• IMMUNE NETWORK
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• 제11권4호
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• pp.223-226
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• 2011

Although exercise-induced growth factors such as Insulin-like growth factor-I (IGF-I) are known to affect various aspects of physiology in skeletal muscle cells, the molecular mechanism by which IGF-I modulates anti-inflammatory effects in these cells is presently unknown. Here, we showed that IGF-I stimulation suppresses the expression of toll-like receptor 4 (TLR4), a key innate immune receptor. A pharmacological inhibitor study further showed that PI3K/Akt signaling pathway is required for IGF-I-mediated negative regulation of TLR4 expression. Furthermore, IGF-I treatment reduced the expression of various NF-${\kappa}B$-target genes such as TNF-${\alpha}$ and IL-6. Taken together, these findings indicate that the anti-inflammatory effect of exercise may be due, at least in part, to IGF-I-induced suppression of TLR4 and subsequent downregulation of the TLR4-dependent inflammatory signaling pathway.

• IMMUNE NETWORK
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• 제9권4호
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• pp.127-132
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• 2009

Background: Toll-like receptors (TLRs) play a fundamental role in innate immunity through their capacity to recognize pathogen-associated molecular patterns. Also, TLRs that are expressed in T cells are reported to function as co-stimulatory receptors. However, the functional capacity of TLRs on CD4 T and CD8 T cells has not been directly compared. Here we compared CD4 and CD8 T cell responses to TLR2 ligand plus TCR-mediated stimulation. Methods: TLR2 expression was analyzed on T cell subsets under naive and alloantigen-primed conditions. We analyzed the effects of TLR2 co-stimulation on proliferation and survival of T cell subsets in vitro when stimulated with soluble anti-CD3 in the presence or absence of synthetic ligand $Pam_3CSK_4$. Results: TLR2 expression on CD8 T cells was induced following activation; this expression was much higher than on CD4 T cells. Thus, the molecule was constitutively expressed on Listeriaspecific memory CD8 T cells. Based on these expression levels, proliferation and survival were markedly elevated in CD8 T cells in response to the TLR2 co-stimulation by $Pam_3CSK_4$ compared with those in CD4 T cells. Conclusion: Our data show that TLR2 co-stimulation is more responsible for proliferation and survival of CD8 T cells than for that of CD4 T cells.

• 한국식품영양학회지
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• 제27권6호
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• pp.1141-1146
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• 2014

The purpose of this study is to investigate the effects of arabinoxylan rice bran and endurance exercise training on TLR4 mediated protein expression in LPS-treated rats. The results showed that TLR4 as an important protein in the inflammatory response against lipopolysaccharide was shown to be significantly lower in both arabinoxylan supplement with exercise group and exercise group, thus the arabinoxylan rice bran had a higher inhibitory activity than arabinoxylan supplement group. However, $NF-{\kappa}B$ and MyD88 protein expression was not changed in arabinoxylan supplement with exercise training group, whereas $NF-{\kappa}B$ significantly decreased in 4 weeks of exercise training group. These results suggest that the supplement of arabinoxylan rice bran with exercise is likely to contribute to inflammation response and the arabinoxylan rice bran can be used as a possible safe alternative to the immunotherapeutic intervention.

• 생명과학회지
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• 제28권6호
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• pp.718-725
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• 2018

Toll 유사수용체의 TLR4는 세포자연사(apoptosis)와 관련하여 세포의 생존과 증식에 영향을 미치는 것으로 알려져 있다. 본 연구에서는 TLR4의 활성이 부인과 질환 특이적 종양세포의 세포사멸기작에 어떠한 영향을 미치는지 살펴보았다. TLR4의 활성에 의한 세포자연사를 확인하기 위하여 부인암 조직(자궁경부암, 자궁내막암, 난소암)에서 종양세포를 분리하여 초대배양시스템을 구축하였고, lipopolysaccharide (LPS)에 의한 TLR4의 활성유도 과정에서 종양세포의 형태학적 변화를 살펴보았다. 또한, TLR4 매개성 세포사멸 기작을 확인하기 위하여 역전사 중합효소 연쇄반응(RT-PCR)을 통해 유전자 분석을 진행하였다. 연구 결과, 부인암의 초대배양세포에서 세포접촉저지(contact inhibition)현상이 감소되었고, 세포의 배가시간(doubling time)이 단축되어, 종양세포의 성장률 변화를 확인하였다(p<0.05). 자궁근육층(정상조직)의 초대배양세포에서는 민무늬근육 확인 인자인 ITGA5 (an alpha5 integrin marker)의 유전자 발현이 나타났으나, 자궁경부조직의 초대배양세포에서는 발현변화를 확인할 수 없었다. 종양세포의 유전자분석 결과에서 p53과 같은 종양억제인자의 발현이 유의적으로 증가한 반면(p<0.05), 세포사멸 신호기작과 관련하여 TLR4와 Caspase-3의 발현은 감소하였다(Caspase-3, p<0.05). LPS를 처리한 종양세포에서는 LPS 비처리군과 비교 시, TLR4의 발현증가와 함께 Caspase-3의 발현변화가 동반되었다. 이러한 결과들은 TLR4 매개성 apoptosis 유도가 종양세포의 증식억제에 중요한 영향을 미치는 것을 의미하며, TLR4 신호기작을 이용한 종양세포의 새로운 치료적 접근법을 제시할 것으로 기대한다.

• IMMUNE NETWORK
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• 제22권6호
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• pp.49.1-49.15
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• 2022

Exosomes derived from mesenchymal stem cells (MSCs) could protect against myocardial infarction (MI). TLR4 is reported to play an important role in MI, while microRNA-182-5p (miR-182-5p) negatively regulates TLR4 expression. Therefore, we hypothesize that MSCs-derived exosomes overexpressing miR-182-5p may have beneficial effects on MI. We generated bone marrow mesenchymal stem cells (BM-MSCs) and overexpressed miR-182-5p in these cells for exosome isolation. H₂O₂-stimulated neonatal mouse ventricle myocytes (NMVMs) and MI mouse model were employed, which were subjected to exosome treatment. The expression of inflammatory factors, heart function, and TLR4 signaling pathway activation were monitored. It was found that miR-182-5p decreased TLR4 expression in BM-MSCs and NMVMs. Administration of exosomes overexpressing miR-182-5p to H₂O₂-stimulated NMVMs enhanced cell viability and suppressed the expression of inflammatory cytokines. In addition, they promoted heart function, suppressed inflammatory responses, and de-activated TLR4/NF-κB signaling pathway in MI mice. In conclusion, miR-182-5p transferred by the exosomes derived from BM-MSCs protected against MI-induced impairments by targeting TLR4.

• Molecules and Cells
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• 제38권1호
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• pp.26-32
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• 2015

Toll-like receptors (TLR) 7 and 9 transduce a cellular signal through the MyD88-dependent pathway and induce the production of inflammatory mediators against microbial nucleotide components. The repeated stimulation of TLR4 leads to endotoxin tolerance, but the molecular mechanisms of tolerance induced through the costimulation of individual TLR has not yet been established, although endosomal TLRs share signaling pathways with TLR4. In the present study, mouse macrophages were simultaneously stimulated with the TLR7 agonist, gardiquimod (GDQ), and the TLR9 agonist, CpG ODN 1826, to examine the mechanism and effector functions of macrophage tolerance. Compared with individual stimulation, the costimulation of both TLRs reduced the secretion of TNF-${\alpha}$ and IL-6 through the delayed activation of the NF-${\kappa}B$ pathway; notably, IL-10 remained unchanged in costimulated macrophages. This tolerance reflected the early induction of suppressor of cytokine signaling-1 (SOCS-1), according to the detection of elevated TNF-${\alpha}$ secretion and restored NF-${\kappa}B$ signaling in response to the siRNA-mediated abrogation of SOCS-1 signaling. In addition, the restimulation of each TLRs using the same ligand significantly reduced the expression of both TLRs in endosomes. These findings revealed that the costimulation of TLR7 and TLR9 induced macrophage tolerance via SOCS-1, and the restimulation of each receptor or both TLR7 and TLR9 downregulated TLR expression through a negative feedback mechanisms that protects the host from excessive inflammatory responses. Moreover, the insufficient and impaired immune response in chronic viral infection might also reflect the repeated and simultaneous stimulation of those endosomal TLRs.

• Clinical and Experimental Reproductive Medicine
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• 제45권4호
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• pp.154-162
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• 2018

Objective: The fallopian tubes play a critical role in the early events of fertilization. The rapid innate immune defense is an important part of the fallopian tubes. Toll-like receptor 3 (TLR3), as a part of the innate immune system, plays an important role in detecting viral infections. In this basic and experimental study, the effect of sex hormones on the function of TLR3 in the OE-E6/E7 cell line was investigated. Methods: The functionality of TLR3 in this cell line was evaluated by cytokine measurements (interleukin [IL]-6 and IL-1b) and the effects of sex hormones on TLR3 were tested by an enzyme-linked immunosorbent assay kit. Additionally, TLR3 small interfering RNA (siRNA) and a TLR3 function-blocking antibody were used to confirm our findings. Results: The production of IL-6 significantly increased in the presence of polyinosinic-polycytidylic acid (poly(I:C)) as the TLR3 ligand. Using a TLR3-siRNA-ransfected OE-E6/E7 cell line and function-blocking antibody confirmed that cytokine production was due to TLR3. In addition, 17-${\beta}$ estradiol and progesterone suppressed the production of IL-6 in the presence and absence of poly(I:C). Conclusion: These results imply that sex hormones exerted a suppressive effect on the function of TLR3 in the fallopian tube cell line when different concentrations of sex hormones were present. The current results also suggest that estrogen receptor beta and nuclear progesterone receptor B are likely to mediate the hormonal regulation of TLR3, as these two receptors are the main estrogen and progesterone receptors in OEE6/E7 cell line.

• Molecules and Cells
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• 제38권1호
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• pp.58-64
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• 2015

Activating transcription factor-3 (ATF3) acts as a negative regulator of cytokine production during Gram-negative bacterial infection. A recent study reported that ATF3 provides protection from Streptococcus pneumoniae infection by activating cytokines. However, the mechanism by which S. pneumoniae induces ATF3 after infection is still unknown. In this study, we show that ATF3 was upregulated via Toll-like receptor (TLR) pathways in response to S. pneumoniae infection in vitro. Induction was mediated by TLR4 and TLR2, which are in the TLR family. The expression of ATF3 was induced by pneumolysin (PLY), a potent pneumococcal virulence factor, via the TLR4 pathway. Furthermore, ATF3 induction is mediated by p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). Thus, this study reveals a potential role of PLY in modulating ATF3 expression, which is required for the regulation of immune responses against pneumococcal infection in macrophages.

• 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.

• 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.