3.3 TBⅡ mitigated DSS-induced colitis via inhibiting NLRP3 signaling
To comprehensively unveil the underlying mechanism involved in the protective role of TBⅡ in the colon of DSS-induced colitis mice, RNA sequencing of control, DSS and TBⅡ-treated colon tissue was performed. First, KEGG analysis showed obvious enrichment of various inflammatory signaling including NOD-like receptor signaling pathway, which played an important role in intestinal immune response, and NLRP3 quickly became an important regulator of intestinal homeostasis (Figure 3A and B). Heat maps further showed that the enrichment of down-regulated genes treated with TB-Ⅱ was significantly affected in multiple inflammatory pathway signals with NOD-like receptor pathways (Figure 3C). Given that the role of NLRP3, an inflammasome with apoptosis-associated speck-like protein (ASC) and the effector molecule pro-caspase-1 that is closely associated with development of inflammatory bowel disease (IBD) (Bauer et al., 2010), in NOD like receptor proteins has been extensively characterized and studied (Dick, Sborgi, Rühl, Hiller & Broz, 2016), we subsequently performed on the determination of NLRP3 expression. Similar to the heatmap results, we confirmed that the protein expression levels of NLRP3, ASC, CASP1 and IL-1β were obviously elevated in DSS-treated mice compared with control mice, whereas TBⅡ treatment significantly inhibited NLRP3 signaling-associated protein expression in a dose-dependent manner (Figure 3D). Together, these results suggested that the mitigation of TBⅡ in DSS-induced colitis may likely be related to the inhibition of NLRP3 signaling.