Baicalin Ameliorates DSS-Induced Colitis by Protecting Goblet Cells through Activating NLRP6 Inflammasomes

OBJECTIVE: Baicalin is an active compound found in many natural herbs and has been used to treat intestinal disorders such as diarrhea and colon cancer. In this study, we used a dextran sodium sulfate (DSS)-induced colitis mouse model to investigate baicalin's mechanisms in the treatment of colitis. METHODS: 3% DSS was administered through the drinking supply for 7 days to induce colitis followed by the administration of 5-aminosalicylic acid and baicalin at three different doses (25, 50, and 100 mg/kg, W/W) for an additional 7 days. Body weight, stool consistency, and colon length were recorded. Colon tissue was stained with hematoxylin and eosin (H&E) to be used for histopathological scoring. Cytokine levels of the colon tissue and serum were evaluated using real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. mRNA expression and protein levels of tight junctions (TJs) were detected with qRT-PCR and Western blotting. Goblet cells and the mucosal layer of the colon were visualized by Alcian Blue/periodic acid-Schiff (AB/PAS) staining. Mucin 2 (MUC2) was evaluated in both mRNA expression and protein levels. Nod-like receptor pyrin domain-containing protein 6 (NLRP6) inflammasomes were detected by immunohistochemistry and Western blotting. RESULTS: Treatment with baicalin significantly relieved colitis as evidenced by reversing both weight loss and colon length shortening. In addition, baicalin inhibited inflammation by reducing proinflammatory cytokines and protected the intestinal barrier by upregulating tight junction proteins. Moreover, goblet cell count and intestinal mucosa thickness were both significantly increased after baicalin treatment. Giving baicalin could upregulate the expression of NLRP6 and interleukin (IL-18) both in mRNA and protein. CONCLUSION: Baicalin ameliorates DSS-induced colitis by protecting goblet cells through activating NLRP6 inflammasomes.