Biology subjects

Smith, A.

Publications and source records attributed to Smith, A..

At least 73 records · Page 4Linked to original sources

bioRxiv2024

Plasmids encode and can mobilize onion pathogenicity in Pantoea agglomerans

Pantoea agglomerans is one of four Pantoea species for which strains have been reported in the United States to cause bacterial rot of onion bulbs. However, not all P. agglomerans strains are pathogenic to onion. We characterized onion-associated strains of P. agglomerans to elucidate the genetic and genomic signatures of onion-pathogenic P. agglomerans. We collected >300 P. agglomerans strains associated with symptomatic onion plants and bulbs from public culture collections, research laboratories, and a multi-year survey in 11 states in the USA. Genome assemblies were generated for 87 P. agglomerans strains that showed a range in onion virulence phenotypes. Combining the 87 genome assemblies with 100 high-quality, public P. agglomerans genome assemblies identified two well-represented and well-supported P. agglomerans phylogroups. Strains causing severe symptoms on onion leaves and bulbs were only identified in Phylogroup II and encoded the HiVir biosynthetic cluster for the phytotoxin pantaphos, supporting the role of HiVir as a crucial pathogenicity factor. Using a MASH-based plasmid classification system, the P. agglomerans HiVir cluster was determined to be encoded in two distinct plasmid contexts: 1) as an accessory gene cluster on a conserved P. agglomerans plasmid (pAggl), or 2) on a mosaic cluster of plasmids common among onion strains (pOnion). Analysis of closed genomes of P. agglomerans revealed that the pOnion plasmids harbored alt genes responsible for encoding tolerance to the thiosulfinate defensive chemistry in Allium spp. Additionally, many of these pOnion plasmids harbored cop gene clusters, which confer resistance to copper. However, the pOnion plasmids encoded the HiVir cluster less frequently. We demonstrated that the pOnion plasmid pCB1C, encoding HiVir and alt clusters as well as an intact conjugative type IV secretion system (T4SS), can act as a natively mobilizable pathogenicity plasmid that transforms P. agglomerans Phylogroup I strains, including environmental strains, into virulent pathogens of onion. This work indicates a central role for plasmids and plasmid ecology in mediating P. agglomerans interactions with onion plants, with potential implications for onion bacterial disease management.

microbiology↗

bioRxiv2024

Neuro-immunology in a mouse model of anti-NMDAR encephalitis and assessment of treatment approaches

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a disorder mediated by autoantibodies against the GluN1 subunit of NMDAR. It occurs with severe neuropsychiatric symptoms that often improve with immunotherapy. Clinical studies and animal models based on patients antibody transfer or NMDAR immunization suggest that the autoantibodies play a major pathogenic role. Yet, there is an important need of models offering an all-inclusive neuro-immunobiology of the disease together with a clinical course long enough to facilitate the assessment of potential new treatments. Toward this end, eight-week-old female mice (C57BL/6J) were immunized (days 1 and 28) with GluN1356-385 peptide or saline with AddaVax adjuvant and pertussis toxin. After symptom development ([~]day 35), subsets of mice were treated with an anti-CD20 (day 35), a positive allosteric modulator (PAM) of NMDAR (NMDAR-PAM, SGE-301) from days 45 to 71, or both. GluN1-antibody synthesis, epitope spreading, effects of antibodies on density and function of NMDAR, brain immunological infiltrates, microglial activation and NMDAR phagocytosis, and antibody synthesis in cultured inguinal and deep cervical lymph nodes (DCLN) were assessed with techniques including immunohistochemistry, calcium imaging, confocal and super-resolution microscopy, electrophysiology, or flow cytometry. Changes of memory and behaviour were assessed with a panel of behavioural tests, and clinical/subclinical seizures with brain-implanted electrodes. Immunized mice, but not controls, developed serum and CSF NMDAR-antibodies (IgG1 predominant) against the immunizing peptide and other GluN1 regions (epitope spreading) resulting in a decrease of synaptic and extrasynaptic NMDAR clusters and reduction of hippocampal plasticity. These findings were associated with brain inflammatory infiltrates, mainly B- and plasma cells, microglial activation, colocalization of NMDAR-IgG complexes with microglia, and presence of these complexes within microglial endosomes. Cultures of DCLC showed GluN1-antibody production. These findings were associated with psychotic-like behaviour (predominant at disease onset), memory deficit, depressive-like behaviour, abnormal movements (15% of mice), and lower threshold for developing pentylenetetrazole-induced seizures (hypoactivity, myoclonic jerks, continuous tonic-clonic) which correlated with regional cFOS expression. Most symptoms and neurobiological alterations were reversed by the anti-CD20 and PAM, alone or combined. Initial repopulation of B cells, by the end of the study, was associated with re-emergence of clinical-neurobiological alterations, which were abrogated by PAM. Overall, this model offers an all-inclusive neuro-immunobiology of the disease, allowing testing novel treatments, supporting the potential therapeutic role of NMDAR-PAM, and suggesting an immunological paradigm of systemic antigen presentation and brain NMDAR epitope spreading, which along the DCLN might contribute to fine-tune the polyclonal immune response.

neuroscience↗

bioRxiv2024

Systematic Targeting of Protein Complexes with Molecular COUPLrs

Molecular glues that engage protein complexes have transformed the study of cell biology and have had a direct impact on clinical oncology. However, the identification of new glue classes and their corresponding protein complexes has remained largely serendipitous. To overcome this challenge, we report the development of molecular COUPLrs, elaborated small molecules flanked by two cysteine-reactive warheads, as well as CONNECT, an integrated chemical proteomic platform for target deconvolution. By profiling a library of molecular COUPLrs across 13 cancer cell lines, we uncovered hundreds of proteins that can be coupled together, including in some cases in mutant selective fashions. We develop an advanced COUPLr for the oncogene EML4-ALK, which engages the fusion outside of its kinase domain, restricts protein dynamics, and disrupts EML4-ALK signaling. Collectively, molecular COUPLrs substantially expand the scope of proteins that can be chemically connected, providing an unbiased approach to identify small molecules that target protein complexes.

systems biology↗

bioRxiv2024

ILC2s navigate tissue redistribution during infection using stage-specific S1P receptors

Lymphocytes can circulate as well as take residence within tissues. While the mechanisms by which circulating populations are recruited to infection sites have been extensively characterized, the molecular basis for the recirculation of tissue-resident cells is less understood. Here, we show that helminth infection- or IL-25-induced redistribution of intestinal group 2 innate lymphoid cells (ILC2s) requires access to the lymphatic vessel network. Although the secondary lymphoid structure is an essential signal hub for adaptive lymphocyte differentiation and dispatch, it is redundant for ILC2 migration and effector function. Upon IL-25 stimulation, a dramatic change in epigenetic landscape occurs in intestinal ILC2s, leading to the expression of sphingosine-1-phosphate receptors (S1PRs). Among the various S1PRs, we found that S1PR5 is critical for ILC2 exit from intestinal tissue to lymph. By contrast, S1PR1 plays a dominant role in ILC2 egress from mesenteric lymph nodes to blood circulation and then to distal tissues including the lung where the redistributed ILC2s contribute to tissue repair. The requirement of two S1PRs for ILC2 migration is largely due to the dynamic expression of the tissue-retention marker CD69, which mediates S1PR1 internalization. Thus, our study demonstrates a stage-specific requirement of different S1P receptors for ILC2 redistribution during infection. We therefore propose a fundamental paradigm that innate and adaptive lymphocytes utilize a shared vascular network frame and specialized navigation cues for migration.

immunology↗

bioRxiv2024

Single-cell imaging of the lytic phage life cycle dissects the timing and noise in individual infection steps

When a lytic bacteriophage infects a bacterial cell, it commandeers the cells resources to replicate, ultimately causing cell lysis and the release of new virions. As phages function as obligate parasites, each stage of the infection process depends on the physiological parameters of the host cell. Given the inherent physiological variability within a population of genetically identical bacterial cells, we ask how the phage infection dynamic reflects such heterogeneity. Here, we introduce a timelapse imaging assay for investigating the dynamics of individual infection steps by a single T7 phage on a single bacterium. This high-throughput, time-resolved assay enables us to monitor the infection progression simultaneously in multiple cells, uncovering substantial heterogeneity at each step and revealing correlations between infection dynamics and the physiological state of the infected cell. Simulations of competing phage populations with different lysis time distributions reveal that heterogeneity in infection dynamics can significantly impact phage fitness, highlighting it as a potential evolutionary driver of phage-bacteria interactions.

microbiology↗

bioRxiv2024

Dynamic co-evolution of transposable elements and the piRNA pathway in African cichlid fishes

East African cichlid fishes have diversified in an explosive fashion, but the (epi)genetic basis of the phenotypic diversity of these fishes remains largely unknown. Although transposable elements (TEs) have been associated with phenotypic variation in cichlids, little is known about their transcriptional activity and epigenetic silencing. Here, we describe dynamic patterns of TE expression in African cichlid gonads and during early development. Orthology inference revealed an expansion of piwil1 genes in Lake Malawi cichlids, likely driven by PiggyBac TEs. The expanded piwil1 copies have signatures of positive selection and retain amino acid residues essential for catalytic activity. Furthermore, the gonads of African cichlids express a Piwi-interacting RNA (piRNA) pathway that target TEs. We define the genomic sites of piRNA production in African cichlids and find divergence in closely related species, in line with fast evolution of piRNA-producing loci. Our findings suggest dynamic co-evolution of TEs and host silencing pathways in the African cichlid radiations. We propose that this co-evolution has contributed to cichlid genomic diversity.

evolutionary biology↗

bioRxiv2024

Single-cell epigenomic dysregulation of Systemic Sclerosis fibroblasts via CREB1/EGR1 axis in self-assembled human skin equivalents

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin fibrosis, internal organ involvement and vascular dropout. We previously developed and phenotypically characterized an in vitro 3D skin-like tissue model of SSc, and now analyze the transcriptomic (scRNA-seq) and epigenetic (scATAC-seq) characteristics of this model at single-cell resolution. SSc 3D skin-like tissues were fabricated using autologous fibroblasts, macrophages, and plasma from SSc patients or healthy control (HC) donors. SSc tissues displayed increased dermal thickness and contractility, as well as increased -SMA staining. Single-cell transcriptomic and epigenomic analyses identified keratinocytes, macrophages, and five populations of fibroblasts (labeled FB1 - 5). Notably, FB1 APOE-expressing fibroblasts were 12-fold enriched in SSc tissues and were characterized by high EGR1 motif accessibility. Pseudotime analysis suggests that FB1 fibroblasts differentiate from a TGF-{beta}1-responsive fibroblast population and ligand-receptor analysis indicates that the FB1 fibroblasts are active in macrophage crosstalk via soluble ligands including FGF2 and APP. These findings provide characterization of the 3D skin-like model at single cell resolution and establish that it recapitulates subsets of fibroblasts and macrophage phenotypes observed in skin biopsies.

genomics↗

bioRxiv2024

Epigenomic profiling of active regulatory elements by enrichment of unmodified CpG dinucleotides

Current approaches for the study of DNA methylation and other modified bases focus on the modified fraction of the genome and are particularly well-suited to the detection of DNA hypermethylation. However, the study of hypomethylation (loss of DNA methylation), which is typically associated with markers of active chromatin, has been largely overlooked, in part, due to the lack of a suitable methodology. We present an enrichment-based and bisulfite-free approach for epigenomic profiling named "Active-Seq" (Azide Click Tagging for In Vitro Epigenomic sequencing) that achieves genome-wide profiling of DNA, by enriching for non-modified CpG sites using a mutated methyltransferase enzyme. We show that the genomic regions enriched by Active-Seq overlap with promoters, enhancers and partially methylated domains, all of which have had their methylation status linked to the development and progression of diseases. Active-Seq is a fast epigenetic profiling platform with a simple and streamlined workflow, performed in tandem with sequencing library preparation. The enzymatic chemistry is non-damaging toward the DNA which is critical for working with low concentration DNA input and will facilitate the future development of multiomics assays. We demonstrate robust and reproducible performance of Active-Seq using low DNA input in cell lines, liquid biopsies (cell-free DNA, cfDNA) and formalin-fixed paraffin embedded (FFPE) tissue.

genomics↗

bioRxiv2024

NRP1-expressing myeloid cells promote arteriogenesis in the ischemic limb

Peripheral arterial disease can cause limb threatening blood flow restriction, requiring amputation in up to a third of patients despite contemporary treatments. Stimulating new blood vessel growth in ischemic limbs using growth factors such as VEGF-A or supplying mixed cell populations via autologous transplantation has been investigated as a therapy for surgically intractable cases, but to date has proven ineffective in randomised controlled clinical studies. To identify more potent pro-arteriogenic cell populations, we have investigated VEGF-A responsive myeloid cell populations in a mouse model of severe hindlimb ischemia. We found that NRP1 ablation from monocytes and macrophages impaired arteriogenesis in the adductor muscle and flow recovery in the injured limb. Vice versa, the exogenous delivery of NRP1-expressing (but not NRP1-negative) macrophages enhanced arteriogenesis in the adductor and flow recovery in the ischemic limb in a VEGF signalling-dependent manner. Further, patient-derived NRP1-expressing monocytes promoted vascular morphogenesis ex vivo. As the levels of circulating NRP1-expressing monocytes were raised in patients with limb ischemia, the therapeutic delivery of autologous NRP1-expressing monocytes could be explored as a treatment for critical limb ischemia.

pathology↗

bioRxiv2023

Comparative transcriptomics provides insight into molecular mechanisms of zinc tolerance in the ectomycorrhizal fungus Suillus luteus

Zinc is a major soil contaminant and high zinc levels can disrupt growth, survival, and reproduction of fungi. Some fungal species have evolved zinc tolerance through cell processes mitigating zinc toxicity, though the genes and detailed mechanisms underlying fungal zinc tolerance remain unexplored. To fill this gap in knowledge, we investigated the gene expression of zinc tolerance in the mycorrhizal fungus Suillus luteus. We found that zinc tolerance in this species is both a constitutive and environmentally dependent trait. Highly differentially expressed genes were predicted to be involved in transmembrane transport, metal chelation, oxidoreductase activity, and signal transduction. Some of these genes were previously reported as candidates for S. luteus zinc tolerance, while others are reported here for the first time. Overall, we found S. luteus zinc tolerance is associated with differences in expression of genes involved in metal exclusion and immobilization, as well as recognition and mitigation of metal-induced oxidative stress. Our results contribute to understanding the mechanisms of fungal metal tolerance and pave the way for further research on the role of metal tolerance in mycorrhizal associations.

genomics↗

bioRxiv2023

Branching topology of the human embryo transcriptome revealed by entropy sort feature weighting

Single cell transcriptomics (scRNA-seq) transforms our capacity to define cell states and reveal developmental trajectories. Resolution is challenged, however, by high dimensionality and noisy data. Analysis is therefore typically performed after sub-setting to highly variable genes (HVGs). However, existing HVG selection techniques have been found to have poor agreement with one another, and tend to be biased towards highly expressed genes. Entropy sorting provides an alternative mathematical framework for feature subset selection. Here we implement continuous entropy sort feature weighting (cESFW). On synthetic datasets, cESFW outperforms HVG selection in distinguishing cell state specific genes. We apply cESFW to six merged scRNA-seq datasets spanning human early embryo development. Without smoothing or augmenting the raw counts matrices, cESFW generates a high-resolution embedding displaying coherent developmental progression from 8-cell to post-implantation stages, delineating 15 distinct cell states. The embedding highlights sequential lineage decisions during blastocyst development while unsupervised clustering identifies branch point populations. Cells previously claimed to lack a developmental trajectory reside in the first branching region where morula differentiates into Inner Cell Mass (ICM) or Trophectoderm (TE). We quantify the relatedness of pluripotent stem cell cultures to embryo cell types and identify naive and primed marker genes conserved across culture conditions and the human embryo. Finally, by identifying genes with specifically enriched and dynamic expression during blastocyst formation, we provide markers for staging lineage progression from morula to blastocyst. Together these analyses indicate that cESFW provides the ability to reveal gene expression dynamics in scRNA-seq data that HVG selection can fail to elucidate.

bioinformatics↗

bioRxiv2023

Light management by algal aggregates in living photosynthetic hydrogels.

Rapid progress in algal biotechnology has triggered a growing interest in hydrogel-encapsulated microalgal cultivation, especially for the engineering of functional photosynthetic materials and biomass production. An overlooked characteristic of gel-encapsulated cultures is the emergence of cell aggregates, which are the result of the mechanical confinement of the cells. Such aggregates have a dramatic effect on the light management of gel-encapsulated photobioreactors and hence strongly affect the photosynthetic outcome. In order to evaluate such an effect, we experimentally studied the optical response of hydrogels containing algal aggregates and developed optical simulations to study the resultant light intensity profiles. The simulations are validated experimentally via transmittance measurements using an integrating sphere and aggregate volume analysis with confocal microscopy. Specifically, the heterogeneous distribution of cell aggregates in a gel matrix can increase light penetration while alleviating photoinhibition compared to a flat biofilm. Finally, we demonstrate that light harvesting efficiency can be further enhanced with the introduction of scattering particles within the hydrogel matrix, leading to a four-fold increase in biomass growth. Our study, therefore, highlights a new strategy for the design of spatially efficient photosynthetic living materials that have important implications for the engineering of future algal cultivation systems. Significance StatementThe ability to cultivate microalgae at scale efficiently would allow more sustainable production of food and food additives. However, efficient growth of microalgae requires optimised light conditions, which are usually challenging to obtain using biofilm cultivations mode: as the outer layer of cells are necessarily more exposed to incoming light than the inner layer, posing the problem of photoinhibition on the outer cells receiving too much light, and shading the ones below. Here we study both experimentally and numerically, how microalgae aggregates growing in the confinement of a hydrogel can provide an improved light distribution and therefore biomass growth is maximised. This study proposes new strategies on how to engineer future photobioreactors.

plant biology↗

bioRxiv2023

Targeting EIF4A triggers an interferon response to synergize with chemotherapy and suppress triple-negative breast cancer

Protein synthesis is frequently dysregulated in cancer and selective inhibition of mRNA translation represents an attractive cancer therapy. Here, we show that therapeutically targeting the RNA helicase eIF4A by Zotatifin, the first-in-class eIF4A inhibitor, exerts pleiotropic effects on both tumor cells and the tumor immune microenvironment in a diverse cohort of syngeneic triple-negative breast cancer (TNBC) mouse models. Zotatifin not only suppresses tumor cell proliferation but also directly repolarizes macrophages towards an M1-like phenotype and inhibits neutrophil infiltration, which sensitizes tumors to immune checkpoint blockade. Mechanistic studies revealed that Zotatifin reprograms the tumor translational landscape, inhibits the translation of Sox4 and Fgfr1, and induces an interferon response uniformly across models. The induction of an interferon response is partially due to the inhibition of Sox4 translation by Zotatifin. A similar induction of interferon-stimulated genes was observed in breast cancer patient biopsies following Zotatifin treatment. Surprisingly, Zotatifin significantly synergizes with carboplatin to trigger DNA damage and an even heightened interferon response resulting in T cell-dependent tumor suppression. These studies identified a vulnerability of eIF4A in TNBC, potential pharmacodynamic biomarkers for Zotatifin, and provide a rationale for new combination regimens comprising Zotatifin and chemotherapy or immunotherapy as treatments for TNBC. One Sentence SummaryTargeting EIF4A sensitizes TNBC to immune therapy and chemotherapy by suppressing Sox4, inducing an interferon response, and reprograming the tumor immune microenvironment.

cancer biology↗

bioRxiv2023

Antimicrobial efficacy of in-situ plasma-generated ozone against Pseudomonas aeruginosa biofilms in drains and water-submerged surfaces

AimsTo demonstrate a novel method of gaseous disinfection that can eradicate biofilms inhabiting elusive regions of plumbing systems. Methods & ResultsHighly biocidal ozone is generated in-situ using the ambient air inside a model sink and drain, via portable plasma discharge, with the plasma device sealing the treated area, ensuring no ozone escape to the external environment. Subsequent bacterial recovery illustrates an approximate bioburden reduction of 5log10 for biofilms suspended in the drain, and 6log10 for biofilms placed in the sink. ConclusionsPlasma-generated ozone is a safe and effective method for controlling bioburden in periodically wetted, otherwise inaccessible pipework and drains, both above and below the water line. Significance and Impact of StudyThe ozone generation system described has potential for controlling healthcare associated infections (HAIs) and infections linked to closed environments, such as cruise ships, from bacteria arising from waste water systems by aerosolization or splash-back. The method has additional benefits provided by an absence of toxic residues after application, reducing risks to users and the waste water system. Cost effectiveness is high, requiring minimal energy input from the electrical supply and only ambient air (no additional feedstock gas is necessary) to generate ozone.

microbiology↗

bioRxiv2023

Dysregulation of chromatin via H3K27 methylation underpins differentiation arrest in Isocitrate dehydrogenase-mutant Acute Myeloid Leukaemia.

Dysregulation of cellular differentiation is a hallmark of cancer. Isocitrate dehydrogenase (IDH) is commonly mutated multiple cancers including glioma, cholangiocarcinoma, lymphoma and Acute Myeloid Leukaemia (AML). Mutant IDH generates d-2-hydroxyglutarate that inhibits enzymes including Jumonji histone demethylases and TET2. Using primary human IDH2-mutant AML cells as a model, single cell RNA-seq and ATAC-seq, we demonstrated the continuum of cell states during restoration of neutrophilic differentiation to leukaemic progenitors by Enasidenib, a mutant IDH2 inhibitor. In cells which ultimately differentiate, there is co-expression of competing GATA2/RUNX3/SOX4-driven stem-progenitor and pro-differentiation EGR1/JUN/FOS programmes, followed by expression of cell cycle and terminal neutrophil programmes involving CEBP family and SPI1/PU.1. Genes upregulated during differentiation display loss of H3K27me3 in bivalent chromatin but not of H3K4me3, while downregulated genes are enriched for PRC2/EZH2 targets. In contrast to previous reports of a TET2-dependent mechanism for IDH-mutations, we observed only a modest link between promoter DNA CpG methylation and gene expression. For the first time in primary AML, we describe the lifting of differentiation block by de-repression of pro-differentiation genes through modulation of H3K27 demethylation in bivalent chromatin, and thus highlight a novel and important mechanism in how IDH mutations disrupt cell fates in cancer.

cancer biology↗

bioRxiv2023

Strong immunogenicity & protection in mice with PlaCCine: A COVID-19 DNA vaccine formulated with a functional polymer

DNA- based vaccines have demonstrated the potential as a safe and effective modality. PlaCCine, a DNA-based vaccine approach described subsequently relies on a synthetic DNA delivery system and is independent of virus or device. The synthetic functionalized polymer combined with DNA demonstrated stability over 12 months at 4C and for one month at 25C. Transfection efficiency compared to naked DNA increased by 5-15-fold in murine skeletal muscle. Studies of DNA vaccines expressing spike proteins from variants D614G (pVAC15), Delta (pVAC16), or a D614G + Delta combination (pVAC17) were conducted. Mice immunized intramuscular injection (IM) with pVAC15, pVAC16 or pVAC17 formulated with functionalized polymer and adjuvant resulted in induction of spike-specific humoral and cellular responses. Antibody responses were observed after one immunization. And endpoint IgG titers increased to greater than 1x 105 two weeks after the second injection. Neutralizing antibodies as determined by a pseudovirus competition assay were observed following vaccination with pVAC15, pVAC16 or pVAC17. Spike specific T cell immune responses were also observed following vaccination and flow cytometry analysis demonstrated the cellular immune responses included both CD4 and CD8 spike specific T cells. The immune responses in vaccinated mice were maintained for up to 14 months after vaccination. In an immunization and challenge study of K18 hACE2 transgenic mice pVAC15, pVAC16 and pVAC17 induced immune responses lead to decreased lung viral loads by greater than 90% along with improved clinical score. These findings suggest that PlaCCine DNA vaccines are effective and stable and further development against emerging SARS-CoV-2 variants is warranted.

immunology↗

bioRxiv2023

Salmonella Infantis, the emerging human multidrug resistant pathogen - a One Health perspective

Salmonella Infantis presents an ever-increasing threat to public health due to its spread throughout many countries and association with high levels of antimicrobial resistance (AMR). Whole genome sequences of 5,284 S. Infantis strains from 74 countries, isolated between 1989 and 2020 from a wide variety of sources including humans, animals, and food, were analysed to compare genetic phylogeny, AMR determinants and plasmid presence. The global S. Infantis population structure diverged into three clusters: a North American cluster, European cluster and a global cluster. The levels of AMR varied between the S. Infantis clusters and by isolation source; 73% of poultry isolates had multidrug resistance (MDR) compared to 35% of human isolates. This correlated with plasmid of emerging S. Infantis (pESI) presence; 71% of poultry isolates contained pESI versus 32% of human isolates. This provides important information for public health teams engaged in reducing the spread of this pathogen.

microbiology↗

bioRxiv2023

APOE4/4 is linked to damaging lipid droplets in Alzheimer's microglia

Several genetic risk factors for Alzheimers Disease (AD) implicate genes involved in lipid metabolism and many of these lipid genes are highly expressed in glial cells. However, the relationship between lipid metabolism in glia and AD pathology remains poorly understood. Through single-nucleus RNA-sequencing of AD brain tissue, we have identified a microglial state defined by the expression of the lipid droplet (LD) associated enzyme ACSL1 with ACSL1-positive microglia most abundant in AD patients with the APOE4/4 genotype. In human iPSC-derived microglia (iMG) fibrillar A{beta} (fA{beta}) induces ACSL1 expression, triglyceride synthesis, and LD accumulation in an APOE-dependent manner. Additionally, conditioned media from LD-containing microglia leads to Tau phosphorylation and neurotoxicity in an APOE-dependent manner. Our findings suggest a link between genetic risk factors for AD with microglial LD accumulation and neurotoxic microglial-derived factors, potentially providing novel therapeutic strategies for AD.

neuroscience↗