• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.35-42
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• 2023

This study aimed to identify the therapeutic ability of a novel toll-like receptor (TLR) 5 agonist, KMRC011, on ulcerative colitis induced by Citrobacter rodentium and dextran sulfate sodium in a C57BL/6N mouse model. Ulcerative colitis was induced in the mice by the oral administration of 1% dextran sulfate sodium in sterile drinking water for seven days ad libitum, followed by C. rodentium infection on the seventh day by intra-gastric administration (DSS-CT group). KMRC011 was administered intramuscularly at both 24 h and 15 min before (Treatment 1 group), and at both 15 min and 24 h after (Treatment 2 group) the C. rodentium infection. The length of the large intestine and histopathological counts were significantly greater and mucosal thickness was significantly thinner in the Treatment 1 group compared to the DSS-CT and Treatment 2 groups. Il-6 and Il-10 mRNA expression levels were upregulated, while Ifn-γ and Tnf-α mRNA expression levels were significantly downregulated in the Treatment 1 group, compared to the DSS-CT group. NF-κB p65 expression level was elevated due to ulcerative colitis in the DSS-CT group, but was significantly downregulated in the Treatment 1 group. Overall, KMRC011 showed protective effects against murine colitis by inhibiting NF-κB signaling.

• BMB Reports
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• v.53 no.5
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• pp.284-289
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• 2020

Tamoxifen, a nonsteroidal estrogen receptor (ER) antagonist, is used routinely as a chemotherapeutic agent for ER-positive breast cancer. However, it is also causes side effects, including retinotoxicity. The retinal pigment epithelium (RPE) has been recognized as the primary target of tamoxifen-induced retinotoxicity. The RPE plays an essential physiological role in the normal functioning of the retina. Nonetheless, potential therapeutic agents to prevent tamoxifen-induced retinotoxicity in breast cancer patients have not been investigated. Here, we evaluated the action mechanisms of sulfasalazine against tamoxifen-induced RPE cell death. Tamoxifen induced reactive oxygen species (ROS)-mediated autophagic cell death and caspase-1-mediated pyroptosis in RPE cells. However, sulfasalazine reduced tamoxifen-induced total ROS and ROS-mediated autophagic RPE cell death. Also, mRNA levels of tamoxifen-induced pyroptosis-related genes, IL-1β, NLRP3, and procaspase-1, also decreased in the presence of sulfasalazine in RPE cells. Additionally, the mRNA levels of tamoxifen-induced AMD-related genes, such as complement factor I (CFI), complement factor H (CFH), apolipoprotein E (APOE), apolipoprotein J (APOJ), toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4), were downregulated in RPE cells. Together, these data provide novel insight into the therapeutic effects of sulfasalazine against tamoxifen-induced RPE cell death.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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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.

• Korean Journal of Food Science and Technology
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• v.41 no.5
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• pp.477-482
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• 2009

Toll-like receptors (TLRs) play a critical 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, namely MyD88- and TRIF-dependent pathways, leading to the activation of nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and interferon regulatory factor 3 (IRF3) and the expression of inflammatory mediators. TLR4 dimerization is required for the activation of downstream signaling pathways and may be one of the first lines of regulation in activating TLR-mediated signaling pathways. In this paper, the molecular targets of curcumin, 6-shogaol, and cinnamaldehyde in TLR signaling pathways will be discussed. Curcumin, 6-shogaol, and cinnamaldehyde with ${\alpha},{\beta}$-unsaturated carbonyl groups inhibit the dimerization of TLR4 induced by lipopolysaccharide, resulting in the downregulation of NF-${\kappa}B$ and IRF3. These results suggest that phytochemicals with the structural motif conferring Michael addition inhibit TLR4 dimerization, suggesting a novel mechanism for the anti-inflammatory activity of phytochemicals.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2807-2812
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• 2012

The purpose of this study was to examine the effect of a Toll-like receptor 5 (TLR5) agonist, CBLB502, on the growth and radiosensitivity of A549 lung cancer cells in vivo. Expression of myeloid differentiation factor 88 (MyD88) or TLR5 was stably knocked down in human lung cancer cells (A549) using lentivirus expressing short hairpin RNA targeting human MyD88 or TLR5. Lack of MyD88 or TLR5 expression enhanced tumor growth in mouse xenografts of A549 lung cancer cells. CBLB502 inhibited the growth of A549 lung cancer cells, not A549-MyD88-KD cells in vivo in the murine xenograft model. Our results showed that the inhibition of A549 by CBLB502 in vivo was realized through regulating the expression of neutrophil recruiting cytokines and neutrophil infiltration. Finally, we found that activation of TLR5 signaling did not affect the radiosensitivity of tumors in vivo.

• Korean Journal of Plant Resources
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• v.25 no.5
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• pp.561-567
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• 2012

Ellagic acid (EA) is a phenolic compound in fruits and nuts including raspberries, strawberries, grapes and walnuts. Previous studies have indicated that EA possesses antioxidant activity, growth-inhibition and apoptosis-promoting activity in cancer cells. However, macrophage mediated cytotoxicity and immunomodulating effects on cancer cells have not been clarified. In the present study, we show that EA increased effects on macrophage mediated tumoricidal activity and NO production without direct tumor cell cytotoxicity. To further determine whether TLR4 (toll like receptor 4) is involved in anti-tumor activity, cells were treated TLR4 signaling inhibitor, CLI-095 in the presence of EA. CLI-095 treatment partially reduced macrophage-mediated tumoridial activity. EA also has inhibitory effects of NO production induced by LPS, whereas phagocytic activity was not changed. These results suggest that EA induces macrophage mediated tumoricidal activity which is partially related to TLR4 signaling and has a potential adjuvant in cancer therapy.

• Biomolecules & Therapeutics
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• v.24 no.4
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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.

• Animal Bioscience
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• v.34 no.4
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• pp.489-498
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• 2021

Objective: Milk production is one of the most desirable traits in livestock. Recently, the toll-like receptor (TLR) has been identified as a candidate gene for milk traits in cows. So far, there is no information concerning the contribution of this gene in milk traits in sheep. This study was designed to investigate the TLR 4 gene polymorphisms in Barki ewes in Egypt and then correlate that with milk traits in order to identify potential single nucleotide polymorphisms (SNPs) for these traits in sheep. Methods: A part of the ovine TLR 4 gene was amplified in Barki ewes, to identify the SNPs. Consequently; Barki ewes were genotyped using polymerase chain reaction-single strand conformation polymorphism protocol. These genotypes were correlated with milk traits, which were the daily milk yield (DMY), protein percentage (PP), fat percentage (FP), lactose percentage, and total solid percentage (TSP). Results: Age and parity of the ewe had a significant effect (p<0.05 or p<0.01) on DMY, FP, and TSP. The direct sequencing identified a missense mutation located in the coding sequence of the gene (rs592076818; c.1710C>A) and was predicted to change the amino acid sequence of the resulted protein (p.Asn570Lys). The association analyses suggested a significant effect (p<0.05) of the TLR genotype on the FP and PP, while the DMY tended to be influenced as well (p = 0.07). Interestingly, the presence of the G allele tended to increase the DMY (+40.5 g/d) and significantly (p<0.05 or p<0.01) decreased the FP (-1.11%), PP (-1.21%), and TSP (-7.98%). Conclusion: The results of this study suggested the toll-like receptor 4 (TLR4) as a candidate gene to improve milk traits in sheep worldwide, which will enhance the ability to understand the genetic architecture of genes underlying SNPs that affect such traits.

• The Korean Journal of Pain
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• v.34 no.1
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• pp.47-57
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• 2021

Background: Lumbar disc herniation (LDH) is a common cause of radicular pain, but the mechanism is not clear. In this study, we investigated the engagement of toll-like receptor 4 (TLR4) and the nuclear factor-kappa B (NF-κB) in radicular pain and its possible mechanisms. Methods: An LDH model was induced by autologous nucleus pulposus (NP) implantation, which was obtained from coccygeal vertebra, then relocated in the lumbar 4/5 spinal nerve roots of rats. Mechanical and thermal pain behaviors were assessed by using von Frey filaments and hotplate test respectively. The protein level of TLR4 and phosphorylated-p65 (p-p65) was evaluated by western blotting analysis and immunofluorescence staining. Spinal microglia activation was evaluated by immunofluorescence staining of specific relevant markers. The expression of proand anti-inflammatory cytokines in the spinal dorsal horn was measured by enzyme linked immunosorbent assay. Results: Spinal expression of TLR4 and p-NF-κB (p-p65) was significantly increased after NP implantation, lasting up to 14 days. TLR4 was mainly expressed in spinal microglia, but not astrocytes or neurons. TLR4 antagonist TAK242 decreased spinal expression of p-p65. TAK242 or NF-κB inhibitor pyrrolidinedithiocarbamic acid alleviated mechanical and thermal pain behaviors, inhibited spinal microglia activation, moderated spinal inflammatory response manifested by decreasing interleukin (IL)-1β, IL-6, tumor necrosis factor-α expression and increasing IL-10 expression in the spinal dorsal horn. Conclusions: The study revealed that TLR4/NF-κB pathway participated in radicular pain by encouraging spinal microglia activation and inflammatory response.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.187-192
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• 2009

Toll-like receptors (TLRs) play an important role in host defense by sensing invading microbial pathogens. The stimulation of TLRs by microbial components triggers the activation of the myeloid differential factor 88 (MyD88)- and toll-interleukin-1 receptor domain-containing adapter inducing interferon-$\beta$ (TRIF)-dependent downstream signaling pathways. TLR/MyD88 signaling pathway induces the activation of nuclear factor-kappa B (NF-${\kappa}B$) and the expression of inflammatory cytokine genes, including tumor necrosis factor-alpha, interleukin (IL)-6, IL-12, and IL-$1{\beta}$. On the other hand, TLR/TRIF signaling pathway induces the delayed-activation of NF-${\kappa}B$ and interferon regulatory factor 3 (IRF3), and the expression of type I interferons (IFNs) and IFN-inducible genes. The divalent heavy metal cadmium (Cd) is clearly toxic to most mammalian organ systems, especially the immune system. Yet, the underlying toxic mechanism(s) remain unclear. Cd inhibits the MyD88-dependent pathway by ceasing the activity of inhibitor-${\kappa}B$ kinase. However, it is not known whether Cd inhibits the TRIF-dependent pathway. Presently, Cd inhibited NF-${\kappa}B$ and IRF3 activation induced by lipopolysaccharide (LPS) and polyinosinic-polycytidylic acid. Cd inhibited LPS-induced IRF3 phosphorylation and IFN-inducible genes such as interferon inducible protein-10 and regulated on activation normal T-cell expressed and secreted (RANTES). These results suggest that Cd can modulate TRIF-dependent signaling pathways of TLRs.