Inflammation is associated with carotid atherosclerosis in dialysis patients. Creed Investigators. Cardiovascular Risk Extended Evaluation in Dialysis Patients

Parenteral iron compounds sensitize mice to injury-initiated TNF-alpha mRNA production and TNF-alpha release

Intravenous Fe is widely used to treat anemia in renal disease patients. However, concerns of potential Fe toxicity exist. To more fully define its spectrum, this study tested Fe's impact on systemic inflammation following either endotoxemia or the induction of direct tissue damage (glycerol-mediated rhabdomyolysis). The inflammatory response was gauged by tissue TNF-alpha message expression and plasma TNF-alpha levels. CD-1 mice received either intravenous Fe sucrose, -gluconate, or -dextran (FeS, FeG, or FeD, respectively; 2 mg), followed by either endotoxin (LPS) or glycerol injection 0-48 h later. Plasma TNF-alpha was assessed by ELISA 2-3 h after the LPS or glycerol challenge. TNF-alpha mRNA expression (RT-PCR) was measured in the kidney, heart, liver, lung, and spleen with Fe +/- LPS treatment. Finally, the relative impacts of intramuscular vs. intravenous Fe and of glutathione (GSH) on Fe/LPS- induced TNF-alpha generation were assessed. Each Fe preparation significantly enhanced LPS- or muscle injury-mediated TNF-alpha generation. This effect was observed for at least 48 h post-Fe injection, a time at which plasma iron levels were increased by levels insufficient to fully saturate transferrin. Fe did not independently increase plasma TNF-alpha or tissue mRNA. However, it potentiated postinjury-induced TNF-alpha mRNA increments and did so in an organ-specific fashion (kidney, heart, and lung; but not in liver or spleen). Intramuscular administration, but not GSH treatment, negated Fe's ability to synergize LPS-mediated TNF-alpha release. We conclude 1) intravenous Fe can enhance TNF-alpha generation during LPS- or glycerol-induced tissue damage; 2) increased TNF-alpha gene transcription in the kidney, heart, and lung may contribute to this result; and 3) intramuscular administration, but not GSH, might potentially mitigate some of Fe's systemic toxic effects.

Carotid atherosclerosis in chronic renal failure-the central role of increased plaque burden

Studies on carotid artery atherosclerosis have been performed in order to understand the high risk for cardiovascular disease in chronic renal failure (CRF). The purpose of this study was to evaluate the extent and nature of carotid artery atherosclerosis in patients with CRF. Of the 135 patients with CRF (52 +/- 11 years), 58 had moderate to severe predialysis CRF (PR), 36 were on dialysis treatment (DI), and 41 were renal transplant recipients (TR). In addition, 58 control subjects (CO) were examined. Common carotid artery intima-media thickness (IMT), plaque prevalence, plaque score, and stiffness index beta were determined. Furthermore, plaque calcification and internal carotid artery stenoses were classified. Plaque prevalence (PR 64%, DI 61%, TR 51%, CO 28%; P < 0.001) and plaque score (PR 3.3 +/- 4.3, DI 3.0 +/- 3.4, TR 2.5 +/- 3.2, CO 0.8 +/- 1.7 mm; P < 0.001) were significantly greater in the CRF patient groups compared to the controls, whereas no difference in IMT was noted between the study groups. The prevalences of plaque calcification and internal carotid artery stenoses were higher among the CRF patient groups. In addition, the stiffness index beta was higher in the CRF patient groups. The present study shows that the characteristic alterations of the carotid arteries in CRF include increased plaque burden, calcification and increased arterial stiffness.

Chlamydia pneumoniae and Atherosclerosis: No Way-Out or Long Way?

Recently, Chlamydia pneumoniae is the microorganism frequently implicated in the infection-based inflammatory atherogenous hypothesis. Although in vitro experimental data and initial sero-epidemiologic, pathology-based studies and antibiotic trials supported this interesting hypothesis, later data are conflicting. Some confounding factors are the causes of uncertainty; lacking of standard methods for C. pneumoniae detection, co-existence of other atherosclerotic risk factors and anti-inflammatory effects of antibiotics used in clinical trials seem to be the principal ones. Standardization of methodology used, antibiotic trials with a different orientation-design and a vaccine preparation that eventually will be tested in clinical trials with a long follow-up, should provide a definite answer regarding the probability C. pneumoniae to be a main, a secondary or an irrelevant factor to atherosclerosis. Studies linking C. pneumoniae to inflammation and accelerated atherosclerosis in renal failure patients are accumulated but limitations are similar to the above mentioned.

Inflammation and nutrition in renal insufficiency

Protein-energy malnutrition (PEM) and inflammation are common in patients with chronic kidney disease (CKD) and worsen as the CKD progresses toward the end-stage renal disease (ESRD). These conditions are major predictors of poor clinical outcome in kidney failure, as reflected by a strong association between hypoalbuminemia and cardiovascular disease (CVD). It has been suggested that inflammation is the cause of both PEM and CVD and, hence, the main link among these conditions, but these hypotheses are not well established. Increased release or activation of inflammatory cytokines, such as interleukin-6 or tumor necrosis factor alpha, may suppress appetite, cause muscle proteolysis and hypoalbuminemia, and may be involved in atherogenesis. Increasing serum levels of proinflammatory cytokines caused by reduced renal function, volume overload, oxidative or carbonyl stress, decreased levels of antioxidants, increased susceptibility to infection in uremia, and the presence of comorbid conditions may lead to inflammation in CKD patients. In hemodialysis patients, the exposure to dialysis tubing and dialysis membranes, poor quality of dialysis water, back-filtration or back-diffusion of contaminants, and foreign bodies in dialysis access maybe additional causes of inflammation. Similarly, episodes of overt or latent peritonitis, peritoneal dialysis (PD) catheter and its related infections, and constant exposure to PD solution may contribute to inflammation in these patients. The degree to which PEM in dialysis patients is caused by inflammation is not clear. Because both PEM and inflammation are strongly associated with each other and can change many nutritional measures and outcome concurrently in the same direction, the terms malnutrition-inflammation complex syndrome (MICS) and/or malnutrition-inflammation-atherosclerosis (MIA) have been suggested to denote the important contribution of both of these conditions to poor clinical outcome. Maintenance dialysis patients who are underweight or who have low serum levels of cholesterol, creatinine, or homocysteine may be suffering from the MICS/MIA and its subsequent poor outcome. Consequently, obesity and hypercholesterolemia may appear protective, which is known as reverse epidemiology. Although MICS/MIA may have a significant contribution in reversing the traditional CVD risk factors in dialysis patients, it is not clear whether PEM or inflammation and their complications can be effectively managed in CKD and ESRD or whether their management improves clinical outcome.

Chlamydial infection and progression of carotid atherosclerosis in patients on regular haemodialysis

BACKGROUND

Recent findings have suggested a possible contribution of chlamydial infection to the pathogenesis of atherosclerosis in the general population. However, the role that chlamydial antibody status plays in atherosclerosis generation in haemodialysis (HD) patients remains uncertain.

METHODS

We measured carotid artery intima medial thickness (IMT) over 4 years in 100 HD subjects (age: 58+/-10 years; time on HD: 13+/-7 years; male/female: 67/33) and examined potential associations between Chlamydia pneumoniae (Cp) antibody seropositivity and changes in carotid artery IMT.

RESULTS

During 4 years, carotid artery IMT increased significantly from 0.62+/-0.13 to 0.73+/-0.12 mm (P< 0.01). IMT progression was significantly and positively correlated with age (r = 0.37, P<0.01), log-transformed C-reactive protein (CRP; r = 0.33, P<0.01) and log-transformed interleukin-6 (IL-6; r = 0.22, P<0.04), but inversely correlated with blood creatinine (r = -0.36, P<0.01) and albumin (r = -0.24, P<0.02). IMT increases were more prominent in patients positive for IgA antibodies (0.039+/- 0.022 mm/year, n = 52) compared with those without IgA antibodies (0.025+/-0.032 mm/year, n = 48) (P<0.01). IgA seropositivity did not accelerate IMT progression in patients with increased CRP (>0.11 mg/dl, n = 53), but significantly increased IMT to a greater extent in IgA-positive subjects than in IgA-negative subjects having lower CRP (</=0.11 mg/dl, n = 47) (0.017+/-0.024 vs 0.034+/- 0.021 mm/year; P = 0.01). Multivariate regression analysis revealed that serum creatinine, log-transformed CRP and IgA Cp seropositivity were independent risk factors for IMT progression (P<0.01). In contrast, IgG Cp antibody did not affect IMT progression or carotid plaque formation.

CONCLUSIONS

IMT progression is associated with inflammation and malnutrition. In addition, persistent chlamydial infection may be associated with IMT progression, but only in HD patients having low blood CRP.

Association between white blood cell count and carotid arteriosclerosis in Japanese smokers

Recent studies have shown the relationship between general inflammatory markers and ischemic heart and cerebrovascular diseases. Here we have investigated the potential association between the circulating white blood cell count and carotid arteriosclerosis in apparently healthy individuals. Between 1994 and 1998, 3455 subjects who had undergone general health screening tests including carotid ultrasonography were enrolled in this study. The intertertile cutoff points for the white blood cell count were 5.1 x 10(3) and 6.4 x 10(3) microL(-1) in the male subjects and 4.6 x 10(3) and microL(-1) in the female subjects. The prevalence of carotid plaque in the first (lowest), the second, and the third tertiles was 19, 28, and 28% in the male subjects, respectively (P < 0.0001), and 10, 15, and 14% in the female subjects, respectively (n.s.). The multivariate analysis showed that the male subjects in the second and third tertiles had increased risk for carotid plaque with odds ratios of 1.54 (95% CI 1.18-2.01) and 1.47 (95% CI 1.11-1.95), respectively, compared to those in the first tertile. When male subjects were subdivided according to their smoking status, the association between white blood cell count and carotid plaque was significant in those who smoked, but not in those who had never smoked. These data suggested the possible association between the circulating white blood cell count and formation of carotid plaque in male smokers, but not in male never smokers or in females, in an apparently healthy Japanese population.

Parenteral iron nephrotoxicity: Potential mechanisms and consequences1

BACKGROUND

Parenteral iron administration is a mainstay of anemia management in renal disease patients. However, concerns of potential iron toxicity persist. Thus, this study was conducted to more fully gauge iron toxicologic profiles and potential determinants thereof.

METHODS

Isolated mouse proximal tubule segments (PTS) or cultured proximal tubular [human kidney (HK-2)] cells were exposed to four representative iron preparations [iron sucrose (FeS), iron dextran (FeD), iron gluconate (FeG), or iron oligosaccharide (FeOS)] over a broad dosage range (0, 30 to 1000 microg iron/mL). Cell injury was assessed by lactate deyhdrogenase (LDH) release, adenosine triphosphate (ATP) reductions, cell cytochrome c efflux, and/or electron microscopy. In vivo toxicity (after 2 mg intravenous iron injections) was assessed by plasma/renal/cardiac lipid peroxidation [malondialdehyde (MDA)], renal ferritin (protein)/heme oxygenase-1 (HO-1) (mRNA) expression, electron microscopy, or postiron injection PTS susceptibility to attack.

RESULTS

In each test, iron evoked in vitro toxicity, but up to 30x differences in severity (e.g., ATP declines) were observed (FeS > FeG > FeD = FeOS). The in vitro differences paralleled degrees of cell (HK-2) iron uptake. In vivo correlates of iron toxicity included variable increases in renal MDA, ferritin, and HO-1 mRNA levels. Again, these changes appeared to parallel in vivo (glomerular) iron uptake (seen with FeS and FeG, but not with FeD or FeOS). Iron also effected in vivo alterations in proximal tubule cell homeostasis, as reflected by the "downstream" emergence of tubule resistance to in vitro oxidant attack.

CONCLUSION

Parenteral iron formulations have potent, but highly variable, cytotoxic potentials which appear to parallel degrees of cell iron uptake (FeS > FeG >> FeD or FeOS). That in vitro injury can be expressed at clinically relevant iron concentrations, and that in vivo glomerular iron deposition/injury may result, suggest caution is warranted if these agents are to be administered to patients with active renal disease.

Parenteral iron therapy exacerbates experimental sepsis Rapid Communication

BACKGROUND

Catalytic iron can potentiate systemic inflammation via its pro-oxidant effects. This raises the possibility that parenteral iron administration might exacerbate a concomitant septic state. This study sought to experimentally test this hypothesis.

METHODS

Male CD-1 mice were subjected to experimental sepsis via intraperitoneal injection of heat-killed Escherichia coli +/- concomitant intravenous iron sucrose (Venofer; 2 mg). Nonseptic mice +/- iron therapy served as controls. Plasma tumor necrosis factor-alpha (TNF-alpha) levels were assessed 2 hours postinjections (serving as an inflammatory marker). Oxidative stress was gauged in heart or kidney tissue (at either 4 or 24 hours) by heme oxygenase-1 (HO-1) mRNA or protein levels. Overall sepsis severity was assessed by morbidity/mortality rates (at 24 hours).

RESULTS

Iron alone or sepsis alone each induced oxidant stress in heart and kidney (HO-1 mRNA/protein increases). When iron and E. coli were coadministered, additive or synergistic HO-1 mRNA/protein increments resulted. Iron injection alone only slightly raised TNF-alpha levels (from 0 to 2.3 pg/mL; P= 0.01). However, iron approximately doubled the TNF-alpha increments which arose from the septic state (1400 --> 2600 pg/mL). Neither sepsis alone, nor iron alone, induced any mortality and no mice became moribund (0/24 mice). However, when iron + sepsis were combined, approximately 60% of mice either died (5/12) or developed a moribund (2/12) state (P= 0.005).

CONCLUSION

Parenteral iron administration can induce systemic oxidative stress and modest TNF-alpha release. However, when iron is given during experimental sepsis, profound increases in both processes, and approximately 60% mortality, result. Given that renal failure patients have decreased antioxidant defenses and intermittently develop bacteremia, the potential for parenteral iron therapy to exacerbate clinical sepsis needs to be addressed.

Does the endothelial function change in renal transplant patients with longer duration of exposure and with higher cumulative doses of cyclosporine?

OBJECTIVE

Administration of cyclosporine (CsA) is one potential cause of endothelial dysfunction in renal transplant patients. We sought to investigate endothelial functional changes with respect to the cumulative dose and duration of exposure to CsA.

METHODS

Sixty-six renal recipients and 25 healthy controls were included in the study. The recipients were classified according to their time of CsA exposure: group 1 (0 to 36 months); group 2 (36 to 72 months); and group 3 (over 72 months). Endothelial function of the brachial artery was evaluated using high-resolution vascular ultrasound. Endothelium-dependent and -independent vasodilatation (EDD and EID, respectively) were assessed by assessing the responses to reactive hyperemia and using sublingual isosorbide dinitrate (ISDN), respectively.

RESULTS

There were no statistically significant differences between the groups with regard to their demographic, clinical, and most biochemical characteristics. Baseline measurements of the diameter of the brachial artery were similar in all groups. The values of mean brachial artery EDD and EID responses in groups 1, 2, and 3 were less than those in the control group (P < .05, P < .05, and P < .05, respectively). Mean brachial artery EDD and EID in group 1 were significantly impaired compared to groups 2 and 3 (for EDD: P < .05 and P < .05, respectively; for EID: P < .05 and P < .05, respectively). In contrast there was no difference between groups 2 and 3 with respect to these parameters. There were mild to moderate positive correlations between the cumulative doses of CsA and EDD and EID (r = .26 and r = .52, P < .05, respectively).

CONCLUSION

Endothelial dysfunction was more prominent in the first 36-month period than later despite the longer exposure to and higher cumulative doses of CsA. This finding may reflect an extended effect of the uremic state on endothelial function or more intense doses of CsA in early posttransplant period.

SEROLOGIC EVIDENCE OF CHLAMYDIA PNEUMONIAE INFECTION AS A LONG-TERM PREDICTOR OF CARDIOVASCULAR DEATH IN RENAL TRANSPLANT RECIPIENTS

BACKGROUND

Cardiovascular disease is the main cause of death with a functioning graft in renal transplant recipients. Elevated levels of C-reactive protein (CRP) and evidence of chronic Chlamydia pneumoniae infection have been linked to cardiovascular disease and survival in patients with normal renal function and patients with end-stage renal disease on dialysis. So far, no such data have been available in renal transplant recipients.

METHODS

CRP, immunoglobulin (Ig)G and IgA antibodies to C. pneumoniae, and classic risk factors were compiled in 143 patients who underwent renal transplantation between January 1989 and April 1991. Samples were collected at transplantation, 1 year later, and at study end. Cardiovascular disease, death, and graft loss were documented during follow-up.

RESULTS

A total of 44 patients died during a mean follow-up of 10 years. Cardiac events were responsible for 37% of deaths. Age, gender, number of antihypertensive drugs, and seropositivity for IgG and IgA antibodies to C. pneumoniae, but not CRP levels, were significantly associated with cardiac death. C. pneumoniae serology and CRP levels, however, did not influence graft survival. Age, presence of diabetes, calcium phosphorus ion product, number of antihypertensive drugs, serum creatinine at 1 year, and presence of chronic rejection were all negatively correlated with graft survival.

CONCLUSIONS

Serologic evidence of chronic C. pneumoniae infection is associated with mortality as the result of cardiovascular disease in renal transplant recipients. CRP serum levels do not predict cardiac death in renal transplant recipients, in contrast with patients with normal renal function and patients on dialysis.

Malnutrition-inflammation complex syndrome in dialysis patients: causes and consequences

Protein-energy malnutrition (PEM) and inflammation are common and usually concurrent in maintenance dialysis patients. Many factors that appear to lead to these 2 conditions overlap, as do assessment tools and such criteria for detecting them as hypoalbuminemia. Both these conditions are related to poor dialysis outcome. Low appetite and a hypercatabolic state are among common features. PEM in dialysis patients has been suggested to be secondary to inflammation; however, the evidence is not conclusive, and an equicausal status or even opposite causal direction is possible. Hence, malnutrition-inflammation complex syndrome (MICS) is an appropriate term. Possible causes of MICS include comorbid illnesses, oxidative and carbonyl stress, nutrient loss through dialysis, anorexia and low nutrient intake, uremic toxins, decreased clearance of inflammatory cytokines, volume overload, and dialysis-related factors. MICS is believed to be the main cause of erythropoietin hyporesponsiveness, high rate of cardiovascular atherosclerotic disease, decreased quality of life, and increased mortality and hospitalization in dialysis patients. Because MICS leads to a low body mass index, hypocholesterolemia, hypocreatininemia, and hypohomocysteinemia, a "reverse epidemiology" of cardiovascular risks can occur in dialysis patients. Therefore, obesity, hypercholesterolemia, and increased blood levels of creatinine and homocysteine appear to be protective and paradoxically associated with a better outcome. There is no consensus about how to determine the degree of severity of MICS or how to manage it. Several diagnostic tools and treatment modalities are discussed. Successful management of MICS may ameliorate the cardiovascular epidemic and poor outcome in dialysis patients. Clinical trials focusing on MICS and its possible causes and consequences are urgently required to improve poor clinical outcome in dialysis patients.

Carotid atherosclerosis is associated with inflammation, malnutrition and intercellular adhesion molecule-1 in patients on continuous ambulatory peritoneal dialysis

BACKGROUND

Recent evidence suggests that endothelial cell adhesion molecules may participate in the initiation and progression of atherosclerotic vascular damage. The aim of the present report was to investigate serum intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin concentrations and their probable association with atherosclerotic disease in patients on continuous ambulatory peritoneal dialysis (CAPD).

METHODS

Sixty-three CAPD patients and 40 age- and sex-matched apparently healthy normotensive controls participated in the study. Atherosclerotic disease in both groups was assessed by measuring the intima-media thickness (IMT) and plaque score of the common carotid arteries using an ultrasound scanner.

RESULTS

Compared with controls, CAPD patients had significantly increased IMT and plaque score values (P<0.001 and P<0.0001, respectively), as well as serum ICAM-1, VCAM-1 and E-selectin concentrations (P<0.0001, P<0.0001 and P<0.05, respectively). In univariate analyses, IMT values were significantly correlated with age, systolic blood pressure (BP), logCRP, fibrinogen, albumin and ICAM-1 levels (P = 0.001, P = 0.04, P = 0.01, P = 0.04, P = 0.02 and P = 0.002, respectively). Multivariate analysis showed that ICAM-1 levels were a strong independent correlate of IMT (P = 0.005). Serum albumin also remained independently associated with IMT values (P = 0.03). Plaque score values were significantly correlated with age, systolic BP and fibrinogen (P = 0.002, P = 0.04 and P = 0.01, respectively). Multivariate analysis showed that fibrinogen concentrations were a significant independent contributor to plaque score values (P = 0.002). Adhesion molecule concentrations did not show any relation with plaque score either on univariate or multivariate analyses.

CONCLUSIONS

In CAPD patients, carotid atherosclerosis is associated with markers of inflammation, malnutrition and circulating levels of adhesion molecule ICAM-1. Hypoalbuminaemia and ICAM-1 appear independently related with atherogenesis but the mechanisms supporting these associations remain to be identified.

Chlamydia pneumoniae and atherosclerosis following carotid endarterectomy

BACKGROUND

Seroepidemiological studies have shown an association between raised antibody titres against Chlamydia pneumoniae, and carotid atherosclerosis or stroke. However, direct evidence for a causal link between arterial infection with C. pneumoniae and carotid disease remains weak. We hypothesized that long-term follow-up of patients with pathologically-proven arterial C. pneumoniae infection might provide further insight into the role of C. pneumoniae in carotid atherosclerosis.

METHODS

We followed a cohort of 70 carotid endarterectomy patients for ipsilateral restenosis, contralateral progression, and all-cause mortality (four year median follow-up period). All patients had presence or absence of C. pneumoniae in their carotid plaques documented by immunohistochemistry after endarterectomy. A survival function was generated and the log-rank test was used to assess the difference in survival between subjects with and without documented chlamydial infection in their plaque.

RESULTS

Baseline demographic and cardiovascular risk factors were similar between the two groups, and survival analysis demonstrated no difference (p>0.05) in all-cause mortality, or all-cause mortality combined with restenosis and progression.

CONCLUSIONS

Our data finds no causal role for C. pneumoniae in restenosis or progression of carotid disease or mortality in this patient population with advanced carotid atherosclerosis.

Association of interleukin-6 -174G/C promoter polymorphism with hypertension and left ventricular hypertrophy in dialysis patients

BACKGROUND

Gene polymorphisms of proinflammatory cytokines, such as interleukin-6 (IL-6) and the chemokine receptor CX3CR1, have been found in association with cardiovascular disease in the general population. In dialysis patients, in whom the prevalence of cardiovascular comorbidity is strikingly high, these polymorphisms have not been investigated.

METHODS

The -174G/C polymorphism of the IL-6 gene and the chemokine receptor CX3CR1 polymorphisms 249V/I and 280T/M were examined for their association with cardiovascular abnormalities in a cohort of 161 patients with end-stage renal disease (ESRD) treated by hemodialysis. Arterial blood pressure, electrocardiogram (ECG) ischemic changes, and left ventricular mass index (LVMI) were the parameters examined for the association study. The control group was made up of 169 healthy subjects.

RESULTS

We found that for both IL-6 and chemokine receptor, genotype frequency and allelic distribution in both ESRD patients and controls were comparable. The genetic association study showed that in the whole group of dialysis patients, individuals with GC + CC genotype for the -174G/C polymorphism had a higher diastolic blood pressure (P = 0.008) and LVMI (P = 0.026) than GG homozygotes. The prevalence of left ventricular hypertrophy (LVH) in the former group was 58.6% vs. 39.2% in the latter (P = 0.02). The same analysis limited to diabetic patients in dialysis, showed that the prevalence of LVH in those with CG + CC genotype was 87.5% vs. 36.3% in those with GG genotype (P = 0.02). In diabetic patients, lower levels of serum albumin was found in the GC + CC genotypic group than in GG subjects; 34.63 +/- 5.18 g/L vs. 41.75 +/- 4.79 g/L (P = 0.003).

CONCLUSION

These data demonstrate an association between the IL-6 promoter polymorphism -174G/C and high blood pressure and LVH in hemodialysis patients, especially those with diabetes. The results strengthen the hypothesis that chronic inflammation is a mechanism of cardiovascular damage in dialysis patients and the role played by the IL-6 system in this mechanism.

Risk factors for aortic atherosclerosis determined by transesophageal echocardiography in patients with CRF

BACKGROUND

The significance of various risk factors for cardiovascular disease (CVD) in the pathogenesis of atherosclerosis in patients with chronic renal failure (CRF) is, to a great deal, unresolved. The high risk for CVD in patients with CRF may be caused by the high prevalence of recognized risk factors for CVD or by factors characteristic of CRF in these patients. In this prospective cross-sectional study, we examined risk factors for thoracic aortic atherosclerosis in a population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients.

METHODS

Of 118 patients, 52 patients had moderate to severe predialysis CRF, 32 patients were on dialysis treatment, and 34 patients were renal transplant recipients. Mean age was 52 +/- 12 years, and 35 patients (30%) had diabetes. Multiplane transesophageal echocardiography (TEE) was performed using local anesthesia.

RESULTS

Large aortic plaques (LAPs; > or = 3.0 mm in diameter) were found in 39 patients (33%). In univariate analysis, age, duration of hypertension, pulse pressure, low diastolic blood pressure, elevated fibrinogen level, C-reactive protein level, total cholesterol level, low-density lipoprotein cholesterol level, and duration of dialysis or a functioning renal transplant were significantly associated (P < 0.05) with LAP. In multivariate analysis, age, duration of hypertension, and total cholesterol level were associated with LAP.

CONCLUSION

Results of the present TEE study suggest that in addition to duration of hypertension and renal disease, hypercholesterolemia has a role in the pathogenesis of atherosclerosis in patients with CRF.

Chlamydia pneumoniae, overall and cardiovascular mortality in end-stage renal disease (ESRD)

BACKGROUND

Cross-sectional and retrospective studies suggest that Chlamydia pneumoniae infection may contribute importantly to the high cardiovascular risk of patients with end-stage renal disease (ESRD).

METHODS

We investigated the relationship between C. pneumoniae serology and survival and incident fatal cardiovascular events in a cohort of 227 ESRD patients (follow-up of 39 +/- 20 months).

RESULTS

On univariate Cox regression analysis patients with anti-C. pneumoniae immunogloblulin A (IgA) titer > or = 1:16 had a significantly higher risk of all-cause and cardiovascular mortality when compared to patients without IgA antibodies. However, after data adjustment for age and smoking, the hazard ratio (HR) decreased substantially and became largely nonsignificant. Adjustments for traditional and nontraditional risk factors further decreased the independent association of IgA anti-C. pneumoniae and these outcomes (all-cause mortality HR, 1.08; 95% CI, 0.68 to 1.72; P = 0.74; cardiovascular mortality HR, 1.07; 95% CI, 0.60 to 1.89; P = 0.83). A similar loss of prognostic power was observed for IgG anti-C. pneumoniae so that in fully adjusted models the HRs were very close to those observed for IgA anti-C. pneumoniae (all-cause mortality HR, 1.13; 95% CI, 0.68 to 1.86, P = 0.64; cardiovascular mortality HR, 1.10; 95% CI, 0.60 to 2.00; P = 0.77).

CONCLUSION

C. pneumoniae seropositivity is associated to shorter survival and incident fatal cardiovascular events in patients with ESRD but these associations are in large part attributable to the link between C. pneumoniae and well-established, traditional risk factors. It is highly unlikely that C. pneumoniae infection is a major risk factor in patients with ESRD.

Fibrinogen, mortality and incident cardiovascular complications in end-stage renal failure

OBJECTIVE

Fibrinogen is an established predictor of cardiovascular events in the general population but the relationship between fibrinogen, mortality and incident cardiovascular complications has been very little investigated in patients with end-stage renal disease (ESRD).

DESIGN AND SUBJECTS

We investigated the relationship between fibrinogen and all cause mortality and cardiovascular outcomes in a prospective cohort study in 192 patients on chronic haemodialysis treatment (follow-up: 34 +/- 16 months).

RESULTS

Fibrinogen was significantly higher in patients who died during the follow-up than in those who survived. Similarly, fibrinogen was higher in patients who had fatal or nonfatal cardiovascular events than in event free patients. On multivariate Cox regression analysis fibrinogen was an independent predictor of survival [hazard ratio (1 g x L(-1) increase in plasma fibrinogen): 1.19, 95% confidence interval (CI): 1.05-1.35, P = 0.006] and a highly significant (P = 0.0008), independent predictor of fatal and nonfatal cardiovascular events [hazard ratio (1 g x L(-1) increase in plasma fibrinogen): 1.25, 95% CI: 1.10-1.43] in a model including traditional risk factors and serum C-reactive protein (CRP) and plasma homocysteine.

CONCLUSIONS

Fibrinogen is as an independent risk factor for overall and cardiovascular mortality in patients with ESRD. Intervention studies are required to see whether reducing plasma fibrinogen may help to curb the exceedingly high cardiovascular risk of the uremic population.

C-reactive protein, lipoprotein(a), homocysteine, and male sex contribute to carotid atherosclerosis in peritoneal dialysis patients

BACKGROUND

In patients with end-stage renal disease, the morbidity and mortality of cardiovascular disease are substantially greater than in the general population. Advancement in understanding the pathogenesis of atherosclerotic vascular disease suggests a central role of inflammation in atherogenesis. However, clinical data evaluating the role of inflammation in atherogenesis are sparse in peritoneal dialysis (PD) patients.

METHODS

We measured serum C-reactive protein (CRP), intact parathyroid hormone, lipoprotein(a) [Lp(a)], interleukin-1 receptor antagonist (IL-1Ra), tumor necrosis factor soluble receptor (TNF-sR), fibrinogen, and plasma homocysteine (Hcy), as well as intima-media thickness (IMT) and number of atherosclerotic plaques (plaque score [PS]) in the carotid arteries by means of carotid B-mode ultrasonography in 59 PD patients (35 men, 24 women; mean age, 52.4 years; average dialysis period, 36 months). All patients had chronic glomerulonephritis.

RESULTS

Sixty-eight percent of PD patients had at least 1 plaque. Serum CRP level was greater than the upper limit of the normal range in 52.5% of patients. Compared with PD patients with normal CRP levels, concentrations of such proinflammatory cytokines as IL-1Ra and TNF-sR, Lp(a), and Hcy were increased in PD patients with elevated CRP levels. However, no differences in plasma fibrinogen and intact parathyroid hormone levels were found between PD patients with increased and normal CRP levels. In a multiple regression model, age, male sex, CRP level, and Lp(a) level were independent predictors of IMT. Similarly, male sex, CRP level, Lp(a) level, and Hcy level were independent correlates of PS.

CONCLUSION

This study suggests that Lp(a) and Hcy levels and male sex, and especially CRP level, have an important role in carotid atherosclerosis in PD patients.

Atherosclerotic cardiovascular disease in rheumatoid arthritis

The past 3 years have seen a remarkable growth in the interest of cardiovascular disease in rheumatoid arthritis. There have been studies published documenting an increased incidence and prevalence of cardiovascular conditions in patients with rheumatoid arthritis compared with individuals without rheumatoid arthritis. There has also been interest in the occurrence of cardiovascular risk factors in rheumatoid arthritis and in the role of antirheumatic therapy, including cyclooxygenase-2 selective nonsteroidal anti-inflammatory drugs, methotrexate, corticosteroids, and tumor necrosis factor inhibitors. A number of studies using noninvasive means to detect atherosclerosis have shown that patients with rheumatoid arthritis may be prone to atherosclerosis. This information should be important to physicians who provide care to patients with rheumatoid arthritis, given the difficulty of recognizing cardiovascular signs and symptoms among patients with the disease.

Fibrinogen, inflammation and concentric left ventricular hypertrophy in chronic renal failure

BACKGROUND

We investigated the relationship between fibrinogen and echocardiographic measurements of left ventricular (LV) geometry and LV function in a group of 192 patients with end stage renal disease (ESRD).

RESULTS

Patients in the third fibrinogen tertile had higher mean wall thickness (MWT), relative wall thickness (RWT) and left ventricular mass index (LVMI) and lower LV end diastolic diameter and LV ejection fraction than those in the other tertiles. On multivariate analysis fibrinogen resulted to be an independent correlate of MWT (P = 0.001) and RWT (P = 0.0001) and the first factor in rank explaining the variance in LV ejection fraction (P = 0.0001). Left ventricular concentric hypertrophy was more prevalent (P = 0.001) in patients in the third fibrinogen tertile (n = 35, 54%) than in those in the second (n = 24, 37%) and first (n = 13, 21%) tertiles. In a multiple logistic regression model patients in the third tertile of fibrinogen had a risk for left ventricular concentric hypertrophy that was 3.56 (95% CI: 1.56-8.14) fold higher than in those in the first tertile (P = 0.003).

CONCLUSIONS

Elevated fibrinogen is independently associated with LV concentric hypertrophy and systolic dysfunction in ESRD patients. These relationships may contribute to the negative prognostic impact of elevated fibrinogen levels in ESRD.

Neuropeptide Y, left ventricular mass and function in patients with end stage renal disease

OBJECTIVE

Neuropeptide Y (NPY) is released during sympathetic stimulation and mediates the central effects of the adipostatic hormone leptin. The plasma concentration of NPY and leptin is increased in patients with end stage renal disease (ESRD), but it is unknown whether these substances are related to biochemical markers of sympathetic activity and to alterations in left ventricular (LV) mass and function in these patients.

DESIGN

We investigated the relationship between NPY, norepinephrine (NE), leptin and echocardiographic measurements in a cross-sectional study in 198 patients with ESRD.

RESULTS

NPY was directly related to plasma NE and heart rate but it was largely independent of arterial pressure and of retention of metabolic waste products. NPY was significantly higher in patients with LV hypertrophy and in those with LV systolic dysfunction than in those without these alterations. Of note, NPY emerged as an independent correlate of LV mass index and of LV ejection fraction (LVEF) (both P <or= 0.002) in multiple linear regression analyses including a series of cardiovascular risk factors. Furthermore in a multiple logistic regression model patients in the top NPY tertile had a risk for LV concentric hypertrophy that was 18.10 (95% confidence interval: 5.87-55.83) times higher than in those in the first tertile (P < 0.001). Leptin was unrelated to NPY as well as to LV mass and to systolic function.

CONCLUSIONS

Elevated NPY is independently associated with LV concentric hypertrophy and systolic dysfunction in ESRD. It remains to be seen whether these links contribute to the high cardiovascular mortality in these patients.

The effect of calcineurin inhibitors on endothelial function in renal transplant recipients

Endothelial dysfunction is of vital importance, as it may cause ischemia and dysfunction in various organs. Despite, this problem has been well documented in patients with end-stage renal disease (ESRD), there is not enough data considering this issue following renal transplantation. One of the potential causes of endothelial dysfunction in renal transplant recipients may be administration of calcineurin inhibitors. The aim of this study is to evaluate the effects of two different calcineurin inhibitors [cyclosporin A (CsA) and tacrolimus (FK506)] on endothelial function in renal transplant patients. Forty-four renal transplant recipients [22 on FK506 (group I) and 22 on CsA (group II)] were studied. Endothelial functions of the brachial artery were evaluated by using high resolution vascular ultrasound. Endothelium-dependent and -independent vasodilations were assessed by establishing reactive hyperemia and using sublingual nitroglycerine (NTG), respectively. Results are presented as percentage change from baseline values. Significant endothelial dysfunction was noted in renal transplant patients treated with CsA. While endothelium-dependent vasodilation was 12.1 +/- 5.1% in group I and it was 6.5 +/- 3.7% in group II (p < 0.001). The increase in brachial artery diameter after sublingual NTG was 20.1 +/- 6.3 and 12.7 +/- 5.6% in groups I and II, respectively. This indicates that the endothelium-dependent and -independent vasodilation of the patients on FK506 is better preserved than the patients on CsA therapy. Besides, blood flow volume (BFV) increase was 51.2 +/- 39.4 and 43.9 +/- 24.3%, in groups I and II, respectively, in reactive hyperemia period (p > 0.05). Post-transplant course of renal transplant recipients is complicated by endothelial dysfunction. This problem is more prominent in patients on CsA therapy, which can predispose these patients to more frequent cardiac complications.

Associations between inflammatory markers, traditional risk factors, and complications in patients with type 2 diabetes mellitus

OBJECTIVE

Inflammatory markers predict cardiovascular events in a wide range of patients. Two factors, fibrinogen (FIB) and high-sensitivity C reactive protein (CRP), are currently entering clinical practice as cardiovascular risk predictors. In patients with type 2 diabetes mellitus, we sought to examine the relationship between macrovascular disease, urinary albumin/creatinine ratio (ACR), and FIB or CRP, as well as the relationship of FIB and CRP with traditional risk predictors of these complications of diabetes.

METHODS

In 202 consecutive patients with type 2 diabetes mellitus from a diabetes clinic, clinical and biochemical data were obtained and a cross-sectional analysis was performed.

RESULTS

Patients with macrovascular disease had higher FIB (P=.02) but not higher CRP. They were older, more likely to have retinopathy or elevated serum creatinine, had higher ACR and lower HDL cholesterol. They were more likely to be treated with statins, beta-blockers, and ASA. Adjustment for statin therapy did not result in significant differences in CRP levels according to macrovascular disease status. Both FIB (P=.01) and CRP (P=.02) were significantly higher in patients with ACR whose values were in the proteinuria range. In multivariate analysis, both FIB (P=.001) and CRP (P=.03) were positively correlated with ACR, but no association was seen between CRP and ACR when FIB was entered in the model. Other factors positively associated with ACR were age, diastolic blood pressure, retinopathy, and hemoglobin A1c (HbA1c). FIB and CRP were strongly correlated (R=.49, P< or =.001) and this effect was independent of statin therapy. CRP was positively associated with body mass index (BMI), serum triglycerides, and sulfonylurea therapy and negatively associated with metformin therapy. Patients on statin therapy had significantly higher FIB and lower CRP. Women on hormone replacement therapy (HRT) had significantly lower FIB and higher CRP.

CONCLUSIONS

In patients with diabetes: (1) the two markers, FIB and CRP, are interrelated; (2) FIB is significantly associated with presence of microvascular disease, independent of CRP; (3) CRP is strongly associated with metabolic factors but not with complications of diabetes, independently of FIB; (4) statins and HRT were divergently associated with CRP and FIB as HRT was associated with lower FIB and higher CRP, while statins showed the reverse association; and (5) CRP and FIB provide different information about the characteristics and consequences of diabetes mellitus because of divergent associations with biological indicators and therapeutic agents.

Soluble Fas: a novel predictor of atherosclerosis in dialysis patients

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in patients with end-stage renal disease (ESRD). Disregulation of apoptosis within the vessel wall and upregulation of the Fas/Fas-ligand (Fas-L) system contribute to the development of atherosclerosis. Cross-sectional studies have suggested that elevated plasma levels of the soluble form of Fas (sFas) are associated with CVD. However, the role of sFas and sFas-L in predicting future cardiovascular events has yet to be defined.

METHODS

We evaluated the role of plasma sFas and sFas-L levels as predictors of CVD in a prospective cohort of 107 chronic hemodialysis patients.

RESULTS

During the study period (27 months), 53 patients (49.5%) presented with at least one cardiovascular end point. On univariate analysis, baseline sFas levels were significantly associated with the occurrence of cardiovascular end points, whereas sFas-L levels were not. Using Cox proportional hazards, increased sFas levels were associated with a significantly greater risk for cardiovascular end points (P = 0.03). This effect was independent of baseline CVD history, classic risk factors for atherosclerosis (diabetes, hypercholesterolemia, hypertension, and smoking), and markers of inflammation (C-reactive protein [CRP], soluble intercellular adhesion molecule-1). Increased CRP levels also were associated with cardiovascular end points (P = 0.04). In addition, increased cardiovascular mortality was found in patients in the highest sFas tertile compared with those in the lowest tertile (27.8% versus 8.6%; P = 0.04).

CONCLUSION

Increased plasma sFas levels are predictive of future CVD. These results suggest that sFas is a novel and independent predictor of active atherosclerotic disease in patients with ESRD.

The effect of viable Chlamydia pneumoniae on serum cytokines and adhesion molecules in hemodialysis patients

BACKGROUND

Chlamydia pneumoniae (Cp) induces the production of cytokines and adhesion molecules in infected host eukaryotic cells. The causes for pro-inflammatory cytokine and adhesion molecule increase in hemodialysis (HD) patients have not been fully elucidated. The possibility that, in this particularly atherosclerotic population, Cp, a microorganism implicated in the infectious-based inflammatory hypothesis of atherosclerosis' is also responsible for these molecules' increase is assessed in this study.

METHODS

In 130 stable HD patients, serum interleukin-1 beta (IL-1), interleukin-6, tumor necrosis factor alpha, interleukin-10, L-selectin, E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 (VCAM-1) levels were determined. Cp presence was identified by inoculation of the patient's peripheral blood mononuclear cells (PBMCs) in Hep-2 cell lines and subsequent polymerase chain reaction (PCR) in DNA extracted from cell cultures, as well as by determination of serum IgG antibodies against Cp (IgGCp).

RESULTS

Patients, positive or negative for IgGCp, had no statistically significant differences in all molecules measured. Patients with viable Cp in PBMCs had higher serum levels of IL-1 and soluble VCAM-1 than negative ones for IgGCp (IL-1 6.87 +/- 7.35 vs. 2.34 +/- 1.47 pg/mL; P = 0.0009 and VCAM-1 1647.16 +/- 513.64 vs. 1162.14 +/- 546.83 ng/mL; P = 0.0115, respectively). Viable Cp in PBMCs remained a significant predictor factor for IL-1 and VCAM-1 in statistical analysis, when patients' characteristics and dialysis conditions were also evaluated.

CONCLUSIONS

Our results showed that some serum cytokine and adhesion molecule increase in HD patients could be attributed to viable Cp presence in PBMCs. These findings support the Cp-based inflammatory atherogenous hypothesis and add a better understanding of these molecules' increase in HD patients.

Adipose tissue as a source of inflammatory cytokines in health and disease: focus on end-stage renal disease

Adipose tissue is a necessary survival characteristic of species that do not have constant access to food. TNF-alpha is a very fundamental "internal regulator" (intra-system) of adipose tissue metabolism, and IL-6 and IL-1 beta are relevant control factors, as well. Leptin and IL-6, but not TNF-alpha, appear to be the major signals linking adipose tissue to the systemic immunologic response. In ESRD, it has been coherently observed that acute-phase reactants like CRP and serum amyloid A are independently associated to atherosclerosis, death, and cardiovascular complications. Leptin is inversely related with plasma creatinine, suggesting that reduced renal clearance is a primary factor responsible for hyperleptinemia in ESRD. On the other hand, this adipose tissue hormone behaves as an inverse acute-phase reactant (i.e., it decreases during spontaneous episodes of the acute-phase response). Dialysis patients with hyperleptinemia have more severe degrees of insulin resistance but further studies are required to see whether leptin plays a role in insulin resistance in these patients. The most abundant protein synthesized in the adipose tissue, adiponectin, is inversely related to metabolic risk factors like glucose, triglycerides, insulin, and HDL cholesterol in uremic patients, suggesting that this cytokine is a protective factor for the cardiovascular system. Accordingly, plasma adiponectin is an independent, inverse predictor of incident cardiovascular events in dialysis patients.

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 between serum albumin and carotid atherosclerosis: the NHLBI Family Heart Study

BACKGROUND AND PURPOSE

Lower concentrations of albumin have been positively related to coronary disease. The aim of this project was to assess the association between serum albumin and carotid atherosclerosis.

METHODS

B-mode ultrasound was used to assess carotid plaques and intima-media thickness (IMT) among white subjects from 592 randomly ascertained families in the National Heart, Lung, and Blood Institute Family Heart Study. Logistic regression was used to estimate prevalence odds ratios of any carotid plaques.

RESULTS

Of the 2072 persons studied, 47% were men. Higher serum albumin was associated with younger age, lower body mass index, and lower prevalence of hypertension and coronary disease. Lower serum albumin levels were not associated with an increased odds of carotid plaques. From the lowest to the highest quartile of albumin, multivariate adjusted odds ratios for the prevalence of any carotid plaques were 1.05 (95% CI, 0.59 to 1.86), 1.34 (95% CI, 0.78 to 2.32), 1.03 (95% CI, 0.52 to 1.86), and 1.0 (reference), respectively, in men and 0.71 (95% CI, 0.40 to 1.26), 0.76 (95% CI, 0.42 to 1.36), 0.79 (95% CI, 0.46 to 1.36), and 1.0, respectively, in women. Similarly, in a linear regression model adjusted for demographic, lifestyle, and metabolic factors, serum albumin was not associated with carotid IMT. When the first 3 were compared with the highest quartile of serum albumin, regression coefficients for internal carotid IMT were 0.06458 (SE, 0.06408), 0.07205 (SE, 0.05469), and 0.000773 (SE, 0.05687), respectively, for men and -0.01795 (SE, 0.05085), -0.08501 (SE, 0.04800), and 0.009528 (SE, 0.04622), respectively, for women.

CONCLUSIONS

Our data suggest that lower serum albumin levels are not associated with an increased odds of prevalent carotid atherosclerosis in either men or women.

Inflammation and outcome in end-stage renal failure: does female gender constitute a survival advantage?

BACKGROUND

Elevated C-reactive protein (CRP) is a strong predictor of cardiovascular events and all-cause mortality in end-stage renal disease (ESRD) patients. However, although sex hormones may influence serum levels of inflammatory proteins, gender has not been taken into consideration in previous studies of inflammation and outcome in ESRD patients.

METHODS

We included 663 (374 males) ESRD patients (59 +/- 1 year) from three European renal centers (Sweden, Germany and Italy) in which CRP levels and outcome data (follow-up 33 +/- 1 months) were available. The relation between outcome and serum levels of the soluble intercellular adhesion molecule (sICAM-1) was evaluated in 312 of the patients.

RESULTS

The present study shows that elevated CRP is a strong predictor of outcome, but whereas no difference in all-cause mortality was observed between non-inflamed (CRP <or=3.4 mg/L) males and females, inflamed males had a significantly (log rank 6.1; P = 0.01) higher mortality rate than inflamed females. A strong positive correlation between CRP and sICAM-1 was found in the combined patient material (rho = 0.37; P < 0.0001) as well as in the male (rho = 0.25; P < 0.01) and female (rho = 0.52; P < 0.0001) subgroups. The Cox proportional hazard model showed that whereas both elevated sICAM-1 and log CRP predicted outcome in males, neither predicted outcome significantly in females.

CONCLUSIONS

As inflamed female patients have a better outcome that inflamed males the present observation suggests that sex hormones may have important cardioprotective effects that limit the effect of inflammation on vascular injury in female ESRD patients.

Sustained increases of plasma homocysteine, copper, and serum ceruloplasmin after coronary artery bypass grafting

BACKGROUND

Homocysteine (Hcy) is an independent risk factor for coronary artery disease, but there are no reports on Hcy levels in patients undergoing coronary artery bypass graft (CABG) surgery. Interactions between Hcy and copper may mediate the vasculopathic impact of Hcy, and this may play a role in vein graft failure. The aim of this study was to assess the perioperative levels of Hcy, copper, ceruloplasmin (CP), folate, and vitamin B12 in patients undergoing myocardial revascularization surgery.

METHODS

Blood samples were taken from 55 consecutive patients undergoing elective conventional CABG (43 male; mean age, 63.2 +/- 5.2 years) 1 day preoperatively and postoperatively at 1 day, 6 days, and 6 weeks. Hcy, copper, CP, red cell folate, vitamin B12, creatinine, and C-reactive protein (CRP) were then measured using standard clinical chemistry methods. The same protocol was applied to 10 patients (7 male; mean age, 63.3 +/- 5.2 years) undergoing off-pump coronary artery bypass (OPCAB) surgery.

RESULTS

In the conventional CABG group, there were significant increases in the plasma concentrations at 6 days and 6 weeks postoperatively of Hcy (from 10.1 to 11.6 and 13.5 micromol/L, respectively), plasma copper (from 13.5 to 20.3 and 18.5 micromol/L), and serum ceruloplasmin (from 0.3 to 0.41 and 0.44 g/L). CRP and vitamin B12 were elevated at 6 days but not 6 weeks after the operation. In contrast, red cell folate and creatinine were not significantly changed. The subgroup analysis for the OPCAB patients showed the same trend as for the conventional group.

CONCLUSIONS

Coronary surgery precipitates a significant and sustained increase in the blood concentrations of Hcy and copper, which is not due to a decrease in folate and vitamin B12, altered renal function, or inflammation. Further studies are required to establish whether the concomitant increase in Hcy and copper plays an etiological role in vein graft disease.

C-reactive protein and cardiovascular disease in peritoneal dialysis patients

BACKGROUND

Elevated plasma concentrations of C-reactive protein (CRP) is a risk factor for cardiovascular disease (CVD) in the general population and in hemodialysis patients. The prognostic value of CRP is less well known in peritoneal dialysis (PD) patients. We examined the association between CRP and cardiovascular event (CVE) in a large population of PD patients.

METHODS

Two hundred and forty patients starting PD were enrolled in this prospective study. The role of CRP was analyzed with respect to other known cardiovascular risk factors.

RESULTS

The patients were followed for a mean duration of 41 +/- 21 months; the median value of CRP was 7 mg/L. Eighty-nine cardiovascular events (CVE; 37.1%) occurred in 84 patients and the CRP levels were higher in patients who experienced CVE (27 +/- 14 vs. 6 +/- 8 mg/L; P < 0.0001). In the Cox model, patients in the three lower quartiles of the CRP levels had a decreased risk of CVE compared with those in the highest quartile. Cox regression analysis also revealed that age, a previous history of cardiovascular disease, hyperhomocysteinemia and hypoalbuminemia were risk factors for CVE. CRP levels were higher in patients who died during the study period (25 +/- 12 vs. 5 +/- 8 mg/L; P = 0.003). In the Cox model, patients with CRP levels above the median had an increased risk of death compared with those in the lowest quartile.

CONCLUSIONS

Chronic inflammation, as reflected by elevated CRP levels, is frequent in patients starting PD and independently contributes to an increased incidence of CVE in this population.

Inflammation in end-stage renal disease: sources, consequences, and therapy

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Although traditional risk factors are common in ESRD patients, they alone may not be sufficient to account for the high prevalence of CVD in this condition. Recent evidence demonstrates that chronic inflammation, a nontraditional risk factor which is commonly observed in ESRD patients, may cause malnutrition and progressive atherosclerotic CVD by several pathogenetic mechanisms. The causes of inflammation in ESRD are multifactorial and, while it may reflect underlying CVD, an acute-phase reaction may also be a direct cause of vascular injury by several pathogenetic mechanisms. Available data suggest that proinflammatory cytokines play a central role in the genesis of both malnutrition and CVD in ESRD. Thus it could be speculated that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) would improve survival in dialysis patients. Recent evidence has demonstrated strong associations between inflammation and both increased oxidative stress and endothelial dysfunction in ESRD patients. As there is not yet any recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status as well as outcome in these patients.

Advanced coronary and carotid arteriopathy in young adults with childhood-onset chronic renal failure

BACKGROUND

Cardiovascular mortality is excessive in young adults with end-stage renal disease (ESRD). The factors contributing to ESRD-related vascular disease are incompletely understood. Young adults with childhood-onset chronic renal failure (CRF) are uniquely suited for risk factor assessment because of their long-term exposure at an age when vascular pathology in the general population is still minimal.

METHODS AND RESULTS

We used novel noninvasive technologies to screen for coronary and carotid artery disease in 39 patients with ESRD aged 19 to 39 years with childhood-onset CRF presently treated by dialysis or renal transplantation. Coronary artery calcification burden was assessed by CT scan with ECG gating and the intima-media thickness (IMT) of the carotid arteries by high-resolution ultrasound. Coronary artery calcifications were present in 92% of patients; calcium scores exceeded the 95th age- and sex-specific percentiles >10-fold on average. Carotid IMT was significantly increased compared with matched control subjects. Both coronary calcium scores and IMT were associated with cumulative dialysis and ESRD time and the cumulative serum calcium-phosphate product. Coronary calcium scores were strongly correlated with C-reactive protein and Chlamydia pneumoniae seropositivity, time-averaged mean serum parathyroid hormone, and plasma homocysteine. C-reactive protein and parathyroid hormone independently predicted coronary calcium accumulation. Smoking, obesity, and HbA1c were correlated with IMT in the control subjects but not in the patients.

CONCLUSIONS

Young adults with childhood-onset CRF have a high prevalence of arteriopathy associated with indicators of microinflammation, hyperparathyroidism, calcium-phosphate overload, and hyperhomocysteinemia but not traditional atherogenic risk factors. These risk factors persist even after successful renal transplantation.

Chlamydia pneumoniae serology is associated with thrombosis-related but not with plaque-related microembolization during carotid endarterectomy

BACKGROUND AND PURPOSE

Chlamydia pneumoniae has repeatedly been associated with atherosclerotic disease. Our study was designed to clarify whether this association is based on C pneumoniae-induced transformation of a stable into an unstable atherosclerotic plaque or on stimulation of hypercoagulability leading to increased thrombotic arterial occlusions by C pneumoniae infection. Transcranial Doppler ultrasonographic monitoring of the middle cerebral artery during carotid endarterectomy offers the opportunity to study, before removal of the plaque, atherothrombotic emboli dislodging from an unstable carotid plaque (plaque-related emboli) and emboli related to (excessive) thrombus formation at the endarterectomy site after removal of the plaque and restoration of flow (thrombosis-related emboli).

METHODS

C pneumoniae IgA (> or =1/16) and IgG (> or =1/64) seropositivity was assessed in 53 patients with symptomatic carotid artery disease undergoing carotid endarterectomy. The removed carotid plaques were studied histologically to assess plaque instability.

RESULTS

Plaque- and thrombosis-related emboli were registered in 43 patients with an adequate transtemporal window. IgA seropositivity (58%) was associated significantly with thrombosis-related embolization (P=0.030) but not with plaque-related embolization or with histological plaque instability.

CONCLUSIONS

C pneumoniae serology is associated with microembolization after endarterectomy and restoration of flow. Since these microemboli represent platelet aggregations and are related to cerebrovascular complications, our data suggest that C pneumoniae infection contributes to cerebrovascular events in patients with carotid artery disease through stimulation of thrombosis.

Association between interleukin-6 and carotid atherosclerosis in hemodialysis patients

BACKGROUND

Interleukin-6 (IL-6) is associated with cardiovascular complications in general subjects. Although blood IL-6 is greatly elevated in hemodialysis (HD) patients, the role of IL-6 in the advance of atherosclerosis remains to be determined.

METHODS

We conducted a cross-sectional study to investigate the relationship between circulating IL-6 and carotid atherosclerotic changes in 156 HD patients (age 58 +/- 1 years; time on HD treatment 13 +/- 1 years; 97 males and 59 females). Serum IL-6, IgG and IgA titers of Chlamydia pneumoniae antibodies, the intima-media thickness (IMT) and the cross-sectional intima-media area (IMarea) of the carotid arteries were measured by ultrasonography in each patient.

RESULTS

Serum IL-6 levels were significantly higher in HD patients (2.04 +/- 0.16 pg/mL) compared to normal age-matched control subjects (0.31 +/- 0.06 pg/mL, N = 24). Circulating log IL-6 levels were positively correlated with IMT (r = 0.278, P < 0.01) and IMarea (r = 0.344, P < 0.01), respectively. A stepwise multiple regression analysis revealed that IL-6 became significant predictors for IMT and IMarea but not for aortic wall calcification at L2/3 vertebrae. Serum log IL-6 was significantly correlated with IgG (r = 0.277, P < 0.01) and IgA titers of anti-Chlamydia antibodies (r = 0.192, P < 0.02). Serum IgA anti-Chlamydia titers were also correlated with the maximal diameter of carotid plaque (r = 0.293, P < 0.04).

CONCLUSIONS

These findings suggested that IL-6 is associated with the severity of carotid atherosclerosis in HD patients. Persistent chronic chlamydial infection may be related, in part, to the advance of carotid plaque enlargement in dialysis patients.

Persistent elevation of C-reactive protein and ischemic heart disease in patients with continuous ambulatory peritoneal dialysis

We evaluated the association between a persistent elevation of C-reactive protein (CRP) level and the presence or severity of ischemic heart disease (IHD) in patients with continuous ambulatory peritoneal dialysis (CAPD). Seventy-three patients, who were over 40 years old, underwent dipyridamole thallium single photon emission computed tomography (SPECT), and followed-up for more than 1 year were enrolled. We measured stored plasma for CRP every 3 months. Elevation of CRP was defined as greater than or equal to 5 mg/L and persistent elevation of CRP as elevated CRP levels that lasted longer than 6 months. Serum albumin, cholesterol, lipoprotein(a), and plasma fibrinogen were measured at 3 months after the start of CAPD. Twenty-six patients showed an elevation of CRP for more than 6 months during the follow-up period. Twenty-eight patients showed positive findings on thallium SPECT. Coronary angiography showed significant stenosis (narrowing of the diameter more than 50%) in 23 of the 25 patients studied. Seventeen (65%) of 26 patients who had an elevated CRP level for longer than 6 months had positive thallium SPECT. The presence of diabetes, albumin, fibrinogen, and the presence of a persistent elevation of CRP were different between the patients with positive (n = 28) or negative thallium SPECT (n = 45). A multivariate logistic regression analysis showed that a persistent elevation of CRP is the only predictor of positive thallium SPECT (P = 0.002). There was a tendency of association, although it was not statistically significant, between the persistence of CRP elevation and the severity of IHD (P = 0.066). Three of 9 patients who had a persistent elevation of CRP and a negative thallium SPECT had a history of cerebral infarction or peripheral vascular disease. Therefore, 77% (20/26) of an elevated CRP level that lasted longer than 6 months can be explained by the presence of IHD or other atherosclerotic vascular disease. In conclusion, a persistent elevation of CRP level in patients with CAPD was strongly associated with IHD. For patients who have a persistent elevation of CRP without an apparent cause, we recommend a workup for IHD or other atherosclerotic cardiovascular disease.

Elevated interleukin-6 predicts progressive carotid artery atherosclerosis in dialysis patients: association with Chlamydia pneumoniae seropositivity

The cardiovascular mortality rate is unacceptably high in patients with end-stage renal disease (ESRD), which suggests an accelerated atherogenic process. The cause(s) of the accelerated atherogenesis in ESRD patients are not known, though recent studies suggest that persistent infection, such as Chlamydia pneumoniae, and proinflammatory cytokines may contribute. Forty-five ESRD patients (26 men) aged 51 +/- 2 years was studied at a time-point close to start of dialysis treatment and again after about 12 months of dialysis treatment. By using noninvasive B-mode ultrasonography, we evaluated changes in a surrogate marker of atherosclerosis, calculated intima media (cIM) area, in the common carotid artery. C-reactive protein (CRP), S-albumin, and interleukin-6 (IL-6) assessed the presence of an inflammatory reaction. We also measured C pneumoniae antibodies by microimmunofluorescence, nutritional status by subjective global assessment, lipid parameters, smoking habits, and the presence of comorbidity close to the start of dialysis. No significant changes in the prevalence of carotid plaques or the mean cIM area were observed during the first 12 months of dialysis. However, because some patients showed marked increases in the cIM area during only 12 months of dialysis we divided the patients into 2 groups: 23 nonprogressors ((delta)cIM area -2.7 +/- 0.4 mm2) and 22 progressors ((delta)cIM area 3.6 +/- 0.7 mm2). Sex, age, body mass index, comorbidity, blood lipid levels, S-albumin, and CRP levels did not differ significantly between the 2 groups. On the other hand, progressors had a significantly elevated basal median level of IL-6 (5.7 versus 3.1 pg/mL; P < 0.05) and an increased prevalence of positive (> or 1/64) immunoglobulin (Ig) A antichlamydia antibodies (59% versus 17%; P < 0.01) compared with nonprogressors. A significant positive (R = 0.41; P < 0.01) correlation was found between Log IL-6 and changes in the cIM area during 12 months of dialysis. In a stepwise multiple regression model, Log IL-6 did predict, independently (P < 0.01) of traditional risk factors and C pneumoniae antibodies, changes in the cIM area. These data suggest that a persistent chlamydial infection stimulates IL-6 levels, which in turn may be involved in the pathogenesis of accelerated carotid atherosclerosis in dialysis patients.

Asymmetric dimethylarginine, C-reactive protein, and carotid intima-media thickness in end-stage renal disease

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthase that has been linked to endothelial dysfunction and atherosclerosis in the general population. ADMA is also elevated in end-stage renal disease and may contribute to the high cardiovascular risk in patients with chronic renal failure. A prospective cohort study was performed to investigate the relationship between plasma ADMA, C-reactive protein (CRP), and intima-media thickness (IMT) in 90 patients undergoing hemodialysis. In the baseline study, plasma ADMA was directly related to IMT both on univariate analysis (r = 0.32, P = 0.002) and on multiple regression analysis (beta = 0.23, P = 0.01). In the follow-up study (15 mo) IMT changes were significantly related to ADMA (r = 0.51, P = 0.02) and serum CRP (r = 0.53, P = 0.01) in patients with initially normal IMT. In these patients, ADMA and CRP were strongly interrelated (r = 0.64, P = 0.002), and on multiple regression analysis the interaction between ADMA and CRP emerged as the sole independent predictor of the progression of intimal lesions. Independently of other risk factors, plasma ADMA in patients on hemodialysis is significantly related to IMT. Furthermore, in patients with initially normal IMT, ADMA and CRP are interacting factors in the progression of carotid intimal lesions. These data support the hypothesis that accumulation of this endogenous inhibitor of NO synthase is an important risk factor for cardiovascular disease in chronic renal failure and suggest a possible link between ADMA and inflammation.

Adiponectin, metabolic risk factors, and cardiovascular events among patients with end-stage renal disease

Adiponectin (ADPN), which is a secretory protein of adipose tissue, attenuates endothelial inflammatory responses in vitro. Among human subjects, plasma ADPN concentrations are reduced among patients with atherosclerotic complications but are substantially increased among patients with advanced renal failure. The clinical and biochemical correlates of plasma ADPN levels were investigated and the predictive power of ADPN levels with respect to survival rates and cardiovascular events was prospectively tested in a cohort of 227 hemodialysis patients, who were monitored for 31 +/- 13 mo. Plasma ADPN levels were 2.5 times higher (P < 0.0001) among dialysis patients (15.0 +/- 7.7 microg/ml) than among healthy subjects (6.3 +/- 2.0 microg/ml), were independent of age, and were higher (P = 0.03) among women (15.2 +/- 7.9 microg/ml) than among men (14.0 +/- 7.4 microg/ml). For both genders, plasma ADPN levels were inversely related to body mass index values, plasma leptin levels, insulin levels, serum triglyceride levels, and homeostatic model assessment index values. Furthermore, plasma ADPN levels were directly related to HDL cholesterol levels and inversely related to von Willebrand factor levels. Plasma ADPN levels were lower (P < 0.05) among patients who experienced new cardiovascular events (13.7 +/- 7.3 microg/ml) than among event-free patients (15.8 +/- 7.8 microg/ml). There was a 3% risk reduction for each 1 microg/ml increase in plasma ADPN levels, and the relative risk of adverse cardiovascular events was 1.56 times (95% confidence interval, 1.12 to 1.99 times) higher among patients in the first ADPN tertile, compared with those in the third tertile. Plasma ADPN levels are an inverse predictor of cardiovascular outcomes among patients with end-stage renal disease. Furthermore, ADPN is related to several metabolic risk factors in a manner consistent with the hypothesis that this protein acts as a protective factor for the cardiovascular system.

Diabetes mellitus, aortic stiffness, and cardiovascular mortality in end-stage renal disease

Cardiovascular mortality is elevated in patients with end-stage renal disease (ESRD), especially in those with diabetes mellitus. Although the higher cardiovascular death rate in diabetic ESRD patients may be the result of more advanced atherosclerotic changes of the arterial wall, this has not been documented previously. Aortic stiffness was compared between ESRD patients with and without diabetes, and the impact of aortic stiffness on cardiovascular mortality was examined in a prospective, observational cohort study. The cohort consisted of 265 ESRD patients on hemodialysis, including 50 diabetic patients studied between June 1992 and December 1998. At baseline, the diabetic ESRD patients had significantly higher aortic pulse wave velocity (PWV), a noninvasive measure of aortic stiffness, than the nondiabetic patients. During a mean follow-up period of 63 mo, 81 deaths, including 36 cardiovascular deaths, were recorded. Kaplan-Meier analysis revealed higher all-cause or cardiovascular mortality rates in the diabetic as compared with the nondiabetic patients and also in those with higher aortic PWV than those with lower aortic PWV. The effect of diabetes on cardiovascular death was significant in the Cox model, including age, years on hemodialysis, gender, smoking, C-reactive protein, hematocrit, and body mass index as covariates. However, when aortic PWV was included as a covariate, the impact of diabetes was no longer significant, whereas aortic PWV was a significant predictor. In a model including 13 covariates, aortic PWV remained a significant predictor for cardiovascular and overall mortality but not for non-cardiovascular death. These results demonstrate that the increased aortic stiffness of the ESRD patients with diabetes mellitus contributed to the higher all-cause and cardiovascular mortality rates.

Association of inflammation and malnutrition with cardiac valve calcification in continuous ambulatory peritoneal dialysis patients

Cardiac valve calcification (VC) has long been regarded as a consequence of aging and abnormal calcium-phosphate metabolism in uremic patients. In view of the recent recognition of association among inflammation, malnutrition, and atherosclerosis, the possible role of inflammation and malnutrition in VC was investigated. Inflammatory markers (including C-reactive protein [CRP], fibrinogen, and basal metabolic rate) and nutritional status (assessed using serum albumin, subjective global nutrition assessment, and handgrip strength) were examined, in addition to calcium phosphate parameters and other traditional cardiovascular risk factors, including gender, smoking habits, BP, and lipid profile, in relation to VC in 137 patients who were on continuous ambulatory peritoneal dialysis. Compared with patients with no VC, patients with VC not only were older (60 [10] versus 54 [12] yr; P = 0.005), had higher plasma phosphate (1.89 [0.52] versus 1.64 [0.41] mmol/L; P = 0.003), and had higher parathyroid hormone (83 [40, 145] versus 38 [16, 71] pmol/L; P = 0.001) but also had higher CRP (4.5 [0.1, 13.4] versus 0.2 [0.1, 4.4] mg/L; P = 0.004), had higher fibrinogen (6.6 [1.9] versus 5.7 [1.3] g/L; P = 0.002), and had lower serum albumin (26 [4] versus 29 [3] g/L; P = 0004). Twenty-three percent of patients with VC versus 17% of patients with no VC were moderately to severely malnourished according to subjective global nutrition assessment (P = 0.05). Even after adjustment for patients' age, duration of continuous ambulatory peritoneal dialysis, diabetes, and calcium x phosphate product, cardiac VC remained strongly associated with CRP (odds ratio, 1.05; P = 0.026) and albumin (odds ratio, 0.85; P = 0.01). The data suggest that VC not only is a passive degenerative process but also involves active inflammation, similar to that seen in atherosclerosis. The presence of uncontrolled hyperphosphatemia and hyperparathyroidism further accelerates the progression of calcification. The data also indicate that VC and atherosclerosis should be considered as associated syndromes, sharing similar pathogenic mechanisms, namely active inflammation.