C-Reactive Protein Gene Polymorphisms, C-Reactive Protein Blood Levels, and Cardiovascular Disease Risk

Lectin-like Oxidized LDL Receptor 1 Is Involved in CRP-Mediated Complement Activation

BACKGROUND

C-reactive protein (CRP) is purported to be a risk factor that acts independently of LDL cholesterol in predicting all-cause mortality in patients with ischemic heart disease. Lectin-like oxidized LDL receptor 1 (LOX-1) impairs endothelial function and exacerbates myocardial injury. We recently demonstrated that CRP increased vascular permeability through direct binding to LOX-1. Here we examined, using a hypertensive rat model, whether LOX-1 is involved in CRP-induced complement activation.

METHODS AND RESULTS

In the cultured LOX-1–expressing cell line hLOX-1-CHO, CRP increased complement activation, but did not do so in native CHO cells. Depleting C1q from serum abolished CRP-induced complement activation. Incubation of CRP with serum on immobilized recombinant LOX-1 similarly showed that CRP activated C1q-requiring classical complement pathway in a LOX-1–dependent manner. Interestingly, the interaction between CRP and LOX-1 was dependent on Ca2+ ion and competed with phosphocholine, suggesting that LOX-1 bound to the B-face of CRP with a phosphocholine-binding domain. This was in contrast to Fcγ receptors, to which CRP bound in A-face with complement-binding domain. In vivo, intradermal injection of CRP to hypertensive SHRSP rats induced complement activation detected by C3d deposition and leukocyte infiltration around the injected area. Anti–LOX-1 antibody reduced the extent of complement activation and leukocyte infiltration.

CONCLUSIONS

LOX-1 appears to be involved in CRP-induced complement activation, and thus may serve to locate the site of CRP-induced complement activation and inflammation.

Study of C-reactive protein and myocardial infarction in the Indian population

To analyse the association of high sensitivity C-reactive (hsCRP) protein levels and -717A/G single nucleotide polymorphism of CRP with acute myocardial infarction (AMI) in the Indian population. Study population included 100 MI cases wherein 32 patients had experienced previous MI (MI-Group-1), 68 MI cases were recruited at presentation (MI-Group-2) and equal number of age and gender matched healthy individuals. hsCRP levels were determined by ELISA and genotyping of -717A/G was carried out by polymerase chain reaction-based restriction digestion method. The -717A/G genotypes did not influence hsCRP level and their distribution did not differ between groups. However, in the present study hsCRP demonstrated significant correlation with BMI in controls of both the genders and with triglycerides in females of AMI at presentation who otherwise are with low risk profile. Identifying traditional risk factors associated with inflammation may help in controlling the acute event.

Single-nucleotide polymorphisms at five loci are associated with C-reactive protein levels in a cohort of Filipino young adults

C-reactive protein (CRP) is a component of nonspecific immune defense and is a reliable marker of low-grade inflammation involved in obesity, type 2 diabetes and cardiovascular disease. Genome-wide association studies in middle-aged and elderly populations, predominantly of European descent, demonstrated associations of CRP levels with single-nucleotide polymorphisms (SNPs) at several loci. To examine whether the variants identified are replicated in Filipino young adults, we applied Tobit regression models to study the association of plasma CRP with 12 SNPs at seven loci in a cohort of 1691 Filipino young adults (aged 21.5±0.3 years) from the Cebu Longitudinal Health and Nutrition Survey. SNPs in or near CRP (P=3.2 × 10(-11)), HNF1A, IL6R, APOE-APOC1 and LEPR showed significant associations (P<0.05) and together explained 4.8% of the total variation in CRP. Modest interactions were observed between LEPR-rs1892534 and waist circumference (uncorrected P(interaction)=0.020) and between APOE-rs769449 and pathogen exposure (uncorrected P(interaction)=0.0073) in models predicting CRP. Our results demonstrated that variants in several loci are significantly associated with plasma CRP in Filipino young adults, suggesting shared genetic influences on circulating CRP across populations and age groups.

Genetic polymorphisms of innate immunity-related inflammatory pathways and their association with factors related to type 2 diabetes

Background

Type 2 diabetes mellitus (T2DM) has been linked to a state of pre-clinical chronic inflammation resulting from abnormalities in the innate immune pathway. Serum levels of pro-inflammatory cytokines and acute-phase proteins, collectively known as 'inflammatory network', are elevated in the pre-, or early, stages of T2DM and increase with disease progression. Genetic variation can affect the innate immune response to certain environmental factors, and may, therefore, determine an individual's lifetime risk of disease.

Methods

We conducted a cross-sectional study in 6,720 subjects from the TwinsUK Registry to evaluate the association between 18 single nucleotide polymorphisms (SNPs) in five genes (TLR4, IL1A, IL6, TNFA, and CRP) along the innate immunity-related inflammatory pathway and biomarkers of predisposition to T2DM [fasting insulin and glucose, HDL- and LDL- cholesterols, triglycerides (TGs), amyloid-A, sensitive C-reactive protein (sCRP) and vitamin D binding protein (VDBP) and body mass index (BMI)].

Results

Of 18 the SNPs examined for their association with nine metabolic phenotypes of interest, six were significantly associated with five metabolic phenotypes (Bonferroni correction, P ≤ 0.0027). Fasting insulin was associated with SNPs in IL6 and TNFA, serum HDL-C with variants of TNFA and CRP and serum sCRP level with SNPs in CRP. Cross-correlation analysis among the different metabolic factors related to risk of T2DM showed several significant associations. For example, BMI was directly correlated with glucose (r = 0.11), insulin (r = 0.15), sCRP (r = 0.23), LDL-C (r = 0.067) and TGs (r = 0.18) but inversely with HDL-C (r = -0.14). sCRP was also positively correlated (P < 0.0001) with insulin (r = 0.17), amyloid-A (r = 0.39), TGs (r = 0.26), and VDBP (r = 0.36) but inversely with HDL-C (r = -0.12).

Conclusion

Genetic variants in the innate immunity pathway and its related inflammatory cascade is associated with some metabolic risk factors for T2DM; an observation that may provide a rationale for further studying their role as biomarkers for disease early risk prediction.

C-reactive protein (CRP) gene polymorphisms: implication in CRP plasma levels and susceptibility to acute myocardial infarction

C-reactive protein (CRP) is one of the many molecular factors involved in pathogenesis of coronary artery disease which its plasma levels are associated with increased risk of cardiovascular events. The present study designed to determine whether polymorphisms in the CRP gene are associated with plasma CRP levels and susceptibility to acute myocardial infarction (AMI). Plasma CRP levels were measured in patients with AMI and control subjects and genomic DNA and peripheral blood mononuclear cells (PBMCs) were extracted. The -717A/G and 1059G/C CRP polymorphisms were detected. The mRNA expression of CRP gene and plasma levels of CRP and interleukin-6 (IL-6) were also analyzed. The -717A/G variation was significantly associated with higher CRP levels, but 1059G/C variation was associated with lower CRP levels. The AA genotype frequency of -717A/G variation was significantly more frequent in the patients than control subjects. By contrast, the genotype and allele distribution in 1059G/C of patient were not statistically different between patients and controls. There were significant differences in circulating levels of CRP and IL-6 in the patients than in controls. The mRNA expression levels of CRP were significantly higher in the patient plasma compared with controls. Our results indicate relationship between many polymorphisms in CRP gene and risk of AMI which suggest that genetic variations in CRP might be helpful for determining susceptibility to AMI in Iranian patients. In addition, CRP gene polymorphisms are associated with plasma CRP levels and susceptibility to AMI might be related to CRP gene expression which affects its plasma levels.

Systems biology and heart failure: concepts, methods, and potential research applications

Dramatic advances in molecular biology dominated twentieth century biomedical science and delineated the function of individual genes and molecules in exquisite detail. However, biological processes cannot be fully understood based on the properties of individual genes and molecules alone, since these elements act in concert to enable the specific functions that make for living cells and organisms. The discipline of systems biology provides a novel conceptual framework for understanding biological phenomenon. Systems biology synthesizes information concerning the interactions of genes and molecules and allows characterization of the supramolecular networks and functional modules that represent the most essential aspects of cell organization and physiology.

Genetic variation in C-reactive protein in relation to colon and rectal cancer risk and survival

C-reactive protein (CRP), a biomarker of inflammation, has been shown to be influenced by genetic variation in the CRP gene. In this study, we test the hypothesis that genetic variation in CRP influences both the risk of developing colon and rectal cancer and survival. Two population-based studies of colon cancer (n = 1,574 cases, 1,970 controls) and rectal (n = 791 cases, 999 controls) were conducted. We evaluated four CRP tagSNPs: rs1205 (G > A, 3' UTR); rs1417938 (T > A, intron); rs1800947 (G > C, L184L); and rs3093075 (C > A, 3' flanking). The CRP rs1205 AA genotype was associated with an increased risk of colon cancer (OR 1.3, 95%CI 1.1-1.7), whereas the rs3093075 A allele was associated with a reduced risk of rectal cancer (OR 0.7, 95%CI 0.5-0.9). The strongest association for the rs1205 polymorphism and colon cancer was observed among those with KRAS2 mutations (OR 1.5, 95%CI 1.1-2.0). The CRP rs1205 AA genotype also was associated with an increased risk of CIMP+ rectal tumors (OR 2.5, 95%CI 1.2-5.3); conversely, the rs1417938 A allele was associated with a reduced risk of CIMP+ rectal tumors (OR 0.5, 95%CI 0.3-0.9). We observed interactions between CRP rs1800947 and BMI and family history of CRC in modifying risk of both colon and rectal cancer. These data suggest that genetic variation in the CRP gene influences risk of both colon and rectal cancer development.

Consumption of Purple/Blue Produce Is Associated With Increased Nutrient Intake and Reduced Risk for Metabolic Syndrome: Results From the National Health and Nutrition Examination Survey 1999-2002

To determine the effect of consuming purple/blue fruit and vegetables (P/B) on nutrient intakes and physiological parameters, a secondary analysis of National Health and Nutrition Examination Survey (NHANES) 1999-2002 data for children aged 5 to 18 years (n = 6345) and adults 19+ years (n = 8827) was conducted. Compared with nonconsumers (n = 13 304), P/B consumers (n = 1559) had increased intakes of total fruit (P < .0001), dietary fiber (P ≤ .0001), vitamin C (P < .001), and potassium (P < .0001) and decreased intakes of added sugar (P < .0001). P/B consumers had higher energy intakes (P < .001), but among children, there were no differences in weight or body mass index (BMI) for age between groups; among adults, lower weight and BMI (P < .0001) were found as compared with nonconsumers. Adult P/B consumers had significantly reduced risk for 3 of the 5 risk factors that define the metabolic syndrome (MetS): elevated blood pressure, low HDL cholesterol, and increased waist circumference. An additional analysis for the subgroup of 100% grape juice (GJ) consumers was conducted. GJ consumers (n = 270) also had higher intakes of fruit (P < .001), vitamin C (P < .001), and potassium (P < .005) and lower intakes of added sugar (P < .01) compared with GJ nonconsumers (n = 14 902), with no differences in weight, BMI, or waist circumference. Consumption of P/B produce was associated with increased fruit and nutrient intakes and with reduced risk for MetS. GJ consumption was also associated with increased nutrient intake.

The CRP genotype, serum levels and lung function in men: the Caerphilly Prospective Study

Systemic CRP (C-reactive protein) has been associated with impaired lung function. A causal relationship would increase the value of CRP as both a diagnostic and therapeutic tool. We assessed the association between lung function parameters, circulating CRP and CRP polymorphisms using Mendelian randomization in efforts to attribute causality to known associations. Spirometric parameters of FEV1 (forced expiratory volume in 1 s) and FVC (forced vital capacity) were determined in 2173 men participating in the Caerphilly Prospective Study. Lung function measures on 1021 participants were available at follow-up (mean, 16.8 years later). Serum CRP levels were measured at baseline, and three CRP polymorphisms were analysed. Haplotype analysis was performed. Serum CRP levels at baseline were inversely associated with contemporaneous FEV1 and FVC as well as at follow-up (P<0.001) even after adjustment for conventional confounders. Serum CRP was associated with FEV1 decline (P=0.04). All three CRP polymorphisms (rs1800947, rs1130864 and rs1205) predicted serum CRP; however, there were no clear associations of the polymorphisms or haplotypes with lung function or with lung function decline. In conclusion, serum CRP was associated with lung function cross-sectionally; however, CRP polymorphisms were not associated with lung function or decline, suggesting that the CRP-lung function relationship is due to reverse causality, an unmeasured confounding factor or only has a modest causal effect.

Association between adolescent emotional problems and metabolic syndrome: the modifying effect of C-reactive protein gene (CRP) polymorphisms

Depression is associated with the development of the metabolic syndrome, and both depression and metabolic syndrome are associated with markers of systemic inflammation, such as C-reactive protein (CRP). We examined associations between affective status in adolescence and adulthood, and the metabolic syndrome at age 53 years in a large representative British birth cohort. We also investigated whether two CRP gene polymorphisms (rs1205 and rs3093068) were associated with affective status and the metabolic syndrome, and whether the association between affective status and the metabolic syndrome was modified by these CRP polymorphisms. Women, but not men, with emotional problems in adolescence were more likely to have the metabolic syndrome (OR=1.53, 95% CI: 1.04, 2.26), although this sex difference was not statistically significant (p=0.22). The CRP SNPs were not associated with affective status or the metabolic syndrome, but the association of adolescent emotional problems with the metabolic syndrome was stronger in those who were homozygous for the major allele (C) of rs1205 (OR=1.83, 95% CI: 1.17, 2.86) than in carriers of the T allele (OR=1.01, 95% CI: 0.66, 1.55) (p=0.05 for gene by affective status interaction). This interaction was stronger when considering adolescent emotional problems as a continuous variable (p=0.003). Adolescent emotional problems play an important role in the development of the metabolic syndrome later in life, particularly in those homozygous for the major allele of CRP rs1205. These findings may highlight new ways of identifying people with emotional problems at high risk of developing the metabolic syndrome, which is of great importance for the management of the physical health of these patients.

C-reactive protein polymorphisms are associated with the cortisol awakening response in basal conditions in human subjects

Cortisol affects the acute-phase response, but it is unknown whether C-reactive protein (CRP), an acute-phase reactant, also affects hypothalamus?pituitary?adrenal axis activity. In the present study, associations were explored between CRP haplotypes with plasma CRP concentrations and basal salivary cortisol level. We included 266 physically healthy Caucasian subjects (103 females and 163 males) aged between 18 and 65 years of whom 94 had a psychiatric disorder in a genetic association study. Six tag single-nucleotide polymorphisms capturing the common genetic variation of the CRP gene were genotyped (i.e. rs2808628, rs2808630, rs1205, rs1800947, rs1417938, and rs3091244) to yield common CRP haplotypes. Plasma CRP concentrations, the salivary cortisol awakening response (CAR) (0, 30, 45, and 60?min after awakening), and the diurnal cortisol decline (11:00, 15:00, 19:00, and 23:00 h) were assessed for 2 days. rs2808628, rs1205, rs1417938, and rs3091244 showed expected associations not only with CRP concentrations, but also with salivary cortisol levels during the CAR. Five well-characterized CRP haplotypes were arranged in ascending order according to increasing CRP levels. There was an inverse linear association between CRP haplotypes and cortisol levels during the CAR, but no association with the diurnal cortisol decline. Hence, genetic variants in the CRP gene that are associated with lifetime plasma CRP levels were also associated with salivary cortisol levels after awakening, in basal, non-inflammatory conditions.

Association of C-reactive protein gene polymorphisms and colorectal cancer

BACKGROUND

An elevated plasma level of C-reactive protein (CRP) is a risk for, and prognostic factor of, colorectal cancer (CRC). In other reports of CRP concerning cardiovascular disease, CRP level correlated with its gene polymorphisms. We hypothesized that CRP polymorphisms associate risk and prognosis of CRC.

METHODS

This study enrolled 421 patients with CRC and 218 healthy control subjects. After preliminary studies, we selected four single nucleotide polymorphisms (SNPs) in the CRP gene: +2147A > G (rs1205), +942G > C (rs1800947), -717A > G (rs2794521), and -757T > C (rs3093059). At first, analyzing distributions of four SNPs between CRC case and non-CRC control groups was performed. Subsequently, the impacts of these SNPs with other prognostic factors of disease-free interval (DFI) and cancer-specific survival (CSS) were analyzed using uni- and multivariate Cox regression analyses.

RESULTS

The case and control groups differed in the frequency of -757T > C (P = 0.002). The CRC case group had a higher percentage of the TT genotype (odds, 1.75). Regarding prognoses, multivariate analyses revealed that four factors, including stage (I, II, III), gross tumor type (polypoid, ulcerative, infiltrative), location (right, left, rectum), and -757T > C SNP (odds, 1.29; P = 0.048), correlated with DFI; two factors, including stage and +2147A > G SNP (odds, 0.71; P = 0.03), correlated with CSS.

CONCLUSIONS

The -757T > C SNP is a risk for and prognostic factor of DFI; the +2147A > G SNP is a prognostic factor of CSS. CRP polymorphisms associate the risk and survival of CRC.

Inflammation and immune system alterations in frailty

Frailty is an important geriatric syndrome characterized by multisystem dysregulation. Substantial evidence suggests heightened inflammatory state and significant immune system alterations in frailty. A heightened inflammatory state is marked by increases in levels of inflammatory molecules (interleukin 6 and C-reactive protein) and counts of white blood cell and its subpopulations, which may play an important role in the pathogenesis of frailty, directly or through its detrimental influence on other physiologic systems. Alterations in the innate immune system include decreased proliferation of the peripheral blood mononuclear cells and upregulated monocytic expression of specific stress-responsive inflammatory pathway genes. In the adaptive immune system, although little information is available about potential B-cell changes, significant alterations have been identified in the T-cell compartment, including increased counts of CD8+, CD8+CD28-, CCR5+T cells, above and beyond age-related senescent immune remodeling.

Prebiotic evaluation of cocoa-derived flavanols in healthy humans by using a randomized, controlled, double-blind, crossover intervention study

BACKGROUND

The absorption of cocoa flavanols in the small intestine is limited, and the majority of the flavanols reach the large intestine where they may be metabolized by resident microbiota.

OBJECTIVE

We assessed the prebiotic potential of cocoa flavanols in a randomized, double-blind, crossover, controlled intervention study.

DESIGN

Twenty-two healthy human volunteers were randomly assigned to either a high-cocoa flavanol (HCF) group (494 mg cocoa flavanols/d) or a low-cocoa flavanol (LCF) group (23 mg cocoa flavanols/d) for 4 wk. This was followed by a 4-wk washout period before volunteers crossed to the alternant arm. Fecal samples were recovered before and after each intervention, and bacterial numbers were measured by fluorescence in situ hybridization. A number of other biochemical and physiologic markers were measured.

RESULTS

Compared with the consumption of the LCF drink, the daily consumption of the HCF drink for 4 wk significantly increased the bifidobacterial (P < 0.01) and lactobacilli (P < 0.001) populations but significantly decreased clostridia counts (P < 0.001). These microbial changes were paralleled by significant reductions in plasma triacylglycerol (P < 0.05) and C-reactive protein (P < 0.05) concentrations. Furthermore, changes in C-reactive protein concentrations were linked to changes in lactobacilli counts (P < 0.05, R(2) = -0.33 for the model). These in vivo changes were closely paralleled by cocoa flavanol-induced bacterial changes in mixed-batch culture experiments.

CONCLUSION

This study shows, for the first time to our knowledge, that consumption of cocoa flavanols can significantly affect the growth of select gut microflora in humans, which suggests the potential prebiotic benefits associated with the dietary inclusion of flavanol-rich foods. This trial was registered at clinicaltrials.gov as NCT01091922.

Inflammatory gene variants in the Tsimane, an indigenous Bolivian population with a high infectious load

The Tsimane of lowland Bolivia are an indigenous forager-farmer population living under conditions resembling pre-industrial European populations, with high infectious morbidity, high infection and inflammation, and shortened life expectancy. Analysis of 917 persons ages 5 to 60+ showed that allele frequencies of 9 SNPs examined in the apolipoprotein E (apoE), C-reactive protein (CRP), and interleukin-6 (IL-6) genes differed from some European, African, and north Asian-derived populations. The apoE2 allele was absent, whereas four SNPs related to CRP and IL-6 were monomorphic: CRP (rs1800947, rs3093061, and rs3093062) and IL-6 (rs1800795). No significant differences in apoE, CRP, and IL-6 variants across age were found CRP levels were higher in carriers of two CRP proinflammatory SNPs, whereas they were lower in carriers of apoE4. Taken together the evidence for (1) different allele frequencies between the Tsimane and other populations and (2) the correlations of CRP and apoE alleles with blood CRP may suggest that these variants are under selection in response to a high infection environment.

Combined effect of C-reactive protein gene SNP +2147 A/G and interleukin-6 receptor gene SNP rs2229238 C/T on anthropometric characteristics among school children in Taiwan

OBJECTIVE

The purpose of this study was to explore the combined effect of the C-reactive protein (CRP) +2147 A/G (rs1205) and interleukin (IL)-6R rs2229238 C/T single-nucleotide polymorphisms (SNPs) on the anthropometric variables of school children in Taiwan.

SUBJECTS AND DESIGN

Cross-sectional analyses were performed using the data from the Taipei Children Heart Study-II. After multi-stage sampling, we selected 430 boys and 463 girls with an average age of 13.1 years. We genotyped these individuals for the CRP +2147 A/G and IL-6R rs2229238 C/T SNPs using a TaqMan 5' nuclease assay. Anthropometric characteristics, which included body height, body weight (BW), body mass index (BMI), waist circumference (WC), hip circumference (HC), body fat percentage (BF), and waist circumference to height ratio (WHtR), were measured/calculated.

RESULTS

When considering the CRP +2147 A/G polymorphism, GG genotype boys were heavier and had larger BMI, WC, HC, BF and WHtR than A allele carriers. The odds ratio (OR) of larger WHtR in GG genotype boys was 2.14 (95% CI: 1.09-4.21). For the IL-6R rs2229238 C/T polymorphism, T allele carrier girls had larger WC and WHtR than those carrying the CC genotype. The OR of a larger HC for T allele carrier boys was 2.33 (95% CI: 1.16-4.68). Boys with the GG genotype of CRP +2147 A/G and the CC genotype of IL-6R rs2229238 C/T had higher OR for BW, BMI, WC, HC, BF and WHtR than boys who were carriers of the A allele of CRP +2147 A/G and had the CC genotype of IL-6R rs2229238 C/T (OR range=3.86-8.04, all P<0.05).

CONCLUSION

Boys who carry the GG genotype of CRP +2147 A/G and the CC genotype of IL-6R rs2229238 C/T have a greater risk of having abnormal BW, BMI, WC, HC, BF and WHtR and of developing obesity than individuals who do not have these genotypes.

Risk stratification of severe acute rhinosinusitis unresponsive to oral antibiotics

CONCLUSIONS

C-reactive protein (CRP) levels may predict the extent of acute rhinosinusitis disease in the computed tomography (CT) scans, as well as the specific symptom severity. High levels may direct the physician to change the treatment.

OBJECTIVE

To establish tools to define 'high risk' patients suffering from acute rhinosinusitis.

METHODS

Patients suffering from severe unresponsive acute rhinosinusitis filled in health-related quality of life questionnaires and rated their symptoms. Blood tests and CT scans were performed. We examined the value of imaging and inflammatory markers, especially CRP, as predictors of disease severity, defined by subjective and objective means; need for surgery; and occurrence of ocular complications.

RESULTS

Thirty-two patients were prospectively recruited. A significant association was found between CRP levels, imaging scores, and symptoms severity. Neither ocular complications nor the need for surgery were present in the group with low CRP level.

C-reactive protein and venous thromboembolism: causal or casual association?

The plasma concentration of C-reactive protein (CRP), the first acute-phase protein to be identified, increases dramatically following tissue injury or inflammation. Although the physiological role of CRP is still not fully known, it has been suggested that concentrations might increase as part of the acute-phase response for facilitating non-specific immune functions, defense against bacterial pathogens, clearance of apoptotic and necrotic cells to prevent immunization against autoantigens and acceleration of the repair process. In agreement with the evidence that inflammation plays a pivotal role in the pathogenesis of atherosclerosis, CRP concentrations have been associated with cardiovascular disease, and measurement of CRP has therefore been proposed as a valuable aid to predict and stratify the risk of myocardial infarction and stroke. Recently, some clinical and biological evidence in support of the hypothesis that CRP might be also involved in the onset of venous thrombosis have emerged. Native and monomeric CRP exert several prothrombotic activities, including activation of blood coagulation, impairment of the endogenous fibrinolytic capacity, and stimulation or enhancement of platelet adhesiveness and responsiveness. Epidemiological investigations have also shown that CRP concentrations are associated with increased risk of venous thromboembolism and, even more interestingly, that statins might be effective in reducing the risk of this pathology. Although there is increasing emphasis that CRP might not only be a marker but also an active player in the development of venous thrombosis, further evidence is needed to establish which event comes first--thrombosis or inflammation.

Association between mannose-binding lectin, high-sensitivity C-reactive protein and the progression of diabetic nephropathy in type 1 diabetes

AIMS/HYPOTHESIS

Diabetic nephropathy has been associated with low-grade inflammation and activation of the complement system in cross-sectional studies. Data from prospective studies are sparse. We investigated the associations of the complement activator mannose-binding lectin (MBL) and the inflammatory marker high-sensitivity C-reactive protein (hsCRP) with the development of nephropathy in a large prospective study of patients with type 1 diabetes from the Finnish Diabetic Nephropathy (FinnDiane) Study.

METHODS

Baseline MBL and hsCRP were measured in 1,564 type 1 diabetes patients from the FinnDiane study, of whom 1,010 had a normal albumin excretion rate, 236 had microalbuminuria and 318 had macroalbuminuria. The main outcome was progression in renal disease during follow-up.

RESULTS

Both baseline MBL (p = 0.038) and hsCRP (p < 0.001) increased with increasing level of albuminuria. During 5.8 +/- 2.2 years of follow-up, progression to a higher albuminuria level or end-stage renal disease (ESRD) occurred in 201 patients. MBL levels were higher in progressors compared with non-progressors at all steps of progression, and in a covariate adjusted multivariate Cox-regression analysis MBL levels above the median were significantly associated with progression from macroalbuminuria to ESRD (hazard ratio 1.88, 95% CI 1.06-3.32, p = 0.030). In a univariate analysis, hsCRP levels above the median were significantly associated with progression from normal albumin excretion rate to microalbuminuria, but the association was only borderline significant after adjustment for covariates (hazard ratio 1.56, 95% CI 0.97-2.51, p = 0.068).

CONCLUSIONS/INTERPRETATION

This study demonstrates that concentrations of both MBL and hsCRP are associated with the progression of renal disease in type 1 diabetes.

C-reactive protein at the interface between innate immunity and inflammation

C-reactive protein (CRP), the prototypic acute-phase protein, increases rapidly in response to infection and inflammation. Although CRP was thought to be a passive, nonspecific marker of inflammation, recent studies indicate that CRP plays a key role in the innate immune system by recognizing pathogens and altered self determinants. Activation of complement and interaction with Fcgamma receptors by CRP provides a link between the innate and adaptive immune systems. Recent evidence suggests that CRP is a marker of atherosclerotic disease and may play a role in its induction. However, CRP has an anti-inflammatory role in autoimmune diseases, such as systemic lupus erythematosus. In this article, we review the biological mechanisms by which CRP exerts its effects on the immune system and discuss its role in infection, cardiovascular disease, malignancy and systemic lupus erythematosus.

Genetic polymorphism of the C-reactive protein (CRP) gene and a deep infection focus determine maximal serum CRP level in Staphylococcus aureus bacteremia

C-reactive protein (CRP) is widely used in early detection of sepsis or organ dysfunction. Several single nucleotide polymorphisms (SNPs) in the CRP gene are shown to be associated with variability of basal CRP. To clarify the effect of these SNPs to CRP response in systemic infections, we compared genetic and clinical data on patients with Staphylococcus aureus bacteremia (SAB). Six SNPs in the CRP gene region (rs2794521, rs30912449, rs1800947, rs1130864, rs1205 and rs3093075) were genotyped in 145 patients and analyzed for associations with CRP and various clinical outcomes. We found that the rare minor A-allele of triallelic SNP rs30912449 (C > T > A) and presence of a deep infection focus were strongly associated to the higher maximal CRP during the first week of SAB. Median of the maximal CRP in patients who had the A-minor allele was 282 mg/L (interquartile range [IQR, defined as the difference between the third quartile and the first quartile], 169 mg/L) but only 179 mg/L (IQR, 148 mg/L) in patients without this allele (P = 0.004), and CRP in patients who had deep infection focus was higher 208 mg/L (IQR, 147 mg/L) than in other patients 114 mg/L (IQR, 121 mg/l) (P < 0.0001). Mortality, degree of leucocytosis, time to defervescence or number of deep infections were not affected by CRP gene SNPs. The maximal CRP during the first week in SAB was partly determined by variation in the CRP gene and partly by presence of deep infection focus. This finding suggests cautiousness in interpreting exceptionally high CRPs from SAB patients and comparison between patients.

Genetic polymorphisms and the cardiovascular risk of non-steroidal anti-inflammatory drugs

The cardiovascular safety of cyclooxygenase-2-selective (coxibs) and nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) is of concern, although most users remain free of adverse outcomes. A gene-drug interaction could modulate this cardiovascular risk through prostaglandin synthesis or inflammatory pathways. From an existing acute coronary syndrome cohort (Recurrence and Inflammation in the Acute Coronary Syndromes Study) (n = 1,210), a case-only study was performed by identifying 115 patients exposed to NSAIDs (rofecoxib [n = 43], celecoxib [n = 49], or nonselective NSAIDs [n = 23]) and 345 unexposed patients matched for age, gender, and hospital center. These patients were genotyped for 115 candidate single-nucleotide polymorphisms (SNPs). Statistically significant associations between NSAID exposure and 9 SNPs in 6 genes were observed. Analyzing patients exposed only to coxibs and their matched unexposed cases, significant associations remained for 5 SNPs at 4 loci (prostaglandin-endoperoxide synthase-1 [PTGS1], chromosome 9p21.3, C-reactive protein [CRP], and klotho [KL]). Two independent SNPs from the PTGS1 gene gave similar results under a recessive model, with odds ratios for the association with NSAID exposure of 6.94 (95% confidence interval 1.35 to 35.65, p = 0.016) and 7.11 (95% confidence interval 1.38 to 36.74, p = 0.033). A significant association was also observed for a SNP in the CRP gene (rs1205) (additive odds ratio 1.64, 95% confidence interval 1.18 to 2.27, p = 0.003). In conclusion, these findings suggest that genetic variability may contribute to the susceptibility for acute coronary syndromes observed in some NSAID users. In particular, genetic polymorphisms in the PTGS1 and CRP genes appear to be candidates for a possible gene-drug interaction influencing the acute coronary risk associated with NSAID use, but these findings will require confirmation in larger cohorts.

Type 2 diabetes mellitus and inflammation: Prospects for biomarkers of risk and nutritional intervention

Obesity is a major risk factor for type 2 diabetes mellitus (T2DM), which is a significant health problem worldwide. Active disease is associated with low-grade chronic inflammation resulting in part from the activation of the innate immune system. In obesity, this activation leads to the release of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β and interleukin-6 that block major anabolic cascades downstream of insulin signaling and thus disrupt insulin homeostasis and action. Cytokines also trigger the production of acute-phase reactants such as C-reactive protein, plasminogen activator inhibitor-1, serum amyloid-A, and haptoglobin. The elevated synthesis of pro-inflammatory cytokines and acute-phase proteins (inflammatory network) characterizes the early (or pre-clinical) stages of T2DM and exhibits a graded increase with the disease progression. Current evidence suggests that understanding inflammatory networks can point to new biomarkers that may permit capturing the interaction between genetic and environmental risk factors in the pathogenesis of T2DM. Such biomarkers have a significant public health potential in the prediction of disease occurrence beyond risk factors presently monitored, such as family history, lifestyle assessment and standard clinical chemistry profiles. Furthermore, inflammatory markers may assist in the evaluation of novel strategies for prevention, particularly in relation to micronutrients. This review discusses the current knowledge linking T2DM risk to inflammatory signaling pathways interacting with the innate immunity system and the prospect of inflammatory markers serving as molecular targets for prevention and/or biomarkers for early risk prediction of T2DM. The potential of micronutrients replenishment to improve insulin action by attenuating inflammation is also evaluated in the context of the public health relevance of this approach.

A population-based assessment of blood lead levels in relation to inflammation

BACKGROUND

Some experimental and observational research suggests that inflammation may be an important mediator of lead toxicity. However, lead-induced inflammation has not been well-studied in non-occupationally exposed populations.

METHODS

Using data for 9,145 individuals >or=40 years of age from the National Health and Nutrition Examination Survey 1999-2004, we assessed the association between blood lead levels (BLLs) and C-reactive protein (CRP), fibrinogen, and white blood cell (WBC) count via ordinal logistic regression. We also examined the interaction between BLL and gender in relation to the inflammatory markers.

RESULTS

No evidence for an association between lead exposure and inflammatory markers was observed with odds ratios around or below the null. Although men but not women appeared to be at increased risk of lead-induced inflammation, no consistent dose-response patterns were observed across BLL quintiles.

CONCLUSION

Inflammation does not appear to be an important mediator of lead toxicity.

C-reactive protein-mediated vascular injury requires complement

BACKGROUND

We previously demonstrated that vascular injury-induced neointima formation is exaggerated in human C-reactive protein (CRP) transgenic (CRPtg) compared to nontransgenic (NTG) mice. We now test the hypothesis that complement is required for this effect.

METHODS AND RESULTS

CRPtg and NTG with a normal complement system versus their counterparts lacking expression of complement component 3 (C3) protein (CRPtg/C3(-/-) and NTG/C3(-/-)) underwent carotid artery ligation. Twenty-eight days later, the injured vessels in CRPtg had thicker neointimas and more immunoreactive C3 in the surrounding adventitia compared with NTG. In CRPtg/C3(-/-), there was no increase in neointimal thickness compared with NTG or NTG/C3(-/-). Decreasing human CRP blood levels through administration of a selective antisense oligonucleotide eliminated the depletion of serum C3 associated with vascular injury and reduced immunoreactive C3 in the resultant lesions. In injured vessels, C3 colocalized with F4/80 (macrophage marker), and in vitro, human CRP elicited increased expression of C3 by bone marrow-derived macrophages.

CONCLUSIONS

Human CRP exaggeration of neointima formation in injured mouse carotid arteries associates with decreased circulating C3 and increased tissue-localized C3. C3 elimination or pharmacological reduction of human CRP prevents CRP-driven exacerbation of the injury response. In the CRPtg model system, mouse C3 is essential for the effect of human CRP.

C-reactive protein as a predictor of disease in smokers and former smokers: a review

BACKGROUND

Cigarette smoking is a classical and a major risk factor in the development of several diseases with an inflammatory component, including cardiovascular disease and chronic obstructive pulmonary disease. Improvements in assays for protein markers of inflammation have led to many studies on these factors and their roles in disease.

AIMS

C-reactive protein (CRP) is one such marker and this review focuses on the evidence for using CRP as a diagnostic marker and how levels of this protein are modified according to the smoking status of the patient, both in terms of the current amount of cigarettes smoked and how CRP levels change following smoking cessation.

CONCLUSIONS

Assay of CRP levels may be useful in monitoring disease progression and determining risk of future cardiovascular complications. However, as this marker is also an indicator of acute inflammation and challenges to the immune system, some caution must be exercised in interpreting the available data on CRP levels in patients with different chronic comorbidities.

Angiotensin-II receptor antagonist combined with calcium channel blocker or diuretic for essential hypertension

To achieve the target blood pressure recommended by the latest guidelines, multiple antihypertensive drugs are needed in most patients. In this study, the efficacy of treatment using an angiotensin II receptor antagonist (ARB) combined with a calcium channel blocker (CCB) or a diuretic was compared from multiple perspectives in patients with hypertension. Twenty-nine patients with essential hypertension, who had failed to achieve their target blood pressure (<130/85 mm Hg for patients <65 years old and <140/90 mm Hg for those >/=65 years) when treated with the ARB olmesartan at 20 mg day(-1), were additionally given 8-16 mg day(-1) of the CCB azelnidipine or 1-2 mg day(-1) of trichlormethiazide (a thiazide diuretic) in a randomized crossover manner for 4 months each. At the end of each combination therapy period, blood and urine samples were collected and arterial stiffness was evaluated by measuring the cardio-ankle pulse wave velocity. Compared with monotherapy, the blood pressure was reduced similarly by adding azelnidipine (-12/-10 mm Hg) or trichlormethiazide (-14/-9 mm Hg). The heart rate was decreased with the CCB by 4 b.p.m. (P<0.05), whereas it was unchanged with the thiazide. Serum K, lipids and blood glucose were not significantly changed with either combination, whereas serum uric acid was increased with the thiazide (P<0.01) but was unchanged with azelnidipine. Plasma levels of renin, angiotensin II and aldosterone were also increased with the thiazide period, whereas high-sensitivity C-reactive protein and oxidized low-density lipoprotein were decreased with azelnidipine. In addition, the cardio-ankle vascular index, a parameter of arterial stiffness, was decreased with the azelnidipine period but was unchanged with the thiazide period (P<0.01). It is suggested that the combination of olmesartan and azelnidipine has advantages over the combination of olmesartan and a thiazide with respect to avoiding hyperuricemia, sympathetic activation, renin-angiotensin-aldosterone system stimulation, inflammation, oxidative stress, and increased arterial stiffness in patients with moderate hypertension. These properties may provide cardiovascular protection in addition to the hypotensive effect.

Inflammation and infection do not promote arterial aging and cardiovascular disease risk factors among lean horticulturalists

Background

Arterial aging is well characterized in industrial populations, but scantly described in populations with little access to modern medicine. Here we characterize health and aging among the Tsimane, Amazonian forager-horticulturalists with short life expectancy, high infectious loads and inflammation, but low adiposity and robust physical fitness. Inflammation has been implicated in all stages of arterial aging, atherogenesis and hypertension, and so we test whether greater inflammation associates with atherosclerosis and CVD risk. In contrast, moderate to vigorous daily activity, minimal obesity, and low fat intake predict minimal CVD risk among older Tsimane.

Methods and Findings

Peripheral arterial disease (PAD), based on the Ankle-Brachial Index (ABI), and hypertension were measured in Tsimane adults, and compared with rates from industrialized populations. No cases of PAD were found among Tsimane and hypertension was comparatively low (prevalence: 3.5%, 40+; 23%, 70+). Markers of infection and inflammation were much higher among Tsimane than among U.S. adults, whereas HDL was substantially lower. Regression models examine associations of ABI and BP with biomarkers of energy balance and metabolism and of inflammation and infection. Among Tsimane, obesity, blood lipids, and disease history were not significantly associated with ABI. Unlike the Tsimane case, higher cholesterol, C-reactive protein, leukocytes, cigarette smoking and systolic pressure among North Americans are all significantly associated with lower ABI.

Conclusions

Inflammation may not always be a risk factor for arterial degeneration and CVD, but instead may be offset by other factors: healthy metabolism, active lifestyle, favorable body mass, lean diet, low blood lipids and cardiorespiratory health. Other possibilities, including genetic susceptibility and the role of helminth infections, are discussed. The absence of PAD and CVD among Tsimane parallels anecdotal reports from other small-scale subsistence populations and suggests that chronic vascular disease had little impact on adult mortality throughout most of human evolutionary history.

Periodontitis-associated up-regulation of systemic inflammatory mediator level may increase the risk of coronary heart disease

BACKGROUND AND OBJECTIVE

Although an elevation in the concentration of high-sensitivity C-reactive protein (hs-CRP) as a result of periodontal infection may account for an increased risk of developing coronary heart disease (CHD), the effect of periodontal infection on the level of hs-CRP in an otherwise healthy Japanese population has not yet been reported. The aim of the present study was to confirm, on a larger scale, our previous pilot study findings that both chronic periodontitis and subsequent periodontal treatment alter the serum levels of C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha).

MATERIAL AND METHODS

The concentrations of serum hs-CRP, IL-6 and TNF-alpha were measured in 78 periodontitis patients at baseline and at re-assessment, and in 40 periodontally healthy subjects at the time of examination.

RESULTS

The concentrations of hs-CRP and IL-6 in the sera of periodontitis patients were significantly higher than those in control subjects. By contrast, the concentration of TNF-alpha was significantly lower in periodontitis patients than in control subjects. Whereas periodontal treatment decreased the levels of serum hs-CRP and IL-6, no such effect was observed for TNF-alpha. When the patients were subdivided into four groups according to their initial concentration of hs-CRP, only the CRP and IL-6 concentrations of the highest quartile group showed a significant reduction following periodontal treatment. No significant difference in the initial clinical parameters was observed in any quartile.

CONCLUSION

Although periodontal infection does affect the concentration of hs-CRP and IL-6 in serum, a subgroup of patients exist who are highly susceptible to an increased risk of CHD associated with periodontitis, suggesting that there may be subjects who have an elevated risk of CHD independent of susceptibility to periodontal tissue destruction per se.

Marked differences in CRP genotype frequencies between the Fulani and sympatric ethnic groups in Africa

Background

C-reactive protein (CRP) is an acute phase protein that can activate various immune cells and bind to certain Fcγ receptors. The latter may compete with the binding of IgG antibodies to these receptors and could thereby interfere with the antigen-specific immune response. Polymorphisms in the promoter region of the CRP gene have been strongly associated with the plasma concentration of CRP. The known lower susceptibility to malaria in the Fulani ethnic group, as compared to their sympatric neighbours in Africa, has been linked to different genetic backgrounds. The present study was performed to investigate if polymorphisms in the CRP gene could contribute to the lower susceptibility to malaria seen in the Fulani ethnic group.

Methods

The CRP -717 T>C, -286 C>T>A, and +1444 C>T polymorphisms were analysed in asymptomatic Fulani and non-Fulani individuals from Mali and Sudan using Pyrosequencing T and TaqMan r MGB probes.

Results

The rare -286 A allele, previously shown to be associated with increased CRP expression and plasma levels, was shown to be more frequent in the non-Fulani ethnic groups as compared to the sympatric Fulani ethnic group both in Mali and Sudan. The common -717 T allele was more prevalent in the non-Fulani ethnic group compared to the sympatric Fulani ethnic group, but only in Mali. The parasite prevalence was increased for the -286 A allele, but not for the -717 T allele. No differences regarding genotype frequency or parasite prevalence were seen for +1444 C>T.

Conclusion

This study indicate that CRP may play an important role in the immune responses to malaria, and that the -286 C/T/A CRP polymorphism may be a contributing factor to the lower susceptibility to malaria seen in the Fulani.

C-Reactive protein gene variants are associated with postoperative C-reactive protein levels after coronary artery bypass surgery

Background

Elevated baseline C-reactive protein (CRP) levels are associated with increased risk for developing cardiovascular disease. Several CRP gene variants have been associated with altered baseline CRP levels in ambulatory populations. However, the influence of CRP gene variants on CRP levels during inflammatory states, such as surgery, is largely unexplored. We describe the association between candidate CRP gene variants and postoperative plasma CRP levels in patients undergoing primary, elective coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB).

Methods

Using a multicenter candidate gene association study design, we examined the association between seventeen candidate CRP single nucleotide polymorphisms (SNPs) and inferred haplotypes, and altered postoperative CRP levels in 604 patients undergoing CABG surgery with CPB. Perioperative CRP levels were measured immediately prior to surgery, post-CPB and on postoperative days (POD) 1–4.

Results

CRP levels were significantly elevated at all postoperative time points when compared with preoperative levels (P < 0.0001). After adjusting for clinical covariates, the minor allele of the synonymous coding SNP, rs1800947 was associated with lower peak postoperative CRP levels (P = 2.4 × 10^-4) and lower CRP levels across all postoperative time points (P = 4.8 × 10^-5). rs1800947 remained highly significant after Bonferroni adjustment for multiple comparisons.

Conclusion

We identified a CRP gene SNP associated with lower postoperative CRP levels in patients undergoing CABG surgery with CPB. Further investigation is needed to clarify the significance of this association between CRP gene variants and the acute-phase rise in postoperative CRP levels with regard to the risk of adverse postoperative outcomes.

Plasma C-reactive protein is related to cognitive deterioration and dementia in patients with mild cognitive impairment

OBJECTIVE

To investigate the relationship between plasma C-reactive protein (CRP) and the risk for cognitive deterioration and development of dementia in patients with mild cognitive impairment (MCI).

METHODS

Elderly Chinese patients with suspected cognitive impairment were screened. A total of 168 patients who met the criteria for MCI were enrolled. Plasma CRP levels were measured at baseline. The global cognitive functions were assessed at baseline and during follow-up periodically with Mini-Mental State Examination (MMSE). All enrolled patients were followed and evaluated regularly for 2 years to determine if the patients developed dementia.

RESULTS

Of the 168 patients with MCI diagnosed at baseline, 14 (8.3%) deceased, 13 (7.7%) lost to follow-up, and 58 (34.5%) developed dementia during follow-up. MMSE score of the enrolled patients declined significantly during follow-up (22.1 +/- 3.0 vs 18.6 +/- 5.5, P < 0.001). MMSE score was significantly lower for the patients with high CRP levels than that for those with low plasma CRP levels (-4.9 +/- 5.4 vs -3.2 +/- 4.2, P < 0.05). Patients with high plasma CRP level had an increased risk for dementia and vascular dementia as compared with patients with low level of plasma CRP (Log rank test, P < 0.05).

CONCLUSION

High plasma CRP level was associated with accelerated cognitive decline and increased risk for dementia in patients with MCI.

Epidemiology of ischemic and hemorrhagic stroke: incidence, prevalence, mortality, and risk factors

The epidemiology of ischemic and hemorrhagic stroke is an ongoing exploration to identify risk factors that continue to expand with the advent of technological advancements and preventative medical practices. Identification of risk factors that can or cannot be modified is a crucial step in determining stroke risk. Many of the modifiable risk factors are well established, and specific interventions to reduce stroke risk have been established. Some risk factors are less established, and intervention to reduce risk is yet to be determined by evidence-based medicine. Data from ongoing randomized clinical trials continue to enhance our ability to prevent a first stroke.

Hepatic nuclear factor 1-alpha: inflammation, genetics, and atherosclerosis

PURPOSE OF REVIEW

Increased plasma levels of C-reactive protein (CRP), a hepatic acute phase reactant, predict risk for coronary heart disease. There has been interest in identifying genetic determinants of CRP as a means of better understanding its regulation and its relation to coronary heart disease. We here review recent findings that have linked plasma CRP levels to single nucleotide polymorphisms in hepatic nuclear factor (HNF) 1-alpha, a transcription factor with a wide range of functions, including many involved in cholesterol, bile acid, and lipoprotein metabolism.

RECENT FINDINGS

Two genome-wide association studies have identified single nucleotide polymorphisms in several genes that are strongly related to plasma CRP levels, including several on chromosome 12 in the vicinity of the HNF1A gene. The CRP gene promoter has two HNF1-alpha-binding sites. Recently, it has been demonstrated that HNF1-alpha is required for cytokine-driven CRP expression and that this involves formation of a complex with STAT3 and c-Fos.

SUMMARY

Based on the recent genetic findings as well as delineation of the role of HNF1-alpha in regulating the expression of the CRP gene, it appears that this transcription factor may play a key role in linking metabolic and inflammatory pathways underlying the pathogenesis of coronary heart disease.

Association of peripheral inflammatory markers with chronic fatigue in a population-based sample

Alterations in the innate immune response may contribute to the pathogenesis of chronic fatigue syndrome (CFS). However, studies have been limited by small sample sizes, use of patients from tertiary care settings, inappropriate selection of controls, and failure to control for confounding demographic, medical and behavioral factors independently associated with immune activity. It is also not known whether specific symptoms account for observed associations between CFS and the innate immune response. To address these limitations, the current study examined plasma concentrations of high-sensitivity c-reactive protein (hs-CRP), white blood cell count (WBC) and a combined inflammation factor in a large population-based sample. Log-transformed mean plasma concentrations of hs-CRP were increased in subjects with CFS (n=102) and in subjects with unwellness symptoms that did not meet diagnostic criteria for CFS (defined as "insufficient fatigue" [ISF]) (n=240) when compared to subjects who were well (n=115). Log transformed WBC was increased in ISF and was increased at a trend level in CFS. The combined inflammation factor was increased in both CFS and ISF. Subjects with CFS and ISF did not differ on any of the inflammation measures. In the entire subject population, the physical component summary score (PCS), but not the mental component summary score (MCS), from the Medical Outcomes Study Short Form-36 (SF-36) was negatively associated with each of the inflammation measures. Depressive symptoms were also associated with increased log hs-CRP. After adjustment for age, sex, race, location of residence, BMI, depressive status and immune-modulating medications, subjects classified as ISF continued to demonstrate increased log hs-CRP, WBC and elevations on the inflammation factor when compared to well controls; however, associations between CFS and log hs-CRP and the inflammation factor were no longer statistically significant. After adjustment, PCS score also remained independently associated with each of the inflammation measures. These findings support a role for innate immune activation in unexplained fatigue and unwellness, but do not suggest that immune activation is specific to CFS.

Association of the FTO rs9939609 single nucleotide polymorphism with C-reactive protein levels

Adipose tissue is a key factor determining C-reactive protein (CRP) plasma levels. Variation at the fat-mass and obesity-associated (FTO) gene locus has been reported to be associated with increased body fat. We investigated whether the FTO rs9939609 T>A single nucleotide polymorphism might alter CRP levels in a population-based sample of 2,415 participants from a large prospective cohort study. Genotype/phenotype relationships were studied by linear trend analysis stratified by sex. The rs9939609 A-allele was significantly associated with CRP levels in both genders (men, +21%, P = 0.002; women, +14%, P = 0.01 per A-allele). The association was attenuated, but remained statistically significant after additional adjustment for BMI, waist-to-hip ratio, and other potential confounding factors (men, +14%, P = 0.03; women, +12%, P = 0.02; per A-allele). Similar results were obtained when subjects with CRP levels higher then 10 mg/l were excluded. Our data provide preliminary evidence that the FTO rs9939609 T>A polymorphism contributes to variation in plasma CRP levels independently of obesity indices.

The interaction of adiposity with the CRP gene affects CRP levels: age, gene/environment susceptibilty-Reykjavik study

OBJECTIVE

Common diseases often have an inflammatory component reflected by associated markers such as serum C-reactive protein (CRP) levels. Circulating CRP levels have also been associated with adipose tissue as well as with specific CRP genotypes. We examined the interaction between measures of body mass index (BMI), waist circumference and fat percent (total fat measured by bioimpedance) with genotypes of the CRP gene in the determination of CRP levels.

METHODS

The first 2296 participants (mean age 76+/-6 years, 42% men) in the Age, Gene/Environment Susceptibility-Reykjavik Study, a multidisciplinary epidemiological study to determine risk factors in aging, were genotyped for 10 single nucleotide polymorphisms (SNPs) in the CRP gene. General linear models with age and terms for interaction of CRP genotypes with BMI, waist circumference and percent fat were used to evaluate the association of genotypes to CRP levels (high-sensitivity method, range 0-10 mg l(-1)) in men and women separately.

RESULTS

We focused on the SNP rs1205 that represents the allele that captures the strongest effects of the gene on CRP levels. Carriers of the rs1205 G allele had significantly higher CRP levels than noncarriers in a dose-dependent manner. Compared to the AA genotype, the slope of the increase in CRP with increasing BMI (P=0.045) and waist circumference (P=0.014) was different for the G allele carriers and of similar magnitude in both men and women. The rs1205 interactions were not significant for fat mass percent, suggesting a possible association with fat localization.

CONCLUSIONS

This study further illuminates the known association between measures of adiposity and CRP levels and is shown to be dependent on variation in the rs1205 SNP of the CRP gene. The correlated increase in CRP levels with adiposity is accentuated by presence of the G allele.

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

OBJECTIVE

The level of C-reactive protein (CRP), an inflammatory marker that predicts future cardiovascular events, is a heritable trait. Our aim was to test the statistical associations between variations in the CRP gene and serum CRP levels in a Taiwanese population with interaction analysis.

METHODS

A sample population of 617 Taiwanese subjects was enrolled. Five CRP single nucleotide polymorphisms (SNPs) previously reported to be associated with CRP level and with reasonable coverage of the CRP gene region were analyzed using polymerase chain reaction and restriction enzyme digestion or by TaqMan SNP Genotyping Assays.

RESULTS

After adjusting for clinical covariates, minor alleles of 3 of the 5 SNPs were associated with change in CRP level: rs3091244 and rs1205 were associated with increased CRP level (P=0.001 and P<0.001, respectively) and rs1800947 with decreased CRP level (P=0.003). Two haplotypes inferred from 5 SNPs (GCGCG and AAGCG) were associated with increased CRP level (P=0.017 and P<0.0001, respectively). Interaction analysis revealed interaction of obesity with CRP genotypes associated with high CRP level (interaction P=0.034 and 0.020 for SNPs rs2794521 and rs1800947, respectively). An effect of obesity on CRP level was also noted in haplotype interaction analysis with the association occurring predominantly in obese subjects (P=0.034).

CONCLUSION

CRP polymorphisms are independently associated with increased or decreased CRP level in Taiwanese. Further, CRP genotypes/haplotypes interact with obesity to set CRP level. These findings have implications for the prediction of atherosclerotic disease.

Cardiovascular biomarkers: increasing impact of laboratory medicine in cardiology practice

The practice of cardiology is in continual evolution, in parallel with the progress achieved by medical research in understanding the pathophysiology of cardiovascular disease and in developing new therapeutic procedures. Consequently, manufacturers of cardiac biomarkers are pressed with new demands to improve the performance of the existing and the development of novel ones. Several highly sensitive and/or specific assays for myocardial ischemic damage and myocardial function detection have already become commercially available. Moreover, an increasing number of novel risk factors have been added to the classical risk factors of cardiovascular disease. Finally, the recent surge of genetic analysis procedures will likely soon provide the clinical cardiologist with a number of laboratory tests for defining the molecular diagnosis, assessing new risk factors, and better targeting the pharmaceutical approaches in patients with cardiovascular disease. In this review, we first present the general characteristics of a biomarker followed by the analytical and clinical performance of assay methods.

Inflammatory gene polymorphisms and susceptibility to kawasaki disease and its arterial sequelae

OBJECTIVE

We tested the hypothesis that single-nucleotide polymorphisms of inflammatory genes C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-alpha) may exert influence on susceptibility to Kawasaki disease and its arterial sequelae.

METHODS

We analyzed the CRP +1444 C-->T and TNF-alpha -308 G-->A polymorphisms in 167 patients aged 8.9 +/- 4.1 years with a history of Kawasaki disease (73 with and 94 without coronary aneurysms) and 124 healthy control subjects. For patients with Kawasaki disease, we further determined whether these single-nucleotide polymorphisms were associated with coronary aneurysms, carotid arterial stiffening, and intima-media thickness.

RESULTS

Genotypic and allelic frequencies of CRP +1444 for T carrier and TNF-alpha -308 for A carrier were significantly higher in patients than in control subjects. The genotypic and allelic distributions did not differ between patients with and those without coronary aneurysms; however, patients with CRP +1444 CT/TT genotype compared with those with a CC genotype and patients with TNF-alpha -308 GA/AA genotype compared with those with a GG genotype had significantly greater carotid arterial stiffness and intima-media thickness. Carriers of both CRP +1444 T allele and TNF-alpha -308 A allele had the highest susceptibility to Kawasaki disease and a significant trend of increased arterial stiffness and intima-media thickness compared with those who carried either 1 or none of the rare alleles. Multiple linear regression analysis identified CRP +1444 allele carrier as a significant determinant of both carotid stiffness and carotid intima-media thickness and TNF-alpha -308 A allele carrier as a determinant of only intima-media thickness.

CONCLUSIONS

Our findings suggest that CRP +1444 C-->T and TNF-alpha -308 G-->A polymorphisms are associated with predisposition to Kawasaki disease and, in patients with Kawasaki disease, increased carotid arterial stiffness and intima-media thickness in the long-term.

The association of C-reactive protein and CRP genotype with coronary heart disease: findings from five studies with 4,610 cases amongst 18,637 participants

Background

It is unclear whether C-reactive protein (CRP) is causally related to coronary heart disease (CHD). Genetic variants that are known to be associated with CRP levels can be used to provide causal inference of the effect of CRP on CHD. Our objective was to examine the association between CRP genetic variant +1444C>T (rs1130864) and CHD risk in the largest study to date of this association.

Methods and Results

We estimated the association of CRP genetic variant +1444C>T (rs1130864) with CRP levels and with CHD in five studies and then pooled these analyses (N = 18,637 participants amongst whom there were 4,610 cases). CRP was associated with potential confounding factors (socioeconomic position, physical activity, smoking and body mass) whereas genotype (rs1130864) was not associated with these confounders. The pooled odds ratio of CHD per doubling of circulating CRP level after adjustment for age and sex was 1.13 (95%CI: 1.06, 1.21), and after further adjustment for confounding factors it was 1.07 (95%CI: 1.02, 1.13). Genotype (rs1130864) was associated with circulating CRP; the pooled ratio of geometric means of CRP level among individuals with the TT genotype compared to those with the CT/CC genotype was 1.21 (95%CI: 1.15, 1.28) and the pooled ratio of geometric means of CRP level per additional T allele was 1.14 (95%CI: 1.11, 1.18), with no strong evidence in either analyses of between study heterogeneity (I² = 0%, p>0.9 for both analyses). There was no association of genotype (rs1130864) with CHD: pooled odds ratio 1.01 (95%CI: 0.88, 1.16) comparing individuals with TT genotype to those with CT/CC genotype and 0.96 (95%CI: 0.90, 1.03) per additional T allele (I²<7.5%, p>0.6 for both meta-analyses). An instrumental variables analysis (in which the proportion of CRP levels explained by rs1130864 was related to CHD) suggested that circulating CRP was not associated with CHD: the odds ratio for a doubling of CRP level was 1.04 (95%CI: 0.61, 1.80).

Conclusions

We found no association of a genetic variant, which is known to be related to CRP levels, (rs1130864) and having CHD. These findings do not support a causal association between circulating CRP and CHD risk, but very large, extended, genetic association studies would be required to rule this out.

Polymorphisms of the IL1-receptor antagonist gene (IL1RN) are associated with multiple markers of systemic inflammation

BACKGROUND

Circulating levels of acute phase reactant proteins such as plasma C-reactive protein (CRP) are likely influenced by multiple genes regulating the innate immune response.

METHODS AND RESULTS

We screened a set of 16 inflammation-related genes for association with CRP in a large population-based study of healthy young adults (n=1627). Results were validated in 2 independent studies (n=1208 and n=4310), including a pooled analysis of all 3 studies. In the pooled analysis, the minor allele of IL1RN 1018 (rs4251961) within the gene encoding interleukin (IL)-1 receptor antagonist (IL-1RA) was significantly associated with higher mean plasma log(CRP) level (P<1 x 10(-4)). The same IL1RN 1018 allele was associated with higher mean plasma log(IL-6) levels (P=0.004). In the pooled analysis, the minor allele of IL1RN 13888 (rs2232354) was associated with higher fibrinogen, (P=0.001). The IL1RN 1018 and 13888 variant alleles tag a clade of IL1RN haplotypes linked to allele 1 of an 86-bp VNTR polymorphism. We confirmed that the IL1RN 1018 variant (rs4251961) was associated with decreased cellular IL-1RA production ex vivo.

CONCLUSIONS

Common functional polymorphisms of the IL1RN gene are associated with several markers of systemic inflammation.