scholarly journals Galectin-3, A Novel Endogenous Trem2 Ligand, Regulates Inflammatory Response and Aβ Fibrilation in Alzheimer’s Disease

2018 ◽  
Author(s):  
Antonio Boza-Serrano ◽  
Rocío Ruiz ◽  
Raquel Sanchez-Varo ◽  
Yiyi Yang ◽  
Juan García-Revilla ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Microglial Activation ◽  
Direct Interaction ◽  
Nucleotide Polymorphisms ◽  
Preferential Expression ◽  
Increased Risk ◽  
Galectin 3 ◽  
5Xfad Mice

ABSTRACTAlzheimer’s disease (AD) is a progressive neurodegenerative disease in which the formation of extracellular aggregates of amyloid beta (Aβ) peptide, intraneuronal tau neurofibrillary tangles and microglial activation are major pathological hallmarks. One of the key molecules involved in microglial activation is galectin-3 (gal3), and we demonstrate here for the first time a key role of gal3 in AD pathology. Gal3 was highly upregulated in the brains of AD patients and 5xFAD (familial Alzheimer’s disease) mice, and found specifically expressed in microglia associated with Aβ plaques. Single nucleotide polymorphisms in the LGALS3 gene, which encodes gal3, were associated to an increased risk of AD. Gal3 deletion in 5xFAD mice attenuated microglia-associated immune responses, particularly those associated with TLR and TREM2/DAP12 signaling. In vitro data demonstrated the requirement of gal3 to fully activate microglia in response to fibrillar Aβ. Gal3 deletion decreased the Aβ burden in 5xFAD mice and improved cognitive behavior. Electron microscopy of gal3 in AD mice demonstrated i) a preferential expression of gal3 by plaque-associated microglia, ii) its presence in the extracellular space and iii) its association to Aβ plaques. Low concentrations (1 nM) of pure gal3 promoted cross-seeding fibrilization of pure Aβ. Importantly, a single intrahippocampal injection of gal3 along with Aβ monomers in WT mice was sufficient to induce the formation of insoluble Aβ aggregates that were absent when gal3 was lacking. High-resolution microscopy (STORM) demonstrated close co-localization of gal3 and TREM2 in microglial processes, and a direct interaction was shown by a fluorescence anisotropy assay involving the gal3 CRD domain. Furthermore, gal3 stimulated the TREM2-DAP12 signaling pathway. In conclusion, we provide evidence that gal3 is a central regulator of microglial immune response in AD. It drives proinflammatory activation and Aβ aggregation, as well as acting as an endogenous ligand to TREM2, a key receptor driving microglial response under disease conditions. Gal3 inhibition may, hence, be a potential pharmacological approach to counteract AD.

scholarly journals Polymorphisms inHSD17B1: Early Onset and Increased Risk of Alzheimer’s Disease in Women with Down Syndrome

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph H. Lee ◽  
Susan Gurney ◽  
Deborah Pang ◽  
Alexis Temkin ◽  
Naeun Park ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Down Syndrome ◽  
Age At Onset ◽  
Nucleotide Polymorphisms ◽  
Risk Alleles ◽  
Increased Risk ◽  
Estrogen Activity ◽  
Intron 4

Background/Aims. Genetic variants that affect estrogen activity may influence the risk of Alzheimer's disease (AD). In women with Down syndrome, we examined the relation of polymorphisms in hydroxysteroid-17beta-dehydrogenase (HSD17B1) to age at onset and risk of AD.HSD17B1encodes the enzyme 17β-hydroxysteroid dehydrogenase (HSD1), which catalyzes the conversion of estrone to estradiol.Methods. Two hundred and thirty-eight women with DS, nondemented at baseline, 31–78 years of age, were followed at 14–18-month intervals for 4.5 years. Women were genotyped for 5 haplotype-tagging single-nucleotide polymorphisms (SNPs) in theHSD17B1gene region, and their association with incident AD was examined.Results. Age at onset was earlier, and risk of AD was elevated from two- to threefold among women homozygous for the minor allele at 3 SNPs in intron 4 (rs676387), exon 6 (rs605059), and exon 4 inCOASY(rs598126). Carriers of the haplotype TCC, based on the risk alleles for these three SNPs, had an almost twofold increased risk of developing AD (hazard ratio = 1.8, 95% CI, 1.1–3.1).Conclusion. These findings support experimental and clinical studies of the neuroprotective role of estrogen.

scholarly journals RTP801/REDD1 contributes to neuroinflammation severity and memory impairments in Alzheimer’s disease

2021 ◽  
Vol 12 (6) ◽  
Author(s):  
Leticia Pérez-Sisqués ◽  
Anna Sancho-Balsells ◽  
Júlia Solana-Balaguer ◽  
Genís Campoy-Campos ◽  
Marcel Vives-Isern ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Hippocampal Neurons ◽  
Mrna Levels ◽  
Spine Density ◽  
Memory Impairments ◽  
Protein Levels ◽  
Synaptic Markers ◽  
5Xfad Mice

AbstractRTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death. Its downregulation in Parkinson’s and Huntington’s disease models ameliorates the pathological phenotypes. In the context of Alzheimer’s disease (AD), the coding gene for RTP801, DDIT4, is responsive to Aβ and modulates its cytotoxicity in vitro. Also, RTP801 mRNA levels are increased in AD patients’ lymphocytes. However, the involvement of RTP801 in the pathophysiology of AD has not been yet tested. Here, we demonstrate that RTP801 levels are increased in postmortem hippocampal samples from AD patients. Interestingly, RTP801 protein levels correlated with both Braak and Thal stages of the disease and with GFAP expression. RTP801 levels are also upregulated in hippocampal synaptosomal fractions obtained from murine 5xFAD and rTg4510 mice models of the disease. A local RTP801 knockdown in the 5xFAD hippocampal neurons with shRNA-containing AAV particles ameliorates cognitive deficits in 7-month-old animals. Upon RTP801 silencing in the 5xFAD mice, no major changes were detected in hippocampal synaptic markers or spine density. Importantly, we found an unanticipated recovery of several gliosis hallmarks and inflammasome key proteins upon neuronal RTP801 downregulation in the 5xFAD mice. Altogether our results suggest that RTP801 could be a potential future target for theranostic studies since it could be a biomarker of neuroinflammation and neurotoxicity severity of the disease and, at the same time, a promising therapeutic target in the treatment of AD.

scholarly journals The Effect of Alzheimer’s Disease-Associated Genetic Variants on Longevity

2021 ◽  
Vol 12 ◽  
Author(s):  
Niccolò Tesi ◽  
Marc Hulsman ◽  
Sven J. van der Lee ◽  
Iris E. Jansen ◽  
Najada Stringa ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Longevity ◽  
Longevity Risk ◽  
Nucleotide Polymorphisms ◽  
Immune Signaling ◽  
Factors Affecting ◽  
Age Related ◽  
Increased Risk ◽  
Parental Longevity

Human longevity is influenced by the genetic risk of age-related diseases. As Alzheimer’s disease (AD) represents a common condition at old age, an interplay between genetic factors affecting AD and longevity is expected. We explored this interplay by studying the prevalence of AD-associated single-nucleotide-polymorphisms (SNPs) in cognitively healthy centenarians, and replicated findings in a parental-longevity GWAS. We found that 28/38 SNPs that increased AD-risk also associated with lower odds of longevity. For each SNP, we express the imbalance between AD- and longevity-risk as an effect-size distribution. Based on these distributions, we grouped the SNPs in three groups: 17 SNPs increased AD-risk more than they decreased longevity-risk, and were enriched for β-amyloid metabolism and immune signaling; 11 variants reported a larger longevity-effect compared to their AD-effect, were enriched for endocytosis/immune-signaling, and were previously associated with other age-related diseases. Unexpectedly, 10 variants associated with an increased risk of AD and higher odds of longevity. Altogether, we show that different AD-associated SNPs have different effects on longevity, including SNPs that may confer general neuro-protective functions against AD and other age-related diseases.

scholarly journals Cannabidiol and Other Cannabinoids Reduce Microglial Activation In Vitro and In Vivo: Relevance to Alzheimer's Disease

2011 ◽  
Vol 79 (6) ◽  
pp. 964-973 ◽  
Author(s):  
Ana María Martín-Moreno ◽  
David Reigada ◽  
Belén G. Ramírez ◽  
R. Mechoulam ◽  
Nadia Innamorato ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Microglial Activation

scholarly journals A General Approach to Convert Hemicyanine Dyes into Highly Optimized Photoacoustic Scaffolds for Analyte Sensing

2021 ◽  
Author(s):  
Sarah Garder ◽  
Catharine Brady ◽  
Cameron Keeton ◽  
Anuj K Yadav ◽  
Sharath C Mallojjala ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Photoacoustic Imaging ◽  
Disease Model ◽  
Photoacoustic Signal ◽  
Model Of Alzheimer’S Disease ◽  
5Xfad Mice ◽  
The Impact

<p>In the context of deep-tissue disease biomarker detection and analyte sensing of biologically relevant species, the impact of photoacoustic imaging has been profound. However, most photoacoustic imaging agents to date are based on the repurposing of existing fluorescent dye platforms that exhibit non-optimal properties for photoacoustic applications (e.g., high fluorescence quantum yield). Herein, we introduce two effective modifications to the hemicyanine dye to afford PA-HD, a new dye scaffold optimized for photoacoustic probe development. We observed a significant increase in the photoacoustic output, representing an increase in sensitivity of 4.8-fold and a red-shift of the λ<sub>abs</sub> from 690 nm to 745 nm to enable ratiometric imaging. Moreover, to demonstrate the generalizability and utility of our remodeling efforts, we developed three probes using common analyte-responsive triggers for beta-galactosidase activity (PA-HD-Gal), nitroreductase activity (PA-HD-NTR), and hydrogen peroxide (PA-HD-H<sub>2</sub>O<sub>2</sub>). The performance of each probe (responsiveness, selectivity) was evaluated <i>in vitro</i> and <i>in cellulo</i>. To showcase the enhance properties afforded by PA-HD for <i>in vivo</i> photoacoustic imaging, we employed an Alzheimer’s disease model to detect H<sub>2</sub>O<sub>2</sub>. In particular, the photoacoustic signal at 735 nm in the brains of 5xFAD mice (a murine model of Alzheimer’s disease) increased by 1.72 ± 0.20-fold relative to background indicating the presence of oxidative stress, whereas the change in wildtype mice was negligible (1.02 ± 0.14). These results were confirmed via ratiometric calibration which was not possible using the parent HD platform.</p>

scholarly journals The effect of Alzheimer’s disease-associated genetic variants on longevity

2021 ◽  
Author(s):  
Niccolò Tesi ◽  
Marc Hulsman ◽  
Sven J. van der Lee ◽  
Iris E. Jansen ◽  
Najada Stringa ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Longevity ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Immune Signaling ◽  
Age Related ◽  
Increased Risk ◽  
Parental Longevity ◽  
Effect Size Distribution

AbstractThe genetics underlying human longevity is influenced by the genetic risk to develop -or escape- age-related diseases. As Alzheimer’s disease (AD) represents one of the most common conditions at old age, an interplay between genetic factors for AD and longevity is expected.We explored this interplay by studying the prevalence of 38 AD-associated single-nucleotide-polymorphisms (SNPs) identified in AD-GWAS, in self-reported cognitively healthy centenarians, and we replicated findings in the largest GWAS on parental-longevity.We found that 28/38 SNPs identified to associate with increased AD-risk also associated with decreased odds of longevity. For each SNP, we express the imbalance between AD- and longevity-risk as an effect-size distribution. When grouping the SNPs based on these distributions, we found three groups: 17 variants increased AD-risk more than they decreased the risk of longevity (AD-group): these variants were functionally enriched for β-amyloid metabolism and immune signaling, and they were enriched in microglia. 11 variants reported a larger effect on longevity as compared to their AD-effect (Longevity-group): these variants were enriched for endocytosis/immune signaling, and at the cell-type level were enriched in microglia and endothelial cells. Next to AD, these variants were previously associated with other aging-related diseases, including cardiovascular and autoimmune diseases, and cancer. Unexpectedly, 10 variants associated with an increased risk of both AD and longevity (Unexpected-group). The effect of the SNPs in AD- and Longevity-groups replicated in the largest GWAS on parental-longevity, while the effects on longevity of the SNPs in the Unexpected-group could not be replicated, suggesting that these effects may not be robust across different studies.Our study shows that some AD-associated variants negatively affect longevity primarily by their increased risk of AD, while other variants negatively affect longevity through an increased risk of multiple age-related diseases, including AD.

Tetrandrine Ameliorated Alzheimer’s Disease through Suppressing the Inflammatory Activation of Microglia in 5XFAD Mouse

2020 ◽  
Author(s):  
Defang Ren ◽  
Yu Fu ◽  
Li Wang ◽  
Xia Zhong ◽  
Jiyuan Yuan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Apoptosis ◽  
Morris Water Maze Test ◽  
Bv2 Cells ◽  
Inflammatory Activation ◽  
Cox 2 ◽  
5Xfad Mice ◽  
The Brain

Abstract Background Alzheimer’s disease is a neurodegenerative disorder prevalent in aged population. Tetrandrine is a natural metabolite isolated from herbal medicine Stephania tetrandra with various activities. Our previous study showed that tetrandrine can ameliorate acute cognitive impairment in a rat model induced by Aβ 1-42 intra-hippocampus injection. In this study, we further investigated the therapeutic role of tetrandrine in the transgenic 5XFAD mouse, a chronic model of Alzheimer’s disease. Methods High performance liquid chromatography (HPLC) was used to determine the distribution of tetrandrine in brain. 5XFAD mice were treated with intraperitoneal injection of saline or tetrandrine (10, 20 and 40 mg/kg per 2 days) for 2 months. Cognitive ability was measured by Morris water maze test. The distribution of amyloid plaque was determined by immunohistochemistry in the brains. The expression of TNFα, IL-1β, IL-6, COX-2, iNOS and NF-κB were quantified by RT-PCR. In vitro , the inflammatory activation of microglial BV2 cells was checked by secretion of TNFα and IL-1β determined by ESLIA. Proinflammatory factors including TLR4, NF-κB, iNOS and COX-2 were analyzed by Western blot. In PC12-derived neural cells, CCK8 assay was used to determine the cell viability. Flow cytometry was applied to quantify cell apoptosis. Immunofluorescence was used to study the expression of apoptosis-involved protein cleaved Caspase-3 and Bcl-2. Results Tetrandrine can be distributed in the brain after intraperitoneal injection. Injection of tetrandrine significantly improved the cognitive ability of 5XFAD mice in the Morris water maze test. 5XFAD mice receiving tetrandrine showed notably reduced deposition of amyloid plaque in the brain and decreased cell apoptosis in the hippocampus. Further, tetrandrine treatment suppressed the expression of pro-inflammatory cytokines (TNFα, IL-1β, IL-6) and inflammation modulator (COX-2, iNOS, NF-κB) in the brain tissue. In vitro , tetrandrine suppressed Aβ 1-42-induced inflammatory activation of microglial BV2 cells as revealed by decreased secretion of TNFα and IL-1β, and inhibited expression of TLR4, NF-κB, iNOS and COX-2. Treatment of PC12-derived neural cells with conditional medium from Aβ 1-42-stimulated BV2 cells remarkably impaired cell viability and promoted cell apoptosis, which was attenuated by tetrandrine pre-treatment of the BV2 cells. Conclusions Tetrandrine improves the Alzheimer’s disease at least partially through suppressing microgrlia-mediated inflammation and neurotoxicity.

scholarly journals Phagocytosis of full-length Tau oligomers by Actin-remodeling of activated microglia

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Rashmi Das ◽  
Abhishek Ankur Balmik ◽  
Subashchandrabose Chinnathambi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Microglial Activation ◽  
Amyloid Β ◽  
Microscopic Analysis ◽  
Brain Parenchyma ◽  
Full Length ◽  
Size Exclusion ◽  
Tau Oligomers

Abstract Background Alzheimer’s disease is associated with the accumulation of intracellular Tau tangles within neurons and extracellular amyloid-β plaques in the brain parenchyma, which altogether results in synaptic loss and neurodegeneration. Extracellular concentrations of oligomers and aggregated proteins initiate microglial activation and convert their state of synaptic surveillance into a destructive inflammatory state. Although Tau oligomers have fleeting nature, they were shown to mediate neurotoxicity and microglial pro-inflammation. Due to the instability of oligomers, in vitro experiments become challenging, and hence, the stability of the full-length Tau oligomers is a major concern. Methods In this study, we have prepared and stabilized hTau40WT oligomers, which were purified by size-exclusion chromatography. The formation of the oligomers was confirmed by western blot, thioflavin-S, 8-anilinonaphthaalene-1-sulfonic acid fluorescence, and circular dichroism spectroscopy, which determine the intermolecular cross-β sheet structure and hydrophobicity. The efficiency of N9 microglial cells to phagocytose hTau40WT oligomer and subsequent microglial activation was studied by immunofluorescence microscopy with apotome. The one-way ANOVA was performed for the statistical analysis of fluorometric assay and microscopic analysis. Results Full-length Tau oligomers were detected in heterogeneous globular structures ranging from 5 to 50 nm as observed by high-resolution transmission electron microscopy, which was further characterized by oligomer-specific A11 antibody. Immunocytochemistry studies for oligomer treatment were evidenced with A11+ Iba1high microglia, suggesting that the phagocytosis of extracellular Tau oligomers leads to microglial activation. Also, the microglia were observed with remodeled filopodia-like actin structures upon the exposure of oligomers and aggregated Tau. Conclusion The peri-membrane polymerization of actin filament and co-localization of Iba1 relate to the microglial movements for phagocytosis. Here, these findings suggest that microglia modified actin cytoskeleton for phagocytosis and rapid clearance of Tau oligomers in Alzheimer’s disease condition.

scholarly journals Galectin-3: a key player in microglia-mediated neuroinflammation and Alzheimer's disease

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yinyin Tan ◽  
Yanqun Zheng ◽  
Daiwen Xu ◽  
Zhanfang Sun ◽  
Huan Yang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Models ◽  
Neurofibrillary Tangles ◽  
Microglial Activation ◽  
Amyloid Β ◽  
Review Article ◽  
Common Cause ◽  
Galectin 3

AbstractAlzheimer’s disease (AD) is the most common cause of dementia and is characterized by the deposition of extracellular aggregates of amyloid-β (Aβ), the formation of intraneuronal tau neurofibrillary tangles and microglial activation-mediated neuroinflammation. One of the key molecules involved in microglial activation is galectin-3 (Gal-3). In recent years, extensive studies have dissected the mechanisms by which Gal-3 modulates microglial activation, impacting Aβ deposition, in both animal models and human studies. In this review article, we focus on the emerging role of Gal-3 in biology and pathobiology, including its origin, its functions in regulating microglial activation and neuroinflammation, and its emergence as a biomarker in AD and other neurodegenerative diseases. These aspects are important to elucidate the involvement of Gal-3 in AD pathogenesis and may provide novel insights into the use of Gal-3 for AD diagnosis and therapy.

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