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Van Hove JLK, Freehauf CL, Ficicioglu C, Pena LDM, Moreau KL, Henthorn TK, Christians U, Jiang H, Cowan TM, Young SP, Hite M, Friederich MW, Stabler SP, Spector EB, Kronquist KE, Thomas JA, Emmett P, Harrington MJ, Pyle L, Creadon-Swindell G, Wempe MF, MacLean KN. Biomarkers of oxidative stress, inflammation, and vascular dysfunction in inherited cystathionine β-synthase deficient homocystinuria and the impact of taurine treatment in a phase 1/2 human clinical trial. J Inherit Metab Dis 2019; 42:424-437. [PMID: 30873612 DOI: 10.1002/jimd.12085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/11/2019] [Indexed: 11/10/2022]
Abstract
STUDY OBJECTIVE A phase 1/2 clinical trial was performed in individuals with cystathionine β synthase (CBS) deficient homocystinuria with aims to: (a) assess pharmacokinetics and safety of taurine therapy, (b) evaluate oxidative stress, inflammation, and vascular function in CBS deficiency, and (c) evaluate the impact of short-term taurine treatment. METHODS Individuals with pyridoxine-nonresponsive CBS deficiency with homocysteine >50 μM, without inflammatory disorder or on antioxidant therapy were enrolled. Biomarkers of oxidative stress and inflammation, endothelial function (brachial artery flow-mediated dilation [FMD]), and disease-related metabolites obtained at baseline were compared to normal values. While maintaining current treatment, patients were treated with 75 mg/kg taurine twice daily, and treatment response assessed after 4 hours and 4 days. RESULTS Fourteen patients (8-35 years; 8 males, 6 females) were enrolled with baseline homocysteine levels 161 ± 67 μM. The study found high-dose taurine to be safe when excluding preexisting hypertriglyceridemia. Taurine pharmacokinetics showed a rapid peak level returning to near normal levels at 12 hours, but had slow accumulation and elevated predosing levels after 4 days of treatment. Only a single parameter of oxidative stress, 2,3-dinor-8-isoprostaglandin-F2α, was elevated at baseline, with no elevated inflammatory parameters, and no change in FMD values overall. Taurine had no effect on any of these parameters. However, the effect of taurine was strongly related to pretreatment FMD values; and taurine significantly improved FMD in the subset of individuals with pretreatment FMD values <10% and in individuals with homocysteine levels >125 μM, pertinent to endothelial function. CONCLUSION Taurine improves endothelial function in CBS-deficient homocystinuria in patients with preexisting reduced function.
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Affiliation(s)
- Johan L K Van Hove
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Cynthia L Freehauf
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Can Ficicioglu
- Division of Human Genetics, The Children's Hospital Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Loren D M Pena
- Division of Medical Genetics, Department of Pediatrics, Duke University, Durham, North Carolina
| | - Kerrie L Moreau
- Department of Medicine, School of Medicine, University of Colorado, Aurora, Colorado
- Geriatric Research and Education Center, Denver Veterans Administration Medical Center, Aurora, Colorado
| | - Thomas K Henthorn
- iC42 Clinical Research and Development, Department of Anesthesiology, School of Medicine, University of Colorado, Aurora, Colorado
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado
| | - Uwe Christians
- iC42 Clinical Research and Development, Department of Anesthesiology, School of Medicine, University of Colorado, Aurora, Colorado
| | - Hua Jiang
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Tina M Cowan
- Department of Pathology, Stanford University, Stanford, California
| | - Sarah P Young
- Division of Medical Genetics, Department of Pediatrics, Duke University, Durham, North Carolina
| | - Michelle Hite
- Research Institute, Children's Hospital Colorado, Aurora, Colorado
| | - Marisa W Friederich
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Sally P Stabler
- Department of Medicine, School of Medicine, University of Colorado, Aurora, Colorado
| | - Elaine B Spector
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Kathryn E Kronquist
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Janet A Thomas
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
| | - Peggy Emmett
- CTRC Core Laboratory, Children's Hospital Colorado, Aurora, Colorado
| | - Mary J Harrington
- CTRC Core Laboratory, Children's Hospital Colorado, Aurora, Colorado
| | - Laura Pyle
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado, Aurora, Colorado
| | | | - Michael F Wempe
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado
| | - Kenneth N MacLean
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, Colorado
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Maclean KN, Jiang H, Phinney WN, Keating AK, Hurt KJ, Stabler SP. Taurine alleviates repression of betaine‐homocysteine S‐methyltransferase and significantly improves the efficacy of long‐term betaine treatment in a mouse model of cystathionine β‐synthase–deficient homocystinuria. FASEB J 2019; 33:6339-6353. [DOI: 10.1096/fj.201802069rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Kenneth N. Maclean
- Department of PediatricsUniversity of Colorado School of Medicine Aurora Colorado USA
| | - Hua Jiang
- Department of PediatricsUniversity of Colorado School of Medicine Aurora Colorado USA
| | - Whitney N. Phinney
- Department of MedicineUniversity of Colorado School of Medicine Aurora Colorado USA
| | - Amy K. Keating
- Department of PediatricsUniversity of Colorado School of Medicine Aurora Colorado USA
| | - K. Joseph Hurt
- Department of Obstetrics and GynecologyUniversity of Colorado School of Medicine Aurora Colorado USA
| | - Sally P. Stabler
- Department of MedicineUniversity of Colorado School of Medicine Aurora Colorado USA
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Maclean KN, Jiang H, Aivazidis S, Kim E, Shearn CT, Harris PS, Petersen DR, Allen RH, Stabler SP, Roede JR. Taurine treatment prevents derangement of the hepatic γ-glutamyl cycle and methylglyoxal metabolism in a mouse model of classical homocystinuria: regulatory crosstalk between thiol and sulfinic acid metabolism. FASEB J 2018; 32:1265-1280. [PMID: 29101223 DOI: 10.1096/fj.201700586r] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cystathionine β-synthase-deficient homocystinuria (HCU) is a poorly understood, life-threatening inborn error of sulfur metabolism. Analysis of hepatic glutathione (GSH) metabolism in a mouse model of HCU demonstrated significant depletion of cysteine, GSH, and GSH disulfide independent of the block in trans-sulfuration compared with wild-type controls. HCU induced the expression of the catalytic and regulatory subunits of γ-glutamyl ligase, GSH synthase (GS), γ-glutamyl transpeptidase 1, 5-oxoprolinase (OPLAH), and the GSH-dependent methylglyoxal detoxification enzyme, glyoxalase-1. Multiple components of the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated antioxidant-response regulatory axis were induced without any detectable activation of Nrf2. Metabolomic analysis revealed the accumulation of multiple γ-glutamyl amino acids and that plasma ophthalmate levels could serve as a noninvasive marker for hepatic redox stress. Neither cysteine, nor betaine treatment was able to reverse the observed enzyme inductions. Taurine treatment normalized the expression levels of γ-glutamyl ligase C/M, GS, OPLAH, and glyoxalase-1, and reversed HCU-induced deficits in protein glutathionylation by acting to double GSH levels relative to controls. Collectively, our data indicate that the perturbation of the γ-glutamyl cycle could contribute to multiple sequelae in HCU and that taurine has significant therapeutic potential for both HCU and other diseases for which GSH depletion is a critical pathogenic factor.-Maclean, K. N., Jiang, H., Aivazidis, S., Kim, E., Shearn, C. T., Harris, P. S., Petersen, D. R., Allen, R. H., Stabler, S. P., Roede, J. R. Taurine treatment prevents derangement of the hepatic γ-glutamyl cycle and methylglyoxal metabolism in a mouse model of classical homocystinuria: regulatory crosstalk between thiol and sulfinic acid metabolism.
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Affiliation(s)
- Kenneth N Maclean
- Department of Pediatrics, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Hua Jiang
- Department of Pediatrics, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Stefanos Aivazidis
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Eugene Kim
- Department of Pediatrics, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Colin T Shearn
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Peter S Harris
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Dennis R Petersen
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Robert H Allen
- Department of Medicine, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - Sally P Stabler
- Department of Medicine, University of Colorado Health Sciences Center, Aurora, Colorado, USA
| | - James R Roede
- Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Aurora, Colorado, USA
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Oxidative Stress in Homocystinuria Due to Cystathionine ß-Synthase Deficiency: Findings in Patients and in Animal Models. Cell Mol Neurobiol 2017; 37:1477-1485. [PMID: 28258516 DOI: 10.1007/s10571-017-0478-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/21/2017] [Indexed: 12/13/2022]
Abstract
Homocystinuria is an inborn error of amino acid metabolism caused by deficiency of cystathionine ß-synthase (CBS) activity, biochemically characterized by homocysteine (Hcy) and methionine (Met) accumulation in biological fluids and high urinary excretion of homocystine. Clinical manifestations include thinning and lengthening of long bones, osteoporosis, dislocation of the ocular lens, thromboembolism, and mental retardation. Although the pathophysiology of this disease is poorly known, the present review summarizes the available experimental findings obtained from patients and animal models indicating that oxidative stress may contribute to the pathogenesis of homocystinuria. In this scenario, several studies have shown that enzymatic and non-enzymatic antioxidant defenses are decreased in individuals affected by this disease. Furthermore, markers of lipid, protein, and DNA oxidative damage have been reported to be increased in blood, brain, liver, and skeletal muscle in animal models studied and in homocystinuric patients, probably as a result of increased free radical generation. On the other hand, in vitro and in vivo studies have shown that Hcy induces reactive species formation in brain, so that this major accumulating metabolite may underlie the oxidative damage observed in the animal model and human condition. Taken together, it may be presumed that the disruption of redox homeostasis may contribute to the tissue damage found in homocystinuria. Therefore, it is proposed that the use of appropriate antioxidants may represent a novel adjuvant therapy for patients affected by this disease.
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Flavanone-rich citrus beverages counteract the transient decline in postprandial endothelial function in humans: a randomised, controlled, double-masked, cross-over intervention study. Br J Nutr 2017; 116:1999-2010. [PMID: 28065188 DOI: 10.1017/s0007114516004219] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Specific flavonoid-rich foods/beverages are reported to exert positive effects on vascular function; however, data relating to effects in the postprandial state are limited. The present study investigated the postprandial, time-dependent (0-7 h) impact of citrus flavanone intake on vascular function. An acute, randomised, controlled, double-masked, cross-over intervention study was conducted by including middle-aged healthy men (30-65 years, n 28) to assess the impact of flavanone intake (orange juice: 128·9 mg; flavanone-rich orange juice: 272·1 mg; homogenised whole orange: 452·8 mg; isoenergetic control: 0 mg flavanones) on postprandial (double meal delivering a total of 81 g of fat) endothelial function. Endothelial function was assessed by flow-mediated dilatation (FMD) of the brachial artery at 0, 2, 5 and 7 h. Plasma levels of naringenin/hesperetin metabolites (sulphates and glucuronides) and nitric oxide species were also measured. All flavanone interventions were effective at attenuating transient impairments in FMD induced by the double meal (7 h post intake; P<0·05), but no dose-response effects were observed. The effects on FMD coincided with the peak of naringenin/hesperetin metabolites in circulation (7 h) and sustained levels of plasma nitrite. In summary, citrus flavanones are effective at counteracting the negative impact of a sequential double meal on human vascular function, potentially through the actions of flavanone metabolites on nitric oxide.
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Weber GJ, Pushpakumar S, Tyagi SC, Sen U. Homocysteine and hydrogen sulfide in epigenetic, metabolic and microbiota related renovascular hypertension. Pharmacol Res 2016; 113:300-312. [PMID: 27602985 DOI: 10.1016/j.phrs.2016.09.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/31/2016] [Accepted: 09/02/2016] [Indexed: 12/18/2022]
Abstract
Over the past several years, hydrogen sulfide (H2S) has been shown to be an important player in a variety of physiological functions, including neuromodulation, vasodilation, oxidant regulation, inflammation, and angiogenesis. H2S is synthesized primarily through metabolic processes from the amino acid cysteine and homocysteine in various organ systems including neuronal, cardiovascular, gastrointestinal, and kidney. Derangement of cysteine and homocysteine metabolism and clearance, particularly in the renal vasculature, leads to H2S biosynthesis deregulation causing or contributing to existing high blood pressure. While a variety of environmental influences, such as diet can have an effect on H2S regulation and function, genetic factors, and more recently epigenetics, also have a vital role in H2S regulation and function, and therefore disease initiation and progression. In addition, new research into the role of gut microbiota in the development of hypertension has highlighted the need to further explore these microorganisms and how they influence the levels of H2S throughout the body and possibly exploiting microbiota for use of hypertension treatment. In this review, we summarize recent advances in the field of hypertension research emphasizing renal contribution and how H2S physiology can be exploited as a possible therapeutic strategy to ameliorate kidney dysfunction as well as to control blood pressure.
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Affiliation(s)
- Gregory J Weber
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY 40202, United States
| | - Sathnur Pushpakumar
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY 40202, United States
| | - Suresh C Tyagi
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY 40202, United States
| | - Utpal Sen
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY 40202, United States.
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Konradi J, Mollenhauer M, Baldus S, Klinke A. Redox-sensitive mechanisms underlying vascular dysfunction in heart failure. Free Radic Res 2015; 49:721-42. [DOI: 10.3109/10715762.2015.1027200] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Yamazaki F. Oral vitamin C enhances the adrenergic vasoconstrictor response to local cooling in human skin. J Appl Physiol (1985) 2012; 112:1689-97. [DOI: 10.1152/japplphysiol.00043.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Local administration of ascorbic acid (Asc) at a supraphysiological concentration inhibits the cutaneous vasoconstrictor response to local cooling (LC). However, whether orally ingesting Asc inhibits the LC-induced vasoconstrictor response remains unknown. The purpose of the present study was to examine the acute influence of oral Asc on the adrenergic vasoconstrictor response to LC in human skin. In experiment 1, skin blood flow (SkBF) was measured by laser-Doppler flowmetry at three sites (forearm, calf, palm). The three skin sites were locally cooled from 34 to 24°C at −1°C/min and maintained at 24°C for 20 min before (Pre) and 1.5 h after (Post) oral Asc (2-g single dose) or placebo supplementation. Cutaneous vascular conductance (CVC) was calculated as the ratio of SkBF to blood pressure and expressed relative to the baseline value before LC. Oral Asc enhanced ( P < 0.05) the reductions in CVC in the forearm (Pre, −50.3 ± 3.3%; Post, −57.8 ± 2.2%), calf (Pre, −52.6 ± 3.7%; Post, −66.1 ± 4.3%), and palm (Pre, −46.2 ± 6.2%; Post, −60.4 ± 5.6%) during LC. The placebo did not change the responses at any site. In experiment 2, to examine whether the increased vasoconstrictor response caused by oral Asc is due to the adrenergic system, the release of neurotransmitters from adrenergic nerves in forearm skin was blocked locally by iontophoresis of bretylium tosylate (BT). Oral Asc enhanced ( P < 0.05) the reductions in CVC at untreated control sites but did not change the responses at BT-treated sites during LC. In experiment 3, to further examine whether adrenergically mediated vasoconstriction is enhanced by oral Asc, 0.1 mM tyramine was administered using intradermal microdialysis in the forearm skin at 34°C in the Pre and Post periods. Oral Asc increased ( P < 0.05) the tyramine-induced reduction in CVC. These findings suggest that oral Asc acutely enhances the cutaneous vasoconstrictor responses to LC through the modification of adrenergic sympathetic mechanisms.
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Affiliation(s)
- Fumio Yamazaki
- Laboratory for Human Physiology, School of Health Sciences, University of Occupational and Environmental Health, Kitakyushu, Japan
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Stanger O, Wonisch W. Enzymatic and non-enzymatic antioxidative effects of folic acid and its reduced derivates. Subcell Biochem 2012; 56:131-161. [PMID: 22116698 DOI: 10.1007/978-94-007-2199-9_8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A great part of the population appears to have insufficient folate intake, especially subgroups with higher demand, as determined through more sensitive methods and parameters currently in use. As the role of folate deficiency in congenital defects, e.g. in cardiovascular and neurodegenerative diseases, and in carcinogenesis has become better understood, folate has been recognized as having great potential to prevent these many disorders through folate supplementation or fortification for the general population. Folates are essential cofactors in the transfer and utilization of one-carbon groups in the process of DNA-biosynthesis with implications for genomic repair and stability. Folate acts indirectly to lower homocysteine levels and insures optimal functioning of the methylation cycle. Homocysteine was shown to be an independent risk factor for neurodegenerative and cardiovascular disease, which includes peripheral vascular disease, coronary artery disease, cerebrovascular disease and venous thrombosis. In fact, it was long believed that the beneficial effects of folate on vascular function and disease are related directly to the mechanism of homocysteine-diminution. Recent investigations have, however, demonstrated beneficial effects of folates unrelated to homocysteine-diminution, suggesting independent properties. One such mechanism could be free radical scavenging and antioxidant activity, as it is now recognized that free radicals play an important role in the oxidative stress leading to many diseases. It was found that folic acid and, in particular, its reduced derivates act both directly and indirectly to produce antioxidant effects. Folates interact with the endothelial enzyme NO synthase (eNOS) and, exert effects on the cofactor bioavailability of NO and thus, on peroxynitrite formation. Folate metabolism provides an interesting example of gene-environmental interaction.
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Affiliation(s)
- Olaf Stanger
- Heart Division, Cardiothoracic Surgery, Royal Brompton and Harefield NHS Foundation, Imperial College of Science, Technology and Medicine, Sydney Street, London, SW3 6NP, UK,
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Frikke-Schmidt H, Lykkesfeldt J. Role of marginal vitamin C deficiency in atherogenesis: in vivo models and clinical studies. Basic Clin Pharmacol Toxicol 2009; 104:419-33. [PMID: 19489786 DOI: 10.1111/j.1742-7843.2009.00420.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Vitamin C is a pivotal redox modulater in many biological reactions of which several remain poorly understood. Naturally, vitamin C has been the subject of many investigations over the past decades in relation to its possible beneficial effects on cardiovascular disease primarily based on its powerful yet general antioxidant properties. However, growing epidemiological, clinical and experimental evidence now suggests a more specific role of ascorbate in vasomotion and in the prevention of atherosclerosis. For example, in contrast to most other biological antioxidants, administration of vitamin C can apparently induce vasodilation. Millions of people worldwide can be diagnosed with vitamin C deficiency according to accepted definitions. In this perspective, the present review examines the evidence for a specific link between vitamin C deficiency and increased risk of atherosclerosis as well as the possible mechanisms by which vitamin C may exert its protective function.
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Affiliation(s)
- Henriette Frikke-Schmidt
- Section of Biomedicine, Department of Disease Biology, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
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McCarty MF. Scavenging of peroxynitrite-derived radicals by flavonoids may support endothelial NO synthase activity, contributing to the vascular protection associated with high fruit and vegetable intakes. Med Hypotheses 2008; 70:170-81. [PMID: 17825500 DOI: 10.1016/j.mehy.2005.09.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Accepted: 09/07/2005] [Indexed: 01/24/2023]
Abstract
Ample intakes of fruit and vegetables have been linked epidemiologically with reduced risk for coronary disease, stroke, hypertension, obesity, many types of cancer, chronic pulmonary disease, osteoporosis, and various ocular disorders. The favorable impact of diets rich in fruit and vegetables on coronary risk has been confirmed in meta-analyses, and is thought to be largely attributable to the folk acid and potassium supplied by these foods. Although high intakes of vitamin C appear to confer some cardiovascular protection, the amounts supplied by typical diets may be too low to be of much benefit in this regard. High flavonoid intakes emerge as protective in some epidemiological studies, albeit the dose-response pattern observed is often L-shaped - seemingly more consistent with low intakes being harmful, than with high intakes being protective. Nonetheless, flavonoids have shown anti-atherogenic activity in rodent models, and both clinical and rodent supplementation studies with foods and food extracts rich in flavonoids demonstrate improvements in endothelium-dependent vasodilation traceable to increased endothelial nitric oxide synthesis. However, flavonoids do not appear to increase the expression of endothelial NO synthase, nor do they modify endothelial superoxide production. A likely explanation is that, even in nanomolar concentrations achievable in vivo, flavonoids can act as efficient scavengers of peroxynitrite-derived radicals, thereby protecting the cofactor tetrahydrobiopterin, crucial for NO synthase activity. Studies with cultured endothelial cells should be useful for evaluating this possibility. It would also be appropriate to assess the effects of flavonoids on prostacylin synthetase activity, on endothelial catabolism of asymmetric dimethylarginine, and on signaling mechanisms that activate NO synthase. Since peroxynitrite can induce mutagenic damage to DNA, it is conceivable that scavenging of peroxynitrite-derived radicals contributes to the reduction in mutagenesis associated with high intakes of fruits and vegetables. Carotenoids also have the potential to prevent peroxynitrite-mediated damage, although, as contrasted with flavonoids, there is comparatively little evidence that these compounds are anti-atherogenic or beneficial for endothelial function; a recent meta-analysis of epidemiological studies suggests that high lutein intakes may modestly reduce coronary risk.
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Affiliation(s)
- Mark F McCarty
- Natural Alternatives International, 1185 Linda Vista Dr., San Marcos, CA 92078, United States.
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McCarty MF. High-dose folate may improve platelet function in acute coronary syndrome and other pathologies associated with increased platelet oxidative stress. Med Hypotheses 2007; 69:12-9. [PMID: 17293058 DOI: 10.1016/j.mehy.2004.08.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 08/13/2004] [Indexed: 11/27/2022]
Abstract
Although nitric oxide of endothelial origin plays a major role in warding off inappropriate thrombus formation, platelets also express the "constitutive" isoform of nitric oxide synthase (cNOS). Activation of this enzyme by calcium influx during platelet aggregation provides an important feedback signal that dampens platelet recruitment. Platelets also express a membrane-bound NAD(P)H oxidase complex, activated by collagen receptors, that produces superoxide. Superoxide can directly quench NO; moreover, by giving rise to peroxynitrite, it can oxidize the cNOS cofactor tetrahydrobiopterin (BH4), thereby suppressing cNOS activity and converting it to superoxide generator. In a canine model of acute coronary syndrome, infusion of BH4 has been shown to prevent thrombus formation. Platelets from patients with acute coronary syndrome produce markedly less NO than do control platelets. A reasonable explanation for these findings is that episodic contact with collagen boosts platelet superoxide production, oxidizing BH4. Since 5-methyltetrahydrofolate can reduce oxidized BH4, or otherwise compensate for its deficiency, supplementation with its precursor folic acid may improve platelet function in acute coronary syndrome and possibly reduce risk for coronary thrombosis in other at-risk patients. Other research demonstrates that superoxide production is increased, and nitric oxide production diminished, in platelets of diabetics; the ability of glutathione--a peroxynitrite scavenger--to largely ameliorate these abnormalities, is consistent with a prominent role for BH4 deficiency in diabetic platelet malfunction. Reports that platelet NO production is decreased, and/or superoxide production increased, in patients with disorders associated with insulin resistance syndrome, suggest that BH4 deficiency--potentially remediable with high-dose folate--may likewise contribute to the platelet hyperreactivity noted in these disorders. Supplemental vitamin C and arginine also have the potential to boost platelet production of NO Increased intakes of taurine, magnesium, gamma-tocopherol, fish oil, and garlic may help to stabilize platelets by additional mechanisms. As a complement to the proven benefits of low-dose aspirin, a supplemental regimen emphasizing these nutrients in appropriate doses may act directly on platelets to further diminish risk for thrombotic episodes.
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Affiliation(s)
- Mark F McCarty
- Natural Alternatives International, 1185 Linda Vista Road, San Marcos, CA 92078, USA.
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Olthof MR, Bots ML, Katan MB, Verhoef P. Acute effect of folic acid, betaine, and serine supplements on flow-mediated dilation after methionine loading: a randomized trial. PLOS CLINICAL TRIALS 2006; 1:e4. [PMID: 16871326 PMCID: PMC1488894 DOI: 10.1371/journal.pctr.0010004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 03/29/2006] [Indexed: 12/31/2022]
Abstract
OBJECTIVES We investigated whether reducing post-methionine homocysteine concentrations via various treatments other than folic acid affects vascular function, as measured through flow-mediated dilation (FMD) of the brachial artery. High fasting and post-methionine homocysteine concentrations are associated with cardiovascular disease risk, but homocysteine might be a surrogate marker for low folate status. DESIGN This was a randomized, placebo-controlled, double-blind, crossover study. SETTING The study took place at Wageningen University in Wageningen in the Netherlands. PARTICIPANTS Participants were 39 apparently healthy men and women, aged 50-70 y. INTERVENTIONS Participants ingested 10 mg of folic acid, 3 g of betaine, 5 g of serine, and placebo together with an oral methionine load. Each supplement was tested on two different days. OUTCOME MEASURES On each of the eight treatment days, plasma homocysteine concentrations and FMD were measured before (t = 0 h, fasting) and 6 h (t = 6 h) after methionine loading. RESULTS The mean (+/- SD) fasting homocysteine concentrations averaged over the eight test days were 9.6 +/- 2.1 micromol/l. Mean fasting FMD was 3.1 +/- 2.4 FMD%. A methionine load with placebo increased homocysteine concentrations by 17.2 +/- 9.3 micromol/l at 6 h after loading, similar to the increase following methionine loading with folic acid. A methionine load together with betaine and with serine increased homocysteine by 10.4 +/- 2.8 micromol/l (p < 0.001 relative to placebo) and by 12.1 +/- 8.2 micromol/l (p < 0.001 relative to placebo), respectively. Methionine loading with placebo did not affect FMD, and neither did methionine loading with folic acid, betaine, or serine; differences relative to placebo were +0.7 FMD% (95%CI, -0.6; 1.9), +0.2 FMD% (-1.0; 1.3), and +0.3 FMD% (-0.8; 1.4), respectively. CONCLUSIONS Experimentally induced acute changes in homocysteine concentrations did not affect FMD in healthy volunteers. This implies that potential adverse effects of high homocysteine concentrations on the cardiovascular system are not mediated through vascular function. However, homocysteine or folate may affect cardiovascular disease risk through other mechanisms.
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Affiliation(s)
- Margreet R Olthof
- Wageningen Centre for Food Sciences and Wageningen University, Wageningen, Netherlands.
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Wilcken DEL, Wang J, Sim AS, Green K, Wilcken B. Asymmetric dimethylarginine in homocystinuria due to cystathionine beta-synthase deficiency: relevance of renal function. J Inherit Metab Dis 2006; 29:30-7. [PMID: 16601865 DOI: 10.1007/s10545-006-0208-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2005] [Accepted: 12/02/2005] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Vascular disease is associated with increased plasma asymmetric dimethylarginine (ADMA) and homocysteine, and both are increased in renal failure. In cystathionine beta-synthase deficiency (CBS) there is severe hyperhomocysteinaemia, precocious vascular disease, and endothelial dysfunction. We investigated whether ADMA levels are elevated in CBS patients with and without renal impairment, and whether lowering plasma homocysteine also lowers ADMA. METHODS We measured plasma homocysteine, arginine, asymmetric and symmetric dimethylarginines, nitrate + nitrite, creatinine and cystatin C in 23 CBS-deficient patients and 24 age-matched controls. RESULTS In the patients, nitrate + nitrite and the ratio L: -arginine/ADMA were markedly reduced (21.6 +/- 6.1 vs 57.7 +/- 7.5 micromol/L and 132.9 +/- 24.7 vs 181.9 +/- 56.1, respectively, p < 0.001 for both), reflecting endothelial dysfunction. Plasma ADMA for the group was moderately increased (0.55 +/- 0.08 vs 0.49 +/- 0.07 micromol/L, p = 0.018), but this was due to significantly higher levels than controls in only those 7 of the 23 patients who had elevated cystatin C levels (0.59 +/- 0.08 vs 0.49 +/- 0.07 mg/L, p = 0.007). Posttreatment total homocysteine in patients varied widely (15-285, median 92 micromol/L), but was not correlated with ADMA or other measured variables. In three newly-diagnosed patients, marked reduction of total homocysteine during treatment produced minimal changes in ADMA. CONCLUSIONS ADMA levels were significantly increased only in the CBS-deficient patients with elevated cystatin C levels, and not in those with normal renal function. The reported relationship between hyperhomocysteinaemia and ADMA may not be direct, but could be secondary to reduced renal function.
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15
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Stefanello FM, Franzon R, Tagliari B, Wannmacher C, Wajner M, Wyse ATS. Reduction of butyrylcholinesterase activity in rat serum subjected to hyperhomocysteinemia. Metab Brain Dis 2005; 20:97-103. [PMID: 15938128 DOI: 10.1007/s11011-005-4147-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In the present study we investigate the effect of homocysteine (Hcy) administration, the main metabolite accumulating in homocystinuria, on butyrylcholinesterase (BuChE) activity in serum of rats. For the acute treatment, 29-day-old Wistar rats received one subcutaneous injection of Hcy (0.6 micromol/g) or saline (control) and were killed 1 h later. For the chronic treatment, Hcy was administered subcutaneously to rats from the 6th to the 28th day of life. Control rats received saline. The rats were killed 12 h after the last injection. In another set of experiments, rats were pretreated for one week with vitamins E and C or saline and 12 h after the last injection received one single injection of Hcy or saline, being killed 1 h later. Serum was used to determine BuChE activity. Our results showed that acute and chronic administration of Hcy significantly decreased BuChE activity. Furthermore, vitamins E and C per se did not alter BuChE activity, but prevented the reduction of this enzyme activity caused by acute administration of Hcy. The data suggest that the inhibitory effect of Hcy on BuChE activity is probably mediated by free radicals, since vitamins E and C administration prevented such effect.
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Affiliation(s)
- Francieli M Stefanello
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, CEP, Porto Alegre, RS, Brasil
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16
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Riksen NP, Rongen GA, Boers GHJ, Blom HJ, van den Broek PHH, Smits P. Enhanced Cellular Adenosine Uptake Limits Adenosine Receptor Stimulation in Patients With Hyperhomocysteinemia. Arterioscler Thromb Vasc Biol 2005; 25:109-14. [PMID: 15539618 DOI: 10.1161/01.atv.0000150651.85907.69] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
Endogenous adenosine has several cardioprotective effects. We postulate that in patients with hyperhomocysteinemia increased intracellular formation of S-adenosylhomocysteine decreases free intracellular adenosine. Subsequently, facilitated diffusion of extracellular adenosine into cells through dipyridamole-sensitive transporters is enhanced, limiting adenosine receptor stimulation. We tested this hypothesis in patients with classical homocystinuria (n=9, plasma homocysteine 93.1±24.7 μmol/L) and matched controls (n=8, homocysteine 9.1±1.0).
Methods and Results—
Infusion of adenosine (0.5, 1.5, 5.0, and 15.0 μg/min/dL forearm) into the brachial artery increased forearm blood flow, as measured with venous occlusion plethysmography, to 2.9±0.4, 4.3±0.5, 5.6±1.1, and 9.6±2.1 in the patients and to 2.8±0.6, 4.4±1.0, 9.0±1.7, and 17.0±3.1 mL/min/dL in controls (
P
<0.05). However, adenosine-induced vasodilation in the presence of dipyridamole (100 μg/min/dL) was similar in both groups (
P
=0.9). Additionally, in isolated erythrocytes, adenosine uptake was accelerated by incubation with homocysteine (half-time 6.4±0.3 versus 8.1±0.5 minutes,
P
<0.001) associated with increased intracellular formation of S-adenosylhomocysteine (
P
<0.0001).
Conclusions—
In hyperhomocysteinemia, adenosine-induced vasodilation is impaired but is restored by dipyridamole. Accelerated cellular adenosine uptake probably accounts for these observations. These impaired actions of adenosine could well contribute to the cardiovascular complications of hyperhomocysteinemia.
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Affiliation(s)
- Niels P Riksen
- Department of Pharmacology-Toxicology 233, University Medical Centre Nijmegen, Geert Grooteplein 21, 6525 EZ Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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17
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Hinderliter AL, Caughey M. Assessing endothelial function as a risk factor for cardiovascular disease. Curr Atheroscler Rep 2004; 5:506-13. [PMID: 14525685 DOI: 10.1007/s11883-003-0042-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The vascular endothelium plays a key role in the prevention of atherosclerosis. Endothelial dysfunction is an antecedent of clinical cardiovascular disease and can be viewed as the final pathway between coronary risk factors and the development of atherosclerosis. The development of a noninvasive method of assessing endothelial health (ie, measurement of flow- mediated dilation of the brachial artery) has enabled investigators to evaluate the effects of dietary patterns on vascular function. Emerging evidence indicates that dietary fats may acutely impair endothelial function, but this effect is dependent on the type of fat and on the other nutrients consumed. Although inconclusive, studies in cohorts of modest size suggest that antioxidants, L-arginine, and folic acid may modulate endothelial function. Additional research is needed to define the impact of complex, long-term dietary patterns on the vascular endothelium.
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Affiliation(s)
- Alan L Hinderliter
- Division of Cardiology, University of North Carolina, 130 Mason Farm Road, Chapel Hill, NC 27599-7075, USA.
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18
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Moat SJ, Lang D, McDowell IFW, Clarke ZL, Madhavan AK, Lewis MJ, Goodfellow J. Folate, homocysteine, endothelial function and cardiovascular disease. J Nutr Biochem 2004; 15:64-79. [PMID: 14972346 DOI: 10.1016/j.jnutbio.2003.08.010] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2003] [Revised: 08/19/2003] [Accepted: 08/25/2003] [Indexed: 10/26/2022]
Abstract
Evidence reported from numerous clinical studies over the past decade has revealed an association between increased plasma total homocysteine (tHcy) concentrations and cardiovascular disease (CVD). In addition, epidemiological studies have identified an inverse association between blood folate concentrations, folate intake and cardiovascular endpoints, that are independent of homocysteine. Folic acid supplementation can lower plasma tHcy concentrations safely and inexpensively. Furthermore, folic acid can reverse endothelial dysfunction observed in patients with CVD. This reversal in endothelial dysfunction with folic acid has been shown to be independent of plasma tHcy lowering, suggesting that folate has pleiotropic effects on the vasculature other than homocysteine lowering. In vitro evidence demonstrates that 5-methyltetrahydrofolate (5MeTHF) the main circulating metabolite of folate, can increase nitric oxide production and can directly scavenge superoxide radicals. The potential beneficial role of folic acid supplements on vascular disease are currently being tested in randomized placebo controlled studies.
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Affiliation(s)
- Stuart J Moat
- Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Cardiff, UK.
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19
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Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies (NDA) a request from the Commission related to the Tolerable Upper Intake Level of Vitamin C (L-Ascorbic acid, its calcium, potassium and sodium salts and L-ascorbyl-6-palmitate. EFSA J 2004. [DOI: 10.2903/j.efsa.2004.59] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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20
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McCarty MF. Coping with endothelial superoxide: potential complementarity of arginine and high-dose folate. Med Hypotheses 2004; 63:709-18. [PMID: 15325022 DOI: 10.1016/j.mehy.2002.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 11/11/2002] [Indexed: 01/31/2023]
Abstract
Superoxide overproduction is a prominent mediator of the endothelial dysfunction associated with a range of vascular disorders, acting in a number of complementary ways to inhibit effective endothelial nitric oxide (NO) activity. The ability of superoxide to quench NO is well known, but oxidants derived from superoxide also appear to inhibit dimethylarginine dimethylaminohydrolase (DDAH) and to oxidize tetrahydrobiopterin (THBP). The former effect boosts the level of methylated arginines that act as potent competitive inhibitors of NO synthase, whereas the latter effect decreases the ability of this enzyme to generate NO, while converting it to a form that readily generates superoxide. The adverse impact of DDAH deficiency on NO production can be offset with supplemental arginine. Although supplementation with THBP has the potential to compensate for the rapid oxidative destruction of this compound, and maintaining optimal vitamin C nutrition may protect or restore the endothelial THBP pool to a limited extent, the most practical way to optimize NO synthase activity in the context of THBP deficit may be administration of high-dose folic acid. The primary circulating metabolite of folate, 5-methyltetrahydrofolate (5MTHF), is structurally analogous to THBP, and appears to normalize the activity of NO synthase in THBP-depleted endothelial cells, either because it "pinch hits" for the absent THBP, or interacts allosterically with NO synthase in some other way to promote the proper function of this enzyme. This observation may rationalize recent clinical studies showing a favorable effect of oral folic acid (5-10 mg daily) on dysfunctional endothelium, independent of any concurrent modulation of homocysteine levels. A recent study reports that, whereas either arginine or THBP alone have only a modest impact on dysfunctional aortic endothelium derived from hypercholesterolemic mice, the combination of the two produces a complete normalization of endothelial function. In aggregate, these considerations suggest that joint administration of arginine and high-dose folate may represent a fruitful approach to preventing and treating vascular disorders - albeit the underlying overproduction of superoxide should also be addressed by ameliorating relevant vascular risk factors.
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Affiliation(s)
- Mark F McCarty
- Pantox Laboratories, 4622 Santa Fe St., San Diego, CA 92109, USA.
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Bagi Z, Cseko C, Tóth E, Koller A. Oxidative stress-induced dysregulation of arteriolar wall shear stress and blood pressure in hyperhomocysteinemia is prevented by chronic vitamin C treatment. Am J Physiol Heart Circ Physiol 2003; 285:H2277-83. [PMID: 12869370 DOI: 10.1152/ajpheart.00448.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We aimed to test the hypothesis that an enhanced level of reactive oxygen species (ROS) is primarily responsible for the impairment of nitric oxide (NO)-mediated regulation of arteriolar wall shear stress (WSS) in hyperhomocysteinemia (HHcy). Thus flow/WSS-induced dilations of pressurized gracilis muscle arterioles (basal diameter: approximately 170 microm) isolated from control (serum Hcy: 6 +/- 1 microM), methionine diet-induced HHcy rats (4 wk, serum Hcy: 30 +/- 6 microM), and HHcy rats treated with vitamin C, a known antioxidant (4 wk, 150 mg. kg body wt-1.day-1; serum Hcy: 32 +/- 10 microM), were investigated. In vessels of HHcy rats, increases in intraluminal flow/WSS-induced dilations were converted to constrictions. Constrictions were unaffected by inhibition of NO synthesis by N omega-nitro-L-arginine methyl ester (L-NAME). Vitamin C treatment of HHcy rats reversed the WSS-induced arteriolar constrictions to L-NAME-sensitive dilations but did not affect control responses. Similar changes in responses were obtained for the calcium ionophore A-23187. In addition, diastolic and mean arterial blood pressure and serum 8-isoprostane levels (a marker of in vivo oxidative stress) were significantly elevated in rats with HHcy, changes that were normalized by vitamin C treatment. Taken together, our data show that in chronic HHcy long-term vitamin C treatment, by decreasing oxidative stress in vivo, enhanced NO bioavailability, restored the regulation of shear stress in arterioles, and normalized systemic blood pressure. Thus our study provides evidence that oxidative stress is an important in vivo mechanism that is primarily responsible for the development of endothelial dysregulation of WSS in HHcy.
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Affiliation(s)
- Zsolt Bagi
- Department of Physiology, New York Medical College, Valhalla, NY 10595, USA
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Abstract
Traditional risk factors as measured in the fasted individual are reported to be responsible for the prediction of only half of the incident cases of cardiovascular disease. However, many complex and deleterious reactions occur in the postprandial state. The consequences of oxidative reactions occurring during this time represent major risk for fatal and nonfatal heart disease, ischemia, and stroke, and include oxidative modifications to low-density lipoproteins (LDL), decreased production and bioactivity of nitric oxide (NO) in endothelial cells, and reduced endothelial function. Supplementation with antioxidants may prevent or reduce many of these risks. Antioxidants have been shown to reduce oxidative modification to LDL cholesterol, prevent glucose auto-oxidation, improve the bioactivity of NO, and attenuate or prevent the decrease in endothelial function associated with the postprandial state. Because many nonfasting reactions represent major risk for disease, postprandial risk analysis must form a larger part of the diagnostic strategy for disease prevention in the future.
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Affiliation(s)
- Colin D Kay
- Department of Human Biology and Nutritional Sciences, University of Guelph, ANNU Building, Room 342, Guelph, Ontario N1G 2W1, Canada
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