Creating a pro-survival and anti-inflammatory phenotype by modulation of acetylation in models of hemorrhagic and septic shock

Protective effect of HDACIs in improves survival and organ injury after CLP-induced sepsis

Introduction

The effects of isoform-specific histone deacetylase inhibitors (HDACIs) and the non-selective HDACI on sepsis have been profoundly reported. However, the best HDAC classes have not been fully evaluated. Therefore, this study aimed to determine which HDACIs are responsible for survival and beneficial for organ injury.

Methods

Experiment I, SD rats were subjected to cecal ligation and puncture and randomly assigned to the no treatment, dimethyl sulfoxide (DMSO) only, MS-275, LMK-235, tubastatinA (TubA), trichostatin-A (TSA), and sirtinol groups (n = 5). Survival was monitored for 48 h. Experiment II, the animals were monitored for 12 h, then, blood and tissues sample were collected. Interleukin (IL)-6, IL-1β, tumour necrosis factor (TNF)-α, alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) expressions were evaluated using ELISA. Liver, heart and lung tissues were analysed via hematoxylin and eosin staining. Liver and heart tissue lysates were analysed for acetylated histones H3, H4, a-tubulin and nuclear factor kappa B (NF-κB), IL-6, IL-1β, and TNF-α using western blotting. Splenocytes were examined via flow cytometry to analyse the immune cell population.

Results

MS-275, TubA and TSA treatments significantly prolonged survival. MS-275, LMK-235, TubA and TSA significantly reduced the histopathological scores and AST, ALT, CK, LDH, IL-6, IL-1β and TNF-α levels, significantly increased acetylated of NF-κB and changed the immune cell proportion.

Conclusion

Our results indicated that HDACI classes I and IIb and non-selective HDACI can significantly prolong survival. Moreover, non-selective and isoform-specific class I and IIa/IIb HDACIs can attenuate inflammation and organ injury.

Modified Suberoylanilide Hydroxamic Acid Reduced Drug-Associated Immune Cell Death and Organ Damage under Lipopolysaccharide Inflammatory Challenge

Histone deacetylase inhibitors (HDACi) induce potent anti-inflammatory responses when used to treat inflammatory diseases. Suberoylanilide hydroxamic acid (SAHA), a pan-HDACi, decreases pro-inflammatory cytokine levels and attenuates cytokine storm in sepsis; however, its toxicity profile toward immune cells has limited its use as a sepsis therapeutic. Here, we developed a modification to SAHA by para-hydroxymethylating the capping group to generate SAHA-OH. We discovered that SAHA-OH provides a favorable improvement to the toxicity profile compared to SAHA. SAHA-OH significantly reduced primary macrophage apoptosis and splenic B cell death as well as mitigated organ damage using a lipopolysaccharide (LPS)-induced endotoxemia mouse model. Furthermore, SAHA-OH retained anti-inflammatory responses similar to SAHA as measured by reductions in LPS-induced proinflammatory cytokine secretions in vitro and in vivo. These effects were attributed to a decreased selectivity of HDAC1, 2, 3, 8 and an increased selectivity for HDAC6 for SAHA-OH as determined by IC50 values. Our results support the potential for SAHA-OH to modulate acute proinflammatory responses while mitigating SAHA-associated drug toxicity for use in the treatment of inflammation-associated diseases and conditions.

Acute Respiratory Distress Syndrome (ARDS) after trauma: Improving incidence, but increasing mortality

PURPOSE

Acute Respiratory Distress Syndrome (ARDS) is an infrequent, yet morbid inflammatory complication in injury victims. With the current project we sought to estimate trends in incidence, determine outcomes, and identify risk factors for ARDS and related mortality.

MATERIALS & METHODS

The national Trauma Quality Improvement Program dataset (2010-2014) was queried. Demographics, injury characteristics and outcomes were compared between patients who developed ARDS and those who did not. Logistic regression models were fitted for the development of ARDS and mortality respectively, adjusting for relevant confounders.

RESULTS

In the studied 808,195 TQIP patients, incidence of ARDS decreased over the study years (3-1.1%, p < 0.001), but related mortality increased (18.-21%, p = 0.001). ARDS patients spent an additional 14.7 ± 10.3 days in the hospital, 9.7 ± 7.9 in the ICU, and 6.6 ± 9.4 on mechanical ventilation (all p < 0.001). Older age, male gender, African American race increased risk for ARDS. Age, male gender, lower GCS and higher ISS also increased mortality risk among ARDS patients. Several pre-existing comorbidities including chronic alcohol use, diabetes, smoking, and respiratory disease also increased risk.

CONCLUSION

Although the incidence of ARDS after trauma appears to be declining, mortality is on the rise.

Propolis from southeastern Brazil produced by Apis mellifera affects innate immunity by modulating cell marker expression, cytokine production and intracellular pathways in human monocytes

OBJECTIVES

Propolis is a bee-made product used for centuries due to its diverse biological properties, including its immunomodulatory action. This work aimed at investigating whether propolis may affect monocyte functions challenged with retinoic acid (RA), B subunit of Escherichia coli heat-labile enterotoxin (EtxB), human melanoma-associated antigen-1 (MAGE-1) and lipopolysaccharide (LPS).

METHODS

Monocytes from healthy donors were treated with the stimuli separately or in the presence of propolis. Cell viability was evaluated by MTT assay, cell marker expression was assessed by flow cytometry, cytokine production by ELISA, gene expression by RT-qPCR.

KEY FINDINGS

Propolis alone maintained TLR-2, TLR-4, HLA-DR, CD40 and CD80 expression in the monocytes; however, its combination with either MAGE-1 or LPS decreased CD40 expression triggered by the stimuli. Propolis maintained RA action on cell marker expression. Propolis inhibited TNF-α (with either EtxB or MAGE-1) and IL-6 (with either RA or MAGE-1), and increased IL-10 (with MAGE-1) production. Propolis downmodulated LC3 expression induced by LPS. It also induced a lower NF-kB expression than control cells and its combination with RA induced a higher expression than the stimulus alone.

CONCLUSIONS

Propolis potentially affected innate immunity by downmodulating the monocytes pro-inflammatory activity.

Targeting Histone Deacetylases to Modulate Graft-Versus-Host Disease and Graft-Versus-Leukemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the main therapeutic strategy for patients with both malignant and nonmalignant disorders. The therapeutic benefits of allo-HSCT in malignant disorders are primarily derived from the graft-versus-leukemia (GvL) effect, in which T cells in the donor graft recognize and eradicate residual malignant cells. However, the same donor T cells can also recognize normal host tissues as foreign, leading to the development of graft-versus-host disease (GvHD), which is difficult to separate from GvL and is the most frequent and serious complication following allo-HSCT. Inhibition of donor T cell toxicity helps in reducing GvHD but also restricts GvL activity. Therefore, developing a novel therapeutic strategy that selectively suppresses GvHD without affecting GvL is essential. Recent studies have shown that inhibition of histone deacetylases (HDACs) not only inhibits the growth of tumor cells but also regulates the cytotoxic activity of T cells. Here, we compile the known therapeutic potential of HDAC inhibitors in preventing several stages of GvHD pathogenesis. Furthermore, we will also review the current clinical features of HDAC inhibitors in preventing and treating GvHD as well as maintaining GvL.

Epigenetic biomarkers for human sepsis and septic shock: insights from immunosuppression

Sepsis is a life-threatening condition that occurs when the body responds to an infection damaging its own tissues. Sepsis survivors sometimes suffer from immunosuppression increasing the risk of death. To our best knowledge, there is no 'gold standard' for defining immunosuppression except for a composite clinical end point. As the immune system is exposed to epigenetic changes during and after sepsis, research that focuses on identifying new biomarkers to detect septic patients with immunoparalysis could offer new epigenetic-based strategies to predict short- and long-term pathological events related to this life-threatening state. This review describes the most relevant epigenetic mechanisms underlying alterations in the innate and adaptive immune responses described in sepsis and septic shock, and their consequences for immunosuppression states, providing several candidates to become epigenetic biomarkers that could improve sepsis management and help predict immunosuppression in postseptic patients.

Tubastatin A prevents hemorrhage-induced endothelial barrier dysfunction

BACKGROUND

Microvascular hyperpermeability resulting from endothelial barrier dysfunction (EBD) is associated with worse clinical outcomes in trauma-induced hemorrhagic shock. We have previously shown that treatment with Tubastatin A (TubA), a histone deacetylase 6 inhibitor, improves outcomes in animal models of shock. In this study, we investigate whether TubA treatment may prevent trauma-related EBD.

METHODS

Wistar-Kyoto rats subjected to 40% hemorrhage were treated with TubA or vehicle control. Acute lung injury (ALI) was assessed histologically from tissues harvested 6 hours posthemorrhage. In vitro, human umbilical vein endothelial cells (HUVECs) were cultured in EGM BulletKit medium. Medium was exchanged for glucose-free Dulbecco's Modified Eagle Medium (0.5% fetal bovine serum) with or without TubA, and cells were placed in an anoxic chamber (5% CO2, 95% N2, 20-48 hours). Expression of acetylated tubulin and hypoxia-inducible factor 1α was measured by Western blot. Soluble Intercellular Adhesion Molecule-1 concentration within the medium, a marker of endothelial integrity, was determined using enzyme-linked immunosorbent assay. Monolayers were assessed for permeability via transwell assays using fluorescein isothiocyanate-labeled albumin.

RESULTS

Rats treated with TubA had significantly reduced ALI relative to vehicle control. In vitro, TubA significantly attenuated anoxia-induced hyperpermeability, hypoxia-inducible factor 1α expression, and glycocalyx shedding.

CONCLUSIONS

Our findings demonstrate that TubA prevents hemorrhage-induced ALI in rats. Additionally, we have shown that TubA prevents anoxia-induced EBD in vitro. Taken together, these results suggest that TubA could attenuate microvascular hyperpermeability related to hemorrhagic shock.

Rapid valproic acid-induced modulation of the traumatic proteome in a porcine model of traumatic brain injury and hemorrhagic shock

BACKGROUND

Histone deacetylase inhibitors such as valproic acid (VPA) improve survival in lethal models of hemorrhagic shock and polytrauma. Although VPA is known to modulate transcription, its ability to reduce mortality within minutes of administration suggests involvement of a rapid, posttranslational mechanism. We hypothesized that VPA treatment would cause proteomic changes within minutes of treatment including quantitative and/or posttranslational differences in structural and/or effector proteins.

MATERIALS AND METHODS

We used a porcine model of traumatic brain injury (computer-controlled cortical impact, 12 mm depth) and hemorrhagic shock (40% hemorrhage). Animals were kept in shock for 2 h and randomized to two groups (n = 3): normal saline (volume = 3:1 hemorrhage volume) or normal saline + VPA (150 mg/kg, single dose). Peripheral blood mononuclear cells were collected at baseline, postshock, and postresuscitation. Intracellular protein profiles were assessed using 1 dimensional gel electrophoresis, liquid chromatography, mass spectrometry, and analyzed with Ingenuity Pathway Analysis software.

RESULTS

Animals treated with VPA demonstrated significant proteomic changes. Quantitative differences were found in over 200 proteins including effector, regulatory, and structural proteins in critical cell signaling pathways. Posttranslational modification analysis demonstrated differential VPA-induced acetylation of lysine residues in histone and nonhistone proteins. Pathway analysis correlated these changes with significant increases in numerous prosurvival and cytoskeletal intracellular pathways, including Rho GTPase signaling (P = 1.66E-11), integrin signaling (P = 4.19E-21), and a decrease in Rho guanosine nucleotide dissociation inhibitor signaling (P = 4.83E-12).

CONCLUSIONS

In a porcine model of severe injuries, a single dose of VPA is associated with protective changes in the proteome that are measurable within minutes of treatment.

Trauma care: Finding a better way

In a Perspective, Hasan Alam discusses emerging treatment approaches in trauma care.

HDACi Valproic Acid (VPA) and Suberoylanilide Hydroxamic Acid (SAHA) Delay but Fail to Protect against Warm Hepatic Ischemia-Reperfusion Injury

BACKGROUND

Histone deacetylases (HDAC) catalyze N-terminal deacetylation of lysine-residues on histones and multiple nuclear and cytoplasmic proteins. In various animal models, such as trauma/hemorrhagic shock, ischemic stroke or myocardial infarction, HDAC inhibitor (HDACi) application is cyto- and organoprotective and promotes survival. HDACi reduce stress signaling, cell death and inflammation. Hepatic ischemia-reperfusion (I/R) injury during major liver resection or transplantation increases morbidity and mortality. Assuming protective properties, the aim of this study was to investigate the effect of the HDACi VPA and SAHA on warm hepatic I/R.

MATERIAL AND METHODS

Male Wistar-Kyoto rats (age: 6-8 weeks) were randomized to VPA, SAHA, vehicle control (pre-) treatment or sham-groups and underwent partial no-flow liver ischemia for 90 minutes with subsequent reperfusion for 6, 12, 24 and 60 hours. Injury and regeneration was quantified by serum AST and ALT levels, by macroscopic aspect and (immuno-) histology. HDACi treatment efficiency, impact on MAPK/SAPK-activation and Hippo-YAP signaling was determined by Western blot.

RESULTS

Treatment with HDACi significantly enhanced hyperacetylation of Histone H3-K9 during I/R, indicative of adequate treatment efficiency. Liver injury, as measured by macroscopic aspect, serum transaminases and histology, was delayed, but not alleviated in VPA and SAHA treated animals. Importantly, tissue destruction was significantly more pronounced with VPA. SAPK-activation (p38 and JNK) was reduced by VPA and SAHA in the early (6h) reperfusion phase, but augmented later on (JNK, 24h). Regeneration appeared enhanced in SAHA and VPA treated animals and was dependent on Hippo-YAP signaling.

CONCLUSIONS

VPA and SAHA delay warm hepatic I/R injury at least in part through modulation of SAPK-activation. However, these HDACi fail to exert organoprotective effects, in this setting. For VPA, belated damage is even aggravated.

Increased Acetylation of Histone H4 at Lysine 12 (H4K12) in Monocytes of Transgenic Alzheimer's Mice and in Human Patients

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by amyloid-β (Aβ) plaque formation, tau pathology, neurodegeneration and inflammatory processes. Monocytes are involved in inflammation in AD and are recruited to the diseased brain. Recently it has been shown that aberrant epigenetic processes including acetylation are associated with the development of AD. The aim of the present study was to examine acetylation of histone H4 at lysine 12 (H4K12) in monocytes in two transgenic AD mouse models (the triple transgenic 3xTg and a model overexpressing amyloid-precursor protein APP with the Swedish-Dutch-Iowa mutations), and to compare with monocytes isolated from human patients with mild cognitive impairment (MCI) and AD.

METHODS

Mouse and human monocytes were selectively isolated with a positive (PluriSelect) respectively with a negative selection method (Miltenyi). Histones were extracted and acetylation of H4K12 was analyzed by a quantification fluorometric kit. Moreover, monocyte cytokine release was measured and cell death analyzed by FACS using incorporation of 7-AAD.

RESULTS

Our data show a significant increase of monocytic H4K12 acetylation in both transgenic AD mouse models early during development of the plaque deposition in the brain. In line with these data we found significantly elevated acetylation of H4K12 in human patients with MCI but not in patients with AD. Further we observed that the monocytes of AD mice and of AD patients were significantly more vulnerable to cell damage (as seen by 7-AAD incorporation in FACS analysis) and displayed an enhanced release of pro-inflammatory cytokines (MIP2 and TNFα).

CONCLUSION

Our findings indicate that epigenetic changes in peripheral monocytes are an early event in AD-pathology. Thus H4K12 acetylation may be considered as a novel biomarker for early changes in AD development.

Trichostatin A protects against intestinal injury in rats with acute liver failure

BACKGROUND

Histone deacetylase (HDAC) inhibitors have been widely applied in the clinic as anticancer drugs against multiple neoplasms and proved their anti-inflammation under different pathology recently. Trichostatin A (TSA) is an HDAC inhibitor specific in class I and II HDAC enzymes. The aim of the present study was to elucidate the protective effects of TSA on acute liver failure (ALF) in rats and its potential mechanism.

METHODS

A total of 18 female Sprague-Dawley rats were separated into control, model, and TSA groups. We used Western blotting to determine the expression of HDACs, inflammatory cytokines, and acetylation of histone in liver and small intestine. The gene expression of inflammatory factors and Cox-2 was detected by a polymerase chain reaction. Colonic motility was assessed by spatiotemporal mapping. Histologic analysis and immunohistochemistry were performed. Intestinal permeability examination and levels of alanine aminotransferase, aspartate aminotransferase, and total bilirubin were also observed.

RESULTS

ALF procedure caused harm to histology of liver and small intestine, increased the intestinal permeability and serum levels of alanine aminotransferase, aspartate aminotransferase, and total bilirubin. It also interrupted the normal organization of colonic motor patterns by hurting enteric nervous system and pacemaker cells. Along with the decrease of inflammatory factors in ALF rats by TSA administration, all the damage to the liver, the small intestine, and the colon was repaired.

CONCLUSIONS

TSA alleviates the lesion in liver, as well as in small intestine and colon in ALF rats by directly inhibiting inflammatory response.

Selective inhibition of histone deacetylase 6 promotes survival in a rat model of hemorrhagic shock

BACKGROUND

Hemorrhage is the leading cause of preventable trauma-related deaths. We have previously shown that treatment with Tubastatin A (Tub A), a histone deacetylase 6 (HDAC6) inhibitor, can improve survival in a rodent model of septic shock. The aims of the present study were to determine whether selective inhibition of HDAC6 can promote survival in a model of hemorrhagic shock (HS).

METHODS

In Experiment I (survival study), Wistar-Kyoto rats were subjected to HS (55% volume blood loss), followed by intraperitoneal injection of either Tub A (70 mg/kg) dissolved in dimethyl sulfoxide (DMSO) or DMSO only (vehicle group) (n = 8 per group). Survival was monitored for 24 hours. In Experiment II (physiologic study), rats were subjected to a sublethal HS (40% blood loss), followed by the same treatment with Tub A (treatment group) or DMSO only (vehicle group, n = 5 per group). All animals were sacrificed 6 hours after hemorrhage, and the heart and liver tissues were harvested. Sham animals were not subjected to hemorrhage and treatment (sham group, n = 5 per group). Cardiac mitochondria were isolated to study the pyruvate dehydrogenase (PDH, an essential enzyme for adenosine triphosphate production) activity. Liver tissue lysates were analyzed for markers of apoptosis (cytochrome c, cleaved caspase 3) and inflammation (high-mobility group box 1) by Western blotting.

RESULTS

Severe HS (55% blood loss) was associated with 75% mortality, which was significantly improved by Tub A treatment (37.5% mortality in 24 hours, p = 0.048). Tub A also significantly enhanced the cardiac PDH activity compared with the vehicle group, while suppressing the hepatic high-mobility group box 1 expression, cytochrome c release, and caspase 3 activation.

CONCLUSION

Our study has demonstrated for the first time that selective inhibition of HDAC6 can improve survival in a rodent model of HS. The potential mechanisms include enhanced PDH activity, decreased inflammatory drive, and attenuated cellular apoptosis.

Histone deactylase gene expression profiles are associated with outcomes in blunt trauma patients

BACKGROUND

Treatment with histone deacetylase (HDAC) inhibitors, such as valproic acid, increases survival in animal models of trauma and sepsis. Valproic acid is a pan-inhibitor that blocks most of the known HDAC isoforms. Targeting individual HDAC isoforms may increase survival and reduce complications, but little is known of the natural history of HDAC gene expression following trauma. We hypothesized that distinct HDAC isoform gene expression patterns would be associated with differences in outcomes following trauma.

METHODS

Twenty-eight-day longitudinal HDAC leukocyte gene expression profiles in 172 blunt trauma patients were extracted from the Inflammation and the Host Response to Injury (Glue Grant) data set. Outcome was classified as complicated (death or no recovery by Day 28, n = 51) or uncomplicated (n = 121). Mixed modeling was used to compare the HDAC expression trajectories between the groups, corrected for Injury Severity Score (ISS), base deficit, and volume of blood products transfused during the initial 12 hours following admission. Weighted gene correlation network analysis identified modules of genes with significant coexpression, and HDAC genes were mapped to these modules. Biologic function of these modules was investigated using the Gene Ontology database.

RESULTS

Elevated longitudinal HDAC expression trajectories for HDAC1, HDAC3, HDAC6, and HDAC11 were associated with complicated outcomes. In contrast, suppressed expression of Sirtuin 3 (SIRT3) was associated with adverse outcome (p < 0.01). Weighted gene correlation network analysis identified significant coexpression of HDAC and SIRT genes with genes involved in ribosomal function and down-regulation of protein translation in response to stress (HDAC1), T-cell signaling, and T-cell selection (HDAC3) as well as coagulation and hemostasis (SIRT3). No coexpression of HDAC11 was identified.

CONCLUSION

Expression trajectories of HDAC1, HDAC3, HDAC6, HDAC11, and SIRT3 correlate with outcomes following trauma and may potentially serve as biomarkers. They may also be promising targets for pharmacologic intervention. The effects of HDAC and SIRT gene expression in trauma may be mediated through pathways involved in ribosomal and T-cell function as well as coagulation and hemostasis.

LEVEL OF EVIDENCE

Prognostic study, level III.

Resuscitation with Valproic Acid Alters Inflammatory Genes in a Porcine Model of Combined Traumatic Brain Injury and Hemorrhagic Shock

Traumatic brain injury and hemorrhagic shock (TBI+HS) elicit a complex inflammatory response that contributes to secondary brain injury. There is currently no proven pharmacologic treatment for TBI+HS, but modulation of the epigenome has been shown to be a promising strategy. The aim of this study was to investigate whether valproic acid (VPA), a histone deacetylase inhibitor, modulates the expression of cerebral inflammatory gene profiles in a large animal model of TBI+HS. Ten Yorkshire swine were subjected to computer-controlled TBI+HS (40% blood volume). After 2 h of shock, animals were resuscitated with Hextend (HEX) or HEX+VPA (300 mg/kg, n = 5/group). Six hours after resuscitation, brains were harvested, RNA was isolated, and gene expression profiles were measured using a porcine microarray. Ingenuity Pathway Analysis® (IPA), gene ontology (GO), Parametric Gene Set Enrichment Analysis (PGSEA), and DAVID (Database for Annotation, Visualization, and Integrated Discovery) were used for pathway analysis. Key microarray findings were verified using real-time polymerase chain reaction (PCR). IPA analysis revealed that VPA significantly down-regulated the complement system (p < 0.001), natural killer cell communication (p < 0.001), and dendritic cell maturation (p < 0.001). DAVID analysis indicated that a cluster of inflammatory pathways held the highest rank and gene enrichment score. Real-time PCR data confirmed that VPA significantly down-expressed genes that ultimately regulate nuclear factor-kB (NF-kB)-mediated production of cytokines, such as TYROBP, TREM2, CCR1, and IL-1β. This high-throughput analysis of cerebral gene expression shows that addition of VPA to the resuscitation protocol significantly modulates the expression of inflammatory pathways in a clinically realistic model of TBI+HS.

Selective histone deacetylase 6 inhibition prolongs survival in a lethal two-hit model

BACKGROUND

Hemorrhagic shock (HS) followed by a subsequent insult ("second hit") often initiates an exaggerated systemic inflammatory response and multiple organ failure. We have previously demonstrated that valproic acid, a pan histone deacetylase inhibitor, could improve survival in a rodent "two-hit" model. In the present study, our goal was to determine whether selective inhibition of histone deacetylase 6 with Tubastatin A (Tub-A) could prolong survival in a two-hit model where HS was followed by sepsis from cecal ligation and puncture (CLP).

METHODS

C57Bl/6J mice were subjected to sublethal HS (30% blood loss) and then randomly divided into two groups (n = 13 per group) such as Tub-A group (treatment) and vehicle (VEH) group (control). The Tub-A group was given an intraperitoneal injection of Tub-A (70 mg/kg) dissolved in dimethyl sulfoxide (DMSO). The VEH group was injected with DMSO (1 μl/g body weight). After 24 h, all mice were subjected CLP followed immediately by another dose of Tub-A or DMSO. Survival was monitored for 10 d. In a parallel study, peritoneal irrigation fluid and liver tissue from Tub-A- or DMSO-treated mice were collected 3 h after CLP. Enzyme-linked immunosorbent assay was performed to quantify activity of the myeloperoxidase and concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) in the peritoneal irrigation fluid. RNA was isolated from the liver tissue, and real-time polymerase chain reaction was performed to measure relative messenger RNA levels of TNF-α and IL-6.

RESULTS

Treatment with Tub-A significantly improved survival compared with that of the control (69.2% versus 15.4%). In addition, Tub-A significantly suppressed myeloperoxidase activity (169.9 ± 8.4 ng/mL versus 70.4 ± 17.4 ng/mL; P < 0.01) and reduced levels of cytokines TNF-α and IL-6 in the peritoneal fluid (TNF-α: 105.7 ± 4.7 versus 7.4 ± 2.4 pg/mL; IL-6: 907.4 ± 2.3 versus 483.6 ± 1.6 pg/mL; P < 0.01) compared with those in the VEH control. Gene expression measured by real-time polymerase chain reaction confirmed that Tub-A inhibits transcription of TNF-α and IL-6.

CONCLUSIONS

Tub-A treatment significantly improves survival, attenuates inflammation, and downregulates TNF-α and IL-6 gene expression in a rodent two-hit model.

Effect of pharmacologic resuscitation on the brain gene expression profiles in a swine model of traumatic brain injury and hemorrhage

BACKGROUND

We have previously shown that addition of valproic acid (VPA; a histone deacetylase inhibitor) to hetastarch (Hextend [HEX]) resuscitation significantly decreases lesion size in a swine model of traumatic brain injury (TBI) and hemorrhagic shock (HS). However, the precise mechanisms have not been well defined. As VPA is a transcriptional modulator, the aim of this study was to investigate its effect on brain gene expression profiles.

METHODS

Swine were subjected to controlled TBI and HS (40% blood volume), kept in shock for 2 hours, and resuscitated with HEX or HEX + VPA (n = 5 per group). Following 6 hours of observation, brain RNA was isolated, and gene expression profiles were measured using a Porcine Gene ST 1.1 microarray (Affymetrix, Santa Clara, CA). Pathway analysis was done using network analysis tools Gene Ontology, Ingenuity Pathway Analysis, and Parametric Gene Set Enrichment Analysis. Real-time polymerase chain reaction was used to verify the key microarray findings.

RESULTS

A total of 1,668 probe sets mapping to 370 known genes were differentially expressed between the HEX and HEX + VPA groups. Expression of apoptotic genes differed between groups, and biologic function analysis predicted a significant downregulation of apoptosis (p = 1.29 × 10), cell death (p = 8.46 × 10), and necrosis (p = 9.07 × 10). Pathway analysis indicated a significant modulation of pathways involved in cell signaling, dendritic cell response, and the complement system.

CONCLUSION

This is the first high-throughput analysis of cerebral gene profiling following TBI + HS. It shows that treatment with VPA significantly alters early transcription of pathways related to cell survival, which may explain its neuroprotective effects.

Valproic acid treatment attenuates caspase-3 activation and improves survival after lethal burn injury in a rodent model

Burn injury may result in multiple organ dysfunction partially because of apoptotic cell death. The authors have previously shown that valproic acid (VPA) improves survival in a dog burn model. The aim of this study is to examine whether a VPA improves survival in a rodent burn model and whether this was because of inhibition of cell apoptosis. Rats were subjected to third-degree 55% TBSA burns and randomized to treatment with a VPA (300 mg/kg) or normal saline. One group of animals was monitored for 12 hours for survival analysis; another group was killed at 6 hours after injury, and brains, hearts, and blood samples were harvested for examination. Plasma creatine kinase (CK)-MB activities and neuron-specific enolase (NSE) levels were measured to evaluate the cardiac and brain damages. The effects of a VPA on acetylation of histone H3 and caspase-3 activation were also evaluated. Major burn injury resulted in a significant decrease in the acetylation of histone H3, and there was an increase in plasma CK-MB activities, NSE concentrations, and tissue levels of activated caspase-3. A VPA treatment significantly increased the acetylation of histone H3 and survival of the animals after major burn injury. In addition, a VPA treatment significantly attenuated the plasma CK-MB activities, an NSE concentrations, and inhibited caspase-3 activation after major burn injury. These results indicate that a VPA can attenuate cardiac and brain injury, and can improve survival in a rodent model of lethal burn injury. These protective effects may be mediated in part through the inhibition of caspase-3 activation.

Effects of acute doxorubicin treatment on hepatic proteome lysine acetylation status and the apoptotic environment

AIM: To determine if doxorubicin (Dox) alters hepatic proteome acetylation status and if acetylation status was associated with an apoptotic environment.

METHODS: Doxorubicin (20 mg/kg; Sigma, Saint Louis, MO; n = 8) or NaCl (0.9%; n = 7) was administered as an intraperitoneal injection to male F344 rats, 6-wk of age. Once animals were treated with Dox or saline, all animals were fasted until sacrifice 24 h later.

RESULTS: Dox treatment decreased proteome lysine acetylation likely due to a decrease in histone acetyltransferase activity. Proteome deacetylation may likely not be associated with a proapoptotic environment. Dox did not increase caspase-9, -8, or -3 activation nor poly (adenosine diphosphate-ribose) polymerase-1 cleavage. Dox did stimulate caspase-12 activation, however, it likely did not play a role in apoptosis induction.

CONCLUSION: Early effects of Dox involve hepatic proteome lysine deacetylation and caspase-12 activation under these experimental conditions.

Valproic acid attenuates lipopolysaccharide-induced acute lung injury in mice

Valproic acid (VPA) has been shown to exert anti-inflammatory and antioxidant effects in a range of diseases including septic shock. However, the effects of VPA on lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains not well understood. We found that VPA pretreatment attenuated the LPS-induced ALI, as evidenced by the reduced histological scores, myeloperoxidase activity, and wet-to-dry weight ratio in the lung tissues. This was accompanied by the downregulated nuclear factor kappa B (NF-κB) p65, nitric oxide, and inducible nitric oxide synthase in the lung tissues and the decreased levels of tumor necrosis factor alpha and interleukin-1β in the bronchoalveolar lavage fluid. Furthermore, VPA reduced the nuclear histone deacetylase (HDAC)3 expression whereas increased the cytoplasmic HDAC3 expression. Our results suggested that VPA attenuates the LPS-induced ALI via inhibiting the NF-κB activation probably through a mechanism depending on HDAC3 redistribution.

Development of a novel neuroprotective strategy: combined treatment with hypothermia and valproic acid improves survival in hypoxic hippocampal cells

BACKGROUND

Therapeutic hypothermia and histone deacetylase inhibitors, such as valproic acid (VPA), independently have been shown to have neuroprotective properties in models of cerebral ischemic and traumatic brain injury. However, the depth of hypothermia and the dose of VPA needed to achieve the desired result are logistically challenging. It remains unknown whether these two promising strategies can be combined to yield synergistic results. We designed an experiment to answer this question by subjecting hippocampal-derived HT22 cells to severe hypoxia in vitro.

METHODS

Mouse hippocampal HT22 cells were exposed to 200 μM cobalt chloride (CoCl(2)), which created hypoxic conditions in vitro. Cells were incubated for 6 or 30 hours under the following conditions: (1) Dulbecco's Modified Eagle Medium; (2) 200 μM CoCl(2); (3) 200 μM CoCl(2) plus 1 mmol/L VPA; (4) 200 μM CoCl(2) plus 32°C hypothermia; and (5) 200 μM CoCl(2) plus both 1 mmol/L VPA and 32°C hypothermia. Cellular viability was evaluated by (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) and lactate dehydrogenase release assays at 30 hours after treatment. Levels of acetylated histone H3, hypoxia-inducible factor-1α, phospho-GSK-3β, β-catenin, and high-mobility group box-1 were measured by Western blotting.

RESULTS

High levels of acetylated histone H3 were detected in the VPA-treated cells. The release of lactate dehydrogenase was greatly suppressed after the combined hypothermia + VPA treatment (0.269 ± 0.003) versus VPA (0.836 ± 0.026) or hypothermia (0.451 ± 0.005) treatments alone (n = 3, P = .0001). (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay showed that the number of viable cells was increased by 17.6 % when VPA and hypothermia were used in combination (n = 5, P = .0001). Hypoxia-inducible factor-1α and phospho-GSK-3β expression were synergistically affected by the combination treatment, whereas high-mobility group box-1 was increased by VPA treatment, and inhibited by the hypothermia.

CONCLUSION

This is the first study to demonstrate that the neuroprotective effects of VPA and hypothermia are synergistic. This novel approach can be used to develop more effective therapies for the prevention of neuronal death.

Selective histone deacetylase-6 inhibition attenuates stress responses and prevents immune organ atrophy in a lethal septic model

BACKGROUND

An overproduction of corticosterone during severe sepsis results in increased apoptosis of immune cells, which may result in relative immunosuppression and an impaired ability to fight infections. We have previously demonstrated that administration of tubastatin A, a selective inhibitor of histone deacetylase-6 (HDAC6), improves survival in a lethal model of cecal ligation and puncture (CLP) in mice. The purpose of this study was to characterize the effects of this treatment on sepsis-induced stress responses and immune function.

METHODS

C57BL/6J mice were subjected to CLP, and 1 hour later given an intraperitoneal injection of either tubastatin A dissolved in dimethyl sulfoxide (DMSO), or DMSO only. Blood samples were collected to measure the levels of circulating corticosterone and adrenocorticotropic hormone (ACTH). Thymus and long bones (femur and tibia) were subjected to hematoxylin and eosin staining, and immunohistochemistry was utilized to detect cleaved-caspase 3 in the splenic follicles as a measure of cellular apoptosis.

RESULTS

All vehicle-treated CLP animals died within 3 days, and displayed increased corticosterone and decreased ACTH levels compared with the sham-operated group. These animals also developed atrophy of thymic cortex with a marked depletion of thymocytes. Tubastatin A treatment significantly attenuated the stress hormone abnormalities. Treated animals also had significantly lower percentages of thymic atrophy (95.0 ± 5.0 vs 42.5 ± 25.3; P = .0366), bone marrow depletion and atrophy (58.3 ± 6.5 vs 25.0 ± 14.4%; P = .0449), and cellular apoptosis in the splenic follicles (41.2 ± 3.7 vs 28.5 ± 4.3 per 40× field; P = .0354).

CONCLUSION

Selective inhibition of HDAC6 in this lethal septic model was associated with a significant blunting of the stress responses, with attenuated thymic and bone marrow atrophy, and decreased splenic apoptosis. Our findings identify a novel mechanism behind the survival advantage seen with tubastatin A treatment.

The histone deacetylase inhibitor vorinostat prevents TNFα-induced necroptosis by regulating multiple signaling pathways

Histone deacetylase (HDAC) inhibitors are novel anticancer reagents that have recently been reported to have anti-inflammatory and neuroprotective effects; however, the mechanisms underlying their activities are largely undefined. The data from this study show that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) can protect L929 cells from TNFα-induced necroptosis. This effect involves multiple mechanisms, including the upregulation of cFLIPL expression, the enhanced activation of NFκB and p38 MAPK, and the inactivation of JNK. In addition, SAHA could initiate cell autophagy by inhibiting Akt and mTOR, which also play important roles in protecting cells from necroptosis. Because cell necroptosis is important for inflammation-related deterioration and neurodegenerative disease, our results indicate that preventing cell necrosis may be an important mechanism through which HDAC inhibitor compounds exert their anti-inflammatory or neuroprotective effects.

Treatment with a histone deacetylase inhibitor, valproic acid, is associated with increased platelet activation in a large animal model of traumatic brain injury and hemorrhagic shock

BACKGROUND

We have previously shown that resuscitation with fresh frozen plasma (FFP) in a large animal model of traumatic brain injury (TBI) and hemorrhagic shock (HS) decreases the size of the brain lesion, and that addition of a histone deacetylase inhibitor, valproic acid (VPA), provides synergistic benefits. In this study, we hypothesized that VPA administration would be associated with a conservation of platelet function as measured by increased platelet activation after resuscitation.

MATERIALS AND METHODS

Ten swine (42-50 kg) were subjected to TBI and HS (40% blood loss). Animals were left in shock for 2 h before resuscitation with either FFP or FFP+VPA (300 mg/kg). Serum levels of platelet activation markers transforming growth factor beta, CD40 L, P-selectin, and platelet endothelial cell adhesion molecule (PECAM) 1 were measured at baseline, postresuscitation, and after a 6-h observation period. Platelet activation markers were also measured in the brain whole cell lysates and immunohistochemistry.

RESULTS

Circulating P-selectin levels were significantly higher in the FFP+VPA group compared with the FFP alone group (70.85±4.70 versus 48.44±7.28 ng/mL; P<0.01). Likewise, immunohistochemistry data showed elevated P-selectin in the VPA treatment group (22.30±10.39% versus 8.125±3.94%, P<0.01). Serum sCD40L levels were also higher in the FFP+VPA group (3.21±0.124 versus 2.38±0.124 ng/mL; P<0.01), as was brain sCD40L levels (1.41±0.15 versus 1.22±0.12 ng/mL; P=0.05). Circulating transforming growth factor beta levels were elevated in the FFP+VPA group, but this did not reach statistical significance (11.20±1.46 versus 8.09±1.41 ng/mL; P=0.17). Brain platelet endothelial cell adhesion molecule 1 levels were significantly lower in the FFP+VPA group compared with the FFP group (5.22±2.00 pg/mL versus 7.99±1.13 pg/mL; P=0.03).

CONCLUSIONS

In this clinically relevant large animal model of combined TBI+HS, the addition of VPA to FFP resuscitation results in an early upregulation of platelet activation in the circulation and the brain. The previously observed neuroprotective effects of VPA may be due to a conservation of platelet function as measured by a higher platelet activation response after resuscitation.

Histone deacetylase inhibitors decrease intra-abdominal adhesions with one intraoperative dose by reducing peritoneal fibrin deposition pathways

BACKGROUND

We previously demonstrated that postoperative peritoneal injury and inflammation contribute to adhesiogenesis. Recent evidence suggests that in addition to their role of interfering with the acetylation status of nuclear histone proteins, histone deacetylase inhibitors (HDACIs) including valproic acid (VPA) can target nonhistone proteins to resolve inflammation and modulate immune cells. We hypothesized that HDACIs could reduce adhesions.

METHODS

Seventy-two rats underwent laparotomy with creation of 6 peritoneal ischemic buttons to induce adhesions. A single intraperitoneal (IP) dose of 50 mg/kg VPA was administered intraoperatively, whereas controls received vehicle. To evaluate the timing, 25 rats underwent ischemic button creation with either an intraoperative or a delayed IP dose of VPA at 1, 3, or 6 hours postoperatively. On postoperative day 7, adhesions were quantified. To investigate mechanisms, ischemic buttons were created in 24 rats and either VPA or saline was administered in 1 intraoperative dose. At 3 or 24 hours later, peritoneal fluid was collected and fibrinolytic activity measured. Alternatively, button tissue was collected 30 minutes postoperatively to measure tissue factor, fibrinogen, and vascular endothelial growth factor (VEGF) by real-time polymerase chain reaction or Western blot.

RESULTS

A single intraoperative dose of VPA reduced adhesions by 50% relative to controls (P < .001). Delayed dosing did not reduce adhesions. In operated animals, peritoneal fibrinolytic activity was not different between groups. Tissue factor mRNA was downregulated by 50% (P = .02) and protein by 34% (P < .01) in animals administered VPA versus saline. VPA decreased fibrinogen protein by 56% and VEGF protein by 25% compared with saline (P = .03).

CONCLUSION

These findings suggest that VPA rapidly reduces the extravasation of key adhesiogenic substrates into the peritoneum. A single, intraoperative intervention provides an ideal dosing strategy and indicates an exciting new role for HDACIs in adhesion prevention.

Pharmacologic modulation of cerebral metabolic derangement and excitotoxicity in a porcine model of traumatic brain injury and hemorrhagic shock

BACKGROUND

Cerebral metabolic derangement and excitotoxicity play critical roles in the evolution of traumatic brain injury (TBI). We have shown previously that treatment with large doses of valproic acid (VPA) decreases the size of brain lesion. The goal of this experiment was to determine whether this effect was owing to metabolic modulation.

METHODS

Yorkshire swine (n = 9) underwent a protocol of computer-controlled TBI and 40% hemorrhage and were resuscitated randomly with either fresh frozen plasma equal to the volume of shed blood (FFP; n = 4) or VPA (300 mg/kg) and FFP (FFP+VPA; n = 5). Hemodynamics, brain oxygenation, and blood glucose were monitored continuously for 6 hours after resuscitation. Cerebral microdialysis was used to measure glucose, lactate, pyruvate, glutamate, and glycerol levels at baseline, 1 and 2 hours post-shock, post-resuscitation (PR), and at 2, 4, and 6 hours PR. Brain samples from the injured side were then separated into mitochondrial and cytosolic fractions, and activity of pyruvate dehydrogenase complex (PDH) was measured using a dipstick assay kit.

RESULTS

At baseline, there was no difference in brain lactate, pyruvate, glycerol, and glutamate concentrations between the groups. At all time points, there were no differences between the groups in brain oxygenation, cerebral perfusion pressure, or blood and brain glucose concentrations. After VPA infusion (PR time point), however, there was sustained decrease in lactate (0.91 ± 0.47 vs 2.54 ± 0.59 mmol/L; P < .01) and pyruvate (12.80 ± 4.89 vs 46.25 ± 9.22; P < .001) concentrations compared with the FFP alone group, implying superior glucose utilization for ATP production. There was also a decrease in concentrations of glutamate (6.64 ± 3.68 vs 42.25 ± 27.07 mmol/L; P = .02) and glycerol (19.20 ± 6.76 vs 69.75 ± 30.07 mmol/L; P = .01), in the FFP+VPA group, signifying lesser degree of excitotoxicity and brain damage, respectively. Brain PDH activity was greater in the mitochondrial fractions (5,984 ± 504 adjusted volume intensity [INT] × mm(2) vs 4,332 ± 1,055 INT × mm(2); P = .04) and lower in cytosolic fractions in the FFP+VPA group (1,597 ± 1,395 vs 4,026 ± 1,067 INT × mm(2); P = .03), indicating better mitochondrial membrane function and enhanced mitochondrial PDH retention.

CONCLUSION

VPA treatment attenuates perturbation of post-traumatic cerebral metabolism by mitigating mitochondrial dysfunction, and decreases glutamate-mediated excitotoxic damage. These properties could explain its effectiveness in decreasing lesion size and post-traumatic cerebral edema.

Valproic acid treatment inhibits hypoxia-inducible factor 1α accumulation and protects against burn-induced gut barrier dysfunction in a rodent model

Objective

Burn-induced gut dysfunction plays an important role in the development of sepsis and multiple organ dysfunction. Emerging evidence suggests that hypoxia-inducible factor-1α (HIF-1α) is critical in paracelluar barrier functions via regulating vascular endothelial growth factor (VEGF) and myosin light chain kinase (MLCK) expression. Previous studies have also demonstrated that histone deacetylase inhibitors (HDACIs) can repress HIF-1α. This study aims to examine whether valproic acid (VPA), a HDACI, protects against burn-induced gut barrier dysfunction via repressing HIF-1α-dependent upregulation of VEGF and MLCK expression.

Methods

Rats were subjected to third degree 55% TBSA burns and treated with/ without VPA (300mg/kg). Intestinal barrier dysfunction was evaluated by permeability of intestinal mucosa to fluorescein isothiocyanate (FITC)-dextran and histologic evaluation. Histone acetylation, tight junction protein zonula occludens 1 (ZO-1), VEGF, MLCK and HIF-1α were measured. In addition, CaCO₂ cells were transfected with siRNA directed against HIF-1α and were stimulated with CoCl2 (1mM) for 24 hours with/without VPA (2mM) followed by analysis of HIF-1α, MLCK, VEGF and ZO-1.

Results

Burn insults resulted in a significant increase in intestinal permeability and mucosal damage, accompanied by a significant reduction in histone acetylation, ZO-1, upregulation of VEGF, MLCK expression, and an increase in HIF-1α accumulation. VPA significantly attenuated the increase in intestinal permeability, mucosa damage, histone deacetylation and changes in ZO-1 expression. VPA also attenuated the increased VEGF, MLCK and HIF-1α protein levels. VPA reduced HIF-1α, MLCK and VEGF production and prevented ZO-1 loss in CoCl2-stimulated Caco-2 cells. Moreover, transfection of siRNA directed against HIF-1α led to inhibition of MLCK and VEGF production, accompanied by upregulation of ZO-1.

Conclusions

These results indicate that VPA can protect against burn-induced gut barrier dysfunction. These protective effects may be due to its inhibitory action on HIF-1α, leading to a reduction in intestinal VEGF and MLCK expression and minimizing ZO-1 degradation.

Valproic acid for the treatment of hemorrhagic shock: a dose-optimization study

BACKGROUND

Valproic acid (VPA) has been shown to improve survival in animal models of hemorrhagic shock at a dose of 300 mg/kg. Our aim was to identify the ideal dose through dose-escalation, split-dosing, and dose de-escalation regimens.

MATERIALS AND METHODS

Rats were subjected to sublethal 40% hemorrhage and treated with vehicle or VPA (dose of 300, 400, or 450 mg/kg) after 30 min of shock. Acetylated histones and activated proteins from the PI3K-Akt-GSK-3β survival pathway at different time points were quantified by Western blot analysis. In a similar model, a VPA dose of 200 mg/kg followed 2 h later by another dose of 100 mg/kg was administered. Finally, animals were subjected to a lethal 50% hemorrhage and VPA was administered in a dose de-escalation manner (starting at dose of 300 mg/kg) until a significant drop in percent survival was observed.

RESULTS

Larger doses of VPA resulted in greater acetylation of histone 3 and increased activation of PI3K pathway proteins. Dose-dependent differences were significant in histone acetylation but not in the activation of the survival pathway proteins. Split-dose administration of VPA resulted in similar results to a single full dose. Survival was as follows: 87.5% with 300 and 250 mg/kg of VPA, 50% with 200 mg/kg of VPA, and 14% with vehicle-treated animals.

CONCLUSIONS

Although higher doses of VPA result in greater histone acetylation and activation of prosurvival protein signaling, doses as low as 250 mg/kg of VPA confer the same survival advantage in lethal hemorrhagic shock. Also, VPA can be given in a split-dose fashion without a reduction in its cytoprotective effectiveness.

The effects of acute doxorubicin treatment on proteome lysine acetylation status and apical caspases in skeletal muscle of fasted animals

BACKGROUND

Doxorubicin treatment is known to cause muscular weakness. However, the cellular mechanisms have not been elucidated. We aimed to determine the effects of acute doxorubicin treatment on proteome lysine acetylation status, an indication of the apoptotic and inflammatory environment, and the expression and activation of various apical caspases involved in the initiation of apoptosis.

METHODS

Six-week-old male F344 rats were injected intraperitoneally with 20 mg/kg of doxorubicin or saline. Once the treatment was administered, both groups of animals were fasted with no food or water until sacrifice 24 h posttreatment.

RESULTS

Doxorubicin treatment affected neither the proteome lysine acetylation status nor the expression of sirtuin 1, sirtuin 3, SOD1, or SOD2 in soleus of fasted animals. Doxorubicin treatment also did not affect the expression or activation of procaspase-1, procaspase-8, procaspase-9, or procaspase-12.

CONCLUSION

We suggest that doxorubicin does not exert a direct effect on these catabolic parameters in skeletal muscle in vivo.

Pharmacologic resuscitation for hemorrhagic shock combined with traumatic brain injury

BACKGROUND

We have previously demonstrated that valproic acid (VPA), a histone deacetylase inhibitor, can improve survival after hemorrhagic shock (HS), protect neurons from hypoxia-induced apoptosis, and attenuate the inflammatory response. We have also shown that administration of 6% hetastarch (Hextend [Hex]) after traumatic brain injury (TBI) decreases brain swelling, without affecting size of the lesion. This study was performed to determine whether addition of VPA to Hex would decrease the lesion size in a clinically relevant large animal model of TBI + HS.

METHODS

Yorkshire swine (42-50 kg) were instrumented to measure hemodynamic parameters, intracranial pressure, and brain tissue oxygenation. A custom-designed, computer-controlled cortical impact device was used to create a TBI through a 20-mm craniotomy: 15-mm cylindrical tip impactor at 4-m/s velocity, 100-millisecond dwell time, and 12-mm penetration depth. Volume-controlled hemorrhage was started (40% blood volume) concurrent with the TBI. After 2 hours of shock, animals were randomized to one of three resuscitation groups (n = 7 per group) as follows: (1) isotonic sodium chloride solution; (2) 6% hetastarch, Hex; and (3) Hex and VPA 300 mg/kg (Hex + VPA). Volumes of Hex matched the shed blood, whereas that of the isotonic sodium chloride solution was three times the volume. VPA treatment was started after an hour of shock. After 6 hours of postresuscitation monitoring, brains were sectioned into 5-mm slices and stained with 2, 3, 5-Triphenyltetrazolium chloride to quantify the lesion size (mm) and brain swelling (percent change compared with uninjured side). Levels of acetylated histone H3 were determined to quantify acetylation, and myeloperoxidase and interleukine-1β (IL-1β) levels were measured as markers of brain inflammation.

RESULTS

Combination of 40% blood loss with cortical impact and a period of shock (2 hours) and resuscitation resulted in a highly reproducible brain injury. Lesion size and brain swelling in the Hex + VPA group (1,989 [156.8] mm, and 19% [1.6%], respectively) were significantly smaller than the isotonic sodium chloride solution group (3,335 [287.9] mm and 36% [2.2%], respectively). Hex alone treatment significantly decreased the swelling (27% [1.6%]) without reducing the lesion size. The number of CD11b-positive cells as well as myeloperoxidase and IL-1 levels in the brains were significantly reduced by the VPA treatment.

CONCLUSION

In a combined HS and TBI model, treatment with artificial colloid (Hex) improves hemodynamic parameters and reduces swelling, without affecting the actual size of the brain lesion. Addition of VPA effectively reduces both the size of brain lesion and associated swelling by attenuating the inflammatory response.