimer’s disease (AD). Recent interest focuses on capturing neuron‐specific EVs from patient‐derived samples, characterizing their contents as a pathological reflection of the central nervous system (CNS). Our recent study identified ATPase Na+/K+ Transporting Subunit Alpha 3 (ATP1A3) as a prevalent neuron‐specific EV marker specifically expressed in brains. This study systematically analyzes neuronal EVs to assess the specificity of ATP1A3 to NDEVs and its potential as a target for NDEV pulldown from accessible biofluids for disease monitoring. Additionally, ATP1A3 is compared with other proposed NDEV markers.MethodWe applied immunoelectron microscopy to detect ATP1A3, L1 cell adhesion molecule (L1CAM) and neural cell adhesion molecule 1 (NCAM1) in EVs isolated from iPSC‐derived excitatory neurons, brain tissue, cerebrospinal fluid (CSF) and plasma. Neuronal EV enrichment was achieved through immunoaffinity isolation, utilizing anti‐ATP1A3, L1CAM and NCAM1 antibodies separately. Evaluation involved quantitative mass‐spectrometry, immunoblotting and ELISA. To compare the enrichment of neuronal markers, EVs isolated from CSF and plasma samples were analyzed using ExoView and Nanoimager. Additionally, we investigated the potential of ATP1A3+ plasma EVs as AD biomarker by comparing the value of amyloid‐beta peptide (Aβ) in ATP1A3+ plasma EVs measured by Nanoimager and other plasma AD biomarkers as determined by SIMOA.ResultATP1A3, identified as a neuron‐specific protein, exhibits substantial enrichment in NDEVs isolated from induced human neurons, brain tissue, CSF, and plasma samples, surpassing NCAM1 or L1CAM. Both single‐ and bulk‐EV analysis consistently demonstrate a higher enrichment of ATP1A3 associated EVs in human samples. Immunoprecipitation of ATP1A3+ EVs from human brain tissues reveals superior neuronal cell‐type specificity over NCAM1+ and L1CAM+ EVs by label‐free mass spectrometry. Increased Aβ levels are observed in ATP1A3+ EVs derived from CSF and plasma of AD cases by SIMOA. Moreover, Aβ+ populations in ATP1A3+ EVs from plasma can distinguish AD from mild cognitive impairment and control cases via Nanoimager compared to the conventional quantification of AD markers.ConclusionOur findings demonstrate that ATP1A3 as a promising target for isolating NDEVs from biofluids, offering potential diagnostic advancements in neurological research.

AbstractBackgroundScalable, efficient methods are needed to enroll diverse populations of older adults into AD observational studies and clinical trials. We evaluated preliminary feasibility of a novel, digital, culturally informed approach to recruit and screen participants for the Alzheimer’s Disease Neuroimaging Initiative (ADNI4).MethodsDigital advertising tailored towards Black/African American and Latinx older adults residing near six clinical ADNI sites directed potential participants to a recruitment website (Figure 1). They completed digital surveys of demographics, ADNI exclusion criteria, memory concerns and changes, self‐report cognitive impairment, and the Everyday Cognition Scale (ECog)‐12 item. Participants also completed Novoic Storyteller, a self‐administered speech‐based cognitive test. Digital assessment results were used to prioritize those from minoritized ethnocultural groups, with low educational attainment, and possible Mild Cognitive Impairment (MCI) for remote blood draw at local Quest phlebotomy centers to obtain AD plasma biomarkers. Completion rates and digital assessment performance were compared between minoritized and non‐minoritized groups.ResultsOf 989 participants recruited from digital advertising efforts who provided contact information, 230 (23%) signed consent, and 183 (19%) completed at least one remote assessment (Table 1). 45% were from minoritized ethnocultural groups, 4% had ≤12 years of education, and 53% had evidence of possible MCI from digital assessments. 34 (19%) were referred to the plasma biomarker study, of which 21% completed blood draw. Compared to non‐minoritized participants, minoritized participants were less likely to report a diagnosed cognitive impairment or a family history of AD, less likely to have ECog scores indicative of MCI, and less likely to have a study partner. Minoritized participants had lower ECog and Novoic Storyteller completion rates.ConclusionRecruitment and assessment of a diverse cohort of older adults, including those with possible cognitive impairment, is feasible using culturally informed digital advertising. Improving study engagement and achieving educational diversity are key challenges. This approach is now being scaled up to facilitate recruitment into in‐clinic ADNI4, with the goal of enrolling 500 new participants: >50% from minoritized groups, 40% with MCI, and 80% amyloid positive across diagnostic groups. This approach can be adapted to facilitate recruitment and longitudinal assessment in other AD studies and trials.

Periprosthetic joint infection (PJI) is a devastating complication of total joint surgery. Surgical management of PJI has increased surgical risks and is costly to the healthcare system. This case study presents a unique clinical scenario involving a patient who was diagnosed with Lyme PJI at the total knee arthroplasty site after undergoing surgical management. Lyme PJI is a rare condition, and there is limited guidance on the diagnosis and management of this condition. It should be considered in the differential of certain individuals with appropriate epidemiological risk factors. This report aims to highlight the complexities associated with the diagnosis and management of periprosthetic Lyme infections.

Importance Monoclonal antibodies (mAbs) targeting calcitonin gene-related peptide (CGRP) or its receptor (anti-CGRP mAbs) offer effective migraine-specific preventive treatment. However, concerns exist about their potential cardiovascular risks due to CGRP blockade. Objective To compare the incidence of cardiovascular disease (CVD) between Medicare beneficiaries with migraine who initiated anti-CGRP-mAbs vs onabotulinumtoxinA in the US. Design, Setting, and Participants This retrospective, sequential cohort study was conducted among a nationally representative population-based sample of Medicare claims from May 2018 through December 2020. Data analysis was performed from August to December 2023. This study included fee-for-service Medicare beneficiaries aged 18 years or older with migraine who initiated either anti-CGRP mAbs or onabotulinumtoxinA. Beneficiaries who had a history of myocardial infarction (MI), stroke, cluster headache, malignant cancer, or hospice service within a 1-year baseline period prior to treatment initiation were excluded. To minimize channeling bias from new drug introductions and time-related bias due to the COVID-19 pandemic, 5 cohorts were established, representing sequential 6-month calendar intervals based on the initial prescription or date of index anti-CGRP mAbs or onabotulinumtoxinA use. Exposure Anti-CGRP mAbs vs onabotulinumtoxinA. Main Outcomes and Measures The primary outcome was time to first MI or stroke. Secondary outcomes included hypertensive crisis, peripheral revascularization, and Raynaud phenomenon. The inverse probability of treatment-weighted Cox proportional hazards models were used to compare outcomes between the 2 treatment groups. Results Among 266 848 eligible patients with migraine, 5153 patients initiated anti-CGRP mAbs (mean [SD] age, 57.8 [14.0] years; 4308 female patients [83.6%]) and 4000 patients initiated onabotulinumtoxinA (mean [SD] age, 61.9 [13.7] years; 3353 female patients [83.8%]). Use of anti-CGRP mAbs was not associated with an increased risk of composite CVD events (adjusted hazard ratio [aHR], 0.88; 95% CI, 0.44-1.77), hypertensive crisis (aHR, 0.46; 95% CI, 0.14-1.55), peripheral revascularization (aHR, 1.50; 95% CI, 0.48-4.73), or Raynaud phenomenon (aHR, 0.75; 95% CI, 0.45-1.24) compared with onabotulinumtoxinA. Subgroup analyses by age group and presence of established non-MI or stroke CVD showed similar findings. Conclusions and Relevance In this cohort study, despite initial concerns regarding the cardiovascular effects of CGRP blockade, anti-CGRP mAbs were not associated with an increased risk of CVD compared with onabotulinumtoxinA among adult Medicare beneficiaries with migraine, who were predominantly older adults or individuals with disability. Future studies with longer follow-up periods and in other populations are needed to confirm these findings.

AbstractBackgroundAlzheimer’s disease (AD) missing heritability remains extensive despite numerous genetic risk loci identified by genome‐wide association or sequencing studies. This has been attributed, at least partially, to mechanisms not currently investigated by traditional single‐marker/gene approaches. Polygenic Risk Scores (PRS) aggregate sparse genetic information across the genome to identify individual genetic risk profiles for disease prediction and patient risk stratification. Recent advancements have pivoted on innovative approaches utilizing OMICS data to construct such risk scores.MethodWe employed a random forest algorithm to identify a list of gene candidates from bulk RNA sequencing data in prefrontal cortex from 565 AD brain samples (non‐Hispanic Whites, n = 399; Hispanics, n = 113; African American, n = 12) across six U.S. brain banks. Subsequently, we calculated their effect size on Braak staging using regression models to construct a polytranscriptomic risk score (PTRS). We employed two distinct models: “Ethnicity‐Agnostic” Model (randomly assigning samples to training and testing samples) and “Ethnicity‐Aware” Model (assigning NHW samples to training and Hispanics to testing sample). Analysis of variance and the receiver operating characteristics area under the curve (ROC AUC) was used to evaluate PTRS’s classification performances. We validated findings using the Religious Orders Study/Memory and Aging Project study (ROS/MAP, n = 1,095).ResultWe found a significant difference in PTRS between samples with low vs. high Braak stages (≤4 vs. ≥5, p = 1*E‐04; Figure 1 upper panel). AUC was found to be 79‐81%, consistently in both Ethnicity‐Agnostic and Ethnicity‐Aware models (Figure 1 lower panel). Finally, the PTRS in ROS/MAP yielded a similar classification performance (p = 2*E‐04, AUC = 77%).Conclusioncontrary to prior studies, we developed a PTRS with optimal transferability across ethnicities. This underscores the importance of developing novel tools to stratify and harmonize large brain repositories for AD.

AbstractBackgroundTauopathies are a group of neurodegenerative disorders which are characterized by the accumulation of abnormal tau protein in the brain. However, the mechanistic understanding of pathogenic tau formation and spread within the brain remains elusive. Astrocytes are major immune reactive cells in the brain and have been implicated in exacerbating tau pathology by releasing extracellular vesicles (AEVs) containing pro‐inflammatory cytokines and chemokines upon activation. Our prior investigation revealed a significant association between AEVs and tau pathology development, as well as cognitive function, by analyzing brain‐derived EV proteins from AD patients. In this study, we explore the potential roles of AEVs in tau pathogenesis using a human induced pluripotent stem cell (iPSC) model.MethodWe obtained two male P301L tau mutant iPSC lines from a Polish family with frontotemporal dementia. By including two male control lines, these iPSCs were differentiated into astrocytes (iAs) and characterized by immunocytochemistry and subjected for bulk RNAseq. Bioinformatics analysis was conducted to compare the transcriptome profile between wild‐type (WT) and P301L iAs. EVs from WT and P301L iAs were isolated by ultracentrifugation combined with size exclusion chromatography. Characterization of WT and P301L iAEVs involved nanoparticle tracking analysis, nano‐flow cytometry and super‐resolution microscopy.ResultWe successfully differentiated WT and P301L mutant iPSC lines into astrocytes with >99% purity. P301L iAs displayed distinctive astrocyte reactivity compared to WT cells, with elevated levels of pan‐reactive astrocyte genes (e.g., GFAP, CD44) and decreased expression of neuroprotective A2 astrocyte‐specific genes (e.g., TM4SF1, PTGS2). Additionally, gene enrichment set analysis of RNAseq data revealed dysregulation in the endo‐lysosomal pathway and extracellular matrix in P301L iAs compared to WT iAs. The count of intraluminal vesicles marked by CD9+ were reduced in P301L iAs compared to WT cells. Moreover, we observed a significant increase in the internalization of Tau by P301L iAs compared to WT iAs following incubation with preformed Tau fibrils, resulting in an augmented release of tau‐containing EVs from P301L iAs.ConclusionOur findings suggest a potential alteration in EV biogenesis in P301L iAs, potentially contributing to astrocyte‐mediated tau pathology. Future investigations will focus on understanding how AEVs contribute to tau propagation and accumulation.

AbstractBackgroundAlzheimer’s Disease (AD) presents complex molecular heterogeneity, influenced by a variety of factors including heterogeneous phenotypic, genetic, and neuropathologic presentations. Regulation of gene expression mechanisms is a primary interest of investigations aiming to uncover the underlying disease mechanisms and progression.MethodWe generated bulk RNA‐sequencing in prefrontal cortex from 565 AD brain samples (non‐Hispanic Whites, n = 399; Hispanics, n = 113; African American, n = 12) across six U.S. brain banks, and conducted differential gene expression and enrichment analyses. We sought to identify cross‐ancestry and ancestry‐specific differentially expressed genes (DEG) and pathways across Braak stages, adjusting for sex, age at death, and RNA quality metrics. We validated our findings using the Religious Orders Study/Memory and Aging Project study (ROS/MAP, n = 1,095). Lastly, we validated top DEG using publically‐available human single‐nucleus RNA sequencing (snRNAseq) data.ResultAD‐known genes VGF (LFC = ‐0.661, padj = 3.78) and ADAMTS2 (padj = 1.21) were consistently differentially expressed across statistical models, ethnic groups, and replicated in ROS/MAP (Figure 1). Genes from the heat shock protein (HSP) family, e.g. HSPB7 (padj = 3.78), were the top DEG, also replicated in ROS/MAP. Ethnic‐stratified analyses prioritized TNFSF14 and SPOCD1 as top DEG in Hispanic samples. Gene set enrichment analysis highlighted several significantly pathways, including “TYROBP causal network in microglia” (WP3945; padj = 1.68) and “Alzheimer Disease” (WP5124; padj = 4.24). snRNAseq validated several DEG, including VGF downregulated in neurons (padj = 1.1).ConclusionTo our knowledge, this is the largest diverse transcriptome study for AD in post‐mortem tissue. We identified perturbated genes and pathways resulting in cross‐ethnic and ethnic‐specific findings, ultimately highlighting the importance of diversity in AD investigations.