• Molecules and Cells
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• v.25 no.2
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• pp.253-257
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• 2008

Acrolein is a highly electrophilic ${\alpha},{\beta}$-unsaturated aldehyde present in a number of environmental sources, especially cigarette smoke. It reacts strongly with the thiol groups of cysteine residues by Michael addition and has been reported to inhibit nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) activation by lipopolysaccharide (LPS). The mechanism by which it inhibits $NF-{\kappa}B$ is not clear. Toll-like receptors (TLRs) play a key role in sensing microbial components and inducing innate immune responses, and LPS-induced dimerization of TLR4 is required for activation of downstream signaling pathways. Thus, dimerization of TLR4 may be one of the first events involved in activating TLR4-mediated signaling pathways. Stimulation of TLR4 by LPS activates both myeloid differential factor 88 (MyD88)- and TIR domain-containing adapter inducing $IFN{\beta}$ (TRIF)-dependent signaling pathways leading to activation of $NF-{\kappa}B$ and IFN-regulatory factor 3 (IRF3). Acrolein inhibited $NF-{\kappa}B$ and IRF3 activation by LPS, but it did not inhibit $NF-{\kappa}B$ or IRF3 activation by MyD88, inhibitor ${\kappa}B$ kinase $(IKK){\beta}$, TRIF, or TNF-receptor-associated factor family member-associated $NF-{\kappa}B$ activator (TANK)-binding kinase 1 (TBK1). Acrolein inhibited LPS-induced dimerization of TLR4, which resulted in the down-regulation of $NF-{\kappa}B$ and IRF3 activation. These results suggest that activation of TLRs and subsequent immune/inflammatory responses induced by endogenous molecules or chronic infection can be modulated by certain chemicals with a structural motif that enables Michael addition.

• Molecular & Cellular Toxicology
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• v.5 no.2
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• pp.141-146
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• 2009

Toll-like receptors (TLRs) induce innate immune responses by recognizing conserved microbial structural molecules. All TLR signaling pathways culminate in the activation of nuclear factor kappa-B (NF-$\kappa$B) leading to the induction of inflammatory gene products such as cyclooxygenase-2 (COX-2). Deregulated activation of TLRs can lead to the development of severe systemic inflammation. Divalent heavy metals, cadmium and mercury, have been used for thousands of years. While cadmium and mercury are clearly toxic to most mammalian organ systems, especially the immune system, their underlying toxic mechanism(s) remain unclear. Here, we report biochemical evidence that cadmium, but not mercury, inhibits NF-$\kappa$B activation and COX-2 expression induced by TLR2 or TLR4 agonists, while cadmium does not inhibit NF-$\kappa$B activation induced by the downstream signaling component of TLRs, MyD88. Thus, the target of cadmium to inhibit NF-$\kappa$B activation may be upstream of MyD88 including TLRs themselves, or events leading to TLR activation by agonists.

• 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.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.332-336
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• 2008

Ginger is widely used as a traditional herbal medicine. Both ginger and its extracts have been used to treat many chronic inflammatory conditions via the inhibition of nuclear factor-kappa B (NF-${\kappa}B$) activation, which results in the suppression of cyclooxygenase-2 (COX-2) expression. However, the mechanisms as to how ginger extracts mediate their health effects are largely unknown. Toll-like receptors (TLRs) trigger anti-microbial innate immune responses, recognizing conserved microbial structural molecules that are known as pathogen-associated molecular patterns. All TLR signaling pathways culminate in the activation of NF-${\kappa}B$. The activation of NF- ${\kappa}B$ leads to the induction of inflammatory gene products, including cytokines and COX-2. This study reports the biochemical evidence that 6-shogaol, an active compound in ginger, inhibits NF-${\kappa}B$ activation and COX-2 expression induced by TLR2, TLR3, and TLR4 agonists. Furthermore, 6-shogaol inhibited NF-${\kappa}B$ activation induced by the following downstream signaling components of the TLRs: MyD88, $IKK{\beta}$, and p65. These results imply that ginger can modulate immune responses that could potentially modify the risk of many chronic inflammatory diseases.

• Journal of Life Science
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• v.18 no.12
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• pp.1637-1643
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• 2008

This study has investigated whether extracellular HSP90 predisposes vascular smooth muscle cells (VSMCs) to pro-inflammatory phenotype. Exposure of rat aortic smooth muscle cells to HSP90 not only enhanced IL-6 release but also profoundly induced IL-6 transcript via promoter activation. HSP90-induced IL-6 promoter activation was suppressed by dominant-negative forms of Toll-like receptor (TLR)-4 and myeloid differentiation factor 88 (MyD88), but not by dominant-negative-forms of TLR-3 and TIR-domain-containing adapter-inducing interferon-${\beta}$ (TRIF). Curcumin, which inhibits dimerization of TLR-4, also attenuated the IL-6 induction by HSP90. Mutation at the NF-${\kappa}B$- or C/EBP-binding site in the IL-6 promoter region suppressed the promoter activation in response to HSP90. The gene delivery of $I{\kappa}B$ using recombinant adenoviruses and treatment with resveratrol, which inhibit NF-${\kappa}B$ activity, attenuated the HSP90-induced IL-6 release from VSMCs. The present study proposes that extracellular HSP90 would contribute to inflammatory reaction in the stressed vasculature by inducing IL-6 in VSMCs, and that TLR-4 and NF-${\kappa}B$ would play active roles in the process.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.335-345
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• 2022

Pyroptosis is an inflammatory form of programmed cell death that is linked with invading intracellular pathogens. Cardiac pyroptosis has a significant role in coronary microembolization (CME), thus causing myocardial injury. Tanshinone IIA (Tan IIA) has powerful cardioprotective effects. Hence, this study aimed to identify the effect of Tan IIA on CME and its underlying mechanism. Forty Sprague-Dawley (SD) rats were randomly grouped into sham, CME, CME + low-dose Tan IIA, and CME + high-dose Tan IIA groups. Except for the sham group, polyethylene microspheres (42 ㎛) were injected to establish the CME model. The Tan-L and Tan-H groups received intraperitoneal Tan IIA for 7 days before CME. After CME, cardiac function, myocardial histopathology, and serum myocardial injury markers were assessed. The expression of pyroptosis-associated molecules and TLR4/MyD88/NF-κB/NLRP3 cascade was evaluated by qRT-PCR, Western blotting, ELISA, and IHC. Relative to the sham group, CME group's cardiac functions were significantly reduced, with a high level of serum myocardial injury markers, and microinfarct area. Also, the levels of caspase-1 p20, GSDMD-N, IL-18, IL-1β, TLR4, MyD88, p-NF-κB p65, NLRP3, and ASC expression were increased. Relative to the CME group, the Tan-H and Tan-L groups had considerably improved cardiac functions, with a considerably low level of serum myocardial injury markers and microinfarct area. Tan IIA can reduce the levels of pyroptosis-associated mRNA and protein, which may be caused by inhibiting TLR4/MyD88/NF-κB/NLRP3 cascade. In conclusion, Tanshinone IIA can suppress cardiomyocyte pyroptosis probably through modulating the TLR4/MyD88/NF-κB/NLRP3 cascade, lowering cardiac dysfunction, and myocardial damage.

• Journal of the Korean Society of Food Culture
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• v.33 no.4
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• pp.337-344
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• 2018

Germinated brown rice (GBR, Orysa sartiva L.) has been reported to have anti-obesity and anti-inflammatory effects. However, the mechanisms underlying these effects in adipocytes are not fully understood. Therefore, this study was conducted to explore the anti-inflammatory mechanisms of GBR on lipopolysaccharide (LPS)-stimulated 3T3-L1 adipocytes. 3T3-L1 adipocytes were pretreated with GBR extracts (0-20 mg/mL) 1 h before LPS stimulation. The mRNA expression of adipokines and Toll-like receptor 4 (TLR4) were measured by RT-PCR. The protein expressions of TLR4-related molecules were detected by western blotting and nuclear factor-${\kappa}B$ ($NF-{\kappa}B$) activation was measured. Our results showed that GBR extract dose-dependently inhibited mRNA expression of LPS-induced tumor necrosis factor-${\alpha}$ ($TNF-{\alpha}$), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1). GBR extract was found to inhibit LPS-induced mRNA expression of TLR4 and protein expression of both myeloid differentiation factor 88 (MyD88) and TNF receptor-associated factor 6 (TRAF6). Furthermore, GBR extract significantly inhibited extracellular receptor-activated kinase (ERK) phosphorylation and $NF-{\kappa}B$ activation. These results suggest that GBR extract has the anti-inflammatory effects on LPS-induced inflammation via inhibition of TLR4 signaling, includingthe ERK and $NF-{\kappa}B$ signaling pathways, in adipocytes.

• The Korean Journal of Food And Nutrition
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• v.27 no.6
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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.

• Biomedical Science Letters
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• v.15 no.3
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• pp.257-260
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• 2009

Toll-like receptors (TLRs) recognize molecular structures derived from microbes including bacteria, viruses, yeast, and fungi. TLRs have emerged as a major signaling component of the mammalian host defense. TLR4 is a member of the Toll family that senses lipopolysaccharide (LPS), a cell wall component of gram negative bacteria. LPS recognition by TLR4 requires an additional accessory molecule, MD-2. LPS induces the activation of NF-${\kappa}B$ and IRF3 through MyD88 or TRIF-dependent pathways. The activation of NF-${\kappa}B$ leads to the induction of inflammatory gene products including cytokines and cyclooxygenase-2 (COX-2). This study was carried out to investigate the anti-inflammatory effects of oak wood vinegar. Oak wood vinegar inhibits the NF-${\kappa}B$ activation and COX-2 expression induced by LPS. These results provide new ideas to understand the mechanism of oak wood vinegar for its anti-bacterial and anti-inflammatory activities.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.2
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• pp.143-155
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• 2023

Percutaneous coronary intervention and acute coronary syndrome are both closely tied to the frequently occurring complication of coronary microembolization (CME). Resveratrol (RES) has been shown to have a substantial cardioprotective influence in a variety of cardiac diseases, though its function and potential mechanistic involvement in CME are still unclear. The forty Sprague-Dawley rats were divided into four groups randomly: CME, CME + RES (25 mg/kg), CME + RES (50 mg/kg), and sham (10 rats per group). The CME model was developed. Echocardiography, levels of myocardial injury markers in the serum, and histopathology of the myocardium were used to assess the function of the cardiac muscle. For the detection of the signaling of TLR4/MyD88/NF-κB along with the expression of pyroptosis-related molecules, ELISA, qRT-PCR, immunofluorescence, and Western blotting were used, among other techniques. The findings revealed that myocardial injury and pyroptosis occurred in the myocardium following CME, with a decreased function of cardiac, increased levels of serum myocardial injury markers, increased area of microinfarct, as well as a rise in the expression levels of pyroptosis-related molecules. In addition to this, pretreatment with resveratrol reduced the severity of myocardial injury after CME by improving cardiac dysfunction, decreasing serum myocardial injury markers, decreasing microinfarct area, and decreasing cardiomyocyte pyroptosis, primarily by blocking the signaling of TLR4/MyD88/NF-κB and also reducing the NLRP3 inflammasome activation. Resveratrol may be able to alleviate CME-induced myocardial pyroptosis and cardiac dysfunction by impeding the activation of NLRP3 inflammasome and the signaling pathway of TLR4/MyD88/NF-κB.