Promoter polymorphism in the endotoxin receptor (CD14) is associated with increased carotid atherosclerosis only in smokers: the Carotid Atherosclerosis Progression Study (CAPS)

Weighted Gene Co-expression Network Analysis Identifies Crucial Genes Mediating Progression of Carotid Plaque

Background

Surface rupture of carotid plaque can cause severe cerebrovascular disease, including transient ischemic attack and stroke. The aim of this study was to elucidate the molecular mechanism governing carotid plaque progression and to provide candidate treatment targets for carotid atherosclerosis.

Methods

The microarray dataset GSE28829 and the RNA-seq dataset GSE104140, which contain advanced plaque and early plaque samples, were utilized in our analysis. Differentially expressed genes (DEGs) were screened using the “limma” R package. Gene modules for both early and advanced plaques were identified based on co-expression networks constructed by weighted gene co-expression network analysis (WGCNA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes Genomes (KEGG) analyses were employed in each module. In addition, hub genes for each module were identified. Crucial genes were identified by molecular complex detection (MCODE) based on the DEG co-expression network and were validated by the GSE43292 dataset. Gene set enrichment analysis (GSEA) for crucial genes was performed. Sensitivity analysis was performed to evaluate the robustness of the networks that we constructed.

Results

A total of 436 DEGs were screened, of which 335 were up-regulated and 81 were down-regulated. The pathways related to inflammation and immune response were determined to be concentrated in the black module of the advanced plaques. The hub gene of the black module was ARHGAP18 (Rho GTPase activating protein 18). NCF2 (neutrophil cytosolic factor 2), IQGAP2 (IQ motif containing GTPase activating protein 2) and CD86 (CD86 molecule) had the highest connectivity among the crucial genes. All crucial genes were validated successfully, and sensitivity analysis demonstrated that our results were reliable.

Conclusion

To the best of our knowledge, this study is the first to combine DEGs and WGCNA to establish a DEG co-expression network in carotid plaques, and it proposes potential therapeutic targets for carotid atherosclerosis.

Promoter polymorphism of the gene for CD14 receptor is not associated with sub-clinical carotid atherosclerosis in a community population

BACKGROUND

The monocyte receptor CD14 is an important mediator of the inflammatory response to bacterial endotoxin. Recently, a functional polymorphism in the promoter of the CD14 gene (CD14-260C>T) was found to be associated with coronary heart disease. We examined if this polymorphism was associated with sub-clinical carotid atherosclerosis in a community population.

DESIGN AND METHODS

A randomly selected community population (557 men and 553 women; aged 27-77 years) underwent conventional risk factor assessment and ultrasound evaluation of the common carotid intima-medial wall thickness (IMT) and carotid plaque formation. CD14-260C>T genotypes were examined by restriction fragment length polymorphism analysis. Chlamydia pneumoniae-specific immunoglobulin G (IgG) and immunoglobulin A (IgA) antibody titres were determined by micro-immunofluorescence.

RESULTS

The carrier frequency of the T allele and TT genotype was 0.48 and 0.22 respectively. Genotype frequencies met Hardy-Weinberg expectation. There was no significant association of -260C>T genotypes with traditional risk factors. On multivariate analysis, there was no independent association of genotypes with common carotid IMT in men and women or with prevalence of carotid plaque in women. Contrary to expectation, men who were TT homozygotes relative to CC wild-type had a lower adjusted risk of carotid plaque formation (odds ratio 0.34, 95% confidence interval 0.17-0.69; P=0.003). There was no evidence that smoking or C. pneumoniae infection modified the association of genotypes with carotid IMT or plaque formation.

CONCLUSION

The CD14-260C>T gene polymorphism was not associated with an increased risk of sub-clinical carotid atherosclerosis in a community population.

TLR-4 and CD14 Genotypes and Soluble CD14: Could They Predispose to Coronary Atherosclerosis?

Background: Inflammatory mechanisms are key to the pathogenesis of atherosclerosis. Functional polymorphisms of TLR-4, Asp299Gly and Thr399Ile, CD14 promoter area C260T polymorphism and plasma levels of soluble CD14 are studied in subjects with Coronary Artery Disease (CAD). Methods: DNA was obtained from 100 human paraffin-embedded aortic specimens, from cadavers with known coronary atheromatosis (Group A) and 100 blood samples from patients with CAD, as detected by cardiac Multi-Detector-row-Computed-Tomography (MDCT) (Group B). Our control group consisted of 100 healthy individuals (Group C). Genotyping was performed by Restriction Fragment Length Polymorphism-Polymerase Chain Reaction (RFLP-PCR). Plasma levels of sCD14 were measured with ELISA. Results: For TLR-4 Asp299Gly and Thr399Ile polymorphisms, no statistically significant differences were observed. Regarding the C260T polymorphism, frequencies of T allele were significantly higher in the control group compared to the case group (p = 0.05). The Odds Ratio (OR) showed statistically significant association of TT genotype with healthy individuals (OR 0.25, 95% Confidence Interval CI 0.10–0.62, p = 0.0017). Plasma levels of sCD14 in patients with CAD (mean value = 1.35 μg/mL) were reduced when compared to reference value. Conclusions: The studied polymorphisms ofTLR-4 showed no association with CAD. Conversely, the functional polymorphism of CD14 has a statistically significant difference in expression between healthy and affected by CAD individuals.

Synergistic effect of ALOX5AP polymorphisms and cigarette smoking on the risk of atherosclerotic cerebral infarction in a Northern Han Chinese population

The effect of activating 5-lipoxygenase (ALOX5AP) gene polymorphisms on stroke risk may be influenced by the coexistence of modifiable predisposing conditions. We explored the interactions of ALOX5AP polymorphisms and cigarette smoking in a case-control study of patients with atherosclerotic cerebral infarction (ACI). Three polymorphisms of the ALOX5AP gene (rs10507391, rs4769874, and rs9551963) were analyzed in 420 ACI patients and 488 unrelated healthy controls matched for age and sex from a Northern Han Chinese population. Among the three single nucleotide polymorphisms, only rs10507391 genotype TT/TA was observed to be associated with an increased risk of ACI on multivariate analysis (odds ratio [OR]=1.82, 95% confidence interval [CI]=1.14-2.92, p=0.012) compared with the AA genotype. However, after stratifying by smoking status, multivariate logistic regression analysis revealed that rs10507391 genotype TT/TA and rs9551963 genotype CC/CA had a 5.63-fold (OR=5.63, 95%CI=2.00-15.84, p=0.001) and a 2.71-fold (OR=2.71, 95%CI=1.28-5.73, p=0.009) increased risk for ACI patients who smoked compared with the AA genotype, respectively. Additionally, according to the haplotype analysis, the risk of haplotype TGC (OR=3.12, 95%CI=2.00-4.88, p<0.001, corrected p [pc]<0.001) increased for ACI patients who smoked compared to the data (OR=1.60, 95%CI=1.28-1.98, p<0.001, pc<0.001) in total samples. These results suggest that ALOX5AP polymorphisms are associated with ACI, and cigarette smoking along with ALOX5AP could increase the risk of ACI.

Helicobacter pylori Infection Enhances Gastric Mucosal Inflammation in Individuals Carrying the 260-T Allele of the CD14 Gene

BACKGROUND/AIMS

We aim to evaluate the association between promoter polymorphism of the clusters of differentiation 14 (CD14) gene and Helicobacter pylori-induced gastric mucosal inflammation in a healthy Korean population.

METHODS

The study population consisted of 267 healthy subjects who visited our hospital for free nationwide gastric cancer screening. Promoter polymorphism at -260 C/T of the CD14 gene was determined by polymerase chain reaction and restriction fragment length polymorphism analysis. The severity of gastric mucosal inflammation was estimated by a gastritis score based on the sum of the values of the grade and activity of the gastritis. Expression of soluble CD14 (sCD14) was assessed by quantitative sandwich ELISA.

RESULTS

CD14 polymorphism was not associated with H. pylori infection. There were no significant differences in gastritis scores among the genotype subgroups, but subjects carrying the CD14 -260 CT/TT genotype had significantly higher sCD14 levels than those carrying the CC genotype. Subjects with the 260-T allele of the CD14 gene and H. pylori infection had significantly higher sCD14 levels than those with the same genotype but without infection.

CONCLUSIONS

In individuals with the T allele at the -260 site of the promoter region of the CD14 gene, H. pylori infection accentuates gastric mucosal inflammation.

Soluble CD14: genomewide association analysis and relationship to cardiovascular risk and mortality in older adults

OBJECTIVE

CD14 is a glycosylphosphotidylinositol-anchored membrane glycoprotein expressed on neutrophils and monocytes/macrophages that also circulates as a soluble form (sCD14). Despite the well-recognized role of CD14 in inflammation, relatively little is known about the genetic determinants of sCD14 or the relationship of sCD14 to vascular- and aging-related phenotypes.

METHODS AND RESULTS

We measured baseline levels of sCD14 in >5000 European-American and black adults aged 65 years and older from the Cardiovascular Health Study, who were well characterized at baseline for atherosclerotic risk factors and subclinical cardiovascular disease, and who have been followed for clinical cardiovascular disease and mortality outcomes up to 20 years. At baseline, sCD14 generally showed strong positive correlations with traditional cardio-metabolic risk factors and with subclinical measures of vascular disease such as carotid wall thickness and ankle-brachial index (independently of traditional cardiovascular disease risk factors), and was also inversely correlated with body mass index. In genomewide association analyses of sCD14, we (1) confirmed the importance of the CD14 locus on chromosome 5q21 in European-American; (2) identified a novel African ancestry-specific allele of CD14 associated with lower sCD14 in blacks; and (3) identified a putative novel association in European-American of a nonsynonymous variant of PIGC, which encodes an enzyme required for the first step in glycosylphosphotidylinositol anchor biosynthesis. Finally, we show that, like other acute phase inflammatory biomarkers, sCD14 predicts incident cardiovascular disease, and strongly and independently predicts all-cause mortality in older adults.

CONCLUSIONS

CD14 independently predicts risk mortality in older adults.

Gut microbiota, immune development and function

The microbiota of Westerners is significantly reduced in comparison to rural individuals living a similar lifestyle to our Paleolithic forefathers but also to that of other free-living primates such as the chimpanzee. The great majority of ingredients in the industrially produced foods consumed in the West are absorbed in the upper part of small intestine and thus of limited benefit to the microbiota. Lack of proper nutrition for microbiota is a major factor under-pinning dysfunctional microbiota, dysbiosis, chronically elevated inflammation, and the production and leakage of endotoxins through the various tissue barriers. Furthermore, the over-comsumption of insulinogenic foods and proteotoxins, such as advanced glycation and lipoxidation molecules, gluten and zein, and a reduced intake of fruit and vegetables, are key factors behind the commonly observed elevated inflammation and the endemic of obesity and chronic diseases, factors which are also likely to be detrimental to microbiota. As a consequence of this lifestyle and the associated eating habits, most barriers, including the gut, the airways, the skin, the oral cavity, the vagina, the placenta, the blood-brain barrier, etc., are increasingly permeable. Attempts to recondition these barriers through the use of so called 'probiotics', normally applied to the gut, are rarely successful, and sometimes fail, as they are usually applied as adjunctive treatments, e.g. in parallel with heavy pharmaceutical treatment, not rarely consisting in antibiotics and chemotherapy. It is increasingly observed that the majority of pharmaceutical drugs, even those believed to have minimal adverse effects, such as proton pump inhibitors and anti-hypertensives, in fact adversely affect immune development and functions and are most likely also deleterious to microbiota. Equally, it appears that probiotic treatment is not compatible with pharmacological treatments. Eco-biological treatments, with plant-derived substances, or phytochemicals, e.g. curcumin and resveratrol, and pre-, pro- and syn-biotics offers similar effects as use of biologicals, although milder but also free from adverse effects. Such treatments should be tried as alternative therapies; mainly, to begin with, for disease prevention but also in early cases of chronic diseases. Pharmaceutical treatment has, thus far, failed to inhibit the tsunami of endemic diseases spreading around the world, and no new tools are in sight. Dramatic alterations, in direction of a paleolithic-like lifestyle and food habits, seem to be the only alternatives with the potential to control the present escalating crisis. The present review focuses on human studies, especially those of clinical relevance.

Gene polymorphisms contributing to hypertension in immunoglobulin A nephropathy

BACKGROUND

Hypertension, which is affected by genetic and environmental factors, is one of the major risk factors for chronic kidney disease. Identification of the genetic factor contributing to hypertension in patients with chronic kidney disease may potentially refine a therapeutic strategy.

METHODS

In the present multicenter cross-sectional study, 240 patients were eligible (aged 15-50 years with urinary protein ≥0.25 g/day) out of 429 patients who were diagnosed as having immunoglobulin (Ig) A nephropathy (IgAN) by renal biopsy between 1990 and 2005 and enrolled in our previous study, PREDICT-IgAN. The outcome was hypertension defined as ≥140 and/or ≥90 mmHg of systolic and diastolic blood pressure and/or use of antihypertensives at renal biopsy. We assessed associations between hypertension and 28 polymorphisms with the frequency of minor genotype ≥10% among 100 atherosclerosis-related polymorphisms using the Chi-squared test in dominant and recessive models. We identified polymorphisms associated with hypertension in multivariate logistic regression models.

RESULTS

Baseline characteristics: hypertension 36.3%. Among 28 polymorphisms, the Chi-squared test revealed that CD14 (-159CC vs CT/TT, P = 0.03) and ACE (DD vs DI/II, P = 0.03) were significantly associated with hypertension after Bonferroni correction. Multivariate logistic regression models revealed that CD14 -159CC [vs CT/TT, odds ratio (OR) 3.58 (95% confidence interval (CI) 1.66-7.63)] and ACE DD [vs DI/II, OR 4.41 (95% CI 1.80-10.8), P = 0.001] were independently associated with hypertension.

CONCLUSIONS

CD14 C-159T and ACE I/D contributed to hypertension in patients with IgAN.

Lipopolysaccharide, CD14 and Toll-like receptors: an emerging link between innate immunity and atherosclerotic disease

Atherosclerosis and its clinical complications are now understood to be an inflammatory syndrome in which an ongoing systemic inflammatory response is combined with the accumulation of immune cells in the atherosclerotic plaque. Both arms of the immune system, innate and adaptive, have been implicated in contributing to essentially all stages of atherosclerosis, from initiation to progression and, ultimately, atherothrombotic complications. Innate immunity is the first line of defense against invading microorganisms. The recognition units of the innate immune system are designed to respond to molecular patterns shared by a variety of infectious microorganisms, such as bacterial lipopolysaccharide. Numerous basic and clinical studies have provided evidence that responsiveness to lipopolysaccharide may be correlated to the risk of atherosclerotic disease. The molecular basis of this connection appears to lie in Toll-like receptors that are expressed on cells of the innate immune system, bind to lipopolysaccharide, and thus determine the strength of antibacterial immune responses in the host. Variations in the function of Toll-like receptors and their signaling pathways are now suspected to play a critical role in determining the risk of atherosclerosis. This review summarizes recent research advances exploring the role of innate immunity, particularly lipopolysaccharide, CD14 and Toll-like receptors, in the initiation and development of atherosclerotic disease.

CD14 promoter-159 polymorphism is associated with reduced risk of intestinal-type gastric cancer in a Japanese population

Host genetic factors may play a key role in determining the long-term outcome of the Helicobacter pylori infection. Toll-like receptor 4 (TLR4) and CD14-mediated recognition of lipo-polysaccharide (LPS) is required for efficient recognition of gram-negative bacterial infections. We investigated the effects of common polymorphisms of TLR4 Asp299Gly, Thr399Ile, and CD14 promoter-C159T on the risk of gastric cancer including its subtypes and clinicopathologic features. We also investigated the effects of these polymorphisms on histologic degree of H. pylori-induced gastritis. The study was performed in 149 gastric cancer (GC) cases [mean age 64.0 +/- 12.4, M:F = 109:40] and 94 patients without evidence of GC (mean age 64.1 +/- 12.3, M:F = 65:25, Peptic ulcer diseases = 43.6%, gastritis = 56.4%) as the control group. TLR4 Asp299Gly, Thr399Ile, and CD14 promoter-C159T were determined by PCR-RFLP in all the patients. Gastritis scores of non-cancerous gastric mucosa were assessed according to the updated Sydney system in H. pylori-positive subjects (n = 179). The frequencies of CD14-260 TT and T carrier were significantly lower in patents with intestinal-type gastric cancer than in controls (OR = 0.31; 95%CI = 0.12-0.78, OR = 0.38; 95%CI = 0.18-0.81, respectively). Compared to patients older than 61 years, the atrophy score in antrum was significantly lower in TT and CT patients. TLR4 Asp299Gly and Thr399Ile were not detected in all the patients. Our data suggests that CD14 promoter-159TT and T carrier were associated with a lower risk of developing gastric mucosal atrophy in H. pylori-infected patients of more than 61 years of age, and these genotypes may reduce the risk of intestinal-type gastric cancer.

Influence of C-159T SNP of the CD14 gene promoter on lung function in smokers

CD14, a co-receptor for endotoxin, plays a significant role in regulating the inflammatory response to this agent. The C-159T single nucleotide polymorphism (SNP) in the CD14 gene promoter is an important regulator of CD14 expression, with TT homozygotes having increased expression of CD14. This SNP has been linked to pathogenesis of asthma and with cardiovascular diseases in smokers. We hypothesize that CD14 also plays a role in the pathophysiology of COPD in smokers who are exposed to endotoxin contained in cigarette smoke as well as endotoxin derived from Gram-negative microbes colonizing their airways. To assess the effect of the C-159T SNP of the CD14 gene promoter on lung function, we recruited 246 smokers 40 years of age or older with a range of 10-156 pack-year smoking exposures. The TT genotype was associated with lower lung function in smokers with a moderate smoking history. However, the CC genotype was associated with decreased lung function in heavy smokers (>56 pack years). The effect of CC genotype on severity of COPD is analogous with the effect of this genotype in risk for asthma. CD14 may be a factor in the pathophysiology of COPD, as it is in asthma and smoking-related cardiovascular diseases.

CD14 promoter-159 polymorphism is associated with reduced risk of intestinal-type gastric cancer in a Japanese population

Host genetic factors may play a key role in determining the long-term outcome of the Helicobacter pylori infection. Toll-like receptor 4 (TLR4) and CD14-mediated recognition of lipo-polysaccharide (LPS) is required for efficient recognition of gram-negative bacterial infections. We investigated the effects of common polymorphisms of TLR4 Asp299Gly, Thr399Ile, and CD14 promoter-C159T on the risk of gastric cancer including its subtypes and clinicopathologic features. We also investigated the effects of these polymorphisms on histologic degree of H. pylori-induced gastritis. The study was performed in 149 gastric cancer (GC) cases [mean age 64.0 +/- 12.4, M:F = 109:40] and 94 patients without evidence of GC (mean age 64.1 +/- 12.3, M:F = 65:25, Peptic ulcer diseases = 43.6%, gastritis = 56.4%) as the control group. TLR4 Asp299Gly, Thr399Ile, and CD14 promoter-C159T were determined by PCR-RFLP in all the patients. Gastritis scores of non-cancerous gastric mucosa were assessed according to the updated Sydney system in H. pylori-positive subjects (n = 179). The frequencies of CD14-260 TT and T carrier were significantly lower in patents with intestinal-type gastric cancer than in controls (OR = 0.31; 95%CI = 0.12-0.78, OR = 0.38; 95%CI = 0.18-0.81, respectively). Compared to patients older than 61 years, the atrophy score in antrum was significantly lower in TT and CT patients. TLR4 Asp299Gly and Thr399Ile were not detected in all the patients. Our data suggests that CD14 promoter-159TT and T carrier were associated with a lower risk of developing gastric mucosal atrophy in H. pylori-infected patients of more than 61 years of age, and these genotypes may reduce the risk of intestinal-type gastric cancer.

Risk factor correlates of platelet and leukocyte markers assessed by flow cytometry in a population-based sample

BACKGROUND

Platelet and leukocyte products are involved in atherothrombosis. However, the determinants of platelet and leukocyte markers assessed by flow cytometry have not been documented in a population-based sample.

METHODS AND RESULTS

We performed flow cytometry on blood from participants (n=1894) in the Atherosclerosis Risk in Communities (ARIC) Carotid MRI Study. Cellular aggregates and multiple platelet and leukocyte markers, such as myeloperoxidase in granulocytes and toll-like receptor-4, CD14, and CD45 in monocytes, were quantified. Their cross-sectional associations with demographic and risk factors were assessed using multiple linear regression. Mean values of most cellular markers and aggregates were considerably higher in blacks than whites (p<0.01). There were some differences in cellular markers between men and women, but little association with age. LDL-cholesterol was associated positively with several markers (toll-like receptor-4 and myeloperoxidase in granulocytes and CD162 in lymphocytes). Cholesterol-lowering therapy tended to show opposite associations. Smokers had much higher granulocyte myeloperoxidase than nonsmokers. However, most other correlations between risk factors and cellular markers were nonsignificant.

CONCLUSIONS

Race/ethnicity, sex, and to a lesser degree LDL-cholesterol and cholesterol-lowering therapy, but few other risk factors, were correlated with markers of cellular activation in this population-based study.

Ischemic stroke risk, smoking, and the genetics of inflammation in a biracial population: the stroke prevention in young women study

BACKGROUND

Although cigarette smoking is a well-established risk factor for vascular disease, the genetic mechanisms that link cigarette smoking to an increased incidence of stroke are not well understood. Genetic variations within the genes of the inflammatory pathways are thought to partially mediate this risk. Here we evaluate the association of several inflammatory gene single nucleotide polymorphisms (SNPs) with ischemic stroke risk among young women, further stratified by current cigarette smoking status.

METHODS

A population-based case-control study of stroke among women aged 15-49 identified 224 cases of first ischemic stroke (47.3% African-American) and 211 age-comparable control subjects (43.1% African-American). Several inflammatory candidate gene SNPs chosen through literature review were genotyped in the study population and assessed for association with stroke and interaction with smoking status.

RESULTS

Of the 8 SNPs (across 6 genes) analyzed, only IL6 SNP rs2069832 (allele C, African-American frequency = 92%, Caucasian frequency = 55%) was found to be significantly associated with stroke using an additive model, and this was only among African-Americans (age-adjusted: OR = 2.2, 95% CI = 1.0-5.0, p = 0.049; risk factor adjusted: OR = 2.5, 95% CI = 1.0-6.5, p = 0.05). When stratified by smoking status, two SNPs demonstrated statistically significant gene-environment interactions. First, the T allele (frequency = 5%) of IL6 SNP rs2069830 was found to be protective among non-smokers (OR = 0.30, 95% CI = 0.11-.082, p = 0.02), but not among smokers (OR = 1.63, 95% CI = 0.48-5.58, p = 0.43); genotype by smoking interaction (p = 0.036). Second, the C allele (frequency = 39%) of CD14 SNP rs2569190 was found to increase risk among smokers (OR = 2.05, 95% CI = 1.09-3.86, p = 0.03), but not among non-smokers (OR = 0.93, 95% CI = 0.62-1.39, p = 0.72); genotype by smoking interaction (p = 0.039).

CONCLUSION

This study demonstrates that inflammatory gene SNPs are associated with early-onset ischemic stroke among African-American women (IL6) and that cigarette smoking may modulate stroke risk through a gene-environment interaction (IL6 and CD14). Our finding replicates a prior study showing an interaction with smoking and the C allele of CD14 SNP rs2569190.

Low HDL cholesterol, smoking and IL-13 R130Q polymorphism are associated with myocardial infarction in Greek Cypriot males. A pilot study

This study was carried out in Greek Cypriot males to identify risk factors that predispose to myocardial infarction (MI). Genetic and lipid risk factors were investigated for the first time in a Greek Cypriot male case-control study.Contrary to other studies, mean low density lipoprotein cholesterol did not differ between cases and controls. High density lipoprotein cholesterol on the other hand, although within normal range in cases and controls, was significantly higher in the control population. In agreement with many other studies, smoking was significantly more prevalent in cases compared with controls. In pooled cases and controls, smokers had a significantly lower HDL-C level compared with non-smokers. The frequency of the IL-13 R130Q homozygotes for the mutation (QQ), as well as the mutant allele were significantly higher in cases compared with controls. The IL-13 R130Q variant, or another locus, linked to it, may increase the risk of MI.

Critical cap thickness and rupture in symptomatic carotid plaques: the oxford plaque study

BACKGROUND AND PURPOSE

Advances in carotid plaque imaging could allow quantification of fibrous cap thickness in vivo. While a cap thickness <65 microm is the accepted definition of rupture-prone plaque in the coronary circulation, the threshold value for carotid plaques is unknown.

METHODS

We made detailed histological assessments of 526 carotid plaques from consecutive patients undergoing endarterectomy for symptomatic carotid stenosis. The thickness of the fibrous cap at the thinnest and most representative part was measured.

RESULTS

Cap thickness could be measured reliably in 428 (81%) plaques. In the ruptured plaques (n=257), the median representative cap thickness was 300 microm (IQR 200 to 500 microm) and the median minimum cap thickness was 150 microm (80 to 210 microm; mean=181 microm), which is much greater than the mean cap thickness of 23 microm at the point of rupture that has been reported for coronary plaques. For nonruptured plaques, the median cap thickness values were 500 microm (300 to 700 microm) and 250 microm (180 to 400 microm), respectively. The optimum cut-offs for discriminating between ruptured and nonruptured plaques were a minimum cap thickness <200 microm (OR 5.00, 3.26 to 7.65, P<0.001), a representative cap thickness <500 microm (OR 3.38, 2.25 to 5.08, P<0.001), or a combination of both (OR 5.11, 3.19 to 8.19, P<0.001). Minimum and representative cap thickness were only modestly correlated (r(2)=0.30) and were both independently associated with cap rupture.

CONCLUSIONS

Critical cap thickness is greater in carotid plaques than coronary plaques. Minimum and representative cap thicknesses were both independently associated with cap rupture. A combination of minimum cap thickness <200 microm and a representative cap thickness <500 microm identified ruptured plaques most reliably. Prospective imaging studies are required to establish whether these cut points predict clinical events in patients with asymptomatic carotid stenosis.

Association between decreased kidney function and endotoxin receptor CD14 C-159T polymorphism among Japanese health check-up examinees

BACKGROUND

A recently identified promoter polymorphism of the endotoxin receptor (CD14 C-159T) was shown to be associated with atherosclerotic diseases such as myocardial infarction. This study was conducted to determine whether this polymorphism is associated with decreased kidney function.

METHODS

A total of 281 male and 522 female health check-up examinees, aged 39-88 years, were genotyped for CD14 C-159T. The glomerular filtration rate (GFR) was estimated by the Modification of Diet in Renal Disease (MDRD) Study equation. Estimated GFR (eGFR) and the proportion of subjects with mildly decreased eGFR (eGFR under 90 mL/min/1.73 m(2)) were compared among the genotypes.

RESULTS

Subjects carrying the T allele showed decreased age- and sex-adjusted eGFR compared with those with CC genotype (101+/-22 vs. 105+/-23 mL/min/1.73 m(2); mean+/-SD, p = 0.012). The proportion of subjects with mildly decreased eGFR was higher in T allele carriers (34.2% for TT+CT and 26.3% for CC genotype, p = 0.041), but not statistically significant when adjusted for age and sex (odds ratio [OR] 1.41, 95% CI 0.97-2.05, p = 0.076). In subjects under 65 years, T allele carriers had a significantly increased risk for mildly decreased eGFR (27.1% for TT+CT and 18.0% for CC; age- and sex-adjusted OR 1.82, 95% CI 1.06-3.12, p = 0.030).

CONCLUSION

CD14-159T allele was associated with decreased eGFR compared with CC genotype, and with a higher prevalence of mildly decreased eGFR in younger subjects under 65.

Influence of the IL-6 -572C>G polymorphism on inflammatory markers according to cigarette smoking in Korean healthy men

We investigated whether smoking would interact with the interleukin-6 (IL-6) polymorphisms (-174G>C and -572C>G, -597G>A and -1363G>T) in determining circulating levels of inflammatory markers and its consequence to oxidative stress. The G/G genotype (n=26) of the -572C>G in nonsmokers (n=376) was associated with higher IL-6 (P=0.028), fibrinogen (P=0.007) and ox-LDL (P=0.006) than those with C/C (n=209) or C/G (n=141). Results were similar for nonsmokers and smokers (n=268), but in smokers, the -572G/G genotype was associated with a greater difference in levels of IL-6 (P=0.031), fibrinogen (P=0.001), ox-LDL (P=0.037) and PGF(2alpha) (P=0.050). IL-6 had positive relations with CRP, fibrinogen, ox-LDL and PGF(2alpha). There was no evidence of an effect of -572C>G genotype on CRP levels in nonsmokers, however, this polymorphism was associated with a highly significant effect on CRP in smokers (P<0.001) (genotype-smoking interaction P=0.04, adjusted for age, BMI and IL-6). The C allele frequency at the -174 promoter region of IL-6 was very rare (<0.01) and -597G>A and -1363G>T were monomorphic in this study. Our results suggest that IL-6 -572C>G has a greater response over time to the inflammatory effects of smoking and this may result in smokers having higher oxidative stress in subjects with G/G compared to C/C or C/G.

Effect of the 252A>G polymorphism of the lymphotoxin-alpha gene on inflammatory markers of response to cigarette smoking in Korean healthy men

BACKGROUND

The systemic inflammatory response is heightened in smokers. We examined whether the established cardiovascular risk factor, smoking status, might interact with the lymphotoxin-alpha (LTA) gene 252A>G polymorphism in determining concentrations of TNF-alpha and eventually IL-6, adiponectin and CRP downstream in the inflammatory cascade.

METHODS

We measured anthropometric parameters, serum lipid profile, glucose, TNF-alpha, IL-6, CRP, adiponectin and urinary excretion of 8-epi PGF2alpha as well as a genotyping for 252A>G polymorphism of LTA in 480 healthy Korean men.

RESULTS

After adjustment for age, 208 smokers with an average consumption of 18+/-1 cigarettes/d had higher concentrations of TNF-alpha, IL-6, CRP and urinary excretion of 8-epi PGF2alpha than nonsmokers (n=272). Nonsmokers with G/G had higher TNF-alpha and 8-epi PGF2alpha concentrations than those with A/A or A/G. TNF-alpha concentrations were higher in smokers than nonsmokers of the same genotype. Smokers with G/G showed higher TNF-alpha concentration than those with A/A and had higher IL-6 and urinary 8-epi PGF2alpha concentrations than those with A/G or A/A. Furthermore, smokers carrying the G allele showed lower adiponectin concentrations than those with A/A. There are main effects of genotype and smoking, as well as the smoking-genotype interaction to TNF-alpha concentration.

CONCLUSION

Our results suggest that the LTA 252A>G polymorphism may modulate the inflammatory effects and oxidative stress of smoking. The detrimental effect of smoking is most clearly seen in men with G/G, suggesting a genotype-specific interaction with smoking.

Synergistic effect of Toll-like receptor 4 and CD14 polymorphisms on the total atherosclerosis burden in patients with peripheral arterial disease

BACKGROUND

Genes involved in the regulation of immune responses, such as Toll-like receptor 4 (TLR4) and CD14, show genetic variations with potential functional implications. Because atherosclerosis is an inflammatory process apparently modulated by chronic infections, we studied the effect of single nucleotide polymorphisms (SNPs) in TLR4 and CD14 on the extent of clinically relevant atherosclerosis in patients with peripheral arterial disease (PAD).

METHODS

Using an in-house-developed polymerase chain reaction-based restriction length polymorphism assay, we determined the genotype, allele frequency, and carrier traits of the TLR4 +896 A>G and the CD14 -260 C>T SNPs in 607 white Dutch patients with PAD. The extent of clinically relevant atherosclerosis was determined on the basis of the number of vascular territories involved, ie, coronary, cerebral, aortic, and peripheral.

RESULTS

A total of 55% of the patients had PAD only. Approximately one third of the patients had two and 11% had three vascular territories affected by clinically relevant atherosclerosis. The TLR4 +866 G allele frequency was 11%, and the CD14 -260 T allele frequency was approximately 74%. Among PAD patients, TLR4 +896 G allele carriership was univariantly associated with extensive (more than two vascular territories affected) atherosclerotic disease (odds ratio, 2.22; P = .020; chi(2) test), whereas CD14 -260 C>T carriership/homozygosity was not. Trend analysis showed that the TLR4 +866 G allele frequency increased with the number of vascular territories affected by clinically relevant atherosclerosis (P trend, .0074). In a multivariate logistic regression analysis including cardiovascular risk factors and TLR4 and CD14 SNPs, only the interaction variable "TLR4 +896 G allele carriership/CD14 -260 TT genotype" survived as an independent predictor of extensive atherosclerotic disease (P = .031; odds ratio, 4.2; 95% confidence interval, 1.1-15.4).

CONCLUSIONS

The carrier trait TLR4 G allele/CD14 TT genotype, rather than each SNP individually, is associated with the extent of clinically relevant atherosclerotic disease. Considering the importance of immune responses in atherogenesis and the genetic variation of immune regulatory genes, our data provide an explanation for interindividual differences in susceptibility to atherosclerosis and demonstrate the need to take a wider approach in analyzing relevant carrier traits instead of individual polymorphisms in relation to atherosclerosis.

CD14 promoter polymorphism in Chinese alcoholic patients with cirrhosis of liver and acute pancreatitis

AIM: To investigate the relationship between genetic polymorphism of the CD14 promoter and the occurrence of alcoholic cirrhosis and alcoholic pancreatitis, and to challenge the conclusion made earlier that the patients with acute alcoholic pancreatitis and patients with alcoholic cirrhosis of liver are two different subpopulations.

METHODS: Using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method, we determined the polymorphism of CD14 gene and aldehyde dehydrogenase gene 2 (ALDH 2) in 335 alcoholic patients with different organ complications i.e., cirrhosis of liver (n = 100), acute pancreatitis (n = 100), esophageal cancer (n = 82) and avascular necrosis of hip joint (AVN) (n = 53) and 194 non-alcoholic controls in a Chinese group.

RESULTS: The results showed that the carriage of T allele was not different among alcoholic patients with cirrhosis of liver, alcoholic patients with other complication and non-alcoholic controls. On the other hand, the carriage of the C allele was significantly more prevalent for alcoholic pancreatitis than for esophageal cancer (0.79 vs 0.60, P<0.001), alcoholic AVN (0.79vs 0.65, P<0.025) and non-alcoholic controls (0.79 vs 0.68, P<0.025). Furthermore, when only subjects with ALDH2 1-1 genotype were examined, the C allele frequency was significantly more prevalent for alcoholic pancreatitis than for alcoholic liver cirrhosis (0.82 vs 0.69, P<0.025), esophageal cancer (0.82 vs 0.61, P<0.01), alcoholic AVN (0.82 vs 0.64, P<0.01) and non-alcoholic controls (0.82 vs 0.69, P<0.05).

CONCLUSION: The C allele may be associated with some mechanism, which is important in the pathogenesis of alcoholic pancreatitis, and that alcoholic patients with acute pancreatitis and cirrhosis of liver are probably two different subpopulations.

Angiotensin converting enzyme gene, smoking and mortality in a population-based study

BACKGROUND

The genetic and environmental risk factors, which may influence longevity and mortality, have received much attention during more than one decade. One of the major risks for mortality is cardiovascular disease and the renin angiotensin system (RAS) plays a major role in maintaining blood pressure homeostasis. In this system, the Angiotensin Converting Enzyme (ACE) is one of the key regulators and has been studied in relation to cardiovascular disease and mortality. We aimed to evaluate if the ACE I/D polymorphism is related to total mortality in the elderly.

MATERIALS AND METHODS

Some 6968 elderly individuals from the Rotterdam study were genotyped for this polymorphism. Smoking was studied as a possible covariable or effect modifier. To examine the effect of the ACE genotype on mortality, a Cox proportional hazards model was fitted.

RESULTS

Our results show an increased risk of total mortality in subjects with age at death below 65 years carriers of the DD genotype (HR 1.8, 95% CI 1.1-2.9, P = 0.016). This association was significant in total and cause specific mortality only in those who smoke (P-value < 0.001 for gene-age interaction). Our findings suggest that the ACE gene is rather associated with early mortality than with late.

CONCLUSIONS

Individuals who carry the DD genotype appear to be susceptible to early mortality if they smoke, suggesting a possible interaction between smoking and the ACE gene.

CD14 C(-260)T gene polymorphism, circulating soluble CD14 levels and arteriosclerosis

BACKGROUND

CD14 pathway is at the crossroads between infection and inflammation. In human pathology, divergent results have been reported on the relationship between a polymorphism in the promoter of receptor CD14 (C260T), expression of soluble CD14 (sCD14) receptor and atherosclerosis. The aim of the study was to investigate in a cross-sectional population-based sample the relationships between C260T polymorphism in CD14 gene, sCD14 blood levels and arterial wall.

METHODS

Among 1015 subjects, randomly recruited by the Toulouse MONICA center between 1995 and 1997, 899 subjects with complete data for all the measurements, were analyzed. sCD14 was measured using an immuno-enzymatic method. Common carotid intima-media thickness (IMT) and the presence of plaques in the carotid and femoral arteries were assessed by ultrasonography. A genotypic examination for the CD14 C260T polymorphism was performed.

RESULTS

An increase in sCD14 expression was observed in subjects carrying t allele (P < 0.01). No significant difference in intima-media thickness, number of plaques and pulse wave velocity was noticed according to C260T polymorphism. An interaction (P < 0.05) was observed between C260T polymorphism and current smoking in sCD14 expression: among smokers, no significant change in sCD14 was observed in individuals carrying t allele.

CONCLUSION

Although (C260T) polymorphism in CD14 gene in this study is associated with expression of sCD14, no significant association was found between this polymorphism and early markers of atherosclerosis. This polymorphism affects plasma levels of sCD14 in relation to current smoking status. Further studies are needed to determine whether this interaction influences the deleterious effect of smoking on vascular events.

Association of the -159C/T polymorphism of the endotoxin receptor (CD14) with carotid artery disease and cardiovascular mortality in dialysis patients

BACKGROUND

Atherosclerosis is a major problem in end-stage renal disease (ESRD) patients treated by hemodialysis and the prevalence of carotid artery disease is much higher in this group than in the general population. Repeated exposure to cytokine-inducing material, derived from dialysate, may induce a chronic inflammatory state, that could contribute to the atherosclerotic process. Endotoxin is mainly cleared from plasma by the sCD14, the soluble form of the endotoxin receptor CD14. The levels of sCD14 are associated with a polymorphism, -159 C/T, of the CD14 gene.

METHODS AND RESULTS

We determined the genotype for the -159 C/T polymorphism in 158 haemodialysis patients and 168 healthy controls. In patients we investigated the association between the CD14 polymorphism and carotid artery disease. With a prospective follow-up study we assessed whether the CD14 polymorphism shows any relationship with cardiovascular mortality. The polymorphic frequency was comparable between patients and controls. In patients, we found a significant difference in the prevalence of carotid artery disease between groups divided by genotype: CC 87.0%, CT 71.7%, TT 48.9% (p = 0.0093). In dialysis patients with hypertension the CC polymorphism was associated with an increased cardiovascular mortality.

CONCLUSIONS

These results demonstrate an association between the -159 C/T polymorphism of the CD14 gene and carotid artery disease in dialysis patients. We hypothesize that the low plasma clearance of endotoxin associated with the CC genotype facilitates the atherogenic action of endotoxin-derived cytokines in haemodialysis patients.

Effect of the G-308A polymorphism of the tumor necrosis factor (TNF)-alpha gene promoter site on plasma levels of TNF-alpha and C-reactive protein in smokers: a cross-sectional study

Background

Plasma levels of tumor necrosis factor (TNF)-α and of C-reactive protein (CRP) are elevated in smokers. Previous studies failed to show an association between the G-308A polymorphism in the promoter region of the TNF-α gene and coronary artery disease (CAD). We investigated whether smoking would interact with the TNF-α G-308A polymorphism in determining plasma levels of TNF-α and CRP.

Methods

Study participants with a complete data set in terms of smoking and the TNF-α G-308A polymorphism were 300 middle-aged male and female industrial employees. After excluding 24 irregular smokers, analyses were performed on 198 "non-smokers" (life-long non-smokers or subjects who quit smoking >6 months ago) as compared to 78 "regular smokers" (subjects currently smoking >3 cigarettes/day). All subjects had a fasting morning blood draw to measure plasma levels of TNF-α and CRP by high-sensitive enzyme-linked immunosorbent assays.

Results

The cardiovascular risk factor adjusted analysis regressing log-transformed CRP levels against smoking status, genotype, and smoking-status-genotype interaction revealed a significant main effect for smoking status (F_1,250 = 5.67, p = .018) but not for genotype (F_1,250 = 0.33, p = .57). The interaction-term between genotype and smoking status was not significant (F_1,250 = 0.09, p = .76). The fully adjusted model with plasma TNF-α failed to show significant main effects for smoking and genotype, as well as for the smoking-status-genotype interaction.

Conclusions

The findings suggest that the TNF-α G-308A polymorphism does not mediate the effect of smoking on plasma CRP levels. It remains to be seen whether other genetic polymorphisms along the inflammatory pathway may modulate vascular risk in smokers.

TLR4/Asp299Gly, CD14/C-260T, plasma levels of the soluble receptor CD14 and the risk of coronary heart disease: The PRIME Study

TLR4 and CD14 are two components of the LPS receptor complex, which are considered to play a key role in the pathogenesis of atherosclerosis. TLR4/Asp299Gly and CD14/C-260T polymorphisms are thought to modulate the activity of this complex. The aim of the study was to examine the association between the TLR4/Asp299Gly and CD14/C-260T polymorphisms, plasma levels of the soluble receptor CD14 (sCD14), and the incidence of coronary heart disease (CHD) in a prospective cohort (the PRIME Study) of 9758 healthy men aged 50-59 years recruited in France and Northern Ireland. A nested case-control design was used, comparing the 249 participants who developed a CHD event during the 5-year follow-up with 492 population- and age-matched control subjects. The two polymorphisms were genotyped and baseline plasma concentrations of sCD14 were measured. None of the two polymorphisms, or sCD14 levels, either considered alone or in combination, were associated with the risk of CHD. The CD14/C-260T allele was associated with increased plasma concentrations of soluble thrombomodulin and vascular cell adhesion molecule-1 and, to a lesser extent, sCD14. No relationship was observed between the TLR4 polymorphism and, any of the inflammatory and endothelial markers measured. The TLR4/Asp299Gly and CD14/C-260T polymorphisms and plasma sCD14 concentrations do not appear as significant predictors of the risk of CHD in healthy individuals.

Genetics of Ultrasonographic Carotid Atherosclerosis

The search for genes related to the cause of common complex disorders such as cardiovascular disease has been frustrating, partly because of the many factors known to contribute to cardiovascular disease and the potential "distance" of cardiovascular disease as a phenotype from genes and gene products. Linkage and association studies for phenotypes more proximal in the pathway from DNA sequence variation to overt clinical disease, such as ultrasound-defined carotid atherosclerosis, may potentially be more enlightening. Only one genetic variant previously reported to be associated with atherosclerosis or clinically evident cardiovascular disease, matrix metalloproteinase (MMP) 3, has shown consistently positive associations with carotid disease, although it has not been studied widely. Another, PON1 L55M, is weakly associated in subgroups only, and 2, ApoE and MTHFR, are equivocal. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis. This may reflect the known inconsistency in associations of genetic variants with clinical cardiovascular disease itself. Alternatively, genetic determinants of ultrasound-defined carotid atherosclerosis may differ from those of clinically manifest cardiovascular disease and may require pursuit through large-scale genomic studies of carotid atherosclerosis as a distinct phenotype. Only 1 genetic variant, MMP 3, has shown consistently positive associations with ultrasonographic carotid disease, although it has not been studied widely. Another, PON1 L55 mol/L, is weakly associated in subgroups only. Genetic variants reported to be associated with clinical cardiovascular disease show weak or no relationship to carotid atherosclerosis.

Genetic risk factors for stroke and carotid atherosclerosis: insights into pathophysiology from candidate gene approaches

Ischaemic stroke is the most common form of stroke and is caused by atherosclerosis in most patients. Several genetic determinants contribute to stroke risk. Of these, carotid intimal-medial wall thickness (IMT) is particularly relevant, because it is a surrogate measure of subclinical atherosclerosis and a strong predictor of future ischaemic stroke. Studies of twins, siblings, and families have provided significant evidence for heritability, but the genes involved have not been identified. Some researchers have reported that IMT is high in people with functional variants of genes related to matrix deposition (MMP3), inflammation (interleukin 6), and lipid metabolism (hepatic lipase, APOE, CETP, and PON1). In this review, we assess the robustness of these associations and examine whether there is any evidence of risk modification by factors, such as smoking.

Age-specific relationship between CD14 and atopy in a cohort assessed from age 8 to 25 years

CD14 influences postnatal switching of T helper cell responses. CD14 C-159T has been associated with altered CD14 and IgE levels in cross-sectional studies. Identifying whether associations vary with age requires data from children of the same age followed longitudinally over many years. In this study, an unselected population with extensive longitudinal data was used to test the hypothesis that CD14 C-159T was associated with early-onset atopy. A total of 305 subjects were assessed on up to seven occasions between ages 8 and 25 years by questionnaire, histamine challenge, and skin prick test. For atopy, airway hyperresponsiveness (AHR), and wheeze, each subject was classified as having early onset, late onset, or no disease onset during follow-up. Compared with subjects with -159CT and -159TT, subjects with -159CC had an odds ratio of 2.2 (p = 0.018) for early-onset atopy and an odds ratio of 2.6 (p = 0.019) for early-onset AHR. Cross-sectional analysis showed increased prevalence of -159CC in subjects with atopy and AHR in childhood but not adulthood. These data suggest that the influence of CD14 -159C on the atopic phenotype may be age specific, exerting an effect during midchildhood, which is no longer apparent by early adulthood.

Oxidized low density lipoprotein and innate immune receptors

PURPOSE OF REVIEW

Atherosclerosis is now recognized as a chronic inflammatory disease. This review discusses recent literature reporting that innate immune receptors bind oxidatively modified LDL and its many oxidized moieties and consequently modulate the atherogenic process. These innate pattern recognition receptors are known to play a central role in pro-inflammatory responses to bacteria by binding pathogen-associated molecular patterns. It is hypothesized that oxidized LDL exposes similar molecular patterns recognized by receptors of innate immunity.

RECENT FINDINGS

Minimally modified LDL and its oxidized phospholipids have been found to bind to CD14 or activate Toll-like receptors on macrophages. In turn, various biological activities have been induced, including the stimulation of cytoskeletal rearrangements that alter phagocytic activity and the stimulation of cytokine secretion, such as IL-8. These findings link modified LDL with innate pattern recognition receptors, such as those involved in the lipopolysaccharide signaling pathway. Human epidemiological studies support the involvement of CD14 and TLR4 in cardiovascular diseases. Oxidized LDL has also been demonstrated to bind to C-reactive protein, an opsonic molecule activating classic complement pathway and Fcgamma receptor endocytosis. These data suggest that C-reactive protein may not only be a strong predictor of clinical disease, but may also play a role in atherogenesis. Recent data on other innate immune receptors are discussed in the context of their potential interactions with oxidized LDL and atherogenesis.

SUMMARY

Recent findings suggest that oxidized forms of LDL interact with innate immune receptors. Further studies are needed to identify the role of these interactions in inflammation and atherosclerosis.