Should C-reactive protein be a target of therapy?

C-reactive protein: a target for therapy to reduce inflammation

C-reactive protein (CRP) is well-recognized as a sensitive biomarker of inflammation. Association of elevations in plasma/serum CRP level with disease state has received considerable attention, even though CRP is not a specific indicator of a single disease state. Circulating CRP levels have been monitored with a varying degree of success to gauge disease severity or to predict disease progression and outcome. Elevations in CRP level have been implicated as a useful marker to identify patients at risk for cardiovascular disease and certain cancers, and to guide therapy in a context-dependent manner. Since even strong associations do not establish causality, the pathogenic role of CRP has often been over-interpreted. CRP functions as an important modulator of host defense against bacterial infection, tissue injury and autoimmunity. CRP exists in conformationally distinct forms, which exhibit distinct functional properties and help explaining the diverse, often contradictory effects attributed to CRP. In particular, dissociation of native pentameric CRP into its subunits, monomeric CRP, unmasks "hidden" pro-inflammatory activities in pentameric CRP. Here, we review recent advances in CRP targeting strategies, therapeutic lowering of circulating CRP level and development of CRP antagonists, and a conformation change inhibitor in particular. We will also discuss their therapeutic potential in mitigating the deleterious actions attributed to CRP under various pathologies, including cardiovascular, pulmonary and autoimmune diseases and cancer.

Cardiovascular benefits of air purifier in patients with stable coronary artery disease: A randomized single-blind crossover study

Background

Exposure to PM_2.5 will accelerate the progression of cardiovascular diseases. Air purifier can reduce the PM_2.5 exposure and theoretically alleviate the influence of PM_2.5 on patients with stable coronary artery disease (SCAD). However, few studies of the protective effect showed significant results because the interferent effects of routine medication had not been taken into account. In order to explore the actual effect on patients with SCAD, we conducted a randomized single-blind crossover air purifier intervention trial.

Method

Levels of PM_2.5 exposure during intervention and cardiovascular indicators (inflammation, coagulation, plaque stability, and blood lipids) after intervention were detected, meanwhile the information of drug use was obtained by questionnaire. The kinds of drug used by more than 20% of the subjects were sorted out. And the influence of these drugs on cardiovascular indicators was summarized through literature review. Based on that, the drug use was included as a variable in linear mixed effects models that used to analyze the associations between PM_2.5 exposure reduction by air purifier and cardiovascular indicators.

Results

The result revealed that the interpretation contribution rate of drug use was more than that of PM_2.5 exposure. The level of C-reactive protein significantly decreased by 20.93% (95%CI: 6.56%, 33.10%), 23.44% (95%CI: 2.77%, 39.39%) and 24.11% (95%CI: 4.21%, 39.69%) on lag1, lag01 and lag02 respectively, while the level of high-density lipoprotein cholesterol significantly increased by 5.10% (95%CI: 0.69%, 9.05%), 3.71% (95%CI: 0.92%, 6.60%) and 6.48% (95%CI: 2.58%, 10.24%) respectively on lag0, lag1 and lag01 associated with an interquartile range decrease of 22.51 μg/m³ in PM_2.5 exposure.

Conclusion

The study shows positive effects of air purifier on SCAD, and also provides methodological reference for future related research.

Anti-Inflammatory Therapy for Atherosclerosis: Focusing on Cytokines

Atherosclerosis is a well-known global health problem. Despite the high prevalence of the disease, numerous aspects of pathogenesis remain unclear. Subsequently, there are still no cure or adequate preventive measures available. Atherogenesis is now considered a complex interplay between lipid metabolism alterations, oxidative stress, and inflammation. Inflammation in atherogenesis involves cellular elements of both innate (such as macrophages and monocytes) and adaptive immunity (such as B-cells and T-cells), as well as various cytokines cascades. Because inflammation is, in general, a well-investigated therapeutic target, and strategies for controlling inflammation have been successfully used to combat a number of other diseases, inflammation seems to be the preferred target for the treatment of atherosclerosis as well. In this review, we summarized data on targeting the most studied inflammatory molecular targets, CRP, IL-1β, IL-6, IFN-γ, and TNF-α. Studies in animal models have shown the efficacy of anti-inflammatory therapy, while clinical studies revealed the incompetence of existing data, which blocks the development of an effective atheroprotective drug. However, all data on cytokine targeting give evidence that anti-inflammatory therapy can be a part of a complex treatment.

Automatic text-mining as an unbiased approach to uncover molecular associations between periodontitis and coronary artery disease

The increasing prevalence of periodontal and cardiovascular diseases is the result of a sedentary lifestyle associated with poor diet, obesity, hypercholesterolaemia, smoking habits, alcohol consumption and stress. The present study aims to uncover molecular associations between periodontitis and coronary heart disease using an unbiased strategy of automatic text mining traditionally applied to bibliometric studies. A total of 1590 articles on these diseases were retrieved from the Web of knowledge database and searched using the VOS viewer to create a network of keywords associated with both diseases. These data were supplemented with data from DisGeNET, which stores known associations to either periodontitis or coronary heart disease. Overall, the automated text mining approach presented here highlighted inflammatory molecules as common associations between periodontitis and coronary heart disease. Specifically, this study showed that molecules such as C-reactive protein, interleukins 6 and 1-β, myeloperoxidase, and matrix metalloproteinase 9 are simultaneously associated with periodontitis and coronary artery disease by both text mining and DisGeNET analyses. This association validates the multiplex assessment of salivary inflammatory markers as a tool to assess cardiovascular disease risk and could become an important tool to identify common molecular targets to monitor both diseases simultaneously. In addition, the text mining protocol and subsequent data processing and methods using bioinformatics tools could be useful to uncover links between other diseases.

Serum Ischemia-Modified Albumin, Fibrinogen, High Sensitivity C- Reactive Proteins in Type-2 Diabetes Mellitus without Hypertension and Diabetes Mellitus with Hypertension: A Case-Control Study

Background

The objective of this study was to determine the levels of serum ischemia-modified albumin (IMA), fibrinogen (FIB) and high sensitivity C-reactive protein (hs-CRP) in type 2 diabetes mellitus (T2DM) patients with hypertension (HT) (DMT2HTN) and without HT (DMT2). Also, their association with certain biochemical and physical factors were studied to identify possible risk factors that lead to cardiovascular complications.

Methods

Fasting blood samples were collected from 35 DMT2 or DMT2HTN patients each to analyze differences in serum and plasma levels of IMA, hs-CRP, FIB, total cholesterol (TC), high and low density lipoproteins (HDL and LDL), triglyceride (TG), hemoglobin A1c (HbA1C), glycated hemoglobin and creatinine.

Results

In DMT2 and DMT2HTN patients, IMA, hs-CRP, FIB, TC, TG, HDL, LDL, glycated hemoglobin and creatinine levels, including body mass index (BMI) and waist-to-hip ratio (WHR), were significantly higher relative to healthy controls. In addition, the levels of IMA, hs-CRP and FIB levels showed a strong link to BMI, WHR, TC, TG, LDL and glycated hemoglobin. Lastly, both DMT2 and DMT2HTN patients demonstrated a significant reduction in HDL.

Conclusion

DMT2 and DMT2HTN patients have a greater risk of developing cardiovascular related complications. This study suggests that quantifying hs-CRP, IMA and FIB levels can help diagnose the risk of developing complications during the early stages of metabolic and cardiovascular disease. Overall, the specific risk factors may be used for early identification of cardiovascular complications to decrease mortality and morbidity in T2DM patients.

Association between C reactive protein and all-cause mortality in the ELSA-Brasil cohort

Background

High-sensitivity C reactive protein (hsCRP) has been proposed as a marker of incident cardiovascular disease and vascular mortality, and may also be a marker of non-vascular mortality. However, most evidence comes from either North American or European cohorts. The present proposal aims to investigate the association of hsCRP with the risk of all-cause mortality in a multiethnic Brazilian population.

Methods

Baseline data (2008–2010) of a cohort of 14 238 subjects participating in the Brazilian Longitudinal Study of Adult Health were used. hsCRP was assayed with immunochemistry. The association of baseline covariates with all-cause mortality was calculated by Cox regression for univariate model and adjusted for different confounders after a mean follow-up of 8.0±1.1 years. The final model was adjusted for age, sex, self-rated race/ethnicity, schooling, health behaviours and prevalent chronic disease.

Results

The risk of death increased steadily by quartiles of hsCRP, from 1.45 (95% CI 1.05 to 2.01) in quartile 2 to 1.95 (95% CI 1.42 to 2.69) in quartile 4, compared with quartile 1. Furthermore, the persistence of a significant graded association after the exclusion of deaths in the first year of follow-up suggests that these results are unlikely to be due to reverse causality. Finally, the HR was unaffected by the exclusion of participants who had self-reported medical history of diabetes, cancer and chronic obstructive pulmonary disease.

Conclusions

Our study shows that hsCRP level is associated with mortality in a highly admixed population, independent of a large set of lifestyle and clinical variables.

High-sensitive C-reactive protein and risk of incident type 2 diabetes: a case-control study nested within the Singapore Chinese Health Study

BACKGROUND

The liver-derived C-reactive protein (CRP) is a sensitive and systemic biomarker of inflammation, and has been associated with increased risk of developing type 2 diabetes in populations other than Chinese. Therefore, we prospectively examined the relation between plasma levels of CRP and risk of type 2 diabetes (T2D) among a Chinese population.

METHODS

Plasma high-sensitive CRP (hs-CRP) concentrations were assayed among 571 T2D cases and 571 controls nested in the prospective cohort of the Singapore Chinese Health Study. Both cases and controls were free of physician-diagnosed diabetes, cardiovascular disease and cancer at blood collections (1999-2004). Incident physician-diagnosed T2D cases were self-reported during the follow-up visits (2006-2010), and controls were matched for age (±3 years) and date (±6 months) of blood collection and gender. Multivariable logistic regression models were used to compute the odds ratio (OR) and the corresponding 95% confidence intervals (CIs).

RESULTS

The mean (SD) concentrations of hs-CRP were 2.79 (2.65) and 1.86 (2.03) mg/L, respectively, in cases and controls (P < 0.001). After multivariate adjustment for T2D risk factors such as lifestyle, body mass index, plasma triglycerides and HDL cholesterol, the OR comparing the extreme quartiles of hs-CRP was 1.74 [95% CI 1.12-2.70; P for trend = 0.016]. When the analysis was limited to 279 cases who had HbA1c ≥6.5% at the time of blood collection and their controls, the OR comparing the extreme quartiles of hs-CRP was 2.43 (95% CI 1.25-4.71; P for trend = 0.003). When confined to the other 292 subjects with HbA1c <6.5% and their controls, the corresponding OR was 1.24 (95% CI 0.64-2.39; P for trend = 0.93).

CONCLUSIONS

We found that CRP was not associated with increased risk of incident diabetes in this cohort of Chinese in Singapore. Previous positive findings from prospective studies might be partly due to undiagnosed T2D among the cases during blood collection.

C-Reactive Protein: An In-Depth Look into Structure, Function, and Regulation

Cardiovascular disease is the leading cause of morbidity and mortality in the adult population worldwide, with atherosclerosis being its key pathophysiologic component. Atherosclerosis possesses a fundamental chronic inflammatory aspect, and the involvement of numerous inflammatory molecules has been studied in this scenario, particularly C-reactive protein (CRP). CRP is a plasma protein with strong phylogenetic conservation and high resistance to proteolysis, predominantly synthesized in the liver in response to proinflammatory cytokines, especially IL-6, IL-1β, and TNF. CRP may intervene in atherosclerosis by directly activating the complement system and inducing apoptosis, vascular cell activation, monocyte recruitment, lipid accumulation, and thrombosis, among other actions. Moreover, CRP can dissociate in peripheral tissue—including atheromatous plaques—from its native pentameric form into a monomeric form, which may also be synthesized de novo in extrahepatic sites. Each form exhibits distinct affinities for ligands and receptors, and exerts different effects in the progression of atherosclerosis. In view of epidemiologic evidence associating high CRP levels with cardiovascular risk—reflecting the biologic impact it bears on atherosclerosis—measurement of serum levels of high-sensitivity CRP has been proposed as a tool for assessment of cardiovascular risk.

Noncardiogenic stroke patients with metabolic syndrome have more border-zone infarction and intracranial artery stenosis

BACKGROUND

Little is known about the clinical character of stroke patients with metabolic syndrome (MetS) in Chinese population. In this hospital-based cross-sectional study, we elucidated the prevalence of MetS among patients with acute noncardiogenic cerebral infarction from south China, the topographic infarction patterns in magnetic resonance imaging, and vascular angiography findings of stroke patients with MetS.

METHODS

The patients with acute noncardiogenic stroke were clinically evaluated including waistline circumference, blood pressure, glycemia, serum triglyceride, high-density lipoprotein cholesterol level, magnetic resonance imaging, and angiography evaluation, including magnetic resonance angiography, computed tomography angiography, or digital subtraction angiography for intracranial (IC) and extracranial arteries. According to the National Cholesterol Education Program Adult Treatment Panel III criterion, the patients were classified into the MetS and non-MetS groups.

RESULTS

Among 222 patients studied, the prevalence of MetS was 54.5%, and there were more women in the MetS group than in the non-MetS group (P < .05). Frequency of all the individual factors of MetS was higher in the MetS group than in the non-MetS group (P < .05). The lesion pattern of border-zone (BZ) infarction was more prevalent in MetS patients (P < .05). The frequency of IC artery stenosis was higher in the MetS group than in the non-MetS group (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.0-3.0). After adjustment for age and gender, IC stenosis was significantly associated with large waistline circumference (OR, .95; 95% CI, .91-.99).

CONCLUSIONS

According to our findings, MetS was of high prevalence in noncardiogenic stroke patients in China, and female patients were more likely to have MetS. The MetS patients tended to have more BZ infarctions and more IC artery stenosis than the non-MetS stroke patients.

Anti-inflammatory and anti-thrombogenic effects of atorvastatin in acute ischemic stroke

Atorvastatin decreases inflammation and thrombogenesis in patients with carotid artery plaque. Atorvastatin is administered to lower lipid levels, but its anti-inflammatory and anti-thrombogenic effects remain unclear. Eighty-nine patients from northeastern China with acute ischemic stroke caused by large-artery atherosclerosis were randomly divided into the study and control groups. All patients received routine treatment, including antiplatelet therapy, circulatory support, and symptomatic treatment. The study group (n = 43) also received daily atorvastatin 20 mg/d, and the control group (n = 46) received daily placebo pills containing glucose. After 4 weeks, the levels of C-reactive protein, fibrinogen, and D-dimer were significantly lower in the study group than in the control group. Decreases in the levels of C-reactive protein, fibrinogen, and D-dimer were not associated with decreases in the levels of triacylglycerol and low-density lipoprotein cholesterol. These results suggest that atorvastatin reduces inflammation and thrombogenesis independent of its lipid-lowering effects in patients with acute ischemic stroke caused by large-artery atherosclerosis.

C-reactive protein: clinical and epidemiological perspectives

An important etiopathogenic component of cardiovascular disease is atherosclerosis, with inflammation being an essential event in the pathophysiology of all clinical pictures it comprises. In recent years, several molecules implicated in this process have been studied in order to assess cardiovascular risk in both primary and secondary prevention. C-reactive protein is a plasmatic protein of the pentraxin family and an acute phase reactant, very useful as a general inflammation marker. Currently, it is one of the most profoundly researched molecules in the cardiovascular field, yet its clinical applicability regarding cardiovascular risk remains an object of discussion, considered by some as a simple marker and by others as a true risk factor. In this sense, numerous studies propose its utilization as a predictor of cardiovascular risk through the use of high-sensitivity quantification methods for the detection of values <1 mg/L, following strict international guidelines. Increasing interest in these clinical findings has led to the creation of modified score systems including C-reactive protein concentrations, in order to enhance risk scores commonly used in clinical practice and offer improved care to patients with cardiovascular disease, which remains the first cause of mortality at the worldwide, national, and regional scenarios.

Are C-reactive protein associated genetic variants associated with serum levels and retinal markers of microvascular pathology in Asian populations from Singapore?

Introduction

C-reactive protein (CRP) levels are associated with cardiovascular disease and systemic inflammation. We assessed whether CRP-associated loci were associated with serum CRP and retinal markers of microvascular disease, in Asian populations.

Methods

Genome-wide association analysis (GWAS) for serum CRP was performed in East-Asian Chinese (N = 2,434) and Malays (N = 2,542) and South-Asian Indians (N = 2,538) from Singapore. Leveraging on GWAS data, we assessed, in silico, association levels among the Singaporean datasets for 22 recently identified CRP-associated loci. At loci where directional inconsistencies were observed, quantification of inter-ethnic linkage disequilibrium (LD) difference was determined. Next, we assessed association for a variant at CRP and retinal vessel traits [central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE)] in a total of 24,132 subjects of East-Asian, South-Asian and European ancestry.

Results

Serum CRP was associated with SNPs in/near APOE, CRP, HNF1A and LEPR (p-values ≤4.7×10⁻⁸) after meta-analysis of Singaporean populations. Using a candidate-SNP approach, we further replicated SNPs at 4 additional loci that had been recently identified to be associated with serum CRP (IL6R, GCKR, IL6 and IL1F10) (p-values ≤0.009), in the Singaporean datasets. SNPs from these 8 loci explained 4.05% of variance in serum CRP. Two SNPs (rs2847281 and rs6901250) were detected to be significant (p-value ≤0.036) but with opposite effect directions in the Singaporean populations as compared to original European studies. At these loci we did not detect significant inter-population LD differences. We further did not observe a significant association between CRP variant and CRVE or CRAE levels after meta-analysis of all Singaporean and European datasets (p-value >0.058).

Conclusions

Common variants associated with serum CRP, first detected in primarily European studies, are also associated with CRP levels in East-Asian and South-Asian populations. We did not find a causal link between CRP and retinal measures of microvascular disease.

Changes in A1C levels are significantly associated with changes in levels of the cardiovascular risk biomarker hs-CRP: results from the SteP study

OBJECTIVE

The effect of therapeutic strategies on cardiovascular (CV) disease can be evaluated by monitoring changes in CV risk biomarkers. This study investigated the effect of a structured self-monitoring of blood glucose (SMBG) protocol and the resulting improvements in glycemic control on changes in high-sensitivity C-reactive protein (hs-CRP) in insulin-naïve patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The Structured Testing Program (STeP) study was a prospective, cluster-randomized, multicenter trial in which 483 poorly controlled, insulin-naïve patients with type 2 diabetes were randomized to active control (ACG) or structured testing (STG) that included quarterly structured SMBG. Changes in A1C, hs-CRP, and glycemic variability (STG subjects only) were measured at baseline and quarterly.

RESULTS

Reductions in geometric mean hs-CRP values were significantly greater in the STG group at months 3 (P = 0.005), 6 (P = 0.0003), and 12 (P = 0.04) than in the ACG group. STG patients at high CV risk (>3 mg/L) showed significantly greater reductions in hs-CRP levels than ACG patients at high CV risk: -3.64 mg/dL (95% CI -4.21 to -3.06) versus -2.18 mg/dL (-2.93 to -1.43), respectively (P = 0.002). There was a strong correlation between reductions in hs-CRP and A1C in both groups: standardized coefficient (β) was 0.25 for the entire cohort (P < 0.0001), 0.31 for STG (P < 0.0001), and 0.16 for ACG (P = 0.02).

CONCLUSIONS

Reductions in hs-CRP level are associated with reductions in A1C but not reductions in lipids or glycemic variability. Comprehensive structured SMBG-based interventions that lower A1C may translate into improvements in CV risk, as evidenced by levels of the biomarker hs-CRP.

Discordant association of C-reactive protein with clinical events and coronary luminal narrowing in postmenopausal women: data from the Women's Angiographic Vitamin and Estrogen (WAVE) study

BACKGROUND

The incidence of cardiovascular events had been shown to be associated with C-reactive protein (CRP). However, it is unclear that the cardiovascular risk associated with CRP is due to progressive coronary narrowing or to other factors such as formation of unstable plaque. This study was designed to determine the effect of baseline CRP on cardiovascular events and on the progression of atherosclerotic narrowing among 423 postmenopausal women with angiographic stenosis between 15% and 75%.

HYPOTHESIS

Baseline CRP levels may affect cardiovascular events and progression of atherosclerotic coronary artery narrowing among postmenopausal women.

METHODS

Baseline and follow-up (2.8 years) angiographic data were analyzed among 320 women. Women were stratified into 4 quartiles according to baseline CRP levels. The changes in lumen diameter and clinical events in each quartile were compared.

RESULTS

The annualized changes in minimal and average lumen diameter in diseased and nondiseased coronary segments were not significantly associated with baseline CRP levels. The composite end point of all-cause mortality and myocardial infarction (MI) increased from 3% (3/107) in the first CRP quartile to 14% (14/98) in fourth CRP quartile (P < 0.001). Similar results were found for cardiovascular death and MI (increased from 1% (2/107) in the first quartile to 11% (11/98) in fourth quartile). The difference remained significant even after adjustment for baseline differences and cardiovascular risk factors.

CONCLUSIONS

Higher baseline CRP was associated with increased risk of clinical events but was not associated with annualized change in luminal diameters. Thus, increased risk of adverse events among patients with higher baseline CRP events was independent of progression of atherosclerosis as measured by change in minimal or average luminal diameter.

Inflammatory markers and risk of type 2 diabetes: a systematic review and meta-analysis

OBJECTIVE

There has been growing evidence that inflammatory markers play a role in the development of type 2 diabetes. We aimed to systematically review prospective studies on the associations of elevated levels of interleukin-6 (IL-6) and C-reactive protein (CRP) with increased risk of type 2 diabetes by conducting a meta-analysis.

RESEARCH DESIGN AND METHODS

A systematic search of the PubMed, EMBASE, ISI Web of Knowledge, and Cochrane Library databases up until 10 February 2012 was conducted to retrieve prospective studies matched to search terms. We used generalized least-squares trend estimation to assess dose-response relationships. The summary risk estimates were pooled using either fixed-effects or random-effects models to incorporate between-study variation.

RESULTS

The meta-analysis, including 10 prospective studies, with a total of 19,709 participants and 4,480 cases, detected a significant dose-response association of IL-6 levels with type 2 diabetes risk (relative risk [RR] 1.31 [95% CI 1.17-1.46]). For CRP, the meta-analysis involving 22 cohorts, with a total of 40,735 participants and 5,753 cases, showed that elevated CRP levels were significantly associated with increased risk of type 2 diabetes (1.26 [1.16-1.37]), with the absence of publication bias. Sensitivity and subgroup analyses further supported the associations.

CONCLUSIONS

This meta-analysis provides further evidence that elevated levels of IL-6 and CRP are significantly associated with increased risk of type 2 diabetes.

Hepatic acute phase proteins--regulation by IL-6- and IL-1-type cytokines involving STAT3 and its crosstalk with NF-κB-dependent signaling

The function of the liver as an important constituent of the immune system involved in innate as well as adaptive immunity is warranted by different highly specialized cell populations. As the major source of acute phase proteins, including secreted pathogen recognition receptors (PRRs), short pentraxins, components of the complement system or regulators of iron metabolism, hepatocytes are essential constituents of innate immunity and largely contribute to the control of a systemic inflammatory response. The production of acute phase proteins in hepatocytes is controlled by a variety of different cytokines released during the inflammatory process with IL-1- and IL-6-type cytokines as the leading regulators operating both as a cascade and as a network having additive, inhibitory, or synergistic regulatory effects on acute phase protein expression. Hence, IL-1β substantially modifies IL-6-induced acute phase protein production as it almost completely abrogates production of acute phase proteins such as γ-fibrinogen, α(2)-macroglobulin or α(1)-antichymotrypsin, whereas production of for example hepcidin, C-reactive protein and serum amyloid A is strongly up-regulated. This switch-like regulation of IL-6-induced acute phase protein production by IL-1β is due to a complex processing of the intracellular signaling events activated in response to IL-6 and/or IL-1β, with the crosstalk between STAT3- and NF-κB-mediated signal transduction being of particular importance. Recent data suggest that in this context complex formation between STAT3 and the p65 subunit of NF-κB might be of key importance. The present review summarizes the regulation of acute phase protein production focusing on the role of the crosstalk of STAT3- and NF-κB-driven pathways for transcriptional control of acute phase gene expression.