Prognostic significance of left ventricular diastolic function in burn patients

Impairment of μ-calpain activation by rhTNFR:Fc reduces severe burn-induced membrane disruption in the heart

Stress cardiomyopathy is a major clinical complication after severe burn. Multiple upstream initiators have been identified; however, the downstream targets are not fully understood. This study assessed the role of the plasma membrane in this process and its relationship with the protease μ-calpain and tumor necrosis factor-alpha (TNF-α). Here, third-degree burn injury of approximately 40% of the total body surface area was established in rats. Plasma levels of LDH and cTnI and cardiac cell apoptosis increased at 0.5 h post burn, reached a peak at 6 h, and gradually declined at 24 h. This effect correlated well with not only the disruption of cytoskeletal proteins, including dystrophin and ankyrin-B, but also with the activation of μ-calpain, as indicated by the cleaved fragments of α-spectrin and membrane recruitment of the catalytic subunit CAPN1. More importantly, these alterations were diminished by blocking calpain activity with MDL28170. Burn injury markedly increased the cellular uptake of Evans blue, indicating membrane integrity disruption, and this effect was also reversed by MDL28170. Compared with those in the control group, cardiac cells in the burn plasma-treated group were more prone to damage, as indicated by a marked decrease in cell viability and increases in LDH release and apoptosis. Of note, these alterations were mitigated by CAPN1 siRNA. Moreover, after neutralizing TNF-α with rhTNFR:Fc, calpain activity was blocked, and heart function was improved. In conclusion, we identified μ-calpain as a trigger for severe burn-induced membrane disruption in the heart and provided evidence for the application of rhTNFR:Fc to inhibit calpain for cardioprotection.

Cardiac Dysfunction in Severely Burned Patients: Current Understanding of Etiology, Pathophysiology, and Treatment

Patients who experience severe burn injuries face a massive inflammatory response resulting in hemodynamic and cardiovascular complications. Even after immediate and appropriate resuscitation, removal of burn eschar and covering of open areas, burn patients remain at high risk for serious morbidity and mortality. As a result of the massive fluid shifts following the initial injury, along with large volume fluid resuscitation, the cardiovascular system is critically affected. Further, increased inflammation, catecholamine surge, and hypermetabolic syndrome impact cardiac dysfunction, which worsens outcomes of burn patients. This review aimed to summarize the current knowledge about the effect of burns on the cardiovascular system.A comprehensive search of the PubMed and Embase databases and manual review of articles involving effects of burns on the cardiovascular system was conducted.Many burn units use multimodal monitors (e.g., transpulmonary thermodilution) to assess hemodynamics and optimize cardiovascular function. Echocardiography is often used for additional evaluations of hemodynamically unstable patients to assess systolic and diastolic function. Due to its noninvasive character, echocardiography can be repeated easily, which allows us to follow patients longitudinally.The use of anabolic and anticatabolic agents has been shown to be beneficial for short- and long-term outcomes of burn survivors. Administration of propranolol (non-selective β-receptor antagonist) or oxandrolone (synthetic testosterone) for up to 12 months post-burn counteracts hypermetabolism during hospital stay and improves cardiac function.A comprehensive understanding of how burns lead to cardiac dysfunction and new therapeutic options could contribute to better outcomes in this patient population.

Transpulmonary Thermodilution Versus Transthoracic Echocardiography for Cardiac Output Measurements in Severely Burned Children

INTRODUCTION

Severe burns trigger a hyperdynamic state, necessitating accurate measurement of cardiac output (CO) for cardiovascular observation and guiding fluid resuscitation. However, it is unknown whether, in burned children, the increasingly popular transthoracic echocardiography (TTE) method of CO measurement is as accurate as the widely used transpulmonary thermodilution (TPTD) method.

PATIENTS AND METHODS

We retrospectively compared near-simultaneously performed CO measurements in severely burned children using TPTD with the Pulse index Continuous Cardiac Output (PiCCO) system or TTE. Outcomes were compared using t tests, multiple linear regression, and a Bland-Altman plot.

RESULTS

Fifty-four children (9 ± 5 years) with 68 ± 18% total body surface area burns were studied. An analysis of 105 data pairs revealed that PiCCO yielded higher CO measurements than TTE (190 ± 39% vs. 150 ± 50% predicted values; P < 0.01). PiCCO- and TTE-derived CO measurements correlated moderately well (R = 0.54, P < 0.01). A Bland-Altman plot showed a mean bias of 1.53 L/min with a 95% prediction interval of 4.31 L/min.

CONCLUSIONS

TTE-derived estimates of CO may underestimate severity of the hyperdynamic state in severely burned children. We propose using the PiCCO system for objective cardiovascular monitoring and to guide goal-directed fluid resuscitation in this population.

Pre-Clinical Tests of an Integrated CMOS Biomolecular Sensor for Cardiac Diseases Diagnosis

Coronary artery disease and its related complications pose great threats to human health. In this work, we aim to clinically evaluate a CMOS field-effect biomolecular sensor for cardiac biomarkers, cardiac-specific troponin-I (cTnI), N-terminal prohormone brain natriuretic peptide (NT-proBNP), and interleukin-6 (IL-6). The CMOS biosensor is implemented via a standard commercialized 0.35 μm CMOS process. To validate the sensing characteristics, in buffer conditions, the developed CMOS biosensor has identified the detection limits of IL-6, cTnI, and NT-proBNP as being 45 pM, 32 pM, and 32 pM, respectively. In clinical serum conditions, furthermore, the developed CMOS biosensor performs a good correlation with an enzyme-linked immuno-sorbent assay (ELISA) obtained from a hospital central laboratory. Based on this work, the CMOS field-effect biosensor poses good potential for accomplishing the needs of a point-of-care testing (POCT) system for heart disease diagnosis.

Diastolic dysfunction in the critically ill patient

Left ventricular diastolic dysfunction is a common finding in critically ill patients. It is characterized by a progressive deterioration of the relaxation and the compliance of the left ventricle. Two-dimensional and Doppler echocardiography is a cornerstone in its diagnosis. Acute pulmonary edema associated with hypertensive crisis is the most frequent presentation of diastolic dysfunction critically ill patients. Myocardial ischemia, sepsis and weaning failure from mechanical ventilation also may be associated with diastolic dysfunction. The treatment is based on the reduction of pulmonary congestion and left ventricular filling pressures. Some studies have found a prognostic role of diastolic dysfunction in some diseases such as sepsis. The present review aims to analyze thoroughly the echocardiographic diagnosis and the most frequent scenarios in critically ill patients in whom diastolic dysfunction plays a key role.

TNF-α down-regulates sarcoplasmic reticulum Ca²⁺ ATPase expression and leads to left ventricular diastolic dysfunction through binding of NF-κB to promoter response element

AIMS

TNF-alpha (TNF-α) causes left ventricular diastolic dysfunction. Down-regulation of sarcoplasmic reticulum Ca(2+)-ATPase 2a protein (SERCA2a) expression is one of the major mechanisms underlying diastolic dysfunction. We investigated whether TNF-α modulates SERCA2a expression and alters cardiac diastolic function, and its detailed signalling pathway.

METHODS AND RESULTS

We used both in vitro cellular cardiomyocyte model and in vivo rat model to address this issue. We found that TNF-α decreased the levels of both SERCA2a mRNA and protein in the cardiomyocytes, with corresponding impairment of diastolic calcium reuptake, a cellular phenotype of cardiac diastolic function. An ∼2 kb promoter of the SERCA2a gene (atp2a2) along with its serial deletions was cloned into the luciferase reporter system. TNF-α significantly decreased the promoter activity, and truncation of the SERCA2a gene promoter with the putative nuclear factor kappa-B (NF-κB) response element abolished TNF-α-induced SERCA2a gene suppression. Chromatin immunoprecipitation and gel retardation also confirmed the binding of NF-κB to this putative-binding site. TNF-α increased the phosphorylation of IKK and the degradation of IκB, resulted in NF-κB nuclear translocation, and decreased SERCA2a gene promoter activity. This process was attenuated by NF-κB blockers and simvastatin. In the in vivo rat model, lipopolysaccharide treatment significantly elevated the serum TNF-α level, as well as phosphorylation of IKK, resulting in a decrease in myocardial SERCA2a expression, diastolic calcium reuptake, and diastolic dysfunction. Oral treatment with simvastatin led to an increase in SERCA2a expression, alleviation, and prevention of the diastolic dysfunction.

CONCLUSIONS

TNF-α suppresses SERCA2a gene expression via the IKK/IκB/NF-κB pathway and binding of NF-κB to the SERCA2a gene promoter, and its effect is blocked by simvastatin, demonstrating the potential therapeutic effect of statins in treating inflammation-related diastolic dysfunction.

14-3-3γ protein attenuates lipopolysaccharide-induced cardiomyocytes injury through the Bcl-2 family/mitochondria pathway

Previous studies have indicated that 14-3-3γ is upregulated by stress in LPS-induced cardiovascular injury. In this study, we investigated the interaction of 14-3-3γ and Bcl-2 family members in the control of the mitochondrial permeability transition (MPT) to test the hypothesis that abundant levels of 14-3-3γ can protect against LPS-induced injury via a Bcl-2 family/mitochondria pathway. The cardiomyocytes were treated with LPS (1mg l(-1)) for 6h; the interaction between 14-3-3γ and phospho-Bad(S112) was detected by co-immunoprecipitation (co-IP); the levels of Bcl-2 family members in the cytosolic and mitochondrial fractions were examined by Western blot; the apoptosis and mitochondrial membrane potential (ΔΨm) were detected by flow cytometry; and the mitochondrial permeability transition pore (mPTP) opening was tested by mitochondrial swelling. Our results revealed that LPS treatment results in cardiomyocyte injury, and these effects were significantly attenuated by pFLAG-14-3-3γ. Moreover, LPS treatment induced Bax translocation to the mitochondria, ΔΨm loss, mitochondrial swelling, and cytochrome c release, and pFLAG-14-3-3γ reversed these effects induced by LPS. Moreover, overexpressed 14-3-3γ protein could assist Bad(S112) phosphorylation and interact with it to form a complex, which might result in the disassociation of Bcl-2 from the Bad/Bcl-2 complex and its translocation from the cytosol to the mitochondria. Our data firstly confirmed that a high level of 14-3-3γ protects against LPS-induced cardiomyocyte injury likely through a pathway associated with the regulation of the subcellular localizations of Bcl-2 and Bad that results in the prevention of mPTP opening, the maintenance of ΔΨm, and ultimately the inhibition of apoptosis.

Estrogen-provided cardiac protection following burn trauma is mediated through a reduction in mitochondria-derived DAMPs

Mitochondria-derived danger-associated molecular patterns (DAMPs) play important roles in sterile inflammation after acute injuries. This study was designed to test the hypothesis that 17β-estradiol protects the heart via suppressing myocardial mitochondrial DAMPs after burn injury using an animal model. Sprague-Dawley rats were given a third-degree scald burn comprising 40% total body surface area (TBSA). 17β-Estradiol, 0.5 mg/kg, or control vehicle was administered subcutaneously 15 min following burn. The heart was harvested 24 h postburn. Estradiol showed significant inhibition on the productivity of H2O2 and oxidation of lipid molecules in the mitochondria. Estradiol increased mitochondrial antioxidant defense via enhancing the activities and expression of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Estradiol also protected mitochondrial respiratory function and structural integrity. In parallel, estradiol remarkably decreased burn-induced release of mitochondrial cytochrome c and mitochondrial DNA (mtDNA) into cytoplasm. Further, estradiol inhibited myocardial apoptosis, shown by its suppression on DNA laddering and downregulation of caspase 1 and caspase 3. Estradiol's anti-inflammatory effect was demonstrated by reduction in systemic and cardiac cytokines (TNF-α, IL-1β, and IL-6), decrease in NF-κB activation, and attenuation of the expression of inflammasome component ASC in the heart of burned rats. Estradiol-provided cardiac protection was shown by reduction in myocardial injury marker troponin-I, amendment of heart morphology, and improvement of cardiac contractility after burn injury. Together, these data suggest that postburn administration of 17β-estradiol protects the heart via an effective control over the generation of mitochondrial DAMPs (mtROS, cytochrome c, and mtDNA) that incite cardiac apoptosis and inflammation.

Connective tissue growth factor and cardiac diastolic dysfunction: human data from the Taiwan diastolic heart failure registry and molecular basis by cellular and animal models

AIMS

Connective tissue growth factor (CTGF) is an emerging marker for tissue fibrosis. We investigated the association between CTGF and cardiac diastolic function using cellular and animal models and clinical human data.

METHODS AND RESULTS

A total of 125 patients with a diagnosis of diastolic heart failure (DHF) were recruited from 1283 patients of the Taiwan Diastolic Heart Failure Registry. The severity of DHF was determined by tissue Doppler imaging (E/e'). Cardiac magnetic resonance imaging (CMRI) was used to evaluate myocardial fibrosis in some of the patients (n = 25). Stretch of cardiomyocytes on a flexible membrane base serves as a cellular phenotype of cardiac diastolic dysfunction (DD). A canine model of DD was induced by aortic banding. A significant correlation was found between plasma CTGF and E/e' in DHF patients. The severity of cardiac fibrosis evaluated by CMRI also correlated with CTGF. In the cell model, stretch increased secretion of CTGF from cardiomyocytes. In the canine model, myocardial tissue CTGF expression and fibrosis significantly increased after 2 weeks of aortic banding. Notably, the expression of CTGF paralleled the severity of LV DD (r = 0.40, P < 0.001 for E/e') and haemodynamic changes (r = 0.80, P < 0.001). After adjusting for confounding factors, CTGF levels still correlated with diastolic parameters in both human and canine models (human plasma CTGF, P < 0.001; canine tissue CTGF, P = 0.04).

CONCLUSION

Plasma CTGF level correlated with the severity of DD and tissue fibrosis in DHF patients. The mechanism may be through myocardial stretch. Our study indicated that CTGF may serve as an early marker for DHF.

Antithrombin attenuates myocardial dysfunction and reverses systemic fluid accumulation following burn and smoke inhalation injury: a randomized, controlled, experimental study

Introduction

We hypothesized that maintaining physiological plasma levels of antithrombin attenuates myocardial dysfunction and inflammation as well as vascular leakage associated with burn and smoke inhalation injury. Therefore, the present prospective, randomized experiment was conducted using an established ovine model.

Methods

Following 40% of total body surface area, third degree flame burn and 4 × 12 breaths of cold cotton smoke, chronically instrumented sheep were randomly assigned to receive an intravenous infusion of 6 IU/kg/h recombinant human antithrombin (rhAT) or normal saline (control group; n = 6 each). In addition, six sheep were designated as sham animals (not injured, continuous infusion of vehicle). During the 48 h study period the animals were awake, mechanically ventilated and fluid resuscitated according to standard formulas.

Results

Compared to the sham group, myocardial contractility was severely impaired in control animals, as suggested by lower stroke volume and left ventricular stroke work indexes. As a compensatory mechanism, heart rate increased, thereby increasing myocardial oxygen consumption. In parallel, myocardial inflammation was induced via nitric oxide production, neutrophil accumulation (myeloperoxidase activity) and activation of the p38-mitogen-activated protein kinase pathway resulting in cytokine release (tumor necrosis factor-alpha, interleukin-6) in control vs. sham animals. rhAT-treatment significantly attenuated these inflammatory changes leading to a myocardial contractility and myocardial oxygen consumption comparable to sham animals. In control animals, systemic fluid accumulation progressively increased over time resulting in a cumulative positive fluid balance of about 4,000 ml at the end of the study period. Contrarily, in rhAT-treated animals there was only an initial fluid accumulation until 24 h that was reversed back to the level of sham animals during the second day.

Conclusions

Based on these findings, the supplementation of rhAT may represent a valuable therapeutic approach for cardiovascular dysfunction and inflammation after burn and smoke inhalation injury.