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OBJECTIVE: Type 2 diabetes and glucose metabolism have previously been linked to Alzheimer disease (AD). Yet, findings on the relation of glucose metabolism with amyloid-ß and tau pathology later in life remain unclear. RESEARCH DESIGN AND METHODS: We included 288 participants (mean age = 43.1 years, SD = 10.7, range 20-70 years) without dementia, from the Framingham Heart Study, who had available measures of glucose metabolism (i.e., one-time fasting plasma glucose and insulin) and positron emission tomography (PET) measures of amyloid-ß and/or tau 14 years later. We performed linear regression analyses to test associations of plasma glucose (continuously and categorically; elevated defined as >100 mg/dL), plasma insulin, homeostatic model assessment for insulin resistance (HOMA-IR) with amyloid-ß or tau load on PET. When significant, we explored whether age, sex, and APOE ε4 allele carriership (AD genetic risk) modified these associations. RESULTS: Our findings indicated that elevated plasma glucose was associated with greater tau load 14 years later (B [95% CI] = 0.03 [0.01-0.05], P = 0.024 after false discovery rate [FDR] correction) but not amyloid-ß. APOE ε4 carriership modified this association (B [95% CI] = -0.08 [-0.12 to -0.03], P = 0.001), indicating that the association was only present in APOE ε4 noncarriers (n = 225). Plasma insulin and HOMA-IR were not associated with amyloid-ß or τ load 14 years later after FDR correction. CONCLUSIONS: Our findings suggest that glucose metabolism is associated with increased future tau but not amyloid-ß load. This provides relevant knowledge for prevention strategies and prognostics to improve health care.
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BACKGROUND: Cerebral microbleeds (CMB) increase the risk for Alzheimer disease. Current neuroimaging methods that are used to detect CMB are costly and not always accessible. OBJECTIVE: This study aimed to explore whether the digital clock-drawing test (DCT) may provide a behavioral indicator of CMB. METHODS: In this study, we analyzed data from participants in the Framingham Heart Study offspring cohort who underwent both brain magnetic resonance imaging scans (Siemens 1.5T, Siemens Healthcare Private Limited; T2*-GRE weighted sequences) for CMB diagnosis and the DCT as a predictor. Additionally, paper-based clock-drawing tests were also collected during the DCT. Individuals with a history of dementia or stroke were excluded. Robust multivariable linear regression models were used to examine the association between DCT facet scores with CMB prevalence, adjusting for relevant covariates. Receiver operating characteristic (ROC) curve analyses were used to evaluate DCT facet scores as predictors of CMB prevalence. Sensitivity analyses were conducted by further including participants with stroke and dementia. RESULTS: The study sample consisted of 1020 (n=585, 57.35% female) individuals aged 45 years and older (mean 72, SD 7.9 years). Among them, 64 (6.27%) participants exhibited CMB, comprising 46 with lobar-only, 11 with deep-only, and 7 with mixed (lobar+deep) CMB. Individuals with CMB tended to be older and had a higher prevalence of mild cognitive impairment and higher white matter hyperintensities compared to those without CMB (P<.05). While CMB were not associated with the paper-based clock-drawing test, participants with CMB had a lower overall DCT score (CMB: mean 68, SD 23 vs non-CMB: mean 76, SD 20; P=.009) in the univariate comparison. In the robust multiple regression model adjusted for covariates, deep CMB were significantly associated with lower scores on the drawing efficiency (ß=-0.65, 95% CI -1.15 to -0.15; P=.01) and simple motor (ß=-0.86, 95% CI -1.43 to -0.30; P=.003) domains of the command DCT. In the ROC curve analysis, DCT facets discriminated between no CMB and the CMB subtypes. The area under the ROC curve was 0.76 (95% CI 0.69-0.83) for lobar CMB, 0.88 (95% CI 0.78-0.98) for deep CMB, and 0.98 (95% CI 0.96-1.00) for mixed CMB, where the area under the ROC curve value nearing 1 indicated an accurate model. CONCLUSIONS: The study indicates a significant association between CMB, especially deep and mixed types, and reduced performance in drawing efficiency and motor skills as assessed by the DCT. This highlights the potential of the DCT for early detection of CMB and their subtypes, providing a reliable alternative for cognitive assessment and making it a valuable tool for primary care screening before neuroimaging referral.
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Encéfalo , Hemorragia Cerebral , Humanos , Femenino , Masculino , Anciano , Persona de Mediana Edad , Hemorragia Cerebral/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Estudios de Cohortes , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/fisiopatologíaRESUMEN
Aim: Endothelial dysfunction has been associated with both cerebrovascular pathology and Alzheimer's disease (AD). However, the connection between circulating endothelial cells and the risk of AD remains uncertain. The objective was to leverage data from the Framingham Heart Study to investigate various circulating endothelial subtypes and their potential correlations with the risk of AD. Methods: The study conducted data analyses using Cox proportional hazard regression and linear regression methods. Additionally, genome-wide association study (GWAS) was carried out to further explore the data. Results: Among the eleven distinct circulating endothelial subtypes, only circulating endothelial progenitor cells (EPCs) expressing CD34+CD133+ were found to be negatively and dose-dependently associated with reduced AD risk. This association persisted even after adjusting for age, sex, years of education, apolipoprotein E (APOE) ε4 status, and various vascular diseases. Particularly noteworthy was the significant association observed in individuals with hypertension and cerebral microbleeds. Consistently, positive associations were identified between CD34+CD133+ EPCs and specific brain regions, such as higher proportions of circulating CD34+CD133+ cells correlating with increased volumes of white matter and the hippocampus. Additionally, a GWAS study unveiled that CD34+CD133+ cells influenced AD risk specifically in individuals with homozygous genotypes for variants in two stem cell-related genes: kirre like nephrin family adhesion molecule 3 (KIRREL3, rs580382 CC and rs4144611 TT) and exocyst complex component 6B (EXOC6B, rs61619102 CC). Conclusions: The findings suggest that circulating CD34+CD133+ EPCs possess a protective effect and may offer a new therapeutic avenue for AD, especially in individuals with vascular pathology and those carrying specific genotypes of KIRREL3 and EXOC6B genes.
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BACKGROUND: Although cerebrospinal fluid (CSF) amyloid-ß42 peptide (Aß42) and phosphorylated tau (p-tau) and blood p-tau are valuable for differential diagnosis of Alzheimer's disease (AD) from cognitively normal (CN) there is a lack of validated biomarkers for mild cognitive impairment (MCI). OBJECTIVE: This study sought to determine how plasma and CSF protein markers compared in the characterization of MCI and AD status. METHODS: This cohort study included Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who had baseline levels of 75 proteins measured commonly in plasma and CSF (257 total, 46 CN, 143 MCI, and 68 AD). Logistic regression, least absolute shrinkage and selection operator (LASSO) and Random Forest (RF) methods were used to identify the protein candidates for the disease classification. RESULTS: We observed that six plasma proteins panel (APOE, AMBP, C3, IL16, IGFBP2, APOD) outperformed the seven CSF proteins panel (VEGFA, HGF, PRL, FABP3, FGF4, CD40, RETN) as well as AD markers (CSF p-tau and Aß42) to distinguish the MCI from AD [area under the curve (AUC)â=â0.75 (plasma proteins), AUCâ=â0.60 (CSF proteins) and AUCâ=â0.56 (CSF p-tau and Aß42)]. Also, these six plasma proteins performed better than the CSF proteins and were in line with CSF p-tau and Aß42 in differentiating CN versus MCI subjects [AUCâ=â0.89 (plasma proteins), AUCâ=â0.85 (CSF proteins) and AUCâ=â0.89 (CSF p-tau and Aß42)]. These results were adjusted for age, sex, education, and APOEϵ4 genotype. CONCLUSIONS: This study suggests that the combination of 6 plasma proteins can serve as an effective marker for differentiating MCI from AD and CN.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/líquido cefalorraquídeo , Proteínas del Líquido Cefalorraquídeo , Péptidos beta-Amiloides/líquido cefalorraquídeo , Estudios de Cohortes , Proteínas tau/líquido cefalorraquídeo , Disfunción Cognitiva/diagnóstico , Disfunción Cognitiva/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeo , Proteínas Sanguíneas , Fragmentos de Péptidos/líquido cefalorraquídeoRESUMEN
Background: Previous study shows that monocyte chemoattractant protein-1 (MCP-1), which is implicated in the peripheral proinflammatory cascade and blood-brain barrier (BBB) disruption, modulates the genetic risks of AD in established AD loci. Methods: In this study, we hypothesized that blood MCP-1 impacts the AD risk of genetic variants beyond known AD loci. We thus performed a genome-wide association study (GWAS) using the logistic regression via generalized estimating equations (GEE) and the Cox proportional-hazards models to examine the interactive effects between single nucleotide polymorphisms (SNPs) and blood MCP-1 level on AD in three cohorts: the Framingham Heart Study (FHS), Alzheimer's Disease Neuroimaging Initiative (ADNI) and Religious Orders Study/Memory and Aging Project (ROSMAP). Results: We identified SNPs in two genes, neuron navigator 3 (NAV3, also named Unc-53 Homolog 3, rs696468) (p < 7.55×10- 9) and Unc-5 Netrin Receptor C (UNC5C rs72659964) (p < 1.07×10- 8) that showed an association between increasing levels of blood MCP-1 and AD. Elevating blood MCP-1 concentrations increased AD risk and AD pathology in genotypes of NAV3 (rs696468-CC) and UNC5C (rs72659964-AT + TT), but did not influence the other counterpart genotypes of these variants. Conclusions: NAV3 and UNC5C are homologs and may increase AD risk through dysregulating the functions of neurite outgrowth and guidance. Overall, the association of risk alleles of NAV3 and UNC5C with AD is enhanced by peripheral MCP-1 level, suggesting that lowering the level of blood MCP-1 may reduce the risk of developing AD for people with these genotypes.
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INTRODUCTION: The precise apolipoprotein E (APOE) ε4-specific molecular pathway(s) for Alzheimer's disease (AD) risk are unclear. METHODS: Plasma protein modules/cascades were analyzed using weighted gene co-expression network analysis (WGCNA) in the Alzheimer's Disease Neuroimaging Initiative study. Multivariable regression analyses were used to examine the associations among protein modules, AD diagnoses, cerebrospinal fluid (CSF) phosphorylated tau (p-tau), and brain glucose metabolism, stratified by APOE genotype. RESULTS: The Green Module was associated with AD diagnosis in APOE ε4 homozygotes. Three proteins from this module, C-reactive protein (CRP), complement C3, and complement factor H (CFH), had dose-dependent associations with CSF p-tau and cognitive impairment only in APOE ε4 homozygotes. The link among these three proteins and glucose hypometabolism was observed in brain regions of the default mode network (DMN) in APOE ε4 homozygotes. A Framingham Heart Study validation study supported the findings for AD. DISCUSSION: The study identifies the APOE ε4-specific CRP-C3-CFH inflammation pathway for AD, suggesting potential drug targets for the disease.Highlights: Identification of an APOE ε4 specific molecular pathway involving blood CRP, C3, and CFH for the risk of AD.CRP, C3, and CFH had dose-dependent associations with CSF p-Tau and brain glucose hypometabolism as well as with cognitive impairment only in APOE ε4 homozygotes.Targeting CRP, C3, and CFH may be protective and therapeutic for AD onset in APOE ε4 carriers.
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C-reactive protein (CRP) impacts apolipoprotein E4 (ApoE4) allele to increase Alzheimer's disease (AD) risk. However, it is unclear how the ApoE protein and its binding to LRP1 are involved. We found that ApoE2 carriers had the highest but ApoE4 carriers had the lowest concentrations of blood ApoE in both humans and mice; blood ApoE concentration was negatively associated with AD risk. Elevation of peripheral monomeric CRP (mCRP) reduced the expression of ApoE in ApoE2 mice, while it decreased ApoE-LRP1 binding in the brains of ApoE4 mice that was characterized by Proximity Ligation Assay. Both serum ApoE and brain ApoE-LRP1 binding were positively associated with the expression of pericytes that disappeared after mCRP treatment, and negatively associated with brain tauopathy and neuroinflammation in the presence of mCRP. In ApoE-/- mice, mCRP reduced the brain expression levels of synaptophysin and PSD95 and the positive relationship between ApoE-LRP1 binding and synaptophysin or PSD95 expression disappeared. Our study suggests that blood ApoE protects against AD pathogenesis by binding to LRP1 during peripheral chronic inflammation.
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Enfermedad de Alzheimer , Humanos , Ratones , Animales , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Apolipoproteína E2 , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Sinaptofisina/metabolismo , Apolipoproteínas E/metabolismo , Encéfalo/metabolismo , Inflamación/metabolismo , Apolipoproteína E3/metabolismo , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismoRESUMEN
Several studies have shown that an abnormal vascular-immunity link could increase Alzheimer's disease (AD) risk; however, the mechanism is unclear. CD31, also named platelet endothelial cell adhesion molecule (PECAM), is a surface membrane protein of both endothelial and immune cells and plays important roles in the interaction between the vascular and immune systems. In this review, we focus on research regarding CD31 biological actions in the pathological process that may contribute to AD based on the following rationales. First, endothelial, leukocyte and soluble forms of CD31 play multi-roles in regulating transendothelial migration, increasing blood-brain barrier (BBB) permeability and resulting in neuroinflammation. Second, CD31 expressed by endothelial and immune cells dynamically modulates numbers of signaling pathways, including Src family kinases, selected G proteins, and ß-catenin which in turn affect cell-matrix and cell-cell attachment, activation, permeability, survival, and ultimately neuronal cell injury. In endothelia and immune cells, these diverse CD31-mediated pathways act as a critical regulator in the immunity-endothelia-brain axis, thereby mediating AD pathogenesis in ApoE4 carriers, which is the major genetic risk factor for AD. This evidence suggests a novel mechanism and potential drug target for CD31 in the background of genetic vulnerabilities and peripheral inflammation for AD development and progression.
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Enfermedad de Alzheimer , Barrera Hematoencefálica , Humanos , Enfermedad de Alzheimer/metabolismo , Barrera Hematoencefálica/metabolismo , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/genética , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Transducción de Señal , Migración Transendotelial y TransepitelialRESUMEN
Cerebrovascular damage coexists with Alzheimer's disease (AD) pathology and increases AD risk. However, it is unclear whether endothelial progenitor cells reduce AD risk via cerebrovascular repair. By using the Framingham Heart Study (FHS) offspring cohort, which includes data on different progenitor cells, the incidence of AD dementia, peripheral and cerebrovascular pathologies, and genetic data (n = 1,566), we found that elevated numbers of circulating endothelial progenitor cells with CD34+CD133+ co-expressions had a dose-dependent association with decreased AD risk (HR = 0.67, 95% CI: 0.46-0.96, p = 0.03) after adjusting for age, sex, years of education, and APOE ε4. With stratification, this relationship was only significant among those individuals who had vascular pathologies, especially hypertension (HTN) and cerebral microbleeds (CMB), but not among those individuals who had neither peripheral nor central vascular pathologies. We applied a genome-wide association study (GWAS) and found that the number of CD34+CD133+ cells impacted AD risk depending on the homozygous genotypes of two genes: KIRREL3 rs580382 CC carriers (HR = 0.31, 95% CI: 0.17-0.57, p<0.001), KIRREL3 rs4144611 TT carriers (HR = 0.29, 95% CI: 0.15-0.57, p<0.001), and EXOC6B rs61619102 CC carriers (HR = 0.49, 95% CI: 0.31-0.75, p<0.001) after adjusting for confounders. In contrast, the relationship did not exist in their counterpart genotypes, e.g. KIRREL3 TT/CT or GG/GT carriers and EXOC6B GG/GC carriers. Our findings suggest that circulating CD34+CD133+ endothelial progenitor cells can be therapeutic in reducing AD risk in the presence of cerebrovascular pathology, especially in KIRREL3 and EXOC6B genotype carriers.
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INTRODUCTION: It is unknown whether vascular and metabolic diseases assessed in early adulthood are associated with Alzheimer's disease (AD) later in life. METHODS: Association of AD with lipid fractions, glucose, blood pressure, body mass index (BMI), and smoking obtained prospectively from 4932 Framingham Heart Study (FHS) participants across nine quadrennial examinations was evaluated using Cox proportional hazard and Kaplan-Meier models. Age-, sex-, and education-adjusted models were tested for each factor measured at each exam and within three adult age groups (early = 35-50, middle = 51-60, and late = 61-70). RESULTS: A 15 mg/dL increase in high density lipoprotein (HDL) cholesterol was associated with decreased AD risk during early (15.4%, P = 0.041) and middle (17.9%, P = 0.014) adulthood. A 15 mg/dL increase in glucose measured during middle adulthood was associated with 14.5% increased AD risk (P = 0.00029). These findings remained significant after adjusting for treatment. DISCUSSION: Our findings suggest that careful management of cholesterol and glucose beginning in early adulthood can lower AD risk.
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Enfermedad de Alzheimer , Adulto , Humanos , Factores de Riesgo , Colesterol , Estudios Longitudinales , GlucosaRESUMEN
INTRODUCTION: C-Reactive protein (CRP) and monocyte chemoattractant protein-1 (MCP-1) are both implicated in the peripheral proinflammatory cascade and blood-brain barrier (BBB) disruption. Since the blood CRP level increases Alzheimer's disease (AD) risk depending on the apolipoprotein E (APOE) genotype, we hypothesized that the blood MCP-1 level exerts different effects on the AD risk depending on the genotypes. METHODS: Using multiple regression analyses, data from the Framingham Heart Study (n = 2884) and Alzheimer's Disease Neuroimaging Initiative study (n = 231) were analyzed. RESULTS: An elevated blood MCP-1 level was associated with AD risk in major histocompatibility complex, Class II, DR beta 1 (HLA-DRB1) rs9271192-AC/CC (hazard ratio [HR] = 3.07, 95% confidence interval [CI] = 1.50-6.28, p = 0.002) and in APOE ε4 carriers (HR = 3.22, 95% CI = 1.59-6.53, p = 0.001). In contrast, among HLA-DRB1 rs9271192-AA and APOE ε4 noncarriers, blood MCP-1 levels were not associated with these phenotypes. DISCUSSION: Since HLA-DRB1 and APOE are expressed in the BBB, blood MCP-1 released in the peripheral inflammatory cascade may function as a mediator of the effects of HLA-DRB1 rs9271192-AC/CC and APOE ε4 genotypes on AD pathogenesis in the brain via the BBB pathways.
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Enfermedad de Alzheimer , Apolipoproteínas E , Quimiocina CCL2 , Cadenas HLA-DRB1 , Humanos , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/genética , Apolipoproteína E4/genética , Apolipoproteínas E/genética , Quimiocina CCL2/sangre , Genotipo , Cadenas HLA-DRB1/genéticaRESUMEN
Apolipoprotein ε4 (APOE ε4) is the most significant genetic risk factor for late-onset Alzheimer's disease (AD). Elevated blood C-reactive protein (CRP) further increases the risk of AD for people carrying the APOE ε4 allele. We hypothesized that CRP, as a key inflammatory element, could modulate the impact of other genetic variants on AD risk. We selected ten single nucleotide polymorphisms (SNPs) in reported AD risk loci encoding proteins related to inflammation. We then tested the interaction effects between these SNPs and blood CRP levels on AD incidence using the Cox proportional hazards model in UK Biobank (n = 279,176 white participants with 803 incident AD cases). The five top SNPs were tested for their interaction with different CRP cutoffs for AD incidence in the Framingham Heart Study (FHS) Generation 2 cohort (n = 3009, incident AD = 156). We found that for higher concentrations of serum CRP, the AD risk increased for SNP genotypes in 3 AD-associated genes (SPI1, CD33, and CLU). Using the Cox model in stratified genotype analysis, the hazard ratios (HRs) for the association between a higher CRP level (≥10 vs. <10 mg/L) and the risk of incident AD were 1.94 (95% CI: 1.33-2.84, p < 0.001) for the SPI1 rs1057233-AA genotype, 1.75 (95% CI: 1.20-2.55, p = 0.004) for the CD33 rs3865444-CC genotype, and 1.76 (95% CI: 1.25-2.48, p = 0.001) for the CLU rs9331896-C genotype. In contrast, these associations were not observed in the other genotypes of these genes. Finally, two SNPs were validated in 321 Alzheimer's Disease Neuroimaging (ADNI) Mild Cognitive Impairment (MCI) patients. We observed that the SPI1 and CD33 genotype effects were enhanced by elevated CRP levels for the risk of MCI to AD conversion. Furthermore, the SPI1 genotype was associated with CSF AD biomarkers, including t-Tau and p-Tau, in the ADNI cohort when the blood CRP level was increased (p < 0.01). Our findings suggest that elevated blood CRP, as a peripheral inflammatory biomarker, is an important moderator of the genetic effects of SPI1 and CD33 in addition to APOE ε4 on AD risk. Monitoring peripheral CRP levels may be helpful for precise intervention and prevention of AD for these genotype carriers.
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Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/genética , Proteína C-Reactiva , Apolipoproteína E4/genética , Proteínas tau/genética , Genotipo , Biomarcadores , Apolipoproteínas E/genética , Lectina 3 Similar a Ig de Unión al Ácido Siálico/genéticaRESUMEN
Background: It remains unclear whether persistent loneliness is related to brain structures that are associated with cognitive decline and development of Alzheimer's disease (AD). This study aimed to investigate the relationships between different loneliness types, cognitive functioning, and regional brain volumes. Methods: Loneliness was measured longitudinally, using the item from the Center for Epidemiologic Studies Depression Scale in the Framingham Heart Study, Generation 3, with participants' average age of 46·3 ± 8·6 years. Robust regression models tested the association between different loneliness types with longitudinal neuropsychological performance (n = 2,609) and regional magnetic resonance imaging brain data (n = 1,829) (2002-2019). Results were stratified for sex, depression, and Apolipoprotein E4 (ApoE4). Findings: Persistent loneliness, but not transient loneliness, was strongly associated with cognitive decline, especially memory and executive function. Persistent loneliness was negatively associated with temporal lobe volume (ß = -0.18, 95%CI [-0.32, -0.04], P = 0·01). Among women, persistent loneliness was associated with smaller frontal lobe (ß = -0.19, 95%CI [-0.38, -0.01], P = 0·04), temporal lobe (ß = -0.20, 95%CI [-0.37, -0.03], P = 0·02), and hippocampus volumes (ß = -0.23, 95%CI [-0.40, -0.06], P = 0·007), and larger lateral ventricle volume (ß = 0.15, 95%CI [0.02, 0.28], P = 0·03). The higher cumulative loneliness scores across three exams, the smaller parietal, temporal, and hippocampus volumes and larger lateral ventricle were evident, especially in the presence of ApoE4. Interpretation: Persistent loneliness in midlife was associated with atrophy in brain regions responsible for memory and executive dysfunction. Interventions to reduce the chronicity of loneliness may mitigate the risk of age-related cognitive decline and AD. Funding: US National Institute on Aging.
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Introduction: Human study shows that elevated C-reactive protein (CRP) in blood impacts apolipoprotein E (APOE) ε4, but not APOE ε3 or APOE ε2, genotype to increase the risk of Alzheimer's disease (AD). However, whether CRP is directly involved in cellular AD pathogenesis and in which type of neuronal cells of APOE ε4 carriers are unknown. Methods: We aimed to use different primary neuronal cells and investigate if CRP induces cellular AD pathology depending on APOE genotypes. Here the different primary neuronal cells from the different APOE genotype knock-in mice cortex were isolated and used. Results: Monomeric CRP (mCRP) increased amyloid beta production and, in parallel, induced tau phosphorylation in addition to their related proteins in the primary neurons in a pattern of APOE ε4 > APOE ε3 > APOE ε2 in a dose- and time-dependent manner. Consistently, mCRP induced the staining of other neurodegenerative biomarkers, including Fluoro-Jade B stain (FjB), TUNEL and Cleaved Caspase-3, in primary neurons in a similar pattern of APOE ε4 > APOE ε3 > APOE ε2. In contrast, pentameric CRP (pCRP) had a tendency to induce cellular AD pathology but did not reach statistical significance. On the other hand, it is intriguing that regardless of APOE genotype, mCRP did not influence the expressions of Iba-1 and CD68 in primary microglia or the expression of glial fibrillary acidic protein in primary astrocytes, and additionally mCRP did not affect the secretions of interleukin (IL)-1α, IL-1ß, and tumor necrosis factor α from these cells. Discussion: This is the first report to demonstrate that mCRP directly induces cellular AD pathogenesis in neurons in an APOE genotype-dependent pattern, suggesting that mCRP plays a role as a mediator involved in the APOE ε4-related pathway for AD during chronic inflammation. Highlights: Pentameric C-reactive protein (pCRP) can be dissociated irreversibly to form free subunits or monomeric CRP (mCRP) during and after the acute phase.mCRP increased amyloid beta production in the primary neurons in a pattern of apolipoprotein E (APOE) ε4 > APOE ε3 > APOE ε2 in a dose-dependent manner.mCRP induced the expression of phosphorylated tau in the primary neurons in a pattern of APOE ε4 > APOE ε3 > APOE ε2 in a dose- and time-dependent manner.mCRP plays an important mediator role in the APOE ε4-related pathway of Alzheimer's disease risk.
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In chronic peripheral inflammation, endothelia in brain capillary beds could play a role for the apolipoprotein E4 (ApoE4)-mediated risk for Alzheimer's disease (AD) risk. Using human brain tissues, here we demonstrate that the interactions of endothelial CD31 with monomeric C-reactive protein (mCRP) versus ApoE were linked with shortened neurovasculature for AD pathology and cognition. Using ApoE knock-in mice, we discovered that intraperitoneal injection of mCRP, via binding to CD31 on endothelial surface and increased CD31 phosphorylation (pCD31), leading to cerebrovascular damage and the extravasation of T lymphocytes into the ApoE4 brain. While mCRP was bound to endothelial CD31 in a dose- and time-dependent manner, knockdown of CD31 significantly decreased mCRP binding and altered the expressions of vascular-inflammatory factors including vWF, NF-κB and p-eNOS. RNAseq revealed endothelial pathways related to oxidative phosphorylation and AD pathogenesis were enhanced, but endothelial pathways involving in epigenetics and vasculogenesis were inhibited in ApoE4. This is the first report providing some evidence on the ApoE4-mCRP-CD31 pathway for the cross talk between peripheral inflammation and cerebrovasculature leading to AD risk.
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Enfermedad de Alzheimer/metabolismo , Apolipoproteínas E/metabolismo , Proteína C-Reactiva/metabolismo , Células Endoteliales/metabolismo , Genotipo , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Transducción de Señal/genética , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Animales , Apolipoproteína E4/metabolismo , Apolipoproteínas E/genética , Encéfalo/metabolismo , Proteína C-Reactiva/administración & dosificación , Estudios de Casos y Controles , Células Cultivadas , Femenino , Técnicas de Sustitución del Gen , Técnicas de Silenciamiento del Gen , Humanos , Inflamación/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados para ApoE , Persona de Mediana Edad , Fosforilación Oxidativa/efectos de los fármacos , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/genética , Factores de Riesgo , Transducción de Señal/efectos de los fármacosRESUMEN
OBJECTIVE: Previous research has shown that elevated blood C-reactive protein (CRP) is associated with increased Alzheimer's disease (AD) risk only in apoliprotein E4 genotype (APOE ε4) allele carriers. The objective of this study was to examine the interactive effects of plasma CRP and apoliprotein E (APOE) genotype on cognition and AD biomarkers. METHODS: Data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study was analyzed, including APOE genotype; plasma CRP concentrations; diagnostic status (i.e., MCI and dementia due to AD); Mini-Mental State Exam (MMSE) and Clinical Dementia Rating (CDR) Dementia Staging Instrument; cerebral spinal fluid (CSF) concentrations of amyloid-ß peptide (Aß42), total tau (t-Tau) and phosphorylated tau (p-Tau); and amyloid (AV45) PET imaging. Multivariable regression analyses tested the associations between plasma CRP and APOE on cognitive and biomarker outcomes. RESULTS: Among 566 ADNI participants, 274 (48.4%) had no, 222 (39.2%) had one, and 70 (12.4%) had two APOE ε4 alleles. Only among participants who had two APOE ε4 alleles, elevated CRP was associated with lower MMSE at baseline [ß (95%CI): -0.52 ( -1.01, -0.12)] and 12-month follow-up [ß (95%CI): -1.09 (-1.88, -0.17)] after adjusting for sex, age and education. The interaction of two APOE ε4 alleles and elevated plasma CRP was associated with increased CSF levels of t-Tau (ß = +11.21, SE = 3.37, p < 0.001) and p-Tau (ß = +2.74, SE = 1.14, p < 0.01). Among those who had no APOE ε4 allele, elevated CRP was associated with decreased CSF t-Tau and p-Tau. These effects were stronger at 12-month follow-up. CONCLUSIONS: CRP released during peripheral inflammation could be a mediator in APOE ε4 related AD neurodegeneration and serve as a drug target for AD.
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INTRODUCTION: The relationship between persistent loneliness and Alzheimer's disease (AD) is unclear. We examined the relationship between different types of mid-life loneliness and the development of dementia and AD. METHODS: Loneliness was assessed in cognitively normal adults using one item from the Center for Epidemiologic Studies Depression Scale. We defined loneliness as no loneliness, transient loneliness, incident loneliness,or persistent loneliness, and applied Cox regression models and Kaplan-Meier plots with dementia and AD as outcomes (n = 2880). RESULTS: After adjusting for demographics, social network, physical health, and apolipoprotein E ε4, persistent loneliness was associated with higher (hazard ratio [HR], 1.91; 95% confidence interval [CI] 1.25-2.90; P < .01), and transient loneliness with lower (HR, 0.34; 95% CI 0.14-0.84; P < .05), risk of dementia onset, compared to no loneliness. Results were similar for AD risk. DISCUSSION: Persistent loneliness in mid-life is an independent risk factor for dementia and AD, whereas recovery from loneliness suggests resilience to dementia risk.
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Envejecimiento/fisiología , Enfermedad de Alzheimer/epidemiología , Voluntarios Sanos/psicología , Soledad/psicología , Enfermedad de Alzheimer/psicología , Escalas de Valoración Psiquiátrica Breve , Demencia/epidemiología , Demencia/psicología , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Factores de RiesgoRESUMEN
BACKGROUND: Depression and Apolipoprotein E4 (APOE4) are associated with decreased cognitive function and differences in brain structure. OBJECTIVE: This study investigated whether APOE4 status moderates the association between elevated depressive symptoms, cognitive function, and brain structure. METHODS: Stroke- and dementia-free participants (nâ=â1,968) underwent neuropsychological evaluation, brain MRI, and depression screening. Linear and logistic regression was used to examine all associations. Secondary analyses were performed using interaction terms to assess effect modification by APOE4 status. RESULTS: Elevated depressive symptoms were associated with lower cognitive performance in several domains. In stratified analyses, elevated depressive symptoms were associated with poorer visual short- and long-term memory performance for APOE4â+âparticipants. Elevated depressive symptoms were not associated with any brain structure in this study sample. CONCLUSION: Elevated depressive symptoms impact cognitive function in non-demented individuals. Having the APOE4 allele may exacerbate the deleterious effects of elevated depressive symptoms on visual memory performance. Screening for elevated depressive symptoms in both research studies and clinical practice may be warranted to avoid false positive identification of neurodegeneration, particularly among those who are APOE4â+â.
Asunto(s)
Apolipoproteína E4/genética , Cognición/fisiología , Disfunción Cognitiva/etiología , Depresión/psicología , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Predisposición Genética a la Enfermedad , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana EdadRESUMEN
Importance: Preclinical studies suggest that amylin has a U-shaped dose-response association with risk of Alzheimer disease (AD). The association of plasma amylin with AD in humans is unknown. Objectives: To measure amylin concentration in plasma by using enzyme-linked immunosorbent assay and to study the association between plasma amylin, incidence of AD, and brain structure in humans. Design, Setting, and Participants: This cohort study used data from the Framingham Heart Study offspring cohort from 1998 to 2015. Using a Monte Carlo approach, participants were divided into 3 plasma amylin concentration groups: (1) low (<75 pmol/L), (2) high (75-2800 pmol/L), and (3) extremely high (≥2800 pmol/L). Data analyses were conducted October 5, 2017, to December 18, 2018. Exposures: Baseline plasma amylin concentrations at examination 7. Main Outcomes and Measures: Incidence of dementia or AD and brain volumetric measures from structural magnetic resonance imaging data. Results: From the Framingham Heart Study offspring cohort, 3061 participants (mean [SD] age at baseline, 61.0 [9.5] years; 1653 [54.0%] women) who had plasma amylin measurements, dementia incidence, and brain volume measurements on record were included in this study. The distribution of plasma amylin concentrations was highly skewed (median [interquartile range], 7.5 [4.6-18.9] pmol/L; mean [SD], 302.3 [1941.0] pmol/L; range, 0.03-44â¯623.7 pmol/L). Compared with the low plasma amylin concentration group, the high plasma amylin concentration group had a lower rate of AD incidence (2.3% vs 5.6%; P = .04), but the extremely high plasma amylin concentration group had a higher rate of AD incidence (14.3%; P < .001). After adjusting for age, sex, education, body mass index, diabetes, cardiovascular disease, high-density lipoprotein level, and APOE4, high plasma amylin was not associated with decreased AD risk (hazard ratio, 0.42 [95% CI, 0.16-1.14]; P = .09) but was positively associated with volume of gray matter in the temporal lobe (ß = 0.17 [SE, 0.05]; P < .001). In contrast, extremely high plasma amylin concentration was associated with a higher AD risk (hazard ratio, 2.51 [95% CI, 1.38-4.57]; P = .003) but not associated with temporal lobe volume (ß = 0.02 [SE, 0.07]; P = .82). Conclusions and Relevance: This study found that plasma amylin concentration was associated with AD incidence and brain structure with a U-shaped pattern. These findings are consistent with preclinical findings that suggest amylin is a neuropeptide that is physiological; however, at extremely high concentrations, it may lead to amylin aggregation and therefore may be a risk factor for AD.