ICAM-1 and VCAM-1 mediate endotoxemic myocardial dysfunction independent of neutrophil accumulation

Aging Impairs the Capacity of Cardiac Functional Recovery Following Endotoxemia: Modulation of Myocardial Klotho Level for Remedy

INTRODUCTION

Endotoxemic/septic cardiac dysfunction occurs frequently in elderly patients undergoing major surgery and contributes to postsurgery morbidity and mortality. This study evaluated the effect of aging on cardiac functional recovery following endotoxemia and explored therapeutic approaches for promotion of the recovery.

METHODS

A small dose of endotoxin (0.5 mg/kg, iv) was administered to young adult (3-4 mo) and old (18-22 mo) mice with or without subsequent treatment with recombinant interleukin-37 (IL-37, 50 μg/kg, iv) or recombinant Klotho (10 μg/kg, iv). Cardiac function was analyzed using a microcatheter at 24, 48, and 96 h following administration of endotoxin. Myocardial levels of Klotho, intercellular adhesion molecule-1, and IL-6 were determined by immunoblotting and Enzyme-linked immunosorbent assay.

RESULTS

Compared to young adult endotoxemic mice, old endotoxemic mice had worse cardiac dysfunction accompanied by greater myocardial levels of intercellular adhesion molecule-1 and IL-6 at each time point and failed to fully recover cardiac function by 96 h. The exacerbated and prolonged myocardial inflammation and cardiac dysfunction in old endotoxemic mice were associated with lower myocardial Klotho level and its further reduction by endotoxemia. Interestingly, recombinant IL-37 up-regulated myocardial Klotho level in old mice with or without endotoxemia and treatment of old endotoxemic mice with IL-37 improved myocardial inflammation resolution and cardiac functional recovery. Similarly, recombinant Klotho suppressed myocardial inflammatory response and promoted inflammation resolution in old endotoxemic mice, leading to complete recovery of cardiac function by 96 h.

CONCLUSIONS

Myocardial Klotho insufficiency in old mice exacerbates myocardial inflammatory response, impairs inflammation resolution and hinders cardiac functional recovery. IL-37 is capable of up-regulating myocardial Klotho level to promote myocardial inflammation resolution and cardiac functional recovery in old endotoxemic mice.

Roles and Therapeutic Targeting of Exosomes in Sepsis-Induced Cardiomyopathy

Sepsis-induced cardiomyopathy (SICM) is a complex and fatal manifestation of sepsis, characterised by myocardial dysfunction that exacerbates the clinical prognosis in septic patients. While the pathophysiology of SICM remains incompletely understood, emerging evidence highlights the multifaceted functions of exosomes, small membrane-bound extracellular vesicles, in mediating the inflammatory responses and cardiac dysfunction involved in this condition. During sepsis, exosomes are secreted by various cells, such as cardiomyocytes, endothelial cells and macrophages, which serve as critical messengers, transferring proteins, lipids and RNA molecules that influence recipient cells, thus affecting cellular functions and disease progression. This review summarises the pathophysiology of SICM and the basics of exosomes and focuses on exosome-mediated mechanisms in SICM, including their role in inflammation, oxidative stress, mitochondrial dysfunction and myocardial injury, offering novel insights into the exosome-based therapeutic strategies in SICM.

Endothelial α1-adrenergic receptor activation improves cardiac function in septic mice via PKC-ERK/p38MAPK signaling pathway

Cardiomyopathy is particularly common in septic patients. Our previous studies have shown that activation of the alpha 1 adrenergic receptor (α1-AR) on cardiomyocytes inhibits sepsis-induced myocardial dysfunction. However, the role of cardiac endothelial α1-AR in septic cardiomyopathy has not been determined. Here, we identified α1-AR expression in mouse and human endothelial cells and showed that activation of α1-AR with phenylephrine (PE) improved cardiac function and survival by preventing cardiac endothelial injury in septic mice. Mechanistically, activating α1-AR with PE decreased the expression of ICAM-1, VCAM-1, iNOS, E-selectin, and p-p38MAPK, while promoting PKC and ERK1/2 phosphorylation in LPS-treated endothelial cells. These effects were abolished by a PKC inhibitor or α1-AR antagonist. PE also reduced p65 nuclear translocation, but this suppression is not blocked by PKC inhibition. Treatment with U0126 (a specific ERK1/2 inhibitor) reversed the effects of PE on p38MAPK phosphorylation. Our results demonstrate that cardiac endothelial α1-AR activation prevents sepsis-induced myocardial dysfunction in mice by inhibiting the endothelial injury via PKC-ERK/p38MAPK signaling pathway and a PKC-independent inhibition of p65 nuclear translocation. These findings offer a new perspective for septic patients with cardiac dysfunction by inhibiting cardiac endothelial cell injury through α1-AR activation.

m6A methylation in myocardial tissue of septic mice analyzed using MeRIP/m6A-sequencing and RNA-sequencing

Septic cardiomyopathy is a secondary myocardial injury caused by sepsis. N6-methyl-adenosine (m6A) modification is involved in the pathological progression of septic cardiomyopathy; however, the pathological mechanism remains unclear. In this study, we identified the overall m6A modification pattern in septic myocardial injury and determined its potential interactions with differentially expressed genes (DEGs). A sepsis mouse model exhibiting septic symptoms and myocardial tissue damage was induced by lipopolysaccharide (LPS). LPS-induced septic myocardial tissues and control myocardial tissues were subjected to methylated RNA immunoprecipitation sequencing and RNA sequencing to screen for differentially expressed m6A peaks and DEGs. We identified 859 significantly m6A-modified genes in septic myocardial tissues, including 432 upregulated and 427 downregulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to explore the biological importance of differentially expressed m6A methylated genes and DEGs. Differentially expressed m6A methylated genes were enriched in immune- and inflammation-related pathways. Conjoint analysis revealed co-expression of differentially expressed m6A genes and DEGs, including genes that were upregulated or downregulated and those showing opposite trends. High expression of m6A-related genes (WTAP and IGF2BP2), interleukin-17, and interleukin-17 pathway-related genes (MAPK11 and TRAF3IP2) was verified using reverse transcription-quantitative PCR. We confirmed the presence of m6A modification of the transcriptome and m6A-mediated gene expression in septic myocardial tissues.

Exploring biomarkers for diagnosing and predicting organ dysfunction in patients with perioperative sepsis: a preliminary investigation

OBJECTIVE

Early diagnosis and prediction of organ dysfunction are critical for intervening and improving the outcomes of septic patients. The study aimed to find novel diagnostic and predictive biomarkers of organ dysfunction for perioperative septic patients.

METHOD

This is a prospective, controlled, preliminary, and single-center study of emergency surgery patients. Mass spectrometry, Gene Ontology (GO) functional analysis, and the protein-protein interaction (PPI) network were performed to identify the differentially expressed proteins (DEPs) from sepsis patients, which were selected for further verification via enzyme-linked immunosorbent assay (ELISA). Logistic regression analysis was used to estimate the relative correlation of selected serum protein levels and clinical outcomes of septic patients. Calibration curves were plotted to assess the calibration of the models.

RESULTS

Five randomized serum samples per group were analyzed via mass spectrometry, and 146 DEPs were identified. GO functional analysis and the PPI network were performed to evaluate the molecular mechanisms of the DEPs. Six DEPs were selected for further verification via ELISA. Cathepsin B (CatB), vascular cell adhesion protein 1 (VCAM-1), neutrophil gelatinase-associated lipocalin (NGAL), protein S100-A9, prosaposin, and thrombospondin-1 levels were significantly increased in the patients with sepsis compared with those of the controls (p < 0.001). Logistic regression analysis showed that CatB, S100-A9, VCAM-1, prosaposin, and NGAL could be used for preoperative diagnosis and postoperative prediction of organ dysfunction. CatB and S100-A9 were possible predictive factors for preoperative diagnosis of renal failure in septic patients. Internal validation was assessed using the bootstrapping validation. The preoperative diagnosis of renal failure model displayed good discrimination with a C-index of 0.898 (95% confidence interval 0.843-0.954) and good calibration.

CONCLUSION

Serum CatB, S100-A9, VCAM-1, prosaposin, and NGAL may be novel markers for preoperative diagnosis and postoperative prediction of organ dysfunction. Specifically, S100-A9 and CatB were indicators of preoperative renal dysfunction in septic patients. Combining these two biomarkers may improve the accuracy of predicting preoperative septic renal dysfunction.

TRIAL REGISTRATION

The study was registered at the Chinese Clinical Trials Registry (ChiCTR2200060418) on June 1, 2022.

Acute lung injury is prevented by monocyte locomotion inhibitory factor in an experimental severe malaria mouse model

Acute lung injury caused by severe malaria (SM) is triggered by a dysregulated immune response towards the infection with Plasmodium parasites. Postmortem analysis of human lungs shows diffuse alveolar damage (DAD), the presence of CD8 lymphocytes, neutrophils, and increased expression of Intercellular Adhesion Molecule 1 (ICAM-1). P. berghei ANKA (PbA) infection in C57BL/6 mice reproduces many SM features, including acute lung injury characterized by DAD, CD8+ T lymphocytes and neutrophils in the lung parenchyma, and tissular expression of proinflammatory cytokines and adhesion molecules, such as IFNγ, TNFα, ICAM, and VCAM. Since this is related to a dysregulated immune response, immunomodulatory agents are proposed to reduce the complications of SM. The monocyte locomotion inhibitory factor (MLIF) is an immunomodulatory pentapeptide isolated from axenic cultures of Entamoeba hystolitica. Thus, we evaluated if the MLIF intraperitoneal (i.p.) treatment prevented SM-induced acute lung injury. The peptide prevented SM without a parasiticidal effect, indicating that its protective effect was related to modifications in the immune response. Furthermore, peripheral CD8+ leukocytes and neutrophil proportions were higher in infected treated mice. However, the treatment prevented DAD, CD8+ cell infiltration into the pulmonary tissue and downregulated IFNγ. Moreover, VCAM-1 expression was abrogated. These results indicate that the MLIF treatment downregulated adhesion molecule expression, impeding cell migration and proinflammatory cytokine tissular production, preventing acute lung injury induced by SM. Our findings represent a potential novel strategy to avoid this complication in various events where a dysregulated immune response triggers lung injury.

Sepsis-Induced myocardial dysfunction: heterogeneity of functional effects and clinical significance

Sepsis is a life-threatening disease state characterized by organ dysfunction and a dysregulated response to infection. The heart is one of the many organs affected by sepsis, in an entity termed sepsis-induced cardiomyopathy. This was initially used to describe a reversible depression in ejection fraction with ventricular dilation but advances in echocardiography and introduction of new techniques such as speckle tracking have led to descriptions of other common abnormalities in cardiac function associated with sepsis. This includes not only depression of systolic function, but also supranormal ejection fraction, diastolic dysfunction, and right ventricular dysfunction. These reports have led to inconsistent definitions of sepsis-induced cardiomyopathy. Just as there is heterogeneity among patients with sepsis, there is heterogeneity in the cardiac response; thus resuscitating these patients with a single approach is likely suboptimal. Many factors affect the heart in sepsis including inflammatory mediators, catecholamine responsiveness, and pathogen related toxins. This review will discuss different functional effects characterized by echocardiographic changes in sepsis and their prognostic and management implications.

Posttreatment with dexmedetomidine aggravates LPS-induced myocardial dysfunction partly via activating cardiac endothelial α2A-AR in mice

BACKGROUND

Dexmedetomidine (DEX) administered before or at 30 min after sepsis induction was reported to alleviate septic cardiomyopathy in experimental models. However, sepsis is a life-threatening organ dysfunction due to infection-induced dysregulated host response, whether DEX treatment in the presence of organ dysfunction affects septic cardiomyopathy is unknown. This study investigated the effect of DEX posttreatment on septic cardiomyopathy.

METHODS

Male wild-type and α_2A-adrenergic receptor (AR) knockout mice were exposed to lipopolysaccharide (LPS) or cecal ligation puncture (CLP), and cultured cardiac endothelial cells were used. Mouse survival, myocardial function, inflammatory response and related signaling pathways were determined.

RESULTS

DEX treatment at 6, 9 h after LPS challenge significantly reduced survival rate of LPS-challenged mice, especially at 9 h. DEX administered at 9 h after LPS injection or CLP significantly reduced survival in LPS or CLP-induced sepsis in wild-type mice, but not in α_2A-AR knockout mice. LPS treatment for 20 h decreased the left ventricle + dp/dt, increased myocardial interleukin (IL)-1β and IL-6 concentrations as well as cardiac endothelial tumor necrosis factor (TNF)-α, vascular cell adhesion molecule-1 (VCAM-1) and ICAM-1 expression, which were enhanced by DEX treated at 9 h after LPS injection in wild-type mice, but not in α_2A-AR knockout mice. Furthermore, DEX posttreatment increased p38 phosphorylation, c-Fos nuclear translocation and VCAM-1 expression in LPS-treated cardiac endothelial cells, which were eliminated by α_2A-AR knockout or PKC inhibitor.

CONCLUSIONS

DEX posttreatment aggravates LPS-induced cardiac inflammation and myocardial dysfunction, at least in part, via activating cardiac endothelial α_2A-AR-mediated PKC signal pathway.

Septic Cardiomyopathy: From Pathophysiology to the Clinical Setting

The onset of cardiomyopathy is a common feature in sepsis, with relevant effects on its pathophysiology and clinical care. Septic cardiomyopathy is characterized by reduced left ventricular (LV) contractility eventually associated with LV dilatation with or without right ventricle failure. Unfortunately, such a wide range of ultrasonographic findings does not reflect a deep comprehension of sepsis-induced cardiomyopathy, but rather a lack of consensus about its definition. Several echocardiographic parameters intrinsically depend on loading conditions (both preload and afterload) so that it may be challenging to discriminate which is primitive and which is induced by hemodynamic perturbances. Here, we explore the state of the art in sepsis-related cardiomyopathy. We focus on the shortcomings in its definition and point out how cardiac performance dynamically changes in response to different hemodynamic clusters. A special attention is also given to update the knowledge about molecular mechanisms leading to myocardial dysfunction and that recall those of myocardial hibernation. Ultimately, the aim of this review is to highlight the unsolved issue in the field of sepsis-induced cardiomyopathy as their implementation would lead to improve risk stratification and clinical care.

microRNA-20-1 and miR-101a suppress the NF-κB-mediated inflammation production by targeting TRAF6 in miiuy croaker

Upon recognition of the pathogen components by PRR (pattern recognition receptors), then the cells could be activated to produce inflammatory cytokines and type I interferons. The inflammation is tightly modulated by the host to prevent inappropriate inflammatory responses. MicroRNAs (miRNAs) are non-coding and small RNAs that can inhibit gene expression and participate in various biological functions, including maintaining a balanced immune response in the host. To maintain the balance of the immune response, these pathways are closely regulated by the host to prevent inappropriate reactions of the cells. However, in low vertebrates, the miRNA-mediated inflammatory response regulatory networks remain largely unknown. Here, we report that two miRNAs, miR-20-1 and miR-101a are identified as negative regulators in teleost inflammatory responses. Initially, we find that both miR-20-1 and miR-101a dramatically increased after lipopolysaccharide (LPS) stimulation and Vibrio harveyi infection. Upregulated miR-20-1 and miR-101a inhibit LPS-induced inflammatory cytokines production by targeting TNF receptor-associated factor 6 (TRAF6), thus avoiding excessive inflammation. Moreover, miR-20-1 and miR-101a regulate the inflammatory responses through the TRAF6-mediated nuclear factor kappa (NF-κB) signaling pathways. Collectively, these data indicate that miR-20-1 and miR-101a act as negative regulators through regulating the TRAF6-mediated NF-κB signaling pathway, and participate in the host antibacterial immune responses, which will provide new insight into the intricate networks of the host-pathogen interaction in the lower vertebrates.

Characterisation of the single-cell human cardiomyocytes taken from the excess heart tissue of the right ventricular outlet in congenital heart disease

Cardiovascular disease is the second highest cause of death across the globe. Myocardial infarction is one of the heart diseases that cause permanent impairment of the heart wall leads to heart failure. Cellular therapy might give hope to regenerate the damaged myocardium. Single cells isolated from an excess heart tissue obtained from the correction of the right ventricular hypertrophy in patients with Tetralogy of Fallot for future heart study were investigated.

METHODS

Once resected, the heart tissues were transported at 37 °C, in Dulbecco's Modified Eagle's medium/ DMEM (4.5 g.L^-1, antibiotic-antimycotic 3x, PRP10% (v/v)), to reach the lab within 30 min, weighted and grouped into less than 500 mg and more than 1000 mg (n = 4). Each sample was digested with 250 U.mL^-1 Collagenase type V and 4U.mL^-1 Proteinase XXIV in the MACS™ C-tube (Milltenyi, Germany), then dissociated using the MACS™ Octo Dissociator with Heater (Milltenyi, Germany) for 60 min at 37 °C.

RESULTS

All cells isolated were rod-shaped cells; viability was up to 90%. The cell density obtained from the 500 mg group were 4,867 ± 899 cells.mg^-1 tissue weight, significantly higher compared to the 1,000 mg group; had 557 ± 490 cells.mg^-1 tissue weight (mean of (n = 3) ± 95% C.l). The isolated cells were analyzed using FACs BD Flowcytometer, expressed cTnT + 13.38%, PECAM-1 + /VCAM-1- 32.25%, cKit + 7.85%, ICAM + 85.53%, indicating the cardiomyocyte progenitor cells.

CONCLUSION

Cardiomyocytes taken from the wasted heart tissue might be a candidate of cardiomyocytes source to study interventions to the heart as it contained up to 13.38% cardiomyocytes, and 32.25% of cardiac progenitor cells. Moreover, perhaps when cardiac cell therapy needs autologous cardiomyocytes, less than 500 mg tissue weight can be considered as sufficient.

The Long-term Effect of Dobutamine on Intrinsic Myocardial Function and Myocardial Injury in Septic Rats with Myocardial Dysfunction

ABSTRACT

Dobutamine (DOB) is recommended as an inotrope for septic patients with low cardiac output, but its long-term impact on sepsis-induced cardiomyopathy remains unclear. This study investigated the long-term effect of DOB on septic myocardial dysfunction and injury. Rats were exposed to cecal ligation and puncture (CLP), the intrinsic myocardial function, other organ functions, hemodynamics, inflammatory response, serum myocardial injury biomarkers, myocardial apoptosis, and vascular permeability were determined. At 6 h after CLP, the left ventricular ±dP/dt were significantly depressed, cardiac tumor necrosis factor-α and vascular cell adhesion molecule-1 expression were increased, but not serum cardiac troponin I (cTnI), N-terminal pro-brain natriuretic peptide (NT-proBNP), heart-type fatty acid-binding protein (H-FABP), creatinine, and urea nitrogen concentrations in CLP group compared with controls. At 9 h after CLP, hepatic dysfunction was present in CLP rats compared with controls. At 6 h after CLP, DOB treatment did not affect hemodynamics, the left ventricular ±dP/dt, cytokine levels in serum and myocardium, as well as cardiomyocyte apoptosis and cardiac vascular hyperpermeability at 20 h after CLP. However, DOB (10.0 μg/kg) increased serum IL-10 level and improved survival in septic rats. These results indicate that the intrinsic myocardial depression occurs earlier than hepatic and renal dysfunction in sepsis and serum cTnI, NT-proBNP, and H-FABP are not suitable as early biomarkers for sepsis-induced myocardial dysfunction. Although DOB treatment (10.0 μg/kg) in the presence of myocardial dysfunction improves survival in septic rats, it neither improves myocardial function and hemodynamics nor attenuates myocardial injury at the later stage of sepsis.

Heart Dysfunction in Sepsis

Cardiac involvement during sepsis frequently occurs. A series of molecules induces a set of changes at the cellular level that result in the malfunction of the myocardium. The understanding of these molecular alterations has simultaneously promoted the implementation of diagnostic strategies that are much more precise and allowed the advance of the therapeutics. The heart is a vital organ for survival. Its well-being ensures the adequate supply of essential elements for organs and tissues.

Oligonucleotide-based Preconditioning of DCD Cardiac Donors and Its Impact on Cardiac Viability

BACKGROUND

While clinical donation after circulatory death (DCD) cardiac transplantation is being implemented with increasing frequency to address the supply/demand mismatch of donor grafts, no research to date has examined a strategy of donor preconditioning to optimize the viability of DCD hearts for transplantation. In our rat model of the DCD protocol, we investigate the impact of pretreating donors with phosphorothioate-linked cytosine and guanine rich oligodeoxynucleotides (CpG ODN) and their effects on cardiac function, injury, and a novel left ventricular (LV) mRNA biomarker panel.

METHODS

DCD rats were subjected to a withdrawal protocol, followed by 20 minutes of warm acirculatory standoff, representing a group of severely injured hearts as previously demonstrated. Beating heart controls and DCD rats were pretreated with vehicle or stimulatory CpG ODN (beating heart control and DCD stimulated with CpG ODN, BST and DST). Hearts were harvested for ex situ heart perfusion (ESHP), where LV function, histochemical injury, and differences in gene expression were characterized between groups.

RESULTS

Donor pretreatment with CpG ODN doubled the number of functional DCD hearts at ESHP. Pretreatment was associated with improved systolic and diastolic LV function, a reduction in histological injury, and markedly reduced elaboration of cardiac troponin-I in coronary effluent during ESHP. Pretreatment was also associated with a reduction in mRNA biomarkers associated with myocardial injury.

CONCLUSIONS

A single dose of CpG ODN was associated with reduced biomarkers of cardiac injury and a 100% increase in cardiac viability in this rodent model of marginal DCD cardiac donation.

Sepsis-induced cardiac dysfunction: a review of pathophysiology

It is well known that cardiac dysfunction in sepsis is associated with significantly increased mortality. The pathophysiology of sepsis-induced cardiac dysfunction can be summarized as involving impaired myocardial circulation, direct myocardial depression, and mitochondrial dysfunction. Impaired blood flow to the myocardium is associated with microvascular dysfunction, impaired endothelium, and ventriculo-arterial uncoupling. The mechanisms behind direct myocardial depression consist of downregulation of β-adrenoceptors and several myocardial suppressants (such as cytokine and nitric oxide). Recent research has highlighted that mitochondrial dysfunction, which results in energy depletion, is a major factor in sepsis-induced cardiac dysfunction. Therefore, the authors summarize the pathophysiological process of cardiac dysfunction in sepsis based on the results of recent studies.

Endothelial HSPA12B Exerts Protection Against Sepsis-Induced Severe Cardiomyopathy via Suppression of Adhesion Molecule Expression by miR-126

Heat shock protein A12B (HSPA12B) is predominately expressed in endothelial cells (ECs) and has been reported to protect against cardiac dysfunction from endotoxemia or myocardial infarction. This study investigated the mechanisms by which endothelial HSPA12B protects polymicrobial sepsis–induced cardiomyopathy. Wild-type (WT) and endothelial HSPA12B knockout (HSPA12B^–/–) mice were subjected to polymicrobial sepsis induced by cecal ligation and puncture (CLP). Cecal ligation and puncture sepsis accelerated mortality and caused severe cardiac dysfunction in HSPA12B^–/– mice compared with WT septic mice. The levels of adhesion molecules and the infiltrated immune cells in the myocardium of HSPA12B^–/– septic mice were markedly greater than in WT septic mice. The levels of microRNA-126 (miR-126), which targets adhesion molecules, in serum exosomes from HSPA12B^–/– septic mice were significantly lower than in WT septic mice. Transfection of ECs with adenovirus expressing HSPA12B significantly increased miR-126 levels. Increased miR-126 levels in ECs prevented LPS-stimulated expression of adhesion molecules. In vivo delivery of miR-126 carried by exosomes into the myocardium of HSPA12B^–/– mice significantly attenuated CLP sepsis increased levels of adhesion molecules, and improved CLP sepsis–induced cardiac dysfunction. The data suggest that HSPA12B protects against sepsis-induced severe cardiomyopathy via regulating miR-126 expression which targets adhesion molecules, thus decreasing the accumulation of immune cells in the myocardium.

Extensive Changes in Transcriptomic "Fingerprints" and Immunological Cells in the Large Organs of Patients Dying of Acute Septic Shock and Multiple Organ Failure Caused by Neisseria meningitidis

Background: Patients developing meningococcal septic shock reveal levels of Neisseria meningitidis (10⁶-10⁸/mL) and endotoxin (10¹-10³ EU/mL) in the circulation and organs, leading to acute cardiovascular, pulmonary and renal failure, coagulopathy and a high case fatality rate within 24 h. Objective: To investigate transcriptional profiles in heart, lungs, kidneys, liver, and spleen and immunostain key inflammatory cells and proteins in post mortem formalin-fixed, paraffin-embedded (FFPE) tissue samples from meningococcal septic shock patients. Patients and Methods: Total RNA was isolated from FFPE and fresh frozen (FF) tissue samples from five patients and two controls (acute non-infectious death). Differential expression of genes was detected using Affymetrix microarray analysis. Lung and heart tissue samples were immunostained for T-and B cells, macrophages, neutrophils and the inflammatory markers PAI-1 and MCP-1. Inflammatory mediators were quantified in lysates from FF tissues. Results: The transcriptional profiles showed a complex pattern of protein-coding and non-coding RNAs with significant regulation of pathways associated with organismal death, cell death and survival, leukocyte migration, cellular movement, proliferation of cells, cell-to-cell signaling, immune cell trafficking, and inflammatory responses in an organ-specific clustering manner. The canonical pathways including acute phase response-, EIF2-, TREM1-, IL-6-, HMBG1-, PPAR signaling, and LXR/RXR activation were associated with acute heart, pulmonary, and renal failure. Fewer genes were regulated in the liver and particularly in the spleen. The main upstream regulators were TNF, IL-1β, IL-6, RICTOR, miR-6739-3p, and CD3. Increased numbers of inflammatory cells (CD68+, MPO+, CD3+, and CD20+) were found in lungs and heart. PAI-1 inhibiting fibrinolysis and MCP-1 attracting leukocyte were found significantly present in the septic tissue samples compared to the controls. Conclusions: FFPE tissue samples can be suitable for gene expression studies as well as immunostaining of specific cells or molecules. The most pronounced gene expression patterns were found in the organs with highest levels of Neisseria meningitidis DNA. Thousands of protein-coding and non-coding RNA transcripts were altered in lungs, heart and kidneys. We identified specific biomarker panels both protein-coding and non-coding RNA transcripts, which differed from organ to organ. Involvement of many genes and pathways add up and the combined effect induce organ failure.

FAM46C inhibits lipopolysaccharides-induced myocardial dysfunction via downregulating cellular adhesion molecules and inhibiting apoptosis

AIMS

Sepsis is a syndrome of inflammatory response induced by infection. Cellular adhesion molecules may involve in sepsis-induced myocardial dysfunction (SIMD) which is a major predictor of morbidity and mortality of sepsis. Here we studied the role of FAM46C in AC16 cells and c57 mice with lipopolysaccharides (LPS) treatment.

MAIN METHODS

Real-time PCR and western blot were used to detect the expression level of relative genes and protein. Cell proliferation and apoptosis were evaluated.

KEY FINDINGS

Interestingly, negative correlation between Toll-like receptor 4 (TLR4) and FAM46C in sepsis was observed. The overexpression of FAM46C reduced the apoptosis induced by LPS in AC16 cells. Inhibition of apoptosis contributed by FAM46C was mediated by adhesion molecule via blocking p38 and ERK/MAPK signaling pathway. Moreover, overexpression of Fam46c and inhibition of TLR4 by TAK-242 could attenuate apoptosis induced by LPS in vivo.

SIGNIFICANCE

FAM46C played an important role in SIMD via inhibiting LPS-induced myocardial dysfunction by downregulating cellular adhesion molecules and inhibiting apoptosis. It was the first time to explore the role of FAM46C in SIMD in this study.

Phenylephrine Attenuated Sepsis-Induced Cardiac Inflammation and Mitochondrial Injury Through an Effect on the PI3K/Akt Signaling Pathway

OBJECTIVE

To investigate whether phenylephrine (PE) inhibits sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury through the PI3K/Akt signaling pathway.

METHODS

A rat model of sepsis was established by cecal ligation and puncture. PE and/or wortmannin (a PI3K inhibitor) were administered to investigate the role of PI3K/Akt signaling in mediating the effects of PE on inhibiting sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury. Hematoxylin-eosin staining, echocardiography, and Langendorff system were used to examine the myocardial injury and function. The concentrations of TNF-α and IL-6 were analyzed by enzyme-linked immunosorbent assay. Intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), myeloperoxidase, mitochondria-related fusion/fission proteins, and PI3K/Akt signaling pathway-associated proteins were analyzed by Western blotting.

RESULTS

PE improved the cardiac function and survival in septic rats. PE decreased TNF-α, IL-6, ICAM-1, VCAM-1, and myeloperoxidase contents in the myocardium of septic rats. Meanwhile, PE increased the fusion-related proteins and decreased the fission-related proteins in the myocardial mitochondria of septic rats. On the other hand, PE activated the PI3K/Akt signaling pathway in the cecal ligation and puncture-treated rats, and all the protective effects of PE were abolished by wortmannin.

CONCLUSIONS

PE attenuated sepsis-induced cardiac dysfunction, cardiac inflammation, and mitochondrial injury through the PI3K/Akt signaling pathway.

Inflammasomes: Pandora's box for sepsis

Sepsis was known to ancient Greeks since the time of great physician Hippocrates (460-377 BC) without exact information regarding its pathogenesis. With time and medical advances, it is now considered as a condition associated with organ dysfunction occurring in the presence of systemic infection as a result of dysregulation of the immune response. Still with this advancement, we are struggling for the development of target-based therapeutic approach for the management of sepsis. The advancement in understanding the immune system and its working has led to novel discoveries in the last 50 years, including different pattern recognition receptors. Inflammasomes are also part of these novel discoveries in the field of immunology which are <20 years old in terms of their first identification. They serve as important cytosolic pattern recognition receptors required for recognizing cytosolic pathogens, and their pathogen-associated molecular patterns play an important role in the pathogenesis of sepsis. The activation of both canonical and non-canonical inflammasome signaling pathways is involved in mounting a proinflammatory immune response via regulating the generation of IL-1β, IL-18, IL-33 cytokines and pyroptosis. In addition to pathogens and their pathogen-associated molecular patterns, death/damage-associated molecular patterns and other proinflammatory molecules involved in the pathogenesis of sepsis affect inflammasomes and vice versa. Thus, the present review is mainly focused on the inflammasomes, their role in the regulation of immune response associated with sepsis, and their targeting as a novel therapeutic approach.

Deletion of caveolin-1 attenuates LPS/GalN-induced acute liver injury in mice

Acute hepatic injury caused by inflammatory liver disease is associated with high mortality. This study examined the role of caveolin-1 (Cav-1) in lipopolysaccharide (LPS) and D-galactosamine (GalN)-induced fulminant hepatic injury in wild type and Cav-1-null (Cav-1-/- ) mice. Hepatic Cav-1 expression was induced post-LPS/GalN treatment in wild-type mice. LPS/GalN-treated Cav-1-/- mice showed reduced lethality and markedly attenuated liver damage, neutrophil infiltration and hepatocyte apoptosis as compared to wild-type mice. Cav-1 deletion significantly reduced LPS/GalN-induced caspase-3, caspase-8 and caspase-9 activation and pro-inflammatory cytokine and chemokine expression. Additionally, Cav-1-/- mice showed suppressed expression of Toll-like receptor 4 (TLR4) and CD14 in Kupffer cells and reduced expression of vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 in liver cells. Cav-1 deletion impeded LPS/GalN-induced inducible nitric oxide synthase expression and nitric oxide production and hindered nuclear factor-κB (NF-κB) activation. Taken together, Cav-1 regulated the expression of mediators that govern LPS-induced inflammatory signalling in mouse liver. Thus, deletion of Cav-1 suppressed the inflammatory response mediated by the LPS-CD14-TLR4-NF-κb pathway and alleviated acute liver injury in mice.

Pathophysiology of Septic Shock

Fundamental features of septic shock are vasodilation, increased permeability, hypovolemia, and ventricular dysfunction. Vasodilation owing to increased nitric oxide and prostaglandins is treated with vasopressors (norepinephrine first). Increased permeability relates to several pathways (Slit/Robo4, vascular endothelial growth factor, angiopoietin 1 and 2/Tie2 pathway, sphingosine-1-phosphate, and heparin-binding protein), some of which are targets for therapies. Hypovolemia is common and crystalloid is recommended for fluid resuscitation. Cardiomyocyte-inflammatory interactions decrease contractility and dobutamine is recommended to increase cardiac output. There is benefit in decreasing heart rate in selected patients with esmolol. Ivabradine is a novel agent for heart rate reduction without decreasing contractility.

[Heart in sepsis : Molecular mechanisms, diagnosis and therapy of septic cardiomyopathy]

An impairment of cardiac function is a key feature of cardiovascular failure associated with sepsis; however, its clinical relevance is still underestimated. Recent advancements in echocardiography in patients with septic shock enable a better characterization of septic cardiomyopathy by unmasking a severe, cardiac dysfunction even in the presence of preserved left ventricular ejection fraction. The pathophysiology of septic cardiomyopathy involves a complex mixture of systemic factors and molecular, metabolic, and structural changes of the cardiomyocytes. A better understanding of these factors will enable the discovery of new therapeutic targets for urgently needed disease-modifying therapeutic interventions. To date, the cornerstone of therapeutic management lies in control of the underlying infectious process and hemodynamic stabilization. This review summarizes the pathogenesis, diagnosis, and treatment of septic cardiomyopathy, and highlights the importance of further urgently needed studies aimed at improving diagnosis and treatment for septic cardiomyopathy.

α2A-adrenergic blockade attenuates septic cardiomyopathy by increasing cardiac norepinephrine concentration and inhibiting cardiac endothelial activation

Cardiomyopathy is a common complication associated with increased mortality in sepsis, but lacks specific therapy. Here, using genetic and pharmacological approaches, we explored the therapeutic effect of α_2A-adrenergic receptor (AR) blockade on septic cardiomyopathy. CLP-induced septic rats were treated with BRL44408 (α_2A-AR antagonist), prazosin (α₁-AR antagonist) and/or reserpine. CLP-induced cardiomyopathy, indicated by reduced dP/dt and increased cardiac troponin I phosphorylation, was attenuated by BRL44408, this was associated with reduced cardiac TNF-α and endothelial VCAM-1 expression, cardiomyocyte apoptosis and related signal molecule phosphorylation. BRL44408 increased cardiac norepinephrine (NE) concentration in CLP rats. Pretreatment with reserpine that exhausts cardiac NE without affecting the circulating NE concentration or with prazosin partially abolished the cardioprotection of BRL44408 and reversed its inhibitory effects on myocardial TNF-α, apoptosis and related signal molecule phosphorylation, but not on VCAM-1 expression in septic rats. These effects of BRL44408 were confirmed by α_2A-AR gene deletion in septic mice. Furthermore, α₂-AR agonist not only enhanced LPS-induced TNF-α and VCAM-1 expression in cardiac endothelial cells that express α_2A-AR, but also enhanced LPS-induced cardiac dysfunction in isolated rat hearts. Our data indicate that α_2A-AR blockade attenuates septic cardiomyopathy by promoting cardiac NE release that activates myocardial α₁-AR and suppressing cardiac endothelial activation.

Growth Differentiation Factor-15 Deficiency Augments Inflammatory Response and Exacerbates Septic Heart and Renal Injury Induced by Lipopolysaccharide

Septic acute kidney injury (AKI) and myocardial dysfunction are leading causes of mortality with no accepted method of therapy. In this study we demonstrate the role of growth differentiating factor 15 (GDF15) in septic AKI and myocardial dysfunction using a murine lipopolysaccharide (LPS)-induced sepsis model and an in vitro cell culture system. Data show that GDF15 deficiency augments inflammatory response and exacerbates renal and cardiac injury induced by LPS, while over-expression of GDF15 protects the kidney and heart from LPS-induced organ dysfunction. Therefore, this study highlights the therapeutic potential of GDF15 in the treatment of endotoxin-induced sepsis.

Endotoxaemia-augmented murine venous thrombosis is dependent on TLR-4 and ICAM-1, and potentiated by neutropenia

Venous thromboembolism is a major cause of death during and immediately post-sepsis. Venous thrombosis (VT) is mediated by cell adhesion molecules and leukocytes, including neutrophil extracellular traps (NETs). Sepsis, or experimentally, endotoxaemia, shares similar characteristics and is modulated via toll like receptor 4 (TLR4). This study was undertaken to determine if endotoxaemia potentiates early stasis thrombogenesis, and secondarily to determine the role of VT TLR4, ICAM-1 and neutrophils (PMNs). Wild-type (WT), ICAM-1^-/- and TLR4^-/- mice underwent treatment with saline or LPS (10 mg/kg i. p.) alone, or followed by inferior vena cava (IVC) ligation to generate stasis VT. In vivo microscopy of leukocyte trafficking was performed in non-thrombosed mice, and tissue and plasma were harvested during early VT formation. Pre-thrombosis, circulating ICAM-1 was elevated and increased leukocyte adhesion and rolling occurred on the IVC of LPS-treated mice. Post-thrombosis, endotoxaemic mice formed larger, platelet-poor thrombi. Endotoxaemic TLR4^-/- mice did not have an augmented thrombotic response and exhibited significantly decreased circulating ICAM-1 compared to endotoxaemic WT controls. Endotoxaemic ICAM-1^-/- mice had significantly smaller thrombi compared to controls. Hypothesising that PMNs localised to the inflamed endothelium were promoting thrombosis, PMN depletion using anti-Ly6G antibody was performed. Paradoxically, VT formed without PMNs was amplified, potentially related to endotoxaemia induced elevation of PAI-1 and circulating FXIII, and decreased uPA. Endotoxaemia enhanced early VT occurs in a TLR-4 and ICAM-1 dependent fashion, and is potentiated by neutropenia. ICAM-1 and/or TLR-4 inhibition may be a unique strategy to prevent sepsis-associated VT.

Pathophysiology of sepsis-induced myocardial dysfunction

Sepsis-induced myocardial dysfunction is a common complication in septic patients and is associated with increased mortality. In the clinical setting, it was once believed that myocardial dysfunction was not a major pathological process in the septic patients, at least in part, due to the unavailability of suitable clinical markers to assess intrinsic myocardial function during sepsis. Although sepsis-induced myocardial dysfunction has been studied in clinical and basic research for more than 30 years, its pathophysiology is not completely understood, and no specific therapies for this disorder exist. The purpose of this review is to summarize our current knowledge of sepsis-induced myocardial dysfunction with a special focus on pathogenesis and clinical characteristics.

Unmasking Silent Endothelial Activation in the Cardiovascular System Using Molecular Magnetic Resonance Imaging

Endothelial activation is a hallmark of cardiovascular diseases, acting either as a cause or a consequence of organ injury. To date, we lack suitable methods to measure endothelial activation in vivo. In the present study, we developed a magnetic resonance imaging (MRI) method allowing non-invasive endothelial activation mapping in the vasculature of the main organs affected during cardiovascular diseases. In clinically relevant contexts in mice (including systemic inflammation, acute and chronic kidney diseases, diabetes mellitus and normal aging), we provided evidence that this method allows detecting endothelial activation before any clinical manifestation of organ failure in the brain, kidney and heart with an exceptional sensitivity. In particular, we demonstrated that diabetes mellitus induces chronic endothelial cells activation in the kidney and heart. Moreover, aged mice presented activated endothelial cells in the kidneys and the cerebrovasculature. Interestingly, depending on the underlying condition, the temporospatial patterns of endothelial activation in the vascular beds of the cardiovascular system were different. These results demonstrate the feasibility of detecting silent endothelial activation occurring in conditions associated with high cardiovascular risk using molecular MRI.

Advances in Sepsis Research

Recent research has identified promising targets for therapeutic interventions aimed at modulating the inflammatory response in sepsis. Herein, the authors describe mechanisms involved in the clearance of pathogen toxin from the circulation and potential interventions aimed at enhancing clearance mechanisms. The authors also describe advances in the understanding of the innate immune response as potential therapeutic targets. Finally, novel potential treatment strategies aimed at decreasing vascular leak are discussed.

Attenuation of Cardiac Dysfunction in Polymicrobial Sepsis by MicroRNA-146a Is Mediated via Targeting of IRAK1 and TRAF6 Expression

Cardiac dysfunction is a major consequence of sepsis/septic shock and contributes to the high mortality of sepsis. Innate and inflammatory responses mediated by TLRs play a critical role in sepsis-induced cardiac dysfunction. MicroRNA-146 (miR-146) was first identified as a negative regulator in innate immune and inflammatory responses induced by LPS. This study examined whether miR-146a will have a protective effect on sepsis-induced cardiac dysfunction. Lentivirus-expressing miR-146a (LmiR-146a) or lentivirus-expressing scrambled miR (LmiR-control) was delivered into the myocardium via the right carotid artery. Seven days after transfection, mice were subjected to cecal ligation and puncture (CLP). Untransfected mice were also subjected to CLP-induced sepsis. Cardiac function was examined by echocardiography before and 6 h after CLP. In vitro studies showed that increased miR-146a levels suppress LPS-induced IκBα phosphorylation and inflammatory cytokine production in both H9C2 cardiomyocytes and J774 macrophages. In vivo transfection of LmiR-146a attenuated sepsis-induced cardiac dysfunction. The values for percent ejection fraction and percent fractional shortening in LmiR-146a-transfected CLP mice were significantly greater than in untransfected CLP control. LmiR-146a transfection prevented sepsis-induced NF-κB activity, suppressed IRAK and TRAF6 expression in the myocardium, and attenuated sepsis-induced inflammatory cytokine production in both plasma and peritoneal fluid. In addition, LmiR-146a transfection decreased sepsis-induced infiltration of neutrophils and macrophages into the myocardium. LmiR-146a can also transfect macrophages in the periphery. We conclude that miR-146a attenuates sepsis-induced cardiac dysfunction by preventing NF-κB activation, inflammatory cell infiltration, and inflammatory cytokine production via targeting of IRAK and TRAF6 in both cardiomyocytes and inflammatory monocytic cells.

Attenuation of Cardiac Dysfunction in Polymicrobial Sepsis by MicroRNA-146a Is Mediated via Targeting of IRAK1 and TRAF6 Expression

Cardiac dysfunction is a major consequence of sepsis/septic shock and contributes to the high mortality of sepsis. Innate and inflammatory responses mediated by TLRs play a critical role in sepsis-induced cardiac dysfunction. MicroRNA-146 (miR-146) was first identified as a negative regulator in innate immune and inflammatory responses induced by LPS. This study examined whether miR-146a will have a protective effect on sepsis-induced cardiac dysfunction. Lentivirus-expressing miR-146a (LmiR-146a) or lentivirus-expressing scrambled miR (LmiR-control) was delivered into the myocardium via the right carotid artery. Seven days after transfection, mice were subjected to cecal ligation and puncture (CLP). Untransfected mice were also subjected to CLP-induced sepsis. Cardiac function was examined by echocardiography before and 6 h after CLP. In vitro studies showed that increased miR-146a levels suppress LPS-induced IκBα phosphorylation and inflammatory cytokine production in both H9C2 cardiomyocytes and J774 macrophages. In vivo transfection of LmiR-146a attenuated sepsis-induced cardiac dysfunction. The values for percent ejection fraction and percent fractional shortening in LmiR-146a-transfected CLP mice were significantly greater than in untransfected CLP control. LmiR-146a transfection prevented sepsis-induced NF-κB activity, suppressed IRAK and TRAF6 expression in the myocardium, and attenuated sepsis-induced inflammatory cytokine production in both plasma and peritoneal fluid. In addition, LmiR-146a transfection decreased sepsis-induced infiltration of neutrophils and macrophages into the myocardium. LmiR-146a can also transfect macrophages in the periphery. We conclude that miR-146a attenuates sepsis-induced cardiac dysfunction by preventing NF-κB activation, inflammatory cell infiltration, and inflammatory cytokine production via targeting of IRAK and TRAF6 in both cardiomyocytes and inflammatory monocytic cells.

HSPA12B inhibits lipopolysaccharide-induced inflammatory response in human umbilical vein endothelial cells

Heat shock protein A12B (HSPA12B) is a newly discovered member of the HSP70 protein family. This study investigated the effects of HSPA12B on lipopolysaccharide (LPS)-induced inflammatory responses in human umbilical vein endothelial cells (HUVECs) and the possible mechanisms involved. A HUVECs inflammatory model was induced by LPS. Overexpression of HSPA12B in HUVECs was achieved by infection with recombinant adenoviruses encoding green fluorescence protein-HSPA12B. Knockdown of HSPA12B was achieved by siRNA technique. Twenty four hours after virus infection or siRNA transfection, HUVECs were stimulated with 1 μg/ml LPS for 4 hrs. Endothelial cell permeability ability was determined by transwell permeability assay. The binding rate of human neutrophilic polymorphonuclear leucocytes (PMN) with HUVECs was examined using myeloperoxidase assay. Cell migrating ability was determined by the wound-healing assay. The mRNA and protein expression levels of interested genes were analyzed by RT-qPCR and Western blot, respectively. The release of cytokines interleukin-6 and tumour necrosis factor-α was measured by ELISA. HSPA12B suppressed LPS-induced HUVEC permeability and reduced PMN adhesion to HUVECs. HSPA12B also inhibited LPS-induced up-regulation of adhesion molecules and inflammatory cytokine expression. By contrast, knockdown of HSPA12B enhanced LPS-induced increases in the expression of adhesion molecules and inflammatory cytokines. Moreover, HSPA12B activated PI3K/Akt signalling pathway and pharmacological inhibition of this pathway by Wortmannin completely abrogated the protection of HSPA12B against inflammatory response in HUVECs. Our results suggest that HSPA12B attenuates LPS-induced inflammatory responses in HUVECs via activation of PI3K/Akt signalling pathway.

Aging and the intramyocardial inflammatory response

The sepsis-induced intramyocardial inflammatory response results in decreased ventricular function and myocardial damage. Chemokines such as monocyte chemoattractant protein-1 causally contribute to retention of intramyocardial mononuclear leukocytes and subsequent ventricular dysfunction during endotoxemic shock in mice and, importantly, this effect is age dependent. It is therefore useful to consider where monocyte chemoattractant protein-1 fits in the complex pathway leading to ventricular dysfunction during sepsis, why this might be an age-dependent effect, and what this implies for care of older sepsis patients.

Laser speckle contrast imaging for measurement of hepatic microcirculation during the sepsis: a novel tool for early detection of microcirculation dysfunction

BACKGROUND

Sepsis is a fatal systemic inflammatory response syndrome caused by severe infection. The aim of this study was to measure hepatic microcirculation during the sepsis with laser speckle contrast imaging (LSCI), as well as investigating the underlying mechanisms.

METHODS

Sepsis was induced by cecal ligation and puncture. Rats were divided into the sham group and sepsis group. The hepatic microcirculation was monitored with LSCI. In addition, hepatic endothelial function (expression of cell adhesion molecules, coagulation and vascular permeability) and neutrophils accumulation in the liver were compared between the two groups.

RESULTS

During the sepsis, hepatic microcirculation decreased dramatically (290.3±70.1 LSPU (laser speckle perfusion units) at baseline vs. 230.4±60.7 LSPU at 12h vs. 125.2±25.4 LSPU at 48h, P<0.001). The rats developed hyperbilirubinemia since 6h. In the early phase of sepsis, the accumulation of neutrophils and formation of microthrombus increased rapidly. In the late phase, hepatic neutrophils accumulation was already at its maximum level. Meanwhile, the endothelial coagulation status shifted from procoagulation to anticoagulation. The vascular leakage was involved in the microcirculation dysfunction since 12h after sepsis.

CONCLUSIONS

Hepatic microcirculation dysfunction occurs early during the sepsis and is associated with liver injury. This microcirculation dysfunction is due to neutrophil-endothelium interactions, microthrombus formation and vascular leakage.

Enhanced monocyte chemoattractant protein-1 production in aging mice exaggerates cardiac depression during endotoxemia

Introduction

Endotoxemia and the systemic inflammatory response syndrome have a significant impact on post-surgery outcome, particularly in the elderly. The cytokine response to endotoxin is altered by aging. We tested the hypothesis that vulnerability to endotoxemic cardiac depression increases with aging due to age-related augmentation of myocardial inflammatory responses.

Methods

Adult (4 to 6 months) and old (20 to 22 months) C57/BL6 mice were treated with endotoxin (0.5 mg/kg, iv). Left ventricle (LV) function was assessed using a microcatheter system. Chemokines and cytokines in plasma and myocardium were analyzed by enzyme-linked immunosorbent assay (ELISA). Mononuclear cells in the myocardium were examined using immunofluorescence staining.

Results

Old mice displayed worse LV function (cardiac output: 3.0 ± 0.2 mL/min versus 4.4 ± 0.3 mL/min in adult mice) following endotoxin treatment. The exaggerated cardiac depression in old mice was associated with higher levels of monocyte chemoattractant protein-1 (MCP-1) and keratinocyte chemoattractant (KC) in plasma and myocardium, greater myocardial accumulation of mononuclear cells, and greater levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and interleukin 6 (IL-6) in plasma and myocardium. Neutralization of MCP-1 resulted in greater reductions in myocardial mononuclear cell accumulation and cytokine production, and greater improvement in LV function in old mice while neutralization of KC had a minimal effect on LV function.

Conclusion

Old mice have enhanced inflammatory responses to endotoxemia that lead to exaggerated cardiac functional depression. MCP-1 promotes myocardial mononuclear cell accumulation and cardiodepressant cytokines production, and plays an important role in the endotoxemic cardiomyopathy in old mice. The findings suggest that special attention is needed to protect the heart in the elderly with endotoxemia.

Gene deletion of protein tyrosine phosphatase 1B protects against sepsis-induced cardiovascular dysfunction and mortality

OBJECTIVE

Cardiovascular dysfunction is a major cause of mortality in patients with sepsis. Recently, we showed that gene deletion or pharmacological inhibition of protein tyrosine phosphatase 1B (PTP1B) improves endothelial dysfunction and reduces the severity of experimental heart failure. However, the cardiovascular effect of PTP1B invalidation in sepsis is unknown. Thus, we explored the beneficial therapeutic effect of PTP1B gene deletion on lipopolysaccharide (LPS)-induced cardiovascular dysfunction, inflammation, and mortality.

APPROACH AND RESULTS

PTP1B(-/-) or wild-type mice received LPS (15 mg/kg) or vehicle followed by subcutaneous fluid resuscitation (saline, 30 mL/kg). α-1-dependent constriction and endothelium-dependent dilatation, assessed on isolated perfused mesenteric arteries, were impaired 8 hours after LPS and significantly improved in PTP1B(-/-) mice. This was associated with reduced vascular expression of interleukin1-β, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, cyclooxygenase-2, and inducible nitric oxide synthase mRNA. PTP1B gene deletion also limited LPS-induced cardiac dysfunction assessed by echocardiography, left ventricular pressure-volume curves, and in isolated perfused hearts. PTP1B(-/-) mice also displayed reduced LPS-induced cardiac expression of tumor necrosis factor-α, interleukin1-β, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and Gp91phox, as well as of several markers of cellular infiltration. PTP1B deficiency also reduced cardiac P38 and extracellular signal-regulated protein kinase 1 and 2 phosphorylation and increased phospholamban phosphorylation. Finally, PTP1B(-/-) mice displayed a markedly reduced LPS-induced mortality, an effect also observed using a pharmacological PTP1B inhibitor. PTP1B deletion also improved survival in a cecal ligation puncture model of sepsis.

CONCLUSIONS

PTP1B gene deletion protects against septic shock-induced cardiovascular dysfunction and mortality, and this may be the result of the profound reduction of cardiovascular inflammation. PTP1B is an attractive target for the treatment of sepsis.

Elevated cardiac troponins in setting of systemic inflammatory response syndrome, sepsis, and septic shock

Elevation of cardiac troponins and creatinine kinase is frequently observed in setting of systemic inflammatory response syndrome (SIRS), sepsis, or septic shock. Underlying pathophysiologic mechanism for such troponin leak, its clinical significance, and what different could be done in such settings remain elusive. In this paper we have briefly overviewed the proposed pathogenic mechanisms for SIRS, sepsis, or septic shock-related troponin elevation (SRTE) and have provided brief overview on its clinical significance. Upon review of the relevant literature we found that majority of patients with the SRTE with no prior history of coronary artery disease (CAD) upon testing are found not to have any CADs. We have also briefly discussed the possible pharmacologic agents and potential targets which are important from pathophysiologic and pharmacologic point of view that may alter the outcomes of SRTE-related myocardial depression in near future.

Rhynchophylline prevents cardiac dysfunction and improves survival in lipopolysaccharide-challenged mice via suppressing macrophage I-κBα phosphorylation

Myocardial dysfunction is a common complication during sepsis and significantly contributes to the mortality of patients with septic shock. However, none of the available therapeutic strategies proven to be effective in patients with severe sepsis are designed specifically to target myocardial dysfunction. The purpose of the present study is to investigate the effect of rhynchophylline (Rhy) on LPS-induced myocardial dysfunction in mice. We found that pretreatment with Rhy significantly improved cardiac systolic dysfunction, increased stroke volume and cardiac output in mice challenged with LPS. LPS induced cardiac inhibitor-κBα (I-κBα) phosphorylation, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) mRNA expression, and in turn increased cardiac TNF-α and IL-1β protein production, all of which were attenuated by pretreatment with Rhy. Immunohistochemistry revealed that TNF-α was found in infiltrated macrophages (F4/80(+)) and myocardium, and Rhy reduced TNF-α immunostaining in cardiac infiltrated macrophages in LPS-challenged mice. Furthermore, Rhy inhibited LPS-induced I-κBα phosphorylation and TNF-α production in cultured mouse peritoneal macrophages, but not in neonatal mouse cardiomyocytes. Pretreatment with Rhy significantly decreased the mortality of LPS-challenged mice. These results indicate that Rhy reduces cardiac dysfunction and improves survival via suppression of macrophage I-κBα phosphorylation in LPS-challenged mice, and suggest that Rhy may be a potential agent for the treatment of septic cardiac dysfunction.

Toll-like receptor 3 plays a central role in cardiac dysfunction during polymicrobial sepsis

OBJECTIVE

To determine the role of Toll-like receptor 3 in cardiac dysfunction during polymicrobial sepsis.

DESIGN

Controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Male C57BL/6, wild-type, Toll-like receptor 3-/-.

INTERVENTION

Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. Toll-like receptors (TLRs) play a critical role in the pathophysiology of sepsis/septic shock. TLR3 is located in intracellular endosomes, and recognizes double-stranded RNA. This study examined the role of TLR3 in cardiac dysfunction following cecal ligation and puncture (CLP)-induced sepsis. TLR3 knockout (TLR3-/-, n=12) and age-matched wild-type (n=12) mice were subjected to CLP. Cardiac function was measured by echocardiography before and 6 hrs after CLP.

MEASUREMENTS AND MAIN RESULTS

CLP resulted in significant cardiac dysfunction as evidenced by decreased ejection fraction by 25.7% and fractional shortening by 29.8%, respectively. However, TLR3-/- mice showed a maintenance of cardiac function at pre-CLP levels. Wild-type mice showed 50% mortality at 58 hrs and 100% mortality at 154 hrs after CLP. In striking contrast, 70% of TLR3-/- mice survived indefinitely, that is, >200 hrs. TLR3 deficiency significantly decreased CLP-induced cardiac-myocyte apoptosis and attenuated CLP-induced Fas and Fas ligand expression in the myocardium. CLP-activation of TLR4-mediated nuclear factor-κB and Toll/IL-1 receptor-domain-containing adapter-inducing interferon-β-dependant interferon signaling pathways was prevented by TLR3 deficiency. In addition, CLP-increased vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 expression, and neutrophil and macrophage sequestration in the myocardium were also attenuated in septic TLR3-/- mice. More significantly, adoptive transfer of wild-type bone-marrow stromal cells to TLR3-/- mice abolished the cardioprotective effect in sepsis.

CONCLUSIONS

These data indicate that TLR3 plays a deleterious role in mediating cardiac dysfunction in sepsis. Thus, modulation of the TLR3 activity may be useful in preventing cardiac dysfunction in sepsis.

Structural changes of the heart during severe sepsis or septic shock

Cardiovascular dysfunction is common in severe sepsis or septic shock. Although functional alterations are often described, the elevated serum levels of cardiac proteins and autopsy findings of myocardial immune cell infiltration, edema, and damaged mitochondria suggest that structural changes to the heart during severe sepsis and septic shock may occur and may contribute to cardiac dysfunction. We explored the available literature on structural (versus functional) cardiac alterations during experimental and human endotoxemia and/or sepsis. Limited data suggest that the structural changes could be prevented, and myocardial function improved by (pre-)treatment with platelet-activating factor, cyclosporin A, glutamine, caffeine, simvastatin, or caspase inhibitors.

Soluble mediators of inflammation in HIV and their implications for therapeutics and vaccine development

From early in the HIV epidemic it was appreciated that many inflammatory markers such as neopterin and TNF-α were elevated in patients with AIDS. With the advent of modern technology able to measure a broad array of cytokines, we now know that from the earliest points of infection HIV induces a cytokine storm. This review will focus on how cytokines are disturbed in HIV infection and will explore potential therapeutic uses of cytokines. These factors can be used directly as therapy during HIV infection, either to suppress viral replication or prevent deleterious immune effects of infection, such as CD4+ T cell depletion. Cytokines also show great promise as adjuvants in the development of HIV vaccines, which would be critical for the eventual control of the epidemic.

Inflammation in myocardial diseases

Inflammatory processes underlie a broad spectrum of conditions that injure the heart muscle and cause both structural and functional deficits. In this article, we address current knowledge regarding 4 common forms of myocardial inflammation: myocardial ischemia and reperfusion, sepsis, viral myocarditis, and immune rejection. Each of these pathological states has its own unique features in pathogenesis and disease evolution, but all reflect inflammatory mechanisms that are partially shared. From the point of injury to the mobilization of innate and adaptive immune responses and inflammatory amplification, the cellular and soluble mediators and mechanisms examined in this review will be discussed with a view that both beneficial and adverse consequences arise in these human conditions.

Mechanical ventilation with high tidal volumes attenuates myocardial dysfunction by decreasing cardiac edema in a rat model of LPS-induced peritonitis

Background

Injurious mechanical ventilation (MV) may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis.

Methods

Normal rats and intraperitoneal (i.p.) lipopolysaccharide (LPS)-treated rats were ventilated with low (6 ml/kg) and high (19 ml/kg) tidal volumes (Vt) under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP), central venous pressure (CVP), cardiac output (CO) and pulmonary plateau pressure (P_plat) were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM)-1 and edema were measured to evaluate endothelial inflammation and leakage.

Results

MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo.

Conclusion

MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation.

Toll-like receptor 4 stimulation initiates an inflammatory response that decreases cardiomyocyte contractility

Toll-like receptors (TLRs) have been identified as primary innate immune receptors for the recognition of pathogen-associated molecular patterns by immune cells, initiating a primary response toward invading pathogens and recruitment of the adaptive immune response. TLRs, especially Toll-like receptor 4 (TLR4), can also be stimulated by host-derived molecules and are expressed in the cardiovascular system, thus acting as a possible key link between cardiovascular diseases and the immune system. TLR4 is involved in the acute myocardial dysfunction caused by septic shock and myocardial ischemia. We used wild-type (WT) mice, TLR4-deficient (TLR4-knockout [ko]) mice, and chimeras that underwent myeloablative bone marrow transplantation to dissociate between TLR4 expression in the heart (TLR4-ko/WT) and the immunohematopoietic system (WT/TLR4-ko). Following lipopolysaccharide (LPS) challenge (septic shock model) or coronary artery ligation, myocardial ischemia (MI) model, we found WT/TLR4-ko mice challenged with LPS or MI displayed reduced cardiac function, increased myocardial levels of interleukin-1β and tumor necrosis factor-α, and upregulation of mRNA encoding TLR4 prior to myocardial leukocyte infiltration. The cardiac function of TLR4-ko or WT/TLR4-ko mice was less affected by LPS and demonstrated reduced suppression by MI compared with WT. These results suggest that TLR4 expressed in the cardiomyocytes plays a key role in this acute phenomenon.

Extracellular heat shock protein 70 induces cardiomyocyte inflammation and contractile dysfunction via TLR2

BACKGROUND

Toll-like receptors (TLRs) are expressed on cardiomyocytes and recognize pathogen-associated molecular patterns. Whether endogenous molecules produced by tissue injury (damage associated molecular patterns, DAMPs) can induce cardiomyocyte inflammation via TLR signalling pathways and/or reduce cardiomyocyte contractility is unknown.

METHODS AND RESULTS

Primary cardiomyocytes isolated from nuclear factor κ B (NFκB)-luciferase knock-in mice were used to assess NFκB signalling. DAMPs, HSP60, HSP70 and HMGB1, increased NFκB transcriptional activity compared to controls. HSP70 stood out compared to other DAMPs and even lipopolysaccharide (LPS). Subsequent experiments focused on HSP70. Cardiomyocytes exposed to HSP70 had a 58% decrease in contractility without a decrease in calcium flux. Exposure of cultured HL-1 cardiomyocytes to HSP70 resulted in increased expression of intercellular adhesion molecule 1 (ICAM-1), interleukin 6 (IL-6) and keratinocyte-derived chemokine (KC) compared to controls. Knock-out mice for TLR2, TLR4 and MyD88, plus background strain controls (C57BL/6) were used to assess induction of cardiomyocyte inflammation by HSP70. The cardiomyocyte expression of ICAM-1 induced by HSP70 was significantly reduced in TLR2 and MyD88 knock-out mice but not TLR4 knock-out mice; implicating the TLR2 signalling pathway. Furthermore, blocking antibodies to TLR2 were able to abrogate HSP70-induced contractile dysfunction and cell death.

CONCLUSIONS

Extracellular HSP70 acting via TLR2 and its obligate downstream adaptor molecule, MyD88, activate NFκB. This causes cardiomyocyte inflammation and decreased contractility.

Early myocardial dysfunction is not caused by mitochondrial abnormalities in a rat model of peritonitis

BACKGROUND

Patients with complicated intra-abdominal infections are prone to develop multiple organ failure, including myocardial dysfunction. We hypothesized that early dysfunction during sepsis is associated with inflammation, mitochondrial injury, impaired mitochondrial function, and activation of mitochondrial biogenesis.

MATERIALS AND METHODS

Rats received lipopolysaccharide (LPS, n = 11) intraperitoneally. Healthy rats (n = 6) served as controls. Myocardial function was measured ex vivo in an isolated Langendorff-perfused heart set-up. Myocardial vascular cell adhesion molecule-1 (VCAM-1) expression was determined by immunofluorescence microscopy. Cytochrome c release and cytochrome c oxidase (COX IV) activity were measured by immunohistochemistry and enzyme histochemistry, respectively. Protein expression of tumor necrosis factor-α (TNF-α), B-cell lymphoma (Bcl)-2, peroxisome proliferator activated receptor γ cofactor 1α (PGC-1α), and mitochondrial transcription factor A (TFAM) were analyzed by Western blot technique. Mitochondria were studied by electron microscopy.

RESULTS

Two hours after LPS injection, developed pressure had decreased and after 4 h myocardial contractility (+dP/dt) and relaxation (-dP/dt) also had decreased. TNF-α protein expression was increased after 2 h and returned to normal at 4 h, whereas after 4 h VCAM-1 expression was higher in LPS-treated animals. At 2 h a substrate-dependent increase in COXIV-activity was seen, but no mitochondrial damage occurred as cytochrome c release, COX IV activity and Bcl-2, PGC-1α or TFAM expression were not changed. Electron microscopy did not reveal differences in myocardial mitochondrial characteristics between LPS-treated and control rats.

CONCLUSIONS

Early myocardial dysfunction in sepsis is associated with myocardial inflammation but not with mitochondrial injury, impaired mitochondrial function, or activated mitochondrial biogenesis.