Sepsis-induced myocardial depression is associated with transcriptional changes in energy metabolism and contractile related genes: a physiological and gene expression-based approach

Mitochondrial abnormalities in septic cardiomyopathy

Septic cardiomyopathy is a common complication in patients with sepsis, and is one of the indicators of poor prognosis. Its pathogenesis is complex, involving calcium ion imbalance in cardiomyocytes, nitric oxide (NO) synthesis disorder, mitochondrial abnormalities and immune inflammatory reaction, especially mitochondrial abnormalities. In this paper, the mechanism of mitochondrial abnormalities causing septic cardiomyopathy was discussed from the aspects of mitochondrial structure change, mitochondrial energy metabolism disorder, redox imbalance, mitochondrial calcium overload, mitochondrial biosynthesis and autophagy abnormalities.

Utilizing omics technologies in the investigation of sepsis-induced cardiomyopathy

Sepsis-induced cardiomyopathy (SIC) is a common and high-mortality complication among critically ill patients. Uncertainties persist regarding the pathogenesis, pathophysiology, and diagnosis of SIC, underscoring the necessity to investigate potential biological mechanisms. With the rise of omics technologies, leveraging their high throughput and big data advantages, a systems biology perspective is employed to study the biological processes of SIC. This approach aids in gaining a better understanding of the disease's onset, progression, and outcomes, ultimately providing improved guidance for clinical practices. This review summarizes the currently applied omics technologies, omics studies related to SIC, and relevant omics databases.

S100A9 as a Key Myocardial Injury Factor Interacting with ATP5 Exacerbates Mitochondrial Dysfunction and Oxidative Stress in Sepsis-Induced Cardiomyopathy

Purpose

Sepsis-induced cardiomyopathy (SICM) is a prevalent cardiac dysfunction caused by sepsis. Mitochondrial dysfunction is a crucial pathogenic factor associated with adverse cardiovascular adverse events; however, research on SICM remains insufficient.

Methods

To investigate the factors contributing to the pathological progression of SICM, we performed a comprehensive analysis of transcriptomic data from the GEO database using bioinformatics and machine learning techniques. CRISPR-Cas9 S100A9 knockout mice and primary cardiomyocytes were exposed to lipopolysaccharide to simulate SICM. Transcriptome analysis and mass spectrometry of primary cardiomyocytes were used to determine the potential pathogenic mechanisms of S100A9. The mitochondrial ultrastructure and mitochondrial membrane potential (MMP) were detected using transmission electron microscopy and flow cytometry, respectively. Pink1/Parkin and Drp1 proteins were detected using Western blotting to evaluate mitochondrial autophagy and division. The mtDNA and mRNA levels of mitochondrial transcription factors and synthases were evaluated using real-time polymerase chain reaction.

Results

Bioinformatics analysis identified 12 common differentially expressed genes, including SERPINA3N, LCN2, MS4A6D, LRG1, OSMR, SOCS3, FCGR2b, S100A9, S100A8, CASP4, ABCA8A, and NFKBIZ. Significant S100A9 upregulation was closely associated with myocardial injury exacerbation and cardiac function deterioration. GSEA revealed that myocardial contractile function, oxidative stress, and mitochondrial function were significantly affected by S100A9. Knocking out S100A9 alleviates the inflammatory response and mitochondrial dysfunction. The interaction of S100A9 with ATP5 enhanced mitochondrial division and autophagy, inhibited MMP and ATP synthesis, and induced oxidative stress, which are related to the Nlrp3-Nfkb-Caspase1 and Drp1-Pink1-Parkin signaling pathways. The expression of mitochondrial transcription factors (TFAM and TFBM) and ATP synthetases (ATP6 and ATP8, as well as COX1, COX2, and COX3) was further suppressed by S100A9 in SICM. Targeted S100A9 inhibition by paquinimod partially reversed myocardial mitochondrial dysfunction and oxidative stress.

Conclusion

The interaction of S100A9 with ATP5 exacerbates myocardial damage in sepsis by inducing mitochondrial dysfunction and oxidative stress.

RIGHT VENTRICULAR DYSFUNCTION IN SEPSIS: AN UPDATED NARRATIVE REVIEW

ABSTRACT

Sepsis is a multisystem disease process, which constitutes a significant public health challenge and is associated with high morbidity and mortality. Among other systems, sepsis is known to affect the cardiovascular system, which may manifest as myocardial injury, arrhythmias, refractory shock, and/or septic cardiomyopathy. Septic cardiomyopathy is defined as the reversible systolic and/or diastolic dysfunction of one or both ventricles. Left ventricle dysfunction has been extensively studied in the past, and its prognostic role in patients with sepsis is well documented. However, there is relatively scarce literature on right ventricle (RV) dysfunction and its role. Given the importance of timely detection of septic cardiomyopathy and its bearing on prognosis of patients, the role of RV dysfunction has come into renewed focus. Hence, through this review, we sought to describe the pathophysiology of RV dysfunction in sepsis and what have we learnt so far about its multifactorial nature. We also elucidate the roles of different biomarkers for its detection and prognosis, along with appropriate management of such patient population.

DJ-1 Deficiency Protects against Sepsis-Induced Myocardial Depression

Oxidative stress is considered one of the early underlying contributors of sepsis-induced myocardial depression. DJ-1, also known as PARK7, has a well-established role as an antioxidant. We have previously shown, in a clinically relevant model of polymicrobial sepsis, DJ-1 deficiency improved survival and bacterial clearance by decreasing ROS production. In the present study, we investigated the role of DJ-1 in sepsis-induced myocardial depression. Here we compared wildtype (WT) with DJ-1 deficient mice at 24 and 48 h after cecal ligation and puncture (CLP). In WT mice, DJ-1 was increased in the myocardium post-CLP. DJ-1 deficient mice, despite enhanced inflammatory and oxidative responses, had an attenuated hypertrophic phenotype, less apoptosis, improved mitochondrial function, and autophagy, that was associated with preservation of myocardial function and improved survival compared to WT mice post-CLP. Collectively, these results identify DJ-1 as a regulator of myocardial function and as such, makes it an attractive therapeutic target in the treatment of early sepsis-induced myocardial depression.

Sex-specific differences in cardiac function, inflammation and injury during early polymicrobial sepsis

BACKGROUND

Sex differences in sepsis are underexplored and incompletely understood. Cardiac function in early sepsis is pivotal in determining survival; hyperdynamic left ventricular ejection fraction is associated with higher mortality. Female sex may be cardioprotective, but variable experimental findings have not controlled for hypovolaemia. Sex-specific local cardiac versus peripheral inflammation in causing cardiovascular dysfunction also remain unclear. We therefore examined whether there are sex-specific differences in cardiac function in early sepsis, controlling for volaemic status and sex-specific differences in the peripheral inflammatory response initiated by tumour necrosis factor (TNFα).

METHODS

We used an experimental polymicrobial sepsis (faecal slurry) model titrated to minimise hypovolaemia as a confounding factor. We quantified cardiac function (transthoracic cardiac echocardiography) 1 week before, and 18 h after, sepsis. Cardiac injury (troponin I), inflammation and immune cell infiltration (flow cytometry) were quantified in naïve and septic female and male mice 18 h after sepsis. To evaluate the sex-specific influence of TNFα derived from peripheral leukocytes, we repeated the experiments in iRHOM2^-/- mice that are unable to shed TNFα exclusively from circulating leucocytes.

RESULTS

Serum troponin I increased to 1.39 ± 0.38 ng mL^-1 (from undetectable levels in controls) 18 h after onset of normovolaemic sepsis to a similar extent in both sexes. Stroke volume in male mice increased by 8 µL [(3-13); p = 0.004], compared to individualised pre-sepsis values. By contrast, stroke volume remained at baseline levels in females [mean difference: 4 µL (- 1 to 9)]. Messenger RNA levels of markers for cardiac injury/inflammation after sepsis (real-time polymerase-chain reaction) were elevated in male wild-type mice compared to female wild types (n = 10/sex), with higher cardiac mRNA levels of atrial natriuretic peptide, inflammation (TNFα) and oxidative stress (superoxide dismutase-1), although serum troponin I values were similarly elevated. Flow cytometry analysis of cardiac tissue showed doubling of CD4 + leukocyte infiltration in male mice. Sex-specific cardiac physiologic differences were similar in iRHOM2^-/- mice that are unable to shed TNFα exclusively from leucocytes.

CONCLUSIONS

In early normovolaemic polymicrobial sepsis, a relative hyperdynamic response develops in male mice. Myocardial stress/injury after early sepsis is limited in females, with less cardiac infiltration of CD4 + leukocytes but independent of shedding of TNFα from peripheral circulating leukocytes.

An Overview on Mitochondrial-Based Therapies in Sepsis-Related Myocardial Dysfunction: Mitochondrial Transplantation as a Promising Approach

Sepsis is defined as a life-threatening organ failure due to dysregulated host response to infection. Despite current advances in our knowledge about sepsis, it is still considered as a major global health challenge. Myocardial dysfunction is a well-defined manifestation of sepsis which is related to worse outcomes in septic patients. Given that the heart is a mitochondria-rich organ and the normal function of mitochondria is essential for successful modulation of septic response, the contribution of mitochondrial damage in sepsis-related myocardial dysfunction has attracted the attention of many scientists. It is widely accepted that mitochondrial damage is involved in sepsis-related myocardial dysfunction; however, effective and potential treatment modalities in clinical setting are still lacking. Mitochondrial-based therapies are potential approaches in sepsis treatment. Although various therapeutic strategies have been used for mitochondrial function improvement, their effects are limited when mitochondria undergo irreversible alterations under septic challenge. Therefore, application of more effective approaches such as mitochondrial transplantation has been suggested. This review highlights the crucial role of mitochondrial damage in sepsis-related myocardial dysfunction, then provides an overview on mitochondrial-based therapies and current approaches to mitochondrial transplantation as a novel strategy, and proposes future directions for more researches in this field.

The Effect of Sepsis on Myocardial Function: A Review of Pathophysiology, Diagnostic Criteria, and Treatment

Sepsis remains a worldwide challenge for physicians with many patients admitted to ICUs with septic shock. Septic shock management involves targeted treatment to control infections, reduce end-organ damage, and reverse the injury. Sepsis-induced myocardial dysfunction or septic cardiomyopathy remains an avenue to be explored with regard to underlying pathophysiology and definite treatment guidelines. This article has compiled various studies to explain the possible mechanisms involved in the development of septic cardiomyopathy and the existing diagnostic criteria including radiological and laboratory tests to assess septic cardiomyopathy. Furthermore, the article highlights management options currently available for physicians dealing with myocardial dysfunction secondary to sepsis.

Induction and deduction in sepsis-induced cardiomyopathy: five typical categories

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The heart is one of the most important oxygen delivery organs, and dysfunction significantly increases the mortality of the body. Hence, the heart has been studied in sepsis for over half a century. However, the definition of sepsis-induced cardiomyopathy is not unified yet, and the conventional conception seems outdated: left ventricular systolic dysfunction (LVSD) along with enlargement of the left ventricle, recovering in 7 to 10 days. With the application of echocardiography in intensive care units, not only LVSD but also left ventricular diastolic dysfunction, right ventricular dysfunction, and even diffuse ventricular dysfunction have been seen. The recognition of sepsis-induced cardiomyopathy is gradually becoming complete, although our understanding of it is not deep, which has made the diagnosis and treatment stagnate. In this review, we summarize the research on sepsis-induced cardiomyopathy. Women and young people with septic cardiomyopathy are more likely to have LVSD, which may have the same mechanism as stress cardiomyopathy. Elderly people with ischemic cardiomyopathy and hypertension tend to have left ventricular diastolic dysfunction. Patients with mechanical ventilation, acute respiratory distress syndrome or other complications of increased right ventricular afterload mostly have right ventricular dysfunction. Diffuse cardiac dysfunction has also been shown in some studies; patients with mixed or co-existing cardiac dysfunction are more common, theoretically. Thus, understanding the pathophysiology of sepsis-induced cardiomyopathy from the perspective of critical care echocardiography is essential.

PINK1 contained in huMSC-derived exosomes prevents cardiomyocyte mitochondrial calcium overload in sepsis via recovery of mitochondrial Ca2+ efflux

Background

Sepsis is a systemic inflammatory response to a local severe infection that may lead to multiple organ failure and death. Previous studies have shown that 40–50% of patients with sepsis have diverse myocardial injuries and 70 to 90% mortality rates compared to 20% mortality in patients with sepsis without myocardial injury. Therefore, uncovering the mechanism of sepsis-induced myocardial injury and finding a target-based treatment are immensely important.

Objective

The present study elucidated the mechanism of sepsis-induced myocardial injury and examined the value of human umbilical cord mesenchymal stem cells (huMSCs) for protecting cardiac function in sepsis.

Methods

We used cecal ligation and puncture (CLP) to induce sepsis in mice and detect myocardial injury and cardiac function using serological markers and echocardiography. Cardiomyocyte apoptosis and heart tissue ultrastructure were detected using TdT-mediated dUTP Nick-End Labeling (TUNEL) and transmission electron microscopy (TEM), respectively. Fura-2 AM was used to monitor Ca²⁺ uptake and efflux in mitochondria. FQ-PCR and Western blotting detected expression of mitochondrial Ca²⁺ distribution regulators and PTEN-induced putative kinase 1 (PINK1). JC-1 was used to detect the mitochondrial membrane potential (Δψm) of cardiomyocytes.

Results

We found that expression of PINK1 decreased in mouse hearts during sepsis, which caused cardiomyocyte mitochondrial Ca²⁺ efflux disorder, mitochondrial calcium overload, and cardiomyocyte injury. In contrast, we found that exosomes isolated from huMSCs (huMSC-exo) carried Pink1 mRNA, which could be transferred to recipient cardiomyocytes to increase PINK1 expression. The reduction in cardiomyocyte mitochondrial calcium efflux was reversed, and cardiomyocytes recovered from injury. We confirmed the effect of the PINK1-PKA-NCLX axis on mitochondrial calcium homeostasis in cardiomyocytes during sepsis.

Conclusion

The PINK1-PKA-NCLX axis plays an important role in mitochondrial calcium efflux in cardiomyocytes. Therefore, PINK1 may be a therapeutic target to protect cardiomyocyte mitochondria, and the application of huMSC-exo is a promising strategy against sepsis-induced heart dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02325-6.

Paeoniflorin and Hydroxysafflor Yellow A in Xuebijing Injection Attenuate Sepsis-Induced Cardiac Dysfunction and Inhibit Proinflammatory Cytokine Production

Sepsis-induced myocardial dysfunction is a major contributor to the poor outcomes of septic shock. As an add-on with conventional sepsis management for over 15 years, the effect of Xuebijing injection (XBJ) on the sepsis-induced myocardial dysfunction was not well understood. The material basis of Xuebijing injection (XBJ) in managing infections and infection-related complications remains to be defined. A murine cecal ligation and puncture (CLP) model and cardiomyocytes in vitro culture were adopted to study the influence of XBJ on infection-induced cardiac dysfunction. XBJ significantly improved the survival of septic-mice and rescued cardiac dysfunction in vivo. RNA-seq revealed XBJ attenuated the expression of proinflammatory cytokines and related signalings in the heart which was further confirmed on the mRNA and protein levels. Xuebijing also protected cardiomyocytes from LPS-induced mitochondrial calcium ion overload and reduced the LPS-induced ROS production in cardiomyocytes. The therapeutic effect of XBJ was mediated by the combination of paeoniflorin and hydroxysafflor yellow A (HSYA) (C0127-2). C0127-2 improved the survival of septic mice, protected their cardiac function and cardiomyocytes while balancing gene expression in cytokine-storm-related signalings, such as TNF-α and NF-κB. In summary, Paeoniflorin and HSYA are key active compounds in XBJ for managing sepsis, protecting cardiac function, and controlling inflammation in the cardiac tissue partially by limiting the production of IL-6, IL-1β, and CXCL2.

Identification of mitochondrial function-associated lncRNAs in septic mice myocardium

The present study aimed to analyze long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in septic mice heart and to identify potential lncRNAs and mRNAs that be responsible for cardiac mitochondrial dysfunction during sepsis. Mice were treated with 10 mg/kg of lipopolysaccharides to induce sepsis. LncRNAs and mRNAs expression were evaluated by using lncRNA and mRNA microarray or real-time polymerase chain reaction technique. LncRNA-mRNA coexpression network assay, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed. The results showed that 1275 lncRNAs were differentially expressed in septic myocardium compared with those in the control group. A total of 2769 mRNAs were dysregulated in septic mice heart, most of which are mainly related to the process of inflammation, mitochondrial metabolism, oxidative stress, and apoptosis. Coexpression network analysis showed that 14 lncRNAs were highly correlated with 11 mitochondria-related differentially expressed mRNA. Among all lncRNAs and their cis-acting mRNAs, 41 lncRNAs-mRNA pairs (such as NONMMUG004378 and Apaf1 gene) were enriched in GO terms and KEGG pathways. In summary, we gained some specific lncRNAs and their potential target mRNAs that might be involved in mitochondrial dysfunction in septic myocardium. These findings provide a panoramic view of lncRNA and might allow developing new treatment strategies for sepsis.

Effect of landiolol on sex-related transcriptomic changes in the myocardium during sepsis

Objectives

The aims of this study are to better understand phenotypic differences between male and female rats during sepsis, to characterise the contribution of the beta1-adrenergic blocker landiolol to septic cardiomyopathy and to determine why landiolol induces divergent effects in males and females.

Methods

The myocardial transcriptional profiles in male and female Wistar rats were assessed after the induction of sepsis by cecal ligation and puncture and addition of landiolol.

Results

Our results showed major differences in the biological processes activated during sepsis in male and female rats. In particular, a significant decrease in processes related to cell organisation, contractile function, ionic transport and phosphoinositide-3-kinase/AKT (PI3K/AKT) signalling was observed only in males. The transcript of ATPase sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 3 (SERCA3) was sex-differently regulated. In males, landiolol reversed several signalling pathways dysregulated during sepsis. The expression level of genes encoding tubulin alpha 8 (TUBA8) and myosin heavy chain 7B (MYH7) contractile proteins, phosphatase 2 catalytic subunit alpha (PPP2CA), G protein-coupled receptor kinase 5 (GRK5) and A-kinase anchoring protein 6 (AKAP6) returned to their basal levels. In contrast, in females, landiolol had limited effects.

Conclusion

In males, landiolol reversed the expression of many genes that were deregulated in sepsis. Conversely, sepsis-induced deregulation of gene expression was less pronounced in females than in males, and was maintained in the landiolol-treated females. These findings highlight important sex-related differences and confirm previous observations on the important benefit of landiolol intake on cardiac function in male rats.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0263-0) contains supplementary material, which is available to authorized users.

Elevated plasma glypicans are associated with organ failure in patients with infection

Background

Increased vascular permeability is a key feature in the pathophysiology of sepsis and the development of organ failure. Shedding of the endothelial glycocalyx is increasingly being recognized as an important pathophysiological mechanism but at present it is unclear if glypicans contribute to this response. We hypothesized that plasma levels of glypicans (GPC) are elevated in patients with sepsis.

Methods

Plasma GPC 1–6 levels were measured by ELISA in 10 patients with sepsis and 10 healthy controls as an initial screening. Plasma GPC 1, 3, and 4 were further measured in a cohort of 184 patients with a clinically confirmed infection. Patients were divided into groups of those who had sepsis and those who had an infection without organ failure. To determine whether plasma glypicans could predict the development of organ failure, patients were further subdivided to those who had organ failure at enrolment and those who developed it after enrollment. The association of plasma GPC 1, 3, and 4 with organ failure and with various markers of inflammation, disease severity, and glycocalyx shedding was investigated.

Results

In the pilot study, only GPC 1, 3, and 4 were detectable in the plasma of sepsis patients. In the larger cohort, GPC 1, 3, and 4 levels were significantly higher (p < 0.001) in patients with sepsis than in those with infection without organ failure. GPC 1, 3, and 4 were significantly positively correlated with plasma levels of the disease severity markers C-reactive protein, lactate, procalcitonin, and heparin binding protein, and with the marker of glycocalyx degradation syndecan 1. They were significantly negatively correlated with plasma levels of the glycocalyx-protective factors apolipoprotein M and sphingosine-1-phosphate.

Conclusions

We show that GPC 1, 3, and 4 are elevated in plasma of patients with sepsis and correlate with markers of disease severity, systemic inflammation, and glycocalyx damage.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0216-z) contains supplementary material, which is available to authorized users.

Cardiac gene expression and function in a mouse model of community-acquired methicillin-resistant Staphylococcus aureus sepsis: Role of inflammatory caspases 1 and 11

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an important cause of invasive infections, including sepsis associated with myocardial dysfunction. Caspases 1 and 11, involved in activation of the inflammasome, have been shown to be critical in response to sepsis as well as myocardial dysfunction of numerous etiologies. We examined the survival, myocardial function, and production of inflammatory mediators in mice lacking caspases 1 and 11. Cas 1/11 KO mice demonstrated no significant difference in mortality or in cardiac shortening fraction relative to control mice. Cas 1/11 KO mice had significantly reduced upregulation of expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the heart relative to control mice after CA-MRSA infection, as well as reduced serum production of IL-1β, TNF-α, and IL-6, with no difference in IL-10 production. Other inflammatory mediators beyond IL-1β, TNF-α, and IL-6 may be involved in myocardial dysfunction in CA-MRSA sepsis.

The role of mitochondria in sepsis-induced cardiomyopathy

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Myocardial dysfunction, often termed sepsis-induced cardiomyopathy, is a frequent complication and is associated with worse outcomes. Numerous mechanisms contribute to sepsis-induced cardiomyopathy and a growing body of evidence suggests that bioenergetic and metabolic derangements play a central role in its development; however, there are significant discrepancies in the literature, perhaps reflecting variability in the experimental models employed or in the host response to sepsis. The condition is characterised by lack of significant cell death, normal tissue oxygen levels and, in survivors, reversibility of organ dysfunction. The functional changes observed in cardiac tissue may represent an adaptive response to prolonged stress that limits cell death, improving the potential for recovery. In this review, we describe our current understanding of the pathophysiology underlying myocardial dysfunction in sepsis, with a focus on disrupted mitochondrial processes.

Septic cardiomyopathy: The value of lactoferrin and CD15 as specific markers to corroborate a definitive diagnosis

Current scientific consensus about the physiopathology in the progression from severe sepsis to septic shock and death focuses on myocardial contractile dysfunction. Nevertheless, objective parameters to establish a pathological correlate of a fatal outcome are lacking; then a cause of death due to sepsis can remain an unsolved problem. We first reviewed all death cases recorded at our institutions during the period from 2007 until 2015. Then, we conducted a retrospective study of a selected autopsy series of people who had received "sepsis" as cause of death. Two pathologists re-examined the heart sections while the most suitable myocardial sample for each case was stained for immunohistochemistry with antibodies targeted for specific inflammatory-related molecules. We used specific antibodies for the following markers: alpha-smooth muscle actin (alpha-SMA); fibronectin; matrix metallopeptidase 9 (MMP-9); intercellular adhesion molecule 1 (ICAM-1); caspase-3; lactoferrin (LF); cluster differentiation 15 (CD15). The statistical significance of differences was assessed using student's t-test for unpaired data or non-parametric Mann-Whitney or Wilcoxon tests for skewed variables or one-way analysis of variance and post hoc Scheffe's test for continuous variables and Pearson's χ2-test for discrete variables. Linear regression analysis was used to determine the presence of a correlation between continuous variables. At our institutions, 2220 deaths have been recorded during the period study. Sepsis accounted as a cause of death for the 20% of total. We finally enrolled 56 cases; of these, only 20 were positive for microbiological analysis. At histological examination, clear inflammation was detectable in the 32% of cases; otherwise, immunohistochemical reaction showed a positive reaction for LF and CD15 in more than a half cases (56%). We still ignore all the underlying mechanisms of sepsis and all its pathophysiological connections with cardiac metabolism; in this sense, we aim to corroborate the diagnostic value of anti-LF and anti-CD15 staining for the post-mortem detection of myocardial inflammation.

Cytotoxicity of propofol in human induced pluripotent stem cell-derived cardiomyocytes

Purpose

Propofol infusion syndrome (PRIS) is a lethal condition caused by propofol overdose. Previous studies suggest that pathophysiological mechanisms underlying PRIS involve mitochondrial dysfunction; however, these mechanisms have not been fully elucidated. This study aimed to establish an experimental model of propofol-induced cytotoxicity using cultured human induced pluripotent stem cell (iPSC)-derived cardiomyocytes to determine the mechanisms behind propofol-induced mitochondrial dysfunction, and to evaluate the protective effects of coenzyme Q10 (CoQ10).

Methods

Human iPSC-derived cardiomyocytes were exposed to propofol (0, 2, 10, or 50 µg/ml) with or without 5 µM CoQ10. Mitochondrial function was assessed by measuring intracellular ATP, lactate concentrations in culture media, NAD⁺/NADH ratio, and the mitochondrial membrane potential. Propofol-induced cytotoxicity was evaluated by analysis of cell viability. Expression levels of genes associated with mitochondrial energy metabolism were determined by PCR. Intracellular morphological changes were analyzed by confocal microscopy.

Results

Treatment with 50 µg/ml propofol for 48 h reduced cell viability. High concentrations of propofol (≥ 10 µg/ml) induced mitochondrial dysfunction accompanied by downregulation of gene expression of PGC-1alpha and its downstream targets (NDUFS8 and SDHB, which are involved in the respiratory chain reaction; and CPT1B, which regulates beta-oxidation). Cardiomyocytes co-treated with 5 µM CoQ10 exhibited resistance to propofol-induced toxicity through recovery of gene expression.

Conclusions

Propofol-induced cytotoxicity in human iPSC-derived cardiomyocytes may be associated with mitochondrial dysfunction via downregulation of PGC-1alpha-regulated genes associated with mitochondrial energy metabolism. Co-treatment with CoQ10 protected cardiomyocytes from propofol-induced cytotoxicity.

Widespread Down-Regulation of Cardiac Mitochondrial and Sarcomeric Genes in Patients With Sepsis

OBJECTIVES

The mechanism(s) for septic cardiomyopathy in humans is not known. To address this, we measured messenger RNA alterations in hearts from patients who died from systemic sepsis, in comparison to changed messenger RNA expression in nonfailing and failing human hearts.

DESIGN

Identification of genes with altered abundance in septic cardiomyopathy, ischemic heart disease, or dilated cardiomyopathy, in comparison to nonfailing hearts.

SETTING

ICUs at Barnes-Jewish Hospital, St. Louis, MO.

PATIENTS

Twenty sepsis patients, 11 ischemic heart disease, nine dilated cardiomyopathy, and 11 nonfailing donors.

INTERVENTIONS

None other than those performed as part of patient care.

MEASUREMENTS AND MAIN RESULTS

Messenger RNA expression levels for 198 mitochondrially localized energy production components, including Krebs cycle and electron transport genes, decreased by 43% ± 5% (mean ± SD). Messenger RNAs for nine genes responsible for sarcomere contraction and excitation-contraction coupling decreased by 43% ± 4% in septic hearts. Surprisingly, the alterations in messenger RNA levels in septic cardiomyopathy were both distinct from and more profound than changes in messenger RNA levels in the hearts of patients with end-stage heart failure.

CONCLUSIONS

The expression profile of messenger RNAs in the heart of septic patients reveals striking decreases in expression levels of messenger RNAs that encode proteins involved in cardiac energy production and cardiac contractility and is distinct from that observed in patients with heart failure. Although speculative, the global nature of the decreases in messenger RNA expression for genes involved in cardiac energy production and contractility suggests that these changes may represent a short-term adaptive response of the heart in response to acute change in cardiovascular homeostasis.

Cyclosporine A attenuates cardiac dysfunction induced by sepsis via inhibiting calcineurin and activating AMPK signaling

The aim of the present study was to investigate whether cyclosporine A (CSA) improved cardiac dysfunction at an early stage of sepsis. Male Wistar rats were randomly divided into the following three groups: the sham‑operated control group, the cecal ligation puncture (CLP) procedure‑induced sepsis group and the CSA intervention group. Cecal ligation was performed to generate a sepsis model. At different time points (2, 6, 12, 24 and 72 h) following sepsis induction, blood pressure, cardiac function, and non‑esterified free fatty acid (NEFA) levels in the plasma and myocardia were measured, and the expression levels of components associated with the AMP‑activated protein kinase (AMPK)‑acetyl CoA carboxylase (ACC)‑carnitine palmitoyl transferase 1 (CPT1) signaling pathway were compared among the three groups. Sepsis induced a decrease in blood pressure and cardiac function at 24 h following sepsis induction in the CLP group, and CSA treatment ameliorated these pathophysiological alterations. In addition, rats in the CLP group exhibited significant increases in calcineurin activity and NEFA accumulation in the heart when compared with those in the sham group. These effects were attenuated by CSA treatment. Mechanistically, the activity of the AMPK‑ACC‑CPT1 pathway was enhanced by CSA treatment. The present study revealed that CSA treatment increases cardiac function at an early stage of sepsis in rats. This treatment partially suppresses calcineurin activity while activating the AMPK‑TCC‑CPT1 pathway.

Sepsis-induced cardiomyopathy

Myocardial dysfunction is one of the main predictors of poor outcome in septic patients, with mortality rates next to 70%. During the sepsis-induced myocardial dysfunction, both ventricles can dilate and diminish its ejection fraction, having less response to fluid resuscitation and catecholamines, but typically is assumed to be reversible within 7-10 days. In the last 30 years, It´s being subject of substantial research; however no explanation of its etiopathogenesis or effective treatment have been proved yet. The aim of this manuscript is to review on the most relevant aspects of the sepsis-induced myocardial dysfunction, discuss its clinical presentation, pathophysiology, etiopathogenesis, diagnostic tools and therapeutic strategies proposed in recent years.

Early functional and transcriptomic changes in the myocardium predict outcome in a long-term rat model of sepsis

Myocardial function is depressed in sepsis and is an important prognosticator in the human condition. Using echocardiography in a long-term fluid-resuscitated Wistar rat model of faecal peritonitis we investigated whether depressed myocardial function could be detected at an early stage of sepsis and, if so, whether the degree of depression could predict eventual outcome. At 6 h post-insult, a stroke volume <0.17 ml prognosticated 3-day mortality with positive and negative predictive values of 93 and 80%, respectively. Subsequent fluid loading studies demonstrated intrinsic myocardial depression with poor-prognosis animals tolerating less fluid than either good-prognosis or sham-operated animals. Cardiac gene expression analysis at 6 h detected 527 transcripts significantly up- or down-regulated by the septic process, including genes related to inflammatory and cell cycle pathways. Predicted mortality was associated with significant differences in transcripts of genes expressing proteins related to the TLR2/MyD88 (Toll-like receptor 2/myeloid differentiation factor 88) and JAK/STAT (Janus kinase/signal transducer and activator of transcription) inflammatory pathways, β-adrenergic signalling and intracellular calcium cycling. Our findings highlight the presence of myocardial depression in early sepsis and its prognostic significance. Transcriptomic analysis in heart tissue identified changes in signalling pathways that correlated with clinical dysfunction. These pathways merit further study to both better understand and potentially modify the disease process.

Mechanisms of cardiac and renal dysfunction in patients dying of sepsis

RATIONALE

The mechanistic basis for cardiac and renal dysfunction in sepsis is unknown. In particular, the degree and type of cell death is undefined.

OBJECTIVES

To evaluate the degree of sepsis-induced cardiomyocyte and renal tubular cell injury and death.

METHODS

Light and electron microscopy and immunohistochemical staining for markers of cellular injury and stress, including connexin-43 and kidney-injury-molecule-1 (Kim-1), were used in this study.

MEASUREMENTS AND MAIN RESULTS

Rapid postmortem cardiac and renal harvest was performed in 44 septic patients. Control hearts were obtained from 12 transplant and 13 brain-dead patients. Control kidneys were obtained from 20 trauma patients and eight patients with cancer. Immunohistochemistry demonstrated low levels of apoptotic cardiomyocytes (<1-2 cells per thousand) in septic and control subjects and revealed redistribution of connexin-43 to lateral membranes in sepsis (P < 0.020). Electron microscopy showed hydropic mitochondria only in septic specimens, whereas mitochondrial membrane injury and autophagolysosomes were present equally in control and septic specimens. Control kidneys appeared relatively normal by light microscopy; 3 of 20 specimens showed focal injury in approximately 1% of renal cortical tubules. Conversely, focal acute tubular injury was present in 78% of septic kidneys, occurring in 10.3 ± 9.5% and 32.3 ± 17.8% of corticomedullary-junction tubules by conventional light microscopy and Kim-1 immunostains, respectively (P < 0.01). Electron microscopy revealed increased tubular injury in sepsis, including hydropic mitochondria and increased autophagosomes.

CONCLUSIONS

Cell death is rare in sepsis-induced cardiac dysfunction, but cardiomyocyte injury occurs. Renal tubular injury is common in sepsis but presents focally; most renal tubular cells appear normal. The degree of cell injury and death does not account for severity of sepsis-induced organ dysfunction.

Effects of tetramethylpyrazine on cardiac function and mortality rate in septic rats

OBJECTIVE

To study the effects of tetramethylpyrazine (TMP) on cardiac function and mortality rate in septic rats.

METHODS

Fifty male Sprague-Dawley rats were randomized into a sham-operation group (sham group, n=10), normal saline group (NS group, n=20), and TMP group (n=20). The rats in the NS and TMP groups underwent cecal ligation and puncture (CLP) to induce sepsis. Rats in the NS group were injected with NS (10 mL/kg) immediately after CLP and 6 h after CLP. Rats in the TMP group were injected with TMP (10 mg/kg) at the same time points. Twenty-four hours after modeling, the mortality rates were observed in each group. Cardiac function and serum concentration of tumor necrosis factor α (TNF-α) were also tested. The correlation between TNF-α and the ejection fraction (EF) was observed. Left ventricle specimens were reserved for histomorphologic study.

RESULTS

Compared with the sham group, the NS and TMP groups had decreased EF values and increased mortality rates and serum TNF-α levels (P <0.05). The TMP group had a comparatively lower mortality rate and TNF-α level and a higher EF value compared with the NS group (P <0.05). Histomorphology indicated that myocardial inflammation in the TMP group was mild compared with that in the NS group. There was a negative correlation between TNF-α level and EF value (r=-0.583,P=0.000).

CONCLUSION

TMP could reduce the mortality rate of septic rats and had certain protective effects on cardiac function.

Salutary effect of resveratrol on sepsis-induced myocardial depression

OBJECTIVES

We hypothesized that resveratrol administration would reverse sepsis-dependent downregulation of peroxisome proliferator activated receptor-γ coactivator 1α, preserve mitochondrial integrity, and rescue animals from sepsis-induced myocardial failure.

SETTING

Teaching hospital research laboratory.

INTERVENTIONS

Cecal ligation and puncture in mice was performed to induce sepsis. Mice that underwent cecal ligation and puncture were randomly assigned to receive resveratrol (30 mg/kg or 60 mg/kg) or vehicle 1 mL sodium chloride 0.9% subcutaneously in the scruff of the neck directly after surgery and at 16, 24, and 40 hrs, respectively.

MEASUREMENTS AND RESULTS

Forty-eight hrs after cecal ligation and puncture, cardiac performance was established using echocardiography. Mitochondrial integrity was evaluated with electron microscopy, and changes in gene expression were evaluated with microarray analysis. Survival at 48 hrs was just under 50% and comparable between groups. Myocardial contractile function significantly improved after resveratrol treatment. Resveratrol-treated mice developed focal areas of edema, whereas vehicle-treated mice developed significant, diffuse myocardial edema. Electron microscopy revealed widespread swollen mitochondria with ruptured outer membranes, autophagosomes, and vacuolation of the internal compartment, which were significantly attenuated in resveratrol-treated animals. Resveratrol treatment significantly increased cardiac expression of peroxisome proliferator-activated receptor-γ coactivator 1a. Microarray analysis revealed that resveratrol treatment resulted in upregulation of the peroxisome proliferator-activated receptor-γ coactivator gene set containing genes known to be regulated by this transcriptional coactivator. Our data strongly suggest that administration of resveratrol modulates bioenergy metabolism, substrate utilization, oxidative stress, and detoxification pathways associated with both mitochondrial and cardiac pathological conditions, but does not alter mortality from sepsis.

CONCLUSIONS

The salutary effects of resveratrol on cecal ligation and puncture-induced myocardial dysfunction are associated with increased peroxisome proliferator-activated receptor-γ coactivator 1a abundance and function. Preservation of myocardial energy production capacity, prevention of secondary injury, mitigation of inflammation, and reversal of sepsis-induced myocardial remodeling are likely to underlie its beneficial effects. This however, does not result in improved survival.

Conflicting physiological and genomic cardiopulmonary effects of recruitment maneuvers in murine acute lung injury

Low tidal volume ventilation, although promoting atelectasis, is a protective strategy against ventilator-induced lung injury. Deep inflation (DI) recruitment maneuvers restore lung volumes, but potentially compromise lung parenchymal and vascular function via repetitive overdistention. Our objective was to examine cardiopulmonary physiological and transcriptional consequences of recruitment maneuvers. C57/BL6 mice challenged with either PBS or LPS via aspiration were placed on mechanical ventilation (5 h) using low tidal volume inflation (TI; 8 μl/g) alone or in combination with intermittent DIs (0.75 ml twice/min). Lung mechanics during TI ventilation significantly deteriorated, as assessed by forced oscillation technique and pressure-volume curves. DI mitigated the TI-induced alterations in lung mechanics, but induced a significant rise in right ventricle systolic pressures and pulmonary vascular resistances, especially in LPS-challenged animals. In addition, DI exacerbated the LPS-induced genome-wide lung inflammatory transcriptome, with prominent dysregulation of a gene cluster involving vascular processes, as well as increases in cytokine concentrations in bronchoalveolar lavage fluid and plasma. Gene ontology analyses of right ventricular tissue expression profiles also identified inflammatory signatures, as well as apoptosis and membrane organization ontologies, as potential elements in the response to acute pressure overload. Our results, although confirming the improvement in lung mechanics offered by DI, highlight a detrimental impact in sustaining inflammatory response and exacerbating lung vascular dysfunction, events contributing to increases in right ventricle afterload. These novel insights should be integrated into the clinical assessment of the risk/benefit of recruitment maneuver strategies.