Xiao-Fei Hu

Anti-atherosclerotic potential of baicalin mediated by promoting cholesterol efflux from macrophages via the PPARγ-LXRα-ABCA1/ABCG1 pathway

BACKGROUND Atherosclerosis (AS) is associated with severe cardiovascular disease. The anti-inflammatory, anti-oxidation, and lipid regulating properties of baicalin suggest potential as an anti-atherosclerotic agent. We therefore investigated whether baicalin can protect against the development of atherosclerosis in an AS rabbit model and explored the underling mechanisms in THP-1 macrophages. METHODS AND RESULTS In vivo, treatment with baicalin markedly decreased atherosclerotic lesion sizes and lipid accumulation in AS rabbit carotid arteries. Western blotting revealed that the protein expression levels of both peroxisome proliferator-activated receptor gamma (PPARγ) and liver X receptor alpha (LXRα) were up-regulated in the baicalin group compared with the model group. In vitro, baicalin restricted oxidized-low density lipoprotein (ox-LDL)-induced intracellular lipid accumulation and foam cell formation in THP-1 macrophages. Molecular data showed that baicalin significantly increased the expression levels of PPARγ, LXRα, ATP binding cassette transporters (ABC) A1 and ABCG1. Cell transfection experiments (including PPARγ and LXRα siRNAs) suggested that the effects of baicalin are mediated by the PPARγ-LXRα signalling pathway, which stimulates the expression of ABCA1 and ABCG1. CONCLUSION These results suggest that baicalin potentially exerts anti-atherosclerosis effects, possibly through the PPARγ-LXRα-ABCA1/ABCG1 pathway, by promoting efflux of cholesterol from macrophages and delaying the formation of foam cells.

Genotype association of C(-735)T polymorphism of the MMP-2 gene with the risk of carotid atherosclerosis-vulnerable plaque in the Han Chinese population

The aim of the current study was to explore the possible association of the polymorphism of C(-735)T in MMP-2 with the vulnerable plaque risk in ultrasound-confirmed carotid atherosclerosis cases. Serum MMP-2 levels were measured to investigate the relationship between the MMP-2 level and the genetic variability. The MMP-2 polymorphism was detected by PCR-RFLP in the 243 cases with stable plaque and 221 cases with vulnerable plaque. Serum MMP-2 levels were measured with ELISA. The results showed that MMP-2 was significantly higher in the cases with vulnerable plaque than in the cases with stable plaque. A statistical difference was found between the genotype distributions in the vulnerable plaque cases and that in the stable cases. T-allele frequency was also found to be over-represented in the stable plaque cases than in the vulnerable plaque cases, which might partially explain the observed difference in the serum MMP-2 levels in the different plaque cases. The current results also suggested that MMP-2 was a risk factor in the cases with vulnerable plaques, whereas TT genotype and T allele might be protective factors in the cases with vulnerable plaques.

Positive association of MMP 14 gene polymorphism with vulnerable carotid plaque formation in a Han Chinese population

Abstract Background. MMP 14 is expressed in atherosclerotic plaques and potentially plays an important role in the development of vulnerable carotid plaques. MMP 14 gene polymorphisms can influence the bioactivity or expression of MMP 14. Objective. The aim of this study was to investigate the association between MMP 14 position + 7096 T > C (NM_004995.2:c.855T> C, rs2236307) polymorphism and vulnerable carotid plaque formation. Methods. 1370 patients with ischemic cerebral infarctions were enrolled and divided into three groups according to their carotid ultrasound examination: No plaque group (n = 346), stable plaque group (n = 695) and vulnerable plaque group (n = 329). The traditional atherosclerosis risk factors were recorded, and the MMP 14 polymorphism were genotyped by Applied Biosystems 7300 Real-Time PCR System using the TaqMan assay. Results. In the multiple logistic regression analysis done among the sub-groups, compared to no carotid plaque group, individuals with the MMP 14 position + 7096 TC+ CC genotype showed a significantly (p = 0.009) lower risk for vulnerable plaque (AOR = 0.675; 95% CI, 0.568–0.922) formation compared with subjects of the TT genotype; however, no relation between TC+ CC genotype and stable carotid plaque was observed (p > 0.125). Age was a risk factor for both stable plaque (p = 0.000; AOR = 3.732; 95% CI: 2.496–5.58) and vulnerable plaque formation (p = 0.001; AOR = 2.234; 95% CI: 1.387–3.597). Meanwhile, fibrinogen (> 4.0 g/L) was a risk factor for stable plaque (p = 0.004; AOR = 2.313; 95% CI: 1.308–4.091). Conclusions. The MMP 14 position + 7096 TC+ CC genotype might lower the risk of vulnerable carotid plaque formation. Fibrinogen (> 4.0 g/L) was a risk factor for stable plaque.

Association of a functional polymorphism in the MMP7 gene promoter with susceptibility to vulnerable carotid plaque in a Han Chinese Population

Abstract Background: Matrix metalloproteinase-7 (MMP-7) may play an important role in the development of vulnerable carotid plaque. An A-to-G transition (–181A/G) in the promoter region of MMP7 is functional in vitro by altering the transcriptional activity of the gene. The aim of this study was to investigate the association between the MMP7 –181A/G polymorphism and vulnerable carotid plaque formation. Methods: The authors enrolled 641 patients and divided them into three groups according to the carotid ultrasound examination: vulnerable plaque group (n=118), stable plaque group (n=385) and no plaque group (n=138). Traditional atherosclerosis risk factors were recorded and the MMP7 –181A/G polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism. Results: In the multinomial logistic regression analysis, compared to the no plaque group, no relationship between MMP7 –181AG+GG genotypes and stable carotid plaque was observed [odds ratio (OR) 1.50; p=0.239]. However, the frequency of AG+GG genotypes was significantly higher in the vulnerable plaque group (OR 2.74; p=0.008). Age was a risk factor for plaque formation, while statin treatment can reduce the prevalence of atherosclerotic plaque. Additionally, using binary logistic regression analysis between the stable and vulnerable plaque groups, this MMP7 polymor phism was associated with vulnerable plaque independently of other factors [OR 1.83; 95% confidence interval 1.08– 3.11; p=0.026]. Conclusions: The MMP7 –181A/G polymorphism is associated with the development of vulnerable carotid plaques. Age is a risk factor for plaque formation, while statin therapy is associated with a decreased prevalence of carotid athero-matous plaques.

High serum levels of sclerostin and Dickkopf-1 are associated with acute ischaemic stroke

BACKGROUND AND AIMS Sclerostin and Dickkopf-1 (Dkk-1) are potent antagonists of Wnt signalling and might therefore play important roles in cardiovascular disease. We investigated whether serum sclerostin and Dkk-1 levels are associated with acute ischaemic stroke and specific stroke subtypes. METHODS Serum levels of sclerostin and Dkk-1 were measured by ELISA on day 1 and on day 6 after stroke in 62 patients with large artery atherosclerotic (LAA) stroke, on day 1 after stroke in 62 age- and gender-matched patients with small-artery occlusion (SAO) stroke and on admission in 62 healthy controls. Stroke severity was determined based on the National Institutes of Health Stroke Scale (NIHSS) and by measuring stroke volume on diffusion-weighted imaging. Outcome was measured by the modified Rankin Scale (mRS) on day 90. RESULTS Compared with controls, serum sclerostin and Dkk-1 levels were significantly higher in both patients with LAA stroke and with SAO stroke, and no difference was detected between the stroke subtypes. Sclerostin and Dkk-1 levels remained stable between the first and sixth day after stroke in the patients with LAA stroke. Receiver operating characteristic curve analysis was used to evaluate sclerostin and Dkk-1 as markers of a high risk of stroke and produced area under curve values of 0.773 and 0.776. Adjusted logistic regression showed that serum sclerostin and Dkk-1 levels remained as independent markers of stroke. No correlations were found between sclerostin or Dkk-1 levels and stroke severity or stroke outcome. CONCLUSIONS High serum levels of sclerostin and Dkk-1 are associated with acute ischaemic stroke.

Lack of independent relationship between the MMP-12 gene polymorphism and carotid plaque susceptibility in the Chinese Han population

The purpose of this study was to investigate whether a polymorphism in the matrix metalloproteinase-12 gene (MMP-12 −82A/G) is correlated with serum protein levels or with the susceptibility for carotid plaques in the Chinese Han population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed on the −82A/G polymorphism in the MMP-12 gene for 1314 patients with acute cerebral infarctions; 710 of these cases were diagnosed with stable plaques, 340 cases were diagnosed with vulnerable plaques and 264 cases had no plaques. At the same time, serum MMP-12 levels were measured using the enzyme-linked immunosorbent assay (ELISA). Compared to the AA genotype, the frequency of the AG+GG genotypes was not significantly different between the three groups (χ2 = 1.242, p = 0.537), and the frequency of the G allele of the MMP-12 gene was not different within the three subgroups (χ2 = 1.218, p = 0.544). There were no significant differences in MMP-12 protein levels among the three groups (F = 0.675, p = 0.510); similarly, there was no difference in MMP-12 protein levels between the stable plaque group and the vulnerable plaque group (p = 0.755). There was also no difference between the vulnerable plaque group and the no plaque group (p = 0.420). The current data suggest that the inter-individual variability in the MMP-12 gene variation may not be a risk factor for vulnerable plaques in the Chinese Han population.

Angiopoietin-like protein 4 serum levels and gene polymorphisms are associated with large artery atherosclerotic stroke.

BACKGROUND Angiopoietin-like protein 4 (ANGPTL4) is a central player in lipid metabolism and atherosclerosis and may thus be involved in ischaemic stroke. However, no study in humans has investigated the association of ANGPTL4 gene polymorphisms or serum levels with ischaemic stroke. METHODS We investigated the influence of the tagged single nucleotide polymorphisms (tSNPs) rs4076317 (c.207C>G) and rs1044250 (c.797C>T; T266M) of the ANGPTL4 gene on ischaemic stroke risk in a large group of 712 large artery atherosclerotic (LAA) stroke patients and 828 controls. In addition, we examined the association of the serum ANGPTL4 levels with lipid metabolism, LAA stroke severity and ischaemic volume in a sample of 302 LAA stroke patients and 307 controls. RESULTS The findings reveal that rs4076317 exerts a co-dominant effect on lower serum TG levels compared with common homozygotes. Fewer stroke cases were homozygous for variants of rs4076317 compared with the controls (7.0% vs. 10.9%). The serum ANGPTL4 levels in patients were significantly higher than those in the controls in a univariate manner (P=0.001) and after adjustment for other risk factors (1.463 [1.215-1.835]; P<0.001). Consistently, the ANGPTL4 levels were statistically correlated with higher NIHSS scores (r=0.172, P=0.003) and larger lesion volumes (r=0.124, P=0.031). CONCLUSION We concluded that the tagged SNPs and high serum levels of ANGPTL4 are associated with LAA stroke and the lipid characteristics.

Tissue inhibitor of the metalloproteinases-3 gene polymorphisms and carotid plaque susceptibility in the Han Chinese population

ABSTRACT Tissue inhibitor of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases that are involved in normal cellular processes and in the development and progression of atherosclerosis. Our purpose was to evaluate the polymorphisms of the TIMP-3 genes for their associations with carotid plaques or with serum protein levels in the Han Chinese population. Two promoter variants, −915A/G (rs2234921) and −1296T/C (rs9619311), were genotyped in 548 subjects with no plaques, 462 subjects with echogenic plaques, and 427 subjects with mixture plaques. The serum TIMP-3 levels were measured using an enzyme-linked immunosorbent assay (ELISA). There was a strong linkage disequilibrium between −1296T/C and −915A/G (D′ = 1.0, r2 = 0.991). The individuals with the genotype (TC+CC) were 1.8 times more likely to have mixture plaques than the individuals with the TT genotype (P = 0.001, OR: 1.836, 95%CI: 1.269–2.665). The frequency of the C allele in the mixture plaque group was significantly higher than in the no plaque group (P = 0.009, CI: 1.119–2.187). We observed a significant elevation of the TIMP-3 levels in the serum of patients affected with mixture plaques compared to those with no plaques (P = 0.013). The current data suggest that genetic variation in the TIMP-3 genes may contribute to individual differences in mixture plaque susceptibility in the Han Chinese population.