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Microglia significantly contribute to the pathophysiology of Alzheimer's disease but an effective microglia-targeted therapeutic approach is not yet available clinically. The potassium channels Kv1.3 and Kir2.1 play important roles in regulating immune cell functions and have been implicated by in vitro studies in the 'M1-like pro-inflammatory' or 'M2-like anti-inflammatory' state of microglia, respectively. We here found that amyloid-β oligomer-induced expression of Kv1.3 and Kir2.1 in cultured primary microglia. Likewise, ex vivo microglia acutely isolated from the Alzheimer's model 5xFAD mice co-expressed Kv1.3 and Kir2.1 as well as markers traditionally associated with M1 and M2 activation suggesting that amyloid-β oligomer induces a microglial activation state that is more complex than previously thought. Using the orally available, brain penetrant small molecule Kv1.3 blocker PAP-1 as a tool, we showed that pro-inflammatory and neurotoxic microglial responses induced by amyloid-β oligomer required Kv1.3 activity in vitro and in hippocampal slices. Since we further observed that Kv1.3 was highly expressed in microglia of transgenic Alzheimer's mouse models and human Alzheimer's disease brains, we hypothesized that pharmacological Kv1.3 inhibition could mitigate the pathology induced by amyloid-β aggregates. Indeed, treating APP/PS1 transgenic mice with a 5-month oral regimen of PAP-1, starting at 9 months of age, when the animals already manifest cognitive deficits and amyloid pathology, reduced neuroinflammation, decreased cerebral amyloid load, enhanced hippocampal neuronal plasticity, and improved behavioural deficits. The observed decrease in cerebral amyloid deposition was consistent with the in vitro finding that PAP-1 enhanced amyloid-β uptake by microglia. Collectively, these results provide proof-of-concept data to advance Kv1.3 blockers to Alzheimer's disease clinical trials. [ABSTRACT FROM AUTHOR]

There is an urgent unmet need for new therapeutics for Alzheimer's disease (AD), the most common cause of dementia in the elderly. Therapeutic approaches targeting amyloid-β (Aβ) and its downstream toxicities have become major strategies in AD drug development. We have taken a rational design approach and synthesized a class of tricyclic pyrone (TP) compounds that show anti-Aβ and other neuroprotective actions. The in vivo efficacy of a lead TP named CP2 to ameliorate AD-like pathologies has been shown in mouse models. Here we report the selection and initial characterization of a new lead TP70, which exhibited an anti-Aβ therapeutic index even higher than CP2. Moreover, TP70 was able to reduce oxidative stress, inhibit acyl-coenzyme A:cholesterol acyltransferase (ACAT), and upregulate the expression of ATP-binding cassette subfamily A, member 1 (ABCA1), actions considered neuroprotective in AD. TP70 further showed excellent pharmacokinetic properties, including brain penetration and oral availability. When administered to 5xFAD mice via intraperitoneal or oral route, TP70 enhanced the overall solubility and decreased the level of cerebral Aβ, including both fibrillary and soluble Aβ species. Interestingly, TP70 enhanced N-methyl-D-aspartate (NMDA) receptor-mediated excitatory post-synaptic potential (EPSP) in the hippocampal CA1 area, increased the magnitude of NMDA-dependent hippocampal long-term potentiation (LTP), a cellular model of learning and memory, and prevented the Aβ oligomer-impaired LTP. Significantly, a single dose of TP70 administered to aged 5xFAD mice was effective in mitigating the impaired LTP induction, recorded at 24 h after administration. Our results support a potential of TP70 in clinical development for AD in view of its synergistic neuroprotective actions, ability to positively modulate NMDA receptor-mediated hippocampal plasticity, and favorable pharmacokinetic properties in rodents. [ABSTRACT FROM AUTHOR]

Amyloid-β (Aβ) protein causes neurotoxicity and its abnormal aggregation into amyloid is a pathological hallmark of Alzheimer's disease (AD). Cellular proteins able to interact with Aβ or its precursor, AβPP (amyloid-β protein precursor), may regulate Aβ production and neurotoxicity. We identified a brain-enriched type I transmembrane protein, tomoregulin (TR), that directly binds Aβ and Aβ oligomers (AβO). TR co-immunoprecipitated with Aβ and AβO in cultured cells and co-localized with amyloid plaques and intraneuronal Aβ in the 5xFAD AD mouse model. TR was also enriched in astrocytic processes reactive to amyloid plaques. Surface plasmon resonance spectroscopy studies showed that the extracellular domain of TR binds to AβO with a high affinity (KD = 76.8 nM). Electron paramagnetic resonance spectroscopy also demonstrated a physical interaction between spin-labeled Aβ and the TR extracellular domain in solution. Furthermore, TR also interacted with AβPP and enhanced its cleavage by α-secretase. Both cellular expression of TR and application of recombinant TR extracellular domain protected N2a neurons from AβO-induced neuronal death. These data provide first evidence that neuronal and astrocytic expression of TR is intimately related to Aβ metabolism and toxicity, and could be neuroprotective through its direct interaction with Aβ and AβPP. [ABSTRACT FROM AUTHOR]

MECP2, an X-linked gene encoding the epigenetic factor methyl-CpG-binding protein-2, is mutated in Rett syndrome (RTT) and aberrantly expressed in autism. Most children affected by RTT are heterozygous Mecp2-/+ females whose brain function is impaired postnatally due to MeCP2 deficiency. Recent studies suggest a role of glia in causing neuronal dysfunction via a non-cell-autonomous effect in RTT. Here we report a potent neurotoxic activity in the conditioned medium (CM) obtained from Mecp2-null microglia. Hippocampal neurons treated withCMfrom Mecp2-null microglia showed an abnormal stunted and beaded dendritic morphology, and signs of microtubule disruption and damage of postsynaptic glutamatergic components within 24 h. We identified that the toxic factor in the CM is glutamate, because (1) Mecp2-null microglia released a fivefold higher level of glutamate, (2) blockage of microglial glutamate synthesis by a glutaminase inhibitor abolished the neurotoxic activity, (3) blockage of microglial glutamate release by gap junction hemichannel blockers abolished the neurotoxic activity, and (4) glutamate receptor antagonists blocked the neurotoxicity of the Mecp2- null microglia CM. We further identified that increased levels of glutaminase and connexin 32 in Mecp2-null microglia are responsible for increased glutamate production and release, respectively. In contrast, the CM from highly pure Mecp2-null astrocyte cultures showed no toxic effect. Our results suggest that microglia may influence the onset and progression of RTT and that microglia glutamate synthesis or release could be a therapeutic target for RTT. [ABSTRACT FROM AUTHOR]

MECP2, an X-linked gene encoding the epigenetic factor methyl-CpG-binding protein-2, is mutated in Rett syndrome (RTT) and aberrantly expressed in autism. Most children affected by RTT are heterozygous Mecp2+/- females whose brain function is impaired postnatally due to MeCP2 deficiency. While prior functional investigations of MeCP2 have focused exclusively on neurons and have concluded the absence of MeCP2 in astrocytes, here we report that astrocytes express MeCP2, and MeCP2 deficiency in astrocytes causes significant abnormalities in BDNF regulation, cytokine production, and neuronal dendritic induction, effects that may contribute to abnormal neurodevelopment. In addition, we show that the MeCP2 deficiency state can progressively spread at least in part via gap junction communications between mosaic Mecp2-/+ astrocytes in a novel non-cell-autonomous mechanism. This mechanism may lead to the pronounced loss of MeCP2 observed selectively in astrocytes in mouse Mecp2-/+ brain, which is coincident with phenotypic regression characteristic of RTT. Our results suggest that astrocytes are viable therapeutic targets for RTT and perhaps regressive forms of autism. [ABSTRACT FROM AUTHOR]

New advances in polarized light microscopy were used to image Congo red-stained cerebral amyloidosis in sharp relief. The rotating-polarizer method was used to separate the optical effects of transmission, linear birefringence, extinction, linear dichroism, and orientation of the electric dipole transition moments and to display them as false-color maps. These effects are typically convolved in an ordinary polarized light microscope. In this way, we show that the amyloid deposits in Alzheimer's disease plaques contain structurally disordered centers, providing clues to mechanisms of crystallization of amyloid in vivo. Comparisons are made with plaques from tissues of subjects having Down's syndrome and a prion disease. In plaques characteristic of each disease, the Congo red molecules are oriented radially. The optical orientation in amyloid deposited in blood vessels from subjects having cerebral amyloid angiopathy was 900 out of phase from that in the plaques, suggesting that the fibrils run tangentially with respect to the circumference of the blood vessels. Our result supports an early model in which Congo red molecules are aligned along the long fiber axis and is in contrast to the most recent binding models that are based on computation. This investigation illustrates that the latest methods for the optical analysis of heterogeneous substances are useful for in situ study of amyloid. [ABSTRACT FROM AUTHOR]

Carbonyl stress from products of lipid peroxidation, such as 4-hydroxynonenal (HNE), and products of sugars in diabetes mellitus, such as methylglyoxal (MG) and glyoxal (G), may contribute to neurodegeneration in Alzheimer's disease (AD). We tested the hypothesis that these carbonyls alter the proposed central pathogenic mechanism of AD, intracellular amyloid-β (Aβ)-mediated cytotoxicity, using a human neuroblastoma cell line that conditionally expresses carboxy-terminal fragments (CTFs) of the amyloid precursor protein. HNE was a potent cytotoxin, whereas G was mildly cytotoxic; cytotoxicity from each was independent of Aβ/CTF expression and not altered by α-tocopherol. In contrast, MG cytotoxicity was enhanced by the induced expression of Aβ/CTFs and suppressed by α-tocopherol. α-tocopherol cytoprotection was accompanied by decreased Aβ/CTF aggregation. G also promoted β/CTF aggregation but by mechanisms unaffected byα-tocopherol treatment. Our findings showed that Aβ/CTF aggregation and cytotoxicity may be profoundly altered by aldehydes associated with diabetes and that in the case of MG, this process is suppressed by α-tocopherol. Moreover, our results suggest that while intracellular aggregation of Aβ/CTFs may be necessary for the development of toxicity attributable to their expression in this model, the presence of high-molecular weight aggregated Aβ/CTFs does not invariably lead to cytotoxicity. [ABSTRACT FROM AUTHOR]

Background: High density lipoproteins (HDL) are primarily known for their critical role in regulating cellular cholesterol concentrations via their capacity to induce cholesterol efflux from cells. HDL are also carriers of apolipoprotein E (ApoE), which is the strongest known genetic risk factor for AD. The main objective of this study was to determine the cholesterol efflux capacity of HDL particles isolated from plasma of APOE genotyped AD patients vs. age‐matched cognitively normal controls, and to characterize plasma lipoprotein profiles using size exclusion chromatography. Method: HDL particles were isolated from plasma samples of 10 AD patients (n=5 APOE3/E3, n=5 APOE3/E4) and 5 cognitively normal controls (n=5 APOE3/E3) using sequential ultracentrifugation followed by size exclusion chromatography. FPLC chromatograms were processed to adjust baseline values and calculate area under the curve (AUC) for LDL, HDL, and albumin using UNICORN 5.0 software. AUCs were used to estimate the relative distributions of fractions, including small and large HDL, and peak elution volume was used to estimate particle size most abundant in each fraction. Cholesterol efflux capacity of the isolated HDL particles was determined in PBMC‐derived macrophages using a fluorescently labeled cholesterol assay kit. Result: HDL from AD patients had dramatically reduced cholesterol efflux capacity compared with controls (36.0% ± 1.2% vs. 26.0% ± 1.2%, P<0.0001), with no difference between AD patients by APOE genotype (APOE3/E3, 25.9% ± 0.9%; APOE3/E4, 26.5% ±1.3%; P=0.21). There were no significant differences in the relative distributions or average particle sizes of HDL, LDL, albumin, or large and small HDL between patients and controls. These results suggest neither the amount nor size distribution of HDL particles is adequate to detect the main difference driving the diminished cholesterol efflux capacity of HDL particles from AD patients. Conclusion: The results of this study support previous findings of decreased cholesterol efflux capacity of HDL in AD patients, and underscore the necessity for additional analyses to characterize the compositional differences driving this diminished functional capacity and to further understand HDL's role in AD pathology. [ABSTRACT FROM AUTHOR]

Background: Macrophages are phagocytic cells that play an essential role in the clearance of cellular debris. Microglia, specialized phagocytic cells of the brain, likewise play a critical role in the clearance of cellular debris, particularly amyloid beta, which is involved in the pathogenesis of Alzheimer's disease. However, activated macrocytic cells displaying a pro‐inflammatory or M1 phenotype are associated with neuroinflammation and have a reduced capacity to phagocytose. Studies have shown that the ability of microglia to remove amyloid beta is influenced by their cellular cholesterol clearance capacity. However, it is not known whether activated macrocytic cells have inherently reduced cholesterol efflux capacity (CEC). Method: In this study the CEC of human THP‐1 monocytes differentiated into macrophages using phorbol‐12‐myristate‐13‐acetate (PMA), achieving a resting state, were polarized to an M1 activated state using lipopolysaccharide (LPS) and interferon gamma (IFNγ) and an M2 alternatively activated state using interleukin 4 (IL4) and macrophage colony‐stimulating factor (M‐CSF). The capacity to remove fluorescently‐labeled cholesterol was compared across all three macrophage states at 3 time points, in the presence and absence of the cholesterol acceptor high‐density lipoprotein (HDL). HDL particles were isolated by ultracentrifugation followed by size exclusion chromatography and added at a concentration of 0.1 mg/mL. Macrophage phenotype was confirmed by qPCR using primers to amplify TNF‐α, IL‐1β, IL‐6, CD206, ARG1 and IGF1. Result: Compared to 12 and 72 hours, 36 hours of cytokine treatment resulted in the largest reduction in CEC in M1 and M2 macrophages compared to resting macrophages. The CEC of M1 and M2 macrophages was 50% and 60% lower, respectively, than the CEC of resting macrophages. This reduction was apparent in both the presence and absence of HDL acceptor. Conclusion: These findings suggest that in conditions of macrocytic activation, such as Alzheimer's disease, macrocytic cells involved in the clearance of cellular debris have a diminished capacity to efflux cholesterol. Whether this reduction of CEC in activated versus resting macrophages is also observed in activated versus resting microglia, and whether it is related to reduced phagocytic capacity and/or involved in the pathogenesis of Alzheimer's disease needs to be determined in future studies. [ABSTRACT FROM AUTHOR]

Diet is inextricably linked to human health and biological functionality. Reduced cognitive function among other health issues has been correlated with a western diet (WD) in mouse models, indicating that increases in neurodegeneration could be fueled in part by a poor diet. In this study, we use matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to spatially map the lipidomic profiles of male and female mice that were fed a high-fat, high-sucrose WD for a period of 7 weeks. Our findings concluded that the cortex and corpus callosum showed significant lipid variation by WD in female mice, while there was little to no variation in the hippocampus, regardless of sex. On the other hand, lipid profiles were significantly affected by sex in all regions. Overall, 83 lipids were putatively identified in the mouse brain; among them, HexCer-(40:1;O3) and PE(34:0) were found to have the largest statistical difference based on diet for female mice in the cortex and corpus callosum, respectively. Additional lipid changes are noted and can serve as a metric for understanding the brain's metabolomic response to changes in diet, particularly as it relates to disease. [ABSTRACT FROM AUTHOR]

Presents a study which found that neurotoxicity from innate immune response is greatest with targeted replacement (TR) of E4 allele of apolipoprotein E (APOE) gene and is mediated by microglial p38MAPK. Cytokine secretion by TR APOE microglia; p38MAPK activation in TR APOE microglia; Conclusion and significance of the study.

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. [ABSTRACT FROM AUTHOR]

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. A Ketogenic Diet (KD) that improves memory in aged C57BL/6 mice is tested in APP/PS1 Alzheimer's mice. Seven months KD rescues Long-Term-Potentiation to wild-type levels, as does a one-hour soak with 3 mM Betahydroxybutyrate. KD increases synaptic pathways but does not alter Aβ amyloid. [ABSTRACT FROM AUTHOR]

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 < 0.05). Upregulation of MGAT1 and B4GALT1 involved in complex N-linked glycan formation and galactosylation, respectively, were reflected by increased concentrations of corresponding N-glycans. Isozyme-specific changes were observed in expression of the polypeptide N-acetylgalactosaminyltransferase (GALNT) family and the alpha-N-acetylgalactosaminide alpha-2,6-sialyltransferase (ST6GALNAC) family of enzymes. Several glycolipid-specific genes (UGT8, PIGM) were upregulated. The critical transcription factors regulating the expression of N-glycosylation and elongation genes were predicted and found to include STAT1 and HSF5. The miRNA predicted to be involved in regulating N-glycosylation and elongation glycosyltransferases were has-miR-1-3p and has-miR-16-5p, respectively. Our findings provide an overview of glycosylation pathways affected by AD and potential regulators of glycosyltransferase expression that deserve further validation and suggest that glycosylation changes occurring in the brains of AD dementia individuals are highly pathway-specific and unique to AD. [ABSTRACT FROM AUTHOR]

Microglia are the immune cells in the central nervous system (CNS) and become pro-inflammatory/activated in Alzheimer's disease (AD). Cell surface glycosylation plays an important role in immune cells; however, the N-glycosylation and glycosphingolipid (GSL) signatures of activated microglia are poorly understood. Here, we study comprehensive combined transcriptomic and glycomic profiles using human induced pluripotent stem cells-derived microglia (hiMG). Distinct changes in N-glycosylation patterns in amyloid-β oligomer (AβO) and LPS-treated hiMG were observed. In AβO-treated cells, the relative abundance of bisecting N-acetylglucosamine (GlcNAc) N-glycans decreased, corresponding with a downregulation of MGAT3. The sialylation of N-glycans increased in response to AβO, accompanied by an upregulation of genes involved in N-glycan sialylation (ST3GAL4 and 6). Unlike AβO-induced hiMG, LPS-induced hiMG exhibited a decreased abundance of complex-type N-glycans, aligned with downregulation of mannosidase genes (MAN1A1, MAN2A2, and MAN1C1) and upregulation of ER degradation related-mannosidases (EDEM1-3). Fucosylation increased in LPS-induced hiMG, aligned with upregulated fucosyltransferase 4 (FUT4) and downregulated alpha-L-fucosidase 1 (FUCA1) gene expression, while sialofucosylation decreased, aligned with upregulated neuraminidase 4 (NEU4). Inhibition of sialyation and fucosylation in AβO- and LPS-induced hiMG alleviated pro-inflammatory responses. However, the GSL profile did not exhibit significant changes in response to AβO or LPS activation. AβO- and LPS- specific glycosylation changes could contribute to impaired microglia function, highlighting glycosylation pathways as potential therapeutic targets for AD., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. Additional Declarations: No competing interests reported.

The disorder and heterogeneity of low-molecular-weight amyloid-beta oligomers (AβOs) underlie their participation in multiple modes of cellular dysfunction associated with the etiology of Alzheimer's disease (AD). The lack of specified conformational states in these species complicates efforts to select or design small molecules to targeting discrete pathogenic states. Furthermore, targeting AβOs alone may be therapeutically insufficient, as AD progresses as a multifactorial, self-amplifying cascade. To address these challenges, we have screened the activity of seven new candidates that serve as Paramagnetic Amyloid Ligand (PAL) candidates. PALs are bifunctional small molecules that both remodel the AβO structure and localize a potent antioxidant that mimics the activity of SOD within live cells. The candidates are built from either a stilbene or curcumin scaffold with nitroxyl moiety to serve as catalytic antioxidants. Measurements of PAL AβO binding and remolding along with assessments of bioactivity allow for the extraction of useful SAR information from screening data. One candidate (HO-4450; PMT-307), with a six-membered nitroxyl ring attached to a stilbene ring, displays the highest potency in protecting against cell-derived Aβ. A preliminary low-dose evaluation in AD model mice provides evidence of modest treatment effects by HO-4450. The results for the curcumin PALs demonstrate that the retention of the native curcumin phenolic groups is advantageous to the design of the hybrid PAL candidates. Finally, the PAL remodeling of AβO secondary structures shows a reasonable correlation between a candidate's bioactivity and its ability to reduce the fraction of antiparallel β-strand.

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., (© 2023 Wiley Periodicals LLC.)

Introduction: We 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., Methods: All 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., Results: HV 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., Discussion: Neurodegeneration 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., Competing Interests: All authors report no disclosures relevant to the manuscript. Author disclosures are available in the supporting information., (© 2022 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.)

Introduction: There 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., Methods: The 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., Results: Partial 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., Discussion: The results of this study suggest that serum glycoprofiling may be a promising approach for biomarker discovery., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.)

Various condensation and ring-closing reactions were used for the syntheses of 3-[(alkylamino)methylene]-6-methylpyri-dine-2,4(1 H ,3 H )-diones, bicyclic pyridinones, and tricyclic morpholinopyrones. For instance, 3-[(dialkylamino)methylene]-6-methylpyridine-2,4(1 H ,3 H )-diones were synthesized from the condensation of dialkylamines and 3-formyl-4-hydroxy-6-methylpyridin-2(1 H )-one. 3-Formyl-4-hydroxy-6-methylpyridin-2(1 H )-one, derived from 3-formyl-4-hydroxy-6-methylpyridin-2(1 H )-one, was used to construct a number of bicyclic pyridinones via a one-pot Knoevenagal and intramolecular lactonization reaction. Tricyclic morpholinopyrones were assembled from a dialkylation reaction involving a dinucleophile, 3-amino-4-hydroxy-6-methyl-2 H -pyran-2-one, and a dielectrophile, trans -3,6-dibromocyclohexene. Depending on the reaction conditions, isomers of the tricyclic molecules can be selectively produced, and their chemical structures were unequivocally determined using single-crystal X-ray analyses and 2D COSY spectroscopy. The fluorescently active bicyclic pyridinone compounds show longer absorption (368-430 nm; maximum) and emission wavelengths (450-467 nm) than those of 7-amino-4-methylcoumarin (AMC; λ abs,max = 350 nm; λ em = 430 nm) suggesting these molecules, such as 3-(2-aminoacetyl)-7-methyl-2 H -pyrano[3,2- c ]pyridine-2,5(6 H )-dione, can be employed as fluorescence activity based probes for tracing biological pathways.

Background: Functional polymorphisms in tumor necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) can affect immune response, inflammation, tissue injury, and possibly the susceptibility to Alzheimer disease (AD)., Objective: To evaluate the association between promoter region polymorphisms in the TNF-alpha and IL-10 genes and risk of late-onset AD in older white subjects., Design: Community-based case-control study., Setting: Group Health Cooperative of Puget Sound., Participants: White subjects (n = 265) meeting criteria for probable or definite AD (cases) and white control subjects (n = 347) (controls)., Main Outcome Measures: Genotyping results for TNF-alpha, IL-10, and apolipoprotein E (APOE) genotyping., Results: The TNF-alpha -863 A allele was associated with reduced odds of developing AD, and the test for trend suggested that having 2 copies of the A allele further reduces the risk (odds ratios [C/C, reference], 0.66 for C/A and 0.58 for A/A; P = .04). Because of linkage disequilibrium in the TNF-alpha region, we constructed promoter region haplotypes as defined by single nucleotide polymorphisms at positions -863 and -308. Based on knowledge of TNF-alpha protein production, we ordered the haplotypes based on apparent increasing transcriptional activity. After adjusting for age, education, and the presence of the APOE epsilon4 genotype, the test for trend showed increasing odds of AD with increasing transcriptional activity (P = .02). The IL-10 -1082 and IL-10 -592 allele and genotype frequencies were not significantly different between cases and controls., Conclusion: Variation in the TNF-alpha promoter region, or possibly polymorphisms in nearby genes, could affect cerebral inflammatory response and the risk of late-onset AD.