Core-shell engineered Col/Cs@ECM microspheres for macrophage-targeted intracellular drug release in RA therapy

The imbalance of macrophage polarization between M1 and M2 phenotypes in rheumatoid arthritis (RA) results in a persistent inflammatory cascade. Activating M2 anti-inflammatory polarization, which remove excess extracellular matrix (ECM) via phagocytosis, represents a potential therapeutic target for RA. This study introduces Col/Cs@ECM microspheres, a novel drug delivery system designed for macrophage recognition via a tailored ECM surface, enhancing phagocytic efficiency and accumulation. Moreover, the Col/Cs@ECM microspheres are composed of biocompatible and fully degradable materials, ensuring their safety profile within the physiological environment. Following cell phagocytosis, the collagen/chitosan (Col/Cs) core release the drug (Dexamethasone, Dex) intracellularly to inhibit M1 polarization by inhibiting the NF-κB signaling pathway and to facilitate M2 polarization. This macrophage targeted and intracellular release approach offers a significant advantage over traditional medications by reducing systemic side effects and improving the therapeutic index. The strategy prompts macrophages to express anti-inflammatory cytokines like IL-10 while suppressing pro-inflammatory cytokines such as TNF-α, thereby remodeling the immune microenvironment. Additionally, the specially engineered ECM shell of the microspheres extends the anti-inflammatory response by prolonging macrophage lifespan, a feature that is not present in conventional treatments. This results in improved treatment outcomes in an in vivo RA animal model. This research presents a possible intracellular anti-inflammatory treatment approach for rheumatoid arthritis injection therapy with the potential to outperform existing treatments in terms of efficacy and safety. From preparation to therapeutic efficacy: the journey of Col/Cs@ECM microspheres in targeting macrophages for RA treatment. I. Preparation of Col/Cs@ECM microsphere. This part illustrates two steps in fabrication process, Col/Cs microspheres copolymerization and ECM micro-sheet crosslinking. II. Macrophage phagocytose microspheres to M2 polarization. The first step is macrophage's pattern recognition of ECM shell. Then, the recognition enhanced phagocytosis and the microspheres were internalized into phagosome. The Dex released from microspheres due to the acid lysosome fusion. Finally, the NF-κB/STAT6 signal pathway was depressed and the polarization shifted to the M2 anti-inflammation stereotype. III. Intracellular RA therapy by microspheres injection in vivo. The RA animal model was induced by CAIA method in C57BL/6 mice, and the microspheres were injected into the joints. • Macrophage-targeted drug delivery for RA therapy using Col/Cs@ECM microspheres. • ECM shell enhances macrophage recognition and prolongs anti-inflammatory state. • Acidic lysosome-responsive Col/Cs core for precise Dex release. • Lesion site injection offers efficient, systemic side-effect-free RA treatment. • Mouse studies validate Col/Cs@ECM microspheres' therapeutic efficacy in RA.