Biology subjects

McDade, K.

Publications and source records attributed to McDade, K..

8 recordsLinked to original sources

bioRxiv2026

Mononuclear myeloid cells mount an adaptive protective response to intracerebral haemorrhage by activation of NRF2

Following intracerebral haemorrhage (ICH), secondary injury contributes to negative outcomes. Here, we describe inter-dependent injurious and adaptive-protective pathways that form a therapeutically modifiable ICH response. In perihaematomal tissue from post-mortem ICH patients, transcriptomic analysis pointed to concurrent perihaematomal activation of the cytoprotective stress-induced transcription factor NRF2 and activation of interferon responses, with mononuclear myeloid cells (microglia and monocyte-derived cells, MMCs) and astrocytes contributing to this signature. In vitro, microglia-astrocyte-neuron co-culture studies revealed that microglial NRF2 activation was induced by clot-conditioned medium and could influence the interferon pathway in both microglia themselves as well as astrocytes. In vivo, MMC-specific deletion of NRF2 inhibited NRF2 target-gene induction, exacerbated interferon pathway activation following ICH, and impaired functional recovery. Pharmacological NRF2 activation suppressed interferon pathway induction post-ICH, and direct interferon pathway antagonism rescued neurological recovery deficits caused by MMC-specific NRF2 deficiency. Thus, augmenting NRF2- or inhibiting interferon-signalling may improve outcomes after ICH.

neuroscience↗

bioRxiv2026

Abrupt Pericyte Loss Precedes Endothelial Activation in Cerebral Small Vessel Disease

Cerebral small vessel disease (cSVD) is a leading cause of stroke and vascular cognitive impairment, yet the cellular mechanisms underlying microvascular dysfunction in human disease remain incompletely understood. In particular, the relationship between pericyte alterations and endothelial activation, two key features of blood-brain barrier dysfunction, remains unresolved. Here, we performed a quantitative single-vessel analysis of the human cortical microvasculature across increasing cSVD severity and ageing. Using multiplex immunohistochemistry combined with spectral unmixing and automated image analysis, we analysed 11,409 microvascular fragments from post-mortem brain tissue derived from 20 cases. Endothelial cells, pericytes, and endothelial activation were assessed using PECAM-1, PDGFR{beta}, and VCAM-1, respectively. Microvascular density and diameter differed between cortical grey matter and the underlying white matter, with white matter vessels being less dense and wider in controls. While vessel diameter remained stable across disease stages, microvascular density increased with cSVD severity and age in the white matter. At the molecular level, PDGFR{beta} signal decreased markedly with increasing cSVD severity, consistent with progressive pericyte loss. This reduction was observed in both grey and white matter and correlated with disease severity and age. Notably, intermediate disease groups displayed marked heterogeneity, with vessels exhibiting either preserved or near-complete pericyte coverage, suggesting a potentially bimodal transition. In parallel, endothelial markers PECAM-1 and VCAM-1 increased significantly with disease severity, reflecting endothelial activation. Unsupervised Gaussian mixture clustering of marker expression identified three vascular states characterised by (i) preserved pericytes with low endothelial activation, (ii) marked pericyte loss without endothelial activation, and (iii) combined pericyte depletion and endothelial activation. These clusters broadly aligned with clinical severity but revealed intermediate states not captured by post-mortem diagnosis alone. Together, these findings suggest that pericyte loss and endothelial activation are partially dissociated processes that occur in a sequential progression in human cSVD, supporting pericyte dysfunction as an early event and highlighting it as a potential therapeutic target in microvascular disease.

pathology↗

bioRxiv2026

Standardized brain and plasma EV enrichment pipeline validated for Single sample multi-Omic and fatty acids applications in Mouse and Human

Extracellular vesicles (EVs) are key mediators of intercellular communication, yet their molecular profiles across tissues and species remain poorly characterized, particularly due to currently available methods requiring a large amount of biological material (tissue or biofluids). Here, we established a workflow allowing the deep phenotyping of EV cargos starting from single samples of human and mouse origin. We took advantage of standardised EV isolation procedures and multi-omic techniques for the isolation and analysis of EVs from brain and plasma of human and mouse, integrating flow cytometric profiling, proteomics, miRNA sequencing, and fatty acid profiling. Here we report specific brain-derived EVs proteome, enriched in neuronal and glial proteins, polyunsaturated fatty acids profiles, and distinct miRNAs. At the periphery, we also report plasma-derived EVs signatures reflecting immune, metabolic, and systemic transport functions. Despite these expected material-specific differences, EVs from the same source displayed greater similarity across species than EVs from different material, supporting the translational relevance of mouse models. Importantly, using state-of-the-art miRNA profiling approach, we identified novel EV-specific miRNAs in human and mouse brain EVs, potentially allowing the exploration of new roles in neuronal signalling. Overall, we report here a method enabling deep multi-omic characterization from minimal starting material, offering a practical approach for studies with limited biological samples. These findings also demonstrate that the origin strongly shapes EV composition, highlighting conserved and species-specific molecular features, and provide a scalable framework for multi-omic investigations of EV biology. Summary StatementWe present a standardised workflow allowing multi-omic profiling of brain and plasma-derived EVs from minimal human and mouse material. Our findings reveal both tissue-specific and species specific EV molecular signatures.

neuroscience↗

bioRxiv2025

Systemic infections alter cortical transcriptional signatures in Alzheimer's disease

Alzheimers disease (AD) is characterized by neuroinflammation, yet the impact of concurrent systemic infections on the AD brain remains poorly understood. We investigated the molecular mechanisms underlying the central nervous system response to systemic infections in AD by analyzing RNA sequencing data generated in the prefrontal cortex from 202 post-mortem donors (113 AD, 89 controls), where we stratified by the presence of a respiratory infection at the time of death. We identified 763 significantly differentially expressed genes (DEGs) between AD and controls without infection, which were enriched for oxidative phosphorylation and neurodegenerative pathways. In contrast, 122 DEGs distinguished AD from controls during infection, with 57 genes uniquely altered in AD in the presence of infection, including MAPK4, VAV3, and POU3F4, implicating infection-dependent mechanisms of vascular and immune regulation. Pathway activity analysis revealed that infection in AD suppresses some immune and vascular pathways, while enhancing transcriptional and developmental programs. Weighted gene co-expression network analysis uncovered three key modules: one module strongly associated with AD, enriched for aging and signal transduction; one module linked to both AD and infection, highlighting cytoskeletal remodelling and host-pathogen interactions; and one module specific to infection, enriched in astrocytes, pericytes, and endothelial cells, implicating blood-brain barrier dysfunction. These findings suggest that systemic respiratory infections reshape transcriptional programs in the AD brain, dampening immune effector pathways and engaging vascular and host-pathogen processes in blood-brain-barrier-associated cell types. Our results highlight the complex interplay between systemic infection, neuroinflammation, and vascular responses in AD.

neuroscience↗

bioRxiv2025

Decades-long elevation of interferon-alpha drives a Sjogren disease endotype: an interdisciplinary study

BACKGROUNDMechanistic heterogeneity is a major obstacle to the development of effective treatment for Sjogren disease (SjD) and there is a pressing need to stratify SjD according to precision medicine principles. Aberrant activation of the type I interferon (IFN) pathway represents a leading candidate pathway, but a causal role of elevated IFN- in driving a Sjogren disease endotype remains to be established. METHODSWe used ultrasensitive single molecule ELISA, and an oligoprotein interferon signature score (derived from broad capture proteomics), to study the role of IFN- in Sjogren disease. We analysed samples from the UK Primary Sjogren Syndrome Registry (UKPSSR, n=177) and UK Biobank Plasma Proteomics Project (n=47606 without Sjogren, n=257 with Sjogren, including 137 individuals sampled prior to diagnosis) to determine the timecourse and immune endotype associated with elevated IFN-. To address causality we created a new transgenic mouse model of IFN- overexpression to establish whether chronically elevated IFN- drives this immune endotype. FINDINGSOligoprotein interferon signatures can be detected at least 14 years prior to diagnosis of Sjogren disease in the UK Biobank-PPP. IFN- concentrations are elevated in 60% of Sjogren disease patients in the UKPSSR. Individuals with elevated IFN- display a distinct immunological endotype characterised by cytopenias, hypergammaglobulinaemia, multiple autoantibodies and autoimmunity against the Sjogren autoantigen TRIM21/Ro52. To address the key question of causal direction, we created a new mouse model of systemic chronic IFN- elevation, in which Ifn4 is overexpressed by conventional dendritic cells. This model recapitulates key features of the endotype and can be partially reversed by IFNAR1 blockade. INTERPRETATIONElevation of IFN- drives an immune endotype of Sjogren disease, originating over a decade prior to diagnosis. SjD patients with elevated IFN- concentrations are broadly clinically similar to those with normal IFN- concentrations, yet are immunologically distinct. This highlights the mechanistic heterogeneity of SjD and the need for immunological stratification along precision medicine principles, using high resolution biomarkers. As well as demonstrating causal direction, biological modelling shows that chronic IFN- elevation over the lifecourse has the potential to establish persistent immune dysregulation which responds only partially to interferon receptor blockade. These findings provide insights into SjD and other "interferonopathic" rheumatological disorders. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSWe searched MEDLINE for "Sjogrens Syndrome/Disease" and "interferon", including the terms "subsets", "sub-groups", "phenotypes", and "endotypes", filtering by "clinical trial", "stratification", and "immune-mediated inflammatory". We also included major review articles from noted experts. We identified reports of associations between IFN- and SjD, usually using indirect or imprecise measures of IFN-. None of these studies included prediagnostic samples and causal inference was limited. Added value of this studyThis study shows that IFN-, when measured directly using ultrasensitive single molecule ELISA approaches (uniquely optimised to determine healthy control concentrations), is elevated in a subset of people with SjD with a specific immunological endotype. Analysis of prediagnostic proteomics shows this elevation can be detected up to 14 years before diagnosis. We show that IFN- drives this endotype (as opposed to vice versa) by recapitulating key endotype features in a novel and unambiguous experimental mouse model of chronic IFN- elevation. We also show that the pathogenic consequences of IFN- elevation over long periods of time can only be partially reversed using IFNAR blockade. Implications of all the available evidenceThese data have important implications for future research, clinical practice, trial design, and therapeutic development. First, our findings provide clinical evidence, supported by unambiguous preclinical evidence, that decades-long elevated IFN can cause and drive a SjD endotype - and accurately defines the level of heterogeneity. Secondly, we provide biomarkers which may be of use in stratifying clinical trial design and also for early identification of at-risk individuals. Thirdly we provide biological proof of principle that longstanding and potentially undiagnosed elevation of IFN- can establish persistent immune dysregulation which may respond only partially to IFNAR blockade. Together these findings inform precision medicine approaches and future trial design.

immunology↗

bioRxiv2025

Differential Cellular Mechanisms Underlie Language and Executive Decline in Amyotrophic Lateral Sclerosis

Cognitive manifestations, including impairment in language and executive functions, are seen in amyotrophic lateral sclerosis (ALS), but the mechanisms that underlie these deficits remain unclear. To address this, we mapped prefrontal cortex regions from ALS patients by integrating spatial and single-nucleus transcriptomics in a cognitively stratified patient cohort. We uncover that cognitive impairment in ALS is associated with distinct patterns of neuronal dysfunction and glial-vascular dysregulation that vary by region and cognitive subtype. Executive dysfunction is linked to reduced mitochondrial and synaptic activity in neurons localized to the deeper layers of the dorsolateral prefrontal cortex, whereas language-related deficits track with a more diffuse, pan-regional response involving both glial and vascular abnormalities. Our analyses also identify signatures in the prefrontal cortex that span both motor and cognitive phenotypes, including a multicellular gliosis response. The findings reveal that the clinical heterogeneity of ALS is driven by phenotype-specific molecular and cellular interactions in motor and non-motor regions of the brain.

genomics↗

bioRxiv2022

Single-cell Mendelian randomisation identifies cell-type specific genetic effects on human brain disease and behaviour

Translating genome-wide association loci to therapies requires knowledge of the causal genes, their directionality of effect and the cell-types in which they act. To infer these relationships in the human brain, we implemented Mendelian randomisation using single cell-type expression quantitative trait loci (eQTLs) as genetic anchors. Expression QTLs were mapped across 8 major cell-types in brain tissue exclusively ascertained from donors with no history of brain disease. We report evidence for a causal association between the change in expression of 118 genes and one or more of 16 brain phenotypes, revealing candidate targets for risk mitigation and opportunities for shared preventative therapeutic strategies. We highlight key causal genes for neurodegenerative and neuropsychiatric disease and for each, we report its cellular context and the therapeutic directionality required for risk mitigation. Our use of control samples establishes a new resource for the causal interpretation of GWAS risk alleles for human brain phenotypes.

neuroscience↗

bioRxiv2021

Random forest modelling of neuropathological features identifies microglial activation as an accurate pathological classifier of C9orf72-related amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are regarded as two ends of a pathogenetic spectrum, termed ALS-frontotemporal spectrum disorder (ALS-FTSD). However, it is currently difficult to predict where on the spectrum an individual will lie, especially for patients with C9orf72 hexanucleotide repeat expansions (HRE), a mutation associated with both ALS and FTD. It has been shown that both inflammation and protein misfolding influence aspects of ALS and ALS-FTSD disease pathogenesis, such as the manifestation or severity of motor or cognitive symptoms. Previous studies have highlighted markers which may influence C9orf72-associated disease presentation in a targeted fashion, though there has yet to be a systematic and quantitative assessment of common immunohistochemical markers to investigate the significance of these pathways in an unbiased manner. Here we report the first extensive digital pathological assessment with random forest modelling of pathological markers often used in neuropathology practice. This study profiles glial activation and protein misfolding in a cohort of deeply clinically profiled post-mortem tissue from patients with a C9orf72 HRE, who either met the criteria for a diagnosis of ALS or ALS-FTSD. We show that microglial immunohistochemical staining features, both morphological and spatial, are the best independent classifiers of disease status and that clinicopathological associations exist between microglial activation status and cognitive dysfunction in ALS-FTSD patients with C9orf72 HRE. Furthermore, we show that spatially resolved changes in FUS staining are also an accurate predictor of disease status, implying that liquid-liquid phase shift of this aggregation-prone RNA-binding protein may be important in ALS caused by a C9orf72 HRE. Our findings provide further support to the hypothesis of dysfunctional immune regulation and proteostasis in the pathogenesis of C9orf72 ALS and provide a framework for digital analysis of commonly used neuropathological stains as a tool to enrich our understanding of clinicopathological associations between cohorts.

neuroscience↗