Transcriptomic analysis reveals a controlling mechanism for NLRP3 and IL-17A in dextran sulfate sodium (DSS)-induced colitis

The incidence of inflammatory bowel disease (IBD) has markedly increased. Our research findings during the past showed that medicinal plant extracts and the derived phytochemical components from Wedelia chinensis (WC) can have strong anti-colitis activities. Here, we further identified the key component phytochemicals from active fractions of different WC preparations (WCHA) that are responsible for the protective effect of WCHA in colitis mice. Of the 3 major compounds (wedelolactone, luteolin and apigenin) in this fraction, luteolin had the highest anti-inflammatory effect in vivo. Using a next-generation sequencing (NGS) (e.g., RNA-seq) system to analyze the transcriptome of colorectal cells/tissues in mice with dextran sulfate sodium (DSS)-induced colitis with/without phytochemicals treatment, luteolin was found to strongly suppress the DSS-activated IL-17 pathway in colon tissue. In addition, co-treatment with wedelolactone and luteolin had a synergistic effect on the expression level of some IL-17 pathway-related genes. Interestingly, our NGS analyses also indicated that luteolin and wedelolactone can specifically suppress the expression of NLRP3 and NLRP1. Using a 3-dimensional cell co-culture system, we further demonstrated that luteolin could efficiently suppress NLRP3 expression via disruption of IL-17A signaling in inflamed colon tissue, which also indicates the pharmacological potential of luteolin and wedelolactone in treating IBD.