fsl-1

TLR2/6 agonist (also a putative TLR10 ligand). Activates NF-κB. Induces pro-inflammatory cytokines including IL-8, IL-1β, CCL20 and TNF-α in vitro. Synergizes with IFNγ to induce CXCL10 release from melanoma cells.

FSL-1 TFA, a toll-like receptor 2/6 (TLR2/6) agonist derived from bacteria, bolsters resistance against experimental HSV-2 infection[1] and stimulates MMP-9 production via the TLR2 and NF-κB/AP-1 signaling pathways in monocytic THP-1 cells[2].

NCI 126224, a toll-like receptor 4 (TLR4) antagonist, demonstrates selective inhibition of nitric oxide (NO) production in RAW 264.7 macrophages, triggered by the TLR4 agonist LPS (IC50 = 0.31 µM), as opposed to minimal effects on NO production induced by agonists for TLR7/8 (R-848), TLR1/2 (Pam3CSK4), and TLR3 (poly(I:C)). Nevertheless, it also effectively inhibits NO production initiated by the TLR2/6 agonist FSL-1 at an IC50 of 0.6 µM in the same cell line. Moreover, NCI 126224 suppresses LPS-induced NF-κB activity in BV-2 microglial cells and reduces LPS-triggered increases in IL-1β and TNF-α levels in RAW 264.7 macrophages with IC50 values of 5.92, 0.42, and 1.54 µM, respectively.