Semon Wu

Association Between a Novel 11–Base Pair Deletion Mutation in the Promoter Region of the Scavenger Receptor Class B Type I Gene and Plasma HDL Cholesterol Levels in Taiwanese Chinese

Objective—Scavenger receptor class B type I (SR-BI) is a multiligand cell-surface receptor that mediates the selective uptake of lipid from HDL cholesterol (HDL-C) into cells. This study hypothesized an association between functional variants in the promoter region of SR-BI gene and HDL-C levels. Methods and Results—We identified 2 novel mutations in the SR-BI gene promoter region by using single-strand conformation polymorphism. One mutation was an 11-bp CCCCGCCCC GT deletion mutation from positions −140 to −150 relative to the transcription start site, corresponding to an Sp1 binding site; the other was a C →T substitution at position −142. Twenty-six of 690 unrelated subjects were heterozygous for the −140 to −150 deletion mutation, and the allele frequency in this population was 0.02. This study showed that the deletion variant prevented binding of Sp1 to this region of the SR-BI promoter and effectively reduced transcriptional activities in HepG2 cells. Notably, the −140 to −150 deletion mutation was significantly associated with increased HDL-C levels and explained ≈0.5% of the variation in HDL-C levels in this population. Conclusions—A genetic variant at the SR-BI gene promoter region might explain a significant proportion of individual differences in HDL-C levels among Taiwanese Chinese. Our results require further replication in an independent population.

Three-Dimensional Reconstruction of the Rabbit Atrioventricular Conduction Axis by Combining Histological, Desmin, and Connexin Mapping Data

Background—The 3D structure of the atrioventricular conduction axis incorporating detailed cellular and molecular composition, especially that relating to gap-junctional proteins, is still unclear, impeding mechanistic understanding of cardiac rhythmic disorders. Methods and Results—A 3D model of the rabbit atrioventricular conduction axis was reconstructed by combining histological and immunofluorescence staining on serial sections. The exact cellular boundaries, especially those between transitional cells and atrial myocardium, were demarcated by a dense and irregular desmin-labeling pattern in conductive myocardium. The model demonstrates that the atrioventricular conduction axis is segregated into 2 connecting compartments, 1 predominantly expressing connexin45 (compact node and transitional cells) and the other predominantly coexpressing connexin43 and connexin45 (His bundle, lower nodal cells, and posterior nodal extension). The transitional zone shows unique features of spatial complexity, including a bridging bilayer structure (a deep transitional zone connecting with a superficial atrial-transitional overlay) and asymmetrical continuity (wider atrial-transitional interfaces and shorter atrial-axial distances in the hisian portion than in the ostial portion). In the latter compartment, the His bundle, lower nodal cells, and posterior nodal extension form a continual axis and longitudinal transitional-axial interface. Conclusions—Key findings of the present study are the demonstration of a distinct anatomical border between transitional and atrial cells, connection between transitional cells and both lower nodal cells and posterior nodal extension, and distinctive connexin expression patterns in different compartments of the rabbit atrioventricular conduction axis. These features, synthesized in a novel 3D model, provide a structural framework for the interpretation of nodal function.

Association between C-reactive protein gene haplotypes and C-reactive protein levels in Taiwanese: Interaction with obesity

OBJECTIVE The level of C-reactive protein (CRP), an inflammatory marker that predicts future cardiovascular events, is a heritable trait. Our aim was to test the statistical associations between variations in the CRP gene and serum CRP levels in a Taiwanese population with interaction analysis. METHODS A sample population of 617 Taiwanese subjects was enrolled. Five CRP single nucleotide polymorphisms (SNPs) previously reported to be associated with CRP level and with reasonable coverage of the CRP gene region were analyzed using polymerase chain reaction and restriction enzyme digestion or by TaqMan SNP Genotyping Assays. RESULTS After adjusting for clinical covariates, minor alleles of 3 of the 5 SNPs were associated with change in CRP level: rs3091244 and rs1205 were associated with increased CRP level (P=0.001 and P<0.001, respectively) and rs1800947 with decreased CRP level (P=0.003). Two haplotypes inferred from 5 SNPs (GCGCG and AAGCG) were associated with increased CRP level (P=0.017 and P<0.0001, respectively). Interaction analysis revealed interaction of obesity with CRP genotypes associated with high CRP level (interaction P=0.034 and 0.020 for SNPs rs2794521 and rs1800947, respectively). An effect of obesity on CRP level was also noted in haplotype interaction analysis with the association occurring predominantly in obese subjects (P=0.034). CONCLUSION CRP polymorphisms are independently associated with increased or decreased CRP level in Taiwanese. Further, CRP genotypes/haplotypes interact with obesity to set CRP level. These findings have implications for the prediction of atherosclerotic disease.

Apolipoprotein A5 gene -1131T/C polymorphism is associated with the risk of metabolic syndrome in ethnic Chinese in Taiwan

Abstract Background: The –1131T>C polymorphism in the apolipoprotein gene A5 (APOA5) was found to be associated with increased levels of plasma triglyceride and decreased levels of high-density lipoprotein cholesterol (HDL-C), which are characteristic dyslipidemic components of metabolic syndrome. This study aimed to identify a link between this polymorphism and the risk of metabolic syndrome. Methods: The sample population comprised 615 unrelated subjects, 18.7% of whom had metabolic syndrome. Genotypes were determined via polymerase chain reaction, restriction mapping with MseI, and gel electrophoresis. Results: A significantly higher level of triglycerides and a lower level of HDL-C were noted in carriers of the –1131C allele than in the non-carriers (p<0.001 and p=0.044, respectively). The frequency of the –1131C allele in the metabolic syndrome-affected subjects was significantly higher than that of the group of unaffected subjects (37.4% vs. 27.7%, p=0.004). Even after adjusting for age, gender, smoking, regular exercise, and waist-to-hip ratio, the APOA5 –1131C allele carriers remained significantly associated with an increased risk of metabolic syndrome (OR=1.77, 95% CI, 1.13–2.77; p=0.012). Conclusions: These results indicate that the association of APOA5 –1131T>C polymorphism with dyslipidemia can also contribute to an increased susceptibility to metabolic syndrome in the Chinese, as a result of its effect on triglyceride metabolism. Clin Chem Lab Med 2008;46:1714–9.

Regulation of macrophage immune responses by antipsychotic drugs

Abstract Antipsychotic drugs (APDs) have been used to ease clinical psychotic symptoms. APDs have also been recently discovered to induce immune regulation. Our previous studies found that atypical APDs risperidone and clozapine could inhibit INF-γ production of human peripheral blood mononuclear cells (PBMC) and could inhibit Th1 differentiation. This study further investigates APD effects on monocyte-derived macrophages, which are the major antigen-presenting cells in PBMC. Our data suggest that adhesion, phagocytosis and reactive oxygen species production of monocytic cell lines would be inhibited by haloperidol, risperidone or clozapine. Also, that APDs inhibited the production of LPS-stimulated macrophages IL-6 and IL-8 suggests that risperidone and clozapine may inhibit inflammation. We further discovered that risperidone and clozapine could inhibit IL-12 production and increase IL-10 production of LPS-stimulated macrophages. These results indicated that risperidone and clozapine could inhibit Th1 differentiation not only by increasing INF-γ production of PBMC but by inhibiting the release of Th1-inducing cytokines and increasing Th2-inducing cytokines of LPS-stimulated macrophages to modulate and regulate immune responses.

The PCSK9 gene E670G polymorphism affects low-density lipoprotein cholesterol levels but is not a risk factor for coronary artery disease in ethnic Chinese in Taiwan.

Abstract Background: An E670G polymorphism of the exon 12 of the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene was recently found to be associated with increased plasma low-density lipoprotein cholesterol (LDL-C) levels and severity of coronary atherosclerosis. This case-control study tested for a possible link between this PCSK9 polymorphism and the risk of coronary artery disease (CAD) in an ethnic Chinese population in Taiwan. Methods: The subjects included 202 CAD patients and 614 unrelated controls. Genotypes were determined via polymerase chain reaction, restriction mapping with MboII, and gel electrophoresis. Results: Contradictory to the results of a previous report, a significantly lower level of LDL-C was noted in 670G carriers than in non-carriers (2.78±0.82 mmol/L vs. 3.02±0.85 mmol/L; p=0.029) among controls, after adjusting for age, gender, smoking, hypertension, diabetes mellitus, body mass index, and use of lipid-lowering agents. The 670G carrier was identified less frequently in patients with CAD than in controls (9.9% vs. 11.9%), but the difference was not significant in a multivariable logistic regression analysis (odds ratio=0.73; 95% CI=0.24–2.22; p=0.575). The G allele also occurred at similar frequencies in the two groups (5.0% vs. 6.0%; p=0.421). Conclusions: These results indicate that the E670G polymorphism of the PCSK9 gene modulates plasma LDL-C levels, but that it is not a risk variant for CAD in ethnic Chinese in Taiwan. Clin Chem Lab Med 2009;47:154–8.

Insulin resistance is associated with C-reactive protein independent of abdominal obesity in nondiabetic Taiwanese.

Insulin resistance, which plays a fundamental role in the pathogenesis of metabolic syndrome and type 2 diabetes mellitus, is associated with serum levels of inflammatory markers and abdominal obesity. Whether insulin resistance is caused by inflammation or is an epiphenomenon of obesity remains unresolved. We therefore conducted a cross-sectional study to investigate whether the association between insulin resistance and C-reactive protein (CRP) levels is independent of abdominal obesity in a nondiabetic Taiwanese population. The study included 574 Taiwanese participants (300 men and 274 women) who were nondiabetic persons with CRP levels not exceeding 10 mg/L and who did not have a history of cardiovascular disease or were taking medication for dyslipidemia. All participants were of Han-Chinese origin. The degree of insulin resistance was determined using the homeostasis model assessment of insulin resistance (HOMA-IR). The CRP levels were categorized into quartiles from the lowest to the highest concentrations (Q1-Q4). Blood pressure, fasting glucose level, triglycerides level, waist circumference, and HOMA-IR were all found to be significantly higher in Q3 and Q4 than in Q1 and Q2. Stratified analysis by sex and abdominal obesity showed that HOMA-IR was significantly associated with CRP levels in both sexes in either obese or nonobese populations. Multiple linear regression analysis adjusting for age, smoking, components of metabolic syndrome, and waist circumference showed that the association between HOMA-IR and CRP levels remained significant in both men and women (P = .029 for men and P < .001 for women). These findings confirm that insulin resistance is strongly associated with CRP levels independent of abdominal obesity in nondiabetic Taiwanese. Factors other than abdominal obesity, such as polymorphisms in the CRP gene, may influence the association of insulin resistance with CRP levels in different ethnic populations.

Association of CDH13 Genotypes/Haplotypes with Circulating Adiponectin Levels, Metabolic Syndrome, and Related Metabolic Phenotypes: The Role of the Suppression Effect

Objective Previous genome-wide association studies have indicated an association between CDH13 genotypes and adiponectin levels. In this study, we used mediation analysis to assess the statistical association between CDH13 locus variants and adiponectin levels, metabolic syndrome, and related metabolic phenotypes. Methods and results A sample population of 530 Taiwanese participants was enrolled. Four CDH13 gene variants in the promoter and intron 1 regions were genotyped. After adjustment for clinical covariates, the CDH13 genotypes/haplotypes exhibited an association with the adiponectin levels (lowest P = 1.95 × 10−11 for rs4783244 and lowest P = 3.78 × 10−13 for haplotype ATTT). Significant correlations were observed between the adiponectin levels and the various metabolic syndrome-related phenotypes (all P ≤ 0.005). After further adjustment for the adiponectin levels, participants with a minor allele of rs12051272 revealed a considerable association with a more favorable metabolic profile, including higher insulin sensitivity, high-density lipoprotein cholesterol levels, lower diastolic blood pressure, circulating levels of fasting plasma glucose, and triglycerides, and as a lower risk of metabolic syndrome (all P < 0.05). The mediation analysis further revealed a suppression effect of the adiponectin levels on the association between CDH13 genotypes and metabolic syndrome and its related phenotypes (Sobel test; all P < 0.001). Conclusion The genetic polymorphisms at the CDH13 locus independently affect the adiponectin levels, whereas the adiponectin levels exhibit a suppressive effect on the association between CDH13 locus variants and various metabolic phenotypes and metabolic syndrome. In addition, these results provide further evidence of the association between the CDH13 gene variants and the risks of metabolic syndrome and atherosclerotic cardiovascular disease.

Association of soluble intercellular adhesion molecule–1 with insulin resistance and metabolic syndrome in Taiwanese

Circulating concentrations of soluble cell adhesive molecules are useful predictors for the risk of development and progression of atherosclerosis. This study was initiated to investigate the association between soluble intercellular adhesive molecule-1 (sICAM-1) levels and traditional and emerging cardiovascular risk factors, as well as insulin resistance and metabolic syndrome, in a Taiwanese population. Six hundred nine unrelated individuals recruited during routine health examinations were enrolled for the analysis. In age- and sex-adjusted regression models, sICAM-1 levels were negatively associated with high-density lipoprotein cholesterol levels and positively associated with systolic, mean, and diastolic blood pressure; body mass index; waist circumference; waist-hip ratio; the homeostasis model assessment index; fasting serum insulin; triglyceride; and C-reactive protein levels. The sICAM-1 levels were also higher in subjects with current smoking (P = .001), diabetes mellitus (P = .004), insulin resistance (P < .001), and metabolic syndrome (P < .001). The sICAM-1 levels increased in a stepwise fashion with increasing Framingham risk score quartiles (P = .001) and with increasing number of metabolic syndrome components (P < .001). In subjects with metabolic syndrome, increased C-reactive protein levels were associated with increased sICAM-1 levels (P = .003). In stepwise linear regression models, sICAM-1 levels remained associated with current smoking, insulin resistance, and metabolic syndrome. In conclusion, our data revealed that insulin resistance and metabolic syndrome were associated with sICAM-1 levels in Taiwanese. These data provide further evidence of the mechanisms of sICAM-1 as a molecular marker for atherosclerosis.

Functional polymorphisms of FGA, encoding α fibrinogen, are associated with susceptibility to venous thromboembolism in a Taiwanese population

To determine the genetic risk factors for venous thromboembolism (VTE), this study examined 14 genetic variants from 10 hemostatic genes in 186 Taiwanese VTE patients and the same number of matched controls, which demonstrated FGA (encoding α fibrinogen) Thr312Ala polymorphism was the only variant significantly associated with VTE. Nine genetic polymorphisms on the fibrinogen cluster region of chromosome 4q28 were further studied, in which four FGA polymorphisms were found in strong linkage disequilibrium and were significantly associated with VTE by genotype and allele frequency analyses. Haplotype analysis showed significantly different FGA haplotype frequencies between VTE patients and controls with the haplotype F1, containing -1051G, -3A, 312Ala and TaqI duplication alleles, significantly associated with susceptibility to VTE (P=0.001). Haplotype-pair analysis results also indicated a strong association of the haplotype-pair F1F1 with VTE in various VTE patient subgroups. In vitro functional analysis indicated that FGA -1051G, -3A and TaqI duplication alleles enhanced significantly the transcription level of FGA; however, control subjects with FGA genotypes containing these alleles had no elevated plasma fibrinogen levels. In conclusion, our experimental data indicated that functional genetic variants in FGA are risk factors for VTE in Taiwanese populations. Determination of FGA genotypes will likely contribute to primary prevention of this condition.