Huangqin Decoction Attenuates DSS-Induced Mucosal Damage and Promotes Epithelial Repair via Inhibiting TNF-α-Induced NF-κB Activation.

Objective: To investigate the protective effect of Chinese herbal formula Huangqin Decoction (HQD) on ulcerative colitis mouse model induced by dextran sulphate sodium (DSS) and human intestinal epithelial cell injury induced by tumour necrosis factor-α (TNF-α).

Methods: In vivo, 30 male C57BL/6 mice were divided into 5 groups using a random number table (n=6 per group), including control, DSS, 5-aminosalicylic acid (5-ASA), HQD low- (HQD-L) and high-dose (HQD-H) groups. The colitis mouse model was established by 3% (w/v) DSS water for 5 days. Meanwhile, mice in the HQD-L, HQD-H and 5-ASA groups were administrated with 100, 200 mg/kg HQD or 100 mg/kg 5-ASA, respectively, once daily by gavage. After 9 days of administration, the body weight, disease activity index (DAI) score and colon length of mice were measured, the pathological changes of colons were analyzed by hematoxylin-eosin staining (HE) staining, and the levels of serum interleukin (IL)-6, IL-1β and TNF-α were measured by enzyme linked immunosorbent assay. In vitro, the human colon epithelial normal cells (FHC cells) were exposed to HQD (0.6 mg/mL) for 12 h and then treated with TNF-α (10 ng/mL) for 24 h. The tight junction (TJ) protein expression levels of Claudin-4 and Occludin, and the protein phosphorylation levels of p65 and inhibitor of nuclear factor kappaB (NF-κB)-α (IκBα) were measured by Western blot.

Results: In vivo, compared with the DSS group, HQD-H treatment attenuated the weight loss and reduced DAI score of mice on the 8th day (P<0.05). Moreover, HQD-H treatment ameliorated the colon shortening in the DSS-induced colitis mice (P<0.05). HE staining showed HQD attenuated the pathological changes of colitis mice, and the histological scores of HQD-H and 5-ASA groups were significantly decreased compared with the DSS group (P<0.05). Meanwhile, HQD-H and 5-ASA significantly decreased the serum IL-1β, IL-6 and TNF-α levels of mice (P<0.05). In vitro experiments showed that HQD up-regulated Occludin and Claudin-4 protein expressions and inhibited p-p65 and p-IκBα levels in FHC cells compared with the TNF-α group (P<0.05).

Conclusion: HQD significantly relieved the symptoms in DSS-induced colitis mice by inhibiting pro-inflammatory cytokines expression and maintained the homeostasis of TJ protein in FHC cells by suppressing TNF-α-induced NF-κB activation.