Serum metabolomic profiling and its association with 25-hydroxyvitamin D.

INTRODUCTION: The beneficial effect of vitamin D on the risk of non-musculoskeletal diseases has been investigated in observational studies and randomized clinical trials, but the findings were inconsistent. Identification of the metabolomic profile associated with vitamin D helps to identify novel biomarkers and increase the understanding of the biochemical and physiological role of vitamin D in different health conditions. METHOD: Serum metabolomic profiling was performed using liquid chromatography/tandem mass spectrometry [LC/MS] and their association with serum 25(OH)D was evaluated using multivariable linear regression in the baseline cohort of 316 participants (aged 20 or above; 92 men, 224 women; mean age±SD: 48.1 ± 15.8 years) and in the follow-up cohort of 275 participants (aged 20 or above; 12 men, 263 women; mean age: 56.2 ± 9.6) of the Hong Kong Osteoporosis Study. We discovered and validated potential metabolites; and by meta-analysis of these associations in two cohorts, we identified metabolites that were significantly associated with serum 25(OH)D levels. RESULTS: Among 835 known metabolites, 102 metabolites showed significant correlation with 25(OH)D levels at baseline visit. Of these metabolites, 27 were validated in the follow-up visit. In meta-analysis of data from these two visits, 13 metabolites were highly correlated with 25(OH)D. The majority of metabolites identified were lipid in nature. Docosahexaenoylcarnitine and eicosapentaenoylcholine had the highest correlations, with effect estimates 0.2554 (p = 9.60 × 10-9) and 0.1682 (p = 4.94 × 10-7) respectively. CONCLUSION: In Hong Kong Chinese at least, serum vitamin D level is closely related to lipid metabolism. Our finding highlights an important new direction in the study of vitamin D in different health conditions.

Serum 25-hydroxyvitamin D and the risk of stroke in Hong Kong Chinese.

Low vitamin D levels have been associated with various cardiovascular diseases; however, whether it is associated with stroke remains inconclusive. We aimed to evaluate the association between serum 25-hydroxyvitamin D and risk of stroke. We conducted a cohort study consisting of 3,458 participants from the Hong Kong Osteoporosis Study aged ≥45 at baseline, examined between 1995 and 2010 and followed up using electronic medical records. Ischaemic and haemorrhagic stroke were defined using the ICD-9 code. In multivariable Cox-proportional hazard regression, quintiles 1 and 4 were significantly associated with increased risk of stroke when compared to the highest quintile (Quintile 1: HR, 1.78; 95 % CI, 1.16-2.74 and quintile 4: HR, 1.61; 95 % CI, 1.07-2.43). A similar association was observed in both men and women. In subgroup analysis, the association was specifically observed for ischaemic stroke, but not haemorrhagic stroke. Using a penalized regression spline, the association between vitamin D and risk of stroke was in a reverse J-shape, with the lowest risk of stroke being observed at 25(OH)D levels between 70 and 80 nmol/l. In conclusion, a low vitamin D level is associated with increased risk of ischaemic stroke; however, whether high vitamin D level is also associated with increased risk of stroke requires further study.

Plasma level of adrenomedullin is influenced by a single nucleotide polymorphism in the adiponectin gene.

OBJECTIVE: Adrenomedullin (ADM) and adiponectin are both involved in inflammation and cardiovascular diseases. The plasma levels of these peptides are influenced by single nucleotide polymorphisms (SNPs) in the ADM and ADIPOQ genes respectively. There is some evidence that ADM may regulate adiponectin gene expression, but whether adiponectin can regulate ADM expression is unclear, and was therefore investigated. METHODS: Plasma ADM level was measured in 476 subjects in the Hong Kong Cardiovascular Risk Factor Prevalence Study-2 (CRISPS2). We genotyped them for 2 ADIPOQ SNPs that are known to be associated with plasma adiponectin level. RESULTS: The minor allele frequencies of ADIPOQ SNPs rs182052 and rs12495941 were 40.6% and 42.2% respectively. Plasma ADM level was significantly associated with rs182052 after adjusting for age and sex (ß=0.104, P=0.023) but not with rs12495941 (ß=0.071, P=0.120). In multivariate analysis, plasma ADM level increased with the number of minor alleles of rs182052 (P=0.013). Compared to subjects with GG genotype, subjects with AA genotype had 17.7% higher plasma ADM level (95% CI: 3.6%-33.7%). Subgroup analysis revealed that the association was significant in diabetic patients (ß=0.344, P=0.001) but not in non-diabetic subjects. CONCLUSION: Plasma ADM level is related to SNP rs182052 in the ADIPOQ gene. Our findings provide new evidence of the interplay between these two important peptides in cardiovascular disease and diabetes. Knowing the genotype may help to refine the interpretation of these biomarkers.

A single nucleotide polymorphism of interleukin-6 gene is related to plasma adrenomedullin levels.

OBJECTIVE: Elevated plasma adrenomedullin (ADM) levels are associated with cardiovascular diseases. Single nucleotide polymorphisms (SNPs) in the gene encoding ADM (ADM) are associated with plasma ADM levels. The presence of a nuclear factor for interleukin-6 (IL-6) expression binding site in the promoter region of the ADM gene suggests a possible relationship between the expression of the ADM and IL-6. Therefore, we investigated whether plasma ADM levels are related to SNPs in the gene encoding IL-6 (IL6). METHODS: Plasma ADM levels were measured in 476 subjects in the Hong Kong Cardiovascular Risk Factor Prevalence Study-2 (CRISPS2). The subjects were genotyped for three tagging SNPs in the IL6 gene. RESULTS: The minor allele frequencies of the IL6 SNPs rs17147230, rs1800796 and rs2069837 were 41·8%, 20·0% and 15·4%, respectively. The tagging SNP, rs17147230, was associated with plasma ADM levels after adjusting for age and sex (ß=-0·096, P = 0·034). The association was significant in women (ß=-0·115, P = 0·021) but not in men. Among all subjects, plasma ADM levels decreased with an increasing number of minor alleles of rs17147230 in multivariate analysis (P = 0·034). Compared to subjects with the AA genotype, subjects with the TT genotype had plasma ADM levels 12·8% lower (95% CI: 0·6-23·5%, P = 0·041). Haplotype analysis demonstrated a significant association of the haplotype ACA with plasma ADM levels in women (P < 0·05). CONCLUSION: Plasma ADM levels are related to the SNP rs17147230 in IL6 gene. The effect of the polymorphism on inflammation and cardiovascular disease remains to be determined.

Management of obesity in the National Health and Nutrition Examination Survey (NHANES), 2007-2008.

PURPOSE: The prevalence of obesity has been increasing in the United States. We set out to investigate the use of pharmacologic and non-pharmacologic therapy for the treatment of obesity in recent years. METHODS: We included 2630 men and 2702 women who took part in the National Health and Nutrition Examination Survey from 2007 to 2008. We analyzed their demographic and anthropometric data and their weight and drug history. RESULTS: A total of 45.9% of men and 45.0% of women were candidates for treatment (body mass index ≥30 kg/m(2), or ≥27 kg/m(2) with risk factors). Among these participants, 85.1% considered themselves overweight, 90.1% would like to lose weight, 61.9% had dietary changes, 36.5% exercised, 3.7% took nonprescription drugs, and 2.2% took prescription drugs to control weight during the preceding year. During the preceding month, 0.5% and 0.1% of participants were taking phentermine and orlistat, respectively. There were no participants on sibutramine. CONCLUSIONS: Although obesity is highly prevalent, only a small percentage of obese Americans are on anti-obesity medication. The withdrawal of sibutramine would have minimal impact on the general population. There is a need for more lifestyle changes in the majority of obese individuals.

Relationship of plasma interleukin-6 and its genetic variants with hypertension in Hong Kong Chinese.

BACKGROUND: Interleukin-6 (IL6) plays a central role in inflammation, insulin resistance, and atherogenesis. We investigated the associations of plasma IL6 and its genetic variants with hypertension in both cross-sectional and prospective study designs. METHODS: Plasma IL6 was measured in 648 normotensive and 294 hypertensive subjects from the Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS)-2 in 2000-2004 and three tagging single-nucleotide polymorphisms (SNPs) in the IL6 gene were genotyped. Among subjects normotensive in CRISPS-2 (baseline), 515 subjects were followed-up in CRISPS-3 in 2005-2008 and 100 of them had developed hypertension. RESULTS: At baseline, plasma IL6 correlated with systolic blood pressure (SBP) (r = 0.128, P < 0.001). Hypertensive subjects had significantly higher plasma IL6 after adjusting for age and sex (geometric mean (95% confidence interval (CI) = 0.60 (0.54-0.65) vs. 0.47 (0.44-0.50) ng/l, P = 0.021). In multiple logistic regression, higher plasma IL6 was associated with hypertension in women (P = 0.009), but not in men. The minor G allele of SNP rs1800796 was associated with lower plasma IL6 (geometric mean (95% CI) = 0.46 (0.41-0.51) ng/l for CG and 0.49 (0.39-0.62) ng/l for GG vs. 0.53 (0.50-0.57) ng/l for CC, P = 0.005). However, this SNP was not associated with hypertension or blood pressure at baseline. Among subjects normotensive in CRISPS-2, plasma IL6 was not associated with the development of hypertension in CRISPS-3. CONCLUSION: The SNP rs1800796 affected plasma IL6 with a small effect size. Elevated plasma IL6 is associated with prevalent hypertension in women, but not incident hypertension.

Plasma adrenomedullin level is related to a single nucleotide polymorphism in the adrenomedullin gene.

OBJECTIVE: Adrenomedullin (ADM) plays an important role in inflammation and is a marker of future cardiovascular events. We studied common single nucleotide polymorphisms (SNPs) in the gene encoding ADM and their relationship with the plasma levels of ADM and other inflammatory markers. DESIGN AND METHODS: Plasma ADM, interleukin 6 (IL6), fibrinogen, and C-reactive protein (CRP) were measured in 476 subjects from the population-based Hong Kong Cardiovascular Risk Factor Prevalence Study-2. Four tag SNPs in ADM were genotyped. RESULTS: Plasma ADM level increased with decreasing plasma IL6 level (ß=-0.116, P=0.014). Plasma ADM level was not related to plasma levels of CRP and fibrinogen, and other clinical characteristics, except age (P=0.049). The four SNPs, rs3814700, rs11042725, rs34354539, and rs4910118, had minor allele frequencies of 31.1, 28.7, 33.8, and 23.4% respectively. Carriers of the minor allele of rs4910118 had a mean plasma ADM level that was 10.5% (95% confidential interval: 2.5-17.8%) lower than the non-carriers (ß=-0.115, P=0.011). Haplotype analysis revealed a similar significant association with plasma ADM (P=0.040). In multivariate analysis, the presence of the minor allele of rs4910118, but not plasma IL6, was independently associated with plasma ADM (P=0.010). CONCLUSION: Plasma ADM correlates with plasma IL6 level, consistent with its role in inflammation. It is related to an SNP common in Chinese, independent of other covariates. ADM genotype should be included in future studies of cardiovascular risk prediction.

A genetic variant in the gene encoding adrenomedullin predicts the development of dysglycemia over 6.4 years in Chinese.

BACKGROUND: Adrenomedullin, a vasodilatory peptide, facilitates the differentiation of pre-adipocytes, and affects lipolysis and glucose uptake. We investigated the association of common single nucleotide polymorphisms (SNPs) in the gene encoding adrenomedullin (ADM) with dysglycemia in the Hong Kong Chinese population. METHODS: Four SNPs were genotyped in 1391 subjects without dysglycemia at baseline from the Hong Kong Cardiovascular Risk Factor Prevalence Study-2, which had a median follow-up time of 6.4 years. Dysglycemia included impaired fasting glucose, impaired glucose tolerance, and diabetes according to the WHO 1998 criteria. At follow-up, 382 subjects had developed dysglycemia. RESULTS: In stepwise logistic regression, the SNP rs11042725 was a significant independent predictor of the development of dysglycemia (OR=1.31, P=0.012), together with baseline age (P<0.001), plasma triglycerides (P<0.001), body mass index (P=0.004), 2-h glucose after oral glucose tolerance test (P<0.001), homeostasis model assessment of insulin resistance index (P=0.045), and follow-up duration (P=0.009). The association was more significant in women (P=0.002) and in subjects without regular exercise (P=0.001). CONCLUSIONS: Our study suggests a potential role of genetic variants in the ADM gene in the development of dysglycemia in our local Chinese population.

Elevated plasma level of soluble F11 receptor/junctional adhesion molecule-A (F11R/JAM-A) in hypertension.

BACKGROUND: The F11 receptor (F11R, also known as junctional adhesion molecule A (JAM-A)) plays a role in the development of hypertension in rat. Genetic variants in the human F11R gene were demonstrated to influence systolic blood pressure. In the present study, we investigated the relationship between F11R and hypertension by examining the levels of a circulating soluble form of F11R (sF11R) in hypertensive patients. METHODS: Plasma sF11R was measured by enzyme-linked immunosorbent assay in 152 hypertensive and 166 normotensive subjects in whom seven tagging single-nucleotide polymorphisms (SNPs) in the F11R gene had been genotyped. RESULTS: Plasma sF11R levels were significantly higher in hypertensive subjects than in normotensive subjects (median (interquartile) range): 162.8 (85.5-293.2) vs. 116.5 (74.1-194.8) pg/ml, P = 0.004), which remained significantly higher after adjusting for age, sex, body mass index (BMI), and homeostasis model assessment of insulin resistance (HOMA-IR) (P = 0.028). In stepwise multiple logistic regression, sF11R level (log-transformed) (P = 0.040), triglycerides (log-transformed) (P = 0.024), and HOMA-IR (log-transformed) (P < 0.001) were independently associated with hypertension. Plasma sF11R level correlated with systolic and diastolic blood pressures (r = 0.15, P < 0.001, and r = 0.13, P = 0.024, respectively). In stepwise multiple linear regression, hypertension (P = 0.013) and fibrinogen levels (P = 0.027) were significant independent predictors of sF11R level. A seven-locus haplotype, present in 2.1% of the subjects, was associated with higher sF11R level (P = 0.024). CONCLUSIONS: These results further support a role of F11 receptor in the pathophysiology of human hypertension.

Association of a polymorphism in the lipin 1 gene with systolic blood pressure in men.

BACKGROUND: Lipin 1 plays a role in abdominal obesity, insulin resistance, and hypertriglyceridemia. The gene is located at 2p25.1, a susceptibility locus for hypertension. We studied the association of tagging single-nucleotide polymorphisms (SNPs) in the lipin 1 (LPIN1) gene with hypertension and blood pressure. METHODS: Twelve tagging SNPs from the HapMap database were genotyped using Sequenom MassArray in 268 hypertensive subjects and 407 normotensive controls, of whom 268 matched the cases in age and sex. RESULTS: None of the tagging SNPs were found to be associated with hypertension after correcting for multiple testing, although carriers of the minor allele of rs10520097 had nominally lower odds for hypertension (P = 0.014). After excluding subjects who were on antihypertensive medications, the minor allele of rs10495584 was nominally associated with lower mean systolic and diastolic blood pressures in men (121.1 +/- 14.2 and 76.3 +/- 10.2 mm Hg vs. 127.4 +/- 15.2 and 80.1 +/- 10.5 mm Hg, P = 0.002 and 0.007, respectively), but not in women (P > 0.05). The association of rs10495584 with systolic blood pressure in men remained significant after correcting for multiple testing and adjustment for age, waist circumference, insulin resistance, triglyceride, and high-density lipoprotein (HDL) cholesterol (beta = -0.158, P = 0.005). An analysis of statistically similar SNPs (ssSNPs) in the regions surrounding rs10495584 suggested that its effect may be caused by its high linkage disequilibrium (LD) with the SNP, rs11524, in which the major allele forms an exonic splicing silencer sequence. CONCLUSION: Our study provides further evidence that lipin 1 may play a role in blood pressure regulation, especially in men.

Polymorphisms of the fibrinogen-beta gene are related to 2-hour glucose level after oral glucose tolerance test in Hong Kong Chinese.

Fibrinogen, an acute phase protein, is an important inflammatory marker that is associated with cardiovascular diseases. We studied the association of three common human fibrinogen-beta gene (FGB) variants, -455G>A, -249C>T, and -148C>T with glycemic parameters in 265 non-diabetic Hong Kong Chinese subjects. Both FGB variants, -455G>A and -148C>T were in complete linkage disequilibrium and were associated with higher levels of plasma fibrinogen and 2-h glucose after a 75-g oral glucose load (p<0.01). Carriers of FGB AC-haplotype, comprising the two nucleotide variants at positions -455 and -249, had higher fibrinogen level (2.64 +/- 0.65 vs 2.42 +/- 0.52 g/L, p=0.002) and 2-h glucose after a 75-g oral glucose load (5.87 +/- 1.14 vs 5.47 +/- 1.22 g/L, p=0.006). The associations were significant in men, but not women. In stepwise multiple regression analysis, AC-haplotype was independently associated with plasma fibrinogen level and 2-h glucose (p=0.002 and 0.010 respectively). This suggests that fibrinogen may play a role in the development of impaired glucose tolerance.

Elevated plasma adrenomedullin and vascular manifestations in patients with systemic sclerosis.

OBJECTIVE: Adrenomedullin (ADM), a vasodilating peptide that possesses antiinflammatory properties, may have a regulatory role in the vascular manifestations of scleroderma (systemic sclerosis, SSc). We examined associations between ADM concentrations and vascular manifestations in a cohort of patients with SSc. METHODS: Patients were examined for manifestations of severe Raynaud's phenomenon (RP), defined as digital resorption, previous iloprost infusion, and sympathectomy. Doppler echocardiography and lung function tests were performed to detect elevation in pulmonary arterial pressure (PAP; > 35 mm Hg) and interstitial lung disease (ILD). Plasma ADM was measured by radioimmunoassay. RESULTS: Plasma ADM was measured in 62 SSc patients and 21 healthy controls. Elevated PAP was found in 15 (24.2%) SSc patients (mean PAP 46.5 +/- 11.2 mm Hg, range 37-74). ADM was not found to be related to age, sex, disease duration, or clinical subset. ADM level was significantly higher (median 13.9 pmol/l) in SSc patients with elevated PAP compared to those with lower PAP (median 7.2 pmol/l) (p = 0.01) and controls (median 7.9 pmol/l) (p = 0.04). ADM level was not different among patients who had elevated PAP with (n = 10) and without concomitant ILD (n = 5) (p = 0.21). SSc patients with severe RP (38.7%; median ADM 11.9 pmol/l) were found not to have different ADM levels compared to controls (p = 0.75). Patients who had both severe RP and elevated PAP were found to have significantly higher ADM levels (median 22.3 pmol/l) than patients who had neither manifestation (median 8.0 pmol/l) (p = 0.006) and those with severe RP alone (median 4.2 pmol/l) (p = 0.006). CONCLUSION: Elevated ADM was found in SSc patients with increased PAP regardless of concomitant ILD.

A novel intronic polymorphism of ABCA1 gene reveals risk for sporadic Alzheimer's disease in Chinese.

Recent genetic studies have shown that variants of the ATP-binding cassette transporter A1, ABCA1, may be implicated in the pathogenesis of Alzheimer's disease (AD). In this case-control study, a panel of 19 single nucleotide polymorphisms (SNP) (including three amino-acid-coding SNPs used for replication of previous work, and 16 newly selected intronic tag SNPs) was genotyped. Nominally significant single marker P-values were observed in four SNPs, with the highest score of 0.003 for rs2297404 (OR = 1.88, 95%CI 1.23-2.87). In addition, six distinct linkage disequilibrium (LD) blocks were detected. LD block1 harbored three nominally significant SNPs (rs2297404, rs2230808, and rs2020927), and showed a different haplotype structure in the affected and unaffected groups. Of the four haplotypes identified, haplotype2 (CAC) was more prevalent in the disease group (0.323 in AD vs. 0.202 in control); while haplotype1 (TGG) was over-represented in the healthy controls (0.595 in control vs. 0.493 in AD), indicating disease risk conferring possibility of haplotype2. After doubling the sample size, the three nominally significant SNPs were still significantly associated with AD. Although coding SNP (rs2230808) was confirmed to have a significant association with AD, prediction of the effects of an amino acid substitution SNP rs2230808 (R1587K) on the three-dimensional structure and function of the ABCA1 protein using PolyPhen program revealed that it is unlikely to be functionally significant. However, the adjacent rs2297404 in the same LD block is potentially functionally significant because of its position in the immediate vicinity of a splicing branch site. Further functional analysis of this polymorphism should be a high priority.

Haplotypes in the urotensin II gene and urotensin II receptor gene are associated with insulin resistance and impaired glucose tolerance.

We studied single nucleotide polymorphisms (SNPs) and haplotypes in the urotensin-II (UTS2) and urotensin-II receptor gene (UTS2R) in Hong Kong Chinese (224 hypertensive and 306 normotensive unrelated subjects) and their relation to hypertension and the metabolic syndrome. For UTS2, the GGT haplotype (-605G, 143G and 3836T) was associated with higher plasma level of U-II and insulin, and higher homeostasis model assessment of insulin resistance index and beta-cell function. For UTS2R, the AC haplotype (-11640A and -8515C) was associated with higher 2 h plasma glucose after a 75 g oral glucose load. Therefore, U-II and its receptor may play a role in insulin resistance.

Inhibition of pyocyanin-potentiated IL-8 release by steroids in bronchial epithelial cells.

Airway epithelial cells are the first targets of environmental stimuli and local cytokines. Pyocyanin-induced synergism with interleukin (IL)-1 or tumour necrosis factor (TNF) in triggering IL-8 release has been documented previously. In this study, IL-8 mRNA and protein expression were examined in cultured human bronchial epithelial cells (BEAS-2B) stimulated with pyocyanin alone, and in combination with IL-1beta or phorbol 12,13-dibutyrate (PDBu) in the absence and presence of a group of glucocorticoids. IL-8 mRNA was measured by RT-PCR, and IL-8 protein by ELISA (cell supernatants). Pyocyanin alone produced no increase in IL-8 mRNA and release. However, pyocyanin upregulated the stimulatory effect of IL-1beta or PDBu on the release of IL-8 in a dose-dependent manner. The stimulatory effect of pyocyanin on the IL-1beta- or PDBu-stimulated IL-8 release was reduced in the presence of dexamethasone, budesonide, and fluticasone. Budesonide and fluticasone were 10-fold more potent than dexamethasone. The protein kinase C (PKC) inhibitor, Go6976, also significantly reduced the stimulatory effect of pyocyanin on IL-1beta, and PDBu increased IL-8 release. In conclusion, this study shows that PKC signal pathway seems to be involved in the pyocyanin-mediated upregulation of the IL-1beta and PDBu-induced IL-8 release in BEAS-2B cells. These findings suggest that a vicious cycle perpetuating inflammation may exist in the biologic milieu of bronchiectatic patients infected with Pseudomonas aeruginosa due to the production of pyocyanin. The priming action of pyocyanin appears to be blocked by glucocorticoids, thus providing in vitro data in support of the clinical efficacy of inhaled glucocorticoids as anti-inflammatory drugs.

Elevated levels of transforming growth factor-beta(1) in serum of patients with stable bronchiectasis.

Bronchiectasis is a chronic inflammatory and infective airway disease characterized by irreversible dilatation of the bronchi and persistent purulent sputum. Transforming growth factor-beta(1) (TGF-beta(1)) has been found to be increased in the lungs or bronchoalveolar lavage fluid of patients with inflammatory lung diseases. However, little is known on the serum TGF-beta(1) levels in patients with bronchiectasis. We aimed to determine the serum TGF-beta(1) concentrations in 95 patients with stable bronchiectasis (63 women; mean+/-sd age, 58.9+/-14.1 years) and 68 control subjects (23 women; 48.9+/-12.8 years) by ELISA, and to correlate with clinical parameters. The serum TGF-beta(1) levels were significantly higher in bronchiectatic patients compared with control subjects (median [range], 1812.5 pg/ml [1226.4-4114.5 pg/ml] vs. 1342.4 pg/ml [940.3-2371.7 pg/ml]; P<0.001). There was, however, no correlation between serum TGF-beta(1) levels with FEV(1) (% predicted), FVC (% predicted), 24h sputum volume, the number of bronchiectatic lung lobes or total white blood cell count (P>0.05). Our findings support previous indications that TGF-beta(1) may contribute to bronchiectatic airway inflammation. Further studies on the potential mechanisms and pathogenesis implications of this elevation should also be pursued in future.