Biology subjects

Muir, R.

Publications and source records attributed to Muir, R..

3 recordsLinked to original sources

bioRxiv2026

Macrophage-derived extracellular vesicles promote T cell-dependent inflammatory pain resolution

Inflammatory pain resolution is increasingly recognized as an active, immune-regulated process, yet the adaptive immune mechanisms that govern this process remain poorly defined. We previously demonstrated that intrathecal administration of macrophage-derived small extracellular vesicles (sEVs) from unstimulated (sEV) or LPS-stimulated (sEV+) RAW 264.7 cells accelerate resolution of complete Freunds adjuvant (CFA)-induced inflammatory pain in male mice. However, the immunological mechanisms underlying this effect remain undefined. Given growing evidence that T cells regulate inflammatory pain resolution, we investigated whether macrophage-derived sEVs engage adaptive immune pathways to promote recovery. In vitro, both sEV and sEV+ enhanced T cell activation, with sEV+ exhibiting greater immunostimulatory capacity. Direct effects on T cells were modest; instead, sEV+ induced robust antigen-presenting cell (APC)-dependent T cell activation characterized by increased costimulatory molecule expression and enhanced Th1 polarization. Loss-of-function and rescue studies in Rag2-/- mice demonstrate that T cells are required for late-phase sEV+-mediated inflammatory pain resolution. In vivo, sEV+ elicited immunostimulatory responses in intrathecal-draining cervical and CFA-draining sacral/internal iliac lymph nodes. Together, these findings identify adaptive immune engagement as a critical mediator of sEV+-induced pain resolution and position macrophage-derived sEVs as a cell-free immunotherapeutic modality that harnesses endogenous T cell-dependent mechanisms of active inflammatory pain resolution. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/706465v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@e49aa4org.highwire.dtl.DTLVardef@648c9forg.highwire.dtl.DTLVardef@14c3cc6org.highwire.dtl.DTLVardef@2a17f0_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Characterization of a Novel Transmembrane Activating STING Agonist using Genetically Humanized Mice

STING is a pattern recognition receptor that activates type I interferon and proinflammatory responses in addition to unrelated molecular processes following exposure of DNA to the cytosol. Its pharmacologic stimulation enhances vaccine potency and generates effective antitumor responses but clinical trials evaluating STING agonists have not led to approval for human use. STING activation can occur through ligand engagement of either cytosolic or transmembrane protein domains, processes to which distinct cellular phenotypes are attributed. However, the only transmembrane STING agonist identified is human selective and in vivo testing in conventional models is not feasible. Here we describe synthesis of novel STING agonists efficacious against allelic variants of the protein. We also describe genetically humanized STING mice and demonstrate their suitability as a model to evaluate in vivo responses following exogenous administration of human-selective agonists. Experiments demonstrate that the lead molecule (termed INI3069) functions through binding to the STING transmembrane region and its comparison with conventional agonists reveals significant differences in molecular and immune effects. INI3069 can also enhance antibody responses to co-administered antigens and antitumor responses. This work both represents the first in vivo examination of the effects of transmembrane STING agonism and demonstrates efficacy of a potential novel vaccine adjuvant and oncological therapeutic.

immunology↗

bioRxiv2023

Covalent macrocyclic proteasome inhibitors mitigate resistance in Plasmodium falciparum

The Plasmodium proteasome is a promising antimalarial drug target due to its essential role in all parasite lifecycle stages. Furthermore, proteasome inhibitors have synergistic effects when combined with current first-line artemisinins. Linear peptides that covalently inhibit the proteasome are effective at killing parasites and have a low propensity for inducing resistance. However, these scaffolds generally suffer from poor pharmacokinetics and bioavailability. Here we describe the development of covalent, irreversible macrocyclic inhibitors of the P. falciparum proteasome. We identified compounds with excellent potency and low cytotoxicity, however, the first generation suffered from poor microsomal stability. Further optimization of an existing macrocyclic scaffold resulted in an irreversible covalent inhibitor carrying a vinyl sulfone electrophile that retained high potency, low cytotoxicity, and had acceptable metabolic stability. Importantly, unlike the parent reversible inhibitor that selected for multiple mutations in the proteasome, with one resulting in a 5,000-fold loss of potency, the irreversible analog only showed a 5-fold loss in potency for any single point mutation. Furthermore, an epoxyketone analog of the same scaffold retained potency against a panel of known proteasome mutants. These results confirm that macrocycles are optimal scaffolds to target the malarial proteasome and that the use of a covalent electrophile can greatly reduce the ability of the parasite to generate drug resistance mutations.

microbiology↗