Phosphatidylserine vesicles enable efficient en bloc transmission of enteroviruses.

A central paradigm within virology is that each viral particle largely behaves as an independent infectious unit. Here, we demonstrate that clusters of enteroviral particles are packaged within phosphatidylserine (PS) lipid-enriched vesicles that are non-lytically released from cells and provide greater infection efficiency than free single viral particles. We show that vesicular PS lipids are co-factors to the relevant enterovirus receptors in mediating subsequent infectivity and transmission, in particular to primary human macrophages. We demonstrate that clustered packaging of viral particles within vesicles enables multiple viral RNA genomes to be collectively transferred into single cells. This study reveals a novel mode of viral transmission, where enteroviral genomes are transmitted from cell-to-cell en bloc in membrane-bound PS vesicles instead of as single independent genomes. This has implications for facilitating genetic cooperativity among viral quasispecies as well as enhancing viral replication.

Double-Balloon Catheter-Mediated Transarterial Chemotherapy Delivery in a Swine Model: A Mechanism Recruiting the Vasa Vasorum for Localized Therapies.

PURPOSE: Treatment of hypovascular tumors, such as pancreatic adenocarcinoma, is challenging owing to inefficient drug delivery. This report examines the potential mechanism of localized drug delivery via transarterial microperfusion (TAMP) using a proprietary adjustable double-balloon occlusion catheter in a porcine model. MATERIALS AND METHODS: Adult Yorkshire swine (N = 21) were used in the Institutional Animal Care & Use Committee-approved protocols. The RC-120 catheter (RenovoRx, Los Altos, California) was positioned into visceral, femoral, and pulmonary arteries with infusion of methylene blue dye, gemcitabine, or gold nanoparticles. Transmural delivery was compared under double-balloon occlusion with and without side-branch exclusion, single-balloon occlusion, and intravenous delivery. Intra-arterial pressure and vascular histologic changes were assessed. RESULTS: Infusion with double-balloon occlusion and side-branch exclusion provided increased intra-arterial pressure in the isolated segment and enhanced perivascular infusate penetration with minimal vascular injury. Infusates were predominantly found in the vasa vasorum by electron microscopy. CONCLUSIONS: TAMP enhanced transmural passage mediated by localized increase in arterial pressure via vasa vasorum.

PPAR-γ activation enhances myelination and neurological recovery in premature rabbits with intraventricular hemorrhage.

Intraventricular hemorrhage (IVH) results in periventricular inflammation, hypomyelination of the white matter, and hydrocephalus in premature infants. No effective therapy exists to prevent these disorders. Peroxisome proliferator activated receptor-γ (PPAR-γ) agonists reduce inflammation, alleviate free radical generation, and enhance microglial phagocytosis, promoting clearance of debris and red blood cells. We hypothesized that activation of PPAR-γ would enhance myelination, reduce hydrocephalus, and promote neurological recovery in newborns with IVH. These hypotheses were tested in a preterm rabbit model of IVH; autopsy brain samples from premature infants with and without IVH were analyzed. We found that IVH augmented PPAR-γ expression in microglia of both preterm human infants and rabbit kits. The treatment with PPAR-γ agonist or PPAR-γ overexpression by adenovirus delivery further elevated PPAR-γ levels in microglia, reduced proinflammatory cytokines, increased microglial phagocytosis, and improved oligodendrocyte progenitor cell (OPC) maturation in kits with IVH. Transcriptomic analyses of OPCs identified previously unrecognized PPAR-γ-induced genes for purinergic signaling, cyclic adenosine monophosphate generation, and antioxidant production, which would reprogram these progenitors toward promoting myelination. RNA-sequencing analyses of microglia revealed PPAR-γ-triggered down-regulation of several proinflammatory genes and transcripts having roles in Parkinson's disease and amyotrophic lateral sclerosis, contributing to neurological recovery in kits with IVH. Accordingly, PPAR-γ activation enhanced myelination and neurological function in kits with IVH. This also enhanced microglial phagocytosis of red blood cells but did not reduce hydrocephalus. Treatment with PPAR-γ agonist might enhance myelination and neurological recovery in premature infants with IVH.

Circulating exosomal microRNAs in acquired aplastic anemia and myelodysplastic syndromes.

Exosomal microRNAs modulate cancer cell metabolism and the immune response. Specific exosomal microRNAs have been reported to be reliable biomarkers of several solid and hematologic malignancies. We examined the possible diagnostic and prognostic values of exosomal microRNAs in two human bone marrow failure diseases: aplastic anemia and myelodysplastic syndromes. After screening 372 microRNAs in a discovery set (n=42) of plasma exosome samples, we constructed a customized PCR plate, including 42 microRNAs, for validation in a larger cohort (n=99). We identified 25 differentially expressed exosomal microRNAs uniquely or frequently present in aplastic anemia and/or myelodysplastic syndromes. These microRNAs could be related to intracellular functions, such as metabolism, cell survival, and proliferation. Clinical parameters and progression-free survival were correlated to microRNA expression levels in aplastic anemia and myelodysplastic syndrome patients before and after six months of immunosuppressive therapy. One microRNA, mir-126-5p, was negatively correlated with a response to therapy in aplastic anemia: patients with higher relative expression of miR-126-5p at diagnosis had the shortest progression-free survival compared to those with lower or normal levels. Our findings suggest utility of exosomal microRNAs in the differential diagnosis of bone marrow failure syndromes. (Registered at clinicaltrials.gov identifiers: 00260689, 00604201, 00378534, 01623167, 00001620, 00001397, 00217594).

Engineered nanofibrillar collagen with tunable biophysical properties for myogenic, endothelial, and osteogenic cell guidance.

A goal of regenerative engineering is the rational design of materials to restore the structure-function relationships that drive reparative programs in damaged tissues. Despite the widespread use of extracellular matrices for engineering tissues, their application has been limited by a narrow range of tunable features. The primary objective of this study is to develop a versatile platform for evaluating tissue-specific cellular interactions using Type I collagen scaffolds with highly tunable biophysical properties. The kinetics of collagen fibrillogenesis were modulated through a combination of varied shear rate and pH during neutralization, to achieve a broad range of fibril anisotropy, porosity, diameter, and storage modulus. The role that each of these properties play in guiding muscle, bone, and vascular cell types was comprehensively identified, and informed the in vitro generation of three distinct musculoskeletal engineered constructs. Myogenesis was highly regulated by smaller fibrils and larger storage moduli, endothelial inflammatory phenotype was predominantly guided by fibril anisotropy, and osteogenesis was enhanced by highly porous collagen with larger fibrils. This study introduces a novel approach for dynamically modulating Type I collagen materials and provides a robust platform for investigating cell-material interactions, offering insights for the future rational design of tissue-specific regenerative biomaterials. STATEMENT OF SIGNIFICANCE: The biophysical properties of regenerative materials facilitate key cell-substrate interactions that can guide the morphology, phenotype, and biological response of cells. In this study, we describe the fabrication of an engineered collagen hydrogel that can be modified to exhibit control over a wide range of biophysical features, including fibril organization and size, nanoscale porosity, and mechanics. We identified the unique combination of collagen features that optimally promote regenerative muscle, bone, and vascular cell types while also delineating the properties that hinder these same cellular responses. This study presents a highly accessible method to control the biophysical properties of collagen hydrogels that can be adapted for a broad range of tissue engineering and regenerative applications.

Autotaxin-lysolipid signaling suppresses a CCL11-eosinophil axis to promote pancreatic cancer progression.

Lipids and their modifying enzymes regulate diverse features of the tumor microenvironment and cancer progression. The secreted enzyme autotaxin (ATX) hydrolyzes extracellular lysophosphatidylcholine to generate the multifunctional lipid mediator lysophosphatidic acid (LPA) and supports the growth of several tumor types, including pancreatic ductal adenocarcinoma (PDAC). Here we show that ATX suppresses the accumulation of eosinophils in the PDAC microenvironment. Genetic or pharmacologic ATX inhibition increased the number of intratumor eosinophils, which promote tumor cell apoptosis locally and suppress tumor progression. Mechanistically, ATX suppresses eosinophil accumulation via an autocrine feedback loop, wherein ATX-LPA signaling negatively regulates the activity of the AP-1 transcription factor c-Jun, in turn suppressing the expression of the potent eosinophil chemoattractant CCL11 (eotaxin-1). Eosinophils were identified in human PDAC specimens, and rare individuals with high intratumor eosinophil abundance had the longest overall survival. Together with recent findings, this study reveals the context-dependent, immune-modulatory potential of ATX-LPA signaling in cancer.

Automated large volume sample preparation for vEM.

New developments in electron microscopy technology, improved efficiency of detectors, and artificial intelligence applications for data analysis over the past decade have increased the use of volume electron microscopy (vEM) in the life sciences field. Moreover, sample preparation methods are continuously being modified by investigators to improve final sample quality, increase electron density, combine imaging technologies, and minimize the introduction of artifacts into specimens under study. There are a variety of conventional bench protocols that a researcher can utilize, though most of these protocols require several days. In this work, we describe the utilization of an automated specimen processor, the mPrep™ ASP-2000™, to prepare samples for vEM that are compatible with focused ion beam scanning electron microscopy (FIB-SEM), serial block face scanning electron microscopy (SBF-SEM), and array tomography (AT). The protocols described here aimed for methods that are completed in a much shorter period of time while minimizing the exposure of the operator to hazardous and toxic chemicals and improving the reproducibility of the specimens' heavy metal staining, all without compromising the quality of the data acquired using backscattered electrons during SEM imaging. As a control, we have included a widely used sample bench protocol and have utilized it as a comparator for image quality analysis, both qualitatively and using image quality analysis metrics.

A workflow for visualizing human cancer biopsies using large-format electron microscopy.

Recent developments in large format electron microscopy have enabled generation of images that provide detailed ultrastructural information on normal and diseased cells and tissues. Analyses of these images increase our understanding of cellular organization and interactions and disease-related changes therein. In this manuscript, we describe a workflow for two-dimensional (2D) and three-dimensional (3D) imaging, including both optical and scanning electron microscopy (SEM) methods, that allow pathologists and cancer biology researchers to identify areas of interest from human cancer biopsies. The protocols and mounting strategies described in this workflow are compatible with 2D large format EM mapping, 3D focused ion beam-SEM and serial block face-SEM. The flexibility to use diverse imaging technologies available at most academic institutions makes this workflow useful and applicable for most life science samples. Volumetric analysis of the biopsies studied here revealed morphological, organizational and ultrastructural aspects of the tumor cells and surrounding environment that cannot be revealed by conventional 2D EM imaging. Our results indicate that although 2D EM is still an important tool in many areas of diagnostic pathology, 3D images of ultrastructural relationships between both normal and cancerous cells, in combination with their extracellular matrix, enables cancer researchers and pathologists to better understand the progression of the disease and identify potential therapeutic targets.

Data supporting the effects of lysozyme on mRNA and protein expression in a colonic epithelial scratch wound model.

Colonic epithelial health is implicated in a host of gastrointestinal (GI) diseases and disorders. Lysozyme is suspected to play a role in the ability of the epithelium to recover from injury (Abey et al., in press; Gallo, 2012; Rubio, 2014) [1], [2], [3]. Disrupted repair mechanisms may lead to delayed or ineffective recovery and disruptions to epithelial biology resulting in GI symptoms and altered barrier function (Peterson and Artis, 2014) [4]. The effect of lysozyme on the transcriptomic and proteomic profile of healthy colonic epithelial cells was investigated. Epithelial cells in culture were scratch wounded and treated with lysozyme. mRNA and protein profiles were simultaneously quantified in the same sample using a digital counting technology. Gene and protein expressions altered by the presence or absence of lysozyme are described in this article. Extensive statistical and bioinformatic analysis, and interpretation of the results can be found in "Lysozyme association with circulating RNA, extracellular vesicles, and chronic stress" (Abey et al., in press) [1].

Lysozyme association with circulating RNA, extracellular vesicles, and chronic stress.

BACKGROUND: Stress has demonstrated effects on inflammation though underlying cell-cell communication mechanisms remain unclear. We hypothesize that circulating RNAs and extracellular vesicles (EVs) in patients with chronic stress contain signals with functional roles in cell repair. METHODS: Blood transcriptome from patients with Irritable Bowel Syndrome versus controls were compared to identify signaling pathways and effectors. Plasma EVs were isolated (size-exclusion chromatography) and characterized for effectors' presence (immunogold labelling-electron microscopy). Based on transcriptome pathways and EV-labelling, lysozyme's effects on cell migration were tested in human colon epithelial CRL-1790 cells and compared to the effects of CXCL12, a migration inducer (wound assay). The effect of lysozyme on immune-linked mRNA and protein levels in cells which survived following serum starvation and scratch wound were investigated (NanoString). RESULTS: Blood transcriptomes revealed pyridoxal 5'phosphate salvage, pyrimidine ribonucleotides salvage pathways, atherosclerosis, and cell movement signaling with membrane CD9 and extracellular lysozyme as effectors. Plasma EVs showed labelling with CD9, mucins, and lysozyme. This is the first identification of lysozyme on plasma EVs. In CRL-1790 cells, lysozyme induced migration and repaired scratch wound as well as CXCL12. Immune mRNA and protein expressions were altered in cells which survived following serum starvation and scratch wound, with or without lysozyme in serum-free media post-wounding: CD9, IL8, IL6 mRNAs and CD9, NT5E, PD-L1 proteins. CONCLUSIONS: Repair and inflammatory signals are identified in plasma EVs and circulating RNAs in chronic stress. Registered clinicaltrials.gov #NCT00824941. GENERAL SIGNIFICANCE: This study highlights the role of circulating RNAs and EVs in stress.