Complement Components sC5b-9 and CH50 Predict Prognosis in Heart Failure Patients Combined With Hypertension

BACKGROUND

Heart failure (HF), resulting from inflammation and vessel injury, is one of the leading causes of poor quality of life and premature death. The complement system plays a leading role in vessel integrity and inflammation response. However, the association between serum complement level and the prognosis of HF remains unclear.

METHODS

In our study, a total of 263 newly diagnosed hypertension patients with HF were included. Eight classical cardiovascular risk factors were collected, and plasma C3a, C3b, C5a, sC5b-9, and CH50 levels were detected.

RESULTS

Compared with the control group, plasma C5a (P<0.001), sC5b-9 (P<0.001), and CH50 (P = 0.004) levels of hypertension patients with HF were significantly increased. On the basis of univariate analysis, an older age, higher frequency of alcohol consumption, high level of body mass index, medium or high risk of hypertension, hyperlipidemia, and diabetes were poor prognostic factors whereas low levels of C5a, sC5b-9, and CH50 were associated with favorable overall survival (OS). When these factors fit into a multivariate regression model, patients with hyperlipidemia (P = 0.002, hazard ratio [HR] = 3.09), N-terminal pro-Brain Natriuretic Peptide (NT-pro-BNP) ≥ 14.8 (P < 0.001, HR = 11.14), sC5b-9 level ≥ 1,406.2 µg/ml (P = 0.180, HR = 5.51) or CH50 level ≥ 294.6 µg/ml (P < 0.001, HR = 4.57) remained statistically factors for worsened OS and regarded as independent risk factors. These independently associated risk factors were used to form an OS estimation nomogram. Nomogram demonstrated good accuracy in estimating the risk, with a bootstrap-corrected C index of 0.789.

CONCLUSIONS

sC5b-9 and CH50 levels are increased in hypertension patients with HF. Nomogram based on multivariate analysis has good accuracy in estimating the risk of OS.

Non-Invasive whole-body detection of complement activation using radionuclide imaging in a mouse model of myocardial ischaemia-reperfusion injury

Complement activation is a recognised mediator of myocardial ischaemia-reperfusion-injury (IRI) and cardiomyocytes are a known source of complement proteins including the central component C3, whose activation products can mediate tissue inflammation, cell death and profibrotic signalling. We investigated the potential to detect and quantify the stable covalently bound product C3d by external body imaging, as a marker of complement activation in heart muscle in a murine model of myocardial IRI. We used single-photon-emission-computed-tomography (SPECT) in conjunction with ^99mTechnecium-labelled recombinant complement receptor 2 (^99mTc-rCR2), which specifically detects C3d at the site of complement activation. Compared to control imaging with an inactive CR2 mutant (^99mTc-K41E CR2) or an irrelevant protein (^99mTc-PSMA) or using ^99mTc-rCR2 in C3-deficient mice, the use of ^99mTc-rCR2 in complement-intact mice gave specific uptake in the reperfused myocardium. The heart to skeletal muscle ratio of ^99mTc-rCR2 was significantly higher than in the three control groups. Histological analysis confirmed specific uptake of ^99mTc-rCR2. Following therapeutic inhibition of complement C3 activation, we found reduced myocardial uptake of ^99mTc-rCR2. We conclude, therefore that ^99mTc-rCR2 imaging can be used for non-invasive detection of activated complement and in future could be exploited to quantify the severity of myocardial damage due to complement activation.

The alternative complement pathway is dysregulated in patients with chronic heart failure

The complement system, an important arm of the innate immune system, is activated in heart failure (HF). We hypothesized that HF patients are characterized by an imbalance of alternative amplification loop components; including properdin and complement factor D and the alternative pathway inhibitor factor H. These components and the activation product, terminal complement complex (TCC), were measured in plasma from 188 HF patients and 67 age- and sex- matched healthy controls by enzyme immunoassay. Our main findings were: (i) Compared to controls, patients with HF had significantly increased levels of factor D and TCC, and decreased levels of properdin, particularly patients with advanced clinical disorder (i.e., NYHA functional class IV), (ii) Levels of factor D and properdin in HF patients were correlated with measures of systemic inflammation (i.e., C-reactive protein), neurohormonal deterioration (i.e., Nt-proBNP), cardiac function, and deteriorated diastolic function, (iii) Low levels of factor H and properdin were associated with adverse outcome in univariate analysis and for factor H, this was also seen in an adjusted model. Our results indicate that dysregulation of circulating components of the alternative pathway explain the increased degree of complement activation and is related to disease severity in HF patients.

Using next-generation RNA sequencing to examine ischemic changes induced by cold blood cardioplegia on the human left ventricular myocardium transcriptome

BACKGROUND

The exact mechanisms that underlie the pathological processes of myocardial ischemia in humans are unclear. Cardiopulmonary bypass with cardioplegic arrest allows the authors to examine the whole transcriptional profile of human left ventricular myocardium at baseline and after exposure to cold cardioplegia-induced ischemia as a human ischemia model.

METHODS

The authors obtained biopsies from 45 patients undergoing aortic valve replacement surgery at baseline and after an average of 79 min of cold cardioplegic arrest. Samples were RNA sequenced and analyzed with the Partek Genomics Suite (Partek Inc., St. Louis, MO) for differential expression. Ingenuity Pathway Analysis (Ingenuity Systems, Redwood City, CA) and Biobase ExPlain (Biobase GmbH, Wolfenbuettel, Germany) systems were used for functional and pathway analyses.

RESULTS

Of the 4,098 genes with a mean expression value greater than 5, 90% were down-regulated and 9.1% were up-regulated. Of those, 1,241 were significantly differentially expressed. Gene ontology analysis revealed significant down-regulation in immune inflammatory response and complement activation categories and highly consistent was the down-regulation of intelectin 1, proteoglycan, and secretory leukocyte peptidase inhibitor. Up-regulated genes of interest were FBJ murine osteosarcoma viral oncogene homolog and the hemoglobin genes hemoglobin α1 (HBA1) and hemoglobin β. In addition, analysis of transcription factor-binding sites revealed interesting targets in factors regulating reactive oxygen species production, apoptosis, immunity, cytokine production, and inflammatory response.

CONCLUSIONS

The authors have shown that the human left ventricle exhibits significant changes in gene expression in response to cold cardioplegia-induced ischemia during cardiopulmonary bypass, which provides great insight into the pathophysiology of ventricular ischemia, and thus, may help guide efforts to reduce myocardial damage during surgery.

MicroRNA-92a inhibition attenuates hypoxia/reoxygenation-induced myocardiocyte apoptosis by targeting Smad7

Background

MicroRNAs (miRNAs) regulate a lot of physiological and pathological processes, including myocardial ischemia/reperfusion. Recent studies reported that knockdown of miR-92a could attenuate ischemia/reperfusion-induced myocardial injury. In the present study, we examined the potential anti-apoptotic effects of miR-92a in a rat myocardiocyte cell line, and the possible role of Smad7 in such actions.

Methodology and Results

In a preliminary bioinformatic analysis, we identified SMAD family member 7 (Smad7) as a potential target for miR-92a. A luciferase reporter assay indeed demonstrated that miR-92a could inhibit Smad7 expression. Myocardial ischemia/reperfusion was simulated in rat H9c2 cells with 24-h hypoxia followed by 12-h reoxygenation. Prior to hypoxia/reoxygenation, cells were transfected by miR-92a inhibitor. In some experiments, cells were co-transfected with siRNA-Smad7. The miR-92a inhibitor dramatically reduced the release of lactate dehydrogenase and malonaldehyde, and attenuated cardiomyocyte apoptosis. The miR-92a inhibitor increased SMAD7 protein level and decreased nuclear NF-κB p65 protein. Effects of the miR-92a inhibitor were attenuated by co-transfection with siRNA-Smad7.

Conclusion

Inhibiting miR-92a can attenuate myocardiocyte apoptosis induced by hypoxia/reoxygenation by targeting Smad7.

Pre-existing endothelial cell activation predicts vasoplegia after mitral valve surgery

OBJECTIVES

Post-cardiac surgery vasoplegia is a common complication of cardiac surgery, characterized by profound loss of systemic vascular resistance. This results in severe hypotension, high cardiac output and metabolic acidosis reflecting inadequate tissue perfusion. The pathophysiological mechanisms underlying this syndrome remain unknown. We hypothesized that this vasoplegia reflects endothelial dysfunction, either as pre-existing condition or as a consequence of the surgical procedure.

METHODS

To examine these mechanisms, six established and distinct markers of endothelial cell activation were measured pre- and perioperatively in patients undergoing mitral valve surgery. Arterial (radial artery) and myocardial venous blood samples (coronary sinus) were collected simultaneously over the reperfused heart at various time points during the first hour after reperfusion. Additional samples were collected at baseline (brachial vein) and 1 day post-reperfusion (radial artery). Post-cardiac surgery vasoplegia was defined as a mean arterial blood pressure of <60 mmHg, with a cardiac index of ≥2.2 l/min/m(2) treated with continuous intravenous administration of norepinephrine.

RESULTS

No myocardial release of endothelial cell activation markers was observed upon reperfusion in patients with vasoplegia (n = 15; mean age 71 years, 73% male). In contrast, in patients without vasoplegia (n = 24; mean age 64 years, 54% male), reperfusion was characterized by a myocardial release of three endothelial cell activation markers. Myocardial von Willebrand Factor propeptide, osteoprotegerin and interleukin-8 were increased 107% (P < 0.001), 106% (P = 0.02) and 116% (P = 0.009), respectively, compared with arterial levels upon reperfusion. Similar systemic levels of all markers were found upon reperfusion in both groups, except for 120% increased soluble P-selectin (sP-selectin) levels in vasoplegia patients (P = 0.03). Remarkably, postoperative vasoplegia was identified with baseline von Willebrand Factor propeptide levels with a cut-off value of 11.9 nM as well as with baseline sP-selectin levels with a cut-off value of 64.4 ng/ml.

CONCLUSIONS

Pre-existing endothelial cell activation, reflected by higher baseline von Willebrand Factor propeptide and sP-selectin levels, is a predisposing factor for post-cardiac surgery vasoplegia. The pre-existing endothelial cell activation may have resulted in desensibilization of endothelium in patients who develop vasoplegic syndrome, resulting in no myocardial release of endothelial cell activation markers upon reperfusion.