Curcumin Suppresses the Activity of Inhibitor-κB Kinase in an in vitro Inflamed Human Intestinal Mucosa Model by S -nitrosylation

Abstract

In previous study, we found curcumin to possess anti-inflammatory properties in lipopolysaccharide (LPS)-induced macrophage cells due to the involvement of curcumin and S-nitrosylation in the NF-κB pathway. However, the role of curcumin on regulation of NF-κB signaling pathway through S-nitrosylation in an in vitro inflamed human intestinal mucosa model has not yet been elucidated. This study aimed to concern inhibitory effects of curcumin on NF-κB pathway in two type of inflamed human intestinal cells, Caco-2 and HT-29. Western blot presented the protein expression of iNOS can be reduced by treated curcumin with 30 μM for 12h. Consistently, pro-inflammatory cytokines, such as IL-1β, IL-6, TNFα and IFN-γ was also repressed. The results also shows curcumin reduced the amount of nitrite and nitrate in inflamed human intestinal cells, Caco-2 and HT-29, maintained total S-nitrosylation level on proteins. Furthermore, the protection of S-nitrosylation on IKKβ in inflamed Caco-2 and HT-29 cells by curcumin caused the repression of IκB phosphorylation and NF-κB activation. In conclusion, this study verified that curcumin-mediated S-nitrosylation may be as an important regulator for anti-inflammation in an in vitro inflamed human intestinal mucosa model.