Dirk Jacobs

C-terminal neurogranin is increased in cerebrospinal fluid but unchanged in plasma in Alzheimer's disease

Biomarkers monitoring synaptic degeneration/loss would be valuable for Alzheimers disease (AD) diagnosis. Postsynaptic protein neurogranin may be a promising cerebrospinal fluid (CSF) biomarker but has not yet been evaluated as a plasma biomarker.

Tau monoclonal antibody generation based on humanized yeast models: impact on Tau oligomerization and diagnostics.

Background: Oligomers of protein Tau are associated with neurodegenerative diseases. Results: New antibodies were generated and validated that recognize different degrees of oligomerization of protein Tau. Conclusion: Low order and higher order oligomers differ in C-terminal Tau phosphorylation and reflect consecutive stages in disease progression. Significance: Antibodies recognizing Tau oligomers provide insight into disease etiology and are promising diagnostic tools. A link between Tau phosphorylation and aggregation has been shown in different models for Alzheimer disease, including yeast. We used human Tau purified from yeast models to generate new monoclonal antibodies, of which three were further characterized. The first antibody, ADx201, binds the Tau proline-rich region independently of the phosphorylation status, whereas the second, ADx215, detects an epitope formed by the Tau N terminus when Tau is not phosphorylated at Tyr18. For the third antibody, ADx210, the binding site could not be determined because its epitope is probably conformational. All three antibodies stained tangle-like structures in different brain sections of THY-Tau22 transgenic mice and Alzheimer patients, and ADx201 and ADx210 also detected neuritic plaques in the cortex of the patient brains. In hippocampal homogenates from THY-Tau22 mice and cortex homogenates obtained from Alzheimer patients, ADx215 consistently stained specific low order Tau oligomers in diseased brain, which in size correspond to Tau dimers. ADx201 and ADx210 additionally reacted to higher order Tau oligomers and presumed prefibrillar structures in the patient samples. Our data further suggest that formation of the low order Tau oligomers marks an early disease stage that is initiated by Tau phosphorylation at N-terminal sites. Formation of higher order oligomers appears to require additional phosphorylation in the C terminus of Tau. When used to assess Tau levels in human cerebrospinal fluid, the antibodies permitted us to discriminate patients with Alzheimer disease or other dementia like vascular dementia, indicative that these antibodies hold promising diagnostic potential.

The Cerebrospinal Fluid Neurogranin/BACE1 Ratio is a Potential Correlate of Cognitive Decline in Alzheimer's Disease.

Background: In diagnosing Alzheimer’s disease (AD), ratios of cerebrospinal fluid (CSF) biomarkers, such as CSF Aβ1-42/tau, have an improved diagnostic performance compared to the single analytes, yet, still a limited value to predict cognitive decline. Since synaptic dysfunction/loss is closely linked to cognitive impairment, synaptic proteins are investigated as candidate CSF AD progression markers. Objective: We studied CSF levels of the postsynaptic protein neurogranin and protein BACE1, predominantly localized presynaptically, and their relation to CSF total-tau, Aβ1-42, Aβ1-40, and Aβ1-38. All six analytes were considered as single parameters as well as ratios. Methods: Every ELISA involved was based on monoclonal antibodies, including the BACE1 and neurogranin immunoassay. The latter specifically targets neurogranin C-terminally truncated at P75, a more abundant species of the protein in CSF. We studied patients with MCI due to AD (n = 38) and 50 dementia due to AD patients, as well as age-matched cognitively healthy elderly (n = 20). A significant subset of the patients was followed up by clinical and neuropsychologically (MMSE) examinations for at least one year. Results: The single analytes showed statistically significant differences between the clinical groups, but the ratios of analytes indeed had a higher diagnostic performance. Furthermore, only the ratio of CSF neurogranin trunc P75/BACE1 was significantly correlated with the yearly decline in MMSE scores in patients with MCI and dementia due to AD, pointing toward the prognostic value of the ratio. Conclusion: This is the first study demonstrating that the CSF neurogranin trunc P75/BACE1 ratio, reflecting postsynaptic/presynaptic integrity, is related to cognitive decline.

Detection and quantification of novel tau/phospho-tau epitopes in CSF using a multiplex assay approach

internationally accepted criteria, and AD cases were further classified for the presence of cerebrovascular disease (CBVD). Controls with no history of stroke and cognitive impairment were selected from the Singapore Epidemiology of Eye Disease program and matched by race, gender and 5year age groups. Retinal vascular parameters (retinal vascular caliber, fractal dimension and tortuosity) were assessed using a semi-automated computer-based program. Due to its skewed distribution, retinal vessel tortuosity was log-transformed. Logistic regression models were constructed adjusting for gender, age, hypertension, diabetes and hypercholesterolemia status. Results: A total of 156 AD cases (98 without CBVD and 58with CBVD), 27 vascular dementia cases, and 493 controls were included in this preliminary analysis. Narrower arteriolar caliber was associated with VaD (multivariable-adjusted odds ratio (OR) per standard deviation (SD) decrease: 2.41; 95%CI: 1.13-5.14) and AD with CBVD (OR per SD decrease: 1.84; 95%CI: 1.05-3.23). Narrower venular caliber (OR per SD decrease: 1.72; 95%CI: 1.11-2.68), decreased arteriolar fractal dimension (OR per SD decrease: 1.29; 95%CI: 1.03-1.61) and venular fractal dimension (OR per SD increase: 1.36; 95%CI: 1.08-1.72) were associated with only AD without CBVD. However, increased arteriolar and venular tortuosity was associated with all three subtypes of dementia. Conclusions: A sparser retinal microvascular network was associated with AD, whereas narrower arterioles were associated with dementia linked to CBVD, and tortuous retinal vessels were associated with all three subtypes of dementia. This suggests that retinal vascular parameters may potentially useful in assessing the contribution of microvascular pathology to the different subtpyes of dementia.

Neurogranin and BACE1 in CSF as Potential Biomarkers Differentiating Depression with Cognitive Deficits from Early Alzheimer’s Disease: A Pilot Study

Background/Aims: Major depressive disorder (MDD) can cooccur with early Alzheimer’s disease (AD) or may cause memory problems independently of AD. Previous studies have suggested that the AD-related cerebrospinal fluid (CSF) biomarkers tau and Aβ(1–42) could help discriminate between early AD and depression unrelated to AD. Moreover, the postsynaptic protein neurogranin and presynaptic BACE1 have increasingly gained attention as potential new AD biomarkers, but they have not yet been investigated concerning depression. Methods: Using ELISAs, we studied CSF neurogranin and BACE1 levels in patients with mild (n = 21) and moderate (n = 19) AD, as well as in MDD patients with (n = 20) and without (n = 20) cognitive deficits. The clinical examinations included analyses of t-tau, Aβ(1–42), and Aβ(1–40), besides neuropsychological tests and cranial magnetic resonance imaging. Depressive symptom severity was assessed using the Geriatric Depression Scale (GDS). Results: Along with classic AD biomarkers, neurogranin and BACE1 CSF levels differed between moderate AD and MDD (p ≤ 0.01). MDD associated with cognitive deficits was distinguished from mild AD through the CSF neurogranin/BACE1 ratio (p < 0.05), which was strongly correlated with GDS scores (ρ = –0.656; p < 0.01). Conclusion: The neurogranin/BACE1 ratio in CSF can distinguish between depression and AD among patients with similar cognitive deficits, along with the classic AD biomarkers. Further longitudinal studies are ongoing to identify which biomarkers have prognostic value.

THE RATIO OF NEUROGRANIN/BACE1 IN CSF FACILITATES CLINICAL ASSIGNMENT OF COGNITIVE DYSFUNCTION IN MILD ALZHEIMER'S DISEASE AND DEPRESSED PATIENTS WITHOUT ALZHEIMER'S DISEASE

Luc Tritsmans, Luc Van Nueten, Niels Andreassen, Sebastiaan Engelborghs, Janssen Research & Development, Beerse, Belgium; 2 Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, M€ olndal, Sweden; Ortho-McNeil Pharmaceutical, Raritan, NJ, USA; Janssen Research & Development, Titusville, NJ, USA; 5 Hospital Mutua de Terrasa, Servicio de Neurologia, Terrassa, Spain; Hospital Universitario La Paz, Madrid, Spain; Hospital Clinico San Carlos, Servicio de Neurologia, Madrid, Spain; Fundaci o ACE, Barcelona, Alzheimer Treatment & Research Center, Barcelona, Spain; 9 Hospital Universitari La Fe Avinguda Abril Martorell, Valencia, Spain; Karolinska Institutet, Stockholm, Sweden; Department of Neurology and Memory Clinic, Hospital Network Antwerp (ZNA) Middelheim and Hoge Beuken, Antwerp, Belgium. Contact e-mail: jstreffe@its.jnj.com

A monoclonal antibody-based elisa for neurogranin

individual CSF samples selected to cover the clinically relevant range of Ab42 concentrations. The most promising candidate CRM formats (neat CSF and CSF spiked with Ab42) were identified and subjected to validation across eight different (Elecsys, EUROIMMUN, IBL, INNO-BIA AlzBio3, INNOTEST, MSD,Simoa, and Saladax) commercial immunoassays as well as SRM LC-MS in another set of 32 individual CSF samples. Commutability was evaluated by Passing-Bablok regression and the candidate CRMwas termed commutablewhen found within the prediction interval. Results:The neat CSF candidate CRM format was found to be commutable for all pairwise method comparisons, except for the Simoa/MSD, Simoa/SRM and SRM/IBL comparisons, where the results were outside the 95% prediction interval. However, the neat CSF was found to be within 5% relative distance to the regression line for the comparison between SRM/IBL, between 5-10% for Simoa/SRM and between 10-15% for Simoa/MSD. Conclusions: The neat CSF candidate CRM format was found to be highly commutable for all method comparisons, with only three exceptions. For these three exceptions, the relative distance to the regression line was close to being acceptable. We conclude that it will be possible to use the neat CSF as a CRM for value assignment of kit calibrators.