Ethyl pyruvate prevents lethality in mice with established lethal sepsis and systemic inflammation

Low dosages: new chemotherapeutic weapons on the battlefield of immune-related disease

Chemotherapeutic drugs eliminate tumor cells at relatively high doses and are considered weapons against tumors in clinics and hospitals. However, despite their ability to induce cellular apoptosis, chemotherapeutic drugs should probably be regarded more as a class of cell regulators than cell killers, if the dosage used and the fact that their targets are involved in basic molecular events are considered. Unfortunately, the regulatory properties of chemotherapeutic drugs are usually hidden or masked by the massive cell death induced by high doses. Recent evidence has begun to suggest that low dosages of chemotherapeutic drugs might profoundly regulate various intracellular aspects of normal cells, especially immune cells. Here, we discuss the immune regulatory roles of three kinds of chemotherapeutic drugs under low-dose conditions and propose low dosages as potential new chemotherapeutic weapons on the battlefield of immune-related disease.

LPS induces HMGB1 relocation and release by activating the NF-κB-CBP signal transduction pathway in the murine macrophage-like cell line RAW264.7

BACKGROUND

High mobility group protein B1 (HMGB1) is an important late inflammatory mediator in sepsis. Understanding the mechanisms that regulate HMGB1 release from cells and their downstream signal transduction pathways may lead to the ability to develop anti-HMGB1 therapies to treat inflammation.

MATERIALS AND METHODS

We stimulated murine macrophage-like RAW 264.7 cells with lipopolysaccharide (LPS) and LPS+ ethylpyruvate (EP) and examined the resulting HMGB1 expression and release. We also studied the expression of related signal transduction factors (NF-κB, p38 MAPK, and CBP).

RESULTS AND CONCLUSION

Gene expression of HMGB1 mRNA in RAW264.7 cell showed no significant change at 0-18 h after stimulation with LPS, but increased significantly at 24, 36, and 48 h. HMGB1 mRNA expression in the LPS+EP group was significantly lower than in LPS alone. HMGB1 was distributed mainly in the nucleus; the cytoplasmic level was low before LPS stimulation. After stimulation with LPS, cytoplasmic HMGB1 increased gradually and plateaued at a high level at 12-48 h. Nuclear HMGB1 decreased gradually at 12-24 h, then increased, maintaining a comparatively high level at 36-48 h. EP prevented this pattern significantly. LPS induced p38 MAPK activation and NF-κB signal pathways first, followed by CBP activation. Activated CBP acetylated HMGB1 was stored in a crino-lysosome and secreted activated NF-κB resulted in increased transcription and synthesis of HMGB1, but the expression of up-regulated HMGB1 mRNA was delayed. Extracellular HMGB1 originated from early synthetic reserves present in the nucleus. New HMGB1 protein was synthesized in the nucleus and transferred into the cytoplasm, causing an increase in HMGB1 in the nucleus and cytoplasm. EP inhibits HMGB1 mRNA up-regulation and release from LPS- stimulated macrophages. The molecular function of EP is to attenuate the activation p38 MAPK, NF-κB, and CBP signaling pathways.

Higher hypochlorous acid scavenging activity of ethyl pyruvate compared to its sodium salt

Although a number of studies have focused on the higher ethyl pyruvate antioxidative activity than its sodium salt under various stress conditions, and the greater protective properties of the ester form have been suggested as the effect of better cell membrane penetration, the molecular mechanism has remained unclear. The aim of the present study was therefore to compare the antioxidative activities of sodium and ethyl pyruvate under in vitro conditions by using a liver homogenate as the model for cell membrane transport deletion. The potential effect of ethanol was also evaluated, and hypochlorous acid was used as an oxidant. Our data indicate the concentration-dependent scavenging potency of both sodium and ethyl pyruvate, with the ester having higher activity. This effect was not related to the presence of ethanol. Better protection of the liver homogenate by ethyl pyruvate was also apparent, despite the fact that cell membrane transport was omitted.

EGCG stimulates autophagy and reduces cytoplasmic HMGB1 levels in endotoxin-stimulated macrophages

Historically, consumption of Green tea (Camellia sinensis) has been associated with health benefits against multiple diseases including cancer, atherosclerosis and cardiovascular disorders. Emerging evidence has suggested a pathogenic role for HMGB1, a newly identified "late" mediator of lethal systemic inflammation, in the aforementioned diseases. Here we demonstrated that a major ingredient of Green tea, EGCG, was internalized into HMGB1-containing LC3-positive cytoplasmic vesicles (likely autophagosomes) in macrophages, and induced HMGB1 aggregation in a time-dependent manner. Furthermore, EGCG stimulated LC3-II production and autophagosome formation, and inhibited LPS-induced HMGB1 up-regulation and extracellular release. The EGCG-mediated HMGB1 inhibitory effects were diminished by inhibition of class III phosphatidylinositol-3 kinase (with 3-methyladenine) or knockdown of an essential autophagy-regulating protein, beclin-1. Moreover, the EGCG-mediated protection against lethal sepsis was partly impaired by co-administration of an autophagy inhibitor, chloroquine. Taken together, the present study has suggested a possibility that EGCG inhibits HMGB1 release by stimulating its autophagic degradation.

Inhibitory mechanism of MMP-9 gene expression by ethyl pyruvate in lipopolysaccharide-stimulated BV2 microglial cells

Ethyl pyruvate (EP) is a stable derivative of pyruvate and has been identified as a therapeutic agent for various inflammatory diseases. In the present study, we showed that EP and sodium pyruvate (SP) inhibited the production of TNF-α, nitric oxide (NO), or reactive oxygen species (ROS) in LPS-stimulated BV2 microglial cells. The inhibitory effects of EP were more potent than SP. Because matrix metalloproteinase-9 (MMP-9) plays a key role in neuroinflammation, as well as in neuronal cell death, we examined the effect of EP on MMP-9 expression. RT-PCR and Western blot analyses revealed that EP inhibits MMP-9 expression at mRNA and protein levels in LPS-stimulated BV2 cells. In addition, EP suppressed MMP-9 secretion, as demonstrated by gelatin zymography analysis. In contrast, SP did not affect MMP-9 expression at an equivalent concentration of EP. Further mechanistic studies revealed that EP inhibits MMP-9 promoter activity by reducing the binding of NF-κB and AP-1 to its cognitive binding sites. In addition, EP suppressed LPS-induced phosphorylation of p38 MAPK, ERK, and Akt, which are upstream signaling molecules in MMP-9 gene expression. Taken together, our data suggest that the inhibition of MMP-9 may be one of the factors contributing to anti-inflammatory activity of EP in LPS-stimulated microglia.

A hepatic protein, fetuin-A, occupies a protective role in lethal systemic inflammation

Background

A liver-derived protein, fetuin-A, was first purified from calf fetal serum in 1944, but its potential role in lethal systemic inflammation was previously unknown. This study aims to delineate the molecular mechanisms underlying the regulation of hepatic fetuin-A expression during lethal systemic inflammation (LSI), and investigated whether alterations of fetuin-A levels affect animal survival, and influence systemic accumulation of a late mediator, HMGB1.

Methods and Findings

LSI was induced by endotoxemia or cecal ligation and puncture (CLP) in fetuin-A knock-out or wild-type mice, and animal survival rates were compared. Murine peritoneal macrophages were challenged with exogenous (endotoxin) or endogenous (IFN-γ) stimuli in the absence or presence of fetuin-A, and HMGB1 expression and release was assessed. Circulating fetuin-A levels were decreased in a time-dependent manner, starting between 26 h, reaching a nadir around 24–48 h, and returning towards base-line approximately 72 h post onset of endotoxemia or sepsis. These dynamic changes were mirrored by an early cytokine IFN-γ-mediated inhibition (up to 50–70%) of hepatic fetuin-A expression. Disruption of fetuin-A expression rendered animals more susceptible to LSI, whereas supplementation of fetuin-A (20–100 mg/kg) dose-dependently increased animal survival rates. The protection was associated with a significant reduction in systemic HMGB1 accumulation in vivo, and parallel inhibition of IFN-γ- or LPS-induced HMGB1 release in vitro.

Conclusions

These experimental data suggest that fetuin-A is protective against lethal systemic inflammation partly by inhibiting active HMGB1 release.

Association between high-mobility group box-1 protein release and immune function of dendritic cells in thermal injury

The present study was performed to investigate in vivo the effect of high-mobility group box-1 protein (HMGB1) on the maturation of dendritic cell (DC) and the influence on T-cell-mediated immunity after thermal injury. Rats were randomly divided into 3 groups as follows: sham burn group, burn group, and burn with ethyl pyruvate (EP) treatment group, and they were sacrificed on post burn days (PBD) 1, 3, 5, and 7 respectively. MACS microbeads were used to isolate splenic DCs and column of nylon wool to obtain T cells. Phenotypes were analyzed by flow cytometry and cytokines were determined with ELISA kits. The expression levels of splenic HMGB1 were significantly elevated during PBD 1-7. DC expressed similar CD80 levels, strongly enhanced CD86, and slightly elevated MHC class II levels in comparison to DC from sham-injured rats, and protein levels of IL-12 were not increased after thermal injury. Administration of EP to inhibit HMGB1 could significantly enhance expression levels of CD80, MHC class II on DC surface, and IL-12 production after burns. Simultaneously, proliferative activity and expression levels of IL-2 as well as IL-2R alpha of T cell were restored. These results suggested that the excessively released HMGB1 might stimulate splenic DC to mature abnormally and down-regulate the IL-12 production, and further shifting of Th1 to Th2 with suppression of T-lymphocyte immune function following burn injury.

Ethyl pyruvate reduces acute lung injury via regulation of iNOS and HO-1 expression in endotoxemic rats

BACKGROUND

Ethyl pyruvate (EP) has been shown to attenuate lipopolysaccharide (LPS)-induced acute lung injury (ALI). Induction of heme oxygenase-1 (HO-1) and suppression of inducible nitric oxide synthase (iNOS) expression provide cytoprotection in lung and vascular injury. The aim of this study is to evaluate whether the beneficial effect of EP on lung inflammation is related to HO-1 induction in a rat model of LPS-induced ALI.

MATERIALS AND METHODS

Rats were administered LPS (30 mg/kg) by intravenous infusion for 4 h to induce ALI. EP (20, 40, and 60 mg/kg/4 h i.v. infusion) or vehicle was given 1 h after LPS initiation.

RESULTS

EP 40 and 60 mg/kg attenuated plasma levels of TNF-α and IL-6 caused by LPS, and further increased IL-10 levels compared with the LPS group. At 6 h after LPS initiation, iNOS protein expression in lungs and plasma NO metabolite levels were markedly increased, which were reduced by EP 60 mg/kg. LPS caused a significant HO-1 induction, whereas administration of EP 60 mg/kg significantly induced higher HO-1 expression compared with the LPS group. The beneficial effects of EP on cytokines and iNOS expression were reversed by HO-1 inhibitor SnPP. EP significantly suppressed phosphorylated p38 MAPK and increased phosphorylated ERK1/2 protein levels in the lung tissue. The edema and infiltration of neutrophils into lungs was reduced by EP.

CONCLUSION

EP reduced LPS-induced ALI, which may be mediated by induction of HO-1. The underlying mechanisms are associated with suppression of p38 MAPK and increase of ERK1/2 signaling pathway activation.

Ethyl pyruvate diminishes the endotoxin-induced inflammatory response of bovine mammary endothelial cells

The endotoxin-induced inflammatory response during coliform mastitis is difficult to control with the currently available therapeutics. Endothelial cells are among the first cell type to be engaged in the inflammatory response and can modulate the severity of inflammation by producing proinflammatory mediators upon endotoxin exposure. Ethyl pyruvate, an ethyl ester of pyruvic acid, can ameliorate endotoxin-induced inflammatory responses by inhibiting the production of proinflammatory mediators in several in vitro and in vivo endotoxemia models. The objective of this study was to determine the effect of ethyl pyruvate on the production of vascular proinflammatory mediators that are associated with the pathogenesis of coliform mastitis. The ability of ethyl pyruvate to reduce the expression of proinflammatory mediators was evaluated in cultured bovine mammary endothelial cells (BMEC) stimulated with endotoxin. Treatment of endotoxin-stimulated BMEC with ethyl pyruvate significantly reduced gene expression of IL-6, IL-8, and intercellular adhesion molecule 1 as well as expression of eicosanoid-producing enzymes, including cyclooxygenase 2 and 15-lipoxygenase 1. This is the first time that the effect of ethyl pyruvate was evaluated in an in vitro BMEC model of coliform mastitis. The ability of ethyl pyruvate to effectively inhibit gene and protein expression of potent vascular proinflammatory mediators in vitro warrants further investigations to assess in vivo efficacy. Ethyl pyruvate is safe for human consumption, and it may be an attractive candidate as a therapeutic in ameliorating the severe pathogenesis associated with coliform mastitis.

Preliminary safety and biological efficacy studies of ethyl pyruvate in normal mature horses

REASONS FOR PERFORMING THE STUDY

Endotoxaemia causes substantial morbidity and mortality in horses with colic and sepsis. Ethyl pyruvate is a novel anti-inflammatory medication that improved survival in preclinical models of severe sepsis endotoxaemia and intestinal ischaemia and reperfusion in rodents, swine, sheep and dogs and may be a useful medication in horses.

HYPOTHESIS

Ethyl pyruvate has no adverse effects in normal horses and is biologically active based on suppression of proinflammatory gene expression in endotoxin stimulated whole blood, in vitro.

METHODS

Physical and neurological examinations, behaviour scores, electrocardiograms and clinicopathological tests were performed on 5 normal healthy horses receiving 4 different doses of ethyl pyruvate. Doses included 0, 50, 100 and 150 mg/kg bwt administered in a randomised crossover design with a 2 week washout period between doses. Biological efficacy was assessed by stimulating whole blood with endotoxin from the horses that received ethyl pyruvate prior to and 1 and 6 h after drug infusion. Gene expression for TNFα, IL-1β and IL-6 was assessed.

RESULTS

There were no effects of drug or dose (0, 50, 100 or 150 mg/kg bwt) on any of the physical or neurological examination, behaviour factors, electrocardiogram or clinical pathological results collected from any of the horses. All parameters measured remained within the normal reference range. There was a significant reduction in TNFα, IL-1β and IL-6 gene expression in endotoxin stimulated whole blood from horses 6 h after receiving 150 mg/kg bwt ethyl pyruvate. There were no detectable effects on gene expression of any of the other doses of ethyl pyruvate tested.

CONCLUSION

We were unable to detect any detrimental effects of ethyl pyruvate administration in normal horses. Ethyl pyruvate significantly decreased proinflammatory gene expression in endotoxin stimulated blood 6 h after drug administration.

CLINICAL RELEVANCE

Ethyl pyruvate may be a safe, effective medication in endotoxaemic horses.

Ethyl pyruvate preserves IGF-I sensitivity toward mTOR substrates and protein synthesis in C2C12 myotubes

Bacterial infection decreases skeletal muscle protein synthesis via inhibition of the mammalian target of rapamycin (mTOR), a key regulator of translation initiation. To better define the mechanism by which muscle mTOR activity is decreased, we used an in vitro model of C2C12 myotubes treated with endotoxin [lipopolysaccharide (LPS)]and interferon (IFN)-γ to determine whether stable lipophilic pyruvate derivatives restore mTOR signaling. Myotubes treated with a combination of LPS and IFNγ down-regulated the phosphorylation of the mTOR substrates S6 kinase-1 and 4E binding protein-1. The phosphorylation of ribosomal protein S6 was decreased, whereas phosphorylation of elongation factor-2 was enhanced; all results consistent with defects in both translation initiation and elongation. LPS/IFNγ decreased protein synthesis 60% in myotubes. Treatment with methyl or ethyl pyruvate partially protected against the LPS/IFNγ-induced fall in mTOR signaling. The protective effect of ethyl and methyl pyruvate could not be replicated by an equimolar amount of sodium pyruvate. Although LPS/IFNγ treated myotubes were initially IGF-I responsive, prolonged exposure (≥ 17 h) resulted in IGF-I resistance at the level of mTOR despite normal IGF-I receptor phosphorylation. Ethyl pyruvate treatment restored IGF-I sensitivity as evidenced by the left shift in the IGF-I dose-response curve and maintained IGF-I responsiveness for a prolonged period of time. Ethyl pyruvate also restored IGF-I-stimulated protein synthesis in LPS/IFNγ-treated myotubes. Cotreatment with N-acetyl cysteine or ascorbic acid also preserved IGF-I sensitivity and mTOR activity. The data suggest that the combination of LPS and IFNγ inhibits mTOR activity and that prolonged exposure induces IGF-I resistance in myotubes. Lipophilic pyruvate derivatives and antioxidants show promise at rescuing mTOR activity and muscle protein synthesis by maintaining IGF-I sensitivity in this model.

Endogenous HMGB1 regulates autophagy

Autophagy clears long-lived proteins and dysfunctional organelles and generates substrates for adenosine triphosphate production during periods of starvation and other types of cellular stress. Here we show that high mobility group box 1 (HMGB1), a chromatin-associated nuclear protein and extracellular damage-associated molecular pattern molecule, is a critical regulator of autophagy. Stimuli that enhance reactive oxygen species promote cytosolic translocation of HMGB1 and thereby enhance autophagic flux. HMGB1 directly interacts with the autophagy protein Beclin1 displacing Bcl-2. Mutation of cysteine 106 (C106), but not the vicinal C23 and C45, of HMGB1 promotes cytosolic localization and sustained autophagy. Pharmacological inhibition of HMGB1 cytoplasmic translocation by agents such as ethyl pyruvate limits starvation-induced autophagy. Moreover, the intramolecular disulfide bridge (C23/45) of HMGB1 is required for binding to Beclin1 and sustaining autophagy. Thus, endogenous HMGB1 is a critical pro-autophagic protein that enhances cell survival and limits programmed apoptotic cell death.

Endogenous HMGB1 regulates autophagy

Autophagy clears long-lived proteins and dysfunctional organelles and generates substrates for adenosine triphosphate production during periods of starvation and other types of cellular stress. Here we show that high mobility group box 1 (HMGB1), a chromatin-associated nuclear protein and extracellular damage-associated molecular pattern molecule, is a critical regulator of autophagy. Stimuli that enhance reactive oxygen species promote cytosolic translocation of HMGB1 and thereby enhance autophagic flux. HMGB1 directly interacts with the autophagy protein Beclin1 displacing Bcl-2. Mutation of cysteine 106 (C106), but not the vicinal C23 and C45, of HMGB1 promotes cytosolic localization and sustained autophagy. Pharmacological inhibition of HMGB1 cytoplasmic translocation by agents such as ethyl pyruvate limits starvation-induced autophagy. Moreover, the intramolecular disulfide bridge (C23/45) of HMGB1 is required for binding to Beclin1 and sustaining autophagy. Thus, endogenous HMGB1 is a critical pro-autophagic protein that enhances cell survival and limits programmed apoptotic cell death.

Simvastatin treatment improves survival in a murine model of burn sepsis: Role of interleukin 6

Infection is the most common and most serious complication of a major burn related to burn size. Recent studies have demonstrated that statin treatment can decrease mortality in murine or human sepsis. In the current study mice were anesthetized and subjected to a dorsal 30% TBSA scald burn. Simvastatin or placebo were administered by intraperitoneal injection once daily or every 12h. On post burn day 7 cecal ligation and puncture with a 21-gauge needle (CLP) was performed under ketamine/xylazine anesthesia, the two different dosing schedules were continued and survival was monitored. In other groups of mice, interleukin-6 (IL-6) levels in blood were measured in mice at 7 days after injury. A simvastatin dependent improvement in survival was observed in the burn sepsis model. This protection was found to be dose and time dependent. In addition, statin treatment reduced the elevation in IL-6 levels of mice burned 7 days previously. However, IL-6 levels in burned mice with or without statin treatment were elevated by CLP to the same degree. The results of these studies suggest that statin treatment reduces mortality in mice with burns and CLP and that this effect may not be mediated via IL-6 levels.

Using Complementary and Alternative Medicines to Target the Host Response during Severe Influenza

It is now accepted that an overwhelming inflammatory response is the cause of human deaths from avian H5N1 influenza infection. With this in mind we sought to examine the literature for examples of complementary and alternative medicines that reduce inflammation, and to place the results of this search in the context of our own work in a mouse model of influenza disease, using a pharmaceutical agent with anti-inflammatory properties. Two Chinese herbs, Angelica sinensis (Dang Gui) and Salvia miltiorrhiza (Danshen), have been recently shown to protect mice during lethal experimental sepsis via inhibition of the novel inflammatory cytokine High Mobility Group Box 1 protein (HMGB1). Biochanin A, a ligand of the peroxisome proliferator activated receptors (PPAR) alpha and gamma and the active isoflavone in Trifolium pratense (red clover), has anti-inflammatory properties, and thus could be used as an influenza treatment. This is of great interest since we have recently shown that gemfibrozil, a drug used to treat hyperlipidemia in humans and a synthetic ligand of PPAR alpha, significantly reduces the mortality associated with influenza infections in mice. The inflammation-modulating abilities of these natural agents should be considered in light of what is now known about the mechanisms of fatal influenza, and tested as potential candidates for influenza treatments in their own right, or as adjunct treatments to antivirals.

Cutaneous lupus erythematosus: recent lessons from animal models

Cutaneous lupus erythematosus (CLE) may present as a clinically heterogeneous group of lupus-specific skin lesions that have common histopathological findings. Determination of the immunopathological sequence of events in this group of disorders has been challenging for dermatologists and immunologists but is vital for therapeutic targeting. We review animal models in which different aspects of immune alteration in CLE have been addressed. The MRL/lpr mouse develops spontaneous skin disease with some features of CLE. Study of this strain and related gene-manipulated strains has revealed roles for multiple cytokines, including interleukin (IL)-6, IL-18, and IL-21, in disease pathogenesis. A role for the growth factor colony stimulating factor 1 and the inflammatory protein high-mobility group box 1 has also been suggested. We discuss potential novel treatment options suggested by these models.

Ethyl pyruvate prevents inflammatory responses and organ damage during resuscitation in porcine hemorrhage

Hemorrhage remains a common cause of death despite the recent advances in critical care, in part because conventional resuscitation fluids fail to prevent lethal inflammatory responses. Here, we analyzed whether ethyl pyruvate can provide a therapeutic anti-inflammatory potential to resuscitation fluids and prevent organ damage in porcine hemorrhage. Adult male Yorkshire swine underwent lethal hemorrhage with trauma and received no resuscitation treatment or resuscitation with Hextend alone, or supplemented with ethyl pyruvate. Resuscitation with ethyl pyruvate did not improve early hemodynamics but prevented hyperglycemia, the intrinsic coagulation pathway, serum aspartate aminotransferase, and myeloperoxidase in the major organs. Resuscitation with ethyl pyruvate provided an anti-inflammatory potential to restrain serum TNF and high-mobility group B protein 1 levels. Ethyl pyruvate inhibited nuclear factor [kappa]B in the spleen but not in the other major organs. In contrast, ethyl pyruvate inhibited NO in all the major organs, and it also inhibited TNF production in the major organs but in the lung and heart. The most significant effects were found in the terminal ileum where ethyl pyruvate inhibited cytokine production, restrained myeloperoxidase activity, preserved the intestinal epithelium, and prevented the systemic distribution of bacterial endotoxin. Ethyl pyruvate can provide therapeutic anti-inflammatory benefits to modulate splenic nuclear factor [kappa]B, restrain inflammatory responses, and prevent hyperglycemia, the intrinsic coagulation pathway, and organ injury in porcine hemorrhage without trauma.

Ethyl pyruvate has anti-inflammatory and delayed myocardial protective effects after regional ischemia/reperfusion injury

PURPOSE

Ethyl pyruvate has anti-inflammatory properties and protects organs from ischemia/reperfusion (I/R)-induced tissue injury. The aim of this study was to determine whether ethyl pyruvate decreases the inflammatory response after regional I/R injury and whether ethyl pyruvate protects against delayed regional I/R injury in an in vivo rat heart model after a 24 hours reperfusion.

MATERIALS AND METHODS

Rats were randomized to receive lactated Ringer's solution or ethyl pyruvate dissolved in Ringer's solution, which was given by intraperitoneal injection 1 hour prior to ischemia. Rats were subjected to 30 min of ischemia followed by reperfusion of the left coronary artery territory. After a 2 hours reperfusion, nuclear factor κB, myocardial myeloperoxidase activity, and inflammatory cytokine levels were determined. After the 24 hours reperfusion, the hemodynamic function and myocardial infarct size were evaluated.

RESULTS

At 2 hours after I/R injury, ethyl pyruvate attenuated I/R-induced nuclear factor κB translocation and reduced myeloperoxidase activity in myocardium. The plasma circulating levels of inflammatory cytokines decreased significantly in the ethyl pyruvate-treated group. At 24 hours after I/R injury, ethyl pyruvate significantly improved cardiac function and reduced infarct size after regional I/R injury.

CONCLUSION

Ethyl pyruvate has the ability to inhibit neutrophil activation, inflammatory cytokine release, and nuclear factor κB translocation. Ethyl pyruvate is associated with a delayed myocardial protective effect after regional I/R injury in an in vivo rat heart model.

Microglial activation in stroke: therapeutic targets

Microglial activation is an early response to brain ischemia and many other stressors. Microglia continuously monitor and respond to changes in brain homeostasis and to specific signaling molecules expressed or released by neighboring cells. These signaling molecules, including ATP, glutamate, cytokines, prostaglandins, zinc, reactive oxygen species, and HSP60, may induce microglial proliferation and migration to the sites of injury. They also induce a nonspecific innate immune response that may exacerbate acute ischemic injury. This innate immune response includes release of reactive oxygen species, cytokines, and proteases. Microglial activation requires hours to days to fully develop, and thus presents a target for therapeutic intervention with a much longer window of opportunity than acute neuroprotection. Effective agents are now available for blocking both microglial receptor activation and the microglia effector responses that drive the inflammatory response after stroke. Effective agents are also available for targeting the signal transduction mechanisms linking these events. However, the innate immune response can have beneficial as well deleterious effects on outcome after stoke, and a challenge will be to find ways to selectively suppress the deleterious effects of microglial activation after stroke without compromising neurovascular repair and remodeling.

Protective effects of hydrogen gas on murine polymicrobial sepsis via reducing oxidative stress and HMGB1 release

Despite recent advances in antibiotic therapy and intensive care, sepsis is still considered to be the most common cause of death in intensive care units. Excessive production of reactive oxygen species plays an important role in the pathogenesis of sepsis. Recently, it has been suggested that molecular hydrogen (H2) exerts a therapeutic antioxidant activity by selectively reducing hydroxyl radicals (*OH, the most cytotoxic reactive oxygen species) and effectively protects against organ damage induced by I/R. Therefore, we hypothesized that H2 treatment had a beneficial effect on sepsis. In the present study, we found that H2 inhalation starting at 1 and 6 h after cecal ligation and puncture (CLP) or sham operation significantly improved the survival rate of septic mice with moderate or severe CLP in a concentration- and time-dependent manner. Furthermore, moderate or severe CLP mice showed significant multiple organ damage characterized by the increases of lung myeloperoxidase activity, wet-to-dry weight ratio, protein concentration in bronchoalveolar lavage, serum biochemical parameters, and organ histopathologic scores at 24 h after CLP operation, which was significantly attenuated by 2% H2 treatment. In addition, we found that the beneficial effects of H2 treatment on sepsis and sepsis-associated organ damage were associated with the decreased levels of oxidative product, increased activities of antioxidant enzymes, and reduced levels of high-mobility group box 1 in serum and tissue. Thus, H2 inhalation may be an effective therapeutic strategy for patients with sepsis.

The RAGE axis in systemic inflammation, acute lung injury and myocardial dysfunction: an important therapeutic target?

BACKGROUND

The sepsis syndromes, frequently complicated by pulmonary and cardiac dysfunction, remain a major cause of death amongst the critically ill. Targeted therapies aimed at ameliorating the systemic inflammation that characterises the sepsis syndromes have largely yielded disappointing results in clinical trials. Whilst there are many potential reasons for lack of success of clinical trials, one possibility is that the pathways targeted, to date, are only modifiable very early in the course of the illness. More recent approaches have therefore attempted to identify pathways that could offer a wider therapeutic window, such as the receptor for advanced glycation end-products (RAGE) and its ligands.

PURPOSE

The objectives of this study were to review the evidence supporting the role of the RAGE axis in systemic inflammation and associated acute lung injury and myocardial dysfunction, to explore some of the problems and conflicts that these RAGE studies have raised and to consider strategies by which they might be resolved.

METHODS

MEDLINE was searched (1990-2010) and relevant literature collected and reviewed.

RESULTS AND CONCLUSION

RAGE is an inflammation-perpetuating receptor with a diverse range of ligands. Evidence supporting a role of the RAGE axis in the pathogenesis of systemic inflammation, ALI and myocardial dysfunction is compelling with numerous animal experiments showing the beneficial effects of inhibiting the RAGE axis. Despite a number of unanswered questions that need to be further addressed, the potential for inhibiting RAGE-mediated inflammation in humans undoubtedly exists.

HMGB1 release and redox regulates autophagy and apoptosis in cancer cells

The functional relationship and cross-regulation between autophagy and apoptosis is complex. Here we show that high-mobility group box 1 protein (HMGB1) is a redox-sensitive regulator of the balance between autophagy and apoptosis. In cancer cells, anti-cancer agents enhanced autophagy and apoptosis as well as HMGB1 release. HMGB1 release may be a pro-survival signal for residual cells following various cytotoxic cancer treatments. Diminished HMGB1 by shRNA transfection or inhibition of HMGB1 release by ethyl pyruvate or other small molecules led to predominantly apoptosis and decreased autophagy in stressed cancer cells. In this setting, reducible HMGB1 binds to the receptor for advanced glycation end products (RAGE) but not Toll-like receptor 4 (TLR4), induces Beclin1-dependent autophagy, and promotes tumor resistance to alkylators (melphalan), tubulin disrupting agents (paclitaxel), DNA crosslinkers (ultraviolet light) and DNA-intercalators (oxaliplatin or adriamycin). Oxidized HMGB1 conversely increases the cytotoxicity of these agents and induces apoptosis mediated by the caspase-9/-3 intrinsic pathway. HMGB1 release as well as its redox state thus link autophagy and apoptosis, representing a suitable target when coupled with conventional tumor treatments.

High mobility group box 1 protein as a potential drug target for infection- and injury-elicited inflammation

In response to infection or injury, a ubiquitous nucleosomal protein, HMGB1 is secreted actively by innate immune cells, and / or released passively by injured/damaged cells. Subsequently, extracellular HMGB1 alerts, recruits, and activates various innate immune cells to sustain a rigorous inflammatory response. A growing number of HMGB1 inhibitors ranging from neutralizing antibodies, endogenous hormones, to medicinal herb-derived small molecule HMGB1 inhibitors (such as nicotine, glycyrrhizin, tanshinones, and EGCG) are proven protective against lethal infection and ischemic injury. Here we review emerging evidence that support extracellular HMGB1 as a proinflammatory alarmin(g) danger signal, and discuss a wide array of HMGB1 inhibitors as potential therapeutic agents for sepsis and ischemic injury.

Novel insights for systemic inflammation in sepsis and hemorrhage

The inflammatory responses in sepsis and hemorrhage remain a major cause of death. Clinically, it is generally accepted that shock in sepsis or hemorrhage differs in its mechanisms. However, the recognition of inflammatory cytokines as a common lethal pathway has become consent. Proinflammatory cytokines such as tumor necrosis factor (TNF) or high-mobility group box1 (HMGB1) are fanatically released and cause lethal multiorgan dysfunction. Inhibition of these cytokines can prevent the inflammatory responses and organ damage. In seeking potential anti-inflammatory strategies, we reported that ethyl pyruvate and alpha7 nicotinic acetylcholine receptor (alpha7nAChR) agonists effectively restrained cytokine production to provide therapeutic benefits in both experimental sepsis and hemorrhage. Here, we review the inflammatory responses and the anti-inflammatory strategies in experimental models of sepsis and hemorrhage, as they may have a consistent inflammatory pathway in spite of their different pathophysiological processes.

Mast cell stabilization improves survival by preventing apoptosis in sepsis

Inhibiting single cytokines produced modest effects in clinical trials, in part because the cytokines were not specific for sepsis, and sepsis may require cellular strategies. Previous studies reported that mast cells (MCs) fight infections in early sepsis. In this study, we report that MC stabilizers restrain serum TNF levels and improve survival in wild-type but not in MC-deficient mice. Yet, MC depletion in knockout mice attenuates serum TNF but does not improve survival in sepsis. Serum HMGB1 was the only factor correlating with survival. MC stabilizers inhibit systemic HMGB1 levels and rescue mice from established peritonitis. MC stabilizers fail to inhibit HMGB1 secretion from macrophages, but they prevent apoptosis and caspase-3 activation in sepsis. These results suggest that MC stabilization provides therapeutic benefits in sepsis by inhibiting extracellular release of HMGB1 from apoptotic cells. Our study provides the first evidence that MCs have major immunological implications regulating cell death in sepsis and represent a pharmacological target for infectious disorders in a clinically realistic time frame.

Ethyl pyruvate downregulates tumor necrosis factor alpha and interleukin (IL)-6 and upregulates IL-10 in lipopolysaccharide-stimulated canine peripheral blood mononuclear cells

We investigated the anti-inflammatory effects of ethyl pyruvate (EP) on LPS-stimulated canine PBMCs in vitro. We found that EP treatment inhibited the mRNA expressions of proinflammatory cytokines (TNF-α and IL-6), but induced mRNA expression of anti-inflammatory cytokines (IL-10). ELISA measurements revealed that EP also effectively downregulates the LPS-induced increase in proinflammatory cytokine release, while upregulating anti-inflammatory cytokine release. These data indicate that EP could be an effective anti-inflammatory agent in dogs.

High-mobility group box 1 and cancer

High-mobility group box 1 protein (HMGB1), a chromatin associated nuclear protein and extracellular damage associated molecular pattern molecule (DAMP), is an evolutionarily ancient and critical regulator of cell death and survival. Overexpression of HMGB1 is associated with each of the hallmarks of cancer including unlimited replicative potential, ability to develop blood vessels (angiogenesis), evasion of programmed cell death (apoptosis), self-sufficiency in growth signals, insensitivity to inhibitors of growth, inflammation, tissue invasion and metastasis. Our studies and those of our colleagues suggest that HMGB1 is central to cancer (abnormal wound healing) and many of the findings in normal wound healing as well. Here, we focus on the role of HMGB1 in cancer, the mechanisms by which it contributes to carcinogenesis, and therapeutic strategies based on targeting HMGB1.

The biochemical basis for the anti-inflammatory and cytoprotective actions of ethyl pyruvate and related compounds

Pyruvate is an important metabolic intermediate, and also is an effective scavenger of hydrogen peroxide and other reactive oxygen species (ROS). Pharmacological administration of pyruvate has been shown to improve organ function in animal models of oxidant-mediated cellular injury. However, pyruvate is relatively unstable in aqueous solutions, which could limit the therapeutic potential of this compound. Ethyl pyruvate (EP), a simple derivative of pyruvic acid, is also an ROS scavenger, but seems to exert pharmacological effects, such as suppression of inflammation, which are at least quantitatively different and in some instances are qualitatively distinct from those exerted by pyruvate anion. Treatment with EP has been shown to improve survival and/or ameliorate organ dysfunction in a wide variety of pre-clinical models of acute illnesses, such as severe sepsis, acute pancreatitis and stroke. Using other animal models, some studies have demonstrated that more prolonged treatment with EP can ameliorate inflammatory bowel disease or slow the rate of growth of malignant tumors. In a clinical trial of patients undergoing cardiac surgery, treatment with EP was shown to be safe, but it failed to improve outcome. The true therapeutic potential of EP and related compounds remains to be elucidated. In this review, some of the biochemical mechanisms, which might be responsible for the pharmacological effects of EP, are discussed.

Role of high-mobility group box 1 protein in the pathogenesis of intestinal barrier injury in rats with severe acute pancreatitis

OBJECTIVE

To investigate the role of high-mobility group box 1 (HMGB1) in the development of intestinal barrier injury of severe acute pancreatitis (SAP) and to examine the effect of ethyl pyruvate (EP) on intestinal inflammation in rats with SAP.

METHODS

Rats were randomly divided into the following experimental groups: control, SAP, and EP treated. Then, the distal ileum was harvested for morphological studies, streptavidin-peroxidase immunohistochemistry examination, and Western blot analysis. The concentrations of plasma amylase, endotoxin, and diamine oxidase (DAO) and the activity of myeloperoxidase (MPO) in the intestine were determined.

RESULTS

We found that the expression of HMGB1 was up-regulated in the ileal mucosa within 6 hours and then remained elevated for more than 48 hours after SAP. Meanwhile, the levels of plasma amylase, endotoxin, and DAO and the activity of MPO in the intestinal mucosa were rapidly increased after SAP. Whereas treatment with EP significantly decreased the expression of intestinal HMGB1, the levels of plasma amylase, endotoxin, and DAO ameliorated the activity of MPO in the intestine in SAP rats.

CONCLUSIONS

Our results demonstrate that HMGB1 participates in intestinal barrier injury in SAP and EP might play a therapeutic role in intestinal inflammation in this SAP model.

The role of Toll-like receptors in renal diseases

Toll-like receptors (TLRs) have a key role in innate immunity. These receptors recognize both pathogen-associated molecular patterns and molecules that are released from damaged tissue. TLRs mediate signal transduction pathways through the activation of transcription factors that regulate the expression of proinflammatory cytokines and chemokines and are required for the development of adaptive immune responses. TLRs might have an important role in the pathogenesis of renal diseases: their exaggerated activation is associated with ischemic kidney damage, acute kidney injury, end-stage renal failure, acute tubulointerstitial nephritis, acute renal transplant rejection and delayed allograft function. As the results of previous studies concerning the role of TLRs in renal diseases are conflicting, further work is needed to determine the exact role of these receptors and to evaluate strategies to prevent TLR-mediated local inflammation. This Review discusses the evidence supporting a role for TLRs in contrasting bacterial infections and in causing or aggravating renal conditions when TLR activation leads to a harmful inflammatory response.

Immunotherapeutic suppression of indoleamine 2,3-dioxygenase and tumor growth with ethyl pyruvate

Efforts to improve cancer care in the developing world will benefit from the identification of simple, inexpensive, and broadly applicable medical modalities based on emergent innovations in treatment, such as targeting mechanisms of tumoral immune tolerance. In this report, we offer preclinical evidence that the low-cost, anti-inflammatory agent ethyl pyruvate elicits a potent immune-based antitumor response through inhibition of indoleamine 2,3-dioxygenase (IDO), a key tolerogenic enzyme for many human tumors. Consistent with its reported ability to interfere with NF-kappaB function, ethyl pyruvate blocks IDO induction both in vitro and in vivo. Antitumor activity was achieved in mice with a noncytotoxic dosing regimen of ethyl pyruvate shown previously to protect against lethality from sepsis. Similar outcomes were obtained with the functional ethyl pyruvate analogue 2-acetamidoacrylate. Ethyl pyruvate was ineffective at suppressing tumor outgrowth in both athymic and Ido1-deficient mice, providing in vivo corroboration of the importance of T-cell-dependent immunity and IDO targeting for ethyl pyruvate to achieve antitumor efficacy. Although ethyl pyruvate has undergone early-phase clinical testing, this was done without consideration of its possible applicability to cancer. Our findings that IDO is effectively blocked by ethyl pyruvate treatment deepen emerging links between IDO and inflammatory processes. Further, these findings rationalize oncologic applications for this agent by providing a compelling basis to reposition ethyl pyruvate as a low-cost immunochemotherapy for clinical evaluation in cancer patients.

Peritoneal inflammation after twenty-week exposure to dialysis solution: effect of solution versus catheter-foreign body reaction

BACKGROUND

We hypothesized that both sterile solutions and foreign body reaction to the peritoneal dialysis catheter are associated with inflammatory changes in rats exposed to hypertonic solution.

METHODS

Four hypertonic solutions (30 - 40 mL) were injected daily via needle and syringe over 20 weeks in 4 groups of rats: 4.25% standard clinical solution (LAC), LAC plus pyridoxamine (PYR), LAC plus ethyl pyruvate (EP), and a biocompatible 4% dextrose solution (BIC). Two groups received catheters: a non-injected 4-week catheter group (C4) and a group injected for 20 weeks with the BIC solution (CI). Control animals (CON) were not injected. In the C4 group, adherent cells were separated from the catheter and examined by culture and electron microscopy to ensure that animals were bacteria free prior to exposure to solution. Animals underwent transport experiments to determine mass transfer coefficients of mannitol (MTC(M)) and albumin (MTC(A)), osmotic filtration flux (J(osm)), and hydrostatic pressure-driven flux (J(p)). After euthanasia, tissues were examined for submesothelial thickness, vascular density, and immunohistochemistry for various cytokines.

RESULTS

The catheter cell layer was free of bacteria and consisted of macrophages, lymphocytes, mesothelial cells, and fibroblastic cells. Marked differences in angiogenesis and submesothelial thickening were noted for the catheter groups. Transport differences were mixed: MTC(M) was significantly less for the CI group and MTC(A) was variable among the groups. There were no differences among groups for J(osm) or J(p). Inflammatory markers in the catheter-adherent cells correlated with inflammatory changes in the tissue. These data demonstrate significant changes in submesothelial thickness, angiogenesis, transport function, and inflammatory markers between animals injected with sterile solutions over 20 weeks with and without catheters.

CONCLUSION

An indwelling catheter amplifies peritoneal inflammation from dialysis solutions through a foreign body reaction. Our data also suggest that additives to existing solutions may have limited the effect on inflammatory response to non-biocompatible solutions.

Novel HMGB1-inhibiting therapeutic agents for experimental sepsis

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. The inflammatory response is partly mediated by innate immune cells (such as macrophages, monocytes, and neutrophils), which not only ingest and eliminate invading pathogens but also initiate an inflammatory response by producing early (e.g., TNF and IFN-gamma) and late (e.g., high-mobility group box [HMGB1]) proinflammatory cytokines. Here, we briefly review emerging evidence that support extracellular HMGB1 as a late mediator of experimental sepsis and discuss therapeutic potential of several HMGB1-inhibiting agents (including neutralizing antibodies and steroid-like tanshinones) in experimental sepsis.

Can we predict the effects of NF-kappaB inhibition in sepsis? Studies with parthenolide and ethyl pyruvate

BACKGROUND

Based partially on encouraging findings from preclinical models, interest has grown in therapeutic inhibition of NF-kappaB to limit inflammatory injury during sepsis. However, NF-kappaB also regulates protective responses, and predicting the net survival effects of such inhibition may be difficult.

OBJECTIVES

To highlight the caution necessary with this therapeutic approach, we review our investigations in a mouse sepsis model with parthenolide and ethyl pyruvate, two NF-kappaB inhibitors proposed for clinical study.

RESULTS

Consistent with published studies, parthenolide decreased NF-kappaB binding activity and inflammatory cytokine release from lipopolysaccharide (LPS) stimulated RAW 264.7 cells in vitro. In LPS-challenged mice (C57BL/6J), however, while both agents decreased lung and kidney NF-kappaB binding activity and plasma cytokines early (1-3 h), these measures were increased later (6-12 h) in patterns differing significantly over time. Furthermore, despite studying several doses of parthenolide (0.25-4.0 mg/kg) and ethyl pyruvate (0.1-100 mg/kg), each produced small but consistent decreases in survival which overall were significant (p < or = 0.04 for each agent).

CONCLUSION

While NF-kappaB inhibitors hold promise for inflammatory conditions such as sepsis, caution is necessary. Clear understanding of the net effects of NF-kappaB inhibitors on outcome will be necessary before such agents are used clinically.

Inflammatory response and immune regulation of high mobility group box-1 protein in treatment of sepsis

Sepsis is an infection induced systemic inflammatory response syndrome and is a major cause of morbidity as well as mortality in intensive care units. A growing body of evidence suggests that the activation of a proinflammatory cascade is responsible for the development of immune dysfunction, susceptibility to severe sepsis and septic shock. The present theories of sepsis as a dysregulated inflammatory response and immune function, as manifested by excessive release of inflammatory mediators such as high mobility group box 1 protein (HMGB1), are supported by increasing studies employing animal models and clinical observations of sepsis. HMGB1, originally described as a DNA-binding protein and released passively by necrotic cells and actively by macrophages/monocytes, has been discovered to be one of essential cytokines that mediates the response to infection, injury and inflammation. A growing number of studies still focus on the inflammation-regulatory function and its contribution to infectious and inflammatory disorders, recent data suggest that HMGB1 formation can also markedly influence the host cell-mediated immunity, including T lymphocytes and macrophages. Here we review emerging evidence that support extracellular HMGB1 as a late mediator of septic complications, and discuss the therapeutic potential of several HMGB1-targeting agents in experimental sepsis. In addition, with the development of traditional Chinese medicine in recent years, it has been proven that traditional Chinese herbal materials and their extracts have remarkable effective in treating severe sepsis. In this review, we therefore provide some new concepts of HMGB1-targeted Chinese herbal therapies in sepsis.

Ethyl pyruvate protects against hypoxic-ischemic brain injury via anti-cell death and anti-inflammatory mechanisms

Ethyl pyruvate (EP) is protective in experimental models of many illnesses. This study investigates whether EP can protect against neonatal hypoxic-ischemic (H-I) brain injury. Pre-treatment with EP significantly reduced brain damage at 7 days post-H-I, with 50 mg/kg EP achieving over 50% recovery in tissue loss compared to vehicle-treated animals. Delayed treatment with EP until 30 min after H-I was still neuroprotective. EP-afforded brain protection, together with neurological function improvement, was observed up to 2 months after H-I. We further demonstrated an inhibitory effect of EP on cell death, both in an in vivo model of H-I and in in vitro neuronal cultures subjected to OGD, by reducing calpain activation and calcium dysregulation. Moreover, EP exerted an anti-inflammatory effect in microglia by inhibiting NF-kappaB activation and subsequent release of inflammatory mediators. Taken together, our results suggest that EP confers potent neuroprotection against neonatal H-I brain injury via its anti-cell death and anti-inflammatory actions. EP is a potential novel therapeutic agent for neonatal H-I brain injury.

[HMGB1: a link between innate and adaptive immunity]

La protéine HMGB1 (high mobility group box 1) a été originalement identifiée comme une protéine nucléaire capable de se fixer à l’ADN. Elle est considérée comme un facteur architectural de la chromatine. Des travaux récents ont pu montrer qu’HMGB1 pouvait être également présente dans le milieu extracellulaire et ont permis de caractériser les processus cellulaires qui conduisent à la libération de la protéine. HMGB1 peut se retrouver dans le milieu extracellulaire de deux façons : (1) lors d’une sécrétion active par les cellules de l’inflammation ; (2) lors d’une libération passive et rapide lorsque les cellules meurent par nécrose. Dans ces conditions, la protéine HMGB1 est capable d’agir comme un médiateur soluble impliqué dans la coordination de divers mécanismes cellulaires. HMGB1 joue un rôle crucial dans l’amplification de la réponse inflammatoire, dans l’établissement de la réponse immunitaire et dans la réparation tissulaire. Cependant, la protéine HMGB1 dans le milieu extracellulaire serait également capable d’agir comme une cytokine pro-inflammatoire et contribuerait ainsi à la pathogenèse de différentes maladies qu’elles soient d’origine inflammatoire ou infectieuse.

Targeting HMGB1 in inflammation

High mobility group box 1 (HMGB1), a highly conserved, ubiquitous protein present in the nuclei and cytoplasm of nearly all cell types, is a necessary and sufficient mediator of inflammation during sterile and infection-associated responses. Elevated levels of HMGB1 in serum and tissues occur during sterile tissue injury and during infection, and targeting HMGB1 with antibodies or specific antagonists is protective in established preclinical inflammatory disease models including lethal endotoxemia or sepsis, collagen-induced arthritis, and ischemia-reperfusion induced tissue injury. Future advances in this field will stem from understanding the biological basis for the success of targeting HMGB1 to therapeutic improvement in the treatment of inflammation, infection and ischemia-reperfusion induced injury.

A systematic review of experimental treatments for mitochondrial dysfunction in sepsis and multiple organ dysfunction syndrome

Sepsis and multiple organ dysfunction syndrome (MODS) are major causes of morbidity and mortality in the intensive care unit. Recently mitochondrial dysfunction has been proposed as a key early cellular event in critical illness. A growing body of experimental evidence suggests that mitochondrial therapies are effective in sepsis and MODS. The aim of this article is to undertake a systematic review of the current experimental evidence for the use of therapies for mitochondrial dysfunction during sepsis and MODS and to classify these mitochondrial therapies. A search of the MEDLINE and PubMed databases (1950 to July 2009) and a manual review of reference lists were conducted to find experimental studies containing data on the efficacy of mitochondrial therapies in sepsis and sepsis-related MODS. Fifty-one studies were included in this review. Five categories of mitochondrial therapies were defined-substrate provision, cofactor provision, mitochondrial antioxidants, mitochondrial reactive oxygen species scavengers, and membrane stabilizers. Administration of mitochondrial therapies during sepsis was associated with improvements in mitochondrial electron transport system function, oxidative phosphorylation, and ATP production and a reduction in cellular markers of oxidative stress. Amelioration of proinflammatory cytokines, caspase activation, and prevention of the membrane permeability transition were reported. Restoration of mitochondrial bioenergetics was associated with improvements in hemodynamic parameters, organ function, and overall survival. A substantial body of evidence from experimental studies at both the cellular and the organ level suggests a beneficial role for the administration of mitochondrial therapies in sepsis and MODS. We expect that mitochondrial therapies will have an increasingly important role in the management of sepsis and MODS. Clinical trials are now required.

Early release of high mobility group box nuclear protein 1 after severe trauma in humans: role of injury severity and tissue hypoperfusion

Introduction

High mobility group box nuclear protein 1 (HMGB1) is a DNA nuclear binding protein that has recently been shown to be an early trigger of sterile inflammation in animal models of trauma-hemorrhage via the activation of the Toll-like-receptor 4 (TLR4) and the receptor for the advanced glycation endproducts (RAGE). However, whether HMGB1 is released early after trauma hemorrhage in humans and is associated with the development of an inflammatory response and coagulopathy is not known and therefore constitutes the aim of the present study.

Methods

One hundred sixty eight patients were studied as part of a prospective cohort study of severe trauma patients admitted to a single Level 1 Trauma center. Blood was drawn within 10 minutes of arrival to the emergency room before the administration of any fluid resuscitation. HMGB1, tumor necrosis factor (TNF)-α, interleukin (IL)-6, von Willebrand Factor (vWF), angiopoietin-2 (Ang-2), Prothrombin time (PT), prothrombin fragments 1+2 (PF1+2), soluble thrombomodulin (sTM), protein C (PC), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) and D-Dimers were measured using standard techniques. Base deficit was used as a measure of tissue hypoperfusion. Measurements were compared to outcome measures obtained from the electronic medical record and trauma registry.

Results

Plasma levels of HMGB1 were increased within 30 minutes after severe trauma in humans and correlated with the severity of injury, tissue hypoperfusion, early posttraumatic coagulopathy and hyperfibrinolysis as well with a systemic inflammatory response and activation of complement. Non-survivors had significantly higher plasma levels of HMGB1 than survivors. Finally, patients who later developed organ injury, (acute lung injury and acute renal failure) had also significantly higher plasma levels of HMGB1 early after trauma.

Conclusions

The results of this study demonstrate for the first time that HMGB1 is released into the bloodstream early after severe trauma in humans. The release of HMGB1 requires severe injury and tissue hypoperfusion, and is associated with posttraumatic coagulation abnormalities, activation of complement and severe systemic inflammatory response.

Ethyl pyruvate administration inhibits hepatic tumor growth

EP is a potent inhibitor of HMGB1 release that has significant anti-inflammatory activities and exerts a protective effect in animal models of inflammation. As inflammation is linked to cancer growth, we hypothesized that EP would have anti-tumor activity and explored its effects in a liver tumor model. Mice injected intraportally with MC38 colorectal cancer cells led to the growth of visible hepatic tumors within 2 weeks. Pretreatment with EP 30 min prior to infusion of tumor cells and continuing daily for 9 days inhibited tumor growth significantly in a dose-dependent manner, with 80 mg/kg EP achieving >70% reduction in the number of tumor nodules when compared with untreated animals. Delayed treatment with EP also suppressed tumor growth significantly, although to a lesser extent. Tumors had early, marked leukocytic infiltrates, and EP administration decreased innate (NK cells, monocytes) and adaptive (T and B cell lymphocytic) immune cell infiltrates acutely and significantly in the liver. Serum IL-6 and HMGB1 levels, which were elevated following tumor injection, were decreased significantly in EP-treated animals. Tumors showed an increase in apoptosis in EP treated mice, and tumor cells treated in vitro with EP had marked increases in LC3-II and cleaved PARP, consistent with enhanced autophagic flux and apoptosis. Thus, EP inhibition of tumor growth in the liver was mediated by tumor (induction of apoptosis) and host (decreased inflammation) effects. EP administration may have a therapeutic role in the treatment of cancer in conjunction with other therapeutic agents.

Ethyl pyruvate reduces mortality in an endotoxin-induced severe acute lung injury mouse model

Background

Ethyl pyruvate (EP) was recently identified as an experimental therapeutic agent in a wide variety of model systems for inflammation-mediated tissue and cellular injury.

Objective

To evaluate the effect of ethyl EP on improving the survival in mice with LPS-induced acute lung injury (ALI).

Methods

ALI was induced by administering lipopolysaccharide (LPS) intratracheally. The mice were treated intraperitoneally (i.p.) with 100, 50 and 10 mg/kg EP immediately before intratracheal instillation of LPS, and 100 mg/kg EP was administered 0, 12, 24 and 48 hours after induction of ALI. The mortality rate was recorded and analyzed by the Kaplan-Meier method. Serum tumor necrosis factor (TNF)-α, interleukin (IL) -6 and IL-1 β were measured in bronchial alveolar lavage fluid using an enzyme-linked immunosorbent assay. High-mobility group box 1 levels were measured by Western immunoblotting.

Results

Treatment with EP significantly inhibited the release of HMGB1, TNF-α, IL-6 and IL-1β into bronchoalveolar lavage (BAL) fluids of ALI mice, and reduced the permeability index of the injured lung. High EP doses reduced the mortality from ALI and the permeability index (100 mg/kg and 50 mg/kg EP versus control; P < 0.0001). Early administration of high-dose EP significantly increased survival rate (0, 12 and 24 h versus control; P < 0.0001, P < 0.0001 and P = 0.01 respectively by log-rank test). There was no survival advantage when EP was initiated at 48 h.

Conclusion

Ethyl pyruvate improves survival and reduces the lung permeability index in mice with LPS-induced ALI.