Scutellaria baicalensis-Derived Extracellular Vesicles Alleviate Inflammatory Bowel Disease by Inhibiting the NF-κB/NLRP3 Pathway

Background: Plant-derived extracellular vesicles (PDEV) are emerging as natural nanomedicines for various diseases. Scutellaria baicalensis (S. baicalensis) is a traditional Chinese herb long used to treat intestinal inflammatory bowel disorders (IBD), with its therapeutic effects attributed to bioactive Flavonoids such as baicalin and wogonin. However, whether SEV contribute to its anti-inflammatory activity remains unexplored. The assembled multi-component nature of SEV, which carry Flavonoids, lipids, proteins, and miRNAs, suggests a potential to exert therapeutic effects against IBD through mechanisms distinct from isolated compounds, with potential advantages in bioavailability and multi-target engagement.

Methods: We demonstrated that SEV exert potent antioxidant and anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages and Caco-2 intestinal epithelial cells. Moreover, we assessed the therapeutic effects of SEV on dextran sulfate sodium (DSS)-induced IBD in a murine model.

Results: In inflamed RAW264.7, SEV modulated the NF-κB/NLRP3 signaling axis to exert anti-inflammatory effects. They scavenged Reactive Oxygen Species (ROS), restored mitochondrial membrane potential, upregulated the anti-inflammatory cytokine IL-10, and suppressed the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. In Caco-2 intestinal epithelial cells, SEV also repaired intestinal barrier function by restoring expression of the tight junction proteins Zonula Occludens-1 (ZO-1), Claudin-1, and Occludin (OCLN), alongside reduced TNF-α levels. In vivo, SEV accumulated at colonic inflammatory loci to effectively alleviate IBD, as evidenced by improved body weight and increased colon length. This protective effect was mediated through inhibition of the NF-κB/NLRP3 signaling axis in colon tissues, which subsequently restored intestinal barrier integrity by increasing goblet cell numbers, upregulating OCLN proteins, and enhancing Mucin2 (MUC2) secretion, while simultaneously rebalancing inflammatory cytokines through suppression of TNF-α/IL-1β and promotion of IL-10 production.

Conclusion: SEV have the potential to protect the colon against DSS-induced colitis by inhibiting the NF-κB/NLRP3 signaling pathway, providing a promising therapeutic candidate for IBD.