Octominin Inhibits LPS-Induced Chemokine and Pro-inflammatory Cytokine Secretion from RAW 264.7 Macrophages via Blocking TLRs/NF-κB Signal Transduction

Inflammation is a well-organized innate immune response that plays an important role during the pathogen attacks and mechanical injuries. The Toll-like receptors (TLR)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a major signal transduction pathway observed in RAW 264.7 macrophages during the inflammatory responses. Here, we investigated the anti-inflammatory effects of Octominin; a bio-active peptide developed from Octopus minor in RAW 264.7 macrophages in vitro. Octominin was found to inhibit lipopolysaccharides (LPS)-stimulated transcriptional activation of NF-κB in RAW 264.7 cells and dose-dependently decreased the mRNA expression levels of TLR4. Specifically, in silico docking results demonstrated that Octominin has a potential to inhibit TLR4 mediated inflammatory responses via blocking formation of TLR4/MD-2/LPS complex. We also demonstrated that Octominin could significantly inhibit LPS-induced secretion of pro-inflammatory cytokine (interleukin-β; IL-1β, IL-6, and tumor necrosis factor-α) and chemokines (CCL3, CCL4, CCL5, and CXCL10) from RAW 264.7 cells. Additionally, Octominin repressed the LPS-induced pro-inflammatory mediators including nitric oxide (NO), prostaglandin E2, inducible NO synthase, and cyclooxygenase 2 in macrophages. These results suggest that Octominin is a potential inhibitor of TLRs/NF-κB signal transduction pathway and is a potential candidate for the treatment of inflammatory diseases.