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-γ 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)-κB 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.
mechanistic insights; macrophages; sterile pouch
The formation of low-density lipoprotein (LDL) cholesterol-loaded macrophage foam cells contributes to the development of atherosclerosis. C-reactive protein (CRP) binds to atherogenic forms of LDL, but the role of CRP in foam cell formation is unclear. In this study, we first explored the binding site on CRP for enzymatically modified LDL (E-LDL), a model of atherogenic LDL to which CRP binds. As reported previously, phosphocholine (PCh) inhibited CRP-E-LDL interaction, indicating the involvement of the PCh-binding site of CRP in binding to E-LDL. However, the amino acids Phe66 and Glu81 in CRP that participate in CRP-PCh interaction were not required for CRP-E-LDL interaction. Surprisingly, blocking of the PCh-binding site with phosphoethanolamine (PEt) dramatically increased the binding of CRP to E-LDL. The PEt-mediated enhancement in the binding of CRP to E-LDL was selective for E-LDL because PEt inhibited the binding of CRP to another PCh-binding site-ligand pneumococcal C-polysaccharide. Next, we investigated foam cell formation by CRP-bound E-LDL. We found that, unlike free E-LDL, CRP-bound E-LDL was inactive because it did not transform macrophages into foam cells. The function of CRP in eliminating the activity of E-LDL to form foam cells was not impaired by the presence of PEt. Combined data lead us to two conclusions. First, PEt is a useful compound because it potentiates the binding of CRP to E-LDL and, therefore, increases the efficiency of CRP to prevent transformation of macrophages into E-LDL-loaded foam cells. Second, the function of CRP to prevent formation of foam cells may influence the process of atherogenesis.
Within the general population, levels of C-reactive protein (CRP) are positively associated with atherosclerotic cardiovascular disease (CVD). Whether CRP is causally implicated in atherogenesis or is the results of atherosclerosis is disputed. A role of CRP to protect endothelium-derived nitric oxide (EDNO) has been suggested. We examined the association of CRP with EDNO-dependent vasomotor function and subclinical measures of atherosclerosis and arteriosclerosis in patients with raised CRP resulting from rheumatoid arthritis (RA).
Patients with RA (n = 59) and healthy control subjects (n = 123), underwent measures of high sensitivity CRP, flow-mediated dilation (FMD, dependent on EDNO), intima-media thickness (IMT, a measure of subclinical atherosclerosis) and aortic pulse wave velocity (PWV, a measure of arteriosclerosis). IMT and PWV were elevated in patients with RA compared to controls but FMD was similar in the two groups. In patients with RA, IMT and PWV were not correlated with CRP but FMD was positively independently correlated with CRP (P<0.01).
These findings argue against a causal role of CRP in atherogenesis and are consistent with a protective effect of CRP on EDNO bioavailability.
The 5 subunits of native pentameric C-reactive protein (CRP) are dissociated to generate monomeric form of CRP (mCRP) in some in vitro conditions, both physiological and non-physiological, and also in vivo. Many bioactivities of mCRP generated by urea-treatment of CRP and of mCRP generated by mutating the primary structure of CRP have been reported. The bioactivities of mCRP generated by spontaneous dissociation of CRP are largely unexplored.
We purified mCRP generated by spontaneous dissociation of CRP and investigated the binding of mCRP to enzymatically-modified low-density lipoprotein (E-LDL).
mCRP was approximately 60 times more potent than CRP in binding to E-LDL. In the presence of the small-molecule compound phosphoethanolamine (PEt), at 37°C, the binding of mCRP to E-LDL was enhanced <2-fold, while the binding of CRP to E-LDL was enhanced >10-fold. In contrast, PEt inhibited the binding of both CRP and mCRP to pneumococcal C-polysaccharide, another phosphocholine-containing ligand to which CRP and mCRP were found to bind. We have not investigated yet whether PEt alters the structure of CRP at 37°C.
Combined data suggest that the targeting of CRP with the aim to monomerize CRP in vivo may be an effective approach to capture modified forms of LDL.
C-reactive protein; Monomeric C-reactive protein; Phosphoethanolamine; Pneumococcal C-polysaccharide; Enzymatically-modified low-density lipoprotein
There is a relationship among hypercholesterolemia, oxidative stress and inflammation in the atherogenesis. Thus, the objective of the present study was to assess paraoxonase (PON1), superoxide dismutase (SOD) and thioredoxin reductase (TrxR-1) activities and their relationship with lipids, oxidative stress and inflammation in subjects with different low density lipoprotein-cholesterol (LDL) levels.
Serum lipids, highly sensitive C-reactive protein (hs-CRP), lipid and protein oxidation, oxidized LDL (LDLox) and LDLox autoantibodies (LDLoxAB) levels and enzymes activities were measured in a total of 116 subjects that were divided into the following groups according to their LDL levels: low-LDL group (LDL < 100 mg/dL, n = 23), intermediate-LDL group (LDL 100–160 mg/dL, n = 50) and high-LDL group (LDL > 160 mg/dL, n = 43).
The LDLox and hs-CRP levels increased in the high-LDL group (2.7- and 3.7- fold, respectively), whereas the intermediate and high-LDL groups had higher LDLoxAB (2.2- and 3.1-fold) when compared to low-LDL group (p < 0.05). Similarly, SOD activity, the atherogenic index (AI) and protein oxidation were also higher in the intermediate (1.3-, 1.3- and 1.2-fold) and high-LDL (1.6-, 2.3- and 1.6-fold) groups when compared to the low-LDL group (p < 0.05). Lipid oxidation and SOD/TrxR-1 ratio increased only in the high-LDL group (1.3- and 1.6-fold) when compared to the low-LDL group (p < 0.05). The SOD/TrxR-1 ratio was positively correlated to TBARS (r = 0.23, p < 0.05), LDLox (r = 0.18, p < 0.05), LDLoxAB (r = 0.21, p < 0.05), LDL (r = 0.19, p < 0.05) and AI (r = 0.22, p < 0.05). PON1 and TrxR-1 activities were similar among groups.
Some oxidative events initiate when LDL levels are clinically acceptable. Moreover, hypercholesterolemic patients have an imbalance in SOD and TrxR-1 activities that is positively associated to LDL oxidation.
Atherogenic index; Hypercholesterolemia; Oxidized low density lipoprotein; Superoxide dismutase; Thioredoxin reductase
Much evidence supports a pivotal role for inflammation in atherosclerosis. C-reactive protein (CRP), the prototypic marker of inflammation in humans, is a cardiovascular risk marker and may also promote atherogenesis. CRP levels are increased in metabolic syndrome and hypertension and confer increased risk of cardiovascular events in patients in these subgroups. Statins have been shown to lower low-density lipoproteins and CRP independently, and reduce cardiovascular events in subjects with and without metabolic syndrome and hypertension. In this review, we focus on the results from the primary prevention statin trial, Justification for the Use of statins in Primary prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER), which showed reductions in LDL, CRP, and cardiovascular events. Post-JUPITER, the new guidelines will now need to consider recommending high-sensitivity CRP testing to intermediate-risk metabolic syndrome patients and those with hypertension and intermediate risk so that we can better identify candidates at greater risk and reduce cardiovascular burden in these subjects with statin therapy.
CRP; Endothelial dysfunction; Atherosclerosis; Inflammation; Monocytes; Statins; Metabolic syndrome; Hypertension
C-reactive protein (CRP) is an acute phase plasma protein. An important binding specificity of CRP is for the modified forms of low-density lipoprotein (LDL) in which the phosphocholine-binding sites of CRP participate. CRP, however, does not bind to native LDL.
We investigated the interaction of CRP with native LDL using sucrose density gradient ultracentrifugation.
We found that the blocking of the phosphocholine-binding sites of CRP with phosphoethanolamine (PEt) converted CRP into a potent molecule for binding to native LDL. In the presence of PEt, CRP acquired the ability to bind to fluid-phase purified native LDL. Because purified native LDL may undergo subtle modifications, we also used whole human serum as the source of native LDL. In the presence of PEt, CRP bound to native LDL in serum also. The effect of PEt on CRP was selective for LDL because PEt-complexed CRP did not bind to high-density lipoprotein in the serum.
The pharmacologic intervention of endogenous CRP by PEt-based compounds, or the use of exogenously prepared CRP-PEt complexes, may turn out to be an effective approach to capture native LDL cholesterol in vivo to prevent the development of atherosclerosis.
C-reactive protein; low-density lipoprotein; cholesterol; phosphocholine; phosphoethanolamine
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 Fcγ 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 Apob100/100Ldlr -/- 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.
Atherosclerosis; cholesterol; C-reactive protein; foam cell; low-density lipoprotein; phosphoethanolamine; myocardial infarction
C-reactive protein (CRP) and lysophosphatidylcholine (LPC) are phosphorylcholine-(PC)-containing oxidized phospholipids (oxPLs) found in oxidized LDL (oxLDL), which trigger pro-atherogenic activities of macrophages during the process of atherosclerosis. It has been previously reported that CRP binds to the PC head group of oxLDL in a calcium-dependent manner. The aim of this study was to investigate the importance of binding between CRP and LPC to the pro-atherogenic activities of macrophages.
Objectives and findings
A chemiluminescent immunoassay and HPLC showed that human recombinant CRP formed a stable complex with LPC in the presence of calcium. The Kd value of the binding of the CRP-LPC complex to the receptors FcγRIA or FcγRIIA was 3–5 fold lower than that of CRP alone. The CRP-LPC complex triggered less potent generation of reactive oxygen species and less activation of the transcription factors AP-1 and NF-kB by human monocyte-derived macrophages in comparison to CRP or LPC alone. However, CRP did not affect activities driven by components of oxLDL lacking PC, such as upregulation of PPRE, ABCA1, CD36 and PPARγ and the enhancement of cholesterol efflux by human macrophages. The presence of CRP inhibited the association of Dil-labelled oxLDL to human macrophages.
The formation of complexes between CRP and PC-containing oxPLs, such as LPC, suppresses the pro-atherogenic effects of CRP and LPC on macrophages. This effect may in part retard the progression of atherosclerosis.
C-reactive protein; Lysophosphatidylcholine; Macrophages; Foam cells
To describe the proportion of “JUPITER-eligible” individuals and clinical outcomes of individuals based on high-sensitivity C-reactive protein (hs-CRP) and low-density lipoprotein cholesterol (LDL-C) strata in the Atherosclerosis Risk in Communities (ARIC) study.
Questions remain after the JUPITER study including whether the observed cardiovascular disease (CVD) event rates would persist with time and how these event rates would compare with other populations (lower hs-CRP and/or higher LDL-C levels).
After stratification into 4 groups based on LDL-C and hs-CRP levels, with cutoffs at 130 mg/dL and 2.0 mg/L, respectively incident CVD events were examined (mean follow-up 6.9 years) and compared.
Of 8,907 age-eligible participants, 18.2% (n=1,621) were “JUPITER-eligible” (hs-CRP ≥2.0 mg/L, LDL-C <130 mg/dL) and had an absolute CVD risk of ~10.9% over a mean follow-up of 6.9 years (1.57% per year). If JUPITER hazard ratios were applied to this group, the number needed to treat to prevent one CVD event would be estimated at 38 over 5 years and 26 over 6.9 years.
ARIC participants with elevated hs-CRP and low LDL-C had a CVD event rate of 1.57% per year over 6.9 years similar to the CVD event rate noted in the JUPITER study placebo group (1.36% per year over 1.9 years). The association of hs-CRP ≥2.0 mg/L with increased CVD risk and mortality regardless of LDL-C provides us a simple method of using age and hs-CRP for identifying higher risk individuals.
hs-CRP; LDL-C; ARIC; lipids; cardiovascular disease
C-reactive protein (CRP) is secreted by hepatocytes as a pentameric molecule made up of identical monomers, circulates in the plasma as pentamers, and localizes in atherosclerotic lesions. In some cases, localized CRP was detected by using monoclonal antibodies that did not react with native pentameric CRP but were specific for isolated monomeric CRP. It has been reported that, once CRP is bound to certain ligands, the pentameric structure of CRP is altered so that it can dissociate into monomers. Accordingly, the monomeric CRP found in atherosclerotic lesions may be a stationary, ligand-bound, by-product of a ligand-binding function of CRP. CRP binds to modified forms of low-density lipoprotein (LDL). The binding of CRP to oxidized LDL requires acidic pH conditions; the binding at physiological pH is controversial. The binding of CRP to enzymatically-modified LDL occurs at physiological pH; however, the binding is enhanced at acidic pH. Using enzymatically-modified LDL, CRP has been shown to prevent the formation of enzymatically-modified LDL-loaded macrophage foam cells. CRP is neither pro-atherogenic nor atheroprotective in ApoE−/− and ApoB100/100Ldlr −/− murine models of atherosclerosis, except in one study where CRP was found to be slightly atheroprotective in ApoB100/100Ldlr −/− mice. The reasons for the ineffectiveness of human CRP in murine models of atherosclerosis are not defined. It is possible that an inflammatory environment, such as those characterized by acidic pH, is needed for efficient interaction between CRP and atherogenic LDL during the development of atherosclerosis and to observe the possible atheroprotective function of CRP in animal models.
Atherosclerosis; C-reactive protein; Enzymatically-modified low-density lipoprotein; Foam cells; Oxidized low-density lipoprotein
C-reactive protein (CRP), the prototypic marker of inflammation, is a cardiovascular risk marker and recent in vitro studies suggest that it may promote atherogenesis. CRP promotes oxidative stress in vitro and induces tissue factor (TF) release. However, there is a paucity of data examining the effects of CRP on oxidative stress and tissue factor procoagulant activity (PCA) in vivo. Thus, we tested the effects of CRP administration on superoxide anion release and tissue factor activity and examined mechanistic pathways using a rat sterile air pouch model. Intraperitoneal administration of CRP (20 mg/kg body weight) compared to human serum albumin (HuSA) increased superoxide anion release and tissue factor activity from peritoneal macrophages in vivo (p < 0.01). This was confirmed using intrapouch administration of CRP (25 μg/mL) compared to HuSA. Pretreatment with reactive oxygen species (ROS) scavengers or protein kinase C (PKC) inhibitor significantly abrogated CRP-induced superoxide anion release and tissue factor activity. Pretreatment with extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) inhibitors, but not p38 mitogen-activated protein kinase (p38MAPK) significantly decreased CRP-induced superoxide anion release from macrophages in vivo. CRP-induced tissue factor activity in vivo was abrogated by pretreatment with inhibitors to p38MAPK, JNK and NFκb (nuclear factor-κb), but not ERK. Antibodies to Fc gamma receptors, CD32 and CD64 resulted in significant reduction in CRP-induced superoxide and tissue factor activity in vivo. Thus, CRP appears to induce oxidative stress in vivo by stimulating NADPH oxidase via PKC, ERK and JNK phosphorylation, and induces tissue factor PCA in vivo via upregulation of PKC, p38MAPK, JNK, ROS and NFκb. CRP-induced ROS appears to precede tissue factor release. These effects are abrogated by blocking Fc gamma receptors, CD32 and CD64. This in vivo demonstration provides further evidence for a role for CRP in atherothrombosis.
Macrophages; Oxidative stress; Rat; Mechanistic insights; Tissue factor; Procoagulant
Inflammation is pivotal in all phases of atherosclerosis. Among the numerous inflammatory biomarkers, the largest amount of published data supports a role for C-reactive protein (CRP) as a robust and independent risk marker in the prediction of primary and secondary adverse cardiovascular events. In addition to being a risk marker, there is much evidence indicating that CRP may indeed participate in atherogenesis.
In this review, we focus on the role of CRP in promoting atherothrombosis by discussing its effects on endothelial cells, endothelial progenitor cells, monocyte-macrophages, and smooth muscle cells.
CRP is clearly a risk marker for cardiovascular disease and is recommended for use in primary prevention. In addition, CRP appears also to contribute to atherogenesis. However, much further research is needed, especially in appropriate animal models, to confirm the possible role of CRP in promoting atherothrombosis.
Inflammation plays an instrumental role in all stages of atherosclerosis. C-reactive protein (CRP), a systemic inflammatory marker, has been gaining recognition as an independent risk factor for cardiovascular disease (CVD). Both baseline CRP levels and drug-induced CRP changes are highly variable and potentially subject to the genetic regulation.
This review summarizes the current studies which have examined the effect of genetic and environmental factors on baseline plasma CRP levels with main focus on CRP genetic polymorphisms and various dietary components. We also address the association of CRP genetic variations with risk of CVD, which may provide support or refute to the causality of CRP in atherosclerotic process. Moreover, we discuss the impact of CRP genetic polymorphisms on CRP change in response to 3-week fenofibrate treatment in the genetic intervention of the GOLDN study.
Both genetic variants on CRP locus and other loci, and dietary and lifestyle factors are responsible for the inter-individual variability of plasma CRP levels. CRP genetic variants further differentiate plasma CRP response after 3-week fenefibrate treatment among subjects with metabolic syndrome. Future studies focusing on the influence and interaction of genetic variation on the CRP response to dietary and other behavior modification as well as drug treatment could have great implication for the development of more personalized preventive and therapeutic approaches to reduce CVD.
Ceruloplasmin is a plasma protein that carries most of the copper found in the blood. Although its elevation after inflammation and trauma has led to its classification as an acute phase protein, its physiological role is uncertain. A frequently reported activity of ceruloplasmin is its ability to suppress oxidation of lipids. In light of the intense recent interest in the oxidation of plasma LDL, we investigated the effects of ceruloplasmin on the oxidation of this lipoprotein. In contrast to our expectations, highly purified, undegraded human ceruloplasmin enhanced rather than suppressed copper ion-mediated oxidation of LDL. Ceruloplasmin increased the oxidative modification of LDL as measured by thiobarbituric acid-reacting substances by at least 25-fold in 20 h, and increased electrophoretic mobility, conjugated dienes, and total lipid peroxides. In contrast, ceruloplasmin that was degraded to a complex containing 115- and 19-kD fragments inhibited cupric ion oxidation of LDL, as did commercial preparations, which were also degraded. However, the antioxidant capability of degraded ceruloplasmin in this system was similar to that of other proteins, including albumin. The copper in ceruloplasmin responsible for oxidant activity was not removed by ultrafiltration, indicating a tight association. Treatment of ceruloplasmin with Chelex-100 removed one of seven copper atoms per molecule and completely blocked oxidant activity. Restoration of the copper to ceruloplasmin also restored oxidant activity. These data indicate that ceruloplasmin, depending on the integrity of its structure and its bound copper, can exert a potent oxidant rather than antioxidant action on LDL. Our results invite speculation that ceruloplasmin may be in part responsible for oxidation of LDL in blood or in the arterial wall and may thus have a physiological role that is quite distinct from what is commonly believed.
C-reactive protein (CRP), the prototypic marker of inflammation, is present in atherosclerotic plaques and appears to promote atherogenesis. Also, CRP has been localized to monocytes and tissue macrophages, which are present in the necrotic core of lesions prone to plaque rupture. Leukocyte-derived myeloperoxidase (MPO), primarily hosted in human polymorphonuclear cells (PMNs), has also been shown to be present in human atherosclerotic lesions. Because MPO and CRP concentrations are increased in acute coronary syndrome (ACS) patients and predict poor outcomes, we tested the effect of CRP on MPO release from PMNs and monocytes.
We treated human PMNs and monocytes with CRP (25 and 50 mg/L for 6 h) and measured MPO release as total mass and activity in culture supernatants. We also measured nitro-tyrosinylation (NO2-Tyr) of LDL as an indicator of biological activity of CRP-mediated MPO release. Furthermore, we explored the effect of human CRP on MPO release in the rat sterile pouch model.
CRP treatment significantly increased release of MPO (both mass and activity) from human PMNs as well as monocytes (P < 0.05) and caused NO2-Tyr of LDL. Human CRP injection in rats resulted in increased concentrations of MPO in pouch exudates (P < 0.05), thus confirming our in vitro data.
CRP stimulates MPO release both in vitro and in vivo, providing further cogent data for the proinflammatory effect of CRP. These results might further support the role of CRP in ACS.
Inflammation and the generation of reactive oxygen species (ROS) have been implicated in the initiation and progression of atherosclerosis. Although C-reactive protein (CRP) has traditionally been considered to be a biomarker of inflammation, recent in vitro and in vivo studies have provided evidence that CRP, itself, exerts pro-thrombotic effects on vascular cells and may thus play a critical role in the development of atherothrombosis. Of particular importance is that CRP interacts with Fcγ receptors on cells of the vascular wall giving rise to the release of pro-thrombotic factors. The present review focuses on distinct sources of CRP-mediated ROS generation as well as the pivotal role of ROS in CRP-induced tissue factor expression. These studies provide considerable insight into the role of the oxidative mechanisms in CRP-mediated stimulation of pro-thrombotic factors and activation of platelets. Collectively, the available data provide strong support for ROS playing an important intermediary role in the relationship between CRP and atherothrombosis.
atherothrombosis; C-reactive protein; platelet; reactive oxygen species; vascular cells
Modified low density lipoproteins (LDL), including their oxidized forms, have been widely implicated in the etiology of atherosclerosis and concomitant cardiovascular disease (CVD) in chronic renal failure (CRF). The nature of events that lead to oxidative changes in LDL proteins are not clearly understood. Thus, patients suffering from CRF were grouped into mild, moderate and severe categories based on their blood urea and serum creatinine levels. Progression of CRF was accompanied not only with gradual increase in serum malondialdehyde (MDA) but also parallel increase in conjugated diene and MDA levels in LDL fractions separated from serum. Serum superoxide dismutase (SOD) activity was concurrently found to decrease, along with a decrease in high-density lipoprotein (HDL) cholesterol, during the progression of CRF. Gradual increase in the appearance of LDL oxidation products seems to accompany progressive manifestation of CRF. The results presented suggest that determination of serum MDA and SOD levels may enhance the diagnostic significance of the study of lipid profile in determining the risk for cardio vascular disease in CRF.
Chronic renal failure; Malondialdehyde; Superoxide dismutase; Low density lipoproteins; Lipid peroxidation
Statins are frequently administered to reduce low-density lipoprotein cholesterol (LDL-C) and vascular inflammation, because LDL-C and high sensitive C-reactive protein (hs-CRP) are associated with high risk for cardiovascular events. When statins do not reduce LDL-C to desired levels in high-risk patients with coronary artery disease (CAD), ezetimibe can be added or the statin dose can be increased. However, which strategy is more effective for treating patients with CAD has not been established. The present study compares anti-inflammatory effects and lipid profiles in patients with CAD and similar LDL-C levels who were treated by increasing the statin dose or by adding ezetimibe to the original rosuvastatin dose to determine the optimal treatment for such patients.
46 patients with high-risk CAD and LDL-C and hs-CRP levels of >70 mg/dL and >1.0 mg/L, respectively, that were not improved by 4 weeks of rosuvastatin (2.5 mg/day) were randomly assigned to receive 10 mg (R10, n = 24) of rosuvastatin or 2.5 mg/day of rosuvastatin combined with 10 mg/day of ezetimibe (R2.5/E10, n = 22) for 12 weeks. The primary endpoint was a change in hs-CRP.
Baseline characteristics did not significantly differ between the groups. At 12 weeks, LDL-C and inflammatory markers (hs-CRP, interleukin-6, tumour necrosis factor-alpha and pentraxin 3) also did not significantly differ between the two groups (LDL-C: R10 vs. R2.5/E10: -19.4 ± 14.2 vs. -22.4 ± 14.3 mg/dL). However, high-density lipoprotein cholesterol (HDL-C) was significantly improved in the R10, compared with R2.5/E10 group (4.6 ± 5.9 vs. 0.0 ± 6.7 mg/dL; p < 0.05).
Both enhanced therapies exerted similar anti-inflammatory effects under an equal LDL-C reduction in patients with high-risk CAD despite 2.5 mg/day of rosuvastatin. However, R10 elevated HDL-C more effectively than R2.5/E10.
Statin; Secondary prevention; Coronary artery disease
Cardiovascular mortality is associated with vascular calcification (VC) in hemodialysis (HD) patients. The present study was designed to find factors related with medial artery calcification on the plain radiography of feet by comparing C-reactive protein (CRP), plasminogen activator inhibitor type 1 (PAI-1) and lipid profile including oxidized low density lipoprotein (ox-LDL) and to elucidate associations among these factors in HD patients. Forty-eight HD patients were recruited for this study. VC in the feet was detected in 18 patients (37.5%) among total patients and 12 patients (85.7%) among diabetic patients. Diabetes, cardiovascular disease (CVD), pulse pressure, ox-LDL/LDL were higher and high density lipoprotein (HDL) was lower in patients with VC than in patients without VC. Negative associations were found between HDL and CRP, PAI-1. PAI-1 had positive association with ox-LDL/LDL. History of CVD was the only determinant of vascular calcification on the plain radiography of feet. Ox-LDL/LDL, HDL, CRP, and PAI-1 were closely related with one another in HD patients. History of CVD is the most important factor associated with the presence of VC and low HDL and relatively high oxidized LDL/LDL ratio may affect VC formation on the plain radiography in the feet of HD patients.
Vascular Calcification; Oxidized Low Density Lipoprotein; High Density Lipoproteins; Hemodialysis
Oxidative stress and inflammation are crucial in atherogenesis. α-Tocopherol is both an antioxidant and an antiinflammatory agent.
We evaluated the effect of RRR-α-tocopherol supplementation on carotid atherosclerosis in patients with stable coronary artery disease (CAD) on drug therapy.
Randomized, controlled, double-blind trial compared RRR-α-tocopherol (1200 IU/d for 2 y) with placebo in 90 patients with CAD. Intimal medial thickness (IMT) of both carotid arteries was measured by high-resolution B-mode ultrasonography at 0, 1, 1.5, and 2 y. At 6-mo intervals, plasma α-tocopherol concentrations, C-reactive protein (CRP), LDL oxidation, monocyte function (superoxide anion release, cytokine release, and adhesion to endothelium), and urinary F2-isoprostanes were measured.
α-Tocopherol concentrations were significantly higher in the α-tocopherol group but not in the placebo group. High-sensitivity CRP concentrations were significantly lowered with α-tocopherol supplementation than with placebo (32%; P <0.001). α-Tocopherol supplementation significantly reduced urinary F2-isoprostanes (P <0.001) and monocyte superoxide anion and tumor necrosis factor release compared with baseline and placebo (P < 0.001). No significant difference was observed in the mean change in total carotid IMT in the placebo and α-tocopherol groups. In addition, no significant difference in cardiovascular events was observed (P = 0.21).
High-dose RRR-α-tocopherol supplementation in patients with CAD was safe and significantly reduced plasma biomarkers of oxidative stress and inflammation but had no significant effect on carotid IMT during 2 y.
Vitamin E; atherosclerosis; coronary artery disease; inflammation; oxidative stress; intimal media thickness; carotid
Carbohydrate quantity and quality may influence risk of cardiovascular disease through blood lipid concentrations and inflammation. We measured dietary glycemic index (GI) and dietary glycemic load (GL) among 18,137 healthy women ≥ 45 years old without diagnosed diabetes using a food-frequency questionnaire. We assayed fasting total, HDL, and LDL cholesterol, LDL:HDL cholesterol ratio, triacylglycerols (TG), and C-reactive protein (CRP). We evaluated associations with dietary GI and GL using a cross-sectional design, adjusting for age, body mass index, lifestyle factors, and other dietary factors. Dietary GI was significantly associated with HDL and LDL cholesterol, LDL:HDL cholesterol ratio, TG, and CRP (comparing top to bottom quintile difference in HDL cholesterol = -2.6 mg/dL, LDL cholesterol = 2.2 mg/dL, LDL:HDL cholesterol ratio = 0.16, TG = 12 mg/dL, and CRP = 0.21 mg/L). Dietary GL was associated with HDL cholesterol, LDL:HDL cholesterol ratio, and TG (comparing top to bottom quintile HDL cholesterol = -4.9 mg/dL, LDL:HDL cholesterol ratio = 0.24, and TG = 13 mg/dL). Differences in blood lipids and CRP between extreme quintiles of dietary GI and GL were small, but may translate into a clinically meaningful difference in cardiovascular risk.
Lipid-coated metal nanoparticles are developed here as a mimic of low-density lipoprotein (LDL) particles and used to study C-reactive protein (CRP) binding to highly curved lipid membranes. A 12 nm shift in the localized surface plasmon resonance (LSPR) was observed when CRP was added to the lipid-coated gold nanoparticles. Transmission electron microscopy (TEM) revealed that CRP induced a structural change to the lipids, resulting in clusters of nanoparticles. This clustering provides a visualization of how CRP could cause the aggregation of LDL particles, which is a key step in atherosclerosis. The cluster formation and resultant LSPR shift requires the presence of both CRP and calcium. Fluorescence anisotropy, using a CRP-specific, fluorophore-labeled aptamer confirmed that CRP was bound to the lipid-coated nanoparticles. An increase in the fluorescence anisotropy (Δr = +0.261 ± 0.004) of the aptamer probe occurs in the presence of CRP, PC-coated nanoparticles, and calcium. Subsequent sequestration of calcium by EDTA leads to a decrease in the anisotropy (Δr = -0.233 ± 0.011), however, there is no change in the LSPR and no change to the cluster structure observed by TEM. This indicates that CRP binds to the PC membrane on the nanoparticle surface reversibly through a calcium bridging mechanism while changing the underlying membrane structure irreversibly as a result of binding.
CRP; gold; LDL; biomimicry; lipid; atherosclerosis
Oxidative modification of low-density lipoproteins (LDL) contributes to the pathology of atherosclerosis. Antioxidants may protect LDL against oxidative modification. Acetaminophen, a widely used analgesic and antipyretic agent, has significant antioxidant properties. However, there is little evidence to suggest that acetaminophen acts as an antioxidant for LDL oxidation in vivo. In this study, we investigated the in vivo effect of acetaminophen on LDL oxidation in hypercholesterolemic rabbits. The oxidative modification of LDL was identified by conjugated dienes and thiobarbituric acid-reactive substances (TBARS). In the cholesterol group which rabbits were fed a diet contained 1% g cholesterol for 8 weeks, TBARS contents and conjugated diene levels in the plasma and isolated LDL samples significantly increased compared with the control rabbits (p<0.05). However, in the cholesterol + acetaminophen group, the TBARS contents and conjugated diene levels were significantly lower than that of the cholesterol group (p<0.05). The results from in vitro studies also demonstrated that the LDL isolated from serum was oxidized by Cu++ ions and this oxidation reduced in the presence of acetaminophen. The reduced oxidative modification of LDL by acetaminophen may be of therapeutic value in preventing the development and progression of atherosclerosis.
Oxidation of LDL; atherosclerosis; acetaminophen; hypercholesterolemia; rabbit
Here we demonstrate that aptamers tethered to gold nanoparticles enable direct visualization of protein-oligonucleotide interactions during gel electrophoresis. This technique is used to confirm that an aptamer previously identified as binding to C-reactive protein (CRP) only binds to the monomeric form of CRP. While native, pentameric CRP (pCRP) is used in clinical assays to predict cardiovascular disease (CVD) risk, it is the monomeric isoform that is more strongly associated with pro-inflammatory and pro-atherogenic effects. To visualize this selectivity, the CRP-aptamer was conjugated to streptavidin-coated gold nanoparticles and the mobility of the free oligonucleotide-nanoparticle conjugate (ON-NP) and the protein/ON-NP complex bands were visualized and recorded during electrophoresis using a simple digital camera. At a concentration of 6 mg/mL, monomeric CRP showed a significant decrease in the observed ON-NP mobility, whereas no change in mobility was observed with pCRP up to 18 mg/mL. Advantages of this nanoparticle-based electrophoretic mobility shift assay (NP-EMSA) over traditional EMSA include real-time detection of protein-oligonucleotide interactions, the avoidance of harmful radioisotopes, and elimination of the need for expensive gel imagers. The availability of both the NP-EMSA technique and an mCRP specific probe will allow for improved clinical diagnostic to more accurately predict future CVD risk.
Aptamer; C-reactive protein; EMSA; Nanoparticle; Real-time detection