• Molecules and Cells
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• 제27권2호
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• pp.211-215
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• 2009

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 ($NF-{\kappa}B$). 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 $NF-{\kappa}B$ 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.

• The Korean Journal of Physiology and Pharmacology
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• 제19권1호
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• pp.1-7
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• 2015

Our previous study has shown berberine prevents damage to the intestinal mucosal barrier during early phase of sepsis in rat through mechanisms independent of the NOD-like receptors signaling pathway. In this study, we explored the regulatory effects of berberine on Toll-like receptors during the intestinal mucosal damaging process in rats. Male Sprague-Dawlay (SD) rats were treated with berberine for 5 d before undergoing cecal ligation and puncture (CLP) to induce polymicrobial sepsis. The expression of Toll-like receptor 2 (TLR 2), TLR 4, TLR 9, the activity of nuclear factor-kappa B ($NF-{\kappa}B$), the levels of selected cytokines and chemokines, percentage of cell death in intestinal epithelial cells, and mucosal permeability were investigated at 0, 2, 6, 12 and 24 h after CLP. Results showed that the tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and interleukin-6 (IL-6) level were significantly lower in berberine-treated rats compared to the control animals. Conversely, the expression level of tight junction proteins, percentage of cell death in intestinal epithelial cells and the mucosal permeability were significantly higher in berberine-treated rats. The mRNA expression of TLR 2, TLR 4, and TLR 9 were significantly affected by berberine treatment. Our results indicate that pretreatment with berberine attenuates tissue injury and protects the intestinal mucosal barrier in early phase of sepsis and this may possibly have been mediated through the TLRs pathway.

• Genomics & Informatics
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• 제10권3호
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• pp.153-166
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• 2012

A variety of ligands differ in their capacity to bind the receptor, elicit gene expression, and modulate physiological responses. Such receptors include Toll-like receptors (TLRs), which recognize various patterns of pathogens and lead to primary innate immune activation against invaders, and G-protein coupled receptors (GPCRs), whose interaction with their cognate ligands activates heterotrimeric G proteins and regulates specific downstream effectors, including immuno-stimulating molecules. Once TLRs are activated, they lead to the expression of hundreds of genes together and bridge the arm of innate and adaptive immune responses. We characterized the gene expression profile of Toll-like receptor 4 (TLR4) in RAW 264.7 cells when it bound with its ligand, 2-keto-3-deoxyoctonate (KDO), the active part of lipopolysaccharide. In addition, to determine the network communications among the TLR, Janus kinase (JAK)/signal transducer and activator of transcription (STAT), and GPCR, we tested RAW 264.7 cells with KDO, interferon-${\beta}$, or cAMP analog 8-Br. The ligands were also administered as a pair of double and triple combinations.

• Journal of Plant Biotechnology
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• 제32권4호
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• pp.269-273
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• 2005

Methylotrophic 효모 Pichia pastoris 발현시스템을 사용하여 인간 TLR9 단백질의 세포내 TIR 도메인을 발현하였다. TIR 단백질이 P. pastoris에서 발현되어 배지 속으로 분비되는 것을 SDS-PAGE로 확인하였고, 발현된 단백질을 western-blot, MALDI-TOF 질량분석으로 동정하였다. 이를 통하여 TIR 딘백질이 P. pastoris에서 안정적으로 발현됨을 알 수 있었다. 그리고 발현된 단백질을 니켈 친화, 양이온교환수지, 겔 투과 크로마토그라피를 사용하여 순수 분리 정제하였다. P. pastoris를 이용한 단백질의 발현과 정제방법은 대장균에서 잘 발현되지 않는 단백질의 발현에 응용될 수 있을 것이다.

• 대한의생명과학회지
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• 제16권1호
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• pp.39-45
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• 2010

Toll-like receptors (TLRs), which are pattern recognition receptors (PRRs), recognize pathogen-associated molecular patterns (PAMPs) and regulate the activation of innate immunity. All TLR signaling pathways culminate in the activation of NF-${\kappa}B$, leading to the induction of inflammatory gene products such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Parthenolide, a sesquiterpene lactone isolated from the herb feverfew (Tanacetum parthenium), has been used as folk remedies to treat many chronic diseases for many years. In the present report, we present biochemical evidence that parthenolide inhibits the NF-${\kappa}B$ activation induced by TLR agonists and the overexpression of downstream signaling components of TLRs, MyD88, $IKK{\beta}$, and p65. Parthenolide also inhibits TLR agonists-induced COX-2 and iNOS expression. These results suggest that parthenolide can modulate the immune responses regulated by TLR signaling pathways.

• 한국식품과학회지
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• 제39권5호
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• pp.481-487
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• 2007

Toll-like receptors (TLRs) induce innate immune responses that are essential for host defenses against invading microbial pathogens, thus leading to the activation of adaptive immune responses. In general, TLRs have two major downstream signaling pathways: the MyD88- and TRIF-dependent pathways, which lead to the activation of $NF-{\kappa}B$ and IRF3. Numerous studies have demonstrated that certain phytochemicals possessing anti-inflammatory effects inhibit $NF-{\kappa}B$ activation induced by pro-inflammatory stimuli, including lipopolysaccharides and $TNF{\alpha}$. However, the direct molecular targets for such anti-inflammatory phytochemicals have not been fully identified. Identifying the direct targets of phytochemicals within the TLR pathways is important because the activation of TLRs by pro-inflammatory stimuli can induce inflammatory responses that are the key etiological conditions in the development of many chronic inflammatory diseases. In this paper we discuss the molecular targets of resveratrol, (-)-epigallocatechin-3-gallate (EGCG), and curcumin in the TLR signaling pathways. Resveratrol specifically inhibited the TRIF pathway in TLR3 and TLR4 signaling, by targetting TBK1 and RIP1 in the TRIF complex. Furthermore, EGCG suppressed the activation of IRF3 by targetting TBK1 in the TRIF-dependent signaling pathways. In contrast, the molecular target of curcumin within the TLR signaling pathways is the receptor itself, in addition to $IKK{\beta}$. Together, certain dietary phytochemicals can modulate TLR-derived signaling and inflammatory target gene expression, and in turn, alter susceptibility to microbial infection and chronic inflammatory diseases.

• 대한의생명과학회지
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• 제19권2호
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• pp.112-117
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• 2013

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) and regulate the activation of innate immunity. All TLR signaling pathways culminate in the activation of NF-${\kappa}B$, leading to the induction of inflammatory gene products such as cyclooxygenase-2 (COX-2). Triptolide (TP), a natural component of Tripterygium wilfordii Hook. F, has been used as folk remedies to treat many chronic diseases for many years. In the present report, we present biochemical evidence that TP inhibits the NF-${\kappa}B$ activation induced by polyriboinosinic polyribocytidylic acid (Poly[I:C], TLR3 agonist) and lipopolysaccharide (LPS, TLR4 agonist). TP also inhibits COX-2 expression induced by Poly[I:C] and LPS. These results suggest that TP can modulate the immune responses regulated by TLR3 and TLR4 signaling pathways.

• 한국식품과학회지
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• 제41권5호
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• pp.477-482
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• 2009

TLRs는 여러 병원균들이 가지고 있는 PAMPs를 인식해서, 선천성 면역 반응을 유도하는 중요한 역할을 한다. TLR4의 이합체 형성은 신호전달 체계의 활성화와 뒤이어 발생하는 선천성 면역 반응을 유도하기 위해서 최초로 일어나는 반응으로 알려져 있다. 우리가 먹는 식품 중에는 항염증 효과가 있다고 널리 알려져 있는 phytochemicals이 포함되어 있다. 특히 ${\alpha},{\beta}$-unsaturated carbonyl group을 가지고 있는 curcumin, 6-shogaol, 그리고 cinnamaldehyde는 Michael addition 반응에 의해서 LPS에 의해서 유도된 TLR4의 이합체 형성을 억제시켜, 전사요소 NF-${\kappa}B$와 IRF3 활성화 및 그것들에 의해서 조절되는 타깃 유전자들을 억제시킨다. 이러한 결과는 ${\alpha},{\beta}$-unsaturated carbonyl group을 가지고 있는 curcumin, 6-shogaol, 그리고 cinnamaldehyde의 항염증 효능에 대한 새로운 기전을 설명해 주는 것이라 할 수 있겠다.

• Journal of Veterinary Science
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• 제23권2호
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• pp.27.1-27.16
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• 2022

Background: The role of Toll-like receptors (TLRs) in a feline infectious peritonitis virus (FIPV) infection is not completely understood. Objectives: This study examined the expression of TLR3, TLR7, TLR9, tumor necrosis factor-alpha (TNF-α), interferon (IFN)-β, and interleukin (IL)-10 upon an FIPV infection in Crandell-Reese feline kidney (CRFK) cells and feline monocytes. Methods: CRFK cells and monocytes from feline coronavirus (FCoV)-seronegative cats and FCoV-seropositive cats were infected with type II FIPV-79-1146. At four, 12, and 24 hours post-infection (hpi), the expression of TLR3, TLR7, TLR9, TNF-α, IFN-β, and IL-10, and the viral load were measured using reverse transcription quantitative polymerase chain reaction. Viral protein production was confirmed using immunofluorescence. Results: FIPV-infected CRFK showed the upregulation of TLR9, TNF-α, and IFN-β expression between 4 and 24 hpi. Uninfected monocytes from FCoV-seropositive cats showed lower TLR3 and TLR9 expression but higher TLR7 expression compared to uninfected monocytes from FCoV-seronegative cats. FIPV-infected monocytes from FCoV-seropositive cats downregulated TLR7 and TNF-α expression between 4 and 24 hpi, and 4 and 12 hpi, respectively. IFN-β was upregulated early in FIPV-infected monocytes from FCoV-seropositive cats, with a significant difference observed at 12 hpi compared to FCoV-seronegative cats. The viral load in the CRFK and FIPV-infected monocytes in both cohorts of cats was similar over time.ConclusionTLR7 may be the key TLR involved in evading the innate response against inhibiting TNF-α production. Distinct TLR expression profiles between FCoV-seronegative and FCoV-seropositive cats were observed. The associated TLR that plays a role in the induction of IFN-β needs to be explored further.

• Animal cells and systems
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• 제13권1호
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• pp.1-8
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• 2009

Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation.