TY - THES A1 - Königer, Tobias T1 - The Vessel Wall and Beyond: Characterization of Myeloid Progenitors in the Adult Mouse Brain T1 - Die Gefäßwand und darüber hinaus: Charakterisierung myeloider Vorläufer im adulten Mäusehirn N2 - After almost two decades of extensive research, some controversy has remained regarding the self-renewal of resident macrophages of the central nervous system (CNS). Concurrently, the vessel wall has emerged as a potentially ubiquitous niche for stem and progenitor cells, including committed macrophage precursors. It is conceivable that their occurrence in the CNS might explain the brain-resident hematopoietic potential, which has repeatedly been observed but not yet characterized in detail. In this work, the presence of hematopoietic progenitors inside and outside the vessel wall was studied in the adult mouse brain, as well as their possible contribution to the resident macrophage pool. An immunohistological analysis did not corroborate CD45+ SCA-1+ macrophage progenitors, which have been characterized in peripheral arteries, in the circle of Willis. Accordingly, the ex vivo culture of CNS vessels did not provide evidence for de novo formation of macrophages, but for the extensive proliferative capacity of mature cells. However, when analyzing whole brain suspensions in colony-forming unit (CFU) assays, rare Iba1- Cx3cr1- (immature) clonogenic cells were detected, which were enriched at the cerebral surface/meninges and differentiated into macrophages in culture. Intravenous antibody injection and cell sorting confirmed their residence behind the blood-brain barrier. Intriguingly, brain-derived CFUs produced a unique pattern of colony types compared to cells from bone marrow (BM) or blood. Still they displayed the same immunophenotype as BM-resident myeloid progenitors (CD45lo, LIN-, SCA-1-, IL7Rα-, c-KIT+) and could be further stratified into a progenitor hierarchy giving rise to all erythro-myeloid cell types in vitro. This similarity was substantiated by labeling of their progeny in Flt3Cre x Rosa26mT/mG mice, which indicated a descendance from hematopoietic stem cells. While forced repopulation of brain macrophages using the CSF-1R inhibitor PLX5622 did not point to a role of progenitors in in vivo microglia/macrophage maintenance, recent advances in hematology imply that they might be involved in CNS immunosurveillance. In conclusion, though there was no evidence for adventitial macrophage precursors in the CNS, this study confirms the presence of myeloid progenitors in the adult brain and provides the anatomical and phenotypical details necessary to elucidate their relevance in neuroinflammation. N2 - Nach fast zwei Jahrzehnten intensiver Forschung wird der Selbsterhalt residenter Makrophagen im zentralen Nervensystem (ZNS) immer noch kontrovers diskutiert. Gleichzeitig hat sich die Gefäßwand als eine potentiell ubiquitäre Nische für Stamm- und Vorläuferzellen herausgestellt, einschließlich determinierter Vorläufer für Makrophagen. Dass diese auch im ZNS vorhanden sind, könnte die wiederholten Berichte über hämatopoetisches Potenzial im Gehirn erklären, welches bisher nicht genau charakterisiert wurde. In der vorliegenden Arbeit wurde daher die Existenz hämatopoetischer Vorläuferzellen sowohl innerhalb als auch außerhalb der Gefäßwände des Gehirns erwachsener Mäuse untersucht. Weiterhin wurde deren Beitrag zu residenten Makrophagen-Populationen überprüft. Eine immunhistologische Analyse konnte CD45+ SCA-1+ Makrophagen-Vorläufer, wie sie in peripheren Arterien beschrieben wurden, im Circulus arteriosus Willisii nicht bestätigen. Entsprechend lieferte die Kultur von ZNS-Gefäßen keine Hinweise auf eine Neubildung von Makrophagen, zeigte aber ein hohes Teilungsvermögen reifer Zellen auf. Allerdings wurden in colony-forming unit assays mit Hirnzellsuspensionen seltene Iba1- Cx3cr1- (unreife) klonogene Zellen detektiert, die im Bereich der Hirnhaut angereichert waren und in Kultur zu Makrophagen differenzierten. Eine intravenöse Antikörperinjektion und Zellsortierung belegten, dass sie sich hinter der Blut-Hirn-Schranke befanden. Klonogene Zellen des Hirns erzeugten ein eigentümliches Muster an Kolonietypen, welches sich von dem des Knochenmarks und des Blutes unterschied. Trotzdem glichen sie in ihrem Immunphänotyp myeloiden Vorläuferzellen des Knochenmarks (CD45lo, LIN-, SCA-1-, IL7Rα-, c-KIT+) und konnten weiter in eine Hierarchie von Vorläufern aufgespalten werden, die in vitro alle erythro-myeloiden Zelltypen hervorbrachte. Diese Ähnlichkeit wurde dadurch unterstrichen, dass ihre Nachkommen in Flt3Cre x Rosa26mT/mG Mäusen markiert wurden, was eine Abstammung von hämatopoetischen Stammzellen anzeigte. Während die induzierte Repopulation von Hirn-Makrophagen mit Hilfe des CSF-1R Inhibitors PLX5622 keine Vorläuferbeteiligung beim Erhalt von Mikroglia/Makrophagen in vivo vermuten ließ, deuten neue Erkenntnisse im Bereich der Hämatologie darauf hin, dass die beschriebenen Vorläufer in die immunologische Überwachung des ZNS involviert sein könnten. Wenngleich keine Anhaltspunkte für adventitielle Makrophagen-Vorläufer im ZNS gefunden wurden, bestätigt diese Arbeit die Existenz myeloider Vorläufer im adulten Hirn und liefert notwendige anatomische und phänotypische Informationen, um deren Bedeutung im Rahmen entzündlicher Prozesse des ZNS aufzuklären. KW - Gehirn KW - Vorläufer KW - Gefäßwand KW - Hirnhaut KW - Brain KW - Myeloid KW - Progenitor KW - Vessel wall KW - Meninges KW - Microglia KW - Depletion Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186465 ER - TY - JOUR A1 - Berve, Kristina A1 - West, Brian L. A1 - Martini, Rudolf A1 - Groh, Janos T1 - Sex- and region-biased depletion of microglia/macrophages attenuates CLN1 disease in mice JF - Journal of Neuroinflammation N2 - Background The neuronal ceroid lipofuscinoses (CLN diseases) are fatal lysosomal storage diseases causing neurodegeneration in the CNS. We have previously shown that neuroinflammation comprising innate and adaptive immune reactions drives axonal damage and neuron loss in the CNS of palmitoyl protein thioesterase 1-deficient (Ppt1\(^{-/-}\)) mice, a model of the infantile form of the diseases (CLN1). Therefore, we here explore whether pharmacological targeting of innate immune cells modifies disease outcome in CLN1 mice. Methods We applied treatment with PLX3397 (150 ppm in the chow), a potent inhibitor of the colony stimulating factor-1 receptor (CSF-1R) to target innate immune cells in CLN1 mice. Experimental long-term treatment was non-invasively monitored by longitudinal optical coherence tomography and rotarod analysis, as well as analysis of visual acuity, myoclonic jerks, and survival. Treatment effects regarding neuroinflammation, neural damage, and neurodegeneration were subsequently analyzed by histology and immunohistochemistry. Results We show that PLX3397 treatment attenuates neuroinflammation in CLN1 mice by depleting pro-inflammatory microglia/macrophages. This leads to a reduction of T lymphocyte recruitment, an amelioration of axon damage and neuron loss in the retinotectal system, as well as reduced thinning of the inner retina and total brain atrophy. Accordingly, long-term treatment with the inhibitor also ameliorates clinical outcomes in CLN1 mice, such as impaired motor coordination, visual acuity, and myoclonic jerks. However, we detected a sex- and region-biased efficacy of CSF-1R inhibition, with male microglia/macrophages showing higher responsiveness toward depletion, especially in the gray matter of the CNS. This results in a better treatment outcome in male Ppt1\(^{-/-}\) mice regarding some histopathological and clinical readouts and reflects heterogeneity of innate immune reactions in the diseased CNS. Conclusions Our results demonstrate a detrimental impact of innate immune reactions in the CNS of CLN1 mice. These findings provide insights into CLN pathogenesis and may guide in the design of immunomodulatory treatment strategies. KW - Neuronal ceroid lipofuscinosis KW - Microglia KW - Macrophages KW - T lymphocytes KW - Neurodegeneration KW - Axon degeneration Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230234 VL - 17 ER - TY - JOUR A1 - Gunesch, Sandra A1 - Hoffmann, Matthias A1 - Kiermeier, Carolina A1 - Fischer, Wolfgang A1 - Pinto, Antonio F. M. A1 - Maurice, Tangui A1 - Maher, Pamela A1 - Decker, Michael T1 - 7-O-Esters of taxifolin with pronounced and overadditive effects in neuroprotection, anti-neuroinflammation, and amelioration of short-term memory impairment in vivo JF - Redox Biology N2 - Alzheimer's disease (AD) is a multifactorial disease and the most common form of dementia. There are no treatments to cure, prevent or slow down the progression of the disease. Natural products hold considerable interest for the development of preventive neuroprotectants to treat neurodegenerative disorders like AD, due to their low toxicity and general beneficial effects on human health with their anti-inflammatory and antioxidant features. In this work we describe regioselective synthesis of 7-O-ester hybrids of the flavonoid taxifolin with the phenolic acids cinnamic and ferulic acid, namely 7-O-cinnamoyltaxifolin and 7-O-feruloyltaxifolin. The compounds show pronounced overadditive neuroprotective effects against oxytosis, ferroptosis and ATP depletion in the murine hippocampal neuron HT22 cell model. Furthermore, 7-O-cinnamoyltaxifolin and 7-O-feruloyltaxifolin reduced LPS-induced neuroinflammation in BV-2 microglia cells as assessed by effects on the levels of NO, IL6 and TNFα. In all in vitro assays the 7-O-esters of taxifolin and ferulic or cinnamic acid showed strong overadditive activity, significantly exceeding the effects of the individual components and the equimolar mixtures thereof, which were almost inactive in all of the assays at the tested concentrations. In vivo studies confirmed this overadditive effect. Treatment of an AD mouse model based on the injection of oligomerized Aβ\(_{25-35}\) peptide into the brain to cause neurotoxicity and subsequently memory deficits with 7-O-cinnamoyltaxifolin or 7-O-feruloyltaxifolin resulted in improved performance in an assay for short-term memory as compared to vehicle and mice treated with the respective equimolar mixtures. These results highlight the benefits of natural product hybrids as a novel compound class with potential use for drug discovery in neurodegenerative diseases due to their pharmacological profile that is distinct from the individual natural components. KW - Alzheimer's disease KW - Natural product hybrids KW - Flavonoids KW - Phenolic acids KW - Microglia KW - In vivo studies Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202718 VL - 29 ER -