Folic acid reduces chemokine MCP-1 release and expression in rats with hyperhomocystinemia

Hyperhomocysteinaemia Promotes Doxorubicin-Induced Cardiotoxicity in Mice

Doxorubicin, a widely used chemotherapeutic drug in clinical oncology, causes a series of cardiac side effects referred to as doxorubicin-induced cardiotoxicity. Hyperhomocysteinaemia is an independent risk factor for multiple cardiovascular diseases. However, whether hyperhomocysteinaemia contributes to doxorubicin-induced cardiotoxicity is currently unknown. In this study, we explored the pathogenic effects of hyperhomocysteinaemia induced by dietary methionine supplementation (2% wt/wt in rodent chow) in a mouse model of doxorubicin-induced cardiotoxicity. Our data showed that methionine supplementation doubled serum homocysteine levels, inducing mild hyperhomocysteinaemia. Doxorubicin at a cumulative dosage of 25 mg/kg body weight led to significant weight loss and severe cardiac dysfunction, which were further exacerbated by methionine-induced mild hyperhomocysteinaemia. Doxorubicin-induced cardiac atrophy, cytoplasmic vacuolisation, myofibrillar disarray and loss, as well as cardiac fibrosis, were also exacerbated by methionine-induced mild hyperhomocysteinaemia. Additional folic acid supplementation (0.006% wt/wt) prevented methionine-induced hyperhomocysteinaemia and inhibited hyperhomocysteinaemia-aggravated cardiac dysfunction and cardiomyopathy. In particular, hyperhomocysteinaemia increased both serum and cardiac oxidative stress, which could all be inhibited by folic acid supplementation. Therefore, we demonstrated for the first time that hyperhomocysteinaemia could exacerbate doxorubicin-induced cardiotoxicity in mice, and the pathogenic effects of hyperhomocysteinaemia might at least partially correlate with increased oxidative stress and could be prevented by folic acid supplementation. Our study provides preliminary experimental evidence for the assessment of hyperhomocysteinaemia as a potential risk factor for chemotherapy-induced cardiotoxicity in cancer patients.

Hyperhomocysteinemia Promotes Cardiac Hypertrophy in Hypertension

Hyperhomocysteinemia (HHcy) is positively linked with several cardiovascular diseases; however, its role and underlying mechanisms in pathological cardiac hypertrophy are still unclear. Here, we focused on the effects and underlying mechanisms of HHcy in hypertensive cardiac hypertrophy, one of the most common and typical types of pathological cardiac hypertrophy. By a retrospective analysis of the association between HHcy and cardiac hypertrophy in a hypertensive cohort, we found that the prevalence of HHcy was higher in patients with hypertrophy and significantly associated with the presence of cardiac hypertrophy after adjusting for other conventional risk factors. In mice, HHcy induced by a methionine (2% wt/wt) diet feeding significantly promoted cardiac hypertrophy as well as cardiac inflammation and fibrosis induced by 3-week angiotensin ІІ (AngІІ) infusion (1000 ng/kg/min), while folic acid (0.006% wt/wt) supplement corrected HHcy and attenuated AngII-stimulated cardiac phenotypes. Mechanistic studies further showed that homocysteine (Hcy) exacerbated AngII-stimulated expression of Calcineurin and nuclear factor of activated T cells (NFAT), which could be attenuated by folic acid both in mice and in neonatal rat cardiomyocytes. Moreover, treatment with cyclosporin A, an inhibitor of Calcineurin, blocked Hcy-stimulated Calcineurin-NFAT signaling and hypertrophy in neonatal rat cardiomyocytes. In conclusion, our study indicates that HHcy promotes cardiac hypertrophy in hypertension, and Calcineurin-NFAT pathway might be involved in the pro-hypertrophic effect of Hcy.

Effect of folic acid combined with pravastatin on arteriosclerosis in elderly hypertensive patients with lacunar infarction

ABSTRACT

This study aimed to assess the effect of folic acid combined with pravastatin on atherosclerosis-related indexes in elderly patients with hypertension complicated with lacunar cerebral infarction.A total of 134 elderly hypertensive patients with lacunar cerebral infarction were randomly divided into 3 groups using the random number table method. Group A, the folic acid group, had 45 cases and received low-dose folic acid (0.8 mg/d) treatment on the basis of antihypertensive treatment. Group B, the pravastatin group, had 45 cases and received pravastatin (20 mg/d) treatment on the basis of antihypertensive treatment. Group C, the folic acid combined with the pravastatin group, had 44 cases. Members of this group received pravastatin (20 mg/d) and low-dose folic acid (0.8 mg/d) based on antihypertensive treatment. Levels of folic acid, homocysteine (Hcy), tumor necrosis factor alpha (TNF-a), matrix metallopeptidase 9 (MMP-9), cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) were measured by ELISA before treatment in all 3 groups. Carotid intima-media thickness (IMT) was measured using ultrasound, and systolic and diastolic blood pressure were measured with a mercury column. After 8 weeks of treatment, the levels of folic acid, Hcy, TNF-a, MMP-9, TC, LDL-C, and systolic and diastolic blood pressure were compared among the 3 groups. IMT levels were measured at 12 weeks of treatment.After 8 weeks of treatment, compared with group B, patients in groups A and C had folic acid levels significantly higher than baseline levels, with significantly lower Hcy levels (both P < .05). Patients in group C presented significantly decreased TNF-a, MMP-9, TC, and LDL-C levels and systolic and diastolic blood pressure after 8 weeks of treatment, compared with those in groups A and B (both P < .05). These patients also showed significantly decreased IMT levels compared with those in the other groups (P < .05).Low-dose folic acid combined with pravastatin in elderly patients with lacunar cerebral infarction can reduce the level of homocysteine, improve the degree of carotid atherosclerosis, protect vascular endothelium, and reduce blood lipids and blood pressure, presenting better benefits than pravastatin alone.

Neural tube defects, folate, and immune modulation

Periconceptional supplementation with folic acid has led to a significant worldwide reduction in the incidence of neural tube defects (NTDs). However, despite increasing awareness of the benefits of folic acid supplementation and the implementation of food fortification programs in many countries, NTDs continue to be a leading cause of perinatal morbidity and mortality worldwide. Furthermore, there exists a significant subgroup of women who appear to be resistant to the protective effects of folic acid supplementation. The following review addresses emerging clinical and experimental evidence for a role of the immune system in the etiopathogenesis of NTDs, with the aim of developing novel preventative strategies to further reduce the incidence of NTD-affected pregnancies. In particular, recent studies demonstrating novel roles and interactions between innate immune factors such as the complement cascade, neurulation, and folate metabolism are explored.

Cerebrospinal fluid monocyte chemoattractant protein-1 in alcoholics: support for a neuroinflammatory model of chronic alcoholism

BACKGROUND

Liver inflammation in alcoholism has been hypothesized to influence the development of a neuroinflammatory process in the brain characterized by neurodegeneration and altered cognitive function. Monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) elevations have been noted in the alcoholic brain at autopsy and may have a role in this process.

METHODS

We studied cerebrospinal fluid (CSF) levels of MCP-1 as well as interleukin-1β and tumor necrosis factor-α in 13 healthy volunteers and 28 alcoholics during weeks 1 and 4 following detoxification. Serum liver enzymes were obtained as markers of alcohol-related liver inflammation.

RESULTS

Compared to healthy volunteers, MCP-1 levels were significantly higher in alcoholics both on day 4 and day 25 (p < 0.0001). Using multiple regression analysis, we found that MCP-1 concentrations were positively associated with the liver enzymes gamma glutamyltransferase (GGT; p = 0.03) and aspartate aminotransferase/glutamic oxaloacetic transaminase (AST/GOT; p = 0.004).

CONCLUSIONS

These preliminary findings are consistent with the hypothesis that neuroinflammation as indexed by CSF MCP-1 is associated with alcohol-induced liver inflammation, as defined by peripheral concentrations of GGT and AST/GOT.

Effect of folic acid supplementation on levels of circulating Monocyte Chemoattractant Protein-1 and the presence of intravascular ultrasound derived virtual histology thin-cap fibroatheromas in patients with stable angina pectoris

BACKGROUND

Virtual Histology Intravascular Ultrasound (VH-IVUS) may be used to detect early signs of unstable coronary artery disease. Monocyte Chemoattractant Protein-1 (MCP-1) is linked with coronary atherosclerosis and plaque instability and could potentially be modified by folic acid treatment.

METHODS

In a randomized, prospective study, 102 patients with stable angina pectoris (SAP) received percutaneous coronary intervention and established medical treatment as well as either homocysteine-lowering folic acid/vitamin B12 (± B6) or placebo (± B6) for 1 year before VH-IVUS was performed. The presence of VH-Thin-Cap Fibroatheroma (VH-TCFA) in non-intervened coronary vessels was registered and serum levels of MCP-1 were measured. The patients were subsequently followed for incident myocardial infarction (MI).

RESULTS

Patients treated with folic acid/vitamin B12 had a geometric mean (SD) MCP-1 level of 79.95 (1.49) versus 86.00 (1.43) pg/mL for patients receiving placebo (p-value 0.34). VH-TCFA lesions were present in 7.8% of patients and did not differ between intervention arms (p-value 0.47). Serum levels of MCP-1 were 1.46 (95% CI 1.12 to 1.92) times higher in patients with VH-TCFA lesions than in those without (p-value 0.005). Afterwards, patients were followed for median 2.1 years and 3.8% experienced a myocardial infarction (MI), which in post-hoc Cox regression analyses was independently predicted by both MCP-1 (P-value 0.006) and VH-TCFA (p-value 0.01).

CONCLUSIONS

In patients with SAP receiving established medical treatment, folic acid supplementation is not associated with either presence of VH-TCFA or levels of MCP-1. MCP-1 is however associated with VH-TCFA, a finding corroborated by increased risk for future MI. ClinicalTrials.gov Identifier: NCT00354081.

Folic acid fortification ameliorates hyperhomocysteinemia caused by a vitamin B₆-deficient diet supplemented with L-methionine

Vitamin B₆ (B₆) deficiency affects homocysteine metabolism, and this leads to hyperhomocysteinemia. In this study, we examined i) the effects of B₆-deficiency and graduated levels of dietary methionine on homocysteine metabolism, and ii) the effects of fortified folate on homocysteine metabolism. In experiment 1, Wistar male rats were fed a control or a B₆-deficient diet supplemented with L-methionine at a level of 3, 6, or 9 g/kg of diet for 5 weeks. The resulting plasma homocysteine levels in the B₆-deficient groups increased in relation to the increase in dietary methionine level. Next, in experiment 2, rats were fed a control, B₆-deficient, or folate enriched (10 mg pteroylmonoglutamic acid/kg) B₆-deficient diet containing L-methionine at 9 g/kg for 5 weeks. Although the B₆-deficient diet induced hyperhomocysteinemia, folate fortification ameliorated the plasma homocysteine concentration. Overall, our results indicate that folate fortification ameliorates the hyperhomocysteinemia induced by B₆ deficiency and supplemental methionine intake.

Homocysteinylated albumin promotes increased monocyte-endothelial cell adhesion and up-regulation of MCP1, Hsp60 and ADAM17

Rationale

The cardiovascular risk factor homocysteine is mainly bound to proteins in human plasma, and it has been hypothesized that homocysteinylated proteins are important mediators of the toxic effects of hyperhomocysteinemia. It has been recently demonstrated that homocysteinylated proteins are elevated in hemodialysis patients, a high cardiovascular risk population, and that homocysteinylated albumin shows altered properties.

Objective

Aim of this work was to investigate the effects of homocysteinylated albumin - the circulating form of this amino acid, utilized at the concentration present in uremia - on monocyte adhesion to a human endothelial cell culture monolayer and the relevant molecular changes induced at both cell levels.

Methods and Results

Treated endothelial cells showed a significant increase in monocyte adhesion. Endothelial cells showed after treatment a significant, specific and time-dependent increase in ICAM1 and VCAM1. Expression profiling and real time PCR, as well as protein analysis, showed an increase in the expression of genes encoding for chemokines/cytokines regulating the adhesion process and mediators of vascular remodeling (ADAM17, MCP1, and Hsp60). The mature form of ADAM17 was also increased as well as Tnf-α released in the cell medium. At monocyte level, treatment induced up-regulation of ICAM1, MCP1 and its receptor CCR2.

Conclusions

Treatment with homocysteinylated albumin specifically increases monocyte adhesion to endothelial cells through up-regulation of effectors involved in vascular remodeling.

CD4+CD25+Foxp3+ regulatory T cells protect endothelial function impaired by oxidized low density lipoprotein via the KLF-2 transcription factor

OBJECTIVE

To investigate the regulation of CD4(+)CD25(+) Regulatory T cells (Tregs) on pro-inflammatory adhesion molecules, Krüppel-Like Factor-2 (KLF-2) and its downstream transcriptional targets in human umbilical vein endothelial cells (HUVECs) impaired by ox-LDL and the mechanisms of it.

METHODS AND RESULTS

HUVECs were cultured in the continuous presence of ox-LDL(0 mg/L,25 mg/L,50 mg/L,100 mg/L) for 4, 6, 12 and 24 hours to allow identification of early-and late-induced genes, respectively, whereas non-stimulated controls were taken at 0 hours. The expression of pro-inflammatory adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1), E-selectin, KLF-2 and its target genes eNOS, PAI-1 were determined by real time RT-PCR and/or western-blot analysis. Expression of pro-inflammatory adhesion molecules, KLF-2, eNOS and PAI-1 in HUVEC cultured alone or with anti-CD3 mAbs activated Tregs, followed by addition of ox-LDL (50 mg/L) for 6 hours, are compared to expression levels in control cultures. Ox-LDL treated HUVECs increased pro-inflammatory adhesion molecules expression, as well as increased PAI-1 but decreased eNOS expression accompanied with significant downregulating of KLF-2 at a dose and time dependent manner. Furthermore, ox-LDL increased pro-inflammatory adhesion molecules but inhibited KLF2 expression was reversed by addition of Tregs. Small interfering RNA reduced endogenous KLF-2 expression and partly reversed the suppressive effect of Tregs on HUVECs activation, which strongly implicate KLF-2 as a transcriptional regulator of the Tregs-mediated effects in endothelial cells. Mechanism studies reveal that Treg-mediated KLF2 expression in HUVECs impaired by ox-LDL requires cell contact as well as soluble factors.

CONCLUSIONS

Tregs could protect endothelial function that is largely dependent on KLF2 and its downstream transcriptional targets regulation involving cell-to-cell contact and soluble factors.

CD4+CD25+Foxp3+ regulatory T cells protect the proinflammatory activation of human umbilical vein endothelial cells

OBJECTIVE

To investigate the role of CD4(+)CD25(+)forkhead box P 3 (Foxp3)(+) T-regulatory cells (Tregs) in protecting the activation and function of human umbilical vein endothelial cells (HUVECs) induced by proinflammatory stimulus and the mechanisms of it.

METHODS AND RESULTS

ECs play a major role in atherogenic initiation, changing their quiescence into activated phenotypes to support every phase of the inflammatory process. HUVECs were incubated alone, with Tregs or CD4(+)CD25(-) T cells in the presence of anti-CD3 monoclonal antibodies for 48 hours, and then were stimulated with or without oxidized low-density lipoprotein/lipopolysaccharide for an additional 24 hours. Tregs are able to induce alternative expression of immune phenotypic markers of activated HUVECs by down modulating CD86 and to inhibit the adhesion molecule, such as vascular cell adhesion molecule-1 (VCAM-1) and proinflammatory cytokine (eg, monocyte chemoattractant protein-1 and interleukin 6), response of HUVECs to oxidized low-density lipoprotein/lipopolysaccharide. Moreover, Tregs downregulate proinflammatory factor nuclear factor-κB activation and induce resistance to suppression of anti-inflammatory factor Kruppellike factor 2 in HUVECs induced by a proinflammatory stimulus. Mechanism studies reveal that Treg-mediated suppression of HUVEC proinflammatory cytokines and adhesion molecule expression impaired by oxidized low-density lipoprotein/lipopolysaccharide require cell contact by cytotoxic T-lymphocyte antigen-4 and CD86 and by soluble factors (mainly interleukin 10 and transforming growth factor [TGF]-β).

CONCLUSIONS

Tregs may exert their protective effects against atherogenesis in part through inducing an immune-inhibitory phenotype of ECs involving cytotoxic T-lymphocyte antigen-4-dependent cell-to-cell contact and also requiring soluble factors (mainly interleukin 10 and TGF-β).

Poly (ADP-ribose) polymerase inhibition improves endothelial dysfunction induced by hyperhomocysteinemia in rats

INTRODUCTION

We investigated the possible protective effect of poly (ADP-ribose) polymerase (PARP) inhibition in preventing endothelial dysfunction induced by hyperhomocysteinemia (Hhcy).

METHODS

Sprague-Dawley rats were divided into Hhcy group, Hhcy + 3-aminobenzamide(3-AB) group, control group and control + 3-AB group. A high-methionine diet was given to induce hyperhomocysteinemia. In Hhcy + 3-AB and control + 3-AB groups, rats were injected intraperitoneally with 3-AB (inhibitor of PARP). After 45 days, ultrastructural changes of aortas were observed by transmission electron microscope. Vascular reactivity of thoracic aortic rings was measured in organ chambers. PARP activity was detected. The levels of plasma total homocysteine, nitrite/nitrate, endothelin (ET)-1 and malondialdehyde were assayed.

RESULTS

Rats in Hhcy group developed severe hyperhomocysteinemia and significant loss of endothelial function as measured by both vascular rings and levels of nitrite/nitrate and ET-1. Malondialdehyde levels increased significantly in Hhcy rats compared with control rats. 3-AB improved Ach-induced, NO-mediated vascular relaxation and stabilized the level of nitrite/nitrate and ET-1. Obvious improvement of ultrastructure can be observed in Hhcy + 3-AB group.

CONCLUSIONS

These results suggest that pharmacological inhibition of PARP prevents the development of endothelial dysfunction in rats with hyperhomocysteinemia which may represent a novel approach to improve vascular dysfunction associated with hyperhomocysteinemia.