• 대한의생명과학회지
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• 제24권2호
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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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• 제54권5호
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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.

• 한국자원식물학회지
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• 제36권4호
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• pp.275-281
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• 2023

본 연구에서 우리는 작약 뿌리 추출물이 TLR4/PI3K/Nrf2 신호전달을 통해 p62/SQSTM1을 증가시켜 대식세포에서 자가포식을 유도한다는 것을 확인하였다. 대식세포의 자가포식 유도는 선천성과 적응성 면역 반응 간의 연결을 강화해 백신 보조제 개발에 있어서 중요한 표적으로 사용되기 때문에, 작약 뿌리 추출물은 백신개발에 필수적인 백신보조제로의 활용이 가능할 것으로 생각된다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.92-92
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• 2019

Excessive or chronic inflammation contributes to the pathogenesis of many inflammatory diseases such as sepsis, rheumatoid arthritis, and ulcerative colitis. Hibiscus syriacus L. has been used as a medicinal plant in many Asian countries, even though its anti-inflammatory activity has been unclear. Therefore, we investigated the anti-inflammatory effect of anthocyanin fractions from the H. syriacus L. varieties Pulsae (PS) on the lipopolysaccharide (LPS)-induced expression of proinflammatory mediators and cytokines in RAW264.7 macrophages. PS suppressed LPS-induced nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) secretion concomitant with downregulation of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. Furthermore, PS inhibited the production of proinflammatory cytokines such as tumor necrosis factor-alpha ($TNF-{\alpha}$), interleukin-6 (IL-6), and IL-12 in LPS-stimulated RAW264.7 macrophages. Further study showed that PS significantly decreased LPS-induced nuclear translocation of the nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) subunits, p65 and p50. Molecular docking data showed that many anthocyanins from PS fit into the hydrophobic pocket of MD2 and bound to Toll-like receptor 4 (TLR4), indicating that PS inhibits the TLR4-MD2-mediated inflammatory signaling pathway. Especially, apigenin-7-O-glucoside most powerfully bound to MD2 and TLR4 through LYS122, LYS122, and SER127 at a distance of $2.205{\AA}$, $3.098{\AA}$, and $2.844{\AA}$ and SER441 at a distance of $2.873{\AA}$ (docking score: -8.4) through hydrogen bonding, respectively. Additionally, PS inhibited LPS-induced TLR4 dimerization/expression on the cell surface, which consequently decreased MyD88 recruitment and IRAK4 phosphorylation. PS completely blocked LPS-mediated mortality in zebrafish larvae by diminishing the recruitment of neutrophil and macrophages accompanied by low levels of proinflammatory cytokines. Taken together, our results indicate that PS attenuates LPS-mediated inflammation in both in vitro and in vivo by blocking the TLR4/MD2-MyD88/IRAK4-$NF-{\kappa}B$ axis. Therefore, PS might be used as a novel modulatory candidate for effective treatment of LPS-mediated inflammatory diseases.

• 대한의생명과학회지
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• 제19권3호
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• pp.173-179
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• 2013

Since the identification and characterization of toll-like receptors (TLR) in Drosophila, numerous scientific studies have examined the role of TLRs in host innate immunity. Recent studies have suggested a convergence of the nuclear factor kappa B (NF-${\kappa}B$) signaling and cytokine production regulated by the cytosolic elicitor known as NLRs (nucleotide-binding domain and leucine-rich repeat containing domain receptors) as a key modulator in inflammatory diseases. Among the NLRs, NOD1 and NOD2 have been intensively investigated for its role in inflammatory bowel disease (IBD). On the other hand, NLRs such as NLRP3, NLRP1, and NLRC4 (also known as IPAF) have been identified to form the inflammasome to activate downstream signaling molecules in response to pathogenic microbes. There is evidence to suggest that substantial crosstalk exists for the TLR and NLR signaling pathway in response to pathogen associated molecular pattern (PAMP). However, the substrate and the mechanistic role of NLRs are largely unknown in innate immune response. Understanding the signaling mechanisms by which NLRs recognize PAMP and other danger signals will shed light on elucidating the pathogenesis of various human inflammatory diseases such as IBD.

• 한국자원식물학회지
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• 제34권6호
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• pp.536-541
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• 2021

In this study, we investigated whether Hibiscus manihot flowers (HMF) exhibits immunostimulatory activity in RAW264.7 cells. HMF increased the production of immunostimulatory factors such as NO, iNOS, IL-1β and TNF-α in RAW264.7 cells. TLR2 and TLR4 blocked HMF-mediated production of immunostimulatory factors in RAW264.7 cells. In addition, the inhibition of MAPK signaling pathway reduced HMF-mediated production of immunostimulatory factors. From these results, HMF is thought to promote the production of immunostimulatory factors through activating TLR2/4/MAPK signaling in macrophages. It is believed that HMF can be developed as an agent related to immune enhancement in the future.

• Biomolecules & Therapeutics
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• 제24권4호
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• pp.387-394
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• 2016

Sepsis, a serious clinical problem, is characterized by a systemic inflammatory response to infection and leads to organ failure. Toll-like receptor (TLR) signaling is intimately implicated in hyper-inflammatory responses and tissue injury during sepsis. Histone deacetylase (HDAC) inhibitors have been reported to exhibit anti-inflammatory properties. The aim of this study was to investigate the hepatoprotective mechanisms of trichostatin A (TSA), a HDAC inhibitor, associated with TLR signaling pathway during sepsis. The anti-inflammatory properties of TSA were assayed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Polymicrobial sepsis was induced in mice by cecal ligation and puncture (CLP), a clinically relevant model of sepsis. The mice were intraperitoneally received TSA (1, 2 or 5 mg/kg) 30 min before CLP. The serum and liver samples were collected 6 and 24-h after CLP. TSA inhibited the increased production of tumor necrosis factor (TNF)-${\alpha}$ and interleukin (IL)-6 in LPS-stimulated RAW264.7 cells. TSA improved sepsis-induced mortality, attenuated liver injury and decreased serum TNF-${\alpha}$ and IL-6 levels. CLP increased the levels of TLR4, TLR2 and myeloid differentiation primary response protein 88 (MyD88) protein expression and association of MyD88 with TLR4 and TLR2, which were attenuated by TSA. CLP increased nuclear translocation of nuclear factor kappa B and decreased cytosolic inhibitor of kappa B ($I{\kappa}B$) protein expression, which were attenuated by TSA. Moreover, CLP decreased acetylation of $I{\kappa}B$ kinase (IKK) and increased association of IKK with $I{\kappa}B$ and TSA attenuated these alterations. Our findings suggest that TSA attenuates liver injury by inhibiting TLR-mediated inflammatory response during sepsis.

• 한국식품영양학회지
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• 제34권5호
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• pp.441-448
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• 2021

This study was designed to investigate the intracellular signaling pathways and immunoenhancing effect of macrophage activation by crude polysaccharides (CPP) extracted from citrus peels. CPP did not affect the cytotoxicity of RAW264.7 cells, but showed dose-dependent effects on cell viability. Also, CPP showed high production of chemokine (nitric oxide (NO)) and cytokines (interleukin (IL)-6 and tumor necrosis factor (TNF)-α). CPP increased IL-6, TNF-α, and inducible nitric oxide synthase (iNOS) mRNA expression dose-dependently. CPP also strongly induced the phosphorylation of the ERK, p38, and IκBα pathways in RAW 264.7 cells. In anti-pattern recognition receptors (PRRs) experiments, the effect of CPP on NO production was strongly suppressed by neutralizing toll-like receptor (TLR)2, TLR4, and Dectin1 antibodies, whereas IL-6 and TNF-α production by CPP was mainly suppressed by mannose receptor (MR). Therefore, these results suggest that CPP treatment-induced NO production was regulated by the ERK, p38, and NF-κB pathways through TLR2, TLR4, and Dectin1 receptors, whereas IL-6 and TNF-α production was primarily regulated by the ERK, p38, and NF-κB pathways through MR receptors.

• 한국해양바이오학회지
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• 제12권1호
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• pp.29-39
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• 2020

In this study, we investigated the inhibitory potential of an ethanol extract of Carpomitra costata (EECC) (Stackhouse) Batters, a brown alga, against neuroinflammatory responses in lipopolysaccharide (LPS)-stimulated BV2 microglia. Our results showed that EECC significantly suppressed the LPS-induced secretion of pro-inflammatory mediators, including nitric oxide (NO) and prostaglandin E₂, with no significant cytotoxic effects. EECC also inhibited the LPS-induced expression of their regulatory enzymes, such as inducible NO synthase and cyclooxygenase-2. In addition, EECC downregulated the LPS-induced expression and production of the proinflammatory cytokines, tumor necrosis factor-α and interleukin-1β. In the mechanistic assessment of the antineuroinflammatory effects, EECC was found to inhibit the nuclear translocation and DNA binding of nuclear factor-kappa B (NF-κB) by disrupting the degradation of the κB-α inhibitor in the cytoplasm. Moreover, EECC effectively suppressed the enhanced expression of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88, as well as the binding of LPS to TLR4 in LPS-treated BV2 cells. Furthermore, EECC markedly reduced the LPS-induced generation of reactive oxygen species (ROS), demonstrating a strong antioxidative effect. Collectively, these results suggest that EECC repressed LPS-mediated inflammatory action in the BV2 microglia through the inactivation of NF-κB signaling by antagonizing TLR4 and/or preventing ROS accumulation. While further studies are needed to fully understand the anti-inflammatory effects associated with the antioxidant activity of EECC, the current findings suggest that EECC has a potential advantage in inhibiting the onset and treatment of neuroinflammatory diseases.

• Journal of Ginseng Research
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• 제46권1호
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• pp.62-70
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• 2022

Background: Maternal Toxoplasma gondii (T. gondii) infection during pregnancy has been associated with various mental illnesses in the offspring. Ginsenoside Rh2 (GRh2) is a major bioactive compound obtained from ginseng that has an anti-T. gondii effect and attenuates microglial activation through toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. GRh2 also alleviated tumor-associated or lipopolysaccharide-induced depression. However, the effects and potential mechanisms of GRh2 on depression-like behavior in mouse offspring caused by maternal T. gondii infection during pregnancy have not been investigated. Methods: We examined GRh2 effects on the depression-like behavior in mouse offspring, caused by maternal T. gondii infection during pregnancy, by measuring depression-like behaviors and assaying parameters at the neuronal and molecular level. Results: We showed that GRh2 significantly improved behavioral measures: sucrose consumption, forced swim time and tail suspended immobility time of their offspring. These corresponded with increased tissue concentrations of 5-hydroxytryptamine and dopamine, and attenuated indoleamine 2,3-dioxygenase or enhanced tyrosine hydroxylase expression in the prefrontal cortex. GRh2 ameliorated neuronal damage in the prefrontal cortex. Molecular docking results revealed that GRh2 binds strongly to both TLR4 and high mobility group box 1 (HMGB1). Conclusion: This study demonstrated that GRh2 ameliorated the depression-like behavior in mouse offspring of maternal T. gondii infection during pregnancy by attenuating the excessive activation of microglia and neuroinflammation through the HMGB1/TLR4/NF-κB signaling pathway. It suggests that GRh2 could be considered a potential therapy in preventing and treating psychiatric disorders in the offspring mice of mothers with prenatal exposure to T. gondii infection.