XA pH-Responsive and Colitis-Targeted Nanoparticle Loaded with Shikonin for the Oral Treatment of Inflammatory Bowel Disease in Mice

Epidemiology shows that more than 6.8 million people in the world are influenced by inflammatory bowel disease (IBD) each year. IBD is a refractory inflammatory disease, and the disease mainly affects the colon. Shikonin (SK) was originally extracted from traditional Chinese medicine "Zicao" (with an English name Lithospermum erythrorhizon) and found to inhibit inflammation, regulate immunity, and be involved in healing wounds. Herein, we used chitosan (CS), hyaluronic acid (HA), and pH-responsive polymer Eudragits S100 (ES100) to design SK-loaded ES100/HA/CS nanoparticles (SK@SAC) as an oral delivery system to treat the colitis mice. Particle size of SK@SAC was 190.3 nm and drug loading efficiency was 6.6%. SAC nanoparticles accumulated in RAW264.7 macrophages and exhibited colitis-targeted ability by increasing the local drug concentration as well as reducing nonspecific distribution after oral gavage. In TNBS-induced IBD mice, SK@SAC treatment had significant therapeutic effects, regulated of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and anti-inflammatory cytokines (IL-10 and TGF-β), and also inhibited COX-2 and iNOS activity. SK@SAC also increased tight junction protein ZO-1 and occludin to some extent. These promising results showed that this novel oral SK-loaded nanoparticle drug delivery system for targeted treatment provides a new strategy for the management of IBD.