Einfluss proinflammatorischer Zytokine auf die A-beta-Sekretion mononukleärer Phagozyten

Background and aims Alzheimers disease (AD) is a progressive neurodegenerative illness and the most frequent cause for dementia. One of the main neuropathological findings in AD are senile β-amyloid depostis (plaques) in the brain parenchyma and in the walls of cerebral vessels. Their major components are A-peptides which are generated by proteolytic cleavage of the β-amyloid-precursor-protein (βAPP). Some findings suggest, that microglia and peripheral mononuclear cells, which both have common precursors and are part of the mononuclear phagocyte system (MPS), participate in the production of amyloid-deposits. Cleavage of βAPP results in the release of different Aβ-peptide species with heterogenous N- and C-termini. Additionally, a hallmark of AD pathology is the presence of other mediators of inflammation, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor-necrosis-factor-alpha (TNF alpha), granulocyte-macrophage-colony-stimulating-factor (GM-CSF). These cytokines are elevated within amyloid plaques, in serum and cerebrospinal fluid of AD-patients. The aim of this work was to investigate, in which way inflammatory cytokines influence the secretion of Aβ-peptides by cells of the MPS. Methods Human monocytes and macrophages and chicken-microglia were stimulated with different concentrations of IL-1β, IL-6, TNF alpha and GM-CSF. Subsequently, Aβ-peptides secreted into the cell culture supernatants were detected by SDS-PAGE and Western-immunoblot analysis and were quantified by densitometry. Differences in total release of Aβ-peptides and changes in the Aβ-peptide release pattern were investigated. Results and findings Total Aβ-peptide release of human monocytes was increased after stimulation with GM-CSF, but the propotion of single Aβ-peptide variants (Aβ release pattern) did not change. These findings were reproduced under different conditons of cultivation. IL-6 increased the total Aβ-peptide release of monocytes, macrophages and microglia. Additionally, IL-6 stimulation of macrophages lead to changes in the proportions of particular Aβ species. TNF-alpha and IL-1β did not influence the secretion of Aβ-peptide by mononuclear cells. Conclusions These findings suggest, that mononuclear cells increase their Aβ-peptide secretion under proinflammatory conditions. This was demonstrated by stimulation with IL-6 and GM-CSF. Inhibition of these cytokines might be a possible phamacological option for the treatment of AD.Hintergrund und Ziele Die Alzheimer-Krankheit (AK) ist eine progressive neurodegenerative Erkrankung und die häufigste Ursache für Demenz. Einer der wichtigsten neuropathologischen Befunde bei der AK sind die senilen β-Amyloid-Ablagerungen (Plaques) im Hirnparenchym und den zerebralen Blutgefässwänden. Hauptbestandteil der Plaques sind Aβ-Peptide, die durch proteolytische Spaltung des β-Amyloid-Vorläuferproteins (βAPP) generiert werden. Einige bisherige Untersuchungen deuten darauf hin, dass Mikroglia und transmigrierte monozytäre Zellen aus der Peripherie, welche gemeinsame Vorläufer haben und zum monozytären Phagozytensystem (MPS) gehören, an der Produktion von Aβ-Peptiden beteiligt sein können. Dabei werden verschiedene Aβ-Peptid-Spezies mit heterogenen C- und N-Termini freigesetzt. Neben Mikroglia spielen bei der Pathogenese der AK auch andere inflammatorische Mediatoren, wie Interleukin-1 (IL 1β), Interleukin 6 (IL-6), Tumor-Nekrose-Faktor-alpha (TNF-alpha), Granulozyten-Makrophagen Kolonie stimulierender Faktor (GM CSF) eine bedeutende Rolle. Diese Zytokine sind in der Umgebung von β Amyloid-Plaques, im Serum oder Liquor von Alzheimer-Patienten erhöht. Ziel dieser Arbeit ist es, zu untersuchen, in wie weit die Sekretion von Aβ-Peptiden durch Zellen des MPS unter der Stimulation mit proinflammatorischen Zytokinen beeinflusst wird. Methoden Humane Monozyten und Makrophagen sowie Hühnchen-Mikroglia wurden mit verschiedenen Konzentrationen der Zytokine IL-1β, IL-6, TNF alpha und GM CSF stimuliert. Anschließend wurden die sezernierten Aβ-Peptide in den Zellkulturüberständen durch Aβ-SDS Gelelektrophorese und Western-Immuno-Blot bestimmt und densitometrisch quantifiziert. Dabei wurden Veränderungen der Aβ-Gesamtsekretion sowie mögliche Veränderungen des Aβ-Sekretionsprofils unter Zytokin-Stimulation untersucht. Ergebnisse und Beobachtungen Die Aβ-Gesamtsekretion humaner Monozyten war nach Stimulation mit GM CSF erhöht, die Verhältnisse der einzelnen Aβ-Peptide zueinander (Aβ-Sekretionsmuster) blieben jedoch unverändert. Diese Beobachtungen konnten unter verschiedenen Kultivationsbedingungen reproduziert werden. IL-6 stimulierte die Aβ-Gesamtsekretion von Monozyten, Makrophagen und Mikroglia. Bei Makrophagen führte IL-6 zudem zu einer Veränderung einzelner Anteile von Aβ Spezies an der Gesamtsekretion. TNF alpha und IL-1β hatten keinen Einfluss auf die Aβ-Peptidsekretion mononukleärer Zellen. Praktische Schlussfolgerungen Die Ergebnisse dieser Arbeit zeigen, dass monozytäre Zellen unter proinflammatorischen Bedingungen eine gesteigerte Sekretion von Aβ Peptiden aufweisen können. Dieser Effekt konnte nach Stimulation mit IL 6 und GM-CSF nachgewiesen werden. Die Hemmung der Wirkung dieser Zytokine könnte eine mögliche zukünftige pharmakologische Option bei der Therapie der Alzheimer Krankheit darstellen

Overexpression of mouse prion protein in transgenic mice causes a non-transmissible spongiform encephalopathy

Transgenic mice over-expressing human PRNP or murine Prnp transgenes on a mouse prion protein knockout background have made key contributions to the understanding of human prion diseases and have provided the basis for many of the fundamental advances in prion biology, including the first report of synthetic mammalian prions. In this regard, the prion paradigm is increasingly guiding the exploration of seeded protein misfolding in the pathogenesis of other neurodegenerative diseases. Here we report that a well-established and widely used line of such mice (Tg20 or tga20), which overexpress wild-type mouse prion protein, exhibit spontaneous aggregation and accumulation of misfolded prion protein in a strongly age-dependent manner, which is accompanied by focal spongiosis and occasional neuronal loss. In some cases a clinical syndrome developed with phenotypic features that closely resemble those seen in prion disease. However, passage of brain homogenate from affected, aged mice failed to transmit this syndrome when inoculated intracerebrally into further recipient animals. We conclude that overexpression of the wild-type mouse prion protein can cause an age-dependent protein misfolding disorder or proteinopathy that is not associated with the production of an infectious agent but can produce a phenotype closely similar to authentic prion disease

Assessment of conformity of actual thoraco-lumbar pedicle screw dimensions to manufacturers’ specifications

Although correct selection of pedicle screw dimensions is indispensable to achieving optimum results, manufacturer-specified or intended dimensions may differ from actual dimensions. Here we analyzed the reliability of specifications made by various manufacturers by comparing them to the actual lengths and diameters of pedicle screws in a standardized experimental setup. We analyzed the actual length and diameter of pedicle screws of five different manufacturers. Four different screw lengths and for each length two different diameters were measured. Measurements were performed with the pedicle screws attached to a rod, with the length determined from the bottom of the tulip to the tip of the screw and the diameters determined at the proximal and distal threads. Differences in length of > 1 mm were found between the manufacturers’ specifications and our actual measurements in 24 different pedicle screws. The highest deviation of the measured length from the manufacturers’ specification was 3.2 mm. The difference in length between the shortest and longest screw with identical specifications was 3.4 mm. The highest deviation of the measured proximal thread diameters and the manufacturer’s specifications was 0.5 mm. The diameter of the distal thread depends on the shape of the pedicle screw and hence varies between manufacturers in conical screws. We found clear differences in the length of pedicle screws with identical manufacturer specifications. Since differences between the actual dimensions and the dimensions indicated by the manufacturer may vary, this needs to be taken into account during the planning of spine instrumentation

Protoplanetary disk evolution and stellar parameters of T Tauri binaries in Chamaeleon I

This study aims to determine the impact of stellar binary companions on the lifetime and evolution of circumstellar disks in the Chamaeleon I (Cha I) star-forming region by measuring the frequency and strength of accretion and circumstellar dust signatures around the individual components of T Tauri binary stars. We used high-angular resolution adaptive optics JHKL'-band photometry and 1.5-2.5mu spectroscopy of 19 visual binary and 7 triple stars in Cha I - including one newly discovered tertiary component - with separations between ~25 and ~1000au. The data allowed us to infer stellar component masses and ages and, from the detection of near-infrared excess emission and the strength of Brackett-gamma emission, the presence of ongoing accretion and hot circumstellar dust of the individual stellar component of each binary. Of all the stellar components in close binaries with separations of 25-100au, 10(+15-5)% show signs of accretion. This is less than half of the accretor fraction found in wider binaries, which itself appears significantly reduced (~44%) compared with previous measurements of single stars in Cha I. Hot dust was found around 50(+30-15)% of the target components, a value that is indistinguishable from that of Cha I single stars. Only the closest binaries (<25au) were inferred to have a significantly reduced fraction (<~25%) of components that harbor hot dust. Accretors were exclusively found in binary systems with unequal component masses M_secondary/M_primary < 0.8, implying that the detected accelerated disk dispersal is a function of mass-ratio. This agrees with the finding that only one accreting secondary star was found, which is also the weakest accretor in the sample. The results imply that disk dispersal is more accelerated the stronger the dynamical disk truncation, i.e., the smaller the inferred radius of the disk. (abridged)Comment: Accepted for publication in A&A. 25 pages, 20 figure

Diverse imaging features of adolescent glioblastoma

We highlight an unusual case of multifocal glioblastoma in an adolescent patient, manifesting as four discrete brain lesions, each distinct in appearance. Familiarity with the diverse imaging features of glioblastoma can reduce misdiagnosis and avoid treatment delays

Prediction of the Topography of the Corticospinal Tract on T1-Weighted MR Images Using Deep-Learning-Based Segmentation

Introduction: Tractography is an invaluable tool in the planning of tumor surgery in the vicinity of functionally eloquent areas of the brain as well as in the research of normal development or of various diseases. The aim of our study was to compare the performance of a deep-learning-based image segmentation for the prediction of the topography of white matter tracts on T1-weighted MR images to the performance of a manual segmentation. Methods: T1-weighted MR images of 190 healthy subjects from 6 different datasets were utilized in this study. Using deterministic diffusion tensor imaging, we first reconstructed the corticospinal tract on both sides. After training a segmentation model on 90 subjects of the PIOP2 dataset using the nnU-Net in a cloud-based environment with graphical processing unit (Google Colab), we evaluated its performance using 100 subjects from 6 different datasets. Results: Our algorithm created a segmentation model that predicted the topography of the corticospinal pathway on T1-weighted images in healthy subjects. The average dice score was 0.5479 (0.3513–0.7184) on the validation dataset. Conclusions: Deep-learning-based segmentation could be applicable in the future to predict the location of white matter pathways in T1-weighted scans

Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells

The final published version can be found here: http://dx.doi.org/10.1073/pnas.141316511

Artificial intelligence in histopathological image analysis of central nervous system tumours: A systematic review

The convergence of digital pathology and artificial intelligence could assist histopathology image analysis by providing tools for rapid, automated morphological analysis. This systematic review explores the use of artificial intelligence for histopathological image analysis of digitised central nervous system (CNS) tumour slides. Comprehensive searches were conducted across EMBASE, Medline and the Cochrane Library up to June 2023 using relevant keywords. Sixty-eight suitable studies were identified and qualitatively analysed. The risk of bias was evaluated using the Prediction model Risk of Bias Assessment Tool (PROBAST) criteria. All the studies were retrospective and preclinical. Gliomas were the most frequently analysed tumour type. The majority of studies used convolutional neural networks or support vector machines, and the most common goal of the model was for tumour classification and/or grading from haematoxylin and eosin-stained slides. The majority of studies were conducted when legacy World Health Organisation (WHO) classifications were in place, which at the time relied predominantly on histological (morphological) features but have since been superseded by molecular advances. Overall, there was a high risk of bias in all studies analysed. Persistent issues included inadequate transparency in reporting the number of patients and/or images within the model development and testing cohorts, absence of external validation, and insufficient recognition of batch effects in multi-institutional datasets. Based on these findings, we outline practical recommendations for future work including a framework for clinical implementation, in particular, better informing the artificial intelligence community of the needs of the neuropathologist

An additional human chromosome 21 causes suppression of neural fate of pluripotent mouse embryonic stem cells in a teratoma model

Background: Down syndrome (DS), caused by trisomy of human chromosome 21 (HSA21), is the most common genetic cause of mental retardation in humans. Among complex phenotypes, it displays a number of neural pathologies including smaller brain size, reduced numbers of neurons, reduced dendritic spine density and plasticity, and early Alzheimer-like neurodegeneration. Mouse models for DS show behavioural and cognitive defects, synaptic plasticity defects, and reduced hippocampal and cerebellar neuron numbers. Early postnatal development of both human and mouse-model DS shows the reduced capability of neuronal precursor cells to generate neurons. The exact molecular cause of this reduction, and the role played by increased dosage of individual HSA21 genes, remain unknown.Results: We have subcutaneously injected mouse pluripotent ES cells containing a single freely segregating supernumerary human chromosome 21 (HSA21) into syngeneic mice, to generate transchromosomic teratomas. Transchromosomic cells and parental control cells were injected into opposite flanks of thirty mice in three independent experiments. Tumours were grown for 30 days, a time-span equivalent to combined intra-uterine, and early post-natal mouse development. When paired teratomas from the same animals were compared, transchromosomic tumours showed a three-fold lower percentage of neuroectodermal tissue, as well as significantly reduced mRNA levels for neuron specific (Tubb3) and glia specific (Gfap) genes, relative to euploid controls. Two thirds of transchromosomic tumours also showed a lack of PCR amplification with multiple primers specific for HSA21, which were present in the ES cells at the point of injection, thus restricting a commonly retained trisomy to less than a third of HSA21 genes.Conclusion: We demonstrate that a supernumerary chromosome 21 causes Inhibition of Neuroectodermal Differentiation (INDI) of pluripotent ES cells. The data suggest that trisomy of less than a third of HSA21 genes, in two chromosomal regions, might be sufficient to cause this effect