Diagnosis associated with Tau higher than 1200 pg/mL: Insights from the clinical and laboratory practice.

CONTEXT: Cerebrospinal fluid (CSF) biomarkers are valuable tools for the diagnosis of neurological diseases. We aimed to investigate within a retrospective multicentric study the final diagnosis associated with very high CSF Tau levels and to identify patterns of biomarkers that would differentiate them in clinical practice, to help clinical biologists into physicians' counseling. PATIENTS AND METHODS: Within the national multicentric network ePLM, we included 1743 patients from January 1, 2008, to December 31, 2013, with CSF biomarkers assayed by the same Innotest assays (protein Tau, phospho-Tau [pTau], and Aß 1-42). We identified 205 patients with protein Tau concentration higher than 1200 pg/mL and final diagnosis. RESULTS: Among those patients, 105 (51.2%) were suffering from Alzheimer's disease, 37 (18%) from sporadic Creuztfeldt-Jakob disease, and 63 (30.7%) from other neurological diseases including paraneoplastic/ central nervous system tumor, frontotemporal dementia, other diagnoses, amyloid angiopathy, Lewy body dementia, and infections of the central nervous system. Phospho-Tau, Aß1-42 and Aß1-42/pTau values differed significantly between the three groups of patients (p < .001). An Aß1-42/pTau ratio between 4.7 and 9.7 was suggestive of other neurological diseases (threshold in AD: 8.3). CSF 14-3-3 was useful to discriminate Alzheimer's disease from Creuztfeldt-Jakob disease in case of Aß1-42 concentrations <550 pg/mL or pTau>60 pg/mL. CONCLUSION: This work emphasizes the interest of a well-thought-out interpretation of CSF biomarkers in neurological diseases, particularly in the case of high Tau protein concentrations in the CSF.

Down-regulation of astroglial CYP2C, glucocorticoid receptor and constitutive androstane receptor genes in response to cocaine in human U373 MG astrocytoma cells.

Psychostimulant drugs abuse is associated with an increased risk of stroke. Cytochromes P450 (CYP), especially the astrocytic members of the CYP2C subfamily may play an important role in the modulation of cerebrovascular functions, by generating vasodilatator metabolites from arachidonic acid (AA). Our study examined the regulation of CYP2C genes in response to cocaine or amphetamine in the human astrocyte-like U373 MG cells, using reverse transcription-polymerase chain reaction (RT-PCR) and western-blot analysis. A treatment for 48h with increasing concentrations of cocaine caused a significant down-regulation of CYP2C8 and CYP2C9 genes and decreased the protein level. These effects were not observed with amphetamine. One mechanism of the CYP2C mRNA regulation implicates various specific receptors including glucocorticoid receptor (GR) and constitutive androstane receptor (CAR). Effects of cocaine on CYP2C were accompanied by a decrease in the GR and CAR gene expression suggesting that these nuclear receptors could be involved in the CYP2C repression by cocaine in the U373 MG cell line. These findings represent a possible molecular mechanism involved in the cerebrovascular risk associated with cocaine abuse.

Astroglial CYP1B1 up-regulation in inflammatory/oxidative toxic conditions: IL-1beta effect and protection by N-acetylcysteine.

The present work aims to determine the relevance of an astrocytoma cell line U373 MG, for assessing the role of some astroglial cytochrome P450 in neurotoxicity and neuroprotection. CYP1B1, CYP2C8, CYP2C9, CYP2D6, CYP2J2, CYP2E1 and CYP4A11 mRNA were detected by reverse transcriptase-polymerase chain reaction in control U373 MG cell cultures. Among them we focused on CYP1B1 expression. After 48 h treatment with a range of concentrations of interleukin-1beta (1, 5, 10 ng/ml) used to simulate stress conditions, CYP1B1 mRNA expression was enhanced in a dose-dependent way. This increased expression was followed 24 h later by an increase in protein level, determined by Western-blot. N-acetylcysteine (NAC) partially inhibited this effect both on the mRNA and protein levels. As CYP1B1 activates procarcinogenic compounds to reactive metabolites, an increase in this P450 isoform will participate to toxic consequences of an inflammatory/oxidative stress. NAC will prevent this deleterious effect.

U373-MG response to interleukin-1beta-induced oxidative stress.

Oxidative stress has been involved in various neurological disorders and, in the central nervous system, astrocytes represent the cell type that contributes to neuroprotection via glutathione (GSH) metabolism, GSH-metabolizing enzymes like gamma-glutamyltransferase (GGT), and apoE secretion. In this study, using IL-1beta, a proinflammatory and prooxidant cytokine that is increased in numerous pathological situations, cells of astrocytoma cell line U373-MG were exposed to an oxidative stress, leading to c-Jun and c-Fos activation. IL-1beta decreased both GGT activity and intracellular GSH content and increased apoE secretion, initiating astroglial response to injury. We observed that antioxidants inhibit IL-1beta effects on c-Jun and c-Fos proteins, GGT activity and the GSH pool but not on apoE secretion. Our results allow us to conclude that neurological disorders associated with an IL-1beta-induced oxidative stress could be, at least experimentally, reversible in the presence of one antioxidant, N-acetylcysteine.