Ethyl pyruvate decreased early nuclear factor-kappaB levels but worsened survival in lipopolysaccharide-challenged mice

Ethyl pyruvate attenuates ventilation-induced diaphragm dysfunction through high-mobility group box-1 in a murine endotoxaemia model

Mechanical ventilation (MV) can save the lives of patients with sepsis. However, MV in both animal and human studies has resulted in ventilator-induced diaphragm dysfunction (VIDD). Sepsis may promote skeletal muscle atrophy in critically ill patients. Elevated high-mobility group box-1 (HMGB1) levels are associated with patients requiring long-term MV. Ethyl pyruvate (EP) has been demonstrated to lengthen survival in patients with severe sepsis. We hypothesized that the administration of HMGB1 inhibitor EP or anti-HMGB1 antibody could attenuate sepsis-exacerbated VIDD by repressing HMGB1 signalling. Male C57BL/6 mice with or without endotoxaemia were exposed to MV (10 mL/kg) for 8 hours after administrating either 100 mg/kg of EP or 100 mg/kg of anti-HMGB1 antibody. Mice exposed to MV with endotoxaemia experienced augmented VIDD, as indicated by elevated proteolytic, apoptotic and autophagic parameters. Additionally, disarrayed myofibrils and disrupted mitochondrial ultrastructures, as well as increased HMGB1 mRNA and protein expression, and plasminogen activator inhibitor-1 protein, oxidative stress, autophagosomes and myonuclear apoptosis were also observed. However, MV suppressed mitochondrial cytochrome C and diaphragm contractility in mice with endotoxaemia (P < 0.05). These deleterious effects were alleviated by pharmacologic inhibition with EP or anti-HMGB1 antibody (P < 0.05). Our data suggest that EP attenuates endotoxin-enhanced VIDD by inhibiting HMGB1 signalling pathway.

Ethyl Pyruvate Combats Human Leukemia Cells but Spares Normal Blood Cells

Ethyl pyruvate, a known ROS scavenger and anti-inflammatory drug was found to combat leukemia cells. Tumor cell killing was achieved by concerted action of necrosis/apoptosis induction, ATP depletion, and inhibition of glycolytic and para-glycolytic enzymes. Ethyl lactate was less harmful to leukemia cells but was found to arrest cell cycle in the G0/G1 phase. Both, ethyl pyruvate and ethyl lactate were identified as new inhibitors of GSK-3β. Despite the strong effect of ethyl pyruvate on leukemia cells, human cognate blood cells were only marginally affected. The data were compiled by immune blotting, flow cytometry, enzyme activity assay and gene array analysis. Our results inform new mechanisms of ethyl pyruvate-induced cell death, offering thereby a new treatment regime with a high therapeutic window for leukemic tumors.

Examining the Predictive Validity of NIH Peer Review Scores

The predictive validity of peer review at the National Institutes of Health (NIH) has not yet been demonstrated empirically. It might be assumed that the most efficient and expedient test of the predictive validity of NIH peer review would be an examination of the correlation between percentile scores from peer review and bibliometric indices of the publications produced from funded projects. The present study used a large dataset to examine the rationale for such a study, to determine if it would satisfy the requirements for a test of predictive validity. The results show significant restriction of range in the applications selected for funding. Furthermore, those few applications that are funded with slightly worse peer review scores are not selected at random or representative of other applications in the same range. The funding institutes also negotiate with applicants to address issues identified during peer review. Therefore, the peer review scores assigned to the submitted applications, especially for those few funded applications with slightly worse peer review scores, do not reflect the changed and improved projects that are eventually funded. In addition, citation metrics by themselves are not valid or appropriate measures of scientific impact. The use of bibliometric indices on their own to measure scientific impact would likely increase the inefficiencies and problems with replicability already largely attributed to the current over-emphasis on bibliometric indices. Therefore, retrospective analyses of the correlation between percentile scores from peer review and bibliometric indices of the publications resulting from funded grant applications are not valid tests of the predictive validity of peer review at the NIH.

NF-κB inhibition after cecal ligation and puncture reduces sepsis-associated lung injury without altering bacterial host defense

Introduction. Since the NF-κB pathway regulates both inflammation and host defense, it is uncertain whether interventions targeting NF-κB would be beneficial in sepsis. Based on the kinetics of the innate immune response, we postulated that selective NF-κB inhibition during a defined time period after the onset of sepsis would reduce acute lung injury without compromising bacterial host defense. Methods. Mice underwent cecal ligation and puncture (CLP). An NF-κB inhibitor, BMS-345541 (50 µg/g mice), was administered by peroral gavage beginning 2 hours after CLP and repeated at 6 hour intervals for 2 additional doses. Results. Mice treated with BMS-345541 after CLP showed reduced neutrophilic alveolitis and lower levels of KC in bronchoalveolar lavage fluid compared to mice treated with CLP+vehicle. In addition, mice treated with CLP+BMS had minimal histological evidence of lung injury and normal wet-dry ratios, indicating protection from acute lung injury. Treatment with the NF-κB inhibitor did not affect the ability of cultured macrophages to phagocytose bacteria and did not alter bacterial colony counts in blood, lung tissue, or peritoneal fluid at 24 hours after CLP. While BMS-345541 treatment did not alter mortality after CLP, our results showed a trend towards improved survival. Conclusion. Transiently blocking NF-κB activity after the onset of CLP-induced sepsis can effectively reduce acute lung injury in mice without compromising bacterial host defense or survival after CLP.

Possible interventional therapies in severe sepsis or septic shock

For many years, basic research with relatively straightforward pathophysiologic approaches has driven clinical trials using molecules that supposedly interfere positively with inflammatory processes. However, most of these trials have failed to demonstrate any outcome benefit. Indeed, we need to revisit current paradigms and to think about the possibility that outcome may be predetermined in severe sepsis or septic shock. In addition, an early diagnosis of sepsis prior to the onset of clinical decline is also of particular interest to health practitioners because this information increases the possibilities for early and specific treatment of this life threatening condition. Indeed, the time to initiate therapy is thought to be crucial and the major determent factor in surviving sepsis. Despite substantial progress in sepsis therapy, the gap between the discovery of new effective medical molecules and their implementation in the daily clinical practice of the intensive care unit remains a major hurdle. Fortunately, ongoing research continues to provide new information on the management of sepsis, in particular, severe sepsis or septic shock. High quality and effective management tools are necessary to bring evidence-based therapy to the bedside. On this basis, new therapies could be tested to reduce mortality rates with respect to recently published studies.

Ethyl pyruvate for the treatment of acetaminophen intoxication: alternative to N-acetylcysteine?

N-acetylcysteine is the classical antidote for acetaminophen overdose-induced hepatotoxicity, but its efficacy is limited by the need for early and only temporary treatment. Therefore, Yang and colleagues tested the hypothesis of whether ethyl pyruvate - another anti-inflammatory and antioxidant compound, which they had previously shown to protect against liver injury of various other etiologies - may allow circumventing these limitations. While ethyl pyruvate improved liver regeneration when administered early and during a limited period only, the opposite response was present both after delayed as well as prolonged treatment. The authors concluded that prolonged anti-inflammatory treatment is detrimental after acetaminophen intoxication-induced liver damage. On the one hand, this research paper confirms the need for biomarkers to monitor organ recovery after acetaminophen. On the other hand, this paper adds to the ongoing discussion on the usefulness of ethyl pyruvate as a resuscitation fluid in the critically ill.

Pyruvate: immunonutritional effects on neutrophil intracellular amino or alpha-keto acid profiles and reactive oxygen species production

For the first time the immunonutritional role of pyruvate on neutrophils (PMN), free α-keto and amino acid profiles, important reactive oxygen species (ROS) produced [superoxide anion (O(2) (-)), hydrogen peroxide (H(2)O(2))] as well as released myeloperoxidase (MPO) acitivity has been investigated. Exogenous pyruvate significantly increased PMN pyruvate, α-ketoglutarate, asparagine, glutamine, aspartate, glutamate, arginine, citrulline, alanine, glycine and serine in a dose as well as duration of exposure dependent manner. Moreover, increases in O(2) (-) formation, H(2)O(2)-generation and MPO acitivity in parallel with intracellular pyruvate changes have also been detected. Regarding the interesting findings presented here we believe, that pyruvate fulfils considerably the criteria for a potent immunonutritional molecule in the regulation of the PMN dynamic α-keto and amino acid pools. Moreover it also plays an important role in parallel modulation of the granulocyte-dependent innate immune regulation. Although further research is necessary to clarify pyruvate's sole therapeutical role in critically ill patients' immunonutrition, the first scientific successes seem to be very promising.

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.

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.

Anti-inflammatory resuscitation improves survival in hemorrhage with trauma

BACKGROUND

Hemorrhage is a common cause of death despite the recent advances in resuscitation and critical care. Conventional resuscitation fluids are designed to reestablish tissue perfusion, but they fail to prevent systemic inflammation. Indeed, resuscitation can promote inflammatory responses, which can be more dangerous than the original hemorrhage. This consideration is relevant in critical care where hemorrhage is normally associated with collateral trauma that can exacerbate the inflammatory responses during resuscitation. Here, we analyzed whether ethyl pyruvate could provide a therapeutic anti-inflammatory potential during resuscitation in experimental hemorrhage with trauma.

METHODS

Adult male Sprague-Dawley rats were subjected to trauma induced by closed femur fracture. Then, the animals were immediately subjected to lethal hemorrhage during 15 minutes to reach a mean arterial blood pressure of 35 mm Hg to 40 mm Hg and subsequent maintenance of this mean arterial blood pressure for another 15 minutes. Resuscitation was limited to 15 mL/kg Hextend with or without ethyl pyruvate.

RESULTS

Resuscitation with conventional fluids reestablished normal tissue perfusion, but still more than 60% of the animals died. Resuscitation with ethyl pyruvate protected all the animals from lethal hemorrhage with trauma. Trauma exacerbated tumor necrosis factor (TNF) levels in the serum, the spleen, and the heart. Ethyl pyruvate blunted TNF levels in the serum and all the organs but particularly in the lung and the liver during resuscitation. TNF levels in the lung, spleen, and the liver of those animals resuscitated with ethyl pyruvate were statistically similar to those in control animals.

CONCLUSION

Ethyl pyruvate may attenuate systemic inflammatory responses during resuscitation and improve survival in experimental models of hemorrhage with trauma.

Ethyl pyruvate improves survival in awake hemorrhage

Classical experimental models of hemorrhage are characterized by the use of anesthetics that may interfere with the typical immune responses and pathology of hemorrhage/resuscitation. Thus, therapeutic strategies successful in anesthetized animals might not be beneficial in clinical trials. In this study, we analyzed whether ethyl pyruvate could provide therapeutic benefits during resuscitation in awake (unanesthetized) hemorrhage. Our results indicate that hemorrhage in unanesthetized animals required approximately 25% higher blood withdrawal than anesthetized animals to achieve the same targeted mean arterial blood pressure. Resuscitation with Hextend reestablished circulatory volume and improved survival during resuscitation of awake rodents. Yet, over 75% of the animals resuscitated with Hextend died within the first hours after hemorrhage. Resuscitation with Hextend containing 50 mM ethyl pyruvate protected over 87% of the animals. This survival benefit did not correlate with significant changes in the metabolic markers but with an anti-inflammatory potential during resuscitation. Unlike classical hemorrhage in anesthetized animals, ethyl pyruvate reestablished mean arterial blood pressure significantly earlier than Hextend in unanesthetized rodents. Unanesthetized animals showed twofold higher serum tumor necrosis factor (TNF)-alpha than anesthetized animals subjected to the same blood pressure. This process was not due to the response of a single organ, but affected all the analyzed organs including the lung, heart, spleen, and liver. Although resuscitation with Hextend failed to attenuate systemic TNF-alpha levels, it inhibited TNF-alpha levels in the lung, heart, and liver but not in the spleen. Unlike Hextend, resuscitation with ethyl pyruvate prevented high serum TNF-alpha levels and blunted TNF-alpha responses in all the organs including the spleen. These studies indicate that the inflammatory responses in anesthetized animals differ from that in unanesthetized animals and that awake hemorrhage can provide advantages in the study of anti-inflammatory strategies during resuscitation. Ethyl pyruvate may attenuate systemic inflammatory responses during resuscitation and improve survival in experimental models of awake hemorrhage.

Anti-inflammatory adjuvant in resuscitation fluids improves survival in hemorrhage

OBJECTIVES

Severe hemorrhage is a common cause of death despite the recent advances in critical care. Conventional resuscitation fluids are designed to reestablish tissue perfusion, but they fail to prevent lethal inflammatory responses. Our previous studies indicate that ethyl pyruvate (EP) inhibits tumor necrosis factor (TNF) production from macrophages. Here, we analyze whether EP can provide a therapeutic anti-inflammatory value to resuscitation fluids.

DESIGN

Laboratory animal experiments.

SETTING

Animal research laboratory at university medical school.

SUBJECTS

Adult male Sprague-Dawley rats.

INTERVENTIONS

Lethal hemorrhage over 15 minutes to reach a mean arterial blood pressure of 35-40 mm Hg and subsequent maintenance of this mean arterial blood pressure for another 15 minutes. Resuscitation was limited to 15 mL/kg Hextend with or without EP.

RESULTS

Resuscitation with Hextend supplemented with EP rescued all the animals from lethal hemorrhage. Unlike conventional fluids, EP inhibited the production of inflammatory and cardiodepressant factors such as TNF and high mobility group B protein-1. From a pharmacologic perspective, resuscitation with EP was particularly effective inhibiting TNF production in the spleen and the heart. Unlike other anti-inflammatory strategies, EP mitigated systemic inflammation through a mechanism independent of the spleen. At the molecular level, EP inhibited both poly(ADP-ribose) polymerase and p65RelA DNA binding without affecting IkappaBalpha activation.

CONCLUSIONS

EP may be a promising anti-inflammatory supplement to improve survival during resuscitation in critical care.

Ethyl pyruvate modulates acute inflammatory reactions in human endothelial cells in relation to the NF-kappaB pathway

BACKGROUND AND PURPOSE

Endothelial cell activation plays a critical role in regulating leukocyte recruitment during inflammation and infection. Ethanol (EtOH) reduces host defence systems, including cell adhesion. However, well-known side effects of EtOH limit its clinical use as an anti-inflammatory drug. Instead, ethyl pyruvate (EtP) may represent a better alternative. Here, we compared effects of EtP and EtOH on neutrophil recruitment and activation of human umbilical vein endothelial cells (HUVECs).

EXPERIMENTAL APPROACH

Adhesion of neutrophils to HUVEC monolayers, surface expression of intercellular cell adhesion molecule, E-selectin, vascular cell adhesion molecule, release of interleukin (IL)-8 and granulocyte colony-stimulating factor (G-CSF) from HUVECs were assessed as well as translocation of interleukin-1 receptor-associated kinase (IRAK-1), the nuclear factor-kappa B (NF-kappaB) subunits p50, p65 and IkappaB-alpha. NF-kappaB activation was analysed with a luciferase reporter plasmid. Cells were stimulated with IL-1beta, lipopolysaccharide (LPS) or tumour necrosis factor-alpha.

KEY RESULTS

EtP was several-fold more potent than EtOH in reducing adhesion of neutrophils to activated HUVECs, generation of IL-8 or G-CSF and surface expression of the adhesion molecules. This last reaction was decreased by EtP even when added after cytokines or LPS. Translocation of IRAK-1, IkappaBalpha and the NF-kappaB p65 subunit to the HUVEC nucleus was inhibited by EtP for all stimuli, whereas the diminished p50 translocation was stimulus specific. When p65 was constitutively expressed in Cos7 cells, stimulation of an NF-kappaB-dependent reporter gene was not affected by EtP, suggesting that EtP acted upstream of gene activation.

CONCLUSIONS AND IMPLICATIONS

EtP impedes adhesive, secretory and signalling events typical of the early inflammatory response in endothelial cells, suggesting EtP as a possible treatment for acute inflammatory conditions.