Abstract
Pro-resolving factors that are critical for colonic epithelial restitution were down-regulated during the treatment with inhibitor of pro-inflammatory cytokines (e.g., anti-TNFα antibody) in ulcerative colitis (UC) therapy. We hypothesized that increased amounts of factors such as interleukin-22 (IL-22) during the therapeutic inhibition of TNFα could facilitate the resolution of intestinal inflammation. As combination therapy is an emerging strategy for UC treatment, we attempt to treat established UC based on the combination of TNFα siRNA (siTNF) and IL-22. Initially, we loaded siTNF into galactosylated polymeric nanoparticles (NPs). The resultant Gal-siTNF-NPs had a desirable average diameter (~261 nm), a narrow size distribution and a slightly negative surface charge (~-6 mV). These NPs successfully mediated the targeted delivery of siTNF to macrophages and efficiently inhibited the expression of TNFα. Meanwhile, IL-22 could obviously accelerate mucosal healing. More importantly, oral administration of Gal-siTNF-NPs plus IL-22 embedded in a hydrogel (chitosan/alginate) showed much stronger capacities to down-regulate the expression of pro-inflammatory factors and promote mucosal healing. This formulation also yielded a much better therapeutic efficacy against UC in a mouse model compared to hydrogel loaded with Gal-siTNF-NPs or IL-22 alone. Our results strongly demonstrate that Gal-siTNF-NP/IL-22-embedded hydrogel can target to inflamed colon, and co-deliver siTNF and IL-22 to boost the effects of either monotherapy, which may become a promising oral drug formulation and enable targeted combination therapy of UC.