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Monozytäre Zellen in der Pathogenese des ischämischen Schlaganfalls

Antragstellerin Professorin Dr. Karen Gertz, seit 7/2018
Fachliche Zuordnung Molekulare und zelluläre Neurologie und Neuropathologie
Klinische Neurologie; Neurochirurgie und Neuroradiologie
Förderung Förderung von 2018 bis 2022
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 397020466
 
Erstellungsjahr 2023

Zusammenfassung der Projektergebnisse

Here, we investigated the different properties of resident microglia compared to invading myeloid cells in the CNS. In particular, we characterized the influence of macrophages migrating from the blood into the stroke lesion and investigated their impact on stroke outcome. Using bone marrow (BM) chimerism and dual-reporter transgenic fate mapping, we set out to delimit the responses of either cell types to mild brain ischemia in a mouse model of 30 min transient middle cerebral artery occlusion (MCAo). CSF-1 receptor-eGFP transgenic mice were used as recipient mice in which resident microglial cells are detectable by a green fluorescent signal. These animals were transplanted with red fluorescent, DsRed+ BM. Immunohistochemical analyses showed that the contralateral hemisphere contained no DsRed-labeled cells, but only quiescent microglial cells. In contrast, we found numerous DsRed+ cells as well as eGFP+ cells in the area of the stroke lesion. These cells typically showed an activated, amoeboid morphology. A discriminatory analysis of gene expression identified transcripts predominantly expressed in blood-derived macrophages or in microglia. The differentially regulated genes were further collated with oligodendrocyte, astrocyte, and neuron transcriptomes, resulting in a dataset of microglia- and monocyte-specific genes in the ischemic brain. Functional categories significantly enriched in blood-derived macrophages included migration, proliferation, and calcium signaling, indicative of strong activation. Wholecell patch-clamp analysis confirmed this highly activated state by demonstrating delayed outward K+ currents selectively in invading cells. Although both cell types displayed a mixture of known phenotypes pointing to the significance of ‘intermediate states’ in vivo, blood-derived macrophages were more skewed toward an M2 neuroprotective phenotype. Finally, we found that decreased engraftment of blood-borne cells in the ischemic brain of chimeras reconstituted with BM from P-selectin ligand knockout mice resulted in larger stroke lesions and worse post-stroke sensorimotor performance. We also expanded our translational expertise and applied methods to study human microglia. Thus, given the limited availability of human primary cells, we were able to establish a protocol to study human iPSC-derived microglia. Based on the hypothesis that neuroinflammatory processes also play a role in the development of affective disorders, we investigated the effect of lithium on tryptophan catabolism and identified a specific signaling pathway through which lithium inhibits inflammatory activation of the kynurenine pathway in human microglia. In a collaboration project, we characterized the effects of the muscarinic acetylcholine receptor 3 (M3R) on myeloid cells and investigated its influence on stroke outcome. We found that upregulation of m3R in microglia and monocytes had a beneficial effect on stroke outcome; however, there appears to be a gender effect, as the effect was seen only in male animals.

Projektbezogene Publikationen (Auswahl)

 
 

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