Modifications of the endosomal compartment in peripheral blood mononuclear cells and fibroblasts from Alzheimer’s disease patients

International audienceIdentification of blood-based biomarkers of Alzheimer’s disease (AD) remains a challenge. Neuropathological studies have identified enlarged endosomes in post-mortem brains as the earliest cellular change associated to AD. Here the presence of enlarged endosomes was investigated in peripheral blood mononuclear cells from 48 biologically defined AD patients (25 with mild cognitive impairment and 23 with dementia (AD-D)), and 23 age-matched healthy controls using immunocytochemistry and confocal microscopy. The volume and number of endosomes were not significantly different between AD and controls. However, the percentage of cells containing enlarged endosomes was significantly higher in the AD-D group as compared with controls. Furthermore, endosomal volumes significantly correlated to [C11]PiB cortical index measured by positron emission tomography in the AD group, independently of the APOE genotype, but not to the levels of amyloid-beta, tau and phosphorylated tau measured in the cerebrospinal fluid. Importantly, we confirmed the presence of enlarged endosomes in fibroblasts from six unrelated AD-D patients as compared with five cognitively normal controls. This study is the first, to our knowledge, to report morphological alterations of the endosomal compartment in peripheral cells from AD patients correlated to amyloid load that will now be evaluated as a possible biomarker

Identification of Novel Functional Inhibitors of Acid Sphingomyelinase

We describe a hitherto unknown feature for 27 small drug-like molecules, namely functional inhibition of acid sphingomyelinase (ASM). These entities named FIASMAs (Functional Inhibitors of Acid SphingoMyelinAse), therefore, can be potentially used to treat diseases associated with enhanced activity of ASM, such as Alzheimer's disease, major depression, radiation- and chemotherapy-induced apoptosis and endotoxic shock syndrome. Residual activity of ASM measured in the presence of 10 µM drug concentration shows a bimodal distribution; thus the tested drugs can be classified into two groups with lower and higher inhibitory activity. All FIASMAs share distinct physicochemical properties in showing lipophilic and weakly basic properties. Hierarchical clustering of Tanimoto coefficients revealed that FIASMAs occur among drugs of various chemical scaffolds. Moreover, FIASMAs more frequently violate Lipinski's Rule-of-Five than compounds without effect on ASM. Inhibition of ASM appears to be associated with good permeability across the blood-brain barrier. In the present investigation, we developed a novel structure-property-activity relationship by using a random forest-based binary classification learner. Virtual screening revealed that only six out of 768 (0.78%) compounds of natural products functionally inhibit ASM, whereas this inhibitory activity occurs in 135 out of 2028 (6.66%) drugs licensed for medical use in humans

Monitorage biologique du traumatisé crânien sévère (étude préliminaire sur la place du dosage des 15-F2t-isoprostanes (8-isoprostaglandines) dans les microdialysats cérébraux)

Le traumatisme crânien constitue un problème de santé publique, par son incidence et le jeune âge des sujets atteints. L'apparition systématique de lésions cérébrales secondaires, surajoutées aux lésions initiales, complique l'évolution clinique. Pour freiner ces lésions secondaires, une prise en charge précoce et un monitorage optimal sont primordiaux. Des marqueurs biologiques, comme la protéine S-IOOb, sont utilisés comme marqueur pronostique et la microdialyse cérébrale constitue une technique novatrice d'échantillonnage du liquide extracellulaire au plus près des lésions. Cette technique permet d'isoler précocement des marqueurs reflétant les perturbations biochimiques rencontrés chez les patients cérébrolésés, telles que l'inflammation, l'excitotoxicité, la défaillance énergétique et le stress oxydant. La susceptibilité du cerveau aux radicaux libres et sa richesse en lipides placent le stress oxydant comme acteur majeur de la physiopathologie des lésions secondaires. La peroxydation lipidique aboutit à la production d'analogue des prostaglandines, les isoprostanes, aux effets bioactifs délétères et constituant un marqueur biologique du stress oxydant. Notre étude princeps dosant les 15-F2t-isoprostanes dans les microdialysats de trois patients traumatisés crâniens sévères par technique ELISA a permis d'en montrer la faisabilité. Ces résultats, couplés aux dosages de la protéine S-IOOb sérique et au lactate, pyruvate, glutamate et glucose issus des microdialysats, ont permis de dégager des profils biologiques évolutifs différents selon le devenir à court et moyen terme des patients. La faisabilité de cette étude encourage à poursuivre les investigations pour démontrer l'intérêt pronostique des 15-F2t-isoprostanes dans le monitorage biologique des traumatisés crâniens.NANCY1-SCD Medecine (545472101) / SudocSudocFranceF

Place du réseau de pharmaciens sentinelles de Lorraine dans le dispositif public de lutte contre les pharmacodépendances

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

Implication de la phospholipase A2 cytoplamique dans la pathogénèse de la maladie d'Alzheimer

Les oligomères solubles de peptide Bêta-amyloïde (Ab) apparaissent comme les acteurs majeurs de la perte synaptique précoce observée au cours de la maladie d'Alzheimer. Notre équipe a précédemment montré que ces oligomères de peptide Ab activent la phospholipase A2 cytosolique (cPLA2), qui entraîne la libération d'acide arachidonique à partir des phospholipides membranaires. En utilisant un modèle d'injection intra cérébro ventriculaire unique d'une faible quantité de peptide Ab, nous avons pu observer que l'inactivation constitutive du gène de la cPLA2 protége les souris KO contre les perturbations mnésiques et empêche la réduction de l'expression de protéines synaptiques au sein de l'hippocampe, ces deux effets délétères étant constatés chez les animaux wild-type. Par la suite, nous avons montré que l'activation des sphingomyélinases, consécutive à l'exposition aux oligomères Ab, est indétectable dans des neurones en culture issus de souris KO. Dans ces mêmes neurones KO, nous avons constaté que la phosphorylation de Akt/PKB n'est pas altérée suite à l'exposition des cellules aux oligomères Ab. Enfin, nous avons pu mettre en évidence une diminution de l'expression de la protéine précurseur du peptide Ab (protéine APP), tant au niveau d'homogénats hippocampiques que de neurones en cultures, issus de souris KO. Néanmoins, des travaux supplémentaires sont requis pour établir le lien exact entre cette réduction de l'expression d'APP et la résistance aux oligomères Ab, tant in vitro qu'in vivo. Toutefois, ces résultats soulignent l'implication de la cPLA2 dans la neuro dégénérescence entrainée par les oligomères Ab, et font apparaitre cette enzyme comme une cible thérapeutique potentielle pour le traitement de la maladie d'AlzheimerSoluble beta-amyloid (Ab) oligomers putatively play a critical role in the early synapse loss and cognitive impairment observed in Alzheimer's disease. We previously demonstrated that A-beta oligomers activate cytosolic phospholipase A2 (cPLA2) which specifically releases arachidonic acid from membrane phospholipids. By using a single Ab oligomers intra cerebro ventricular injection, we observed that cPLA2 gene suppression prevents both the alterations of cognitive abilities and the reduction of hippocampal synaptic markers levels which are observed in wild type mice. We further demonstrated that the Ab oligomers-induced sphingomyelinase activation is suppressed and that the phosphorylation of Akt/PKB is preserved in neuronal cells isolated from KO mice. Interestingly, expression of the Ab precursor protein (APP) is reduced in hippocampus homogenates and neuronal cells from KO mice, but the relationship with the resistance of these mice to the Ab oligomers toxicity requires further investigation. These results therefore show that cPLA2 plays a key role in the Ab oligomers-associated neurodegenerative effects, and as such represents a potential therapeutic target for the treatment of Alzheimer's diseaseMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

No prognostic value of routine cerebrospinal fluid biomarkers in a population-based cohort of 407 multiple sclerosis patients

International audienceBackground: We aimed to determine the association of clinical and routine cerebrospinal fluid biochemical markers (total protein, IgG index and oligoclonal bands) with disability in multiple sclerosis and whether these biomarkers assessed at diagnosis add prognostic value. Methods: We followed a cohort of patients included in the Multiple Sclerosis Lorraine Register (eastern France) who had a diagnosis of multiple sclerosis for at least 5 years, as well as biological markers values and MRI findings (Barkhof's criteria). In a Cox regression model, endpoint was time to score of 4 on the Expanded Disability Status Scale (EDSS) (i.e., limited time walking without aid or rest for more than 500 m). Results: For 407 patients included, the median time from multiple sclerosis onset to EDSS score 4 was 4.5 years [2.2-7.2]. Cerebrospinal fluid total protein factor < 500 mg/L was associated with EDSS score 4 on bivariate analysis (hazard ratio 0.66, 95% confidence interval 0.46-0.95, p = 0.02). On multivariate analysis, older age at disease onset (= 50 years) and initial primary progressive course of MS but not biological markers predicted worse prognosis. Conclusion: Routine cerebrospinal fluid biological markers at diagnosis were not prognostic factors of multiple sclerosis progression

Additional Use of A beta(42)/A beta(40) Ratio with Cerebrospinal Fluid Biomarkers P-Tau and A beta(42) Increases the Level of Evidence of Alzheimer's Disease Pathophysiological Process in Routine Practice

International audienceBackground: Cerebrospinal fluid (CSF) biomarkers have recently been included in the criteria for the diagnosis of Alzheimer's disease (AD). Since interpretation of CSF profile requires the combination of three parameters, biological data are not always conclusive and isolated elevation of phosphorylated tau (P-tau) or reduction of amyloid-beta (A beta)(42) alone can be observed. In these cases, A beta(42)/A beta(40) ratio could be more relevant than A beta(42) absolute values by considering inter-individual variations in the total amyloid load. Objective: The objective of this study was to assess the use of A beta(42)/A beta(40) ratio to improve the accuracy of biological conclusions in the diagnosis of patients with ambiguous CSF A beta(42) or tau results. Methods: Among 386 lumbar punctures analyzed in the lab in 2 years, 122 showed ambiguous biological data that were completed by CSF A beta(40) quantification and A beta(42)/A beta(40) ratio calculation. A biological conclusion was then made using 0.05 as the A beta(42)/A beta(40) ratio cut-off. Results: Our results showed that one-third of the biological profiles of patients with atypical dementia were ambiguous. The addition of A beta(42)/A beta(40) ratio increased the proportion of interpretable biological profiles from 69% to 87%, without changing the conclusion when usual biomarkers (A beta(42) and P-tau) were concordant. Conclusion: Our results support the use of the A beta(42)/A beta(40) ratio in addition to the usual CSF AD biomarkers for patients with ambiguous biological profiles. This method could be specifically directed to this population in order to improve the level of certainty for clinical routine practice

Effets pro-vieillissement d’un régime hyperipidique sur la fonctionnalité d’une cible thérapeutique neuronale d’intérêt dans la maladie d’Alzheimer

National audienc