Biochem/physiol Actions

CU-CPT9a is a potent and selective inhibitor of Toll-like receptor 8 (TLR8). It binds to TLR8 at a site different from current small-molecule TLR7/8 agonists, stabilizing the TLR8 dimer in its resting state, thus preventing TLR8 activation It exhibited an IC50 value of 0.5 nM and blocked TLR8 activation induced by either resiquimod (R848) or ssRNA without affecting the closely related TLR7 or cells expressing other TLRs. CU-CPT9a also suppressed TNF-α levels in a dose-dependent manner in cells from patients with rheumatoid arthritis.