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

Complement C3 and C-Reactive Protein Are Elevated in South Asians Independent of a Family History of Stroke

BACKGROUND AND PURPOSE

Complement components are emerging risk factors for cardiovascular disease. In this study, we examined the relation among C3, C-reactive protein (CRP), factor B, and features of the insulin resistance (IR) syndrome in 143 first-degree relatives of South Asian subjects with ischemic stroke, 141 South Asian controls, and 121 white controls.

METHODS

C3, CRP (high-sensitivity assay), and factor B levels were measured by ELISAs, and their relation to features of the IR syndrome were assessed. Data are presented as geometric mean (95% CI).

RESULTS

There was no significant difference in the levels of C3 between South Asian relatives (1.25 [1.21, 1.29] g/L) and South Asian controls (1.20 [1.15, 1.24] g/L, P=0.2). Levels in both South Asian groups were significantly higher than in white controls (0.95 [0.92, 0.98] g/L; P<0.001 for both comparisons). These differences remained significant after adjustment for covariates. Similarly, levels of CRP were not different between the 2 South Asian groups, but levels in both South Asian groups, after adjustment for covariates, were significantly higher than in white controls. There was no difference in the levels of factor B among the 3 groups. South Asian subjects with elevated C3 levels clustered risk factors associated with IR to a greater extent than those with high CRP.

CONCLUSIONS

These results suggest that South Asians have a greater level of chronic subclinical inflammation than do whites, independent of a family history of stroke. In addition, C3 is more likely to cluster with features of the IR syndrome compared with CRP in South Asians.

Serum markers of vascular inflammation in dyslipemia

Atherosclerosis is widely recognized as an inflammatory disease because systemic and local inflammatory events mediate all phases of plaque development and progression. Basic and clinical studies have focused on identifying potentially useful markers of inflammation. In this article, we review the inflammatory pathogenesis of atherosclerosis, and highlight recent results of several of the more promising markers of inflammation for cardiovascular risk assessment. Of these markers, the most reliable and accessible for clinical use is currently high-sensitivity C-reactive protein (CRP). At present, most clinical guidelines do not recommend routine measurement of these inflammatory markers. However, these serum markers of vascular inflammation may be useful as an adjunct to lipid screening, especially for patients whose lipid values may not be severely elevated, but who are at intermediate risk according to scoring systems that take into account multiple established risk factors. In addition, since the pleiotropic effects of statins include the inhibition of inflammatory response, serum inflammatory markers could also be useful for monitoring this action. Nevertheless, several issues have to be evaluated before the measurements of inflammatory markers can be used for cardiovascular risk prediction in either clinical practice or in clinical trials evaluating anti-atherosclerotic drugs.

The L162V polymorphism at the peroxisome proliferator activated receptor alpha locus modulates the risk of cardiovascular events associated with insulin resistance and diabetes mellitus: The Veterans Affairs HDL Intervention Trial (VA-HIT)

BACKGROUND

The Veterans Affairs HDL Intervention Trial (VA-HIT) showed that gemfibrozil, which activates peroxisome proliferator-activator receptor alpha (PPARalpha), significantly reduced the risk of cardiovascular (CV) events in men with low HDL cholesterol (< 40 mg/dl) and established coronary heart disease. Treatment was particularly beneficial in those with insulin resistance (IR) or diabetes mellitus (DM). We hypothesized that the association between a functional polymorphism at the PPARA locus (L162V) and the risk of a CV event, as well as response to fibrate therapy, might be greatest in those with either IR or DM (DM/IR) in VA-HIT.

METHODS AND RESULTS

A total of 827 men (placebo, n = 413; gemfibrozil, n = 414) from the VA-HIT were genotyped. This population included a high proportion of subjects with DM/IR. In VA-HIT, the PPARA V162 allele was associated with reduced levels of HDL cholesterol and the presence of DM/IR at baseline. It was also associated with reduced risk of CV events in those with DM/IR but not in those with neither (DM/IR *PPARA genotype, P = 0.005). Among subjects with DM/IR, treatment with gemfibrozil reduced CV events in non-carriers from 29.9 to 17.8% and carriers of the V162 allele from 14.7 to 4.8%. In contrast, carriers of the V162 allele with no DM/IR who were treated with gemfibrozil experienced significantly more CV events than did those who received placebo (20.6% versus 13.6%; P = 0.01).

CONCLUSIONS

The effect of the L162V polymorphism at the PPARA locus on CV risk depends on the presence of DM/IR. Among subjects treated with gemfibrozil, the V162 allele was associated not only with reduced CV risk in subjects with DM/IR, but also with significantly increased CV risk in the absence of these traits, identifying this genetic variant as a potential marker for predicting which subjects may have a favorable response to fibrate therapy.

Vascular effects of TZDs: New implications

The incidence of diabetes, now affecting more than 170 million individuals is growing rapidly. Type 2 diabetes, which accounts for 90% of all diabetes cases, is associated with increased cardiovascular morbidity and mortality. Thiazolidinediones (TZDs), used for the treatment of patients with type 2 diabetes improve insulin sensitivity and endothelial dysfunction and exert beneficial effects on the lipid profile by activating the peroxisome proliferator-activated receptor gamma (PPAR-gamma). Moreover, a large body of evidence indicates that TZDs exhibit antiatherogenic effects independent of their antidiabetic and lipid-lowering properties by modulating inflammatory processes. This review will focus on the role of PPAR-gamma agonists in the vessel wall and summarize their effects on C-reactive protein (CRP), plasminogen activator inhibitor type-1 (PAI-1), matrix metalloproteinase-9 (MMP-9), adiponectin and ATP-binding cassette transporter A1 (ABCA1) and their implications for treatment of advanced stages of atherosclerosis, particularly in a setting of type 2 diabetes.

C-reactive protein in vulnerable coronary plaques

BACKGROUND

An increased level of serum C-reactive protein (CRP) is a known prognostic factor for acute coronary events and sudden cardiac death, and it is associated with coronary calcification. CRP is expressed in coronary arteries, but its role in the development of coronary plaques is unclear.

AIM

To investigate CRP immunoreactivity in relation to the severity of coronary artery disease and plaque morphology in human left anterior descending coronary arteries (LAD).

METHODS

A prospective, consecutive autopsy series of 66 patients (mean age 63.4 years) in Tampere University Hospital, Tampere, Finland.

RESULTS

CRP immunoreactivity was seen in 59% of the cases. In logistic regression analysis with age, sex and body mass index as confounders, CRP immunoreactivity in LAD was associated with >50% stenosis and plaque calcification. All three cases with acute coronary thrombosis due to rupture or erosion of the plaque showed a clear immunopositive reaction. CRP-positive cells were never detected in normal arteries, but were often found in early fibrous plaques (75%) and almost invariably present in the shoulder area of plaques with necrotic core (96%). CRP immunoreactivity adjacent to calcified areas in more stable plaques (71%) was less consistent with one-third of these plaques showing no immunoreactivity.

CONCLUSIONS

CRP immunoreactivity is associated with the progression of atherosclerosis, and especially with unstable coronary plaques. The immunoreactivity could cease at the stable calcified stages of atherosclerosis.

Central obesity as a major determinant of increased high-sensitivity C-reactive protein in metabolic syndrome

INTRODUCTION

Traditional cardiovascular risk factors such as central obesity, high blood pressure and insulin resistance, all constituents of metabolic syndrome, have been associated with increased levels of C-reactive protein (CRP). Therefore, this marker of low-grade inflammation may play a major role in the pathogenesis of cardiovascular diseases. In this study, data from a representative sample of urban adults was used to evaluate the association between CRP and metabolic syndrome, accounting for the type and number of its constituents.

METHODS

Using random digit dialing, 1022 participants, aged 18-92 y, were selected. All participants completed a structured questionnaire comprising of information on social, demographic, behavioral and clinical aspects. Anthropometrics and blood pressure were recorded and a fasting blood sample collected. Metabolic syndrome was defined, according to the Third Report of the Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults, as the presence of three or more of the following characteristics: waist circumference greater than 102 cm in men and 88 cm in women; triglyceride levels > or = 150 mg/dl; high-density lipoprotein cholesterol levels < 40 mg/dl in men and < 50 mg/dl in women; blood pressure > or = 130/85 mm Hg; and serum glucose > or = 110 mg/dl. High-sensitivity CRP was assessed by immunonephelometric assay. After excluding 65 participants with CRP > or = 10 mg/l, 957 subjects (599 women and 358 men) remained for analysis. Geometric means were compared after adjustment for age, sex, alcohol consumption and smoking.

RESULTS

Higher mean levels of CRP (2.34 vs 1.36, P < 0.001) were observed when metabolic syndrome was present. Also, mean CRP levels were significantly higher in the presence of central obesity (2.45 vs 1.24, P < 0.001), high blood pressure (1.76 vs 1.12, P < 0.001), hypertriglyceridemia (2.17 vs 1.32, P < 0.001) and high fasting glucose (1.96 vs 1.46, P = 0.032). We found a significant increasing trend (P < 0.001) in mean levels of CRP as the number of features of metabolic syndrome increased. The major contributing features for high CRP levels were central obesity and high blood pressure.

CONCLUSIONS

Present data show that increasing severity of metabolic syndrome is associated with increasing CRP. Additionally, we found that central obesity and high blood pressure are the most important determinants of the low-grade chronic inflammation present in metabolic syndrome.

Helper T cells and atherosclerosis: the cytokine web

There is growing evidence regarding the importance of inflammation in the pathogenesis of atherosclerosis and its ultimate progression to the clinical syndromes. Recently there has been an increasing interest in the role of helper T (Th) cells in atherosclerosis. The Th cells act with the macrophages and the dendritic cells via the various cytokines in bringing about a variety of changes thus leading to the progression of atherosclerosis. Atherosclerotic lesions have been seen to have increased expression of type 1 helper T (TH1) cells together with increased levels of the Th1 related cytokines. It is mainly the cytokines involved with Th1 functioning that seem to show a prominent effect, with the whole process centred around interferon gamma, making it seem like every pathway and the cytokines involved lead to a final common pathway of interferon gamma secretion; the increase or decrease of which dictates the progression of atherosclerosis and its final manifestation as the clinical syndromes.

A comparative study of markers of inflammation for the assessment of cardiovascular risk in patients presenting to the emergency department with acute chest pain suggestive of acute coronary syndrome

BACKGROUND

The role of inflammation in the pathogenesis of acute coronary syndrome (ACS) is established. Little is known however, regarding the use of inflammatory markers as predictors of future cardiovascular events in patients presenting to the emergency department (ED) with suspected ACS.

HYPOTHESIS

To assess whether biomarkers that predict cardiovascular risk in apparently healthy individuals and coronary artery disease patients are useful predictors of future cardiovascular events in patients presenting to the ED with chest pain suggestive of ACS.

METHODS

We compared the abilities of serum C-reactive protein (hs-CRP), albumin and leukocyte count to identify subjects with ACS and those who are at high risk of developing events during a 30-day follow-up.

RESULTS

144 patients (mean age 62+/-13 years, 45 female) presenting to the ED <3 h after the onset of symptoms suggestive of ACS were evaluated. Final hospital diagnoses were non-ischemic chest pain in 43 (30%) and ACS in 101 (70%) patients. Patients with ACS had significantly higher leukocyte count (p<0.0001) and hs-CRP levels (p<0.02) and lower albumin concentrations, compared to patients with NICP (p<0.0001). Lower albumin concentrations (p=0.03) and hs-CRP (p=0.049) were predictors of recurrent events at 30 days. On multivariate analysis, however, only leukocyte count was a predictor of ACS (OR 20.9; 95% CI: 3.7-19.5; p=0.01) and high hs-CRP levels were a predictor of clinical outcome (OR 2.8; 95% CI: 1.5-5.2; p=0.001).

CONCLUSIONS

Leukocyte count is an independent predictor of ACS in patients presenting to the ED with chest pain suggestive of ACS and high hs-CRP levels are an independent predictor of clinical outcome in ACS patients.

Endogenous Expression of C-Reactive Protein Is Increased in Active (Ulcerated Noncomplicated) Human Carotid Artery Plaques

Background and Purpose— There is growing evidence suggesting that C-reactive protein (CRP) is an effecter molecule able to induce and promote atherothrombosis. The presence of CRP in atherosclerotic plaques may reflect local production or infiltration from circulating CRP increased in general inflammatory responses. Our aim was to analyze the presence of CRP in human advanced carotid artery plaques with differential anatomo-pathological characteristics and to assess local expression of CRP and other proinflammatory genes in these lesions.

Methods— Human carotid artery specimens from 38 patients undergoing scheduled endarterectomy were classified into 3 groups: ulcerated (noncomplicated) (UNC, n=19), fibrous (F, n=12) and ulcerated (complicated/hemorrhagic) plaques (UC, n=7). The presence of CRP was evaluated by immunohistochemistry, and plasma samples were screened for circulating high-sensitivity C-reactive protein. TaqMan Low-density Arrays were used for study of genes related to inflammation (CRP, interleukin-6, macrophage colony-stimulating factor-1, monocyte chemotactic protein-1, cyclooxygenase-2).

Results— CRP mRNA levels were predominantly detected in UNC-high risk plaques but not in UC ( P =0.001). UNC also exhibit the highest expression levels of other genes involved in the inflammatory responses: cyclooxygenase-2 ( P <0.005 versus F and versus UC), IL-6 ( P <0.005 versus F and versus UC) and monocyte chemoattractant protein-1 ( P <0.01 versus F and versus UC). Plaque CRP mRNA levels correlated with immunohistochemical findings but were independent of plasma high-sensitivity CRP. In UNC plaques endothelial cells and inflammatory cells were strongly positive for CRP around areas of newly formed microvessels.

Conclusions— In human high-risk carotid artery plaques (UNC) CRP expression reflects an active proinflammatory stage. Local synthesis of CRP could be involved in plaque neovascularization and increased risk of hemorrhagic transformation.

Different inflammatory response and oxidative stress in neointimal hyperplasia after balloon angioplasty and stent implantation in cholesterol-fed rabbits

Inflammatory responses appear to play an important role in the occurrence of restenosis following coronary intervention. However, the contribution of C-reactive protein (CRP) and oxidative stress to restenosis after balloon angioplasty and stent implantation remains unclear. The aim of this study was to examine this issue using hyperlipidemic rabbits. Rabbits were divided into two groups; they were fed with a 0.5% cholesterol diet and with a mixed 0.5% cholesterol and 0.5% probucol diet. Each group of rabbits underwent balloon injury and stent implantation in right and left iliac arteries, respectively. Eight weeks after the intervention, we examined luminal stenosis, neointimal hyperplasia, immunoreactivity for macrophage, CRP and oxidized phosphatidylcholine (oxPC), and also the expression of CRP mRNA. The degrees of neointimal hyperplasia and immunopositive areas (%) for macrophage, CRP, and oxPC in the neointima were significantly higher after stent implantation than after balloon injury, but CRP mRNA was undetectable in either artery. Anti-oxidant probucol reduced angiographic stenosis, neointimal hyperplasia, and macrophage- and oxPC-positive areas much more significantly after stenting. The results demonstrate that the inflammatory response to the development of neointimal hyperplasia differs after balloon injury and stent implantation and that CRP deposition and oxidative stress might be involved more significantly in neointimal development after stent implantation.

Chlamydia pneumoniae infections augment atherosclerotic lesion formation: a role for serum amyloid P

Multiple reports have demonstrated an association between Chlamydia pneumoniae (Cpn) and cardiovascular disease. In this study we evaluated the effect of Cpn infections on early lesion progression in C57BL/6J mice. Since plaque formation in these mice does not develop past the initial stage, we thought these mice might be a better model for unravelling the effect of Cpn infection on early lesion type progression. C57BL/6J mice were fed an atherogenic diet and injected 10 times with 5 x 10(7) IFU Cpn or mock. At sacrifice, lesion number, size and type were analysed. To study the role of Cpn in inflammation, serum amyloid P (SAP) in plasma was determined as well as T-cells, macrophages and SAP in the lesions. In the aortic sinus of both groups, type 2 lesions were found. Cpn infection resulted in a 2.2-fold increase in total lesion size (Cpn: 10821+/-2429 microm(2)vs mock: 5022+/-1348 microm(2); p=0.04). No difference in lesion number was observed. Also, Cpn infection increased SAP in the lesions from 1.10(-4)+/-0.1.10(-4) SAP-positive cells/lesion area to 10.10(-4)+/-1.10(-4) SAP-positive cells/lesion area (p=0.05). The influx of T-lymphocytes and macrophages in the lesions as well as SAP plasma levels were not different between groups. Multiple Cpn infections resulted in a significant increase in total lesion size of C57BL/6J mice. Increase in total SAP-positive area in infected mice suggests a role for this acute-phase protein in lesion enlargement.

Native pentameric C-reactive protein displays more potent pro-atherogenic activities in human aortic endothelial cells than modified C-reactive protein

Inflammation is pivotal in atherogenesis. Numerous prospective studies have shown that levels of high sensitive C-reactive protein (CRP) predict cardiovascular events. Recently, data suggests that CRP could be a mediator in atherothrombosis. Loss of pentameric symmetry in CRP has been shown to result in the formation of modified CRP (mCRP). The main aim of this study was to examine the biological effects of the native, pentameric form of CRP compared to a modified form in human aortic endothelial cells. Human pentameric native CRP (n-CRP) from two different sources (recombinant and serum) was purified and used. It was then subjected to EDTA chelation and urea treatment to prepare modified CRP (m-CRP). Purity of both n-CRP and m-CRP preparations was checked by gel electrophoresis. Both n-CRP and m-CRP were incubated with human aortic endothelial cells (HAEC) and biological activities was tested by assaying for interleukin-8 (IL-8), plasminogen activator inhibitor-1(PAI-1), cyclic GMP and prostaglandin F1-alpha. n-CRP significantly upregulated IL-8 at concentrations > or = 10 microg/mL while m-CRP upregulated IL-8 only at concentrations of 50 microg/mL (p < 0.05). PAI-1 levels were significantly increased to a greater extent with native compared to m-CRP (p < 0.05). While both decreased PGF1-alpha at concentrations of 50 microg/mL, the effect of native CRP was more pronounced and was evident at 10 microg/mL (p < 0.05). The most pronounced difference was observed with regard to inhibition of eNOS activity as assessed by cGMP which was observed at 10 microg/ml of native CRP but only at 50 microg/mL for m-CRP (native CRP versus mCRP: p < 0.001). Thus, native pentameric CRP compared to modified CRP exerts more potent atherogenic effects in human aortic endothelial cells.

Effect of Modified C-Reactive Protein on Complement Activation

OBJECTIVE

The capacity of human C-reactive protein (CRP) to activate/regulate complement may be an important characteristic that links CRP and inflammation with atherosclerosis. Recent advances suggest that in addition to classical pentameric CRP, a conformationally distinct isoform of CRP, termed modified or monomeric CRP (mCRP), may also play an active role in atherosclerosis. Although the complement activation behavior of CRP has been well established, the capacity of mCRP to interact with and activate the complement cascade is unknown.

METHODS AND RESULTS

mCRP bound avidly to purified C1q, and this binding occurred primarily through collagen-like region of C1q. Fluid phase mCRP inhibited the activation of complement cascade via engaging C1q from binding with other complement activators. In contrast, when immobilized or bound to oxidized or enzymatically modified low-density lipoprotein, mCRP could activate classical complement pathway. Low-level generation of sC5b-9 indicated that the activation largely bypassed the terminal sequence of complement, which appears to involve recruitment of Factor H.

CONCLUSIONS

These results indicate that mCRP can both inhibit and activate the classical complement pathway by binding C1q, depending on whether it is in fluid phase or surface-bound state.

C-Reactive Protein Induces Matrix Metalloproteinase-1 and -10 in Human Endothelial Cells

OBJECTIVES

We examined the effect of C-reactive protein (CRP) on matrix metalloproteinase (MMP) and inhibitor expression in endothelial cells and in patients with clinical and subclinical atherosclerosis.

BACKGROUND

In addition to predicting atherosclerotic vascular disease, CRP may directly promote a proinflammatory/proatherosclerotic phenotype.

METHODS

Human umbilical vein endothelial cells (HUVECs) and aortic endothelial cells (HAECs) were incubated in the presence or absence of CRP (50 mug/ml). Microarray analysis, real-time polymerase chain reaction, immunological and activity assays for MMPs were performed. Specific inhibitors of mitogen-activated protein kinase pathway were used. The MMP-1 and -10 plasma levels were measured in apparently healthy subjects (n = 70). Immunolocalization of CRP, MMP-1, and MMP-10 was performed in human mammary arteries and carotid endarterectomy specimens.

RESULTS

C-reactive protein augmented MMP-1 and -10 messenger ribonucleic acid expression in HUVEC (p < 0.05) and HAEC (p < 0.01). C-reactive protein stimulation also increased MMP-1 and -10 protein in conditioned culture medium (p < 0.001), as well as MMP activity (p = 0.001). Specific inhibition of p38 or MEK abolished the CRP induction of the MMP-1, whereas MMP-10 induction blockade required the simultaneous inhibition of p38 and Jun N-terminal kinase pathways. Subjects with CRP values >3 mg/l (n = 37) had increased plasma MMP-1 and -10 (p < 0.05), the association being significant after adjustment for confounding variables (p = 0.04 and p = 0.008, respectively). The MMP-10 levels were elevated in subjects with higher carotid intima-media thickness (p = 0.009). Increased CRP and MMP-10 colocalized in endothelial layer and macrophage-rich areas in advanced atherosclerotic plaques.

CONCLUSIONS

Increased local and systemic CRP-related MMP activation might provide a link between inflammation and plaque vulnerability.

Leptin, soluble interleukin-6 receptor, C-reactive protein and soluble vascular cell adhesion molecule-1 levels in human coronary atherosclerotic plaque

The aim of the present study was to explore the relationship between tissue levels of leptin, soluble interleukin-6 receptor (sIL-6R), high-sensitive-C-reactive protein (hs-CRP) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in atherosclerotic plaques, and traditional risk factors. Coronary artery specimens were obtained from 35 consecutive patients (26 men and nine women) who underwent coronary artery bypass grafting procedure. The mean tissue levels of leptin, hs-CRP and sIL-6R were significantly higher in patients with diabetes mellitus than without diabetes mellitus. When patients were classified according to the smoking status, the mean tissue levels of leptin, hs-CRP and sIL-6R were significantly higher in current smokers than both former smokers and non-smokers. In addition, the mean tissue levels of leptin and sIL-6R were significantly higher in former smokers than non-smokers. There was a positive association between leptin and hs-CRP, sIL-6R and plasma glucose in all patients. Plasma HDL levels were associated negatively with atherosclerotic tissue levels of leptin. Tissue levels of sIL-6R were associated significantly in a positive manner with leptin, hs-CRP and plasma glucose, while tissue levels of hs-CRP were associated with both leptin and sIL-6R. In conclusion, it is attractive to speculate that hs-CRP, sIL-6R and leptin could act synergistically in course of local inflammatory activity and those molecules may not be just markers of inflammation and cardiovascular risk but are also likely to play a pathogenic role in atheromatous plaque. In addition, atherosclerotic tissue levels of CRP, sIL-6R and leptin were significantly higher in current smokers and patients with diabetes.

The novel role of C-reactive protein in cardiovascular disease: risk marker or pathogen

C-reactive protein (CRP) is a non-specific biomarker of inflammation. Recent research has shown that inflammation is an important step in the genesis of atherosclerosis, and is involved in the development of unstable plaques. Measurement of serum levels of CRP using a high sensitivity assay (hsCRP) can demonstrate subclinical inflammatory states, which may reflect vascular inflammation. Clinical studies have shown that elevated hsCRP levels in healthy populations predict vascular events such as myocardial infarction (MI) and stroke as well as the development of diabetes. In patients with acute coronary syndromes, higher hsCRP levels are associated with adverse outcomes and subsequent vascular events. There is data to suggest that aspirin, angiotensin converting enzyme (ACE) inhibitors and HMG Co-A reductase inhibitors (statins), which all reduce vascular event rates, also reduce serum levels of hsCRP and therefore hsCRP levels may potentially guide therapy. As well as having a critical role in risk prediction, recent evidence has emerged implicating CRP directly in atherogenesis. CRP has been found in human atherosclerotic plaque and CRP has been shown to cause endothelial cell dysfunction, oxidant stress and intimal hypertrophy in experimental models. We review the postulated roles of CRP in atherogenesis and prediction of vascular events, as well as discussing current recommendations for CRP testing in patients.

Colocalisation of intraplaque C reactive protein, complement, oxidised low density lipoprotein, and macrophages in stable and unstable angina and acute myocardial infarction

BACKGROUND

C reactive protein (CRP), an important serum marker of atherosclerotic vascular disease, has recently been reported to be active inside human atherosclerotic plaques.

AIMS

To investigate the simultaneous presence of macrophages, CRP, membrane attack complex C5b-9 (MAC), and oxidised low density lipoprotein (oxLDL) in atherectomy specimens from patients with different coronary syndromes.

METHODS

In total, 54 patients with stable angina (SA; n = 21), unstable angina (UA; n = 15), and myocardial infarction (MI; n = 18) underwent directional coronary atherectomy for coronary lesions. Cryostat sections of atherosclerotic plaques were immunohistochemically stained with monoclonal antibodies: anti-CD68 (macrophages), anti-5G4 (CRP), aE11 (MAC), and 12E7 (oxLDL). Immunopositive areas were evaluated in relation to fibrous and neointima tissues, atheroma, and media. Quantitative analysis was performed using image cytometry with systematic random sampling (percentage immunopositive/total tissue area).

RESULTS

Macrophages, CRP, MAC, and oxLDL were simultaneously present in a higher proportion of fibrous tissue and atheroma of atherectomy specimens from patients with UA and MI compared with SA (p<0.05). Quantitative analysis showed significantly higher mean percentages of macrophages in plaques from patients with MI (44%) than UA (30%; p<0.01) and SA (20%; p<0.001). Significantly higher mean percentages of CRP were also seen in MI (25%) and UA (25%) compared with SA (12%; p<0.05).

CONCLUSIONS

The presence of CRP, complement, and oxLDL in a high proportion of plaque tissue from patients with unstable coronary artery disease implies that these surrogate markers have important proinflammatory effects inside atherosclerotic plaques. This may increase vulnerability to plaque rupture and thrombosis, with subsequent clinical sequelae.

Mechanisms of c-reactive protein up-regulation in arterialized vein grafts

BACKGROUND

C-reactive protein (CRP), an acute phase reactant, is an independent predictor of coronary artery syndromes and a mediator of the vascular response to injury. CRP has been found in arterialized vein grafts and has been linked to atherogenesis; however, its involvement in vein graft early failure or intimal hyperplasia has not been assessed. This study was designed to investigate the mechanism(s) of CRP up-regulation in arterialized vein grafts.

METHODS

Carotid artery bypass with arterialized jugular vein grafts (AVG) was performed in 18 dogs. AVG were harvested at 3, 8, and 24 hours and 4, 14, and 28 days, using the femoral vein obtained at the time of AVG harvest as a control. Serum CRP levels were characterized by enzyme-linked immunosorbent assay; AVG expression of CRP was studied by immunofluorescence, Western blotting, in situ hybridization, Northern blotting, and quantitative RT-PCR.

RESULTS

CRP levels peaked at 24 hours in serum and AVG but remained at baseline in control veins. By double immunofluorescence, CRP was associated with the media and adventitia of AVG. However, Northern blotting analysis showed no CRP mRNA expression in AVG. Reverse transcriptase polymerase chain reaction analysis confirmed the lack of up-regulation of CRP in AVG.

CONCLUSION

CRP levels are increased in AVG, peaking 24 hours after arterialization. However, no significant production of CRP was detected in AVG. Therefore, increased CRP levels within AVG appear to originate mostly from CRP diffusion from the systemic circulation. These results have significant implications for the development of strategies aimed at blocking CRP up-regulation in bypass grafts.

C-Reactive Protein: A Family of Proteins to Regulate Cardiovascular Function

Based on a multitude of clinical studies, C-reactive protein (CRP) has emerged as a risk marker for the development of cardiovascular disease, leading to recently published recommendations for screening the general population for plasma CRP level as a predictor for future cardiovascular events. However, uncertainties exist in how to apply these recommendations to populations with very high serum CRP levels and a high prevalence of cardiovascular disease, such as patients with end-stage renal disease. Furthermore, in vitro results are conflicting concerning the role of CRP in the vessel wall. Although many data are in favor of a proinflammatory effect of CRP, evidence is accumulating that CRP also exerts anti-inflammatory actions, mainly in neutrophils and platelets. Many of the apparently contradictory actions of CRP may be attributed to method issues, but, of interest, also may be explained by the existence of 2 distinct conformations of CRP, the native pentamer (nCRP) and modified CRP (mCRP) forms. nCRP is the classical acute-phase reactant detected in serum, whereas mCRP represents a predominantly tissue-bound form. It is detected immunohistochemically, mainly in and around endothelial and vascular smooth muscle cells. Although mCRP activates endothelial cells and neutrophils, induces neutrophil adhesion to the endothelium, and delays apoptosis of neutrophils in vitro, these effects were absent using nCRP. Clearly defined CRP conformers thus may provide a tool for how to reconcile the reported proinflammatory and anti-inflammatory properties of CRP. There is good evidence to believe that CRP is more than just a "bad guy," and further experiments are needed to determine how these 2 configurations contribute to atherogenesis, development of cardiovascular disease, and acute coronary events.

Expression of C-reactive protein by renal cell carcinomas and unaffected surrounding renal tissue

BACKGROUND

Elevation of plasma C-reactive protein (CRP) is common in patients with renal cell carcinoma (RCC). Renal tubular epithelial cells are capable of synthesizing CRP. Although production of interleukin (IL)-6 has been described in RCC, CRP expression by carcinoma cells has yet not been investigated.

METHODS

In the present study we analyzed CRP plasma levels as well as intratumoral CRP and IL-6 expression of RCC from 40 patients who underwent radical nephrectomy by means of quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry. For each tumor, specimens were obtained from tumor center, tumor margin, and unaffected surrounding renal tissue.

RESULTS

Preoperative plasma CRP levels correlated significantly with tumor stage (P = 0.05) and grade (P < 0.01). CRP mRNA expression was detected in 26 of 33 (79%), 30 of 36 (83%), and 32 of 36 (89%) samples from tumor center, tumor margin, and unaffected surrounding tissue, respectively. However, levels of CRP mRNA were significantly higher in tumor tissue compared to adjacent renal tissue (P < 0.01). Clear cell carcinoma exhibited significantly higher CRP mRNA levels than papillary carcinoma (P < 0.05). CRP plasma levels correlated significantly with quantitative levels of CRP mRNA within tumors (P < 0.0001). Immunohistochemically, strong CRP production was observed both in tumor cells and in tubular epithelial cells in unaffected tissue, respectively. All kidneys expressed IL-6 mRNA in the tumor and/or the unaffected tissue, but levels of intratumoral IL-6 mRNA showed no significant correlation with CRP plasma levels or local CRP transcription.

CONCLUSION

In patients with RCC, a tumor-derived origin of some plasma CRP is likely. Activity of the IL-6/CRP network in RCC contributes to the accumulating evidence of the acute-phase reaction as a local inflammatory process.

Prediction of Mortality by High-Sensitivity C-Reactive Protein and Brain Natriuretic Peptide in Patients With Dilated Cardiomyopathy

BACKGROUND

The prognostic role of serum C-reactive protein (CRP) in chronic heart failure (CHF) patients, especially those with nonischemic dilated cardiomyopathy (DCM), remains unknown. In the present study, whether CRP provides prognostic information in DCM patients was evaluated.

METHODS AND RESULTS

Neurohumoral factors and hemodynamics in 84 consecutive DCM patients were measured and these patients were followed up for a mean period of 42 months. During the follow-up period, 23 patients developed cardiac events and 18 patients died of cardiac causes. Using stepwise multivariate Cox proportional hazards regression analyses, log brain natriuretic peptide (BNP) (p = 0.007) and high-sensitivity CRP (hsCRP) > 1 mg/L (p = 0.008) were significant independent predictors of cardiac events. The patients were stratified into 4 groups based on the normal serum concentration of hsCRP (1 mg/L) and median plasma concentration of BNP (110 pg/ml). Survival rates were significantly higher in patients with hsCRP < 1 mg/L and BNP < 110 pg/ml. The hazard ratio of patients with BNP > 110 pg/ml and hsCRP > 1 mg/L was 15.8 (95% confidence interval, 1.9-127.2) compared with those with BNP < 110 pg/ml and hsCRP < 1 mg/L for cardiac death.

CONCLUSIONS

Serum hsCRP level is an independent prognostic predictor in patients with DCM and the combination of hsCRP and BNP may be useful for the management of CHF patients with DCM.

Treatment with combined oral contraceptives induces a rise in serum C-reactive protein in the absence of a general inflammatory response

BACKGROUND

The role of inflammation in the pathogenesis of cardiovascular disease is well established. C-reactive protein (CRP) is the strongest independent predictor of myocardial infarction and stroke in women. Recent studies have indicated that CRP levels are raised during use of combined oral contraceptives (COCs).

OBJECTIVES

The aim of the study was to investigate the effect of COCs on serum CRP levels and to indicate the underlying mechanisms of an expected increase.

METHOD

In a prospective randomized cross over-study 35 women used two different preparations of COC, one second and one third generation. Serum levels of CRP, serum amyloid A (SAA), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), antibodies against oxidized LDL, insulin and insulin-like growth factor-I (IGF-I) along with insulin-like growth factor binding protein-1 (IGFBP-1) and IGFBP-3 were analyzed before and during the two treatments. E-selectin, von Willebrand factor and factor VIII concentrations in plasma were also measured.

RESULTS

A rise in serum CRP was observed during both treatments; the median level increased from 0.45 mg L(-1) at baseline to 1.48 mg L(-1) with second generation and to 2.02 mg L(-1) with third generation COC. The serum levels of SAA increased slightly during treatment with the third generation COC. IL-6 and TNFalpha were unaffected by treatment. Both preparations lowered IGF-I and raised IGFBP-1 and IGFBP-3 concentrations.

CONCLUSION

The raised serum CRP concentration during treatment with COCs appears to be related to a direct effect on hepatocyte CRP synthesis and does not reflect IL-6 mediated inflammation, endothelial activation or induction of insulin resistance.

The role of biomarkers in the assessment of lupus

Although considered a prototypic autoimmune disease, the hallmark of systemic lupus erythematosus (SLE) is its heterogeneity. Accordingly, manifestations can vary widely from person to person, with the potential involvement of virtually any bodily organ. Furthermore, the genetic abnormalities underlying this condition are complicated, with diverse genetic polymorphisms described in different ethnic groups, strongly suggesting that the actual pathology underlying the immunologic disarray might not be the same for each patient. Evolving concepts of genetics and immunity have clarified that patients can carry unique arrays of exacerbating and protective factors. These factors, in conjunction with variable environmental triggers for SLE, probably determine the sequelae that an individual experiences. Therefore, it is not surprising that the clinical manifestations are diverse, the temporal sequence of organ involvement often unpredictable, and that the flares of inflammatory activity that characterize SLE can either remit without consequence or leave permanent damage in their wake. It is widely accepted that the current standard of care for SLE patients is inadequate. Programs to develop and test new drug and/or device therapies have been ongoing since the mid-1990s but have encountered formidable obstacles. With the current burst of drug discovery and the advent of several large international trials of promising new agents, the challenge to overcome these obstacles has never been greater. A burgeoning literature in the past decades nevertheless suggests that despite the complexities of the many immunologic pathways that impact on SLE, characteristic biologic markers are emerging as potential signposts that can characterize patient subgroups, predict prognosis, mark the exacerbations and remissions of SLE flares, and serve as endpoints in the determination of the dosing and timing of immune-modulating treatments. Several of the promising biomarkers are addressed in this chapter.

Coronary stenting and inflammation

Restenosis after stent implantation is mainly caused by neointimal proliferation through the stent struts. Experimental studies performed in the last decade indicate that inflammatory mechanisms play a key role in the process of neointimal proliferation and restenosis. Coronary stenting is a strong inflammatory stimulus, and the acute local and systemic inflammatory responses to local inflammation produced by coronary stenting are highly individual and predictive of restenosis and event-free survival. The benefit of anti-inflammatory periprocedural therapy, such as with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and steroids, and long-term follow-up is dependent on the individual's inflammatory status. Measurement of acute-phase reactants, such as C-reactive protein plasma concentration, appears to be important for the identification of subjects at high risk and the development of specific treatment tailored to individual patients.

Production of modified C-reactive protein in U937-derived macrophages

Plasma C-reactive protein (CRP) has been proposed to be a strong independent predictor for cardiovascular disease. This circulating form of CRP (native CRP or nCRP) is well described. Recently, the existence of a conformationally distinct isoform of CRP (modified CRP or mCRP) has been reported. The relevance of each CRP isoform to atherosclerotic disease is unknown. The purpose of this study was to examine the natural expression of CRP in undifferentiated, differentiated, and stimulated macrophages, cells known to contribute to atherogenesis in vivo, and to determine whether transcribed CRP was expressed as nCRP or mCRP. Macrophages were generated from U937 monocytes using phorbol 12-myristate 13-acetate. Differentiated macrophages were further stimulated with lipopolysaccharides (LPS). In undifferentiated, differentiated, and stimulated cells, CRP expression was assessed by reverse transcription-polymerase chain reaction, and CRP protein production was measured by fluorescence microscopy and flow cytometry (cellular CRP) or high-sensitivity enzyme-linked immunosorbent assay (secreted CRP). CRP transcript was minimally expressed in undifferentiated cells. Expression increased markedly in macrophages during differentiation and was not affected by LPS at 24 hrs. Cellular CRP protein increased in a time-dependent manner after LPS stimulation, and this induction was mediated via interleukin (IL)-6 and IL-1beta. A small amount of secreted CRP was detected in the media of differentiated cells, but it was not significantly increased after LPS stimulation. Using specific monoclonal antibodies, our data indicate that cellular CRP is directly translated as the mCRP rather than the nCRP isomer. These results indicate that U937-derived macrophages are a good cell model to further study the production of mCRP under conditions relevant for the atherogenic process.

C-reactive protein in atherosclerotic lesions: its origin and pathophysiological significance

C-reactive protein (CRP) is frequently deposited in the lesions of the arterial intima; however, the origin and pathological significance of CRP in these lesions are not completely understood. In this study, we measured CRP levels in the plasma of hypercholesterolemic rabbits and investigated CRP expression at both the mRNA and protein levels using rabbit and human atherosclerotic specimens. CRP levels were significantly elevated in both cholesterol-fed and Watanabe heritable hyperlipidemic rabbits, and CRP levels were clearly correlated with aortic atherosclerotic lesion size. Immunohistochemical staining coupled with Western blotting analysis revealed that CRP-immunoreactive proteins were found at all stages of atherosclerosis from the early to advanced lesions. CRP was present extracellularly and co-localized with apolipoprotein B but was rarely associated with the cytoplasm of macrophages and foam cells. Real-time reverse transcriptase-polymerase chain reaction analysis revealed that CRP mRNA in atherosclerotic lesions was barely detectable, and isolated macrophages did not express CRP mRNA, suggesting that CRP proteins found in the lesions were essentially derived from the circulation rather than synthesized de novo by vascular cells. These results suggest that there is a link between plasma CRP and the degree of atherosclerosis and that inhibition of plasma CRP may represent a therapeutic modality for the treatment of cardiovascular disease.

C-reactive protein increases matrix metalloproteinase-2 expression and activity in cultured human vascular smooth muscle cells

The C-reactive protein (CRP) is a strong predictor of cardiovascular events both in the general population and in patients with coronary artery disease. We aimed to evaluate whether in cultured human vascular smooth muscle cells (hVSMC) CRP modulates the synthesis and release of metalloproteinase-2 (MMP-2), which is deeply involved in plaque instabilization and vascular remodeling, and of the tissue inhibitor of metalloproteinase-2 (TIMP-2). Both in supernatants and in cell lysates of cultured hVSMC exposed to CRP (0-10 mg/L), we evaluated MMP-2 activity (gelatin zymography), MMP-2 and TIMP-2 protein synthesis (immunoblotting), MMP-2 and TIMP-2 mRNA expression (reverse transcription-polymerase chain reaction). CRP effects were also investigated after cell exposure to specific MEK inhibitor PD98059 (15-30 micromol/L) to evaluate the involvement of mitogen-activated protein kinase (MAPK). CRP upregulated MMP-2 mRNA expression. MMP-2 synthesis and activity were increased by 1-10 mg/L CRP starting from 8-hour incubation. The effect was prevented by exposure to PD98059. CRP did not modify TIMP-2 mRNA expression, protein synthesis, and secretion. CRP, at concentrations that predict cardiovascular events, upregulates MMP-2 mRNA expression and increases MMP-2 protein synthesis and release in hVSMC through mechanisms involving activation of MAPK pathway. These data indicate that CRP is not only a risk marker for vascular events, but it is also directly involved in the mechanisms leading to remodeling and instabilization of atherosclerotic plaque.

Uric acid-induced C-reactive protein expression: implication on cell proliferation and nitric oxide production of human vascular cells

Recent experimental and human studies have shown that hyperuricemia is associated with hypertension, systemic inflammation, and cardiovascular disease mediated by endothelial dysfunction and pathologic vascular remodeling. Elevated levels of C-reactive protein (CRP) have emerged as one of the most powerful independent predictors of cardiovascular disease. In addition to being a marker of inflammation, recent evidence suggests that CRP may participate directly in the development of atherosclerotic vascular disease. For investigating whether uric acid (UA)-induced inflammatory reaction and vascular remodeling is related to CRP, the UA-induced expression of CRP in human vascular smooth muscle cells (HVSMC) and human umbilical vein endothelial cells (HUVEC) was examined, as well as the pathogenetic role of CRP in vascular remodeling. It is interesting that HVSMC and HUVEC expressed CRP mRNA and protein constitutively, revealing that vascular cells are another source of CRP production. UA (6 to 12 mg/dl) upregulated CRP mRNA expression in HVSMC and HUVEC with a concomitant increase in CRP release into cell culture media. Inhibition of p38 or extracellular signal-regulated kinase 44/42 significantly suppressed UA-induced CRP expression, implicating these pathways in the response to UA. UA stimulated HVSMC proliferation whereas UA inhibited serum-induced proliferation of HUVEC assessed by 3H-thymidine uptake and cell counting, which was attenuated by co-incubation with probenecid, the organic anion transport inhibitor, suggesting that entry of UA into cells is responsible for CRP expression. UA also increased HVSMC migration and inhibited HUVEC migration. In HUVEC, UA reduced nitric oxide (NO) release. Treatment of vascular cells with anti-CRP antibody revealed a reversal of the effect of UA on cell proliferation and migration in HVSMC and NO release in HUVEC, which suggests that CRP expression may be responsible for UA-induced vascular remodeling. This is the first study to show that soluble UA, at physiologic concentrations, has profound effects on human vascular cells. The observation that UA alters the proliferation/migration and NO release of human vascular cells, mediated by the expression of CRP, calls for careful reconsideration of the role of UA in hypertension and vascular disease.

Relationship between C-reactive protein and arterial stiffness in an asymptomatic population

Plasma concentration of high sensitive C-reactive protein (hsCRP) is used as a marker for inflammatory states and is directly correlated with the risk for coronary heart disease. Evidence concerning the role of inflammation in atheroma formation has been derived from several models of atherosclerosis. Inflammation should exert its adverse vascular effects by structural changes in the artery wall and consequently alterations in arterial elasticity, which could be detected already in asymptomatic early vascular disease. We hypothesized that CRP is related to large artery elasticity, but not to small artery elasticity in early vascular disease. Therefore, we examined the association between arterial stiffness of large and small arteries and inflammation in an asymptomatic population referred for primary prevention cardiovascular screening. Studies were performed in 391 subjects (age 21-82 years; 254 men, 137 women) who underwent screening at the Cardiovascular Disease Prevention Center. Large artery (C1) and small artery (C2) elasticity indices were obtained by the CVProfiler 2000 (HDI, Eagan, MN, USA). After overnight fasting, venous samples were taken for measurement of hsCRP, lipids, glucose. There was a significant inverse correlation between hsCRP (0.29 +/- 0.40 mg/dl) and C1 (16.7 +/- 5.8 ml/mmHg), r = -0.133, P = 0.01; there was no significant correlation between hsCRP and C2 (6.6 +/- 3.2 ml/mmHg). C2, but not hsCRP, was inversely correlated with age, abnormal lipids and glucose, whereas C1, but not hsCRP, was inversely correlated with age and systolic blood pressure (SBP). In multiple regression analysis, the relationship between hsCRP and C1 was not affected by age, body mass index, SBP, serum glucose or lipids. In conclusion, these findings support the hypothesis that hsCRP, a marker for acute and low-grade inflammation, is associated with large artery but not with small artery elasticity in asymptomatic individuals undergoing primary prevention cardiovascular screening.

Inflammation, thrombosis and acute coronary syndromes

Inflammation plays a central role in the pathogenesis of acute coronary syndromes, the prevalence of which is increased in individuals with diabetes. Monocytes and macrophages, T cells and mast cells contribute to the initiation, development and rupture of atherosclerotic plaques by synthesising a variety of pro-inflammatory cytokines, including interleukin 1beta, interleukin 6 and tumour necrosis factor alpha. Cytokines upregulate endothelial cell adhesion molecules, recruit leukocytes and induce smooth muscle cell migration and proliferation. Cytokines act systemically to initiate the acute phase response, up-regulating proteins involved in inflammation and haemostasis and resulting in a pro-inflammatory and pro-thrombotic state. Expression of tissue factor by inflammatory cells potently induces thrombus formation upon plaque rupture, leading to acute coronary syndromes. Inflammatory biomarkers, including C-reactive protein, complement proteins, interleukin 6 and white blood cell count, predict development of acute coronary syndromes. C-reactive protein has been widely studied and consistently predicts future acute coronary syndrome events.

A proatherogenic role for C-reactive protein in vivo

PURPOSE OF REVIEW

We have selectively reviewed some of the latest papers on the mechanistic role of C-reactive protein in atherosclerotic cardiovascular disease.

RECENT DEVELOPMENTS

C-reactive protein is known to activate the classic pathway of the complement system. One paper examined the role of C-reactive protein in complement activation by enzymatically remodeled LDL proteins. Enzymatically remodeled LDL was found to induce complement activation with or without C-reactive protein, but in the presence of C-reactive protein the activation of complement halted before its terminal sequence. Complement activation by C-reactive protein in atherogenesis remains controversial. Different laboratories have reported the multi-organ origin of C-reactive protein. The atherosclerotic lesion itself is another place where C-reactive protein could be produced. Numerous studies have continued to dissect the potential diverse proatherogenic actions of C-reactive protein on cultured vascular cells. Caution must be exercised in inadequately controlled studies that have unwittingly used commercial C-reactive protein preparations contaminated by other bioactive components. In contrast to in-vitro experiments, in-vivo studies that support a proatherogenic role of C-reactive protein are less likely to be subject to misinterpretation.

SUMMARY

Evidence suggests that C-reactive protein is a proatherogenic molecule that plays an active role. The amount of C-reactive protein in lesions is determined by its plasma levels and its local production. The biological effect of C-reactive protein on atherosclerosis development seems to encompass a complex network of interactions with other players in immunity and inflammation, such as the complement system, as well as a direct effect of C-reactive protein on the cells involved in lesion growth and development.

Vitamin E, oxidative stress, and inflammation

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the Western world. Its incidence has also been increasing lately in developing countries. Several lines of evidence support a role for oxidative stress and inflammation in atherogenesis. Oxidation of lipoproteins is a hallmark in atherosclerosis. Oxidized low-density lipoprotein induces inflammation as it induces adhesion and influx of monocytes and influences cytokine release by monocytes. A number of proinflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) modulate monocyte adhesion to endothelium. C-reactive protein (CRP), a prototypic marker of inflammation, is a risk marker for CVD and it could contribute to atherosclerosis. Hence, dietary micronutrients having anti-inflammatory and antioxidant properties may have a potential beneficial effect with regard to cardiovascular disease. Vitamin E is a potent antioxidant with anti-inflammatory properties. Several lines of evidence suggest that among different forms of vitamin E, alpha-tocopherol (AT) has potential beneficial effects with regard to cardiovascular disease. AT supplementation in human subjects and animal models has been shown to decrease lipid peroxidation, superoxide (O2-) production by impairing the assembly of nicotinamide adenine dinucleotide phosphate (reduced form) oxidase as well as by decreasing the expression of scavenger receptors (SR-A and CD36), particularly important in the formation of foam cells. AT therapy, especially at high doses, has been shown to decrease the release of proinflammatory cytokines, the chemokine IL-8 and plasminogen activator inhibitor-1 (PAI-1) levels as well as decrease adhesion of monocytes to endothelium. In addition, AT has been shown to decrease CRP levels, in patients with CVD and in those with risk factors for CVD. The mechanisms that account for nonantioxidant effects of AT include the inhibition of protein kinase C, 5-lipoxygenase, tyrosine-kinase as well as cyclooxygenase-2. Based on its antioxidant and anti-inflammatory activities, AT (at the appropriate dose and form) could have beneficial effects on cardiovascular disease in a high-risk population.

C-reactive protein decreases expression of VEGF receptors and neuropilins and inhibits VEGF165-induced cell proliferation in human endothelial cells

C-reactive protein (CRP) is associated with cardiovascular disease. However, its biological functions for the vascular system are largely unknown. The objective of this study was to determine whether CRP could affect endothelial cell proliferation and expression of VEGF receptors (VEGFRs) and/or neuropilins. Human coronary artery endothelial cells (HCAECs) treated with CRP showed a significant reduction of mRNA levels of VEGFR-2, VEGFR-3, NRP-1, and NRP-2 by 34%, 63%, 41%, and 43%, respectively, as compared to untreated control cells (p < 0.05) by real-time PCR analysis. In addition, VEGF165-induced cell proliferation was determined by [3H]thymidine incorporation and MTS assay as well as capillary-like tube formation on Matrigel. HCAECs pretreated with CRP significantly decreased VEGF165-induced [3H]thymidine incorporation by 73%, MTS absorbance by 44%, and capillary-like tube formation by 54% as compared to CRP-untreated cells (p < 0.05). These data demonstrate that CRP significantly attenuates VEGF165-induced HCAEC proliferation and capillary-like tube formation through downregulation of expression of VEGFRs and NRPs. This study suggests a new molecular mechanism underlying the adverse effect of CRP on the vascular system.

Tissue resident C reactive protein in degenerative aortic valves: correlation with serum C reactive protein concentrations and modification by statins

OBJECTIVE

To assess aortic valve probes for valvar C reactive protein (CRP) presence, the relation between valvar and serum CRP, and a possible modification of CRP by statin medication.

SETTING

Tertiary referral centre.

PATIENTS AND DESIGN

End stage, degenerative valve tissue was taken from 81 patients, 57 with non-rheumatic aortic valve stenosis (AS) and 24 with degenerative aortic valve bioprosthesis (BP). Five non-stenosed valves served as controls. Tissue from four non-implanted bioprostheses was also examined. The presence and location of CRP was analysed by use of immunostaining and morphometry. Serum CRP concentrations were measured preoperatively.

RESULTS

The majority of AS and BP valves exhibited CRP labelled cells, predominantly localised to the valvar fibrosa. The expression of CRP was much higher in BP than in AS (by a factor of 3.7, p = 0.03). Notably, non-stenosed aortic valves and non-implanted bioprostheses did not have CRP signalling. Serum CRP was also increased with BP (by a factor of 2.5, p = 0.02) and was significantly correlated with valvar CRP expression (r = 0.54, p < 0.001). The main finding in patients with (n = 26) and without statin treatment (n = 55) was that both valvar CRP expression (p = 0.02) and serum CRP concentrations (p = 0.04) were lower in the statin treated group.

CONCLUSIONS

CRP was found in a large series of degenerative aortic valves, more often in bioprostheses than in native cusps. Serum CRP concentrations may reflect inflammatory processes within the aortic valve. The association of statin treatment with decreases in both valvar and serum CRP concentrations may explain known pleiotropic effects of statins in patients with aortic stenosis.

C-reactive protein decreases tissue plasminogen activator activity in human aortic endothelial cells: evidence that C-reactive protein is a procoagulant

OBJECTIVE

C-reactive protein (CRP) can promote atherothrombosis by decreasing endothelial nitric oxide synthase and prostacyclin, and by stimulating both plasminogen activator inhibitor-1 in endothelial cells and tissue factor in mononuclear cells. Plasminogen activator-1, a marker of fibrinolysis, is the primary inhibitor of tissue plasminogen activator (tPA). Thus, we tested the effect of CRP on tPA in human aortic endothelial cells.

METHODS AND RESULTS

Incubation of human aortic endothelial cells with CRP (> or =12.5 microg/mL) significantly decreased tPA antigen and activity. Adenyl cyclase inhibitors, an endothelin receptor antagonist, superoxide dismutase, and a nitric oxide donor failed to reverse the effect of CRP on tPA. CRP increased interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. Neutralization of both IL-1beta and TNFalpha reversed the inhibition of tPA by CRP. Furthermore, in volunteers that have high CRP levels, euglobulin clot lysis time was significantly increased compared with those that have low CRP levels, providing further evidence that high CRP levels are associated with a procoagulant state.

CONCLUSIONS

CRP inhibits tPA activity via generation of proinflammatory cytokines (IL-1beta and TNFalpha). This study provides additional novel data that CRP is a procoagulant and has implications for atherothrombosis.

Native C-Reactive Protein Increases Whereas Modified C-Reactive Protein Reduces Atherosclerosis in Apolipoprotein E–Knockout Mice

Background— C-reactive protein (CRP) may have proatherogenic but also vasoprotective properties. We tested the hypothesis that the configuration of CRP (pentameric, or native [nCRP], versus monomeric, or modified [mCRP]) determines these different characteristics in an in vivo model.

Methods and Results— We investigated the effects of human nCRP and mCRP on the development of atherosclerosis in apolipoprotein E–knockout (ApoE −/− ) mice. Treatment with nCRP for 8 weeks (2.5 mg/kg SC weekly) resulted in a 4-fold-higher mean aortic plaque area in 14-week-old female ApoE −/− mice compared with the saline controls. In contrast, mean plaque size was decreased by ≈50% in mCRP-treated ApoE −/− mice (2.5 mg/kg SC weekly). Using immunohistochemistry, we report the natural presence of the mCRP antigen in saline controls. mCRP antigen was expressed in smooth muscle cells and extracellularly in the vicinity of the plaques to a similar level in both CRP-treated groups and saline controls. mCRP and ApoB colocalized with macrophages and were equally upregulated in all aortic plaques. Vascular cell adhesion molecule expression was increased, and CD154 and intercellular adhesion molecule showed a trend for higher expression in nCRP-treated compared with mCRP-treated mice. CD154 expression in the vessel wall and plaque size correlated significantly. mCRP-treated ApoE −/− exhibited higher serum levels of the antiinflammatory interleukin-10 compared with the other 2 groups.

Conclusions— Here, we show that mCRP and nCRP have opposite effects on atherosclerosis in ApoE −/− mice. These data may explain in part the conflicting activities previously reported for CRP in models of atherogenesis.

Expression of C-reactive protein in human lung epithelial cells and upregulation by cytokines and carbon particles

C-reactive protein (CRP) is the prototypic human acute-phase protein and is found at increased levels in the blood during episodes of inflammation. CRP was generally thought to be produced only by hepatocytes; however, several studies have shown extrahepatic synthesis of CRP. A previous study showed that PM10 and ultrafine carbon black (ufCB) were able to induce CRP expression in A549 cells. This study aims to examine the factors that lead to the production of CRP in A549 cells. A549 human lung epithelial cells were treated with cytokines (interleukin 6, tumor necrosis factor alpha, interferon gamma, or interleukin 1beta) or carbon particles (CB and ufCB) for 18 h. It was found that CRP could be expressed within the cells and that CRP was secreted from the cells particularly with tumor necrosis factor alpha, CB and ufCB treatments. It was also found that this expression of CRP with CB and ufCB treatments was dependent on nuclear factor kappa B (NFkappaB). The expression of CRP in A549 cells may indicate an important role for CRP expression and secretion from lung epithelial cells in response to inflammatory stimuli.

C-reactive protein in peripheral arterial disease: Relation to severity of the disease and to future cardiovascular events

BACKGROUND

Serum C-reactive protein (CRP) has proven to be an independent marker of the extent of atherosclerosis in patients with coronary, cerebrovascular, and peripheral arterial disease. In this prospective observational study, we wanted to assess the relationship between serum CRP and extent of disease transversely and longitudinally in time, as well as future cardiovascular complications in patients with peripheral arterial disease (PAD). Hypothesizing that CRP not only is a marker of but also actively participates in atherogenesis, we explored the possibility of CRP production by femoral atherosclerotic plaques.

METHODS

Serum CRP was measured as highly sensitive (hsCRP) in 387 patients with PAD attending the vascular clinic of a university and 2 affiliated teaching hospitals. Serum hsCRP was related to the ankle-brachial pressure index (ABPI) as an indication of severity of disease at inclusion and at 12 months' follow-up and to future events (death and coronary, cerebral, and peripheral arterial events). In femoral plaques, the production of CRP was analyzed with reverse transcription-polymerase chain reaction, and CRP plaque localization was assessed with immunostaining on serial tissue sections with antibodies toward CRP, smooth muscle cells, T cells, and macrophages.

RESULTS

The hsCRP (average +/- SD) was 3.26 +/- 2.41 mg/L. Serum hsCRP showed a correlation with baseline and 12-month follow-up ABPI (Spearman rank correlation; P < .05 for both correlations). When the patients were divided into three equally sized groups according to baseline serum hsCRP, the ABPI at baseline and at 12 months decreased significantly from the low- to the high-hsCRP group (baseline ABPI: 0.70, 0.65, and 0.57, P < .01; 12-month follow-up ABPI: 0.78, 0.70, and 0.65, P < .01). These associations persisted after correction for conventional risk factors. Furthermore, serum hsCRP was related to the combined end point "death and/or any cardiovascular event" (log-rank test; P = .04) during a median 24-month follow-up period. Reverse transcription-polymerase chain reaction analysis showed CRP production in 4 of 14 femoral plaques. CRP was detected in all femoral plaques, but not in healthy brachial arteries. Immunoreactivity for CRP was observed in smooth muscle cells, macrophages, and T cells.

CONCLUSIONS

Serum hsCRP was related to the severity of PAD, showing a relation to future hemodynamic function and cardiovascular events in PAD patients. In addition to coronary plaques, aneurysmal aortas, and failed venous coronary bypasses, femoral plaques also produce CRP, thus illustrating that the production of CRP may represent a universal response to vascular injury and suggesting that vascular CRP may contribute to plaque development.

Local Release of C-Reactive Protein From Vulnerable Plaque or Coronary Arterial Wall Injured by Stenting

OBJECTIVES

The purpose of this study was to assess local release of C-reactive protein (CRP) from atherosclerotic plaques or the vessel wall injured by stenting.

BACKGROUND

Recent research has focused on the local production of CRP, especially in inflammatory atherosclerotic plaques.

METHODS

The study consisted of two separate protocols. In protocol 1, we measured serum high-sensitivity-CRP (hs-CRP) levels in coronary arterial blood sampled just distal and proximal to the culprit lesions in 36 patients with stable angina and 13 patients with unstable angina. In protocol 2, we measured serial serum hs-CRP levels and activated Mac-1 on the surface of neutrophils in both coronary sinus and peripheral blood in 20 patients undergoing coronary stenting.

RESULTS

In protocol 1, CRP was higher in distal blood than proximal blood in both stable (p < 0.05) and unstable angina (p < 0.01). The translesional CRP gradient (distal CRP minus proximal CRP, p < 0.05) as well as the proximal CRP (p < 0.05) and distal CRP (p < 0.05) was higher in unstable angina than in stable angina. In protocol 2, the transcardiac CRP gradient (coronary sinus minus peripheral blood) and activated Mac-1 increased gradually after stenting, reaching a maximum at 48 h (p < 0.001 vs. baseline for both). There was a positive correlation between the transcardiac CRP gradient and activated Mac-1 at 48 h (r = 0.45, p < 0.01).

CONCLUSIONS

C-reactive protein is an excellent marker for plaque instability or poststent inflammatory status, and its source might be the inflammation site of the plaque or the coronary arterial wall injured by stenting.

Anti-inflammatory strategies in hypertension: focus on COX-1 and COX-2

An increasing body of evidence suggests that elevated levels of blood pressure may induce a proinflammatory response. Indeed, both C-reactive protein and blood pressure are independent determinants of cardiovascular risk, and, in combination, each parameter has additional predictive value. Hence, strategies targeted to lower blood pressure and reduce vascular inflammation may potentially provide clinical benefit. In this review, we discuss the role of chronic low-grade inflammation in the context of cardiovascular disease with a focus on roles of cyclooxygenase-1 and -2 in potential anti-inflammatory treatment strategies.

Influenza and pneumococcal vaccination as a model to assess C-reactive protein response to mild inflammation

This study was set up to examine whether an influenza vaccine or an influenza vaccine in combination with pneumococcal vaccine can be used as a model to study responses to mild stimulation of the inflammatory system. In this study, 19 subjects received the influenza vaccine, 20 subjects the combination of influenza and pneumococcal vaccine. CRP and prothrombin fragment 1 and 2 (F1+2) were measured at baseline, and two times after vaccination. Influenza vaccination increased CRP by 0.20 mg/L, and influenza in combination with pneumococcal vaccine increased CRP by 0.60 mg/L. F1+2 increased 0.15 nmol/L after the combined vaccination; an increase in response to the influenza vaccination was not statistically significant. Our findings show that the influenza vaccine alone as well as the combination of the influenza and pneumococcal vaccine increases CRP-levels with a peak 2 days after vaccination.

Anti-inflammatory effects of alpha-tocopherol

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the western world. Its incidence has been increasing lately in the developing countries. Much evidence suggests a major role for inflammation in all phases of atherosclerosis. Cell adhesion molecules, cytokines, chemokines, and monocytes-macrophages as well as T lymphocytes play a pivotal role in atherogenesis. C-reactive protein (CRP), a downstream marker of inflammation, in addition to being a risk marker for CVD, could contribute to atherosclerosis. Dietary micronutrients with anti-inflammatory properties, specially alpha-tocopherol, may play an important role with regard to the prevention and treatment of CVD. alpha-Tocopherol has been shown to have anti-inflammatory effects both in vitro and in vivo. alpha-Tocopherol therapy, especially at high doses, has been shown to decrease release of pro-inflammatory cytokines (such as interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha) and the chemokine interleukin-8, and to decrease adhesion of monocytes to endothelium. In addition, alpha-tocopherol has been shown to decrease CRP levels in patients with CVD and having related risk factors for CVD (such as diabetes and smoking). Furthermore, pro-inflammatory cytokines and plasminogen activator inhibitor-1 (PAI-1) levels have also been shown to be decreased with alpha-tocopherol supplementation in vivo. In this review, our focus will be on anti-inflammatory effects of alpha-tocopherol reported in in vivo studies.

Dramatic changes in the serum levels of anti-cholesterol antibodies after eversion endarterectomy in patients with severe carotid atherosclerosis

Our goal was to study changes in anti-cholesterol antibodies (ACHA) levels in patients with severe carotid stenosis after eversion endarterectomy. Seventy consecutive patients who underwent eversion endarterectomy at the Department of Cardiovascular Surgery, Semmelweis University, Budapest, were included in the study. Serum samples from 66 healthy volunteers served as controls. Patients had medical check up at 5.7 (4.6-8.0) weeks (median (interquartile range)), 6.8 (6.2-7.9) months as well as 13.8 (12.3-19.0) months after endarterectomy. In all patients the carotid arteries were investigated by color duplex ultrasound. ACHA concentrations were determined in the serum samples taken before operation as well as at the first and last follow-up visits by using an ELISA method. ACHA concentrations (median (interquartile range) were found to be significantly (p<0.0001) lower in the sera of the patients with carotid atherosclerosis (13.5 (8.4-21.3)AU/ml) than in the healthy subjects (26.1 (20.9-33.2)AU/ml) (Mann-Whitney test). Strong negative correlation was found between the preoperative ACHA and LDL-cholesterol levels (r=-0.413, p=0.0004). Serum ACHA concentrations significantly (p<0.0001) increased from the values measured before operation (13.5 (8.4-21.3)AU/ml) to 27.1 (19.9-34.7)AU/ml measured at the end of the 14 months long follow-up. Increase occurred only in patients with low or medium baseline ACHA concentration. Our present findings indicate that after surgical removal of atherosclerotic plaques from the carotid arteries the reduced baseline levels of ACHA reach normal values in 1 year. Different not mutually exclusive mechanisms (binding of ACHA to lipid/lipoproteins particles, to advanced plaques or reversibly injured endothelial cells in CNS) can be responsible for this novel finding.