C-reactive protein and coronary artery disease-what is the link?

Selected Growth Factors in Peritoneal Dialysis: Their Relationship to Markers of Inflammation, Dialysis Adequacy, Residual Renal Function, and Peritoneal Membrane Transport

Objectives

Markers of chronic inflammation, acute-phase reactants, and growth factors may be concomitantly involved in a number of pathologic processes in the general population and uremic patients. In addition, growth factors may influence peritoneal membrane transport characteristics. However, the association between plasma growth factors, markers of chronic inflammation, and peritoneal membrane transport remains largely unknown. The aim of this study was to evaluate the relationship between plasma levels of selected growth factors [basic fibroblast growth factor (bFGF), transforming growth factor β1 (TGFβ1), vascular endothelial growth factor (VEGF)] and markers of chronic inflammation [interleukin (IL)-6, C-reactive protein (CRP), and fibrinogen] in continuous ambulatory peritoneal dialysis (CAPD) patients. The potential link between the above substances and dialysis adequacy was also explored.

Design

Single-center, cross-sectional study.

Setting

Peritoneal Dialysis Unit, Medical Faculty, Jagiellonian University Hospital, Kraków, Poland.

Patients

32 stable end-stage renal disease patients (13 M, 19 F; mean age 53.6 ± 13.7 years) on CAPD for a median period of 19.5 months. Patients free from signs and symptoms of any inflammatory disease (including peritonitis) for at least 3 months were included into the study. All patients underwent measurements of dialysis dose [Kt/V, weekly creatinine clearance (wCCr)] and peritoneal solute transport using a standard peritoneal equilibration test (PET).

Methods

TGFβ1, bFGF, VEGF, and IL-6 were measured with ELISA, CRP was assayed with immunonephelometry, and fibrinogen with Multifibren U reagent (Dade Behring Marburg GmbH, Marburg, Germany). Nephron 97 for Windows software was used to assess dialysis adequacy.

Results

Significant positive correlations between plasma bFGF and IL-6, as well as fibrinogen concentrations ( R = 0.36, p < 0.05 and R = 0.39, p < 0.05, respectively), were found. VEGF correlated significantly with IL-6 and CRP ( R = 0.65, p < 0.0001 and R = 0.51, p < 0.005, respectively). An association between VEGF and bFGF was also found ( R = 0.59, p < 0.0005). Serum level of TGFβ1 revealed no relationship with any marker of acute-phase activation, remaining growth factors, or dialysis adequacy. Positive correlation between TGFβ1 concentration and dialysate-to-plasma ratio for creatinine in PET ( R = 0.35, p < 0.05) was found. In addition, patients with lower solute transport (low/low-average transporters) had lower serum levels of both bFGF and TGFβ1 compared to patients with higher solute transport. Patients with total wCCr > 60 L/week/m2 were characterized by lower levels of bFGF and IL-6. Serum level of IL-6 and plasma levels of bFGF and VEGF were significantly lower among subjects with residual renal function (RRF) > 2.0 mL/minute.

Conclusions

Our results indicate that systemic inflammation in peritoneal dialysis patients is associated with increased plasma VEGF and bFGF but not TGFβ1. The negative correlation with RRF suggests that either the renal clearance of these cytokines and growth factors may contribute to their elimination, or cytokines and growth factors have a negative impact on RRF. We also suggest an association between serum levels of growth factors tested and peritoneal membrane function.

High Volume Exercise Training in Older Athletes Influences Inflammatory and Redox Responses to Acute Exercise

To examine whether the volume of previous exercise training in older athletes influences inflammatory, redox, and hormonal profiles, 40 trained marathon runners were divided into higher-volume (HVG, ∼480 min/week) and lower-volume groups (LVG, ∼240 min/week). Plasma inflammatory proteins, redox biomarkers, salivary testosterone, and cortisol were assessed at restand following two maximal acute exercise bouts. At rest, the LVG exhibited higher CRP, higher protein carbonyls, and lower SOD activity compared to the HVG (p's < .05). In response to exercise, TNF-α declined similarly in both groups whereas CRP increased differentially (+60% LVG; +24% HVG; p's < .05). Protein carbonyls decreased and thiols increased similarly in both groups, but SOD declined differentially between groups (-14% LVG; -20% HVG; p's < .05). Salivary testosterone decreased similarly in both groups, whereas cortisol did not change. A higher volume of training is associated with favorable inflammatory and redox profiles at rest, perhaps mediated by small inflammatory responses to acute exercise.

Anthocyanins from fruit juices improve the antioxidant status of healthy young female volunteers without affecting anti-inflammatory parameters: results from the randomised, double-blind, placebo-controlled, cross-over ANTHONIA (ANTHOcyanins in Nutrition Investigation Alliance) study

Anthocyanins (ACN) can exert beneficial health effects not only through their antioxidative potential but also through modulation of inflammatory parameters that play a major role in CVD. A randomised cross-over study was carried out to investigate the effects of ACN-rich beverage ingestion on oxidation- and inflammation-related parameters in thirty healthy female volunteers. The participants consumed 330 ml of beverages (placebo, juice and smoothie with 8·9 (sd 0·3), 983·7 (sd 37) and 840·9 (sd 10) mg/l ACN, respectively) over 14 d. Before and after each intervention, blood and 24 h urine samples were collected. Plasma superoxide dismutase (SOD) and catalase activities increased significantly after ACN-rich beverage ingestion (P< 0·001), whereas after placebo juice ingestion no increase could be observed. Plasma glutathione peroxidase and erythrocyte SOD activities were not affected. An increase in Trolox equivalent antioxidant capacity could also be observed after juice (P< 0·001) and smoothie (P< 0·01) ingestion. The plasma and urinary concentrations of malondialdehyde decreased after ACN-rich beverage ingestion (P< 0·001), whereas those of 8-OH-2-deoxyguanosine as well as inflammation-related parameters (IL-2, -6, -8 and -10, C-reactive peptide, soluble cluster of differentiation 40 ligand, TNF-α, monocyte chemoattractant protein-1 and soluble cell adhesion molecules) were not affected. Thus, ingestion of ACN-rich beverages improves antioxidant enzyme activities and plasma antioxidant capacity, thus protecting the body against oxidative stress, a hallmark of ongoing atherosclerosis.

[Effect of "Pintes" white wine on metabolic parameters in patients with metabolic syndrome]

Moderate alcohol consumption has been associated with decreased cardiovascular mortality in the general population. Relatively few studies have been conducted to evaluate the effect of white wine on insulin sensitivity.

AIMS

The authors studied the impact of moderate Pintes white wine consumption on insulin sensitivity and other metabolic parameters.

METHODS

The prospective study involved 18 patients with metabolic syndrome. The patients consumed Pintes white wine for 4 weeks, and parameters were measured before and after consumption.

RESULTS

The HOMA-IR decreased significantly after white wine consumption (2.28±2.04 vs 1.08±0.6; p = 0.002). There were no changes in serum cholesterol, LDL-cholesterol, triglyceride and fasting plasma glucose levels.

CONCLUSION

White wine consumption improved insulin sensitivity in patients with metabolic syndrome.

Cardiac calcification in renal patients: what we do and don't know

Cardiovascular (CV) disease is one of the major causes of mortality in patients with renal diseases, with an increased odds ratio of mortality with risk factors as diverse as blood pressure (high or low), cholesterol level (high or low), left ventricular hypertrophy, vascular stiffness, chronic inflammation, and hyperhomocysteinemia. Mainly cross-sectional studies of renal patients showed excess CV calcification (CVC) compared with the general population, but a clear link between calcification and subsequent mortality is tenuous to date. Several factors have been incriminated to explain the increase in CVC in this particular population. Increased duration of dialysis therapy, dyslipidemia, altered calcium-phosphorus metabolism, and chronic inflammation have all been associated with increased CVC. However, with the shortage of large, observational, population-based, prospective studies tracking these potential risk factors and the pathogenesis of CVC in renal patients not yet sufficiently understood, it is difficult with the present state of knowledge to make robust recommendations about care strategies. The purpose of this review is to examine the 10 available studies of renal patients that have used modern CVC imaging and quantification techniques for clues to likely targets for future interventional studies.

An association between aortic pulse wave velocity, blood pressure and chronic inflammation in ESRD patients on peritoneal dialysis

Increased aortic pulse wave velocity (AoPWV) has been identified as a risk factor for cardiovascular morbidity in the general population and in patients on dialysis. Most of the studies in ESRD patients refer to subjects on hemodialysis. Influence of the inflammatory process on aortic stiffening remains largely unknown. The aim of the present study was to evaluate potential relationships between AoPWV and blood pressure, basic anthropometric parameters, selected growth factors and markers of the inflammatory process in ESRD patients treated with peritoneal dialysis. The study population consisted of 43 patients (19 F, 24 M) with a mean age of 50.6 +/- 13.4 years on PD for a mean period of 21.9 +/- 20.7 months. AoPWV was measured using two pressure transducers placed on the carotid and femoral arteries and connected to an automatic processor (Complion Colson AS, Paris, France). Serum levels of Tumor Necrosis Factor alpha (TNFalpha), interleukin 6 (IL-6) and plasma basic Fibroblast Growth Factor (bFGF) were measured with ELISA; C-reactive protein and fibrinogen with nephelometry. Serum lipid profile was also assessed. Blood pressure was measured in an outpatient department under standardized conditions. Mean aortic pulse wave velocity in the study population was 10.7 +/- 2.1 m/s. No difference in AoPWV was found between men and women. AoPWV correlated significantly with age (R = 0.41; p < 0.01) but not with time on dialysis. Positive relationship between AoPWV and body weight and BMI was shown (R = 0.31; p < 0.05 and R = 0.35; p < 0.05, respectively). AoPWV correlated significantly with systolic blood pressure (SBP), mean arterial pressure (MAP) and pulse pressure (PP) (R = 0.46, p < 0.005, R = 0.46, p < 0.005 and R = 0.43, p < 0.01, respectively). AoPWV correlated with serum IL-6 and plasma bFGF (R = 0.32, p < 0.05 and R = 0.4, p < 0.01; respectively). The correlation with serum CRP was borderline significant (p < 0.53). In multiple regression analysis age (beta 0.38; p < 0.005), plasma bFGF level (beta 0.3; p < 0.05), and systolic blood pressure (beta 0.29; p < 0.05) were independently associated with pulse wave velocity. Our results suggest that AoPWV values in patients on PD are associated with factors similar to those encountered in the general population. We suggest that increased aortic stiffening may also be related to the chronic inflammatory process in PD patients.

Relation of C-reactive protein to features of the metabolic syndrome in normal glucose tolerant, impaired glucose tolerant, and newly diagnosed type 2 diabetic subjects

OBJECTIVE

To determine the relationship between CRP levels and the components of MS in normal glucose tolerant (NGT), impaired glucose tolerant (IGT), and Type 2 diabetic subjects.

MATERIAL AND METHODS

A based cross-sectional population study was performed. Eligible subjects, men and non-pregnant women, 30 to 64 year of age, were randomly recruited. Subjects with acute or chronic diseases were excluded. Only newly diagnosed type 2 diabetic or hypertensive subjects were included. Disorders related to CRP increase, also were exclusion criteria. In accordance to WHO proposal, components of MS were: High Blood Pressure, Dyslipidemia, Obesity, and Microalbuminuria, and MS was defined, for the NGT, if at least two of the criteria were fulfilled and in addition the subject had insulin resistance. The MS in IGT and DM subjects was defined if at least two of the criteria were fulfilled.

RESULTS

CRP was significantly associated with MS for the NGT (Odds ratio -OR- 3.8, CI(95%) 1.6-14.8), IGT (OR 4.9, CI(95%) 1.2-15.5), and diabetes (OR 5.6, CI(95%) 1.9-10.2). For NGT, after adjustment for obesity, CRP was not longer associated with MS. After adjust for obesity and fasting glucose (FG), the relationship between CRP and MS for IGT was lost. Finally, after adjustment for obesity, FG, and microalbuminuria, CRP was not longer associated with MS for diabetic subjects.

CONCLUSIONS

This study show a significant relationship between CRP and MS which is maintained only by obesity in the NGT, by obesity and FG in the IGT, and by obesity, FG, and microalbuminuria in the newly diagnosed diabetic subjects.

An association between coronary artery calcification score, lipid profile, and selected markers of chronic inflammation in ESRD patients treated with peritoneal dialysis

BACKGROUND

Chronic uremia is considered a proinflammatory state associated with high cardiovascular morbidity and mortality. The aim of the present study is to evaluate the potential relationship between the prevalence of coronary artery calcification (CAC) and selected factors that may be involved in the process of atherogenesis (lipid profile, acute-phase reactants, growth factors, and cytokines).

METHODS

The study group consisted of 43 patients (19 women, 24 men) with a mean age of 50.6 +/- 13.4 years treated with peritoneal dialysis (PD) for a median period of 15 months (range, 2 to 96 months). Only patients with sinus rhythm were included. CAC score (CaSc) was measured using multirow spiral computed tomography (MSCT). As parameters of lipid profile, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides were assayed. C-reactive protein (CRP) and fibrinogen represented the level of acute-phase activation. Proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-alpha]), leptin, and basic fibroblast growth factor (bFGF) also were measured.

RESULTS

Median CaSc equaled 17.9 Agatston units (range, 0 to 5,502 Agatston units). No calcification was detected in 20 subjects (46.5%; CaSc < 10 Agatston units). CaSc correlated with age (R = 0.57; P < 0.0001), body mass index (R = 0.42; P < 0.005), and serum leptin (R = 0.3; P < 0.05) and CRP levels (R = 0.38; P < 0.05). The correlation with PD therapy duration was borderline statistically significant (P = 0.063). Patients with the greatest values for CaSc (> 400 Agatston units) were characterized by significantly greater levels of IL-6, bFGF, and CRP compared with subjects with a CaSc less than 10 Agatston units (P < 0.05 for all). Patients with history of coronary artery disease (CAD) had significantly greater CaSc values (median, 778.6 versus 3.3 Agatston units; P < 0.001) compared with those without CAD. Serum triglyceride levels were significantly greater and HDL cholesterol levels were significantly lower in patients with CAD. The first group also was characterized by significantly greater serum TNF-alpha (P < 0.01) and CRP levels (P < 0.005). In multiple regression analysis, only age was independently associated with CaSc (beta = 0.45; P = 0.002).

CONCLUSION

Our results may suggest an association between CAC and chronic inflammation activity in the mentioned group of patients. To our knowledge, this is the first study reporting the prevalence of CAC in PD patients using the MSCT method. The association between CaSc results and classic, as well as inflammatory, risk factors for CAD found in this study should be interpreted with caution because of its method limitations (cross-sectional design, heterogeneity of study population, and small number of studied patients).

Homocysteine and C-reactive protein levels in haemodialysis patients

BACKGROUND

Mild to moderate hyperhomocysteinemia is very common among patients undergoing haemodialysis. There is sufficient evidence that hyperhomocysteinemia is an independent risk factor for cardiovascular and or atheromatous disease in end stage renal failure patients. Vitamin supplementation such as vitamin B6, B12 or folate has been proposed to correct this metabolic disturbance and it is to be proved if this intervention benefit these patients, but there is no agreement whether oral folate supplementation is capable to normalize homocysteine levels in end stage renal failure patients.

METHODS

In 53 patients, undergoing haemodialysis, homocysteine levels (Hcy), folate, vitamin B12, ferritin and C-reactive protein (CRP) were estimated before and after dialysis, without folate supplementation. Thirty voluntary blood donors were used as controls to compare homocysteine levels. After four weeks of oral folate supplementation (10 mg/24 hours) the levels of homocysteine, serum folate and intra-erythrocyte folate were estimated again. Eighteen months later the survival rate of our patients was recorded and analyzed in relation to Hcy and CRP levels.

RESULTS

The results showed that haemodialysis patients exhibited, almost, fourfold higher homocysteine levels than controls (27.39 +/- 11.54 vs 7.38 +/- 3.5, t = -8.2, p = 0.000000). Folate levels, vitamin B12 and CRP increase significantly after haemodialysis where as homocysteine levels decrease (Hcy1 vs. Hcy2: z = 2.08, p = 0.03). Fourteen (14) patients suffered from coronary heart disease (CHD) and they exhibited the higher levels of homocysteine (Hcy1 vs. CHD: z = -3.4, p = 0.0006). All estimations performed revealed a negative correlation between homocysteine levels and plasma or intra-erythrocyte folate. No other variable exhibited any significant influence upon homocysteine levels. After folate supplementation homocysteine levels in the whole number of patients were unchanged (Hcy(before) vs. Hcy(after): 27.39 +/- 11.54 vs. 26.95 +/- 8.22, z = 0.3, p = 0.7, NS). When patients with homocysteine levels higher than 24 micromol/L were selected, a significant decrease was observed (34.77 +/- 9.32 vs. 30.0 +/- 8.05, z = 2.09, p = 0.02). Forty-two patients were treated with erythropoietin for their anemia and we found a positive correlation between C-reactive protein levels and rhu-Epo dose (CRP vs. Epo: r = 0.45, p = 0.002). Homocysteine levels did not exhibit any significant influence upon short-term survival (U = -0.37, p = 0.3, NS) where as CRP levels exhibit a significant influence upon short-term survival (U = 2.15, p = 0.005).

CONCLUSIONS

Homocysteine levels in haemodialysis patients are fourfold higher than healthy controls. Folate, vitamin B12 and CRP increases significantly after dialysis. Patients with coronary heart disease exhibit the highest levels of homocysteine. The homocysteine levels are inversely related with the folate levels. The exogenous folate supplementation increase the serum folate levels but decreases homocysteine only in patients with higher than mild hyperhomocysteinemia. Hcy doesn't exert any significant effect upon the short-term survival of the haemodialysis patients but CRP level is a god predictor of the short-term survival of these patients.

Moderate alcohol consumption reduces plasma C-reactive protein and fibrinogen levels; a randomized, diet-controlled intervention study

OBJECTIVE

To evaluate the effect of moderate alcohol consumption on the acute phase proteins C-reactive protein and fibrinogen.

DESIGN

Randomized, diet-controlled, cross-over study.

SETTING

The study was performed at TNO Nutrition and Food Research, Zeist, The Netherlands.

SUBJECTS

Ten middle-aged men and 10 postmenopausal women, all apparently healthy, non-smoking and moderate alcohol drinkers, were included. One women dropped out because of a treatment-unrelated cause. The remaining 19 subjects finished the experiment successfully.

INTERVENTIONS

Men consumed four glasses and women consumed three glasses of beer or no-alcohol beer (control) with evening dinner during two successive periods of 3 weeks. The total diet was supplied to the subjects and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period to compensate for possible carry-over effects.

RESULTS

Plasma C-reactive protein and fibrinogen levels were decreased by 35% (P=0.02) and 12.4% (P< or =0.001), respectively, after 3 weeks' consumption of beer, as compared to no-alcohol beer consumption.

CONCLUSIONS

Moderate alcohol consumption significantly decreased plasma C-reactive protein and fibrinogen levels. An anti-inflammatory action of alcohol may help explain the link between moderate alcohol consumption and lower cardiovascular disease risk.

SPONSORSHIP

Dutch Foundation for Alcohol Research (SAR).

Relevance of C-reactive protein levels in peritoneal dialysis patients

BACKGROUND

C-reactive protein (CRP) levels are increased in 30 to 50% of dialysis patients and predict cardiovascular morbidity and mortality. It is usually considered that raised CRP levels reflect underlying atherosclerosis. However, many patients may have clinically apparent cardiovascular disease without raised CRP levels. This study was designed to assess both the risk factors for high CRP levels and the usefulness of the test as a marker of clinically apparent coronary artery disease (CAD), peripheral vascular disease (PVD) and the presence of ongoing infections/inflammatory disorders (INF-INFL) in peritoneal dialysis patients.

METHODS

A chart review of 190 prevalent peritoneal dialysis patients was performed. CRP, albumin, ferritin, erythropoietin (EPO) dose and resistance, Kt/V, and residual renal function values were obtained and a history or presence of cardiovascular disease (CAD, PVD) and presence of INF-INFL recorded. Data were analyzed by Chi-square, Spearman correlation and logistic regression.

RESULTS

A total of 31% of patients had a raised CRP. INF-INFL was highly predictive of raised CRP levels (OR 16.97; 95% CI 5.41 to 53.14, P=0.000), whereas CAD and PVD either singly or in combination had no such association. The sensitivity/specificity for CRP as a test for INF-INFL was 83/77%. For CAD and PVD, the sensitivities were less than 40% and specificities 70%. Increased CRP values were more common in females but not in diabetics. Weak linear correlations existed between CRP levels and albumin, ferritin and residual renal function (r=-0.212, 0.228 and -0.163 respectively, P < 0.02). By regression analysis, INF-INFL predicted high CRP levels, but CAD and PVD did not. The majority of patients (57%) with high CRP had no identifiable cause; 40% of these patients had subsequent or previous normal CRP values. High transport status predicted high CRP levels (OR 7.28; 95% CI 1.417 to 37.36, P=0.006).

CONCLUSIONS

The majority of elevated CRP levels in peritoneal dialysis patients occur without an obvious cause. Clinically apparent cardiovascular disease does not predict high CRP levels. CRP levels vary over time in the same patient, from normal to high or vice versa, for no obvious reason. Sources of inflammation other than CAD, PVD and clinically obvious INF-INFL in peritoneal dialysis patients remain to be identified.

Cardiovascular disease determinants in chronic renal failure: clinical approach and treatment

INTRODUCTION

Cardiovascular disease (CVD), as the leading cause of morbidity and mortality in patients on renal replacement therapy (RRT), has a central role in everyday nephrological practice.

METHODS

Consensus was reached on key points relating to the clinical approach and treatment of the main cardiovascular risk factors in RRT patients (hypertension, anaemia, hyperparathyroidism, dyslipidaemia, new emerging risk factors). In addition, the role of convective treatments on cardiovascular outcomes was examined.

RESULTS

Hypertension should be managed by aiming at blood pressure values of < or =140/90 mmHg (< or =160/90 mmHg in the elderly), firstly by ensuring target dry body weight is achieved. No single class of drug has proved superior to others in RRT patients, provided that the blood pressure target is achieved, although ACE inhibitors have shown specific organ protection in high-risk patients (HOPE study) and are well tolerated. Anaemia should be managed by using erythropoietin and iron supplements, aiming at haemoglobin levels of 12 g/dl and keeping serum ferritin levels < 500 ng/ml. The management of hyperparathyroidism is currently unsatisfactory, as calcium supplements have the potential to increase cardiovascular calcification. While awaiting new calcium- and aluminium-free phosphate binders, it is essential to ensure dialysis adequacy. Clinical studies are in progress to assess the real impact of lipid-lowering drugs in RRT. In the meantime, serum LDL-cholesterol < 160 mg/dl and triglycerides < 500 mg/dl may be desirable targets. The impact of new emerging risk factors (inflammation and chronic infection, hyperhomocysteinaemia, metabolic waste-product accumulation) and their proper management are still under research. Convective dialysis treatments may confer some degree of protection from dialysis-related amyloidosis and mortality, but clinical data on this important issue are still controversial and no definitive conclusions can be drawn at present.

CONCLUSION

CVD prevention and treatment is a great challenge for the nephrologist. Achieving evidence-based consensus can help in encouraging the implementation of best clinical practice in line with the progress of current knowledge.