scholarly journals Impaired hepatic insulin signalling in PON2-deficient mice: a novel role for the PON2/apoE axis on the macrophage inflammatory response

2011 ◽  
Vol 436 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Noam Bourquard ◽  
Carey J. Ng ◽  
Srinivasa T. Reddy
Keyword(s):  
Oxidative Stress ◽  
Inflammatory Response ◽  
Insulin Signalling ◽  
Antioxidant Properties ◽  
Hepatic Glucose Metabolism ◽  
Hepatic Glucose ◽  
Activated Macrophage ◽  
Inflammatory Stimuli ◽  
Deficient Mice

Hepatic glucose metabolism is strongly influenced by oxidative stress and pro-inflammatory stimuli. PON2 (paraoxonase 2), an enzyme with undefined antioxidant properties, protects against atherosclerosis. PON2-deficient (PON2-def) mice have elevated hepatic oxidative stress coupled with an exacerbated inflammatory response from PON2-deficient macrophages. In the present paper, we demonstrate that PON2 deficiency is associated with inhibitory insulin-mediated phosphorylation of hepatic IRS-1 (insulin receptor substrate-1). Unexpectedly, we observed a marked improvement in the hepatic IRS-1 phosphorylation state in PON2-def/apoE (apolipoprotein E)−/− mice, relative to apoE−/− mice. Factors secreted from activated macrophage cultures derived from PON2-def and PON2-def/apoE−/− mice are sufficient to modulate insulin signalling in cultured hepatocytes in a manner similar to that observed in vivo. We show that the protective effect on insulin signalling in PON2-def/apoE−/− mice is directly associated with altered production of macrophage pro-inflammatory mediators, but not elevated intracellular oxidative stress levels. We further present evidence that modulation of the macrophage inflammatory response in PON2-def/apoE−/− mice is mediated by a shift in the balance of NO and ONOO− (peroxynitrite) formation. Our results demonstrate that PON2 plays an important role in hepatic insulin signalling and underscores the influence of macrophage-mediated inflammatory response on hepatic insulin sensitivity.

scholarly journals CXCR2 deficient mice display macrophage-dependent exaggerated acute inflammatory responses

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Douglas P. Dyer ◽  
Kenneth Pallas ◽  
Laura Medina-Ruiz ◽  
Fabian Schuette ◽  
Gillian J. Wilson ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Inflammatory Responses ◽  
Suppressor Cells ◽  
Myeloid Derived Suppressor Cells ◽  
Inflammatory Stimuli ◽  
Neutrophil Depletion ◽  
Deficient Mice ◽  
Important Therapeutic Target ◽  
Macrophage Accumulation

Abstract CXCR2 is an essential regulator of neutrophil recruitment to inflamed and damaged sites and plays prominent roles in inflammatory pathologies and cancer. It has therefore been highlighted as an important therapeutic target. However the success of the therapeutic targeting of CXCR2 is threatened by our relative lack of knowledge of its precise in vivo mode of action. Here we demonstrate that CXCR2-deficient mice display a counterintuitive transient exaggerated inflammatory response to cutaneous and peritoneal inflammatory stimuli. In both situations, this is associated with reduced expression of cytokines associated with the resolution of the inflammatory response and an increase in macrophage accumulation at inflamed sites. Analysis using neutrophil depletion strategies indicates that this is a consequence of impaired recruitment of a non-neutrophilic CXCR2 positive leukocyte population. We suggest that these cells may be myeloid derived suppressor cells. Our data therefore reveal novel and previously unanticipated roles for CXCR2 in the orchestration of the inflammatory response.

scholarly journals Protection of the vascular endothelium in experimental situations

2011 ◽  
Vol 4 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Ružena Sotníková ◽  
Jana Nedelčevová ◽  
Jana Navarová ◽  
Viera Nosáľová ◽  
Katarína Drábiková ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Vascular Endothelium ◽  
Vascular Dysfunction ◽  
Antioxidant Properties ◽  
Pharmacological Intervention ◽  
Ros Production ◽  
Nitric Oxide Radical ◽  
Endothelium Dependent Relaxation

Protection of the vascular endothelium in experimental situationsOne of the factors proposed as mediators of vascular dysfunction observed in diabetes is the increased generation of reactive oxygen species (ROS). This provides support for the use of antioxidants as early and appropriate pharmacological intervention in the development of late diabetic complications. In streptozotocin (STZ)-induced diabetes in rats we observed endothelial dysfuction manifested by reduced endothelium-dependent response to acetylcholine of the superior mesenteric artery (SMA) and aorta, as well as by increased endothelaemia. Changes in endothelium-dependent relaxation of SMA were induced by injury of the nitric oxide radical (·NO)-signalling pathway since the endothelium-derived hyperpolarising factor (EDHF)-component of relaxation was not impaired by diabetes. The endothelial dysfunction was accompanied by decreased ·NO bioavailabity as a consequence of reduced activity of eNOS rather than its reduced expression. The results obtained using the chemiluminiscence method (CL) argue for increased oxidative stress and increased ROS production. The enzyme NAD(P)H-oxidase problably participates in ROS production in the later phases of diabetes. Oxidative stress was also connected with decreased levels of reduced glutathione (GSH) in the early phase of diabetes. After 10 weeks of diabetes, adaptational mechanisms probably took place because GSH levels were not changed compared to controls. Antioxidant properties of SMe1EC2 foundin vitrowere partly confirmedin vivo.Administration of SMe1EC2 protected endothelial function. It significantly decreased endothelaemia of diabetic rats and improved endothelium-dependent relaxation of arteries, slightly decreased ROS-production and increased bioavailability of ·NO in the aorta. Further studies with higher doses of SMe1EC2 may clarify the mechanism of its endothelium-protective effectin vivo.

scholarly journals Disruption of γ-Glutamyl Leukotrienase Results in Disruption of Leukotriene D4 Synthesis In Vivo and Attenuation of the Acute Inflammatory Response

2001 ◽  
Vol 21 (16) ◽  
pp. 5389-5395 ◽  
Author(s):  
Zheng-Zheng Shi ◽  
Bing Han ◽  
Geetha M. Habib ◽  
Martin M. Matzuk ◽  
Michael W. Lieberman
Keyword(s):  
Inflammatory Response ◽  
Double Mutant ◽  
Inflammatory Process ◽  
Embryonic Stem ◽  
Acute Inflammatory Response ◽  
Leukotriene D4 ◽  
Glutamyl Transpeptidase ◽  
Targeting Strategy ◽  
Deficient Mice

ABSTRACT To study the function of γ-glutamyl leukotrienase (GGL), a newly identified member of the γ-glutamyl transpeptidase (GGT) family, we generated null mutations in GGL (GGLtm1) and in both GGL and GGT (GGLtm1-GGTtm1) by a serial targeting strategy using embryonic stem cells. Mice homozygous for GGLtm1 show no obvious phenotypic changes. Mice deficient in both GGT and GGL have a phenotype similar to the GGT-deficient mice, but ∼70% of these mice die before 4 weeks of age, at least 2 months earlier than mice deficient only in GGT. These double-mutant mice are unable to cleave leukotriene C4 (LTC4) to LTD4, indicating that this conversion is completely dependent on the two enzymes, and in some organs (spleen and uterus) deletion of GGL alone abolished more than 90% of this activity. In an experimental model of peritonitis, GGL alone is responsible for the generation of peritoneal LTD4. Further, during the development of peritonitis, GGL-deficient mice show an attenuation in neutrophil recruitment but not of plasma protein influx. These findings demonstrate an important role for GGL in the inflammatory response and suggest that LTC4 and LTD4 have distinctly different functions in the inflammatory process.

Epicatechin and its in vivo metabolite, 3′-O-methyl epicatechin, protect human fibroblasts from oxidative-stress-induced cell death involving caspase-3 activation

2001 ◽  
Vol 354 (3) ◽  
pp. 493-500 ◽  
Author(s):  
Jeremy P. E. SPENCER ◽  
Hagen SCHROETER ◽  
Gunter KUHNLE ◽  
S. Kaila S. SRAI ◽  
Rex M. TYRRELL ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Cell Death ◽  
Caspase 3 ◽  
Cell Damage ◽  
Protective Action ◽  
Human Fibroblasts ◽  
Membrane Damage ◽  
Antioxidant Properties

There is considerable current interest in the cytoprotective effects of natural antioxidants against oxidative stress. In particular, epicatechin, a major member of the flavanol family of polyphenols with powerful antioxidant properties in vitro, has been investigated to determine its ability to attenuate oxidative-stress-induced cell damage and to understand the mechanism of its protective action. We have induced oxidative stress in cultured human fibroblasts using hydrogen peroxide and examined the cellular responses in the form of mitochondrial function, cell-membrane damage, annexin-V binding and caspase-3 activation. Since one of the major metabolites of epicatechin in vivo is 3′-O-methyl epicatechin, we have compared its protective effects with that of epicatechin. The results provide the first evidence that 3′-O-methyl epicatechin inhibits cell death induced by hydrogen peroxide and that the mechanism involves suppression of caspase-3 activity as a marker for apoptosis. Furthermore, the protection elicited by 3′-O-methyl epicatechin is not significantly different from that of epicatechin, suggesting that hydrogen-donating antioxidant activity is not the primary mechanism of protection.

scholarly journals Antioxidant supplementation slows telomere shortening in free-living white stork chicks

2020 ◽  
Vol 287 (1918) ◽  
pp. 20191917 ◽  
Author(s):  
Javier Pineda-Pampliega ◽  
Amparo Herrera-Dueñas ◽  
Ellis Mulder ◽  
José I. Aguirre ◽  
Ursula Höfle ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Properties ◽  
White Stork ◽  
Control Treatment ◽  
Antioxidant Treatment ◽  
Telomere Attrition ◽  
Final Sample ◽  
Shortening Rate

Telomere length (TL) and shortening is increasingly shown to predict variation in survival and lifespan, raising the question of what causes variation in these traits. Oxidative stress is well known to accelerate telomere attrition in vitro , but its importance in vivo is largely hypothetical. We tested this hypothesis experimentally by supplementing white stork ( Ciconia ciconia ) chicks with antioxidants. Individuals received either a control treatment, or a supply of tocopherol (vitamin E) and selenium, which both have antioxidant properties. The antioxidant treatment increased the concentration of tocopherol for up to two weeks after treatment but did not affect growth. Using the telomere restriction fragment technique, we evaluated erythrocyte TL and its dynamics. Telomeres shortened significantly over the 21 days between the baseline and final sample, independent of sex, mass, size and hatching order. The antioxidant treatment significantly mitigated shortening rate of average TL (−31% in shorter telomeres; percentiles 10th, 20th and 30th). Thus, our results support the hypothesis that oxidative stress shortens telomeres in vivo .

scholarly journals Aloin Preconditioning Attenuates Hepatic Ischemia/Reperfusion Injury via Inhibiting TLR4/MyD88/NF-κB Signal Pathway In Vivo and In Vitro

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Yichao Du ◽  
Baolin Qian ◽  
Lin Gao ◽  
Peng Tan ◽  
Hao Chen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Inflammatory Response ◽  
Liver Tissue ◽  
Molecular Mechanisms ◽  
Ischemia Reperfusion ◽  
Primary Hepatocytes ◽  
Hepatic Ischemia ◽  
Hepatic Ischemia Reperfusion

Background. Aloin exerts considerable protective effects in various disease models, and its effect on hepatic ischemia-reperfusion (HIR) injury remains unknown. This research is aimed at conducting an in-depth investigation of the antioxidant, anti-inflammatory, and antiapoptosis effects of aloin in HIR injury and explain the underlying molecular mechanisms. Methods. In vivo, different concentrations of aloin were intraperitoneally injected 1 h before the establishment of the HIR model in male mice. The hepatic function, pathological status, oxidative stress, and inflammatory and apoptosis markers were measured. In vitro, aloin (AL, C21H22O9) or lipopolysaccharide (LPS) was added to a culture of mouse primary hepatocytes before it underwent hypoxia/reoxygenation (H/R), and the apoptosis in the mouse primary hepatocytes was analyzed. Results. We found that 20 mg/kg was the optimum concentration of aloin for mitigating I/R-induced liver tissue damage, characterized by decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Aloin pretreatment substantially suppressed the generation of hepatic malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α), and IL-6 and enhanced the hepatic superoxide dismutase (SOD) activities as well as glutathione (GSH) and IL-10 levels in the liver tissue of I/R mice; this indicated that aloin ameliorated I/R-induced liver damage by reducing the oxidative stress and inflammatory response. Moreover, aloin inhibited hepatocyte apoptosis and inflammatory response that was caused by the upregulated expression of Bcl-2, the downregulated expression of cleaved caspase3(C-caspase3), Bax, Toll-like receptor 4 (TLR4), FADD, MyD88, TRAF6, phosphorylated IKKα/β (p-IKKα/β), and phosphorylated nuclear factor κB p65 (p-NF-κB p65).

scholarly journals Melatonin Modulation of Sirtuin-1 Attenuates Liver Injury in a Hypercholesterolemic Mouse Model

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Francesca Bonomini ◽  
Gaia Favero ◽  
Luigi Fabrizio Rodella ◽  
Mohammed H. Moghadasian ◽  
Rita Rezzani
Keyword(s):  
Oxidative Stress ◽  
Biochemical Markers ◽  
Antioxidant Properties ◽  
Sirtuin 1 ◽  
Oral Supplementation ◽  
Stress Markers ◽  
Serum Biochemical ◽  
Stress Signals

Hypercholesterolemia increases and exacerbates stress signals leading also to liver damage (LD) and failure. Sirtuin1 (SIRT1) is involved in lifespan extension and it plays an essential role in hepatic lipid metabolism. However, its involvement in liver hypercholesterolemic damage is not yet completely defined. This in vivo study evaluated the role of SIRT1 in the hypercholesterolemic-related LD and, then, investigated how oral supplementation of melatonin, pleiotropic indoleamine, may be protective. Control mice and apolipoprotein E-deficient mice (ApoE−/−) of 6 and 15 weeks of age were treated or not treated with melatonin at the dose of 10 mg/kg/day for 9 weeks. In this study, we evaluated serum biochemical markers, liver SIRT1 expression, and oxidative stress markers. We observed that hypercholesterolemia increased significantly serum cholesterol and triglycerides, reduced significantly liver SIRT1, and, in turn, induced hepatic oxidative stress in untreated ApoE−/− mice with respect to control mice. Interestingly, melatonin treatment improved serum biochemical markers and hepatic morphological impairment and inhibited oxidative stress through its antioxidant properties and also by SIRT1 upregulation. In summary, melatonin oral supplementation may represent a new protective approach to block hypercholesterolemic liver alterations involving also a SIRT1-dependent mechanism.

scholarly journals PML is a ROS sensor activating p53 upon oxidative stress

2017 ◽  
Vol 214 (11) ◽  
pp. 3197-3206 ◽  
Author(s):  
Michiko Niwa-Kawakita ◽  
Omar Ferhi ◽  
Hassane Soilihi ◽  
Morgane Le Bras ◽  
Valérie Lallemand-Breitenbach ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Biology ◽  
Antioxidant Properties ◽  
Promyelocytic Leukemia ◽  
Nuclear Bodies ◽  
Glutathione Depletion ◽  
Pml Nuclear Bodies ◽  
P53 Activation ◽  
Induced Changes

Promyelocytic leukemia (PML) nuclear bodies (NBs) recruit partner proteins, including p53 and its regulators, thereby controlling their abundance or function. Investigating arsenic sensitivity of acute promyelocytic leukemia, we proposed that PML oxidation promotes NB biogenesis. However, physiological links between PML and oxidative stress response in vivo remain unexplored. Here, we identify PML as a reactive oxygen species (ROS) sensor. Pml−/− cells accumulate ROS, whereas PML expression decreases ROS levels. Unexpectedly, Pml−/− embryos survive acute glutathione depletion. Moreover, Pml−/− animals are resistant to acetaminophen hepatotoxicity or fasting-induced steatosis. Molecularly, Pml−/− animals fail to properly activate oxidative stress–responsive p53 targets, whereas the NRF2 response is amplified and accelerated. Finally, in an oxidative stress–prone background, Pml−/− animals display a longevity phenotype, likely reflecting decreased basal p53 activation. Thus, similar to p53, PML exerts basal antioxidant properties but also drives oxidative stress–induced changes in cell survival/proliferation or metabolism in vivo. Through NB biogenesis, PML therefore couples ROS sensing to p53 responses, shedding a new light on the role of PML in senescence or stem cell biology.

scholarly journals Mulberry Anthocyanin Extract Ameliorates Oxidative Damage in HepG2 Cells and Prolongs the Lifespan of Caenorhabditis elegans through MAPK and Nrf2 Pathways

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Fujie Yan ◽  
Yushu Chen ◽  
Ramila Azat ◽  
Xiaodong Zheng
Keyword(s):  
Oxidative Stress ◽  
Caenorhabditis Elegans ◽  
Hepg2 Cells ◽  
Insulin Signalling ◽  
Glucose Consumption ◽  
Redox Status ◽  
C Elegans ◽  
Beneficial Effects

Mulberry anthocyanins possess many pharmacological effects including liver protection, anti-inflammation, and anticancer. The aim of this study was to evaluate whether mulberry anthocyanin extract (MAE) exerts beneficial effects against oxidative stress damage in HepG2 cells and Caenorhabditis elegans. In vitro, MAE prevented cytotoxicity, increased glucose consumption and uptake, and eliminated excessive intracellular free radicals in H2O2-induced cells. Moreover, MAE pretreatment maintained Nrf2, HO-1, and p38 MAPK stimulation and abolished upregulation of p-JNK, FOXO1, and PGC-1α that were involved in oxidative stress and insulin signalling modulation. In vivo, extended lifespan was observed in C. elegans damaged by paraquat in the presence of MAE, while these beneficial effects were disappeared in pmk-1 and daf-16 mutants. PMK-1 and SKN-1 were activated after exposure to paraquat and MAE suppressed PMK-1 activation but enhanced SKN-1 stimulation. Our findings suggested that MAE recovered redox status in HepG2 cells and C. elegans that suffered from oxidative stress, which might be by targeting MAPKs and Nrf2.

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