quercetin-3-o-glucuronide and Inflammation

Pulmonary injury is defined as a progressive inflammation. Extensive pro-inflammatory cytokines are secreted from alveolus, associated with the production of reactive oxygen species (ROS) and apoptosis. The model of endotoxin lipopolysaccharide (LPS)-stimulated lung cells has been applied to mimic the pulmonary injury. Some antioxidants and anti-inflammatory compounds can be used as chemopreventive agents of pulmonary injury. Quercetin-3-glucuronide (Q3G) has been showed to exert antioxidant, anti-inflammatory, anti-cancer, anti-aging and anti-hypertension effects. The aim of the study is to examine the inhibitory potential of Q3G on pulmonary injury and inflammation in vitro and in vivo. Firstly, human lung fibroblasts MRC-5 cells pre-treated with LPS were demonstrated to cause survival loss and ROS generation, were recovered by Q3G. Q3G also exhibited the anti-inflammatory effects on the LPS-treated cells with a reduction in the activation of NLRP3 [nucleotide-binding and oligomerization domain (NOD)-like receptor protein 3] inflammasome, leading to pyroptosis. Also, Q3G showed the anti-apoptotic effect in the cells might be mediated via inhibition of mitochondrial apoptosis pathway. To further explore in vivo pulmonary-protective effect of Q3G, C57BL/6 mice were intranasally exposed to a combination of LPS and elastase (LPS/E) to perform the pulmonary injury model. The results revealed that Q3G ameliorated pulmonary function parameters and lung edema in the LPS/E-induced mice. Q3G also suppressed the LPS/E-stimulated inflammation, pyroptosis and apoptosis in the lungs. Taken together, this study suggested the lung-protective potential of Q3G via downregulation of inflammation, pyroptotic and apoptotic cell death, contributing to its chemopreventive activity of pulmonary injury.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Humans; Inflammation; Lipopolysaccharides; Lung Injury; Mice; Mice, Inbred C57BL; Reactive Oxygen Species

Quercetin-3-glucuronide (Q3GA), the main phase II metabolite of quercetin (Q) in human plasma, is considered to be a more stable form of Q for transport with the bloodstream to tissues, where it can be potentially deconjugated by β-glucuronidase (β-Gluc) to Q aglycone, which easily enters the brain. This study evaluates the effect of lipopolysaccharide (LPS)-induced acute inflammation on β-Gluc gene expression in the choroid plexus (ChP) and its activity in blood plasma, ChP and cerebrospinal fluid (CSF), and the concentration of Q and its phase II metabolites in blood plasma and CSF. Studies were performed on saline- and LPS-treated adult ewes (

Topics: Animals; Brain; Cell Line, Tumor; Choroid Plexus; Epithelial Cells; Female; Glucuronidase; Humans; Inflammation; Lipopolysaccharides; Male; Primary Cell Culture; Quercetin; Rats; Rats, Wistar; Sheep

An impaired capacity of adipose tissue expansion leads to adipocyte hypertrophy, inflammation and insulin resistance (IR) under positive energy balance. We previously showed that a grape pomace extract, rich in flavonoids including quercetin (Q), attenuates adipose hypertrophy. This study investigated whether dietary Q supplementation promotes adipogenesis in the epididymal white adipose tissue (eWAT) of rats consuming a high-fat diet, characterizing key adipogenic regulators in 3T3-L1 pre-adipocytes. Consumption of a high-fat diet for 6 weeks caused IR, increased plasma TNFα concentrations, eWAT weight, adipocyte size and the eWAT/brown adipose tissue (BAT) ratio. These changes were accompanied by decreased levels of proteins involved in angiogenesis, VEGF-A and its receptor 2 (VEGF-R2), and of two central adipogenic regulators, i.e. PPARγ and C/EBPα, and proteins involved in mature adipocyte formation, i.e. fatty acid synthase (FAS) and adiponectin. Q significantly reduced adipocyte size and enhanced angiogenesis and adipogenesis without changes in eWAT weight and attenuated systemic IR and inflammation. In addition, high-fat diet consumption increased eWAT hypoxia inducible factor-1 alpha (HIF-1α) levels and those of proteins involved in adipose inflammation (TLR-4, CD68, MCP-1, JNK) and activation of endoplasmic reticulum (ER) stress, i.e. ATF-6 and XBP-1. Q mitigated all these events. Q and quercetin 3-glucoronide prevented TNFα-mediated downregulation of adipogenesis during 3T3-L1 pre-adipocytes early differentiation. Together, Q capacity to promote a healthy adipose expansion enhancing angiogenesis and adipogenesis may contribute to reduced adipose hypertrophy, inflammation and IR. Consumption of diets rich in Q could be useful to counteract the adverse effects of high-fat diet-induced adipose dysfunction.

Topics: 3T3-L1 Cells; Adipocytes; Adipogenesis; Adipose Tissue, Brown; Adipose Tissue, White; Animals; Antioxidants; Body Weight; Diet, High-Fat; Hypertrophy; Hypoxia-Inducible Factor 1, alpha Subunit; Inflammation; Insulin Resistance; Male; Mice; Obesity; Quercetin; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

Quercetin represents antioxidative/antiinflammatory flavonoids widely distributed in the human diet. Quercetin is efficiently metabolized during absorption to quercetin-3-O-glucuronide. This study aims to parallelly investigate whether quercetin and quercetin-3-O-glucuronide exert protection against palmitate (PA)-induced inflammation and insulin resistance in the endothelium.. Human umbilical vein endothelial cells were pretreated with quercetin and quercetin-3-O-glucuronide for 30 min, and then incubated with 100 μM PA for 30 min or 12 h with or without insulin. PA stimulation led to reactive oxygen species (ROS) production with collapse of mitochondrial membrane potential (Δψm). Quercetin and quercetin-3-O-glucuronide inhibited ROS overproduction and effectively restored Δψm, demonstrating their chemorpotection of mitochondrial function through antioxidative actions. Also, quercetin and quercetin-3-O-glucuronide inhibited ROS-associated inflammation by inhibition of interleukin-6 and tumor necrosis factor-α production with suppression of IKKβ/NF-κB phosphorylation. Inflammation impaired insulin PI3K signaling and reduced insulin-mediated nitric oxide (NO) production. Quercetin and quercetin-3-O-glucuronide facilitated PI3K signaling by positive regulation of serine/tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and restoration of downstream Akt/eNOS activation, leading to an increased insulin-mediated NO level.. The above-mentioned evidence indicates that quercetin and quercetin-3-O-glucuronide are equally effective in inhibiting ROS-associated inflammation and ameliorating insulin resistant endothelial dysfunction by beneficial regulation of IRS-1 function.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Endothelium, Vascular; Human Umbilical Vein Endothelial Cells; Humans; I-kappa B Kinase; Inflammation; Insulin Receptor Substrate Proteins; Insulin Resistance; Interleukin-6; NF-kappa B; Nitric Oxide Synthase Type III; Oxidative Stress; Palmitates; Phosphorylation; Proto-Oncogene Proteins c-akt; Quercetin; Reactive Oxygen Species; Tumor Necrosis Factor-alpha

Dietary flavonoids, such as quercetin, have long been recognized to protect blood vessels from atherogenic inflammation by yet unknown mechanisms. We have previously discovered the specific localization of quercetin-3-O-glucuronide (Q3GA), a phase II metabolite of quercetin, in macrophage cells in the human atherosclerotic lesions, but the biological significance is poorly understood. We have now demonstrated the molecular basis of the interaction between quercetin glucuronides and macrophages, leading to deconjugation of the glucuronides into the active aglycone. In vitro experiments showed that Q3GA was bound to the cell surface proteins of macrophages through anion binding and was readily deconjugated into the aglycone. It is of interest that the macrophage-mediated deconjugation of Q3GA was significantly enhanced upon inflammatory activation by lipopolysaccharide (LPS). Zymography and immunoblotting analysis revealed that β-glucuronidase is the major enzyme responsible for the deglucuronidation, whereas the secretion rate was not affected after LPS treatment. We found that extracellular acidification, which is required for the activity of β-glucuronidase, was significantly induced upon LPS treatment and was due to the increased lactate secretion associated with mitochondrial dysfunction. In addition, the β-glucuronidase secretion, which is triggered by intracellular calcium ions, was also induced by mitochondria dysfunction characterized using antimycin-A (a mitochondrial inhibitor) and siRNA-knockdown of Atg7 (an essential gene for autophagy). The deconjugated aglycone, quercetin, acts as an anti-inflammatory agent in the stimulated macrophages by inhibiting the c-Jun N-terminal kinase activation, whereas Q3GA acts only in the presence of extracellular β-glucuronidase activity. Finally, we demonstrated the deconjugation of quercetin glucuronides including the sulfoglucuronides in vivo in the spleen of mice challenged with LPS. These results showed that mitochondrial dysfunction plays a crucial role in the deconjugation of quercetin glucuronides in macrophages. Collectively, this study contributes to clarifying the mechanism responsible for the anti-inflammatory activity of dietary flavonoids within the inflammation sites.

Topics: Animals; Anti-Inflammatory Agents; Biological Transport; Calcium; Cell Line; Glucuronidase; Humans; Inflammation; Macrophages; Mice; Mitochondria; Quercetin

Due to their recently discovered plasticity, macrophages could be an important target in the treatment and prevention of atherosclerosis, and it is of interest that quercetin has been shown to modulate inflammation in humans through mechanisms involving macrophages. The aim of this work was to investigate the effect of quercetin-3-O-glucuronide (Q3GA), a major circulating human metabolite of quercetin, on gene expression in differently polarized human macrophages. Classical (M1) and alternative (M2a) macrophages were exposed to Q3GA (500 nM). Gene expression was monitored after incubation periods of 6, 12 and 24 h. M1 and M2a macrophages maintained their respective traits. Q3GA did not affect M1 macrophages in the promotion of a defense response, which remains the principal characteristic of this type of activation, but it was able to reduce the transcription of genes involved in inflammation, such as pro-inflammatory interleukins and enzymes involved in oxidative stress responses. Exposure of M2a to Q3GA elicited an improvement in anti-inflammatory features resulting from further down-regulation of pro-inflammatory genes. Thus, Q3GA is a potential anti-atherogenic metabolite, enhancing the anti-inflammatory properties of M2a macrophages and modulating immune response effects in the presence of pro-inflammatory stimuli.

Topics: Anti-Inflammatory Agents; Down-Regulation; Humans; Immunity; Inflammation; Interleukins; Macrophage Activation; Macrophages; Microarray Analysis; Oxidative Stress; Quercetin; Transcriptome

In the present study the effect of quercetin and its major metabolites quercetin-3-glucuronide (Q3G) and isorhamnetin on inflammatory gene expression was determined in murine RAW264.7 macrophages stimulated with lipopolysaccharide. Quercetin and isorhamnetin but not Q3G significantly decreased mRNA and protein levels of tumor necrosis factor alpha. Furthermore a significant decrease in mRNA levels of interleukin 1β, interleukin 6, macrophage inflammatory protein 1α and inducible nitric oxide synthase was evident in response to the quercetin treatment. However Q3G did not affect inflammatory gene expression. Anti-inflammatory properties of quercetin and isorhamnetin were accompanied by an increase in heme oxygenase 1 protein levels, a downstream target of the transcription factor Nrf2, known to antagonize chronic inflammation. Furthermore, proinflammatory microRNA-155 was down-regulated by quercetin and isorhamnetin but not by Q3G. Finally, anti-inflammatory properties of quercetin were confirmed in vivo in mice fed quercetin-enriched diets (0.1 mg quercetin/g diet) over 6 weeks.

Topics: Animals; Anti-Inflammatory Agents; Cell Line; Cell Survival; Down-Regulation; Female; Flavonols; Gene Expression; Heme Oxygenase-1; Inflammation; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Macrophages; Mice; Mice, Inbred C57BL; MicroRNAs; Nitric Oxide Synthase Type II; Quercetin; Tumor Necrosis Factor-alpha

Quercetin is anti-inflammatory in macrophages by inhibiting lipopolysaccharide (LPS)-mediated increases in cytokine and nitric oxide production but there is little information regarding the corresponding effect on the vasculature. We have examined the effect of quercetin, and its principal human metabolites, on inflammatory changes in the porcine isolated coronary artery.. Porcine coronary artery segments were incubated overnight at 37°C in modified Krebs-Henseleit solution with or without 1µg·mL(-1) LPS. Some segments were also co-incubated with quercetin-related flavonoids or Bay 11-7082, an inhibitor of NFκB. Changes in isometric tension of segments to vasoconstrictor and vasodilator agents were recorded. Nitrite content of the incubation solution was estimated using the Griess reaction, while inducible nitric oxide synthase was identified immunohistochemically.. Lipopolysaccharide reduced, by 35-50%, maximal contractions to KCl and U46619, thromboxane A(2) receptor agonist, and impaired endothelium-dependent relaxations to substance P. Nitrite content of the incubation medium increased 3- to 10-fold following exposure to LPS and inducible nitric oxide synthase was detected in the adventitia. Quercetin (0.1-10µM) opposed LPS-induced changes in vascular responses, nitrite production and expression of inducible nitric oxide synthase. Similarly, 10µM Bay 11-7082, 10µM quercetin 3'-sulphate and 10µM quercetin 3-glucuronide prevented LPS-induced changes, while myricetin (10µM) was inactive. Myricetin (10µM) prevented quercetin-induced modulation of LPS-mediated nitrite production.. Quercetin, quercetin 3'-suphate and quercetin 3-glucuronide, exerted anti-inflammatory effects on the vasculature, possibly through a mechanism involving inhibition of NFκB. Myricetin-induced antagonism of the effect of anti-inflammatory action of quercetin merits further investigation.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Coronary Vessels; Cytokines; Flavonoids; In Vitro Techniques; Inflammation; Isometric Contraction; Lipopolysaccharides; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase Type II; Nitriles; Nitrites; Potassium Chloride; Quercetin; Sulfones; Swine