12033 research outputs found
Sort by
Strukturelle Veränderungen des Nucleus dentatus bei Mutationsträger*innen mit spinozerebellärer Ataxie Typ 3 / Machado-Joseph-Krankheit
Full text linkDie spinozerebelläre Ataxie Typ 3 (SCA3) ist eine autosomal-dominant vererbte CAG-Triplett-Expansions-Erkrankung. In der manifesten (ataktischen) Phase der SCA3 ist diese klinisch von einer progredienten Ataxie gekennzeichnet. Dieser Phase geht ein prä-ataktisches Stadium voraus, das keine oder allenfalls eine geringe klinische Symptomatik zeigt.
Es existiert bislang kein geeigneter Progressionsmarker für dieses Stadium der Erkrankung. Vor diesem Hintergrund wurde in der vorliegenden Arbeit untersucht, ob sich die auf MRT-Aufnahmen miterfassten zerebellären Kerne und im Besonderen der Ncl. dentatus dazu eignen, die Dynamik der Erkrankung abzubilden.
Zur Untersuchung dieser Fragestellung wurde die Studienkohorte der "European Spinocerebellar Ataxia Type 3 / Machado-Joseph-Disease Initiative (ESMI)", einer multizentrischen und longitudinalen Studie, verwendet. SCA3-Mutationsträger*innen wurden in prä-ataktische und ataktische Mutationsträger*innen unter Verwendung des SARA, unterteilt. Zudem lagen Untersuchungen von gesunden Kontrollen im Vergleich vor.
Der Querschnittsvergleich und die univariate Varianzanalyse der Kernvolumina zum Zeitpunkt der Baseline-Untersuchung zeigten in der Gruppe sowohl der prä-ataktischen als auch der ataktischen Studienteilnehmer*innen ein statistisch signifikant geringeres Kernvolumen im Vergleich zu den gesunden Kontrollen (p
Der Querschnittsvergleich und die univariate Varianzanalyse der Volumendifferenzen zwischen Baseline- und 1-Jahres-Verlaufs-Untersuchung zeigten insbesondere im prä-ataktischen Stadium einen Trend zur Volumenabnahme, der allerdings keine statistische Signifikanz erreichte.
Die dargestellten Zusammenhänge sollten in longitudinalen Studien mit einer höheren Anzahl von Verlaufs-Untersuchungen der prä-ataktischen Mutationsträger*innen und einer höheren Auflösung der verwendeten Scans, mit bspw. eisensensitiven Sequenzen, weiter eruiert werden, um genauere Aussagen bzgl. der Eignung des Ncl. dentatus als Progressionsmarker der SCA3 treffen zu können.
Trotz der genannten Limitationen konnte durch diese Arbeit gezeigt werden, dass die strukturellen Veränderungen der zerebellären Kerne und des Ncl. dentatus bereits im prä-ataktischen Stadium der Erkrankung auffällig sind und somit das Potential haben, einen Bildgebungs-Progressionsmarker für die SCA3, im Besonderen für das prä-ataktische Stadium der Erkrankung, darzustellen
High-throughput sequencing data analyses across multiple approaches
No full text(noch nicht zugänglich / not yet accessible
Antibiotic-induced cellular effects in <em>Wolbachia</em>: Insights from cell wall biosynthesis inhibitors and corallopyronin A
No full text(noch nicht zugänglich / not yet accessible
Impact of dietary interventions on metabolism and the gut-brain axis in adults with metabolic syndrome traits
No full textIn recent decades, the incidence of obesity and obesity-associated comorbidities such as the metabolic syndrome has exponentially increased in both developed and developing counties. It is widely accepted that inadequate dietary intake, especially a high consumption of ultra-processed, energy-dense foods and sugar-sweetened beverages, which is defined as ‘Western-type’ dietary pattern, is a main contributor to this global development. The Western-type dietary pattern encourages hyperenergetic nutrition leading to weight gain and increased visceral adipose tissue accumulation, which can result in subclinical, systemic inflammation and whole body insulin resistance. Moreover, the Western-type diet has been associated with a dysbiosis of the gut microbiota and age-related cognitive decline and dementia including Alzheimer’s diseases (AD) in epidemiological studies. The aim of this randomized, controlled intervention trial in obese adults with a habitual Western-type diet is to determine the effects of acute and mid-term, potentially health-promoting, dietary interventions on metabolic functions and brain health elucidating underlying mechanisms.
One hundred and twenty obese, cognitively unimpaired adults aged 45 to 70 years with at least one metabolic syndrome trait including visceral fat distribution, (pre)hypertension, dyslipidemia, and a subclinical inflammation underwent a three hours mixed meal tolerance test (MMTT) for deep metabolic characterization. Fasting and multiple postprandial blood samples were collected to follow the time course of serum/plasma levels of insulin, glucose, blood lipids ((non)-LDL cholesterol, non-esterified fatty acids, and triglycerides), the gut hormone glucagon-like peptide 1 (GLP 1) and AD-related proteins (neurofilament light, glial fibrillary acidic protein, amyloid-beta 42/40, phosphorylated (phospho) tau 181 and 231, total-tau). Furthermore, genetic make-up, gut microbiome composition, and fecal microbial metabolites were analyzed. After completing the baseline visit, participants were randomly assigned to one of three study groups: the Nordic diet (ND) group, the lacto-ovo vegetarian diet (VD) group, or the control group (HD). The key components of the ND were berries, green leafy and root vegetables, whole grain from rye, spelt and oat, boiled potatoes, nuts, fish, and rapeseed oil. The VD comprised plant-derived foods complemented milk(products) and eggs. Both intervention diets were designed isoenergetically to ensure a constant body weight during the six weeks study period and were self-prepared by the participants according to detailed recipes. The HD group was instructed to maintain their habitual Western-type diet, physical activity level and body weight over the six weeks study duration. Compliance with the treatment was monitored using six weeks food diaries and a short-form questionnaire to review the frequency of consuming the key food items of the respective study diet as well as anthropometrics and several blood biomarkers as the fatty acids composition of the phospholipids or vitamin levels. After six weeks of dietary intervention, metabolite and microbiome analyses were repeated.
After six weeks of ND intervention, significant reductions in the concentrations of LDL- and non-LDL cholesterol fractions as well as triglycerides and liver enzymes were observed. Both the ND and VD study diet induced taxonomic alterations of the gut microbiome. Correlation analysis of metabolic markers (lipid metabolism and liver enzymes) and the individual microbes revealed more than 80 significant correlations before and after intervention, suggesting a possible involvement of specific microbes in metabolism and outcome measures of the dietary intervention. The success of the ND in reducing blood lipids was determined by the basal gut microbiota composition, as the largest diet-induced reductions were seen in individuals with a specific microbiome signature. Furthermore, it was observed that individuals with the highest genetic risk for dyslipidemia benefited the most from the ND intervention. In fasting and postprandial levels of GLP-1, glucose, insulin, and AD-related protein concentrations, no ND- or VD induced effects were found. However, poorer long-term glucose control and higher fasting plasma glucose levels were associated with higher fasting and postprandial plasma (phospho) tau levels. The consumption of the standardized meal (MMTT) led to immediate changes in AD-related protein concentrations, which exceeded biomarker dynamics observed in the fasting state and were directly attributed to food intake and associated metabolic events.
We concluded that specific microbial signatures and the individual genetic risk have a strong impact on the success of a dietary change, pointing towards a personalized nutrition approach in preventing cardiometabolic diseases. Because of the observed beneficial effects of the ND study diet on blood lipid profile and liver function, we concluded that the ND was superior to VD in reducing cardiometabolic risk factors. As both study diets were applied isoenergetically, the observed findings can directly be attributed to the specific key foods and nutrient profile of the respective dietary pattern. Furthermore, it was convincingly shown that food intake and glucose control have a decisive impact on the concentration of AD-related biomarkers, which should be considered when using these biomarkers for diagnosis and monitoring of disease progression and drug respons
Influence of antiviral RNA binding effector proteins on innate immune responses
No full textThe efficient elimination of viruses is initiated by the recognition of the viral nucleic acid genome or replication intermediates through innate immune receptors. Several different receptors specifically detect double stranded (ds) RNA: the RIG-I-like helicase (RLH) family including retinoic acid inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5), as well as receptors with direct antiviral activity like protein kinase R (PKR) and oligoadenylate synthetase (OAS) that activates ribonuclease L (RNase L). RLHs are the main interferon (IFN)-inducing receptors and initiate a strong antiviral response, while PKR and OAS/RNase L inhibit host and virus translation once dsRNA is sensed to limit viral replication.
This thesis showed that coactivation of PKR and OAS/RNase L inhibits the RIG-I-induced antiviral cytokine expression after stimulation with long triphosphorylated dsRNA (3P-dsRNA). These results were validated in PKR depleted primary human monocyte-derived macrophages, which demonstrated increased IFNα and interferon-stimulated gene (ISG) induction after stimulation with long 3P-dsRNA compared to wt cells. Polysome profiling showed a global PKR-mediated inhibition of translation when cells were stimulated with long 3P-dsRNA. qRT-PCR analysis of polysome fractions supported that finding, showing the inhibition of translation of CXCL10, IFNB1 and IFIT1 by PKR. The results obtained in this thesis indicate that the dsRNA receptors PKR and OAS/RNase L exert an inhibitory effect on RIG-I-induced type I IFN and ISG expression.
The dsRNA-binding protein interferon-inducible double-stranded RNA-dependent protein kinase activator A (PACT) is known to activate PKR and was described to bind to RLHs and modulate their activity. In this thesis, PACT was shown to support the RIG-I-mediated type I IFN induction upon recognition of long dsRNA like polyI:C but intriguingly does not enhance the response to short triphosphorylated dsRNA. Furthermore, it was found to enhance the RIG-I-dependent induction of IP10 during IAV ΔNS1 infection. The findings of this thesis reveal PACT as an important co-factor of RIG-I with clear ligand specificity.
An essential feature of the vertebrate antiviral defence is the discrimination between self and non-self nucleic acids. Posttranscriptional modifications of RNAs, such as the cap 1 structure, mark mRNA as self and thus prevent recognition by RIG-I. Some viruses like Yellow fever virus (YFV) exploit this mechanism to circumvent immune recognition. YFV is an arbovirus transmitted by mosquitoes which intriguingly are also able to distinguish between cap 0 and cap 1 structures, as shown in this thesis. Transfection of a synthetic reporter mRNA with a cap 1 structure led to higher reporter protein expression compared to an mRNA with a cap 0 structure. Intriguingly, this difference in expression varied between different cell lines, suggesting that the expression of a potential cap-recognising immune receptor is cell type-specific. Subsequent qRT-PCR analysis demonstrated that the cap structure does not influence mRNA stability in mosquito cells, hinting towards a translational inhibition of cap 0 mRNAs. The findings of this thesis reveal that not only the vertebrate but also the insect immune system is capable of discriminating between self and non-self nucleic acids.
In conclusion, the findings obtained in this thesis make an important contribution to the understanding of the interplay between the RNA receptors RIG-I, PKR and OAS/RNase L during viral infections, the action of the co-factor PACT in supporting RIG-I signalling, as well as the detection of viral RNAs in mosquitoes
Obesity impairs virus-specific memory CD8<sup>+</sup> T cell signalling and function
No full textThe main function of the immune system is to protect the host against invading pathogens. Immunological memory is formed after a primary infection and serves to provide protection in a fast and vigorous manner upon secondary encounter with the same pathogen. Under obesity conditions, however, protective immunity is impaired, constituting a significant risk factor for high incidence and severity of re-infections. Indeed, during the current COVID-19 pandemic, obesity has been recognized as a major risk factor for adverse clinical outcomes. Impaired immunity observed in obese individuals has been attributed to a dysfunction in CD8+ T cells, which are essential for the elimination and sterile clearance of viral infections. Yet, the underlying mechanisms of the immune-compromised status of obese individuals remain poorly understood.
Using mouse models of diet-induced obesity and lymphocytic choriomeningitis virus infection, we showed increased morbidity and mortality of obese mice after re-infection, recapitulating the clinical situation in humans. Obese mice failed to mount protective immunity and showed a profound loss of virus-specific memory CD8+ T cells in the spleen and liver. This phenotype was associated with a compromised proliferation capacity and reduced ability to produce the effector cytokines IFNg and TNFa. Furthermore, our data revealed a severe decline specifically within hepatic tissue-resident memory T cell pool, which positively correlated with the body weight and contributed to the severe symptoms observed in obese mice. Additionally, we observed enhanced accumulation of IgA+, IL-10 producing, and PD-L1+ B cells in the liver of obese mice, and their
absence was associated with normal numbers of hepatic tissue-resident memory T cells. Notably, genetic ablation of IL-10 production by B cells did not reconstitute the memory response, indicating that IgA+ B cells do not exert a suppressive effect towards the virus-specific CD8+ T cells via IL-10. Furthermore, our findings show that the impaired memory response in obese mice is due to T-cell intrinsic mechanisms driven by long-term exposure of virus-specific memory CD8+ T cells to the inflammatory environment, rather than by affecting their development and recruitment. Molecular analysis revealed transcriptional reprogramming of memory CD8+ T cells under obesity conditions, resulting in impaired T-cell receptor signaling. The obesity-inflicted changes in memory CD8+ T cells were highlighted by the impairment of Ca2+ influx upon CD8+ T cell stimulation in vitro. Collectively, our findings indicate that virus-specific memory CD8+ T cells exposed to an obese environment lose their ability to confer protection. The future intention of this project is to identify key molecules within the Ca2+ signalling pathway that could be therapeutically modulated to improve the ability of virus-specific memory CD8+ T cells to provide protection and to improve the immune response of obese individuals to re-infections
Generation of an isogenic stem cell model to decipher the pathogenesis of <em>SYNGAP1</em> syndrome in human neurons
No full textThe synaptic GTPase-activating protein SynGAP is an important constituent of the postsynaptic compartment. Haploinsufficiency of the SYNGAP1 gene is associated with a neurodevelopmental disorder characterized by mental retardation, moderate to severe intellectual disability, global developmental delay, and a generalized form of epilepsy. Most of the studies on SYNGAP1 syndrome were performed in Syngap1 +/- and -/- mouse models. Although animal-based experiments have made significant contributions to understanding disease mechanisms, these models are limited when it comes to human conditions, primarily due to major disparities in physiology and development. Here, we set out to model this disorder using isogenic engineered SYNGAP1 haploinsufficient human pluripotent stem cells and forward programmed them into neurons for disease modeling. SYNGAP1 +/- glutamatergic neurons (iGlutNs) showed increased Ras-GTP and phospho-Erk concentration, alterations in pathways downstream of SynGAP. These pathway alterations may contribute to increased neural complexity, as evidenced by the longer and more intricate dendritic structures observed in our model. At the synaptic level, we noted a general increase in spine surface area and length. Moreover, there was a rise in the proportion of mature, mushroom-shaped spines, suggesting enhanced differentiation. Electrophysiologically, at the network level, the SYNGAP1 +/- neurons showed a higher network burst frequency with concurrently shorter network bursts and fewer spikes per network burst, with overall lower synchrony. Additionally, SYNGAP1 +/- neurons demonstrated elevated expression of AMPA receptors, potentially leading to postsynaptic saturation. This saturation could result in the occlusion of long-term potentiation (LTP), a phenomenon that was confirmed through patch-clamp experiments. The increased network burst frequency and duration might be a phenotype originating from glutamatergic neurons, while the decreased number of spikes might evolve from GABAergic neurons, suggesting that SYNGAP1 also plays a role in inhibitory neurons. The pathoelectrophysiological network pattern might resemble the phenotypes to those found in primary neurons from mouse epilepsy models. Overall, these findings indicate that SynGAP, through alterations in RasGTP and Erk concentration may promote spine growth and synaptic strength through multiple pathways, including actin polymerization and AMPAR insertion. This ultimately may lead to impaired LTP resulting in altered neuronal activity
Effect of Microglial Purinergic P2Y12 Receptor on Efficiency of Beta-Amyloid Immunotherapy and Aging
No full textMicroglia, as the primary immune cells of the central nervous system (CNS), play a pivotal role in the efficiency of Aβ immunotherapy by facilitating β-amyloid clearance and forming a protective barrier around β-amyloid plaques. However, the signaling pathways underlying this Aβ antibody-induced effect in microglia remain elusive. P2Y12, a member of the purinergic receptor family expressed by microglia in the CNS, is involved in crucial microglial functions, including directed cell process movement, chemotaxis, and phagocytosis. Therefore, this project aimed to investigate the role of microglial P2Y12 in mediating Aβ clearance and directed cell migration toward plaques during Aβ immunotherapy using microglial cell culture and ex-vivo experimental approaches utilizing confocal microscopy or live-cell imaging. My findings demonstrate that P2Y12 receptor-mediated signaling enhances anti-Aβ antibody-mediated microglial directed cell movement, microglial uptake of synthetic Aβ and Aβ plaque material and contributes to amyloid plaque clearance in the presence of anti-Aβ antibody. Therefore, the study proposed the clinical significance of P2Y12 in mediating the therapeutic effect of developed anti-Aβ immunotherapy.
In the aging CNS, chronic inflammation, and adaptive immune responses, such as parenchymal T-cell infiltration, are observed. However, the role of microglia in regulating the adaptive immune response during aging remains poorly understood. P2Y12 has been implicated in cytokine and chemokine release in the aged brain. To investigate the role of P2Y12 for microglial activation in the aged brain, we conducted morphometric and transcriptomic analyses of microglia in adult and aged P2Y12 knockout and wild-type mice. Our transcriptomic analysis revealed a sex-dependent upregulation of activation-related and interferon-responsive genes in microglia from male adult P2Y12 knockout mice compared to wild-type mice. Morphological analysis showed aging-associated changes in microglia from aged P2Y12 knockout and wild-type mice, with fewer cell process ramifications, particularly pronounced in aged male P2Y12 knockout mice. Additionally, there was an exacerbated aging-associated periventricular infiltration of CD8+ T-cells in aged male P2Y12 knockout mice. In-vitro interferon-γ stimulation in primary microglia from P2Y12 knockout mice revealed an exacerbated cytokine and chemokine response, suggesting a role of P2Y12 in facilitating interferon-γ-induced chemokine release in microglia. These findings underscore a potential role of P2Y12 in mitigating aging-related microglial phenotype alterations and T-cell infiltration in a sex-dependent manner
Nutzen der MRT-basierten Fettquantifizierung zur nicht-invasiven Abschätzung des Differenzierungsgrades hepatozellulärer Karzinome
Full text linkZielsetzung
Die bildbasierte Detektion von intraläsionalem Fett in fokalen Leberläsionen ist in diagnostischen Leitlinien als charakteristisches Merkmal für das hepatozelluläre Karzinom (HCC) etabliert und wird mit einer günstigen Prognose assoziiert. Angesichts jüngster Fortschritte bei MRT-basierten Fettquantifizierungstechniken untersuchten wir eine mögliche Korrelation zwischen dem intraläsionalen Fettgehalt und dem histologischen Tumorgrading bei steatotischen HCCs.
Methoden
Patient*innen mit histopathologisch gesichertem HCC und vorangegangener MRT inklusive Protonen-Dichte-Fettanteil-Mapping (PDFF) wurden retrospektiv identifiziert. Das intraläsionale Fett der HCCs wurde mittels einer ROI-basierten Analyse bewertet. Der mediane Fettanteil der steatotischen HCCs wurde zwischen den Tumorgraden G1-3 mittels nicht-parametrischer Tests verglichen. Bei statistisch signifikanten Unterschieden (p
Ergebnisse
Insgesamt 57 Patient*innen mit steatotischen HCCs (62 Läsionen) wurden in die Analyse eingeschlossen. Der mediane Fettanteil war bei G1-Läsionen signifikant höher (Median [Interquartilsabstand]: 7,9 % [6,0–10,7 %]) als bei G2-Läsionen (4,4 % [3,2–6,6 %]; p = 0,001) und G3-Läsionen (4,7 % [2,8–7,8 %]; p = 0,036). Die PDFF erwies sich als guter Diskriminator zwischen G1- und G2/3-Läsionen (AUC 0,81; Cut-off 5,8 %, Sensitivität 83 %, Spezifität 68 %) mit vergleichbaren Ergebnissen bei Patient*innen mit Leberzirrhose. Bei Patient*innen mit Lebersteatose war der intraläsionale Fettgehalt höher als in der Gesamtstichprobe, wobei die PDFF hier eine noch bessere Differenzierung zwischen G1- und G2/3-Läsionen ermöglichte (AUC 0,92; Cut-off 8,8 %, Sensitivität 83 %, Spezifität 91 %).
Schlussfolgerungen
Die Quantifizierung des intraläsionalen Fetts mittels MRT-PDFF-Mapping erlaubt die Unterscheidung zwischen hochdifferenzierten (G1) und weniger differenzierten (G2/3) steatotischen HCCs.
Klinische Relevanz
Das PDFF-Mapping kann als Instrument zur Beurteilung des Tumorgrads bei steatotischen HCCs dazu beitragen, die Präzisionsmedizin zu optimieren. Die weitere Untersuchung des intratumoralen Fettgehalts als potenzieller prognostischer Indikator für das Ansprechen auf eine Therapie ist erstrebenswert
Diagnostische und prognostische Aussagekraft von perioperativem NT-proBNP in Serum und Urin bei Kindern mit angeborenen Herzfehlern
Full text linkNT-proBNP ist ein wichtiger Marker für Kinder mit angeborenen Herzfehlern. Gerade in diesem Kollektiv könnte sich ein Vorteil aus der Bestimmung des NT-proBNP aus dem Urin ergeben, da häufige Blutentnahmen bei dem geringem Blutvolumen der Kinder ein Risiko für erhöhten Transfusionsbedarf darstellen. Die vorliegende Arbeit untersucht den Zusammenhang von postoperativ gewonnenen NT-proBNP-Werten aus Serum und Urin. Zudem wird der Zusammenhang zwischen der Höhe des NT-proBNPs und der Dauer der invasiven und nicht-invasiven Beatmung geprüft. Ziel ist es, zu eruieren, ob NT-proBNP als prognostischer Biomarker für Beatmungsdauern nach pädiatrischer Herz-Operation genutzt werden kann und ein Marker für Extubationsversagen in diesem Kollektiv darstellt.
Für die Studie entnahmen wir bei 117 Kinder mit angeborenen Herzfehlern im perioperativen Verlauf Blut- und Urinproben. Sowohl die Blut- als auch die Urinproben wurden direkt an die Biobank Core Facility verschickt, wo sie in 1mL Portionen aliquotiert und bis zur Analyse bei -80°C eingefroren wurden. Die NT-proBNP Bestimmungen erfolgten mit Elecsys proBNP II assay (ECLIA, Roche Diagnostics, Canada), die Kreatinin-Bestimmung mit Reagenz CREJ2, Gerät cobas c702 (VIS-Photometrie, Roche Diagnostics Canada). Die statistische Auswertung erfolgte mit IBMs SPSS Version 29. Der Zusammenhang zwischen NT-proBNP und kontinuierlichen Variablen wie die Dauer der Beatmung wurden nach Log10-Transformation in eine Normalverteilung mittels Pearson-Korrelation untersucht. Um den Einfluss des zugrundeliegenden Herzfehlers zu untersuchen wurden die Kinder nach der Komplexität des Herzfehlers von zwei erfahrenen Kinderkardiologinnen in zwei Gruppen eingeteilt. T-Tests für unabhängige Stichproben wurden eingesetzt um diese Gruppen untereinander zu vergleichen und Unterschiede zwischen den NT-proBNP-Werten von Kindern mit und ohne Extubationsversagen zu untersuchen.
Postoperative Urinwerte zeigten eine gute Korrelation zu NT-proBNP aus dem Serum (r= 0,721, p
Postoperative NT-proBNP-Werte aus dem Urin zeigen eine gute Korrelation mit Serumwerten, insbesondere wenn sie Kreatinin-korrigiert sind. Zudem korrelieren postoperative Urinwerte gut mit den Beatmungsdauern von Kindern mit angeborenen Herzfehlern. Demzufolge ist NT-proBNP im Urin auch in der dynamischen postoperativen Periode ein valider Marker und ein potentieller Ersatz für Blutbestimmungen bei Kindern mit angeborenen Herzfehlern. Darüber hinaus kann perioperatives NT-proBNP ein Marker für Extubationsversagen bei Kindern in diesem Setting sein