Activin is produced by rat Sertoli cells in vitro and can act as an autocrine regulator of Sertoli cell function

Regulation of androgen receptor (AR) mRNA expression was studied in Sertoli cells and peritubular myoid cells isolated from immature rat testis, and in the lymph node carcinoma cell line derived from a human prostate (LNCaP). Addition of dibutyryl-cyclic AMP (dbcAMP) to Sertoli cell cultures resulted in a rapid transient decrease in AR mRNA expression (5 h), which was followed by a gradual increase in AR mRNA expression (24-72 h). This effect of dbcAMP mimicked follicle-stimulating hormone (FSH) action. In peritubular myoid cells, there was only a moderate but prolonged decrease during incubation in the presence of dbcAMP, and in LNCaP cells no effect of dbcAMP on AR mRNA expression was observed. When Sertoli cells or peritubular myoid cells were cultured in the presence of androgens, AR mRNA expression in these cell types did not change. This is in contrast to LNCaP cells, that showed a marked reduction of AR mRNA expression during androgen treatment. In the present experiments, transcriptional regulation of AR gene expression in Sertoli cells and LNCaP cells was also examined. Freshly isolated Sertoli cell clusters were transfected with a series of luciferase reporter gene constructs, driven by the AR promoter. It was found that addition of dbcAMP to the transfected Sertoli cells resulted in a small but consistent increase in reporter gene expression (which was interpreted as resulting from AR promoter activity); a construct that only contained the AR 5' untranslated region of the cDNA sequence did not show such a regulation. The same constructs, transfected into LNCaP cells, did not show any transcriptional down-regulation when the synthetic androgen R1881 was added to the cell cultures. A nuclear transcription elongation experiment (run-on), however, demonstrated that androgen-induced AR mRNA down-regulation in LNCaP cells resulted from an inhibition of AR gene transcription. The present results indicate that in Sertoli cells and LNCaP cells, hormonal effects on AR gene transcription play a role in regulation of AR expression. However, AR gene transcription in these cells is differentially regulated

Effect of the micro-environment on alpha-synuclein conversion and implication in seeded conversion assays

Background: α-Synuclein is a small soluble protein, whose physiological function in the healthy brain is poorly understood. Intracellular inclusions of α-synuclein, referred to as Lewy bodies (LBs), are pathological hallmarks of α- synucleinopathies, such as Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). Main body: Understanding of the molecular basis as well as the factors or conditions promoting α-synuclein misfolding and aggregation is an important step towards the comprehension of pathological mechanism of α- synucleinopathies and for the development of efficient therapeutic strategies. Based on the conversion and aggregation mechanism of α-synuclein, novel diagnostic tests, such as protein misfolding seeded conversion assays, e.g. the real-time quaking-induced conversion (RT-QuIC), had been developed. In diagnostics, α-synuclein RT-QuIC exhibits a specificity between 82 and 100% while the sensitivity varies between 70 and 100% among different laboratories. In addition, the α-synuclein RT-QuIC can be used to study the α-synuclein-seeding-characteristics of different α-synucleinopathies and to differentiate between DLB and PD. Conclusion: The variable diagnostic accuracy of current α-synuclein RT-QuIC occurs due to different protocols, cohorts and material etc.. An impact of micro-environmental factors on the α-synuclein aggregation and conversion process and the occurrence and detection of differential misfolded α-synuclein types or strains might underpin the clinical heterogeneity of α-synucleinopathies

Plasma amyloid-β levels, cerebral atrophy and risk of dementia: A population-based study

Background: Plasma amyloid-β (Aβ) levels are increasingly studied as a potential accessible marker of cognitive impairment and dementia. However, it remains underexplored whether plasma Aβ levels including the novel Aβ peptide 1-38 (Aβ1-38) relate to preclinical markers of neurodegeneration and risk of dementia. We investigated the association of plasma Aβ1-38, Aβ1-40, and Aβ1-42 levels with imaging markers of neurodegeneration and risk of dementia in a prospective population-based study. Methods: We analyzed plasma Aβ levels in 458 individuals from the Rotterdam Study. Brain volumes, including gray matter, white matter, and hippocampus, were computed on the basis of 1.5-T magnetic resonance imaging (MRI). Dementia and its subtypes were defined on the basis of internationally accepted criteria. Results: A total of 458 individuals (mean age, 67.8 ± 7.7 yr; 232 [50.7%] women) with baseline MRI scans and incident dementia were included. The mean ± SD values of Aβ1-38, Aβ1-40, and Aβ1-42 (in pg/ml) were 19.4 ± 4.3, 186.1 ± 35.9, and 56.3 ± 6.2, respectively, at baseline. Lower plasma Aβ1-42 levels were associated with smaller hippocampal volume (mean difference in hippocampal volume per SD decrease in Aβ1-42 levels, - 0.13; 95% CI, - 0.23 to - 0.04; p = 0.007). After a mean follow-up of 14.8 years (SD, 4.9; range, 4.1-23.5 yr), 79 persons developed dementia, 64 of whom were diagnosed with Alzheimer's disease (AD). Lower levels of Aβ1-38 and Aβ1-42 were associated with increased risk of dementia, specifically AD (HR for AD per SD decrease in Aβ1-38 levels, 1.39; 95% CI, 1.00-2.16; HR for AD per SD decrease in Aβ1-42 levels, 1.35; 95% CI, 1.05-1.75) after adjustment for age, sex, education, cardiovascular risk factors, apolipoprotein E ϵ4 allele carrier status, and other Aβ isoforms. Conclusions: Our results show that lower plasma Aβ levels were associated with risk of dementia and incident AD. Moreover, lower plasma Aβ1-42 levels were related to smaller hippocampal volume. These results suggest that plasma Aβ1-38 and Aβ1-42 maybe useful biomarkers for identification of individuals at risk of dementia

Core Alzheimer’s disease cerebrospinal fluid biomarker assays are not affected by aspiration or gravity drip extraction methods

Background: CSF biomarkers are well-established for routine clinical use, yet a paucity of comparative assessment exists regarding CSF extraction methods during lumbar puncture. Here, we compare in detail biomarker profiles in CSF extracted using either gravity drip or aspiration. Methods: Biomarkers for β-amyloidopathy (Aβ1–42, Aβ1–40), tauopathy (total tau), or synapse pathology (BACE1, Neurogranin Trunc-p75, α-synuclein) were assessed between gravity or aspiration extraction methods in a sub-population of the Australian Imaging, Biomarkers and Lifestyle (AIBL) study (cognitively normal, N = 36; mild cognitive impairment, N = 8; Alzheimer’s disease, N = 6). Results: High biomarker concordance between extraction methods was seen (concordance correlation \u3e 0.85). Passing Bablock regression defined low beta coefficients indicating high scalability. Conclusions: Levels of these commonly assessed CSF biomarkers are not influenced by extraction method. Results of this study should be incorporated into new consensus guidelines for CSF collection, storage, and analysis of biomarkers

Plasma glial fibrillary acidic protein is elevated in cognitively normal older adults at risk of Alzheimer’s disease

© 2021, The Author(s). Glial fibrillary acidic protein (GFAP), an astrocytic cytoskeletal protein, can be measured in blood samples, and has been associated with Alzheimer’s disease (AD). However, plasma GFAP has not been investigated in cognitively normal older adults at risk of AD, based on brain amyloid-β (Aβ) load. Cross-sectional analyses were carried out for plasma GFAP and plasma Aβ1–42/Aβ1–40 ratio, a blood-based marker associated with brain Aβ load, in participants (65–90 years) categorised into low (Aβ−, n = 63) and high (Aβ+, n = 33) brain Aβ load groups via Aβ positron emission tomography. Plasma GFAP, Aβ1–42, and Aβ1–40 were measured using the Single molecule array (Simoa) platform. Plasma GFAP levels were significantly higher (p \u3c 0.00001), and plasma Aβ1–42/Aβ1–40 ratios were significantly lower (p \u3c 0.005), in Aβ+ participants compared to Aβ− participants, adjusted for covariates age, sex, and apolipoprotein E-ε4 carriage. A receiver operating characteristic curve based on a logistic regression of the same covariates, the base model, distinguished Aβ+ from Aβ− (area under the curve, AUC = 0.78), but was outperformed when plasma GFAP was added to the base model (AUC = 0.91) and further improved with plasma Aβ1–42/Aβ1–40 ratio (AUC = 0.92). The current findings demonstrate that plasma GFAP levels are elevated in cognitively normal older adults at risk of AD. These observations suggest that astrocytic damage or activation begins from the pre-symptomatic stage of AD and is associated with brain Aβ load. Observations from the present study highlight the potential of plasma GFAP to contribute to a diagnostic blood biomarker panel (along with plasma Aβ1–42/Aβ1–40 ratios) for cognitively normal older adults at risk of AD

CSF Aβ42/Aβ40 and Aβ42/Aβ38 ratios: better diagnostic markers of Alzheimer disease

OBJECTIVE: The diagnostic accuracy of cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) must be improved before widespread clinical use. This study aimed to determine whether CSF Aβ42/Aβ40 and Aβ42/Aβ38 ratios are better diagnostic biomarkers of AD during both predementia and dementia stages in comparison to CSF Aβ42 alone. // METHODS: The study comprised three different cohorts (n = 1182) in whom CSF levels of Aβ42, Aβ40, and Aβ38 were assessed. CSF Aβs were quantified using three different immunoassays (Euroimmun, Meso Scale Discovery, Quanterix). As reference standard, we used either amyloid (18F‐flutemetamol) positron emission tomography (PET) imaging (n = 215) or clinical diagnosis (n = 967) of well‐characterized patients. // RESULTS: When using three different immunoassays in cases with subjective cognitive decline and mild cognitive impairment, the CSF Aβ42/Aβ40 and Aβ42/Aβ38 ratios were significantly better predictors of abnormal amyloid PET than CSF Aβ42. Lower Aβ42, Aβ42/Aβ40, and Aβ42/Aβ38 ratios, but not Aβ40 and Aβ38, correlated with smaller hippocampal volumes measured by magnetic resonance imaging. However, lower Aβ38, Aβ40, and Aβ42, but not the ratios, correlated with non‐AD‐specific subcortical changes, that is, larger lateral ventricles and white matter lesions. Further, the Aβ42/Aβ40 and Aβ42/Aβ38 ratios showed increased accuracy compared to Aβ42 when distinguishing AD from dementia with Lewy bodies or Parkinson's disease dementia and subcortical vascular dementia, where all Aβs (including Aβ42) were decreased. //INTERPRETATION: The CSF Aβ42/Aβ40 and Aβ42/Aβ38 ratios are significantly better than CSF Aβ42 to detect brain amyloid deposition in prodromal AD and to differentiate AD dementia from non‐AD dementias. The ratios reflect AD‐type pathology better, whereas decline in CSF Aβ42 is also associated with non‐AD subcortical pathologies. These findings strongly suggest that the ratios rather than CSF Aβ42 should be used in the clinical work‐up of AD

The Alzheimer's Disease Neuroimaging Initiative 2 Biomarker Core: A review of progress and plans

INTRODUCTION: We describe Alzheimer's Disease Neuroimaging Initiative (ADNI) Biomarker Core progress including: the Biobank; cerebrospinal fluid (CSF) amyloid beta (Aβ1-42), t-tau, and p-tau181 analytical performance, definition of Alzheimer's disease (AD) profile for plaque, and tangle burden detection and increased risk for progression to AD; AD disease heterogeneity; progress in standardization; and new studies using ADNI biofluids. METHODS: Review publications authored or coauthored by ADNI Biomarker core faculty and selected non-ADNI studies to deepen the understanding and interpretation of CSF Aβ1-42, t-tau, and p-tau181 data. RESULTS: CSF AD biomarker measurements with the qualified AlzBio3 immunoassay detects neuropathologic AD hallmarks in preclinical and prodromal disease stages, based on CSF studies in non-ADNI living subjects followed by the autopsy confirmation of AD. Collaboration across ADNI cores generated the temporal ordering model of AD biomarkers varying across individuals because of genetic/environmental factors that increase/decrease resilience to AD pathologies. DISCUSSION: Further studies will refine this model and enable the use of biomarkers studied in ADNI clinically and in disease-modifying therapeutic trials

Elevated plasma sclerostin is associated with high brain amyloid-b load in cognitively normal older adults

Osteoporosis and Alzheimer’s disease (AD) mainly affect older individuals, and the possibility of an underlying link contributing to their shared epidemiological features has rarely been investigated. In the current study, we investigated the association between levels of plasma sclerostin (SOST), a protein primarily produced by bone, and brain amyloid-beta (A ) load, a pathological hallmark of AD. The study enrolled participants meeting a set of screening inclusion and exclusion criteria and were stratified into A − (n = 65) and A + (n = 35) according to their brain A load assessed using A -PET (positron emission tomography) imaging. Plasma SOST levels, apolipoprotein E gene (APOE) genotype and several putative AD blood-biomarkers including A 40, A 42, A 42/A 40, neurofilament light (NFL), glial fibrillary acidic protein (GFAP), total tau (t-tau) and phosphorylated tau (p-tau181 and p-tau231) were detected and compared. It was found that plasma SOST levels were significantly higher in the A + group (71.49 ± 25.00 pmol/L) compared with the A − group (56.51 ± 22.14 pmol/L) (P \u3c 0.01). Moreover, Spearman’s correlation analysis showed that plasma SOST concentrations were positively correlated with brain A load (ρ = 0.321, P = 0.001). Importantly, plasma SOST combined with A 42/A 40 ratio significantly increased the area under the curve (AUC) when compared with using A 42/A 40 ratio alone (AUC = 0.768 vs 0.669, P = 0.027). In conclusion, plasma SOST levels are elevated in cognitively unimpaired older adults at high risk of AD and SOST could complement existing plasma biomarkers to assist in the detection of preclinical AD

CERTIFICATION REPORT: The certification of Amyloid β1-42 in CSF in ERM®-DA480/IFCC, ERM®-DA481/IFCC and ERM®-DA482/IFCC

This report describes the production of ERM®-DA480/IFCC, ERM®-DA481/IFCC and ERM®-DA482/IFCC, which are human cerebrospinal fluid (CSF) materials certified for the mass concentration of amyloid β1-42 peptide (Aβ1-42). These materials were produced by the European Commission, Joint Research Centre (EC-JRC) in collaboration with the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) following ISO Guide 34:2009 and are certified in accordance with ISO Guide 35:2006. The starting material used to prepare ERM-DA480/IFCC, ERM-DA481/IFCC and ERM-DA482/IFCC was human CSF collected from normal pressure hydrocephalus patients by continuous lumbar drainage. After collection, the CSF was aliquoted and frozen at -80 °C. For the preparation of each certified reference material (CRM) a selected number of CSF donations were thawed, pooled, mixed, filled in microvials and stored at (-70 ± 10) °C immediately thereafter. Between unit-homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006 [ ]. The material was characterised by an interlaboratory comparison of laboratories of demonstrated competence and adhering to ISO/IEC 17025 [ ]. Technically invalid results were removed but no outlier was eliminated on statistical grounds only. Uncertainties of the certified values were calculated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) [ ] and include uncertainties related to possible inhomogeneity, instability and characterisation. The materials are intended for the calibration of methods, quality control and/or the assessment of method performance. As with any reference material, they can be used for establishing control charts or validation studies. The CRMs are available in microvials containing at least 0.5 mL of frozen liquid. The minimum amount of sample to be used is 15 µL.JRC.F.6-Reference Material

Plasma amyloid‐beta levels in a pre‐symptomatic dutch‐type hereditary cerebral amyloid angiopathy pedigree: A cross‐sectional and longitudinal investigation

Plasma amyloid‐beta (Aβ) has long been investigated as a blood biomarker candidate for Cerebral Amyloid Angiopathy (CAA), however previous findings have been inconsistent which could be attributed to the use of less sensitive assays. This study investigates plasma Aβ alterations between pre‐symptomatic Dutch‐type hereditary CAA (D‐CAA) mutation‐carriers (MC) and non-carriers (NC) using two Aβ measurement platforms. Seventeen pre‐symptomatic members of a D‐ CAA pedigree were assembled and followed up 3–4 years later (NC = 8;MC = 9). Plasma Aβ1‐40 and Aβ1‐42 were cross‐sectionally and longitudinally analysed at baseline (T1) and follow‐up (T2) and were found to be lower in MCs compared to NCs, cross‐sectionally after adjusting for covari-ates, at both T1(Aβ1‐40: p = 0.001; Aβ1‐42: p = 0.0004) and T2 (Aβ1‐40: p = 0.001; Aβ1‐42: p = 0.016) employing the Single Molecule Array (Simoa) platform, however no significant differences were observed using the xMAP platform. Further, pairwise longitudinal analyses of plasma Aβ1‐40 revealed decreased levels in MCs using data from the Simoa platform (p = 0.041) and pairwise longitudinal analyses of plasma Aβ1‐42 revealed decreased levels in MCs using data from the xMAP platform (p = 0.041). Findings from the Simoa platform suggest that plasma Aβ may add value to a panel of biomarkers for the diagnosis of pre‐symptomatic CAA, however, further validation studies in larger sample sets are required