Mechanisms in acute septic cardiomyopathy: evidence from isolated myocytes

EvaLuation of early CRRT and beta-blocker InTervention in patients with ECMO (ELITE) trial: study protocol for a 2 × 2 partial factorial randomized controlled trial

Background

In critically ill patients requiring extracorporeal membrane oxygenation (ECMO) therapy, early initiation of continuous renal replacement therapy (CRRT) and beta-blockade of catecholamine-induced inotropic effects may improve outcomes.

Methods

A 2 × 2 partial factorial randomized controlled trial in eligible ECMO patients without a clear indication or contraindication to either intervention is centrally randomly assigned to (A) early or conventional-indicated CRRT and/or (B) beta-blocker or usual care. The primary outcome is all-cause mortality at 30 days for both arms. A total of 496 participants provides 80% power to determine a 20% risk reduction in mortality at 30 days with 5% type I error.

Discussion

This trial will help define the role of early CRRT and beta-blockade in ECMO patients. There have been 89 patients enrolled at 10 hospitals in study A and is ongoing. However, study B was stopped in August 2019 in the absence of any patients being enrolled.

Trial registration

ClinicalTrials.govNCT03549923. Registered on 8 June 2018. World Health Organization International Clinical Trials Registry Platform (WHO ICTEP) network. The Ethics Committee of Beijing Anzhen Hospital Approval ID is 2018013.

Agomelatine protects heart and aorta against lipopolysaccharide-induced cardiovascular toxicity via inhibition of NF-kβ phosphorylation

The aim of this study was to investigate the possible ameliorating effects of agomelatine (AGO) on lipopolysaccharide (LPS)-induced endothelial and cardiac damage. Twenty-four female Wistar Albino rats divided into 3 groups as follows: Control, LPS and LPS + AGO. Total oxidant status (TOS), total antioxidant status (TAS), nuclear factor kappa beta (NF-kβ)/p65, p-NF-kβ, full caspase-8 (Cas-8) and cleaved cas-8 levels were measured in cardiac tissues and creatine kinase MB (CKMB), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) levels in blood biochemically. In addition; cas-8, sirtuin-1 (SIRT-1), interleukin-4 (IL-4), interleukin-10 (IL-10), haptoglobin measured histopathologically in cardiac and aortic tissues. The levels of CKMB, AST, LDH and TOS were increased and TAS were decreased in the LPS group. In Western blot analyses NF-kβ/p65, p-NF-kβ/p65, full and cleaved cas-8 protein levels increased in cardiac tissues of LPS group. In histopathological and immunohistochemical evaluation of the heart sections; hyperemia, micro-hemorrhages and inflammatory cell infiltrations, increase of cas-8, haptoglobin, IL-4 and IL-10 and decrease of SIRT-1 levels were observed in cardiac and endothelial tissues of LPS groups. AGO treatment reversed all these parameters. It was shown that LPS-induced inflammation, oxidative stress and apoptosis via increasing of NF-kβ/p65 signaling, decreasing of SIRT-1 levels and increase of cas-8 levels in heart and endothelial tissues respectively. AGO corrected all these parameters by its antioxidant, antiinflammatory and antiapoptotic activities.

Shenfu injection attenuates lipopolysaccharide-induced myocardial inflammation and apoptosis in rats

Shenfu injection (SFI), a Chinese medicinal product, shows potent efficacy in treating sepsis. The aim of the present study was to clarify the protective effects of SFI against lipopolysaccharide (LPS)-induced myocardial inflammation and apoptosis. Experiments were carried out in Sprague-Dawley (SD) rats treated with LPS or LPS + SFI, and in H9C2 cardiomyocytes. The sepsis-associated myocardial inflammation and apoptosis was induced by the intraperitoneal injection of LPS (20 mg·kg^-1). SFI attenuated the increased expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1β induced by LPS both in serum and heart. In LPS group, cell viability was reduced, and reversed after SFI administration. LPS treatment increased the expression levels of cleaved-caspase 3 and Bax, and those of Bcl2 and Bcl2/Bax. These two trends were reversed by SFI administration. The expression levels of phosphorylated mitogen-activated protein kinase kinase (p-MEK) and phosphorylated extracellular regulated protein kinases (p-ERK) were increased by LPS, and reversed by SFI. MEK inhibitor U0126 attenuated the apoptosis induced by LPS. These results indicate that SFI could treat LPS-induced cardiac dysfunction. In conclusion, SFI attenuates the inflammation and apoptosis induced by LPS via downregulating the MEK and ERK signaling pathways.

Circumferential Strain Can Be Used to Detect Lipopolysaccharide-Induced Myocardial Dysfunction and Predict the Mortality of Severe Sepsis in Mice

BACKGROUND

Sepsis-induced myocardial dysfunction is a common and severe complication of septic shock. However, conventional echocardiography often fails to reveal myocardial depression in severe sepsis. Recently, strain measurements based on speckle tracking echocardiography (STE) have been used to evaluate cardiac function.

AIMS

To investigate the role of STE in detecting lipopolysaccharide (LPS)-induced cardiac dysfunction, M-mode and 2-D echocardiography were used in LPS-treated mice.

METHODS

The mice were treated with a 10mg/kg (n = 10), 20mg/kg (n = 10) or 25mg/kg LPS (n = 30) to induce cardiac dysfunction. Subsequently, the ejection fraction (EF) and fractional shortening (FS) were measured with standard M-mode tracings, whereas the circumferential (Scirc) and radial strain (Srad) were measured with STE. Serum biochemical and cardiac histopathological examinations were performed to assess sepsis-induced myocardial injury.

RESULTS

20mg/kg LPS resulted in more deterioration, myocardial damage and cardiac contractile dysfunction based on serum biochemical and histological examinations. The mice that were subjected to 20mg/kg LPS exhibited reduced Scirc but no reduction in Srad, whereas on conventional echocardiography, the ejection fraction (EF) and fractional shortening (FS) were similar in the 10mg/kg and 20mg/kg groups. Moreover, Scirc was positively correlated with body temperature in the mice at 20 h after LPS injection (r = 0.746, p = 0.001), but no significant correlation was observed between Srad and body temperature (r = 0.356, p = 0.123). Moreover, the mice with high Scirc (-5.9% to -10.4%) exhibited reduced mortality following the administration of 25mg/kg LPS (p = 0.03) compared with the low-strain group (-2% to -5.9%).

CONCLUSIONS

Taken together, our findings indicate that circumferential strain is a specific and reliable indicator for evaluating LPS-induced cardiac dysfunction in mice.

Septic cardiomyopathy in rat LPS-induced endotoxemia: relative contribution of cellular diastolic Ca(2+) removal pathways, myofibrillar biomechanics properties and action of the cardiotonic drug levosimendan

Cardiac dysfunction is a common complication in sepsis and is characterized by forward pump failure. Hallmarks of septic cardiomyopathy are decreased myofibrillar contractility and reduced Ca(2+) sensitivity but it is still not clear whether reduced pump efficiency is predominantly a diastolic impairment. Moreover, a comprehensive picture of upstream Ca(2+) handling mechanisms and downstream myosin biomechanical parameters is still missing. Ca(2+)-sensitizing agents in sepsis may be promising but mechanistic insights for drugs like levosimendan are scarce. Here, we used an endotoxemic LPS rat model to study mechanisms of sepsis on in vivo hemodynamics, multicellular myofibrillar Ca(2+) sensitivity, in vitro cellular Ca(2+) homeostasis and subcellular actomyosin interaction with intracardiac catheters, force transducers, confocal Fluo-4 Ca(2+) recordings in paced cardiomyocytes, and in vitro motility assay, respectively. Left ventricular ejection fraction and myofibrillar Ca(2+) sensitivity were depressed in LPS animals but restored by levosimendan. Diastolic Ca(2+) transient kinetics was slowed down by LPS but ameliorated by levosimendan. Selectively blocking intracellular and sarcolemmal Ca(2+) extrusion pathways revealed minor contribution of sarcoplasmic reticulum Ca(2+) ATPase (SERCA) to Ca(2+) transient diastole in LPS-evoked sepsis but rather depressed Na(+)/Ca(2+) exchanger and plasmalemmal Ca(2+) ATPase. This was mostly compensated by levosimendan. Actin sliding velocities were depressed in myosin heart extracts from LPS rats. We conclude that endotoxemia specifically impairs sarcolemmal diastolic Ca(2+) extrusion pathways resulting in intracellular diastolic Ca(2+) overload. Levosimendan, apart from stabilizing Ca(2+)-troponin C complexes, potently improves cellular Ca(2+) extrusion in the septic heart.

Effects of cytokines on the contractility of cultured cardiac myocytes

Cardiac impairment is a major complication in immunotherapy. In order to investigate whether the cardiac complications are due to directly cardiodepressant cytokine effects, the contractility of heart cells in culture under immune mediator exposition was studied. The beat frequency and inotropy of spontaneously contracting cultured cardiac myocytes was determined in a microscope perfusion system equipped with computer image analysis devices. Under control conditions, the perfused cardiac myocytes were rhythmically and synchronously beating for many hours. Perfusion with the cytokines (IL-1, IL-2, IL-3, TNF) induced arrhythmias resulting in a complete cessation of spontaneous contractions and a severe loss of myocyte inotropy. The effects were concentration-dependent and reversible. Our results indicate a direct toxic interference of the interleukins and TNF with the contractile function of cultured cardiac myocytes.