Identification of Expression Patterns Associated with Hemorrhage and Resuscitation: Integrated Approach to Data Analysis

Assessment of the Cytoprotective Effects of High-Dose Valproic Acid Compared to a Clinically Used Lower Dose

OBJECTIVE

Valproic acid (VPA) treatment improves survival in animal models of injuries on doses higher than those allowed by Food and Drug Administration (FDA). We investigated the proteomic alterations induced by a single high-dose (140mg/kg) of VPA (VPA140) compared to the FDA-approved dose of 30mg/kg (VPA30) in healthy humans. We also describe the proteomic and transcriptomic changes induced by VPA140 in an injured patient. We hypothesized that VPA140 would induce cytoprotective changes in the study participants.

METHODS

Serum samples were obtained from healthy subjects randomized to two groups; VPA140 and VPA30 at 3 timepoints: 0h(baseline), 2h, and 24h following infusion(n = 3/group). Samples were also obtained from an injured patient that received VPA140 at 0h, 6h and 24h following infusion. Proteomic analyses were performed using liquid chromatography-mass spectrometry (LC-MS/MS), and transcriptomic analysis was performed using RNA-sequencing. Differentially expressed (DE) proteins and genes were identified for functional annotation and pathway analysis using iPathwayGuide and gene set enrichment analysis (GSEA), respectively.

RESULTS

For healthy individuals, a dose comparison was performed between VPA140 and VPA30 groups at 2 and 24 h. Functional annotation showed that top biological processes in VPA140 versus VPA30 analysis at 2 h included regulation of fatty acid (P = 0.002) and ATP biosynthesis (P = 0.007), response to hypoxia (P = 0.017), cell polarity regulation (P = 0.031), and sequestration of calcium ions (P = 0.031). Top processes at 24 h in VPA140 versus VPA30 analysis included amino acid metabolism (P = 0.023), collagen catabolism (P = 0.023), and regulation of protein breakdown (P = 0.023). In the injured patient, annotation of the DE proteins in the serum showed that top biological processes at 2 h included neutrophil chemotaxis (P = 0.002), regulation of cellular response to heat (P = 0.008), regulation of oxidative stress (P = 0.008) and regulation of apoptotic signaling pathway (P = 0.008). Top biological processes in the injured patient at 24 h included autophagy (P = 0.01), glycolysis (P = 0.01), regulation of apoptosis (P = 0.01) and neuron apoptotic processes (P = 0.02).

CONCLUSIONS

VPA140 induces cytoprotective changes in human proteome not observed in VPA30. These changes may be responsible for its protective effects in response to injuries.

Life on the battlefield: Valproic acid for combat applications

The leading causes of death in military conflicts continue to be hemorrhagic shock (HS) and traumatic brain injury (TBI). Most of the mortality is a result of patients not surviving long enough to obtain surgical care. As a result, there is a significant unmet need for a therapy that stimulates a "prosurvival phenotype" that counteracts the cellular pathophysiology of HS and TBI to prolong survival. Valproic acid (VPA), a well-established antiepileptic therapy for more than 50 years, has shown potential as one such prosurvival therapy. This review details how VPA's role as a nonselective histone deacetylase inhibitor induces cellular changes that promote survival and decrease cellular pathways that lead to cell death. The review comprehensively covers more than two decades worth of studies ranging from preclinical (mice, swine) to recent human clinical trials of the use of VPA in HS and TBI. Furthermore, it details the different mechanisms in which VPA alters gene expression, induces cytoprotective changes, attenuates platelet dysfunction, provides neuroprotection, and enhances survival in HS and TBI. Valproic acid shows real promise as a therapy that can induce the prosurvival phenotype in those injured during military conflict.

Hypotheses about sub-optimal hydration in the weeks before coronavirus disease (COVID-19) as a risk factor for dying from COVID-19

To address urgent need for strategies to limit mortality from coronavirus disease 2019 (COVID-19), this review describes experimental, clinical and epidemiological evidence that suggests that chronic sub-optimal hydration in the weeks before infection might increase risk of COVID-19 mortality in multiple ways. Sub-optimal hydration is associated with key risk factors for COVID-19 mortality, including older age, male sex, race-ethnicity and chronic disease. Chronic hypertonicity, total body water deficit and/or hypovolemia cause multiple intracellular and/or physiologic adaptations that preferentially retain body water and favor positive total body water balance when challenged by infection. Via effects on serum/glucocorticoid-regulated kinase 1 (SGK1) signaling, aldosterone, tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), aquaporin 5 (AQP5) and/or Na⁺/K⁺-ATPase, chronic sub-optimal hydration in the weeks before exposure to COVID-19 may conceivably result in: greater abundance of angiotensin converting enzyme 2 (ACE2) receptors in the lung, which increases likelihood of COVID-19 infection, lung epithelial cells which are pre-set for exaggerated immune response, increased capacity for capillary leakage of fluid into the airway space, and/or reduced capacity for both passive and active transport of fluid out of the airways. The hypothesized hydration effects suggest hypotheses regarding strategies for COVID-19 risk reduction, such as public health recommendations to increase intake of drinking water, hydration screening alongside COVID-19 testing, and treatment tailored to the pre-infection hydration condition. Hydration may link risk factors and pathways in a unified mechanism for COVID-19 mortality. Attention to hydration holds potential to reduce COVID-19 mortality and disparities via at least 5 pathways simultaneously.

Histone Deacetylase Inhibitors: A Novel Strategy in Trauma and Sepsis

Trauma remains a leading cause of morbidity and mortality among all age groups in the United States. Hemorrhagic shock and traumatic brain injury (TBI) are major causes of preventable death in trauma. Initial treatment involves fluid resuscitation to improve the intravascular volume. Although crystalloids may provide volume expansion, they do not have any pro-survival properties. Furthermore, aggressive fluid resuscitation can provoke a severe inflammatory response and worsen clinical outcomes. Due to logistical constraints, however, definitive resuscitation with blood products is often not feasible in the prehospital setting-highlighting the importance of adjunctive therapies. In recent years, histone deacetylase inhibitors (HDACis) have shown promise as pharmacologic agents for use in both trauma and sepsis. In this review, we discuss the role of histone deacetylases (HDACs) and pharmacologic agents that inhibit them (HDACis). We also highlight the therapeutic effects and mechanisms of action of HDACis in hemorrhagic shock, TBI, polytrauma, and sepsis. With further investigation and translation, HDACis have the potential to be a high-impact adjunctive therapy to traditional resuscitation.

Creating a "Prosurvival Phenotype" Through Histone Deacetylase Inhibition: Past, Present, and Future

Traumatic injuries and their sequelae represent a major source of mortality in the United States and globally. Initial treatment for shock, traumatic brain injury, and polytrauma is limited to resuscitation fluids to replace lost volume. To date, there are no treatments with inherent prosurvival properties. Our laboratory has investigated the use of histone deacetylase inhibitors (HDACIs) as pharmacological agents to improve survival. This class of drugs acts through posttranslational protein modifications and is a direct regulator of chromatin structure and function, as well as the function of numerous cytoplasmic proteins. In models of hemorrhagic shock and polytrauma, administration of HDACIs offers a significant survival advantage, even in the absence of fluid resuscitation. Positive results have also been shown in two-hit models of hemorrhage and sepsis and in hemorrhagic shock combined with traumatic brain injury. Accumulating data generated by our group and others continue to support the use of HDACIs for the creation of a prosurvival phenotype. With further research and clinical trials, HDACIs have the potential to be an integral tool in the treatment of trauma, especially in the prehospital phase.

Effects of Ringer's sodium pyruvate solution on serum tumor necrosis factor-α and interleukin-6 upon septic shock

Objective:

To study the effects of Ringer’s sodium pyruvate solution on tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) upon septic shock.

Methods:

Ninety emergency patients with septic shock were divided into a treatment group and a control group by random draw. The control group was resuscitated with 50 ml of compound sodium chloride (Ringer’s solution), and the treatment group was given 50 ml of Ringer’s sodium pyruvate solution. Both groups were basically treated.

Results:

All patients were successfully resuscitated. After treatment, extravascular lung water index, intrathoracic blood volume index, systemic vascular resistance index and cardiac index of the two groups were significantly improved compared with those before treatment (P<0.05). However, there were no significant inter-group differences at different time points (P>0.05). Blood lactic acid level, central venous oxygen saturation index and urine output were also improved after treatment, with significant inter-group differences (P<0.05). Serum TNF-α and IL-6 levels of both groups significantly decreased after treatment (P<0.05), and the levels of the treatment group were significantly lower than those of the control group (P<0.05). During 28 days of follow-up, the mortality rate of the treatment group (4.4%) was significantly lower than that of the control group (20.0%) (P<0.05).

Conclusion:

Patients with septic shock are complicated with disordered expressions of inflammatory factors. During resuscitation, Ringer’s sodium pyruvate solution can effectively promote blood circulation, mitigate inflammation and maintain acid-base equilibrium, thus decreasing the prognostic mortality rate.

Effects of different resuscitation fluids on pulmonary expression of aquaporin1 and aquaporin5 in a rat model of uncontrolled hemorrhagic shock and infection

BACKGROUND

To investigate the effects of fluids resuscitation on pulmonary expression of aquaporin1 and aquaporin5 in a rat model of uncontrolled hemorrhagic shock and infection.

METHODS

Sixty Sprague-Dawley rats were randomly assigned to five groups, sham operation group (Group C) and four treated groups: no fluid resuscitation group (Group NF), groups resuscitated with Lactated Ringer's (LR),7.5% NaCl (HTS) and Hydroxyl ethyl starch (HES) respectively. Three-phased uncontrolled hemorrhagic shock and infection model was used. Phase I: Massive hemorrhage with a mean arterial pressure of 35-40 mmHg for 60 min, and followed by infection of lipopolysaccharide. Then some animals were resuscitated with solutions mentioned above, until 90 min. Phase II: At hemorrhagic shock 90 minutes, phase II of 60 minutes began with hemostasis and returning of all the initial shed blood. Phase III: Observation phase for 3.5 hours. After phase III, arterial blood gas analysis and the survival rates of the rats were recorded, Wet-to-dry lung weight ratio, BALF protein, pulmonary permeability index, and expressions of aquaporin1 and aquaporin5 were tested.

RESULTS

The expressions of aquaporin1 and aquaporin5 were decreased in treatment groups comparing with sham operation group. Group HES and Group HTS decreased pulmonary vascular permeability and Wet-to-dry lung weight ratio, improved arterial blood gas analysis and survival rates, and attenuated the decreased pulmonary expression of aquaporin1 and aquaporin5 after the "two-hit", comparing with groups NF and LR,but these beneficial effects were blunted in group HTS.

CONCLUSION

The expression of aquaporin1 and aquaporin5 may play important roles in formation of pulmonary edema. Resuscitation with HTS and HES, especially HES can reduce lung injury after hemorrhagic shock, partly by up-regulating the expressions of aquaporin1 and aquaporin5.

Permissive hypotension does not reduce regional organ perfusion compared to normotensive resuscitation: animal study with fluorescent microspheres

Introduction

The objective of this study was to investigate regional organ perfusion acutely following uncontrolled hemorrhage in an animal model that simulates a penetrating vascular injury and accounts for prehospital times in urban trauma. We set forth to determine if hypotensive resuscitation (permissive hypotension) would result in equivalent organ perfusion compared to normotensive resuscitation.

Methods

Twenty four (n=24) male rats randomized to 4 groups: Sham, No Fluid (NF), Permissive Hypotension (PH) (60% of baseline mean arterial pressure - MAP), Normotensive Resuscitation (NBP). Uncontrolled hemorrhage caused by a standardised injury to the abdominal aorta; MAP was monitored continuously and lactated Ringer’s was infused. Fluorimeter readings of regional blood flow of the brain, heart, lung, kidney, liver, and bowel were obtained at baseline and 85 minutes after hemorrhage, as well as, cardiac output, lactic acid, and laboratory tests; intra-abdominal blood loss was assessed. Analysis of variance was used for comparison.

Results

Intra-abdominal blood loss was higher in NBP group, as well as, lower hematocrit and hemoglobin levels. No statistical differences in perfusion of any organ between PH and NBP groups. No statistical difference in cardiac output between PH and NBP groups, as well as, in lactic acid levels between PH and NBP. NF group had significantly higher lactic acidosis and had significantly lower organ perfusion.

Conclusions

Hypotensive resuscitation causes less intra-abdominal bleeding than normotensive resuscitation and concurrently maintains equivalent organ perfusion. No fluid resuscitation reduces intra-abdominal bleeding but also significantly reduces organ perfusion.

Transcriptomic response of murine liver to severe injury and hemorrhagic shock: a dual-platform microarray analysis

Trauma-hemorrhagic shock (HS/T) is a complex process that elicits numerous molecular pathways. We hypothesized that a dual-platform microarray analysis of the liver, an organ that integrates immunology and metabolism, would reveal key pathways engaged following HS/T. C57BL/6 mice were divided into five groups (n = 4/group), anesthetized, and surgically treated to simulate a time course and trauma severity model: 1) nonmanipulated animals, 2) minor trauma, 3) 1.5 h of hemorrhagic shock and severe trauma (HS/T), 4) 1.5 h HS/T followed by 1 h resuscitation (HS/T+1.0R), 5) 1.5 h HS/T followed by 4.5 h resuscitation (HS/T+4.5R). Liver RNA was hybridized to CodeLink and Affymetrix mouse whole genome microarray chips. Common genes with a cross-platform correlation >0.6 (2,353 genes in total) were clustered using k-means clustering, and clusters were analyzed using Ingenuity Pathways Analysis. Genes involved in the stress response and immunoregulation were upregulated early and remained upregulated throughout the course of the experiment. Genes involved in cell death and inflammatory pathways were upregulated in a linear fashion with elapsed time and in severe injury compared with minor trauma. Three of the six clusters contained genes involved in metabolic function; these were downregulated with elapsed time. Transcripts involved in amino acid metabolism as well as signaling pathways associated with glucocorticoid receptors, IL-6, IL-10, and the acute phase response were elevated in a severity-dependent manner. This is the first study to examine the postinjury response using dual-platform microarray analysis, revealing responses that may enable novel therapies or diagnostics.

Histone deacetylase inhibitor treatment attenuates MAP kinase pathway activation and pulmonary inflammation following hemorrhagic shock in a rodent model

BACKGROUND

Hemorrhagic shock activates cellular stress signals and can lead to systemic inflammatory response, organ injury, and death. We have previously shown that treatment with histone deacetylase inhibitors (HDACIs) significantly improves survival in lethal models (60% blood loss) of hemorrhage. The aim of the current study was to examine whether these protective effects were due to attenuation of mitogen activated protein kinase (MAPK) signaling pathways, which are known to promote inflammation and apoptosis.

METHODS

Wistar-Kyoto rats (250-300 g) were subjected to 40% blood loss and randomized to treatment with: (1) HDACI valproic acid (VPA 300 mg/kg i.v.; volume = 0.75 mL/kg), or (2) vehicle control (0.75 mL/kg of 0.9% saline). Animals were sacrificed at 1, 4, and 20 h (n = 3-4/group/timepoint), and lung samples were analyzed by Western blotting for expression of active (phosphorylated) and inactive forms of c-Jun N-terminal Kinase (JNK) and p38 MAPK. Myeloperoxidase (MPO) activity was measured in lung tissue 20 h after hemorrhage as a marker of neutrophil infiltration. Normal animals (n = 3) served as shams.

RESULTS

Hemorrhaged animals demonstrated significant increases in phosphorylated p38 at 1 h, phosphorylated JNK at 4 h, and increased MPO activity at 20 h (P < 0.05 compared with sham). VPA treatment significantly (P < 0.05) attenuated all of these changes.

CONCLUSIONS

Hemorrhagic shock activates pro-inflammatory MAPK signaling pathways and promotes pulmonary neutrophil infiltration, affects that are significantly attenuated by VPA treatment. This may represent a key mechanism through which HDACIs decrease organ damage and promote survival in hemorrhagic shock.

Pharmacologic resuscitation promotes survival and attenuates hemorrhage-induced activation of extracellular signal-regulated kinase 1/2

BACKGROUND

Hemorrhage is the leading cause of preventable trauma-related deaths, and histone deacetylase inhibitors (HDACI) such as valproic acid (VPA) can improve survival following lethal hemorrhage. HDACI acetylate proteins, and acetylation regulates many cellular functions. Here we have investigated the effects of VPA treatment on extracellular signal-regulated kinase 1/2 (ERK) activation, as ERK is well known to modulate cell death, gene expression, and inflammation.

MATERIALS AND METHODS

Anesthetized Wistar-Kyoto rats were subjected to lethal (60%) blood loss, and then randomized (n = 5-6/group) to (1) VPA 300 mg/kg or (2) vehicle control. Survival was monitored for 24 h. A separate group of rats were subjected to sublethal (40%) hemorrhage and were treated with VPA or vehicle. Rats were sacrificed at 1, 4, and 20 h, and lung tissue was assessed for the degree of acetylation of histone 3, and activation (phosphorylation) of ERK. Sham animals served as normal controls.

RESULTS

Sixty percent hemorrhage resulted in severe shock. Only 17% of the vehicle-treated animals survived (most died within 1 h), whereas 80% of the VPA-treated animals survived (P < 0.05). Hemorrhage resulted in a significant increase in phosphorylated ERK (activated form) compared with sham at the 1 and 4 h time points, but not at the 20 h time point. VPA treatment significantly attenuated these changes, while increasing histone protein acetylation.

CONCLUSIONS

VPA treatment significantly improves survival following lethal hemorrhagic shock. Hemorrhage induces ERK activation, which is significantly attenuated by VPA treatment. This may represent one mechanism through which VPA promotes survival in otherwise lethal hemorrhagic shock.

SelSA, selenium analogs of SAHA as potent histone deacetylase inhibitors

Cancer treatment and therapy has moved from conventional chemotherapeutics to more mechanism-based targeted approach. Disturbances in the balance of histone acetyltransferase (HAT) and deacetylase (HDAC) leads to a change in cell morphology, cell cycle, differentiation, and carcinogenesis. In particular, HDAC plays an important role in carcinogenesis and therefore it has been a target for cancer therapy. Structurally diverse group of HDAC inhibitors are known. The broadest class of HDAC inhibitor belongs to hydroxamic acid derivatives that have been shown to inhibit both class I and II HDACs. Suberoylanilide hydroxamic acid (SAHA) and Trichostatin A (TSA), which chelate the zinc ions, fall into this group. In particular, SAHA, second generation HDAC inhibitor, is in several cancer clinical trials including solid tumors and hematological malignancy, advanced refractory leukemia, metastatic head and neck cancers, and advanced cancers. To our knowledge, selenium-containing HDAC inhibitors are not reported in the literature. In order to find novel HDAC inhibitors, two selenium based-compounds modeled after SAHA were synthesized. We have compared two selenium-containing compounds; namely, SelSA-1 and SelSA-2 for their inhibitory HDAC activities against SAHA. Both, SelSA-1 and SelSA-2 were potent HDAC inhibitors; SelSA-2 having IC50 values of 8.9 nM whereas SAHA showed HDAC IC(50) values of 196 nM. These results provided novel selenium-containing potent HDAC inhibitors.

Fluid resuscitation: past, present, and the future

Hemorrhage remains a major cause of preventable death following both civilian and military trauma. The goals of resuscitation in the face of hemorrhagic shock are restoring end-organ perfusion and maintaining tissue oxygenation while attempting definitive control of bleeding. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. This article reviews the historical development and scientific underpinnings of modern resuscitation techniques. We summarized data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids, including isotonic crystalloids, natural and artificial colloids, hypertonic and hyperoncotic solutions, and artificial oxygen carriers, on cellular injury and how these relate to clinical practice. The data reveal that a uniformly safe, effective, and practical resuscitation fluid when blood products are unavailable and direct hemorrhage control is delayed has been elusive. Yet, it is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. Thus, we describe how some novel resuscitation strategies aimed at preventing or ameliorating cellular injury may become clinically available in the future.

Hypoxic "second hit" in leukocytes from trauma patients: Modulation of the immune response by histone deacetylase inhibition

INTRODUCTION

Histone deacetylase inhibitors (HDACI), can improve survival after lethal hemorrhagic shock, and modulate the inflammatory response after hemorrhage/lipopolysaccharide (LPS). The current experiments were designed to study the effects of HDACI after hemorrhage and severe hypoxia.

METHODS

Splenic leukocytes from trauma and non-trauma patients (n=4-5/group) were exposed to severe hypoxia with/without suberoylanilide hydroxamic acid (SAHA, 400 nM) for 8h. Cytokines were measured by ELISA and RT-PCR, and hypoxia inducible factor (HIF)-1a and heme oxygenase (HO)-1 by Western blot.

RESULTS

After hemorrhage and hypoxia, SAHA increased IL-1b gene (4.7+/-1.2-fold) and protein expression (2.1+/-0.6-fold) in trauma splenic leukocytes. It also reduced IL-10 gene expression (0.6+/-0.2-fold), but did not alter TNFa or IL-6 levels. This unexpected pro-inflammatory response may be due to a decrease in HIF-1a and HO-1 protein levels.

CONCLUSIONS

In this model of severe hypoxia, treatment with SAHA increased the inflammatory response in trauma leukocytes, possibly through inhibition of the HIF-1/HO-1 pathway. Splenic leukocytes from non-trauma patients were variably affected by SAHA. Taken in context with the known anti-inflammatory properties of HDACI after hemorrhage/LPS, these findings suggest that the immune-modulating functions of HDACI are dependent on the type and severity of both the priming injury and subsequent insult.

Early organ-specific endothelial activation during hemorrhagic shock and resuscitation

Multiple organ dysfunction syndrome (MODS) is a complication of hemorrhagic shock (HS) and related to high morbidity and mortality. Interaction of activated neutrophils and endothelial cells is considered to play a prominent role in the pathophysiology of MODS. Insight in the nature and molecular basis of endothelial cell activation during HS can assist in identifying new rational targets for early therapeutic intervention. In this study, we examined the kinetics and organ specificity of endothelial cell activation in a mouse model of HS. Anesthetized male mice were subjected to controlled hemorrhage to a MAP of 30 mmHg. Mice were killed after 15, 30, 60, or 90 min of HS. After 90 min of hemorrhagic shock, a group of mice was resuscitated with 6% hydroxyethyl starch 130/0.4. Untreated mice and sham shock mice that underwent instrumentation and 90 min of anesthesia without shock served as controls. Gene expression levels of inflammatory endothelial cell activation (P-selectin, E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1) and hypoxia-responsive genes (vascular endothelial growth factor and hypoxia-inducible factor 1alpha) were quantified in kidney, liver, lung, brain, and heart tissue by quantitative reverse-transcription-polymerase chain reaction. Furthermore, we examined a selection of these genes with regard to protein expression and localization using immunohistochemical analysis. Induction of inflammatory genes occurred early during HS and already before resuscitation. Expression of adhesion molecules was significantly induced in all organs, albeit to a different extent depending on the organ. Endothelial genes CD31 and VE-cadherin, which function in endothelial cell homeostasis and integrity, were not affected during the shock phase except for VE-cadherin in the liver, which showed increased mRNA levels. The rapid inflammatory activation was not paralleled by induction of hypoxia-responsive genes. This study demonstrated the occurrence of early and organ-specific endothelial cell activation during hemorrhagic shock, as presented by induced expression of inflammatory genes. This implies that early therapeutic intervention at the microvascular level may be a rational strategy to attenuate MODS.

Surviving blood loss without fluid resuscitation

BACKGROUND

Patients with massive blood loss often die before delivery of definitive care, especially in austere environments. Strategies that can maintain life during evacuation and transport to higher levels of care may be lifesaving. We have previously shown that administration of histone deacetylase inhibitors (HDACI) enhance gene transcription through specific modifications of DNA-associated histone proteins. Furthermore, it protects against organ damage when given before hemorrhage. The current experiment was done to test whether administration of HDACI after lethal hemorrhage, without fluid resuscitation, would improve outcome by creating a pro-survival phenotype.

METHODS

Seventy-two male Wistar-Kyoto rats (n = 12 per group) were subjected to 60% blood volume loss for 1 hour (40% arterial bleed for 10 minutes and 20% venous bleed for 50 minutes). After hemorrhage, animals were randomized to receive one of two HDACI: (1) valproic acid (VPA, 300 mg/kg in 0.25 mL saline), or (2) suberoyanilide hydroxamic acid (SAHA, 7.5 mg/kg in 0.25 mL saline). Control groups included (3) no hemorrhage (Sham), (4) no resuscitation (NR), (5) 0.9% saline resuscitation, 3 times the volume of shed blood (NS), and (6) vehicle control, 0.25 mL 0.9% saline (VEH). Hemodynamic data were recorded continuously, and physiologic parameters were measured serially. Survival for 3 hours was the primary endpoint for this experiment.

RESULTS

Nonresuscitated shock (NR group) was highly lethal and only 25% of the animals survived for 3 hours. Administration of HDACI after hemorrhage (without fluid resuscitation) significantly improved survival (75% and 83% in VPA and SAHA groups, respectively, p < 0.05 vs. NR). Survival was 40%, 100%, and 100% in the VEH, Sham, and NS resuscitation groups, respectively.

CONCLUSIONS

This study demonstrates that post-shock administration of HDACI can significantly improve early survival in a highly lethal model of hemorrhagic shock, even in the absence of conventional fluid resuscitation. This approach may be especially relevant for austere environments where fluids are in limited supply, such as a battlefield.

Impact of resuscitation strategies on the acetylation status of cardiac histones in a swine model of hemorrhage

BACKGROUND

Chromatin remodeling through histone acetylation is a key control mechanism in gene transcription. We have shown previously that fluid resuscitation in rodents is coupled with highly structured post-translational modifications of cardiac histones. The current experiment was performed to validate this concept in a clinically relevant large animal model of hemorrhage and resuscitation, and to correlate the changes in histone acetylation with altered expression of immediate-early response genes.

STUDY DESIGN

Yorkshire swine (n=49, 7/group, weight=40-58kg) were subjected to combined uncontrolled and controlled hemorrhage (40% of estimated blood volume) and randomly assigned to the following resuscitation groups: (1) 0.9% saline (NS), (2) racemic lactated Ringer's (dl-LR), (3) l-isomer lactated Ringer's (l-LR), (4) Ketone Ringer's (KR), (5) 6% hetastarch in saline (Hespan). KR contained an equimolar substitution of lactate with beta-hydroxybutyrate. No hemorrhage (NH) and no resuscitation (NR) groups were included as controls. Cardiac protein was used in Western blotting to analyze total protein acetylation and histone acetylation specifically. Lysine residue-specific acetylation of histone subunits H3 and H4 was further evaluated. In addition, Chromatin Immunoprecipitation (ChIP) technique was used to separate the DNA bound to acetylated histones (H3 and H4 subunits), followed by measurement of genes that are altered by hemorrhage/resuscitation, including immediate-early response genes (c-fos and c-myc), and heat shock protein (HSP) 70.

RESULTS

The type of fluid used for resuscitation influenced the patterns of cardiac histone acetylation. Resuscitation with dl-LR and KR induced hyperacetylation on H3K9. KR resuscitation was also associated with increased acetylation on H3K14 and H4K5, and hypoacetylation on H3K18. The expression of genes was also fluid specific, with the largest number of changes following KR resuscitation (increased c-fos and c-myc, HSP 70 linked with H3; and increased c-myc linked with H4). Among the histone subunits studied, altered H3 acetylations were associated with the majority of changes in immediate-early gene expression.

CONCLUSIONS

Acetylation status of cardiac histones, affected by hemorrhage, is further modulated by resuscitation producing a fluid-specific code that is preserved in different species. Resuscitation with KR causes histone acetylation at the largest number of lysine sites (predominately H3 subunit), and has the most pronounced impact on the transcriptional regulation of selected (immediate-early response) genes.

Histone deacetylase as therapeutic target in a rodent model of hemorrhagic shock: effect of different resuscitation strategies on lung and liver

BACKGROUND

DNA transcription is regulated in part by acetylation of nuclear histones, controlled by 2 groups of enzymes: histone deacetylases (HDAC) and histone acetyl transferases (HAT). We have shown previously that hemorrhage and resuscitation are associated with HDAC/HAT imbalance, which influences the acetylation status of cardiac histones. The goals of this study were to determine whether: (1) resuscitation after hemorrhage affects histone acetylation in a fluid- and organ-specific fashion; and (2) administration of HDAC inhibitors influences histone acetylation and subsequent gene expression.

METHODS

In the first experiment, rats (n = 6/group) were subjected to volume-controlled hemorrhage and resuscitated with: (1) racemic lactated Ringer's (DL-LR); (2) L-lactated Ringer's (L-LR); (3) 7.5% hypertonic saline (HTS); (4) ketone Ringer's (KR); or (5) pyruvate Ringer's (PR). Control groups included: (6) no hemorrhage (Sham); and (7) hemorrhage with no resuscitation (NR). In the second experiment (n = 5/group), 3 HDAC inhibitors, valproic acid (VPA), trichostatin A (TSA), and suberoylanilide hydroxamic acid (SAHA), were added to normal saline and used as fluid for resuscitation. At the end of resuscitation, lung and liver tissues were subjected to subcellular protein fractionation and Western blotting to analyze histone acetylation. In addition, cDNA microarrays and RT-PCR were used to measure expression of selected genes.

RESULTS

Hemorrhage did not change the level of histone acetylation in lungs, whereas resuscitation predominantly hyperacetylated histones. An analysis of histone acetylation on 10 lysine sites showed that L-LR, HTS, and KR resuscitation caused the largest number of changes (7, 6, and 6 respectively). SAHA hyperacetylated 7 sites in liver and affected expression of 57 genes (44 up, 13 down).

CONCLUSIONS

Resuscitation with various fluids, as well as infusion of pharmacologic HDAC inhibitors affects histone acetylation in a fluid- and organ-specific fashion, even when administered post-insult for a limited period of time. Uniquely affected genes are associated with metabolism, cellular growth, proliferation, differentiation, transformation, and cellular signaling.

Differential effect of resuscitation on Toll-like receptors in a model of hemorrhagic shock without a septic challenge

It has been shown that the inflammatory response and cellular damage after hemorrhagic shock are influenced by resuscitation strategies. Toll-like receptors (TLRs) play an important role in signal transduction in inflammatory conditions. However, alterations in TLR expression following hemorrhagic shock and resuscitation have not been well documented. This study was conducted to measure the impact of different resuscitation strategies on TLR expression and downstream signaling in key organs.

METHODS

Sprague Dawley rats (n=38) were subjected to a severe volume-controlled hemorrhage protocol. After 75 min of shock, they were resuscitated over 45 min as follows: (1) lactated Ringer's (LR, 81 ml/kg), (2) ketone Ringer's (KR, 81 ml/kg), (3) 7.5% hypertonic saline (HTS, 9.7 ml/kg), (4) 6% hetastarch (HEX, 27 ml/kg), (5) pyruvate Ringer's (PR, 81 ml/kg). Sham hemorrhage (NH) and no resuscitation (NR) groups served as controls. The KR and PR solutions were identical to LR except for equimolar substitution of racemic lactate with beta hydroxybutyrate and sodium pyruvate, respectively. At the end of resuscitation, the expression of TLRs (types 1-10), and cytokines (IL-10, IL-1beta and TNF-alpha) were measured in the lung and spleen using RT-PCR. Levels of phosphorylated and total IkB-alpha and NF-kappaB were detected by Western blotting. The systemic and lung protein levels of TNF-alpha were measured using ELISA and immunohistochemistry.

RESULTS

Expression of TLRs in the lung was affected more than in the spleen by hemorrhagic shock and resuscitation. In the lung, hemorrhage increased TLR-2, -3 and -6 (but not TLR-4) mRNA expression, with an up-regulation of the ratio of phosphor-NF-kappaBp65 and total NF-kappaBp65, NF-kappaBp65 activation, and enhanced systemic and tissue TNF-alpha protein levels. Post-resuscitation, TLR mRNA profile and subsequent downstream proteins in the lung and spleen were affected by the choice of resuscitation strategy.

CONCLUSIONS

Hemorrhagic shock activates TLR signaling in lung, but not the spleen, probably through an up-regulation of TLR gene expression, and activation of NF-kappaB pathway. Resuscitation modulates this response in a fluid- and tissue-specific fashion.

New developments in fluid resuscitation

Hemorrhagic shock is the leading cause of death in civilian and military trauma. Effective hemorrhage control and optimal resuscitation are the main goals in the management of severely injured patients. This article addresses the changing trends in fluid resuscitation in regards to who, when, and how. Much of these changing trends are caused by the recognition that the current method of resuscitation with crystalloid fluids may not be optimal and may even have detrimental consequences. This article summarizes a number of studies that have evaluated the cellular toxicities of commonly used resuscitation fluids, to highlight the need for the development of new fluids.

An update on fluid resuscitation

Hemorrhagic shock is the leading cause of death in civilian and military trauma. Effective hemorrhage control and better resuscitation strategies have the potential of saving lives. However, if not performed properly, resuscitation can actually exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation plays an important role in this injury pattern. It is logical to prevent this cellular injury through wiser resuscitation strategies than attempting immunomodulation after the damage has already occurred. It is important to recognize that unlike numerous other variables, resuscitation is completely under our control. We decide who, when and how should get resuscitated. This paper summarizes data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids on cellular injury, and how these relate to clinical practice. In addition, some novel resuscitation strategies are described that may become clinically available in the near future.