Generation of C-reactive protein and complement components in atherosclerotic plaques

Oxidation of LDL and its clinical implication

Oxidative modification of low-density lipoprotein (LDL) is one of the earliest events in atherosclerosis. Oxidized LDL (oxLDL) represents a variety of modification of both lipid and apolipoprotein B (apoB) components by lipid peroxidation. This promotes atherosclerosis through inflammatory and immunologic mechanisms that lead to the formation of macrophage foam cells. Recent findings also suggest that oxLDL forms complexes with beta(2)-glycoprotein I (beta(2)GPI) and/or C-reactive protein (CRP) within atherosclerotic lesions and that these complexes appear in the circulation. Autoantibodies (auto-Abs) against oxLDL/beta(2)GPI complexes occur in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS). These autoantibodies significantly correlate with arterial thrombosis. IgG auto-Abs having similar specificity emerge spontaneously in NZWxBXSB F1 mice, which generally are considered to be an animal model of APS, and these mice produce a monoclonal IgG auto-Ab (WB-CAL-1) against oxLDL/beta(2)GPI complexes. WB-CAL-1 significantly increased the in vitro uptake of oxLDL/beta(2)GPI complexes by macrophages, which suggests that such IgG auto-Abs are pro-atherogenic. In contrast, IgM anti-oxLDL natural Abs found in the atherosclerosis-prone mice have been proposed to be protective. The presence of such Abs in humans has been documented in many publications but their exact pathophysiological significance remains unclear. In this article, we review recent progress in our understanding of the clinical significance of oxidation of LDL, formation of oxLDL complexes, and Abs in atherosclerotic and/or autoimmune disease.

Human C-reactive protein promotes oxidized low density lipoprotein uptake and matrix metalloproteinase-9 release in Wistar rats

C-reactive protein (CRP) is present in the atherosclerotic plaques and appears to promote atherogenesis. Intraplaque CRP colocalizes with oxidized low density lipoprotein (OxLDL) and macrophages in human atherosclerotic lesions. Matrix metalloproteinase-9 (MMP-9) has been implicated in plaque rupture. CRP promotes OxLDL uptake and MMP induction in vitro; however, these have not been investigated in vivo. We examined the effect of CRP on OxLDL uptake and MMP-9 production in vivo in Wistar rats. CRP significantly increased OxLDL uptake in the peritoneal and sterile pouch macrophages compared with human serum albumin (huSA). CRP also significantly increased intracellular cholesteryl ester accumulation compared with huSA. The increased uptake of OxLDL by CRP was inhibited by pretreatment with antibodies to CD32, CD64, CD36, and fucoidin, suggesting uptake by both scavenger receptors and Fc-gamma receptors. Furthermore, CRP treatment increased MMP-9 activity in macrophages compared with huSA, which was abrogated by inhibitors to p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), and nuclear factor (NF)-kappaB but not Jun N-terminal kinase (JNK) before human CRP treatment. Because OxLDL uptake by macrophages contributes to foam cell formation and MMP release contributes to plaque instability, this study provides novel in vivo evidence for the role of CRP in atherosclerosis.

Effects of drug-eluting stents on systemic inflammatory response in patients with unstable angina pectoris undergoing percutaneous coronary intervention

Inflammatory markers are elevated in acute coronary syndromes, and are also known to play a crucial role in the pathogenesis of neointimal proliferation and stent restenosis. Drug-eluting stents (DESs) have been shown to decrease stent restenosis in different studies. In this study, we aimed to investigate the effect of treatment with DESs on systemic inflammatory response in patients with unstable angina pectoris who underwent percutaneous coronary intervention (PCI). We compared plasma high-sensitivity C-reactive protein (hsCRP), human tumor necrosis factor alpha (Hu TNF-alpha), and interleukin 6 (IL-6) levels after DES (dexamethasone-eluting stent [DEXES], and sirolimuseluting stent [SES]) implantation with levels after bare metal stent (BMS) implantation. We performed PCI with a single stent in 90 patients (62 men; 59 +/- 9 years of age; n = 30 in the BMS group, n = 30 in the DEXES group, n = 30 in the SES group) who had acute coronary syndrome. Plasma hsCRP, Hu TNF-alpha, and IL-6 levels were determined before intervention and at 24 h, 48 h, and 1 week after PCI. The results were as follows. Plasma hsCRP levels at 48 h (11.19 +/- 4.54, 6.43 +/- 1.63 vs 6.23 +/- 2.69 mg/l, P = 0.001) after stent implantation were significantly higher in the BMS group than in the DES group; this effect persisted for 7 days (P = 0.001). Plasma Hu TNF-alpha levels at each time point were higher in the SES group than in the BMS and DEXES groups (P < 0.05). The time course of Hu TNF-alpha values was similar in all groups. Although IL-6 levels at baseline and at 24 and 48 h showed no statistically significant difference between the study groups, postprocedural values at 7 days were slightly statistically significant in the SES group (P = 0.045). Drug-eluting stents showed significantly lower plasma hsCRP levels after PCI compared with BMSs. This may reflect the potent effects of DESs on acute inflammatory reactions induced by PCI.

Aortic dissection and third-degree atrioventricular block in a patient with a hypertensive crisis

A 55-year-old man with a history of uncontrolled hypertension was admitted because of an episode of severely elevated blood pressure. An electrocardiogram revealed complete atrioventricular block while imaging showed a dissecting aneurysm of the descending thoracic and abdominal aorta, type B according to the Stanford classification. Laboratory tests revealed significant increases in serum C-reactive protein. Coronary arteriography was performed and was negative for coronary artery disease. A VDD pacemaker was placed, and a combination of 4 antihypertensive agents was used as treatment. Type B aortic dissection may present with a wide range of manifestations. The authors suggest that measurement of C-reactive protein may be used in hypertensive patients to help reflect vascular injury and its degree, progression, and prognosis. Disorders of intraventricular conductivity are rarely seen in both types of dissection of the aorta (type A, B). Atrioventricular conductivity disorders that result in complete atrioventricular block have been reported only in patients with type A dissection (before the bifurcation of the subclavian artery). In this particular case, however, the authors diagnosed an atrioventricular conductivity disorder causing atrioventricular block in a patient with type B dissection. Consequently, the authors speculate that myocardial fibrosis, as a result of long-standing hypertension, could be the main pathogenetic mechanism leading to the development of such phenomena, resulting from a potential expanding of the fibrotic process to the atrioventricular conduction system.

Human C-Reactive Protein Activates Monocyte-Derived Dendritic Cells and Induces Dendritic Cell-Mediated T-Cell Activation

Objective— Recent studies proposed a pathogenic role for C-reactive protein (CRP), an independent predictor of cardiovascular disease (CVD), in atherosclerosis. Therefore, we tested whether CRP may modulate dendritic cell (DC) function, because these professional antigen-presenting cells have been implicated in atherogenesis.

Methods and Results— Human monocyte-derived immature DCs were cultured with human CRP (0 to 60 μg/mL) for 24 hours. Thereafter, activation markers were measured by flow-cytometry and DCs were cocultured with CFSE-labeled lymphocytes to measure T-cell proliferation and interferon (IFN)-γ secretion after 8 days. Exposure to 60 μg/mL CRP (n=5) induced an activated cell morphology and significant (CD40 increase MFI 5.23±0.28, P <0.01 paired t test; CD80 6.18±0.51, P <0.01) to modest (CD83 1.38±0.17, P <0.05, CCR7 1.60±0.29, P =0.05) upregulation of DC activation markers. The expression of CD86 and HLA-DR was high, but not affected. T-lymphocytes incubated with CRP-pulsed DCs displayed increased IFN-γ secretion and proliferation ( P <0.001). DC activation was concentration-dependent and detected from 2 μg/mL CRP; the maximum effect was equivalent to that seen with 0.1 μg/mL lipopolysaccharide (LPS). Polymyxin B abolished the LPS response, without influencing CRP effects. Finally, immunohistochemistry could demonstrate DC/CRP colocalization in human atherosclerotic lesions.

Conclusions— These findings suggest that CRP in plaques or found circulating in CVD patients can influence DC function during atherogenesis.

C-reactive protein enhances tissue factor expression by vascular smooth muscle cells: mechanisms and in vivo significance

OBJECTIVE

We examined the impact of C-reactive protein (CRP) on vascular smooth muscle cell (VSMC) expression of tissue factor (TF) and TF pathway inhibitor (TFPI).

METHODS AND RESULTS

TF mRNA, protein, and activity levels were significantly higher in VSMCs isolated from CRP-transgenic (Tg) mice than from wild-type (WT) mice. TFPI expression was significantly downregulated in CRP-Tg versus WT VSMCs. Transfection of human VSMCs with CRP expression plasmid significantly increased TF expression and decreased TFPI expression. Gene silencing of Fc gamma receptor IIIa (Fc gammaRIIIa) blocked the effect of CRP on VSMC TF expression. CRP activated p44/42, but not p38 or JNK MAP kinase (MAPK), and the effect of CRP on TF expression was blocked by pharmacological inhibitor of p44/42, but not p38 or JNK MAPK. Reactive oxygen species (ROS) scavengers blocked CRP-induced upregulation of VSMC TF expression. In vivo analyses revealed significant increases in TF expression and decreases in TFPI expression in carotid arteries of CRP-Tg mice versus WT mice.

CONCLUSIONS

CRP increases TF and decreases TFPI expression by VSMCs in vitro and in vivo. Induction of TF expression by CRP is mediated by Fc gammaRIIIa, p44/42 MAPK, and ROS generation. These data offer important insights into the role of CRP in the pathogenesis of arterial thrombosis.

Markers of systemic bacterial exposure in periodontal disease and cardiovascular disease risk: a systematic review and meta-analysis

BACKGROUND

Recent meta-analyses reported a weak association between periodontal disease (PD) on clinical examination and cardiovascular disease (CVD). Systemic bacterial exposure from periodontitis, which correlates poorly with the clinical examination, has been proposed as the more biologically pertinent risk factor. The purpose of this study was to review and analyze the association between PD with elevated systemic bacterial exposure and CVD.

METHODS

We searched in the PubMed, Cochrane Controlled Trials Register, EMBASE, and SCOPUS databases for all literature examining PD and CVD. From 10 selected publications, we extracted 12 cohort (N = 5) and cross-sectional (N = 7) studies and included 11 of these in a meta-analysis. With stratified analyses, this resulted in 14 analyses of coronary heart disease (CHD; N = 7), stroke (N = 4), and carotid intima-medial thickening (CIMT; N = 3) as a measure of early atherosclerosis. Systemic bacterial exposure was measured by periodontal bacterial burden (N = 1), periodontitis-specific serology (N = 12), or C-reactive protein (N = 1).

RESULTS

Periodontal disease with elevated markers of systemic bacterial exposure was associated strongly with CHD compared to subjects without PD, with a summary odds ratio of 1.75 (95% confidence interval (CI): 1.32 to 2.34; P <0.001). This group was not associated with CVD events or with stroke but was associated with a significant increase in mean CIMT (0.03 mm; 95% CI: 0.02 to 0.04).

CONCLUSION

Periodontal disease with elevated bacterial exposure is associated with CHD events and early atherogenesis (CIMT), suggesting that the level of systemic bacterial exposure from periodontitis is the biologically pertinent exposure with regard to atherosclerotic risk.

Targeting C-reactive protein levels using high-dose atorvastatin before coronary artery bypass graft surgery

BACKGROUND

Statin medication exhibits pleiotropic properties, such as improvement of endothelial function.

AIM

To determine whether a high loading dose of atorvastatin prescribed before and after coronary artery bypass graft (CABG) surgery will attenuate the inflammatory response reflected in kinetic concentrations of C-reactive protein (CRP).

METHODS

The individual area under the concentration-time curve (AUC) of CRP concentration was calculated for the first five days after CABG surgery and compared among three groups of patients: group A patients (n=16), who were on chronic statin therapy, were switched to an equivalent therapy of 20 mg atorvastatin daily for 120 h; group B patients (n=15), who were on chronic statin therapy, were switched to 80 mg atorvastatin daily (one dose 24 h before CABG surgery, one on the day of surgery and two further doses after surgery) followed by 40 mg/day up to 120 h after surgery; and group C patients (n=10), who were naive to statin therapy, underwent elective CABG surgery.

RESULTS

The three groups were comparable according to measurements of their intra- and postoperative variables, except for their mean weight. The mean (+/- SEM) AUC-CRP for group B was 13,545+/-959.9 mg/L.h, significantly smaller (P=0.01) than that for group A (17,085+/-858.4 mg/L.h). In group C (statin-naïve patients), the AUC-CRP was 16,191+/-1447 mg/L.h, which was not significantly different from groups A and B, respectively.

CONCLUSIONS

High loading doses of atorvastatin before CABG surgery reduced CRP concentration, expressed as AUC-CRP. This effect supports the idea that a high dose of atorvastatin is needed to attenuate the 'negative' inflammatory response. The present study also lends support to the possibility that high-dose atorvastatin positively improves post-open-heart surgery results.

The connection between C-reactive protein and atherosclerosis

The connection between C-reactive protein (CRP) and atherosclerosis lies on three grounds. First, the concentration of CRP in the serum, which is measured by using highly sensitive (a.k.a. 'hs') techniques, correlates with the occurrence of cardiovascular disease. Second, although CRP binds only to Fcgamma receptor-bearing cells and, in general, to apoptotic and damaged cells, almost every type of cultured mammalian cells has been shown to respond to CRP treatment. Many of these responses indicate proatherogenic functions of CRP but are being reinvestigated using CRP preparations that are free of endotoxins, sodium azide, and biologically active peptides derived from the protein itself. Third, CRP binds to modified forms of low-density lipoprotein (LDL), and, when aggregated, CRP can bind to native LDL as well. Accordingly, CRP is seen with LDL and damaged cells at the atherosclerotic lesions and myocardial infarcts. In experimental rats, human CRP was found to increase the infarct size, an effect that could be abrogated by blocking CRP-mediated complement activation. In the Apob (100/100) Ldlr (-/-) murine model of atherosclerosis, human CRP was shown to be atheroprotective, and the importance of CRP-LDL interactions in this protection was noted. Despite all this, at the end, the question whether CRP can protect humans from developing atherosclerosis remains unanswered.

Relation between plasma adiponectin, high-sensitivity C-reactive protein, and coronary plaque components in patients with acute coronary syndrome

The present study investigated the relation between plasma high-sensitivity C-reactive protein (hs-CRP) and adiponectin and coronary plaque components in patients with acute coronary syndrome (ACS). Previous studies showed a pivotal role of inflammation in the progression of atherosclerosis and the prognostic value of several biomarkers. However, relations among inflammatory biomarkers and plaque characteristics were unknown. Ninety-three culprit plaques (ACS n = 50, non-ACS n = 43) and 56 nonculprit plaques (ACS n = 28, non-ACS n = 28) were analyzed using Virtual Histology intravascular ultrasound to examine relations among plasma hs-CRP, adiponectin, and ratios of each coronary plaque component. Plasma adiponectin was significantly lower and plasma hs-CRP was significantly higher in patients with than without ACS. Culprit plaques in patients with ACS had greater amounts of necrotic core plaque than those in patients without ACS. There was an inverse relation between serum hs-CRP and adiponectin with regard to necrotic core ratio in both culprit and nonculprit lesions in patients with ACS, but not those without ACS. In conclusion, increased plasma hs-CRP and hypoadiponectinemia might be related to the progression of ACS.

Serum adiponectin, C-reactive protein and TNF-alpha levels in obese Korean children

AIM

To determine whether there are differences of serum adiponectin, CRP and TNF-a levels between obese and non-obese children and to investigate the relationship between childhood obesity and inflammation.

METHODS

A total of 103 (73 obese, 30 non-obese) children were evaluated for height, weight, blood pressure and body mass index (BMI). We measured serum adiponectin, hs-CRP, and TNF-alpha levels and analyzed their correlation with BMI, serum glucose, lipid profile and insulin resistance.

RESULTS

Serum adiponectin levels were significantly decreased in the obese children compared to non-obese children, and had a negative correlation with BMI, fasting glucose and HOMA-IR. Serum hs-CRP and TNF-alpha levels were increased in obese children compared to non-obese children, and had a positive correlation with BMI.

CONCLUSIONS

Serum adiponectin level was decreased and serum CRP and TNF-alpha levels were increased in obese children. Our findings suggest that childhood obesity is associated with inflammatory processes.

New risk factors for cardiovascular diseases in patients with rheumatoid arthritis

Introduction In the last three decades numerous epidemiologic studies have shown the correlation between risk factors and cardiovascular diseases. Clinical research has proven that rheumatoid arthritis patients (RA) have higher prevalence of classical risk factors in relation to general population, and over the last few years there has been an emphasis on some new risk factors which can contribute to cardiovascular diseases (CVD). Material and methods This study examined risk factor values for CVD in 88 patients with RA treated at Rheumatology Department, Clinical Hospital Center, Zemun. All patients have been thoroughly examined (clinical findings, laboratory and echocardiographic examination). Apart from classical factors, 'new' risk factors have been examined in all patients: C-reactive proteine (CRP), high-sensitive C-reactive proteine (hs-CRP) and homocystein. Results It has been determined that RA patients have more frequent higher new risk factors in comparison to classical ones. 84.1% of patients had higher CRP values, 97.1% had hsCRP and 39.5% had homocystein. The mean CRP values, especially hsCRP have been higher in patients with positive rheumatoid factor finding. Discussion Rheumatoid arthritis patients may have worse 'background atherosclerosis' than even subjects matched for classical cardiovascular risk factors. Continuous exposure to high grade systemic inflammation may be linked to accelerated atherosclerosis. Conclusions Timely identification of patients with risk factors, particularly with new risk factors, enables adequate approach in prevention of and treatment for CVD in rheumatoid arthritis patients.

Effects of dietary soy protein on iliac and carotid artery atherosclerosis and gene expression in male monkeys

Male cynomolgus macaques (n=91) consumed an isoflavone (IF)-free, atherogenic control diet containing casein/lactalbumin for 5 months, then were randomized to three groups: control (n=30) continued on the control diet; low IF (n=30) received a mixture of unmodified and IF-depleted soy protein isolate (SPI) (0.94 mg IF/g protein, approximating a human intake of 75 mg/day); high IF (n=31) received unmodified SPI (1.88 mg IF/g protein, approximating a human intake of 150 mg/day) for 31 months. Iliac and carotid artery atherosclerosis, and arterial and hepatic mRNA transcripts related to inflammation and estrogen receptors (ER) were measured. Trend analysis identified a significant inverse relationship between dietary IF content and plaque area in the iliac (p<0.05) but not carotid arteries (p>0.13). No significant effect of diet on inflammatory gene or estrogen receptor expression was observed. Plaque area was positively correlated with the mRNA transcript levels for arterial MCP-1, ICAM-1, and the macrophage marker CD68 (all r>0.25, p<0.03), and negatively correlated with ER alpha and ER beta (all r<-0.23, p<0.03). Coronary artery plaque area appeared to be more closely associated with gene expression patterns of the iliac arteries than the carotid arteries. The data suggests benefits of dietary soy on atherosclerotic plaque development in males may be mediated through inflammation-independent pathways. The negative associations of arterial ER alpha expression with atherosclerosis lend support to a mechanistic role for estrogen receptors in atherosclerosis susceptibility which merits further study.

Sex differences in the association between leptin and CRP: Results from the Dallas Heart Study

OBJECTIVE

Higher C-reactive protein (CRP) levels in women compared with men may reflect sex differences in the relationship between obesity and inflammation. We evaluated how the adipokine leptin influenced these relationships.

METHODS AND RESULTS

Dual energy X-ray absorptometry measurements of fat mass and plasma levels of leptin and CRP were measured in 1188 women and 1102 men from the Dallas Heart Study. Analyses were stratified by sex and a leptin/percent fat index was created to evaluate the association between leptin and CRP independent of fat mass. Women had higher body mass index, percent fat mass, and plasma levels of CRP and leptin. CRP levels correlated with leptin levels in both women (Spearman rho=0.48, p<0.0001) and in men (rho=0.27, p<0.0001). In multivariable models adjusting for confounders including total fat mass, leptin/percent fat index remained significantly associated with logCRP in women (p=0.005), but not in men (p=0.95). A significant interaction was observed between sex and leptin levels on CRP (p(interaction)=0.03).

CONCLUSION

Leptin was associated with CRP independent of other measures of obesity in women, but not in men. These findings suggest that sex differences in CRP may reflect sex-related differences in the inflammatory responses to obesity, and may in part, be mediated by leptin.

Reduction of C-reactive protein and the use of anti-hypertensives

Inflammatory processes are increasingly recognized as important participants in the pathophysiology of hypertension and cardiovascular disease. Angiotensin II may be to a large degree responsible for triggering vascular inflammation by inducing oxidative stress, resulting in up-regulation of inflammatory mediators. Inflammatory markers such as C-reactive protein are increased in the blood of patients with hypertension and predict the development of cardiovascular disease. Moreover, C-reactive protein may be a pro-inflammatory molecule under certain circumstances. C-reactive protein and high blood pressure in combination have additional predictive value for cardiovascular outcomes, as they contribute as independent determinants of cardiovascular risk. Therapeutic intervention aimed to reduce vascular inflammation in hypertensive patients has been proposed. Recent lines of evidence suggest that lifestyle modification and pharmacological approaches may reduce blood pressure and inflammation in patients with hypertension. Antagonism of the renin-angiotensin system with the selective angiotensin receptor blockers may improve cardiovascular outcome beyond blood pressure control, by reducing vascular inflammation and remodeling.

C-reactive protein measurement in the patient with vascular disease

C-reactive protein (CRP) is becoming more frequently measured in patients with vascular disease. Awareness of why CRP levels are measured, knowledge of normal versus elevated levels, ability to obtain accuracy in measurement, and teaching appropriate for patients with vascular disease may enhance the care given by vascular nurses. The purpose of this article is to provide a guide for vascular nurses in understanding the role of the serum marker CRP for patients with vascular disease.

C-reactive protein in nipple aspirate fluid associated with Gail model factors

BACKGROUND

The majority of breast cancers originate in the epithelial lining of the breast ductal system. Premalignant cell damage in this lining may produce biochemical signals that deliver inflammatory proteins to the site. The presence of C-reactive protein (CRP) in nipple aspirate fluid (NAF) may reflect an inflammatory state indicative of a premalignant breast microenvironment. This study ascertained CRP's presence in NAF and evaluated if risk factors, as identified by the Gail model, were associated with NAF CRP levels among healthy women.

DESIGN

NAF CRP levels were assayed in 59 women.

RESULTS

CRP was present in NAF and significantly (p = .04) and positively related to breast cancer risk as predicted by the Gail model.

CONCLUSION

CRP is differentially present in NAF and varies by Gail model risk factors. CRP in NAF holds promise as a noninvasive biomarker that detects a precarcinogenic breast ductal microenvironment and may contribute to the diagnosis of breast cancer early in the course of the disease when prognosis is most favorable.

Complement activity and pharmacological inhibition in cardiovascular disease

While complement is the most important component of humoral autoimmunity, and inflammation plays a key role in atherosclerosis, relatively few studies have looked at complement implications in atherosclerosis and its complications. C-reactive protein is a marker of inflammation and is also involved in atherosclerosis; it activates complement and colocalizes with activated complement proteins within the infarcting myocardium and the active atherosclerotic plaques. As new agents capable of modulating complement activity are being developed, new targets for the management of atherosclerosis are emerging that are related to autoimmunity and inflammation. The present paper reviews the putative roles of the various complement activation pathways in the development of atherosclerosis, in ST segment elevation and non-ST segment elevation acute coronary syndromes, and in coronary artery bypass graft surgery. It also provides a perspective on new therapeutic interventions being developed to modulate complement activity. These interventions include the C1 esterase inhibitor, which may be consumed in some inflammatory states resulting in the loss of one of the mechanisms inhibiting activation of the classical and lectin pathways; TP10, a recombinant protein of the soluble complement receptor type 1 (sCR1) which inhibits the C3 and C5 convertases of the common pathway by binding C3b and C4b; a truncated version of the soluble complement receptor type 1 CRI lacking the C4b binding site which selectively inhibits the alternative pathway; and pexelizumab, a monoclonal antibody selectively blocking C5 to prevent the activation of the terminal pathway that is involved in excessive inflammation and autoimmune responses.

Interleukin-17 stimulates C-reactive protein expression in hepatocytes and smooth muscle cells via p38 MAPK and ERK1/2-dependent NF-kappaB and C/EBPbeta activation

Elevated systemic levels of the acute phase C-reactive protein (CRP) are predictors of future cardiovascular events. There is evidence that CRP may also play a direct role in atherogenesis. Here we determined whether the proinflammatory interleukin (IL)-17 stimulates CRP expression in hepatocytes (Hep3B cell line and primary hepatocytes) and coronary artery smooth muscle cells (CASMC). Our results demonstrate that IL-17 potently induces CRP expression in Hep3B cells independent of IL-1beta and IL-6. IL-17 induced CRP promoter-driven reporter gene activity that could be attenuated by dominant negative IkappaBalpha or C/EBPbeta knockdown and stimulated both NF-kappaB and C/EBP DNA binding and reporter gene activities. Targeting NF-kappaB and C/EBPbeta activation by pharmacological inhibitors, small interfering RNA interference and adenoviral transduction of dominant negative expression vectors blocked IL-17-mediated CRP induction. Overexpression of wild type p50, p65, and C/EBPbeta stimulated CRP transcription. IL-17 stimulated p38 MAPK and ERK1/2 activation, and SB203580 and PD98059 blunted IL-17-mediated NF-kappaB and C/EBP activation and CRP transcription. These results, confirmed in primary human hepatocytes and CASMC, demonstrate for the first time that IL-17 is a potent inducer of CRP expression via p38 MAPK and ERK1/2-dependent NF-kappaB and C/EBPbeta activation and suggest that IL-17 may mediate chronic inflammation, atherosclerosis, and thrombosis.

Leptin Induces C-Reactive Protein Expression in Vascular Endothelial Cells

OBJECTIVE

There is increasing evidence of an association between leptin and increased cardiovascular risk. Higher leptin levels are associated with increased levels of C-reactive protein (CRP), which itself elicits proatherogenic effects in the vascular endothelium. We tested the hypothesis that leptin induces CRP expression in human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

We confirmed the presence of both long and short isoforms of the leptin receptor in cultured HCAECs. Leptin but not IFNalphaA/D nor tumor necrosis factor (TNF) alpha, induced expression of CRP. A dose dependent increase of CRP mRNA and protein was observed with increasing concentration of leptin (0 to 400 ng/mL). This increased CRP expression was attenuated in the presence of anti-leptin receptor antibodies and also by inhibition of ERK1/2 by PD98059 (20 to 40 micromol/L). Time (0 to 60 minutes) and leptin concentration (0 to 200 ng/mL)-dependence of ERK1/2 phosphorylation were evident in response to leptin treatment. Leptin also elicited ROS generation. Inhibition of ROS by catalase (200 microg/mL) prevented ERK1/2 phosphorylation and CRP mRNA transcription.

CONCLUSION

Leptin induces CRP expression in HCAECs via activation of the leptin receptor, increased ROS production, and phosphorylation of ERK1/2. These studies suggest a mechanism for the proatherogenic effects of leptin.

C-reactive protein in cardiovascular risk assessment: a review of the evidence

C-reactive protein (CRP) is an inflammatory biomarker that is strongly associated with coronary heart disease, inflammation, and the metabolic syndrome. Large-scale prospective cohort trials have shown that measurement of CRP may add predictive accuracy to the Framingham risk score, but interpretation of these data are conflicting. In the primary prevention setting, CRP can be used to reclassify patients in low or intermediate Framingham risk score groups to a higher risk category, thus making them eligible for more intensive pharmacologic interventions.

Hostility, anger, and depression predict increases in C3 over a 10-year period

We examined the relation of hostility, anger, and depression to 10-year changes in the third (C3), and fourth (C4) complement in 313, apparently healthy male participants enrolled in the Air Force Health Study (AFHS), a 20-year study designed to evaluate the health consequences of dioxin exposure. Hostility, depression, and anger were assessed using subscales from the Minnesota Multiphasic Personality Inventory (MMPI), which was administered in 1985. Given the high intercorrelations among these psychological scales, we used a principal component analysis to generate a composite score representing the linear combination of the hostility, anger, and depression scales. The dependent variables, C3 and C4 levels, were determined from samples collected in 1992, 1997, and 2002. Regression analyses controlling for age, race, alcohol use, body mass index, and cigarette use as well as onset of disease, and use of lipid lowering and blood pressure medications during follow-up revealed a significant timexcomposite score interaction for C3 complement (p<.0003), but not C4. Post-hoc analyses revealed that high composite scores were associated with larger 10-year increases in C3. These observations suggest that men who are hostile and are prone to experience frequent and intense feelings of anger, and depression show activation of the complement system, and specifically increases in C3, that may contribute to the development of coronary heart disease.

C-reactive protein and atherogenesis: from fatty streak to clinical event

In recent years, it has become increasingly clear that arterial inflammation represents a key feature determining the course of atherogenesis. The consecutive stages in the evolution of atherosclerotic lesions are respectively, plaque buildup and growth, and destabilization, predisposing to plaque rupture and intravascular thrombosis. This chain of events leading from lesion formation to clinical events has been carefully elucidated during the last three decades. C-reactive protein (CRP) has been directly implicated in the pathogenesis of atherosclerosis. In the present review, we will focus on a potentially causal role of CRP during the various stages of atherogenesis.

Differential associations of traditional and non-traditional risk factors with carotid intima-media thickening and plaque in peritoneal dialysis patients

BACKGROUND

This study sought to examine the associations of traditional and non-traditional cardiovascular risk factors with carotid intima-media thickening and plaque in peritoneal dialysis (PD) patients.

METHODS

A cross-sectional study was performed in 147 PD patients with carotid intima-media thickness (IMT) and plaque assessed by B-mode ultrasonography and fasting blood collected for biochemical measurements.

RESULTS

On univariate analysis, age, smoking history, fibrinogen, C-reactive protein (CRP), adiponectin, fetuin-A, lipoprotein(a) and diastolic blood pressure were associated with carotid IMT while age, smoking history, diabetes, CRP and diastolic blood pressure were associated with carotid plaque. Using multivariate analysis, elevated CRP (p = 0.015) and serum calcium (p = 0.022) were associated with carotid plaque but not with IMT. CRP and serum calcium were synergistically associated with carotid plaque in that those with CRP > median and serum calcium > median showed the highest prevalence of carotid plaque than either factor alone (p = 0.003).

CONCLUSIONS

An elevated CRP appeared to be a better biomarker of presence of carotid plaque than intima-media thickening. Furthermore, CRP and serum calcium showed synergistic association with presence of carotid plaque. However, our study was limited by the cross-sectional design and baseline laboratory abnormalities were inevitably confounded by the treatment already given, resulting in difficulty to distinguish cause and effect relationship. Nevertheless, these observations warrant further investigation as it may potentially have important implications on differentiating therapeutic strategies for reducing carotid IMT and plaque progression in PD patients.

Obesity, and not obstructive sleep apnea, is responsible for increased serum hs-CRP levels in patients with sleep-disordered breathing in Delhi

OBJECTIVE

The present study was conducted to evaluate serum levels of high-sensitivity C-reactive protein (hs-CRP) in newly diagnosed patients with obstructive sleep apnea (OSA).

SUBJECTS AND METHODS

Between April 2005 and March 2006, a total of 231 consecutive adult habitual snorers underwent polysomnography (PSG) in the sleep laboratory. Ninety-seven subjects were found suitable for hs-CRP measurement after application of the following exclusion criteria: patients with diabetes mellitus, hypertension, coronary artery disease, acromegaly, hypothyroidism, chronic renal failure, congestive cardiac failure, or smoking history, patients who were pregnant, on steroid treatment, on hormone replacement therapy, or with chronic use of drugs such as non-steroidal anti-inflammatory drugs, oral anticoagulants and lipid-lowering drugs and patients having undergone upper airway surgery. Patients were classified as apneic [apnea-hypopnea index (AHI)>5], obese non-apneic [body mass index (BMI)>25, AHI<5] and non-obese non-apneic (BMI<25, AHI<5). C-reactive protein levels were measured in stored sera by high-sensitivity enzyme immunoassay (Biocheck, Inc. Foster City, CA, USA). After checking normality with the Kolmogorov-Smirnov test and using a square-root transformation, Pearson's and partial correlation coefficients were calculated for identified risk factors and confounders. A multiple linear regression model was used to identify variables that were independently associated with hs-CRP.

RESULTS

The mean serum levels of hs-CRP were found to be 0.25+/-0.23, 0.58+/-0.55, and 0.51+/-0.37 mg/dl in non-obese non-apneics (n=23), obese non-apneics (n=45) and apneics (obese and non-obese, n=29), respectively. Pearson's correlation coefficient of hs-CRP with BMI was found to be 0.25 (p=0.01), and with AHI 0.16 (p=0.12). Partial correlation analysis showed that hs-CRP levels correlated significantly with BMI after adjustment for AHI and age (r=0.22, p=0.03), while correlation with disease severity as assessed by AHI after adjustment for BMI and age was not significant (r=0.10, p=0.33). After stepwise multiple linear regression, only BMI was found to be significantly associated with serum hs-CRP levels (beta=0.02, p=0.01).

CONCLUSIONS

In this first comprehensive cross-sectional study on Indian subjects, we found that obesity, and not obstructive sleep apnea, is associated with elevated serum levels of hs-CRP. No independent correlation was found between severity of OSA and hs-CRP in the present study.

C-reactive protein levels and their relationship with metabolic syndrome and insulin resistance in Mexican adolescents

OBJECTIVE

To investigate the relationship of high sensitive C-reactive protein (hs-CRP) with metabolic syndrome components and insulin resistance in Mexican adolescents.

METHODS

325 adolescents, 182 girls and 143 boys, aged 12-16 years were studied. Standardized clinical measurements and plasma lipids, glucose, insulin and hs-CRP were determined. For metabolic syndrome (MS), the NCEP-ATP III definition was used.

RESULTS

MS prevalence was 13%. The most frequent MS components were low HDL-C (50%), high triglycerides (35%), and high waist circumference (28%). hs-CRP median and 75th percentile values for all children were 0.42 and 0.97 mg/dl, respectively. The highest values of hs-CRP were found in children who had MS, p <0.007. hs-CRP was positively correlated with waist circumference, triglycerides, and negatively with HDL-C, p <0.01, and positively with insulin, p <0.001. In stepwise multiple regression analysis, body mass index and HOMA-IR accounted for 10.4% and 12.7% of hs-CRP levels, respectively.

CONCLUSIONS

Body mass index and insulin resistance have an independent effect on high hs-CRP levels, and explain a large part of hs-CRP concentrations in adolescents. Central adipose tissue might induce an inflammatory state that could be identified from adolescence.

Selective estrogen receptor modulators and risk for coronary heart disease

Coronary heart disease (CHD) is the leading cause of death in women in most countries. Atherosclerosis is the main biological process determining CHD. Clinical data support the notion that CHD is sensitive to estrogens, but debate exists concerning the effects of the hormone on atherosclerosis and its complications. Selective estrogen receptor modulators (SERMs) are compounds capable of binding the estrogen receptor to induce a functional profile distinct from estrogens. The possibility that SERMs may shift the estrogenic balance on cardiovascular risk towards a more beneficial profile has generated interest in recent years. There is considerable information on the effects of SERMs on distinct areas that are crucial in atherogenesis. The complexity derived from the diversity of variables affecting their mechanism of action plus the differences between compounds make it difficult to delineate one uniform trend for SERMs. The present picture, nonetheless, is one where SERMs seem less powerful than estrogens in atherosclerosis protection, but more gentle with advanced forms of the disease. The recent publication of the Raloxifene Use for The Heart (RUTH) study has confirmed a neutral effect for raloxifene. Prothrombotic states may favor occlusive thrombi at sites occupied by atheromatous plaques. Platelet activation has received attention as an important determinant of arterial thrombogenesis. Although still sparse, available evidence globally suggests neutral or beneficial effects for SERMs.

Complement regulation in human atherosclerotic coronary lesions

OBJECTIVE

The complement system is activated in human atherosclerotic lesions and may hence aggravate local inflammation. We studied the presence and localization of C4b-binding protein (C4bp), the major inhibitor of the classical complement pathway, in human atherosclerotic lesions in relation to complement activation products and protein S, which circulates in complex with C4bp.

METHODS AND RESULTS

Immunohistochemistry of human coronary arteries showed C4bp to be virtually absent in normal arteries but present in early and advanced atherosclerotic lesions. In the lesions, C4bp is associated with proteoglycans, and affinity chromatography showed that C4bp interacts with human arterial proteoglycans. Areas containing C4bp also contained IgM and C4 suggesting that C4bp is involved in the regulation of the classical complement pathway. However, C5b-9 was virtually absent in these areas but, instead, colocalized with properdin deeper in the intima, suggesting that C5b-9 is formed by the alternative complement pathway. A fraction of C4bp was associated with protein S and apoptotic cells.

CONCLUSIONS

The results indicate that C4bp regulates the classical complement pathway in human atherosclerotic lesions. Thus, unlike the alternative pathway, the classical complement pathway does not generate C5b-9, but is likely to be involved in the clean-up of apoptotic cells and cell debris in the arterial intima.

Systemic High-sensitivity C-reactive Protein Levels in Normal-tension Glaucoma and Primary Open-angle Glaucoma

PURPOSE

To determine the systemic high-sensitivity C-reactive protein (hsCRP) level in patients with normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG).

MATERIALS AND METHODS

With the exclusion of patients with cardiovascular and other systemic diseases, 40 patients with NTG, 40 with POAG, and 40 normal controls were enrolled in this study. Each patient underwent blood sampling for hsCRP, biochemistry, and lipid profile analysis.

RESULTS

Each group had similar demographic parameters including the age, sex, body mass index, heart rate, and blood pressure. There was no statistically significant difference in the hsCRP and biochemistry results between the 3 groups. The lipid profile exhibited a mild elevation in the patients with POAG.

CONCLUSIONS

Our data revealed no difference in the hsCRP level between NTG, POAG, and normal controls after exclusion of patients with cardiovascular and other systemic diseases. Systemic vascular inflammation may not be a major cause in the pathogenesis of glaucoma in those without histories of cardiovascular diseases.

C-Reactive protein-induced endothelial microparticle generation in HUVECs is related to BH4-dependent NO formation

BACKGROUND

C-reactive protein (CRP) has been proven to facilitate endothelial injury via reduced NO production. Endothelial microparticles (EMPs) have emerged as a novel marker of endothelial injury.

METHODS

In vitro cultured human umbilical vein endothelial cells (HUVECs) were incubated with CRP (20 mg/l) for 24 h. The numbers of EMPs with CD31- and CD51-positive staining were assessed flow-cytometrically, and NO production was measured using the Griess reaction in the presence or absence of tetrahydrobiopterin (BH(4)), respectively.

RESULTS

The number of EMPs was significantly increased in HUVECs stimulated by CRP compared with the control group and, in parallel, NO production was decreased (p < 0.05). In the presence of CRP, pretreatment with BH(4) decreased EMP counts and restored NO production to baseline levels (p < 0.05) while pretreatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), a BH(4) synthesis inhibitor, further prompted EMP formation and decreased NO production (p < 0.05). However, adding exogenous BH(4) after pretreatment with DAHP suppressed EMP formation and restored NO production (p < 0.05).

CONCLUSIONS

This study demonstrates that CRP induces EMP generation in HUVECs and this effect is, at least in part, related to impaired BH(4)-dependent NO production. Augmented EMP generation in HUVECs is suggested as a novel potential mechanism contributing to the pathogenesis of vascular injury related to CRP.

C-reactive protein genetics is associated with carotid artery compliance in men in The Cardiovascular Risk in Young Finns Study

Although C-reactive protein (CRP) is known to predict cardiovascular events, its status as a causal risk factor is still controversial. CRP gene single nucleotide polymorphisms (SNPs) have been shown to associate with CRP concentration, but no direct independent effect on early atherosclerotic changes has been demonstrated. We aimed to determine if CRP gene polymorphisms or haplotypes are associated with CRP concentration or carotid artery compliance (CAC), an indicator of subclinical atherosclerosis. We genotyped CRP gene polymorphisms -717A>G, -286C>T>A, +1059G>C, +1444C>T and +1846G>A and measured CRP concentration and CAC in 2283 young adults participating in The Cardiovascular Risk in Young Finns Study. A strong association was found between CRP genotypes and CRP concentration, which was also seen at the haplotype level. Linear regression analysis showed an independent effect of each SNP on CRP concentration after adjustment for risk factors, except for +1444 in males. Moreover, -286C>T>A, +1444C>T and +1846G>A were associated with CAC in males, but not in females. Men carrying the SNP -286 allele C had increased CAC after adjusting for risk factors. These data suggest that the presence of high producer CRP genotype is deleterious to carotid elasticity in men.

Role of C-reactive protein in coronary risk reduction: focus on primary prevention

Given the limitations of current risk assessment strategies, adjunctive markers are needed to improve the prediction of a first coronary event. Research into the inflammatory nature of atherosclerosis suggests that inflammatory-response proteins may serve as potential predictors of clinical events. One in particular, C-reactive protein, has been the focus of much attention. Epidemiologic studies have shown a fairly consistent independent association between high-sensitivity C-reactive protein (hs-CRP) elevations and coronary risk, although a causal relation has not yet been established. Given this association, current guidelines recommend the optional use of hs-CRP to predict enhanced absolute risk in selected patients. The use of a marker in general clinical practice should be based on statistical measures that show incremental benefit over established risk factors and on randomized clinical trials in which therapy initiated as a result of marker screening improves patient outcomes. Thus far, statistical evidence concerning the incremental benefit of hs-CRP is not conclusive. Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) is now being conducted to compare the efficacy of statin therapy versus placebo in subjects considered to be at increased risk on the basis of hs-CRP elevations, despite low to normal levels of low-density lipoprotein cholesterol. In conclusion, although epidemiologic studies suggest that low-grade C-reactive protein elevations are independently associated with coronary risk, more complete evidence is needed to validate the use of hs-CRP as a risk assessment tool in general practice and as a target for therapy in individual patients.

Widespread vascular production of C-reactive protein (CRP) and a relationship between serum CRP, plaque CRP and intimal hypertrophy

OBJECTIVES

Evidence of local vascular production and a relationship between serum hsCRP levels and tissue expression of CRP in subjects with vascular disease would support a direct role for CRP in atherosclerosis.

METHODS AND RESULTS

Vascular tissue from subjects undergoing coronary artery bypass grafting surgery (CABGS) (n=28) and carotid endarterectomy (CEA) (n=25) were studied. Histological samples were assessed for intima-media ratio (IMR) and CRP by immunohistochemistry. CRP mRNA was quantified by real-time polymerase chain reaction. CRP mRNA was seen in all plaques, non-atherosclerotic artery and atrium but no difference in mRNA expression was seen between plaque and non-atherosclerotic tissue. Serum hsCRP correlated with IMR (r=0.64, p=0.001) in non-atherosclerotic arteries and with plaque CRP staining (r=0.57, p=0.009) independent of age, BMI, lipids, diabetes and blood pressure. In a separate patient series, serum hsCRP was measured in aortic and coronary sinus blood from subjects undergoing CABGS or angiography (n=54). There was a coronary circulation hsCRP gradient ([mean+/-S.E.M.] aortic CRP 4.3mg/l+/-0.8 versus coronary sinus 5.8+/-1.2mg/l, p<0.05).

CONCLUSIONS

Widespread vascular CRP mRNA expression, a correlation between serum hsCRP, intimal hypertrophy and plaque CRP, and a coronary hsCRP gradient suggest vascular secretion may contribute to serum CRP levels.

C-reactive protein is expressed and secreted by peripheral blood mononuclear cells

C-reactive protein (CRP) protects against bacterial pathogens and is a predictor of cardiovascular events. CRP is produced by vascular and organ-specific cells but the generation of CRP from peripheral blood mononuclear cells (PBMC) is poorly established. In a randomized, double-blind, placebo-controlled, two-way cross-over trial six healthy volunteers received a bolus infusion of 20 IU/kg Escherichia coli endotoxin [lipopolysaccharide (LPS)] or placebo. Intracellular CRP protein and CRP secretion of peripheral blood mononuclear cells (PBMC) was measured at baseline and 6 h after LPS by flow cytometry and enzyme-linked immubosorbent assay (ELISA), respectively. CRP mRNA expression was determined by real-time polymerase chain reaction (PCR). Regulation of the expression pathway was assessed using specific inhibitors in vitro. Small amounts of CRP protein and mRNA were detectable in PBMC, which were up-regulated between two- and eightfold by endotoxaemia in vivo. Augmented expression and release of CRP by LPS was consistent in PBMC cell culture experiments. LPS, interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-alpha increased and IL-10 reduced CRP expression in PBMC. Toll-like receptor (TLR)-4, nuclear factor (NF)-kappaB and protein kinase C (PKC) activation were identified as intracellular signal transduction pathways of LPS-induced CRP expression. Constitutive CRP expression and release in PBMC is enhanced by inflammatory stimuli in vivo and in vitro. LPS might induce CRP generation via activation of TLR-4, NF-kappaB and PKC.

Antibodies against C-reactive protein cross-react with 60-kilodalton heat shock proteins

C-reactive protein (CRP) is an acute-phase reactant frequently used in histochemistry as a marker of ongoing inflammation. Furthermore, CRP is a powerful biomarker for the prediction of coronary artery disease risk. Heat-shock protein 60 (Hsp60) and CRP are complement-activating molecules, and the effect of their interactions on the regulation of complement activation was studied. However, during the first experiments, we learned that polyclonal anti-CRP antibodies cross-react with Hsp60. Therefore, the aim of our present study was to analyze the cross-reactivity of anti-CRP antibodies (Ab) with Hsp60 in solid-phase enzyme immune assays, in epitope studies using a series of overlapping synthetic peptides, and in Ouchterlony analyses. We found that three different commercial rabbit polyclonal antibodies and two monoclonal (9C9 and CRP-8) anti-CRP antibodies specifically recognize recombinant human Hsp60 and recombinant Mycobacterium tuberculosis Hsp65, respectively. Hsp60 was found to inhibit the binding of anti-CRP polyclonal Ab to Hsp60. Six epitope regions of Hsp60 were recognized by the anti-CRP antibodies, and one region (amino acids [AA] 218 to 232) was recognized by monoclonal antibodies CRP-8 and 9C9. This epitope region of Hsp60 displays 26.6% amino acid identity to CRP AA region 77 to 90. These data suggest that the B-cell epitopes shared between CRP and Hsp60 give rise to a true mimicry-based cross-reaction and the induction of cross-reactive antibodies. Our study underlines the importance of thorough study design and careful interpretation of results while using polyclonal anti-CRP antibodies for histochemistry, especially at low dilutions. Furthermore, analytical interference with Hsp60 in CRP assays should also be tested.

Antibody and Complement in Transplant Vasculopathy

Advances in immunosuppression have decreased the incidence of acute rejection, but the development of vasculopathy in the coronary arteries of transplants continues to limit the survival of cardiac allografts. Transplant vasculopathy has also been referred to as accelerated graft arteriosclerosis because it has features of arteriosclerosis, but it is limited to the graft and develops over a period of months to years. Although the pathological features of transplant vasculopathy are well defined, the causative mechanisms are not completely understood. This review focuses on the mechanisms by which antibody and complement can cause or contribute to coronary vasculopathy in cardiac transplants. Antibodies and complement can have independent effects, but the combination of antibodies and complement with inflammatory cells has greater pathogenic potential for the endothelial and smooth muscle cells of the coronary arteries. For example, stimulation through receptors for IgG or complement split products can activate macrophages, but stimulation through combinations of these receptors generates synergistic results. Together, antibodies and complement efficiently integrate the activation of endothelial cells, platelets, and macrophages, which are 3 of the primary components in the pathogenesis of transplant vasculopathy. Recent findings indicate that antibodies and complement produced within the transplant may contribute to vascular pathology in some transplants. Acute rejection caused by antibodies and complement has been treated by combinations of plasmapheresis, intravenous gamma-globulin and monoclonal antibodies to CD20 on B lymphocytes. The effect of these treatment modalities on the development of coronary vasculopathy is unknown.

C-reactive protein: a nontraditional serum marker of cardiovascular risk

Cardiovascular disease (CVD) is multifactorial in etiology. Traditional cardiovascular risk factors, such as increased cholesterol concentrations and blood pressure, are used to assess CVD risk. Recently, better understanding of the role of inflammation in atherosclerosis has prompted many to propose the measurement of various inflammatory markers to better identify those who are at increased risk. C-reactive protein (CRP) is found in endothelial atherosclerotic lesions, and evidence suggests that it may play a role in atherogenesis. Of candidate serum markers that might add information to clinical risk assessment, high-sensitivity C-reactive protein (hsCRP) measurement has the most potential for clinical use for multiple reasons: (a) high hsCRP is associated with a twofold to a threefold increase in the prevalence of myocardial infarction, stroke, and peripheral vascular disease, and it predicts incident cardiovascular events in those with and without preexisting CVD; (b) the increased risk associated with high hsCRP is independent of other established risk factors; (c) hsCRP augments the predictive capacity of the Framingham Risk Score; (d) hsCRP assays are standardized, and this analyte is biologically stable over time; (e) various risk-reducing interventions also reduce hsCRP, and research is underway to assess whether specifically targeting hsCRP reduces CVD risk. National guidelines regarding the clinical utility of hsCRP in primary and secondary prevention settings have been recently issued.

Calcification of coronary intima and media: immunohistochemistry, backscatter imaging, and x-ray analysis in renal and nonrenal patients

Coronary calcification is a potent predictor of cardiac events. In patients with chronic renal disease, both prevalence and intensity of coronary calcification are increased. It has remained uncertain whether it is the intima of the coronaries or the media that is calcified and whether the morphologic details of calcified plaques differ between renal and nonrenal patients. Autopsy samples of coronaries were obtained from standard sites in 23 renal and 23 age- and gender-matched nonuremic patients. Specimens were examined using light and electron microscopy, immunohistochemistry, backscatter imaging, and x-ray analysis. In coronaries, calcified plaques occupied a similar proportion of the intima area in renal versus nonrenal patients (17.3 +/- 11.9 versus 18.1 +/- 11.9%) but occupied a significantly higher proportion of the media (16.6 +/- 10.6 versus 3.8 +/- 2.31%). Expression of the proteins osteocalcin, C-reactive protein, TGF-beta, and collagen IV was significantly more intensive around coronary plaques of renal compared with nonrenal patients. The non-plaque-bearing intima of renal patients showed minimal staining for fetuin, but fetuin staining was seen surrounding calcified plaques. In addition, more pronounced deposition of C5b-9 was found around coronary plaques of renal patients, and glycophorin deposition pointed to more past intraplaque hemorrhage in renal patients. Calcification by electron backscatter analysis is more intense in the coronary media, but not if the intima is more intense in renal compared with nonrenal patients. A more marked inflammatory response in renal patients is suggested by more frequent presence and greater intensity of markers of inflammation.

Cell membranes and liposomes dissociate C-reactive protein (CRP) to form a new, biologically active structural intermediate: mCRP(m)

Emerging evidence indicates that C-reactive protein (CRP) has at least two conformationally distinct isoforms, i.e., pentameric CRP (pCRP) and monomeric CRP (mCRP or CRP subunit). Both CRP isoforms are proposed to play roles in inflammation and may participate in the pathogenesis of cardiovascular disease. However, the origin of mCRP in situ and the interplay between the two CRP isoforms under physiological/pathological circumstances remain elusive. Herein, by probing conformational alteration, neoepitope expression, and direct visualization using electron-microscopy, we have shown that calcium-dependent binding of pCRP to membranes, including liposomes and cell membranes, led to a rapid but partial structural change, producing molecules that express CRP subunit antigenicity but with retained native pentameric conformation. This hybrid molecule is herein termed mCRP(m). The formation of mCRP(m) was associated with significantly enhanced complement fixation. mCRP(m) can further detach from membrane to form the well-recognized mCRP isoform converted in solution (mCRP(s)) and exert potent stimulatory effects on endothelial cells. The membrane-induced pCRP dissociation not only provides a physiologically relevant scenario for mCRP formation but may represent an important mechanism for regulating CRP function.

A nuclear receptor corepressor-dependent pathway mediates suppression of cytokine-induced C-reactive protein gene expression by liver X receptor

C-reactive protein (CRP), the prototypical human acute phase protein, is an independent risk predictor of future cardiovascular events, both in healthy individuals and in patients with known cardiovascular disease. In addition, previous studies indicate that CRP might have direct proatherogenic properties. Ligand activation of the liver X receptor (LXR), a member of the nuclear hormone receptor superfamily, inhibits inflammatory gene expression in macrophages and attenuates the development of atherosclerosis in various animal models. We demonstrate herein that 2 synthetic LXR ligands, T0901317 and GW3965, inhibit interleukin-1beta/interleukin-6-induced CRP mRNA and protein expression in human hepatocytes. Knockdown of LXRalpha/beta by short interfering RNAs completely abolished the inhibitory effect of the LXR agonist T0901317 on cytokine-induced CRP gene transcription. Transient transfection experiments with 5'-deletion CRP promoter constructs identified a region from -125 to -256 relative to the initiation site that mediated the inhibitory effect of LXR ligands on CRP gene transcription. Depletion of the nuclear receptor corepressor by specific short interfering RNA increased cytokine-inducible CRP mRNA expression and promoter activity and reversed LXR ligand-mediated repression of CRP gene transcription. Chromatin immunoprecipitation assays indicated that nuclear receptor corepressor is present on the endogenous CRP promoter under basal conditions. Cytokine-induced clearance of nuclear receptor corepressor complexes was inhibited by LXR ligand treatment, maintaining the CRP gene in a repressed state. Finally, treatment of C57Bl6/J mice with LXR ligands attenuated lipopolysaccharide-induced mouse CRP and serum amyloid P component gene expression in the liver, whereas no effect was observed in LXRalphabeta knockout mice. Our observations identify a novel mechanism of inflammatory gene regulation by LXR ligands. Thus, inhibition of CRP expression by LXR agonists may provide a promising approach to impact initiation and progression of atherosclerosis.

Biomarkers of atherosclerotic plaque instability and rupture

Basic research over the last two decades has identified a large number of molecules pertinent to the atherosclerotic process, which have clearly improved our understanding of the underlying pathology. It is now well established that inflammation represents a major feature which is present in the vessel wall throughout all stages of the disease until the final pathophysiologic steps, representing plaque destabilization and eventually plaque rupture. Several cells typical for the atherosclerotic plaque, like monocyte-derived macrophages and T-lymphocytes are able to produce and secrete such mediator molecules, like cytokines, chemokines, growth-factors, enzymes, and disintegrins, which lead to activation of endothelial cells, proliferation of smooth muscle cells, lesion progression, and finally to the weakening of a vulnerable plaque by matrix degradation of its fibrous cap. Today, many of these molecules involved can be measured systemically by sensitive assays, and elevated concentrations in the circulation have been shown to be associated with future cardiovascular events. Determination of several of these molecules carries important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification. However, for most of these biomarkers the clinical utility has not yet been established.

C-reactive protein in hypertension: clinical significance and predictive value

Mild elevations in C-reactive protein concentration predict myocardial infarction, stroke, and vascular death in a variety of clinical settings. Despite the lack of specific evidence that C-reactive protein levels are independently associated with cardiovascular risk in patients with hypertension, the prognostic value of C-reactive protein has proven to be complementary to that of blood pressure values. Recent epidemiological evidence has indicated a link between hypertension and increased C-reactive protein levels, and there are some indications that C-reactive protein may predict the future development of hypertension. Vessel wall inflammation is part of the vascular changes observed in animal models of hypertension. C-reactive protein is involved in the complex pathways leading to endothelial dysfunction, increased peripheral vascular resistance, and large artery stiffness in hypertension. In this regard, the role of C-reactive protein as a marker or a causal factor in promoting hypertension and its complications remains, however, to be elucidated. In this review, various aspects of the pathogenesis of inflammation in hypertension are summarized and connected with clinical studies that address the role of C-reactive protein in hypertensive disease.

C-reactive protein and cardiovascular disease in people with diabetes: high-sensitivity CRP testing can help assess risk for future cardiovascular disease events in this population

Having both diabetes and an elevated C-reactive protein (CRP) level compounds one's risk of developing cardiovascular disease, for which people with diabetes are at particularly high risk. CRP is both a biomarker for infectious and noninfectious disorders associated with inflammation and a risk factor for such conditions. Many researchers now believe that the protein also plays a role in the disease processes. The American Heart Association and the Centers for Disease Control and Prevention recently defined three cardiovascular risk categories relative to CRP levels. This article reviews the relevant literature and explores how CRP levels can be used in cardiovascular disease risk assessment, prevention, and treatment.

CRP promotes monocyte-endothelial cell adhesion via Fcγ receptors in human aortic endothelial cells under static and shear flow conditions

Monocyte-endothelial cell adhesion is a key early event in atherogenesis. C-reactive protein (CRP), a cardiovascular risk marker, is known to stimulate ICAM and VCAM in human aortic endothelial cells (HAEC) and induces monocyte-endothelial cell adhesion. In this study, we examined the mechanisms by which native CRP promotes monocyte-endothelial cell adhesion under static conditions and tested the effect of CRP on adhesion under shear flow. Incubation of HAEC with CRP (>25 μg/ml) upregulated NF-κB activity, and this resulted in a significant increase in ICAM (54% increase, P < 0.001), VCAM (41% increase, P < 0.01), and monocyte-endothelial cell adhesion (44% increase, P < 0.02) compared with those of control. Preincubation with antibodies to CD32 and CD64 but not CD16 effectively inhibited this activation. Blocking NF-κB activity with inhibitors or a dominant negative inhibitory κB significantly decreased ICAM, VCAM upregulation, and subsequent monocyte-endothelial cell adhesion. Preincubation with antibodies to CD32 and CD64 or transient transfection with small interference RNA to CD32 attenuated CRP-induced NF-κB activity, ICAM, VCAM, and monocyte-endothelial cell adhesion under static conditions. Also, the Syk kinase inhibitor piceatannol and MG-132, a proteasome degradation inhibitor, produced similar attenuation in NF-κB activity, ICAM, VCAM, and adhesion. Furthermore, CRP-activated endothelial cells supported monocyte rolling, arrest, and transmigration in shear flow (2 dyn/cm2), and this was also inhibited by preincubation with antibodies to CD32 and CD64. Thus, in HAEC, CRP upregulates monocyte-endothelial adhesion by activation of NF-κB through engaging the Fcγ receptors CD32 and CD64.

The inflammatory C-reactive protein is increased in both liver and adipose tissue in severely obese patients independently from metabolic syndrome, Type 2 diabetes, and NASH

OBJECTIVE

C-Reactive Protein (CRP), a nonspecific marker of inflammation that is moderately elevated in obesity, metabolic syndrome (MS), and type 2 diabetes, has been proposed as a surrogate marker of nonalcoholic steatohepatitis (NASH). Its clinical usefulness in the diagnosis of NASH was evaluated in severely obese patients without or with MS, diabetes, and NASH and the potential roles of the liver and of the adipose tissue in CRP production were characterized.

METHODS

Severely obese patients without NASH (without MS [N = 13], with MS [N = 11], or with MS and diabetes [N = 7]) and with NASH (without [N = 8] or with [N = 7] MS) were studied. For each patient, liver and adipose tissue biopsies were collected during a bariatric surgery and were used to determine the CRP gene expression by real-time PCR. The role of interleukin-6 (IL6) and lipopolysaccharide in CRP expression was also evaluated in subcutaneous adipose tissue obtained during cosmetic abdominoplasty.

RESULTS

Plasma CRP levels were elevated in severely obese patients independently from the presence or absence of MS, diabetes, or NASH. CRP gene expression was not only increased in livers but also in adipose tissues of obese patients compared with controls subjects. In human adipose tissue, CRP mRNA levels were positively correlated with those of IL-6 and the CRP expression was enhanced in vitro by IL-6 and lipopolysaccharide.

CONCLUSION

Plasma CRP levels are not predictive of the diagnosis of NASH in severely obese patients. The liver but also the adipose tissue can produce CRP, a process which could be dependent on IL6. Therefore, both tissues might contribute to the elevated plasma CRP levels found in obesity. In addition, the large amount of body fat may well produce an important part of the circulating CRP, further limiting its clinical usefulness in the evaluation of NASH in severely obese patients.