Mice lacking the IL-1R–associated kinase 4 (IRAK4) are completely resistant to LPS-induced endotoxic disorder or the TLR9 agonist CpG DNA plus d-galactosamine–induced acute liver injury (ALI), whereas wild-type strains succumb. However, translational drugs against sepsis or ALI remain elusive. Lonicerae flos extract is undergoing the clinical trial phase I in LPS-injected healthy human volunteers for sepsis treatment. In the current study, chlorogenic acid (CGA), a major anti-inflammatory constituent of lonicerae flos extract, rescued endotoxic mortality of LPS-intoxicated C57BL/6 mice, as well as ameliorated ALI of LPS/d-galactosamine–challenged C57BL/6 mice. As a mechanism, CGA inhibited various TLR agonist–, IL-1α–, or high-mobility group box-1–stimulated autophosphorylation (activation) of IRAK4 in peritoneal macrophages from C57BL/6 or C3H/HeJ mice via directly affecting the kinase activity of IRAK4, a proximal signal transducer in the MyD88-mediated innate immunity that enhances transcriptional activity of NF-κB or AP-1. CGA consequently attenuated protein or mRNA levels of NF-κB/AP-1 target genes encoding TNF-α, IL-1α, IL-6, and high-mobility group box-1 in vivo under endotoxemia or ALI. Finally, this study suggests IRAK4 as a molecular target of CGA in the treatment of innate immunity–related shock and organ dysfunction following insult of various TLR pathogens from bacteria and viruses.

TGF-beta activated kinase1 (TAK1) has been reported to play an essential role in pro-inflammatory cellular signaling pathway. Activated TAK1 phosphorylates IkB kinase β (IKKβ), leading to NF-kB activation. Nuclear factor-kB (NF-kB) is a ubiquitous transcriptional factor that controls the expression of genes involved in immune responses. Here, treatment with 5-Pyridin-2-ylmethylene-6,7-dihydro-5H-benzo[b]thiophen-4-one (PT-2-318) inhibited not only autophosphorylation of TAK1 but also acute liver injury of E.coli LPS/D-galactosamine-challenged mice. As a mechanism, PT-2-318 directly inhibited autophosphorylation of TAK1. So, phosphorylation of both IkB and MAPKs was inhibited. Also, LPS-induced NF-kB and AP-1 promotor activity in lipololysaccharides (LPS)-stimulated macrophages RAW 264.7 was inhibited by blocked TAK1. As TAK1 was blocked, PT-2-318 attenuated LPS-induced mRNA expression of cytokines (IL-1β, TNF-α). On the other hand, PT-2-318 did not inhibit phosphorylation of IRAK4 and degradation of IRAK1. in vivo, intravenous treatment with PT-2-318 protected against LPS/GalN-induced acute liver failure in C57/BL7 mice. These results suggest that PT-2-318 might be considered as a potential agents for the treatment of inflammatory diseases.