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Toll-like receptors (TLRs) play an important role in induction of innate immune responses for host defense against invading microbial pathogens. Microbial component engagement of TLRs can trigger the activation of myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent downstream signaling pathways. Parthenolide, an active ingredient of feverfew ( Tanacetum parthenium), has been used for centuries to treat many chronic diseases. Parthenolide inhibits the MyD88-dependent pathway by inhibiting the activity of inhibitor-κB kinase. However, it is not known whether parthenolide inhibits the TRIF-dependent pathway. To evaluate the therapeutic potential of parthenolide, its effect on signal transduction via the TRIF-dependent pathway of TLRs induced by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly [I:C]) was examined. Parthenolide inhibited nuclear factor-κB and interferon regulatory factor 3 activation induced by LPS or poly[I:C], and the LPS-induced phosphorylation of interferon regulatory factor 3 as well as interferon-inducible genes such as interferon inducible protein-10. These results suggest that parthenolide can modulate TRIF-dependent signaling pathways of TLRs, and may be the basis of effective therapeutics for chronic inflammatory diseases. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) play an important role in host defense by sensing invading microbial pathogens and initiating innate immune responses. The stimulation of TLRs by microbial components triggers the activation of myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent downstream signaling pathways. Isoliquiritigen in (ILG), an active ingredient of Licorice, has been used for centuries to treat many chronic diseases. ILG inhibits the MyD88-dependent pathway by inhibiting the activity of inhibitor-κB kinase. However, it is not known whether ILG inhibits the TRIF-dependent pathway. To evaluate the therapeutic potential of ILG, we examined its effect on signal transduction via the TRIF-dependent pathway of TLRs induced by several agonists. ILG inhibited nuclear factor-κB and interferon regulatory factor 3 activation induced by lipopolysaccharide or polyinosinic-polycytidylic acid. ILG inhibited the lipopolysaccharide-induced phosphorylation of interferon regulatory factor 3 as well as interferon-inducible genes such as interferon inducible protein-10, and regulated activation of normal T-cell expressed and secreted (RANTES). These results suggest that ILG can modulate TRIF-dependent signaling pathways of TLRs, leading to decreased inflammatory gene expression. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) play a critical role in sensing microbial components and inducing innate immune and inflammatory responses by recognizing invading microbial pathogens. Lipopolysaccharide-induced dimerization of TLR4 is required for the activation of downstream signaling pathways including nuclear factor-kappa B (NF-κB). Therefore, TLR4 dimerization may be an early regulatory event in activating ligand-induced signaling pathways and induction of subsequent immune responses. Here, we report biochemical evidence that 6-shogaol, the most bioactive component of ginger, inhibits lipopolysaccharide-induced dimerization of TLR4 resulting in the inhibition of NF-κB activation and the expression of cyclooxygenase-2. Furthermore, we demonstrate that 6-shogaol can directly inhibit TLR-mediated signaling pathways at the receptor level. These results suggest that 6-shogaol can modulate TLR-mediated inflammatory responses, which may influence the risk of chronic inflammatory diseases. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) play critical roles in the induction of immune and inflammatory responses by recognizing invading microbial pathogens. One of the most important proteins for inflammatory responses is inducible nitric oxide synthase (iNOS). The dysregulated iNOS activation play important roles in the development of certain inflammatory diseases. The present study investigated the effects of arachidic acid (ACA), which is a saturated fatty acid (SFA), and eicosapentanoic acid (EPA), which is polyunsaturated fatty acid (PUFA), on inflammation by modulating NF-κB activation and iNOS expression induced by TLRs agonists in murine macrophages. EPA suppressed NF-κB activation and iNOS expression induced by a lipopolysaccharide, macrophage-activating lipopeptide 2-kDa, and polyriboinosinic polyribocytidylic acid, but ACA did not. These results suggested that EPA can modulate TLR signaling pathways and subsequent chronic inflammatory responses, but ACA did not mediate these effects. All the results suggest that EPA is a promising novel agent for the treatment of inflammatory diseases. [ABSTRACT FROM AUTHOR]

Inflammation is a pathological process that is known to be involved in numerous diseases. Microbial infection or tissue injury activates inflammatory responses, resulting in the induction of proinflammatory proteins including cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS).Aster yomenais used in traditional Korean remedies to treat cough, asthma, and insect bites. Here, we investigated the effects ofA. yomenaextract (EAY) on the expression of COX-2 and iNOS induced by LPS. EAY inhibited NF-κB activation and IκBα degradation induced by LPS. EAY suppressed LPS-induced COX-2 and iNOS expression which are the target genes regulated through NF-κB activation in macrophages. EAY also suppressed LPS-induced nitrite production. These results suggest that EAY has the potential to be developed as a potent anti-inflammatory drug. [ABSTRACT FROM AUTHOR]