Yee, K. K. | bioRxiv Science

bioRxiv2024

Harnessing Synaptic Vesicle Release and Recycling Mechanism for Molecule Delivery to Neurons

Neurodegenerative clinical trials often fail due to insufficient drug doses in reaching targeted cells and the unintended delivery to non-targeted cells. This study demonstrates an alternative neuron-selective drug delivery system, which utilizes the synaptic vesicle release and recycling mechanism (SVRM) by antibody shuttles targeting synaptic vesicle transmembrane proteins for molecule delivery. Using Synaptotagmin-2 (SYT2), we exemplify that intravenously administered anti-SYT2 antibodies localize to neuromuscular junctions, undergo uptake, and retrograde transport to ChAT-positive motor neurons (MNs) in the spinal cord and brainstem. The delivery of anti-microtubule agent and Malat1 gapmer antisense oligonucleotide to MNs with anti-SYT2 antibodies induces axon degeneration and reduction of Malat1 RNA expression, respectively. This approach circumvents the blood-spinal cord barrier, enabling selective delivery of therapeutic molecules to neurons while minimizing effects in non-targeted cells. Thus harnessing SVRM presents a promising strategy for enhancing drug concentrations in neurons and improving treatment efficacy for neurodegenerative diseases.

neuroscience↗

bioRxiv2024

An in vitro modelling of resolving macrophage with Raw 264.7 macrophage cell line

In acute inflammation, macrophages polarises its phenotype in order to participate effectively in the inflammatory, anti-inflammatory and resolving phases. Particularly, the resolving phase is vital for homeostatic recovery. The in vivo murine peritonitis model had identified various subtypes of resolving macrophages. However, the in vivo model has limitations in deciphering the molecular mechanisms required for resolving macrophage polarisation. Therefore the aim of this study is to establish an in vitro model that could simplify the reproduction of resolving macrophage polarisation. This model will be a useful tool to screen for molecular mechanisms essential for triggering resolution. Our in vitro model showed Raw 264.7 cells exhibited classical inflammatory-like (M1-like) phenotype between 2-24 h with increased interleukin-1{beta} expression and tumour necrosis factor- secretion. Concurrently, at 22-24 h there was an increase in Raw 264.7 cells polarising to anti-inflammatory like (M2-like) phenotype. These M2-like macrophages were increased in arginase activity and interleukin-10 expression. By 48 h, Raw 264.7 cells were polarised to resolving-like (Mres-like/CD11blow) phenotype. These macrophages were characterised by high efferocytic index and a decrease in inflammatory cytokine expression, low arginase activity and low CD11b expression. In summary, this in vitro resolution model showed resolving-like polarisation in a macrophage cell line.

cell biology↗