Treatment of atherosclerosis in the new millennium: is there a role for vitamin E?

Vitamin E-induced coagulopathy in a young patient: a case report

BACKGROUND

High-dose vitamin E intake is known to inhibit vitamin K-derived coagulation factor synthesis, which can cause serious bleeding events such as gastrointestinal bleeding and intracranial hemorrhage. We report a case of coagulopathy induced by marginally increased levels of vitamin E.

CASE PRESENTATION

A 31-year-old Indian man presented with oral bleeding, black tarry stools, and bruising over his back. He had been taking non-steroidal anti-inflammatory drugs for low backache and vitamin E for hair loss. He had mild anemia with normal platelet count, thrombin time, and prolonged bleeding time, activated partial thromboplastin time, and prothrombin time. Serum fibrinogen was slightly raised. Mixing studies with pooled normal plasma, aged plasma, and adsorbed plasma were suggestive of deficiency of multiple coagulation factors due to acquired vitamin K deficiency. Serum phylloquinone was normal, while prothrombin induced by vitamin K absence-II level was increased. Serum alpha-tocopherol was slightly raised. Upper gastrointestinal endoscopy showed multiple gastroduodenal erosions. A final diagnosis of vitamin E toxicity-related coagulopathy was made. The patient responded well to pantoprazole, vitamin K supplementation, multiple fresh frozen plasma transfusions, and other supportive treatments besides the discontinuation of vitamin E supplementation. The coagulation parameters normalized, and the patient was discharged with complete resolution of symptoms and remained asymptomatic during the follow-up for 6 months.

CONCLUSIONS

Vitamin E-related inhibition of vitamin K-dependent factors with coagulopathy may occur even at marginally increased levels of serum vitamin E. This risk becomes significant in patients receiving other drugs that may increase the risk of bleeding.

Could Antioxidant Supplementation Delay Progression of Cardiovascular Disease in End-Stage Renal Disease Patients?

In end-stage renal disease patients, the leading causes of mortality are of cardiovascular (CV) origin. The underlying mechanisms are complex, given that sudden heart failure is more common than acute myocardial infarction. A contributing role of oxidative stress is postulated, which is increased even at early stages of chronic kidney disease, is gradually augmented in parallel to progression to endstage renal disease and is further accelerated by renal replacement therapy. Oxidative stress ensues when there is an imbalance between reactive pro-oxidants and physiologically occurring electron donating antioxidant defence systems. During the last decade, a close association of oxidative stress with accelerated atherosclerosis and increased risk for CV and all-cause mortality has been established. Lipid peroxidation has been identified as a trigger for endothelial dysfunction, the first step towards atherogenesis. In order to counteract the deleterious effects of free radicals and thereby ameliorate, or delay, CV disease, exogenous administration of antioxidants has been proposed. Here, we attempt to summarize existing data from studies that test antioxidants for CV protection, such as vitamins E and C, statins, omega-3 fatty acids and N-acetylcysteine.

Alpha-tocopherol and contrast-induced nephropathy: A meta-analysis of randomized controlled trials

Background: Contrast-induced nephropathy (CIN) is a relevant cause of acute renal dysfunction and is associated with an increased morbidity and mortality. Purpose: Verify the effect of α-tocopherol pre-treatment on CIN prevention in subjects with chronic kidney disease. Methods: A Medline/Embase and clinicaltrials.gov were searched up to May 1st, 2017. Randomized controlled trials recruiting patients undergoing diagnostic or therapeutic radiocontrast infusion comparing the effect of either oral or i.v. multiple administration of pharmacological dose of α-tocopherol in preventing CIN versus placebo were included. A random-effects model, calculating Mantel-Haenszel odds ratio with 95% confidence interval, was applied to study the effect of α-tocopherol on CIN occurrence. Funnel plot analysis was used to assess publication bias, while agreement within studies was measured by the I² index and tested with the Q-Cochran test. Results: Out of 242 studies, 4 trials were selected. CIN incidence resulted significantly lower in α-tocopherol compared to placebo group (5.8% vs. 15.4%, MH-OR [95% C.I.] 0.34 [0.19 - 0.59]). Alpha-tocopherol treatment was associated with both a tendential higher eGFR (mean difference 2.19 [95% C.I. -0.41; 4.79] mL/min) and lower creatinine level (mean difference -0.06 [95% C.I. -0.21; 0.09] mg/dl) compared to placebo. No relevant publication bias (p = 0.48) and heterogeneity (I² = 0%; χ² = 1.01, df = 3 [p = 0.80], I² = 0%) were evident. Conclusions: Alpha-tocopherol pre-treatment is associated with reduction of incidence of CIN. Its administration deserves to be further explored as a simple and inexpensive tool for CIN prevention.

Solid phase synthesis of mitochondrial triphenylphosphonium-vitamin E metabolite using a lysine linker for reversal of oxidative stress

Mitochondrial targeting of antioxidants has been an area of interest due to the mitochondria's role in producing and metabolizing reactive oxygen species. Antioxidants, especially vitamin E (α-tocopherol), have been conjugated to lipophilic cations to increase their mitochondrial targeting. Synthetic vitamin E analogues have also been produced as an alternative to α-tocopherol. In this paper, we investigated the mitochondrial targeting of a vitamin E metabolite, 2,5,7,8-tetramethyl-2-(2′-carboxyethyl)-6-hydroxychroman (α-CEHC), which is similar in structure to vitamin E analogues. We report a fast and efficient method to conjugate the water-soluble metabolite, α-CEHC, to triphenylphosphonium cation via a lysine linker using solid phase synthesis. The efficacy of the final product (MitoCEHC) to lower oxidative stress was tested in bovine aortic endothelial cells. In addition the ability of MitoCEHC to target the mitochondria was examined in type 2 diabetes db/db mice. The results showed mitochondrial accumulation in vivo and oxidative stress decrease in vitro.

Is there a role for supplemented antioxidants in the prevention of atherosclerosis?

BACKGROUND

Oxidative stress is thought to play a substantial role in the pathogenesis of atherosclerosis. Supplementation of antioxidants has been studied as a strategy in the prevention of occurrence and progression of atherosclerosis.

METHOD

We searched the MEDLINE and PubMed databases (up to February 2008) for randomized, double-blind, placebo-controlled trials of antioxidant (and in particular vitamins E, C and/or beta-carotene) supplementation, published in English.

RESULTS

We identified 22 trials (N=134,590 subjects) of antioxidant supplementation for the prevention of atherosclerosis (7 primary, 13 secondary and 2 both primary and secondary). Of these studies, 10 examined the effect of a single antioxidant supplementation on primary or secondary prevention of cardiovascular disease, while 12 the effect of a combination of antioxidants.

CONCLUSION

As the majority of studies included in this review does not support a possible role of antioxidant supplementation in reducing the risk of cardiovascular disease, no definite conclusion can be drawn to justify the use of antioxidant vitamin supplements for the prevention of atherosclerotic events.

Antioxidant vitamins induce angiogenesis in the normal pig kidney

The effects of chronic supplementation with antioxidant vitamins on angiogenesis are controversial. The aim of the present study was to evaluate in kidneys of normal pigs the effect of chronic supplementation with vitamins E and C, at doses that are effective in reducing oxidative stress and attenuating angiogenesis under pathological conditions. Domestic pigs were randomized to receive a 12-wk normal diet without ( n = 6) or with antioxidant vitamins supplementation (1g/day vitamin C, 100 IU·kg−1·day−1 vitamin E; n = 6). Electron beam computed tomography (CT) was used to evaluate renal cortical vascular function in vivo, and micro-CT was to assess the spatial density and average diameter of cortical microvessels (diameter <500 μm) ex vivo. Oxidative stress and expressions of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor (HIF)-1α were evaluated in renal tissue. The effects of increasing concentrations of the same vitamins on redox status and angiogenesis were also evaluated in human umbilical vascular endothelial cells (HUVEC). Compared with normal pigs, the density of cortical transmural microvessels was significantly greater in vitamin-supplemented pigs (149.0 ± 11.7 vs. 333.8 ± 48.1 vessel/cm2, P < 0.05), whereas the cortical perfusion response to ACh was impaired. This was accompanied by a significant increase in tissue oxidative stress and levels of VEGF and HIF-1α. A low dose of antioxidant decreased, whereas a high dose increased, HUVEC oxidative stress and angiogenesis, which was partly mediated by hydrogen peroxide. Antioxidant vitamin supplementation can increase tissue oxidative redox and microvascular proliferation in the normal kidney, probably due to a biphasic effect that depends on basal redox balance.

Circulating 4-hydroxynonenal-protein thioether adducts assessed by gas chromatography-mass spectrometry are increased with disease progression and aging in spontaneously hypertensive rats

Oxidative stress has been implicated in numerous degenerative diseases of aging, including heart diseases. However, there is still a need to identify biomarkers of oxidative stress-related events, such as protein modification by the lipid peroxidation product 4-hydroxynonenal (HNE) in these diseases in humans. The objective of this study was to assess if circulating levels of HNE-protein adducts (i) can be assessed with precision by GCMS and (ii) vary with disease progression and aging in a model of cardiomyopathy that displays enhanced oxidative stress, namely the spontaneously hypertensive rats (SHR). We modified a previously published isotope dilution GCMS method that quantifies HNE and its inactive metabolite, 1,4-dihydroxynonene (DHN), bound to thiol proteins following treatment with NaB(2)H(4) and Raney nickel, to increase its sensitivity (20-fold), precision, and robustness. Levels of these adducts were measured in blood and plasma collected from SHR and control Wistar rats at 7, 15, 22, and 30 weeks of age. Levels of protein-bound HNE, which were quantitated with good precision in the nanomolar range in blood, but not in plasma, were significantly increased by disease (SHR) and age (P < 0.0001 for both). Compared to Wistar rats, SHR showed greater blood levels of HNE-protein adducts at 22 and 30 weeks. Levels of protein-bound DHN, which were detected in blood and in plasma, were not affected by disease or age. Collectively, the results of this study conducted in an animal model of cardiomyopathy demonstrate that changes in blood HNE-protein thioether adducts with disease progression and aging can be assessed with good precision by the described GCMS method. This method may prove to be useful in evaluating the occurrence and impact of oxidative stress-related events involving bioactive HNE in heart diseases and aging in humans.

Symptoms and Treatment in Cancer Therapy‐Induced Early Menopause

Young women with breast cancer often experience early menopause as a result of the therapy for their malignant disease. The sudden occurrence of menopause resulting from chemotherapy, oophorectomy, radiation, or gonadal dysgenesis frequently results in hot flashes that begin at a younger age and may occur at a greater frequency and intensity than hot flashes associated with natural menopause. Hormone therapy relieves symptoms effectively in 80%-90% of women who initiate treatment. This therapy, however, is generally contraindicated in estrogen-dependent cancers, such as breast cancer, because of the potentially increased risk for recurrence. Many agents have been investigated as potential means for alleviating hot flashes in survivors of breast cancer, such as progestagens, clonidine, gabapentin, and anti-depressants. Several complementary and alternative medicines frequently used by patients have also been studied. These include black cohosh, phytoestrogens, homeopathy, vitamin E, acupuncture, and behavior strategies. To support the use of one of more of these nonpharmacological or pharmacological options in the treatment of hot flashes in breast cancer patients, more evidence from well-controlled clinical trials is needed. In particular, soundly based scientific research with complementary and alternative medicine therapies is lacking. Pharmacological treatments appear to be more beneficial than nonpharmacological treatments. This article reviews the current literature to assess the epidemiology and diagnosis of hot flashes and the nonpharmacological and pharmacological options for the treatment of hot flashes, in breast cancer patients in particular. When specific treatment options have not been evaluated in breast cancer patients specifically, published data on the management of hot flashes with this modality in healthy postmenopausal women are described.

Hyperoxaluria-induced oxidative stress and antioxidants for renal protection

Renal cellular exposure to oxalate (Ox) and/or CaOx crystals leads to the production of reactive oxygen species (ROS), development of oxidative stress followed by injury and inflammation. Renal injury and inflammation appear to play a significant role in stone formation. ROS are produced from many sources and involve a variety of signaling pathways. Tissue culture and animal model studies show that treatments with anti-oxidants and free radical scavengers reduce Ox/CaOx crystal induced injuries. In addition, CaOx crystal deposition in kidneys is significantly reduced by treatments with antioxidants and free radical scavengers, indicating their efficacy. These results point towards a great potential for the therapeutic application of antioxidants and free radical scavengers to reduce stone recurrence particularly after shock wave lithotripsy, which is itself known to generate ROS and cause renal damage.

Lipid peroxidation in diabetes mellitus

There is considerable evidence that hyperglycemia represents the main cause of complications of diabetes mellitus (DM), and oxidative stress resulting from increased generation of reactive oxygen species plays a crucial role in their pathogenesis. In fact, in the absence of an appropriate response from endogenous antioxidant mechanisms, the redox imbalance causes the activation of stress-sensitive intracellular signaling pathways. The latter play a key role in the development of late complications of DM, as well as in mediating insulin resistance (i.e., resistance to insulin-mediated glucose uptake by some cells) and impaired insulin secretion. This review, focused on lipid peroxidation in DM, will examine the mechanisms and clinical readouts of oxidative stress in this setting, the relationship between lipid peroxidation and antioxidant status in type 1 and type 2 DM, the effects of hyperglycemia and metabolic control on in vivo markers of lipid peroxidation (i.e., isoprostanes), and the association between isoprostane formation and platelet activation. Finally, possible targets of antioxidant therapy for diabetic vascular complications will be discussed.

Biological functions and metabolic fate of vitamin E revisited

Information accumulated lately has confirmed the essentiality of vitamin E for humans and provided a better understanding of its biological function and metabolic fate. The discovery of alpha-tocopherol transfer protein, which preferentially binds to RRR-alpha-tocopherol, not only provides conclusive evidence of the essentiality of vitamin E for humans, but also sheds light on the superiority of RRR-alpha-tocopherol biologically over other isomers. The presence of tocopherol regeneration systems and multiple interdependent antioxidant systems is largely responsible for the lack of a widespread deficiency in humans and the difficulty to deplete vitamin E in the adult. The bulk of excess tocopherols consumed is excreted to feces unchanged or to urine with the side chain shortened but the chroman ring intact. The ability of dietary vitamin E to mediate mitochondrial superoxide generation affords a possible mode of action of vitamin E at the tissue levels. By decreasing the generation and/or the levels of reactive oxygen/nitrogen species, dietary vitamin E not only protects against oxidative damage, but also modulates the expression and/or activation of redox-sensitive biological response modifiers that regulate important cellular events.

Effect of vitamin E supplementation on vitamin K status in adults with normal coagulation status

BACKGROUND

Cases of enhanced anticoagulant effect in response to high-dose vitamin E supplementation have been reported among patients taking oral anticoagulants. Although a vitamin E-vitamin K interaction was proposed to underlie this effect, it has not been systematically investigated in adults with normal baseline coagulation status.

OBJECTIVE

The objective was to study the effect of 12 wk of supplementation with 1000 IU RRR-alpha-tocopherol/d on biochemical measures of vitamin K status in men and women not taking oral anticoagulants.

DESIGN

Vitamin K status, which was assessed with the use of plasma phylloquinone concentrations, the degree of under-gamma-carboxylation of prothrombin (proteins induced by vitamin K absence-factor II, PIVKA-II), and the percentage of undercarboxylated osteocalcin (ucOC), was determined in 38 men and women with rheumatoid arthritis (study A) and in 32 healthy men (study B) participating in 2 independent, 12-wk randomized clinical trials of vitamin E supplementation (1000 IU/d).

RESULTS

Mean (+/- SD) PIVKA-II increased from 1.7 +/- 1.7 to 11.9 +/- 16.1 ng/mL (P < 0.001) in study A and from 1.8 +/- 0.6 to 5.3 +/- 3.9 ng/mL (P < 0.001) in study B in response to 12 wk of vitamin E supplementation. An increase in PIVKA-II is indicative of poor vitamin K status. In contrast, the other measures of vitamin K status (ie, plasma phylloquinone concentration and percentage of ucOC) did not change significantly in response to the supplementation.

CONCLUSIONS

High-dose vitamin E supplementation increased PIVKA-II in adults not receiving oral anticoagulant therapy. The clinical significance of these changes warrants further investigation, but high doses of vitamin E may antagonize vitamin K. Whether such an interaction is potentially beneficial or harmful remains to be determined.

Effect of vitamin E on glutathione-dependent enzymes

Reactive oxygen species and various electrophiles are involved in the etiology of diseases varying from cancer to cardiovascular and pulmonary disorders. The human body is protected against damaging effects of these compounds by a wide variety of systems. An important line of defense is formed by antioxidants. Vitamin E (consisting of various forms of tocopherols and tocotrienols) is an important fat-soluble, chain-breaking antioxidant. Besides working as an antioxidant, this compound possesses other functions with possible physiological relevance. The glutathione-dependent enzymes form another line of defense. Two important enzymes in this class are the free radical reductase and glutathione S-transferases (GSTs). The GSTs are a family of phase II detoxification enzymes. They can catalyze glutathione conjugation with various electrophiles. In most cases the electrophiles are detoxified by this conjugation, but in some cases the electrophiles are activated. Antioxidants do not act in isolation but form an intricate network. It is, for instance, known that vitamin E, together with glutathione (GSH) and a membrane-bound heat labile GSH-dependent factor, presumably an enzyme, can prevent damaging effects of reactive oxygen species on polyunsaturated fatty acids in biomembranes (lipid peroxidation). This manuscript reviews the interaction between the two defense systems, vitamin E and glutathione-dependent enzymes. On the simplest level, antioxidants such as vitamin E have protective effects on glutathione-dependent enzymes; however, we will see that reality is somewhat more complicated.