Effect of Microglial Purinergic P2Y12 Receptor on Efficiency of Beta-Amyloid Immunotherapy and Aging

Microglia, 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

Role of GluA2-containing AMPARs in Oligodendrocyte Lineage Cells

Oligodendrocytes precursor cells (OPC), also called NG2 cells, proliferate or differentiate into myelin-producing oligodendrocytes throughout life. Myelination depends on neuronal activity. Although NG2 cells receive neuronal glutamatergic synaptic input throughout the CNS, factors mediating activity-dependent control of the oligodendrocyte lineage cell fate have not been resolved yet. Glutamatergic signalling in NG2 cells is mainly mediated by AMPARs. During the postnatal period, AMPARs are calcium impermeable due to the expression of the GluA2 subunit. Later in the adult period, NG2 cells downregulate the GluA2 subunit, therefore they express GluA2-lacking AMPARs, permeable to calcium. Thus, the decline of the proliferation rate of NG2 cells observed during the transition from the postnatal to the adult period is mirrored by an increase in the calcium-permeability of synaptic AMPA receptors. We hypothesized that the postnatally expressed GluA2 subunit enables the proliferation of NG2 cells by suppressing calcium entry during synaptic activity. Here, we assessed the impact of postnatal GluA2 subunit deletion on the oligodendrocyte lineage cell fate. In order to induce a conditional deletion of the GluA2 subunit in NG2 cells, we crossed the three following mouse lines. NG2CreER mouse line conditionally express Cre under the NG2 promotor. R26REYFP mouse line express the yellow fluorescent protein reporter after Cre expression. GluA2lox mouse line undergoes a deletion of Gria2 allele responsible for GluA2 expression. First, we followed the oligodendrocyte lineage cell fate with the BrdU and PCNA markers to examine NG2 cell proliferation, the cleaved caspase-3 marker to probe for cell death, and the CC1 marker to analyse differentiation of NG2 cells into oligodendrocytes. We found that GluA2 deletion in early postnatal NG2 cells increased BrdU uptake in NG2 cells without increasing cell density or cell death in the oligodendrocyte lineage cell population. Secondly, we investigated the role of GluA2 subunit on myelination establishment by measuring the internodes length during myelination onset and at a later timepoint during the postnatal phase. GluA2 deletion in NG2 cells shortened immature internodes during myelination onset. Thirdly, the role of the GluA2 subunit in NG2 cells was investigated in a motor learning task requiring newly formed oligodendrocytes. GluA2 deletion altered the motor learning performance in mice. Although it did not affect the myelination properties investigated or NG2 cells proliferation. Overall, the GluA2 subunit in postnatal NG2 cells regulates DNA synthesis in NG2 cells and myelination onset through the regulation of internode elongation. Our study highlights the prominence of glutamatergic synaptic input integration in postnatal NG2 cells to regulate oligodendrocyte lineage cell fate

Medicinal Chemistry and Pharmacology of Ectonucleotidases: Assay Development and Characterisation of Inhibitors

(noch nicht zugänglich / not yet accessible

Reprogramming Borohydride Reactivity by Integrating Titanium and Chromium in Cooperative Catalysis

(noch nicht zugänglich / not yet accessible

Cell-type-specific transcriptional programming of the neonatal immune system

(noch nicht zugänglich / not yet accessible

Grundlagen zur automatischen intrinsischen metabolischen Defibrillation von ventrikulären Herzrhythmusstörungen mittels säuresensitiver Ionenkanäle

Diese Studie untersucht die Möglichkeit, überexprimierte säuresensitive Kationenkanäle (ASICs) in Kardiomyozyten als Werkzeug zur selbständigen Beendigung hämodynamisch relevanter Herzrhythmusstörungen wie ventrikuläre Tachykardien zu nutzen. Die Ergebnisse legen die Grundlage für das innovative Konzept der automatisch intrinsisch metabolischen Defibrillation. Dieser alternative Methode zur Terminierung ventrikulärer Tachykardien würde keinen Einsatz implantierbarer Defibrillatoren erfordern

Immunhistochemische Untersuchungen zum Nachweis der Angiogenese während der Einheilung von Knochenersatzmaterialien

In der Zahnmedizin ist der Einsatz von Knochenersatzmaterialien alltäglich geworden. Bei den Einheilungsprozessen von Knochenersatzmaterialien sind Osteogenese und Angiogenese eng miteinander verbunden. Die Kenntnis der biologischen Vorgänge während der Angiogenese ist wichtig für die Prognose von Augmentationsverfahren und die Beurteilung von Misserfolgen. Ziel dieser Arbeit war es, Auftreten und Verteilung von Blut- und Lymphgefäßen während der Einheilung von Knochenersatzmaterialien an Biopsien zu untersuchen, die von insgesamt 60 Patienten nach zweizeitiger Augmentation des Sinusbodens zur späteren Insertion von Implantaten entnommen worden waren. Hierbei wurde in einer ersten Operation das Knochenersatzmaterial, welches entweder allogenen, xenogenen, phykogenen oder alloplastischen Ursprungs war, eingebracht. Nach einer Einheilzeit von drei bis sechs Monaten wurden in einem zweiten Eingriff die Biopsien entnommen. Jede Knochenersatzmaterialgruppe umfasste 15 Patienten. Zum Nachweis von Gefäßen wurden die Marker vWF, CD31 und CD34 an ausgewählten Schnitten immunhistochemisch nachgewiesen. Zusätzlich erfolgte ein immunhistochemischer Nachweis von Lymphgefäßen mit Hilfe eines Antikörpers gegen Podoplanin. Nach qualitativer Befundung der Präparate, vor allem hinsichtlich ablaufender Osteogenesevorgänge, erfolgte eine quantitative Untersuchung der immunhistochemischen Befunde in definierten Regions of Interest mit nachfolgender statistischer Auswertung. Für jede Knochenersatzmaterialgruppe wurde das Verhalten der Blutgefäße in der Peripherie augmentierter Bereiche sowie bei Nachweis granulärer Knochenersatzmaterial-Residuen peri- und intragranulär untersucht. Alle Präparate zeigten semiquantitativ eine mäßige bis starke Vaskularisierung in der Peripherie. Es war festzustellen, dass mit Zunahme der peripheren Vaskularisierung die peri- und intragranulären Gefäßeinsprossungen zunahmen. Darüber hinaus zeigte sich, dass die Osteogenese umso weiter fortgeschritten war, je stärker die periphere Vaskularisierung war. Die histologischen und immunhistochemischen Auswertungen der untersuchten Knochenersatzmaterialien zeigten insgesamt keine signifikanten Unterschiede zwischen den einzelnen untersuchten Materialien. Erstmals konnten Lymphgefäße während der Einheilung von Knochenersatzmaterialien nachgewiesen werden. So zeigte circa ein Viertel aller Präparate einen positiven Lymphgefäßbefund. Die Gefäße erwiesen sich mit einem Durchmesser von circa 50 µm als initiale Lymphgefäße. Ein Zusammenhang zwischen einem positiven Lymphgefäßnachweis und dem Auftreten von Infiltraten konnte nachgewiesen werden. Es konnte gezeigt werden, dass Beschaffenheit und Porengröße eines Knochenersatzmaterials großen Einfluss auf das Eindringverhalten von Gefäßen und dem damit verbundenen erfolgreichen Einwachsen von Knochen in das Material haben. Die Porengrößen der verwendeten Knochenersatzmaterialien liegen im Makroporenbereich und zeigten eine gute Neovaskularisation, die mit den Ergebnissen anderer Studien vergleichbar ist

Transcriptomic heterogeneity of microglia in relation to Alzheimer's disease-associated pathology and post-mortem delay

(noch nicht zugänglich / not yet accessible

The role of the food environment as a driver of diet quality in children and adolescents : A cross-sectional analysis of external and individual factors

The food environment, typically considered the place where individuals interface with food supply, is increasingly discussed for its role and opportunity to influence diet quality of individuals. Available studies suggest that the food environment plays a role for diet quality, but the pathway behind this remains unclear. It is also not well understood to what degree the role of the food environment is mitigated by individual factors, such as wealth, education or sex. Additionally, detailed analysis on the role of the food environment for specific age group (children and adolescents) is lacking. Lastly, a better understanding of how food environments differ from each other is needed to inform targeted, effective policies to improve diet quality. Consequently, the aim of this research was to investigate if, and to what degree, the food environment is associated with the diet quality of children and adolescents. More specifically, we analysed the relationship between food environment indicators and diet quality of young children in 20 LMICs (study I) and identified the variation of diet intake among individuals aged 6-18 years within Dortmund, Germany (study II). Additionally, individual-level factors that influence diet intake among adolescents (study III) and the association between food environment indicators and diet quality around schools in Accra, Ghana (study IV) were investigated. Results from study I show that diet intake and quality vary across geographical settings. This study (n = 247 subnational areas, 6-23 months) highlights that high variation of food environment indicators (e.g. food price and availability) exists across LMICs. It also shows a superordinate association between food environment indicators and diet quality at the subnational level. study II (n = 360, 6-18 years) captures variation at the city level, using data from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study and shows that, in comparison to the North of Dortmund, students in the South have lower BMI, lower intake of sugar-sweetened Beverages and higher intake of vegetables. Results from study III suggest that individual level factors create dependency of adolescents (n = 409, 12-15 years) on the food environment. We report that daily food budget is negatively associated with overall diet quality and positively with food group diversity. Food environment indicators are also associated with diet quality after controlling for individual factors (study IV). Research conducted in Accra documents that pricing of foods from vendors (n = 1,340) in and around schools (n = 12) are associated with diet intake of students (n = 409, 12-15 years) in the same location. This association persists even after controlling for individual factors, indicating that some drivers of dietary quality are outside the control of the individual. In conclusion, the food environment is an important factor in understanding the variation in diet quality for children and adolescents. This result was confirmed by data from observational studies carried out in subnational areas in 20 LMICs, Dortmund, Germany and Accra, Ghana. The consistent association of financial indicators (both prices and budget) with diet quality suggests that affordability should be a key consideration for policies aiming to ensure access to a healthy, nutritious diet within the food environment

Metal-Centered Cleavage of E≡E Triple Bonds (E = Si, Ge): A Leap in Metal-Tetrel Triple Bond Chemistry

(noch nicht zugänglich / not yet accessible