MYOCARDIAL STRUCTURAL CHANGES IN LONG-TERM HUMAN SEVERE SEPSIS/SEPTIC SHOCK MAY BE RESPONSIBLE FOR CARDIAC DYSFUNCTION

Po-Ge-Jiu-Xin decoction alleviate sepsis-induced cardiomyopathy via regulating phosphatase and tensin homolog-induced putative kinase 1 /parkin-mediated mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Sepsis is a life-threatening systemic syndrome usually accompanied by myocardial dysfunction. Po-Ge-Jiu-Xin decoction (PGJXD), a traditional Chinese prescription medicine, has been used clinically to treat cardiovascular disease including heart failure, sepsis-induced cardiomyopathy (SIC) and even septic shock. Previous clinical studies suggested PGJXD has shown promising results in improving cardiac function and treating heart failure in sepsis. However, more research is needed to elucidate the mechanisms underlying PGJXD's therapeutic effects in sepsis-induced cardiomyopathy.

MATERIALS AND METHODS

Initially, we identified the major compounds of PGJXD through ultra-performance liquid chromatography-mass spectrometry technology analysis. We established in a SIC rat model using cecal ligation and puncture(CLP) and treated by PGJXD and levosimendan. We evaluated pathological damage by hematoxylin and eosin staining and measured serum myocardial injury biomarkers. Myocardial apoptosis was detected by Tunel staining and quantifying specific biomarker protein levels. Subsequently, we evaluated myocardium mitochondrial quality using Transmission electron microscope (TEM), antioxidant stress indexes and tissue adenosine triphosphate(ATP) content. We detected the expression of phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1), parkin, LC3, and p62 using Western blotting and Quantitative real time polymerase chain reaction(qRT-PCR). (Lipopolysaccharides, LPS)-induced H9c2 cell model was established to further explore the mechanism of PGJXD on SIC. In addition to measuring cell viability, we measured mitochondrial membrane potential using JC-1 staining. Additionally, Parkin-siRNA transfected into H9c2 cells to validate whether PGJXD conducted protective effects against SIC through PINK1/Parkin-mediated mitophagy.

RESULTS

It has been demonstrated that PGJXD reduced mortality in septic rat, contributed to ameliorating myocardium injury, suppressed inflammatory response and ameliorated the myocardial apoptosis. PGJXD could also alleviate mitochondrial structural abnormality, mitigated oxidative stress injury and promoted energy synthesis in CLP models. Western blotting and qRT-PCR have further confirmed that PGJXD can activate PINK1/parkin pathway-mediated mitophagy, resulting in preserving mitochondrial quality in the myocardium. Furthermore, Parkin siRNA partially reversed the beneficial effect of PGJXD on mitochondrial fission/fusion and mitophagy in vitro. Therefore, the cardioprotective effect of PGJXD is achieved by inducing PINK1/Parkin-mediated mitophagy in maintaining mitochondrial homeostasis.

CONCLUSIONS

These results suggest that the potential therapeutic effect of PGJXD on cardiac dysfunction during sepsis and support its mechanism of targeted induction of PINK1-Parkin-mediated mitophagy.

A murine model of acute and prolonged abdominal sepsis, supported by intensive care, reveals time-dependent metabolic alterations in the heart

BACKGROUND

Sepsis-induced cardiomyopathy (SICM) often occurs in the acute phase of sepsis and is associated with increased mortality due to cardiac dysfunction. The pathogenesis remains poorly understood, and no specific treatments are available. Although SICM is considered reversible, emerging evidence suggests potential long-term sequelae. We hypothesized that metabolic and inflammatory cardiac changes, previously observed in acute sepsis as potential drivers of SICM, partially persist in prolonged sepsis.

METHODS

In 24-week-old C57BL/6J mice, sepsis was induced by cecal ligation and puncture, followed by intravenous fluid resuscitation, subcutaneous analgesics and antibiotics, and, in the prolonged phase, by parenteral nutrition. Mice were killed after 5 days of sepsis (prolonged sepsis, n = 15). For comparison, we included acutely septic mice killed at 30 h (acute sepsis, n = 15) and healthy controls animals (HC, n = 15). Cardiac tissue was collected for assessment of inflammatory and metabolic markers through gene expression, metabolomic analysis and histological assessment.

RESULTS

In prolonged sepsis, cardiac expression of IL-1β and IL-6 and macrophage infiltration remained upregulated (p ≤ 0.05). In contrast, tissue levels of Krebs cycle intermediates and adenosine phosphates were normal, whereas NADPH levels were low in prolonged sepsis (p ≤ 0.05). Gene expression of fatty acid transporters and of the glucose transporter Slc2a1 was upregulated in prolonged sepsis (p ≤ 0.01). Lipid staining and glycogen content were elevated in prolonged sepsis together with increased gene expression of enzymes responsible for lipogenesis and glycogen synthesis (p ≤ 0.05). Intermediate glycolytic metabolites (hexose-phosphates, GADP, DHAP) were elevated (p ≤ 0.05), but gene expression of several enzymes for glycolysis and mitochondrial oxidation of pyruvate, fatty-acyl-CoA and ketone bodies to acetyl-CoA were suppressed in prolonged sepsis (p ≤ 0.05). Key metabolic transcription factors PPARα and PGC-1α were downregulated in acute, but upregulated in prolonged, sepsis (p ≤ 0.05 for both). Ketone body concentrations were normal but ketolytic enzymes remained suppressed (p ≤ 0.05). Amino acid metabolism showed mild, mixed changes.

CONCLUSIONS

Our results suggest myocardial lipid and glycogen accumulation and suppressed mitochondrial oxidation, with a functionally intact Krebs cycle, in the prolonged phase of sepsis, together with ongoing myocardial inflammation. Whether these alterations have functional consequences and predispose to long-term sequelae of SICM needs further research.

Aspirin is associated with improved outcomes in patients with sepsis-induced myocardial injury: An analysis of the MIMIC-IV database

BACKGROUND

The effectiveness of aspirin treatment in septic patients remains a subject of debates.

OBJECTIVE

To explore the association between aspirin usage and the prognosis of patients with sepsis-induced myocardial injury (SIMI), as well as the timing of aspirin administration.

METHODS

Patients with SIMI were screened in the MIMIC-IV database and categorized into aspirin and non-aspirin groups based on their medications during intensive care unit (ICU) stay, and propensity matching analysis (PSM) was subsequently performed to reduce bias at baseline between the groups. The primary outcome was 28-day all-cause mortality. Cox multivariate regression analysis was conducted to evaluate the impact of aspirin on the prognosis of patients with SIMI.

RESULTS

The pre-PSM and post-PSM cohorts included 1170 and 1055 patients, respectively. In the pre-PSM cohort, the aspirin group is older, has a higher proportion of chronic comorbidities, and lower SOFA and SAPS II scores when compared to the non-aspirin group. In the PSM analysis, most of the baseline characterization biases were corrected, and aspirin use was also associated with lower 28-day mortality (hazard ratio [HR] = 0.51, 95 % confidence interval [CI]: 0.42-0.63, P < 0.001), 90-day mortality (HR = 0.58, 95 % CI: 0.49-0.69, P < 0.001) and 1-year mortality (HR = 0.65, 95 % CI: 0.56-0.76, P < 0.001), irrespective of aspirin administration timing. A sensitivity analysis based on the original cohort confirmed the robustness of the findings. Additionally, subsequent subgroup analysis revealed that the use of vasopressin have a significant interaction with aspirin's efficacy.

CONCLUSION

Aspirin was associated with decreased mortality in SIMI patients, and this beneficial effect persisted regardless of pre-ICU treatment.

Energy metabolism: from physiological changes to targets in sepsis-induced cardiomyopathy

Sepsis is a systemic inflammatory response syndrome caused by a variety of dysregulated responses to host infection with life-threatening multi-organ dysfunction. Among the injuries or dysfunctions involved in the course of sepsis, cardiac injury and dysfunction often occur and are associated with the pathogenesis of hemodynamic disturbances, also defined as sepsis-induced cardiomyopathy (SIC). The process of myocardial metabolism is tightly regulated and adapts to various cardiac output demands. The heart is a metabolically flexible organ capable of utilizing all classes of energy substrates, including carbohydrates, lipids, amino acids, and ketone bodies, to produce ATP. The demand of cardiac cells for energy metabolism changes substantially in septic cardiomyopathy, with distinct etiological causes and different times. This review describes changes in cardiomyocyte energy metabolism under normal physiological conditions and some features of myocardial energy metabolism in septic cardiomyopathy and briefly outlines the role of the mitochondria as a center of energy metabolism in the septic myocardium, revealing that changes in energy metabolism can serve as a potential future therapy for infectious cardiomyopathy.

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.

FTO alleviated ferroptosis in septic cardiomyopathy via mediating the m6A modification of BACH1

Sepsis is a global health challenge that results in systemic inflammation, oxidative stress, and multi-organ dysfunction, with the heart being particularly susceptible. This study aimed to elucidate the effect of FTO, a key regulator in m6A methylation in septic cardiomyopathy, and its potential therapeutic implications. Cellular and animal models of septic myocardial injury were established. Moreover, it was revealed that ferroptosis, which is a form of programmed necrosis occurring with iron dependence, was activated within cardiomyocytes during septic conditions. The overexpression of FTO-suppressed ferroptosis alleviated heart inflammation and dysfunction and improved survival rates in vivo. However, the protective effects of FTO were attenuated by the overexpression of BACH1, which is a molecule negatively correlated with FTO. Mechanistically, FTO modulated the m6A modification of BACH1, suggesting a complex interplay in the regulation of cardiomyocyte damage and sepsis. Our findings reveal the potential of targeting the FTO/BACH1 axis and ferroptosis inhibitors as therapeutic strategies for sepsis-induced cardiac injuries.

Engineered exosomes: a potential therapeutic strategy for septic cardiomyopathy

Septic cardiomyopathy, a life-threatening complication of sepsis, can cause acute heart failure and carry a high mortality risk. Current treatments have limitations. Fortunately, engineered exosomes, created through bioengineering technology, may represent a potential new treatment method. These exosomes can both diagnose and treat septic cardiomyopathy, playing a crucial role in its development and progression. This article examines the strategies for using engineered exosomes to protect cardiac function and treat septic cardiomyopathy. It covers three innovative aspects: exosome surface modification technology, the use of exosomes as a multifunctional drug delivery platform, and plant exosome-like nanoparticle carriers. The article highlights the ability of exosomes to deliver small molecules, proteins, and drugs, summarizing several RNA molecules, proteins, and drugs beneficial for treating septic cardiomyopathy. Although engineered exosomes are a promising biotherapeutic carrier, they face challenges in clinical application, such as understanding the interaction mechanism with host cells, distribution within the body, metabolism, and long-term safety. Further research is essential, but engineered exosomes hold promise as an effective treatment for septic cardiomyopathy.

Urolithin A protects severe acute pancreatitis-associated acute cardiac injury by regulating mitochondrial fatty acid oxidative metabolism in cardiomyocytes

Severe acute pancreatitis (SAP) often develops into acute cardiac injury (ACI), contributing to the high mortality of SAP. Urolithin A (UA; 3,8-dihydroxy-6H-dibenzopyran-6-one), a natural polyphenolic compound, has been extensively studied and shown to possess significant anti-inflammatory effects. Nevertheless, the specific effects of UA in SAP-associated acute cardiac injury (SACI) have not been definitively elucidated. Here, we investigated the therapeutic role and mechanisms of UA in SACI using transcriptomics and untargeted metabolomics analyses in a mouse model of SACI and in vitro studies. SACI resulted in severely damaged pancreatic and cardiac tissues with myocardial mitochondrial dysfunction and mitochondrial metabolism disorders. UA significantly reduced the levels of lipase, amylase and inflammatory factors, attenuated pathological damage to pancreatic and cardiac tissues, and reduced myocardial cell apoptosis and oxidative stress in SACI. Moreover, UA increased mitochondrial membrane potential and adenosine triphosphate production and restored mitochondrial metabolism, but the efficacy of UA was weakened by the inhibition of CPT1. Therefore, UA can attenuate cardiac mitochondrial dysfunction and reduce myocardial apoptosis by restoring the balance of mitochondrial fatty acid oxidation metabolism. CPT1 may be a potential target. This study has substantial implications for advancing our understanding of the pathogenesis and drug development of SACI.

Mechanisms of Acute Right Ventricular Injury in Cardiothoracic Surgical and Critical Care Settings: Part 2

The right ventricle (RV) is intricately linked in the clinical presentation of critical illness; however, the basis of this is not well-understood and has not been studied as extensively as the left ventricle. There has been an increased awareness of the need to understand how the RV is affected in different critical illness states. In addition, the increased use of point-of-care echocardiography in the critical care setting has allowed for earlier identification and monitoring of the RV in a patient who is critically ill. The first part of this review describes and characterizes the RV in different perioperative states. This second part of the review discusses and analyzes the complex pathophysiologic relationships between the RV and different critical care states. There is a lack of a universal RV injury definition because it represents a range of abnormal RV biomechanics and phenotypes. The term "RV injury" (RVI) has been used to describe a spectrum of presentations, which includes diastolic dysfunction (early injury), when the RV retains the ability to compensate, to RV failure (late or advanced injury). Understanding the mechanisms leading to functional 'uncoupling' between the RV and the pulmonary circulation may enable perioperative physicians, intensivists, and researchers to identify clinical phenotypes of RVI. This, consequently, may provide the opportunity to test RV-centric hypotheses and potentially individualize therapies.

ANGPTL2 aggravates LPS-induced septic cardiomyopathy via NLRP3-mediated inflammasome in a DUSP1-dependent pathway

Angiopoietin-like protein 2 (ANGPTL2) was implicated in various cardiovascular diseases; however, its role in lipopolysaccharide (LPS)-related septic cardiomyopathy remains unclear. Herein, mice were exposed to LPS to generate septic cardiomyopathy, and adeno-associated viral vector was employed to overexpress ANGPTL2 in the myocardium. Besides, mice were treated with adenoviral vector to knock down ANGPTL2 in hearts. ANGPTL2 expressions in hearts and cardiomyocytes were upregulated by LPS challenge. ANGPTL2 overexpression aggravated, while ANGPTL2 silence ameliorated LPS-associated cardiac impairment and inflammation. Mechanically, we found that ANGPTL2 activated NLRP3 inflammasome via suppressing DUSP1 signaling, and NLRP3 knockdown abrogated the detrimental role of ANGPTL2 in aggravating LPS-induced cardiac inflammation. Furthermore, DUSP1 overexpression significantly inhibited ANGPTL2-mediated NLRP3 activation, and subsequently improved LPS-related cardiac dysfunction. In summary, ANGPTL2 exacerbated septic cardiomyopathy via activating NLRP3-mediated inflammation in a DUSP1-dependent manner, and our study uncovered a promising therapeutic target in preventing septic cardiomyopathy.

Atrial inflammation and microvascular thrombogenicity are increased in deceased COVID-19 patients

BACKGROUND

Histopathological studies have shown inflammation, cardiomyocyte injury, and microvascular thrombosis in the ventricular myocardium of patients with coronavirus disease 2019 (COVID-19). However, although atrial dysfunction is common in COVID-19, little is known about histopathological changes in the atria of the heart. We therefore analyzed inflammation, cardiomyocyte injury, and microvascular thrombogenicity in the atria of deceased patients with COVID-19.

METHODS

Atrial tissue was obtained from autopsied COVID-19 (n=16) patients and control patients (n=10) and analyzed using immunohistochemistry. The infiltration of CD45+ leukocytes, CD3+ T lymphocytes, CD68+ macrophages, MPO+ neutrophils, and Tryptase+ mast cells were quantified as well as cardiomyocyte damage and microvascular thrombosis. In addition, Tissue Factor (TF) and Factor XII (FXII) were quantified as markers of microvascular thrombogenicity.

RESULTS

The numbers of lymphocytes, macrophages, and neutrophils were significantly increased in the atrial myocardium and epicardial atrial adipose tissue of COVID-19 patients compared with the control group. This was accompanied by dispersed cardiomyocyte injury, the occasional presence of microvascular thrombosis, and an increased presence of TF and FXII in the microvascular endothelium.

CONCLUSIONS

Severe COVID-19 induces inflammation, cardiomyocyte injury, and microvascular thrombosis in the atria of the heart.

Modulation of the mTOR Pathway by Curcumin in the Heart of Septic Mice

mTOR is a signaling pathway involved in cell survival, cell stress response, and protein synthesis that may be a key point in sepsis-induced cardiac dysfunction. Curcumin has been reported in vitro as an mTOR inhibitor compound; however, there are no studies demonstrating this effect in experimental sepsis. Thus, this study aimed to evaluate the action of curcumin on the mTOR pathway in the heart of septic mice. Free curcumin (FC) and nanocurcumin (NC) were used, and samples were obtained at 24 and 120 h after sepsis. Histopathological and ultrastructural analysis showed that treatments with FC and NC reduced cardiac lesions caused by sepsis. Our main results demonstrated that curcumin reduced mTORC1 and Raptor mRNA at 24 and 120 h compared with the septic group; in contrast, mTORC2 mRNA increased at 24 h. Additionally, the total mTOR mRNA expression was reduced at 24 h compared with the septic group. Our results indicate that treatment with curcumin and nanocurcumin promoted a cardioprotective response that could be related to the modulation of the mTOR pathway.

Septic cardiomyopathy: characteristics, evaluation, and mechanism

Sepsis is a common clinical disease; if there is no early active treatment, it is likely to develop into multiple organ dysfunction syndrome and even cause death. Septic cardiomyopathy is a complication of sepsis-related cardiovascular failure, characterized by reversible left ventricular dilatation and decreased ventricular systolic and/or diastolic function. At present, echocardiography and biomarkers are often used to screen septic cardiomyopathy in clinics. Although there is still a lack of clear diagnostic criteria for septic cardiomyopathy, according to existing studies, the pathogenesis of several septic cardiomyopathy has been clarified, such as immune response caused by infection and mitochondrial dysfunction. This review summarizes the characteristics, pathophysiology, and diagnosis of septic cardiomyopathy and focuses on the mechanisms of infection immunity and mitochondrial dysfunction.

Age-Independent Cardiac Protection by Pharmacological Activation of Beclin-1 During Endotoxemia and Its Association With Energy Metabolic Reprograming in Myocardium-A Targeted Metabolomics Study

Background We showed that Beclin-1-dependent autophagy protects the heart in young and adult mice that underwent endotoxemia. Herein, we compared the potential therapeutic effects of Beclin-1 activating peptide, TB-peptide, on endotoxemia-induced cardiac outcomes in young adult and aged mice. We further evaluated lipopolysaccharide (lipopolysaccharide)-induced and TB-peptide treatment-mediated alterations in myocardial metabolism. Methods and Results C57BL/6J mice that were 10 weeks and 24 months old were challenged by lipopolysaccharide using doses at which cardiac dysfunction occurred. Following the treatment of TB-peptide or control vehicle, heart contractility, circulating cytokines, and myocardial autophagy were evaluated. We detected that TB-peptide boosted autophagy, attenuated cytokines, and improved cardiac performance in both young and aged mice during endotoxemia. A targeted metabolomics assay was designed to detect a pool of 361 known metabolites, of which 156 were detected in at least 1 of the heart tissue samples. Lipopolysaccharide-induced impairments were found in glucose and amino acid metabolisms in mice of all ages, and TB-peptide ameliorated these alterations. However, lipid metabolites were upregulated in the young group but moderately downregulated in the aged by lipopolysaccharide, suggesting an age-dependent response. TB-peptide mitigated lipopolysaccharide-mediated trend of lipids in the young mice but had little effect on the aged. (Study registration: Project DOI: https://doi.org/10.21228/M8K11W). Conclusions Pharmacological activation of Beclin-1 by TB-peptide is cardiac protective in both young and aged population during endotoxemia, suggest a therapeutic potential for sepsis-induced cardiomyopathy. Metabolomics analysis suggests that an age-independent protection by TB-peptide is associated with reprograming of energy production via glucose and amino acid metabolisms.

Mechanisms of Post-critical Illness Cardiovascular Disease

Prolonged critical care stays commonly follow trauma, severe burn injury, sepsis, ARDS, and complications of major surgery. Although patients leave critical care following homeostatic recovery, significant additional diseases affect these patients during and beyond the convalescent phase. New cardiovascular and renal disease is commonly seen and roughly one third of all deaths in the year following discharge from critical care may come from this cluster of diseases. During prolonged critical care stays, the immunometabolic, inflammatory and neurohumoral response to severe illness in conjunction with resuscitative treatments primes the immune system and parenchymal tissues to develop a long-lived pro-inflammatory and immunosenescent state. This state is perpetuated by persistent Toll-like receptor signaling, free radical mediated isolevuglandin protein adduct formation and presentation by antigen presenting cells, abnormal circulating HDL and LDL isoforms, redox and metabolite mediated epigenetic reprogramming of the innate immune arm (trained immunity), and the development of immunosenescence through T-cell exhaustion/anergy through epigenetic modification of the T-cell genome. Under this state, tissue remodeling in the vascular, cardiac, and renal parenchymal beds occurs through the activation of pro-fibrotic cellular signaling pathways, causing vascular dysfunction and atherosclerosis, adverse cardiac remodeling and dysfunction, and proteinuria and accelerated chronic kidney disease.

Characterization of critically ill patients with septic shock and sepsis-associated cardiomyopathy using cardiovascular MRI

Aims

Sepsis‐induced cardiomyopathy is a major complication of septic shock and contributes to its high mortality. This pilot study investigated myocardial tissue differentiation in critically ill, sedated, and ventilated patients with septic shock using cardiovascular magnetic resonance (MR).

Methods and results

Fifteen patients with septic shock were prospectively recruited from the intensive care unit. Individuals received a cardiac MR scan (1.5 T) within 48 h after initial catecholamine peak and a transthoracic echocardiography at 48 and 96 h after cardiac MR. Left ventricular ejection fraction was assessed using both imaging modalities. During cardiac MR imaging, balanced steady‐state free precession imaging was performed for evaluation of cardiac anatomy and function in long‐axis and short‐axis views. Native T1 maps (modified Look–Locker inversion recovery 5 s(3 s)3 s), T2 maps, and extracellular volume maps were acquired in mid‐ventricular short axis and assessed for average plane values. Patients were given 0.2 mmol/kg of gadoteridol for extracellular volume quantification and late gadolinium enhancement imaging. Critical care physicians monitored sedated and ventilated patients during the scan with continuous invasive monitoring and realized breathholds through manual ventilation breaks. Laboratory analysis included high‐sensitive troponine T and N terminal pro brain natriuretic peptide levels. Twelve individuals with complete datasets were available for analysis (age 59.5 ± 16.9 years; 6 female). Nine patients had impaired systolic function with left ventricular ejection fraction (LVEF) < 50% (39.8 ± 5.7%), and three individuals had preserved LVEF (66.9 ± 6.7%). Global longitudinal strain was impaired in both subgroups (LVEF impaired: 11.0 ± 1.8%; LVEF preserved: 16.0 ± 5.8%; P = 0.1). All patients with initially preserved LVEF died during hospital stay; in‐hospital mortality with initially impaired LVEF was 11%. Upon echocardiographic follow‐up, LVEF improved in all previously impaired patients at 48 (52.3 ± 9.0%, P = 0.06) and 96 h (54.9 ± 7.0%, P = 0.02). Patients with impaired systolic function had increased T2 times as compared with patients with preserved LVEF (60.8 ± 5.6 ms vs. 52.2 ± 2.8 ms; P = 0.02). Left ventricular GLS was decreased in all study individuals with impaired LVEF (11.0 ± 1.8%) and less impaired with preserved LVEF (16.0 ± 5.8%; P = 0.01). T1 mapping showed increased T1 times in patients with LVEF impairment as compared with patients with preserved LVEF (1093.9 ± 86.6 ms vs. 987.7 ± 69.3 ms; P = 0.03). Extracellular volume values were elevated in patients with LVEF impairment (27.9 ± 2.1%) as compared with patients with preserved LVEF (22.7 ± 1.9%; P < 0.01).

Conclusions

Septic cardiomyopathy with impaired LVEF reflects inflammatory cardiomyopathy. Takotsubo‐like contractility patterns occur in some cases. Cardiac MR is safely feasible in critically ill, sedated, and ventilated patients using extensive monitoring and experienced staff.

Trial Registration: retrospectively registered (ISRCTN85297773)

Metabolites Concentration in Plasma and Heart Tissue in Relation to High Sensitive Cardiac Troponin T Level in Septic Shock Pigs

Elevated circulating cardiac troponin T (cTnT) is frequent in septic shock patients. Signs of myocardial ischemia and myocyte necrosis are not universally present, but the precise mechanism for elevated cTnT is unknown. We investigated plasma and heart tissue metabolites concentration in six septic shock (SS) and three sham swine undergoing a protocol of polymicrobial septic shock and resuscitation, in order to highlight possible pathways and biomarkers involved in troponin release (high sensitive cardiac troponin T, hs-cTnT). The animals were divided into two groups: the high cTnT group (n = 3) were pigs showing a significantly higher concentration of cTnT and lactate after resuscitation; the low cTnT group (n = 6, three sham and three septic shock) characterized by a lower value of cTnT and a lactate level < 2 mmol/L. Spearman correlation was assessed on plasma fold-change of cTnT, cytokines (TNF-α and IL-10), and metabolites. Finally, the fold-change between the end of resuscitation and baseline values (Res./BL) of plasma metabolites was used to perform a partial least square discriminant analysis (PLS-DA) with three latent variables. Before building the model, the number of features was reduced by summing up the metabolites of the same class that resulted similarly correlated to cTnT fold-change. Proline and glycine were significantly higher in the high cTnT group at the end of experiment both in the myocardium and plasma analyses. Moreover, plasma proline fold-change was found to be positively correlated with cTnT and cytokine fold-changes, and trans-4-hydroxyproline (t4-OH-Pro) fold-change was positively correlated with cTnT fold-change. The PLS-DA model was able to separate the two groups and, among the first ranked features based on VIP score, we found sugars, t4-OH-Pro, proline, creatinine, total amount of sphingomyelins, and glycine. Proline, t4-OH-Pro, and glycine are very abundant in collagen, and our results may suggest that collagen degradation could represent a possible mechanism contributing to septic myocardial injury. The common phenotype of septic cardiomyopathy could be associated to dysregulated collagen metabolism and/or degradation, further exacerbated by higher inflammation and oxidative stress.

Cardiac Metabolism in Sepsis

The mechanism of sepsis-induced cardiac dysfunction is believed to be different from that of myocardial ischemia. In sepsis, chemical mediators, such as endotoxins, cytokines, and nitric oxide, cause metabolic abnormalities, mitochondrial dysfunction, and downregulation of β-adrenergic receptors. These factors inhibit the production of ATP, essential for myocardial energy metabolism, resulting in cardiac dysfunction. This review focuses on the metabolic changes in sepsis, particularly in the heart. In addition to managing inflammation, interventions focusing on metabolism may be a new therapeutic strategy for cardiac dysfunction due to sepsis.

Cardiac inflammation and microvascular procoagulant changes are decreased in second wave compared to first wave deceased COVID-19 patients

Background

Compelling evidence has shown cardiac involvement in COVID-19 patients. However, the overall majority of these studies use data obtained during the first wave of the pandemic, while recently differences have been reported in disease course and mortality between first- and second wave COVID-19 patients. The aim of this study was to analyze and compare cardiac pathology between first- and second wave COVID-19 patients.

Methods

Autopsied hearts from first- (n = 15) and second wave (n = 10) COVID-19 patients and from 18 non-COVID-19 control patients were (immuno)histochemically analyzed. CD45+ leukocyte, CD68+ macrophage and CD3+ T lymphocyte infiltration, cardiomyocyte necrosis and microvascular thrombosis were quantified. In addition, the procoagulant factors Tissue Factor (TF), Factor VII (FVII), Factor XII (FXII), the anticoagulant protein Dipeptidyl Peptidase 4 (DPP4) and the advanced glycation end-product N(^ε)-Carboxymethyllysine (CML), as markers of microvascular thrombogenicity and dysfunction, were quantified.

Results

Cardiac inflammation was significantly decreased in second wave compared to first wave COVID-19 patients, predominantly related to a decrease in infiltrated lymphocytes and the occurrence of lymphocytic myocarditis. This was accompanied by significant decreases in cardiomyocyte injury and microvascular thrombosis. Moreover, microvascular deposits of FVII and CML were significantly lower in second wave compared to first wave COVID-19 patients.

Conclusions

These results show that in our cohort of fatal COVID-19 cases cardiac inflammation, cardiomyocyte injury and microvascular thrombogenicity were markedly decreased in second wave compared to first wave patients. This may reflect advances in COVID-19 treatment related to an increased use of steroids in the second COVID-19 wave.

COVID-19 and Heart Failure: From Epidemiology During the Pandemic to Myocardial Injury, Myocarditis, and Heart Failure Sequelae

A close and intriguing relationship has been suggested between heart failure (HF) and coronavirus disease 2019 (COVID-19). First, COVID-19 pandemic represented a global public health emergency in the last year and had a catastrophic impact on health systems worldwide. Several studies showed a reduction in HF hospitalizations, ranging from 30 to 66% in different countries and leading to a subsequent increase in HF mortality. Second, pre-existing HF is a risk factor for a more severe clinical course of COVID-19 and an independent predictor of in-hospital mortality. Third, patients hospitalized for COVID-19 may develop both an acute decompensation of chronic HF and de-novo HF as a consequence of myocardial injury and cardiovascular (CV) complications. Myocardial injury occurred in at least 10% of unselected COVID-19 cases and up to 41% in critically ill patients or in those with concomitant CV comorbidities. Few cases of COVID-19-related acute myocarditis, presenting with severe reduction in the left ventricular (LV) ejection fraction and peculiar histopathological findings, were described. However, recent data suggested that COVID-19 may be associated with both systolic and diastolic LV dysfunction, with LV diastolic impairment, pulmonary hypertension, and right ventricular dysfunction representing the most frequent findings in echocardiographic studies. An overview of available data and the potential mechanisms behind myocardial injury, possibly leading to HF, will be presented in this review. Beyond the acute phase, HF as a possible long-term consequence of cardiac involvement in COVID-19 patients has been supposed and need to be investigated yet.

Heart Metabolism in Sepsis-Induced Cardiomyopathy-Unusual Metabolic Dysfunction of the Heart

Due to the need for continuous work, the heart uses up to 8% of the total energy expenditure. Due to the relatively low adenosine triphosphate (ATP) storage capacity, the heart's work is dependent on its production. This is possible due to the metabolic flexibility of the heart, which allows it to use numerous substrates as a source of energy. Under normal conditions, a healthy heart obtains approximately 95% of its ATP by oxidative phosphorylation in the mitochondria. The primary source of energy is fatty acid oxidation, the rest of the energy comes from the oxidation of pyruvate. A failed heart is characterised by a disturbance in these proportions, with the contribution of individual components as a source of energy depending on the aetiology and stage of heart failure. A unique form of cardiac dysfunction is sepsis-induced cardiomyopathy, characterised by a significant reduction in energy production and impairment of cardiac oxidation of both fatty acids and glucose. Metabolic disorders appear to contribute to the pathogenesis of cardiac dysfunction and therefore are a promising target for future therapies. However, as many aspects of the metabolism of the failing heart remain unexplained, this issue requires further research.

Energetic dysfunction in sepsis: a narrative review

Background

Growing evidence associates organ dysfunction(s) with impaired metabolism in sepsis. Recent research has increased our understanding of the role of substrate utilization and mitochondrial dysfunction in the pathophysiology of sepsis-related organ dysfunction. The purpose of this review is to present this evidence as a coherent whole and to highlight future research directions.

Main text

Sepsis is characterized by systemic and organ-specific changes in metabolism. Alterations of oxygen consumption, increased levels of circulating substrates, impaired glucose and lipid oxidation, and mitochondrial dysfunction are all associated with organ dysfunction and poor outcomes in both animal models and patients. The pathophysiological relevance of bioenergetics and metabolism in the specific examples of sepsis-related immunodeficiency, cerebral dysfunction, cardiomyopathy, acute kidney injury and diaphragmatic failure is also described.

Conclusions

Recent understandings in substrate utilization and mitochondrial dysfunction may pave the way for new diagnostic and therapeutic approaches. These findings could help physicians to identify distinct subgroups of sepsis and to develop personalized treatment strategies. Implications for their use as bioenergetic targets to identify metabolism- and mitochondria-targeted treatments need to be evaluated in future studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00893-7.

Myocardial Edema: an Overlooked Mechanism of Septic Cardiomyopathy?

Septic cardiomyopathy is an increasingly relevant topic in clinical management of septic shock. However, pathophysiological mechanisms and long-term consequences of sepsis-induced myocardial injury are still poorly understood. Herein, new clinical and histological evidence is provided suggesting an association of myocardial edema formation with tissue injury and subsequent remodeling in septic shock patients. This preliminary data supports myocardial edema as a potentially relevant and largely unexplored mechanism of human septic cardiomyopathy.

Pathophysiology of sepsis-induced cardiomyopathy

Sepsis is the life-threatening organ dysfunction caused by a dysregulated host response to infection and is the leading cause of death in intensive care units. Cardiac dysfunction caused by sepsis, usually termed sepsis-induced cardiomyopathy, is common and has long been a subject of interest. In this Review, we explore the definition, epidemiology, diagnosis and pathophysiology of septic cardiomyopathy, with an emphasis on how best to interpret this condition in the clinical context. Advances in diagnostic techniques have increased the sensitivity of detection of myocardial abnormalities but have posed challenges in linking those abnormalities to therapeutic strategies and relevant clinical outcomes. Sophisticated methodologies have elucidated various pathophysiological mechanisms but the extent to which these are adaptive responses is yet to be definitively answered. Although the indications for monitoring and treating septic cardiomyopathy are clinical and directed towards restoring tissue perfusion, a better understanding of the course and implications of septic cardiomyopathy can help to optimize interventions and improve clinical outcomes.

Metabolic Alterations in Sepsis

Sepsis is defined as “life-threatening organ dysfunction caused by a dysregulated host response to infection”. Contrary to the older definitions, the current one not only focuses on inflammation, but points to systemic disturbances in homeostasis, including metabolism. Sepsis leads to sepsis-induced dysfunction and mitochondrial damage, which is suggested as a major cause of cell metabolism disorders in these patients. The changes affect the metabolism of all macronutrients. The metabolism of all macronutrients is altered. A characteristic change in carbohydrate metabolism is the intensification of glycolysis, which in combination with the failure of entering pyruvate to the tricarboxylic acid cycle increases the formation of lactate. Sepsis also affects lipid metabolism—lipolysis in adipose tissue is upregulated, which leads to an increase in the level of fatty acids and triglycerides in the blood. At the same time, their use is disturbed, which may result in the accumulation of lipids and their toxic metabolites. Changes in the metabolism of ketone bodies and amino acids have also been described. Metabolic disorders in sepsis are an important area of research, both for their potential role as a target for future therapies (metabolic resuscitation) and for optimizing the current treatment, such as clinical nutrition.

Pellino1 deficiency reprograms cardiomyocytes energy metabolism in lipopolysaccharide-induced myocardial dysfunction

Pellino1 has been shown to regulate proinflammatory genes by activating the nuclear factor kappa B (NF-κB) and Toll-like receptor (TLR) signaling pathways, which are important in the pathological development of lipopolysaccharide (LPS)-induced myocarditis. However, it is still unknown whether silencing Pellino1 (si-Pellino1) has a therapeutic effect on this disease. Here, we showed that silencing Pellino1 can be a potential protective strategy for abnormal myocardial energy metabolism in LPS-induced myocarditis. We used liquid chromatography electrospray–ionization tandem mass spectrometry (LC–MS/MS) to analyze samples from si-Pellino1 neonatal rat cardiac myocytes (NRCMs) treated with LPS or left untreated. After normalization of the data, metabolite interaction analysis of matched KEGG pathway associations following si-Pellino1 treatment was applied, accompanied by interaction analysis of gene and metabolite associations after this treatment. Moreover, we used western blot (WB) and polymerase chain reaction (PCR) analyses to determine the expression of genes involved in regulating cardiac energy and energy metabolism in different groups. LC–MS-based metabolic profiling analysis demonstrated that si-Pellino1 treatment could alleviate or even reverse LPS-induced cellular damage by altering cardiomyocytes energy metabolism accompanied by changes in key genes (Cs, Cpt2, and Acadm) and metabolites (3-oxoocotanoyl-CoA, hydroxypyruvic acid, lauroyl-CoA, and NADPH) in NRCMs. Overall, our study unveiled the promising cardioprotective effect of silencing Pellino1 in LPS-induced myocarditis through fuel and energy metabolic regulation, which can also serve as biomarkers for this disease.

Pathological features of COVID-19-associated myocardial injury: a multicentre cardiovascular pathology study

Aims

Coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been associated with cardiovascular features of myocardial involvement including elevated serum troponin levels and acute heart failure with reduced ejection fraction. The cardiac pathological changes in these patients with COVID-19 have yet to be well described.

Methods and results

In an international multicentre study, cardiac tissue from the autopsies of 21 consecutive COVID-19 patients was assessed by cardiovascular pathologists. The presence of myocarditis, as defined by the presence of multiple foci of inflammation with associated myocyte injury, was determined, and the inflammatory cell composition analysed by immunohistochemistry. Other forms of acute myocyte injury and inflammation were also described, as well as coronary artery, endocardium, and pericardium involvement. Lymphocytic myocarditis was present in 3 (14%) of the cases. In two of these cases, the T lymphocytes were CD4 predominant and in one case the T lymphocytes were CD8 predominant. Increased interstitial macrophage infiltration was present in 18 (86%) of the cases. A mild pericarditis was present in four cases. Acute myocyte injury in the right ventricle, most probably due to strain/overload, was present in four cases. There was a non-significant trend toward higher serum troponin levels in the patients with myocarditis compared with those without myocarditis. Disrupted coronary artery plaques, coronary artery aneurysms, and large pulmonary emboli were not identified.

Conclusions

In SARS-CoV-2 there are increased interstitial macrophages in a majority of the cases and multifocal lymphocytic myocarditis in a small fraction of the cases. Other forms of myocardial injury are also present in these patients. The macrophage infiltration may reflect underlying diseases rather than COVID-19.

Myocardial Function during Low versus Intermediate Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome

BACKGROUND

Mechanical ventilation with low tidal volumes has the potential to mitigate ventilation-induced lung injury, yet the clinical effect of tidal volume size on myocardial function has not been clarified. This cross-sectional study investigated whether low tidal volume ventilation has beneficial effects on myocardial systolic and diastolic function compared to intermediate tidal volume ventilation.

METHODS

Forty-two mechanically ventilated patients without acute respiratory distress syndrome (ARDS) underwent transthoracic echocardiography after more than 24 h of mechanical ventilation according to the Protective Ventilation in Patients without ARDS (PReVENT) trial comparing a low versus intermediate tidal volume strategy. The primary outcome was left ventricular and right ventricular myocardial performance index as measure for combined systolic and diastolic function, with lower values indicating better myocardial function and a right ventricular myocardial performance index greater than 0.54 regarded as the abnormality threshold. Secondary outcomes included specific systolic and diastolic parameters.

RESULTS

One patient was excluded due to insufficient acoustic windows, leaving 21 patients receiving low tidal volumes with a tidal volume size (mean ± SD) of 6.5 ± 1.8 ml/kg predicted body weight, while 20 patients were subjected to intermediate tidal volumes receiving a tidal volume size of 9.5 ± 1.6 ml/kg predicted body weight (mean difference, -3.0 ml/kg; 95% CI, -4.1 to -2.0; P < 0.001). Right ventricular dysfunction was reduced in the low tidal volume group compared to the intermediate tidal volume group (myocardial performance index, 0.41 ± 0.13 vs. 0.64 ± 0.15; mean difference, -0.23; 95% CI, -0.32 to -0.14; P < 0.001) as was left ventricular dysfunction (myocardial performance index, 0.50 ± 0.17 vs. 0.63 ± 0.19; mean difference, -0.13; 95% CI, -0.24 to -0.01; P = 0.030). Similarly, most systolic parameters were superior in the low tidal volume group compared to the intermediate tidal volume group, yet diastolic parameters did not differ between both groups.

CONCLUSIONS

In patients without ARDS, intermediate tidal volume ventilation decreased left ventricular and right ventricular systolic function compared to low tidal volume ventilation, although without an effect on diastolic function.

Sepsis Immunometabolism: From Defining Sepsis to Understanding How Energy Production Affects Immune Response

OBJECTIVES

This review will examine current definitions and trends in sepsis management as well pathophysiologic mechanisms in animal and ex vivo studies that correlate decreased energy production with deranged inflammatory response during the septic process.

DATA SOURCES

The latest articles in the literature that focus on the role of immunometabolism and associated mechanisms in sepsis were selected.

STUDY SELECTION

The most relevant, original articles were included in the review.

DATA EXTRACTION

All pertinent data for sepsis definitions as well as changes in immunometabolic pathways during the septic process was reviewed and assessed for inclusion in this article.

DATA SYNTHESIS

Sepsis is a major cause of multiple organ dysfunction. It is the principal cause of death resulting from infection and one of the most expensive conditions treated in the United States. Despite current efforts to accurately define sepsis, novel treatments and highly trained providers, mortality rates for sepsis remain high, prompting a need for further investigation of underlying immunometabolic mechanisms to identify potential treatment targets. The definition of sepsis has shifted and changed in the past few decades due to poorly defined criteria, as well as unclear guidelines for providers with regards to management of severe sepsis and septic shock. The early identification of patients with a systemic inflammatory response that will progress to septic shock is critical since recent traditional therapeutic approaches, such as early goal-directed therapy, IV immunoglobulin, and anti-tumor necrosis factor-α antibodies have failed.

CONCLUSIONS

There are no effective anti-sepsis drug therapies due to complex inflammatory and metabolic interactions. Further studies regarding the interface between innate immunity and metabolism should be investigated to effectively address septic patient mortality rates.

Preclinical septic shock research: why we need an animal ICU

Animal experiments are widely used in preclinical medical research with the goal of disease modeling and exploration of novel therapeutic approaches. In the context of sepsis and septic shock, the translation into clinical practice has been disappointing. Classical animal models of septic shock usually involve one-sex-one-age animal models, mostly in mice or rats, contrasting with the heterogeneous population of septic shock patients. Many other factors limit the reliability of preclinical models and may contribute to preclinical research failure in critical care, including the host specificity of several pathogens, the fact that laboratory animals are raised in pathogen-free facilities and that organ support techniques are either absent or minimal. Advanced animal models have been developed with the aim of improving the clinical translatability of experimental findings. So-called animal ICUs refer to the preclinical investigation of adult or even aged animals of either sex, using—in case of rats and mice—miniaturized equipment allowing for reproducing an ICU environment at a small animal scale and integrating chronic comorbidities to more closely reflect the clinical conditions studied. Strength and limitations of preclinical animal models designed to decipher the mechanisms involved in septic cardiomyopathy are discussed. This article reviews the current status and the challenges of setting up an animal ICU.

Myocardial caspase-3 and NF-κB activation promotes calpain-induced septic apoptosis: The role of Akt/eNOS/NO pathway

AIMS

To explore the potential mechanism that the role of the Akt/eNOS/NO pathway in calpain-induced caspase-3 and NF-κB activation during septic apoptosis.

MAIN METHODS

Septic rats were stimulated by LPS (8 mg/kg, i.p.). Myocardial calpain, caspase-3, NO, TNF-α and IL-1β levels were detected by ELISA. The levels of Akt/p-Akt, eNOS/p-eNOS, iNOS proteins and number of apoptotic cells were evaluated by immunohistochemistry, western blot and TUNEL method.

KEY FINDINGS

Compared with sham, LPS treatment resulted in 4.1-fold and 1.8-fold increases in myocardial calpain activity and caspase-3 activation, respectively, and a significant increase (6.8-fold) in apoptotic cardiomyocytes was observed. The administration of calpain inhibitors (calpain inhibitor-IV, PD150606 and PD151746) showed that p-Akt and p-eNOS protein levels were correlated with the levels of LPS-induced myocardial calpain and caspase-3 activity. In addition, the quantity of p-Akt protein and NO content were markedly attenuated by wortmannin, a phosphoinositide 3-kinase (PI3K) inhibitor. Pretreatment with L-NAME, an NOS inhibitor, induced a decrease in p-eNOS proteins and apoptosis in myocardial tissues, while iNOS proteins were strongly increased in septic rats.

SIGNIFICANCE

This study suggests that the Akt/eNOS/NO pathway might lead to a novel pharmacological therapy for cardiomyocytes apoptosis in 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.

GTS-21 Protected Against LPS-Induced Sepsis Myocardial Injury in Mice Through α7nAChR

Sepsis-induced myocardial injury is a well-known cause of mortality. The cholinergic anti-inflammatory pathway (CHAIP) is a physiological mechanism by which the central nervous system regulates immune response through the vagus nerve and acetylcholine; the α7-nicotinic acetylcholine receptor (α7nAChR) is the main component of CHAIP; GTS-21, a synthetic α7nAChR selective agonist, has repeatedly shown its powerful anti-inflammatory effect. However, little is known about its effect on LPS-induced myocardial injury. We investigated the protective effects of GTS-21 on lipopolysaccharide (LPS)-induced cardiomyopathy via the cholinergic anti-inflammatory pathway in a mouse sepsis model. We constructed the model of myocardial injury in sepsis mice by C57BL/6 using LPS and determined the time of LPS treatment by hematoxylin-eosin (HE) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). C57BL/6 mice were randomized into five groups: blank control group, model group, α-bungarotoxin + LPS group, GTS-21 + LPS group, and α-bungarotoxin + GTS-21 + LPS group. The pathological results of myocardial tissue were detected by the HE method; the apoptosis rate was detected by the TUNEL method; the relative expressions of NF-κB p65, Caspase-3, Caspase-8, Bcl-2, Bax, p53, and a7nAChR were detected by real-time quantitative PCR (RT-PCR); and the protein expressions of IL-6, IL-1 β, TNF-α, and pSTAT3 were detected by western blot. The results showed that LPS-induced myocardial pathological and apoptosis changes were significant compared with the blank group, which was reversed by GTS-21; however, pretreatment with α-bungarotoxin obviously blocked the protective effect of GTS-21. NF-κB p65, Caspase-3, Caspase-8, Bax, p53, IL-6, IL-1β, TNF-α, and pSTAT3 were significantly increased in the model group, while a7nAChR and Bcl-2 were significantly decreased; GTS-21 treatment reversed that result, while pretreatment with α-bungarotoxin strengthened the result in the model. And pretreatment with α-bungarotoxin blocked the protective effect of GTS-21. GTS-21 can alleviate the LPS-induced damage in the heart via a7nAChR, and pretreatment with α-bungarotoxin obviously blocked the protective effect of GTS-21 on sepsis in mice.

Reprogramming of basic metabolic pathways in microbial sepsis: therapeutic targets at last?

Sepsis is a highly lethal and urgent unmet medical need. It is the result of a complex interplay of several pathways, including inflammation, immune activation, hypoxia, and metabolic reprogramming. Specifically, the regulation and the impact of the latter have become better understood in which the highly catabolic status during sepsis and its similarity with starvation responses appear to be essential in the poor prognosis in sepsis. It seems logical that new interventions based on the recognition of new therapeutic targets in the key metabolic pathways should be developed and may have a good chance to penetrate to the bedside. In this review, we concentrate on the pathological changes in metabolism, observed during sepsis, and the presumed underlying mechanisms, with a focus on the level of the organism and the interplay between different organ systems.

Analysis on sarcoglycans expression as markers of septic cardiomyopathy in sepsis-related death

The post-mortem assessment of sepsis-related death can be carry out by many methods recently suggested as microbiological and biochemical investigations. In these cases, the cause of death is a multiple organ dysfunction due to a dysregulated inflammatory response occurring after the failure of infection control process. It was highlighted also that the heart can be a target organ in sepsis which determines the so-called septic cardiomyopathy characterized by myocardial depression. Several mechanisms to explain the pathophysiology of septic cardiomyopathy were suggested, but very few studies about the structural alterations of cardiac cells responsible for myocardial depression were carried out. The aim of this study was to evaluate whether sarcoglycans (SG) were involved in septic cardiac damage analyzing their expression in sepsis-related deaths and, particularly, if these proteins can be used as markers of septic myocardial dysfunction. Cases of septic-related death confirmed by clinical and autopsy records were investigated and compared to a control group of traumatic deaths. Indirect immunofluorescence analysis was performed to analyze α-SG, β-SG, δ-SG, ζ-SG, ε-SG, and γ-SG. Decrease of fluorescence staining pattern for all tested sarcoglycans was observed in the septic-related deaths compared to normal fluorescence staining pattern of control group. These results provide new findings about the myocytes structural alterations due to sepsis and suggest that these proteins could be used in forensic assessment of septic cardiomyopathy.

Biologic drugs and arrhythmic risk in chronic inflammatory arthritis: the good and the bad

Increasing evidence indicates that patients with chronic inflammatory arthritis (CIA), including rheumatoid arthritis and spondyloarthropathies, have an increased risk of arrhythmic events, significantly contributing to the higher cardiovascular disease (CVD) morbidity and mortality observed in these subjects compared to the general population. Although the mechanisms accounting for such an arrhythmogenic substrate are not fully understood, the main role is probably played by chronic systemic inflammation, able to accelerate the development of structural CVD, as well as to directly affect cardiac electrophysiology. In the past decade, biologic therapies have revolutionized the treatment of CIA by highly enhancing the probability to effectively control disease activity and its systemic consequences, including cardiovascular involvement. Accordingly, accumulating data demonstrated that by potently inhibiting systemic inflammation, biologic drugs can reduce CVD progression and ameliorate arrhythmic risk parameters, with a putative beneficial impact on arrhythmia incidence. Nevertheless, a significant number of reports from clinical trials and postmarketing experience suggest that some of these medications, particularly TNF inhibitor monoclonal antibodies and rituximab, may in some circumstances precipitate arrhythmia occurrence, probably by acutely amplifying myocardial electric instability intrinsically associated with these diseases. In this review, we analyze the intricate link between biologic drugs and arrhythmias in CIA in the effort to identify which factors are involved in the fine-tuning of antiarrhythmic/pro-arrhythmic balance, and understand how this knowledge should be translated in the clinical practice to obtain the most favorable benefit-to-risk profile when biologic drugs are used in these patients.

Sepsis-Induced Cardiomyopathy: Oxidative Implications in the Initiation and Resolution of the Damage

Cardiac dysfunction may complicate the course of severe sepsis and septic shock with significant implications for patient's survival. The basic pathophysiologic mechanisms leading to septic cardiomyopathy have not been fully clarified until now. Disease-specific treatment is lacking, and care is still based on supportive modalities. Septic state causes destruction of redox balance in many cell types, cardiomyocytes included. The production of reactive oxygen and nitrogen species is increased, and natural antioxidant systems fail to counterbalance the overwhelming generation of free radicals. Reactive species interfere with many basic cell functions, mainly through destruction of protein, lipid, and nucleic acid integrity, compromising enzyme function, mitochondrial structure and performance, and intracellular signaling, all leading to cardiac contractile failure. Takotsubo cardiomyopathy may result from oxidative imbalance. This review will address the multiple aspects of cardiomyocyte bioenergetic failure in sepsis and discuss potential therapeutic interventions.

Improved Survival in a Long-Term Rat Model of Sepsis Is Associated With Reduced Mitochondrial Calcium Uptake Despite Increased Energetic Demand

OBJECTIVES

To investigate the relationship between prognosis, changes in mitochondrial calcium uptake, and bioenergetic status in the heart during sepsis.

DESIGN

In vivo and ex vivo controlled experimental studies.

SETTING

University research laboratory.

SUBJECTS

Male adult Wistar rats.

INTERVENTIONS

Sepsis was induced by intraperitoneal injection of fecal slurry. Sham-operated animals served as controls. Confocal microscopy was used to study functional and bioenergetic parameters in cardiomyocytes isolated after 24-hour sepsis. Electron microscopy was used to characterize structural changes in mitochondria and sarcoplasmic reticulum. The functional response to dobutamine was assessed in vivo by echocardiography.

MEASUREMENTS AND MAIN RESULTS

Peak aortic blood flow velocity measured at 24 hours was a good discriminator for 72-hour survival (area under the receiver operator characteristic, 0.84 ± 0.1; p = 0.03) and was used in ex vivo experiments at 24 hours to identify septic animals with good prognosis. Measurements from animals with good prognostic showed 1) a smaller increase in mitochondrial calcium content and in nicotinamide adenine dinucleotide fluorescence following pacing and 2) increased distance between mitochondria and sarcoplasmic reticulum on electron microscopy, and 3) nicotinamide adenine dinucleotide redox potential and adenosine triphosphate/adenosine diphosphate failed to reach a new steady state following pacing, suggesting impaired matching of energy supply and demand. In vivo, good prognosis animals had a blunted response to dobutamine with respect to stroke volume and kinetic energy.

CONCLUSIONS

In situations of higher energetic demand decreased mitochondrial calcium uptake may constitute an adaptive cellular response that confers a survival advantage in response to sepsis at a cost of decreased oxidative capacity.

PPARα augments heart function and cardiac fatty acid oxidation in early experimental polymicrobial sepsis

Children with sepsis and multisystem organ failure have downregulated leukocyte gene expression of peroxisome proliferator-activated receptor-α (PPARα), a nuclear hormone receptor transcription factor that regulates inflammation and lipid metabolism. Mouse models of sepsis have likewise demonstrated that the absence of PPARα is associated with decreased survival and organ injury, specifically of the heart. Using a clinically relevant mouse model of early sepsis, we found that heart function increases in wild-type (WT) mice over the first 24 h of sepsis, but that mice lacking PPARα (Ppara^-/-) cannot sustain the elevated heart function necessary to compensate for sepsis pathophysiology. Left ventricular shortening fraction, measured 24 h after initiation of sepsis by echocardiography, was higher in WT mice than in Ppara^-/- mice. Ex vivo working heart studies demonstrated greater developed pressure, contractility, and aortic outflow in WT compared with Ppara^-/- mice. Furthermore, cardiac fatty acid oxidation was increased in WT but not in Ppara^-/- mice. Regulatory pathways controlling pyruvate incorporation into the citric acid cycle were inhibited by sepsis in both genotypes, but the regulatory state of enzymes controlling fatty acid oxidation appeared to be permissive in WT mice only. Mitochondrial ultrastructure was not altered in either genotype indicating that severe mitochondrial dysfunction is unlikely at this stage of sepsis. These data suggest that PPARα expression supports the hyperdynamic cardiac response early in the course of sepsis and that increased fatty acid oxidation may prevent morbidity and mortality.

NEW & NOTEWORTHY

In contrast to previous studies in septic shock using experimental mouse models, we are the first to demonstrate that heart function increases early in sepsis with an associated augmentation of cardiac fatty acid oxidation. Absence of peroxisome proliferator-activated receptor-α (PPARα) results in reduced cardiac performance and fatty acid oxidation in sepsis.

Activation of Both the Calpain and Ubiquitin-Proteasome Systems Contributes to Septic Cardiomyopathy through Dystrophin Loss/Disruption and mTOR Inhibition

Cardiac dysfunction caused by the impairment of myocardial contractility has been recognized as an important factor contributing to the high mortality in sepsis. Calpain activation in the heart takes place in response to increased intracellular calcium influx resulting in proteolysis of structural and contractile proteins with subsequent myocardial dysfunction. The purpose of the present study was to test the hypothesis that increased levels of calpain in the septic heart leads to disruption of structural and contractile proteins and that administration of calpain inhibitor-1 (N-acetyl-leucinyl-leucinyl-norleucinal (ALLN)) after sepsis induced by cecal ligation and puncture prevents cardiac protein degradation. We also tested the hypothesis that calpain plays a role in the modulation of protein synthesis/degradation through the activation of proteasome-dependent proteolysis and inhibition of the mTOR pathway. Severe sepsis significantly increased heart calpain-1 levels and promoted ubiquitin and Pa28β over-expression with a reduction in the mTOR levels. In addition, sepsis reduced the expression of structural proteins dystrophin and β-dystroglycan as well as the contractile proteins actin and myosin. ALLN administration prevented sepsis-induced increases in calpain and ubiquitin levels in the heart, which resulted in decreased of structural and contractile proteins degradation and basal mTOR expression levels were re-established. Our results support the concept that increased calpain concentrations may be part of an important mechanism of sepsis-induced cardiac muscle proteolysis.

Cardiac dysfunction, mitochondrial architecture, energy production, and inflammatory pathways: Interrelated aspects in endotoxemia and sepsis

Septic patients with myocardial dysfunction have a 3-fold increase in mortality compared with patients without cardiovascular impairment, and usually show myocarditis, disruption of the contractile apparatus, increased amounts of interstitial collagen, and damaged mitochondria. The presence of nitric oxide and cytokines in cardiac tissue constitute the molecular markers and the intracellular messengers of inflammatory conditions in the heart due to the onset of sepsis and endotoxemia, derived from the nuclear factor-κB pathway activation and proinflammatory gene transcription. Sepsis occurs with an exacerbated inflammatory response that damages tissue mitochondria and impaired bioenergetic processes. The heart consumes 20-30 times its own weight in adenosine triphosphate every day, and 90% of this molecule is derived from mitochondrial oxidative phosphorylation. Cardiac energy management is comprised in sepsis and endotoxemia; both a deficit in energy production and alterations in the source of energy substrates are believed to be involved in impaired cardiac function. Although several hypotheses try to explain the molecular mechanisms underlying the complex condition of sepsis and endotoxemia, the current view is that these syndromes are the result of an intricate balance between prevailing levels of mitochondrial stress, biogenesis/autophagy signaling and mitochondria quality control processes, rather on a single factor. The aim of this review is to discuss current hypothesis of cardiac dysfunction related to energy metabolism and mitochondrial function in experimental models of sepsis and endotoxemia, and to introduce the importance of lipids (mainly cardiolipin) in the mechanism of cardiac energy mismanagement in these inflammatory conditions.

Left ventricular function during porcine-resuscitated septic shock with pre-existing atherosclerosis

Background

Reversible, depressed cardiac function is frequently encountered during septic shock and commonly called septic cardiomyopathy. Previous studies demonstrated reduced ejection fraction and left ventricular dilatation in both humans and animal models. However, the majority of the studies in humans excluded pre-existing cardiac disease and animal studies were performed on healthy specimen and/or without vasopressor support during sepsis. In order to more closely mimic the actual patients’ conditions on intensive care units and to assess the influence of both cardiac comorbidity and vasopressor support on septic cardiomyopathy, we evaluated the left ventricular function in a porcine model of resuscitated septic shock with pre-existing atherosclerosis.

Methods

Hypercholesterolaemic, atherosclerotic pigs due to homozygous low-density lipoprotein receptor mutation and high-fat diet were anaesthetised and surgically instrumented. Faecal peritonitis was induced by inoculation of autologous faeces into the peritoneal cavity in n = 8 animals; n = 5 pigs underwent sham procedure. Sepsis resuscitation included administration of fluids and noradrenaline. Left ventricular function was analysed via pressure-conductance catheters before, 12 and 24 h after the induction of sepsis.

Results

The main findings were impaired ventricular dilatation (no significant change in the left ventricular end-diastolic volume) and unchanged ejection fraction in septic pigs with pre-existing atherosclerosis. The relaxation time constant τ decreased while dp/dt_max increased. Cardiac nitrotyrosine formation increased while expression of the endogenous hydrogen sulphide (H₂S)-producing enzyme cystathionine γ-lyase (CSE) decreased.

Conclusions

The data of the present study are in conflict with previously published data from healthy animal models, most likely as a result of ongoing resuscitation including noradrenaline treatment or intrinsic pathophysiologic processes of the pre-existing atherosclerosis. Moreover, increased nitrotyrosine formation and decreased expression of CSE suggest the implication of augmented oxidative/nitrosative stress and/or reduced bioavailability of nitric oxide as well as diminished endogenous H₂S release in the pathophysiology of septic cardiomyopathy.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-016-0089-y) contains supplementary material, which is available to authorized users.

Endotoxemia Engages the RhoA Kinase Pathway to Impair Cardiac Function By Altering Cytoskeleton, Mitochondrial Fission, and Autophagy

AIMS

The RhoA/ROCK pathway controls crucial biological processes involved in cardiovascular pathophysiology, such as cytoskeleton dynamics, vascular smooth muscle contraction, and inflammation. In this work, we tested whether Rho kinase inhibition would beneficially impact cardiac cytoskeleton organization, bioenergetics, and autophagy in experimental endotoxemia induced by lipopolysaccharides (LPSs) in mice.

RESULTS

Fasudil, a potent ROCK inhibitor, prevented LPS-induced cardiac inflammation, oxidative stress, cytoskeleton disarray, and mitochondrial injury. ROCK inhibition prevented phosphorylation of cofilin and dynamin-related protein-1, which promotes stabilization-polymerization of F-actin and mediates mitochondrial fission, respectively. Pyr1, which exclusively alters actin dynamics, prevented LPS-induced myocardial dysfunction, suggesting that beneficial impact of ROCK inhibition was not mainly related to pleiotropic effects of fasudil on cardiac inflammation and oxidative stress. Fasudil reduced mitochondrial fragmentation, stimulated initiation of autophagy, and elicited cardioprotection in LPS heart. Mdivi-1, a potent mitochondria fission inhibitor, converted cardioprotective autophagy to an inefficient form due to cargo loading failure in which autophagic vacuoles fail to trap cytosolic cargo, despite their formation at enhanced rates and lysosomal elimination.

INNOVATION

In experimental endotoxemia, cardioprotection by RhoA/ROCK inhibition may be related to changes in actin cytoskeleton reorganization and mitochondrial homeostasis. Improvement of LPS-induced mitochondrial dysfunction by fasudil was attributed to inhibition of ROCK-dependent Drp1 phosphorylation and activation of autophagic processes that can limit mitochondrial fragmentation and enhance degradation of damaged mitochondria, respectively.

CONCLUSION

Fasudil prevented LPS-induced heart oxidative stress, abnormal F-actin distribution, and oxidative phosphorylation, which concur to improve cardiac contractile and bioenergetic function. We suggest that fasudil may represent a valuable therapy for patients with sepsis.

Sepsis protects the myocardium and other organs from subsequent ischaemic/reperfusion injury via a MAPK-dependent mechanism

BACKGROUND

Sepsis has been shown to precondition the intact heart against ischaemia/reperfusion (IR) injury, and prior endotoxin exposure of cells in in vitro models has shown evidence of protection against subsequent simulated ischaemia. Our aim in this study is to validate these findings and further investigate the signaling pathways involved.

METHODS

Adult male Sprague Dawley rats were randomised to control (n = 7) or caecal ligation and perforation (CLP)-induced sepsis (n = 7). Hearts were harvested at 48 h, suspended in Langendorff mode and subjected to 30-min global ischaemia followed by 90-min reperfusion. In subsequent experiments, designed to determine the mechanisms by which sepsis protected against ischaemic injury, endotoxin-stimulated isolated cardiomyocytes, pulmonary A549 cells and renal HK2 cells were subjected to normoxic and hypoxic conditions. The roles of key pathways, including mitogen-activated protein (MAP) kinases extracellular-regulated protein kinase (ERK) 1/2, p38 MAPK (p38), c-Jun NH2-terminal protein kinase (JNK)), and nuclear factor-kappaB (NF-κB) were examined.

RESULTS

Systemic sepsis protected isolated hearts from subsequent ischaemic/reperfusion-induced injury, enhancing functional recovery on reperfusion [developed left ventricular pressure ((d)LVP) mean(SE) 66.63(±10.7) mmHg vs. 54.13(±9.9) mmHg; LVPmax at 60 min 67.29(±11.9) vs. 72.48(±9.3), sepsis vs. control] despite significantly reduced baseline LV function in CLP animals (p < 0.001). Septic preconditioning significantly reduced infarct size after IR injury (p < 0.05). Endotoxin exposure protected isolated cardiomyocytes against hypoxia-induced cell death (p < 0.001). This effect appeared mediated in part via the p38, JNK and NF-κB pathways, but was independent of the ERK pathway, and did not appear to be mediated via HMGB1. The preconditioning effect of endotoxin was also demonstrated in isolated kidney and lung cells, suggesting that this preconditioning effect of sepsis is not confined to the myocardium.

CONCLUSIONS

Sepsis preconditions the isolated rat heart against myocardial IR injury. These effects appeared to be mediated in part via the p38, JNK and NF-κB and pathways, but were independent of the ERK and HMGB pathways.

Left ventricular global longitudinal strain is independently associated with mortality in septic shock patients

PURPOSE

Conventional echocardiography may not detect subtle cardiac dysfunction of septic patients. Two-dimensional left ventricular (LV) global peak systolic longitudinal strain (GLS) can detect early cardiac dysfunction. We sought to determine the prognostic value of GLS for septic shock patients admitted to intensive care units (ICUs).

METHODS

We prospectively included 111 ICU patients with septic shock. A full medical history was recorded for each patient, and LV systolic function, including GLS, was measured. Our endpoints were ICU and hospital mortality.

RESULTS

The ICU and hospital mortalities were 31.5% (n = 35) and 35.1% (n = 39), respectively. There was no significant difference in LV ejection fraction of the non-survivors and the survivors; however, upon ICU admission, the non-survivors exhibited GLSs that were less negative than those of the survivors, which indicated worse LV systolic function. GLS of -13% presented the best sensitivity and specificity in the prediction of mortality (area under the curve 0.79). The patients with GLS ≥ -13% exhibited higher ICU and hospital mortality rates (hazard ratio 4.34, p < 0.001 and hazard ratio 4.21, p < 0.001, respectively). Cox regression analyses revealed that higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores and less negative GLSs were independent predictors of ICU and hospital mortalities. GLS was found to add prognostic information to the APACHE II score.

CONCLUSIONS

These findings suggest that combining GLS and the APACHE II score has additive value in the prediction of ICU and hospital mortalities and that GLS may help in early identification of high-risk septic shock patients in ICU.