Hwa-Jeong Shin

Isobavachalcone suppresses expression of inducible nitric oxide synthase induced by Toll-like receptor agonists.

Toll-like receptors (TLRs) play an important role by recognizing many pathogen-associated molecular patterns and inducing innate immunity. Dysregulated activation of TLR signaling pathways induces the activation of various transcription factors such as nuclear factor-κB, leading to the induction of pro-inflammatory gene products such as inducible nitric oxide synthase (iNOS). The present study investigated the effect of isobavachalcone (IBC), a natural chalcone component of Angelica keiskei, on inflammation by modulating iNOS expression induced by TLR agonists in murine macrophages. IBC suppressed iNOS expression induced by macrophage-activating lipopeptide 2-kDa, polyriboinosinic polyribocytidylic acid, or lipopolysaccharide. These results indicate the potential of IBC as a potent anti-inflammatory drug.

Parthenolide inhibits TRIF-dependent signaling pathway of toll-like receptors in RAW264.7 macrophages

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.

Suppression of TRIF-dependent signaling pathway of toll-like receptors by allyl isothiocyanate in RAW 264.7 macrophages.

Toll-like receptors (TLR) play a significant role in the induction of innate immune responses that are essential for host defense against invading microbial pathogens. In general, TLRs have two major downstream signaling pathways: myeloid differential factor 88 (MyD88)-dependent and toll-interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF)-dependent pathways. Allyl isothiocyanate (AITC) found in cruciferous vegetables has an effect on treatment of many chronic diseases. However, the exact molecular targets of AITC are still unidentified. Here, it was investigated whether AITC can modulate TLR signaling pathways and what is the molecular target of AITC in TLRs signaling pathways. AITC suppressed the activation of nuclear factor-κB by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly[I:C]), but not by macrophage-activating lipopeptide of 2kDa (MALP-2) or cytosine-phosphate-guanine dinucleotide (CpG DNA). AITC also suppressed the activation of interferon regulatory factor 3 (IRF3) and the expression of interferon inducible protein-10 (IP-10) induced by LPS or poly[I:C]. These results suggest that AITC can modulate TRIF-dependent signaling pathways of TLRs leading to decreased inflammatory gene expression.

TBK1-targeted suppression of TRIF-dependent signaling pathway of Toll-like receptors by helenalin

AIMS The purpose of this study was to evaluate the therapeutic potential of the helenalin in Toll-like receptor (TLR) signaling pathways. MAIN METHODS RAW264.7 cells were transfected with a NF-κB, IFNβ PRDIII-I, or IP-10 luciferase plasmid and then luciferase enzyme activities were determined by luciferase assay. The expression of iNOS, COX-2, and IP-10 and phosphorylation of IRF3 were determined by Western blotting. The levels of IP-10 were determined with culture medium by using IP-10 ELISA kit. TBK1 kinase activity was determined by MBP assay kit. KEY FINDINGS Helenalin inhibited transcription factor NF-κB and IRF3 activation, which was induced by TLR agonists as well as its target genes, such as COX-2, iNOS, and IP-10. Helenalin attenuated ligand-independent activation of NF-κB induced by MyD88, IKKβ, and p65, and IRF3 induced by TRIF, TBK1, or IRF3. Furthermore, helenalin inhibited TBK1 kinase activity in vitro. SIGNIFICANCE TLRs are primary sensors that detect a wide variety of microbial components and play an important role in the induction of innate immune. To evaluate the therapeutic potential of helenalin, we examined its effect on signal transduction via the TLR signaling pathways. Our results suggest that beneficial effects of helenalin on chronic inflammatory diseases are mediated through modulation of TLR signaling pathways by targeting TBK1.

Japanese bog orchid (Eupatorium japonicum) extract suppresses expression of inducible nitric oxide synthase and cyclooxygenase-2 induced by toll-like receptor agonists

Toll-like receptors (TLR) play an important role in the recognition of many pathogen-associated molecular patterns and the induction of innate immunity. Dysregulated activation of TLR signaling pathways is associated with certain inflammatory diseases. Japanese bog orchid (Eupatorium japonicum), which belongs to a family of Asteraceae plants, is consumed as a tea. The present study investigated the effect of the ethanol extracts of flowers of Japanese bog orchid (EJE) on nuclear factor (NF)-κB activation and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) by TLR agonists in murine macrophages. EJE suppressed NF-κB activation and iNOS and COX-2 expression induced by lipopolysaccharide (TLR4 agonist), polyriboinosinic polyribocytidylic acid (TLR3), and macrophage-activating 2 kDa lipopeptide (TLR2 and TLR6). These results suggest that EJE can regulate TLR signaling pathways and indicated its potential as a potent anti-inflammatory drug.

Suppression of the TRIF-dependent signaling pathway of toll-like receptors by (E)-isopropyl 4-oxo-4-(2-oxopyrrolidin-1-yl)-2-butenoate

Toll-like receptors (TLRs) are pattern recognition receptors that recognize molecular structures derived from microbes and initiate innate immunity. TLRs have two downstream signaling pathways, the MyD88- and TRIF-dependent pathways. Dysregulated activation of TLRs is closely linked to increased risk of many chronic diseases. Previously, we synthesized fumaryl pyrrolidinone, (E)-isopropyl 4-oxo-4-(2-oxopyrrolidin-1- yl)-2-butenoate (IPOP), which contains a fumaric acid isopropyl ester and pyrrolidinone, and demonstrated that it inhibits the activation of nuclear factor kappa B by inhibiting the MyD88-dependent pathway of TLRs. However, the effect of IPOP on the TRIF-dependent pathway remains unknown. Here, we report the effect of IPOP on signal transduction via the TRIF-dependent pathway of TLRs. IPOP inhibited lipopolysaccharide- or polyinosinic-polycytidylic acid-induced interferon regulatory factor 3 activation, as well as interferon- inducible genes such as interferon inducible protein-10. These results suggest that IPOP can modulate the TRIF-dependent signaling pathway of TLRs, leading to decreased inflammatory gene expression.

Curcumin Inhibits Ovalbumin-Induced Inducible Nitric Oxide Synthase Expression

Egg allergy has been reported as the most prevalent food hypersensitivity among children. One of the major egg allergens is ovalbumin (OVA). OVA is the major protein in the egg white, comprising 54% of its total protein content. Curcumin isolated from Curcuma longa has been used as folk remedies in order to treat many chronic diseases for many years. In the present report, we present biochemical evidence that curcumin inhibits the NF- activation induced by OVA. Curcumin also inhibits OVA-induced iNOS expression and nitrite production. These data suggest new approaches for the development of efficient anti-allergic strategies.

Phenethyl Isothiocyanate Inhibits Ovalbumin-induced Inducible Nitric Oxide Synthase Expression

Egg allergies have been reported as one of the most prevalent food hypersensitivities in the pediatric population. One of the major egg allergens is ovalbumin (OVA), which is the major protein in the egg whites. Phenethyl isothiocyanate (PEIC) from cruciferous vegetables has an effect on anti-inflammatory therapy. In the present report, we show that PEIC inhibits the nuclear factor- (NF-) activation induced by OVA. PEIC also inhibits the OVA-induced inducible nitric oxide synthase (iNOS) expression and nitrite production. However, PEIC did not suppress the cyclooxygenase-2 (COX-2) expression induced by OVA. These results suggest that PEIC has the specific mechanism for anti-inflammatory responses and efficient anti-allergic activities.

Costunolide inhibits interferon regulatory factor 3 activation induced by lipopolysaccharide and polyinosinic-polycytidylic acid

Inflammation can be initiated by invading microbial pathogens. Toll-like receptors (TLRs) recognize molecular structures derived from microbial pathogens and regulate the activation of innate immunity. In general, TLRs have 2 major downstream signaling pathways, the myeloid differentiation primary response protein 88 (MyD88)- and Toll/interleukin 1 receptor (TIR) domaincontaining adaptor protein (TIRAP) inducing interferon (TRIF)-dependent pathways, which lead to the activation of nuclear factor (NF)-κB and interferon regulatory factor 3 (IRF3). Costunolide, one of the active ingredients in Aucklandiae Radix (Saussurea lappa), has been used to treat many chronic inflammatory diseases. To evaluate the therapeutic potential of costunolide, its effect on signal transduction via the TLR signaling pathways was examined. Costunolide inhibited lipopolysaccharide or polyinosinicpolycytidylic acid-induced NF-κB and IRF3 activation and IRF3 phosphorylation, as well as interferon-inducible genes such as interferon inducible protein-10. The results suggest that costunolide can modulate immune responses regulated by TLR signaling pathways and may be the basis of effective therapeutics for chronic inflammatory diseases.

Inhibition of homodimerization of toll-like receptor 4 by (E)-isopropyl 4-oxo-4-(2-oxopyrrolidin-1-yl)-2-butenoate

Toll-like receptors (TLRs) recognize molecular structures derived from microbes and initiate innate immunity. The stimulation of TLR4 by lipopolysaccharide triggers the activation of the myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain -containing adapter inducing interferon-β (TRIF)-dependent signaling pathways. Previously, we synthesized a fumaryl pyrrolidinone, (E)-isopropyl 4-oxo-4-(2-oxopyrrolidin-1-yl)-2-butenoate (IPOP) and demonstrated that it inhibits activation of nuclear factor kappa B (NF-κB) by inhibiting the MyD88-dependent pathway of TLRs. TLR4 and the downstream signaling components are good therapeutic targets for many chronic inflammatory diseases. Here, it is investigated whether IPOP modulates TLR4 downstream signaling pathways and what anti-inflammatory target in TLR4 signaling is regulated by IPOP. IPOP inhibited LPSinduced NF-κB and interferon regulatory factor 3 (IRF3) activation by targeting TLR4 dimerization. These results suggest that IPOP can modulate TLR4 signaling pathway at the receptor level to decrease inflammatory gene expression.