Costunolide inhibits cyclooxygenase-2 expression induced by toll-like receptor 3 or 4 agonist

Abstract

Toll-like receptors (TLRs) play an important role in the induction of innate immune responses recognizing conserved microbial structural molecules. The microbial pathogens trigger the activation of two downstream signaling pathways of TLRs; myeloid differential factor 88 (MyD88)- and toll interleukin-1 receptor domain containing adapter inducing interferon-β (TRIF)-dependent pathways leading to the activation of nuclear factor-κB (NF-κB) and interferon regulatory factor 3 (IRF3). Saussureae Radix has been used for centuries to treat a variety of diseases. Costunolide, one of the active ingredients in Saussureae Radix, has been used to treat many chronic diseases. However, the mechanism of costunolide’s beneficial effects is largely unknown. Here, we report biochemical evidence that costunolide inhibits NF-κB activation and cyclooxygenase-2 expression induced by the TLR3 agonist polyriboinosinic polyribocytidylic acid (poly[I : C]) or the TLR4 agonist lipopolysaccharide (LPS). These results suggest that costunolide can modulate the immune responses regulated by TLR signaling pathways.