Genetically elevated C-reactive protein and ischemic vascular disease

Multimarker prediction of coronary heart disease risk: the Women's Health Initiative

OBJECTIVES

The aim of this study was to investigate whether multiple biomarkers contribute to improved coronary heart disease (CHD) risk prediction in post-menopausal women compared with assessment using traditional risk factors (TRFs) only.

BACKGROUND

The utility of newer biomarkers remains uncertain when added to predictive models using only TRFs for CHD risk assessment.

METHODS

The Women's Health Initiative Hormone Trials enrolled 27,347 post-menopausal women ages 50 to 79 years. Associations of TRFs and 18 biomarkers were assessed in a nested case-control study including 321 patients with CHD and 743 controls. Four prediction equations for 5-year CHD risk were compared: 2 Framingham risk score covariate models; a TRF model including statin treatment, hormone treatment, and cardiovascular disease history as well as the Framingham risk score covariates; and an additional biomarker model that additionally included the 5 significantly associated markers of the 18 tested (interleukin-6, d-dimer, coagulation factor VIII, von Willebrand factor, and homocysteine).

RESULTS

The TRF model showed an improved C-statistic (0.729 vs. 0.699, p = 0.001) and net reclassification improvement (6.42%) compared with the Framingham risk score model. The additional biomarker model showed additional improvement in the C-statistic (0.751 vs. 0.729, p = 0.001) and net reclassification improvement (6.45%) compared with the TRF model. Predicted CHD risks on a continuous scale showed high agreement between the TRF and additional biomarker models (Spearman's coefficient = 0.918). Among the 18 biomarkers measured, C-reactive protein level did not significantly improve CHD prediction either alone or in combination with other biomarkers.

CONCLUSIONS

Moderate improvement in CHD risk prediction was found when an 18-biomarker panel was added to predictive models using TRFs in post-menopausal women.

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.

Evaluating the quality of research into a single prognostic biomarker: a systematic review and meta-analysis of 83 studies of C-reactive protein in stable coronary artery disease

BACKGROUND

Systematic evaluations of the quality of research on a single prognostic biomarker are rare. We sought to evaluate the quality of prognostic research evidence for the association of C-reactive protein (CRP) with fatal and nonfatal events among patients with stable coronary disease.

METHODS AND FINDINGS

We searched MEDLINE (1966 to 2009) and EMBASE (1980 to 2009) and selected prospective studies of patients with stable coronary disease, reporting a relative risk for the association of CRP with death and nonfatal cardiovascular events. We included 83 studies, reporting 61,684 patients and 6,485 outcome events. No study reported a prespecified statistical analysis protocol; only two studies reported the time elapsed (in months or years) between initial presentation of symptomatic coronary disease and inclusion in the study. Studies reported a median of seven items (of 17) from the REMARK reporting guidelines, with no evidence of change over time. The pooled relative risk for the top versus bottom third of CRP distribution was 1.97 (95% confidence interval [CI] 1.78-2.17), with substantial heterogeneity (I(2) = 79.5). Only 13 studies adjusted for conventional risk factors (age, sex, smoking, obesity, diabetes, and low-density lipoprotein [LDL] cholesterol) and these had a relative risk of 1.65 (95% CI 1.39-1.96), I(2) = 33.7. Studies reported ten different ways of comparing CRP values, with weaker relative risks for those based on continuous measures. Adjusting for publication bias (for which there was strong evidence, Egger's p<0.001) using a validated method reduced the relative risk to 1.19 (95% CI 1.13-1.25). Only two studies reported a measure of discrimination (c-statistic). In 20 studies the detection rate for subsequent events could be calculated and was 31% for a 10% false positive rate, and the calculated pooled c-statistic was 0.61 (0.57-0.66).

CONCLUSION

Multiple types of reporting bias, and publication bias, make the magnitude of any independent association between CRP and prognosis among patients with stable coronary disease sufficiently uncertain that no clinical practice recommendations can be made. Publication of prespecified statistical analytic protocols and prospective registration of studies, among other measures, might help improve the quality of prognostic biomarker research.

The influence of growth hormone replacement on peripheral inflammatory and cardiovascular risk markers in adults with severe growth hormone deficiency

BACKGROUND

Adult GHD syndrome is associated with clustering of adverse cardiovascular (CV) risk factors such as abnormal body composition, dyslipidemia, insulin resistance and abnormal haemostatic factors. There is a wealth of evidence linking CV events with elevated levels of inflammatory markers (hs-CRP and IL-6) in the general population; however data on their abnormalities in GHD and specially the effects of GH replacement (GHR) on these inflammatory markers are limited.

OBJECTIVE

To study the effects of GHR on inflammatory markers, glucose homeostasis and body composition in a cohort of adults with recently diagnosed severe GHD due to hypothalamic pituitary disease.

DESIGN

Fifteen hypopituitary adults (11 males, mean age 48.5 years) with recently diagnosed, severe GHD were recruited. Patients received GHR (in addition to other pituitary hormone replacements) titrated to clinical response and to normalize age and gender adjusted IGF-1 levels. Weight, waist hip ratio (WHR), body composition, fasting plasma glucose and insulin, insulin resistance index (HOMA-IR), fasting serum lipid levels, hs-CRP, IL-6 and TNF-alpha were measured at baseline and following a minimum 6 months of stable maintenance GHR.

RESULTS

GHR resulted in a physiological increase in IGF-1 SDS [median -0.6 to +0.39, P<0.0001], improved quality of life (mean pre-treatment AGHDA score 16 vs. post-treatment score 7, P<0.0001) and reduction in WHR (0.94 vs. 0.92, P=0.01). There were no significant changes in body weight and composition. Levels of hs-CRP (log transformed, mean (SD)) were significantly reduced following GHR (pre 1.21 (0.9) vs. post 0.27 (0.9), P<0.0001) but TNF-alpha and IL-6 levels remained unchanged. Fasting glucose (mmol/L) [4.6 (0.1) vs. 5.1 (0.1), P=0.003], fasting insulin (muU/mL) [9.4 (8.1) vs. 12.1 (9.2), P=0.03] and HOMA-IR [1.2 (1.0) vs. 1.5 (1.1) P=0.02] (all pre-GHR vs. post-GHR and mean (SD)) significantly increased following GHR indicating increased insulin resistance. Significant improvements were noted in fasting LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels following GHR [3.4 (0.9) vs. 2.9 (0.7), P=0.03 and 1.2 (0.2) vs. 1.3 (0.2), P=0.02, respectively] (all pre-GHR vs. post-GHR and mean (SD)). Levels of total cholesterol and triglycerides did not change following GHR.

CONCLUSIONS

Physiological GHR for at least 6 months in hypopituitary adults with recently diagnosed severe GHD resulted in favourable changes in hs-CRP, WHR, fasting LDL-C and HDL-C levels all of which are recognised CV risk markers. However, there remains a high prevalence of obesity in this population and given the worsening of insulin sensitivity in the short term with GHR, monitoring and aggressive treatment of established CV risk factors is essential to reduce premature atherosclerotic CVD in this patient population.

C-reactive protein and risk of venous thromboembolism in the general population

OBJECTIVE

To examine the robustness of the association between C-reactive protein (CRP) levels and increased risk of venous thromboembolism (VTE) and to examine whether genetically elevated CRP levels cause VTE.

METHODS AND RESULTS

In the prospective Copenhagen City Heart Study, we observed 10 388 participants for longer than 16 years, of whom 484 developed a VTE. In the cross-sectional Copenhagen General Population Study, we studied 36 616 participants, of whom 903 previously had a VTE. Levels of CRP greater than 3 mg/L versus less than 1 mg/L were associated with a 2.3- and 2.4-fold increased risk of VTE in the Copenhagen City Heart Study and the Copenhagen General Population Study, respectively. CRP levels in tertiles, quintiles, and octiles associated with a stepwise increase in VTE risk. CRP genotypes associated with an increase in plasma CRP levels up to 59% but did not associate consistently with risk of VTE in either study. The causal odds ratio for VTE for a doubling in genetically elevated CRP on instrumental variable analyses was lower than the odds ratio for VTE observed for a doubling in plasma CRP on logistic regression ([odds ratio and 95% CI] 0.80 [0.56 to 1.12] versus 1.17 [1.08 to 1.27]; P=0.04).

CONCLUSIONS

We observed 47,000 participants from the general population, of whom 1387 developed VTE. Although elevated CRP levels robustly associated with increased risk of VTE, this may not necessarily be a causal association because genetically elevated CRP did not associate with VTE risk.

An integrated view of humoral innate immunity: pentraxins as a paradigm

The innate immune system consists of a cellular and a humoral arm. Pentraxins (e.g., the short pentraxin C reactive protein and the long pentraxin PTX3) are key components of the humoral arm of innate immunity which also includes complement components, collectins, and ficolins. In response to microorganisms and tissue damage, neutrophils, macrophages, and dendritic cells are major sources of fluid-phase pattern-recognition molecules (PRMs) belonging to different molecular classes. Humoral PRMs in turn interact with and regulate cellular effectors. Effector mechanisms of the humoral innate immune system include activation and regulation of the complement cascade; agglutination and neutralization; facilitation of recognition via cellular receptors (opsonization); and regulation of inflammation. Thus, the humoral arm of innate immunity is an integrated system consisting of different molecules and sharing functional outputs with antibodies.

Interleukin-1 gene cluster variants with innate cytokine production profiles and osteoarthritis in subjects from the Genetics, Osteoarthritis and Progression Study

OBJECTIVE

To assess whether genetic variation in the interleukin-1 (IL-1) gene cluster contributes to familial osteoarthritis (OA) by influencing innate ex vivo production of IL-1beta or IL-1 receptor antagonist (IL-1Ra).

METHODS

Innate ex vivo IL-1beta and IL-1Ra production upon lipopolysaccharide (LPS) stimulation of whole blood cells was measured in subjects from the Genetics, Osteoarthritis and Progression (GARP) Study, which includes sibling pairs in which at least one sibling has symptomatic OA at multiple sites. Radiographic OA (ROA) was assessed by Kellgren/Lawrence score. Subjects from the GARP Study and controls from the Rotterdam Study were genotyped for 7 single-nucleotide polymorphisms (SNPs) encompassing the IL-1 gene cluster on chromosome 2q13. Linkage disequilibrium analysis and genotype and haplotype association analysis were performed to assess the relationship between the IL-1 gene cluster SNPs, innate ex vivo cytokine production, and OA.

RESULTS

Among subjects in the GARP Study, the haplotype variable-number tandem repeat in intron 2/T+8006C/T+11100C 2/2/1 of the IL1RN gene was significantly associated with reduced innate ex vivo bioavailability of IL-1beta upon LPS stimulation (P = 0.026) and with ROA at the highest number of joint locations.

CONCLUSION

These results show that genetic variation at the IL-1 gene cluster is associated with lower IL-1beta bioavailability and with OA at a large number of joint locations. The data further indicate that, among subjects with OA affecting the highest number of joints, the innate immune system may be activated, thereby obscuring possible underlying mechanisms.

Paradoxical association of C-reactive protein with endothelial function in rheumatoid arthritis

BACKGROUND

Within the general population, levels of C-reactive protein (CRP) are positively associated with atherosclerotic cardiovascular disease (CVD). Whether CRP is causally implicated in atherogenesis or is the results of atherosclerosis is disputed. A role of CRP to protect endothelium-derived nitric oxide (EDNO) has been suggested. We examined the association of CRP with EDNO-dependent vasomotor function and subclinical measures of atherosclerosis and arteriosclerosis in patients with raised CRP resulting from rheumatoid arthritis (RA).

METHODOLOGY/PRINCIPAL FINDINGS

Patients with RA (n = 59) and healthy control subjects (n = 123), underwent measures of high sensitivity CRP, flow-mediated dilation (FMD, dependent on EDNO), intima-media thickness (IMT, a measure of subclinical atherosclerosis) and aortic pulse wave velocity (PWV, a measure of arteriosclerosis). IMT and PWV were elevated in patients with RA compared to controls but FMD was similar in the two groups. In patients with RA, IMT and PWV were not correlated with CRP but FMD was positively independently correlated with CRP (P<0.01).

CONCLUSIONS/SIGNIFICANCE

These findings argue against a causal role of CRP in atherogenesis and are consistent with a protective effect of CRP on EDNO bioavailability.

C-reactive protein and risk of lung cancer

PURPOSE

Chronic inflammation could play a role in lung carcinogenesis, underscoring the potential for lung cancer prevention and screening. We investigated the association of circulating high-sensitivity C-reactive protein (CRP, an inflammation biomarker) and CRP single nucleotide polymorphisms (SNPs) with prospective lung cancer risk.

PATIENTS AND METHODS

We conducted a nested case-control study of 592 lung cancer patients and 670 controls with available prediagnostic serum and 378 patients and 447 controls with DNA within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (N = 77,464). Controls were matched to patients on age, sex, entry year, follow-up time, and smoking. We measured CRP levels in baseline serum samples and genotyped five common CRP SNPs.

RESULTS

Elevated CRP levels were associated with increased lung cancer risk (odds ratio [OR], 1.98; 95% CI, 1.35 to 2.89; P-trend < .001 for fourth quartile [Q4, > or = 5.6 mg/L] v Q1 [< 1.0 mg/L]). The CRP association did not differ significantly by histology, follow-up time, or smoking status, but was most apparent for squamous cell carcinomas (OR, 2.92; 95% CI, 1.30 to 6.54), 2 to 5 years before lung cancer diagnosis (OR, 2.33; 95% CI, 1.24 to 4.39), and among former smokers (OR, 2.48; 95% CI, 1.53 to 4.03) and current smokers (OR, 1.90; 95% CI, 1.06 to 3.41). Although CRP SNPs and haplotypes were associated with CRP levels, they were not associated with lung cancer risk. Ten-year standardized absolute risks of lung cancer were higher with elevated CRP levels among former smokers (Q4: 2.55%; 95% CI, 1.98% to 3.27% v Q1: 1.39%; 95% CI, 1.07% to 1.81%) and current smokers (Q4: 7.37%; 95% CI, 5.81% to 9.33% v Q1: 4.03%; 95% CI, 3.01% to 5.40%).

CONCLUSION

Elevated CRP levels are associated with subsequently increased lung cancer risk, suggesting an etiologic role for chronic pulmonary inflammation in lung carcinogenesis.

Should we measure C-reactive protein on earth or just on JUPITER?

Evidence for the role of inflammation in the pathogenesis of atherosclerosis is compelling and has generated interest in high-sensitivity C-reactive protein (hs-CRP) as a marker of cardiovascular risk. Data regarding hs-CRP and cardiovascular risk, though largely consistent, is of unclear clinical relevance. Most recently, the Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) trial has led to further debate regarding the utility of hs-CRP. This article provides a comprehensive review of the data regarding cardiovascular risk and hs-CRP with an emphasis on the JUPITER trial and concludes with an evidence-based analysis of the current role of hs-CRP in cardiovascular risk assessment.

Persistent inflammation as a catalyst for other risk factors in chronic kidney disease: a hypothesis proposal

Because inflammation by now is a "traditional" finding that predicts poor outcome and cardiovascular events in the vast majority of patients with ESRD, it could be argued that inflammatory biomarkers should not longer be considered "novel" risk factors. In this review, we forward the hypothesis that, in addition to putative direct proatherogenic effects, persistent inflammation may serve as a catalyst and, in the toxic uremic milieu, modulate the effects of other concurrent vascular and nutritional risk factors. We discuss some recent observational studies, suggesting that the presence of persistent inflammation magnifies the risk for poor outcome via mechanisms related to self-enhancement of the inflammatory cascade and exacerbation of both the wasting and the vascular calcification processes. Because persistent inflammation may be the silent culprit of other commonly observed pathophysiologic alterations in chronic kidney disease, it is imperative that inflammatory markers be regularly monitored and therapeutic attempts be made to target persistent low-grade inflammation in this patient group.

Biochemistry and biomarkers of inflamed patients: why look, what to assess

Specific laboratory tests and physical findings are available to the practicing clinician that should raise the suspicion of inflammation. Inflammation is related to specific clinical outcomes. Once identified, changes in clinical practice may affect the level of inflammation in individual and or groups of dialysis patients with the hope that these changes may in turn affect outcome in a positive manner. Standard clinical tests and observations associated with inflammation are hypoalbuminemia, erythropoietin resistance, decreased iron saturation accompanied by high ferritin, frailty, low serum creatinine, reduced total and LDL-cholesterol, and increased C reactive protein (CRP). Inflammation is strongly associated with loss of physical function, dyslipidemia (low LDL- and HDL-cholesterol, increased triglycerides), and anemia that is unresponsive to erythropoietin. Inflammation is associated with cardiovascular events, increased hospitalization, and death. Correctible causes of inflammation are tunneled dialysis catheters, arteriovenous grafts, catheter infection, periodontal disease, poor water quality, and dialyzer incompatibility. Obesity also is a source of cytokines but may be less amenable to treatment. Inflammation is multifactorial in dialysis patients. Some sources are recognizable and correctable, such as vascular access type, clinical infection, and water quality, and some are not. Inflammation is strongly associated with outcome.

Obesity without established comorbidities of the metabolic syndrome is associated with a proinflammatory and prothrombotic state, even before the onset of puberty in children

BACKGROUND

Metabolic syndrome (MS)-related comorbidities in obesity, such as hypertension, dyslipidemia, and glucose intolerance, are increasingly recognized in children, predisposing them to early cardiovascular disease.

OBJECTIVE

The objective of the study was to investigate whether markers of inflammation and prothrombosis are abnormal in obese children without established MS comorbidities across puberty, as compared with lean, age-matched controls.

SUBJECTS AND METHODS

Obese children (body mass index >95%) with normal fasting glucose, blood pressure, cholesterol and triglycerides were recruited; lean controls (body mass index 10-75%) had no first-degree relatives with MS. High-sensitivity C-reactive protein (hsCRP), IL-6, plasminogen activator inhibitor 1, and fibrinogen concentrations were measured. Body composition was assessed by waist circumference and dual-energy x-ray absorptiometry.

RESULTS

Of 623 children screened, 203 enrolled (106 males, 97 females), aged 7-18 yr, 115 obese, 88 lean (balanced for age and gender), 99 prepubertal, and 104 pubertal. Many screen failures were due to silent comorbidities. Obese subjects with insulin resistance but without MS comorbidities had about 10 times higher hsCRP concentrations than controls and higher fibrinogen, IL-6, and plasminogen activator inhibitor-1 (P < 0.01 all). Differences were significant, even in the prepubertal cohort. hsCRP and fibrinogen correlated with waist circumference (r = 0.73 and 0.40, respectively) and percent fat mass (r = 0.76 and 0.47) (P < 0.0001).

CONCLUSION

Childhood obesity per se is associated with a proinflammatory and prothrombotic state before other comorbidities of the MS are present and even before the onset of puberty. Whether biomarkers like hsCRP and fibrinogen are useful in assessing cardiovascular risk and whether these abnormalities are reversible with earlier therapeutic interventions in very young obese children requires further study.

APOE polymorphism and its effect on plasma C-reactive protein levels in a large general population sample

The published data remain inconsistent on association between apolipoprotein E (APOE) gene variations and plasma levels of C-reactive protein (CRP), mainly because of low statistical power of previous studies. To clarify this question, we analyzed data from large population sample of randomly selected individuals from seven Czech towns (2,886 males and 3,344 females, the HAPIEE [Health, Alcohol, and Psychosocial factors In Eastern Europe] study). In both males and females, the lowest levels of plasma hsCRP were observed in the carriers of the APOE epsilon 4 epsilon 4 and epsilon 4 epsilon 3 genotypes. The median (interquartile range, IQR) concentration of hsCRP in carriers of the most common APOE epsilon 3 epsilon 3 genotype (two-thirds of participants) was 1.13 mg/l (IQR, 0.56-2.33) in men and 1.23 mg/l (IQR, 0.61-2.65) in women, compared with 0.72 mg/l (IQR, 0.61-0.86) in male and 0.72 mg/l (IQR, 0.61-0.85) in female carriers of APOE epsilon 4 epsilon 3/epsilon 4 epsilon 4 genotypes; the differences were statistically significant (p < 0.001). The association between APOE and CRP was not materially affected by adjustment for age, sex, history of cardiovascular disease, or cardiovascular risk factors. This study, the largest to date, provides robust evidence of an association between plasma hsCRP and the APOE genotype, an association not explained by history of cardiovascular disease nor its risk factors.

Clozapine therapy raises serum concentrations of high sensitive C-reactive protein in schizophrenic patients

Eight schizophrenic inpatients without manifest comorbidity were longitudinally studied. The aim was to find whether clozapine, the prototype of atypical antipsychotic drugs, altered their serum concentrations of high sensitive C-reactive protein (hsCRP), an inflammatory marker of high clinical importance. Following first-time therapy with clozapine, predominantly as the sole antipsychotic for 8 weeks, hsCRP profiles increased subclinically by 600%. This rise, and the Spearman correlation between hsCRP values and corresponding leukocyte counts, was statistically significant. A one-time cross-section investigation of 25 long-term clozapine patients and 25 patient controls did not show an elevation of hsCRP under clozapine after 1 year and more. It is assumed that the clozapine-evoked increase of hsCRP is part of a transient acute-phase response. The underlying inflammatory process needs clarification.

Mendelian randomization: use of genetics to enable causal inference in observational studies

The aim of aetiologic studies in epidemiology is to investigate whether factors are causally related to diseases and therefore become a potential target for therapeutic interventions. Mendelian randomization enables estimation of causal relationships in observational studies using genetic variants as instrumental variables. An instrumental variable is a variable that can be considered to mimic the coin toss in a randomized study. Given the random assignment of alleles in gamete formation, the use of genetic variants is an alternative method to control for confounding. This educational article describes the approach of Mendelian randomization, its underlying rationale and its necessary assumptions.

Risk factors for near-term myocardial infarction in apparently healthy men and women

BACKGROUND

Limited information is available regarding risk factors for the near-term (4 years) onset of myocardial infarction (MI). We evaluated established cardiovascular risk factors and putative circulating biomarkers as predictors for MI within 4 years of measurement.

METHODS

We conducted a matched, nested case-control study (252 cases and 499 controls) drawing on 45 735 men and women participating in the Copenhagen City Heart Study and the Copenhagen General Population Study. Established risk factors and 17 putative biomarkers, including inflammation-sensitive plasma proteins (C-reactive protein, fibrinogen, alpha(l)-antitrypsin, complement 3), apolipoproteins (A1, B, E, B/A1 ratio), markers of iron overload (iron, transferrin, transferrin saturation), creatinine, alkaline phosphatase, gamma-glutamyl transpeptidase, and leukocytes (lymphocyte count, neutrophil count, neutrophil/lymphocyte ratio) were assessed.

RESULTS

Among women and men, only 13% and 50%, respectively, of those with near-term MI were classified as high risk by Framingham risk score at baseline. After adjustment for established risk factors, odds ratios for near-term MI, which compared highest to lowest quintiles, were 2.87(95% CI 1.51-5.48; P = 0.001) for alpha(l)-antitrypsin, 2.84(1.42-5.67; P = 0.003) for C-reactive protein, 1.97(1.09-3.57; P = 0.03) for creatinine, 1.99(1.09-3.65; P = 0.03) for fibrinogen, and 0.37(0.19-0.73; P = 0.004) for iron. The corresponding odds ratio for all biomarkers combined was 7.24 (3.28-16.0; P < 0.001).

CONCLUSIONS

We identified 5 biomarkers associated with increased near-term risk of MI independently of established risk factors. All putative biomarkers combined explained a 7-fold increase in the odds of near-term MI.

Expanded network of inflammatory markers of atherogenesis: where are we now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesis via activation of monocytes/macrophages and T lymphocytes. Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Expanded Network of Inflammatory Markers of Atherogenesis: Where Are We Now?

Inflammatory biomarkers play a pivotal role in atherosclerotic lesions. The plasma levels of these markers are predictive of adverse outcomes such as myocardial infarction and cardiovascular death. The immune system is involved at all stages of atherogenesisviaactivation of monocytes/macrophages and T lymphocytes.Circulating proinflammatory cytokines and chemokines produced by these cells interact with specific receptors on various cells and activate specific signaling pathways, leading to inflammation-induced atherosclerotic lesions. Recent studies have focused on predictive value of inflammatory biomarkers such as C-reactive protein and interleukin-6. These biomarkers were shown to be associated with poor quality of life and predictive of adverse events in coronary atherosclerosis and left ventricular dysfunction. Vascular predictive value of other numerous inflammatory markers is being investigated. We herein analyze the role of several mediators of inflammation, affecting vascular functions and leading toward atherosclerotic lesions.

Induction of interleukin-8 gene expression and protein secretion by C-reactive protein in ARPE-19 cells

C-reactive protein (CRP) is an acute phase reactant and its level rises rapidly during inflammation. Recent studies have suggested the potential involvement of CRP in the pathogenesis of age-related macular degeneration (AMD). To delineate the functional roles of CRP in inflammatory response by the ocular posterior segments, the effects of CRP on ARPE-19, an immortalized human retinal pigment epithelia (hRPE) cell line, were investigated in the present study. Treatment of ARPE-19 cells with CRP resulted in enhanced NF-kB nuclear translocation and dose-dependent transient induction of IL-8 mRNA synthesis and protein secretion. Stimulated expression of VEGF, but not MCP-1 by CRP was also observed. The induced IL-8 expression was transient and peaked at 12h post stimulation. In the presence of inhibitors for NF-kB, p38, MEK and JNK, the CRP-induced IL-8 production was abolished by 99.5+/-2.3, 97.8+/-2.1, 55.3+/-2.5 and 37.3+/-1.3%, respectively. Neutralization of Fc gamma receptors by anti-CD32 and CD64 antibodies produced 39.9+/-1.6 and 59.5+/-2.6% reduction, respectively, of CRP-stimulated IL-8 secretion, whereas that by anti-CD16 antibody had no effect. This study suggests that the pro-inflammatory effects of CRP in ARPE-19 cells may contribute to the inflammatory retinal diseases by induction of pro-inflammatory cytokines such as IL-8. This induction is mediated by NF-kB and multiple MAPK pathways through Fc gamma receptors.

C-reactive protein levels and post-ICU mortality in nonsurgical intensive care patients

BACKGROUND

There are no data on the association between acute inflammation during critical illness and long-term mortality in ICU patients.

METHODS

Nonsurgical patients with an ICU length of stay > 24 h surviving until ICU discharge were included into this prospective, observational, follow-up study. Demographics, chronic diseases, admission diagnosis, the Simplified Acute Physiology Score (SAPS) II, length of ICU stay, maximum C-reactive protein (CRP) levels during the ICU stay (CRPmax), and CRP levels at ICU discharge (CRPdis) were documented. After a follow-up time of 1.88 ± 1.16 years (range, 0.5-4 years), the survival status was determined.

RESULTS

Seven hundred sixty-five patients were enrolled into the study protocol. One hundred fifty-eight patients (20.7%) died within 0.62 ± 0.88 years after ICU discharge. Cumulative survival rates differed between patients grouped into the CRPmax and CRPdis quartiles. Patients in the first and second CRPmax quartiles had better cumulative survival rates than those in higher CRPmax quartiles (all P < .001). Patients in the first CRPdis quartile had better cumulative survival rates than those in higher CRPdis quartiles (all P < .001). Using adjusted Cox proportional hazards models, both CRPmax and CRPdis were independently associated with post-ICU mortality (both P < .001). Furthermore, the number of chronic diseases (P < .001), age (P < .001), and the SAPS II (P = .03) were associated with post-ICU mortality in both Cox models.

CONCLUSIONS

CRP levels during critical illness seem independently associated with post-ICU survival in nonsurgical ICU patients. Future research focusing on the association between acute systemic inflammation and post-ICU outcome is warranted in order to improve long-term survival of critically ill patients.

Venous thromboembolism and risk of idiopathic interstitial pneumonia: a nationwide study

RATIONALE

Idiopathic interstitial pneumonia is characterized by pulmonary fibrosis and high mortality.

OBJECTIVES

We examined the association between ever-diagnosed venous thromboembolism and risk of incident idiopathic interstitial pneumonia. Venous thromboembolism was taken as a proxy for a procoagulant state in an individual.

METHODS

We conducted a study of the entire Danish population from 1980 through 2007, comprising 7.4 million individuals. Incident idiopathic interstitial pneumonia, ever-diagnosed venous thromboembolism, and use of prescription anticoagulants were drawn from national Danish registries.

MEASUREMENTS AND MAIN RESULTS

Age-standardized incidence rates per 10,000 person-years for idiopathic interstitial pneumonia were higher among those ever diagnosed with venous thromboembolism (1.8; n = 158,676), pulmonary embolism (2.8; n = 70,586), and deep venous thrombosis only (1.2; n = 88,090), than among control subjects (0.8; n = 7,260,278). Multivariate-adjusted hazard ratios for idiopathic interstitial pneumonia were 1.8 (95% confidence interval [CI], 1.7-1.9) in those ever diagnosed with venous thromboembolism, 2.4 (95% CI, 2.3-2.6) in those ever diagnosed with pulmonary embolism, and 1.3 (95% CI, 1.2-1.4) in those ever diagnosed with deep venous thrombosis only, compared with control subjects. Corresponding hazard ratios in those ever diagnosed with venous thromboembolism stratified in those ever and never treated with anticoagulants were 1.4 (95% CI, 1.2-1.6) and 2.8 (95% CI, 2.4-3.1) (venous thromboembolism x anticoagulation use interaction on idiopathic interstitial pneumonia outcome: P = 1.5 x 10(-10)).

CONCLUSIONS

In the general population, ever-diagnosed venous thromboembolism was associated with idiopathic interstitial pneumonia, particularly among those never treated with anticoagulants.

Association of C-reactive protein with cognitive impairment

BACKGROUND

High-sensitivity C-reactive protein (hsCRP) is a biomarker of cardiovascular risk that is suggested to be a biomarker for cognitive impairment.

OBJECTIVE

To explore the association between hsCRP and cognitive impairment.

DESIGN

Cross-sectional analysis of a population-based community aging study.

SETTING

Northern Manhattan, New York, New York.

OTHER PARTICIPANTS

One thousand three hundred thirty-one participants from a longitudinal study of aging without dementia and with available hsCRP and neuropsychological testing data at baseline.

MAIN OUTCOME MEASURES

Four cognitive scores (memory, visuospatial, executive, and language impairment) derived from a neuropsychological battery. Cognitive impairment was defined by scores below 1.5 SDs of demographically corrected means.

RESULTS

Participants in the highest hsCRP tertile had higher adjusted odds of impaired memory (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.0-2.1; P = .03) than participants in the lowest tertile. Subjects in the highest hsCRP tertile also had greater odds of visuospatial impairment (OR, 1.6; 95% CI, 1.0-2.3; P = .03). Higher hsCRP was not associated with executive or language impairment. Persons with at least 1 APOE epsilon4 allele and hsCRP in the highest tertile had the greatest odds of impaired memory (OR, 2.7; 95% CI, 1.6-4.4).

CONCLUSIONS

High hsCRP may be a marker of memory and visuospatial impairment in the elderly. The role of APOE epsilon4 requires further exploration.

Inflammation markers and metabolic characteristics of subjects with 1-h plasma glucose levels

OBJECTIVE

To assess the association of 1-h plasma glucose (1hPG) and inflammation with normal glucose tolerance (NGT) and pre-diabetes.

RESEARCH DESIGN AND METHODS

A cohort of 1,062 subjects was enrolled. After oral glucose load (oral glucose tolerance test), we compared subjects with NGT and pre-diabetes above and below the 1hPG cut point (155 mg/dl). Fibrinogen and leukocytes count (white blood cells [WBCs]) for subclinical inflammation, lipid ratios, insulin sensitivity (Matsuda index) were determined.

RESULTS

Patients with NGT and pre-diabetes (1hPG >155 mg/dl) showed a significant increase of inflammatory markers and lipid ratios (for all, P < 0.05). In age-, sex-, and BMI-adjusted analysis, 1hPG was associated with a significantly higher WBC count and fibrinogen (P < 0.05). Patients with elevated 1hPG showed a highly significant lower insulin sensitivity than subjects <1hPG (P < 0.01).

CONCLUSIONS

Elevated 1hPG in subjects with NGT and pre-diabetes is associated with subclinical inflammation, high lipid ratios, and insulin resistance. Therefore, 1hPG >155 mg/dl could be considered a new "marker" for cardiovascular risk.

NOD2/CARD15 genotype and common gastrointestinal diseases in 43,600 individuals

OBJECTIVES

NOD2/CARD15 is involved in the innate immune response and three polymorphisms in this gene (Arg702Trp rs2066844, Gly908Arg rs2066845 and Leu1007fsinsC rs5743293) have been associated with risk of the rare Crohn's disease. We tested the hypothesis that polymorphisms in NOD2/CARD15 associate with risk of nine common gastrointestinal diseases.

DESIGN AND SETTING

We genotyped 43 596 white individuals from the Danish general population followed for 31 years, during which time 782 developed oesophagitis and reflux, 1395 ulcus ventriculi and duodeni, 1384 gastritis and dyspepsia, 1407 appendicitis, 646 irritable bowel syndrome, 1301 infectious diseases of the gastrointestinal tract, 681 anal fissure, fistula and abscess, 826 gastrointestinal cancer and 161 developed cancer in liver and pancreas.

RESULTS

Some 89% were non-carriers, 11% heterozygotes, 0.15% homozygotes and 0.23% compound heterozygotes. Cumulative incidences differed by genotype for appendicitis (log-rank P = 0.02), anal fissure, fistula and abscess (P = 0.003) and gastrointestinal cancer (P = 0.004), but not for any of the other endpoints. Compared with non-carriers, age and sex adjusted hazard ratios were 2.7 (95%CI 1.4-5.5) for appendicitis amongst compound heterozygotes, 3.2 (1.3-7.8) for anal fissure, fistula and abscess amongst compound heterozygotes, and 3.8 (1.6-9.2) for gastrointestinal cancer amongst homozygotes, whilst other genotypes did not have increased risk. The increased risk of gastrointestinal cancer amongst homozygotes appeared to be similar amongst both men and women and amongst those below or above 60 years, and likely included both upper gastrointestinal cancer and colorectal cancer.

CONCLUSIONS

NOD2/CARD15 polymorphisms are not major risk factors for common gastrointestinal diseases; however, we cannot completely exclude association with appendicitis, anal fissure, fistula and abscess, and gastrointestinal cancer.

Fabrication of oriented antibody-conjugated magnetic nanoprobes and their immunoaffinity application

In an attempt to fabricate highly active immunoprobes for serum biomarker detection, we report a simple and effective method for site-specific and self-oriented immobilization of antibodies on magnetic nanoparticles (MNPs). Through boronate formation, the carbohydrate moiety within the constant domain, Fc, of the antibody can be specifically and covalently linked to a boronic acid-functionalized MNP (BA@MNP) without hindering the antigen binding domain, Fab. The performance was evaluated by immunoaffinity extraction of multiple serum antigens. Compared with the random immobilization of antibody on a MNP, the antibody self-oriented immunoprobe provides long-term stability (>2 months) and 5-fold extraction efficiency. It also provides 5-fold improved sensitivity at a low nM range (0.4 nM), presumably through enhanced antibody@MNP activity. In addition, false-positive detections arising from nonspecific binding can be completely minimized by effective surface protection using concentration-dependent dextran blocking. Compared with conventional antibody site-specific immobilization through protein G, this new BA-mediated covalent antibody immobilization provides interference-free extraction resulting from noncovalent immobilization of antibody by protein G. The new immunoassay was applied in comparative profiling of serum amyloid P (SAP), serum amyloid A (SAA), and C-reactive protein (CRP) in human serum. Our triple immunoassay revealed a distinct pattern among normal patients, patients with cancer, and patients with cardiovascular disease. Using the previously reported quantization capability of the MALDI MS readout, we expect that this site-specific immunonanoprobe-based immunoassay can be highly active, rapid, and accurate in nanodiagnosis.

C-reactive protein and uremia

Since the first report of elevated serum levels of C-reactive protein (CRP) predicting all cause and cardiovascular mortality more than 10 years ago, many other studies have recognized that the uremic milieu is associated with a state of chronic inflammation. The causes for inflammation are multiple and have been well studied in the past 10 years. Nondialysis, uremia related and endogenous factors as well as the dialysis procedure itself may be responsible for the high prevalence of inflammation in dialysis patients. Today, CRP serves to improve overall vascular risk stratification and, in the individual, to detect sources of specific infections. Because multiple factors contribute to the milieu of inflammation, the predictive value of CRP is rather nonspecific in dissecting a cause, with respect to the subcomponents of cardiac, vascular, and even noncardiovascular causes of mortality. So far, no specific pharmacologic treatment, including atorvastatin, has been identified that can substantially reduce CRP and accompanying inflammation.

Relationship of interleukin-6 with regional and global left-ventricular function in asymptomatic individuals without clinical cardiovascular disease: insights from the Multi-Ethnic Study of Atherosclerosis

AIMS

We sought to examine the relationship between circulating interleukin-6 (IL-6) level and regional left-ventricular (LV) function among apparently healthy individuals free of cardiovascular disease.

METHODS AND RESULTS

Using magnetic resonance myocardial tagging, we determined peak systolic circumferential strain (Ecc) as a measure of regional systolic function in 894 asymptomatic participants in the Multi-Ethnic Study of Atherosclerosis. Ecc was analysed by harmonic phase imaging separately in the LV anterior wall, septum, lateral wall, and inferior wall. Global Ecc was calculated as the average of Ecc in all myocardial segments. We performed multivariable linear regression to evaluate the independent associations between log IL-6 and Ecc, after adjusting for demographic features, cardiovascular risk factors, and markers of subclinical atherosclerosis. The inverse relationships between IL-6 and absolute Ecc were similar in both genders. In multivariable analysis, higher IL-6 level was independently associated with reduced systolic function (less negative Ecc) in the septum [regression coefficient = 1.03 per unit higher log IL-6, 95% confidence interval (CI) 0.26-1.79, P = 0.008] and inferior wall (regression coefficient = 1.65, 95% CI 0.74-2.56, P < 0.001), but not in the anterior wall (P = 0.27) or lateral wall (P = 0.52). Overall, there was an independent inverse association between IL-6 and global Ecc (regression coefficient = 0.94, 95% CI 0.37-1.51, P = 0.001). Compared with C-reactive protein, higher IL-6 level demonstrates a stronger independent association with reduced regional systolic function.

CONCLUSION

In asymptomatic men and women without documented cardiovascular disease, there is a strong, independent, inverse relationship between IL-6 and regional LV systolic function. These findings suggest that IL-6 may underlie the pathogenetic link between inflammation, LV dysfunction and incipient heart failure. The observed variable relationships between IL-6 and systolic function across different LV regions warrant further investigations.

C-reactive protein concentration and risk of coronary heart disease, stroke, and mortality: an individual participant meta-analysis

BACKGROUND

Associations of C-reactive protein (CRP) concentration with risk of major diseases can best be assessed by long-term prospective follow-up of large numbers of people. We assessed the associations of CRP concentration with risk of vascular and non-vascular outcomes under different circumstances.

METHODS

We meta-analysed individual records of 160 309 people without a history of vascular disease (ie, 1.31 million person-years at risk, 27 769 fatal or non-fatal disease outcomes) from 54 long-term prospective studies. Within-study regression analyses were adjusted for within-person variation in risk factor levels.

RESULTS

Log(e) CRP concentration was linearly associated with several conventional risk factors and inflammatory markers, and nearly log-linearly with the risk of ischaemic vascular disease and non-vascular mortality. Risk ratios (RRs) for coronary heart disease per 1-SD higher log(e) CRP concentration (three-fold higher) were 1.63 (95% CI 1.51-1.76) when initially adjusted for age and sex only, and 1.37 (1.27-1.48) when adjusted further for conventional risk factors; 1.44 (1.32-1.57) and 1.27 (1.15-1.40) for ischaemic stroke; 1.71 (1.53-1.91) and 1.55 (1.37-1.76) for vascular mortality; and 1.55 (1.41-1.69) and 1.54 (1.40-1.68) for non-vascular mortality. RRs were largely unchanged after exclusion of smokers or initial follow-up. After further adjustment for fibrinogen, the corresponding RRs were 1.23 (1.07-1.42) for coronary heart disease; 1.32 (1.18-1.49) for ischaemic stroke; 1.34 (1.18-1.52) for vascular mortality; and 1.34 (1.20-1.50) for non-vascular mortality.

INTERPRETATION

CRP concentration has continuous associations with the risk of coronary heart disease, ischaemic stroke, vascular mortality, and death from several cancers and lung disease that are each of broadly similar size. The relevance of CRP to such a range of disorders is unclear. Associations with ischaemic vascular disease depend considerably on conventional risk factors and other markers of inflammation.

FUNDING

British Heart Foundation, UK Medical Research Council, BUPA Foundation, and GlaxoSmithKline.

C-reactive protein and the risk of cancer: a mendelian randomization study

Elevated plasma levels of C-reactive protein (CRP), a marker of inflammation, are associated with an increased risk of cancer, but it is unclear whether this association is causal. We examined whether four common single-nucleotide polymorphisms (SNPs) in the CRP gene that are associated with altered plasma CRP levels are causally associated with an increased risk of cancer. The study population included participants in a prospective study (n = 10 215) and a cross-sectional study (n = 36 403) of the adult general population in Denmark, all of whom were genotyped for the CRP SNPs. The association between plasma CRP levels measured by a high-sensitivity turbidimetry assay and the risk of cancer was examined for 8224 participants in the prospective study. The hazard ratio of cancer for a doubling of the plasma CRP level was 1.09 (95% confidence interval [CI] = 1.03 to 1.14). The nine most common genotype combinations of the four CRP SNPs were associated with up to a 72% increase (95% CI = 58% to 87%) in CRP levels but not with an increased risk of cancer. The estimated causal odds ratio for cancer associated with a genetically induced doubling in CRP level was 0.94 (95% CI = 0.81 to 1.08). This finding suggests that elevated CRP levels do not cause cancer.

Influence of low-grade inflammation on plasma B-type natriuretic peptide levels

OBJECTIVE

B-type natriuretic peptide (BNP) is a cardiac hormone. The results of previous in vitro studies suggest that neurohumoral factors, and not only hemodynamic factors, may cause BNP secretion. In this study, we examined the impact of serum C-reactive protein (CRP) levels on the relationship between echocardiographic parameters and plasma BNP levels in patients with cardiovascular diseases.

METHODS AND PATIENTS

The study population comprised 417 patients who visited our cardiovascular unit with a problem. Both blood sampling and echocardiography were performed within one month.

RESULTS

Multiple regression analysis showed that plasma BNP levels were negatively correlated with male gender, body mass index, and estimated glomerular filtration rate, and positively correlated with serum CRP levels and left ventricular end-systolic dimension (LVDs). The study population was divided into two groups based on the 75th percentile of the serum CRP levels. Single regression analysis showed that a regression line between LVDs and plasma BNP levels was steeper in the group of patients with CRP levels above the 75th percentile. Multiple regression analysis revealed that the interaction term (LVDs×CRP) was significant, which means LVDs had more impact on plasma BNP levels at higher CRP levels.

CONCLUSION

Plasma BNP levels increased with respect to the severity of cardiac dysfunction and serum CRP levels, and should therefore be considered a collective or total marker for life-threatening conditions including systemic inflammation, and not simply as a marker of cardiac dysfunction in patients with cardiovascular diseases.

Tumor necrosis factor-alpha antagonists improve aortic stiffness in patients with inflammatory arthropathies: a controlled study

The chronic inflammatory state of rheumatoid arthritis and other inflammatory arthropathies, such as ankylosing spondylitis and psoriatic arthritis, contributes to the accelerated atherosclerosis associated with these conditions. This study evaluates the effect of treatment with tumor necrosis factor (TNF)-alpha antagonists on arterial stiffness in patients with inflammatory arthropathies. A total of 60 patients with rheumatoid arthritis, ankylosing spondylitis, or psoriatic arthritis and clinical indication for anti-TNF-alpha therapy were included. Thirty-five patients started with anti-TNF-alpha therapy and were compared with a nontreatment group of 25 patients. Aortic stiffness (aortic pulse wave velocity), augmentation index, and disease activity were assessed at baseline and after 3 months. Aortic pulse wave velocity (mean+/-SD) was reduced in the treatment group but not in the control group (-0.50+/-0.78 m/s versus 0.05+/-0.54 m/s, respectively; P=0.002). Concomitantly, C-reactive protein and the disease activity score were reduced in the treatment group (-9.3+/-20.2 mg/L [P<0.001] and -0.74+/-0.91 [P=0.004]). Augmentation index remained unchanged in both groups (0.1+/-7.1% versus -1.0+/-5.8%, respectively; P=0.53). In a multivariate linear regression model, only treatment with TNF-alpha antagonist and change in mean arterial pressure predicted alterations in aortic pulse wave velocity. In summary, anti-TNF-alpha therapy improved aortic stiffness in patients with inflammatory arthropathies. These findings support the idea that anti-inflammatory treatment has a favorable effect on cardiovascular risk in patients with inflammatory arthropathies.

Primary prevention of vascular events in patients with high levels of C-reactive protein: the JUPITER study

The Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) study was the first large-scale, prospective study to examine the benefits of statin therapy in subjects with elevated levels of high-sensitivity C-reactive protein but with low-to-normal LDL-cholesterol levels, who were not qualified for lipid-lowering treatment according to the current guidelines for primary prevention. The JUPITER study aimed to determine whether rosuvastatin 20 mg daily would reduce the rate of first major cardiovascular events, including cardiovascular death, nonfatal stroke, nonfatal myocardial infarction, hospitalization for unstable angina or arterial revascularization. Rosuvastatin reduced LDL-cholesterol levels by 50% and high-sensitivity C-reactive protein by 37%. Compared with placebo, the combined primary end point was reduced in 44% (p < 0.00001), and total mortality in 20% (p = 0.02). The trial confirmed the relationship between the rates of major cardiovascular events with both high-sensitivity C-reactive protein and LDL-cholesterol levels achieved after statin treatment. Interestingly, this was the first large, prospective statin trial to show benefit in the reduction of venous thromboembolism.