The activated immune system and the renin-angiotensin-aldosterone system in congestive heart failure

Interaction between angiotensin-converting enzyme gene rs4343 polymorphism, environment factors, and angiotensin II level on susceptibility to knee osteoarthritis

OBJECTIVES

Osteoarthritis (OA) is a complex multifactorial disease. The association of knee OA risk with ACE gene rs4343 polymorphism, gene environment synergistic effect, and angiotensin II serum level has not been previously examined. Therefore, we investigate the ACE gene rs4343 polymorphism in knee OA, and its association with severity of knee OA, and angiotensin II serum level.

METHODS

Using a case-control design, we recruited 200 subjects (100 cases and 100 controls) and all were subjected to genotyping of rs4343 SNP by real-time polymerase chain reaction and assay of serum angiotensin II level by ELISA.

RESULTS

G containing genotypes (AG and GG) and G allele frequencies of the ACE rs4343 polymorphism were significantly higher in the case group than that in the control group. There was significant association between ACE rs4343 genotypes and risk of knee OA under the following genetic inheritance models: GG vs. AA (P=0.003), AA vs. GG/AG (P=0.014), AG/AA vs. GG (P=0.037), and G vs. A (P<0.001). Stratified analyses showed ACE rs4343 polymorphism was evidently associated with a significantly increased risk of knee OA among those had BMI≥25% (adjusted OR=3.016; 95% CI 1.052-8.648; P=0.040). Additionally, knee OA patients with GG genotype had greater knee specific WOMAC index, Kellgren score, and serum angiotensin II level than those with AA or GA genotypes.

CONCLUSION

The investigated polymorphism in the ACE gene rs4343 may reflect the risk and severity of knee OA in the Egyptian population, particularly with the GG genotype. The interaction between ACE gene rs4343 polymorphism and obesity further increased the risk of knee OA. Moreover, the higher angiotensin II level may be involved in the pathogenesis of knee OA.

The Preoperative Inflammatory Status Affects the Clinical Outcome in Cardiac Surgery

AIMS

There are many reasons for the increase in post-operative mortality and morbidity in patients undergoing surgery. In fact, an activated inflammatory state before cardiac surgery, can potentially worsen the patient's prognosis and the effects of this preoperative inflammatory state in the medium-term remains unknown.

METHODS

There were 470 consecutive patients who underwent cardiac surgery, and were divided in three groups according to the median values of preoperative C-reactive protein (CRP) and fibrinogen (FBG): The first group was the low inflammatory status group (LIS) with 161 patients (CRP < 0.39 mg/dL and FBG < 366 mg/dL); the second was the medium inflammatory status group (MIS) with 150 patients (CRP < 0.39 mg/dL and FBG ≥ 366 mg/dL or CRP ≥ 0.39 mg/dL and FBG < 366 mg/dL,); and the third was the high inflammatory status group (HIS) with 159 patients (CRP ≥ 0.39 mg/dL and FBG ≥ 366 mg/dL,).

RESULTS

The parameters to be considered for the patients before surgery were similar between the three groups except, however, for age, left ventricular ejection fraction (LVEF) and the presence of arterial hypertension. The operative mortality was not significantly different between the groups (LIS = 2.5%, MIS = 6%, HIS = 6.9%, p = 0.16) while mortality for sepsis was significantly different (LIS = 0%, MIS = 1.3%, HIS = 3.7%, p = 0.03). The infections were more frequent in the HIS group (p = 0.0002). The HIS group resulted in an independent risk factor for infections (relative risk (RR) = 3.1, confidence interval (CI) = 1.2-7.9, p = 0.02). During the 48-months follow-up, survival was lower for the HIS patients. This HIS group (RR = 2.39, CI = 1.03-5.53, p = 0.05) and LVEF (RR = 0.96, CI = 0.92-0.99, p = 0.04) resulted in independent risk factors for mortality during the follow-up.

CONCLUSIONS

The patients undergoing cardiac surgery with a preoperative highly activated inflammatory status are at a higher risk of post-operative infections. Furthermore, during the intermediate follow-up, the preoperative highly activated inflammatory status and LVEF resulted in independent risk factors for mortality.

C-reactive protein level on admission and time to and cause of death in patients hospitalized for acute heart failure

Aims

We analysed the association between C-reactive protein (CRP) levels measured on admission and timing and cause of death among patients hospitalized for acute heart failure (AHF).

Methods and Results

The ATTEND study prospectively registered 4777 hospitalized AHF patients with data on CRP levels on admission. Mortality risks were assessed by univariable and multivariable Cox proportional and non-proportional hazards models. The overall median CRP level was 5.8 mg/L (intertertile range: 2.9-11.8 mg/L). There were significant increases in all-cause, cardiac, and non-cardiac mortalities from the lowest to highest CRP tertiles throughout the follow-up periods. Within 120 days after admission, CRP levels in the highest tertile (>11.8 mg/L) were independently associated with higher all-cause (hazard ratio [HR], 2.21; 95% confidence interval [CI], 1.69-2.88; P < 0.001), cardiac (HR, 1.88; 95% CI, 1.37-2.58; P < 0.001), and non-cardiac (HR, 3.21; 95% CI, 1.94-5.32; P < 0.001) deaths, while levels in the second tertile (2.9-11.8 mg/L) were not associated with poorer survival, compared with levels in the first tertile (<2.9 mg/L). However, in terms of cardiac death, the hazard ratios for patients in the third tertile decreased markedly with time and only CRP levels in second tertile were independently associated with poorer cardiac survival after the follow-up period of 120 days (HR, 1.44; 95% CI, 1.09-1.89; P = 0.011).

Conclusions

Markedly elevated CRP levels at admission in patients with AHF may be associated with higher short-term cardiac and non-cardiac mortalities. In addition, modestly elevated CRP levels may be associated with higher mortality, especially cardiac mortality, after 120 days of long-term follow-up.

Effect of Elevated C-Reactive Protein Level at Discharge on Long-Term Outcome in Patients Hospitalized for Acute Heart Failure

In the acute heart failure (AHF) setting, the usefulness of C-reactive protein (CRP) at admission as a risk marker is challenged by the possible confounding effect of an acute-phase response. We thus evaluated the relation of CRP level at discharge (i.e., after stabilization of AHF) with subsequent postdischarge outcome in patients hospitalized for AHF. The acute decompensated heart failure syndromes study prospectively registered 4,269 hospitalized AHF patients with data on CRP levels at discharge. The median CRP level was 3.1 mg/L (interquartile range 1.1 to 9.5 mg/L). Within 120 days after discharge, only CRP levels in the fourth quartile (≥9.6 mg/L) were independently associated with higher all-cause mortality (adjusted hazard ratio [HR], 1.68) according to multivariable models with first-quartile (≤1.1 mg/L) as the reference. However, the HR for CRP levels in the fourth quartile decreased markedly with time, and CRP levels in the second (1.2 to 3.1 mg/L) and third (3.2 to 9.5 mg/L) quartiles were independently associated with poorer survival after the 120-day follow-up period (adjusted HR, 1.41 and 1.63, respectively). In addition, only CRP levels in the third quartile were independently associated with the composite end point of all-cause death and readmission for AHF after the 120 days of long-term follow-up (adjusted HR, 1.31). In conclusion, our results suggest that a modestly elevated CRP level (approximately 3 to 10 mg/L) at discharge had unique long-term prognostic implications in hospitalized patients with AHF.

MicroRNA involvement in immune activation during heart failure

Heart failure is one of the common end stages of cardiovascular diseases, the leading cause of death in developed countries. Molecular mechanisms underlying the development of heart failure remain elusive but there is a consistent observation of chronic immune activation and aberrant microRNA (miRNA) expression that is present in failing hearts. This review will focus on the interplay between the immune system and miRNAs as factors that play a role during the development of heart failure. Several studies have shown that heart failure patients can be characterized by a sustained innate immune activation. The role of inflammatory signaling is discussed and TLR4 signaling, IL-1β, TNFα and IL-6 expression appears to coincide with the development of heart failure. Furthermore, we describe the implication of the renin angiotensin aldosteron system in immunity and heart failure. In the past decade microRNAs (miRNAs), small non-coding RNAs that translationally repress protein synthesis by binding to partially complementary sequences of mRNA, have come to light as important regulators of several kinds of cardiovascular diseases including cardiac hypertrophy and heart failure. The involvement of differentially expressed miRNAs in the inflammation that occurs during the development of heart failure is still subject of investigation. Here, we summarize and comment on the first studies in this field and hypothesize on the putative involvement of certain miRNAs in heart failure. MicroRNAs have been shown to be critical regulators of cardiac function and inflammation. Future research will have to point out if dampening the immune response, and the miRNAs associated with it, during the development of heart failure is a therapeutically plausible route to follow.

Critical appraisal of C-reactive protein throughout the spectrum of cardiovascular disease

Clinicians involved in the care of patients with cardiovascular conditions have recently been confronted with an important body of literature linking inflammation and cardiovascular disease. Indeed, the level of systemic inflammation as measured by circulating levels of C-reactive protein (CRP) has been linked to prognosis in patients with atherosclerotic disease, congestive heart failure, atrial fibrillation, myocarditis, aortic valve disease and heart transplantation. In addition, a number of basic science reports suggest an active role for CRP in the pathophysiology of cardiovascular diseases. This article explores the potential role of CRP in disease initiation, progression, and clinical manifestations and reviews its role in the prediction of future events in clinical practice. Therapeutic interventions to decrease circulating levels of CRP are also reviewed.

Preoperative C-Reactive Protein Predicts Mid-Term Outcome After Cardiac Surgery

BACKGROUND

C-reactive protein (CRP) is a known risk factor for cardiovascular events in the healthy population and in patients with coronary artery disease. High CRP levels before cardiac surgery are associated with worse short-term outcome, but its role after discharge home remains unknown. The study objective was to evaluate the effect of CRP on short-term and mid-term outcome after cardiac surgery.

METHODS

From August 2000 to May 2004, values for preoperative CRP were available for 597 unselected patients undergoing cardiac operations. CRP was used to divide this cohort in two groups: a low inflammatory status (LHS) group of 354 patients with CRP of less than 0.5 mg/dL, and a high inflammatory status (HIS) group of 243 patients with a CRP of 0.5 mg/dL or more. Follow-up lasted a maximum of 3 years (median, 1.8 +/- 1.5 years) and was 92.6% complete.

RESULTS

In-hospital mortality was 8.2% in the HIS group and 3.4% in the LIS group (odds ratio [OR], 2.61; p = 0.02). Incidence of postoperative infections was 16.5% in the HIS group and 5.1% in the LIS group (OR, 3.25; p = 0.0001). Sternal wound infections were also more frequent in the HIS group (10.7% versus 2.8%; OR, 3.43; p = 0.002). During follow-up, the HIS group had worse survival (88.5% +/- 2.9% versus 91.9% +/- 2.5%; OR, 1.93; p = 0.05) and a higher need of hospitalization for cardiac-related causes (73.6% +/- 6% versus 86.5% +/- 3.2%; OR, 1.82; p = 0.05).

CONCLUSIONS

Patients undergoing cardiac surgery with a CRP level of 0.5 mg/dL or more are exposed to a higher risk of in-hospital mortality and postoperative infections. Despite surgical correction of cardiac disease, a high preoperative CRP value is an independent risk factor for mid-term survival and hospitalization for cardiac causes.

Chronic heart failure and the immune system

Several lines of evidence support a role of immune mechanisms in the pathogenesis of chronic heart failure (CHF). Proinflammatory cytokines (interleukin-1, -2, -6, and tumor necrosis factor) and chemokines are involved in cardiac depression and in the progression of heart failure. Other components believed to be relevant to the pathogenesis of CHF are adhesion molecules, autoantibodies, nitric oxide (NO), and endothelin-1. The origin of the immune activation in patients with CHF is still unknown, however two hypotheses have been proposed on the basis of experimental and clinical data. One suggests that the bowel wall edema leads to bacterial translocation with subsequent endotoxin release and immune activation. The second suggests that the heart in CHF is the main source of cytokines, as is shown by the fact that TNF alpha is produced by the failing myocardium but not by a normal one. No single source of cytokine production (gut or heart) seems sufficient to fully explain the multiple organ involvement and the systemic inflammation of CHF, which is probably related to systemic hypoxia, a potent stimulus for activation of the immune system and for cytokine production. The effort of define the immune system's role has opened new perspectives of therapeutic strategies, such as anti-cytokine drugs, to treat CHF.

C-reactive protein as a predictor of improvement and readmission in heart failure

OBJECTIVES

Only recently, new risk factors to explain atherosclerotic disease have been identified. One of the most important clinical manifestations of atherosclerosis is heart failure. Our study was aimed at investigating C-reactive protein (CRP), a marker of systemic inflammation, in the context of heart failure, and to determine its usefulness in predicting the need for readmission in patients with heart failure and their degree of improvement.

DESIGN

We studied patients admitted to our hospital due to heart failure, independent of the cause. CRP levels were measured with a sensitive standard assay on a Nephelometer analyser. Patients were classified on admission and discharge following New York Heart Association (NYHA) functional criteria; left ejection fraction was also determined by transthoracic echocardiography. Patients presenting clear sources of infection or inflammatory disease were excluded. Our control group consisted of patients admitted for syncope. Each patient was followed up through a computer system controlling admissions to and discharge from the hospital, for a period of 18 months after initial admission. End points considered were NYHA functional class on discharge, readmission and death.

RESULTS

We studied prospectively 76 patients with a mean age of 73.5+/-11 [95% confidence interval (CI) 71.2-75.8]; 44 were male (58%) and 32 female (42%). The mean CRP level in patients with heart failure was 3.94+/-5.87 (95% CI, 1.26-7.60), while in 15 patients with syncope it was 0.84+/-1.95 (95% CI, 0.96-2.94) (P=0.0007). The principal causes of heart failure included dilated cardiomyopathy due to coronary arterial disease (30%), valvular disease (28%) and heart failure secondary to hypertension (25%). The mean left ejection fraction adequately measured in 72 (95%) patients was 50.41+/-9.88 (95% CI, 41.20-59.65). We observed a trend of higher CRP levels in relation to ejection fractions below 35%: 7.50+/-9.88 vs. 3.75+/-4.57, (P=0.09). Our results showed that on discharge CRP levels increased in relation to NYHA class: I: 0.74+/-0.69; II: 3.78+/-3.76; III: 7.4+/-8.65; IV: 12.2+/-15.27 (P<0.05). On follow-up of each patient for 18 months, 32 (43%) were readmitted due to deterioration of their heart condition. For patients who were readmitted, those presenting CRP levels >0.9 mg/dl were identified as candidates for earlier hospitalisation than those with levels below 0.9 mg/dl (P=0.02) RR=1.43. In logistic-regression analysis the only group of tested variables predicting readmission were levels of CRP, NYHA class and plasmatic K on discharge and left ventricle ejection fraction. Analysis of covariates yields CRP levels as being an independent predictor of readmission.

CONCLUSIONS

An inflammatory response is present in deteriorating heart failure. We observed higher CRP levels in patients with higher NYHA functional class, perhaps signalling a poor therapeutic response. Higher CRP levels were also related to higher rates of readmission and mortality and it could be an independent marker of improvement and readmission in heart failure.

Neopterin measurement in clinical diagnosis

Neopterin is a marker associated with cell-mediated immunity. It is produced in monocytes/macrophages primarily upon stimulation with interferon-gamma. Due to its chemical structure, neopterin belongs to the class of pteridines. It is excreted in an unchanged form via the kidneys. Serum levels above 10 nmol/L are regarded as elevated. The levels of neopterin in body fluids are elevated in infections, autoimmune diseases, malignancies, allograft rejection, cardiac and renal failure, coronary artery disease and myocardial infarction. Neopterin measurements not only provide an insight into the present state of cell-mediated immune response but also allow monitoring and prognosis of disease progression.

Elevated serum levels of soluble interleukin-2 receptor, neopterin and beta-2-microglobulin in idiopathic dilated cardiomyopathy: relation to disease severity and autoimmune pathogenesis

BACKGROUND

It has not been assessed whether high levels of soluble interleukin 2 receptor (sIL-2R), neopterin and beta-2 microglobulin in idiopathic dilated cardiomyopathy reflect heart failure severity and/or an active autoimmune process. The aim of this study was to relate serum levels of these markers to clinical and autoimmune features.

METHODS

We studied 60 patients with idiopathic dilated cardiomyopathy, 67 controls with ischemic heart failure and 34 normals.

RESULTS

Abnormal levels of sIL-2R, but not of neopterin and beta-2 microglobulin, were more frequent in idiopathic dilated cardiomyopathy than in ischemic patients (35% vs. 16%; P=0.02) or in normals (35% vs. 12%, P=0.01); mean sIL-2R levels were, however, similar in idiopathic dilated cardiomyopathy and ischemic heart failure (842+/-75 vs. 762+/-93 U/ml, P=NS). In idiopathic dilated cardiomyopathy abnormal levels of sIL-2R were associated with lower peak oxygen consumption (P=0.008), higher neopterin and HLA class II expression in the myocardium (P=0.02), but were unrelated to cardiac autoantibody status or titer. In addition, abnormal levels of neopterin were associated with adverse prognosis and higher beta-2 microglobulin; abnormal levels of beta-2 microglobulin with lower echocardiographic percent fractional shortening, higher sIL-2R and higher neopterin.

CONCLUSIONS

There is no convincing evidence that abnormal sIL-2R, neopterin and/or beta-2 microglobulin are disease-specific markers of idiopathic dilated cardiomyopathy. The lack of association with cardiac autoantibodies suggests that these abnormalities are mainly related to heart failure severity rather than autoimmune pathogenesis. In keeping with this view, high levels of sIL-2R, neopterin and/or beta-2 microglobulin identified a subset of idiopathic dilated cardiomyopathy patients with advanced disease and poor prognosis.