Propofol lowers serum PF4 level and partially corrects hypercoagulopathy in endotoxemic rats

EGFR promotes the apoptosis of CD4+ T lymphocytes through TBK1/Glut1 induced Warburg effect in sepsis

INTRODUCTION

Sepsis-induced apoptosis leads to lymphopenia including the decrease of CD4⁺ T cells thus favoring immunosuppression.

OBJECTIVES

Although epidermal growth factor receptor (EGFR) inhibitors significantly improve the survival rate of septic mice, the effect of EGFR on the function and metabolism of CD4⁺ T cells in sepsis remained unknown.

METHODS

CD4⁺ T cells from septic mice and patients were assessed for apoptosis, activation, Warburg metabolism and glucose transporter 1 (Glut1) expression with or without the interference of EGFR activation.

RESULTS

EGFR facilitates CD4⁺ T cell activation and apoptosis through Glut1, which is a key enzyme that controls glycolysis in T cells. EGFR, TANK binding kinase 1 (TBK1) and Glut1 form a complex to facilitate Glut1 transportation from cytoplasm to cell surface. Both the levels of membrane expression of EGFR and Glut1 and the activation levels of CD4⁺ T cells were significantly higher in patients with sepsis as compared with healthy subjects.

CONCLUSION

Our data demonstrated that through its downstream TBK1/Exo84/RalA protein system, EGFR regulates Glut1 transporting to the cell surface, which is a key step for inducing the Warburg effect and the subsequent cellular activation and apoptosis of CD4⁺ T lymphocytes and may eventually affect the immune functional status, causing immune cell exhaustion in sepsis.

The Secretome Deregulations in a Rat Model of Endotoxemic Shock

Introduction

Septic shock is a systemic inflammatory response syndrome associated with organ failures. Earlier clinical diagnosis would be of benefit to a decrease in the mortality rate. However, there is currently a lack of predictive biomarkers. The secretome is the set of proteins secreted by a cell, tissue, or organism at a given time and under certain conditions. The plasma secretome is easily accessible from biological fluids and represents a good opportunity to discover new biomarkers that can be studied with nontargeted “omic” strategies.

Aims

To identify relevant deregulated proteins (DEP) in the secretome of a rat endotoxemic shock model.

Methods

Endotoxemic shock was induced in rats by intravenous injection of lipopolysaccharides (LPS, S. enterica typhi, 0.5 mg/kg) and compared to controls (Ringer Lactate, iv). Under isoflurane anesthesia, carotid cannulation allowed mean arterial blood pressure (MAP) and heart rate (HR) monitoring and blood sampling at different time points (T0 and T50 or T0 and T90, with EDTA and protease inhibitor). Samples were prepared for large-scale tandem mass spectrometry (MS-MS) based on a label-free quantification to allow identification of the proteins deregulated upon endotoxemic conditions. A Gene Ontology (GO) analysis defined several clusters of biological processes (BP) in which the DEP are involved.

Results

Ninety minutes after shock induction, the LPS group presents a reduction in MAP (-45%, p < 0.05) and increased lactate levels (+27.5%, p < 0.05) compared to the control group. Proteomic analyses revealed 10 and 33 DEP in the LPS group, respectively, at 50 and 90 minutes after LPS injection. At these time points, GO-BP showed alterations in pathways involved in oxidative stress response and coagulation.

Conclusion

This study proposes an approach to identify relevant DEP in septic shock and brings new insights into the understanding of the secretome adaptations upon sepsis.

[Molecular mechanism underlying the inhibitory effect of propofol on lipopolysaccharide-induced pyroptosis of mouse bone marrow-derived macrophages]

OBJECTIVE

To investigate the molecular mechanism underlying the inhibitory effect of propofol on pyroptosis of macrophages.

METHODS

Macrophages derived from bone marrow were extracted and divided into three groups: control group, LPS+ATP group and propofol+LPS+ATP group. The control group was not given any treatment; LPS+ATP group was given LPS 1 μg/mL stimulation for 4 h, then ATP 4 mM stimulation for 1 h; Propofol+LPS+ATP group was given propofol+LPS 1 μg/mL stimulation for 4 h, then ATP stimulation for 1 h. After treatment, the supernatant and cells of cell culture were collected. the cell activity was detected by CCK8 and flow cytometry. The inflammatory cytokines IL-1βand IL-18 were detected by Elisa. Western blot was used to detect the expression of caspase-1 protein and TLR4 on cell membran Immunohistochemical fluorescence was used to detect apoptosis of cells.

RESULTS

LPS+ATP significantly decreased the viability of the macrophages and increased the cellular production of IL-1β and IL-18, activation of caspase-1 protein and the expression of TLR-4 on the cell membrane (P &lt; 0.05). Treatment with propofol obviously reversed the changes induced by LPS+ATP.

CONCLUSIONS

LPS+ATP can induce pyroptosis of mouse bone marrow-derived macrophages, and propofol effectively inhibits such cell death, suggesting that propofol anesthesia is beneficial during operation and helps to regulate the immune function of in patients with sepsis.

Intestinal Injury in Heat Stroke

BACKGROUND

Heat stroke is a life-threatening syndrome that is characterized by its severe clinical symptoms, rapid progression, and high rate of mortality. Recently, research has indicated that a dysfunctional intestinal epithelia barrier plays an important role in the pathophysiology of heat stroke. Protecting the intestines from heat stress had been identified as a potentially effective treatment for patients with heat stroke and may reduce the innate immune response caused by endotoxins in circulation.

OBJECTIVES

The aim of this review is to discuss this key event in heat stroke and to describe the mechanism during progression.

DISCUSSION

Direct injuries and secondary impairments of the intestine induced by heat stress are discussed; recent studies that refer to intestine-specific prevention and treatment in heat stroke and heat stress-induced injuries are also summarized.

CONCLUSIONS

A more detailed pathogenesis of heat stroke needs to be elucidated so that potentially effective means of treatment and prevention of heat stroke can be developed and studied.

Endotoxin modulates the electrophysiological characteristics of human embryonic stem cell‐differentiated cardiomyocytes

Gram‐negative bacteria‐induced infections result in fever, arrhythmia, and even death. Lipopolysaccharide (LPS), a constituent of bacteria, leads to an inflammatory response under sepsis and increase arrhythmogenesis. This study analyzed the effects on human embryonic stem cell‐differentiated cardiomyocytes (HIPSC‐CMs) exposed to LPS. A whole cell patch clamp was used to record the action potential (AP) and ionic currents with or without different doses of LPS in HIPSC‐CMs. Compared with the control, a different dose (0.04, 0.2, 1, and 5 µg/ml) of LPS‐treated HIPSC‐CMs resulted in a longer AP duration. The IC50 of sodium channel current was 1.254 µg/ml, L‐type calcium channel current was 5 µg/ml, and I_k channel currents were 1.254 µg/ml. LPS‐treated HIPSC‐CMs showed a lower sodium channel current, L‐type calcium channel current, and I_k channel currents. Furthermore, the expressions of Nav1.5 were decreased, and L‐Ca, Kv11.1, and Kv7.1 were increased in LPS‐treated HIPSC‐CMs. LPS‐induced arrhythmogenesis was related to the electrophysiological characteristics of sodium channel current, L‐type calcium channel current, and I_k channel currents. These results suggest a potential mechanism of cardiomyocyte injury in endotoxemia.

Differential role of intravenous anesthetics in colorectal cancer progression: implications for clinical application

Anesthetics are unavoidable to colorectal cancer (CRC) patients who underwent surgical treatment. Thus, the molecular mechanisms underlying the role of the intravenous anesthetics in CRC metastasis are still unclear. In this study, the effects of intravenous anesthetics, such as propofol, etomidate and dexmedetomidine, on cell migration were determined. The migration of CRC cells was inhibited by propofol in vitro, but not in vivo. Etomidate, however, promoted the migration of CRC cells both in vitro and in vivo. Epithelial-mesenchymal transition (EMT) mediated the promotive effect of propofol and etomidate on the migration of CRC cells through PI3K/AKT signaling pathway. Dexmedetomidine alone or in combination with propofol or etomidate had minor effect on the migration of CRC cells. These findings indicate that propofol inhibites CRC cell migration in vitro. Etomidate playes a role for prompting CRC metastasis progression by activating (PI3K)/AKT signaling and inducing EMT. It provides an important hint for the clinical application of these anesthetics.

Propofol protects against endotoxin-induced myocardial injury by inhibiting NF-κB-mediated inflammation

This study investigated whether propofol protects against endotoxin-induced myocardial injury by inhibiting NF-κB-mediated inflammation. Thirty clean male SD rats were randomly divided into a control (n=10), a model (n=10) and a propofol group (n=10). The model and propofol groups were injected with lipopolysaccharide (LPS) via the caudal vein to establish animal models of myocardial injury. At the same time, the control group was injected with normal saline via the caudal vein. At 30 min after the injections, the propofol group was treated with a continuous intravenous infusion of propofol, the control and model groups were injected with normal saline, and the three groups were treated continuously for 4 h. The changes in levels of interleukin-1 (IL-1), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum were detected via enzyme-linked immunosorbent assay (ELISA). The mRNA expression level of nuclear factor-κB (NF-κB) in myocardial tissues was detected via quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression levels of NF-κB, Bax and Bcl-2 in atrial muscles in each group were measured via Western blotting. The damage of myocardial tissues was detected via hematoxylin eosin (H&E) staining of tissues. Our results showed that compared with those in control group, the levels of IL-1, IL-6 and TNF-α in serum in the model and propofol groups were significantly higher; however, the levels in the model group, were significantly higher than those in the propofol group (P<0.01). The mRNA and protein expression levels of NF-κB in the propofol group were significantly lower than those in the model group (P<0.01). Likewise, the protein expression levels of Bax were significantly lower, while those of Bcl-2 were significantly increased. H&E staining showed that the myocardial tissues in the model group were damaged significantly, but the damage in the propofol group was significantly less severe. Based on our findings, it seems propofol can indeed protect against endotoxin-induced myocardial injury through its inhibition of the NF-κB-mediated inflammatory pathway.

Propofol inhibits lipopolysaccharide-induced tumor necrosis factor-alpha expression and myocardial depression through decreasing the generation of superoxide anion in cardiomyocytes

TNF-α has been shown to be a major factor responsible for myocardial depression in sepsis. The aim of this study was to investigate the effect of an anesthetic, propofol, on TNF-α expression in cardiomyocytes treated with LPS both in vivo and in vitro. In cultured cardiomyocytes, compared with control group, propofol significantly reduced protein expression of gp91phox and phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2) and p38 MAPK, which associates with reduced TNF-α production. In in vivo mice studies, propofol significantly improved myocardial depression and increased survival rate of mice after LPS treatment or during endotoxemia, which associates with reduced myocardial TNF-α production, gp91phox, ERK1/2, and p38 MAPK. It is concluded that propofol abrogates LPS-induced TNF-α production and alleviates cardiac depression through gp91phox/ERK1/2 or p38 MAPK signal pathway. These findings have great clinical importance in the application of propofol for patients enduring sepsis.

Effects of propofol on damage of rat intestinal epithelial cells induced by heat stress and lipopolysaccharides

Gut-derived endotoxin and pathogenic bacteria have been proposed as important causative factors of morbidity and death during heat stroke. However, it is still unclear what kind of damage is induced by heat stress. In this study, the rat intestinal epithelial cell line (IEC-6) was treated with heat stress or a combination of heat stress and lipopolysaccharide (LPS). In addition, propofol, which plays an important role in anti-inflammation and organ protection, was applied to study its effects on cellular viability and apoptosis. Heat stress, LPS, or heat stress combined with LPS stimulation can all cause intestinal epithelial cell damage, including early apoptosis and subsequent necrosis. However, propofol can alleviate injuries caused by heat stress, LPS, or the combination of heat stress and LPS. Interestingly, propofol can only mitigate LPS-induced intestinal epithelial cell apoptosis, and has no protective role in heat-stress-induced apoptosis. This study developed a model that can mimic the intestinal heat stress environment. It demonstrates the effects on intestinal epithelial cell damage, and indicated that propofol could be used as a therapeutic drug for the treatment of heat-stress-induced intestinal injuries.

Role of HMGB1 in propofol protection of rat intestinal epithelial cells injured by heat shock

Gut-derived endotoxin and pathogenic bacteria may be important causative factors of morbidity and death during heat stroke. However, as the key component of intestinal mucosal barrier, the molecular mechanism of how intestinal epithelial cells are injured by heat shock is remains unclear. After rat intestinal epithelial cells (IEC-6) had been exposed to heat shock, their viability was measured. Propofol, which plays an important role in anti-inflammation and organ protection, was investigated to see how it affected viability under this stress. Changes of high mobility group box 1 (HMGB1) in IEC-6 cells were measured with RT-PCR and Western blot assay at transcription and translational levels, respectively. Ethyl pyruvate (EP), a specific inhibitor of HMGB1 that can inhibit the release of HMGB1 without affecting its intracellular synthesis, was also investigated. Heat shock significantly reduced the intracellular level of HMGB1, and propofol inhibit its reduction. Propofol protected the heat shock-injured cells, at least partly through inhibiting the release of intracellular HMGB1 to reduce the direct or indirect cell damage caused by HMGB1. Pretreatment with high concentrations of EP also attenuated heat-shock injury.

Concerns of the anesthesiologist: anesthetic induction in severe sepsis or septic shock patients

Septic patients portray instable hemodynamic states because of hypotension or cardiomyopathy, caused by vasodilation, thus, impairing global tissue perfusion and oxygenation threatening functions of critical organs. Therefore, it has become the primary concern of anesthesiologists in conducting anesthesia (induction, maintenance, recovery, and postoperative care), especially in the induction of those who are prone to fall into hemodynamic crisis, due to hemodynamic instability. The anesthesiologist must have a precise anesthetic plan based on a thorough preanesthetic evaluation because many cases are emergent. Primary circulatory status of patients, including mental status, blood pressure, urine output, and skin perfusion, are necessary, as well as more active assessment methods on intravascular volume status and cardiovascular function. Because it is difficult to accurately evaluate the intravascular volume, only by central venous pressure (CVP) measurements, the additional use of transthoracic echocardiography is recommended for the evaluation of myocardial performance and hemodynamic state. In order to hemodynamically stabilize septic patients, adequate fluid resuscitation must be given before induction. Most anesthetic induction agents cause blood pressure decline, however, it may be useful to use drugs, such as ketamine or etomidate, which carry less cardiovascular instability effects than propofol, thiopental and midazolam. However, if blood pressure is unstable, despite these efforts, vasopressors and inotropic agents must be administered to maintain adequate perfusion of organs and cellular oxygen uptake.

Regional citrate anticoagulation for hemorrhage experiments in rats

INTRODUCTION

Hemorrhage alone without concomitant trauma often results in a hypercoagulable state that makes it difficult to prevent clotting within the blood withdrawal catheters. Although systemic administration of heparin can ameliorate this problem, heparin use has many additional actions that may confound interpretation of the hemorrhage experiments. The problem can be resolved by the use of a dual lumen catheter that anticoagulates only the blood within the withdrawal circuit. We describe the design of such a catheter and evaluate its function in studies of hemorrhagic shock in rats.

MATERIALS AND METHODS

Construction directions are provided for the dual lumen catheter along with a commercial source. The catheters were connected to computer controllable infusion syringes. Either citrate or heparin was used for regional extracorporeal anticoagulation. Rats were anesthetized and hemorrhaged to 40mmHg for more than 15min through the use of a computer program written in Labview. Ionized calcium measurements were obtained pre- and posthemorrhage.

RESULTS

The catheters remained patent throughout the experiments. There was no significant difference in the ionized calcium whether citrate or heparin was used for extracorporeal anticoagulation.

CONCLUSION

The dual lumen catheters are suitable for the study of hemorrhagic shock in rats without the need for systemic anticoagulation. The catheters can be used with computer-controlled hemorrhage procedures.