Chlamydia pneumoniae seropositivity is associated with increased plasma levels of soluble cellular adhesion molecules in community-dwelling subjects: the Shimanami Health Promoting Program (J-SHIPP) study.

BACKGROUND AND PURPOSE: In vitro studies have demonstrated that Chlamydia pneumoniae infection of the endothelium increases the expression of adhesion molecules and chemokines, indicating that C pneumoniae infection affects the adhesion and recruitment of leukocytes to the endothelium, which is believed to be involved in the initial steps of atherosclerosis. However, whether chronic C pneumoniae infection increases these molecules in vivo has not been elucidated. METHODS: The association between C pneumoniae seropositivity and plasma concentrations of soluble adhesion molecules and a chemokine was investigated in 200 community-dwelling residents free from cardiovascular diseases and medication. Plasma levels of IgA and IgG antibodies to C pneumoniae were measured by enzyme-linked immunosorbent assay. Indices of IgG and IgA antibodies were determined as the ratio to the standardized positive control. The subjects were divided into 3 groups according to the indices of antibodies: C pneumoniae seronegative (n=57, IgA<1.0 and IgG<1.0), C pneumoniae intermediate (n=81, 1.0< or =IgA> or =1.1 or 1.0< or =IgG> or =1.1), and C pneumoniae seropositive (n=62, IgA>1.1 and IgG>1.1). Plasma concentrations of soluble forms of intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1, and monocyte chemoattractant protein-1 were determined by enzyme-linked immunosorbent assay. RESULTS: Plasma concentrations of ICAM-1 (392+/-118, 398+/-94, 470+/-154 ng/mL, P=0.0004) and vascular cellular adhesion molecule-1 (402+/-146, 419+/-130, 472+/-181 ng/mL, P=0.03) were significantly different among the C pneumoniae seronegative, intermediate, and seropositive groups respectively. However, plasma monocyte chemoattractant protein-1 was not significantly different among the 3 groups. Stepwise regression analysis showed that plasma concentration of ICAM-1 was significantly associated with C pneumoniae seropositivity, independent of other known risk factors for atherosclerosis and carotid intima-media thickness. CONCLUSION: These findings indicate that C pneumoniae seropositivity is associated with higher plasma concentrations of soluble forms of adhesion molecules in the general population. The increase in circulating adhesion molecules may underlie the mechanisms linking C pneumoniae infection and atherosclerosis in vivo.

Plasma hepatocyte growth factor and the relationship between risk factors and carotid atherosclerosis.

Hepatocyte growth factor (HGF) has been shown to have a unique stimulating property on the endothelium as well as an anti-apoptotic action on the endothelium. Through these mechanisms, HGF has been shown to have an anti-atherogenic action in animal models. In atherosclerotic disorders, the circulating level of HGF has been shown to be increased to compensate for its decline in tissue. However, whether increased circulating HGF has any influence on the development of atherosclerosis has not been elucidated. In the present study, the association between plasma HGF concentration and the risk factor-carotid atherosclerosis relationship was evaluated. Three hundred and seventeen community-dwelling subjects participated in the study. The plasma concentration of HGF was determined by enzyme-linked immunosorbent assay (ELISA). The subjects were divided into two groups according to the plasma level of HGF: a low HGF group (n=199, plasma HGF < 150 pg/ml) and a high HGF group (n=118, plasma HGF > or = 150 pg/ml). Risk factors for atherosclerosis were evaluated in each subject. Carotid ultrasonography was performed to measure carotid arterial intima-media thickness (IMT) and the presence of plaque. The association between carotid IMT and risk factors was then evaluated in the two HGF groups. The regression lines between age and carotid IMT were significantly different between the low HGF and high HGF groups (F[1,313]=5.98, p=0.015). The regression lines between systolic blood pressure and carotid IMT were also significantly different between the two HGF groups (F[1,313]=5.17, p=0.024). A general linear model showed that the interaction between age and plasma level of HGF was significantly associated with carotid IMT, suggesting that the plasma level of HGF modifies the age-related increase in carotid IMT. In addition, clustering of risk factors was evaluated in subjects with carotid atherosclerosis. The number of total risk factors in carotid atherosclerosis subjects with high plasma HGF was significantly greater than that in those with low HGF, even though the two groups had a similar magnitude of carotid atherosclerosis. In conclusion, these findings indicate that risk factor-dependent augmentation of carotid atherosclerosis could be influenced by circulating HGF.

Genotype-specific association between circulating soluble cellular adhesion molecules and carotid intima-media thickness in community residents: J-SHIPP study. Shimanami Health Promoting Program.

Plasma levels of soluble forms of cellular adhesion molecules (CAMs) and their relationships with carotid intima-media thickness (IMT) were investigated in community residents. Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured by ELISA in 200 community residents in Japan. Carotid IMT showed a weak but significant positive correlation with the plasma levels of both sICAM-1 (r=0.175, p=0.013) and sVCAM-1 (r=0.19, p=0.0075). Gene polymorphisms of angiotensin converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) M235T, angiotensin II type 1 receptor (AT1R) A1166C and apolipoprotein E (apoE) were determined for each subject. The plasma level of sVCAM-1 tended to be lower in subjects with the ACE DD genotype than in those with the ACE ID and II genotypes (373+/-94, 421+/-133, 443+/-135 ng/ml, respectively, p=0.056). However, there were no genotype-specific differences in the plasma levels of soluble forms of CAMs for the other genes examined. In a separate analysis, the plasma level of sICAM-1 was significantly associated with carotid IMT in ACE D carriers (ID + DD) (r=0.28, p=0.002), AGT M carriers (MT + MM) (r=0.32, p=0.0045), and subjects with apoE4 (r=0.35, p=0.036). In contrast, the plasma level of sVCAM-1 showed significant positive correlations with carotid IMT in subjects with the ACE II genotype (r=0.33, p=0.0027) or AGT TT genotype (r= 0.22, p=0.015), and subjects with apoE E2/E3 or E3/E3 (r=0.16, p=0.043). Stepwise regression analysis showed that plasma sVCAM-1 was independently associated with carotid IMT in subjects with the ACE II genotype or apoE4 genotype. Similarly, the plasma level of sICAM-1 was independently associated with carotid IMT in AGT M carriers. These findings suggest that genetic background could be involved in the association between plasma CAMs and atherosclerosis.

Polymorphism of the monocyte chemoattractant protein (MCP-1) gene is associated with the plasma level of MCP-1 but not with carotid intima-media thickness.

Monocyte chemoattractant protein-1 (MCP-1) plays an important role in atherosclerosis. Recently, single nucleotide polymorphisms (SNPs) in the MCP-1 regulatory region have been identified, and an in vitro study demonstrated that the SNP at position -2518 of the MCP-1 gene affected transcription of the gene. The purpose of this study was to clarify the association of the plasma level of MCP-1 and the SNP of the MCP-1 gene with carotid atherosclerosis in community-based subjects. The study subjects consisted of 325 community residents, aged 50 years or older (mean age, 70.5 +/- 9.4 years) and free from any cardiovascular complications. Carotid intima-media thickness (IMT) was measured in the right common carotid artery using ultrasonography. The plasma level of MCP-1 was measured by enzyme-linked immunosorbent assay (ELISA). The SNP of the MCP-1 gene was determined by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique. The plasma level of MCP-1 was significantly associated with IMT (r = 0.12, p < 0.05) and carotid arterial dimension (r = 0.13, p < 0.05). There was a significant difference in plasma MCP-1 level between the genotypes (AA, 166 +/- 36 ng/ml; GG + AG, 184 +/- 56 ng/ml; p = 0.036). Analysis restricted to the subjects not receiving antihypertensive drugs or other medication further increased the statistical significance. However, carotid IMT and carotid arterial diameter were not significantly different among the MCP-1 genotypes. Stepwise regression analysis for plasma MCP-1 revealed that the MCP-1 genotype was an independent determinant of plasma MCP-1 level. These findings indicate that plasma MCP-1 is associated with carotid atherosclerosis. Although -2518 SNP is associated with the plasma level of MCP-1, it was not directly associated with carotid atherosclerosis.

Association of the GNAS1 gene variant with hypertension is dependent on alcohol consumption.

The beta-adrenoceptor (beta-AR)-stimulatory guanine nucleotide-binding (Gs) protein system has been shown to play important roles in the cardiovascular system. The gene encoding the alpha-subunit of Gs proteins (GNAS1) is a candidate genetic determinant for hypertension. Because alcohol consumption is known to affect blood pressure partly through the beta-AR-Gs protein system, we examined the possible interaction between GNAS1 T393C polymorphism and drinking status in the association with hypertension in the present study. As a result, a non-significant but reasonable trend supporting the presence of an interaction was shown (p = 0.076). In line with this trend, the T393C polymorphism significantly interacted with drinking status in the association with systolic blood pressure (p = 0.028). Moreover, supporting the presence of an interaction, T allele carriers consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than CC homozygotes in non-drinkers and light drinkers. In contrast, CC homozygotes consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than T allele carriers in moderate to heavy drinkers. The present study also showed a significant interaction between the T393C polymorphism and drinking status in the association with pulse pressure (p = 0.026), reflected by a significant association between the T393C polymorphism and pulse pressure in moderate to heavy drinkers (p = 0.026). These findings may be helpful in conducting further molecular and biological studies on the relationship among the effects of alcohol, the beta-AR-Gs protein system, and hypertension.

Genome-wide linkage disequilibrium mapping of hypertension in Japan.

Hypertension is a common, complex phenotype resulting from the interaction between genetic and environmental factors. To select candidate regions potentially responsible for hypertension, we are conducting a genome-wide linkage disequilibrium (LD) mapping of hypertension using dinucleotide repeat markers in 146 hypertensive and 136 normotensive subjects. Although the LD mapping is still underway, 19 alleles of 15 markers have already shown a nominally significant association (p<0.05), with odds ratios ranging from 0.08 to 5.12, suggesting the presence of many hypertension-related loci with weak effects in the human genome. These markers should be further assessed, adjusting for confounding factors and considering gene-gene and gene-environmental interactions in additional samples. In this report, we discuss our ongoing LD mapping project and describe the 15 markers thus far discovered. Among the 15 markers, D10S537 had a highly significant association with hypertension (p=5.3x10(-5); OR=3.80; 95% CI=1.98-7.27; where OR indicates the odds ratio and 95% CI indicates the 95% confidence interval). Further analysis in a large Japanese population showed that D10S537 was significantly associated with hypertension (p=0.044; OR=1.27; 95% CI=1.01-1.59). D10S537 was more significantly associated with hypertension in subjects with normotriglyceridemia in our population (p=0.007; OR=1.47; 95% CI=1.11-1.95).

Association of angiotensin II type 2 receptor gene variant with hypertension.

The renin-angiotensin system plays an important role in blood pressure regulation by influencing salt-water homeostasis and vascular tone. Angiotensin II, the major biologically active component of this system, exerts its effect via two pharmacologically distinct subtypes of angiotensin II receptors, the angiotensin II type 1 receptor (AT1-R) and the angiotensin II type 2 receptor (AT2-R). Thus, the AT2-R gene may be involved in hypertension. Accordingly, our objective was to examine whether polymorphisms of the AT2-R gene are involved in hypertension. The entire AT2-R gene including the promoter region was screened to find polymorphisms. As a result, two novel single nucleotide polymorphisms (SNPs), A1818T in intron 2 and G4303A in exon 3, as well as two known SNPs, A1675G in intron 1 and C4599A in exon 3, were identified. These four SNPs had similar allele frequencies, and the A1675G and C4599A polymorphisms were in almost complete linkage disequilibrium. Because the AT2-R gene is located on the X chromosome, we analyzed the possible association between the C4599A polymorphism and hypertension in men and in women separately in two large Japanese populations. This analysis showed that the C4599A polymorphism was associated with hypertension in women (p=0.0058), but not in men. Moreover, this female-specific association was pronounced in premenopausal women. The female-specific association may be helpful in conducting further molecular and biological studies on the relationship among sex, the renin-angiotensin system, and hypertension.

[Effect of elapsed time after standing up on orthostatic blood pressure change in the elderly].

The effect of time elapsed after standing on the orthostatic change in blood pressure was investigated. The study subjects were recruited from 237 community-dwelling elderly residents free from any history of cardiovascular disease and not on medication. Basal blood pressure was determined by averaging two determinations of supine blood pressure measured with an automatic oscillometric blood pressure recorder after resting for more than 10 minutes. Orthostatic change in systolic blood pressure (SBP) was determined as more than a 10% increase or decrease in SBP after standing. In the total population, maximum change in SBP was observed at 1 minute after standing-up. However, 8.4% and 7.2% of subjects showed abnormal increase or decrease in SBP only after 3 minutes. These results suggests that orthostatic dysregulation of blood pressure could be evaluated by measuring at 1 minute after standing up. However, if abnormal variation of blood pressure was not observed at 1 minute after standing up, repeated measurement at 3 minutes would be necessary.

Effects of conjugated linoleic acid on anaphylaxis and allergic pruritus.

The effects of conjugated linoleic acid (CLA) against anaphylaxis and allergic pruritus were investigated using a in vivo assay. Inhibitory effects of CLA were observed on the immediate (type 1) hypersensitivity reaction, with CLA significantly suppressing the decrease in blood pressure (BP) and blood flow (BF) induced by the hen egg-white lysozyme (HEL)-anaphylactic reaction in ddY mice. After oral administration, CLA showed antipruritic activity, with significant inhibition of scratching behavior induced by compound 48/80 (COM), a histamine-release agent. When painted onto the skin, CLA also inhibited COM, platelet-activating factor, and protease-induced scratching behavior, and COM-induced vasodilation of the skin. CLA offers promise as a drug for the treatment of allergic and inflammatory pruritus not only as an oral but also a topical agent. The present findings demonstrate that CLA can be effective for the prevention and treatment of allergic disease with severe pruritus.

Association of GNAS1 gene variant with hypertension depending on smoking status.

The beta-adrenoceptor (beta-AR) G(s) protein system has been shown to have important roles in the cardiovascular system. The gene encoding the alpha-subunit of G(s) proteins (GNAS1) is a candidate genetic determinant for hypertension. We studied the GNAS1 T393C polymorphism in >2000 Japanese individuals. chi(2) test showed a marginally significant difference in the frequencies of the alleles (P=0.036) and genotypes (P=0.094) between hypertensives and normotensives. Because hypertension is considered to be a complex disorder resulting from interactions between genetic and environmental factors, we further analyzed the T393C polymorphism, with consideration of interactions between the polymorphism and confounding factors in regression models. These analyses showed a significant interaction between the polymorphism and cigarette smoking in the pathogenesis of hypertension (P=0.0005). The interaction was reflected in a significant association of the polymorphism with hypertension in nonheavy smokers (P=0.0028; odds ratio, 1.52; 95% confidence interval, 1.16 to 2.00). A significant interaction between the polymorphism and aging in the pathogenesis of hypertension was also shown in nonheavy smokers. These findings may be helpful in conducting further molecular and biological studies on the relationship among cigarette smoking, the beta-AR-G(s) protein system, and hypertension.

Association of endothelin-1 gene variant with hypertension.

Endothelin-1 (ET-1) is a powerful vasoconstrictor peptide produced by endothelial and smooth muscle cells. Many lines of biological evidence suggest that the ET-1 gene is a candidate gene for hypertension. Moreover, recent association studies suggested that a G/T polymorphism with an amino acid substitution (Lys/Asn) at codon 198 in exon 5 of the ET-1 gene interacts with body mass index (BMI) in association with blood pressure. They suggested that T carriers are more sensitive to weight gain than GG homozygotes in association with blood pressure. However, association studies are often irreproducible, and the first study often suggests a stronger genetic effect than is found by subsequent studies. We therefore assessed the interaction in 2 large Japanese populations. The present study showed a nonsignificant but similar trend to the results of previous reports. Moreover, in line with previous reports, this study revealed a significant interaction between the ET-1 K198N (G/T) polymorphism and BMI in association with hypertension in our populations (P=0.027). The interaction was significant, even after adjustment for gender and age (P=0.045) and for all confounding factors (P=0.044). T carriers were more sensitive to weight gain than GG homozygotes in association with hypertension. Considering the combined impact of obesity and hypertension on the development of cardiovascular and cerebrovascular disorders, T allele carriers might represent elective targets for therapy to lower their body weight.