Biology subjects

Dichgans, M.

Publications and source records attributed to Dichgans, M..

14 recordsLinked to original sources

bioRxiv2026

Reversible hypervascularization drives cognitive decline and blood-brain barrier damage during aging

Cerebrovascular dysfunction emerges early in neurodegeneration, yet how vascular structure, blood-brain barrier (BBB) failure, and cognition are linked remains undefined. Using VesselPro, a whole-brain pipeline integrating perfusion-resolved 3D imaging with spatial proteomics, we mapped vascular aging across the mouse lifespan. We identify two discrete trajectories: a hypovascular state and a previously unrecognized hyper-vascular, BBB-compromised state, defined relative to a young-adult vascular baseline. The hyper-vascular trajectory, concentrated in the cortex and hippocampus, was associated with marked spatial memory impairment and pervasive BBB leakage. Spatial proteomics revealed a coordinated program involving angiogenic activation, endothelial stress, cytoskeletal remodeling, and inflammatory signaling. Cross-species comparison with human proteomic biomarkers from the UK Biobank showed strong alignment between the mouse hypervascular signature and vascular dementia risk, but minimal concordance with Alzheimers disease, defining a vascular-specific dementia endotype. Transient Tie2 activation with AKB-9778 attenuated this trajectory, improving vessel organization, BBB integrity, and memory performance. Our findings show that endothelial instability is a key mechanistic driver of this heterogeneous vascular aging state. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/720441v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@39494aorg.highwire.dtl.DTLVardef@faa4acorg.highwire.dtl.DTLVardef@1511dd5org.highwire.dtl.DTLVardef@7db29b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIVesselPro: we developed a pipeline for capturing perfused blood vessels in the brain: unexpected bifurcation in vascular aging: traditional hypovascular state and a novel, hypervascular, BBB-compromised state. C_LIO_LIHypervascular pathology: Linked the hypervascular profile in the cortex and hippocampus to spatial memory impairment, pervasive BBB leakage, and angiogenic inflammatory signaling. C_LIO_LIClinical endotype: Cross-species analysis via the UK Biobank confirms this hypervascular signature aligns with vascular dementia risk rather than Alzheimers disease. C_LIO_LIPharmacological stabilization: Demonstrated that Tie2 signaling activation (AKB-9778) improves the vessel organization, BBB integrity, and memory performance. C_LI

neuroscience↗

bioRxiv2025

Endothelial Arf6 sustains capillary electrical signaling and cerebral blood flow through PIP2 regeneration and activation of Kir2.1 channels.

Brain capillaries sense neural activity and direct blood flow to active regions--a process termed neurovascular coupling that underlies activity-dependent increases in local perfusion (functional hyperemia). A key contributor to functional hyperemic responses is the capillary endothelial cell (cEC) inward rectifier K+ (Kir2.1) channel, which is activated by neuronal activity-derived extracellular K+ and initiates vasodilatory electrical signals that propagate through the vascular network. Kir2.1 channel function requires continual production of its lipid cofactor, phosphatidylinositol-4,5-bisphosphate (PIP2), and is compromised in mouse models of cerebral small vessel (cSVD). Although decreased PIP2 availability is a common feature of cSVD, mechanisms underlying PIP2 synthesis remain poorly understood. We hypothesized that Arf6, a small GTPase expressed in cECs that stimulates PIP2 production, is critical for this process. Using patch-clamp electrophysiology, we demonstrate that inhibiting Arf6 activity progressively decreased cEC Kir2.1 channel activity. This deficit corresponded to loss of capillary-to-arteriole electrical signaling in isolated vessels and diminished functional hyperemia in vivo. Exogenously provided PIP2 restored Kir2.1 currents and functional hyperemia after Arf6 inhibition or genetic knockdown. Collectively, our data indicate that cEC Arf6 sustains Kir2.1 activity by maintaining PIP2 levels and demonstrate that diminished PIP2 synthesis is sufficient to impair functional hyperemia. Furthermore, we identify Arf6 as a mechanistic link between PIP2 production and endothelial electrical signaling, highlighting Arf6 as a potential therapeutic target for restoring functional hyperemia. Significance StatementActive brain regions send electrical signals through capillaries to dilate upstream arterioles and increase blood flow. The resulting activity-dependent increase in local blood flow (functional hyperemia) is mediated through inward-rectifier potassium (Kir2.1) channels. These channels-- and hence functional hyperemia--require continuous regeneration of the lipid cofactor PIP2 (phosphatidylinositol-4,5-bisphosphate). If PIP2 is deficient, electrical signaling fails--a defect characteristic of models of cerebral small vessel disease and Alzheimers disease. We identify the small GTPase Arf6 as a key to maintaining PIP2 and thus preserving capillary Kir2.1 activity and functional hyperemia. Our findings reveal an important pathway for PIP2 homeostasis and position Arf6 as a cornerstone upholding functional hyperemic responses, highlighting Arf6 as a target for restoring cerebral blood flow in disease.

neuroscience↗

bioRxiv2024

Immunothrombolytic monocyte-neutrophil axes dominate the single-cell landscape of human thrombosis

AbstractThrombotic diseases remain the major cause of death and disability worldwide with insufficient preventive and therapeutic strategies available. In the last decades a prominent inflammatory component has been identified as a key driver in the initiation and propagation of thrombosis - named thromboinflammation. However, a comprehensive investigation of the human immune system in thromboinflammation, beyond histological quantification, is lacking, which is essential for the development of novel therapeutic approaches. We therefore mapped the trajectories, functional states, and intercommunication of immune cells in stroke thrombi, retrieved by thrombectomy, at single-cell resolution. We reveal distinct leukocyte subpopulations with prothrombotic and, surprisingly, prominent fibrinolytic properties characterized by aberrant activation of intracellular host defense as well as hypoxia induced pathways. A prominent thrombolytic PLAUhigh, PLAURhigh, THBDhigh thrombus neutrophil subset, also expressing high levels of pro-recanalizing VEGFA and VEGFB, dominated the thrombus neutrophil environment. On the other hand CD16high NR4A1high non-classical monocytes with strong CXCL8, CXCL2, CXCL1 and CXCL16 mediated neutrophil- attracting and PLAU, PLAUR, THBD and TFPI mediated thrombolytic properties defined the thrombus monocyte environment. These thrombus monocyte subsets were characterized by high expression of TIMP1 and TREM1. These novel innate immune- cell subsets provide insights into the thrombogenic and pro-resolving properties of innate immune-cells. To provide mechanistic insight into these multi-omic findings, we utilized reverse translation approaches. In vitro as well as murine in vivo thrombosis models underlined the causal relevance of these immune-cell axes for thrombolysis: NR4A1high thrombus monocytes acquired a neutrophil-chemoattractive transcriptomic phenotype, neutrophils continuously infiltrated established murine thrombi in vivo and acquired a HIF1-mediated thrombolytic phenotype in vitro. A depletion of NR4A1high thrombus monocytes reduced thrombus neutrophil influx and exacerbated thrombosis in vivo. Together, this unravels cross-communicating monocyte and neutrophil subsets with thrombus-resolving properties and provide a publicly accessible immune-landscape of thrombosis. This provides a valuable resource for future research on thrombo- inflammation and might pave the way for novel immune-modulatory approaches for prevention or resolution of thrombosis.

immunology↗

bioRxiv2023

Innate immune memory after brain injury drives inflammatory cardiac dysfunction

The enormous medical burden of stroke is not only due to the brain injury itself and the acute systemic effects, but is largely determined by chronic comorbidities that develop secondarily after stroke. We hypothesized that the high rate of comorbidity developing after a stroke might have a shared immunological cause, however, the chronic effects of brain injury on systemic immunity have so far been barely investigated. Here, we identified myeloid innate immune memory as a cause of remote organ dysfunction after stroke. Using single-cell sequencing, we identified persistent pro-inflammatory transcriptomic changes in resident monocytes/macrophages in multiple organs one month after experimental ischemic brain injury, which was particularly abundant in the heart and associated with the development of cardiac fibrosis and diastolic dysfunction. A similar phenotype was seen in myocardial autopsy samples from stroke versus control patients. We observed chronic functional changes in myeloid hematopoiesis driven by post-stroke IL-1{beta}-mediated epigenetic changes. These alterations could be transplanted to naive recipient mice and were sufficient to induce cardiac dysfunction. By effectively blocking the trafficking of pro-inflammatory monocytes from the bone marrow to the heart using a dual CCR2/5 inhibitor, we successfully prevented post-stroke cardiac dysfunction. This approach holds promising potential as a novel immune-targeted secondary prevention therapy. We anticipate that the epigenetic immune reprogramming mechanisms detailed here for the brain-heart axis could be generalized to provide a novel framework for explaining the development of various comorbidities after acute tissue injury in remote organs.

immunology↗

bioRxiv2023

Shared inflammatory glial cell signature after brain injury, revealed by spatial, temporal and cell-type-specific profiling of the murine cerebral cortex

Traumatic brain injury leads to a highly orchestrated immune- and glial cell response partially responsible for long-lasting disability and the development of secondary neurodegenerative diseases. A holistic understanding of the mechanisms controlling the responses of specific cell types and their crosstalk is required to develop an efficient strategy for better regeneration. Here, we combined spatial and single-cell transcriptomics to chart the transcriptomic signature of the injured murine cerebral cortex, and identified specific states of astrocytes, microglia, and oligodendrocyte precursor cells contributing to this signature. Interestingly, these cellular populations share a large fraction of injury-regulated genes, including inflammatory programs downstream of the innate immune-associated pathways Cxcr3 and Tlr1/2. Systemic manipulation of these pathways decreased the reactivity state of glial cells associated with poor regeneration. The functional relevance of the newly discovered shared signature of glial cells highlights the importance of our resource enabling comprehensive analysis of early events after brain injury.

neuroscience↗

bioRxiv2021

Multi-omics and 3D-imaging reveal bone heterogeneity and unique calvaria cells in neuroinflammation

The meninges of the brain are an important component of neuroinflammatory response. Diverse immune cells move from the calvaria marrow into the dura mater via recently discovered skull-meninges connections (SMCs). However, how the calvaria bone marrow is different from the other bones and whether and how it contributes to human diseases remain unknown. Using multi-omics approaches and whole mouse transparency we reveal that bone marrow cells are highly heterogeneous across the mouse body. The calvaria harbors the most distinct molecular signature with hundreds of differentially expressed genes and proteins. Acute brain injury induces skull-specific alterations including increased calvaria cell numbers. Moreover, TSPO-positron-emission-tomography imaging of stroke, multiple sclerosis and neurodegenerative disease patients demonstrate disease-associated uptake patterns in the human skull, mirroring the underlying brain inflammation. Our study indicates that the calvaria is more than a physical barrier, and its immune cells may present new ways to control brain pathologies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/473988v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@978194org.highwire.dtl.DTLVardef@bc45e8org.highwire.dtl.DTLVardef@91afdborg.highwire.dtl.DTLVardef@b06bc6_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIBone marrow across the mouse body display heterogeneity in their molecular profile C_LIO_LICalvaria cells have a distinct profile that is relevant to brain pathologies C_LIO_LIBrain native proteins are identified in calvaria in pathological states C_LIO_LITSPO-PET imaging of the human skull can be a proxy of neuroinflammation in the brain C_LI Supplementary Videos can be seen at: http://discotechnologies.org/Calvaria/

cell biology↗

bioRxiv2021

CCL2/CCR2 inhibition in atherosclerosis: a meta-analysis of preclinical studies

RationaleThe CC-chemokine ligand-2 (CCL2)/ CC-chemokine receptor-2 (CCR2) axis governs monocyte recruitment to atherosclerotic lesions. Coherent evidence from experimental studies employing genetic deletion of CCL2 or CCR2 and human epidemiological studies support a causal involvement of the CCL2/CCR2 axis in atherosclerosis. Still, preclinical studies testing pharmacological inhibition of CCL2 or CCR2 in atheroprone mice apply widely different approaches and report inconsistent results, thus halting clinical translation. ObjectiveTo systematically review and meta-analyze preclinical studies pharmacologically targeting the CCL2/CCR2 axis in atherosclerosis in an effort to inform the design of future trials. Methods and ResultsWe identified 14 studies testing CCL2/CCR2 inhibition using 11 different pharmacological agents in mouse models of atherosclerosis. In meta-analyses, blockade of CCL2 or CCR2 attenuated atherosclerotic lesion size in the aortic root or arch (g=-0.75 [-1.17 to -0.32], p=6x10-4; N=171/171 mice in experimental/control group), the carotid (g=-2.39 [-4.23 to -0.55], p=0.01; N=24/25) and the femoral artery (g=-2.38 [-3.50 to -1.26], p=3x10-5; N=10/10). Furthermore, CCL2/CCR2 inhibition reduced intralesional macrophage accumulation and increased smooth muscle cell content and collagen deposition, consistent with a plaque-stabilizing effect. While there was heterogeneity across studies, the effects of CCL2/CCR2 inhibition on lesion size correlated with reductions in plaque macrophage accumulation, in accord with a prominent role of CCL2/CCR2 signaling in monocyte recruitment. Subgroup analyses revealed similar efficacy of both CCL2- and CCR2-inhibiting approaches across different atherosclerosis models in reducing lesion size and intralesional macrophage accumulation, but stronger atheroprotective effects in carotid and femoral arteries, as compared to the aorta. ConclusionsPharmacological targeting of CCL2 or CCR2 lowers atherosclerotic lesion burden and confers plaque stability in mice across different vascular territories, drug candidates, and models of atherosclerosis. Our findings in conjunction with recent human data highlight the translational potential of targeting the CCL2/CCR2 axis in atherosclerosis and can inform future clinical trials. Subject codesatherosclerosis, inflammation, vascular biology, translational studies

immunology↗

bioRxiv2020

Microbiota-derived short chain fatty acids promote Aβ plaque deposition

Previous studies have identified a crucial role of the gut microbiome in modifying Alzheimers disease (AD) progression. However, the mechanisms of microbiome-brain interaction in AD, including the microbial mediators and their cellular targets in the brain, were so far unknown. Here, we identify microbiota-derived short chain fatty acids (SCFA) as key metabolites along the gut-brain axis in AD. Germ-free (GF) AD mice exhibit a substantially reduced A{beta} plaque load and markedly reduced SCFA plasma concentrations; conversely, SCFA supplementation to GF AD mice was sufficient to increase the A{beta} plaque load to levels of conventionally colonized animals. While A{beta} generation was only mildly affected, we observed strong microglial activation and upregulation of ApoE upon the SCFA supplementation. Taken together, our results demonstrate that microbiota-derived SCFA are the key mediators along the gut-brain axis resulting in increased microglial activation, ApoE upregulation and A{beta} deposition.

neuroscience↗

bioRxiv2020

Detection of deleterious on-target effects after HDR-mediated CRISPR editing

CRISPR genome editing is a promising tool for translational research but can cause undesired editing outcomes, both on-target at the edited locus and off-target at other genomic loci. We investigated the occurrence of deleterious on-target effects in human stem cells after insertion of disease-related mutations by homology-directed repair (HDR). We identified large, mono-allelic genomic deletions and loss-of-heterozygosity that escaped standard quality controls in up to 40% of edited clones. To reliably detect such events, we developed simple, low-cost and universally applicable quantitative genotyping PCR (qgPCR) as well as sequencing-based tools and suggest their usage as additional quality controls after editing. This will help to ensure the integrity of edited loci and increase the reliability of CRISPR editing.

genomics↗

bioRxiv2019

Genomic risk score offers predictive performance comparable to clinical risk factors for ischaemic stroke

Recent genome-wide association studies in stroke have enabled the generation of genomic risk scores (GRS) but the predictive power of these GRS has been modest in comparison to established stroke risk factors. Here, using a meta-scoring approach, we developed a metaGRS for ischaemic stroke (IS) and analysed this score in the UK Biobank (n=395,393; 3075 IS events by age 75). The metaGRS hazard ratio for IS (1.26, 95% CI 1.22-1.31 per standard deviation increase of the score) doubled that of previous GRS, enabling the identification of a subset of individuals at monogenic levels of risk: individuals in the top 0.25% of metaGRS had a three-fold increased risk of IS. The metaGRS was similarly or more predictive when compared to established risk factors, such as family history, blood pressure, body mass index and smoking status. For participants within accepted guideline levels for established stroke risk factors, we found substantial variation in incident stroke rates across genomic risk backgrounds. We further estimated combinations of reductions needed in modifiable risk factors for individuals with different levels of genomic risk and suggest that, for individuals with high metaGRS, achieving currently recommended risk factor levels may be insufficient to mitigate risk.

genomics↗

bioRxiv2019

Automated analysis of whole brain vasculature using machine learning

Tissue clearing methods enable imaging of intact biological specimens without sectioning. However, reliable and scalable analysis of such large imaging data in 3D remains a challenge. Towards this goal, we developed a deep learning-based framework to quantify and analyze the brain vasculature, named Vessel Segmentation & Analysis Pipeline (VesSAP). Our pipeline uses a fully convolutional network with a transfer learning approach for segmentation. We systematically analyzed vascular features of the whole brains including their length, bifurcation points and radius at the micrometer scale by registering them to the Allen mouse brain atlas. We reported the first evidence of secondary intracranial collateral vascularization in CD1-Elite mice and found reduced vascularization in the brainstem as compared to the cerebrum. VesSAP thus enables unbiased and scalable quantifications for the angioarchitecture of the cleared intact mouse brain and yields new biological insights related to the vascular brain function.\n\nGRAPHICAL ABSTRACT\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC=\"FIGDIR/small/613257_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (51K):\norg.highwire.dtl.DTLVardef@8c79eborg.highwire.dtl.DTLVardef@984d3aorg.highwire.dtl.DTLVardef@f62d9borg.highwire.dtl.DTLVardef@2c20bc_HPS_FORMAT_FIGEXP M_FIG Supporting material of VesSAP is available at http://DISCOtechnologies.org/VesSAP\n\nC_FIG

neuroscience↗

bioRxiv2018

Genetic variants related to antihypertensive targets inform drug efficacy and side effects

BackgroundDrug effects can be investigated through natural variation in the genes for their protein targets. We aimed to use this approach to explore the potential side effects and repurposing potential of antihypertensive drugs, which are amongst the most commonly used medications worldwide.\n\nMethodsWe identified genetic instruments for antihypertensive drug classes as variants in the gene for the corresponding target that associated with systolic blood pressure at genome-wide significance. To validate the instruments, we compared Mendelian randomisation (MR) estimates for drug effects on coronary heart disease (CHD) and stroke risk to randomised controlled trial (RCT) results. Phenome-wide association study (PheWAS) in the UK Biobank was performed to identify potential side effects and repurposing opportunities, with findings investigated in the Vanderbilt University Biobank (BioVU) and in observational analysis of the UK Biobank.\n\nFindingsWe identified suitable genetic instruments for beta-blockers (BBs) and calcium channel blockers (CCBs). MR estimates for their effect on CHD and stroke risk respectively were comparable to results from RCTs against placebo. PheWAS in the UK Biobank identified an association of the CCB genetic risk score (scaled to drug effect) with increased risk of diverticulosis (odds ratio [OR] 1.23, 95%CI 1.10-1.38), with a consistent estimate found in BioVU (OR 1.16, 95%CI 0.94-1.44). Association with diverticulosis was further supported in observational analysis of CCB use in the UK Biobank (OR 1.08, 95%CI 1.02-1.15).\n\nInterpretationWe identified valid genetic instruments for BBs and CCBs. Using genetic and observational approaches, we highlighted a previously unreported potential detrimental effect of CCBs on risk of diverticulosis. This work serves as a proof of concept that investigation of genetic variants can offer a complementary approach to exploring the efficacy and side effects of anti-hypertensive medications.\n\nFundingWellcome Trust.

genetics↗

bioRxiv2018

In vivo widefield calcium imaging of the mouse cortex for analysis of network connectivity in health and brain disease

The organization of brain areas in functionally connected networks, their dynamic changes, and perturbations in disease states are subject of extensive investigations. Research on functional networks in humans predominantly uses functional magnetic resonance imaging (fMRI). However, adopting fMRI and other functional imaging methods to mice, the most widely used model to study brain physiology and disease, poses major technical challenges and faces important limitations. Hence, there is great demand for alternative imaging modalities for network characterization. Here, we present a refined protocol for in vivo widefield calcium imaging of both cerebral hemispheres in mice expressing a calcium sensor in excitatory neurons. We implemented a stringent protocol for minimizing anesthesia and excluding movement artifacts which both imposed problems in previous approaches. We further adopted a method for unbiased identification of functional cortical areas using independent component analysis (ICA) on resting-state imaging data. Biological relevance of identified components was confirmed using stimulus-dependent cortical activation. To explore this novel approach in a model of focal brain injury, we induced photothrombotic lesions of the motor cortex, determined changes in inter- and intrahemispheric connectivity at multiple time points up to 56 days post-stroke and correlated them with behavioral deficits. We observed a severe loss in interhemispheric connectivity after stroke, which was partially restored in the chronic phase and associated with corresponding behavioral motor deficits. Taken together, we present an improved widefield calcium imaging tool accounting for anesthesia and movement artifacts, adopting an advanced analysis pipeline based on human fMRI algorithms and with superior sensitivity to recovery mechanisms in mouse models compared to behavioral tests. This tool will enable new studies on interhemispheric connectivity in murine models with comparability to human imaging studies for a wide spectrum of neuroscience applications in health and disease.

neuroscience↗

bioRxiv2018

The Subtype Specificity of Genetic Loci Associated with Stroke in 16,664 cases and 32,792 controls

BackgroundGenome-wide association studies have identified multiple loci associated with stroke. However, the specific stroke subtypes affected, and whether loci influence both ischaemic and haemorrhagic stroke, remains unknown. For loci associated with stroke, we aimed to infer the combination of stroke subtypes likely to be affected, and in doing so assess the extent to which such loci have homogeneous effects across stroke subtypes.\n\nMethodsWe performed Bayesian multinomial regression in 16,664 stroke cases and 32,792 controls of European ancestry to determine the most likely combination of stroke subtypes affected for loci with published genome-wide stroke associations, using model selection. Cases were subtyped under two commonly used stroke classification systems, Trial of Org 10172 Acute Stroke Treatment (TOAST) and Causative Classification of Stroke (CCS). All individuals had genotypes imputed to the Haplotype Reference Consortium 1.1 Panel.\n\nResultsSixteen loci were considered for analysis. Seven loci influenced both haemorrhagic and ischaemic stroke, three of which influenced ischaemic and haemorrhagic subtypes under both TOAST and CCS. Under CCS, 4 loci influenced both small vessel stroke and intracerebral haemorrhage. An EDNRA locus demonstrated opposing effects on ischaemic and haemorrhagic stroke. No loci were predicted to influence all stroke subtypes in the same direction and only one locus (12q24) was predicted to influence all ischaemic stroke subtypes.\n\nConclusionsHeterogeneity in the influence of stroke-associated loci on stroke subtypes is pervasive, reflecting differing causal pathways. However, overlap exists between haemorrhagic and ischaemic stroke, which may reflect shared pathobiology predisposing to small vessel arteriopathy. Stroke is a complex, heterogeneous disorder requiring tailored analytic strategies to decipher genetic mechanisms.

genetics↗