Biology subjects

Lee, M.

Publications and source records attributed to Lee, M..

At least 145 records · Page 8Linked to original sources

bioRxiv2023

Interleukin 11 therapy causes acute heart failure and its use in patients should be reconsidered

BackgroundInterleukin 11 (IL11) was initially thought important for platelet production, which led to recombinant IL11 being developed as a drug to treat thrombocytopenia. IL11 was later found to be redundant for haematopoiesis and its use in patients is associated with unexplained cardiac side effects. Here we identify previously unappreciated and direct cardiomyocyte toxicities associated with IL11 therapy. MethodsWe injected recombinant mouse lL11 (rmIL11) into mice and studied its molecular effects in the heart using immunoblotting, qRT-PCR, bulk RNA-seq, single nuclei RNA-seq (snRNA-seq) and ATAC-seq. The physiological impact of IL11 was assessed by echocardiography in vivo and using cardiomyocyte contractility assays in vitro. To determine the activity of IL11 specifically in cardiomyocytes we made two cardiomyocyte-specific Il11ra1 knockout mouse models using either AAV9-mediated and Tnnt2-restricted (vCMKO) or Myh6 (m6CMKO) Cre expression and an Il11ra1 floxed mouse strain. In pharmacologic studies, we studied the effects of JAK/STAT inhibition on rmIL11-induced cardiac toxicities. ResultsInjection of rmIL11 caused acute and dose-dependent impairment of left ventricular ejection fraction (saline (2 {micro}L/kg), 60.4%{+/-}3.1; rmIL11 (200 mcg/kg), 31.6%{+/-}2.0; p<0.0001, n=5). Following rmIL11 injection, myocardial STAT3 and JNK phosphorylation were increased and bulk RNA-seq revealed upregulation of pro-inflammatory pathways (TNF, NF{kappa}B and JAK/STAT) and perturbed calcium handling. SnRNA-seq showed rmIL11-induced expression of stress factors (Ankrd1, Ankrd23, Xirp2), activator protein-1 (AP-1) transcription factor genes and Nppb in the cardiomyocyte compartment. Following rmIL11 injection, ATAC-seq identified epigenetic enrichment of the Ankrd1 and Nppb genes and stress-responsive, AP-1 transcription factor binding sites. Cardiomyocyte-specific effects were examined in vCMKO and m6CMKO mice, which were both protected from rmIL11-induced left ventricular impairment and molecular pathobiologies. In mechanistic studies, inhibition of JAK/STAT signalling with either ruxolitinib or tofacitinib prevented rmIL11-induced cardiac dysfunction. ConclusionsInjection of IL11 directly activates JAK/STAT3 in cardiomyocytes to cause acute heart failure. Our data overturn the earlier assumption that IL11 is cardioprotective and explain the serious cardiac side effects associated with IL11 therapy, which questions its continued use in patients. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIInjection of IL11 to mice causes acute and dose-dependent left ventricular impairment C_LIO_LIIL11 activates JAK/STAT3 in cardiomyocytes to cause cell stress, inflammation and impaired calcium handling C_LIO_LIThese data identify, for the first time, that IL11 is directly toxic in cardiomyocytes, overturning the earlier literature that suggested the opposite C_LI What are the clinical implications?O_LIRecombinant human IL11 (rhIL11) is used as a drug to increase platelets in patients with thrombocytopenia but this has severe and unexplained cardiac side effects C_LIO_LIWe show that IL11 injection causes cardiomyocyte dysfunction and heart failure, which explains its cardiac toxicities that were previously thought non-specific C_LIO_LIThese findings have immediate translational implications as they question the continued use of rhIL11 in patients around the world C_LI

molecular biology↗

bioRxiv2023

Virtual biomarkers: predicting immune status using label-free holotomography of individual human monocytes and machine learning analysis

Precise evaluation of immune status is critical for managing diseases such as sepsis, in which the immune system transitions between hyper-inflammatory and immune-suppressed states. However, current biomarkers are limited by low specificity and time-consuming protocols. Here, we present a label-free, imaging-based framework for single-cell immune profiling of human monocytes using three-dimensional holotomography (HT) and deep learning. HT captures subcellular refractive index (RI) distributions of live, unlabeled cells, enabling quantitative extraction of morphological and biophysical features. Using an in vitro LPS-based model, we classified three functional immune states--control, hyper-inflammation, and immune suppression--based on 4,059 holotomograms from 11 donors. Immune state transitions were associated with significant changes in cell volume, surface area, RI variability, and the abundance of lipid droplets. A 3D convolutional neural network trained on HT images achieved 83.7% accuracy for single-cell predictions, increasing to 99.9% with ensemble averaging. This study establishes HT as a scalable, label-free platform for real-time immune monitoring and introduces subcellular RI features as robust correlates of immune dysregulation.

immunology↗

bioRxiv2023

Unilateral ephaptic program underlying sweetness dominance

In ephaptic coupling, physically adjacent neurons influence one anothers activity via the electric fields they generate. To date, the molecular mechanisms that mediate and modulate ephaptic couplings effects remain poorly understood. Here, we show that the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel lateralizes the potentially mutual ephaptic inhibition between Drosophila gustatory receptor neurons (GRNs). While sweet-sensing GRNs (sGRNs) engage in ephaptic suppression of the adjacent bitter-sensing GRNs (bGRNs), HCN expression in sGRNs enables them to resist ephaptic suppression from the bGRNs. Such one-sided ephaptic inhibition confers sweetness dominance, facilitating ingestion of bitter-laced sweets. Flies with HCN-deficient sGRNs exhibited dramatically decreased attraction to sucrose mixed with moderate levels of caffeine, highlighting the behavioral significance that gustatory ephaptic inhibition promotes ingestion of carbohydrates buried in bitterness. Our findings indicate a role for the gating of ephaptic coding to ensure the intake of the essential nutrient despite bitter contaminants present in the feeding niche of Drosophila, as the gating establishes a hierarchy of gustatory neuron excitation. Such refinement provides a previously unappreciated mechanism for controlling the activity of a neuronal network with potential implications in the mammalian brain, given the evolutionary conservation of the HCN genes.

neuroscience↗

bioRxiv2023

A patchwork pathway for catabolism of the sulfosugar sulfofucose

The rare sulfosugar sulfofucose (6-deoxy-6-sulfo-D-galactose) is catabolized by Paracoccus wurundjeri sp. nov. strain Merri via a novel tandem pathway that couples sulfofucolytic and sulfolactate sulfolyase reactions. We isolated P. wurundjeri from soil and demonstrated its ability to utilize SFuc as the sole carbon source, leading to complete degradation of sulfofucose and release of sulfite. Proteomics and metabolomics analysis revealed a sulfofucolytic variant of the Entner-Doudoroff (ED) pathway, wherein sulfofucose is converted to sulfolactaldehyde through oxidation, lactone hydrolysis, dehydration and retro-aldol steps. The sulfolactaldehyde is subsequently degraded to pyruvate and sulfite via a downstream biomineralization pathway involving sulfolactate as an intermediate. In vitro reconstitution of the key enzymatic steps validated the pathway, identifying four enzymes: SfcH (dehydrogenase), SfcD (lactonase), SfcF (dehydratase), and SfcE (aldolase), that collectively convert sulfofucose to sulfolactaldehyde and pyruvate. Our findings provide insight into microbial utilization of rare sulfosugars and expand the known metabolic versatility of the genus Paracoccus. ImportanceSulfosugars, such as sulfoquinovose, are integral to the global sulfur cycle, but the metabolism of rarer sulfosugars, like sulfofucose, remains poorly understood. This study identifies a unique bacterial catabolic pathway for sulfofucose degradation, comprising a sulfofucolytic ED pathway followed by biomineralization to sulfite. The identification of this tandem pathway highlights the metabolic flexibility of bacteria to adapt carbohydrate catabolic pathways for processing structurally similar sulfosugars. This work sheds light on the ecological role of sulfofucose metabolism and broadens our understanding of bacterial sulfur metabolism, offering potential implications for biogeochemical sulfur cycling and biotechnological applications.

microbiology↗

bioRxiv2023

In vivo single-cell CRISPR uncovers distinct TNF-alphaprograms in clonal expansion and tumorigenesis

The tumor evolution model posits that malignant transformation is preceded by randomly distributed driver mutations in cancer genes, which cause clonal expansions in phenotypically normal tissues. Although clonal expansions occur frequently in human epithelia and can remodel almost entire tissues, the mechanisms behind why only a small number of clones transform into malignant tumors remain enigmatic. Here, we develop an in vivo single-cell CRISPR strategy to systematically investigate tissue-wide clonal dynamics of the 150 most frequently mutated squamous cell carcinoma genes. We couple ultrasound-guided in utero lentiviral microinjections, single-cell RNA sequencing, guide capture and spatial transcriptomics to longitudinally monitor cell type-specific clonal expansions, document their underlying gene programs and contrast clonal expansions from tumor initiation. We uncover a TNF- signaling module that acts as a generalizable driver of clonal expansions in epithelial tissues. Conversely, during tumorigenesis, the TNF- signaling module is downregulated, and instead, we identify a subpopulation of invasive cancer cells that switch to an autocrine TNF- gene program. By analyzing clonally expanded perturbations and their frequency in tumors, we demonstrate that the autocrine TNF- gene program is associated with epithelial-mesenchymal transition (EMT) and is preexistent in a subpopulation of expanded epidermal stem cells, contributing to the predisposition for tumor initiation. Finally, we provide in vivo evidence that the epithelial TNF- gene program is sufficient to mediate invasive properties of epidermal stem cells and show that the TNF- signature correlates with shorter overall survival in human squamous cell carcinoma patients. Collectively, our study demonstrates the power of applying in vivo single-cell CRISPR screening to mammalian tissues and unveils distinct TNF- programs in tumor evolution. Understanding the biology of clonal expansions in phenotypically normal epithelia and the mechanisms governing their transformation will guide the development of novel strategies for early cancer detection and therapy.

cancer biology↗

bioRxiv2023

Cardiomyocyte-restricted expression of IL11 causes cardiac fibrosis, inflammation, and dysfunction.

AbstractBackground: Cardiac fibrosis is a common pathological process in heart disease and represents a therapeutic target. TGF{beta} is the canonical driver of cardiac fibrosis and was recently shown to be dependent on IL11 for its profibrotic effects in fibroblasts. In the opposite direction, recombinant human IL11 has been reported as anti-fibrotic and also anti- inflammatory in the mouse heart. Objectives: In this study, we determined the effects of IL11 expression in cardiomyocytes on cardiac pathobiology and function. Methods: We used the Cre-loxP system to generate a tamoxifen-inducible mouse with cardiomyocyte-restricted murine Il11 expression. Using protein assays, bulk RNA-sequencing, and in vivo imaging we analysed the effects of IL11 on myocardial fibrosis, inflammation and cardiac function and challenge previous reports suggesting cardioprotective potential of IL11. Results: TGF{beta} stimulation of cardiomyocytes caused Il11 upregulation. As compared to wild-type controls, Il11 expressing hearts demonstrated severe cardiac fibrosis and inflammation that was associated with the upregulation of cytokines, chemokines, complement factors and increased inflammatory cells. IL11 expression also activated a programme of endothelial-to- mesenchymal transition and resulted in left ventricular dysfunction. Conclusion: Our data define species matched IL11 as strongly profibrotic and proinflammatory when secreted from cardiomyocytes and further establish IL11 as a disease factor.

molecular biology↗

bioRxiv2023

DNA repair and anti-cancer mechanisms in the longest-living mammal: the bowhead whale

At over 200 years, the maximum lifespan of the bowhead whale exceeds that of all other mammals. The bowhead is also the second-largest animal on Earth, reaching over 80,000 kg1. Despite its very large number of cells and long lifespan, the bowhead is not highly cancer-prone, an incongruity termed Petos Paradox2. This phenomenon has been explained by the evolution of additional tumor suppressor genes in other larger animals, supported by research on elephants demonstrating expansion of the p53 gene3-5. Here we show that bowhead whale fibroblasts undergo oncogenic transformation after disruption of fewer tumor suppressors than required for human fibroblasts. However, analysis of DNA repair revealed that bowhead cells repair double strand breaks (DSBs) and mismatches with uniquely high efficiency and accuracy compared to other mammals. The protein CIRBP, implicated in protection from genotoxic stress, was present in very high abundance in the bowhead whale relative to other mammals. We show that CIRBP and its downstream protein RPA2, also present at high levels in bowhead cells, increase the efficiency and fidelity of DNA repair in human cells. These results indicate that rather than possessing additional tumor suppressor genes as barriers to oncogenesis, the bowhead whale relies on more accurate and efficient DNA repair to preserve genome integrity. This strategy which does not eliminate damaged cells but repairs them may be critical for the long and cancer-free lifespan of the bowhead whale.

cancer biology↗

bioRxiv2023

Discovery of GS-5245 (Obeldesivir), an Oral Prodrug of Nucleoside GS-441524 that Exhibits Antiviral Efficacy in SARS-CoV-2 Infected African Green Monkeys

Remdesivir 1 is an amidate prodrug that releases the monophosphate of nucleoside GS-441524 (2) into lung cells thereby forming the bioactive triphosphate 2-NTP. 2-NTP, an analog of ATP, inhibits the SARS-CoV-2 RNA-dependent RNA polymerase replication and transcription of viral RNA. Strong clinical results for 1 have prompted interest in oral approaches to generate 2-NTP. Here we describe the discovery of a 5-isobutyryl ester prodrug of 2 (GS-5245, Obeldesivir, 3) that has low cellular cytotoxicity and three to seven-fold improved oral delivery of 2 in monkeys. Prodrug 3 is cleaved pre-systemically to provide high systemic exposures of 2 that overcome its less efficient metabolism to 2-NTP leading to strong SARS-CoV-2 antiviral efficacy in an African green monkey infection model. Exposure-based SARS-CoV-2 efficacy relationships resulted in an estimated clinical dose of 350-400 mg twice-daily. Importantly, all SARS-CoV-2 variants remain susceptible to 2 which supports development of 3 as a promising COVID-19 treatment.

pharmacology and toxicology↗

bioRxiv2023

DeepCORE: An interpretable multi-view deep neural network model to detect co-operative regulatory elements

Gene transcription is an essential process involved in all aspects of cellular functions with significant impact on biological traits and diseases. This process is tightly regulated by multiple elements that co-operate to jointly modulate the transcription levels of target genes. To decipher the complicated regulatory network, we present a novel multi-view attention-based deep neural network that models the relationship between genetic, epigenetic, and transcriptional patterns and identifies co-operative regulatory elements (COREs). We applied this new method, named DeepCORE, to predict transcriptomes in 25 different cell lines, which outperformed the state-of-the-art algorithms. Furthermore, DeepCORE translates the attention values embedded in the neural network into interpretable information, including locations of putative regulatory elements and their correlations, which collectively implies COREs. These COREs are significantly enriched with known promoters and enhancers. Novel regulatory elements discovered by DeepCORE showed epigenetic signatures consistent with the status of histone modification marks.

bioinformatics↗

bioRxiv2023

Spatiotemporal Genomic Profiling of Intestinal Metaplasia Reveals Clonal Dynamics of Gastric Cancer Progression

Intestinal metaplasia (IM) is a pre-malignant condition of the gastric mucosa associated with increased gastric cancer (GC) risk. We analyzed 1256 gastric samples (1152 IMs) from 692 subjects through a prospective 10-year study. We identified 26 IM driver genes in diverse pathways including chromatin regulation (ARID1A) and intestinal homeostasis (SOX9), largely occurring as small clonal events. Analysis of clonal dynamics between and within subjects, and also longitudinally across time, revealed that IM clones are likely transient but increase in size upon progression to dysplasia, with eventual transmission of somatic events to paired GCs. Single-cell and spatial profiling highlighted changes in tissue ecology and lineage heterogeneity in IM, including an intestinal stem-cell dominant cellular compartment linked to early malignancy. Expanded transcriptome profiling revealed expression-based molecular subtypes of IM, including a body-resident "pseudoantralized" subtype associated with incomplete histology, antral/intestinal cell types, ARID1A mutations, inflammation, and microbial communities normally associated with the healthy oral tract. We demonstrate that combined clinical- genomic models outperform clinical-only models in predicting IMs likely to progress. Our results raise opportunities for GC precision prevention and interception by highlighting strategies for accurately identifying IM patients at high GC risk and a role for microbial dysbiosis in IM progression.

cancer biology↗

bioRxiv2023

STORM imaging buffer with refractive index matched to standard immersion oil

Stochastic optical reconstruction microscopy (STORM) provides exceptional super-resolution imaging by sparsely blinking individual dye molecules in thiol-containing media. STORM is now well-established for imaging thin biological specimens, and recent technological advancements have expanded its use to thick tissues. While the use of mounting media with an oil refractive index has been shown to reduce light scattering within tissues and thus greatly improve imaging depth and resolution in optical microscopy, the refractive index of STORM imaging buffers is typically water-like and oil-index (OI) buffers have never been considered for this purpose. In this study, we report a 3-pyridinemethanol-based STORM buffer that matches the refractive index of standard immersion oil. Our OI buffer exhibits similar superior performance in terms of photoswitching of Alexa Flour 647 dye and STORM image quality in fixed cells as conventional STORM buffers, despite having a completely different refractive index. Interestingly, it shows remarkable stability for at least 25 days, and potentially longer, which will enable STORM imaging of a large number of cells on a single prepared slide, as well as larger field-of-view imaging through multiple field stitching. By achieving perfect index matching with oil immersion objectives, OI buffers can produce accurate nanoscale morphology of thin biological specimens, without the need for complex microscope calibrations across sample depth. More importantly, our STORM buffer is expected to play a crucial role in lightsheet STORM applications for thick tissues by reducing light scattering, thereby leading to improved imaging depth and localization performance.

bioengineering↗

bioRxiv2023

Angiotensin II receptor inhibition ameliorates liver fibrosis and enhances hepatocellular carcinoma infiltration by effector T cells

Although viral hepatocellular carcinoma (HCC) is declining, non-viral HCC, which often is the end-stage of non-alcoholic or alcoholic steatohepatitis (NASH, ASH), is on an upward trajectory. Immune checkpoint inhibitors (ICI) that block the T cell inhibitory receptor PD-1 were approved for treatment of all HCC types. However, only a small portion of HCC patients show a robust and sustained response to PD-1 blockade, calling for improved understanding of factors that negatively impact response rate and duration and the discovery of new adjuvant treatments that enhance ICI responsiveness. Using a mouse model of NASH-driven HCC, we identified peritumoral fibrosis as a potential obstacle to T cell mediated tumor regression and postulated that anti-fibrotic medications may increase ICI responsiveness. We now show that the angiotensin II receptor inhibitor losartan, a commonly prescribed and safe antihypertensive drug, reduced liver and peritumoral fibrosis and substantially enhanced anti-PD-1 induced tumor regression. Although losartan did not potentiate T cell reinvigoration, it substantially enhanced HCC infiltration by effector CD8+ T cells compared to PD-1 blockade alone. The beneficial effects of losartan correlated with inhibition of TGF-{beta} receptor signaling, collagen deposition and depletion of immunosuppressive fibroblasts. SignificanceImmune checkpoint inhibitors are used in HCC treatment but overall response rates for single agent PD-1/PD-L1 blockers have remained stubbornly low. Using a mouse model of NASH-driven HCC, we show that co-treatment with the safe and inexpensive angiotensin II receptor inhibitor losartan substantially enhanced anti-PD-1 triggered HCC regression. Although losartan did not influence the reinvigoration of exhausted CD8+ T cells it considerably enhanced their intratumoral invasion, which we postulated to be compromised by peritumoral fibrosis. Indeed, the beneficial effect of losartan correlated with inhibition of TGF-{beta} signaling and collagen deposition, and depletion of immunosuppressive fibroblasts. Losartan should be evaluated for its adjuvant activity in HCC patients undergoing PD-1/PD-L1 blocking therapy.

cancer biology↗

bioRxiv2023

FBP1 is a nonenzymatic safety valve that curtails AKT activation to prevent insulin hyperresponsiveness

Insulin inhibits gluconeogenesis and stimulates glucose conversion to glycogen and lipids. How these activities are coordinated to prevent hypoglycemia and hepatosteatosis is not clear. Fructose-1,6 bisphosphatase (FBP1) is rate controlling for gluconeogenesis. However, inborn human FBP1 deficiency does not cause hypoglycemia unless accompanied by fasting or starvation, which also trigger paradoxical hepatomegaly, hepatosteatosis, and hyperlipidemia in affected individuals. Hepatocyte FBP1-ablated mice exhibit identical fasting-conditional pathologies along with AKT hyperactivation, whose inhibition reversed hepatomegaly, hepatosteatosis and hyperlipidemia but not hypoglycemia. Surprisingly, fasting-mediated AKT hyperactivation is insulin-dependent. FBP1 prevents insulin hyperresponsiveness, independently of its catalytic activity, by interacting with AKT, PP2A-C and Aldolase-B (ALDOB) to specifically accelerate AKT dephosphorylation. Enhanced by fasting and weakened by elevated insulin, FBP1:AKT:PP2A-C:ALDOB complex formation, which is disrupted by human FBP1 deficiency mutations or a C-terminal FBP1 truncation, prevents insulin-triggered liver pathologies and maintains lipid and glucose homeostasis. Conversely, a complex disrupting peptide reverses diet-induced insulin resistance.

molecular biology↗

bioRxiv2023

A pillar/perfusion plate enhances cell growth, reproducibility, throughput, and user friendliness in dynamic 3D cell culture

Static three-dimensional (3D) cell culture has been demonstrated in ultralow attachment well plates, hanging droplet plates, and microtiter well plates with hydrogels or magnetic nanoparticles. Although it is simple, reproducible, and relatively inexpensive, thus potentially used for high-throughput screening, statically cultured 3D cells often suffer from the necrotic core due to limited nutrient and oxygen diffusion and waste removal and have limited in vivo-like tissue structure. Here, we overcome these challenges by developing a pillar/perfusion plate platform and demonstrating high-throughput, dynamic 3D cell culture. Cell spheroids have been loaded on the pillar plate with hydrogel by simple sandwiching and encapsulation and cultured dynamically in the perfusion plate on a digital rocker. Unlike traditional microfluidic devices, fast flow rates were maintained within perfusion wells, and the pillar plate could be separated from the perfusion plate for cell-based assays. It was compatible with common lab equipment and allowed cell culture, testing, staining, and imaging in situ. The pillar/perfusion plate enhanced cell growth by rapid diffusion, reproducibility, assay throughput, and user friendliness in dynamic 3D cell culture.

bioengineering↗

bioRxiv2023

High-resolution assessment of multidimensional cellular mechanics using label-free refractive-index traction force microscopy

A critical requirement for studying cell mechanics is three-dimensional (3D) assessment of cellular shapes and forces with high spatiotemporal resolution. Traction force microscopy (TFM) with fluorescence imaging enables the measurement of cellular forces, but it is limited by photobleaching and a slow 3D acquisition speed. Here, we present refractive-index traction force microscopy (RI-TFM), a high-speed volumetric technique that simultaneously quantifies the 3D morphology and traction force of cells. RI-TFM reconstructs a 3D tomogram of single cells on a planar hydrogel elastomer using a high-speed illumination scheme with 0.5-Hz temporal resolution. This allows for quantitative analyses of 3D dry-mass distributions and shear (in-plane) and normal (out-of-plane) tractions of single cells on the extracellular matrix without labelling. When combined with a constrained total variation-based deconvolution algorithm, the proposed method provides 0.55-Pa shear (in-plane) and 1.59-Pa normal (out-of-plane) traction sensitivity for a 1-kPa hydrogel substrate. We demonstrate the utility of RI-TFM by assessing the effects of compromised intracellular stress due to actin disruption or low temperature and capturing the rapid dynamics of cellular junction formation in the spatiotemporal changes in non-planar traction components.

biophysics↗

bioRxiv2023

A General Fluorescence-Based Method for Quantifying and Mapping Biomolecular Polarity In Vitro and In Cells

Spatial discretization of biomolecules in the complex cellular environment is crucial for biomolecular form and function. The ability to better understand the driving force of spatial discretization of biomolecules in the complex cellular matrix remains a challenging task. We report on the robust polarity sensitive solvatochromic probe, FLAM, in conjunction with spectral phasor analysis as a general method for studying environmental polarity in biological systems. We find that phase separated proteins of SFPQ have distinct polarity depending on the type of phase separation occurring, suggesting that polarity plays a role in the formation of phase separated condensates. When using FLAM in cells, distinct subcellular environmental polarity distribution but similar trend of changes is observed for cells under similar type of stressors. Taken together, our method puts forth an exciting development in the tool set for the study of phase separation.

biochemistry↗

bioRxiv2023

Volumetric refractive index measurement and quantitative density analysis of mouse brain tissue with sub-micrometer spatial resolution

High-resolution structural imaging of brain tissue is important for neuroscience research. However, conventional approaches have several limitations, such as the need for exogenous staining, limited accessibility to volumetric information, and qualitative analysis. Herein, we present high-resolution label-free volumetric imaging and analysis of mouse brain tissue using three-dimensional quantitative phase imaging. Measurement of the refractive index distribution of tissue enables direct imaging of the cellular and subcellular structures. Quantification of subcellular organelles is performed in the anatomical regions of the somatosensory cortex, corpus callosum, caudoputamen, and thalamus regions.

biophysics↗

bioRxiv2023

Early infection response of the first trimester human placenta at single-cell scale

Placental infections are a major worldwide burden, particularly in developing countries. The placenta is a transient tissue located at the interface between the mother and the fetus. Some pathogens can access the placental barrier resulting in pathological transmission from mother to fetus, which may have a profound impact on the health of the developing fetus. Limited tissue accessibility, critical differences between humans and mice, and, until recently, lack of proper in vitro models, have hampered our understanding of the early placental response to pathogens. Here we use single-cell transcriptomics to describe the placental primary defence mechanisms against three pathogens that are known to cause fetal and maternal complications during pregnancy - Plasmodium falciparum, Listeria monocytogenes and Toxoplasma gondii. We optimise ex vivo placental explants of the first-trimester human placenta and show that trophoblasts (the epithelial-like cells of the placenta), and Hofbauer cells (placental macrophages) orchestrate a coordinated inflammatory response after 24 hours of infection. We show that hormone biosynthesis and transport are downregulated in the trophoblasts, suggesting that protective responses are promoted at the expense of decreasing other critical functions of the placenta, such as the endocrine production and the nourishment of the fetus. In addition, we pinpoint pathogen-specific effects in some placental lineages, including a strong mitochondrial alteration in the Hofbauer cells in response to T. gondii. Finally, we identify adaptive strategies and validate nutrient acquisition employed by the P. falciparum during placental malaria infection. This study provides the first detailed cellular map of the first-trimester placenta upon infection and describes the early events that may lead to fetal and placental disorders if left unchecked.

genomics↗