• Molecules and Cells
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• v.43 no.3
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• pp.251-263
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• 2020

Flagellin, a major structural protein of the flagellum found in all motile bacteria, activates the TLR5- or NLRC4 inflammasome-dependent signaling pathway to induce innate immune responses. Flagellin can also serve as a specific antigen for the adaptive immune system and stimulate anti-flagellin antibody responses. Failure to recognize commensal-derived flagellin in TLR5-deficient mice leads to the reduction in anti-flagellin IgA antibodies at steady state and causes microbial dysbiosis and mucosal barrier breach by flagellated bacteria to promote chronic intestinal inflammation. Despite the important role of anti-flagellin antibodies in maintaining the intestinal homeostasis, regulatory mechanisms underlying the flagellin-specific antibody responses are not well understood. In this study, we show that flagellin induces interferon-β (IFN-β) production and subsequently activates type I IFN receptor signaling in a TLR5- and MyD88-dependent manner in vitro and in vivo. Internalization of TLR5 from the plasma membrane to the acidic environment of endolysosomes was required for the production of IFN-β, but not for other pro-inflammatory cytokines. In addition, we found that anti-flagellin IgG2c and IgA responses were severely impaired in interferon-alpha receptor 1 (IFNAR1)-deficient mice, suggesting that IFN-β produced by the flagellin stimulation regulates anti-flagellin antibody class switching. Our findings shed a new light on the regulation of flagellin-mediated immune activation and may help find new strategies to promote the intestinal health and develop mucosal vaccines.

• BMB Reports
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• v.54 no.2
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• pp.136-141
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• 2021

Thyroid eye disease (TED) is a complex autoimmune disease with a spectrum of signs. we previously reported that trisialoganglioside (GT)1b is significantly overexpressed in the orbital tissue of TED patients, and that exogenous GT1b strongly induced HA synthesis in orbital fibroblasts. However, the signaling pathway in GT1b-induced hyaluronic acid synthase (HAS) expression in orbital fibroblasts from TED patients have rarely been investigated. Here, we demonstrated that GT1b induced phosphorylation of Akt/mTOR in a dose-dependent manner in orbital fibroblasts from TED patients. Both co-treatment with a specific inhibitor for PI3K and siRNA knockdown of TLR2 attenuated GT1b-induced Akt phosphorylation. GT1b significantly induced HAS2 expression at both the transcriptional and translational level, which was suppressed by specific inhibitors of PI3K or Akt/mTOR, and by siRNA knockdown of TLR2. In conclusion, GT1b induced HAS2 in orbital fibroblasts from TED patients via activation of the PI3K-related signaling pathway, dependent on TLR2.

• Biomolecules & Therapeutics
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• v.31 no.1
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• pp.27-39
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• 2023

Extensive research supported the therapeutic potential of curcumin, a naturally occurring compound, as a promising cytokine-suppressive anti-inflammatory drug. This study aimed to investigate the synergistic anti-inflammatory and anti-cytokine activities by combining 6-shogaol and 10-shogaol to curcumin, and associated mechanisms in modulating lipopolysaccharides and interferon-γ-induced proinflammatory signaling pathways. Our results showed that the combination of 6-shogaol-10-shogaolcurcumin synergistically reduced the production of nitric oxide, inducible nitric oxide synthase, tumor necrosis factor and interlukin-6 in lipopolysaccharides and interferon-γ-induced RAW 264.7 and THP-1 cells assessed by the combination index model. 6-shogaol-10-shogaol-curcumin also showed greater inhibition of cytokine profiling compared to that of 6-shogaol-10-shogaol or curcumin alone. The synergistic anti-inflammatory activity was associated with supressed NFκB translocation and downregulated TLR4-TRAF6-MAPK signaling pathway. In addition, SC also inhibited microRNA-155 expression which may be relevant to the inhibited NFκB translocation. Although 6-shogaol-10-shogaol-curcumin synergistically increased Nrf2 activity, the anti-inflammatory mechanism appeared to be independent from the induction of Nrf2. 6-shogaol-10-shogaol-curcumin provides a more potent therapeutic agent than curcumin alone in synergistically inhibiting lipopolysaccharides and interferon-γ induced proinflammatory mediators and cytokine array in macrophages. The action was mediated by the downregulation of TLR4/TRAF6/MAPK pathway and NFκB translocation.

• 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.

• Journal of Animal Science and Technology
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• v.62 no.3
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• pp.385-395
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• 2020

Polyinosinic:polycytidylic acid (poly[I:C]) can stimulate Toll-like receptor 3 (TLR3) signaling pathways. In this study, DF-1 cells were treated with poly(I:C) at various concentrations and time points to examine the comparative expression patterns of innate immune response genes. The viability of DF-1 cells decreased from 77.41% to 38.68% when cells were treated different dose of poly(I:C) from 0.1 ㎍/mL to 100 ㎍/mL for 24 h respectively. The expressions of TLR3, TLR4, TLR7, TLR15, TLR21, IL1B, and IL10 were increased in dose- and time-dependent manners by poly(I:C) treatment. On the contrary, the expression patterns of interferon regulatory factors 7 (IRF7), Jun proto-oncogene, AP-1 transcription factor subunit (JUN), Nuclear Factor Kappa B Subunit 1 (NF-κB1), and IL8L2 were varied; IRF7 and IL8L2 were increasingly expressed whereas the expressions of JUN and NF-κB1 were decreased in a dose-dependent manner after they were early induced. In time-dependent analysis, IRF7 expression was significantly upregulated from 3 h to 24 h, whereas JUN and NF-κB1 expressions settled down from 6 h to 24 h after poly(I:C) treatment although they were induced at early time from 1 h to 3 h. Poly(I:C) treatment rapidly increased the expression of IL8L2 from 3 h to 6 h with a plateau at 6 h and then the expression of IL8L2 was dramatically decreased until 24 h after poly(I:C) treatment although the expression level was still higher than the non-treated control. These results may provide the basis for understanding host response to viral infection and its mimicry system in chickens.

• 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.

• 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.

• Molecular & Cellular Toxicology
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• v.5 no.2
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• pp.147-152
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• 2009

This study was conducted to evaluate the inflammatory mechanisms of LPS-stimulated BV-2 microglial cells. The inflammation mechanism was evaluated in BV-2 cells with or without LPS treated using the Affymetrix microarray analysis system. The microarray analysis revealed that B cell receptor signaling pathway, cytokine-cytokine receptor interaction, Jak-STAT signaling pathway, MAPK signaling pathway, Neuro-active ligand-receptor interaction, TLR signaling path-way, and T cell receptor signaling pathway-related genes were up-regulated in LPS stimulated BV-2 cells. Selected genes were validated using real time RTPCR. These results can help an effective therapeutic approach to alleviating the progression of neuro-in-flammatory diseases.

• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.185-191
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• 2019

Nucleoporin 210 (Nup210) is associated with several physiological processes including muscle and neural cell differentiation, autoimmune diseases, and peripheral T cell homeostasis. Chicken Nup210 (chNup210) gene was originally identified as one of the differentially expressed genes (DEGs) in the kidney tissues of chicken. To elucidate the role of Nup210 in metabolic disease of chicken, we studied the molecular characteristics of chNup210 and analyzed its gene expression under the stimulation of Toll-like receptor 3 (TLR3) ligands. The Nup210 genomic DNA and amino acid sequences of various species including fowls, fishes, and mammals were retrieved from the Ensemble database and subjected to bioinformatics analyses. The expression of Nup210 from several chicken tissues was probed through qRT-PCR, and chicken fibroblast DF-1 cell line was used to determine the change in expression of chNup210 after stimulation with TLR3 ligand, polyinosinic-polycytidylic acid (poly (I:C)). The chNup210 gene was highly expressed in chicken lung and spleen tissues. Although highly conserved among the species, chNup210 was evolutionary clustered in the same clade as that of duck compared to other mammals. Furthermore, this study revealed that chNup210 is expressed in TLR3 signaling pathway and provides fundamental information on Nup210 expression in chicken. Future studies that offer insight into the involvement of chNup210 in the chicken innate immune response against viral infection are recommended.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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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.