Folate Improves Endothelial Function in Patients with Coronary Heart Disease

The Effect of Folic Acid Supplementation on Endothelial Function and Arterial Stiffness Markers in Adults: A Systematic Review and Meta-Analysis

Folic acid might improve endothelial function, but the results are inconclusive. This systematic review evaluated the effect of folic acid supplementation on endothelial parameters and arterial stiffness in adults. The study protocol was registered with the PROSPERO database (CRD42021290195). The PubMed, Web of Sciences, Cochrane and Scopus databases were searched to identify English-language randomised controlled trials of the effect of folate supplementation on arterial stiffness and endothelial function markers in adults. There were significant differences between the effect of folic acid and placebo on flow-mediated dilation (random-effects model, standardized mean differences (SMD): 0.888, 95% confidence interval (CI): 0.447, 1.329, p < 0.001) and monocyte chemotactic protein 1 (random-effects model, SMD: -1.364, 95% CI: -2.164, -0.563, p < 0.001), but there was no significant difference in the central pulse wave velocity (fixed-effects model, SMD: -0.069, 95% CI: -0.264, 0.125, p = 0.485) and peripheral pulse wave velocity (fixed-effects model, SMD: -0.093, 95% CI: -0.263, 0.077, p = 0.284). In conclusion, folic acid might have a favourable effect on endothelial function but may not affect arterial stiffness. Further studies are needed to confirm these results.

The effects of folic acid supplementation on endothelial function in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND

Endothelial dysfunction serves as an early marker for the risk of cardiovascular disease (CVD); therefore, it is an attractive site of therapeutic interventions to reduce the risk of CVD. This study was conducted to investigate the effect of folic acid supplementation on endothelial function markers in randomized controlled trials (RCTs).

METHODS

PubMed, ISI web of science, and Scopus databases were searched up to July 2022 for detecting eligible studies. A random-effects model was used for meta-analysis, and linear Meta-regression and non-linear dose-response analysis were performed to assess whether the effect of folic acid supplementation was affected by the dose and duration of intervention. Cochrane tools were also used to assess the risk of bias in the included studies.

RESULTS

Twenty-one studies, including 2025 participants (1010 cases and 1015 controls), were included in the present meta-analysis. Folic acid supplementation significantly affected the percentage of flow-mediated dilation (FMD%) (WMD: 2.59%; 95% CI: 1.51, 3.67; P < 0.001) and flow-mediated dilation (FMD) (WMD: 24.38 μm; 95% CI: 3.08, 45.68; P = 0.025), but not end-diastolic diameter (EDD) (WMD: 0.21 mm; 95% CI: - 0.09, 0.52; P = 0.176), and intercellular adhesion molecule (ICAM) (WMD: 0.18 ng/ml; 95% CI: - 10.02, 13.81; P = 0.755).

CONCLUSIONS

These findings suggest that folic acid supplementation may improve endothelial function by increasing FMD and FMD% levels.

TRIAL REGISTRATION

PROSPERO registration cod: CRD42021289744.

Coronary Artery Disease and Endothelial Dysfunction: Novel Diagnostic and Therapeutic Approaches

Coronary artery disease is the leading cause of morbidity and mortality worldwide. The most common pathophysiologic substrate is atherosclerosis which is an inflammatory procedure that starts at childhood and develops throughout life. Endothelial dysfunction is associated with the initiation and progression of atherosclerosis and is characterized by the impaired production of nitric oxide. In general, endothelial dysfunction is linked to poor cardiovascular prognosis and different methods, both invasive and non-invasive, have been developed for its evaluation. Ultrasound evaluation of flow mediated dilatation of the branchial artery is the most commonly used method to assessed endothelial function while intracoronary administration of vasoactive agents may be also be used to test directly endothelial properties of the coronary vasculature. Endothelial dysfunction has also been the subject of therapeutic interventions. This review article summarizes the knowledge about evaluation of endothelial function in acute coronary syndromes and stable coronary artery disease and demonstrates the current therapeutic approaches against endothelial dysfunction.

Correlation analysis between 25-hydroxyvitamin D3, vitamin B12 and vitamin C and endothelial function of patients with CHD

The aim of the study was to investigate the correlation between levels of 25-hydroxyvitamin D3, vitamin B12 and C and endothelial function of patients with coronary heart disease (CHD). Forty patients with CHD diagnosed in Shanghai Tenth People's Hospital from May 2016 to April 2017 were selected as the observation group. A total of 45 healthy individuals were selected as the control group. The participants included 54 males and 31 females. General information was collected. Peripheral serum biochemical indicators, levels of 25-hydroxyvitamin D3, vitamin B12 and C, homocysteine (Hcy), nitric oxide (NO) and endothelial NOS (eNOS) were measured. Arterial lesions detected by coronary angiography were recorded and indexes of observation and control group were compared for the correlation analysis. A proportion of hypertensive patients and their body mass index (BMI) were significantly higher in the observation than in the control group (P<0.05). Levels of 25-hydroxyvitamin D3, vitamin B12 and C in peripheral blood of observation were significantly lower than those of the control group (P<0.05). Compared with the control group, incidence of single-branch lesion and non-lesion rate were significantly lower, but incidence of double- and triple-branch lesions were significantly higher in observation than in control group (P<0.05). In addition, the level of Hcy in the observation group was higher than that in the control group, but levels of NO and eNOS in observation were significantly lower than those in control group (P<0.05. The correlation analysis revealed that 25-hydroxyvitamin D3 (r=0.792, P<0.01), vitamin B12 (r=0.635, P<0.01) and vitamin C (r=0.703, P<0.01) were negatively correlated with serum NO level. Thus, hypertension, BMI, 25-hydroxyvitamin D3, vitamin B12 and C have independent predictive value for coronary endothelial dysfunction (P<0.05). In conclusion, serum levels of 25-hydroxyvitamin D3, vitamin B12 and C are closely related to vascular endothelial dysfunction in patients with CHD and affect the severity of vascular endothelial dysfunction in patients with CHD.

Cerebrovascular and cognitive benefits of high-oleic peanut consumption in healthy overweight middle-aged adults

OBJECTIVE

Peanuts contain bioactive nutrients beneficial for vascular function. This study investigated whether consumption of unsalted peanuts (with skins) would enhance cerebrovascular perfusion and cognitive performance.

METHOD

In a randomized crossover trial, 61 volunteers (29 males/32 females, 65 ± 7 years, BMI 31 ± 4 kg/m²) consumed their habitual diet ± high-oleic peanuts (56-84 g/day), each for 12 weeks. Nutrient intakes, vascular and cognitive function were assessed at baseline and at the end of each 12-week phase. Differences between the ends of each phase were compared by general linear repeated measures ANOVA controlling for baseline. Pearson's correlation analyses determined relationships between differences in cerebrovascular reactivity (CVR) and cognitive function.

RESULTS

Intakes of bioactive nutrients increased during the peanut phase. CVR was 5% greater in the left middle cerebral artery (MCA) and 7% greater in the right MCA. Small artery elasticity was 10% greater after peanut consumption; large artery elasticity and blood pressure did not differ between phases. Measures of short-term memory, verbal fluency, and processing speed were also higher following the peanut phase; other cognitive measures did not change. Differences in CVR in the left MCA correlated with differences in delayed memory and recognition.

DISCUSSION

Regular peanut consumption improved cerebrovascular and cognitive function; increased intakes of bioactive nutrients may have mediated these improvements. This clinical trial was registered with the Australian Clinical Trials Registry (ACTRN 12612000192886).

The role of homocysteine-lowering B-vitamins in the primary prevention of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality in the Western world. The effort of research should aim at the primary prevention of CVD. Alongside statin therapy, which is maintained to be an effective method of CVD prevention, there are alternative methods such as vitamin B substitution therapy with folic acid (FA), and vitamins B12 and B6 . B-vitamins may inhibit atherogenesis by decreasing the plasma level of homocysteine (Hcy)-a suspected etiological factor for atherosclerosis-and by other mechanisms, primarily through their antioxidant properties. Although Hcy-lowering vitamin trials have failed to demonstrate beneficial effects of B-vitamins in the prevention of CVD, a meta-analysis and stratification of a number of large vitamin trials have suggested their effectiveness in cardiovascular prevention (CVP) in some aspects. Furthermore, interpretation of the results from these large vitamin trials has been troubled by statin/aspirin therapy, which was applied along with the vitamin substitution, and FA fortification, both of which obscured the separate effects of vitamins in CVP. Recent research results have accentuated a new approach to vitamin therapy for CVP. Studies undertaken with the aim of primary prevention have shown that vitamin B substitution may be effective in the primary prevention of CVD and may also be an option in the secondary prevention of disease if statin therapy is accompanied by serious adverse effects. Further investigations are needed to determine the validity of vitamin substitution therapy before its introduction in the protocol of CVD prevention.

Short- and long-term treatment with folic acid suppresses thrombus formation in atherogenic mice in vivo

In the present study, we examined the effects of short- and long-term treatment with folic acid (FA) on thrombus formation in vivo in atherogenic mice to explore a novel agent for the prevention of atherothrombotic disease. Apolipoprotein E and low-density lipoprotein receptor double deficient (ApoE(-/-)LDLR(-/-)) mice were orally administrated a single bolus of FA (20mg/kg) or fed an atherogenic diet with or without FA (0.02, 0.5, and 1.5mg/kg) for 12 weeks. Thrombus formation and endothelial function were assessed in vivo using the He-Ne laser-induced carotid artery thrombus formation test and the flow-mediated vasodilation method. Platelet reactivity was assessed ex vivo using haemostatometry. Short-term treatment with FA markedly increased plasma folate levels and significantly suppressed laser-induced thrombus formation in apoE(-/-)LDLR(-/-) mice. Short-term treatment with FA suppressed platelet reactivity in apoE(-/-)LDLR(-/-) mice, but FA treatment did not affect endothelial function or plasma homocysteine levels. Long-term treatment with FA increased plasma folate levels dose-dependently. Thrombus formation and endothelial dysfunction were suppressed by treatment with 0.5 and 1.5mg/kg of FA, respectively, but not with 0.02mg/kg of FA, whereas platelet reactivity was not altered by treatment with any dose of FA. Long-term treatment with all doses of FA decreased the plasma homocysteine levels in apoE(-/-)LDLR(-/-) mice, although this result was not consistent with its anti-thrombotic action. In conclusion, our data showed that short- and long-term treatment with FA could suppress in vivo thrombus formation in an atherogenic setting, independent of its hypohomocysteinemic action.

Efficacy of folic acid supplementation on endothelial function and plasma homocysteine concentration in coronary artery disease: A meta-analysis of randomized controlled trials

The aim of the present study was to conduct an updated meta-analysis of relevant randomized controlled trials (RCTs) in order to estimate the effect of folic acid supplementation on endothelial function and the concentration of plasma homocysteine in patients with coronary artery disease (CAD). An extensive search of PubMed was conducted to identify RCTs that compared folic acid with placebo therapy. The mean difference (MD) and 95% confidence interval (CI) were used as a measure of the correlation between folic acid supplementation and endothelial function/plasma homocysteine concentration. Of the 377 patients included in this analysis, 191 patients underwent folic acid supplementation and 186 individuals underwent placebo treatment. Compared with the use of a placebo, folic acid supplementation alone exhibited significant efficacy on increasing flow-mediated dilation (FMD; MD, 57.72 μm; 95% CI, 50.14–65.31; P<0.05) and lowering the concentration of plasma homocysteine (MD, −3.66 μmol/l; 95% CI, −5.44–−1.87; P<0.05; I², 87%). There was no significant change in the response to end diastolic diameter, glyceryl-trinitrate diameter, heart rate, baseline and peak hyperemic flow and systolic and diastolic blood pressure between the folic acid and placebo groups (P>0.05). Therefore, the meta-analysis indicated that 5 mg folic acid daily supplementation for >4 weeks significantly improved FMD and lowered the concentration of plasma homocysteine in patients with CAD. However, more RCTs are required in order to confirm these observations.

Hydrogen sulphide-related thiol metabolism and nutrigenetics in relation to hypertension in an elderly population

Hydrogen sulphide (H(2)S) is a gaseous signalling molecule that regulates blood flow and pressure. It is synthesised from cysteine via cystathionine β-synthase and cystathionine γ-lyase. We examined whether thiol precursors of H(2)S, transsulphuration pathway gene variants (CBS-844ins68 and CTH-G1364T) and key B-vitamin cofactors might be critical determinants of hypertension in an elderly Australian population. An elderly Australian retirement village population (n = 228; age 65-96 years, 91 males and 137 females) was assessed for the prevalence of two transsulphuration pathway-related variant genes associated with cysteine synthesis and hence H(2)S production. Thiols were determined by HPLC, genotypes by PCR and dietary intake by food frequency questionnaire. Homocysteine levels were statistically higher in the hypertensive phenotype (p = 0.0399), but there was no difference for cysteine or glutathione. Using nominal logistic regression, cysteine, CTH-G1364T genotype, dietary synthetic folate and vitamin B(6) predicted clinical phenotype (determined as above/below 140/90 mm Hg) and then only in female subjects (p = 0.0239, 0.0178, 0.0249 and 0.0371, respectively). Least-squares regression supports cysteine being highly inversely predictive of diastolic blood pressure: p and r (2) values <0.0001 and 0.082; 0.0409 and 0.046; and <0.0001 and 0.113 for all subjects, males and females, respectively. Additionally, CTH-G1364T genotype predicts diastolic blood pressure in males (p = 0.0217; r (2) = 0.083), but contrasts with observations for females. Overall, analyses, including stepwise regression, suggest cysteine, dietary natural and synthetic folate, vitamins B(6) and B(12), and both genetic variants (CTH-C1364T and CBS-844ins68) are all aetiologically relevant in the regulation of blood pressure. Hydrogen sulphide is a vasorelaxant gasotransmitter with characteristics similar to nitric oxide. Cysteine and the G1364T and 844ins68 variants of the cystathionine γ-lyase and cystathionine β-synthase genes, respectively, are the biological determinants of H(2)S synthesis, and all three are shown here to influence the hypertensive phenotype. Additionally, B-vitamin cofactors for these three enzymes may also be important determinants of blood pressure.

DNA damage in children and adolescents with cardiovascular disease risk factors

The risk of developing cardiovascular disease (CVD) is related to lifestyle (e.g. diet, physical activity and smoking) as well as to genetic factors. This study aimed at evaluating the association between CVD risk factors and DNA damage levels in children and adolescents. Anthropometry, diet and serum CVD risk factors were evaluated by standard procedures. DNA damage levels were accessed by the comet assay (Single cell gel electrophoresis; SCGE) and cytokinesis-blocked micronucleus (CBMN) assays in leukocytes. A total of 34 children and adolescents selected from a population sample were divided into three groups according to their level of CVD risk. Moderate and high CVD risk subjects showed significantly higher body fat and serum CVD risk markers than low risk subjects (P<0.05). High risk subjects also showed a significant increase in DNA damage, which was higher than that provided by low and moderate risk subjects according to SCGE, but not according to the CBMN assay. Vitamin C intake was inversely correlated with DNA damage by SCGE, and micronucleus (MN) was inversely correlated with folate intake. The present results indicate an increase in DNA damage that may be a consequence of oxidative stress in young individuals with risk factors for CVD, indicating that the DNA damage level can aid in evaluating the risk of CVD.

Oxidative stress and endothelial dysfunction: therapeutic implications

In a previous issue of Annals of Medicine, we presented evidence in support of the concept that an abnormally increased production of reactive oxygen species plays a central role in the genesis and progression of cardiovascular disease. While a number of preclinical lines of evidence support this concept, and despite the results of many studies suggesting a beneficial impact of antioxidant drugs on endothelial function, large clinical trials have failed to demonstrate a benefit of antioxidants on cardiovascular outcomes. Studies exploring the possibility that classical antioxidants such as vitamin C, vitamin E, selenium, or folic acid may improve the prognosis of patients with cardiac disease have substantially reported neutral-and occasionally negative-results. In contrast, medications such as statins, ACE inhibitors, certain β-blockers, or angiotensin I receptor blockers, which possess indirect 'ancillary' antioxidant properties, have been associated with beneficial effects in both preclinical studies and large clinical trials. The reasons for the failure of the 'direct' approach to antioxidant therapy, and for the success of the therapy with these drugs, are discussed in the present review.

Homocysteine-lowering therapy: a role in stroke prevention?

On the basis of the results of several recent clinical trials, many researchers have concluded that vitamin therapy designed to lower total homocysteine concentrations is not effective in reducing the risk of cardiovascular events. However, whereas almost all myocardial infarctions are due to plaque rupture, stroke has many more pathophysiological mechanisms, and thrombosis-which is increased by raised total homocysteine concentrations-has an important role in many of these processes. Thus, stroke and myocardial infarction could respond differently to vitamin therapy. A detailed assessment of the results of the recent HOPE-2 trial and a reanalysis of the VISP trial restricted to patients capable of responding to vitamin therapy suggest that higher doses of vitamin B12 and perhaps new approaches to lowering total homocysteine besides routine vitamin therapy with folate, vitamin B6, and vitamin B12 could reduce the risk of stroke. Thus, therapy to lower homocysteine could still help to prevent stroke, if not other vascular outcomes.

Simultaneous quantification of homocysteine and folate in human serum or plasma using liquid chromatography/tandem mass spectrometry

A unified extraction and quantification procedure based on stable isotope-dilution liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed for the simultaneous determination of total homocysteine and folate (5-methyltetrahydrofolic acid and folic acid) levels in human serum and plasma. This is the first report documenting the simultaneous extraction and quantification of these structurally dissimilar analytes. Analytes are quantitatively isolated from samples (500 microL) prior to LC/MS/MS analysis using a two-step stabilization process combined with C18 solid-phase extraction. The method exhibits excellent linearity over 4 orders of magnitude for each analyte. Measurement repeatability (RSD, N = 2) ranged from 0.3% to 3% for all analytes over 1 day of analysis. Total method variability (RSD, N = 6) ranged from 0.7% to 10% for all analytes over three independent days of analysis. The accuracy and practical applicability of the method were demonstrated by applying the method to the quantitative determination of each analyte in a new NIST serum Standard Reference Material (NIST SRM 1955 Homocysteine and Folate in Frozen Human Serum) and in a small subset of normal donor plasma samples.

Influence of specific nutrients on progression of atherosclerosis, vascular function, haemostasis and inflammation in coronary heart disease patients: a systematic review

Epidemiological evidence suggests that the diet influences CHD risk, although the protective effects of dietary intervention for patients in diseased states has gained less attention. Secondary care prevention strategies for patients often involves drug therapy that is expensive and can result in undesirable side effects. Therefore, it is potentially beneficial to utilise other strategies, such as diet, in the management of CHD. A systematic review was conducted to examine the effects of specific nutrients on progression of atherosclerosis, vascular function, haemostasis and inflammation in CHD patients. Results show substantial evidence for the efficacy ofn–3 oils in reducing cardiovascular mortality and one mechanism may be related to the stabilisation of vulnerable atherosclerotic plaques, although the effects on progression of atherosclerosis, haemostatic activity and vascular inflammation remain equivocal. Promising data also exist for the efficacy of flavonoid-rich foods for improving endothelial function, although strong clinical endpoint evidence is lacking. The variation in the efficacy of certain nutrients in CHD patients may be explained by genetics, existing risk factors, psychosocial factors and methodological issues, although these are often not adequately taken into consideration. We conclude that there is a need to undertake more appropriately designed trials in specific clinical populations, controlling for additional lifestyle and risk factors, examining potential interactions with medications, and also establishing methods to increase compliance to dietary recommendations before specific nutrients can be widely prescribed for secondary prevention. Future research should also utilise techniques that provide a direct measure of atherosclerosis.

Synergy of genes and nutrients: the case of homocysteine

PURPOSE OF REVIEW

Folic acid is now considered an important functional food component: it lowers potentially toxic homocysteine, prevents birth defects and modulates the risk of several cancers. The complexity of interactions involved, however, means we still have much to learn about the role of folate and homocysteine in both health and disease.

RECENT FINDINGS

This review examines the emergence of homocysteine as a public health issue, and places this in context by exploring recent developments in the field of homocysteine as a vasculo, neuro and embryotoxic thiol. The paper also examines the homocysteine nexus in relation to mood disorders and cancer. It ends with an assessment of the issues associated with government-mandated folate fortification.

SUMMARY

Folate fortification as a population measure may mask B12 deficiency, affect antiepileptic drug seizure control, and influence the genetic selection of a potentially deleterious genotype, albeit over a number of generations. It is likely that only large studies with a comprehensive battery of endpoints that fully address the complexity of nutrient-gene and gene-gene interactions will be able to answer all the necessary questions fully.

G80A reduced folate carrier SNP influences the absorption and cellular translocation of dietary folate and its association with blood pressure in an elderly population

The functional consequences of the G80A RFC SNP on the expressed reduced folate carrier protein were evaluated by looking at the relationship between intake of folate, plasma folate and cellular stores of the vitamin. The effect on homocysteine was also examined. Homocysteine is a thiol that is known to be inversely associated with folate, and which is considered to be both thrombo- and athrogenic. At high levels, homocysteine may also interfere with nitric oxide mediated vasodilation, cause oxidative injury to, and proliferation of the vascular endothelium, and alter the elastic properties of the vascular wall, contributing to increased blood pressure. Participants (119; 52 male, 67 female) from a NSW retirement village were assessed. Independent of gender, the assimilation of folate from dietary sources into red cells showed a significant association for GG (r=0.399; p=0.022) and GA (r=0.564; p<0.0001) subjects, but not homozygous recessive (AA) individuals (r=0.223; p=0.236). The same genotype based pattern of significance was shown for the association between dietary folate and plasma folate (GG: r=0.524; p=0.002, GA: r=0.408; p=0.002). No genotype-related pattern of significance was shown for the association between dietary folate and homocysteine. When examined by gender, some differences were apparent; one-way ANOVA showed that genotype influenced diastolic blood pressure in males (p=0.019), while only females showed a significant correlation between dietary folate and blood pressure within specific genotypes (Systolic pressure GA: r=-0.372; p=0.025, carriage of A: r=0.-0.357; p=0.011. Diastolic pressure GA: r=-0.355; p=0.034, carriage of A: r=0.-0.310; p=0.029). The G80A RFC SNP had an impact on the absorption and cellular translocation of dietary folate and its association with blood pressure in an elderly population.

G80A reduced folate carrier SNP modulates cellular uptake of folate and affords protection against thrombosis via a non homocysteine related mechanism

Dietary folate is absorbed in the jejunum by the 'Reduced Folate Carrier' binding protein. This protein also sequesters extracellular folate for use by many cells in the body. As several biosynthetic pathways require folate for critical life processes, any change in the properties of this protein could lower folate bioavailability, cellular levels of the vitamin, and thus influence health. Since folate lowers thrombogenic homocysteine, we examined the prevalence of a common genetic polymorphism encoding the Reduced Folate Carrier (G80A RFC) to see if it acts as a risk factor for thrombotic vascular disease via an effect on homocysteine disposition in a cohort of 156 patients. The odds ratio indicates a significant protective effect of the mutant A allele against thrombosis: OR = 0.56(95% CI; 0.34-0.92). chi2; p = 0.022 (Yates corrected chi2; p = 0.031). The polymorphism had no impact on homocysteine, but did increase the level of extracellular to intracellular folate as might be predicted by the biological role of the expressed protein. This, and not homocysteine level, may be what affords protection against thrombosis.

Randomized controlled trial of homocysteine-lowering vitamin treatment in elderly patients with vascular disease

BACKGROUND

Homocysteine is an independent risk factor for vascular disease and is associated with dementia in older people. Potential mechanisms include altered endothelial and hemostatic function.

OBJECTIVE

We aimed to determine the effects of folic acid plus vitamin B-12, riboflavin, and vitamin B-6 on homocysteine and cognitive function.

DESIGN

This was a factorial 2 x 2 x 2, randomized, placebo-controlled, double-blind study with 3 active treatments: folic acid (2.5 mg) plus vitamin B-12 (500 microg), vitamin B-6 (25 mg), and riboflavin (25 mg). We studied 185 patients aged >or=65 y with ischemic vascular disease. Outcome measures included plasma homocysteine, fibrinogen, and von Willebrand factor at 3 mo and cognitive change (determined with the use of the Letter Digit Coding Test and on the basis of the Telephone Interview of Cognitive Status) after 1 y.

RESULTS

The mean (+/-SD) baseline plasma homocysteine concentration was 16.5 +/- 6.4 micromol/L. This value was 5.0 (95% CI: 3.8, 6.2) micromol/L lower in patients given folic acid plus vitamin B-12 than in patients not given folic acid plus vitamin B-12 but did not change significantly with vitamin B-6 or riboflavin treatment. Homocysteine lowering with folic acid plus vitamin B-12 had no significant effect, relative to the 2 other treatments, on fibrinogen, von Willebrand factor, or cognitive performance as measured by the Letter Digit Coding Test (mean change: -1; 95% CI: -2.3, 1.4) and the Telephone Interview of Cognitive Status (-0.7; 95% CI: -1.7, 0.4).

CONCLUSION

Oral folic acid plus vitamin B-12 decreased homocysteine concentrations in elderly patients with vascular disease but was not associated with statistically significant beneficial effects on cognitive function over the short or medium term.

Homocysteine triggers mucosal microvascular activation in inflammatory bowel disease

OBJECTIVES

Increased homocysteine contributes to the pathophysiology of several chronic inflammatory diseases. Whether homocysteine could participate in mucosal inflammation in inflammatory bowel disease (IBD) has not been explored yet. Our aims were to study the levels of plasma and mucosal homocysteine in IBD patients and to assess whether homocysteine can trigger an inflammatory reaction on human intestinal microvascular endothelial cells (HIMECs).

METHODS

Homocysteine was measured in the plasma, mucosal biopsy, and lamina propria mononuclear cell (LPMC) supernatants from normal and IBD subjects. HIMEC were cultured in presence of homocysteine, TNF-alpha, or folic acid, alone or in combination. Expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular cell adhesion molecule 1 was measured by flow cytometry and monocyte chemoattractant protein-1 (MCP-1) production by ELISA. Phosphorylation of p38 and p42/44 was assessed by immunoblot in HIMEC extracts. T-cell- and monocyte-HIMEC adhesion assays were used to evaluate the impact of homocysteine on leukocyte adhesion to intestinal endothelial cells.

RESULTS

Patients with IBD displayed significantly higher homocysteine plasma and mucosal levels than control subjects. IBD-derived LPMC released higher homocysteine than control-derived LPMC. Treatment of HIMEC with homocysteine, and synergistically with the combination of TNF-alpha and homocysteine, triggered HIMEC inflammation, resulting in VCAM-1 up-regulation, MCP-1 production, and p38 phosphorylation. These events lead to an increased capacity of HIMEC to adhere T- and monocyte cells and were blocked by folic acid treatment.

CONCLUSIONS

Homocysteine is increased in both the mucosa and plasma of patients with Crohn's disease and ulcerative colitis and contributes to the inflammatory state of the mucosal IBD endothelium. Therefore, homocysteine could play a proinflammatory role in IBD, which can be efficiently targeted by folic acid supplementation.