Biology subjects

Park, C.

Publications and source records attributed to Park, C..

At least 55 records · Page 3Linked to original sources

bioRxiv2024

Aryl-hydrocarbon receptor in smooth muscle cells protect against dioxin induced adverse remodeling of atherosclerosis

IntroductionEnvironmental exposure to dioxin has been linked to increased myocardial infarction. Smooth muscle cells (SMC) in the coronary vasculature play a critical role in atherosclerotic plaque remodeling due to their phenotypic plasticity, however, the detailed mechanism linking dioxin exposure to adverse SMC modulation is not well understood. MethodsSingle-cell RNA and ATAC sequencing and histological analyses were performed on the aorta from mouse models of atherosclerosis exposed to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) or control. Primary human coronary artery SMC (HCASMC) treated in culture with TCDD were used to perform RNA-Seq, ATAC-Seq, and functional phenotypic assays. ChIP-Seq was performed with antibodies against Aryl-hydrocarbon receptor (AHR) and TCF21, two of known SMC modulating transcription factors. ResultsModulated SMC were the most transcriptionally responsive cell type to dioxin in the atherosclerotic aorta. Dioxin accelerated disease phenotype by promoting a modulated SMC phenotype early, resulting in increased lesion size, migration of SMC, and macrophage recruitment to the lesion. We found C3 expressing modulated SMCs to be likely contributing to the increased macrophage recruitment and inflammation. Analysis of the RNA-Seq data from HCASMC treated with TCDD showed differential enrichment of biological pathways related to cell migration, localization, and inflammation. Furthermore, ATAC-Seq data showed a significant activation for pathways regulating vascular development, cell migration, inflammation, and apoptosis. With TCDD treatment, there was also enrichment of AHR ChIP-Seq peaks, while the TCF21 enrichment decreased significantly. The SMC-specific Ahr knockout resulted in increased oxidative stress in SMC, increased lesion size and macrophage content, and loss of SMC lineage cells in the lesion cap when exposed to TCDD, consistent with a more vulnerable plaque phenotype. ConclusionDioxin adversely remodels atherosclerotic plaque by accelerating the SMC- phenotypic modulation, and increasing inflammation and oxidative stress resulting in increased macrophage recruitment and lesion size. Dioxin may adversely affect the SMC phenotype and disease state by affecting the TCF21 occupancy in the open chromatin regions. Furthermore, we observed that SMC-specific deletion of Ahr in mice resulted in worsening of dioxin mediated SMC modulation and atherosclerosis, suggesting that Ahr in SMC confers protection against dioxin by promoting a stable plaque phenotype and reducing dioxin induced oxidative stress. SummaryO_LIExposure to dioxin, an environmental pollutant present in tobacco smoke and air pollution, accelerates smooth muscle cell modulation, and atherosclerosis. C_LIO_LIDioxin exposure leads to inflammatory smooth muscle cell phenotype characterized by complement pathway activation and increased macrophage recruitment to plaque C_LIO_LIAryl-hydrocarbon receptor in SMC protects against oxidative stress, and promotes a stable plaque phenotype C_LI

molecular biology↗

bioRxiv2024

Spatial and Single Cell Mapping of Castleman Disease Reveals Key Stromal Cell Types and Cytokine Pathways

Castleman disease (CD) is inflammatory lymphoproliferative disorder of unclear etiology. To determine the cellular and molecular basis of CD, we analyzed the spatial proteome of 4,485,009 single cells, transcriptome of 50,117 single nuclei, immune repertoire of 8187 single nuclei, and pathogenic mutations in Unicentric CD, idiopathic Multicentric CD, HHV8-associated MCD, and reactive lymph nodes. CD was characterized by increased non-lymphoid and stromal cells that formed unique microenvironments where they interacted with lymphoid cells. Interaction of activated follicular dendritic cell (FDC) cytoplasmic meshworks with mantle zone B cells was associated with B cell activation and differentiation. VEGF, IL-6, MAPK, and extracellular matrix pathways were elevated in stromal cells of CD. CXCL13+ FDCs, PDGFRA+ T-zone reticular cells (TRC), and ACTA2-positive perivascular reticular cells (PRC) were identified as the predominant source of increased VEGF expression and IL-6 signaling in CD. VEGF expression by FDCs was associated with peri-follicular neovascularization. FDC, TRC and PRC of CD activated JAK-STAT, TGF{beta}, and MAPK pathways via ligand-receptor interactions involving collagen, integrins, complement components, and VEGF receptors. T, B and plasma cells were polyclonal but showed class-switched and somatically hypermutated IgG1+ plasma cells consistent with stromal cell-driven germinal center activation. In conclusion, our findings show that stromal cell activation and associated B-cell activation and differentiation, neovascularization and stromal remodeling underlie CD and suggest new targets for treatment. Key pointsO_LICastleman Disease is characterized by activation and proliferation of CXCL13+ FDCs, PDGFRA+ reticular cells, and ACTA2-positive PRCs. C_LIO_LIVEGF and IL-6 from lymph node stromal cells are associated with B-cell activation and differentiation, endothelial proliferation, and inflammation in CD C_LI

pathology↗

bioRxiv2024

Acute inhibition of iron-sulfur cluster biosynthesis disrupts metabolic flexibility in mice

Iron-sulfur clusters (ISCs) are cell-essential cofactors present in [~]60 proteins including subunits of OXPHOS complexes I-III, DNA polymerases, and iron-sensing proteins. Dysfunctions in ISC biosynthesis are associated with anemias, neurodegenerative disorders, and metabolic diseases. To assess consequences of acute ISC inhibition in a whole body setting, we developed a mouse model in which key ISC biosynthetic enzyme NFS1 can be acutely and reversibly suppressed. Contrary to in vitro ISC inhibition and pharmacological OXPHOS suppression, global NFS1 inhibition rapidly enhances lipid utilization and decreases adiposity without affecting caloric intake and physical activity. ISC proteins decrease, including key proteins involved in OXPHOS (SDHB), lipoic acid synthesis (LIAS), and insulin mRNA processing (CDKAL1), causing acute metabolic inflexibility. Age-related metabolic changes decelerate loss of adiposity substantially prolonged survival of mice with NFS1 inhibition. Thus, the observation that ISC metabolism impacts organismal fuel choice will aid in understanding the mechanisms underlying ISC diseases with increased risk for diabetes. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/608291v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@863cbaorg.highwire.dtl.DTLVardef@fce90borg.highwire.dtl.DTLVardef@27df04org.highwire.dtl.DTLVardef@1a2a9bf_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Acute ISC inhibition leads to rapid loss of adiposity in mice - Multi-metabolic pathway disruption upon ISC deficiency blocks energy storage - Nfs1 inhibition induces glucose dyshomeostasis due to ISC deficiency in {beta}-cells - Energy distress caused by inhibition of ISC synthesis is attenuated in aged mice

physiology↗

bioRxiv2024

Autophagy-mediated CTR1 turnover orchestrates the reciprocal interaction between autophagy and ethylene signaling

The phytohormone ethylene and autophagy are crucial for plant adaptation to various environmental stresses, yet the integration of these signaling networks into stress responses is not fully understood. Here, we report that ethylene signaling and autophagy reciprocally regulate each other through Constitutive Triple Response 1 (CTR1), a negative regulator of ethylene signaling. Autophagy facilitates the turnover of the CTR1 protein, which interacts with the key autophagy-related protein ATG8 as autophagic cargo. Impaired autophagy attenuates ethylene responses. Conversely, ethylene-insensitive mutants exhibit enhanced autophagic flux, while a constitutive ethylene response mutant is hypersensitive to carbon starvation stress, which induces autophagy. This suggests that ethylene suppresses autophagy during carbon limitation. We further elucidated that ethylene receptors with a receiver domain play a primary role in modulating autophagy, while receptor kinase activity is not essential. Our findings uncover that the autophagic control of CTR1 degradation allows reciprocal cross-regulation between autophagy and ethylene transduction cascades, optimizing stress responses and resilience.

plant biology↗

bioRxiv2024

Molecular basis for the host range function of the poxvirus PKR inhibitor E3

The antiviral protein kinase R (PKR) is activated by viral double-stranded RNA and phosphorylates translation initiation factor eIF2, thereby inhibiting translation and virus replication. Most poxviruses contain two PKR inhibitors, called E3 and K3 in vaccinia virus (VACV), which are determinants of viral host range. The prevailing model for E3 function is that it inhibits PKR through the non-specific sequestration of double-stranded (ds) RNA. Our data revealed that Syrian hamster PKR was resistant to E3, which is at odds with the sequestration model. However, Syrian hamster PKR was still sensitive to K3 inhibition. In contrast, Armenian hamster PKR showed opposite sensitivities, being sensitive to E3 and resistant to K3 inhibition. Mutational analyses of hamster PKRs showed that sensitivity to E3 inhibition was largely determined by the region linking the dsRNA-binding domains and the kinase domain of PKR, whereas two amino acid residues in the kinase domain (helix G) determined sensitivity to K3. Expression of PKRs in congenic cells showed that Syrian hamster PKR containing the two Armenian hamster PKR residues in helix-G was resistant to wild type VACV infection, and that cells expressing either hamster PKR recapitulated the phenotypes observed in species-derived cell lines. The observed resistance of Syrian hamster PKR to E3 explains its host range function and challenges the paradigm that dsRNA-binding PKR inhibitors mainly act by the sequestration of dsRNA. SignificanceThe molecular mechanisms that govern the host range of viruses are incompletely understood. A small number of poxvirus genes have been identified that influence the host range of poxviruses. We show that the host range functions of E3 and K3, two host range factors from vaccinia virus, are a result of species-specific interactions with the antiviral protein kinase R (PKR) and that PKR from closely related species displayed dramatic differences in their sensitivities to these viral inhibitors. While there is a substantial body of work demonstrating host-specific interactions with K3, the current model for E3-mediated PKR inhibition is that E3 non-specifically sequesters dsRNA to prevent PKR activation. This model does not predict species-specific sensitivity to E3; therefore, our data suggest that the current model is incomplete, and that dsRNA sequestration is not the primary mechanism for E3 activity.

microbiology↗

bioRxiv2024

Native Korean wild mice (Mus musculus): molecular phylogeny and morphometrics

Taxonomic status of house mice in the Korean Peninsula remains poorly understood. Here, we analyze genetic and morphological characteristics of mice from Korea and evaluate their phylogenetic relationships to the well-known primary subspecies. Using a comprehensive set of publicly available genetic data (mtDNA cytb gene), Korean mice including our specimens from islands, mountains, and agricultural fields were identified to Mus mus musculus. External morphology, such as tail ratios of our specimens, resembled previously assigned subspecies (e.g., M. m. molossinus, M. m. utsuryonis, and M. m. yamashinai), suggesting a single subspecific group within M. m. musculus. Korean mice displayed a distinctive landmark configuration around the snout, with a relatively short and slender premaxillary tooth-patch width (PMXW) and a larger maxillary tooth-row length (MXTL) compared to laboratory strains derived from M. m. domesticus. Our investigation provides insights into the phylogenetic relationships and taxonomic status of Korean mice relative to the primary lineages of M. musculus subspecies. Understanding the evolutionary history of Korean M. m. musculus sheds new light on how their spatiotemporal dynamics led to diversification, with the Korean Peninsula serving as an ecological bridge between East Eurasia and neighboring regions.

zoology↗

bioRxiv2024

Inference of Causal Interaction Networks of Gut Microbiota Using Transfer Entropy

Understanding the complex dynamics of gut microbiota interactions is essential for unraveling their influence on human health. In this study, we employed transfer entropy analysis to construct a causal interaction network among gut microbiota genera from the time-series data of bacterial abundances. Based on the longitudinal microbiome data from two subjects, we found that the constructed gut microbiota regulatory networks exhibited power-law degree distribution, intermediate modularity, and enrichment of feedback loops. Interestingly, the networks of the two subjects displayed differential enrichment of feedback loops, which may be associated with the differential recovery dynamics of the two subjects. In summary, the transfer entropy-based network construction provides us with valuable insights into the ecosystem of gut microbiota and allows us to identify key microbial hubs that play pivotal roles in shaping the microbial balances.

systems biology↗

bioRxiv2024

Iterative in silico identification of P-glycoprotein inhibitors

Overexpression of the polyspecific efflux transporter, P-glycoprotein (P-gp, MDR1, ABCB1), is a major mechanism by which cancer cells acquire multidrug resistance (MDR), the resistance to diverse chemotherapeutic drugs. Inhibiting drug transport by P-gp can resensitize cancer cells to chemotherapy, but there are no P-gp inhibitors available to patients. Clinically unsuccessful P-gp inhibitors tend to bind at the pumps transmembrane drug binding domains and are often P-gp transport substrates, resulting in lowered intracellular concentration of the drug and altered pharmacokinetics. In prior work, we used computationally accelerated drug discovery to identify novel P-gp inhibitors that target the pumps cytoplasmic nucleotide binding domains. Our first-draft study provided conclusive evidence that the nucleotide binding domains of P-gp are viable targets for drug discovery. Here we develop an enhanced, computationally accelerated drug discovery pipeline that expands upon our prior work by iteratively screening compounds against multiple conformations of P-gp with molecular docking. Targeted molecular dynamics simulations with our homology model of human P-gp were used to generate docking receptors in conformations mimicking a putative drug transport cycle. We offset the increased computational complexity using custom Tanimoto chemical datasets, which maximize the chemical diversity of ligands screened by docking. Using our expanded, virtual-assisted pipeline, we identified nine novel P-gp inhibitors that reverse MDR in two types of P-gp overexpressing human cancer cell lines, reflecting a 13.4% hit rate. Of these inhibitors, all were non-toxic to non-cancerous human cells, and six were not likely to be transport substrates of P-gp. Our novel P-gp inhibitors are chemically diverse and are good candidates for lead optimization. Our results demonstrate that the nucleotide binding domains of P-gp are an underappreciated target in the effort to reverse P-gp-mediated multidrug resistance in cancer.

cancer biology↗

bioRxiv2024

Coordinated Immune Cell Networks in the Bone Marrow Microenvironment Define the Graft versus Leukemia Response with Adoptive Cellular Therapy

Understanding how intra-tumoral immune populations coordinate to generate anti-tumor responses following therapy can guide precise treatment prioritization. We performed systematic dissection of an established adoptive cellular therapy, donor lymphocyte infusion (DLI), by analyzing 348,905 single-cell transcriptomes from 74 longitudinal bone-marrow samples of 25 patients with relapsed myeloid leukemia; a subset was evaluated by protein-based spatial analysis. In acute myelogenous leukemia (AML) responders, diverse immune cell types within the bone-marrow microenvironment (BME) were predicted to interact with a clonally expanded population of ZNF683+GZMB+ CD8+ cytotoxic T lymphocytes (CTLs) which demonstrated in vitro specificity for autologous leukemia. This population, originating predominantly from the DLI product, expanded concurrently with NK and B cells. AML nonresponder BME revealed a paucity of crosstalk and elevated TIGIT expression in CD8+ CTLs. Our study highlights recipient BME differences as a key determinant of effective anti-leukemia response and opens new opportunities to modulate cell-based leukemia-directed therapy.

cancer biology↗

bioRxiv2024

Regulatory role of cholesterol in modulating actin dynamics and cell adhesive interactions in the trabecular meshwork

The trabecular meshwork (TM) tissue plays a crucial role in maintaining intraocular pressure (IOP) homeostasis. Increased TM contractility and stiffness are directly correlated with elevated IOP. Although cholesterol is known to be a determinant of glaucoma occurrence and elevated IOP, the underlying mechanisms remain elusive. In this study, we used human TM (HTM) cells to unravel the effects of cholesterol on TM stiffness. We achieved this by performing acute cholesterol depletion with Methyl-{beta}-cyclodextrin (M{beta}CD) and cholesterol enrichment/replenishment with M{beta}CD cholesterol complex (CHOL). Interestingly, cholesterol depletion triggered notable actin depolymerization and decreased focal adhesion formation, while enrichment/replenishment promoted actin polymerization, requiring the presence of actin monomers. Using a specific reporter of phosphatidylinositol 4,5-bisphosphate (PIP2), we demonstrated that cholesterol depletion decreases PIP2 levels on the cell membrane, whereas enrichment increases them. Given the critical role of PIP2 in actin remodeling and focal adhesion formation, we postulate that cholesterol regulates actin dynamics by modulating PIP2 levels on the membrane. Furthermore, we showed that cholesterol levels regulate integrin 5{beta}1 and V{beta}3 distribution and activation, subsequently altering cell-extracellular matrix (ECM) interactions. Notably, the depletion of cholesterol, as a major lipid constituent of the cell membrane, led to a decrease in HTM cell membrane tension, which was reversed upon cholesterol replenishment. Overall, our systematic exploration of cholesterol modulation on TM stiffness highlights the critical importance of maintaining appropriate membrane and cellular cholesterol levels for achieving IOP homeostasis.

cell biology↗

bioRxiv2023

DIISCO: A Bayesian framework for inferring dynamic intercellular interactions from time-series single-cell data

Characterizing cell-cell communication and tracking its variability over time is essential for understanding the coordination of biological processes mediating normal development, progression of disease, or responses to perturbations such as therapies. Existing tools lack the ability to capture time-dependent intercellular interactions, such as those influenced by therapy, and primarily rely on existing databases compiled from limited contexts. We present DIISCO, a Bayesian framework for characterizing the temporal dynamics of cellular interactions using single-cell RNA-sequencing data from multiple time points. Our method uses structured Gaussian process regression to unveil time-resolved interactions among diverse cell types according to their co-evolution and incorporates prior knowledge of receptor-ligand complexes. We show the interpretability of DIISCO in simulated data and new data collected from CAR-T cells co-cultured with lymphoma cells, demonstrating its potential to uncover dynamic cell-cell crosstalk. AvailabilityDIISCO is publicly accessible at https://github.com/azizilab/DIISCO_public. All data will be deposited to GEO upon publication.

bioinformatics↗

bioRxiv2023

Plasma cell differentiation, antibody quality, and initial germinal center B cell population depend on glucose influx rate

Antibody secretion into sera, selection for higher affinity BCR, and the generation of higher Ab affinities are important elements of immune response optimization, and a core function of germinal center reactions. B cell proliferation requires nutrients to support the anabolism inherent in clonal expansion. Glucose usage by GC B cells has been reported to contribute little to their energy needs, with questions raised as to whether or not glucose uptake or glycolysis increases in GC B cells compared to their naive precursors. Indeed, metabolism can be highly flexible, such that supply shortage along one pathway may be compensated by increased flux on others. We now show that elimination of the glucose transporter GLUT1 after establishment of a pre-immune B cell repertoire, even after initiation of the GC B cell gene expression program, decreased initial GC B cell population numbers, affinity maturation, and PC outputs. Glucose oxidation was heightened in GC B cells, but this hexose flowed more into the pentose phosphate pathway (PPP), whose activity was important in controlling reactive oxygen (ROS) and ASC production. In modeling how glucose usage by B cells promotes the Ab response, the control of ROS appeared insufficient. Surprisingly, the combination of galactose, which mitigated ROS, with provision of mannose - an efficient precursor to glycosylation - supported robust production of and normal Ab secretion by ASC under glucose-free conditions. Collectively, the findings indicate that GC depend on normal glucose influx, especially in PC production, but reveal an unexpected metabolic flexibility in hexose requirements. KEY POINTSO_LIGlucose influx is critical for GC homeostasis, affinity maturation and the generation of Ab-secreting cells. C_LIO_LIPlasma cell development uses the Pentose Phosphate Pathway, and hexose sugars maintain redox homeostasis. C_LIO_LIPCs can develop and achieve robust Ab secretion in the absence of glucose using a combination of hexose alternatives. C_LI

immunology↗

bioRxiv2023

A cerebellar disinhibitory circuit supports synaptic plasticity

How does the cerebellum learn how to control motion? The cerebellar motor learning critically depends on the long-term depression of the synapses between granule cells and Purkinje cells, which encode motor commands and inhibitory modifications to motor outputs, respectively, for simultaneous granule cell inputs and climbing fibre inputs, the latter of which encode the error signals1-3. However, recent studies have revealed that inhibitory inputs to Purkinje cells may disrupt long-term depression4-8, and it is not clear how long-term depression can occur without disruption. In search of a clue, we investigated the synaptic connectivity among the neurons reconstructed from serial electron microscopy images of the cerebellar molecular layer9,10. We discovered synapses between climbing fibres and a subset of inhibitory interneurons, which synapse onto the remaining interneurons, which in turn synapse onto Purkinje cells. Such connectivity redefines the interneuron types, which have been defined morphologically or molecularly11-13. Together with climbing fibres to Purkinje cell connections, those cell types form a feedforward disinhibitory circuit14. We argued that this circuit secures long-term depression by suppressing inhibition whenever climbing fibre input is provided and long-term depression needs to occur15, and we validated the hypothesis through a computational model. This finding implies a general principle of circuit mechanism in which disinhibition supports synaptic plasticity16,17.

neuroscience↗

bioRxiv2023

Thyroid hormone rewires cortical circuits to coordinate body-wide metabolism and exploratory drive

Animals adapt to varying environmental conditions by modifying the function of their internal organs, including the brain. To be adaptive, alterations in behavior must be coordinated with the functional state of organs throughout the body. Here we find that thyroid hormone-- a prominent regulator of metabolism in many peripheral organs-- activates cell-type specific transcriptional programs in anterior regions of cortex of adult mice via direct activation of thyroid hormone receptors. These programs are enriched for axon-guidance genes in glutamatergic projection neurons, synaptic regulators across both astrocytes and neurons, and pro-myelination factors in oligodendrocytes, suggesting widespread remodeling of cortical circuits. Indeed, whole-cell electrophysiology recordings revealed that thyroid hormone induces local transcriptional programs that rewire cortical neural circuits via pre-synaptic mechanisms, resulting in increased excitatory drive with a concomitant sensitization of recruited inhibition. We find that thyroid hormone bidirectionally regulates innate exploratory behaviors and that the transcriptionally mediated circuit changes in anterior cortex causally promote exploratory decision-making. Thus, thyroid hormone acts directly on adult cerebral cortex to coordinate exploratory behaviors with whole-body metabolic state.

neuroscience↗

bioRxiv2023

CDDO-Methyl Ester Inhibits BRAF Inhibitor Resistance and Remodels the Myeloid Compartment in BRAF-mutant Melanoma

Approximately 50% of advanced melanomas harbor activating BRAFV600E mutations that are sensitive to BRAF inhibition. However, the duration of the response to BRAF inhibitors (BRAFi) has been limited due to the development of acquired resistance, which is preceded by recruitment of immunosuppressive myeloid cells and regulatory T cells (Tregs). While the addition of MAPK/ERK kinase 1 inhibitors (MEKi) prolongs therapeutic response to BRAF inhibition, most patients still develop resistance. Using a BrafV600E/+/Pten-/- graft mouse model of melanoma, we now show that the addition of the methyl ester of the synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (C-Me) to the BRAFi vemurafenib analog PLX4720 at resistance significantly reduces tumor burden. Dual treatment remodels the BRAFi resistant-tumor microenvironment (TME), reducing infiltration of Tregs and tumor associated macrophages (TAMs), and attenuates immunosuppressive cytokine production. For the first time, we characterize myeloid populations using scRNA-seq in BRAFi-resistant tumors and demonstrate that restoration of therapeutic response is associated with significant changes in immune-activated myeloid subset representation. Collectively, these studies suggest that C-Me inhibits acquired resistance to BRAFi. Use of C-Me in combination with other therapies may both inhibit melanoma growth and enhance therapeutic responsiveness more broadly.

immunology↗

bioRxiv2023

SARS-CoV-2 Spike Protein Reduces Burst Activities in Neurons Measured by Micro-Electrode Arrays

SARS-CoV-2 caused a large-scale global pandemic between 2020 and 2022. Despite efforts to understand its biology and mechanisms of pathogenicity, the viral impact on the neurological systems remains unclear. The main goal of this study was to quantify the neurological phenotypes induced by SARS-CoV-2 spike protein in neurons, measured by in-vitro multi-well micro-electrode arrays (MEAs). We extracted the whole-brain neurons from the newborn P1 mice and plated them on multi-well micro-electrode arrays and administered purified recombinant spike proteins (S1 and S2 subunits respectively) from the SARS-CoV-2 virus. The signals from the MEAs were transmitted from an amplifier to a high-performance computer for recording and analysis. We used an in-house developed algorithm to quantify neuronal phenotypes. Among all the phenotypic features analyzed, we discovered that the S1 protein of SARS-CoV-2 decreased the mean burst numbers observed on each electrode; This effect was not observed for the spike 2 protein (S2) and could be rescued by an anti-S1 antibody. Finally, our data strongly suggest that the receptor binding domain (RBD) of S1 is responsible for the reduction of burst activities in neurons. Overall, our results strongly indicate that spike proteins may play an important role in altering neuronal phenotypes, specifically the burst patterns, when neurons are exposed during early development.

microbiology↗

bioRxiv2023

Exogenous TGFβ1 and its mimic HpTGM attenuate the heart's inflammatory response to ischaemic injury and improve long term cardiac outcomes

RationaleSuccessful and timely coronary reperfusion following acute ST-elevation myocardial infarction (STEMI) is standard therapy to salvage transiently ischaemic heart muscle. However, the subsequent inflammatory response within the infarct can lead to further loss of viable myocardium. Robust interventions are required in the acute MI setting to minimise cardiac injury and reduce risk of further detrimental progression. ObjectiveTGF{beta}1 is an anti-inflammatory cytokine released endogenously in response to infection or tissue injury. The goal of this study was to investigate its protective effects when given exogenously following myocardial infarction. Methods and ResultsTGF{beta}1 is found at increased levels in the blood of STEMI patients immediately following myocardial infarction. We observe a significant correlation (p=0.003) between higher circulating TGF{beta}1 levels at 24h post MI and a reduction in infarct size over the following 3 months, suggesting that an early increase in circulating TGF{beta}1 is protective in these patients. Using a mouse model of cardiac ischaemia-reperfusion we demonstrate that additional exogenous TGF{beta}1 delivered in the acute setting has multiple beneficial outcomes. At 24 hours post-reperfusion It leads to a significantly smaller infarct size (30% reduction, p=0.025), reduced inflammatory infiltrate (28% reduction, p=0.015), lower intra-cardiac expression of inflammatory cytokines IL1{beta} and CCL2 (>50 % reduction, p=0.038 and 0.0004, respectively) and reduced scar size at 4 weeks (21% reduction, p=0.015). Furthermore exogenous delivery of an equivalent dose of HpTGM, a recently described low-fibrogenic mimic of TGF{beta}1, secreted by a helminth parasite to evade immune rejection, has an almost identical protective effect on injured mouse hearts. Furthermore using a genetic approach we show the benefit is mediated by the vascular endothelium. ConclusionsThis work reveals the potential of exogenous TGF{beta}1 and HpTGM delivered in the acute MI setting to provide protective anti-inflammatory effects and reduce infarct size, leading to a smaller scar and reduced detrimental progression.

pathology↗

bioRxiv2023

Stricturing Crohn's disease single-cell RNA sequencing reveals fibroblast heterogeneity and intercellular interactions

BackgroundFibroblasts play a key role in stricture formation in Crohns disease (CD) but understanding its pathogenesis requires a systems-level investigation to uncover new treatment targets. We studied full thickness CD tissues to characterize fibroblast heterogeneity and function by generating the first single cell RNA sequencing (scRNAseq) atlas of strictured bowel and providing proof of principle for therapeutic target validation. MethodsWe performed scRNAseq of 13 fresh full thickness CD resections containing non-involved, inflamed non-strictured, and strictured segments as well as 7 normal non-CD bowel segments. Each segment was separated into mucosa/submucosa or muscularis propria and analyzed separately for a total of 99 tissue samples and 409,001 cells. We validated cadherin-11 (CDH11) as a potential therapeutic target by using whole tissues, isolated intestinal cells, NanoString nCounter, next generation sequencing, proteomics and animal models. ResultsOur integrated dataset revealed fibroblast heterogeneity in strictured CD with the majority of stricture-selective changes detected in the mucosa/submucosa, but not the muscle layer. Cell-cell interaction modeling revealed CXCL14+ as well as MMP/WNT5A+ fibroblasts displaying a central signaling role in CD strictures. CDH11, a fibroblast cell-cell adhesion molecule, was broadly expressed and upregulated, and its pro-fibrotic function was validated by NanoString nCounter, RNA sequencing, tissue target expression, in vitro gain- and loss-of-function experiments, proteomics, and two animal models of experimental colitis. ConclusionA full-thickness bowel scRNAseq atlas revealed previously unrecognized fibroblast heterogeneity and interactions in CD strictures and CDH11 was validated as a potential therapeutic target. These results provide a new resource for a better understanding of CD stricture formation and opens potential therapeutic developments.

immunology↗