No effect of homocysteine-lowering therapy on vascular inflammation and haemostasis in peripheral arterial occlusive disease

Effect of Combined Treatment With Folic Acid, Vitamin B6, and Vitamin B12 on Plasma Biomarkers of Inflammation and Endothelial Dysfunction in Women

Background

The aim of this study was to determine whether reducing plasma homocysteine concentrations with long‐term, combined treatment with folic acid, vitamin B₆, and vitamin B₁₂ alters plasma biomarkers of inflammation and endothelial dysfunction in women at increased risk of cardiovascular disease.

Methods and Results

We conducted a blood substudy of 300 treatment‐adherent participants (150 in the active treatment group, 150 in the placebo group) in the WAFACS (Women's Antioxidant and Folic Acid Cardiovascular Study), a randomized, double‐blind, placebo‐controlled trial testing a daily combination of folic acid (2.5 mg), vitamin B₆ (50 mg), vitamin B₁₂ (1 mg), or matching placebo, in cardiovascular disease prevention among women at increased risk of cardiovascular disease. Plasma concentration of 3 biomarkers of inflammation (C‐reactive protein, interleukin‐6, and fibrinogen) and a biomarker of endothelial dysfunction (intercellular adhesion molecule 1) were measured at baseline and at the end of treatment and follow‐up. After 7.3 years of combined treatment with folic acid, vitamin B₆, and vitamin B₁₂, homocysteine concentrations were reduced by 18% in the active treatment group as compared with the placebo group (P<0.001). However, there was no difference between treatment groups in change in blood concentration from baseline to follow‐up for C‐reactive protein (P=0.77), interleukin‐6 (P=0.91), intercellular adhesion molecule 1 (P=0.38), or fibrinogen (P=0.68).

Conclusions

These findings indicate that long‐term, combined treatment with folic acid, vitamin B₆, and vitamin B₁₂ lowers homocysteine concentrations, but does not alter major biomarkers of vascular inflammation, consistent with the lack of clinical cardiovascular disease benefit in the trial.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000541.

Biomarkers of one-carbon metabolism are associated with biomarkers of inflammation in women

Folate-mediated one-carbon metabolism is essential for DNA synthesis, repair, and methylation. Perturbations in one-carbon metabolism have been implicated in increased risk of some cancers and may also affect inflammatory processes. We investigated these interrelated pathways to understand their relation. The objective was to explore associations between inflammation and biomarkers of nutritional status and one-carbon metabolism. In a cross-sectional study in 1976 women selected from the Women's Health Initiative Observational Study, plasma vitamin B-6 [pyridoxal-5'-phosphate (PLP)], plasma vitamin B-12, plasma folate, and RBC folate were measured as nutritional biomarkers; serum C-reactive protein (CRP) and serum amyloid A (SAA) were measured as biomarkers of inflammation; and homocysteine and cysteine were measured as integrated biomarkers of one-carbon metabolism. Student's t, chi-square, and Spearman rank correlations, along with multiple linear regressions, were used to explore relations between biomarkers; additionally, we tested stratification by folic acid fortification period and multivitamin use. With the use of univariate analysis, plasma PLP was the only nutritional biomarker that was modestly significantly correlated with serum CRP and SAA (ρ = -0.22 and -0.12, respectively; P < 0.0001). Homocysteine (μmol/L) showed significant inverse correlations with all nutritional biomarkers (ranging from ρ = -0.30 to ρ = -0.46; all P < 0.0001). With the use of multiple linear regression, plasma PLP, RBC folate, homocysteine, and cysteine were identified as independent predictors of CRP; and PLP, vitamin B-12, RBC folate, and homocysteine were identified as predictors of SAA. When stratified by folic acid fortification period, nutrition-homocysteine correlations were generally weaker in the postfortification period, whereas associations between plasma PLP and serum CRP increased. Biomarkers of inflammation are associated with PLP, RBC folate, and homocysteine in women. The connection between the pathways needs to be further investigated and causality established. The trial is registered at clinicaltrials.gov as NCT00000611.

Tratamento dietético da hiper-homocisteinemia na doença arterial periférica

A homocisteína está envolvida na gênese da aterosclerose e, assim, é considerada um importante e prevalente fator de risco na doença arterial periférica. O estado nutricional vitamínico deficiente, em especial do folato, é a principal causa de hiper-homocisteinemia nesses casos. Embora ainda não haja consenso sobre a dose exata e a forma de utilização do folato em suplementos e sobre adequação alimentar ou fortificação de cereais para o tratamento da hiper-homocisteinemia, diversos estudos realizados em pacientes com doença vascular periférica mostraram que o folato, isoladamente, pode reduzir as concentrações de homocisteína, bem como a concentração de alguns marcadores biológicos do processo de aterosclerose. No entanto, estudos recentes não comprovaram esse benefício sobre o processo inflamatório associado à hiper-homocisteinemia. Desta forma, embora a utilização isolada do folato seja uma terapêutica custo-efetiva no controle da hiper-homocisteinemia, seu impacto na evolução das doenças arteriais ainda persiste inconclusivo. Esta revisão abordará os efeitos obtidos com as diversas formas de utilização do folato no tratamento da hiper-homocisteinemia.

Randomized clinical trial of folate supplementation in patients with peripheral arterial disease

BACKGROUND

The aim was to determine whether folate supplementation improved arterial function in patients with peripheral arterial disease (PAD).

METHODS

Individuals with PAD were randomly assigned to receive 400 microg folic acid (45 patients) or 5-methyltetrahydrofolate (5-MTHF) (48) daily, or placebo (40) for 16 weeks. Primary endpoints were changes in plasma total homocysteine (tHcy), ankle : brachial pressure index (ABPI) and pulse wave velocity (PWV). Secondary outcomes were changes in plasma inflammatory markers.

RESULTS

Plasma tHcy was significantly reduced in folic acid and 5-MTHF groups compared with controls: median difference: - 2.12 (95 per cent confidence interval - 3.70 to - 0.75) micromol/l (P = 0.002) and - 2.07 (-3.48 to - 0.54) micromol/l (P = 0.007) respectively. ABPI improved significantly: median difference 0.07 (0.04 to 0.11) (P < 0.001) and 0.05 (0.01 to 0.10) (P = 0.009) respectively. Brachial-knee PWV (bk-PWV) decreased significantly in individuals receiving 5-MTHF and tended to be reduced in those taking folic acid compared with controls: median difference: - 1.10 (-2.20 to - 0.20) m/s (P = 0.011) and - 0.90 (-2.10 to 0.00) m/s (P = 0.051) respectively. Plasma levels of inflammatory markers were not affected.

CONCLUSION

Folate administration reduced plasma homocysteine, and slightly improved ABPI and bk-PWV.

The Influence of Total Plasma Homocysteine and Traditional Atherosclerotic Risk Factors on Degree of Abdominal Aortic Aneurysm Tissue Inflammation

Objective: Modulating effects of genetic and environmental risk factors on severity of human abdominal aortic aneurysm (AAA) tissue inflammation remain unclear. We investigated the influence of total plasma homocysteine (tHcy) and traditional atherosclerotic risk factors (ARF) on degree of AAA tissue inflammation. Methods: Aneurysm specimens were obtained from 89 male patients aged 52 to 83 years, underwent asymptomatic not ruptured AAA (mean diameter 5.5 cm) open repair and graded for degree of histologic inflammation. Multivariate analysis was used to determine the association of tHcy and ARF, with degree of inflammation. Results: Current cigarette smoking, odds ratio (OR) 4.4, 95% confidence interval 1.3 to 15.2, P = .01 and no other ARF, neither tHcy levels OR 0.9 (0.9-1.02), P = .2 were associated with high-grade tissue inflammation. Conclusion: These results provide evidence against a major effect of tHcy levels on AAA tissue inflammation, while current cigarette smoking is a significant modulating factor.

Dietary choline and betaine intakes in relation to concentrations of inflammatory markers in healthy adults: the ATTICA study

BACKGROUND

Choline and betaine are found in a variety of plant and animal foods and were recently shown to be associated with decreased homocysteine concentrations.

OBJECTIVE

The scope of this work was to investigate the associations between dietary choline and betaine consumption and various markers of low-grade systemic inflammation.

DESIGN

Under the context of a cross-sectional survey that enrolled 1514 men (18-87 y of age) and 1528 women (18-89 y of age) with no history of cardiovascular disease (the ATTICA Study), fasting blood samples were collected and inflammatory markers were measured. Dietary habits were evaluated with a validated food-frequency questionnaire, and the intakes of choline and betaine were calculated from food-composition tables.

RESULTS

Compared with the lowest tertile of choline intake (<250 mg/d), participants who consumed >310 mg/d had, on average, 22% lower concentrations of C-reactive protein (P < 0.05), 26% lower concentrations of interleukin-6 (P < 0.05), and 6% lower concentrations of tumor necrosis factor-alpha (P < 0.01). Similarly, participants who consumed >360 mg/d of betaine had, on average, 10% lower concentrations of homocysteine (P < 0.01), 19% lower concentrations of C-reactive protein (P < 0.1), and 12% lower concentrations of tumor necrosis factor-alpha (P < 0.05) than did those who consumed <260 mg/d. These findings were independent of various sociodemographic, lifestyle, and clinical characteristics of the participants.

CONCLUSIONS

Our results support an association between choline and betaine intakes and the inflammation process in free-eating and apparently healthy adults. However, further studies are needed to confirm or refute our findings.

Homocysteine, folates, and the eye

Plasma homocysteine has been identified as a risk factor for arterial disease, retinal artery and vein occlusions, and other common eye diseases. The value of treating an elevated plasma homocysteine with folic acid for preventing further vascular disease has not been proven. Although secondary prevention of coronary artery disease using this approach has been unsuccessful, trials on primary prevention of stroke and loss of cognitive function with folic acid supplementation appear to be successful. Further trial data are awaited. In patients with premature retinovascular disease, the measurement of plasma homocysteine is suggested and reduction of elevated homocysteine with folic acid for secondary prevention of retinal arterial and venous occlusion. Meanwhile, the debate on fortification of flour for primary prevention of neural tube defects, which has already taken place in North America, continues in European countries. Such fortification could have an impact on primary and secondary prevention of vascular disease.

Association between homocysteine, vitamin B6 concentrations and inflammation

During the last years, a growing body of evidence has been accumulated on the role of hyperhomocysteinemia in the occurrence of coronary artery disease and other arterial occlusive diseases. The mechanism by which high circulating homocysteine concentrations are a risk factor for atherothrombosis is incompletely understood. The present review is aimed to evaluate the role of inflammation in influencing homocysteine (Hcy) and vitamin B

Clin Chem Lab Med 2007;45:1728–36.