Amyloid-ß levels and cognitive trajectories in non-demented pTau181-positive subjects without amyloidopathy.

Phosphorylated Tau181 (pTau181) in CSF and recently in plasma has been associated with Alzheimer's disease. In the absence of amyloidopathy, individuals with increased total Tau levels and/or temporal lobe atrophy experience no or only mild cognitive decline compared with biomarker-negative controls, leading to the proposal to categorize this constellation as suspected non-Alzheimer's disease pathophysiology (SNAP). We investigated whether the characteristics of SNAP also applied to individuals with increased CSF-pTau181 without amyloidopathy. In this long-term observational study, 285 non-demented individuals, including 76 individuals with subjective cognitive impairment and 209 individuals with mild cognitive impairment, were classified based on their CSF levels of pTau181 (T), total Tau (N), amyloid-ß42 (Aß42) and Aß42/Aß40 ratio (A) into A+T+N±, A+T-N±, A-T+N±, and A-T-N-. The longitudinal analysis included 154 subjects with a follow-up of more than 12 months who were followed to a median of 4.6 years (interquartile range = 4.3 years). We employed linear mixed models on psychometric tests and region of interest analysis of structural MRI data. Cognitive decline and hippocampal atrophy rate were significantly higher in A+T+N± compared to A-T+N±, whereas there was no difference between A-T+N± and A-T-N-. Furthermore, there was no significant difference between A-T+N± and controls in dementia risk [hazard ratio 0.3, 95% confidence interval (0.1, 1.9)]. However, A-T+N± and A-T-N- could be distinguished based on their Aß42 and Aß40 levels. Both Aß40 and Aß42 levels were significantly increased in A-T+N± compared to controls. Long term follow-up of A-T+N± individuals revealed no evidence that this biomarker constellation was associated with dementia or more severe hippocampal atrophy rates compared to controls. However, because of the positive association of pTau181 with Aß in the A-T+N± group, a link to the pathophysiology of Alzheimer's disease cannot be excluded in this case. We propose to refer to these individuals in the SNAP group as 'pTau and Aß surge with subtle deterioration' (PASSED). The investigation of the circumstances of simultaneous elevation of pTau and Aß might provide a deeper insight into the process under which Aß becomes pathological.

Analysis of Surface Levels of IL-1 Receptors and Macrophage Scavenger Receptor I in Peripheral Immune Cells of Patients With Alzheimer Disease.

Increased concentrations of interleukin 1 (IL-1) in the cerebrospinal fluid and serum of patients with Alzheimer disease (AD) reduced phagocytic capacity point to an inflammatory activation of mononuclear phagocytes in AD. Interleukin 1 receptors (IL-1R) and the macrophage scavenger receptor I (MSRI) are important players in IL-1 signaling and phagocytosis. In 20 patients with AD and 17 controls, IL-1RI, IL-1RII, and MSRI were assessed on peripheral blood mononuclear cells by flow cytometry. IL-1ß, soluble IL-1 receptors, and IL-1R antagonist (IL-1Ra) were measured by enzyme-linked immunosorbent assay. The fraction of IL-1RI+ monocytes was increased by 10% and the expression of MSRI was reduced by 12% in AD. A 3.6% increased fraction of IL-1RI+ lymphocytes was accompanied by a 6.1% reduced expression of IL-1RII. The IL-1RI on monocytes and lymphocytes discriminated patients with AD with an accuracy of 0.79 and 0.75, respectively. The IL-1Ra was elevated in AD. Changes in the expression of IL-1 receptors and MSRI on peripheral blood cells fit to the concept of a proinflammatory state of the peripheral immune system. However, the observed differences are not strong enough to suggest their application as biomarkers for AD.

Astrocytes and microglia but not neurons preferentially generate N-terminally truncated Aß peptides.

The neuropathological hallmarks of Alzheimer's disease include extracellular neuritic plaques and neurofibrillary tangles. The neuritic plaques contain ß-amyloid peptides (Aß peptides) as the major proteinaceous constituent and are surrounded by activated microglia and astrocytes as well as dystrophic neurites. N-terminally truncated forms of Aß peptides are highly prevalent in neuritic plaques, including Aß 3-x beginning at Glu eventually modified to pyroglutamate (Aß N3pE-x), Aß 2-x, Aß 4-x, and Aß 5-x. The precise origin of the different N-terminally modified Aß peptides currently remains unknown. To assess the contribution of specific cell types to the formation of different N-terminally truncated Aß peptides, supernatants from serum-free primary cell cultures of chicken neurons, astrocytes, and microglia, as well as human astrocytes, were analyzed by Aß-ELISA and one- and two-dimensional SDS-urea polyacrylamide gel electrophoresis followed by immunoblot analysis. To evaluate the contribution of ß- and γ-secretase to the generation of N-terminally modified Aß, cultured astrocytes were treated with membrane-anchored "tripartite ß-secretase (BACE1) inhibitors" and the γ-secretase inhibitor DAPT. Neurons, astrocytes, and microglia each exhibited cell type-specific patterns of secreted Aß peptides. Neurons predominantly secreted Aß peptides that begin at Asp1, whereas those released from astrocytes and microglia included high proportions of N-terminally modified Aß peptides, presumably including Aß 2/3-x and 4/5-x. The inhibition of BACE1 reduced the amount of Aß 1-x in cell culture supernatants but not the amount of Aß 2-x.

Spot quantification in two dimensional gel electrophoresis image analysis: comparison of different approaches and presentation of a novel compound fitting algorithm.

BACKGROUND: Various computer-based methods exist for the detection and quantification of protein spots in two dimensional gel electrophoresis images. Area-based methods are commonly used for spot quantification: an area is assigned to each spot and the sum of the pixel intensities in that area, the so-called volume, is used a measure for spot signal. Other methods use the optical density, i.e. the intensity of the most intense pixel of a spot, or calculate the volume from the parameters of a fitted function. RESULTS: In this study we compare the performance of different spot quantification methods using synthetic and real data. We propose a ready-to-use algorithm for spot detection and quantification that uses fitting of two dimensional Gaussian function curves for the extraction of data from two dimensional gel electrophoresis (2-DE) images. The algorithm implements fitting using logical compounds and is computationally efficient. The applicability of the compound fitting algorithm was evaluated for various simulated data and compared with other quantification approaches. We provide evidence that even if an incorrect bell-shaped function is used, the fitting method is superior to other approaches, especially when spots overlap. Finally, we validated the method with experimental data of urea-based 2-DE of Aß peptides andre-analyzed published data sets. Our methods showed higher precision and accuracy than other approaches when applied to exposure time series and standard gels. CONCLUSION: Compound fitting as a quantification method for 2-DE spots shows several advantages over other approaches and could be combined with various spot detection methods.The algorithm was scripted in MATLAB (Mathworks) and is available as a supplemental file.

N-truncation and pyroglutaminylation enhances the opsonizing capacity of Aß-peptides and facilitates phagocytosis by macrophages and microglia.

Abnormal accumulations of amyloid-ß (Aß)-peptides are one of the pathological hallmarks of Alzheimer's disease (AD). The precursor of the Aß-peptides, the amyloid precursor protein (APP), is also found in peripheral blood cells, but its function in these cells remains elusive. We previously observed that mononuclear phagocytes release Aß-peptides during activation and phagocytosis, suggesting a physiologic role in inflammatory processes. Here, we show that supplementing the media with soluble N-terminally truncated Aß(2-40) and Aß(2-42) as well as Aß(1-42) induced the phagocytosis of polystyrene particles (PSPs) by primary human monocytes. If the PSPs were pre-incubated with Aß-peptides, phagocytosis was induced by all tested Aß-peptide species. N-terminally truncated Aß(x-42) induced the phagocytosis of PSPs significantly more effectively than did Aß(x-40). Similarly, the phagocytosis of Escherichia coli by GM-CSF- and M-CSF-elicited macrophages as well as microglia was particularly facilitated by pre-incubation with N-terminally truncated Aß(x-42). The proinflammatory polarization of monocytes was indicated by the reduced MSRI expression and IL-10 secretion after phagocytosis of PSPs coated with Aß(1-42), Aß(2-42) and Aß(3p-42). Polarization of the macrophages by GM-CSF reduced the phagocytic activity, but it did not affect the capabilities of Aß-peptides to opsonize prey. Taken together, Aß-peptides support phagocytosis as soluble factors and act as opsonins. Differential effects among the Aß-peptide variants point to distinct mechanisms of interaction among monocytes/macrophages, prey and Aß-peptides. A proinflammatory polarization induced by the phagocytosis of Aß-peptide coated particles may provide a model for the chronic inflammatory reaction and sustained plaque deposition in AD.

Facilitative effects of VNS on the motor threshold: implications for its antidepressive mode of action?

In the present study, the effects of vagus nerve stimulation (VNS) on the resting motor threshold (rMT) of patients treated with repetitive transcranial magnetic stimulation were evaluated. Patients showed a significant decrease in the rMT during VNS-on stimulation. VNS was the only significant factor affecting rMT changes and did not appear to be a static variable. Further studies should focus on the effect of VNS on neural neurogenesis in depressive disorders, and the effects of other treatment options for major depressive disorder on the rMT should also be determined.

The effects of stimulation parameters on clinical outcomes in patients with vagus nerve stimulation implants with major depression.

Stimulation techniques, such as vagus nerve stimulation, are a promising new approach for treatment-resistant depression. Most international studies have used fixed stimulation parameters or have varied the stimulation frequencies. Our retrospective examination of 2 parallel groups of 10 patients each compared low-strength/high-frequency vagus nerve stimulation parameters (≤1.5 mA, 20 Hz) with high-strength/low-frequency ( >1.5 mA, 15 Hz) parameters. We found a significant decrease in the Hamilton Rating Scale for Depression scores in patients who were treated using the low-strength/high-frequency stimulation parameters. In contrast, the scores of the patients treated with high-strength/low-frequency stimulation did not change.

Reconceptualization of the Erlangen Score for the Assessment of Dementia Risk: The ERlangen Score.

BACKGROUND: The established Erlangen Score (ES) for the interpretation of cerebrospinal fluid (CSF) biomarkers in the diagnostics of Alzheimer's disease (AD) uses markers of amyloidopathy and tauopathy, equally weighted to form an easy-interpretable ordinal scale. However, these biomarkers are not equally predictive for AD. OBJECTIVE: The higher weighting of the Aß42/Aß40 ratio, as a reconceptualized ERlangen Score (ERS), was tested for advantages in diagnostic performance. METHODS: Non-demented subjects (N = 154) with a mean follow up of 5 years were assigned to a group ranging from 0 to 4 in ES or ERS. Psychometric trajectories and dementia risk were assessed. RESULTS: The distribution of subjects between ES and ERS among the groups differed considerably, as grouping allocated 32 subjects to ES group 2, but only 2 to ERS group 2. The discriminative accuracy between the ES (AUC 73.2%, 95% CI [64.2, 82.2]) and ERS (AUC 72.0%, 95% CI [63.1, 81.0]) for dementia risk showed no significant difference. Without consideration of the Aß42/Aß40 ratio in ES grouping, the optimal cut-off of the ES shifted to ≥2. CONCLUSIONS: The ERS showed advantages over the ES in test interpretation with comparable overall test performance, as fewer cases were allocated to the intermediate risk group. The established cut-off of ≥2 can be maintained for the ERS, whereas it must be adjusted for the ES when determining the Aß42/Aß40 ratio.

Digit Ratio (2D:4D) Is Not Associated with Alzheimer's Disease in the Elderly.

The development of Alzheimer's disease (AD) is influenced by sex hormones-estrogens and androgens in particular. However, the impact of prenatal sex hormone exposure is less clear; very few investigations have examined the relationship between the second-to-fourth digit length ratio (2D:4D), a putative proxy for the ratio of prenatal estrogens to androgens, and AD, with inconsistent results among the few that have. Therefore, we aimed to investigate this relationship using methodologically robust metrics. In a 2 (sex) × 4 (group) MANOVA incorporating 108 participants (30 AD patients, 19 patients with tauopathy but no amyloidopathy, 31 clinical and 28 healthy age- and education-matched controls), the effects of sex and group on the dependent variables right and left 2D:4D were examined. We also explored the association between 2D:4D and the severity of AD symptoms assessed via neuropsychological examination. We did not find any significant differences in the right- and left-hand 2D:4D between patients with AD and the other groups; no significant associations between 2D:4D and neuropsychological task performances were found in the dementia groups. The 2D:4D of healthy women was significantly lower than that of depressed women without AD, i.e., clinical controls, but not significantly different from depressed female patients with AD. This investigation does not support the role of 2D:4D in the development or severity of AD in general, but suggests a potential role of 2D:4D for depression in women. Future studies are warranted to clarify whether 2D:4D can distinguish between early- and late-onset depression in women.

PASSED: Brain atrophy in non-demented individuals in a long-term longitudinal study from two independent cohorts.

Introduction: Alzheimer's disease (AD) is indicated by a decrease in amyloid beta 42 (Aß42) level or the Aß42/Aß40 ratio, and by increased levels of Tau with phosphorylated threonine at position 181 (pTau181) in cerebrospinal fluid (CSF) years before the onset of clinical symptoms. However, once only pTau181 is increased, cognitive decline in individuals with subjective or mild cognitive impairment is slowed compared to individuals with AD. Instead of a decrease in Aß42 levels, an increase in Aß42 was observed in these individuals, leading to the proposal to refer to them as nondemented subjects with increased pTau-levels and Aß surge with subtle cognitive deterioration (PASSED). In this study, we determined the longitudinal atrophy rates of AD, PASSED, and Biomarker-negative nondemented individuals of two independent cohorts to determine whether these groups can be distinguished by their longitudinal atrophy patterns or rates. Methods: Depending on their CSF-levels of pTau 181 (T), total Tau (tTau, N), Aß42 or ratio of Aß42/Aß40 (A), 185 non-demented subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and 62 non-demented subjects from Erlangen AD cohort were assigned to an ATN group (A-T-N-, A-T+N±, A+T-N±and A+T+N±) and underwent T1-weighted structural magnetic resonance imaging (sMRI). Longitudinal grey matter (GM) atrophy patterns were assessed with voxel-based morphometry (VBM) using the cat12 toolbox on spm12 (statistical parametric mapping) of MRI scans from individuals in the ADNI cohort with a mean follow-up of 2 and 5 years, respectively. The annualized atrophy rate for individuals in the Erlangen cohort was determined using region of interest analysis (ROI) in terms of a confirmatory analysis. Results: In the A-T+N± group, VBM did not identify any brain region that showed greater longitudinal atrophy than the A+T+N±, A+T+N± or biomarker negative control group. In contrast, marked longitudinal atrophy in the temporal lobe was evident in the A+T-N± group compared with A+T-N± and biomarker-negative subjects. The ROI in the angular gyrus identified by VBM analysis of the ADNI cohort did not discriminate better than the hippocampal volume and atrophy rate between AD and PASSED in the confirmatory analysis. Discussion: In this study, nondemented subjects with PASSED did not show a unique longitudinal atrophy pattern in comparison to nondemented subjects with AD. The nonsignificant atrophy rate compared with controls suggests that increased pTau181-levels without concomitant amyloidopathy did not indicate a neurodegenerative disorder.

Cerebrospinal fluid biomarkers for cerebral amyloid angiopathy.

Integrating cerebrospinal fluid-biomarkers into diagnostic workup of patients with sporadic cerebral amyloid angiopathy may support early and correct identification. We aimed to identify and validate clinical- and cerebrospinal fluid-biomarkers for in vivo diagnosis of cerebral amyloid angiopathy. This observational cohort study screened 2795 consecutive patients admitted for cognitive complaints to the academic departments of neurology and psychiatry over a 10-year period (2009-2018). We included 372 patients with available hemosiderin-sensitive MR imaging and cerebrospinal fluid-based neurochemical dementia diagnostics, i.e. Aß40, Aß42, t-tau, p-tau. We investigated the association of clinical- and cerebrospinal fluid-biomarkers with the MRI-based diagnosis of cerebral amyloid angiopathy, applying confounder-adjusted modelling, receiver operating characteristic and unsupervised cluster analyses. We identified 67 patients with cerebral amyloid angiopathy, 76 patients with Alzheimer's disease, 75 patients with mild cognitive impairment due to Alzheimer's disease, 76 patients with mild cognitive impairment with unlikely Alzheimer's disease and 78 healthy controls. Patients with cerebral amyloid angiopathy showed a specific cerebrospinal fluid pattern: average concentration of Aß40 [13 792 pg/ml (10 081-18 063)] was decreased compared to all controls (P < 0.05); Aß42 [634 pg/ml (492-834)] was comparable to Alzheimer's disease and mild cognitive impairment due to Alzheimer's disease (P = 0.10, P = 0.93) but decreased compared to mild cognitive impairment and healthy controls (both P < 0.001); p-tau [67.3 pg/ml (42.9-91.9)] and t-tau [468 pg/ml (275-698)] were decreased compared to Alzheimer's disease (P < 0.001, P = 0.001) and mild cognitive impairment due to Alzheimer's disease (P = 0.001, P = 0.07), but elevated compared to mild cognitive impairment and healthy controls (both P < 0.001). Multivariate modelling validated independent clinical association of cerebral amyloid angiopathy with older age [odds-ratio: 1.06, 95% confidence interval (1.02-1.10), P < 0.01], prior lobar intracerebral haemorrhage [14.00 (2.64-74.19), P < 0.01], prior ischaemic stroke [3.36 (1.58-7.11), P < 0.01], transient focal neurologic episodes (TFNEs) [4.19 (1.06-16.64), P = 0.04] and gait disturbance [2.82 (1.11-7.15), P = 0.03]. For cerebrospinal fluid-biomarkers per 1 pg/ml, both lower Aß40 [0.9999 (0.9998-1.0000), P < 0.01] and lower Aß42 levels [0.9989 (0.9980-0.9998), P = 0.01] provided an independent association with cerebral amyloid angiopathy controlled for all aforementioned clinical confounders. Both amyloid biomarkers showed good discrimination for diagnosis of cerebral amyloid angiopathy among adjusted receiver operating characteristic analyses (area under the receiver operating characteristic curves, Aß40: 0.80 (0.73-0.86), P < 0.001; Aß42: 0.81 (0.75-0.88), P < 0.001). Unsupervised Euclidian clustering of all cerebrospinal fluid-biomarker-profiles resulted in distinct segregation of cerebral amyloid angiopathy patients from all controls. Together, we demonstrate that a distinctive set of cerebrospinal fluid-biomarkers effectively differentiate cerebral amyloid angiopathy patients from patients with Alzheimer's disease, mild cognitive impairment with or without underlying Alzheimer's disease, and healthy controls. Integrating our findings into a multiparametric approach may facilitate diagnosing cerebral amyloid angiopathy, and may aid clinical decision-making, but warrants future prospective validation.

Correlation between homocysteine serum levels and the duration of seizures in patients treated with electroconvulsive therapy.

Little is known about homocysteine and related changes in serum levels in patients receiving ECT. This study examined relationships between levels of homocysteine and seizure duration in 11 patients with depression receiving electroconvulsive therapy. Elevated homocysteine levels, such as have been associated in other studies with cellular damage, were not observed.

Persecution-induced reduction in earning capacity of Holocaust victims: influence of psychiatric and somatic aspects.

The incidence of mental and somatic sequelae is very high in the group of persons damaged by the Holocaust. Based on the sociomedical criteria prevailing in Germany, the assessment of persecution-induced reduction in earning capacity of Holocaust victims (vMdE) is mainly orientated towards direct Holocaust-induced somatic and mental sequelae but must also take into account the interaction of direct Holocaust-induced damage with subsequently acquired physical, mental, and psychosocial factors. The current medical evaluation is focused on the question whether persecution-induced symptoms are exacerbated by endogenous factors like mental or somatic diseases and/or exogenous factors like life events. In that case the grade of vMdE could be increased. Based on the synopsis of 56 Holocaust victims, we ascertained in this study that newly acquired somatic diseases and psychic morbidities contribute to an increase in persecution-induced mental complaints.

Cerebrospinal Fluid of Patients With Alzheimer's Disease Contains Increased Percentages of Synaptophysin-Bearing Microvesicles.

INTRODUCTION: In Alzheimer's disease, the severity of symptoms is linked to a loss of synaptic density and the spread of pathologically hyperphosphorylated tau. The established cerebrospinal fluid markers Aß, tau and phospho-tau reflect the histopathological hallmarks of Alzheimer's disease but do not indicate disease progression. Such markers are of special interest, especially for trials of disease modifying drugs. Microvesicles are produced by stressed cells and reflect part of the metabolism of their cells of origin. Therefore, we investigated microvesicles of neuronal origin in cerebrospinal fluid. MATERIALS AND METHODS: We used flow cytometry to analyze microvesicles carrying tau, phospho-tau-Thr181, phospho-tau-Ser202Thr205, synaptophysin, and SNAP-25 in the cerebrospinal fluid of 19 patients with Alzheimer's disease and 15 non-inflammatory neurological disease controls. RESULTS: The percentages of synaptophysin-bearing microvesicles were significantly higher in the cerebrospinal fluid of patients with Alzheimer's disease than in the CSF of non-inflammatory neurological disease controls. Tau, phospho-tau-Thr181, phospho-tau-Ser202Thr205, and SNAP-25 did not differ between the groups. The percentages of synaptophysin-bearing vesicles distinguished patients with Alzheimer's disease from the controls (AUC = 0.81). CONCLUSION: The loss of synapses in Alzheimer's disease may be reflected by synaptophysin-bearing microvesicles in the cerebrospinal fluid. Future studies are needed to investigate the possibility of using these MVs as a marker to determine the activity of Alzheimer's disease.

Phagocytosis and LPS alter the maturation state of ß-amyloid precursor protein and induce different Aß peptide release signatures in human mononuclear phagocytes.

BACKGROUND: The classic neuritic ß-amyloid plaque of Alzheimer's disease (AD) is typically associated with activated microglia and neuroinflammation. Similarly, cerebrovascular ß-amyloid (Aß) deposits are surrounded by perivascular macrophages. Both observations indicate a contribution of the mononuclear phagocyte system to the development of ß-amyloid. METHODS: Human CD14-positive mononuclear phagocytes were isolated from EDTA-anticoagulated blood by magnetic activated cell sorting. After a cultivation period of 72 hours in serum-free medium we assessed the protein levels of amyloid precursor protein (APP) as well as the patterns and the amounts of released Aß peptides by ELISA or one-dimensional and two-dimensional urea-based SDS-PAGE followed by western immunoblotting. RESULTS: We observed strong and significant increases in Aß peptide release upon phagocytosis of acetylated low density lipoprotein (acLDL) or polystyrene beads and also after activation of the CD14/TLR4 pathway by stimulation with LPS. The proportion of released N-terminally truncated Aß variants was increased after stimulation with polystyrene beads and acLDL but not after stimulation with LPS. Furthermore, strong shifts in the proportions of single Aß1-40 and Aß2-40 variants were detected resulting in a stimulus-specific Aß signature. The increased release of Aß peptides was accompanied by elevated levels of full length APP in the cells. The maturation state of APP was correlated with the release of N-terminally truncated Aß peptides. CONCLUSIONS: These findings indicate that mononuclear phagocytes potentially contribute to the various N-truncated Aß variants found in AD ß-amyloid plaques, especially under neuroinflammatory conditions.

Pharmacological Inhibition of Amyloidogenic APP Processing and Knock-Down of APP in Primary Human Macrophages Impairs the Secretion of Cytokines.

It has been previously shown that the amyloid precursor protein (APP) support the innate immune defense as an immune receptor. Amyloid ß (Aß) peptides seem to have properties of an antimicrobial peptide and can act as opsonines. In APP-deficient mouse models, a reduced secretion of cytokines has been observed. Still, it is unclear whether this can be attributed to the lack of APP or to the missing secretion of Aß peptides. We inhibited the secretion of Aß peptides in primary human monocyte derived macrophages with the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine-t-butyl-ester (DAPT) or the ß-secretase inhibitor GL-189. Alternatively, we knocked down APP by transfection with siRNA. We measured tumor necrosis factor α (TNFα), interleukin 6 (IL-6) and interleukin (IL-10) by enzyme linked immunosorbent assay (ELISA) and evaluated the phagocytotic activity by flow cytometry. We observed reduced concentrations of TNFα and IL-6 in the media of APPk/d macrophages and after inhibition of the ß-, or γ-secretase, especially after additional immunological activation with lipopolysaccharide (LPS). Secretion of IL-10 was increased after pharmacological inhibition of APP processing when the macrophages were not immunologically activated but was decreased during LPS-induced inflammation in APPk/d macrophages. No changes of the phagocytotic activity were observed. We conclude that macrophage APP and Aß peptides support the initiation of an immune response and are involved in the regulation of TNFα, IL-6, and IL-10 secretion by human monocyte-derived macrophages.

The Role of Cathepsin B in the Degradation of Aß and in the Production of Aß Peptides Starting With Ala2 in Cultured Astrocytes.

Astrocytes may not only be involved in the clearance of Amyloid beta peptides (Aß) in Alzheimer's disease (AD), but appear to produce N-terminally truncated Aß (Aßn-x) independently of BACE1, which generates the N-Terminus of Aß starting with Asp1 (Aß1-x). A candidate protease for the generation of Aßn-x is cathepsin B (CatB), especially since CatB has also been reported to degrade Aß, which could explain the opposite roles of astrocytes in AD. In this study, we investigated the influence of CatB inhibitors and the deletion of the gene encoding CatB (CTSB) using CRISPR/Cas9 technology on Aß2-x and Aß1-x levels in cell culture supernatants by one- and two-dimensional Urea-SDS-PAGE followed by immunoblot. While the cell-permeant inhibitors E64d and CA-074 Me did not significantly affect the Aß1-x levels in supernatants of cultured chicken and human astrocytes, they did reduce the Aß2-x levels. In the glioma-derived cell line H4, the Aß2-x levels were likewise decreased in supernatants by treatment with the more specific, but cell-impermeant CatB-inhibitor CA-074, by CA-074 Me treatment, and by CTSB gene deletion. Additionally, a more than 2-fold increase in secreted Aß1-x was observed under the latter two conditions. The CA-074 Me-mediated increase of Aß1-x, but not the decrease of Aß2-x, was influenced by concomitant treatment with the vacuolar H+-ATPase inhibitor Bafilomycin A1. This indicated that non-lysosomal CatB mediated the production of Aß2-x in astrocytes, while the degradation of Aß1-x seemed to be dependent on lysosomal CatB in H4 cells, but not in primary astrocytes. These findings highlight the importance of considering organelle targeting in drug development to promote Aß degradation.

DSC Brain Perfusion Using Advanced Deconvolution Models in the Diagnostic Work-up of Dementia and Mild Cognitive Impairment: A Semiquantitative Comparison with HMPAO-SPECT-Brain Perfusion.

BACKGROUND: SPECT (single-photon emission-computed tomography) is used for the detection of hypoperfusion in cognitive impairment and dementia but is not widely available and related to radiation dose exposure. We compared the performance of DSC (dynamic susceptibility contrast) perfusion using semi- and fully adaptive deconvolution models to HMPAO-SPECT (99mTc-hexamethylpropyleneamine oxime-SPECT). MATERIAL AND METHODS: Twenty-seven patients with dementia of different subtypes including frontotemporal dementia (FTD) and mild cognitive impairment (MCI) received a multimodal diagnostic work-up including DSC perfusion at a clinical 3T high-field scanner and HMPAO-SPECT. Nineteen healthy control individuals received DSC perfusion. For calculation of the hemodynamic parameter maps, oscillation-index standard truncated singular value decomposition (oSVD, semi-adaptive) as well as Bayesian parameter estimation (BAY, fully adaptive) were performed. RESULTS: Patients showed decreased cortical perfusion in the left frontal lobe compared to controls (relative cerebral blood volume corrected, rBVc: 0.37 vs 0.27, p = 0.048, adjusted for age and sex). Performance of rBVc (corrected for T1 effects) was highest compared to SPECT for detection of frontal hypoperfusion (sensitivity 83%, specificity 80% for oSVD and BAY, area under curve (AUC) = 0.833 respectively, p < 0.05) in FTD and MCI. For nonleakage-corrected rBV and for rBF (relative cerebral blood flow), sensitivity of frontal hypoperfusion was above 80% for oSVD and for BAY (rBV: sensitivity 83%, specificity 75%, AUC = 0.908 for oSVD and 0.917 for BAY, p < 0.05 respectively; rBF: sensitivity 83%, specificity 65%, AUC = 0.825, p < 0.05 for oSVD). CONCLUSION: Advanced deconvolution DSC can reliably detect pathological perfusion alterations in FTD and MCI. Hence, this widely accessible technique has the potential to improve the diagnosis of dementia and MCI as part of an interdisciplinary multimodal imaging work-up. Advances in knowledge: Advanced DSC perfusion has a high potential in the work-up of suspected dementia and correlates with SPECT brain perfusion results in dementia and MCI.

Distinct fractional Abeta release patterns in human mononuclear phagocytes.

The presence of cells of the mononuclear phagocyte lineage surrounding neuritic and vascular beta-amyloid (Abeta) plaques is a hallmark of Alzheimer's disease (AD) neuropathology. The fractional Abeta peptide patterns released by human mononuclear phagocyte (MNP), lymphocyte and PBMC cultures were assessed by Abeta-SDS-PAGE/immunoblot and compared with the Abeta patterns in neuronal supernatants, in cerebrospinal fluid (CSF), and plasma. MNP released substantial amounts of Abeta peptides and the Abeta pattern contrasted with that in neuronal supernatants, CSF and plasma by reduced Abeta(1-42) and increased proportions of N-truncated Abeta species. MNP derived from early AD patients released significantly more total Abeta peptides than age-matched controls. The proportion of Abeta(1-42) was not altered.

Microvesicles from cerebrospinal fluid of patients with Alzheimer's disease display reduced concentrations of tau and APP protein.

Microvesicles are small membranous particles generated during cellular activation or stress. The analysis of the content and the surface of microvesicles allow conclusions about the cells they are originating from and the underlying pathology. Therefore, CSF microvesicles have been suggested to be promising targets to monitor the (etio)pathology of neurodegenerative diseases. Microvesicles in the CSF of 15 patients with Alzheimer's disease and 15 controls were analyzed by flow cytometry regarding the levels of CD3, CD4, CD45, CD64, BACE1, Aß, APP and tau. The results were replicated in a second cohort comprising 14 patients with Alzheimer's disease and 9 controls. The levels of tau and APP were reduced in microvesicles of Alzheimer's disease patients. A significant change was neither observed in the number of microvesicles nor in the expression of the other antigens. Tau and APP in microvesicles separated patients with Alzheimer's disease from controls with an AUC of 0.84 and 0.89 respectively. We conclude that tau and APP in CSF microvesicles are promising biomarkers which could directly provide information about the Alzheimer pathology on a cellular level.