The sinomenine enteric-coated microspheres suppressed the TLR/NF-κB signaling in DSS-induced experimental colitis

- Sinomenine inhibits TLRs/NF-κB p65 signaling pathway in DSS-induced colitis of mice in vivo.
- Eudragit-coated sinomenine chitosan microspheres had better therapeutic effect than unencapsulated sinomenine.
- Enteric-coated sinomenine represents a potential candidate drug for immunoregulation in inflammatory bowel disease.

Sinomenine is a pure alkaloid with immunosuppressive effects that is extracted from the Chinese medicinal plant Sinomenium acutum. We studied the therapeutic effects of sinomenine on inflammatory bowel disease. In this study, we randomly divided mice into the following ten groups: Control group; DSS-induced colitis group; Salicylazosulfapyridine (SASP)-treated group; Chitosan-treated group; low-, medium-, and high-dose sinomenine-treated and sinomenine enteric-coated microspheres-treated groups. We recorded changes in colon length, disease activity index (DAI), and colon pathology, measured TLR4, MyD88, SIGIRR, NF-κB p65 protein levels and inflammatory serum cytokine levels.Except for the Control group, the weight of mice in each group decreased, the DAI of the DSS-induced colitis group was significantly higher than the other groups, and the DAIs of the sinomenine- and sinomenine enteric-coated microspheres-treated groups were significantly lower than that of the SASP-treated group. TLR4, MyD88, NF-κB p65 and proinflammatory cytokine expressions decreased dose dependently in the sinomenine and sinomenine enteric-coated microspheres-treated groups and were generally lower in the sinomenine enteric-coated microspheres groups. However, SIGIRR and anti-inflammatory IL-10 expressions exhibited the opposite pattern. Based on the superior therapeutic effect, sinomenine enteric-coated microspheres might regulate TLR/NF-κB signaling and would be beneficial for an effective and safe therapy of inflammatory bowel disease.