Hyaluronic acid-coated polypeptide nanogel enhances specific distribution and therapy of tacrolimus in rheumatoid arthritis.

Rheumatoid arthritis (RA) involves chronic inflammation, oxidative stress, and complex immune cell interactions, leading to joint destruction. Traditional treatments are often limited by off-target effects and systemic toxicity. This study introduces a novel therapeutic approach using hyaluronic acid (HA)-conjugated, redox-responsive polyamino acid nanogels (HA-NG) to deliver tacrolimus (TAC) specifically to inflamed joints. The nanogels' disulfide bonds enable controlled TAC release in response to high intracellular glutathione (GSH) levels in activated macrophages, prevalent in RA-affected tissues. In vitro results demonstrated that HA-NG/TAC significantly reduced TAC toxicity to normal macrophages and showed high biocompatibility. In vivo, HA-NG/TAC accumulated more in inflamed joints compared to non-targeted NG/TAC, enhancing therapeutic efficacy and minimizing side effects. Therapeutic evaluation in collagen-induced arthritis (CIA) mice revealed HA-NG/TAC substantially reduced paw swelling, arthritis scores, synovial inflammation, and bone erosion while suppressing pro-inflammatory cytokine levels. These findings suggest that HA-NG/TAC represents a promising targeted drug delivery system for RA, offering potential for more effective and safer clinical applications.