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      Hyperhomocysteinemia is associated with decreased apolipoprotein AI levels in normal healthy people

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          Abstract

          Background

          Hyperhomocysteinemia (HHcy) is an independent risk factor for various cardiovascular diseases. Animal studies have shown that homocysteine (Hcy) inhibits hepatic expression of apolipoprotein AI (apoAI). Our recent clinical study showed that increased plasma Hcy levels were associated with decreased apoAI levels in patients with impaired glucose tolerance. In this study, we assessed a potential association between Hcy and apoAI levels in normal healthy people.

          Methods

          A total of 1768 normal healthy individuals were divided into two groups: the control group (subjects without HHcy) and the HHcy group (subjects with HHcy).

          Results

          HHcy subjects exhibited significantly lower high-density lipoprotein cholesterol (HDL-C) and apoAI levels than the control group (HDL-C: 1.18 ± 0.25 vs. 1.29 ± 0.32 mmol/L; apoAI: 1.38 ± 0.19 vs. 1.47 ± 0.25 g/L; all P < 0.01). Plasma Hcy levels were negatively associated with HDL-C and apoAI levels after adjustments for age, BMI and TG (HDL-C: r = –0.10; apoAI: r = –0.11; all P < 0.05). Multivariate regression analysis showed that the plasma Hcy levels were an independent influencing factor for apoAI ( β = –0.065, P < 0.05).

          Conclusions

          Increased plasma Hcy levels were associated with decreased apoAI levels in normal healthy people, and the inhibition of apoAI synthesis might be a mechanism through which Hcy is linked with the development of atherosclerosis in HHcy subjects.

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          Most cited references23

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          Hyperhomocysteinemia promotes insulin resistance by inducing endoplasmic reticulum stress in adipose tissue.

          Type 2 diabetes is a chronic inflammatory metabolic disease, the key point being insulin resistance. Endoplasmic reticulum (ER) stress plays a critical role in the pathogenesis of type 2 diabetes. Previously, we found that hyperhomocysteinemia (HHcy) induced insulin resistance in adipose tissue. Here, we hypothesized that HHcy induces ER stress, which in turn promotes insulin resistance. In the present study, the direct effect of Hcy on adipose ER stress was investigated by the use of primary rat adipocytes in vitro and mice with HHcy in vivo. The mechanism and the effect of G protein-coupled receptor 120 (GPR120) were also investigated. We found that phosphorylation or expression of variant ER stress markers was elevated in adipose tissue of HHcy mice. HHcy activated c-Jun N-terminal kinase (JNK), the downstream signal of ER stress in adipose tissue, and activated JNK participated in insulin resistance by inhibiting Akt activation. Furthermore, JNK activated c-Jun and p65, which in turn triggered the transcription of proinflammatory cytokines. Both in vivo and in vitro assays revealed that Hcy-promoted macrophage infiltration aggravated ER stress in adipose tissue. Chemical chaperones PBA and TUDCA could reverse Hcy-induced inflammation and restore insulin-stimulated glucose uptake and Akt activation. Activation of GPR120 reversed Hcy-induced JNK activation and prevented inflammation but not ER stress. Therefore, HHcy inhibited insulin sensitivity in adipose tissue by inducing ER stress, activating JNK to promote proinflammatory cytokine production and facilitating macrophage infiltration. These findings reveal a new mechanism of HHcy in the pathogenesis of insulin resistance.
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            Vitamin B12 deficiency and hyperhomocysteinemia as correlates of cardiovascular risk factors in Indian subjects with coronary artery disease.

            Folate and vitamin B12 are essential components in the metabolism of homocysteine (Hcy). Hyperhomocysteinemia has been implicated in endothelial dysfunction and cardiovascular disease. However, the association of Hcy, vitamin B12, and folic acid with cardiovascular risk factors in patients with coronary artery disease (CAD) has not been studied in Indian patients. This study was conducted with the aim to evaluate the relationship of vitamin B12, folic acid, and Hcy levels with cardiovascular risk factors in subjects with known CAD. Three hundred patients (216 men; 84 women; aged 25-92 years) who had CAD on angiography were included in this study consecutively. All patients were evaluated for anthropometry and cardiovascular risk factors, and blood samples were collected for biochemical, nutritional, and inflammatory markers. Percentage of vitamin B12 and folate deficiency was 86.7% and 2.7%, respectively. Hyperhomocysteinemia was present in 95.3% patients. Vitamin B12 levels were significantly lower and Hcy levels were significantly higher in subjects with dyslipidemia, DM, and/or hypertension. Serum vitamin B12 was inversely associated with triglyceride and very low-density lipoprotein (VLDL) and positively with high-density lipoprotein (HDL). Hcy was positively associated with triglyceride and VLDL and negatively with HDL. Vitamin B12 was inversely correlated with inflammatory markers (high-sensitivity C-reactive protein and interleukin-6) directly related to insulin resistance whereas Hcy showed the opposite pattern. Serum vitamin B12 deficiency and hyperhomocysteinemia are related with cardiovascular risk factors in Indian patients with CAD. Copyright © 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.
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              Elevated homocysteine reduces apolipoprotein A-I expression in hyperhomocysteinemic mice and in males with coronary artery disease.

              Hyperhomocysteinemia, a risk factor for cardiovascular disease, is caused by nutritional or genetic disturbances in homocysteine metabolism. A polymorphism in methylenetetrahydrofolate reductase (MTHFR) is the most common genetic cause of mild hyperhomocysteinemia. To examine mechanisms by which an elevation in plasma homocysteine leads to vascular disease, we first performed microarray analyses in livers of Mthfr-deficient mice and identified differentially expressed genes that are involved in lipid and cholesterol metabolism. Microarrays and RT-PCR showed decreased mRNA for apolipoprotein A (ApoA)-IV and for ApoA-I and increased mRNA for cholesterol 7alpha hydroxylase (Cyp7A1) in Mthfr(+/-) mice compared with Mthfr(+/+) mice. Western blotting revealed that ApoA-I protein levels in liver and plasma of Mthfr(+/-) mice were 52% and 62% of levels in the respective tissues of Mthfr(+/+) mice. We also performed Western analysis for plasma ApoA-I protein levels in 60 males with coronary artery disease and identified a significant (P<0.01) negative correlation (-0.33) between ApoA-I and plasma homocysteine levels. This cohort also displayed a negative correlation (-0.24, P=0.06) between high-density lipoprotein cholesterol and plasma homocysteine. Treatment of HepG2 cells with supraphysiological levels of 5 mmol/L homocysteine reduced peroxisome proliferator-activated receptor (PPAR) alpha and ApoA-I protein levels and decreased ApoA-I promoter activity. Transfection with a PPARalpha construct upregulated ApoA-I and MTHFR. Our results suggest that hyperhomocysteinemia may increase risk of atherosclerosis by decreasing expression of ApoA-I and increasing expression of CYP7A1.
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                Author and article information

                Contributors
                +8610-85231710 , dllengsong@126.com
                +8610-85231710 , drwg6688@yeah.net
                Journal
                BMC Cardiovasc Disord
                BMC Cardiovasc Disord
                BMC Cardiovascular Disorders
                BioMed Central (London )
                1471-2261
                13 January 2016
                13 January 2016
                2016
                : 16
                : 10
                Affiliations
                [ ]Physical Examination Center, Beijing Chao-yang Hospital, Capital Medical University, NO. 8, Gongti South Road, Chaoyang district, Beijing, 100020 China
                [ ]Department of Endocrinology, Beijing Chao-yang Hospital, Capital Medical University, NO. 8, Gongti South Road, Chaoyang District, Beijing, 100020 China
                [ ]Health Management Center, The Second Hospital of Dalian Medical University, NO. 467, Zhongshan Road, Shahekou District, Dalian, 116000 China
                Article
                186
                10.1186/s12872-016-0186-6
                4711068
                26758372
                087d0e62-63e2-4468-80b0-92af913b08c8
                © Wang et al. 2016

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                History
                : 28 September 2015
                : 8 January 2016
                Funding
                Funded by: the Major National Basic Research Program of P. R. China
                Award ID: 2011CB503904
                Award Recipient :
                Funded by: the Chinese National Natural Science Foundation
                Award ID: 81270369, 81070244, 30770873
                Award Recipient :
                Funded by: the Beijing Natural Science Foundation
                Award ID: 7142060
                Award Recipient :
                Categories
                Research Article
                Custom metadata
                © The Author(s) 2016

                Cardiovascular Medicine
                hyperhomocysteinemia,apolipoprotein ai,cardiovascular disease
                Cardiovascular Medicine
                hyperhomocysteinemia, apolipoprotein ai, cardiovascular disease

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