Biology subjects

Radloff, K.

Publications and source records attributed to Radloff, K..

3 recordsLinked to original sources

bioRxiv2026

mRNA/LNP-mediated expression of a ligand-independent Tie2 pathway activator, COMP-Tie2*, enables sustained endothelial stabilization

Activation of the angiopoietin/Tie2 signaling axis is a validated strategy for endothelial stabilization. However, therapeutic Tie2 activation via angiopoietin-1 (Ang1) or Ang1-derived agonists is intrinsically limited due to several mechanism including ligand instability, competitive Ang2 inhibition, Tie2 ectodomain cleavage, VE-PTP-mediated Tie2 dephosphorylation, and ligand-induced receptor degradation. All these inhibitory mechanisms restrict both magnitude as well as duration of therapeutic Tie2 signaling, particularly under inflammatory conditions such as acute respiratory distress syndrome (ARDS) or sepsis. Here, we describe a novel ligand-independent strategy for sustained Tie2 activation based on engineered membrane-anchored Tie2 variants. By combining intracellular Tie2 kinase domains harboring naturally occurring autoactivating mutations with heterologous membrane-targeting domains, we generated truncated, constitutively active Tie2 variants that bypass extracellular ligand regulation entirely. mRNA-mediated expression of these constructs induced robust and persistent Tie2 autophosphorylation and downstream Akt-FOXO1 signaling in pulmonary endothelial cells, which exceeded COMP-Ang1-mediated activation in both strength and duration. Systemic administration of COMP-Tie2* mRNA using lung-targeted lipid nanoparticles resulted in selective pulmonary Tie2 receptor engagement in vivo. Collectively, these data establish LNP-mediated mRNA delivery of engineered recombinant receptors for intrinsic Tie2 activation as a promising novel approach for endothelial stabilization under inflammatory conditions.

cell biology↗

bioRxiv2026

Translational Pharmacokinetics and Pharmacodynamics of a Cationic mRNA-Lipid Nanoparticle from Mice to Non-Human Primates

Cationic lipid nanoparticles have demonstrated unique potential for extrahepatic mRNA delivery, particularly enabling selective targeting of the pulmonary endothelium. However, their translational development has been hampered by reports of infusion-related immune reactions and innate immune system activation, most notably transient complement activation. Here, we present a case study illustrating the discovery and translational advancement of a selected cationic LNP into non-human primates (NHPs) for initial pharmacokinetic assessment and evaluation of potential immunostimulatory side effects. We show surface charge dependent organ-selective expression of reporter mRNAs from different LNPs in vivo. An mRNA encoding the Tie2 agonist COMP-Angl, was formulated with LNP002, and respective pharmacokinetic and pharmacodynamic readouts were analyzed in two independent non-human primate studies. Notably, dose-dependent transient complement activation could be abrogated by extending the infusion time. Finally, we identified the blood-borne pharmacodynamic biomarker PDGFB for LNP002/mRNA-76 treatment reflecting activated Tie2-signalling in healthy pulmonary endothelium in vivo supported by single cell sequencing and cluster-alignment of downstream effector genes with the same spatial profile as the delivered mRNA.

pharmacology and toxicology↗

bioRxiv2022

Spatial expression of an mRNA encoding Tie2-agonist in the capillary endothelium of the lung prevents pulmonary vascular leakage

Angiopoietin ligands Ang1 and Ang2 and the Tie2 receptor tyrosine kinases form an endothelial signaling pathway regulating vascular homeostasis and controlling vessel permeability, inflammation and angiogenic responses. Whereas Ang1-mediated Tie2 activation reduces inflammation and endothelial permeability, its antagonist, Ang2 increases it. Increased plasma Ang2 levels are associated with poor outcomes in patients with acute lung injury (ALI), as well as in acute respiratory distress syndrome (ARDS). In the study presented here we tested the effect of a novel synthetic, nucleoside-modified mRNA-76 encoding for a hyperactive Ang1 derived fusion protein (COMP-Ang1) on attenuating post-inflammation vascular leakage. COMP-Ang1 mRNA was formulated into a cationic lipid nanoparticle (cLNP) using an optimized mixture of three different lipids and a microfluidic mixing technology. After intravenous injection, the respective mRNA-loaded LNPs were found to be delivered predominantly to the endothelial cells of the lung, while sparing other vascular beds. Also, the specific multimeric folding of the COMP-Ang1 protein complex appeared to be pivotal for its activity in preventing vascular leakage and in restoring the alveolar-endothelial barrier function in the inflamed and injured pulmonary vasculature. The mode of action of mRNA-76, such as its activation of the Tie2 signal transduction pathway, was tested by pharmacological studies in vitro and in vivo by systemic administration in respective mouse models. mRNA-76 was found to prevent lung vascular leakage/lung edema as well as neutrophil infiltration in an LPS-challenging model.

molecular biology↗