Biology subjects

Haage, V. C.

Publications and source records attributed to Haage, V. C..

5 recordsLinked to original sources

bioRxiv2025

INPP5D/SHIP1 is a dual regulator of endo-lysosome function and selective phagocytosis in human microglia

INPP5D, which encodes SHIP1, is genetically associated with Alzheimers disease (AD) risk and regulates microglial immune function. Here we identified SHIP1 as a regulator of endo-lysosomal homeostasis in human microglia. INPP5D haploinsufficiency impaired endosome maturation and lysosomal degradation, leading to lipid droplet accumulation, lysosomal stress, and NLRP3 inflammasome activation. SHIP1-deficient microglia shifted from an immune-responsive state toward a disease-associated state with elevated cargo-selective phagocytosis. Although amyloid-{beta} uptake was unaffected, SHIP1-deficient microglia accumulated intracellular amyloid-{beta} and exhibited exacerbated lipid droplet accumulation, consistent with defective lysosomal processing. Proteomic analysis of genetically diverse human microglia revealed that the protective INPP5D rs10933431 variant is associated with elevated phosphatase-domain containing SHIP1, and protein profiles consistent with enhanced endolysosomal trafficking. In mice xenografted with SHIP1-deficient human microglia, high amyloid-{beta} burden exacerbated lysosomal, lipid droplet and inflammasome phenotypes. Together, these findings identify disrupted endo-lysosomal trafficking and degradative capacity as mechanisms linking INPP5D dysfunction to disease-associated microglial states in AD.

neuroscience↗

bioRxiv2025

A factor-based analysis of individual human microglia uncovers regulators of an Alzheimer-related transcriptional signature

Human microglial heterogeneity is only beginning to be appreciated at the molecular level. Here, we present a large, single-cell atlas of expression signatures from 441,088 live microglia broadly sampled across a diverse set of brain regions and neurodegenerative and neuroinflammatory diseases obtained from 161 donors sampled at autopsy or during a neurosurgical procedure. Using single-cell hierarchical Poisson factorization (scHPF), we derived a 23-factor model for continuous gene expression signatures across microglia which capture specific biological processes (e.g., metabolism, phagocytosis, antigen presentation, inflammatory signaling, disease-associated states). Using external datasets, we evaluated the aspects of microglial phenotypes that are encapsulated in various in vitro and in vivo microglia models and identified and replicated the role of two factors in human postmortem tissue of Alzheimers disease (AD). Further, we derived a complex network of transcriptional regulators for all factors, including regulators of an AD-related factor enriched for the mouse disease-associated microglia 2 (DAM2) signature: ARID5B, CEBPA, MITF, and PPARG. We replicated the role of these four regulators in the AD-related factor and then designed a multiplexed MERFISH panel to assess our microglial factors using spatial transcriptomics. We find that, unlike cells with high expression of the interferon-response factor, cells with high expression of the AD DAM2-like factor are widely distributed in neocortical tissue. We thus propose a novel analytic framework that provides a taxonomic approach for microglia that is more biologically interpretable and use it to uncover new therapeutic targets for AD.

neuroscience↗

bioRxiv2024

HDAC Inhibitors recapitulate Human Disease-Associated Microglia Signatures in vitro

Disease-associated microglia (DAM), initially described in mouse models of neurodegenerative diseases, have been classified into two related states; starting from a TREM2-independent DAM1 state to a TREM2 dependent state termed DAM2, with each state being characterized by the expression of specific marker genes1. Recently, single-cell (sc)RNA-Seq studies have reported the existence of DAMs in humans2-6; however, whether DAMs play beneficial or detrimental roles in the context of neurodegeneration is still under debate7,8. Here, we present a pharmacological approach to mimic human DAM in vitro by exposing different human microglia models to selected histone deacetylase (HDAC) inhibitors. We also provide an initial functional characterization of our model system, showing a specific increase of amyloid beta phagocytosis along with a reduction of MCP-1 secretion. Additionally, we report an increase in MITF expression, a transcription factor previously described to drive expression towards the DAM phenotype. We further identify CADM1, LIPA and SCIN as DAM- marker genes shared across various proposed DAM signatures and in our model systems. Overall, our strategy for targeted microglial polarization bears great potential to further explore human DAM function and biology.

neuroscience↗

bioRxiv2024

A pharmacological toolkit for human microglia identifies Topoisomerase I inhibitors as immunomodulators for Alzheimer's disease

AbstractWhile efforts to identify microglial subtypes have recently accelerated, the relation of transcriptomically defined states to function has been largely limited to in silico annotations. Here, we characterize a set of pharmacological compounds that have been proposed to polarize human microglia towards two distinct states - one enriched for AD and MS genes and another characterized by increased expression of antigen presentation genes. Using different model systems including HMC3 cells, iPSC-derived microglia and cerebral organoids, we characterize the effect of these compounds in mimicking human microglial subtypes in vitro. We show that the Topoisomerase I inhibitor Camptothecin induces a CD74high/MHChigh microglial subtype which is specialized in amyloid beta phagocytosis. Camptothecin suppressed amyloid toxicity and restored microglia back to their homeostatic state in a zebrafish amyloid model. Our work provides avenues to recapitulate human microglial subtypes in vitro, enabling functional characterization and providing a foundation for modulating human microglia in vivo.

neuroscience↗

bioRxiv2021

The Need for Sustainable Leadership in Academia - a German Case Study

Academic leaders are selected based on their publication record, citation index and acquisition of third party funding. However, heading a successful research team, also requires leadership skills. Despite the clear need, leadership development has been systematically neglected in the present academic system. At the same time, growing evidence suggests that leadership styles of academic supervisors can dramatically affect the mental health of academic employees as well as drive highly skilled researchers out of academia. Here, we assessed the current state of academic leadership in the German academic system by surveying 368 participants currently employed in academia in Germany. We report that 64% of current academic leaders did not feel prepared for their current position while 86% of participants expressed their interest in leadership development programs offered by their research institutions. Our results highlight the demand for leadership development programs in German academic institutions to ensure a more efficient academic system.

scientific communication and education↗