Bufalin Inhibits Cytokine Storm by Regulating TLR4/TLR3 Signaling Pathway

BACKGROUND: Bufalin is one main component of the dried venom from Bufo gargarizans Cantor, which has anti-tumor, cardiotonic, anti-inflammatory and other physiological activities. However, in recent years, researchers have mainly paid attention to its anti-tumor effect and neglected its anti-inflammatory effect. METHODS: We used lipopolysaccharide (TLR4 ligand) and poly inosinic acid (TLR3 ligand) to stimulate cultured macrophages to induce inflammatory condition. Transcriptome sequencing and molecular experiments were performed to investigate the underlying mechanism. RESULTS: Bufalin could significantly reduce the production of pro-inflammatory factors (IL-6, TNF-α, IL-1β, IL-8, CXCL10, etc.), through inhibiting the phosphorylation of IKBα and IRF3, and thus down-regulating Toll-like receptor pathway. Molecular docking predicted that one of the molecular targets of bufalin is MD-2 coupled with lipopolysaccharide-activated TLR4. CONCLUSION: These findings not only support the pharmacological basis of using toad to treat inflammatory diseases in the Chinese medical history, but also provide a promising anti-inflammatory drug candidate for future clinical application.