Ac4SGL inhibits activation of TLR2 signaling. THP-1 cells were stimulated with various stimuli in the presence or not of Ac4SGL at the indicated concentrations. After 16 h, NF-κB activation (A and B), IL-8 in the culture supernatant (C), and CD40 expression (D) were measured. (A and B) NF-κB activation was determined by measuring alkaline phosphatase activity in the culture supernatant and reading OD at 630 nm. (C) IL-8 release in the culture supernatant was determined by sandwich ELISA. (D) CD40 expression was monitored by flow cytometry. Data show mean ± SEM. MDP, muramyl dipeptide, a ligand of NOD2; n.i., not induced.