12 research outputs found
Supramolecular Assembly of AminoethyleneâLipopeptide PMO Conjugates into RNA SpliceâSwitching Nanomicelles
Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of preâmRNA splicing. Similar to other classes of nucleic acidâbased therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinylâtetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strainâpromoted azideâalkyne cycloaddition conjugation with spliceâswitching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest spliceâswitching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2Kâmdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant spliceâswitching at very low nanomolar concentrations. The presented aminoethyleneâlipopeptides are thus a promising platform for the generation of PMOâtherapeutics with a favorable activity/toxicity profile
Tuning the Morphological Appearance of Iron(III) Fumarate: Impact on Material Characteristics and Biocompatibility
Iron(III) fumarate materials are well suited for biomedical applications as they feature biocompatible building blocks, porosity, chemical functionalizability, and magnetic resonance imaging (MRI) activity. The synthesis of these materials however is difficult to control, and it has been challenging to produce monodisperse particle sizes and morphologies that are required in medical use. Here, we report the optimization of iron(III) fumarate nano- and microparticle synthesis by surfactant-free methods, including room temperature, solvothermal, microwave, and microfluidic conditions. Four variants of iron(III) fumarate with distinct morphologies were isolated and are characterized in detail. Structural characterization shows that all iron(III) fumarate variants exhibit the metalâorganic framework (MOF) structure of MIL-88A. Nanoparticles with a diameter of 50 nm were produced, which contain crystalline areas not exceeding 5 nm. Solvent-dependent swelling of the crystalline particles was monitored using in situ X-ray diffraction. Cytotoxicity experiments showed that all iron(III) fumarate variants feature adequate biotolerability and no distinct interference with cellular metabolism at low concentrations. Magnetic resonance relaxivity studies using clinical MRI equipment, on the other hand, proved that the MRI contrast characteristics depend on particle size and morphology. All in all, this study demonstrates the possibility of tuning the morphological appearance of iron(III) fumarate particles and illustrates the importance of optimizing synthesis conditions for the development of new biomedical materials
Introducing relational work in Facebook, discussion boards and New Media events
This paper functions as the introduction to the special issue on ârelational work in Facebook and discussion boardsâ. We position our research endeavors within interpersonal pragmatics (see Locher and Graham 2010), by reviewing literature on politeness, impoliteness and relational work in the context of computer-mediated communication. Foregrounding the relational aspect of language, we are particularly interested in establishing the connections between politeness, face and linguistic identity construction. We then position the four papers that form this special issue within this field of research. Two papers contribute to the study of relational work on discussion boards (Kleinke and Boes; Haugh, Chang and KĂĄdĂĄr) and two deal with practices on Facebook (Theodoropoulou; Bolander and Locher)
Peptide nucleic acid-zirconium coordination nanoparticles
Abstract Ideal drug carriers feature a high loading capacity to minimize the exposure of patients with excessive, inactive carrier materials. The highest imaginable loading capacity could be achieved by nanocarriers, which are assembled from the therapeutic cargo molecules themselves. Here, we describe peptide nucleic acid (PNA)-based zirconium (Zr) coordination nanoparticles which exhibit very high PNA loading of > 94 % w/w. This metal-organic hybrid nanomaterial class extends the enormous compound space of coordination polymers towards bioactive oligonucleotide linkers. The architecture of single- or double-stranded PNAs was systematically varied to identify design criteria for the coordination driven self-assembly with Zr(IV) nodes at room temperature. Aromatic carboxylic acid functions, serving as Lewis bases, and a two-step synthesis process with preformation of Z r 6 O 4 ( O H ) 4 turned out to be decisive for successful nanoparticle assembly. Confocal laser scanning microscopy confirmed that the PNA-Zr nanoparticles are readily internalized by cells. PNA-Zr nanoparticles, coated with a cationic lipopeptide, successfully delivered an antisense PNA sequence for splicing correction of the ÎČ -globin intron mutation IVS2-705 into a functional reporter cell line and mediated splice-switching via interaction with the endogenous mRNA splicing machinery. The presented PNA-Zr nanoparticles represent a bioactive platform with high design flexibility and extraordinary PNA loading capacity, where the nucleic acid constitutes an integral part of the material, instead of being loaded into passive delivery systems
Apoptosis inducing factor (AIF) is essential for neuronal cell death following transient focal cerebral ischemia
CD4+ T cell-induced inflammatory cell death controls immune-evasive tumours
Most clinically applied cancer immunotherapies rely on the ability of CD8+ cytolytic T cells to directly recognize and kill tumour cells1,2,3. These strategies are limited by the emergence of major histocompatibility complex (MHC)-deficient tumour cells and the formation of an immunosuppressive tumour microenvironment4,5,6. The ability of CD4+ effector cells to contribute to antitumour immunity independently of CD8+ T cells is increasingly recognized, but strategies to unleash their full potential remain to be identified7,8,9,10. Here, we describe a mechanism whereby a small number of CD4+ T cells is sufficient to eradicate MHC-deficient tumours that escape direct CD8+ T cell targeting. The CD4+ effector T cells preferentially cluster at tumour invasive margins where they interact with MHC-II+CD11c+ antigen-presenting cells. We show that T helper type 1 cell-directed CD4+ T cells and innate immune stimulation reprogramme the tumour-associated myeloid cell network towards interferon-activated antigen-presenting and iNOS-expressing tumouricidal effector phenotypes. Together, CD4+ T cells and tumouricidal myeloid cells orchestrate the induction of remote inflammatory cell death that indirectly eradicates interferon-unresponsive and MHC-deficient tumours. These results warrant the clinical exploitation of this ability of CD4+ T cells and innate immune stimulators in a strategy to complement the direct cytolytic activity of CD8+ T cells and natural killer cells and advance cancer immunotherapies.Title in Web of Science: CD4(+) T cell-induced inflammatory cell death controls immune-evasive tumours</p