C-reactive protein (CRP): more than just an innocent bystander?

Elevated C-reactive protein and cardiovascular risk

PURPOSE OF REVIEW

This review critically examines the evolving role of C-reactive protein (CRP) in cardiovascular disease (CVD), addressing its pathogenesis and relationship with various CVDs including coronary artery disease (CAD), heart failure, and atrial fibrillation.

RECENT FINDINGS

CRP is mechanistically implicated in endothelial dysfunction, oxidative stress, and plaque destabilization. Recent studies demonstrate that lipid-lowering agents (statins, bempedoic acid) and anti-inflammatory therapies (canakinumab, colchicine) reduce CRP levels and improve outcomes in CAD. In heart failure, elevated CRP predicts adverse events, though evidence on phenotypes varies, and novel therapies (glucagon-like peptide-1 agonists, sodium-glucose cotransporter-2 inhibitors) lower CRP independently of weight loss. For atrial fibrillation, CRP correlates with postoperative incidence and recurrence postablation, though data remain inconsistent. Guidelines offer differing opinion with the American College of Cardiology and the American Heart Association (ACC/AHA) guidelines cautiously endorsing CRP for risk stratification in intermediate-risk individuals, while European guidelines advise against its routine use for primary prevention, reflecting unresolved questions about CRP's additive value.

SUMMARY

CRP remains a pivotal inflammation biomarker in CVD, yet its causal role and clinical applicability require clarification. While CRP-guided therapies show promise, discrepancies in guidelines highlight the need for robust trials to determine whether targeting CRP directly improves outcomes. Future research should focus on CRP's pathophysiological mechanisms and validate its utility in personalized CVD management.

Apolipoprotein E (APOE) ε4 moderates the relationship between c-reactive protein, cognitive functioning, and white matter integrity

Elevated serum C-reactive protein (CRP) and possessing an APOE ε4 allele are two of the most prominent risk factors for cognitive and neurological dysfunction in older adults, but little is known about the unique or cumulative effects of these risk factors in young-to-middle-aged adults. To further characterize these potential relationships, measures of cognition and microstructural white matter integrity were examined using data from a sample of 329 post-9/11 war veterans that was collected as part of a comprehensive evaluation that included assessment of neuropsychological functioning, MRI scanning, psychiatric diagnoses, health screening, markers of inflammation, and APOE genotypes. Hierarchical linear regression analyses revealed the CRP and APOE ε4 interaction was associated with global cognition (β = -0.633), executive functioning (β = -0.566), and global fractional anisotropy (β = -0.470), such that elevated CRP was associated with worse cognition and white matter integrity in APOE ε4 carriers. Diffusion tensor imaging (DTI) was used to determine if CRP × APOE ε4 presence was associated with regionally specific fractional anisotropy in white matter tracts. Tract-based spatial statistics revealed CRP × APOE ε4 presence was associated with fractional anisotropy in the corpus callosum, right superior longitudinal fasciculus, right posterior corona radiata, as well as the bilateral anterior and superior corona radiatas. This suggests that APOE ε4 carriers may be uniquely vulnerable to the potentially negative impact of elevated systematic inflammation to cognition and microstructural white matter integrity.

C-reactive protein derived from perivascular adipose tissue accelerates injury-induced neointimal hyperplasia

AIM

Inflammation within the perivascular adipose tissue (PVAT) in obesity plays an important role in cardiovascular disorders. C-reactive protein (CRP) level in obesity patients is significantly increased and associated with the occurrence and progression of cardiovascular disease. We tested the hypothesis CRP derived from PVAT in obesity contributes to vascular remodeling after injury.

METHODS

A high-fat diet (HFD) significantly increased CRP expression in PVAT. We transplanted thoracic aortic PVAT from wild-type (WT) or transgenic CRP-expressing (CRPTG) mice to the injured femoral artery in WT mice.

RESULTS

At 4 weeks after femoral artery injury, the neointimal/media ratio was increased significantly in WT mice that received PVAT from CRPTG mice compared with that in WT mice that received WT PVAT. Transplanted CRPTG PVAT also significantly accelerated adventitial macrophage infiltration and vasa vasorum proliferation. It was revealed greater macrophage infiltration in CRPTG adipose tissue than in WT adipose tissue and CRP significantly increased the adhesion rate of monocytes through receptor Fcγ RI. Proteome profiling showed CRP over-expression promoted the expression of chemokine (C-X-C motif) ligand 7 (CXCL7) in adipose tissue, transwell assay showed CRP increased monocyte migration indirectly via the induction of CXCL7 expression in adipocytes.

CONCLUSION

CRP derived from PVAT was significantly increased in HFD mice and promoted neointimal hyperplasia after vascular injury.

Dyslipidaemia in the elderly: to treat or not to treat?

INTRODUCTION

The elderly population (i.e. aged ≥ 65 years) is increasing worldwide. Ageing is associated with a higher incidence and prevalence of cardiovascular disease (CVD). Areas covered: The prevalence of CVD risk factors including type 2 diabetes mellitus, hypertension and dyslipidaemia also increases with advancing age, contributing to the higher absolute CVD risk observed in the elderly. The present narrative review comments on the associations of dyslipidaemia with CVD as well as the effects of lifestyle measures and lipid-lowering drugs on lipids and CVD risk with a special focus on the elderly population. Individual treatment goals and therapeutic options according to current guidelines are also reviewed. Finally, we discuss special characteristics of the elderly that may influence the efficacy and safety of drug therapy and should be considered before selection of hypolipidaemic pharmacotherapy. Expert commentary: There may be a greater CVD benefit in older patients following drug therapy compared with younger ones. Treatment goals and therapeutic options should be individualized according to current guidelines. Specific characteristics that may influence the efficacy and safety of drug therapy in the elderly should be considered in relation to dyslipidaemia treatment.

Apolipoprotein J: A New Predictor and Therapeutic Target in Cardiovascular Disease?

Objective:

To review the functional mechanism of apolipoprotein J (apoJ) in the process of atherosclerosis and the feasibility of apoJ as a therapeutic endpoint.

Data Sources:

Relevant articles published in English from 1983 to present were selected from PubMed. The terms of “atherosclerosis, apolipoprotein J, clusterin (CLU), oxidative stress, and inflammation” were used for searching.

Study Selection:

Articles studying the role of apoJ with atherosclerosis and restenosis after injury were reviewed. Articles focusing on the intrinsic determinants of atherosclerosis were selected. The exclusion criteria of articles were that the studies on immunologic vasculitis.

Results:

ApoJ, involved in numerous physiological process important for lipid transportation and vascular smooth muscle cell differentiation, including apoptotic cell death, cell-cycle regulation, cell adhesion, tissue remodeling, immune system regulation, and oxidative stress, plays a role in the development of clinical atherosclerosis. In the process of relieving atherosclerosis, apoJ can promote cholesterol and phospholipid export from macrophage-foam cells, and exhibit cytoprotective and anti-inflammatory actions by interacting with lots of known inflammatory proteins which may predict the onset of clinical cardiovascular events and may actually play a causal role in mediating atherosclerotic disease such as C-reactive protein, paraoxonase, and leptin. As known as CLU, apoJ has been identified to play central roles in the process of vascular smooth cells migration, adhesion, and proliferation, which can contribute significantly to restenosis after vascular injury.

Conclusions:

Intense effort and substantial progress have been made to identify the apoJ that relieves atherosclerosis and vascular restenosis after percutaneous coronary intervention. More work is needed to elucidate the exact mechanisms of and the interrelationship between the actions of apoJ and to successfully achieve regression of atherosclerosis by regarding it as a therapeutic endpoint.

Possible mechanisms of C-reactive protein mediated acute myocardial infarction

Myocardial infarction is a relevant cardiovascular event worldwide for morbidity and mortality. It has been theorized that acute myocardial infarctions (AMIs) and other acute coronary events that are precipitated by atherosclerosis are due to arterial blockage from fat deposits. It is now known, however, that atherosclerosis involves more than just lipids. Inflammation has also been studied extensively to play a substantial role in myocardial infarction. There have been debates and conflicting reports over the past few years about the value of assessing levels of C-reactive protein and other biomarkers of inflammation for the prediction of cardiovascular events. Several studies have shown that CRP is not only an inflammatory marker, but also involved in the pathogenesis of myocardial infarction. Studies have linked atherogenesis and rupture of atherosclerotic lesion to endothelial dysfunction. CRP directly inhibits endothelial cell nitric oxide (NO) production via destabilizing endothelial NO synthase (eNOS). Decreased NO release causes CRP mediated inhibition of angiogenesis, stimulating endothelial cell apoptosis. CRP can also activate the complement system through the classical pathway. Complement activation plays an important role in mediating monocyte and neutrophil recruitment in an injured myocardium and may therefore lead to increase in infarct size. This article discusses the possible roles of CRP in complement activation, endothelial dysfunction and its impact on the development of myocardial infarction. We also reviewed the possible therapeutic approaches to myocardial infarction.

Fumaric acid esters can block pro-inflammatory actions of human CRP and ameliorate metabolic disturbances in transgenic spontaneously hypertensive rats

Inflammation and oxidative stress have been implicated in the pathogenesis of metabolic disturbances. Esters of fumaric acid, mainly dimethyl fumarate, exhibit immunomodulatory, anti-inflammatory, and anti-oxidative effects. In the current study, we tested the hypothesis that fumaric acid ester (FAE) treatment of an animal model of inflammation and metabolic syndrome, the spontaneously hypertensive rat transgenically expressing human C-reactive protein (SHR-CRP), will ameliorate inflammation, oxidative stress, and metabolic disturbances. We studied the effects of FAE treatment by administering Fumaderm, 10 mg/kg body weight for 4 weeks, to male SHR-CRP. Untreated male SHR-CRP rats were used as controls. All rats were fed a high sucrose diet. Compared to untreated controls, rats treated with FAE showed significantly lower levels of endogenous CRP but not transgenic human CRP, and amelioration of inflammation (reduced levels of serum IL6 and TNFα) and oxidative stress (reduced levels of lipoperoxidation products in liver, heart, kidney, and plasma). FAE treatment was also associated with lower visceral fat weight and less ectopic fat accumulation in liver and muscle, greater levels of lipolysis, and greater incorporation of glucose into adipose tissue lipids. Analysis of gene expression profiles in the liver with Affymetrix arrays revealed that FAE treatment was associated with differential expression of genes in pathways that involve the regulation of inflammation and oxidative stress. These findings suggest potentially important anti-inflammatory, anti-oxidative, and metabolic effects of FAE in a model of inflammation and metabolic disturbances induced by human CRP.

C-reactive protein promotes vascular endothelial dysfunction partly via activating adipose tissue inflammation in hyperlipidemic rabbits

BACKGROUND

Endothelial dysfunction is the basic and original sign of atherogenesis. Some evidences show that C-reactive protein (CRP) and perivascular adipose tissue (PVAT) play a pivotal role in atherosclerosis. However, the effects of CRP on atherosclerosis and the related mechanisms require elucidation.

METHODS

The levels of basic total cholesterol, low-density lipoprotein cholesterol, triglyceride, CRP, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO) and endothelin-1 (ET-1) were respectively measured in rabbits, endothelium-dependent vasorelaxation function was also evaluated. Animals were randomly divided into two groups: PVAT(-) and PVAT(+) group (removing or keeping pericarotid adipose tissue (PCAT)). Both of the two groups were exposed to a high-fat diet for six-week, and then sustained CRP treatment was performed for a week, at this time point all the above parameters were remeasured. In addition, mRNA and protein expression of TNF-α, IL-6, and macrophage chemoattractant protein-1 (MCP-1) were respectively evaluated by Polymerase Chain Reaction and immunoblotting in PCAT and cultured adipocytes treated by CRP.

RESULTS

High-fat diet greatly increased the serum lipids and inflammatory markers, induced endothelial dysfunction and imbalance between NO and ET-1, increased mRNA and protein expression of TNF-α, IL-6, MCP-1 and enhanced macrophage infiltration of PCAT. CRP treatment could further promote macrophage infiltration of PVAT, induce the imbalance between NO and ET-1, aggravate endothelial dysfunction especially in PVAT(+) arteries, and could also enhance the above-mentioned mRNA and protein expression in PCAT and cultured adipocytes.

CONCLUSIONS

CRP could significantly promote endothelial dysfunction in high-fat diet rabbits especially in PVAT(+) groups, which may be partly mediated by activating inflammatory reaction of adipose tissue.

Carotid intima-media thickness in patients with inflammatory bowel disease: a systematic review

We systematically reviewed the available data on carotid intima-media thickness (cIMT) in patients with inflammatory bowel diseases (IBDs) without history of cardiovascular disease (CVD) and its associated factors. A total of 6 studies met the inclusion criteria including 217 patients with Crohn's disease (CD) and 85 with ulcerative colitis (UC). Two studies included only patients with CD. The prevalence of traditional CVD risk factors and the inflammatory burden (IBD duration and activity) varied greatly among patients and studies. Factors that correlated with cIMT were age, male gender, body mass index, arterial hypertension, as well as cholesterol and homocysteine levels. The current data on cIMT in patients with IBD are inconclusive. This is probably due to small number of patients, population heterogeneity with regard to inflammatory burden and smoking habits, and lack of strict matching with controls. In order to elucidate any potential association between IBD and CVD risk, larger prospective studies are required.

C-reactive protein, early life stress, and wellbeing in healthy adults

OBJECTIVE

To determine whether C-reactive protein (CRP) can serve as a marker for alterations in immune function prior to the manifestation of significant psychiatric and medical disorders.

METHOD

Ninety-two healthy adults were recruited from the community and determined to be free of psychiatric or medical disorders. The concentration of plasma CRP from a single resting sample was examined in relation to current mental and physical health as well as to self-reported history of early life adversity.

RESULTS

C-reactive protein showed a significant positive correlation with body mass index (BMI; r = 0.477, P < 0.001). Non-specific pain, fatigue, and lower overall quality of physical health were all associated with higher CRP concentrations (all P < 0.05 or P < 0.01), after controlling for effect of BMI and other relevant covariates. Subthreshold depression symptoms and other indices of mental/emotional wellbeing were not associated with CRP, nor was CRP significantly linked to any measures of early life adversity.

CONCLUSION

Lower-quality physical health and wellbeing, but not the presence of mood/anxiety symptoms or early life stress (ELS), were significantly related to plasma CRP. Elevated CRP does not appear to be a fundamental consequence of ELS among healthy adults.

The CD40 gene polymorphism rs1883832 is associated with risk of acute coronary syndrome in a Chinese case-control study

Numerous reports in the past few years have demonstrated that atherosclerosis is a lipid-driven, chronic inflammatory disease of the vessel. Recent studies have indicated that the immune mediator CD40-CD40L (CD40 ligand), which is expressed on several inflammatory cells within human atherosclerotic lesions, has roles in atherogenesis. A functional polymorphism (-1C>T, rs1883832) in the 5' untranslated region of TNFRSF5 gene has been reported to affect CD40 expression and be associated with several chronic inflammatory and autoimmune diseases. The aim of the present study was to validate the potential coronary artery disease susceptibility marker in a Chinese case-control study. A total of 160 patients with acute coronary syndrome (ACS) and 180 control subjects were used to genotype and identify this single-nucleotide polymorphism by polymerase chain reaction-restriction fragment length polymorphism and sequencing, respectively. Peripheral blood mononuclear cells were isolated and incubated with interferon-γ with or without pretreatment of fluvastatin, followed by measurement of CD40 expression using flow cytometry. In addition, soluble CD40L was determined by ELISA as another biomarker of coronary artery disease. The distribution of the rs1883832 genotypes (CC, CT, and TT) was 33.1%, 54.4%, and 12.5% in the ACS group and 22.8%, 53.3%, and 23.9% in controls, respectively. The frequency of the C allele was significantly higher among ACS patients compared with controls (60.3% vs. 49.4%, odds ratio=1.554, 95% confidence intervals: 1.146-2.107, p<0.05). ACS patients showed a significant increase of CD40 and sCD40L coexpression compared with controls (p<0.05). Cell culture experiments showed that CC carriers presented significantly higher CD40 expression levels than CT and TT subjects (p<0.05). Additionally, fluvastatin suppressed CD40 expression in all three genotypes. These data suggest that the single-nucleotide polymorphism of CD40 gene is associated with susceptibility to ACS in Chinese population, and the polymorphism may influence the CD40 production. These expand the understanding of inflammatory mechanisms during atherogenesis.

Are lipid ratios less susceptible to change with systemic inflammation than individual lipid components in patients with rheumatoid arthritis?

Rheumatoid arthritis (RA) associates with excess cardiovascular risk and there is a need to assess that risk. However, individual lipid levels may be influenced by disease activity and drug use, whereas lipid ratios may be more robust. A cross-sectional cohort of 400 consecutive patients was used to establish factors that influenced individual lipid levels and lipid ratios in RA, using multiple regression models. A further longitudinal cohort of 550 patients with RA was used to confirm these findings, using generalized estimating equations. Cross-sectionally, higher C-reactive protein (CRP) levels correlated with lower levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol ([HDL-C] P ≤ .015), whereas lipid ratios did not correlate with CRP. The findings were broadly replicated in the longitudinal data. In summary, the effects of inflammation on individual lipid levels may underestimate lipid-associated cardiovascular disease (CVD) risk in RA, thus lipid ratios may be more appropriate for CVD risk stratification in RA.

Dorsal (Posterior) Versus Medial Approach for the Surgical Repair of Popliteal Artery Aneurysms

The surgical approach-of-choice for the management of popliteal artery aneurysms (PAAs) remains controversial. We compared the results of the medial (MA) and dorsal (posterior) surgical approach (DA). Fifty patients (44 males/6 females; median age [range]: 59 [49-84] years) treated for 58 atherosclerotic PAAs were studied (MA: 29 PAAs; DA: 29 PAAs). The 3-year graft patency rates were higher after DA compared with MA (76% vs 52%, respectively), but the difference was not significant (P = .056). There were no differences between the 2 approaches in amputation, restenosis, reoperation, and wound infection rates. Dorsal approach and the MA may be alternative approaches with similar long-term results. Due to the controversial results reported so far, a meta-analysis may be necessary to establish the surgical approach-of-choice. Future studies should take into account additional factors, other than the surgical technique, when assessing outcome (eg, preoperative statin use, age, and emergency vs routine surgery).

Atorvastatin restores endothelial function in offspring of protein-restricted rats in a cholesterol-independent manner

Maternal protein restriction in rats leads to endothelial dysfunction and decreased NO bioavailability in the offspring. Statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) are recognized to have pleiotropic actions including increasing NO bioavailability and reducing inflammation and oxidative damage. This study assessed statin treatment on vascular function in a model of endothelial dysfunction, which is independent of dyslipidemia. Wistar rats were fed a control (18% casein) or protein-restricted (9% casein) diet throughout pregnancy. At weaning, a subset of the protein-restricted group was given atorvastatin (10 mg/kg per day) in the drinking water. At 145 days of age, offspring were euthanized by CO(2) inhalation. Plasma samples were collected for markers of inflammation, vascular reactivity of the thoracic aorta, and small mesenteric arteries were assessed on the wire myograph, and tissues were snap frozen for molecular biology analysis. Thoracic aorta endothelial-dependent vasodilatation was attenuated in the male offspring from both protein-restricted groups compared with controls (P<0.05) but was similar in females (P value not significant). Endothelial-dependent dilatation of mesenteric arteries was attenuated in male and female protein-restricted offspring (P<0.05) and was corrected by atorvastatin. Maternal protein restriction increased plasma inflammatory markers granulocyte chemotactic protein, lipocalin-2, and beta(2)-microglobulin in male and C-reactive protein in female offspring (P<0.05). Atorvastatin had no effect on inflammatory markers in the males but restored C-reactive protein to control levels in the females (P<0.05). Aortic and mesenteric artery mRNA levels of endothelial NO synthase, superoxide dismutase 1, and tumor necrosis factor-alpha were unchanged. These data suggest that atorvastatin can restore endothelial function in this model, but its effects are gender specific and dependent on the vascular bed.

JUPITER: major implications for vascular risk assessment

This Editorial comments on the recently published JUPITER trial (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin), the further evidence it provides for supporting the role of statins in primary prevention and the major implications this may hold for vascular risk assessment and clinical practice guidelines.

Statin treatment, carotid atherosclerotic plaque macrophage infiltration and circulating inflammatory markers

BACKGROUND

Statin treatment is considered as first line therapy in patients with atherosclerotic disease. We evaluated the effect of pre-treatment with statins on carotid plaque infiltration by macrophages and on the circulating levels of proinflammatory cytokines in patients who underwent carotid endarterectomy.

PATIENTS AND METHODS

One hundred fourteen patients were enrolled; 89 men and 25 women (mean age 67+/-8 years; range 42-83 years). Fifty three patients (46%) were on statin treatment at least 3 months before endarterectomy and 61 (54%) had never received statin treatment. The serum levels of high sensitivity C reactive protein (hsCRP), serum amyloid A (SAA), tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta and IL-6 were evaluated preoperatively. The intensity of macrophage infiltration was evaluated by immunochemistry, using the monoclonal antibody CD 68. The area of the plaque covered by macrophages was measured as a proportion of the whole plaque area, using a custom designed image tool analysis.

RESULTS

Patients on statins had lower serum total cholesterol levels (172+/-50 vs 194+/-35 mg/dl, p= 0.014), lower low density cholesterol levels (103+/-44 vs 123+/-31 mg/dl, p= 0.010) and lower serum hsCRP levels (1.8 [1.1-3.4] vs 3.4 [1.3-4.9] mg/l, p= 0.03), while SAA, TNFalpha, IL-6 and IL-1beta levels did not differ between the 2 groups. The infiltration of atherosclerotic plaque by macrophages was similar in statin treated patients and in controls (0.55+/-0.15% vs 0.49+/-0.19%, p= 0.21).

CONCLUSION

Patients on statins have similar macrophage accumulation in their carotid atherosclerotic plaques compared with patients not on statins. Inflammatory markers were also similar in both groups except for hsCRP which was significantly lower in those taking statins.

Do Different Vascular Risk Factors Affect All Arteries Equally?

Established vascular risk factors (ie, smoking, hypertension, diabetes mellitus, and dyslipidemia) play an important role in the development of vascular disease. Emerging evidence suggests that some of these risk factors may have a more intense effect on specific arterial beds, a finding that holds implications for a prognostic role for certain types of vascular disease.