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Lee HH, Shin JS, Chung KS, Kim JM, Jung SH, Yoo HS, Hassan AHE, Lee JK, Inn KS, Lee S, Kim NJ, Lee KT. 3',4'-Dihydroxyflavone mitigates inflammatory responses by inhibiting LPS and TLR4/MD2 interaction. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 109:154553. [PMID: 36610153 DOI: 10.1016/j.phymed.2022.154553] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/04/2022] [Accepted: 11/15/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND We previously reported the potential inhibitory activity of 3',4'-dihydroxyflavone (DHF) on nitric oxide (NO) and prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-stimulated macrophages. PURPOSE We investigated the underlying molecular mechanisms of DHF in LPS-activated macrophages and evaluated its effect on LPS-induced septic shock in mice. METHODS To explore the anti-inflammatory effect of DHF, nitrite, PGE2, and cytokines were measured in vitro and in vivo experiments. In addition, to verify the molecular signaling pathway, quantitative real time-PCR, luciferase assay, nuclear extraction, electrophoretic mobility shift assay, immunocytochemistry, immunoprecipitation, molecular docking analysis, and myeloid differentiation 2 (MD2)-LPS binding assay were conducted. RESULTS DHF suppressed the LPS-induced expression of proinflammatory mediators through nuclear factor-κB (NF-κB), activator protein-1 (AP-1), and interferon regulatory factor 3 (IRF3) inactivation pathways in RAW 264.7 macrophages. Importantly, molecular docking analysis and in vitro binding assays showed that DHF interacts with the hydrophobic pocket of MD2 and then interferes with the interaction between LPS and toll-like receptor 4 (TLR4). DHF inhibited LPS-induced oxidative stress by upregulating nuclear factor erythroid 2-related factor 2 (Nrf2). Treatment of LPS-induced endotoxemia mice with DHF reduced the expression levels of pro-inflammatory mediators via the inactivation of NF-κB, AP-1, and signal transducer and activator of transcription 1 (STAT1) in the lung tissue, thus increasing the survival rate. CONCLUSION Taken together, our data first time revealed the underlying mechanism of the DHF-dependent anti-inflammatory effect by preventing LPS from binding to the TLR4/MD2 complex. Therefore, DHF may be a possible anti-inflammatory agent for the treatment of LPS-mediated inflammatory diseases.
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Affiliation(s)
- Hwi-Ho Lee
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea
| | - Ji-Sun Shin
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea
| | - Kyung-Sook Chung
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea
| | - Jae-Min Kim
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Seang-Hwan Jung
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Hyung-Seok Yoo
- College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Ahmed H E Hassan
- Medicinal Chemistry Laboratory, Department of Pharmacy, College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea; Department of Medicinal Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - Jong Kil Lee
- Department of Fundamental Pharmaceutical Science, Graduate School, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Kyung-Soo Inn
- Department of Pharmaceutical Science, College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Sangmin Lee
- College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea
| | - Nam-Jung Kim
- College of Pharmacy, Kyung Hee University, Seoul 02247, Republic of Korea.
| | - Kyung-Tae Lee
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02247, Republic of Korea.
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Hu X, Chakravarty SD, Ivashkiv LB. Regulation of interferon and Toll-like receptor signaling during macrophage activation by opposing feedforward and feedback inhibition mechanisms. Immunol Rev 2009; 226:41-56. [PMID: 19161415 DOI: 10.1111/j.1600-065x.2008.00707.x] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Activated macrophages and their inflammatory products play a key role in innate immunity and in pathogenesis of autoimmune/inflammatory diseases. Macrophage activation needs to be tightly regulated to rapidly mount responses to infectious challenges but to avoid toxicity associated with excessive activation. Rapid and potent macrophage activation is driven by cytokine-mediated feedforward loops, while excessive activation is prevented by feedback inhibition. Here we discuss feedforward mechanisms that augment macrophage responses to Toll-like receptor (TLR) ligands and cytokines that are mediated by signal transducer and activator of transcription 1 (STAT1) and induced by interferon-gamma (IFN-gamma). IFN-gamma also drives full macrophage activation by inactivating feedback inhibitory mechanisms, such as those mediated by interleukin-10 (IL-10), and STAT3. Priming of macrophages with IFN-gamma reprograms cellular responses to other cytokines, such as type I IFNs and IL-10, with a shift toward pro-inflammatory STAT1-dominated responses. Similar but partially distinct priming effects are induced by other cytokines that activate STAT1, including type I IFNs and IL-27. We propose a model whereby opposing feedforward and feedback inhibition loops crossregulate each other to fine tune macrophage activation. In addition, we discuss how dysregulation of the balance between feedforward and feedback inhibitory mechanisms can contribute to the pathogenesis of autoimmune and inflammatory diseases, such as rheumatoid arthritis and systemic lupus erythematosus.
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Affiliation(s)
- Xiaoyu Hu
- Arthritis and Tissue Degeneration Program, Hospital for Special Surgery, New York, NY, USA
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Natarajan M, Lin KM, Hsueh RC, Sternweis PC, Ranganathan R. A global analysis of cross-talk in a mammalian cellular signalling network. Nat Cell Biol 2006; 8:571-80. [PMID: 16699502 DOI: 10.1038/ncb1418] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 04/18/2006] [Indexed: 12/19/2022]
Abstract
Cellular information processing requires the coordinated activity of a large network of intracellular signalling pathways. Cross-talk between pathways provides for complex non-linear responses to combinations of stimuli, but little is known about the density of these interactions in any specific cell. Here, we have analysed a large-scale survey of pathway interactions carried out by the Alliance for Cellular Signalling (AfCS) in RAW 264.7 macrophages. Twenty-two receptor-specific ligands were studied, both alone and in all pairwise combinations, for Ca2+ mobilization, cAMP synthesis, phosphorylation of many signalling proteins and for cytokine production. A large number of non-additive interactions are evident that are consistent with known mechanisms of cross-talk between pathways, but many novel interactions are also revealed. A global analysis of cross-talk suggests that many external stimuli converge on a relatively small number of interaction mechanisms to provide for context-dependent signalling.
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Affiliation(s)
- Madhusudan Natarajan
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9050, USA
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Schneeman TA, Bruno MEC, Schjerven H, Johansen FE, Chady L, Kaetzel CS. Regulation of the polymeric Ig receptor by signaling through TLRs 3 and 4: linking innate and adaptive immune responses. THE JOURNAL OF IMMUNOLOGY 2005; 175:376-84. [PMID: 15972671 DOI: 10.4049/jimmunol.175.1.376] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
IgA Abs help to maintain homeostasis at mucosal surfaces by promoting defense mechanisms that protect against pathogens while suppressing inflammatory responses to commensal organisms and food Ags. The polymeric Ig receptor (pIgR) mediates transport of IgA across mucosal epithelial cells. We hypothesized that signaling through TLRs may up-regulate pIgR expression by intestinal epithelial cells and thus enhance IgA-mediated homeostasis. To test this hypothesis we treated the HT29 human intestinal epithelial cell line with dsRNA, a ligand for TLR3, or LPS, a ligand for TLR4. Both dsRNA and LPS up-regulated levels of pIgR mRNA and cell surface pIgR protein. By contrast, dsRNA but not LPS up-regulated expression of TLR3 and TLR4 mRNA. However, cell surface expression of both TLR3 and TLR4 was enhanced by treatment of HT29 cells with their respective ligands. Transfection of HT29 cells with wild-type and mutated promoter/enhancer plasmids suggested that TLR3 and TLR4 signal primarily through NF-kappaB to enhance transcription of pIgR mRNA. TLR3 signaling resulted in a more pronounced inflammatory response than did TLR4, as evidenced by up-regulation of the transcription factor IFN regulatory factor-1, chemokines IL-8 and RANTES, and the proinflammatory cytokine TNF. Signaling through LPS/TLR4 appears to up-regulate pIgR expression while minimizing proinflammatory responses, a mechanism that could promote IgA-mediated homeostasis in the presence of commensal Gram-negative bacteria.
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Affiliation(s)
- Tracey A Schneeman
- Department of Microbiology, Immunology and Molecular, University of Kentucky, Lexington, KY 40536, USA
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