Sara Borniquel - Academia.edu (original) (raw)

Papers by Sara Borniquel

We studied the cytotoxic effect of the heavy metals Cd, Zn and Cu on three different species of c... more We studied the cytotoxic effect of the heavy metals Cd, Zn and Cu on three different species of ciliated protozoa isolated from an urban wastewater treatment plant. The order of toxicity was Cd > Cu Zn or Cu > Cd Zn, depending on the microbial species. In bimetallic (Cd + Zn) treatments, results indicated that, in general, the presence of Zn in the same medium decreased Cd cytotoxicity. Both cellular assays and microscopic observations showed that bioaccumulation is an important mechanism of resistance to these toxic environmental pollutants in such eukaryotic microorganisms. However, bioaccumulation might not be the main mechanism involved in Cu resistance. For the first time, fluorescence methodology was applied for revealing metal deposits in the cellular cytoplasm. This microscopic method is only useful when cell cultures can be exposed to rather high metal concentrations, as in the case of Zn. Inside the ciliated protozoa exposed to sublethal concentrations of Cd or Zn, it is possible to observe diverse electron-dense granules by TEM which are not seen in controls. Problems in comparing our results on heavy metal cytotoxic effects on ciliates with already published data are exposed and discussed. The use of these eukaryotic microorganisms as potential whole cells or molecular (ciliate metallothioneins) biosensors seems to be a reasonable useful alternative for assessing metallic pollution.  2005 Elsevier SAS. All rights reserved.

Journal of Biological Chemistry, 2009

Oxidative stress is a hallmark of metabolism-related diseases and a risk factor for atheroscleros... more Oxidative stress is a hallmark of metabolism-related diseases and a risk factor for atherosclerosis. FoxO factors have been shown to play a key role in vascular endothelial development and homeostasis. Foxo3a can protect quiescent cells from oxidative stress through the regulation of detoxification genes such as sod2 and catalase. Here we show that Foxo3a is a direct transcriptional regulator of a group of oxidative stress protection genes in vascular endothelial cells. Importantly, Foxo3a activity requires the transcriptional co-activator PGC-1␣, because it is severely curtailed in PGC-1␣-deficient endothelial cells. Foxo3a and PGC-1␣ appear to interact directly, as shown by co-immunoprecipitation and in vitro interaction assays, and are recruited to the same promoter regions. The notion that Foxo3a and PGC-1␣ interact directly to regulate oxidative stress protection genes in the vascular endothelium is supported by the observation that PGC-1␣ transcriptional activity at the sod2 (manganese superoxide dismutase) promoter requires a functional FoxO site. We also demonstrate that Foxo3a is a direct transcriptional regulator of PGC-1␣, suggesting that an auto-regulatory cycle regulates Foxo3a/PGC-1␣ control of the oxidative stress response.

Nitric Oxide-biology and Chemistry, 2006

Frontiers in bioscience : a journal and virtual library, 2007

The integrity of mitochondrial function is fundamental to cell life. The cell demands for mitocho... more The integrity of mitochondrial function is fundamental to cell life. The cell demands for mitochondria and their complex integration into cell biology, extends far beyond the provision of ATP. It follows that disturbances of mitochondrial function lead to disruption of cell function, expressed as disease or even death. Mitochondria are major producers of free radical species and also possibly of nitric oxide, and are, at the same time, major targets for oxidative damage. In this review we consider recent developments in our knowledge of how the mitochondrial production of reactive oxygen species (ROS) plays a critical role in several major human pathologies. We will also consider recent advances in our understanding of the molecular mechanisms involved in mitochondrial ROS detoxification.

Molecular and cellular biology, 2010

In damaged or proliferating endothelium, production of nitric oxide (NO) from endothelial nitric ... more In damaged or proliferating endothelium, production of nitric oxide (NO) from endothelial nitric oxide synthase (eNOS) is associated with elevated levels of reactive oxygen species (ROS), which are necessary for endothelial migration. We aimed to elucidate the mechanism that mediates NO induction of endothelial migration. NO downregulates expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 alpha), which positively modulates several genes involved in ROS detoxification. We tested whether NO-induced cell migration requires PGC-1 alpha downregulation and investigated the regulatory pathway involved. PGC-1 alpha negatively regulated NO-dependent endothelial cell migration in vitro, and inactivation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway, which is activated by NO, reduced NO-mediated downregulation of PGC-1 alpha. Expression of constitutively active Foxo3a, a target for Akt-mediated inactivation, reduced NO-depende...

The FASEB Journal, 2006

Nitric oxide (NO) has both prooxidant and antioxidant activities in the endothelium; however, the... more Nitric oxide (NO) has both prooxidant and antioxidant activities in the endothelium; however, the molecular mechanisms involved are still a matter of controversy. PGC-1␣ [peroxisome proliferators-activated receptor (PPAR) ␥ coactivator 1-␣] induces the expression of several members of the mitochondrial reactive oxygen species (ROS) detoxification system.

Proceedings of the National Academy of Sciences, 2010

The metabolic syndrome is a clustering of risk factors of metabolic origin that increase the risk... more The metabolic syndrome is a clustering of risk factors of metabolic origin that increase the risk for cardiovascular disease and type 2 diabetes. A proposed central event in metabolic syndrome is a decrease in the amount of bioavailable nitric oxide (NO) from endothelial NO synthase (eNOS). Recently, an alternative pathway for NO formation in mammals was described where inorganic nitrate, a supposedly inert NO oxidation product and unwanted dietary constituent, is serially reduced to nitrite and then NO and other bioactive nitrogen oxides. Here we show that several features of metabolic syndrome that develop in eNOS-deficient mice can be reversed by dietary supplementation with sodium nitrate, in amounts similar to those derived from eNOS under normal conditions. In humans, this dose corresponds to a rich intake of vegetables, the dominant dietary nitrate source. Nitrate administration increased tissue and plasma levels of bioactive nitrogen oxides. Moreover, chronic nitrate treatment reduced visceral fat accumulation and circulating levels of triglycerides and reversed the prediabetic phenotype in these animals. In rats, chronic nitrate treatment reduced blood pressure and this effect was also present during NOS inhibition. Our results show that dietary nitrate fuels a nitratenitrite-NO pathway that can partly compensate for disturbances in endogenous NO generation from eNOS. These findings may have implications for novel nutrition-based preventive and therapeutic strategies against cardiovascular disease and type 2 diabetes. glucose | insulin | s-nitrosothiol | obesity | bacteria

European Journal of Protistology, 2000

Cyrtolophosis elongata is a small soil ciliate of the order Cyrtolophosidida, class Colpodea. Usi... more Cyrtolophosis elongata is a small soil ciliate of the order Cyrtolophosidida, class Colpodea. Using the silver carbonate method we have been able to study the ciliary pattern of vegetative and dividing cells. Transmission electron microscopy revealed that there is no micro-macronuclear complex in this species. This type of nuclear apparatus thus cannot be considered as most important apomorphy of the Cyrtolophosidida. Division is in the swimming condition, stomatogenesis is pleurotelokinetal. Feulgen stain indicates the absence of a macronuclear chromatin extrusion process during both division and encystment. Cortical and cytoplasmic phenomena during encystment are similar to those of Colpoda spp. These data and ultrastructural observations of mature resting cysts indicate that Cyrtolophosis elongata has resting cysts of PKR (Partial-kinetosome-resorbing) type, with a cyst wall composed by two layers.

Redox Biology, 2014

Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel ... more Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel disease, Redox Biology, http://dx.Abstract Background: Inorganic nitrate and nitrite have emerged as alternative substrates for nitric oxide (NO) generation in the gastrointestinal tract, and have shown to be protective against drug-induced gastric injury. The aim of this study was to investigate the preventive and therapeutic effects of nitrate and nitrite in a model of experimental colitis. Methods: Colitis was induced in mice by administrating dextran sulfate sodium (DSS) with concurrent administration of nitrite (1mM) or nitrate (10 mM) in the drinking water for 7 days. A therapeutic approach was also investigated by initiating nitrite treatment 3 days after DSS-induced colitis. Clinical and inflammatory markers were assessed and the colonic mucus thickness was measured in vivo. The effect of nitrite on wound healing was evaluated using colon epithelial cells. Results: Concurrent administration of DSS and nitrite (1mM) alleviated inflammation as determined by reduced disease activity index score (DAI) and increased colon length, while nitrate (10mM) only reduced the DAI-score. Nitrite also displayed therapeutic effects by ameliorating established colonic inflammation with reduced colonic expression of iNOS and improving histopathology. DSS-induced decrease in colonic mucus thickness was completely prevented by nitrite administration. In addition, goblet cell abundance was lower by DSS treatment, but was increased by addition of nitrite. Further studies using colon epithelial cells revealed an NO-dependent improvement in wound healing with nitrite administration. Work supported by The Ruth and Richard Juhlin's Foundation, Dr. P Håkanssons/Druvan Stiftelse, Karolinska Institutet Foundation (S.B.), Vinnova (CIDaT) (J.O.L.), Vetenskapsrådet -08646 (LH) and K2012-99x (MP), Ragnar Söderberg foundation (MP), Nanna Svartz foundation (MP).

Free Radical Biology and Medicine, 2010

Free Radical Biology and Medicine, 2013

Hydrogen sulfide (H 2 S), generated through various endogenous enzymatic and nonenzymatic pathway... more Hydrogen sulfide (H 2 S), generated through various endogenous enzymatic and nonenzymatic pathways, is emerging as a regulator of physiological and pathological events throughout the body. Bacteria in the gastrointestinal tract also produce significant amounts of H 2 S that regulates microflora growth and virulence responses. However, the impact of the microbiota on host global H 2 S bioavailability and metabolism remains unknown. To address this question, we examined H 2 S bioavailability in its various forms (free, acid labile, or bound sulfane sulfur), cystathionine γ-lyase (CSE) activity, and cysteine levels in tissues from germ-free versus conventionally housed mice. Free H 2 S levels were significantly reduced in plasma and gastrointestinal tissues of germ-free mice. Bound sulfane sulfur levels were decreased by 50-80% in germ-free mouse plasma and adipose and lung tissues. Tissue CSE activity was significantly reduced in many organs from germ-free mice, whereas tissue cysteine levels were significantly elevated compared to conventional mice. These data reveal that the microbiota profoundly regulates systemic bioavailability and metabolism of H 2 S.

Free Radical Biology and Medicine, 2010

Nitric oxide and its metabolites undergo nitration reactions with unsaturated fatty acids during ... more Nitric oxide and its metabolites undergo nitration reactions with unsaturated fatty acids during oxidative inflammatory conditions, forming electrophilic nitro-fatty acid derivatives. These endogenous electrophilic mediators activate anti-inflammatory signaling reactions, serving as high-affinity ligands for peroxisome proliferator-activated receptor γ (PPARγ). Here we examined the therapeutic effects of 9-or 10-nitro-octadecenoic oleic acid (OA-NO 2 ) and native oleic acid (OA) in a mouse model of colitis. OA-NO 2 reduced the disease activity index and completely prevented dextran sulfate sodium-induced colon shortening and the increase in colonic p65 expression. Increased PPARγ expression was observed in colon samples as well as in cells after OA-NO 2 administration, whereas no effect was seen with OA. This induction of PPARγ expression was completely abolished by the PPARγ antagonist GW9662. 5-Aminosalicylic acid, an anti-inflammatory drug routinely used in the management of inflammatory bowel disease, also increased PPARγ expression but to a lesser extent. Altogether, these findings demonstrate that administration of OA-NO 2 attenuates colonic inflammation and improves clinical symptoms in experimental inflammatory bowel disease. This protection involves activation of colonic PPARγ.

Cell Metabolism, 2011

Nitrate, an inorganic anion abundant in vegetables, is converted in vivo to bioactive nitrogen ox... more Nitrate, an inorganic anion abundant in vegetables, is converted in vivo to bioactive nitrogen oxides including NO. We recently demonstrated that dietary nitrate reduces oxygen cost during physical exercise, but the mechanism remains unknown. In a double-blind crossover trial we studied the effects of a dietary intervention with inorganic nitrate on basal mitochondrial function and whole-body oxygen consumption in healthy volunteers. Skeletal muscle mitochondria harvested after nitrate supplementation displayed an improvement in oxidative phosphorylation efficiency (P/O ratio) and a decrease in state 4 respiration with and without atractyloside and respiration without adenylates. The improved mitochondrial P/O ratio correlated to the reduction in oxygen cost during exercise. Mechanistically, nitrate reduced the expression of ATP/ADP translocase, a protein involved in proton conductance. We conclude that dietary nitrate has profound effects on basal mitochondrial function. These findings may have implications for exercise physiology-and lifestyle-related disorders that involve dysfunctional mitochondria.

Antioxidants & Redox Signaling, 2014

Abstract Aims: Inorganic nitrate and nitrite from endogenous and dietary sources have emerged as ... more Abstract Aims: Inorganic nitrate and nitrite from endogenous and dietary sources have emerged as alternative substrates for nitric oxide (NO) formation in addition to the classic L-arginine NO synthase (NOS)-dependent pathway. Here we investigated a potential crosstalk between these two pathways in regulation of vascular function.

Free Radical Biology and Medicine, 2010

Background: The metabolic syndrome is a clustering of risk factors of metabolic origin which incr... more Background: The metabolic syndrome is a clustering of risk factors of metabolic origin which increase the risk for cardiovascular disease and type-2 diabetes. The underlying mechanism for metabolic syndrome is not clear, however decreased nitric oxide (NO) production from endothelial NO synthase (eNOS) has been proposed. Recently, an alternative pathway for NO formation in mammals was described where inorganic nitrate, a supposedly inert NO oxidation product, is serially reduced to nitrite and then NO and other bioactive nitrogen oxides. Aim: Here we tested the hypothesis that eNOS-deficient mice develop features of the metabolic syndrome, and that dietary inorganic nitrate may have therapeutical effects. Methods and Results: eNOS-deficient mice developed features of the metabolic syndrome, which could be reversed by dietary inorganic nitrate supplementation (8-10 weeks). The daily amount of nitrate administered (0.1 mmol kg -1 day -1 ), is similar to that derived from eNOS under normal conditions. In humans this dose corresponds to a diet rich in vegetables, the major source of nitrate. Nitrate supplementation increased tissue and plasma levels of bioactive nitrogen oxides. Moreover, chronic nitrate treatment reduced visceral adipose tissue accumulation, reduced circulating triglyceride levels, and reversed the prediabetic phenotype in eNOS-deficient mice. In rats, chronic nitrate treatment reduced blood pressure and this effect was further pronounced during NOS inhibition. Conclusions: Dietary inorganic nitrate supplementation may fuel the nitrate-nitrite-NO pathway, thus compensate for disturbances in endogenous NO generation from eNOS. These findings suggest a role for inorganic nitrate in novel nutrition based preventive and therapeutic strategies against cardiovascular disease and type-2 diabetes.

We studied the cytotoxic effect of the heavy metals Cd, Zn and Cu on three different species of c... more We studied the cytotoxic effect of the heavy metals Cd, Zn and Cu on three different species of ciliated protozoa isolated from an urban wastewater treatment plant. The order of toxicity was Cd > Cu Zn or Cu > Cd Zn, depending on the microbial species. In bimetallic (Cd + Zn) treatments, results indicated that, in general, the presence of Zn in the same medium decreased Cd cytotoxicity. Both cellular assays and microscopic observations showed that bioaccumulation is an important mechanism of resistance to these toxic environmental pollutants in such eukaryotic microorganisms. However, bioaccumulation might not be the main mechanism involved in Cu resistance. For the first time, fluorescence methodology was applied for revealing metal deposits in the cellular cytoplasm. This microscopic method is only useful when cell cultures can be exposed to rather high metal concentrations, as in the case of Zn. Inside the ciliated protozoa exposed to sublethal concentrations of Cd or Zn, it is possible to observe diverse electron-dense granules by TEM which are not seen in controls. Problems in comparing our results on heavy metal cytotoxic effects on ciliates with already published data are exposed and discussed. The use of these eukaryotic microorganisms as potential whole cells or molecular (ciliate metallothioneins) biosensors seems to be a reasonable useful alternative for assessing metallic pollution.  2005 Elsevier SAS. All rights reserved.

Journal of Biological Chemistry, 2009

Oxidative stress is a hallmark of metabolism-related diseases and a risk factor for atheroscleros... more Oxidative stress is a hallmark of metabolism-related diseases and a risk factor for atherosclerosis. FoxO factors have been shown to play a key role in vascular endothelial development and homeostasis. Foxo3a can protect quiescent cells from oxidative stress through the regulation of detoxification genes such as sod2 and catalase. Here we show that Foxo3a is a direct transcriptional regulator of a group of oxidative stress protection genes in vascular endothelial cells. Importantly, Foxo3a activity requires the transcriptional co-activator PGC-1␣, because it is severely curtailed in PGC-1␣-deficient endothelial cells. Foxo3a and PGC-1␣ appear to interact directly, as shown by co-immunoprecipitation and in vitro interaction assays, and are recruited to the same promoter regions. The notion that Foxo3a and PGC-1␣ interact directly to regulate oxidative stress protection genes in the vascular endothelium is supported by the observation that PGC-1␣ transcriptional activity at the sod2 (manganese superoxide dismutase) promoter requires a functional FoxO site. We also demonstrate that Foxo3a is a direct transcriptional regulator of PGC-1␣, suggesting that an auto-regulatory cycle regulates Foxo3a/PGC-1␣ control of the oxidative stress response.

Nitric Oxide-biology and Chemistry, 2006

Frontiers in bioscience : a journal and virtual library, 2007

The integrity of mitochondrial function is fundamental to cell life. The cell demands for mitocho... more The integrity of mitochondrial function is fundamental to cell life. The cell demands for mitochondria and their complex integration into cell biology, extends far beyond the provision of ATP. It follows that disturbances of mitochondrial function lead to disruption of cell function, expressed as disease or even death. Mitochondria are major producers of free radical species and also possibly of nitric oxide, and are, at the same time, major targets for oxidative damage. In this review we consider recent developments in our knowledge of how the mitochondrial production of reactive oxygen species (ROS) plays a critical role in several major human pathologies. We will also consider recent advances in our understanding of the molecular mechanisms involved in mitochondrial ROS detoxification.

Molecular and cellular biology, 2010

In damaged or proliferating endothelium, production of nitric oxide (NO) from endothelial nitric ... more In damaged or proliferating endothelium, production of nitric oxide (NO) from endothelial nitric oxide synthase (eNOS) is associated with elevated levels of reactive oxygen species (ROS), which are necessary for endothelial migration. We aimed to elucidate the mechanism that mediates NO induction of endothelial migration. NO downregulates expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 alpha), which positively modulates several genes involved in ROS detoxification. We tested whether NO-induced cell migration requires PGC-1 alpha downregulation and investigated the regulatory pathway involved. PGC-1 alpha negatively regulated NO-dependent endothelial cell migration in vitro, and inactivation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway, which is activated by NO, reduced NO-mediated downregulation of PGC-1 alpha. Expression of constitutively active Foxo3a, a target for Akt-mediated inactivation, reduced NO-depende...

The FASEB Journal, 2006

Nitric oxide (NO) has both prooxidant and antioxidant activities in the endothelium; however, the... more Nitric oxide (NO) has both prooxidant and antioxidant activities in the endothelium; however, the molecular mechanisms involved are still a matter of controversy. PGC-1␣ [peroxisome proliferators-activated receptor (PPAR) ␥ coactivator 1-␣] induces the expression of several members of the mitochondrial reactive oxygen species (ROS) detoxification system.

Proceedings of the National Academy of Sciences, 2010

The metabolic syndrome is a clustering of risk factors of metabolic origin that increase the risk... more The metabolic syndrome is a clustering of risk factors of metabolic origin that increase the risk for cardiovascular disease and type 2 diabetes. A proposed central event in metabolic syndrome is a decrease in the amount of bioavailable nitric oxide (NO) from endothelial NO synthase (eNOS). Recently, an alternative pathway for NO formation in mammals was described where inorganic nitrate, a supposedly inert NO oxidation product and unwanted dietary constituent, is serially reduced to nitrite and then NO and other bioactive nitrogen oxides. Here we show that several features of metabolic syndrome that develop in eNOS-deficient mice can be reversed by dietary supplementation with sodium nitrate, in amounts similar to those derived from eNOS under normal conditions. In humans, this dose corresponds to a rich intake of vegetables, the dominant dietary nitrate source. Nitrate administration increased tissue and plasma levels of bioactive nitrogen oxides. Moreover, chronic nitrate treatment reduced visceral fat accumulation and circulating levels of triglycerides and reversed the prediabetic phenotype in these animals. In rats, chronic nitrate treatment reduced blood pressure and this effect was also present during NOS inhibition. Our results show that dietary nitrate fuels a nitratenitrite-NO pathway that can partly compensate for disturbances in endogenous NO generation from eNOS. These findings may have implications for novel nutrition-based preventive and therapeutic strategies against cardiovascular disease and type 2 diabetes. glucose | insulin | s-nitrosothiol | obesity | bacteria

European Journal of Protistology, 2000

Cyrtolophosis elongata is a small soil ciliate of the order Cyrtolophosidida, class Colpodea. Usi... more Cyrtolophosis elongata is a small soil ciliate of the order Cyrtolophosidida, class Colpodea. Using the silver carbonate method we have been able to study the ciliary pattern of vegetative and dividing cells. Transmission electron microscopy revealed that there is no micro-macronuclear complex in this species. This type of nuclear apparatus thus cannot be considered as most important apomorphy of the Cyrtolophosidida. Division is in the swimming condition, stomatogenesis is pleurotelokinetal. Feulgen stain indicates the absence of a macronuclear chromatin extrusion process during both division and encystment. Cortical and cytoplasmic phenomena during encystment are similar to those of Colpoda spp. These data and ultrastructural observations of mature resting cysts indicate that Cyrtolophosis elongata has resting cysts of PKR (Partial-kinetosome-resorbing) type, with a cyst wall composed by two layers.

Redox Biology, 2014

Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel ... more Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel disease, Redox Biology, http://dx.Abstract Background: Inorganic nitrate and nitrite have emerged as alternative substrates for nitric oxide (NO) generation in the gastrointestinal tract, and have shown to be protective against drug-induced gastric injury. The aim of this study was to investigate the preventive and therapeutic effects of nitrate and nitrite in a model of experimental colitis. Methods: Colitis was induced in mice by administrating dextran sulfate sodium (DSS) with concurrent administration of nitrite (1mM) or nitrate (10 mM) in the drinking water for 7 days. A therapeutic approach was also investigated by initiating nitrite treatment 3 days after DSS-induced colitis. Clinical and inflammatory markers were assessed and the colonic mucus thickness was measured in vivo. The effect of nitrite on wound healing was evaluated using colon epithelial cells. Results: Concurrent administration of DSS and nitrite (1mM) alleviated inflammation as determined by reduced disease activity index score (DAI) and increased colon length, while nitrate (10mM) only reduced the DAI-score. Nitrite also displayed therapeutic effects by ameliorating established colonic inflammation with reduced colonic expression of iNOS and improving histopathology. DSS-induced decrease in colonic mucus thickness was completely prevented by nitrite administration. In addition, goblet cell abundance was lower by DSS treatment, but was increased by addition of nitrite. Further studies using colon epithelial cells revealed an NO-dependent improvement in wound healing with nitrite administration. Work supported by The Ruth and Richard Juhlin's Foundation, Dr. P Håkanssons/Druvan Stiftelse, Karolinska Institutet Foundation (S.B.), Vinnova (CIDaT) (J.O.L.), Vetenskapsrådet -08646 (LH) and K2012-99x (MP), Ragnar Söderberg foundation (MP), Nanna Svartz foundation (MP).

Free Radical Biology and Medicine, 2010

Free Radical Biology and Medicine, 2013

Hydrogen sulfide (H 2 S), generated through various endogenous enzymatic and nonenzymatic pathway... more Hydrogen sulfide (H 2 S), generated through various endogenous enzymatic and nonenzymatic pathways, is emerging as a regulator of physiological and pathological events throughout the body. Bacteria in the gastrointestinal tract also produce significant amounts of H 2 S that regulates microflora growth and virulence responses. However, the impact of the microbiota on host global H 2 S bioavailability and metabolism remains unknown. To address this question, we examined H 2 S bioavailability in its various forms (free, acid labile, or bound sulfane sulfur), cystathionine γ-lyase (CSE) activity, and cysteine levels in tissues from germ-free versus conventionally housed mice. Free H 2 S levels were significantly reduced in plasma and gastrointestinal tissues of germ-free mice. Bound sulfane sulfur levels were decreased by 50-80% in germ-free mouse plasma and adipose and lung tissues. Tissue CSE activity was significantly reduced in many organs from germ-free mice, whereas tissue cysteine levels were significantly elevated compared to conventional mice. These data reveal that the microbiota profoundly regulates systemic bioavailability and metabolism of H 2 S.

Free Radical Biology and Medicine, 2010

Nitric oxide and its metabolites undergo nitration reactions with unsaturated fatty acids during ... more Nitric oxide and its metabolites undergo nitration reactions with unsaturated fatty acids during oxidative inflammatory conditions, forming electrophilic nitro-fatty acid derivatives. These endogenous electrophilic mediators activate anti-inflammatory signaling reactions, serving as high-affinity ligands for peroxisome proliferator-activated receptor γ (PPARγ). Here we examined the therapeutic effects of 9-or 10-nitro-octadecenoic oleic acid (OA-NO 2 ) and native oleic acid (OA) in a mouse model of colitis. OA-NO 2 reduced the disease activity index and completely prevented dextran sulfate sodium-induced colon shortening and the increase in colonic p65 expression. Increased PPARγ expression was observed in colon samples as well as in cells after OA-NO 2 administration, whereas no effect was seen with OA. This induction of PPARγ expression was completely abolished by the PPARγ antagonist GW9662. 5-Aminosalicylic acid, an anti-inflammatory drug routinely used in the management of inflammatory bowel disease, also increased PPARγ expression but to a lesser extent. Altogether, these findings demonstrate that administration of OA-NO 2 attenuates colonic inflammation and improves clinical symptoms in experimental inflammatory bowel disease. This protection involves activation of colonic PPARγ.

Cell Metabolism, 2011

Nitrate, an inorganic anion abundant in vegetables, is converted in vivo to bioactive nitrogen ox... more Nitrate, an inorganic anion abundant in vegetables, is converted in vivo to bioactive nitrogen oxides including NO. We recently demonstrated that dietary nitrate reduces oxygen cost during physical exercise, but the mechanism remains unknown. In a double-blind crossover trial we studied the effects of a dietary intervention with inorganic nitrate on basal mitochondrial function and whole-body oxygen consumption in healthy volunteers. Skeletal muscle mitochondria harvested after nitrate supplementation displayed an improvement in oxidative phosphorylation efficiency (P/O ratio) and a decrease in state 4 respiration with and without atractyloside and respiration without adenylates. The improved mitochondrial P/O ratio correlated to the reduction in oxygen cost during exercise. Mechanistically, nitrate reduced the expression of ATP/ADP translocase, a protein involved in proton conductance. We conclude that dietary nitrate has profound effects on basal mitochondrial function. These findings may have implications for exercise physiology-and lifestyle-related disorders that involve dysfunctional mitochondria.

Antioxidants & Redox Signaling, 2014

Abstract Aims: Inorganic nitrate and nitrite from endogenous and dietary sources have emerged as ... more Abstract Aims: Inorganic nitrate and nitrite from endogenous and dietary sources have emerged as alternative substrates for nitric oxide (NO) formation in addition to the classic L-arginine NO synthase (NOS)-dependent pathway. Here we investigated a potential crosstalk between these two pathways in regulation of vascular function.

Free Radical Biology and Medicine, 2010

Background: The metabolic syndrome is a clustering of risk factors of metabolic origin which incr... more Background: The metabolic syndrome is a clustering of risk factors of metabolic origin which increase the risk for cardiovascular disease and type-2 diabetes. The underlying mechanism for metabolic syndrome is not clear, however decreased nitric oxide (NO) production from endothelial NO synthase (eNOS) has been proposed. Recently, an alternative pathway for NO formation in mammals was described where inorganic nitrate, a supposedly inert NO oxidation product, is serially reduced to nitrite and then NO and other bioactive nitrogen oxides. Aim: Here we tested the hypothesis that eNOS-deficient mice develop features of the metabolic syndrome, and that dietary inorganic nitrate may have therapeutical effects. Methods and Results: eNOS-deficient mice developed features of the metabolic syndrome, which could be reversed by dietary inorganic nitrate supplementation (8-10 weeks). The daily amount of nitrate administered (0.1 mmol kg -1 day -1 ), is similar to that derived from eNOS under normal conditions. In humans this dose corresponds to a diet rich in vegetables, the major source of nitrate. Nitrate supplementation increased tissue and plasma levels of bioactive nitrogen oxides. Moreover, chronic nitrate treatment reduced visceral adipose tissue accumulation, reduced circulating triglyceride levels, and reversed the prediabetic phenotype in eNOS-deficient mice. In rats, chronic nitrate treatment reduced blood pressure and this effect was further pronounced during NOS inhibition. Conclusions: Dietary inorganic nitrate supplementation may fuel the nitrate-nitrite-NO pathway, thus compensate for disturbances in endogenous NO generation from eNOS. These findings suggest a role for inorganic nitrate in novel nutrition based preventive and therapeutic strategies against cardiovascular disease and type-2 diabetes.