Homocysteine and coronary atherosclerosis: from folate fortification to the recent clinical trials

The role of redox signaling in epigenetics and cardiovascular disease

SIGNIFICANCE

The term epigenetics refers to the changes in the phenotype and gene expression that occur without alterations in the DNA sequence. There is a rapidly growing body of evidence that epigenetic modifications are involved in the pathological mechanisms of many cardiovascular diseases (CVDs), which intersect with many of the pathways involved in oxidative stress.

RECENT ADVANCES

Most studies relating epigenetics and human pathologies have focused on cancer. There has been a limited study of epigenetic mechanisms in CVDs. Although CVDs have multiple established genetic and environmental risk factors, these explain only a portion of the total CVD risk. The epigenetic perspective is beginning to shed new light on how the environment influences gene expression and disease susceptibility in CVDs. Known epigenetic changes contributing to CVD include hypomethylation in proliferating vascular smooth muscle cells in atherosclerosis, changes in estrogen receptor-α (ER-α) and ER-β methylation in vascular disease, decreased superoxide dismutase 2 expression in pulmonary hypertension (PH), as well as trimethylation of histones H3K4 and H3K9 in congestive heart failure.

CRITICAL ISSUES

In this review, we discuss the epigenetic modifications in CVDs, including atherosclerosis, congestive heart failure, hypertension, and PH, with a focus on altered redox signaling.

FUTURE DIRECTIONS

As advances in both the methodology and technology accelerate the study of epigenetic modifications, the critical role they play in CVD is beginning to emerge. A fundamental question in the field of epigenetics is to understand the biochemical mechanisms underlying reactive oxygen species-dependent regulation of epigenetic modification.

Descriptive study of possible link between cardioankle vascular index and homocysteine in vascular-related diseases

OBJECTIVES

Cardioankle vascular index (CAVI) is a new index of arterial stiffness independent of immediate blood pressure. Homocysteine (Hcy) is an independent risk factor for vascular diseases. The aim of this study was to investigate the relationship between Hcy and CAVI in the vascular-related diseases.

DESIGN

Descriptive research.

PARTICIPANTS

88 patients (M/F 46/42) with or without hypertension, coronary artery disease or arteriosclerosis obliterans were enrolled to our study. They were divided into two groups according to the level of Hcy.

METHODS

CAVI, carotid-femoral pulse wave velocity (CF-PWV) and carotid-radial pulse wave velocity (CR-PWV) were measured by VS-1000 and Complior apparatus.

RESULTS

There was significant correlation between Hcy and CF-PWV, CR-PWV, CAVI in the entire group (r=0.33, p=0.002; r=0.51, p<0.001; r=0.42, p<0.001, respectively). And there was significant correlation between Hcy and CF-PWV, CR-PWV, CAVI in the vascular-related disease group (r=0.23, p=0.048; r=0.51, p<0.001; r=0.392, p=0.001, respectively). The level of Hcy was significantly higher in patients with one or more vascular diseases than in patients without vascular diseases. The levels of CF-PWV, CR-PWV and CAVI were significantly higher in Hcy ≥15 μmol/l group than in Hcy <5 μmol/l group (13.7±3.0 vs 10.8±2.5, p < 0.001; 10.6±2.1 vs 9.2±1.6, p=0.001; 9.30±2.1 vs 7.79±2.1, p=0.001, respectively). Multiple linear regression showed that Hcy, body mass index (BMI) and age were independent associating factors of CAVI in the entire study group (β=0.421, p=0.001; β=-0.309, p=0.006; β=0.297, p=0.012, respectively). And Hcy, BMI and age were independent influencing factors of CAVI in the vascular-related disease group (β=0.434, p=0.001; β=-0.331, p=0.009; β=0.288, p=0.022, respectively).

CONCLUSIONS

CAVI was positively correlated with Hcy in the vascular-related diseases.

Hyperhomocysteinemia is an independent risk factor in young patients with coronary artery disease in southern China

BACKGROUND

Elevated plasma homocysteine (Hcy) is considered to be a risk factor of coronary artery disease (CAD), although this is still controversially discussed. This study investigated the role of Hcy in young patients with CAD in southern China.

METHODS

A total of 146 consecutive patients (aged ≤ 55 years) with angiographically proven CAD were enrolled in the study and 138 age-matched non-CAD individuals were included as the control group. Hcy levels were measured by enzymatic assay. Hyperhomocysteinemia (HHcy) was defined as Hcy ≥ 15 µmol/l. A 10-year CAD risk was calculated using the Framingham risk score (FRS) modified according to the National Cholesterol Education Program Adult Treatment Panel III.

RESULTS

There were significant differences between the CAD and control groups with regard to male sex (P < 0.01), smoking history (P < 0.05), and triglyceride levels (TG, P < 0.05), but no remarkable difference in other conventional risk factors (all P > 0.05). Hcy and high-sensitivity C-reactive protein (hs-CRP) levels were significantly higher in the CAD group than those in the control group (both P < 0.05). The FRS and estimated 10-year absolute CAD event risk were low in both groups and did not show a statistical difference. Multivariate logistic regression showed that male sex (odds ratio, OR, 3.68; 95 % confidence interval, 95 % CI, 1.54-10.01), smoking (OR, 2.54; 95 % CI, 1.15-5.36), TG (OR, 1.30; 95  % CI, 1.08-3.06), hs-CRP (OR, 3.74; 95 % CI, 1.72-12.21), and HHcy (OR, 2.03; 95 % CI, 1.26-5.83) were independently correlated with CAD in young patients.

CONCLUSION

HHcy is an important independent risk factor for CAD in young patients in southern China after adjusting for other risk factors.

Elevated homocysteine levels are associated with low muscle strength and functional limitations in older persons

OBJECTIVE

The current study aimed to examine homocysteine in relation to different aspects of physical functioning.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional and longitudinal data (3-years follow-up) from the Longitudinal Aging Study Amsterdam (LASA) were used. The study was performed in persons aged ≥ 65 years (N= 1301 after imputation).

MEASUREMENTS

Different measures of physical functioning, including muscle mass, grip strength, functional limitations, and falling were regarded as outcomes. Gender and serum creatinine level were investigated as effect modifiers.

RESULTS

Results were stratified by gender. In men, higher homocysteine levels were associated with lower grip strength (Quartile 4: regression coefficient (B)= -3.07 (-4.91; -1.22)), and more functional limitations at baseline (Quartile 4: B= 1.15 (0.16-2.14)). In women, higher homocysteine levels were associated with more functional limitations after 3 years (Quartile 4: B= 1.19 (0.25; 2.13)). Higher homocysteine levels were not associated with low muscle mass or falling.

CONCLUSIONS

These data suggest an inverse association of homocysteine levels with functional limitations in older men and women, and with muscle strength in older men.

Hass avocado composition and potential health effects

Hass avocados, the most common commercial avocado cultivars in the world, contain a variety of essential nutrients and important phytochemicals. Although the official avocado serving is one-fifth of a fruit (30 g), according to NHANES analysis the average consumption is one-half an avocado (68 g), which provides a nutrient and phytochemical dense food consisting of the following: dietary fiber (4.6 g), total sugar (0.2 g), potassium (345 mg), sodium (5.5 mg), magnesium (19.5 mg), vitamin A (43 μg), vitamin C (6.0 mg), vitamin E (1.3 mg), vitamin K1 (14 μg), folate (60 mg), vitamin B-6 (0.2 mg), niacin (1.3 mg), pantothenic acid (1.0 mg), riboflavin (0.1 mg), choline (10 mg), lutein/zeaxanthin (185 μg), phytosterols (57 mg), and high-monounsaturated fatty acids (6.7 g) and 114 kcals or 1.7 kcal/g. The avocado oil consists of 71% monounsaturated fatty acids (MUFA), 13% polyunsaturated fatty acids (PUFA), and 16% saturated fatty acids (SFA), which helps to promote healthy blood lipid profiles and enhance the bioavailability of fat soluble vitamins and phytochemicals from the avocado or other fruits and vegetables, naturally low in fat, which are consumed with avocados. There are eight preliminary clinical studies showing that avocado consumption helps support cardiovascular health. Exploratory studies suggest that avocados may support weight management and healthy aging.

Genistein attenuates vascular endothelial impairment in ovariectomized hyperhomocysteinemic rats

Hyperhomocysteinemia (HHcy) is a well-known independent risk factor for vascular diseases in the general population. This study was to explore the effect of genistein (GST), a natural bioactive compound derived from legumes, on HHcy-induced vascular endothelial impairment in ovariectomized rats in vivo. Thirty-two adult female Wistar rats were assigned randomly into four groups (n = 8): (a) Con: control; (b) Met: 2.5% methionine diet; (c) OVX + Met: ovariectomy + 2.5% methionine diet; (d) OVX + Met + GST: ovariectomy + 2.5% methionine diet + supplementation with genistein. After 12 wk of different treatment, the rats' blood, toracic aortas and liver samples were collected for analysis. Results showed that high-methionine diet induced both elevation of plasma Hcy and endothelial dysfunction, and ovariectomy deteriorated these injuries. Significant improvement of both functional and morphological changes of vascular endothelium was observed in OVX + Met + GST group; meanwhile the plasma Hcy levels decreased remarkably. There were significant elevations of plasma ET-1 and liver MDA levels in ovariectomized HHcy rats, and supplementation with genistein could attenuate these changes. These results implied that genistein could lower the elevated Hcy levels, and prevent the development of endothelial impairment in ovariectomized HHcy rats. This finding may shed a novel light on the anti-atherogenic activities of genistein in HHcy patients.

Methodology for a rapid and simultaneous determination of total cysteine, homocysteine, cysteinylglycine and glutathione in plasma by isocratic RP-HPLC

Alterations in the plasma aminothiols levels can be considered as important biomarkers for the diagnosis and screening of several human disorders, namely cardiovascular diseases. We aimed to optimize a rapid, sensitive and accurate RP-HPLC methodology with fluorescence detection, for the simultaneous determination of the total concentrations of cysteine, homocysteine, cysteinylglycine and glutathione in blood plasma, as well as its application to the evaluation of those thiols levels in plasma of a group of Azorean subjects. Aminothiols were reduced with tri-n-butylphosphine and derivatized with a thiol-specific fluorogenic reagent ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate. The thiols adducts were separated by an isocratic elution on a Platinum EPS C18 analytical column (53mm×7mm I.D., 3μm) using a phosphate buffer containing 4% of acetonitrile as a mobile phase. Results indicated an excellent linearity for all the analytes over their respective concentration ranges with correlation coefficients (r(2)) ≥0.99. The LOD for the four plasma thiols was lower than 0.10μmol/L, while LOQ varied from 0.5 to 15μmol/L. For both intra- and inter-day precision, the RSD (%) values were lower than 1.9%, and the CV (%) values were found under 0.5%. The recovery ranged from 92% to 100% indicating a high degree of the method's accuracy. This method allows a simultaneous, complete analysis of the four plasma aminothiols and the internal standard in 6min. By reducing the total run time, a larger number of analysis can be performed daily.

Linking preeclampsia and cardiovascular disease later in life

Preeclampsia (PE), which is defined as new onset hypertension after 20 weeks of pregnancy accompanied by proteinuria, is characterized by inadequate placentation, oxidative stress, inflammation and widespread endothelial dysfunction. A link between PE and long-term risk of cardiovascular disease (CVD) was suggested by retrospective studies, which found that PE was associated with a 2–3-fold risk of CVD later in life, with a 5–7-fold risk in the case of severe and/or early-onset PE. Recently, meta-analyses and prospective studies have confirmed the association between PE and the emergence of an unfavorable CVD risk profile, in particular a 3–5-fold increased prevalence of the metabolic syndrome only 8 years after the index pregnancy. PE and CVD share many risk factors, including obesity, hypertension, dyslipidemia, hypercoagulability, insulin resistance and both entities are characterized by endothelial dysfunction. PE and CVD are complex traits sharing common risk factors and pathophysiological processes, but the genetic link between both remains to be elucidated. However, recent evidence suggests that genetic determinants associated with the metabolic syndrome, inflammation and subsequent endothelial dysfunction are involved. As the evidence now supports that PE represents a risk factor for the emergence of the metabolic syndrome and CVD later in life, the importance of long-term follow-up assessment of CVD risk beginning early in women with a history of PE must be considered and translated into new preventive measures.

Effect of 9p21.3 coronary artery disease locus neighboring genes on atherosclerosis in mice

BACKGROUND

The human 9p21.3 chromosome locus has been shown to be an independent risk factor for atherosclerosis in multiple large-scale genome-wide association studies, but the underlying mechanism remains unknown. We set out to investigate the potential role of the 9p21.3 locus neighboring genes, including Mtap, the 2 isoforms of Cdkn2a, p16Ink4a and p19Arf, and Cdkn2b, in atherosclerosis using knockout mice models.

METHODS AND RESULTS

Gene-targeted mice for neighboring genes, including Mtap, Cdkn2a, p19Arf, and Cdkn2b, were each bred to mice carrying the human APO*E3 Leiden transgene that sensitizes the mice for atherosclerotic lesions through elevated plasma cholesterol. We found that the mice heterozygous for Mtap developed larger lesions compared with wild-type mice (49623±21650 versus 18899±9604 μm(2) per section [mean±SD]; P=0.01), with morphology similar to that of wild-type mice. The Mtap heterozygous mice demonstrated changes in metabolic and methylation profiles and CD4(+) cell counts. The Cdkn2a knockout mice had smaller lesions compared with wild-type and heterozygous mice, and there were no significant differences in lesion size in p19Arf and Cdkn2b mutants compared with wild type. We observed extensive, tissue-specific compensatory regulation of the Cdkn2a and Cdkn2b genes among the various knockout mice, making the effects on atherosclerosis difficult to interpret.

CONCLUSIONS

Mtap plays a protective role against atherosclerosis, whereas Cdkn2a appears to be modestly proatherogenic. However, no relation was found between the 9p21 genotype and the transcription of 9p21 neighboring genes in primary human aortic vascular cells in vitro. There is extensive compensatory regulation in the highly conserved 9p21 orthologous region in mice.

From hypertension to stroke: mechanisms and potential prevention strategies

Stroke is a major cause of disability and death worldwide. Prevention aimed at risk factors of stroke is the most effective strategy to curb the stroke pandemic. Hypertension is one of the most important risk factors for stroke. Despite the substantial evidence of the benefits of lowering blood pressure, conventional treatment does not normalize the burden of major cardiovascular events in patients with hypertension. Fully understanding the factors involved in the hypertension-induced stroke helps to develop new strategies for stroke prevention. Antihypertensive therapies selected should have positive blood pressure-independent effects on stroke risk. This review summarizes the factors involved in the hypertension-induced stroke, such as oxidative stress, inflammation, and arterial baroreflex dysfunction, and potential strategies for its prevention, therefore, provides clues for clinicians.

Fortification of flours with folic acid reduces homocysteine levels in Brazilian women

Our hypothesis is that the fortification of flour with folic acid contributes to the reduction of plasma homocysteine (Hcy). We conducted a cross-sectional study covering 2 periods, before and after fortification (2002-2003 and 2008-2009, respectively), to assess the influence of the consumption of corn and wheat flours prefortification and postfortification with folic acid on Hcy levels and other biomarkers. In the total, 93 women (38 prefortification and 55 postfortification) were included. Levels of lipids and glucose, total Hcy and serum folate, and cobalamin were determined using commercial kits by colorimetric method, competitive immunoassay, and chemiluminescence, respectively The participants' average age was 48.1 ± 9.5 years for the prefortification group and 39.1 ± 4.1 years for the postfortification group (P < .001) but adjusted statistical tests by age. Both groups presented obesity class 1. In the prefortification group, 71.1% (n = 27) of women had a dietary intake of folate, which was lower than the current recommended for adults (< 400 μg/d), whereas in the postfortification group, only 16.4% (n = 9) of women had lower intakes than recommended. In the prefortification group, 42.1% (n = 16) of women had hyperhomocysteinemia (> 10 mmol/L) compared with only 9.1% (n = 5) in the postfortification group. Moreover, statistically significant differences were found between the 2 groups in total cholesterol, high-density lipoprotein, triglycerides, and dietary fiber. Our findings corroborate the hypothesis that fortification of wheat and corn flours with folic acid can possibly be associated with lower concentrations of plasma Hcy, providing probable greater cardiovascular protection in this group.

The human paraoxonase gene cluster as a target in the treatment of atherosclerosis

The paraoxonase (PON) gene cluster contains three adjacent gene members, PON1, PON2, and PON3. Originating from the same fungus lactonase precursor, all of the three PON genes share high sequence identity and a similar β propeller protein structure. PON1 and PON3 are primarily expressed in the liver and secreted into the serum upon expression, whereas PON2 is ubiquitously expressed and remains inside the cell. Each PON member has high catalytic activity toward corresponding artificial organophosphate, and all exhibit activities to lactones. Therefore, all three members of the family are regarded as lactonases. Under physiological conditions, they act to degrade metabolites of polyunsaturated fatty acids and homocysteine (Hcy) thiolactone, among other compounds. By detoxifying both oxidized low-density lipoprotein and Hcy thiolactone, PONs protect against atherosclerosis and coronary artery diseases, as has been illustrated by many types of in vitro and in vivo experimental evidence. Clinical observations focusing on gene polymorphisms also indicate that PON1, PON2, and PON3 are protective against coronary artery disease. Many other conditions, such as diabetes, metabolic syndrome, and aging, have been shown to relate to PONs. The abundance and/or activity of PONs can be regulated by lipoproteins and their metabolites, biological macromolecules, pharmacological treatments, dietary factors, and lifestyle. In conclusion, both previous results and ongoing studies provide evidence, making the PON cluster a prospective target for the treatment of atherosclerosis.

Riboflavin offers a targeted strategy for managing hypertension in patients with the MTHFR 677TT genotype: a 4-y follow-up

BACKGROUND

We recently reported that the elevated blood pressure (BP) observed in patients with cardiovascular disease who are homozygous for the 677C→T polymorphism (TT genotype) in the gene encoding methylenetetrahydrofolate reductase (MTHFR) was responsive to supplementation with riboflavin-the cofactor for MTHFR.

OBJECTIVE

The objective was to investigate the effect of riboflavin on BP targeted at patients with the TT genotype 4 y after initial investigation, during which time major changes in the clinical guidelines for antihypertensive therapy were introduced.

DESIGN

A total of 83 patients (representing all 3 genotypes) who participated in a placebo-controlled riboflavin intervention for 16 wk in 2004 agreed to take part. Nested within this follow-up, those with the TT genotype (n = 31) proceeded to intervention with riboflavin (1.6 mg/d for 16 wk) or placebo, conducted in a crossover style whereby the 2004 treatment groups were reversed.

RESULTS

At follow-up in 2008, as in 2004, patients with the TT genotype had higher systolic BP (P < 0.01), with a nonsignificant trend noted for higher diastolic BP (P = 0.051). Despite the marked changes in antihypertensive therapy that had occurred, BP remained unchanged in patients with the TT genotype at the time of follow-up. Riboflavin supplementation (administered in 2004 and 2008) produced an overall decrease in systolic (-9.2 ± 12.8 mm Hg; P = 0.001) and diastolic (-6.0 ± 9.9 mm Hg; P = 0.003) BP.

CONCLUSIONS

Optimizing riboflavin status offers a low-cost targeted strategy for managing elevated BP in this genetically at-risk group. These findings, if confirmed in the general population, could have important implications for the prevention of hypertension.

Value and level of plasma homocysteine in patients with angina pectoris undergoing coronary angiographic study

This study tested whether the plasma level of total homocysteine (tHcy) was predictive of obstructive coronary artery disease (CAD) and clinical outcome in patients undergoing coronary angiographic (CAG) study. From September 2002 to October 2004, 1,305 consecutive patients with angina pectoris undergoing CAG study were consecutively enrolled. Blood samples were prospectively collected to assess the plasma level of tHcy from each patient before catheterization. Of these 1305 patients, 676 (51.8%) had multivessel disease (group 1), 367 (28.1%) had single-vessel disease (group 2), and 262 (20.1%) had normal coronary artery or insignificant coronary artery disease (group 3). The plasma level of tHcy was notably higher in group 1 than in groups 2 and 3 (11.6 ± 4.4 versus 10.9 ± 4.0 versus 10.4 ± 3.8, P < 0.001). Univariate binary logistic regression analysis demonstrated that the plasma tHcy level was strongly associated with multiple-vessel disease (MVD) (defined as ≥ 2 vessel disease) (P < 0.001). Multivariate binary logistic regression analysis showed that tHcy level, fasting blood sugar, diabetes mellitus, and age were significantly and independently predictive of MVD (all P < 0.03). Univariate Cox regression analysis demonstrated that tHcy level was predictive of long-term mortality (P = 0.042). However, the tHcy level was not an independent predictor of long-term mortality on multivariate Cox regression analysis (P > 0.05). The results of our study support the hypothesis that tHcy level is an independent predictor of MVD in patients with chest pain undergoing CAG study. Conversely, our study did not support the tHcy level as an independent predictor of long-term mortality in this clinical setting.

Helicobacter pylori infection, chronic atrophic gastritis and major cardiovascular events: a population-based cohort study

OBJECTIVE

There is debate whether infection with Helicobacter (H.) pylori, the main inducer of chronic atrophic gastritis (CAG), is a risk factor for cardiovascular disease and premature mortality.

METHODS

Serological measurements of H. pylori infection and pepsinogen (PG) I and II were obtained in a population-based German cohort of 9953 older adults (50-74 years). Cox regression was employed to estimate hazard ratios (HR) and 95% confidence intervals (CI) for myocardial infarction, stroke, cardiovascular and all-cause mortality during five-year follow-up.

RESULTS

According to serology, 4977 participants (51.9%) were infected with H. pylori (2604 with cytotoxin-associated gene A (cagA) strains) and 541 (5.7%) had CAG (PGI<70 ng/mL and PGI/PGII<3). During follow-up, 540 participants died (163 from cardiovascular causes), 170 experienced a primary myocardial infarction and 241 had a stroke. Neither cytotoxin-associated gene A (cagA) negative nor cagA positive H. pylori infections were associated with an increased risk for myocardial infarction, stroke or all-cause mortality. Intriguingly, infection with cagA positive H. pylori strains was inversely associated with cardiovascular mortality (HR, 0.62; CI: 0.41-0.94). No statistically significant associations were observed for the small group of participants with CAG, but point estimates of adjusted HRs for myocardial infarction, stroke and cardiovascular mortality were all below 1 (0.71, 0.59 and 0.65, respectively).

CONCLUSIONS

Our results do not support the hypothesis that H. pylori infection or CAG are risk factors for cardiovascular disease or mortality and instead suggest an inverse relationship of cagA positive H. pylori infection with fatal cardiovascular events.

Glutathione peroxidase-1 in health and disease: from molecular mechanisms to therapeutic opportunities

Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace mineral selenium and selenocysteine incorporation during translation. In addition, GPx-1 has been implicated in the development and prevention of many common and complex diseases, including cancer and cardiovascular disease. This review discusses the role of GPx-1 in these diseases and speculates on potential future therapies to harness the beneficial effects of this ubiquitous antioxidant enzyme.

Multiple coronary artery thrombosis in 5,10-methylenetetrahydrofolate reductase gene mutation

A 42-year-old man presented at our attention with chest pain. His cardiac risk factors were smoking habit and family history of coronary artery disease. At the ECG, a mild ST-segment elevation in the inferior leads was shown. A normal left ventricular function was demonstrated at the echocardiography. An emergency coronary angiography was performed, and an extensive thrombosis of the right coronary artery and midleft anterior descending coronary artery was visualized. A primary angioplasty with thrombus aspiration and direct stenting of both sites followed. Biochemical analysis revealed a high plasma homocysteine level with a homozygotic anomaly of the 5,10-methylenetetrahydrofolate reductase. Currently, a nine-month followup negative for cardiac events is recorded.

AMP-activated protein kinase inhibits homocysteine-induced dysfunction and apoptosis in endothelial progenitor cells

PURPOSE

Homocysteine (Hcy) has been shown to induce oxidative stress and apoptosis of endothelial progenitor cells (EPCs). AMP-activated protein kinase (AMPK) has been reported to have protective effects on endothelial function. However, effects of AMPK activation on Hcy-induced EPCs injury remain to be determined. In this study, we examined the effect of AMPK phosphorylation on Hcy-induced NO bioavailability impairment and NADPH oxidase 4 (Nox4) derived reactive oxygen species (ROS) accumulation in EPCs.

MATERIALS AND METHODS

EPCs were pre-treated with various concentrations of 5-amino-4-imidazolecarboxamide riboside-l-beta-D-ribofuranoside (AICAR), a pharmacological agonist of AMPK, and then incubated with Hcy for 24 h. Furthermore, we challenged EPCs with Hcy in the presence or absence of atorvastatin and AMPK-DN which expressed a dominant-negative mutant of AMPK. Migration, proliferation and apoptosis were assayed to evaluate EPCs function. NO production, expression of endothelial nitric oxide synthase (eNOS), intracellular ROS levels and Nox4 activation were determined to explore the potential mechanisms of Hcy-induced EPCs dysfunction.

RESULTS

We observed that AICAR attenuated the inhibition effects of Hcy on EPCs migration and proliferation. The apoptosis rates of EPCs were down-regulated by AICAR compared with the group treated with Hcy only [(0.25 mmol/L AICAR: 10.48 ± 1.6%; 0.5 mmol/L AICAR: 8.70 ± 1.0%; 1 mmol/L AICAR: 5.83 ± 1.3%) vs. (500 μmol/L Hcy only: 12.60 ± 1.9%)]. We also found that NO production and eNOS expression were up-regulated by AICAR compared with the group treated with Hcy only, while ROS accumulation and Nox4 activation were inhibited. Furthermore, atorvastatin suppressed Hcy-induced dysfunction of EPCs, increased NO production and eNOS expression, and down-regulated ROS accumulation and Nox4 activation. And these effects of atorvastatin could be blunted by AMPK-DN.

CONCLUSION

AMPK activation inhibits eNOS down-regulation and Nox4-derived ROS accumulation induced by Hcy in EPCs, and may contribute to the protective effects of atorvastatin on endothelial function.

Macrophage activation and coronary atherosclerosis in systemic lupus erythematosus and rheumatoid arthritis

OBJECTIVE

Activation of macrophages may contribute to increased atherosclerosis and coronary artery disease in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Neopterin, a pteridine derivative, is a novel marker of monocyte and macrophage activation that is associated with atherosclerosis and cardiovascular risk in the general population. We examined the hypothesis that macrophage activation is associated with accelerated atherosclerosis in SLE and RA.

METHODS

We compared serum neopterin concentrations, adjusted for age, race, sex, and serum creatinine concentration, in patients with SLE (n=148) or RA (n=166) and control subjects (n=177). In patients with SLE or RA, serum neopterin concentrations were then tested for association (adjusted for age, race, sex, serum creatinine, and medication use) with measures of disease activity or damage, inflammatory markers and mediators, and coronary artery calcium measured by electron beam computed tomography.

RESULTS

Neopterin concentrations were significantly higher in patients with SLE (median 8.0, interquartile range [IQR] 6.5-9.8 nmoles/liter) and RA (median 6.7, IQR 5.3-8.9 nmoles/liter) than controls (median 5.7, IQR 4.8-7.1 nmoles/liter), and were higher in SLE patients than in RA patients (all P<0.001). In SLE, neopterin was significantly correlated with higher erythrocyte sedimentation rate (ESR; P=0.001), tumor necrosis factor α (P<0.001), monocyte chemoattractant protein 1 (P=0.005), and homocysteine concentrations (P=0.01), but in RA, it was only associated with ESR (P=0.01). Neopterin was not associated with coronary calcium in either SLE (P=0.65) or RA (P=0.21).

CONCLUSION

Macrophage activation, reflected by increased serum neopterin concentrations, was increased in both SLE and RA. Neopterin was more robustly associated with atherogenic mediators of inflammation and homocysteine in SLE than in RA, but was not associated with coronary atherosclerosis in either disease.

Atorvastatin inhibits homocysteine-induced endoplasmic reticulum stress through activation of AMP-activated protein kinase

AIM

Accumulating evidence suggests that endoplasmic reticulum (ER) stress plays a fundamental role in the initiation and development of atherosclerosis. Atorvastatin is known to exert pleiotropic effects on cardiovascular system. This study was designed to examine the effect of atorvastatin on homocysteine (Hcy)-induced activation of ER stress and the potential mechanisms regarding AMP-activated protein kinase (AMPK).

METHODS AND RESULTS

Apolipoprotein E-deficient (apoE(-/-)) mice were administrated with methionine or atorvastatin and sacrificed 2 months later for plasma tests and immunohistochemical analysis. To further study the mechanisms, human umbilical vein endothelial cells (HUVECs) were incubated with various concentrations of Hcy for 1 h, or 500 μmol/L Hcy for 1-24 h. Furthermore, we challenged HUVECs with Hcy in the presence or absence of atorvastatin, 5-amino-4-imidazolecarboxamide riboside-l-beta-D-ribofuranoside (AICAR), an AMPK agonist, and AMPK-DN that expressed a dominant-negative mutant of AMPK. Expression levels of ER stress markers were measured by real-time PCR and Western blot analysis. Our data revealed that atorvastatin prevented Hcy-induced ER stress in the aortic roots of hyperhomocysteinemic mice. In vitro study showed atorvastatin suppressed Hcy-induced ER stress in HUVECs as well. AICAR is found to have the same effect as that of atorvastatin, which could be antagonized by AMPK-DN.

CONCLUSIONS

Atorvastatin inhibits Hcy-induced ER stress both in vitro and in vivo. The protective effect of atorvastatin against Hcy-induced vascular injury is mediated by AMPK activation.

Tetra primer ARMS-PCR relates folate/homocysteine pathway genes and ACE gene polymorphism with coronary artery disease

Cardiovascular disorders and coronary artery disease (CAD) are significant contributors to morbidity and mortality in heart patients. As genes of the folate/homocysteine pathway have been linked with the vascular disease, we investigated association of these gene polymorphisms with CAD/myocardial infarction (MI) using the novel approach of tetraprimer ARMS-PCR. A total of 230 participants (129 MI cases, 101 normal subjects) were recruited. We genotyped rs1801133 and rs1801131 SNPs in 5'10' methylenetetrahydrofolate reductase (MTHFR), rs1805087 SNP in 5' methyltetrahydrofolate homocysteine methyltransferase (MTR), rs662 SNP in paroxanse1 (PON1), and rs5742905 polymorphism in cystathionine beta synthase (CBS). Angiotensin converting enzyme (ACE) insertion/deletion polymorphism was detected through conventional PCR. Covariates included blood pressure, fasting blood sugar, serum cholesterol, and creatinine concentrations. Our results showed allele frequencies at rs1801133, rs1801131, rs1805087 and the ACE insertion/deletion (I/D) polymorphism varied between cases and controls. Logistic regression, after adjusting for covariates, demonstrated significant associations of rs1801133 and rs1805087 with CAD in the additive, dominant, and genotype model. In contrast, ACE I/D polymorphism was significantly related with CAD where recessive model was applied. Gene-gene interaction against the disease status revealed two polymorphism groups: rs1801133, rs662, and rs1805087; and rs1801131, rs662, and ACE I/D. Only the latter interaction maintained significance after adjusted for covariates. Our study concludes that folate pathway variants exert contributory influence on susceptibility to CAD. We further suggest that tetraprimer ARMS-PCR successfully resolves the genotypes in selected samples and might prove to be a superior technique compared to the conventional approach.

Determinants of hyperhomocysteinemia after gastric bypass surgery in obese subjects

BACKGROUND

Effectiveness of gastric bypass (GBP) on reduction of vascular risk factors is well established, but GBP induces nutritional deficits that could reduce the cardiovascular benefit of weight loss. Particularly, hyperhomocysteinemia, now clearly identified as a vascular risk factor, has been described after GBP. The aim of this study was to clarify the factors associated with increased homocysteine concentration after GBP.

METHODS

Homocysteine concentration and multiple nutritional parameters were measured in 213 consecutive subjects. One hundred and eight subjects were studied before surgery (control (CT)), 115 one to 6 years after GBP, and 41 both before and 6 months after GBP.

RESULTS

Homocysteine concentration did not differ before and after GBP (9.1 ± 3.2 vs 8.6 ± 3.4 μmol/l), but 94% of subjects had been supplemented with a multivitamin preparation after surgery. The nutritional parameters best correlated with homocysteine concentration both before and after GBP were folate and creatinine concentrations (p < 0.0001). In contrast, vitamin B12 and metabolic parameters (including glucose, insulin, lipids and C-reactive protein) were not associated with homocysteine concentration. After GBP, homocysteine concentration was significantly lower in subjects taking a multivitamin supplementation containing a high dose of folate than those who did not (7.7 ± 2.8 vs 10.1 ± 3.9 μmol/l, p < 0.0001).

CONCLUSIONS

The main determinants of homocysteine concentration identified in this study are folate and serum creatinine. Multivitamin supplementation with a high dose of folate prevents hyperhomocysteinemia after GBP.

Folate supplementation in schizophrenia: a possible role for MTHFR genotype

BACKGROUND

Folate deficiency and the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism have been linked to negative symptoms in schizophrenia both independently and synergistically. This study examined the effect of folate supplementation on negative symptoms overall and in relation to MTHFR 677C>T genotype.

METHOD

Forty-six stable adult schizophrenia outpatients were enrolled and 32 were randomised, double-blind, in a parallel-group, twelve week add-on trial of folate 2mg/d or matching placebo. The primary outcome measure was change from baseline to week 12 on the modified SANS total score using a mixed-model analysis. In addition, we measured the effect of MTHFR genotype on treatment effects and on changes in serum folate by grouping participants with T/T genotype together with C/T genotype and comparing their interactions to patients with C/C genotype.

RESULTS

Twenty-eight participants completed the trial. Folate supplementation did not significantly affect negative symptoms compared to placebo across the entire cohort. However, there was a significant genotype×treatment effect on negative symptoms (F=7.13, df=1,39, p=0.01). In addition, MTHFR status significantly moderated the relationship between change in serum folate and change in negative symptoms: among participants with at least one copy of the T allele negative symptoms were more likely to improve with increased serum folate (p=0.03).

CONCLUSION

We did not detect a therapeutic benefit of folate supplementation in a sample of patients with residual negative symptoms. However, a possible association between genotypes associated with reduced MTHFR activity and benefit from folate supplementation should be investigated further.

Hearing impairment risk and interaction of folate metabolism related gene polymorphisms in an aging study

Background

Recent investigations demonstrated many genetic contributions to the development of human age-related hearing impairment (ARHI), however, reports of factors associated with a reduction in the ARHI risk are rare. Folate metabolism is essential for cellular functioning. Despite the extensive investigations regarding the roles of folate metabolism related gene polymorphisms in the pathophysiology of complex diseases, such as cancer, cardio-cerebrovascular disease, and atherosclerosis, little is known about the association with ARHI. The aim of this study is to investigate the effects of the methionine synthase (MTR) A2756G and methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphisms on the risk of hearing impairment in middle-aged and elderly Japanese.

Methods

Data were collected from community-dwelling Japanese adults aged 40-84 years who participated in the Longitudinal Study of Aging biennially between 1997 and 2008. We analyzed cumulative data (5,167 samples in accumulated total) using generalized estimating equations.

Results

The MTHFR 677T allele was significantly associated with a reduced risk of hearing impairment only when the subjects were wild-type homozygotes for MTR A2756G. The per-T allele odds ratio of MTHFR for the risk of developing hearing impairment was 0.7609 (95% CI: 0.6178-0.9372) in the MTR AA genotype. In addition, a subgroup analysis demonstrated that the favorable effect of the MTHFR 677T allele on the risk of developing hearing impairment was independent of folate and homocysteine level, whereas plasma total homocysteine level was independently associated with an increased risk of developing hearing impairment. The interactive effect of gene polymorphisms associated with folate metabolism may modify the risk of developing hearing impairment after middle age. These results contribute to the elucidation of the causes of ARHI.

Conclusions

The present study has found that the MTHFR 677T allele has a favorable effect on a risk of hearing impairment in the middle-aged and elderly population, only when the individuals were wild-type homozygotes for MTR A2756G.

Serum tartrate-resistant acid phosphatase isoform 5a (TRACP5a) as a potential risk marker in cardiovascular disease

OBJECTIVE

This study was undertaken to determine the association between serum tartrate-resistant acid phosphatase 5a (TRACP5a) and cardiovascular disease (CVD) risk.

METHODS

Four hundred patients were enrolled including, 291 asymptomatic subjects grouped by the number of traditional risk factors, 36 patients undergoing cardiac arteriography, 34 undergoing percutaneous cardiac intervention, and 39 with acute myocardial infarction. Serum was collected at baseline and, in arteriograpy and intervention groups, periodically for 1 week afterward. In addition to laboratory and clinical evaluation for risk assessment, serum TRACP5a, C-reactive protein (CRP) and interleukin-6 (IL-6) were determined.

RESULTS

All biomarkers rose with increasing CVD risk. Only serum TRACP5a, logCRP and cholesterol were elevated in symptomatic patients. Serum TRACP5a was higher in men and correlated with age, logCRP, logIL-6 and log-triglycerides, and in symptomatic patients, with the number of diseased coronary arteries. IL-6 and CRP showed acute phase responses, whereas TRACP5a did not change over 1 week after arteriography or intervention. After adjustment for all other variables and risk factors, TRACP5a and logCRP were the only biomarkers to associate with symptomatic disease. TRACP5a was more specific than CRP to predict myocardial infarction among all subjects.

CONCLUSIONS

Serum TRACP5a is a macrophage-derived inflammation marker associated with CVD risk, and with coronary vessel disease and its severity and may be a useful marker for screening and assessment of CVD risk.

Ischemic heart disease and stroke in relation to blood DNA methylation

BACKGROUND

Epigenetic features such as DNA hypomethylation have been associated with conditions related to cardiovascular risk. We evaluated whether lower blood DNA methylation in heavily methylated repetitive sequences predicts the risk of ischemic heart disease and stroke.

METHODS

We quantified blood DNA methylation of Long Interspersed Nucleotide Element-1 (LINE-1) repetitive elements through PCR-pyrosequencing in 712 elderly individuals from the Boston-area Normative Aging Study. We estimated risk-factor adjusted relative risks (RRs) for ischemic heart disease and stroke at baseline (242 prevalent cases), and during follow-up (44 new cases; median follow-up, 63 months), as well as subsequent mortality from ischemic heart disease (86 deaths; median follow-up, 75 months).

RESULTS

Blood LINE-1 hypomethylation was associated with baseline ischemic heart disease (RR = 2.1 [95% confidence interval = 1.2-4.0] for lowest vs. highest methylation quartile) and for stroke (2.5 [0.9-7.5]). Among participants free of baseline disease, individuals with methylation below the median also had higher risk of developing ischemic heart disease (4.0 [1.8-8.9]) or stroke (5.7 [0.8-39.5]). In the entire cohort, persons with methylation below the median had higher mortality from ischemic heart disease (3.3 [1.3-8.4]) and stroke (2.8 [0.6-14.3]). Total mortality was also increased (2.0 [1.2-3.3]). These results were confirmed in additional regression models using LINE-1 methylation as a continuous variable.

CONCLUSIONS

Subjects with prevalent IHD and stroke exhibited lower LINE-1 methylation. In longitudinal analyses, persons with lower LINE-1 methylation were at higher risk for incident ischemic heart disease and stroke, and for total mortality.

Folic Acid and vitamin B12 supplementation improves coronary flow reserve in elderly subjects with vitamin B12 deficiency

BACKGROUND AND AIMS

Major cardiovascular risk factors including hyperhomocysteinemia are frequently associated with decreased coronary flow reserve (CFR), an important physiological parameter of the coronary circulation. This study was designed to determine whether folate (5 mg) and vitamin B12 (500 μg) supplementation in elderly patients with vitamin B12 deficiency improved CFR, while reducing homocysteine levels.

METHODS

Forty-four patients aged >65 years showing serum vitamin B12 concentrations <180 mg/dL were randomized to take either oral folate (5 mg) plus vitamin B12 (500 μg) supplementation (n = 24) or placebo (n = 20) for 8 weeks. The study course consisted of two visits: visit 1 (pretreatment) included the baseline assessment of laboratory profile and CFR values with trans-thoracic Doppler echocardiography. Visit 2 was scheduled 8 weeks later to repeat CFR and laboratory tests after therapy.

RESULTS

In the treatment arm, oral supplementation with folate and vitamin B12 significantly improved total cholesterol, serum folate, serum vitamin B12, homocysteine, and insulin resistance. At 8 weeks, the treatment group had a significant increase from baseline in CFR values (baseline: 1.7 ± 0.2; postttreatment: 2.1 ± 0.2, p <0.001) that was not seen in the placebo group (baseline: 1.6 ± 0.2; posttreatment: 1.6 ± 0.2; P = ns).

CONCLUSIONS

In this study of elderly subjects with vitamin B12 deficiency, supplementation with folate and vitamin B12 was associated with a significant improvement in CFR values.

Methylxanthines and human health: epidemiological and experimental evidence

When considering methylxanthines and human health, it must be recognized that in many countries most caffeine is consumed as coffee. This is further confounded by the fact that coffee contains many bioactive substances in addition to caffeine; it is rich in phenols (quinides, chlorogenic acid, and lactones) and also has diterpenes (fatty acid esters), potassium, niacin, magnesium, and the vitamin B(3) precursor trigonelline. There is a paradox as consumption of either caffeine or caffeinated coffee results in a marked insulin resistance and yet habitual coffee consumption has repeatedly been reported to markedly reduce the risk for type 2 diabetes. There is strong evidence that caffeine reduces insulin sensitivity in skeletal muscle and this may be due to a combination of direct antagonism of A(1) receptors and indirectly β-adrenergic stimulation as a result of increased sympathetic activity. Caffeine may also induce reduced hepatic glucose output. With the exception of bone mineral, there is little evidence that caffeine impacts negatively on other health issues. Coffee does not increase the risk of cardiovascular diseases or cancers and there is some evidence suggesting a positive relationship for the former and for some cancers, particularly hepatic cancer.

Proximal tubule cell hypothesis for cardiorenal syndrome in diabetes

Incidence of cardiovascular disease (CVD) is remarkably high among patients with chronic kidney disease (CKD), even in the early microalbuminuric stages with normal glomerular filtration rates. Proximal tubule cells (PTCs) mediate metabolism and urinary excretion of vasculotoxic substances via apical and basolateral receptors and transporters. These cells also retrieve vasculoprotective substances from circulation or synthesize them for release into the circulation. PTCs are also involved in the uptake of sodium and phosphate, which are critical for hemodynamic regulation and maintaining the mineral balance, respectively. Dysregulation of PTC functions in CKD is likely to be associated with the development of CVD and is linked to the progression to end-stage renal disease. In particular, PTC dysfunction occurs early in diabetic nephropathy, a leading cause of CKD. It is therefore important to elucidate the mechanisms of PTC dysfunction to develop therapeutic strategies for treating cardiorenal syndrome in diabetes.

Vitamin B12 status, homocysteine and mortality amongst community-dwelling Irish elders

BACKGROUND

Vitamin B12 deficiency is associated with hyperhomocysteinaemia, which is associated with atherosclerosis and increased mortality. High levels of vitamin B12 have also been associated with increased mortality in certain patient populations.

AIMS

We examined vitamin B12 and homocysteine status and mortality rates in a population of Irish community-dwelling elders over a 3-year period.

METHODS

Prospective, community-based observational cohort study.

RESULTS

Subjects in the highest quartile of homocysteine had increased mortality rates (14.68 vs. 7.32%, relative risk 2.09). This relationship was attenuated when controlled for the presence or absence of a history of stroke or myocardial infarction. There was no relationship between vitamin B12 status and mortality during the observation period.

CONCLUSION

Vitamin B12 levels are not associated with death rates in Irish community-dwelling elders. Homocysteine levels are associated with mortality and may act via the mechanism of atherosclerotic disease.

Multivitamin use and the risk of myocardial infarction: a population-based cohort of Swedish women

BACKGROUND

Dietary supplements are widely used in industrialized countries.

OBJECTIVE

The objective was to examine the association between multivitamin use and myocardial infarction (MI) in a prospective, population-based cohort of women.

DESIGN

The study included 31,671 women with no history of cardiovascular disease (CVD) and 2262 women with a history of CVD aged 49-83 y from Sweden. Women completed a self-administered questionnaire in 1997 regarding dietary supplement use, diet, and lifestyle factors. Multivitamins were estimated to contain nutrients close to recommended daily allowances: vitamin A (0.9 mg), vitamin C (60 mg), vitamin D (5 μg), vitamin E (9 mg), thiamine (1.2 mg), riboflavin (1.4 mg), vitamin B-6 (1.8 mg), vitamin B-12 (3 μg), and folic acid (400 μg).

RESULTS

During an average of 10.2 y of follow-up, 932 MI cases were identified in the CVD-free group and 269 cases in the CVD group. In the CVD-free group, use of multivitamins only, compared with no use of supplements, was associated with a multivariable-adjusted hazard ratio (HR) of 0.73 (95% CI: 0.57, 0.93). The HR for multivitamin use together with other supplements was 0.70 (95% CI: 0.57, 0.87). The HR for use of supplements other than multivitamins was 0.93 (95% CI: 0.81, 1.08). The use of multivitamins for ≥5 y was associated with an HR of 0.59 (95% CI: 0.44, 0.80). In the CVD group, use of multivitamins alone or together with other supplements was not associated with MI.

CONCLUSIONS

The use of multivitamins was inversely associated with MI, especially long-term use among women with no CVD. Further prospective studies with detailed information on the content of preparations and the duration of use are needed to confirm or refute our findings.

Homocysteine thiolactone induces cardiac dysfunction: role of oxidative stress

This study investigates the cardiac functioning in male Wistar rats after treatments with methionine and homocysteine thiolactone (HcyT). The rats were distributed into 3 groups and treated for 8 weeks. Group I was the control (CO) group, given water, group II was treated with methionine, and group III with HcyT (100 mg/kg). Morphometric and functional cardiac parameters were evaluated by echocardiography. Superoxide dismutase (SOD), catalase, and glutathione S-transferase activities, chemiluminescence, thiobarbituric acid reactive substances, and immunocontent were measured in the myocardium. Hyperhomocysteinemiawas observed in rats submitted to the both treatments. The results showed diastolic function was compromised in HcyT group, seen by the increase of E/A (peak velocity of early (E) and late (A) diastolic filling) ratio, decrease in deceleration time of E wave and left ventricular isovolumic relaxation time. Myocardial performance index was increased in HcyT group and was found associated with increased SOD immunocontent. HcyT group demonstrated an increase in SOD, catalase, and glutatione S-transferase activity, and chemiluminescence and thiobarbituric acid reactive substances. Overall, these results indicated that HcyT induces a cardiac dysfunction and could be associated with oxidative stress increase in the myocardium.

Chronic treatment with cyclosporine affects systemic purinergic parameters, homocysteine levels and vascular disturbances in rats

Vascular disease is a major cause of morbidity and mortality among transplanted recipients and cyclosporine (CsA) treatment has been consistently implicated in this event. In this study we assessed total blood homocysteine levels (tHcy), ecto-nucleotidase activities and adenine nucleotide/nucleoside levels searching for parameters related to the mechanisms of vascular damage induced by chronic CsA treatment in non-transplanted rats. Thirty male Wistar rats were divided in three groups: control group treated with corn oil, CsA 5mg/kg and CsA 15 mg/kg, administered by daily gastric gavage during 8 weeks. CsA 15 mg/kg treatment increased blood levels of tHcy. Both CsA treatments (5mg/kg and 15 mg/kg) decreased adenine nucleotides hydrolysis by ecto-nucleotidases in serum, which negatively correlated with tHcy levels (r: -0.74, r: -0.63 and r: -0.63, p<0.004, for ATP, ADP and AMP, respectively). CsA 15mg/kg induced a statistically significant increase in ADP and decrease in adenosine (ADO) plasma levels compared to control group. THcy levels were positively correlated with plasma ADP levels and negatively correlated with ADO levels (r: 0.84, p<0.0001 and r: -0.68, p<0.0001, respectively). Rats under CsA 15 mg/kg treatment presented cell injury and inflammatory responses in the endothelium and intima layer of the aorta artery. In conclusion, blood ecto-nucleotidases activity, tHcy, and ADP and ADO levels may be implicated in vascular injury induced by CsA treatment.

Association of carotid plaque Lp-PLA(2) with macrophages and Chlamydia pneumoniae infection among patients at risk for stroke

Background

We previously showed that the burden of Chlamydia pneumoniae in carotid plaques was significantly associated with plaque interleukin (IL)-6, and serum IL-6 and C-reactive protein (CRP), suggesting that infected plaques contribute to systemic inflammatory markers in patients with stroke risk. Since lipoprotein-associated phospholipase A2 (Lp-PLA₂) mediates inflammation in atherosclerosis, we hypothesized that serum Lp-PLA₂ mass and activity levels and plaque Lp-PLA₂ may be influenced by plaque C. pneumoniae infection.

Methodology/Principal Findings

Forty-two patients underwent elective carotid endarterectomy. Tissue obtained at surgery was stained by immunohistochemistry for Lp-PLA₂ grade, macrophages, IL-6, C. pneumoniae and CD4+ and CD8+ cells. Serum Lp-PLA₂ activity and mass were measured using the colorimetric activity method (CAM™) and ELISA, respectively. Serum homocysteine levels were measured by HPLC. Eleven (26.2%) patients were symptomatic with transient ischemic attacks. There was no correlation between patient risk factors (smoking, coronary artery disease, elevated cholesterol, diabetes, obesity, hypertension and family history of genetic disorders) for atherosclerosis and serum levels or plaque grade for Lp-PLA₂. Plaque Lp-PLA₂ correlated with serum homocysteine levels (p = 0.013), plaque macrophages (p<0.01), and plaque C. pneumoniae (p<0.001), which predominantly infected macrophages, co-localizing with Lp-PLA₂.

Conclusions

The significant association of plaque Lp-PLA₂ with plaque macrophages and C. pneumoniae suggests an interactive role in accelerating inflammation in atherosclerosis. A possible mechanism for C. pneumoniae in the atherogenic process may involve infection of macrophages that induce Lp-PLA₂ production leading to upregulation of inflammatory mediators in plaque tissue. Additional in vitro and in vivo research will be needed to advance our understanding of specific C. pneumoniae and Lp-PLA₂ interactions in atherosclerosis.

Effect of homocysteine-lowering B vitamin treatment on angiographic progression of coronary artery disease: a Western Norway B Vitamin Intervention Trial (WENBIT) substudy

Total plasma homocysteine (tHcy) is an independent risk factor for coronary artery disease, and tHcy is lowered by B vitamins. To assess the effect of homocysteine-lowering B-vitamin treatment on angiographic progression of coronary artery disease, this substudy of the Western Norway B Vitamin Intervention Trial (WENBIT) included patients who had undergone percutaneous coronary intervention. The patients were randomized to daily oral treatment with folic acid, vitamin B(12), and vitamin B(6) or placebo in a 2 x 2 factorial design. The coronary angiograms obtained at baseline and follow-up were evaluated. The primary angiographic end points were the changes in minimum lumen diameter and diameter stenosis. A total of 348 subjects (288 men) with a mean +/- SD age of 60 +/- 10.2 years were followed up for a median of 10.5 months (twenty-fifth, seventy-fifth percentile 9.2, 11.8). The baseline median plasma tHcy level was 10.0 mumol/L (twenty-fifth, seventy-fifth percentile 8.1, 11.0), and treatment with folic acid/vitamin B(12) lowered the tHcy levels by 22%. At follow-up, we found 309 lesions with a significant decrease from baseline in the minimum lumen diameter of a mean of -0.16 +/- 0.4 mm and an increase in the diameter stenosis of 4.4 +/- 0.7%. Treatment with folic acid/vitamin B(12) or vitamin B(6) was not associated with a change in diameter stenosis or minimum lumen diameter. In a post hoc analysis, folic acid/vitamin B(12) treatment was significantly associated with rapid progression (odds ratio 1.84, 95% confidence interval 1.07 to 3.18). In conclusion, vitamin B treatment showed no beneficial effect on the angiographic progression of coronary artery disease, and the post hoc analyses suggested that folic acid/vitamin B(12) treatment might promote more rapid progression.

The efficacy of omega-3 fatty acid supplementation on plasma homocysteine and malondialdehyde levels of type 2 diabetic patients

BACKGROUND AND AIMS

Cardiovascular diseases are the major cause of mortality among diabetic patients. The concentration of malondialdehyde (MDA) and homocysteine is believed to play a role in cardiovascular diseases. Omega-3 fatty acid supplementation could be effective in some diabetes complications and in the control of the glycemic index. However, it may increase lipid peroxidation. The objective of this study was to determine the effect of omega-3 fatty acids on the concentration of homocysteine and MDA in diabetic patients.

METHODS AND RESULTS

A randomized double-blind, placebo-controlled clinical trial was conducted on 81 patients with type 2 diabetes. The patients were randomly assigned to either the treatment or control groups. Each subject received three capsules of omega-3 fatty acids or a placebo every day for a period of 2months. The two groups were similar in terms of body mass index and food intake. At the beginning of the study and after 2months of supplementation their levels of HbA(1)c, homocysteine, MDA, C-reactive protein (CRP), total cholesterol, LDL-cholesterol and fasting blood sugar (FBS) were determined. Due to omega-3 fatty acid supplementation, homocysteine was changed significantly in both treatment and control groups up to -3.10mumol/L and 0.10mumol/L respectively, and HbA(1)c decreased by 0.75% in the treatment group and increased by 0.26% in the control group. However, the changes in fasting blood sugar (FBS), malondialdehyde (MDA), C-reactive protein (CRP), total cholesterol and LDL-cholesterol levels were not significant.

CONCLUSION

The consumption of omega-3 fatty acid supplements (3g/day) for 2months decreases the levels of homocysteine in diabetic patients with no change in FBS, MDA and CRP levels.