• Nutrition Research and Practice
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• v.10 no.6
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• pp.623-628
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• 2016

BACKGROUND/OBJECTIVES: Obesity-induced steatohepatitis accompanied by activated hepatic macrophages/Kupffer cells facilitates the progression of hepatic fibrinogenesis and exacerbates metabolic derangements such as insulin resistance. Heme oxyganase-1 (HO-1) modulates tissue macrophage phenotypes and thus is implicated in protection against inflammatory diseases. Here, we show that the flavonoid quercetin reduces obesity-induced hepatic inflammation by inducing HO-1, which promotes hepatic macrophage polarization in favor of the M2 phenotype. MATERIALS/METHODS: Male C57BL/6 mice were fed a regular diet (RD), high-fat diet (HFD), or HFD supplemented with quercetin (HF+Que, 0.5g/kg diet) for nine weeks. Inflammatory cytokines and macrophage markers were measured by ELISA and RT-PCR, respectively. HO-1 protein was measured by Western blotting. RESULTS: Quercetin supplementation decreased levels of inflammatory cytokines ($TNF{\alpha}$, IL-6) and increased that of the anti-inflammatory cytokine (IL-10) in the livers of HFD-fed mice. This was accompanied by upregulation of M2 macrophage marker genes (Arg-1, Mrc1) and downregulation of M1 macrophage marker genes ($TNF{\alpha}$, NOS2). In co-cultures of lipid-laden hepatocytes and macrophages, treatment with quercetin induced HO-1 in the macrophages, markedly suppressed expression of M1 macrophage marker genes, and reduced release of MCP-1. Moreover, these effects of quercetin were blunted by an HO-1 inhibitor and deficiency of nuclear factor E2-related factor 2 (Nrf2) in macrophages. CONCLUSIONS: Quercetin reduces obesity-induced hepatic inflammation by promoting macrophage phenotype switching. The beneficial effect of quercetin is associated with Nrf2-mediated HO-1 induction. Quercetin may be a useful dietary factor for protecting against obesity-induced steatohepatitis.

• Journal of the Korean Institute of Oriental Medical Informatics
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• v.21 no.1
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• pp.14-22
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• 2015

Flavonoids show diverse bioactivities, such as anti-oxidant, anti-cancer, anti-allergic, anti-inflammatory, and anti-viral. Quercetin is one of the flavonoids present in a wide range of plants, especially onions and consumed all over the world. Recently, it is known that quercetin induces mitochondrial biogenesis in vivo and in vitro. However, detail mechanism of these actions remains unknown. We investigated quercetin's effects on mitochondrial biogenesis in HepG2 cells, and determined the mechanisms involved. We found that quercetin treatment induced the expression of mitochondrial biogenesis activators, $PGC-1{\alpha}$, NRF-1, TFAM, and mitochondrial proteins, cytochorome c and complex IV (COXIV). Moreover, amount of mitochondrial DNA was also increased by quercetin. Quercetin has been known to induce heme oxygenase (HO)-1 in several types of cells. Here, we found quercetin induces HO-1, and inhibition of HO-1 or CO, which is product of HO-1, decreased quercetin-induced mitochondrial biogenesis such as induction of $PGC-1{\alpha}$, NRF-1, TFAM, cytochorome c, COXIV, and mitochondrial DNA. These findings imply that quercetin can increase mitochondrial biogenesis via HO-1/CO system. High glucose results in dysfunction of mitochondria biogenesis. In the present study, 25 mM glucose decreased mitochondrial biogenesis and this damage was restored by quercetin. Conversely, inhibition of HO-1 or CO inhibited quercetin-induced mitochondrial biogenesis rescue. These results suggest that quercetin enhances mitochondrial biogenesis via HO-1/CO system and hence, can rescue mitochondria from damage by high glucose.

• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.518-526
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• 2019

Pueraria montana var. lobata is a bioactive substance with various beneficial health effects and has long been extensively used as a traditional medication for the treatment of fever, acute dysentery, diabetes, and cardiovascular diseases in Northeast Asian countries. The purpose of this study was to evaluate the cytoprotective activity of Pueraria montana var. lobata ethanol extract (PLE) for ultraviolet B (UVB)-induced oxidative stress in human dermal fibroblasts (HDF). It was hypothesized that PLE treatment ($25-100{\mu}g/ml$) would reduce intracellular reactive oxygen species (ROS) levels as well as increase collagen production in UVB-irradiated HDF. The results confirmed this theory, with collagen production increasing in the PLE treatment group in a dose-dependent manner. In addition, regulators of cellular ROS accumulation, including HO-1 and NOQ-1, were activated by Nrf2, which was mediated by PLE. Hence, intracellular levels of ROS were also reduced in the PLE treatment group in a dose-dependent manner. In conclusion, PLE increases collagen production and maintains hyaluronic acid (HA) levels in human dermal fibroblasts exposed to UVB-irradiation, thereby inhibiting photoaging.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.230-236
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• 2009

Acrolein, a known toxin in cigarette smoke, is the most abundant electrophilic $\alpha$, $\beta$-unsaturated aldehyde to which humans are exposed in a variety of environmental pollutants, and is also product of lipid peroxidation. Increased unsaturated aldehyde levels and reduced antioxidant status plays a major role in the pathogenesis of various diseases such as diabetes, Alzheimer's and atherosclerosis. The findings reported here show that low concentrations of acrolein induce heme oxygenase-1 (HO-1) expression in RAW 264.7 macrophages. HO-1 induction by acrolein and signal pathways was measured using reverse transcription-polymerase chain reaction, Western blot and immunofluorescence staining analyses. Inhibition of extracellular signal-regulated kinase activity significantly attenuated the induction of HO-1 protein by acrolein, while suppression of Jun N-terminal kinase and p38 activity did not affect induction of HO-1 expression. Moreover, rottlerin, an inhibitor of protein kinase $\delta$, suppressed the upregulation of HO-1 protein production, possibly involving the interaction of NF-E2-related factor 2 (Nrf2), which has a key role as a HO-1 transcription factor. Acrolein elevated the nuclear translocation of Nrf2 in nuclear extraction. The results suggest that RAW 264.7 may protect against acrolein-mediated cellular damage via the upregulation of HO-1, which is an adaptive response to oxidative stress.

• Journal of Life Science
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• v.29 no.3
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• pp.325-331
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• 2019

Lettuce (Lactuca sativa L.) is one of the most popular green leafy vegetables, and it contains various beneficial components including polyphenolic compounds and has been known to possess various biological functions such as anti-microbial, anti-oxidative, and anti-inflammatory activities. In the present study, we prepared ethanol extract of dried lettuce (DLE) and investigated its anti-inflammatory activity. To evaluate the anti-inflammatory activity of DLE, nitric oxide (NO) production was measured in LPS-activated mouse macrophage RAW 264.7 cells. DLE significantly suppressed NO production in these cells without affecting cell viabilities while resveratrol was used as a positive control. DLE dramatically decreased the expression of pro-inflammatory genes such as iNOS and COX-2 at the mRNA and protein levels and reduced the expression of several cytokines including $IL-1{\alpha}$, $IL-1{\beta}$, IL-1F6, $TNF-{\alpha}$, CSF2 and CXCL10. In addition, DLE suppressed phosphorylation of MAPKs and the nuclear translocation of $NF-{\kappa}B$ p65 indicating DLE shows its anti-inflammatory activity via regulating MAPKs pathway and $NF-{\kappa}B$ pathways. And also, DLE reduced the production of reactive oxygen species in a dose-dependent manner. DLE increased HO-1 protein expression, and also increased the nuclear translocation of Nrf2. Overall, our results suggest that lettuce down-regulate various pro-inflammatory genes and have its anti-inflammatory activity via regulating MAPKs, $NF-{\kappa}B$, and Nrf2/HO-1 pathways.

• Korean Journal of Food Science and Technology
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• v.51 no.1
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• pp.70-80
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• 2019

The aim of this study was to investigate the effects of red ginseng-derived non-saponin fraction (NSF) on inflammatory responses and monocyte-to-macrophage differentiation in RAW264.7 and THP-1. NSF effectively inhibited inflammatory responses by downregulating nitric oxide (NO) production and protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). NSF ($2000{\mu}g/mL$) decreased the levels of NO, iNOS, and COX-2 by 33, 83, and 64%, respectively. NSF inhibited the differentiation of monocyte-to-macrophage by decreasing cell adherence along with downregulation of the cluster of differentiation molecule $11{\beta}$ ($CD11{\beta}$) and CD36. In addition, pro-inflammatory cytokines, such as tumor necrosis factor-alpha, interleukin 6, and monocyte chemoattractant protein 1 (MCP-1), were significantly reduced with NSF treatment. The NSF-mediated inhibition of inflammatory responses was due to the regulation of nuclear factor kappa-light-chain-enhancer of activated B cells ($NF-{\kappa}B$) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2). NSF effectively suppressed the translocation of $NF-{\kappa}B$ into the nucleus, while nuclear Nrf2 and its target protein, heme oxygenase-1, levels were significantly increased.

• Korean Journal of Pharmacognosy
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• v.44 no.4
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• pp.379-383
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• 2013

Portulaca oleracea L. is known to have many biological benefits such as anti-oxidant, anti-inflammatory, anti-allergic and anti-tumor. The objective of this study is to explore the neuroprotective effect of P. oleracea L. against glutamate-induced oxidative stress in mouse hippocampal HT22 cells. P. oleracea L. 70% ethanol extract and solvent fractions have the potent neroprotective effects on glutamate-induced nerotoxicity by induced the expression of heme oxygenase (HO)-1 in HT22 cells. Especially, ethyl acetate fraction showed higher protective effect. In HT22 cell, P. oleracea L. treatment with ERK inhibitor (PD98059) and c-JUN N-terminal kinase (JNK) inhibitor (SP600125) reduced P. oleracea L. ethyl acetate fraction induced HO-1 expression and P. oleracea L. ethyl acetate fraction also increased ERK and JNK phosphorylation. Furthermore, we found that treatment of P. oleracea L. caused the nuclear accumulation of Nrf2. In conclusion, the ethyl acetate fraction of 70% ethanol extract of P. oleracea L. significantly protect glutamate-induced oxidative damage by induction of HO-1 via Nrf2, ERK and JNK pathway in mouse hippocampal HT22. Taken together these finding suggest that P. oleracea L. ethyl acetate fraction is good source for taking active compounds and may be a potential therapeutic agent for brain disorder that induced by oxidative stress and neuronal damage.

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.31-37
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• 2017

Glutamate-induced oxidative stress results in neuro-degenerative disorders in many central nervous system (CNS) such as Alzheimer's disease, ischemia, Huntington's disease, and Parkinson's disease. Our study was performed to investigate neuroprotective effects of Allium hookeri extracts (leaf, root, and whole) on glutamate-induced HT22 cells. In this study, ethanol extract of A. hookeri showed the outstanding neuroprotective effect in HT22 cells. In addition, we found that ethanol extract of A. hookeri root increased heme oxygenase (HO)-1 in HT22 cells. Moreover, ethanol extract of A. hookeri root also upregulated nuclear accumulation of nuclear factor E2-related factor 2 (Nrf2) in HT22 cells. These results demonstrate that ethanol extract of A. hookeri root contributes neuroprotective effects against glutamate-induced oxidative stress in HT22 cells, via Nrf2-mediated HO-1 expression. Our study suggests that ethanol extract of A. hookeri root could be the potential agent for the treatment of many neuro-degenerative diseases.

• Biomolecules & Therapeutics
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• v.19 no.4
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• pp.419-424
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• 2011

Galla Rhois and its components are known to possess anti-infl ammatory properties. In the present study, we prepared equilibrium mixture of ethyl m-digallate and ethyl p-digallate isomers (EDG) from Galla Rhois and examined its effect on nitric oxide (NO) production in murine macrophage cell line. Treatment of RAW264.7 macrophages with EDG signifi cantly inhibited NO production and inducible nitric oxide synthase (iNOS) expression stimulated by LPS, as assessed by Western blot and quantitative RT-PCR analyses. We also demonstrated that EDG treatment led to an increase in heme oxygenase-1 (HO-1) mRNA and protein expression. EDG treatment also enhanced expression level of nuclear factor-erythroid 2-related factor 2 (Nrf2) in nucleus, which is critical for transcriptional induction of HO-1. Treatment with SnPP (tin protoporphyrin IX), a selective HO-1 inhibitor, reversed EDG-mediated inhibition of nitrite production, suggesting that HO-1 plays an important role in the suppression of NO production by EDG. Taken together, these results indicate that EDG isolated from Galla Rhois suppresses LPS-stimulated NO production in RAW 264.7 macrophages via HO-1 induction.

• Korean Journal of Pharmacognosy
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• v.46 no.2
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• pp.116-122
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• 2015

Keratinocytes are first barrier against outer challenges on skin. However, it is still largely unknown about effective protectors against ultraviolet B (UVB), and oxidative stress in human keratinocyte, HaCaT cells. Inducible heme oxygenase (HO)-1 acts against oxidants that are thought to play a role in the pathogenesis of skin disorders. Therefore, the purpose of this study was to evaluate the effect of Portulaca oleracea 70% EtOH extracts against hydrogen peroxide (H₂O₂)-induced oxidative stress in human keratinocytes, HaCaT cells. P. oleracea 70% EtOH extracts showed the potent protective effects on H₂O₂-induced toxicity by induced the expression of HO-1 in human keratinocyte, HaCaT cells. Furthermore, P. oleracea 70 % EtOH extracts caused the nuclear accumulation of nuclear factor E2-related factor 2 (Nrf2) in human keratinocytes, HaCaT cells. In addition, we found that treatment with c-Jun N-terminal kinase (JNK) inhibitor (SP600125) reduced P. oleracea 70% EtOH extracts-induced HO-1 expression, and JNK inhibitor (SP600125) also inhibited protective effects by P. oleracea 70% EtOH extracts. Therefore, these results suggest that P. oleracea 70 % EtOH extracts increases cellular resistance to H₂O₂-induced oxidative injury in human keratinocyte, HaCaT cells, presumably through JNK pathway-Nrf2-dependent HO-1 expression.