Biology subjects

Sanchez, T.

Publications and source records attributed to Sanchez, T..

At least 19 recordsLinked to original sources

bioRxiv2026

Conserved Brain-Associated CD8+ T Cell Programs and Their Regulation by the Brain Microenvironment

CD8+ T cells are increasingly recognized as components of the healthy brain, yet whether their specialized functional characteristics are conserved across species and how the brain microenvironment regulates their effector programs remain poorly understood. Here, we characterized brain-associated CD8+ T cells in the common marmoset and investigated their regulation by brain-derived signals. Flow cytometric analysis revealed a substantial population of CD8+ T cells in the healthy marmoset brain parenchyma that exhibited high IFN-{gamma} competence but minimal granzyme B (GzmB) expression, resembling the functional phenotype previously identified in mice. Single-cell transcriptomic analyses of mouse and marmoset CD8+ T cells revealed tissue-associated transcriptional heterogeneity and distinct differentiation- and effector-associated programs. To investigate how the brain microenvironment shapes these characteristics, we exposed activated mouse CD8+ T cells to brain lysate and performed targeted CRISPR interference screening of 107 cell-surface receptor genes coupled with single-cell RNA sequencing. Brain lysate selectively reduced Gzmb and Ifng expression while increasing Tnf and Xcl1, indicating differential regulation of cytotoxic and inflammatory effector programs. Receptor perturbations revealed heterogeneous transcriptional responses and identified candidate pathways potentially involved in sensing brain-derived signals. Together, these findings identify shared functional characteristics of brain-associated CD8+ T cells across rodents and nonhuman primates and establish a framework for understanding how the neural microenvironment shapes adaptive immune function.

immunology↗

bioRxiv2026

Characterization of Fetal Cortical Development Using Spectral Analysis of Gyrification (SPANGY)

The prenatal period of human brain development is critical for mental health and cognition across the entire lifespan. During this period, the cortex undergoes a dramatic transformation from a smooth lissencephalic surface into an elaborately folded structure, a process whose precise characterization is essential for understanding neurodevelopmental trajectories. This study represents the first application of Spectral Analysis of Gyrification (SPANGY) to a large multi-centric fetal brain MRI dataset (635 subjects, 20-38 weeks gestational age). SPANGY characterizes geometric variations on a surface based on the wavelength of folds, hence, providing a quantitative local description of gyrification at the individual level. Using rigorous normative modeling (GAMLSS) and statistical harmonization (ComBat-GAM), we established age-specific reference trajectories for multi-scale gyrification features (spectral frequency bands). We provide the first ever quantification of the temporally-ordered emergence of cortical folding in successive waves: the earliest-emerging low frequency, deep fissures are progressively superseded by the accelerating expansion of higher frequency folds. The normative curves provide the first step in taking prenatal neurodevelopmental assessment from qualitative inspection into a rigorous statistical inference, creating an objective reference against which deviations from healthy brain growth can be caught earlier, and with greater precision.

neuroscience↗

bioRxiv2026

Attentive-SPIDNA: Attention-based neural networks for population genetics

Artificial neural networks (ANNs) have recently offered new perspectives to solve inference problems from high dimensional data in numerous scientific fields, but it is yet unclear which architectures are the most suited to genomic data. Here, we present a new ANN architecture integrating attention mechanisms to infer effective population size history from genomic data. Built upon our previous exchangeable architecture SPIDNA, Attentive-SPIDNA adds attention layers that allow computing more expressive and complex features from combinations of haplotypes. The contribution of each haplotype to the features is learned automatically and depends on its content and affinity with the other haplotypes. Likewise, we use this mechanism to automatically perform a voting scheme that aggregates predictions from different genomic regions. This new architecture outperforms approximate Bayesian computation and previously published neural networks while relying directly on raw genetic data and being invariant to haplotype permutation in the input. As a proof-of-concept, we use this architecture to infer the effective population size history of 54 populations from the HGDP dataset (Bergstrom et al, 2020). This application highlights the ability of the network to handle data with a varying number of haplotypes and to quickly perform predictions for datasets including numerous populations. Therefore, the proposed mechanism could be integrated to various neural networks solving population genetics tasks.

evolutionary biology↗

bioRxiv2026

Data quality biases normative models derived from fetal brain MRI

Normative modeling is increasingly used to characterize typical growth trajectories and identify atypical neurodevelopment, including early brain development using magnetic resonance imaging (MRI) acquired before birth. Recent work has emphasized the importance of large sample sizes for accurate and robust centile estimation. In this study, we investigate how image quality influences fetal brain normative models, a critical factor in this context where MRI is acquired on a moving fetus in utero. Using a multi-centric cohort of 635 fetal MRI scans, we applied a standardized visual quality control (QC) protocol with continuous quality ratings. We fit normative models for multiple brain structures under progressively relaxed QC stringency, and quantified the deviations in centile estimates relative to a high-quality reference subgroup. Our results showed that including lower-quality data systematically biased normative centiles, with the strongest effects observed in the outer centiles, particularly the lower tail (1st-10th). Bias increased progressively as QC stringency was relaxed and could not be attributed solely to the number of subjects used to fit the models. Quality-induced bias was structure-dependent, and often not visually apparent at the segmentation level. These findings highlight that image quality is an important source of bias in normative fetal brain modeling, and that increasing sample size at the expense of quality may systematically affect centile estimates, potentially jeopardizing the utility of the model.

neuroscience↗

bioRxiv2025

Endothelial Sphingosine-1-Phosphate Receptor (S1PR) 1, a Functional S1PR in the Human Cerebrovascular Endothelium, Limits Blood Brain Barrier Permeability and Neuronal Injury following Subarachnoid Hemorrhage in Mice.

Hypoxia-induced blood-brain barrier (BBB) permeability has been identified as a key contributor to the progression of ischemic-hypoxic brain injury and neuronal dysfunction in stroke and other cerebrovascular diseases. Emerging clinical evidence highlights that the vasoprotective signaling properties of high-density lipoprotein (HDL), mediated through its bioactive lipid component sphingosine-1-phosphate (S1P), may be impaired in cardiovascular and inflammatory conditions. Nonetheless, the precise contributions and mechanistic roles of S1P signaling within the cerebral microvasculature remain insufficiently characterized. In this study, we aimed to elucidate the role of S1P signaling via its endothelial receptor S1PR1 in the pathophysiology of early brain injury following subarachnoid hemorrhage (SAH), a particularly severe form of stroke. Additionally, we sought to evaluate the relevance of the endothelial S1PR1 pathway in the human cerebrovascular endothelium, its functional role in hypoxia-induced cerebral endothelial barrier dysfunction, and its underlying molecular mechanisms. To address these objectives, we utilized endothelial-specific S1PR1 knockout mice subjected to the endovascular rupture model of aneurysmal SAH, performed mechanistic studies in primary human cerebral microvascular endothelial cells, and characterized S1PR1 expression in human brain tissue using validated protocols. Our findings reveal robust expression of S1PR1 in the cerebrovascular endothelium of both mice and humans. Functional analyses demonstrated that S1PR1 is critical for maintaining BBB integrity and mitigating neuronal injury in the context of SAH. Mechanistic in vitro studies indicated that S1PR1 exerts a vasoprotective effect by limiting hypoxia-induced BBB dysfunction in human primary brain microvascular endothelial cells through inhibition of Rho-associated kinase (ROCK)-mediated phosphorylation of myosin light chain (MLC), suppression of stress fiber formation and caveolin-1-dependent endosomal trafficking. These results highlight the pivotal role of endothelial S1PR1 signaling in preserving cerebral vascular integrity and provide a strong scientific foundation for developing novel therapeutic approaches targeting the S1P pathway in the endothelium to enhance neurovascular protection.

neuroscience↗

bioRxiv2024

Defacing biases visual quality assessments of structural MRI

A critical step before data-sharing of human neuroimaging is removing facial features to protect individuals privacy. However, not only does this process redact identifiable information about individuals, but it also removes non-identifiable information. This introduces undesired variability into downstream analysis and interpretation. This registered report investigated the degree to which the so-called defacing altered the quality assessment of T1-weighted images of the human brain from the openly available "IXI dataset". The effect of defacing on manual quality assessment was investigated on a single-site subset of the dataset (N=185). By comparing two linear mixed-effects models, we determined that four trained human raters perception of quality was significantly influenced by defacing by modeling their ratings on the same set of images in two conditions: "nondefaced" (i.e., preserving facial features) and "defaced". In addition, we investigated these biases on automated quality assessments by applying repeated-measures, multivariate ANOVA (rm-MANOVA) on the image quality metrics extracted with MRIQC on the full IXI dataset (N=581; three acquisition sites). This study found that defacing altered the quality assessments by humans and showed that MRIQCs quality metrics were mostly insensitive to defacing.

bioinformatics↗

bioRxiv2024

Assessing data quality on fetal brain MRI reconstruction: a multi-site and multi-rater study

Quality assessment (QA) has long been considered essential to guarantee the reliability of neuroimaging studies. It is particularly important for fetal brain MRI, where unpredictable fetal motion can lead to substantial artifacts in the acquired images. Multiple images are then combined into a single volume through super-resolution reconstruction (SRR) pipelines, a step that can also introduce additional artifacts. While multiple studies designed automated quality control pipelines, no work evaluated the reproducibility of the manual quality ratings used to train these pipelines. In this work, our objective is twofold. First, we assess the inter- and intra-rater variability of the quality scoring performed by three experts on over 100 SRR images reconstructed using three different SRR pipelines. The raters were asked to assess the quality of images following 8 specific criteria like blurring or tissue contrast, providing a multi-dimensional view on image quality. We show that, using a protocol and training sessions, artifacts like bias field and blur level still have a low agreement (ICC below 0.5), while global quality scores show very high agreement (ICC = 0.9) across raters. We also observe that the SRR methods are influenced differently by factors like gestational age, input data quality and number of stacks used by reconstruction. Finally, our quality scores allow us to unveil systematic weaknesses of the different pipelines, indicating how further development could lead to more robust, well rounded SRR methods. Our rating protocol is made available at https://doi.org/10.5281/zenodo.15696638.

neuroscience↗

bioRxiv2024

Molecular and functional alterations in the cerebral microvasculature in an optimized mouse model of sepsis-associated cognitive dysfunction.

Systemic inflammation has been implicated in the development and progression of neurodegenerative conditions such as cognitive impairment and dementia. Recent clinical studies indicate an association between sepsis, endothelial dysfunction, and cognitive decline. However, the investigations of the role and therapeutic potential of the cerebral microvasculature in systemic inflammation-induced cognitive dysfunction have been limited by the lack of standardized experimental models for evaluating the alterations in the cerebral microvasculature and cognition induced by the systemic inflammatory response. Herein, we validated a mouse model of endotoxemia that recapitulates key pathophysiology related to sepsis-induced cognitive dysfunction, including the induction of an acute systemic hyperinflammatory response, blood-brain barrier (BBB) leakage, neurovascular inflammation, and memory impairment after recovery from the systemic inflammatory response. In the acute phase, we identified novel molecular (e.g. upregulation of plasmalemma vesicle associated protein, a driver of endothelial permeability, and the pro-coagulant plasminogen activator inhibitor-1, PAI-1) and functional perturbations (i.e., albumin and small molecule BBB leakage) in the cerebral microvasculature along with neuroinflammation. Remarkably, small molecule BBB permeability, elevated levels of PAI-1, intra/perivascular fibrin/fibrinogen deposition and microglial activation persisted 1 month after recovery from sepsis. We also highlight molecular neuronal alterations of potential clinical relevance following systemic inflammation including changes in neurofilament phosphorylation and decreases in postsynaptic density protein 95 and brain-derived neurotrophic factor suggesting diffuse axonal injury, synapse degeneration and impaired neurotrophism. Our study serves as a standardized model to support future mechanistic studies of sepsis-associated cognitive dysfunction and to identify novel endothelial therapeutic targets for this devastating condition. SIGNIFICANCEThe limited knowledge of how systemic inflammation contributes to cognitive decline is a major obstacle to the development of novel therapies for dementia and other neurodegenerative diseases. Clinical evidence supports a role for the cerebral microvasculature in sepsis-induced neurocognitive dysfunction, but the investigation of the underlying mechanisms has been limited by the lack of standardized experimental models. Herein, we optimized a mouse model that recapitulates important pathophysiological aspects of systemic inflammation-induced cognitive decline and identified key alterations in the cerebral microvasculature associated with cognitive dysfunction. Our study provides a reliable experimental model for mechanistic studies and therapeutic discovery of the impact of systemic inflammation on cerebral microvascular function and the development and progression of cognitive impairment.

neuroscience↗

bioRxiv2024

Moesin activation controls bone resorption and tunneling nanotube-dependent osteoclast fusion

Cell-cell fusion is an evolutionarily conserved process that is essential for many functions, including fertilisation and the formation of placenta, muscle and osteoclasts, multinucleated cells that are unique in their ability to resorb bone. The mechanisms of osteoclast multinucleation involve dynamic interactions between the actin cytoskeleton and the plasma membrane that are still poorly characterized. Here, we found that moesin, a cytoskeletal linker protein member of the Ezrin/Radixin/Moesin (ERM) protein family, is activated during osteoclast maturation and plays an instrumental role in both osteoclast fusion and function. In mouse and human osteoclast precursors, moesin inhibition favors their ability to fuse into multinucleated osteoclasts. Accordingly, we demonstrated that moesin depletion decreases membrane-to-cortex attachment and enhances the formation of tunneling nanotubes (TNTs), F-actin-based intercellular bridges that we reveal here to trigger cell-cell fusion. Moesin also controls HIV-1- and inflammation-induced cell fusion. In addition, moesin regulates the formation of the sealing zone, the adhesive structure determining osteoclast bone resorption area, and thus controls bone degradation, via a {beta}3-integrin/RhoA/SLK pathway. Supporting our results, moesin-deficient mice present a reduced density of trabecular bones and increased osteoclast abundance and activity. These findings provide a better understanding of the regulation of cell-cell fusion and osteoclast biology, opening new opportunities to specifically target osteoclast activity in bone disease therapy.

cell biology↗

bioRxiv2024

Genome-wide association study reveals multiple loci for analgesia and heroin taking behavior in outbred rats

The increased prevalence of opioid use disorder (OUD) makes it imperative to disentangle the biological mechanisms contributing to individual differences in OUD vulnerability. OUD shows strong heritability, however genetic variants contributing to vulnerability remain poorly defined. We performed a genome-wide association study using over 850 male and female heterogeneous stock (HS) rats to identify genes underlying behaviors associated with OUD such as nociception, as well as heroin-taking, extinction and seeking behaviors. By using an animal model of OUD, we were able to identify genetic variants associated with distinct OUD behaviors while maintaining a uniform environment, an experimental design not easily achieved in humans. Furthermore, we used a novel non-linear network-based clustering approach to characterize rats based on OUD vulnerability to assess genetic variants associated with OUD susceptibility. Our findings confirm the heritability of several OUD-like behaviors, including OUD susceptibility. Additionally, several genetic variants associated with nociceptive threshold prior to heroin experience, heroin consumption, escalation of intake, and motivation to obtain heroin were identified. Tom1, a microglial component, was implicated for nociception. Several genes involved in dopaminergic signaling, neuroplasticity and substance use disorders, including Brwd1, Pcp4, Phb1l2 and Mmp15 were implicated for the heroin traits. Additionally, an OUD vulnerable phenotype was associated with genetic variants for consumption and break point, suggesting a specific genetic contribution for OUD-like traits contributing to vulnerability. Together, these findings identify novel genetic markers related to the susceptibility to OUD-relevant behaviors in HS rats.

genetics↗

bioRxiv2023

The membrane-actin linkers ezrin, radixin, and moesin are dispensable for macrophage migration and cortex mechanics.

The cellular actin cortex provides crucial mechanical support and plays critical roles in numerous functions, including cell division and migration. The proteins of the ERM family, ezrin, radixin, and moesin, are central to these processes by linking the plasma membrane to the actin cytoskeleton. To investigate the individual contributions of these three proteins to leukocyte migration, we generated single and triple ERM knock-out macrophages. Surprisingly, we found that even in the absence of ERMs, macrophages can still form the different actin structures promoting cell migration, such as filopodia, lamellipodia, podosomes, and ruffles. Furthermore we discovered that, unlike every other cell type previously investigated, the single or triple knock-out of ERMs does not affect macrophage migration in a large diversity of contexts. Finally, we demonstrated that the loss of ERMs in macrophages does not affect the mechanics of their actin cortex. These findings challenge the notion that ERMs are universally essential for cortex mechanics and cell migration and support the notion that the macrophage cortex may have diverged from that of other cells to allow for their adaptive cortical plasticity.

cell biology↗

bioRxiv2023

Vascular oxidative stress causes neutrophil arrest in brain capillaries, leading to decreased cerebral blood flow and contributing to memory impairment in a mouse model of Alzheimer's disease

INTRODUCTIONIn this study, we explore the role of oxidative stress produced by NOX2-containing NADPH oxidase as a molecular mechanism causing capillary stalling and cerebral blood flow deficits in the APP/PS1 mouse model of AD. METHODSWe inhibited NOX2 in APP/PS1 mice by administering a 10 mg/kg dose of the peptide inhibitor gp91-ds-tat i.p., for two weeks. We used in vivo two-photon imaging to measure capillary stalling, penetrating arteriole flow, and vascular inflammation. We also characterized short-term memory function and gene expression changes in cerebral microvessels. RESULTSWe found that after NOX2 inhibition capillary stalling, as well as parenchymal and vascular inflammation, were significantly reduced. In addition, we found a significant increase in penetrating arteriole flow, followed by an improvement in short-term memory, and downregulation of inflammatory gene expression pathways. DISCUSSIONOxidative stress is a major mechanism leading to microvascular dysfunction in AD, and represents an important therapeutic target.

neuroscience↗

bioRxiv2020

Cellular Stress Signaling Activates Type-I IFN Response Through FOXO3-regulated Lamin Posttranslational Modification

Neural stem/progenitor cells (NSPCs) persist over the lifespan while encountering constant challenges from age or injury related brain environmental changes, including elevated oxidative stress. A time-dependent stress response that regulates the dynamic balance between quiescence and differentiation is thus essential to preserve NSPC long-term regenerative potential. Here we report that acutely elevated cellular oxidative stress in NSPCs suppresses neurogenic differentiation through induction of FOXO3-mediated cGAS/STING and type I interferon (IFN-I) responses. We show that oxidative stress activates FOXO3 promoting upregulation of its transcriptional target glycine-N-methyltransferase (GNMT) and thus depletion of s-adenosylmethionine (SAM), a key co-substrate involved in methyl group transfer reactions. Mechanistically, we demonstrate that reduced intracellular SAM availability disrupts carboxymethylation and maturation of nuclear lamin, which trigger cytosolic release of chromatin fragments and subsequent activation of the cGAS/STING/IFN-I cascade. Together, our findings suggest the FOXO3-GNMT/SAM-lamin-cGAS/STING-IFN-I signaling cascade as a critical stress response program that preserves its long-term regenerative potential.

cell biology↗

bioRxiv2020

Deep learning for population size history inference: design, comparison and combination with approximate Bayesian computation

AO_SCPLOWBSTRACTC_SCPLOWFor the past decades, simulation-based likelihood-free inference methods have enabled researchers to address numerous population genetics problems. As the richness and amount of simulated and real genetic data keep increasing, the field has a strong opportunity to tackle tasks that current methods hardly solve. However, high data dimensionality forces most methods to summarize large genomic datasets into a relatively small number of handcrafted features (summary statistics). Here we propose an alternative to summary statistics, based on the automatic extraction of relevant information using deep learning techniques. Specifically, we design artificial neural networks (ANNs) that take as input single nucleotide polymorphic sites (SNPs) found in individuals sampled from a single population and infer the past effective population size history. First, we provide guidelines to construct artificial neural networks that comply with the intrinsic properties of SNP data such as invariance to permutation of haplotypes, long scale interactions between SNPs and variable genomic length. Thanks to a Bayesian hyperparameter optimization procedure, we evaluate the performance of multiple networks and compare them to well established methods like Approximate Bayesian Computation (ABC). Even without the expert knowledge of summary statistics, our approach compares fairly well to an ABC based on handcrafted features. Furthermore we show that combining deep learning and ABC can improve performance while taking advantage of both frameworks. Finally, we apply our approach to reconstruct the effective population size history of cattle breed populations.

evolutionary biology↗

bioRxiv2019

Translationally relevant transcriptomic alterations in mouse ischemic cerebral microvessels

Increasing evidence implicates cerebral microvascular dysfunction in the pathophysiology of numerous central nervous system pathologies, including stroke. Understanding the molecular alterations in cerebral microvessels in these conditions will provide original opportunities for scientific investigation at the pre-clinical and clinical levels. In this study, we conducted a novel genome-wide transcriptomic analysis of microvessels in a mouse model of transient focal cerebral ischemia. Using a publicly available human ischemic stroke dataset, we identified shared alterations in our microvessel dataset with implications for human pathophysiology. From this unbiased analysis, we report predicted alterations in inter- and intra-cellular signaling, emphasizing perturbations in genes involved in blood brain barrier function, endothelial cell activation and metabolism. Furthermore, our study unveiled previously unreported gene expression changes associated with altered sphingolipid metabolism. Altogether, our results have identified microvessel-specific transcriptomic changes in a number of translationally relevant pathways that support the targeting of these pathways in preclinical studies. The data shared here provide a resource for future investigation of translationally relevant pathways in ischemic stroke.

neuroscience↗

bioRxiv2019

Genetic engineering of hoxb8 immortalized hematopoietic progenitors: a potent tool to study macrophage tissue migration

Tumor-associated macrophages (TAM) are detrimental in most cancers. Controlling their recruitment is thus potentially therapeutic. We showed that TAM perform the protease-dependent mesenchymal migration in cancer, while macrophages perform amoeboid migration in other tissues. Inhibition of mesenchymal migration correlates with decreased TAM infiltration and tumor growth, providing rationale for a new cancer immunotherapy specifically targeting TAM motility. To identify new effectors of mesenchymal migration, we produced ER-Hoxb8-immortalized hematopoietic progenitors with unlimited proliferative ability. The functionality of macrophages differentiated from ER-Hoxb8 progenitors was compared to bone marrow-derived macrophages (BMDM). They polarized into M1- and M2-orientated macrophages, generated ROS, ingested particles, formed podosomes, degraded the extracellular matrix, adopted amoeboid and mesenchymal migration in 3D, and infiltrated tumor explants ex vivo using mesenchymal migration. We also used the CRISPR/Cas9 system to disrupt gene expression of a known effector of mesenchymal migration, WASP, to provide a proof of concept. We observed impaired podosome formation and mesenchymal migration capacity, thus recapitulating the phenotype of BMDM isolated from Wasp-KO mice. Thus, we validate the use of Hoxb8-macrophages as a potent tool to investigate macrophage functionalities.\n\nSummary statementWe validate the use of ER-Hoxb8-immortalized hematopoietic progenitors combined to CRISPR/Cas9 technology as a potent tool to investigate macrophage functionalities with a large scale of applications.

cell biology↗

bioRxiv2018

Evaluation of S1PR1/pSTAT3 and S1PR2/FOXP1 Expression in Aggressive, Mature B Cell Lymphomas

Aggressive, mature B-cell lymphomas represent a heterogeneous group of diseases including Burkitt Lymphoma (BL), High Grade B Cell Lymphomas (HGBL) (eg, Double-Hit B cell lymphomas (HGBL-DH: HGBL with MYC and BCL2 and/or BCL6 translocations)), HGBL, Not Otherwise Specified (HGBL, NOS) and Diffuse Large B Cell Lymphoma. The overlapping morphologic and immunohistochemical features of these lymphomas may pose diagnostic challenges in some cases, and a better understanding of potential diagnostic biomarkers and possible therapeutic targets is needed. Sphingosine 1 Phosphate Receptors (S1PR1-5) represent a family of G-protein coupled receptors that bind the sphingolipid (S1P) and influence migration and survival pathways in a variety of cell types, including lymphocytes. S1PRs are emerging as biomarkers in B cell biology and interaction between S1PR pathways and STAT3 or FOXP1 has been reported, especially in DLBCL. Our aim was to extend the understanding of the S1PR1, STAT3 and S1PR2, FOXP1 expression beyond DLBCL, into additional aggressive, mature B cell lymphomas such as BL, HGBL-DH and HGBL,NOS.\n\nHerein, we report that S1PR1 and S1PR2 showed different patterns of expression in mantle zones and follicle centers in reactive lymphoid tissue and, among the lymphomas in this study, Burkitt lymphomas showed a unique pattern of expression compared to HGBL and DLBCL. Additionally, we found that S1PR1 and S1PR2 expression was typically mutually exclusive and were expressed in a low proportion of cases (predominantly HGBL involving extranodal sites). Lastly, FOXP1 was expressed in a high proportion of the various case types and pSTAT3 was detected in a significant proportion of HGBL and DLBCL cases. Taken together, these findings provide further evidence that S1PR1, pSTAT3, S1PR2 and FOXP1 play a role in a subset of aggressive mature B cell lymphomas.

pathology↗

bioRxiv2018

Exacerbation of blood brain barrier dysfunction and brain injury after aneurysmal subarachnoid hemorrhage in endothelial specific S1PR1 knock out mice.

Blood brain barrier (BBB) dysfunction upon ischemia and hypoxia has been implicated in the exacerbation of neuronal injury in stroke. Despite the therapeutic potential of the cerebrovascular endothelium, the limited understanding of the endothelial signaling pathways governing BBB function restricts progress towards developing novel therapeutic approaches specifically targeting the endothelium. Sphingosine-1-phosphate (S1P) is a potent modulator of endothelial function via its receptors (S1PR). Recent human and mouse studies indicate that vasoprotective endothelial S1P signaling via S1PR1 may be impaired in cardiovascular and inflammatory diseases. Herein, we investigated the expression of S1PR1 in the mouse and human cerebrovascular endothelium and the role of endothelial-specific S1PR1 signaling in brain injury in a mouse model of aneurysmal subarachnoid hemorrhage (SAH), the most devastating type of stroke. We found that S1PR1 is the most abundant S1PR transcript in the mouse brain and in mouse and human brain endothelial cells (20-100 mRNA copies per cell). S1PR1 transcripts were significantly enriched (~6 fold) in mouse cortical microvessels compared to total brain. Using the S1PR1-eGFP knock in mouse, we found that S1PR1-eGFP is abundantly expressed in the cerebrovascular endothelium in the mouse brain. A similar pattern of expression was observed in human brain samples. Endothelial specific deletion of S1PR1 in adult mice (S1pr1 flox/floxxCdh5-CreERT2, referred to as S1pr1iECKO), resulted in exacerbation of brain edema, neuronal injury and worsened neurological outcomes upon SAH compared to S1pr1 flox/flox littermates. No differences in the subarachnoid blood, hemostasis or cerebral blood flow changes during and after SAH were found between groups. Mechanistically, S1pr1iECKO exhibited aggravated BBB dysfunction and increased phosphorylation of myosin light chain (MLC) in isolated cortical microvessels, a downstream effector of the Rho-ROCK pathway implicated in endothelial inflammation and barrier dysfunction. Taken together, our data indicate that S1PR1 is an endogenous protective signaling pathway in the endothelium, critical to maintain BBB function and to mitigate neuronal injury in pathological conditions. Thus, the therapeutic and diagnostic potential of the endothelial sphingosine-1-phosphate pathway in stroke deserves further study.

neuroscience↗