RNA encoded peptide barcodes enable efficient in vivo screening of RNA delivery systems.

Lipid nanoparticles (LNPs) have been demonstrated to hold great promise for the clinical advancement of RNA therapeutics. Continued exploration of LNPs for application in new disease areas requires identification and optimization of leads in a high throughput way. Currently available high throughput in vivo screening platforms are well suited to screen for cellular uptake but less so for functional cargo delivery. We report on a platform which measures functional delivery of LNPs using unique peptide 'barcodes'. We describe the design and selection of the peptide barcodes and the evaluation of these for the screening of LNPs. We show that proteomic analysis of peptide barcodes correlates with quantification and efficacy of barcoded reporter proteins both in vitro and in vivo and, that the ranking of selected LNPs using peptide barcodes in a pool correlates with ranking using alternative methods in groups of animals treated with individual LNPs. We show that this system is sensitive, selective, and capable of reducing the size of an in vivo study by screening up to 10 unique formulations in a single pool, thus accelerating the discovery of new technologies for mRNA delivery.

A Novel Graphene Quantum Dot-Based mRNA Delivery Platform.

During the last decades, there has been growing interest in using therapeutic messager RNA (mRNA) together with drug delivery systems. Naked, unformulated mRNA is, however, unable to cross the cell membrane and is susceptible to degradation. Here we use graphene quantum dots (GQDs) functionalized with polyethyleneimine (PEI) as a novel mRNA delivery system. Our results show that these modified GQDs can be used to deliver intact and functional mRNA to Huh-7 hepatocarcinoma cells at low doses and, that the GQDs are not toxic, although cellular toxicity is a problem for these first-generation modified particles. Functionalized GQDs represent a potentially interesting delivery system that is easy to manufacture, stable and effective.

A high-throughput Galectin-9 imaging assay for quantifying nanoparticle uptake, endosomal escape and functional RNA delivery.

RNA-based therapies have great potential to treat many undruggable human diseases. However, their efficacy, in particular for mRNA, remains hampered by poor cellular delivery and limited endosomal escape. Development and optimisation of delivery vectors, such as lipid nanoparticles (LNPs), are impeded by limited screening methods to probe the intracellular processing of LNPs in sufficient detail. We have developed a high-throughput imaging-based endosomal escape assay utilising a Galectin-9 reporter and fluorescently labelled mRNA to probe correlations between nanoparticle-mediated uptake, endosomal escape frequency, and mRNA translation. Furthermore, this assay has been integrated within a screening platform for optimisation of lipid nanoparticle formulations. We show that Galectin-9 recruitment is a robust, quantitative reporter of endosomal escape events induced by different mRNA delivery nanoparticles and small molecules. We identify nanoparticles with superior escape properties and demonstrate cell line variances in endosomal escape response, highlighting the need for fine-tuning of delivery formulations for specific applications.

High-Throughput Automation of Endosomolytic Polymers for mRNA Delivery.

In recent years, there has been an increasing interest in designing delivery systems to enhance the efficacy of RNA-based therapeutics. Here, we have synthesized copolymers comprised of dimethylaminoethyl methacrylate (DMAEMA) or diethylaminoethyl methacrylate (DEAEMA) copolymerized with alkyl methacrylate monomers ranging from 2 to 12 carbons, and developed a high throughput workflow for rapid investigation of their applicability for mRNA delivery. The structure activity relationship revealed that the mRNA encapsulation efficiency is improved by increasing the cationic density and use of shorter alkyl side chains (2-6 carbons). Minimal cytotoxicity was observed when using DEAEMA-co-BMA (EB) polyplexes up to 18 h after dosing, independent of a poly(ethylene glycol) (PEG) first block. The lowest molecular weight polymer (EB10,250) performed best, exhibiting greater transfection than polyethyenimine (PEI) based upon the number of cells transfected and mean intensity. Conventional investigations into the performance of polymeric materials for mRNA delivery is quite tedious, consequently limiting the number of materials and formulation conditions that can be studied. The high throughput approach presented here can accelerate the screening of polymeric systems and paves the way for expanding this generalizable approach to assess various materials for mRNA delivery.

Human iPS-Derived Astroglia from a Stable Neural Precursor State Show Improved Functionality Compared with Conventional Astrocytic Models.

In vivo studies of human brain cellular function face challenging ethical and practical difficulties. Animal models are typically used but display distinct cellular differences. One specific example is astrocytes, recently recognized for contribution to neurological diseases and a link to the genetic risk factor apolipoprotein E (APOE). Current astrocytic in vitro models are questioned for lack of biological characterization. Here, we report human induced pluripotent stem cell (hiPSC)-derived astroglia (NES-Astro) developed under defined conditions through long-term neuroepithelial-like stem (ltNES) cells. We characterized NES-Astro and astrocytic models from primary sources, astrocytoma (CCF-STTG1), and hiPSCs through transcriptomics, proteomics, glutamate uptake, inflammatory competence, calcium signaling response, and APOE secretion. Finally, we assess modulation of astrocyte biology using APOE-annotated compounds, confirming hits of the cholesterol biosynthesis pathway in adult and hiPSC-derived astrocytes. Our data show large diversity among astrocytic models and emphasize a cellular context when studying astrocyte biology.

Target Deconvolution Efforts on Wnt Pathway Screen Reveal Dual Modulation of Oxidative Phosphorylation and SERCA2.

Wnt signaling is critical for development, cell proliferation and differentiation, and mutations in this pathway resulting in constitutive signaling have been implicated in various cancers. A pathway screen using a Wnt-dependent reporter identified a chemical series based on a 1,2,3-thiadiazole-5-carboxamide (TDZ) core with sub-micromolar potency. Herein we report a comprehensive mechanism-of-action deconvolution study toward identifying the efficacy target(s) and biological implication of this chemical series involving bottom-up quantitative chemoproteomics, cell biology, and biochemical methods. Through observing the effects of our probes on metabolism and performing confirmatory cellular and biochemical assays, we found that this chemical series inhibits ATP synthesis by uncoupling the mitochondrial potential. Affinity chemoproteomics experiments identified sarco(endo)plasmic reticulum Ca2+ -dependent ATPase (SERCA2) as a binding partner of the TDZ series, and subsequent validation studies suggest that the TDZ series can act as ionophores through SERCA2 toward Wnt pathway inhibition.

Role of B Cell-Activating Factor in Chronic Obstructive Pulmonary Disease.

RATIONALE: B cell-activating factor (BAFF) plays a major role in activation of B cells and in adaptive humoral immune responses. In chronic obstructive pulmonary disease (COPD), lymphoid follicles have been associated with disease severity, and overexpression of BAFF has been demonstrated within lymphoid follicles of patients with severe COPD. OBJECTIVES: To investigate expression and localization of BAFF in the lungs of patients with COPD and to study the role of BAFF in COPD by antagonizing BAFF in a mouse model of chronic cigarette smoke (CS) exposure. METHODS: We quantified and localized BAFF expression in lungs of never-smokers, smokers without COPD, and patients with COPD and in lungs of air- or CS-exposed mice by reverse-transcriptase polymerase chain reaction, ELISA, immunohistochemistry, and confocal imaging. Next, to investigate the role of BAFF in COPD, we antagonized BAFF by prophylactic or therapeutic administration of a soluble fusion protein of the BAFF-receptor, BAFFR-Fc, in mice exposed to air or CS for 24 weeks and evaluated several hallmarks of COPD and polarization of lung macrophages. MEASUREMENTS AND MAIN RESULTS: BAFF expression was significantly increased in lungs of patients with COPD and CS-exposed mice. BAFF staining in lymphoid follicles was observed around B cells, CD4(+) cells, dendritic cells, follicular dendritic cells, and fibroblastic reticular cells. Prophylactic and therapeutic administration of BAFFR-Fc in mice reduced pulmonary B-cell numbers and prevented CS-induced formation of lymphoid follicles and increases in immunoglobulin levels. Interestingly, prophylactic BAFFR-Fc administration significantly attenuated pulmonary inflammation and destruction of alveolar walls. Moreover, antagonizing BAFF altered the phenotype of alveolar and interstitial macrophages. CONCLUSIONS: BAFF is significantly increased in lungs of patients with COPD and is present around both immune and stromal cells within lymphoid follicles. Antagonizing BAFF in CS-exposed mice attenuates pulmonary inflammation and alveolar destruction.

Long-term chronic toxicity testing using human pluripotent stem cell-derived hepatocytes.

Human pluripotent stem cells (hPSC) have the potential to become important tools for the establishment of new models for in vitro drug testing of, for example, toxicity and pharmacological effects. Late-stage attrition in the pharmaceutical industry is to a large extent caused by selection of drug candidates using nonpredictive preclinical models that are not clinically relevant. The current hepatic in vivo and in vitro models show clear limitations, especially for studies of chronic hepatotoxicity. For these reasons, we evaluated the potential of using hPSC-derived hepatocytes for long-term exposure to toxic drugs. The differentiated hepatocytes were incubated with hepatotoxic compounds for up to 14 days, using a repeated-dose approach. The hPSC-derived hepatocytes became more sensitive to the toxic compounds after extended exposures and, in addition to conventional cytotoxicity, evidence of phospholipidosis and steatosis was also observed in the cells. This is, to the best of our knowledge, the first report of a long-term toxicity study using hPSC-derived hepatocytes, and the observations support further development and validation of hPSC-based toxicity models for evaluating novel drugs, chemicals, and cosmetics.

15-deoxy-Delta12,14-prostaglandin J2 inhibits the expression of microsomal prostaglandin E synthase type 2 in colon cancer cells.

Prostaglandin (PG) E(2) (PGE(2)) plays a predominant role in promoting colorectal carcinogenesis. The biosynthesis of PGE(2) is accomplished by conversion of the cyclooxygenase (COX) product PGH(2) by several terminal prostaglandin E synthases (PGES). Among the known PGES isoforms, microsomal PGES type 1 (mPGES-1) and type 2 (mPGES-2) were found to be overexpressed in colorectal cancer (CRC); however, the role and regulation of these enzymes in this malignancy are not yet fully understood. Here, we report that the cyclopentenone prostaglandins (CyPGs) 15-deoxy-Delta(12,14)-PGJ(2) and PGA(2) downregulate mPGES-2 expression in the colorectal carcinoma cell lines Caco-2 and HCT 116 without affecting the expression of any other PGES or COX. Inhibition of mPGES-2 was subsequently followed by decreased microsomal PGES activity. These effects were mediated via modulation of the cellular thiol-disulfide redox status but did not involve activation of the peroxisome proliferator-activated receptor gamma or PGD(2) receptors. CyPGs had antiproliferative properties in vitro; however, this biological activity could not be directly attributed to decreased PGES activity because it could not be reversed by adding PGE(2). Our data suggest that there is a feedback mechanism between PGE(2) and CyPGs that implicates mPGES-2 as a new potential target for pharmacological intervention in CRC.

Non-specific effects of leukotriene synthesis inhibitors on HeLa cell physiology.

We examined the effects of various leukotriene synthesis inhibitors on calcium signalling in HeLa cells, before and after transfection with BLT(1). All of the inhibitors studied were found to reduce increases in intracellular calcium concentration induced by BLT(1), but also by an ionophore or activation of various G-protein coupled receptors, regardless of BLT(1) expression. In order to explore the mechanism of these apparently general effects we examined HeLa cell expression of leukotriene receptors and biosynthetic enzymes and found that the genes for key leukotriene synthesis enzymes and all of the leukotriene receptors were not expressed. Leukotrienes are involved in the pathology of a variety of cancers, and for HeLa cells leukotrienes have been reported to be important for aspects of the carcinogenic phenotype. We find that leukotriene synthesis inhibitors have non-specific effects, so careful controls are necessary to avoid interpreting non-specific effects as evidence for leukotriene involvement.

Pro- and anti-inflammatory substances modulate expression of the leukotriene B4 receptor, BLT1, in human monocytes.

The high-affinity leukotriene B(4) (LTB(4)) receptor, BLT1, is a chemotactic receptor involved in inflammatory responses. In this study, we have explored the regulation of BLT1 expression in human monocytes by pro- and anti-inflammatory cytokines, lipopolysaccharide (LPS), and dexamethasone. We found that proinflammatory mediators, such as interferon-gamma (IFN-gamma), tumor necrosis factor-alpha, and LPS, down-regulated expression, whereas the anti-inflammatory cytokine, interleukin-10, and dexamethasone up-regulated BLT1 mRNA expression. The effect of IFN-gamma on BLT1 mRNA expression was rapidly detectable (<4 h) and concentration-dependent (1-50 ng/ml) and seems to be exerted through a block in transcriptional activity. Alterations in mRNA expression were accompanied by changes in BLT1 surface expression, and receptor down-modulation following IFN-gamma stimulation resulted in a diminished chemotactic response to LTB(4). The regulation of BLT1 mRNA and receptor protein expression was similar to the regulation of the monocyte chemoattractant protein-1 chemokine receptor, CC chemokine recptor 2 (CCR2). Flow cytometric analysis of fresh peripheral blood cells revealed that classical (CD14(++)CD16(-)) monocytes express high levels of BLT1 and CCR2 and that both receptors are down-regulated on CD14(+)CD16(+) monocytes. Apart from providing insight into the regulation of BLT1 in human monocytes, our results reveal a parallel expression and regulation of BLT1 and CCR2, which may help to understand monocyte trafficking during pathophysiological conditions.