• International Journal of Oral Biology
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• v.45 no.4
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• pp.225-231
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• 2020

Glial cells, including astrocytes and microglia, interact closely with neurons and modulate pain transmission, particularly under pathological conditions. In this study, we examined the excitability of substantia gelatinosa (SG) neurons of the spinal dorsal horn using a patch clamp recording to investigate the roles of microglial activation in the nociceptive processes of rats. We used xanthine/xanthine oxidase (X/XO), a generator of superoxide anion (O2·-), to induce a pathological pain condition. X/XO treatment induced an inward current and membrane depolarization. The inward current was significantly inhibited by minocycline, a microglial inhibitor, and fluorocitrate, an astrocyte inhibitor. To examine whether toll-like receptor 4 (TLR4) in microglia was involved in the inward current, we used lipopolysaccharide (LPS), a highly specific TLR4 agonist. The LPS induced inward current, which was decreased by pretreatment with Tak-242, a TLR4-specific inhibitor, and phenyl N-t-butylnitrone, a reactive oxygen species scavenger. The X/XO-induced inward current was also inhibited by pretreatment with Tak-242. These results indicate that the X/XO-induced inward current of SG neurons occurs through activation of TLR4 in microglial cells, suggesting that neuroglial cells modulate the nociceptive process through central sensitization.

• Biomedical Science Letters
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• v.25 no.1
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• pp.60-65
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• 2019

Toll-like receptors (TLRs) are one of the families of pattern recognition receptors (PRR) operating in the innate immunity. TLRs have the ability to recognize relatively conserved microbial components, which are generally referred to as pathogen-associated molecular patterns (PAMPs). The activation of TLRs signaling leads to the activation of $NF-{\kappa}B$ and the expression of pro-inflammatory gene products such as cytokines and inducible nitric oxide synthase (iNOS). To evaluate the therapeutic potential of pristimerin, which is a naturally occurring triterpenoid compound from Celastraceae plants, iNOS expression induced by MALP-2 (TLR2 and TLR6 agonist), Poly[I:C] (TLR3 agonist), or LPS (TLR4 agonist) were examined. Pristimerin suppressed the iNOS expression induced by MALP-2, Poly[I:C], or LPS. These results suggest that pristimerin can modulate TLRs signaling pathways leading to decreased inflammatory gene expression.

• Biomedical Science Letters
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• v.25 no.3
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• pp.267-274
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• 2019

Toll-like receptors (TLRs) are one of the families of pattern recognition receptors (PRR) to recognize pathogen-associated molecular patterns (PAMPs). PAMPs stimulate TLRs to initiate specific immunoactivity. The activation of TLRs signaling leads to the expression of pro-inflammatory gene products such as cytokines and inducible nitric oxide synthase (iNOS). To evaluate the therapeutic potential of dehydrocostus lactone (DHL), which is a natural sesquiterpene lactone derived from various medicinal plants, iNOS expression induced by LPS (TLR4 agonist), MALP-2 (TLR2 and TLR6 agonist), or Poly[I:C] (TLR3 agonist) were examined. DHL suppressed the iNOS expression induced by LPS, MALP-2, or Poly[I:C]. DHL also inhibited nitrite production induced by LPS, MALP-2, or Poly[I:C]. These results suggest that DHL can modulate TLRs signaling pathways resulting in anti-inflammatory effect.

• Biomedical Science Letters
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• v.24 no.2
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• pp.102-107
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• 2018

Toll-like receptors (TLRs) play an important role for host defense against invading pathogens. The activation of TLRs signaling leads to the activation of $NF-{\kappa}B$ and the expression of pro-inflammatory gene products such as cytokines and inducible nitric oxide synthase (iNOS). To evaluate the therapeutic potential of cardamonin, which is a naturally occurring chalcone from Alpinia species (zingiberaceous plant species), $NF-{\kappa}B$ activation and iNOS expression induced by MALP-2 (TLR2 and TLR6 agonist) or LPS (TLR4 agonist) were examined. Cardamonin inhibited the activation of $NF-{\kappa}B$ induced by MALP-2 or LPS. Cardamonin also suppressed the iNOS expression induced by MALP-2 or LPS. These results suggest that cardamonin has the specific mechanism for anti-inflammatory responses by regulating of TLRs signaling pathway.

• Parasites, Hosts and Diseases
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• v.54 no.5
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• pp.679-684
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• 2016

Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-${\kappa}B$-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1294-1298
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• 2008

Toll-like receptors (TLRs) induce innate immune responses recognizing conserved microbial structural molecules. All TLR signaling pathways culminate in the activation of nuclear factor-${\kappa}B$ (NF-${\kappa}B$). The activation of NF-${\kappa}B$ leads to the induction of inflammatory gene products such as cyclooxygenase-2 (COX-2). Guggul has been used for centuries to treat a variety of diseases. Guggulstreone, one of the active ingredients in guggul, has been used to treat many chronic diseases. However, the mechanism as to how guggulsterone mediate the health effects is largely unknown. Here, we report biochemical evidence that guggulsterone inhibits the NF-${\kappa}B$ activation and COX-2 expression induced by TLR2, TLR3, and TLR4 agonists. Guggulsterone also inhibits the NF-${\kappa}B$ activation induced by downstream signaling components of TLRs, myeloid differential factor 88 (MyD88), $I{\kappa}B$ kinase ${\beta}$ ($IKK{\beta}$), and p65. These results imply that guggulsterone can modulate the immune responses regulated by TLR signaling pathways.

• Food Science of Animal Resources
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• v.43 no.5
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• pp.938-947
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• 2023

In the present study, we aimed to examine the inhibition of genomic DNA from Lactiplantibacillus plantarum (LpDNA) on Porphyromonas gingivalis lipopolysaccharide (PgLPS)-induced inflammatory responses in RAW264.7 cells. Pretreatment with LpDNA for 15 h significantly inhibited PgLPS-induced mRNA expression and protein secretion of interleukin (IL)-1β, IL-6, and monocyte chemoattractant protein-1. LpDNA pretreatment also reduced the mRNA expression of Toll-like receptor (TLR)2 and TLR4. Furthermore, LpDNA inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) and the activation of nuclear factor-κB (NF-κB) induced by PgLPS. Taken together, these findings demonstrate that LpDNA attenuates PgLPS-induced inflammatory responses by regulating MAPKs and NF-κB signaling pathways through the suppression of TLR2 and TLR4 expression.

• Korean Journal of Plant Resources
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• v.36 no.4
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• pp.275-281
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• 2023

Autophagy contributes to enhancing the immune system (innate and adaptive immune system) against foreign pathogens. Autophagy of macrophages is used as a major indicator for developing vaccine adjuvants to increase the adaptive immune response. In this study, PLR activated autophagy and increased p62/SQSTM1. The knockdown of p62/SQSTM1 attenuated PLR-mediated autophagy. Inhibition of TLR4 blocked PLR-mediated increase in p62/SQSTM1 level and autophagy induction. In addition, inhibition of PI3K blocked HSL-mediated increase of p62/SQSTM1. PLR increased Nrf2 level and the inhibition of TLR4 and PI3K reduced PLR-mediated increase of Nrf2. Taken together, it is believed that PLR may induce autophagy through upregulating p62/SQSTM1 via TLR4/PI3K/Nrf2 signaling pathway.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.2
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• pp.267-272
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• 2017

Piceatannol (PIC) is a natural hydroxylated analog of resveratrol (RSV), which is a polyphenol known to extend lifespan by stimulating sirtuins. The aim of this study was to investigate the effects of PIC and RSV on the toll-like receptor 4 (TLR4)-nuclear factor kappa B ($NF-{\kappa}B$) pathway in mouse hepatocytes and an obese/diabetic KK/HlJ mouse model. AML12 mouse hepatocytes in the absence or presence of palmitic acids (PA) were treated with PIC ($50{\mu}M$) or RSV ($50{\mu}M$). Male KK/HlJ mice at 20 weeks of age were divided into three subgroups as follows: 1) obese and diabetic control (KK), 2) KK_PIC, and 3) KK_RSV. PIC and RSV were administered orally at a dose of 10 mg/kg/d for 4 weeks. Four weeks of PIC and RSV treatment did not affect body weight or food intake in KK mice. Serum fasting blood glucose was significantly reduced in KK_PIC, and 2 h oral glucose tolerance test area under the curve was significantly reduced by PIC and RSV treatment in KK mice. PIC tended to improve homeostasis model assessment of the insulin resistance index (HOMA-IR) and HOMA beta-cells in diabetic KK mice. TLR4 and $NF-{\kappa}B$ were down-regulated by PIC and RSV treatments in hepatocytes in the absence or presence of PA. Insulin receptor, AMP-activated protein kinase, peroxisome proliferator-activated receptor gamma, nucleotide oligomerization domain-like receptor family pyrin domain-containing 3, interleukin-1, and $NF-{\kappa}B$ were altered in PIC-treated livers. Collectively, PIC and RSV inhibited the $TLR4-NF-{\kappa}B$ pathway, and PIC seems to be more effective than RSV in the regulation of analyzed targets, which are involved in insulin signaling and inflammation in vivo.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1321-1326
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• 2014

Background/Aim: Toll-like receptor 4 (TLR4) and B7-H1, both normally expressed restricted to immune cells, are found to be aberrantly expressed in a majority of human tumors and may play important roles in regulation of tumor immunity. It has been shown that urothelial bladder cancer (UBC) patients can manifest tumoral immune escape which may be a potential critical factor in tumor pathogenesis and progression. However, so far, the mechanisms of UBC-related immune escape have not been clarified. The aim of this study was to investigate the effect of TLR4 and B7-H1 on immune escape of UBC. Methods: Bladder cancer T24 cells were pre-incubated with LPS and co-cultured with tumor specific CTLs. CTL cytotoxicity and apoptosis rates were measured by MTT assay and flow cytometry, respectively. The effects of an ERK inhibitor on B7-H1 expression and CTL cytotoxicity against T24 cells were also evaluated. In addition, TLR4, B7-H1 and PD-1 protein expression was analyzed by immunohistochemistry in 60 UBC specimens and 10 normal urothelia. Results: TLR4 activation protected T24 cells from CTL killing via B7-H1 overexpression. However PD98059, an inhibitor of ERK, enhanced CTL killing of T24 cells by reducing B7-H1 expression. TLR4 expression was generally decreased in UBC specimens, while B7-H1 and PD-1 were greatly overexpressed. Moreover, expression of both B7-H1 and PD-1 was significantly associated with UICC stage and WHO grade classification. Conclusions: TLR4 and B7-H1 may contribute to immune escape of UBC. Targeting B7-H1 or the ERK pathway may offer new immunotherapy strategies for bladder cancer.