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Sphingolipids are an essential subset of bioactive lipids found in most eukaryotic cells that contribute to membrane biophysical properties and are involved in cellular differentiation, recognition, and mediating interactions. The described nanoHPLC-ESI-Q/ToF methodology utilizes known biosynthetic pathways, accurate mass detection, optimized collision-induced disassociation, and a robust nanoflow chromatographic separation for the analysis of intact sphingolipids found in human tissue, cells, and serum. The methodology was developed and validated with an emphasis on addressing the common issues experienced in profiling these amphipathic lipids, which are part of the glycocalyx and lipidome. The high sensitivity obtained using nanorange flow rates with robust chromatographic reproducibility over a wide range of concentrations and injection volumes results in confident identifications for profiling these low-abundant biomolecules.

Genetic variants and epigenetic features both contribute to the risk of Alzheimer's disease (AD). We studied the AD association of CpG-related single nucleotide polymorphisms (CGS), which act as a hub of both the genetic and epigenetic effects, in Caribbean Hispanics (CH) and generalized the findings to Non-Hispanic Whites (NHW). First, we conducted a genome-wide, sliding-window-based association with AD, in 7,155 CH and 1,283 NHW participants. Next, using data from the dorsolateral prefrontal cortex in 179 CH brains, we tested the cis- and trans-effects of AD-associated CGS on brain DNA methylation to mRNA expression. For the genes with significant cis- and trans-effects, we investigated their enriched pathways. We identified six genetic loci in CH with CGS dosage associated with AD at genome-wide significance levels: ADAM20 (Score = 55.19, P = 4.06 × 10-8), the intergenic region between VRTN and SYNDIG1L (Score = - 37.67, P = 2.25 × 10-9), SPG7 (16q24.3) (Score = 40.51, P = 2.23 × 10-8), PVRL2 (Score = 125.86, P = 1.64 × 10-9), TOMM40 (Score = - 18.58, P = 4.61 × 10-8), and APOE (Score = 75.12, P = 7.26 × 10-26). CGSes in PVRL2 and APOE were also significant in NHW. Except for ADAM20, CGSes in the other five loci were associated with CH brain methylation levels (mQTLs) and CGSes in SPG7, PVRL2, and APOE were also mQTLs in NHW. Except for SYNDIG1L (P = 0.08), brain methylation levels in the other five loci affected downstream mRNA expression in CH (P

Accurate and scalable quantification of amyloid-β (Aβ) pathology is crucial for deeper disease phenotyping and furthering research in Alzheimer Disease (AD). This multidisciplinary study addresses the current limitations on neuropathology by leveraging a machine learning (ML) pipeline to perform a granular quantification of Aβ deposits and assess their distribution in the temporal lobe. Utilizing 131 whole-slide-images from consecutive autopsied cases at the University of California Davis Alzheimer Disease Research Center, our objectives were threefold: (1) Validate an automatic workflow for Aβ deposit quantification in white matter (WM) and gray matter (GM); (2) define the distributions of different Aβ deposit types in GM and WM, and (3) investigate correlates of Aβ deposits with dementia status and the presence of mixed pathology. Our methodology highlights the robustness and efficacy of the ML pipeline, demonstrating proficiency akin to experts' evaluations. We provide comprehensive insights into the quantification and distribution of Aβ deposits in the temporal GM and WM revealing a progressive increase in tandem with the severity of established diagnostic criteria (NIA-AA). We also present correlations of Aβ load with clinical diagnosis as well as presence/absence of mixed pathology. This study introduces a reproducible workflow, showcasing the practical use of ML approaches in the field of neuropathology, and use of the output data for correlative analyses. Acknowledging limitations, such as potential biases in the ML model and current ML classifications, we propose avenues for future research to refine and expand the methodology. We hope to contribute to the broader landscape of neuropathology advancements, ML applications, and precision medicine, paving the way for deep phenotyping of AD brain cases and establishing a foundation for further advancements in neuropathological research.

IntroductionThe role of lipopolysaccharide binding protein (LBP), an inflammation marker of bacterial translocation from the gastrointestinal tract, in Alzheimer's disease (AD) is not clearly understood.MethodsIn this study the concentrations of LBP were measured in n = 79 individuals: 20 apolipoprotein E (APOE)3/E3 carriers with and 20 without AD dementia, and 19 APOE3/E4 carriers with and 20 without AD dementia. LBP was found to be enriched in the 1.21-1.25 g/mL density fraction of plasma, which has previously been shown to be enriched in intestinally derived high-density lipoproteins (HDL). LBP concentrations were measured by ELISA.ResultsLBP was significantly increased within the 1.21-1.25 g/mL density fraction of plasma in APOE3/E3 AD patients compared to controls, but not APOE3/E4 patients. LBP was positively correlated with Clinical Dementia Rating (CDR) and exhibited an inverse relationship with Verbal Memory Score (VMS).DiscussionThese results underscore the potential contribution of gut permeability to bacterial toxins, measured as LBP, as an inflammatory mediator in the development of AD, particularly in individuals with the APOE3/E3 genotype, who are genetically at 4-12-fold lower risk of AD than individuals who express APOE4.

Cerebrovascular and α-synuclein pathologies are frequently observed alongside Alzheimer disease (AD). The heterogeneity of AD necessitates comprehensive approaches to postmortem studies, including the representation of historically underrepresented ethnic groups. In this cohort study, we evaluated small vessel disease pathologies and α-synuclein deposits among Hispanic decedents (HD, n = 92) and non-Hispanic White decedents (NHWD, n = 184) from three Alzheimer's Disease Research Centers: Columbia University, University of California San Diego, and University of California Davis. The study included cases with a pathological diagnosis of Intermediate/High AD based on the National Institute on Aging- Alzheimer's Association (NIA-AA) and/or NIA-Reagan criteria. A 2:1 random comparison sample of NHWD was frequency-balanced and matched with HD by age and sex. An expert blinded to demographics and center origin evaluated arteriolosclerosis, cerebral amyloid angiopathy (CAA), and Lewy bodies/Lewy neurites (LBs/LNs) with a semi-quantitative approach using established criteria. There were many similarities and a few differences among groups. HD showed more severe Vonsattel grading of CAA in the cerebellum (p = 0.04), higher CAA density in the posterior hippocampus and cerebellum (ps = 0.01), and increased LBs/LNs density in the frontal (p = 0.01) and temporal cortices (p = 0.03), as determined by Wilcoxon's test. Ordinal logistic regression adjusting for age, sex, and center confirmed these findings except for LBs/LNs in the temporal cortex. Results indicate HD with AD exhibit greater CAA and α-synuclein burdens in select neuroanatomic regions when compared to age- and sex-matched NHWD with AD. These findings aid in the generalizability of concurrent arteriolosclerosis, CAA, and LBs/LNs topography and severity within the setting of pathologically confirmed AD, particularly in persons of Hispanic descent, showing many similarities and a few differences to those of NHW descent and providing insights into precision medicine approaches.

The Ketogenic Diet (KD) improves memory and longevity in aged C57BL/6 mice. We tested 7 months KD vs. control diet (CD) in the mouse Alzheimer's Disease (AD) model APP/PS1. KD significantly rescued Long-Term-Potentiation (LTP) to wild-type levels, not by changing Amyloid-β (Aβ) levels. KD's 'main actor' is thought to be Beta-Hydroxy-butyrate (BHB) whose levels rose significantly in KD vs. CD mice, and BHB itself significantly rescued LTP in APP/PS1 hippocampi. KD's 6 most significant pathways induced in brains by RNAseq all related to Synaptic Plasticity. KD induced significant increases in synaptic plasticity enzymes p-ERK and p-CREB in both sexes, and of brain-derived neurotrophic factor (BDNF) in APP/PS1 females. We suggest KD rescues LTP through BHB's enhancement of synaptic plasticity. LTP falls in Mild-Cognitive Impairment (MCI) of human AD. KD and BHB, because they are an approved diet and supplement respectively, may be most therapeutically and translationally relevant to the MCI phase of Alzheimer's Disease.

Abstract: Background: Neuropathology studies of the oldest‐old have significantly advanced our understanding of the multiple etiologies late in very late life. Most studies, however, have limited ethnoracial diversity with almost exclusively White decedents. Our goal was to characterize neuropathology in a cohort of ethnically and racially diverse oldest‐old decedents. Method: The LifeAfter90 study is an ongoing cohort study of Kaiser Permanente Northern California members, aged 90+ with targeted recruitment of individuals across different racial/ethnic groups with no prior diagnosis of dementia in their medical record. Interviews and cognitive assessments occur approximately every 6 months. Brain donation was available to all interested consenting participants. Neuropathology was assessed using the National Alzheimer’s Coordinating Center Neuropathology form v.10 and used NIA‐AA guidelines for Alzheimer’s diagnoses. As of January 2023, 304 participants (40%) were enrolled in autopsy (20% Asian, 18% African American, 17% Latino, 9% Multiracial/Other, and 36% White). Result: Of the 304 participants, 59 had died and neuropathological evaluations were completed. The median age of death was 93 years (range 90‐105), 33 (56%) were female, 8 Asian, 5 Black, 10 Latino, 31 White, and 5 Multiracial/Other. At final clinical exam, 17 participants had dementia (29%), 25 questionable/mild cognitive impairment (42%), and 16 were cognitively normal (27%). Alzheimer disease (AD) and vascular pathologies were the most frequent findings (Figure). Twenty two percent of participants did not have AD, one lacked neurofibrillary tangles (NFT). The most severe distributions/densities of NFTs and plaques were infrequent, with high likelihood of AD in two participants. For vascular pathologies, 98% had some level of arteriolosclerosis, 97% had atherosclerosis, 70% had amyloid angiopathy, and 26% had at least one old microinfarct. Other pathologies were less common: 27% had Lewy bodies, 18% had TDP‐43 deposits, and only one had Hippocampal sclerosis. Although data is sparse to test for associations, the proportion of individuals with dementia tended to increase with increasing pathology severity especially for AD pathologies. Conclusion: This diverse cohort of oldest‐old individuals reveal numerous brain pathologies are present with advanced age, with AD and select vascular pathologies being the most common. Future analyses will investigate their role with cognitive impairment.

Limbic-predominant age-related TDP-43 encephalopathy (LATE) affects approximately one-third of older individuals and is associated with cognitive impairment. However, there is a highly incomplete understanding of the genetic determinants of LATE neuropathologic changes (LATE-NC) in diverse populations. The defining neuropathologic feature of LATE-NC is TDP-43 proteinopathy, often with comorbid hippocampal sclerosis (HS). In terms of genetic risk factors, LATE-NC and/or HS are associated with single nucleotide variants (SNVs) in 3 genes-TMEM106B (rs1990622), GRN (rs5848), and ABCC9 (rs1914361 and rs701478). We evaluated these 3 genes in convenience samples of individuals of African ancestry. The allele frequencies of the LATE-associated alleles were significantly different between persons of primarily African (versus European) ancestry: In persons of African ancestry, the risk-associated alleles for TMEM106B and ABCC9 were less frequent, whereas the risk allele in GRN was more frequent. We performed an exploratory analysis of data from African-American subjects processed by the Alzheimer's Disease Genomics Consortium, with a subset of African-American participants (n = 166) having corroborating neuropathologic data through the National Alzheimer's Coordinating Center (NACC). In this limited-size sample, the ABCC9/rs1914361 SNV was associated with HS pathology. More work is required concerning the genetic factors influencing non-Alzheimer disease pathology such as LATE-NC in diverse cohorts.

Aim: H3G34 diffuse hemispheric glioma is a CNS tumor that is difficult to diagnose and treat and accompanied with poor prognosis. It is becoming clear that extra CNS metastasis may present in a subset of patients with H3G34 gliomas, further complicating diagnosis and treatment. Materials & methods: We present a case of a 19-year-old female with a H3G34 mutant diffuse hemispheric glioma with osseous metastases. We then provide a literature review of the most recent understanding of H3G34 mutant malignancies. Conclusion: Given the stress that patients with H3G34 can experience and the poor prognosis, it is imperative to expand our knowledge and ascertain accurate diagnostic methodologies and targeted therapeutic approaches.

TAR DNA-binding protein-43 (TDP-43) proteinopathies are accompanied by the pathological hallmark of cytoplasmic inclusions in the neurodegenerative diseases, including frontal temporal lobar degeneration-TDP and amyotrophic lateral sclerosis. We found that transthyretin accumulates with TDP-43 cytoplasmic inclusions in frontal temporal lobar degeneration-TDP human patients and transgenic mice, in which transthyretin exhibits dramatic expression decline in elderly mice. The upregulation of transthyretin expression was demonstrated to facilitate the clearance of cytoplasmic TDP-43 inclusions through autophagy, in which transthyretin induces autophagy upregulation via ATF4. Of interest, transthyretin upregulated ATF4 expression and promoted ATF4 nuclear import, presenting physical interaction. Neuronal expression of transthyretin in frontal temporal lobar degeneration-TDP mice restored autophagy function and facilitated early soluble TDP-43 aggregates for autophagosome targeting, ameliorating neuropathology and behavioural deficits. Thus, transthyretin conducted two-way regulations by either inducing autophagy activation or escorting TDP-43 aggregates targeted autophagosomes, suggesting that transthyretin is a potential modulator therapy for neurological disorders caused by TDP-43 proteinopathy.

Fucosylation, especially core fucosylation of N-glycans catalyzed by α1-6 fucosyltransferase (fucosyltransferase 8 or FUT8), plays an important role in regulating the peripheral immune system and inflammation. However, its role in microglial activation is poorly understood. Here we used human induced pluripotent stem cells-derived microglia (hiMG) as a model to study the role of FUT8-catalyzed core fucosylation in amyloid-β oligomer (AβO)-induced microglial activation, in view of its significant relevance to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AβO and lipopolysaccharides (LPS) with a pattern of pro-inflammatory activation as well as enhanced core fucosylation and FUT8 expression within 24 h. Furthermore, we found increased FUT8 expression in both human AD brains and microglia isolated from 5xFAD mice, a model of AD-like cerebral amyloidosis. Inhibition of fucosylation in AβO-stimulated hiMG reduced the induction of pro-inflammatory cytokines, suppressed the activation of p38MAPK, and rectified phagocytic deficits. Specific inhibition of FUT8 by siRNA-mediated knockdown also reduced AβO-induced pro-inflammatory cytokines. We further showed that p53 binds to the two consensus binding sites in the Fut8 promoter, and that p53 knockdown abolished FUT8 overexpression in AβO-activated hiMG. Taken together, our evidence supports that FUT8-catalyzed core fucosylation is a signaling pathway required for AβO-induced microglia activation and that FUT8 is a component of the p53 signaling cascade regulating microglial behavior. Because microglia are a key driver of AD pathogenesis, our results suggest that microglial FUT8 could be an anti-inflammatory therapeutic target for AD.

BackgroundUnderstanding the neurobiological underpinnings between established multimodal dementia risk factors and noninvasive blood-based biomarkers may lead to greater precision and earlier identification of older adults at risk of accelerated decline and dementia. We examined whether key vascular and genetic risk impact the association between cerebral amyloid burden and plasma aβ (amyloid β) 42/40 in nondemented older adults.MethodsWe used nondemented older adults from the UCD-ADRC (University of California, Davis-Alzheimer's Disease Research Center) study (n=96) and Alzheimer's Disease Neuroimaging Initiative (n=104). Alzheimer's Disease Neuroimaging Initiative was examined as confirmatory study cohort. We followed a cross-sectional design and examined linear regression followed by mediation analyses. Vascular risk score was obtained as the sum of hypertension, diabetes, hyperlipidemia, coronary artery disease, and cerebrovascular disease. Apolipoprotein E (APOE) ε4+ risk was genotyped, and plasma aβ42 and aβ40 were assayed. Cerebral amyloid burden was quantified using Florbetapir-PET scans. Baseline age was included as a covariate in all models.ResultsVascular risk significantly predicted cerebral amyloid burden in Alzheimer's Disease Neuroimaging Initiative but not in the UCD-ADRC cohort. Cerebral amyloid burden was associated with plasma aβ 42/40 in both cohorts. Higher vascular risk increased cerebral amyloid burden was indirectly associated with reduced plasma aβ 42/40 in Alzheimer's Disease Neuroimaging Initiative but not in UCD-ADRC cohort. However, when stratified by APOE ε4+ risk, we consistently observed this indirect relationship only in APOE ε4+ carriers across both cohorts.ConclusionsVascular risk is indirectly associated with the level of plasma aβ 42/40 via cerebral amyloid burden only in APOE ε4+ carriers. Nondemented older adults with genetic vulnerability to dementia and accelerated decline may benefit from careful monitoring of vascular risk factors directly associated with cerebral amyloid burden and indirectly with plasma aβ 42/40.

Challenges in identifying a glioblastoma's infiltrative edge during neurosurgical procedures result in rapid recurrence. A label-free fluorescence lifetime imaging (FLIm) device was used to evaluate glioblastoma's infiltrative edge in vivo in 15 patients (89 samples). FLIm data were analyzed according to tumor cell density, infiltrating tissue type (gray and white matter), and diagnosis history (new or recurrent). Infiltrations in white matter from new glioblastomas showed decreasing lifetimes and a spectral red shift with increasing tumor cell density. Areas of high versus low tumor cell density were separated through a linear discriminant analysis with a ROC-AUC=0.74. Current results support the feasibility of intraoperative FLIm for real-time in vivo brain measurements and encourage refinement to predict glioblastoma infiltrative edge, underscoring the ability of FLIm to optimize neurosurgical outcomes.

Identifying isocitrate dehydrogenase (IDH)-mutation and glioma subtype during surgery instead of days later can aid in modifying tumor resection strategies for better survival outcomes. We report intraoperative identification of IDH-mutant glioma (N = 12 patients) with a clinically compatible fluorescence lifetime imaging (FLIm) device (excitation: 355 nm; emission spectral bands: 390/40 nm, 470/28 nm, 542/50 nm). The fluorescence-derived parameters were analyzed to study the optical contrast between IDH-mutant tumors and surrounding brain tissue. IDH-mutant oligodendrogliomas exhibited shorter lifetimes (3.3 ± 0.1 ns) than IDH-mutant astrocytomas (4.1 ± 0.1 ns). Both IDH-mutant glioma subtypes had shorter lifetimes than white matter (4.6 ± 0.4 ns) but had comparable lifetimes to cortex. Lifetimes also increased with malignancy grade within IDH-mutant oligodendrogliomas (grade 2: 2.96 ± 0.08 ns, grade 3: 3.4 ± 0.3 ns) but not within IDH-mutant astrocytomas. The current results support the feasibility of FLIm as a surgical adjuvant for identifying IDH-mutant glioma tissue.

Computational machine learning (ML)-based frameworks could be advantageous for scalable analyses in neuropathology. A recent deep learning (DL) framework has shown promise in automating the processes of visualizing and quantifying different types of amyloid-β deposits as well as segmenting white matter (WM) from gray matter (GM) on digitized immunohistochemically stained slides. However, this framework has only been trained and evaluated on amyloid-β-stained slides with minimal changes in preanalytic variables. In this study, we evaluated select preanalytical variables including magnification, compression rate, and storage format using three digital slides scanners (Zeiss Axioscan Z1, Leica Aperio AT2, and Leica Aperio GT 450), on over 60 whole slide images, in a cohort of 14 cases having a spectrum of amyloid-β deposits. We conducted statistical comparisons of preanalytic variables with repeated measures analysis of variance evaluating the outputs of two DL frameworks for segmentation and object classification tasks. For both WM/GM segmentation and amyloid-β plaque classification tasks, there were statistical differences with respect to scanner types (p

Glycosylation has been found to be altered in the brains of individuals with Alzheimer's disease (AD). However, it is unknown which specific glycosylation-related pathways are altered in AD dementia. Using publicly available RNA-seq datasets covering seven brain regions and including 1724 samples, we identified glycosylation-related genes ubiquitously changed in individuals with AD. Several differentially expressed glycosyltransferases found by RNA-seq were confirmed by qPCR in a different set of human medial temporal cortex (MTC) samples (n = 20 AD vs. 20 controls). N-glycan-related changes predicted by expression changes in these glycosyltransferases were confirmed by mass spectrometry (MS)-based N-glycan analysis in the MTC (n = 9 AD vs. 6 controls). About 80% of glycosylation-related genes were differentially expressed in at least one brain region of AD participants (adjusted p-values

Research has found that genes specific to microglia are among the strongest risk factors for Alzheimer's disease (AD) and that microglia are critically involved in the etiology of AD. Thus, microglia are an important therapeutic target for novel approaches to the treatment of AD. High-throughput in vitro models to screen molecules for their effectiveness in reversing the pathogenic, pro-inflammatory microglia phenotype are needed. In this study, we used a multi-stimulant approach to test the usefulness of the human microglia cell 3 (HMC3) cell line, immortalized from a human fetal brain-derived primary microglia culture, in duplicating critical aspects of the dysfunctional microglia phenotype. HMC3 microglia were treated with cholesterol (Chol), amyloid beta oligomers (AβO), lipopolysaccharide (LPS), and fructose individually and in combination. HMC3 microglia demonstrated changes in morphology consistent with activation when treated with the combination of Chol + AβO + fructose + LPS. Multiple treatments increased the cellular content of Chol and cholesteryl esters (CE), but only the combination treatment of Chol + AβO + fructose + LPS increased mitochondrial Chol content. Microglia treated with combinations containing Chol + AβO had lower apolipoprotein E (ApoE) secretion, with the combination of Chol + AβO + fructose + LPS having the strongest effect. Combination treatment with Chol + AβO + fructose + LPS also induced APOE and TNF-α expression, reduced ATP production, increased reactive oxygen species (ROS) concentration, and reduced phagocytosis events. These findings suggest that HMC3 microglia treated with the combination of Chol + AβO + fructose + LPS may be a useful high-throughput screening model amenable to testing on 96-well plates to test potential therapeutics to improve microglial function in the context of AD.

Despite the increasing demographic diversity of the United States' aging population, there remain significant gaps in post-mortem research investigating the ethnoracial heterogeneity in the neuropathological landscape of Alzheimer Disease (AD). Most autopsy-based studies have focused on cohorts of non-Hispanic White decedents (NHWD), with few studies including Hispanic decedents (HD). We aimed to characterize the neuropathologic landscape of AD in NHWD (n = 185) and HD (n = 92) evaluated in research programs across three institutions: University of California San Diego, University of California Davis, and Columbia University. Only persons with a neuropathologic diagnosis of intermediate/high AD determined by NIA Reagan and/or NIA-AA criteria were included. A frequency-balanced random sample without replacement was drawn from the NHWD group using a 2:1 age and sex matching scheme with HD. Four brain areas were evaluated: posterior hippocampus, frontal, temporal, and parietal cortices. Sections were stained with antibodies against Aβ (4G8) and phosphorylated tau (AT8). We compared the distribution and semi-quantitative densities for neurofibrillary tangles (NFTs), neuropil threads, core, diffuse, and neuritic plaques. All evaluations were conducted by an expert blinded to demographics and group status. Wilcoxon's two-sample test revealed higher levels of neuritic plaques in the frontal cortex (p = 0.02) and neuropil threads (p = 0.02) in HD, and higher levels of cored plaques in the temporal cortex in NHWD (p = 0.02). Results from ordinal logistic regression controlling for age, sex, and site of origin were similar. In other evaluated brain regions, semi-quantitative scores of plaques, tangles, and threads did not differ statistically between groups. Our results demonstrate HD may be disproportionately burdened by AD-related pathologies in select anatomic regions, particularly tau deposits. Further research is warranted to understand the contributions of demographic, genetic, and environmental factors to heterogeneous pathological presentations.

We postulate that myelin injury contributes to cholesterol release from myelin and cholesterol dysmetabolism which contributes to Abeta dysmetabolism, and combined with genetic and AD risk factors, leads to increased Abeta and amyloid plaques. Increased Abeta damages myelin to form a vicious injury cycle. Thus, white matter injury, cholesterol dysmetabolism and Abeta dysmetabolism interact to produce or worsen AD neuropathology. The amyloid cascade is the leading hypothesis for the cause of Alzheimer's disease (AD). The failure of clinical trials based on this hypothesis has raised other possibilities. Even with a possible new success (Lecanemab), it is not clear whether this is a cause or a result of the disease. With the discovery in 1993 that the apolipoprotein E type 4 allele (APOE4) was the major risk factor for sporadic, late-onset AD (LOAD), there has been increasing interest in cholesterol in AD since APOE is a major cholesterol transporter. Recent studies show that cholesterol metabolism is intricately involved with Abeta (Aβ)/amyloid transport and metabolism, with cholesterol down-regulating the Aβ LRP1 transporter and upregulating the Aβ RAGE receptor, both of which would increase brain Aβ. Moreover, manipulating cholesterol transport and metabolism in rodent AD models can ameliorate pathology and cognitive deficits, or worsen them depending upon the manipulation. Though white matter (WM) injury has been noted in AD brain since Alzheimer's initial observations, recent studies have shown abnormal white matter in every AD brain. Moreover, there is age-related WM injury in normal individuals that occurs earlier and is worse with the APOE4 genotype. Moreover, WM injury precedes formation of plaques and tangles in human Familial Alzheimer's disease (FAD) and precedes plaque formation in rodent AD models. Restoring WM in rodent AD models improves cognition without affecting AD pathology. Thus, we postulate that the amyloid cascade, cholesterol dysmetabolism and white matter injury interact to produce and/or worsen AD pathology. We further postulate that the primary initiating event could be related to any of the three, with age a major factor for WM injury, diet and APOE4 and other genes a factor for cholesterol dysmetabolism, and FAD and other genes for Abeta dysmetabolism.

The proteins in the cell membrane of the brain are modified by glycans in highly interactive regions. The glycans and glycoproteins are involved in cell-cell interactions that are of fundamental importance to the brain. In this study, the comprehensive N-glycome and N-glycoproteome of the brain were determined in 11 functional brain regions, some of them known to be affected with the progression of Alzheimer's disease. N-glycans throughout the regions were generally highly branched and highly sialofucosylated. Regional variations were also found with regard to the glycan types including high mannose and complex-type structures. Glycoproteomic analysis identified the proteins that differed in glycosylation in the various regions. To obtain the broader representation of glycan compositions, four subjects with two in their 70s and two in their 90s representing two Alzheimer's disease subjects, one hippocampal sclerosis subject, and one subject with no cognitive impairment were analyzed. The four subjects were all glycomically mapped across 11 brain regions. Marked differences in the glycomic and glycoproteomic profiles were observed between the samples.

Significance5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence is currently used for image-guided glioma resection. Typically, this widefield imaging method highlights the bulk of high-grade gliomas, but it underperforms at the infiltrating edge where PpIX fluorescence is not visible to the eyes. Fluorescence lifetime imaging (FLIm) has the potential to detect PpIX fluorescence below the visible detection threshold. Moreover, simultaneous acquisition of time-resolved nicotinamide adenine (phosphate) dinucleotide [NAD(P)H] fluorescence may provide metabolic information from the tumor environment to further improve overall tumor detection.AimWe investigate the ability of pulse sampling, fiber-based FLIm to simultaneously image PpIX and NAD(P)H fluorescence of glioma infiltrative margins in patients.ApproachA mesoscopic fiber-based point-scanning FLIm device (355 nm pulses) was used to simultaneously resolve the fluorescence decay of PpIX (629/53 nm) and NAD(P)H (470/28 nm). The FLIm device enabled data acquisition at room light and rapid (

Neuropathology studies of the oldest-old have significantly advanced our understandingof the multiple etiologies late in very late life; however, this hasbeen limited to studies of non-Hispanic white (NHW) decedents. The LifeAfter90study is an ongoing cohort study of integrated healthcare deliverysystem members in Northern California, aged 90+ with targeted recruitmentof persons across different racial/ethnic backgrounds with no prior diagnosisof dementia in their medical record. Brain donation is available to all interestedconsenting participants. As of January 2022, 216 participants (26% ofsample) were enrolled in autopsy (autopsy enrollees: 20% Asian, 15% AfricanAmerican, 17% Latino, 9% Multiracial/Other, and 39% NHW) with 25deceased and neuropathological evaluations completed. Average age ofdeath was 95 years (range 91-106), 13 (62.5%) were female, 14 NHW, 6 Latino,3 Multiracial, 1 Asian, and 1 African American. At final clinical exam,14 participants were cognitively normal (56%), 8 had questionable/mild cognitiveimpairment (32%), and 3 were dementia (12%). With respect to Alzheimer'sdisease (AD) neuropathologic diagnosis, no cases had high ADlikelihood, 8 met criteria for intermediate (32%), 11 low (44%), and 6 did nothave AD (24%). All participants had some level of neurofibrillary tangles(NFTs); median Braak NFT stage was II (range I-V). Six participants lackedplaques, and highest Thal phase was 4. Eleven participants (44%) had Lewybodies. TDP-43 inclusions were detected in 5 participants (20%). The mostcommon assessed pathologies were ARTAG in 19 participants (76%) andsome degree of arteriolosclerosis in 24 participants (96%) although only 4were considered to have severe arteriolosclerosis. This diverse cohort ofoldest-old individuals indicate numerous brain pathologies are present withadvanced age, albeit most participants having mild severity and distributionsof pathologies providing further evidence of the complex and multifactorialnature of clinic-pathological correlations.

IntroductionWe examine whether the association between key plasma biomarkers (amyloid β [aβ] 42/40, total tau (t-tau), neurofilament light [NfL]) and cognitive trajectories (executive function [EF] and episodic memory [EM]) is mediated through neurodegeneration.MethodsAll participants were recruited from the University of California, Davis-Alzheimer's Disease Research Center (n = 473; baseline age range = 49-95 years, 60% women). We applied an accelerated longitudinal design to test latent growth models for EF and EM, and path and mediation analyses. Age was centered at 75 years, and all models were adjusted for sex, education, and ethnicity.ResultsHV differentially mediated the association aβ 42/40 and NfL on EF and EM level and change. Hippocampal volume (HV) did not mediate the association between t-tau and cognitive performance.DiscussionNeurodegeneration as represented with HV selectively mediates the association between key non-invasive plasma biomarkers and cognitive trajectories in an ethnoracially and clinically diverse community-based sample.

IntroductionThere is an increased need for the development of novel blood-based biomarkers for early detection, prevention, or intervention in Alzheimer's disease (AD). This study sought to determine whether serum glycopeptide analysis holds potential for identifying novel diagnostics and prognostics of AD.MethodsThe study involved 195 participants, including 96 patients with an AD diagnosis and 99 controls with no cognitive deficit. Utilizing a validated analytical mass spectrometry method, we monitored the site-specific glycosylation of 52 serum glycoproteins.ResultsPartial least-squares discriminant analysis revealed that changes in overall sialylation and fucosylation of serum glycoproteins may be indicators of an AD disease state. Loss of fucosylation of immunoglobulin G1 (IgG1) and IgG2 was indicative of AD diagnosis. Individual glycopeptide analysis found separation between the AD patients and controls on complement proteins and apolipoprotein B.DiscussionThe results of this study suggest that serum glycoprofiling may be a promising approach for biomarker discovery.

High-density lipoproteins (HDL) play a critical role in cholesterol homeostasis. Apolipoprotein E (APOE), particularly the E4 allele, is a significant risk factor for Alzheimer's disease but is also a key HDL-associated protein involved in lipid transport in both the periphery and central nervous systems. The objective was to determine the influence of the APOE genotype on HDL function and size in the context of Alzheimer's disease. HDL from 194 participants (non-demented controls, mild cognitive impairment, and Alzheimer's disease dementia) were isolated from the plasma. The HDL cholesterol efflux capacity (CEC), lecithin-cholesterol acyltransferase (LCAT) activity, and particle diameter were measured. Neuropsychological test scores, clinical dementia rating, and magnetic resonance imaging scores were used to determine if cognition is associated with HDL function and size. HDL CEC and LCAT activity were reduced in APOE3E4 carriers compared to APOE3E3 carriers, regardless of diagnosis. In APOE3E3 carriers, CEC and LCAT activity were lower in patients. In APOE3E4 patients, the average particle size was lower. HDL LCAT activity and particle size were positively correlated with the neuropsychological scores and negatively correlated with the clinical dementia rating. We provide evidence for the first time of APOE genotype-specific alterations in HDL particles in Alzheimer's disease and an association between HDL function, size, and cognitive function.

It has been shown that the Western diet (WD) induces systemic inflammation and cognitive decline. Moreover, probiotic supplementation and antibiotic treatment reduce diet-induced hepatic inflammation. The current study examines whether shaping the gut microbes by Bifidobacterium infantis (B. infantis) supplementation and antibiotic treatment reduce diet-induced brain inflammation and improve neuroplasticity. Furthermore, the significance of bile acid (BA) signaling in regulating brain inflammation was studied. Mice were fed a control diet (CD) or WD for seven months. B. infantis was supplemented to WD-fed mice to study brain inflammation, lipid, metabolomes, and neuroplasticity measured by long-term potentiation (LTP). Broad-spectrum coverage antibiotics and cholestyramine treatments were performed to study the impact of WD-associated gut microbes and BA in brain inflammation. Probiotic B. infantis supplementation inhibited diet-induced brain inflammation by reducing IL6, TNFα, and CD11b levels. B. infantis improved LTP and increased brain PSD95 and BDNF levels, which were reduced due to WD intake. Additionally, B. infantis reduced cecal cholesterol, brain ceramide and enhanced saturated fatty acids. Moreover, antibiotic treatment, as well as cholestyramine, diminished WD-induced brain inflammatory signaling. Our findings support the theory that intestinal microbiota remodeling by B. infantis reduces brain inflammation, activates BA receptor signaling, and improves neuroplasticity.

Tau pathology is instrumental in the gradual loss of neuronal functions and cognitive decline in tauopathies, including Alzheimer's disease (AD). Earlier reports showed that adenosine metabolism is abnormal in the brain of AD patients while consequences remained ill-defined. Herein, we aimed at investigating whether manipulation of adenosine tone would impact Tau pathology, associated molecular alterations and subsequent neurodegeneration. We demonstrated that treatment with an inhibitor (J4) of equilibrative nucleoside transporter 1 (ENT1) exerted beneficial effects in a mouse model of Tauopathy. Treatment with J4 not only reduced Tau hyperphosphorylation but also rescued memory deficits, mitochondrial dysfunction, synaptic loss, and abnormal expression of immune-related gene signatures. These beneficial effects were particularly ascribed to the ability of J4 to suppress the overactivation of AMPK (an energy reduction sensor), suggesting that normalization of energy dysfunction mitigates neuronal dysfunctions in Tauopathy. Collectively, these data highlight that targeting adenosine metabolism is a novel strategy for tauopathies.

Persons over the age of 90 are the fastest growing segment of the population in the US, yet there is a dearth of studies investigating the underlying neuropathology of cognitive impairment and dementias, in ethnically diverse, non-white decedents. The Life after 90 study began enrollment in July 2018 and is an ongoing cohort study of members of Kaiser Permanente Northern California aged 90+ with targeted recruitment of individuals across different racial/ethnic groups with no prior diagnosis of dementia in their medical record. Participants are examined every 6 months. Brain donation was available to all interested consenting participants. Neuropathology was assessed using the National Alzheimer's Coordinating Center Neuropathology form v. 10. As of January 2021, 173 (26%) participants enrolled in autopsy (18% Asian, 12% African American, 12% Latino, and 10% as multiracial) with 8 deceased and neuropathological evaluations completed. Average age of death was 96 years (range 91 to 105), 5 (62.5%) were female, 3 Latino, 3 Caucasian, and 2 multiracial. At the final clinical exam, which was on average 4 months before death (range: 2-8), 2 participant had dementia (25%), 3 questionable/mild cognitive impairment (37.5%), and 3 cognitively normal (37.5%). With respect to a neuropathologic diagnosis of Alzheimer's disease (AD), 2 met criteria for intermediate likelihood (25%), 4 low (50%), and 2 were considered not to have AD (25%). Notably, none had high likelihood of AD. All participants had some level of neurofibrillary tangles with Braak stages between II and IV. Two participants lacked plaques (Amyloid-Beta or neuritic types), and the highest Thal phase was 4. Four participants (50%) had Lewy bodies (LBs), 1 in olfactory bulb/tract only, 2 Transitional, and 1 with Diffuse. Hippocampal sclerosis was not seen in any whereas TDP-43 inclusions were detected in 2 participants (25%). Diffuse LB, TDP-43 inclusions, and intermediate AD co-occurred in one (50%) of the dementia participants while all lacking in the other. Preliminary results of the first 8 deaths in this multiethnic cohort of oldest-old individuals indicate that numerous brain pathologies are present with advanced age. Further work with this study will examine the clinical impact of this pathological heterogeneity.

Alzheimer's disease is characterized by the accumulation of amyloid-[beta] plaques, aggregation of hyperphosphorylated tau (pTau), and microglia activation. Galectin-3 (Gal3) is a [beta]-galactoside- binding protein that has been implicated in amyloid pathology. Its role in tauopathy remains enigmatic. Here, we showed that Gal3 was upregulated in the microglia of humans and mice with tauopathy. pTau triggered the release of Gal3 from human induced pluripotent stem cell-derived microglia in both its free and extracellular vesicular-associated (EV-associated) forms. Both forms of Gal3 increased the accumulation of pathogenic tau in recipient cells. Binding of Gal3 to pTau greatly enhanced tau fibrillation. Besides Gal3, pTau was sorted into EVs for transmission. Moreover, pTau markedly enhanced the number of EVs released by iMGL in a Gal3-dependent manner, suggesting a role of Gal3 in biogenesis of EVs. Single-cell RNA-Seq analysis of the hippocampus of a mouse model of tauopathy (THY-Tau22) revealed a group of pathogenic tau-evoked, Gal3- associated microglia with altered cellular machineries implicated in neurodegeneration, including enhanced immune and inflammatory responses. Genetic removal of Gal3 in THY-Tau22 mice suppressed microglia activation, reduced the level of pTau and synaptic loss in neurons, and rescued memory impairment. Collectively, Gal3 is a potential therapeutic target for tauopathy., Introduction Neuronal inclusions consisting of the microtubule-associated protein tau are found in various neurodegenerative diseases known as tauopathies. Alzheimer's disease (AD) is the most prevalent tauopathy and is characterized by [...]

Background: Local protein synthesis and mRNA metabolism mediated by mRNP granules in the dendrites and the postsynaptic compartment is essential for synaptic remodeling and plasticity in neuronal cells. Dysregulation of these processes caused by TDP-43 proteinopathy leads to neurodegenerative diseases, such as frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Methods: Using biochemical analysis and imaging techniques, including super-resolution microscopy, we provide evidence, for the first time, for the postsynaptic localization of TDP-43 in mammalian synapses and we show that TDP-43 is a component of neuronal mRNP granules. Results: With activity stimulation and various molecular approaches, we further demonstrate activity-dependent mRNP granule dynamics involving disassembly of mRNP granules, release of mRNAs, activation of local protein translation, and the impairment of granule disassembly in cellular, animal and human models of TDP-43 proteinopathy. Conclusion: Our study elucidates the interplay between TDP-43 and neuronal mRNP granules in normal physiology and TDP-43 proteinopathy in the regulation of local protein translation and mRNA metabolism in the postsynaptic compartment.

In vivo, minimally invasive microscopy in deep cortical and sub-cortical regions of the mouse brain has been challenging. To address this challenge, we present an in vivo high numerical aperture optical coherence microscopy (OCM) approach that fully utilizes the water absorption window around 1700 nm, where ballistic attenuation in the brain is minimized. Key issues, including detector noise, excess light source noise, chromatic dispersion, and the resolution-speckle tradeoff, are analyzed and optimized. Imaging through a thinned-skull preparation that preserves intracranial space, we present volumetric imaging of cytoarchitecture and myeloarchitecture across the entire depth of the mouse neocortex, and some sub-cortical regions. In an Alzheimer's disease model, we report that findings in superficial and deep cortical layers diverge, highlighting the importance of deep optical biopsy. Compared to other microscopic techniques, our 1700 nm OCM approach achieves a unique combination of intrinsic contrast, minimal invasiveness, and high resolution for deep brain imaging.

Corpora amylacea (CA) increase in number and size with aging. Their origins and functions remain unknown. Previously, we found that Alzheimer's disease (AD) brains have more CA in the periventricular white matter (PVWM) compared to aging controls. In addition, CA is associated with neurodegeneration as indicated by colocalization of degraded myelin basic protein (dMBP) with periodic acid-Schiff (PAS), a CA marker. We also found that bacterial lipopolysaccharide is present in aging brains, with more LPS in AD compared with controls. Periodic acid-Schiff staining is used to identify CA by virtue of their high polysaccharide content. Despite the growing knowledge of CA as a contributor to AD pathology, the molecules that contribute to the polysaccharides in CA are not known. Notably, lipopolysaccharides (LPS) are important cell-surface polysaccharides found in all Gram-negative bacteria. However, it is unknown whether PAS could detect LPS, whether the LPS found in aging brains contribute to the polysaccharide found in CA, and whether LPS associate with myelin injury. In this study, we found that aging brains had a myelin deficit zone (MDZ) adjacent to the ventricles in PVWM. The MDZ contained vesicles, most of which were CA. LPS and dMBP levels were higher in AD than in control brains. LPS was colocalized with dMBP in the vesicles/CA, linking white matter injury with a bacterial pro-inflammatory molecule. The vesicles also contained oxidized fibers, C-reactive protein, NG2, and GALC, markers of oligodendrocyte precursor cells (OPCs) and oligodendrocyte cells (OLs), respectively. The vesicles/CA were surrounded by dense astrocyte processes in control and AD brains. LPS was co-localized with CA by double staining of PAS with LPS in aging brains. The relationship of LPS with PAS staining was confirmed by PAS staining of purified LPS on nitrocellulose membranes. These findings reveal that LPS is one of the polysaccharides found in CA which can be stained with PAS. In addition, vesicles/CA are associated with oxidized and damaged myelin. The LPS in these vesicles/CA may have contributed to this oxidative myelin damage and may have contributed to oxidative stress to OPCs and OLs which could impair the ability to repair damaged myelin in AD and control brains.

BackgroundChronic consumption of high sugar and high fat diet associated with liver inflammation and cognitive decline. This paper tests a hypothesis that the development and resolution of diet-induced nonalcoholic fatty liver disease (NAFLD) has an impact on neuroplasticity and cognition.MethodsC57BL/6 wild-type mice were fed with either a healthy control diet (CD) or a fructose, palmitate, and cholesterol (FPC)-enriched diet since weaning. When mice were 3-months old, FPC diet-fed mice were randomly assigned to receive either FPC-enriched diet with or without 6% inulin supplementation. At 8 months of age, all three groups of mice were euthanized followed by analysis of inflammatory signaling in the liver and brain, gut microbiota, and cecal metabolites.ResultsOur data showed that FPC diet intake induced hepatic steatosis and inflammation in the liver and brain along with elevated RORγ and IL-17A signaling. Accompanied by microglia activation and reduced hippocampal long-term potentiation, FPC diet intake also reduced postsynaptic density-95 and brain derived neurotrophic factor, whereas inulin supplementation prevented diet-reduced neuroplasticity and the development of NAFLD. In the gut, FPC diet increased Coriobacteriaceae and Erysipelotrichaceae, which are implicated in cholesterol metabolism, and the genus Allobaculum, and inulin supplementation reduced them. Furthermore, FPC diet reduced FXR and TGR5 signaling, and inulin supplementation reversed these changes. Untargeted cecal metabolomics profiling uncovered 273 metabolites, and 104 had significant changes due to FPC diet intake or inulin supplementation. Among the top 10 most affected metabolites, FPC-fed mice had marked increase of zymosterol, a cholesterol biosynthesis metabolite, and reduced 2,8-dihydroxyquinoline, which has known benefits in reducing glucose intolerance; these changes were reversible by inulin supplementation. Additionally, the abundance of Barnesiella, Coprobacter, Clostridium XIVa, and Butyrivibrio were negatively correlated with FPC diet intake and the concentration of cecal zymosterol but positively associated with inulin supplementation, suggesting their benefits.ConclusionTaken together, the presented data suggest that diet alters the gut microbiota and their metabolites, including bile acids. This will subsequently affect IL-17A signaling, resulting in systemic impacts on both hepatic metabolism and cognitive function.

The FGFR1 gene encoding fibroblast growth factor receptor 1 has emerged as a frequently altered oncogene in the pathogenesis of multiple low-grade neuroepithelial tumor (LGNET) subtypes including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumor (DNT), rosette-forming glioneuronal tumor (RGNT), and extraventricular neurocytoma (EVN). These activating FGFR1 alterations in LGNET can include tandem duplication of the exons encoding the intracellular tyrosine kinase domain, in-frame gene fusions most often with TACC1 as the partner, or hotspot missense mutations within the tyrosine kinase domain (either at p.N546 or p.K656). However, the specificity of these different FGFR1 events for the various LGNET subtypes and accompanying genetic alterations are not well defined. Here we performed comprehensive genomic and epigenomic characterization on a diverse cohort of 30 LGNET with FGFR1 alterations. We identified that RGNT harbors a distinct epigenetic signature compared to other LGNET with FGFR1 alterations, and is uniquely characterized by FGFR1 kinase domain hotspot missense mutations in combination with either PIK3CA or PIK3R1 mutation, often with accompanying NF1 or PTPN11 mutation. In contrast, EVN harbors its own distinct epigenetic signature and is characterized by FGFR1-TACC1 fusion as the solitary pathogenic alteration. Additionally, DNT and pilocytic astrocytoma are characterized by either kinase domain tandem duplication or hotspot missense mutations, occasionally with accompanying NF1 or PTPN11 mutation, but lacking the accompanying PIK3CA or PIK3R1 mutation that characterizes RGNT. The glial component of LGNET with FGFR1 alterations typically has a predominantly oligodendroglial morphology, and many of the pilocytic astrocytomas with FGFR1 alterations lack the biphasic pattern, piloid processes, and Rosenthal fibers that characterize pilocytic astrocytomas with BRAF mutation or fusion. Together, this analysis improves the classification and histopathologic stratification of LGNET with FGFR1 alterations.

TDP-43 inclusions are found in many Alzheimer's disease (AD) patients presenting faster disease progression and greater brain atrophy. Previously, we showed full-length TDP-43 forms spherical oligomers and perturbs amyloid-β (Aβ) fibrillization. To elucidate the role of TDP-43 in AD, here, we examined the effect of TDP-43 in Aβ aggregation and the attributed toxicity in mouse models. We found TDP-43 inhibited Aβ fibrillization at initial and oligomeric stages. Aβ fibrillization was delayed specifically in the presence of N-terminal domain containing TDP-43 variants, while C-terminal TDP-43 was not essential for Aβ interaction. TDP-43 significantly enhanced Aβ's ability to impair long-term potentiation and, upon intrahippocampal injection, caused spatial memory deficit. Following injection to AD transgenic mice, TDP-43 induced inflammation, interacted with Aβ, and exacerbated AD-like pathology. TDP-43 oligomers mostly colocalized with intracellular Aβ in the brain of AD patients. We conclude that TDP-43 inhibits Aβ fibrillization through its interaction with Aβ and exacerbates AD pathology.

Microglia-mediated inflammation exerts adverse effects in ischemic stroke and in neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the voltage-gated potassium channel Kv1.3 is required for microglia activation. Both genetic deletion and pharmacological inhibition of Kv1.3 are effective in reducing microglia activation and the associated inflammatory responses, as well as in improving neurological outcomes in animal models of AD and ischemic stroke. Here we sought to elucidate the molecular mechanisms underlying the therapeutic effects of Kv1.3 inhibition, which remain incompletely understood. Using a combination of whole-cell voltage-clamp electrophysiology and quantitative PCR (qPCR), we first characterized a stimulus-dependent differential expression pattern for Kv1.3 and P2X4, a major ATP-gated cationic channel, both in vitro and in vivo. We then demonstrated by whole-cell current-clamp experiments that Kv1.3 channels contribute not only to setting the resting membrane potential but also play an important role in counteracting excessive membrane potential changes evoked by depolarizing current injections. Similarly, the presence of Kv1.3 channels renders microglia more resistant to depolarization produced by ATP-mediated P2X4 receptor activation. Inhibiting Kv1.3 channels with ShK-223 completely nullified the ability of Kv1.3 to normalize membrane potential changes, resulting in excessive depolarization and reduced calcium transients through P2X4 receptors. Our report thus links Kv1.3 function to P2X4 receptor-mediated signaling as one of the underlying mechanisms by which Kv1.3 blockade reduces microglia-mediated inflammation. While we could confirm previously reported differences between males and females in microglial P2X4 expression, microglial Kv1.3 expression exhibited no gender differences in vitro or in vivo. MAIN POINTS: The voltage-gated K+ channel Kv1.3 regulates microglial membrane potential. Inhibition of Kv1.3 depolarizes microglia and reduces calcium entry mediated by P2X4 receptors by dissipating the electrochemical driving force for calcium.

Saccharides in our diet are major sources of carbon for the formation of biomass such as proteins, lipids, nucleic acids and glycans. Among the dietary monosaccharides, glucose occupies a central role in metabolism, but human blood contains regulated levels of other monosaccharides as well. Their influence on metabolism and how they are utilized have not been explored thoroughly. Applying metabolic flux analysis on glycan synthesis can reveal the pathways that supply glycosylation precursors and provide a snapshot of the metabolic state of the cell. In this study, we traced the incorporation of six 13C uniformly labeled monosaccharides in the N-glycans, O-glycans and glycosphingolipids of both pluripotent and neural NTERA-2 cells. We gathered detailed isotopologue data for hundreds of glycoconjugates using mass spectrometry methods. The contributions of de novo synthesis and direct incorporation pathways for glucose, mannose, fructose, galactose, N-acetylglucosamine and fucose were determined based on their isotope incorporation. Co-feeding studies revealed that fructose incorporation is drastically decreased by the presence of glucose, while mannose and galactose were much less affected. Furthermore, increased sialylation slowed down the turnover of glycans, but fucosylation attenuated this effect. Our results demonstrated that exogenous monosaccharide utilization can vary markedly depending on the cell differentiation state and monosaccharide availability, and that the incorporation of carbons can also differ among different glycan structures. We contend that the analysis of metabolic isotope labeling of glycans can yield new insights about cell metabolism.

Disruptions in the gene encoding methyl-CpG binding protein 2 (MECP2) underlie complex neurodevelopmental disorders including Rett Syndrome (RTT), MECP2 duplication disorder, intellectual disabilities, and autism. Significant progress has been made on the molecular and cellular basis of MECP2-related disorders providing a new framework for understanding how altered epigenetic landscape can derail the formation and refinement of neuronal circuits in early postnatal life and proper neurological function. This review will summarize selected major findings from the past years and particularly highlight the integrated and multidisciplinary work done at eight NIH-funded Intellectual and Developmental Disabilities Research Centers (IDDRC) across the US. Finally, we will outline a path forward with identification of reliable biomarkers and outcome measures, longitudinal preclinical and clinical studies, reproducibility of results across centers as a synergistic effort to decode and treat the pathogenesis of the complex MeCP2 disorders.

Characterization of the key cellular targets contributing to sustained microglial activation in neurodegenerative diseases, including Parkinson's disease (PD), and optimal modulation of these targets can provide potential treatments to halt disease progression. Here, we demonstrated that microglial Kv1.3, a voltage-gated potassium channel, was transcriptionally upregulated in response to aggregated α-synuclein (αSynAgg) stimulation in primary microglial cultures and animal models of PD, as well as in postmortem human PD brains. Patch-clamp electrophysiological studies confirmed that the observed Kv1.3 upregulation translated to increased Kv1.3 channel activity. The kinase Fyn, a risk factor for PD, modulated transcriptional upregulation and posttranslational modification of microglial Kv1.3. Multiple state-of-the-art analyses, including Duolink proximity ligation assay imaging, revealed that Fyn directly bound to Kv1.3 and posttranslationally modified its channel activity. Furthermore, we demonstrated the functional relevance of Kv1.3 in augmenting the neuroinflammatory response by using Kv1.3-KO primary microglia and the Kv1.3-specific small-molecule inhibitor PAP-1, thus highlighting the importance of Kv1.3 in neuroinflammation. Administration of PAP-1 significantly inhibited neurodegeneration and neuroinflammation in multiple animal models of PD. Collectively, our results imply that Fyn-dependent regulation of Kv1.3 channels plays an obligatory role in accentuating the neuroinflammatory response in PD and identify Kv1.3 as a potential therapeutic target for PD.

TAR DNA-binding protein 43 (TDP-43) has been implicated in frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-TDP) and amyotrophic lateral sclerosis. Histone deacetylase 1 (HDAC1) is involved in DNA repair and neuroprotection in numerous neurodegenerative diseases. However, the pathological mechanisms of FTLD-TDP underlying TDP-43 proteinopathies are unclear, and the role of HDAC1 is also poorly understood. Here, we found that aberrant cell cycle activity and DNA damage are important pathogenic factors in FTLD-TDP transgenic (Tg) mice, and we further identified these pathological features in the frontal cortices of patients with FTLD-TDP. TDP-43 proteinopathies contributed to pathogenesis by inducing cytosolic mislocalization of HDAC1 and reducing its activity. Pharmacological recovery of HDAC1 activity in FTLD-TDP Tg mice ameliorated their cognitive and motor impairments, normalized their aberrant cell cycle activity, and attenuated their DNA damage and neuronal loss. Thus, HDAC1 deregulation is involved in the pathogenesis of TDP-43 proteinopathies, and HDAC1 is a potential target for therapeutic interventions in FTLD-TDP.

Brain tumors are the most common solid tumors of childhood, and the genetic drivers and optimal therapeutic strategies for many of the different subtypes remain unknown. Here, we identify that bithalamic gliomas harbor frequent mutations in the EGFR oncogene, only rare histone H3 mutation (in contrast to their unilateral counterparts), and a distinct genome-wide DNA methylation profile compared to all other glioma subtypes studied to date. These EGFR mutations are either small in-frame insertions within exon 20 (intracellular tyrosine kinase domain) or missense mutations within exon 7 (extracellular ligand-binding domain) that occur in the absence of accompanying gene amplification. We find these EGFR mutations are oncogenic in primary astrocyte models and confer sensitivity to specific tyrosine kinase inhibitors dependent on location within the kinase domain or extracellular domain. We initiated treatment with targeted kinase inhibitors in four children whose tumors harbor EGFR mutations with encouraging results. This study identifies a promising genomically-tailored therapeutic strategy for bithalamic gliomas, a lethal and genetically distinct brain tumor of childhood.

Abstract BACKGROUND Rosette-forming glioneuronal tumor (RGNT) is an uncommon CNS tumor originally described in the fourth ventricle characterized by a low-grade glial neoplasm admixed with a rosette-forming neurocytic component. METHODS We reviewed clinicopathologic features of 42 patients with RGNT. Targeted next-generation sequencing was performed, and genome-wide methylation profiling is underway. RESULTS The 20 male and 22 female patients had a mean age of 25 years (range 3–47) at time of diagnosis. Tumors were located within or adjacent to the lateral ventricle (n=16), fourth ventricle (15), third ventricle (9), and spinal cord (2). All 31 tumors assessed to date contained FGFR1 activating alterations, either in-frame gene fusion, kinase domain tandem duplication, or hotspot missense mutation in the kinase domain (p.N546 or p.K656). While 7 of these 31 tumors harbored FGFR1 alterations as the solitary pathogenic event, 24 contained additional pathogenic alterations within PI3-kinase or MAP kinase pathway genes: 5 with additional PIK3CA and NF1 mutations, 4 with PIK3CA mutation, 3 with PIK3R1 mutation (one of which also contained focal RAF1 amplification), 5 with PTPN11 mutation (one with additional PIK3R1 mutation), and 2 with NF1 deletion. The other 5 cases demonstrated anaplastic features including hypercellularity and increased mitotic activity. Among these anaplastic cases, 3 harbored inactivating ATRX mutations and two harbored CDKN2A homozygous deletion, in addition to the FGFR1 alterations plus other PI3-kinase and MAP kinase gene mutations seen in those RGNT without anaplasia. CONCLUSION Independent of ventricular location, RGNT is defined by FGFR1 activating mutations or rearrangements, which are frequently accompanied by mutations involving PIK3CA, PIK3R1, PTPN11, NF1, and KRAS. Whereas pilocytic astrocytoma and ganglioglioma are characterized by solitary activating MAP kinase pathway alterations (e.g. BRAF fusion or mutation), RGNT are genetically more complex with dual PI3K-Akt-mTOR and Ras-Raf-MAPK pathway activation. Rare anaplastic examples may show additional ATRX and/or CDKN2A inactivation.

Neuropathologists assess vast brain areas to identify diverse and subtly-differentiated morphologies. Standard semi-quantitative scoring approaches, however, are coarse-grained and lack precise neuroanatomic localization. We report a proof-of-concept deep learning pipeline that identifies specific neuropathologies-amyloid plaques and cerebral amyloid angiopathy-in immunohistochemically-stained archival slides. Using automated segmentation of stained objects and a cloud-based interface, we annotate > 70,000 plaque candidates from 43 whole slide images (WSIs) to train and evaluate convolutional neural networks. Networks achieve strong plaque classification on a 10-WSI hold-out set (0.993 and 0.743 areas under the receiver operating characteristic and precision recall curve, respectively). Prediction confidence maps visualize morphology distributions at high resolution. Resulting network-derived amyloid beta (Aβ)-burden scores correlate well with established semi-quantitative scores on a 30-WSI blinded hold-out. Finally, saliency mapping demonstrates that networks learn patterns agreeing with accepted pathologic features. This scalable means to augment a neuropathologist's ability suggests a route to neuropathologic deep phenotyping.

ObjectiveMicroglia play a pivotal role in the initiation and progression of Alzheimer's disease (AD). We here tested the therapeutic hypothesis that the Ca2+-activated potassium channel KCa3.1 constitutes a potential target for treating AD by reducing neuroinflammation.MethodsTo determine if KCa3.1 is relevant to AD, we tested if treating cultured microglia or hippocampal slices with Aβ oligomer (AβO) activated KCa3.1 in microglia, and if microglial KCa3.1 was upregulated in 5xFAD mice and in human AD brains. The expression/activity of KCa3.1 was examined by qPCR, Western blotting, immunohistochemistry, and whole-cell patch-clamp. To investigate the role of KCa3.1 in AD pathology, we resynthesized senicapoc, a clinically tested KCa3.1 blocker, and determined its pharmacokinetic properties and its effect on microglial activation, Aβ deposition and hippocampal long-term potentiation (hLTP) in 5xFAD mice.ResultsWe found markedly enhanced microglial KCa3.1 expression/activity in brains of both 5xFAD mice and AD patients. In hippocampal slices, microglial KCa3.1 expression/activity was increased by AβO treatment, and its inhibition diminished the proinflammatory and hLTP-impairing activities of AβO. Senicapoc exhibited excellent brain penetrance and oral availability, and in 5xFAD mice, reduced neuroinflammation, decreased cerebral amyloid load, and enhanced hippocampal neuronal plasticity.InterpretationOur results prompt us to propose repurposing senicapoc for AD clinical trials, as senicapoc has excellent pharmacological properties and was safe and well-tolerated in a prior phase-3 clinical trial for sickle cell anemia. Such repurposing has the potential to expedite the urgently needed new drug discovery for AD.

IntroductionWe sought to establish the relationships between standard postmortem measures of AD neuropathology and antemortem [11C]PIB-positron emission tomography ([11C]PIB-PET) analyzed with the Centiloid (CL) method, a standardized scale for Aβ-PET quantification.MethodsFour centers contributed 179 participants encompassing a broad range of clinical diagnoses, PET data, and autopsy findings.ResultsCL values increased with each CERAD neuritic plaque score increment (median -3 CL for no plaques and 92 CL for frequent plaques) and nonlinearly with Thal Aβ phases (increases were detected starting at phase 2) with overlap between scores/phases. PET-pathology associations were comparable across sites and unchanged when restricting the analyses to the 56 patients who died within 2 years of PET. A threshold of 12.2 CL detected CERAD moderate-to-frequent neuritic plaques (area under the curve = 0.910, sensitivity = 89.2%, specificity = 86.4%), whereas 24.4 CL identified intermediate-to-high AD neuropathological changes (area under the curve = 0.894, sensitivity = 84.1%, specificity = 87.9%).DiscussionOur study demonstrated the robustness of a multisite Centiloid [11C]PIB-PET study and established a range of pathology-based CL thresholds.

Our nation is becoming increasingly diverse; however, few autopsy studies examine multiple ethnoracial groups, especially Hispanics. We examined differences in neuropathological diagnoses of 423 deceased participants with dementia from three ethnoracial groups (35 Black, 28 Hispanic, and 360 non-Hispanic White) evaluated at the University of California Davis Alzheimer's Disease Center. We used novel applications of bootstrap resampling and logistic regression standardization to project neuropathological diagnostic rates for non-Hispanic Whites to minority sample characteristics to improve inference of findings. Alzheimer's disease (AD) without significant cerebrovascular disease (CVD) or other dementia-related pathologies (AD (non-mixed)) was present in 15 Black (43%), 4 Hispanic (14%), and 156 (43%) non-Hispanic Whites. CVD sufficient to contribute to dementia was confirmed in 14 Black (40%), 15 Hispanic (54%), and 101 (28%) non-Hispanic White decedents. The observed CVD prevalence of 40% in Blacks exceeded the predicted 29% [95% CI: 22%-36%]. Despite being outside the 95% confidence interval, the difference between observed and predicted was not statistically significant after bootstrap testing. Conversely, for Hispanics, the observed proportion at 54% exceeded significantly the predicted prevalence of 24% from non-Hispanic Whites [95% CI: 16%-34%], avg. p = 0.008). An identical analysis using AD (non-mixed) as the outcome predicted AD (non-mixed) in Blacks averaging 41% [95% CI: 34%-48%], nearly equal to observed prevalence. For Hispanics, however, the observed proportion at 14%, was well below predictions (mean = 42%, 95% CI: 32%-53%], avg. p = 0.008). We conclude mixed diagnoses and CVD are more common in Hispanic and Black decedents than Non-Hispanic Whites with dementia in our cohort. The increased prevalence of vascular co-morbidity may be a potential opportunity to intervene more effectively in dementia treatment of those individuals.

Microglia show a rich repertoire of activation patterns regulated by a complex ensemble of surface ion channels, receptors, and transporters. We and others have investigated whether microglia vary their K+ channel expression as a means to achieve functional diversity. However, most of the prior studies were conducted using in vitro models such as BV2 cells, primary microglia, or brain slices in culture, which may not accurately reflect microglia physiology in adult individuals. Here we employed an in vivo mouse model of selective innate immune activation by intracerebroventricular injection of lipopolysaccharides (ICV-LPS) to determine the role of the voltage-gated Kv1.3 channel in LPS-induced M1-like microglial activation. Using microglia acutely isolated from adult brains, we detected Kv1.3 and Kir2.1 currents, and found that ICV-LPS increased the current density and RNA expression of Kv1.3 but did not affect those of Kir2.1. Genetic knockout of Kv1.3 abolished LPS-induced microglial activation exemplified by Iba-1 immunoreactivity and expression of pro-inflammatory mediators such as IL-1β, TNF-α, IL-6, and iNOS. Moreover, Kv1.3 knockout mitigated the LPS-induced impairment of hippocampal long-term potentiation (hLTP), suggesting that Kv1.3 activity regulates pro-inflammatory microglial neurotoxicity. Pharmacological intervention using PAP-1, a small molecule that selectively blocks homotetrameric Kv1.3 channels, achieved anti-inflammatory and hLTP-recovery effects similar to Kv1.3 knockout. We conclude that Kv1.3 is required for microglial M1-like pro-inflammatory activation in vivo. A significant implication of our in vivo data is that Kv1.3 blockers could be therapeutic candidates for neurological diseases where microglia-mediated neurotoxicity is implicated in the pathogenesis.

There is growing recognition regarding the role of intracellular amyloid beta (Aβ) in the Alzheimer's disease process, which has been linked with aberrant signaling and the disruption of protein degradation mechanisms. Most notably, intraneuronal Aβ likely underlies the oxidative stress and mitochondrial dysfunction that have been identified as key elements of disease progression. In this study, we employed fluorescence imaging to explore the ability of a bifunctional small molecule to reduce aggregates of intracellular Aβ and attenuate oxidative stress. Structurally, this small molecule is comprised of a nitroxide spin label linked to an amyloidophilic fluorene and is known as spin-labeled fluorene (SLF). The effect of the SLF on intracellular Aβ accumulation and oxidative stress was measured in MC65 cells, a human neuronal cell line with inducible expression of the amyloid precursor protein and in the N2a neuronal cell line treated with exogenous Aβ. Super-resolution microscopy imaging showed SLF decreases the accumulation of intracellular Aβ. Confocal microscopy imaging of MC65 cells treated with a reactive oxygen species (ROS)-sensitive dye demonstrated SLF significantly reduces the intracellular Aβ-induced ROS signal. In order to determine the contributions of the separate SLF moieties to these protective activities, experiments were also carried out on cells with nitroxides lacking the Aβ targeting domain or fluorene derivatives lacking the nitroxide functionality. The findings support a synergistic effect of SLF in counteracting both the conformational toxicity of both endogenous and exogenous Aβ, its promotion of ROS, and Aβ metabolism. Furthermore, these studies demonstrate an intimate link between ROS production and Aβ oligomer formation.