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INTRODUCTION: Despite increasing evidence of a role of rare genetic variation in the risk of Alzheimer's disease (AD), limited attention has been paid to its contribution to AD-related biomarker traits indicative of AD-relevant pathophysiological processes. METHODS: We performed whole-exome gene-based rare-variant association studies (RVASs) of 17 AD-related traits on whole-exome sequencing (WES) data generated in the European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery (EMIF-AD MBD) study (n = 450) and whole-genome sequencing (WGS) data from ADNI (n = 808). RESULTS: Mutation screening revealed a novel probably pathogenic mutation (PSEN1 p.Leu232Phe). Gene-based RVAS revealed the exome-wide significant contribution of rare coding variation in RBKS and OR7A10 to cognitive performance and protection against left hippocampal atrophy, respectively. DISCUSSION: The identification of these novel gene-trait associations offers new perspectives into the role of rare coding variation in the distinct pathophysiological processes culminating in AD, which may lead to identification of novel therapeutic and diagnostic targets.
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Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/diagnóstico , Exoma/genética , Estudios de Asociación Genética , Fenotipo , BiomarcadoresRESUMEN
INTRODUCTION: Neurofilament light (NfL), chitinase-3-like protein 1 (YKL-40), and neurogranin (Ng) are biomarkers for Alzheimer's disease (AD) to monitor axonal damage, astroglial activation, and synaptic degeneration, respectively. METHODS: We performed genome-wide association studies (GWAS) using DNA and cerebrospinal fluid (CSF) samples from the EMIF-AD Multimodal Biomarker Discovery study for discovery, and the Alzheimer's Disease Neuroimaging Initiative study for validation analyses. GWAS were performed for all three CSF biomarkers using linear regression models adjusting for relevant covariates. RESULTS: We identify novel genome-wide significant associations between DNA variants in TMEM106B and CSF levels of NfL, and between CPOX and YKL-40. We confirm previous work suggesting that YKL-40 levels are associated with DNA variants in CHI3L1. DISCUSSION: Our study provides important new insights into the genetic architecture underlying interindividual variation in three AD-related CSF biomarkers. In particular, our data shed light on the sequence of events regarding the initiation and progression of neuropathological processes relevant in AD.
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Enfermedad de Alzheimer/genética , Biomarcadores/líquido cefalorraquídeo , Estudio de Asociación del Genoma Completo , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/genética , Anciano , Proteína 1 Similar a Quitinasa-3/genética , Femenino , Humanos , Masculino , Proteínas de Neurofilamentos/genética , Neurogranina/líquido cefalorraquídeoRESUMEN
INTRODUCTION: This study sought to discover and replicate plasma proteomic biomarkers relating to Alzheimer's disease (AD) including both the "ATN" (amyloid/tau/neurodegeneration) diagnostic framework and clinical diagnosis. METHODS: Plasma proteins from 972 subjects (372 controls, 409 mild cognitive impairment [MCI], and 191 AD) were measured using both SOMAscan and targeted assays, including 4001 and 25 proteins, respectively. RESULTS: Protein co-expression network analysis of SOMAscan data revealed the relation between proteins and "N" varied across different neurodegeneration markers, indicating that the ATN variants are not interchangeable. Using hub proteins, age, and apolipoprotein E ε4 genotype discriminated AD from controls with an area under the curve (AUC) of 0.81 and MCI convertors from non-convertors with an AUC of 0.74. Targeted assays replicated the relation of four proteins with the ATN framework and clinical diagnosis. DISCUSSION: Our study suggests that blood proteins can predict the presence of AD pathology as measured in the ATN framework as well as clinical diagnosis.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides/sangre , Biomarcadores/sangre , Proteínas Sanguíneas , Proteómica , Proteínas tau/sangre , Anciano , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/patología , Apolipoproteína E4/sangre , Apolipoproteína E4/genética , Disfunción Cognitiva/sangre , Disfunción Cognitiva/patología , Europa (Continente) , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Dynamic Functional Connectivity (dFC) in the resting state (rs) is considered as a correlate of cognitive processing. Describing dFC as a flow across morphing connectivity configurations, our notion of dFC speed quantifies the rate at which FC networks evolve in time. Here we probe the hypothesis that variations of rs dFC speed and cognitive performance are selectively interrelated within specific functional subnetworks. In particular, we focus on Sleep Deprivation (SD) as a reversible model of cognitive dysfunction. We found that whole-brain level (global) dFC speed significantly slows down after 24h of SD. However, the reduction in global dFC speed does not correlate with variations of cognitive performance in individual tasks, which are subtle and highly heterogeneous. On the contrary, we found strong correlations between performance variations in individual tasks -including Rapid Visual Processing (RVP, assessing sustained visual attention)- and dFC speed quantified at the level of functional sub-networks of interest. Providing a compromise between classic static FC (no time) and global dFC (no space), modular dFC speed analyses allow quantifying a different speed of dFC reconfiguration independently for sub-networks overseeing different tasks. Importantly, we found that RVP performance robustly correlates with the modular dFC speed of a characteristic frontoparietal module.
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Atención/fisiología , Encéfalo/fisiopatología , Disfunción Cognitiva/fisiopatología , Conectoma , Memoria a Corto Plazo/fisiología , Red Nerviosa/fisiopatología , Desempeño Psicomotor/fisiología , Privación de Sueño/fisiopatología , Percepción Visual/fisiología , Adulto , Encéfalo/diagnóstico por imagen , Disfunción Cognitiva/diagnóstico por imagen , Disfunción Cognitiva/etiología , Humanos , Masculino , Red Nerviosa/diagnóstico por imagen , Privación de Sueño/diagnóstico por imagen , Factores de TiempoRESUMEN
BACKGROUND: The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults. METHODS: Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session. RESULTS: Significant MRI site and vendor effects (p â< â.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p â< â1.39E-36). In particular, volumes larger than 200 âmm3 (for amygdalar nuclei) and 300 âmm3 (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε â< â5% and DICE â> â0.80). CONCLUSION: Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.
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Amígdala del Cerebelo/anatomía & histología , Hipocampo/anatomía & histología , Procesamiento de Imagen Asistido por Computador/normas , Neuroimagen/normas , Programas Informáticos , Adulto , Anciano , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Imagen por Resonancia Magnética/normas , Masculino , Persona de Mediana Edad , Neuroimagen/métodos , Reproducibilidad de los ResultadosRESUMEN
PURPOSE/BACKGROUND: Alzheimer disease (AD) is a public health issue because of the low number of symptomatic drugs and the difficulty to diagnose it at the prodromal stage. The need to develop new treatments and to validate sensitive tests for early diagnosis could be met by developing a challenge model reproducing cognitive impairments of AD. Therefore, we implemented a 24-hour sleep deprivation (SD) design on healthy volunteers in a randomized, double-blind, placebo-controlled, crossover study on 36 healthy volunteers. METHODS/PROCEDURE: To validate the SD model, cognitive tests were chosen to assess a transient worsening of cognitive functions after SD and a restoration under modafinil as positive control (one dose of 200 mg). Then, the same evaluations were replicated after 15 days of donepezil (5 mg/d) or memantine (10 mg/d). The working memory (WM) function was assessed by the N-back task and the rapid visual processing (RVP) task. FINDINGS/RESULTS: The accuracy of the N-back task and the reaction time of the RVP revealed the alteration of the WM with SD and its restoration with modafinil (changes in score after SD compared with baseline before SD), respectively, in the placebo group and in the modafinil group (-0.2% and +1.0% of satisfactory answers, P = 0.022; +21.3 and +1.9 milliseconds of reaction time, P = 0.025). Alzheimer disease drugs also tended to reverse this deterioration: the accuracy of the N-back task was more stable through SD (compared with -3.0% in the placebo group, respectively, in the memantine group and in the donepezil group: -1.4% and -1.6%, P = 0.027 and P = 0.092) and RVP reaction time was less impacted (compared with +41.3 milliseconds in the placebo group, respectively, in the memantine group and in the donepezil group: +16.1 and +29.3 milliseconds, P = 0.034 and P = 0.459). IMPLICATIONS/CONCLUSIONS: Our SD challenge model actually led to a worsening of WM that was moderated by both modafinil and AD drugs. To use this approach, the cognitive battery, the vulnerability of the subjects to SD, and the expected drug effect should be carefully considered.
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Enfermedad de Alzheimer/tratamiento farmacológico , Disfunción Cognitiva/tratamiento farmacológico , Voluntarios Sanos/psicología , Memantina/uso terapéutico , Memoria a Corto Plazo/efectos de los fármacos , Privación de Sueño/psicología , Adulto , Enfermedad de Alzheimer/psicología , Estudios Cruzados , Donepezilo/uso terapéutico , Método Doble Ciego , Humanos , Masculino , Modafinilo/uso terapéutico , Modelos Psicológicos , Pruebas Neuropsicológicas , Nootrópicos/uso terapéutico , Tiempo de Reacción/efectos de los fármacosRESUMEN
OBJECTIVE: In this exploratory study, we tested whether electroencephalographic (EEG) rhythms may reflect the effects of a chronic administration (4 weeks) of an anti-amyloid ß-site amyloid precursor protein (APP) cleaving enzyme 1 inhibitor (BACE-1; ER-901356; Eisai Co., Ltd., Tokyo, Japan) in TASTPM (double mutation in APP KM670/671NL and PSEN1 M146V) producing Alzheimer's disease (AD) amyloid neuropathology as compared to wild type (WT) mice. METHODS: Ongoing EEG rhythms were recorded from a bipolar frontoparietal and two monopolar frontomedial (prelimbic) and hippocampal channels in 11 WT Vehicle, 10 WT BACE-1, 10 TASTPM Vehicle, and 11 TASTPM BACE-1 mice (males; aged 8/9 months old at the beginning of treatment). Normalized EEG power (density) was compared between the first day (Day 0) and after 4 weeks (Week 4) of the BACE-1 inhibitor (10 mg/Kg) or vehicle administration in the 4 mouse groups. Frequency and magnitude of individual EEG delta and theta frequency peaks (IDF and ITF) were considered during animal conditions of behaviorally passive and active wakefulness. Cognitive status was not tested. RESULTS: Compared with the WT group, the TASTPM group generally showed a significantly lower reactivity in frontoparietal ITF power during the active over the passive condition (p < 0.05). Notably, there was no other statistically significant effect (e.g., additional electrodes, recording time, and BACE-1 inhibitor). CONCLUSIONS: The above EEG biomarkers reflected differences between the WT and TASTPM groups, but no BACE-1 inhibitor effect. The results suggest an enhanced experimental design with the use of younger mice, longer drug administrations, an effective control drug, and neuropathological amyloid markers.
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Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Precursor de Proteína beta-Amiloide/genética , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Electroencefalografía , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/farmacología , Mutación/genética , Presenilina-1/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Animales , Ácido Aspártico Endopeptidasas/metabolismo , Electrodos , Electromiografía , Ratones Endogámicos C57BL , Ratones Transgénicos , Procesamiento de Señales Asistido por ComputadorRESUMEN
INTRODUCTION: We investigated relations between amyloid-ß (Aß) status, apolipoprotein E (APOE) ε4, and cognition, with cerebrospinal fluid markers of neurogranin (Ng), neurofilament light (NFL), YKL-40, and total tau (T-tau). METHODS: We included 770 individuals with normal cognition, mild cognitive impairment, and Alzheimer's disease (AD)-type dementia from the EMIF-AD Multimodal Biomarker Discovery study. We tested the association of Ng, NFL, YKL-40, and T-tau with Aß status (Aß- vs. Aß+), clinical diagnosis APOE ε4 carriership, baseline cognition, and change in cognition. RESULTS: Ng and T-tau distinguished between Aß+ from Aß- individuals in each clinical group, whereas NFL and YKL-40 were associated with Aß+ in nondemented individuals only. APOE ε4 carriership did not influence NFL, Ng, and YKL-40 in Aß+ individuals. NFL was the best predictor of cognitive decline in Aß+ individuals across the cognitive spectrum. DISCUSSION: Axonal degeneration, synaptic dysfunction, astroglial activation, and altered tau metabolism are involved already in preclinical AD. NFL may be a useful prognostic marker.
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Enfermedad de Alzheimer/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeo , Disfunción Cognitiva/líquido cefalorraquídeo , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Neurogranina/líquido cefalorraquídeo , Proteínas tau/líquido cefalorraquídeo , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides , Apolipoproteína E4/genética , Disfunción Cognitiva/fisiopatología , Femenino , HumanosRESUMEN
INTRODUCTION: Plasma proteins have been widely studied as candidate biomarkers to predict brain amyloid deposition to increase recruitment efficiency in secondary prevention clinical trials for Alzheimer's disease. Most such biomarker studies are targeted to specific proteins or are biased toward high abundant proteins. METHODS: 4001 plasma proteins were measured in two groups of participants (discovery group = 516, replication group = 365) selected from the European Medical Information Framework for Alzheimer's disease Multimodal Biomarker Discovery study, all of whom had measures of amyloid. RESULTS: A panel of proteins (n = 44), along with age and apolipoprotein E (APOE) ε4, predicted brain amyloid deposition with good performance in both the discovery group (area under the curve = 0.78) and the replication group (area under the curve = 0.68). Furthermore, a causal relationship between amyloid and tau was confirmed by Mendelian randomization. DISCUSSION: The results suggest that high-dimensional plasma protein testing could be a useful and reproducible approach for measuring brain amyloid deposition.
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Enfermedad de Alzheimer , Amiloide/metabolismo , Biomarcadores/sangre , Encéfalo/metabolismo , Proteómica , Factores de Edad , Anciano , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Europa (Continente) , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Resting-state connectivity has been widely studied in the healthy and pathological brain. Less well-characterized are the brain networks altered during pharmacological interventions and their possible interaction with vigilance. In the hopes of finding new biomarkers which can be used to identify cortical activity and cognitive processes linked to the effects of drugs to treat neurodegenerative diseases such as Alzheimer's disease, the analysis of networks altered by medication would be particularly interesting. Eleven healthy subjects were recruited in the context of the European Innovative Medicines Initiative 'PharmaCog'. Each underwent five sessions of simultaneous EEG-fMRI in order to investigate the effects of donepezil and memantine before and after sleep deprivation (SD). The SD approach has been previously proposed as a model for cognitive impairment in healthy subjects. By applying network based statistics (NBS), we observed altered brain networks significantly linked to donepezil intake and sleep deprivation. Taking into account the sleep stages extracted from the EEG data we revealed that a network linked to sleep is interacting with sleep deprivation but not with medication intake. We successfully extracted the functional resting-state networks modified by donepezil intake, sleep and SD. We observed donepezil induced whole brain connectivity alterations forming a network separated from the changes induced by sleep and SD, a result which shows the utility of this approach to check for the validity of pharmacological resting-state analysis of the tested medications without the need of taking into account the subject specific vigilance.
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Encéfalo/efectos de los fármacos , Donepezilo/farmacología , Red Nerviosa/efectos de los fármacos , Nootrópicos/farmacología , Privación de Sueño/fisiopatología , Sueño/fisiología , Adulto , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Mapeo Encefálico , Electroencefalografía , Humanos , Imagen por Resonancia Magnética , Masculino , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/fisiopatología , Privación de Sueño/diagnóstico por imagenRESUMEN
INTRODUCTION: In this study, the influence of physiological determinants on 18F-fluoro-d-glucose ((18)F-FDG) brain uptake was evaluated in a mouse model of Alzheimer disease. MATERIALS AND METHODS: TASTPM (Tg) and age-matched C57BL/6 J (WT) mice were fasted for 10 hours, while another group was fasted for 20 hours to evaluate the effect of fasting duration. The effect of repeatedly scanning was evaluated by scanning Tg and WT mice at days 1, 4, and 7. Brain (18)F-FDG uptake was evaluated in the thalamus being the most indicative region. Finally, the cerebellum was tested as a reference region for the relative standard uptake value (rSUV). RESULTS: When correcting the brain uptake for glucose, the effect of different fasting durations was attenuated and the anticipated hypometabolism in Tg mice was demonstrated. Also, with repeated scanning, the brain uptake values within a group and the hypometabolism of the Tg mice only remained stable over time when glucose correction was applied. Finally, hypometabolism was also observed in the cerebellum, yielding artificially higher rSUV values for Tg mice. CONCLUSION: Corrections for blood glucose levels have to be applied when semiquantifying (18)F-FDG brain uptake in mouse models for AD. Potential reference regions for normalization should be thoroughly investigated to ensure that they are not pathologically affected also by afferent connections.
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Enfermedad de Alzheimer/diagnóstico por imagen , Ayuno/fisiología , Fluorodesoxiglucosa F18/administración & dosificación , Radiofármacos/administración & dosificación , Tálamo/diagnóstico por imagen , Animales , Glucemia/metabolismo , Cerebelo/diagnóstico por imagen , Modelos Animales de Enfermedad , Humanos , Ratones , Ratones Transgénicos , Neuroimagen/métodos , Tomografía de Emisión de PositronesRESUMEN
Detecting and treating Alzheimer's disease, before cognitive deficits occur, has become the health challenge of our time. The earliest known event in Alzheimer's disease is rising amyloid-ß. Previous studies have suggested that effects on synaptic transmission may precede plaque deposition. Here we report how relative levels of different soluble amyloid-ß peptides in hippocampus, preceding plaque deposition, relate to synaptic and genomic changes. Immunoprecipitation-mass spectrometry was used to measure the early rise of different amyloid-ß peptides in a mouse model of increasing amyloid-ß ('TASTPM', transgenic for familial Alzheimer's disease genes APP/PSEN1). In the third postnatal week, several amyloid-ß peptides were above the limit of detection, including amyloid-ß40, amyloid-ß38 and amyloid-ß42 with an intensity ratio of 6:3:2, respectively. By 2 months amyloid-ß levels had only increased by 50% and although the ratio of the different peptides remained constant, the first changes in synaptic currents, compared to wild-type mice could be detected with patch-clamp recordings. Between 2 and 4 months old, levels of amyloid-ß40 rose by â¼7-fold, but amyloid-ß42 rose by 25-fold, increasing the amyloid-ß42:amyloid-ß40 ratio to 1:1. Only at 4 months did plaque deposition become detectable and only in some mice; however, synaptic changes were evident in all hippocampal fields. These changes included increased glutamate release probability (P < 0.001, n = 7-9; consistent with the proposed physiological effect of amyloid-ß) and loss of spontaneous action potential-mediated activity in the cornu ammonis 1 (CA1) and dentate gyrus regions of the hippocampus (P < 0.001, n = 7). Hence synaptic changes occur when the amyloid-ß levels and amyloid-ß42:amyloid-ß40 ratio are still low compared to those necessary for plaque deposition. Genome-wide microarray analysis revealed changes in gene expression at 2-4 months including synaptic genes being strongly affected but often showing significant changes only by 4 months. We thus demonstrate that, in a mouse model of rising amyloid-ß, the initial deposition of plaques does not occur until several months after the first amyloid-ß becomes detectable but coincides with a rapid acceleration in the rise of amyloid-ß levels and the amyloid-ß42:amyloid-ß40 ratio. Prior to acceleration, however, there is already a pronounced synaptic dysfunction, reflected as changes in synaptic transmission and altered gene expression, indicating that restoring synaptic function early in the disease progression may represent the earliest possible target for intervention in the onset of Alzheimer's disease.
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Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Placa Amiloide/patología , Transmisión Sináptica/fisiología , Animales , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Hipocampo/patología , Inmunoprecipitación , Espectrometría de Masas , Ratones , Ratones Transgénicos , Análisis de Secuencia por Matrices de Oligonucleótidos , Técnicas de Placa-Clamp , Placa Amiloide/genética , Placa Amiloide/metabolismo , TranscriptomaRESUMEN
A non-selective antihistamine, dimebon, has recently emerged as a potential treatment for Alzheimer's disease and Huntington's disease. Dimebon exerts several effects in addition to its anti-histaminergic effect, and of particular interest is its ability to enhance cognitive function in several models. The mechanism underlying this is unknown though it has been suggested that it may be associated with its anti-cholinergic action. Dimebon has also been reported to be neuroprotective, perhaps as a result of its ability to stabilize mitochondria. We considered that these effects might impact on the well-described age-related impairment in spatial learning and therefore examined the effect of repeated administration of dimebon on performance of young and aged animals in the Morris water maze. Whereas a clear age-related deficit was observed, dimebon failed to exert any effect on performance. Similarly, dimebon exerted no effect on the age-related increase in hippocampal expression of several markers of microglial and astroglial activation. We conclude that, despite its cognitive enhancing effects in some models, dimebon failed to modulate the deficit in spatial learning in aged rats and the evidence suggests that the drug does not possess anti-inflammatory properties.
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Gliosis/tratamiento farmacológico , Indoles/farmacología , Aprendizaje por Laberinto/efectos de los fármacos , Envejecimiento , Animales , Cognición/efectos de los fármacos , Proteína Ácida Fibrilar de la Glía/metabolismo , Indoles/uso terapéutico , Masculino , Ratas , Ratas WistarRESUMEN
AIMS: This paper describes findings from the first-in-human study for GSK1482160, an orally available allosteric P2X7 receptor modulator. The study aimed to assess the pharmacokinetics (PK), pharmacodynamics (PD), safety and tolerability of the compound in healthy subjects. METHODS: Escalating single doses of up to 1 g were administered to healthy subjects in a single-blind and placebo-controlled fashion. Safety, tolerability, blood drug concentrations and ex vivo Il-1ß production in blood were evaluated. RESULTS: Drug concentration peaked within 3.5 h of dosing under fasting conditions and declined thereafter with a relatively short half-life of less than 4.5 h. Exposure was proportional to dose with between subject variability of less than 60%. A PK/PD model quantified Il-1ß as a function of drug exposure. The model allowed simulation of in vivo pharmacology for various untested dose levels and regimens. Furthermore, the mechanistic model supported the hypothesis that the compound reduces the efficacy of ATP at the P2X7 receptor without affecting its affinity. No major safety or tolerability concerns were identified in this small study (n = 29), except for one case of asymptomatic accelerated idioventricular rhythm at the top dose. CONCLUSION: The model-based approach maximized analysis power by integrating all biomarker data and revealed mechanistic insight into the pharmacology of P2X7 modulation by GSK1482160. Simulations by this model ultimately led to the discontinuation of the development of this compound. The therapeutic relevance of the P2X7 receptor remains to be tested in patients. The mechanistic-model-based approach can be applied widely to drug development.
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Receptores Purinérgicos P2X7/efectos de los fármacos , Adulto , Anciano , Regulación Alostérica , Femenino , Humanos , Interleucina-1beta/biosíntesis , Masculino , Persona de Mediana Edad , Proyectos Piloto , Método Simple CiegoRESUMEN
Developmental and epileptic encephalopathies (DEEs) are a group of rare childhood disorders characterized by severe epilepsy and cognitive deficits. Numerous DEE genes have been discovered thanks to advances in genomic diagnosis, yet putative molecular links between these disorders are unknown. CDKL5 deficiency disorder (CDD, DEE2), one of the most common genetic epilepsies, is caused by loss-of-function mutations in the brain-enriched kinase CDKL5. To elucidate CDKL5 function, we looked for CDKL5 substrates using a SILAC-based phosphoproteomic screen. We identified the voltage-gated Ca2+ channel Cav2.3 (encoded by CACNA1E) as a physiological target of CDKL5 in mice and humans. Recombinant channel electrophysiology and interdisciplinary characterization of Cav2.3 phosphomutant mice revealed that loss of Cav2.3 phosphorylation leads to channel gain-of-function via slower inactivation and enhanced cholinergic stimulation, resulting in increased neuronal excitability. Our results thus show that CDD is partly a channelopathy. The properties of unphosphorylated Cav2.3 closely resemble those described for CACNA1E gain-of-function mutations causing DEE69, a disorder sharing clinical features with CDD. We show that these two single-gene diseases are mechanistically related and could be ameliorated with Cav2.3 inhibitors.
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Epilepsia , Síndromes Epilépticos , Espasmos Infantiles , Animales , Niño , Humanos , Ratones , Canales de Calcio/genética , Epilepsia/genética , Síndromes Epilépticos/genética , Proteínas Serina-Treonina Quinasas/genética , Espasmos Infantiles/genéticaRESUMEN
BACKGROUND: Genome-wide association studies (GWAS) of Alzheimer's disease (AD) have identified several risk loci, but many remain unknown. Cerebrospinal fluid (CSF) biomarkers may aid in gene discovery and we previously demonstrated that six CSF biomarkers (ß-amyloid, total/phosphorylated tau, NfL, YKL-40, and neurogranin) cluster into five principal components (PC), each representing statistically independent biological processes. Here, we aimed to (1) identify common genetic variants associated with these CSF profiles, (2) assess the role of associated variants in AD pathophysiology, and (3) explore potential sex differences. METHODS: We performed GWAS for each of the five biomarker PCs in two multi-center studies (EMIF-AD and ADNI). In total, 973 participants (n = 205 controls, n = 546 mild cognitive impairment, n = 222 AD) were analyzed for 7,433,949 common SNPs and 19,511 protein-coding genes. Structural equation models tested whether biomarker PCs mediate genetic risk effects on AD, and stratified and interaction models probed for sex-specific effects. RESULTS: Five loci showed genome-wide significant association with CSF profiles, two were novel (rs145791381 [inflammation] and GRIN2D [synaptic functioning]) and three were previously described (APOE, TMEM106B, and CHI3L1). Follow-up analyses of the two novel signals in independent datasets only supported the GRIN2D locus, which contains several functionally interesting candidate genes. Mediation tests indicated that variants in APOE are associated with AD status via processes related to amyloid and tau pathology, while markers in TMEM106B and CHI3L1 are associated with AD only via neuronal injury/inflammation. Additionally, seven loci showed sex-specific associations with AD biomarkers. CONCLUSIONS: These results suggest that pathway and sex-specific analyses can improve our understanding of AD genetics and may contribute to precision medicine.
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Enfermedad de Alzheimer , Humanos , Femenino , Masculino , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/patología , Estudio de Asociación del Genoma Completo , Proteínas tau/genética , Biomarcadores , Inflamación , Apolipoproteínas E/genética , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/genética , Receptores de N-Metil-D-Aspartato/genéticaRESUMEN
AIMS: To investigate the effects of two single nucleotide polymorphisms (SNPs) in the human P2X7 receptor gene (P2RX7)--1068G>A (A348T) and 1513A>C (E496A)--on P2X7 receptor function, using a specific receptor antagonist (GSK1370319A) and prospective genetic stratification. METHODS: Lipopolysaccharide- and ATP-stimulated interleukin-1ß production was determined in the presence or absence of GSK1370319A in blood culture from 32 prospectively genotyped subjects. RESULTS: There was approximately 6.7-fold difference (P < 0.0001) in IC50 for inhibition of ATP-stimulated interleukin-1ß release by GSK1370319A between individuals with the homozygous gain--(1068A) and loss-of-function (1513C) genotypes (expressing the 348T, 496E and 348A, 496A alleles, respectively). CONCLUSIONS: Leukocyte P2X7 receptors had significantly altered pharmacodynamic responses to a specific antagonist (GSK1370319A), directly related to SNP genotype.
Asunto(s)
Leucocitos/efectos de los fármacos , Polimorfismo de Nucleótido Simple , Antagonistas del Receptor Purinérgico P2X/farmacología , Pirrolidinas/farmacología , Receptores Purinérgicos P2X7/efectos de los fármacos , Receptores Purinérgicos P2X7/genética , Adenosina Trifosfato/metabolismo , Adulto , Relación Dosis-Respuesta a Droga , Femenino , Genotipo , Heterocigoto , Homocigoto , Humanos , Interleucina-1beta/farmacología , Leucocitos/metabolismo , Lipopolisacáridos/farmacología , Masculino , Persona de Mediana Edad , Fenotipo , Estudios ProspectivosRESUMEN
Alzheimer's disease (AD) is the most frequent neurodegenerative disease with an increasing prevalence in industrialized, aging populations. AD susceptibility has an established genetic basis which has been the focus of a large number of genome-wide association studies (GWAS) published over the last decade. Most of these GWAS used dichotomized clinical diagnostic status, i.e., case vs. control classification, as outcome phenotypes, without the use of biomarkers. An alternative and potentially more powerful study design is afforded by using quantitative AD-related phenotypes as GWAS outcome traits, an analysis paradigm that we followed in this work. Specifically, we utilized genotype and phenotype data from n = 931 individuals collected under the auspices of the European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery (EMIF-AD MBD) study to perform a total of 19 separate GWAS analyses. As outcomes we used five magnetic resonance imaging (MRI) traits and seven cognitive performance traits. For the latter, longitudinal data from at least two timepoints were available in addition to cross-sectional assessments at baseline. Our GWAS analyses revealed several genome-wide significant associations for the neuropsychological performance measures, in particular those assayed longitudinally. Among the most noteworthy signals were associations in or near EHBP1 (EH domain binding protein 1; on chromosome 2p15) and CEP112 (centrosomal protein 112; 17q24.1) with delayed recall as well as SMOC2 (SPARC related modular calcium binding 2; 6p27) with immediate recall in a memory performance test. On the X chromosome, which is often excluded in other GWAS, we identified a genome-wide significant signal near IL1RAPL1 (interleukin 1 receptor accessory protein like 1; Xp21.3). While polygenic score (PGS) analyses showed the expected strong associations with SNPs highlighted in relevant previous GWAS on hippocampal volume and cognitive function, they did not show noteworthy associations with recent AD risk GWAS findings. In summary, our study highlights the power of using quantitative endophenotypes as outcome traits in AD-related GWAS analyses and nominates several new loci not previously implicated in cognitive decline.
RESUMEN
Manipulation of diet such as increasing the level of fat or inducing insulin resistance has been shown to exacerbate the pathology in several animal models of neurological disease. Caloric restriction, however, has been demonstrated to extend the life span of many organisms. Reduced calorie consumption appears to increase the resistance of neurons to intracellular and extracellular stress and consequently improves the behavioural phenotype in animal models of neurological diseases, such as Alzheimer's disease. We review the evidence from a variety of mouse models that diet is a risk factor that can significantly contribute to the development of neurological diseases.
Asunto(s)
Restricción Calórica , Dieta , Modelos Animales de Enfermedad , Enfermedades del Sistema Nervioso/fisiopatología , Animales , Ingestión de Energía , Humanos , RatonesRESUMEN
Multiple sclerosis (MS), a chronic disorder of the central nervous system and common cause of neurological disability in young adults, is characterized by moderate but complex risk heritability. Here we report the results of a genome-wide association study performed in a 1000 prospective case series of well-characterized individuals with MS and group-matched controls using the Sentrix HumanHap550 BeadChip platform from Illumina. After stringent quality control data filtering, we compared allele frequencies for 551 642 SNPs in 978 cases and 883 controls and assessed genotypic influences on susceptibility, age of onset, disease severity, as well as brain lesion load and normalized brain volume from magnetic resonance imaging exams. A multi-analytical strategy identified 242 susceptibility SNPs exceeding established thresholds of significance, including 65 within the MHC locus in chromosome 6p21.3. Independent replication confirms a role for GPC5, a heparan sulfate proteoglycan, in disease risk. Gene ontology-based analysis shows a functional dichotomy between genes involved in the susceptibility pathway and those affecting the clinical phenotype.