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Amyloid, Tau, and neurodegeneration biomarkers can stage Alzheimer's Disease (AD). Synaptic biomarkers may help track cognition.

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The lack of (inter-)laboratory standardization has hampered the application of universal cutoff values for Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarkers and their transfer to general clinical practice. The automation of the AD biomarker immunoassays is suggested to generate more robust results than using manual testing. Open-access platforms will facilitate the integration of automation for novel biomarkers, allowing the introduction of the protein profiling concept. A feasibility study was performed on an automated open-access platform of the commercial immunoassays for the 42-amino-acid isoform of amyloid-β (Aβ1–42), Aβ1–40, and total tau in CSF. Automated Aβ1–42, Aβ1–40, and tau immunoassays were performed within predefined acceptance criteria for bias and imprecision. Similar accuracy was obtained for ready-to-use calibrators as for reconstituted lyophilized kit calibrators. When compared with the addition of a standard curve in each test run, the use of a master calibrator curve, determined before and applied to each batch analysis as the standard curve, yielded an acceptable overall bias of −2.6% and −0.9% for Aβ1−42and Aβ1–40, respectively, with an imprecision profile of 6.2% and 8.4%, respectively. Our findings show that transfer of commercial manual immunoassays to fully automated open-access platforms is feasible, as it performs according to universal acceptance criteria.

The lack of (inter-)laboratory standardization has hampered the application of universal cutoff values for Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarkers and their transfer to general clinical practice. The automation of the AD biomarker immunoassays is suggested to generate more robust results than using manual testing. Open-access platforms will facilitate the integration of automation for novel biomarkers, allowing the introduction of the protein profiling concept. A feasibility study was performed on an automated open-access platform of the commercial immunoassays for the 42-amino-acid isoform of amyloid-β (Aβ1–42), Aβ1–40, and total tau in CSF. Automated Aβ1–42, Aβ1–40, and tau immunoassays were performed within predefined acceptance criteria for bias and imprecision. Similar accuracy was obtained for ready-to-use calibrators as for reconstituted lyophilized kit calibrators. When compared with the addition of a standard curve in each test run, the use of a master calibrator curve, determined before and applied to each batch analysis as the standard curve, yielded an acceptable overall bias of –2.6% and –0.9% for Aβ1–42and Aβ1–40, respectively, with an imprecision profile of 6.2% and 8.4%, respectively. Our findings show that transfer of commercial manual immunoassays to fully automated open-access platforms is feasible, as it performs according to universal acceptance criteria.

The exceedingly high rate of failed trials in Alzheimer's disease (AD) calls for immediate attention to improve efficiencies and learning from past, ongoing, and future trials. Accurate, highly rigorous standardized data are at the core of meaningful scientific research. Data standards allow for proper integration of clinical data sets and represent the essential foundation for regulatory endorsement of drug development tools. Such tools increase the potential for success and accuracy of trial results.

Neuregulin1 (Nrg1) est un substrat présynaptique de la bêta-sécrétase 1 (BACE1) qui peut notamment activer les récepteurs ErbB4 post-synaptiques. Le gène Nrg1 a été associé à la schizophrénie. L’activation de la voie Nrg1/ErbB4 peut induire la synaptogenèse et la plasticité, améliorer l’expression des récepteurs NMDA et GABA et est neuroprotectrice. Cette voie de signalisation peut induire une neuroinflammation et également altérer la formation de la mémoire. Dans la maladie d’Alzheimer (MA), Nrg1 est associées avec les plaques neuritiques. Alors que plusieurs études ont montré une augmentation de BACE1 dans le cerveau et le liquide cérébrospinal (LCS) des patients atteints de MA, aucune étude n’a évalué les niveaux de Nrg1 dans le LCS des patients atteints de MA ou des patients pré-Alzheimer (mild cognitive impairement[MCI]-MA) lié à la MA.

IMPORTANCE: Individuals in the presymptomatic stage of Alzheimer disease (AD) are increasingly being targeted for AD secondary prevention trials. How early during the normal life span underlying AD pathologies begin to develop, their patterns of change over time, and their relationship with future cognitive decline remain to be determined. OBJECTIVE: To characterize the within-person trajectories of cerebrospinal fluid (CSF) biomarkers of AD over time and their association with changes in brain amyloid deposition and cognitive decline in cognitively normal middle-aged individuals. DESIGN, SETTING, AND PARTICIPANTS: As part of a cohort study, cognitively normal (Clinical Dementia Rating [CDR] of 0) middle-aged research volunteers (n = 169) enrolled in the Adult Children Study at Washington University, St Louis, Missouri, had undergone serial CSF collection and longitudinal clinical assessment (mean, 6 years; range, 0.91-11.3 years) at 3-year intervals at the time of analysis, between January 2003 and November 2013. A subset (n = 74) had also undergone longitudinal amyloid positron emission tomographic imaging with Pittsburgh compound B (PiB) in the same period. Serial CSF samples were analyzed for β-amyloid 40 (Aβ40), Aβ42, total tau, tau phosphorylated at threonine 181 (P-tau181), visinin-like protein 1 (VILIP-1), and chitinase-3-like protein 1 (YKL-40). Within-person measures were plotted according to age and AD risk defined by APOE genotype (ε4 carriers vs noncarriers). Linear mixed models were used to compare estimated biomarker slopes among middle-age bins at baseline (early, 45-54 years; mid, 55-64 years; late, 65-74 years) and between risk groups. Within-person changes in CSF biomarkers were also compared with changes in cortical PiB binding and progression to a CDR higher than 0 at follow-up. MAIN OUTCOMES AND MEASURES: Changes in Aβ40, Aβ42, total tau, P-tau181, VILIP-1, and YKL-40 and, in a subset of participants, changes in cortical PiB binding. RESULTS: While there were no consistent longitudinal patterns in Aβ40 (P = .001-.97), longitudinal reductions in Aβ42 were observed in some individuals as early as early middle age (P ≤ .05) and low Aβ42 levels were associated with the development of cortical PiB-positive amyloid plaques (area under receiver operating characteristic curve = 0.9352; 95% CI, 0.8895-0.9808), especially in mid middle age (P < .001). Markers of neuronal injury (total tau, P-tau181, and VILIP-1) dramatically increased in some individuals in mid and late middle age (P ≤ .02), whereas the neuroinflammation marker YKL-40 increased consistently throughout middle age (P ≤ .003). These patterns were more apparent in at-risk ε4 carriers (Aβ42 in an allele dose-dependent manner) and appeared to be associated with future cognitive deficits as determined by CDR. CONCLUSIONS AND RELEVANCE: Longitudinal CSF biomarker patterns consistent with AD are first detectable during early middle age and are associated with later amyloid positivity and cognitive decline. Such measures may be useful for targeting middle-aged, asymptomatic individuals for therapeutic trials designed to prevent cognitive decline.

Alzheimer disease (AD) and Parkinson disease (PD) are the most common neurodegenerative disorders. For both diseases, early intervention is thought to be essential to the success of disease-modifying treatments. Cerebrospinal fluid (CSF) can reflect some of the pathophysiological changes that occur in the brain, and the number of CSF biomarkers under investigation in neurodegenerative conditions has grown rapidly in the past 20 years. In AD, CSF biomarkers are increasingly being used in clinical practice, and have been incorporated into the majority of clinical trials to demonstrate target engagement, to enrich or stratify patient groups, and to find evidence of disease modification. In PD, CSF biomarkers have not yet reached the clinic, but are being studied in patients with parkinsonism, and are being used in clinical trials either to monitor progression or to demonstrate target engagement and downstream effects of drugs. CSF biomarkers might also serve as surrogate markers of clinical benefit after a specific therapeutic intervention, although additional data are required. It is anticipated that CSF biomarkers will have an important role in trials aimed at disease modification in the near future. In this Review, we provide an overview of CSF biomarkers in AD and PD, and discuss their role in clinical trials.

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers of Alzheimer disease (AD) are currently being considered for inclusion in revised diagnostic criteria for research and/or clinical purposes to increase the certainty of antemortem diagnosis. OBJECTIVE: To test whether CSF biomarker assays differ in their ability to identify true markers of underlying AD pathology (eg, amyloid plaques and/or neurofibrillary tangles) in living individuals. DESIGN: We compared the performances of the 2 most commonly used platforms, INNOTEST enzyme-linked immunosorbent assay and INNO-BIA AlzBio3, for measurement of CSF β-amyloid (Aβ) and tau proteins to identify the presence of amyloid plaques in a research cohort (n=103). Values obtained for CSF Aβ1-42, total tau, and phosphorylated tau 181 (p-tau181) using the 2 assay platforms were compared with brain amyloid load as assessed by positron emission tomography using the amyloid imaging agent Pittsburgh compound B. SETTING: The Knight Alzheimer's Disease Research Center at Washington University in St Louis, Missouri. SUBJECTS: Research volunteers who were cognitively normal or had mild to moderate AD dementia. RESULTS: The 2 assay platforms yielded different (approximately 2- to 6-fold) absolute values for the various analytes, but relative values were highly correlated. The CSF Aβ1-42 correlated inversely and tau and p-tau181 correlated positively with the amount of cortical Pittsburgh compound B binding, albeit to differing degrees. Both assays yielded similar patterns of CSF biomarker correlations with amyloid load. The ratios of total tau to Aβ1-42 and p-tau181 to Aβ1-42 outperformed any single analyte, including Aβ1-42, in discriminating individuals with vs without cortical amyloid. CONCLUSIONS: The INNOTEST and INNO-BIA CSF platforms perform equally well in identifying individuals with underlying amyloid plaque pathology. Differences in absolute values, however, point to the need for assay-specific diagnostic cutoff values.

OBJECTIVE To identify biomarker patterns typical for Alzheimer disease (AD) in an independent, unsupervised way, without using information on the clinical diagnosis. DESIGN Mixture modeling approach. SETTING Alzheimer's Disease Neuroimaging Initiative database. PATIENTS OR OTHER PARTICIPANTS Cognitively normal persons, patients with AD, and individuals with mild cognitive impairment. MAIN OUTCOME MEASURES Cerebrospinal fluid–derived β-amyloid protein 1-42, total tau protein, and phosphorylated tau181P protein concentrations were used as biomarkers on a clinically well-characterized data set. The outcome of the qualification analysis was validated on 2 additional data sets, 1 of which was autopsy confirmed. RESULTS Using the US Alzheimer's Disease Neuroimaging Initiative data set, a cerebrospinal fluid β-amyloid protein 1-42/phosphorylated tau181P biomarker mixture model identified 1 feature linked to AD, while the other matched the “healthy” status. The AD signature was found in 90%, 72%, and 36% of patients in the AD, mild cognitive impairment, and cognitively normal groups, respectively. The cognitively normal group with the AD signature was enriched in apolipoprotein E ε4 allele carriers. Results were validated on 2 other data sets. In 1 study consisting of 68 autopsy-confirmed AD cases, 64 of 68 patients (94% sensitivity) were correctly classified with the AD feature. In another data set with patients (n = 57) with mild cognitive impairment followed up for 5 years, the model showed a sensitivity of 100% in patients progressing to AD. CONCLUSIONS The mixture modeling approach, totally independent of clinical AD diagnosis, correctly classified patients with AD. The unexpected presence of the AD signature in more than one-third of cognitively normal subjects suggests that AD pathology is active and detectable earlier than has heretofore been envisioned.Arch Neurol. 2010;67(8):949-956--

Cerebrospinal fluid (CSF) levels of tau (total tau), growth-associated protein-43 (GAP-43), soluble amyloid precursor protein (sAPP; i.e. total sAPP), and β-amyloid42 (Aβ42) were studied in patients with frontotemporal dementia (FTD; n = 14), Alzheimer’s disease (AD; n = 47) and vascular dementia (VAD; n = 16), and in age-matched controls (n = 12). CSF-tau was increased in AD compared to controls and FTD (p < 0.001 for both). CSF-GAP-43 was increased in AD compared to controls (p < 0.05), and both CSF-GAP-43 and CSF-sAPP were increased in AD compared to FTD (p < 0.01). Positive and highly significant correlations were found between CSF-tau and CSF-GAP-43 in all groups and between CSF-tau, CSF-GAP-43 and CSF-sAPP in AD. The correlations found may reflect a common pathophysiologic process such as axonal degeneration.

The standardization and clinical validation of the measurement of β-amyloid. (Aβ42) in cerebrospinal fluid (CSF), plasma and urine is described using a commercially available sandwich-type ELISA with 2 IF12 and 3D6 as monoclonal antibodies. The INNOTEST™ β-amyloid(1-42) allows the specific and reliable measurement of (1-42) amyloid peptides in CSF and plasma. The Aβ42 concentrations in serum and urine were below the detection limit. In plasma, no differences were found in Aβ42 levels between controls and patients with different neurodegenerative disorders (Alzheimer's disease (AD), Lewy body disease (LED), others). In contrast, CSF-Aβ42 concentrations were lower in AD and LBD patients as compared to controls. No correlation was found in AD patients between CSF and plasma concentrations of Aβ42 or between CSF Aβ42 levels and blood-brain-barrier function. The quantitative outcome of the test is in part dependent on confounding factors such as tube type, freeze/thaw cycles, temperature of incubation, standard preparation protocol, and antibody selection. Notwithstanding these aspects, it emerged that Aβ42 is a useful biochemical marker for the diagnosis of AD patients, but there is a need for an international Aβ standard, a universally accepted protocol for CSF preparation, and a thorough evaluation of assay performance in function of the boundary conditions.

Deposition of amyloid β-peptide (Aβ) in cerebral vessel walls (cerebral amyloid angiopathy, CAA) is very frequent in Alzheimer’s disease and occurs also as a sporadic disorder. Here, we describe significant CAA in addition to amyloid plaques, in aging APP/Ld transgenic mice overexpressing the London mutant of human amyloid precursor protein (APP) exclusively in neurons. The number of amyloid-bearing vessels increased with age, from ∼10 to 50 per coronal brain section in APP/Ld transgenic mice, aged 13 to 24 months. Vascular amyloid was preferentially deposited in arterioles and ranged from small focal to large circumferential depositions. Ultrastructural analysis allowed us to identify specific features contributing to weakening of the vessel wall and aneurysm formation, ie, disruption of the external elastic lamina, thinning of the internal elastic lamina, interruption of the smooth muscle layer, and loss of smooth muscle cells. Biochemically, the much lower Aβ42:Aβ40 ratio evident in vascular relative to plaque amyloid, demonstrated that in blood vessel walls Aβ40 was the more abundant amyloid peptide. The exclusive neuronal origin of transgenic APP, the high levels of Aβ in cerebrospinal fluid compared to plasma, and the specific neuroanatomical localization of vascular amyloid strongly suggest specific drainage pathways, rather than local production or blood uptake of Aβ as the primary mechanism underlying CAA. The demonstration in APP/Ld mice of rare vascular amyloid deposits that immunostained only for Aβ42, suggests that, similar to senile plaque formation, Aβ42 may be the first amyloid to be deposited in the vessel walls and that it entraps the more soluble Aβ40. Its ability to diffuse for larger distances along perivascular drainage pathways would also explain the abundance of Aβ40 in vascular amyloid. Consistent with this hypothesis, incorporation of mutant presenilin-1 in APP/Ld mice, which resulted in selectively higher levels of Aβ42, caused an increase in CAA and senile plaques. This mouse model will be useful in further elucidating the pathogenesis of CAA and Alzheimer’s disease, and will allow testing of diagnostic and therapeutic strategies.

Mutations in the presenilin 1(PSEN1) gene are an important cause of autosomal dominant Alzheimer's disease (AD). Both in vitroand in vivoexperiments showed that PSEN1mutations increase secretion of amyloid β42 (Aβ42), the longer and more fibrillogenic isoform of Aβ. We measured secreted Aβ42 in plasma of patients, presymptomatic mutation carriers, and escapees of two extended Belgian early-onset AD families, AD/A and AD/B, with a similar severe phenotype in terms of onset age (mean 35 years), duration of the disease (mean 6.5 years), and pathology. Both families segregate a different missense mutation in PSEN1located in different parts of the protein: I143T in family AD/A and G384A in family AD/B. A significant increase in Aβ42 concentrations was observed in plasma of mutation carriers in family AD/B, but not in family AD/A. A differential effect of the two PSEN1mutations on Aβ42 secretion was also detected in conditioned medium of stably transfected HEK293 cells. Both mutations increased Aβ42 secretion significantly; however, the increase was highest for G384A (5.5-fold over wild-type PSEN1), the largest effect observed for missense PSEN1mutations to date. Although the Aβ42 concentrations measured in vivoand in vitrodid not correlate with onset age, a positive correlation was obtained with age in the presymptomatic mutation carriers and a negative correlation with duration of disease in the patients. Our data obtained for PSEN1mutation carriers suggest that measuring Aβ42 concentrations in plasma will be informative as a diagnostic marker in a limited number of cases.

The expression and function of gonadotropin receptors, and the secretion of steroids, transferrin, and cytokines were investigated in three immortalized (single transfection with v-myc) mouse granulosa cell lines (GRM01, GRM01L, and GRM02). A dose-dependent increase in progesterone production was obtained in GRM01 and GRM02 cells after addition of LH, FSH, modulators of the adenylate cyclase enzyme system, and cAMP analogues. The LH-induced release of progesterone was already detectable in GRM02 cells after 8 h and was related to incubation time and cell number. Both epidermal growth factor (EGF) and transforming growth factor α (TGFα) induced the secretion of progesterone in GRM02 cells, while no effect was obtained with TGFβ. LH receptor concentration was highest in the GRM02 cell line. FSH receptor mRNA was visualized in GRM01 and GRM02 cells. Aromatase activity in GRM02 cells was induced by androgens and inhibited by aromatase inhibitors. Whereas all cell lines were able to secrete transferrin, only in GRM01 cells was transferrin secretion increased significantly by LH. FSH did not affect transferrin secretion in the three cell lines, in contrast to forskolin or 8-bromo-cAMP.The immortalized mouse granulosa cell lines were able to express and release several growth factors. The expression and secretion of activin, inhibin, TGFβ, EGF, TGFα, insulin-like growth factor II, fibroblast growth factor (acidic and basic), platelet-derived growth factor, and interleukin-6 suggest an autocrine or paracrine role for these factors in follicular differentiation and function. In conclusion, these cells, derived from mural granulosa cells and immortalized in a preovulatory state, can be used to study granulosa cell physiology or to study the role of granulosa cells and their derivatives in the process of follicular maturation, fertilization, and early embryonic development.