Antigen-specific age-related memory CD8 T cells induce and track Alzheimer's-like neurodegeneration.

Cerebral (Aß) plaque and (pTau) tangle deposition are hallmarks of Alzheimer's disease (AD), yet are insufficient to confer complete AD-like neurodegeneration experimentally. Factors acting upstream of Aß/pTau in AD remain unknown, but their identification could enable earlier diagnosis and more effective treatments. T cell abnormalities are emerging AD hallmarks, and CD8 T cells were recently found to mediate neurodegeneration downstream of tangle deposition in hereditary neurodegeneration models. The precise impact of T cells downstream of Aß/pTau, however, appears to vary depending on the animal model. Our prior work suggested that antigen-specific memory CD8 T ("hiT") cells act upstream of Aß/pTau after brain injury. Here, we examine whether hiT cells influence sporadic AD-like pathophysiology upstream of Aß/pTau. Examining neuropathology, gene expression, and behavior in our hiT mouse model we show that CD8 T cells induce plaque and tangle-like deposition, modulate AD-related genes, and ultimately result in progressive neurodegeneration with both gross and fine features of sporadic human AD. T cells required Perforin to initiate this pathophysiology, and IFNγ for most gene expression changes and progression to more widespread neurodegenerative disease. Analogous antigen-specific memory CD8 T cells were significantly elevated in the brains of human AD patients, and their loss from blood corresponded to sporadic AD and related cognitive decline better than plasma pTau-217, a promising AD biomarker candidate. We identify an age-related factor acting upstream of Aß/pTau to initiate AD-like pathophysiology, the mechanisms promoting its pathogenicity, and its relevance to human sporadic AD.

Elevated lipopolysaccharide binding protein in Alzheimer's disease patients with APOE3/E3 but not APOE3/E4 genotype.

Introduction: The 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. Methods: In 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. Results: LBP 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). Discussion: These 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.

The neuropathological landscape of small vessel disease and Lewy pathology in a cohort of Hispanic and non-Hispanic White decedents with Alzheimer disease.

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.

A Mechanistic Spectrum of O-H Bond Cleavage Observed for Reactions of Phenols with a Manganese Superoxo Complex.

Reaction of a rare and well-characterized MnIII-superoxo species, Mn(BDPBrP)(O2⋅) (1, H2BDPBrP=2,6-bis((2-(S)-di(4-bromo)phenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine), with 4-dimethylaminophenol at -80 °C proceeds via concerted proton electron transfer (CPET) to produce a MnIII-hydroperoxo complex, Mn(BDPBrP)(OOH) (2), alongside 4-dimethylaminophenoxy radical; whereas, upon treatment with 4-nitrophenol, complex 1 undergoes a proton transfer process to afford a MnIV-hydroperoxo complex, [Mn(BDPBrP)(OOH)]+ (3). Intriguingly, the reactions of 1 with 4-chlorophenol and 4-methoxyphenol follow two routes of CPET and sequential proton and electron transfer to furnish complex 2 in the end. UV-vis and EPR spectroscopic studies coupled with DFT calculations provided support for this wide mechanistic spectrum of activating various phenol O-H bonds by a single MnIII-superoxo complex, 1.

Efficacy and safety of odevixibat in patients with Alagille syndrome (ASSERT): a phase 3, double-blind, randomised, placebo-controlled trial.

BACKGROUND: In patients with Alagille syndrome, cholestasis-associated clinical features can include high serum bile acids and severe pruritus that can necessitate liver transplantation. We aimed to evaluate the efficacy and safety of the ileal bile acid transporter inhibitor odevixibat versus placebo in patients with Alagille syndrome. METHODS: The ASSERT study was a phase 3, double-blind, randomised, placebo-controlled trial that enrolled patients at 21 medical centres or hospitals in ten countries (Belgium, France, Germany, Italy, Malaysia, the Netherlands, Poland, Türkiye, the UK, and the USA). Eligible patients had a genetically confirmed diagnosis of Alagille syndrome, a history of significant pruritus, and elevated serum bile acids. Patients were randomly assigned (2:1) to receive oral odevixibat 120 µg/kg per day or placebo for 24 weeks (in a block size of six and stratified by age: <10 years and ≥10 years to <18 years) via a web-based system. Patients, clinicians, study staff, and people analysing the data were masked to treatment allocation. The primary efficacy endpoint was change in caregiver-reported scratching score (on the PRUCISION instrument; range 0-4) from baseline to weeks 21-24. The prespecified key secondary efficacy endpoint was change in serum bile acid concentration from baseline to the average of weeks 20 and 24. Outcomes were analysed in patients who received at least one dose of study drug (the full analysis set for efficacy outcomes and the safety analysis set for safety outcomes). This trial is registered on ClinicalTrials.gov (NCT04674761) and EudraCT (2020-004011-28), and is completed. FINDINGS: Between Feb 26, 2021, and Sept 9, 2022, 52 patients were randomly assigned to receive odevixibat (n=35) or placebo (n=17), all of whom were included in the analysis sets. The median age was 5·5 years (IQR 3·2 to 8·9). 27 (52%) of 52 patients were male and 25 (48%) were female. The mean scratching score was elevated at baseline in both groups (2·8 [SD 0·5] for odevixibat vs 3·0 [0·6] for placebo). Mean scratching scores at weeks 21-24 were 1·1 (0·9) for odevixibat and 2·2 (1·0) for placebo, representing a least-squares (LS) mean change of -1·7 (95% CI -2·0 to -1·3) for odevixibat and -0·8 (-1·3 to -0·3) for placebo, which was significantly greater for odevixibat than for placebo (difference in LS mean change from baseline -0·9 [95% CI -1·4 to -0·3]; p=0·0024). Odevixibat also resulted in significantly greater reductions in mean serum bile acids from baseline versus placebo (237 µmol/L [SD 115] with odevixibat vs 246 µmol/L [121] with placebo) to the average of weeks 20 and 24 (149 µmol/L [102] vs 271 µmol/L [167]; LS mean change -90 µmol/L [95% CI -133 to -48] with odevixibat vs 22 µmol/L [-35 to 80] with placebo; difference in LS mean change -113 µmol/L [95% CI -179 to -47]; p=0·0012). The most common treatment-emergent adverse events were diarrhoea (ten [29%] of 35 patients in the odevixibat group vs one [6%] of 17 in the placebo group) and pyrexia (eight [23%] vs four [24%]). Seven patients had serious treatment-emergent adverse events during the treatment period: five (14%) in the odevixibat group and two (12%) in the placebo group. No patients discontinued treatment and there were no deaths. INTERPRETATION: Odevixibat could be an efficacious non-surgical intervention to improve pruritus, reduce serum bile acids, and enhance the standard of care in patients with Alagille syndrome. Longer-term safety and efficacy data of odevixibat in this population are awaited from the ongoing, open-label ASSERT-EXT study. FUNDING: Albireo Pharma, an Ipsen company.

An international multidisciplinary consensus on pediatric metabolic dysfunction-associated fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is highly prevalent in children and adolescents, particularly those with obesity. NAFLD is considered a hepatic manifestation of the metabolic syndrome due to its close associations with abdominal obesity, insulin resistance, and atherogenic dyslipidemia. Experts have proposed an alternative terminology, metabolic dysfunction-associated fatty liver disease (MAFLD), to better reflect its pathophysiology. This study aimed to develop consensus statements and recommendations for pediatric MAFLD through collaboration among international experts. METHODS: A group of 65 experts from 35 countries and six continents, including pediatricians, hepatologists, and endocrinologists, participated in a consensus development process. The process encompassed various aspects of pediatric MAFLD, including epidemiology, mechanisms, screening, and management. FINDINGS: In round 1, we received 65 surveys from 35 countries and analyzed these results, which informed us that 73.3% of respondents agreed with 20 draft statements while 23.8% agreed somewhat. The mean percentage of agreement or somewhat agreement increased to 80.85% and 15.75%, respectively, in round 2. The final statements covered a wide range of topics related to epidemiology, pathophysiology, and strategies for screening and managing pediatric MAFLD. CONCLUSIONS: The consensus statements and recommendations developed by an international expert panel serve to optimize clinical outcomes and improve the quality of life for children and adolescents with MAFLD. These findings emphasize the need for standardized approaches in diagnosing and treating pediatric MAFLD. FUNDING: This work was funded by the National Natural Science Foundation of China (82070588, 82370577), the National Key R&D Program of China (2023YFA1800801), National High Level Hospital Clinical Research Funding (2022-PUMCH-C-014), the Wuxi Taihu Talent Plan (DJTD202106), and the Medical Key Discipline Program of Wuxi Health Commission (ZDXK2021007).

Growth Patterns of 11-29-Month-Old Children Consuming Young Child Formula: Secondary Analysis of a Randomized, Controlled Study.

INTRODUCTION: The impact of young child formula (YCF) consumption on children's growth, particularly under suboptimal conditions, has scarcely been studied. In the current study, weight-for-age (WAZ), length-for-age (LAZ), and BMI-for-age (BAZ) z-score development was evaluated in children from five different countries (n = 668) who participated in a double-blind, randomized, controlled trial. METHODS: The children (1-3 years old) were randomized to one of two intervention YCFs (with presence or absence of prebiotics and n-3 LCPUFAs) during 52 weeks of intervention. Additional stratified analyses evaluated the growth patterns of underweight, overweight, or stunted children. RESULTS: No apparent differences in anthropometric measurements were observed between the intervention groups. In both YCF intervention groups, mean WAZ, LAZ and BAZ development was indicative of adequate growth during the intervention period. Stratified analyses showed stable WAZ and BAZ development among children with a healthy weight or overweight at baseline. Among underweight and stunted children, normalization in mean weight (∼1 SD) and length (∼0.8 SD) gain, respectively, was observed. CONCLUSION: The current study suggests that consumption of YCF, either or not containing prebiotics and n-3 LCPUFAs, is associated with adequate growth among young children. This association may depend on the child's baseline nutritional status. Future studies to assess the potential role of YCF in supporting adequate weight/length gain among children at risk for undernutrition are warranted.

Profiling Intact Glycosphingolipids with Automated Structural Annotation and Quantitation from Human Samples with Nanoflow Liquid Chromatography Mass Spectrometry.

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.

Magneto-Structural Correlation of Five-Coordinate Trigonal Bipyramidal High Spin Cobalt(II) Complexes.

Here, we combined magnetometry, multi-frequency electronic paramagnetic resonance, and wave function based ab initio calculations to investigate magnetic properties of two high spin Co(II) complexes Co(BDPRP) (BDPRP=2,6-bis((2-(S)-di(4-R)phenylhydroxylmethyl-1-pyrrolidi-nyl)methyl)pyridine, R=H for 8; R=tBu for 9). Complexes 8 and 9 featuring effective D3h symmetry were found to possess D=24.0 and 32.0 cm-1, respectively, in their S=3/2 ground states of 1 e ' ' d x z / y z 4 1 e ' d x y / x 2 - y 2 2 1 a 1 ' d z 2 1 ${{\left(1{{\rm e}}^{{\rm { {^\prime}}}{\rm { {^\prime}}}}\right({d}_{xz/yz}\left)\right)}^{4}{\left(1{{\rm e}}^{{\rm { {^\prime}}}}\right({d}_{{xy/{x}^{2}-y}^{2}}\left)\right)}^{2}{\left(1{{\rm a}}_{1}^{{\rm { {^\prime}}}}\right({d}_{{z}^{2}}\left)\right)}^{1}}$ . Ligand field analyses revealed that the low-lying d-d excited states make either positive or vanishing contributions to D. Hence, total positive D values were measured for 8 and 9, as well as related D3h high spin Co(II) complexes. In contrast, negative D values are usually observed for C3v congeners. In-depth analyses suggested that lowering symmetry from D3h to C3v induces orbital mixing between 1 e d x z / y z ${1{\rm e}\left({d}_{xz/yz}\right)}$ and 2 e d x y / x 2 - y 2 ${2{\rm e}\left({d}_{{xy/{x}^{2}-y}^{2}}\right)}$ and admixes excited state 4 A 2 1 e → 2 e ${{}^{4}{{\rm A}}_{2}\left(1e\to 2e\right)}$ into the ground state. Both factors turn the total D value progressively negative with the increasing distance (δ) of the Co(II) center out of the equatorial plane. Therefore, δ determines the sign and magnitude of final D values of five-coordinate trigonal bipyramidal S=3/2 Co(II) complexes as measured for a series of such species with varying δ.

Effects of Sex and Western Diet on Spatial Lipidomic Profiles for the Hippocampus, Cortex, and Corpus Callosum in Mice Using MALDI MSI.

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.

Antigen-specific age-related memory CD8 T cells induce and track Alzheimer's-like neurodegeneration.

Cerebral (Aß) plaque and (pTau) tangle deposition are hallmarks of Alzheimer's disease (AD), yet are insufficient to confer complete AD-like neurodegeneration experimentally. Factors acting upstream of Aß/pTau in AD remain unknown, but their identification could enable earlier diagnosis and more effective treatments. T cell abnormalities are emerging AD hallmarks, and CD8 T cells were recently found to mediate neurodegeneration downstream of tangle deposition in hereditary neurodegeneration models. The precise impact of T cells downstream of Aß/fibrillar pTau, however, appears to vary depending on the animal model used. Our prior work suggested that antigen-specific memory CD8 T (" hi T") cells act upstream of Aß/pTau after brain injury. Here we examine whether hi T cells influence sporadic AD-like pathophysiology upstream of Aß/pTau. Examining neuropathology, gene expression, and behavior in our hi T mouse model we show that CD8 T cells induce plaque and tangle-like deposition, modulate AD-related genes, and ultimately result in progressive neurodegeneration with both gross and fine features of sporadic human AD. T cells required Perforin to initiate this pathophysiology, and IFNγ for most gene expression changes and progression to more widespread neurodegenerative disease. Analogous antigen-specific memory CD8 T cells were significantly elevated in the brains of human AD patients, and their loss from blood corresponded to sporadic AD and related cognitive decline better than plasma pTau-217, a promising AD biomarker candidate. Our work is the first to identify an age-related factor acting upstream of Aß/pTau to initiate AD-like pathophysiology, the mechanisms promoting its pathogenicity, and its relevance to human sporadic AD. Significance Statement: This study changes our view of Alzheimer's Disease (AD) initiation and progression. Mutations promoting cerebral beta-amyloid (Aß) deposition guarantee rare genetic forms of AD. Thus, the prevailing hypothesis has been that Aß is central to initiation and progression of all AD, despite contrary animal and patient evidence. We show that age-related T cells generate neurodegeneration with compelling features of AD in mice, with distinct T cell functions required for pathological initiation and neurodegenerative progression. Knowledge from these mice was applied to successfully predict previously unknown features of human AD and generate novel tools for its clinical management.

Ketogenic diet and BHB rescue the fall of long-term potentiation in an Alzheimer's mouse model and stimulates synaptic plasticity pathway enzymes.

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-ß (Aß) 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.

Multi-omics Characterization of Epigenetic and Genetic Risk of Alzheimer Disease in Autopsied Brains from two Ethnic Groups.

Background: Both genetic variants and epigenetic features contribute to the risk of Alzheimer's disease (AD). We studied the AD association of CpG-related single nucleotide polymorphisms (CGS), which act as the hub of both the genetic and epigenetic effects, in Hispanics decedents and generalized the findings to Non-Hispanic Whites (NHW) decedents. Methods: First, we derived the dosage of the CpG site-creating allele of multiple CGSes in each 1 KB window across the genome and we conducted a sliding window association test with clinical diagnosis of AD in 7,155 Hispanics (3,194 cases and 3,961 controls) using generalized linear mixed models with the adjustment of age, sex, population structure, genomic relationship matrix, and genotyping batches. Next, using methylation and bulk RNA-sequencing data from the dorsolateral pre-frontal cortex in 150 Hispanics 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 checked their enriched pathways. Results: We identified six genetic loci in Hispanics with CGS dosage associated with AD at genome-wide significance levels: ADAM20 (Score=55.2, P= 4.06×10 -8 ), between VRTN (Score=-19.6, P= 1.47×10 -8 ) and SYNDIG1L (Score=-37.7, P= 2.25×10 -9 ), SPG7 (16q24.3) (Score=40.5, 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 genome-wide significant in NHW. Except for ADAM20 , CGSes in all the other five loci were associated with Hispanic 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 all the other five loci affected downstream RNA expression in the Hispanics ( P <0.05), and methylation at VRTN and TOMM40 were also associated with RNA expression in NHW. Gene expression in these six loci were also regulated by CpG sites in genes that were enriched in the neuron projection and synapse (FDR<0.05). Conclusions: We identified six CpG associated genetic loci associated with AD in Hispanics, harboring both genetic and epigenetic risks. However, their downstream effects on mRNA expression maybe ethnic specific and different from NHW.

ATG16L1 rs2241880/T300A increases susceptibility to perianal Crohn's disease: An updated meta-analysis on inflammatory bowel disease risk and clinical outcomes.

BACKGROUND: ATG16L1 plays a fundamental role in the degradative intracellular pathway known as autophagy, being a mediator of inflammation and microbial homeostasis. The variant rs2241880 can diminish these capabilities, potentially contributing to inflammatory bowel disease (IBD) pathogenesis. OBJECTIVES: To perform an updated meta-analysis on the association between ATG16L1 rs2241880 and IBD susceptibility by exploring the impact of age, ethnicity, and geography. Moreover, to investigate the association between rs2241880 and clinical features. METHODS: Literature searches up until September 2022 across 7 electronic public databases were performed for all case-control studies on ATG16L1 rs2241880 and IBD. Pooled odds ratios (ORP ) and 95% CI were calculated under the random effects model. RESULTS: Our analyses included a total of 30,606 IBD patients, comprising 21,270 Crohn's disease (CD) and 9336 ulcerative colitis (UC) patients, and 33,329 controls. ATG16L1 rs2241880 was significantly associated with CD susceptibility, where the A allele was protective (ORP : 0.74, 95% CI: 0.72-0.77, p-value: <0.001), while the G allele was a risk factor (ORP : 1.23, 95% CI: 1.09-1.39, p-value: 0.001), depending on the minor allele frequencies observed in this multi-ancestry study sample. rs2241880 was predominantly relevant in Caucasians from North America and Europe, and in Latin American populations. Importantly, CD patients harbouring the G allele were significantly more predisposed to perianal disease (ORP : 1.21, 95% CI: 1.07-1.38, p-value: 0.003). CONCLUSIONS: ATG16L1 rs2241880 (G allele) is a consistent risk factor for IBD in Caucasian cohorts and influences clinical outcomes. As its role in non-Caucasian populations remains ambiguous, further studies in under-reported populations are necessary.

Galectin-3 aggravates microglial activation and tau transmission in tauopathy.

Alzheimer's disease is characterized by the accumulation of amyloid-ß plaques, aggregation of hyperphosphorylated tau (pTau), and microglia activation. Galectin-3 (Gal3) is a ß-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.

The ketone body ß-hydroxybutyrate shifts microglial metabolism and suppresses amyloid-ß oligomer-induced inflammation in human microglia.

Fatty acids are metabolized by ß-oxidation within the "mitochondrial ketogenic pathway" (MKP) to generate ß-hydroxybutyrate (BHB), a ketone body. BHB can be generated by most cells but largely by hepatocytes following exercise, fasting, or ketogenic diet consumption. BHB has been shown to modulate systemic and brain inflammation; however, its direct effects on microglia have been little studied. We investigated the impact of BHB on Aß oligomer (AßO)-stimulated human iPS-derived microglia (hiMG), a model relevant to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AßO with proinflammatory activation, which was mitigated by BHB at physiological concentrations of 0.1-2 mM. AßO stimulated glycolytic transcripts, suppressed genes in the ß-oxidation pathway, and induced over-expression of AD-relevant p46Shc, an endogenous inhibitor of thiolase, actions that are expected to suppress MKP. AßO also triggered mitochondrial Ca2+ increase, mitochondrial reactive oxygen species production, and activation of the mitochondrial permeability transition pore. BHB potently ameliorated all the above mitochondrial changes and rectified the MKP, resulting in reduced inflammasome activation and recovery of the phagocytotic function impaired by AßO. These results indicate that microglia MKP can be induced to modulate microglia immunometabolism, and that BHB can remedy "keto-deficiency" resulting from MKP suppression and shift microglia away from proinflammatory mitochondrial metabolism. These effects of BHB may contribute to the beneficial effects of ketogenic diet intervention in aged mice and in human subjects with mild AD.

The neuropathological landscape of Hispanic and non-Hispanic White decedents with Alzheimer disease.

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 Aß (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.

Cholesterol, Amyloid Beta, Fructose, and LPS Influence ROS and ATP Concentrations and the Phagocytic Capacity of HMC3 Human Microglia Cell Line.

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 (AßO), lipopolysaccharide (LPS), and fructose individually and in combination. HMC3 microglia demonstrated changes in morphology consistent with activation when treated with the combination of Chol + AßO + fructose + LPS. Multiple treatments increased the cellular content of Chol and cholesteryl esters (CE), but only the combination treatment of Chol + AßO + fructose + LPS increased mitochondrial Chol content. Microglia treated with combinations containing Chol + AßO had lower apolipoprotein E (ApoE) secretion, with the combination of Chol + AßO + fructose + LPS having the strongest effect. Combination treatment with Chol + AßO + 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 + AßO + 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.

Transcriptomic and glycomic analyses highlight pathway-specific glycosylation alterations unique to Alzheimer's disease.

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.