Modulation of acetylation: creating a pro-survival and anti-inflammatory phenotype in lethal hemorrhagic and septic shock

Multimodal nanoparticle-containing modified suberoylanilide hydroxamic acid polymer conjugates to mitigate immune dysfunction in severe inflammation

Excessive immune activation and immunosuppression are opposing factors that contribute to the dysregulated innate and adaptive immune responses seen in severe inflammation and sepsis. Here, a novel analog of the histone deacetylase inhibitor (HDACi), suberoylanilide hydroxamic acid (SAHA-OH), was incorporated into immunomodulatory poly(lactic acid)-based nanoparticles (iNP-SAHA) by employing a prodrug approach through the covalent modification of poly(lactic-co-glycolic acid) (PLGA) with SAHA-OH. iNP-SAHA formulation allowed for controlled incorporation and delivery of SAHA-OH from iNP-SAHA and treatment led to multimodal biological responses including significant reductions in proinflammatory cytokine secretions and gene expression, while increasing the survival of primary macrophages under lipopolysaccharide (LPS) challenge. Using a lethal LPS-induced endotoxemia mouse model of sepsis, iNP-SAHA administration improved the survival of mice in a dose-dependent manner and tended to improve survival at the lowest doses compared to iNP control. Further, iNP-SAHA reduced the levels of plasma proinflammatory cytokines and chemokines associated with sepsis more significantly than iNP and similarly improved inflammation-induced spleen and liver toxicity as iNP, supporting its potential polypharmacological activity. Collectively, iNP-SAHA offers a potential drug delivery approach to modulate the multifaceted inflammatory responses observed in diseases such as sepsis.

Vagus nerve stimulation attenuates septic shock-induced cardiac injury in rats

This research aimed to evaluate whether vagus nerve stimulation (VNS) could effectively prevent septic shock-induced cardiac injury in rats and investigate the potential mechanisms. Female Sprague-Dawley rats were divided into the Sham group (sham cecal ligation and puncture [CLP] plus vagal nerve trunk separation), the Vehicle group (CLP plus vagal nerve trunk separation), and the VNS groups (CLP plus vagal nerve trunk separation plus VNS). The left ventricular function was analyzed by echocardiography. Histologic examinations of the cardiac tissues were performed through hematoxylin and eosin staining and TUNEL staining. The Vehicle group had worse cardiac function, higher levels of cardiac injury markers, and enhanced myocardial apoptosis than the Sham group. The rats in the VNS groups had enhanced cardiac function, lower levels of cardiac injury markers, and inhibited myocardial apoptosis than those in the Vehicle group. Elevated interleukin-1beta and tumor necrosis factor-alpha-levels and activated nuclear factor kappa B (NF-kappa-B) signal in septic shock rats were inhibited by the performance of VNS. This study suggests that VNS contributes to the reduction of myocardial apoptosis and improvement of left ventricular function to attenuate septic shock-induced cardiac injury in rats. The performance of VNS inhibits the inflammatory responses in heart tissues via the regulation of NF-kappa-B signal.

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.

HDAC Inhibition as Potential Therapeutic Strategy to Restore the Deregulated Immune Response in Severe COVID-19

The COVID-19 pandemic has had a devastating impact worldwide and has been a great challenge for the scientific community. Vaccines against SARS-CoV-2 are now efficiently lessening COVID-19 mortality, although finding a cure for this infection is still a priority. An unbalanced immune response and the uncontrolled release of proinflammatory cytokines are features of COVID-19 pathophysiology and contribute to disease progression and worsening. Histone deacetylases (HDACs) have gained interest in immunology, as they regulate the innate and adaptative immune response at different levels. Inhibitors of these enzymes have already proven therapeutic potential in cancer and are currently being investigated for the treatment of autoimmune diseases. We thus tested the effects of different HDAC inhibitors, with a focus on a selective HDAC6 inhibitor, on immune and epithelial cells in in vitro models that mimic cells activation after viral infection. Our data indicate that HDAC inhibitors reduce cytokines release by airway epithelial cells, monocytes and macrophages. This anti-inflammatory effect occurs together with the reduction of monocytes activation and T cell exhaustion and with an increase of T cell differentiation towards a T central memory phenotype. Moreover, HDAC inhibitors hinder IFN-I expression and downstream effects in both airway epithelial cells and immune cells, thus potentially counteracting the negative effects promoted in critical COVID-19 patients by the late or persistent IFN-I pathway activation. All these data suggest that an epigenetic therapeutic approach based on HDAC inhibitors represents a promising pharmacological treatment for severe COVID-19 patients.

Ring finger protein 219 regulates inflammatory responses by stabilizing sirtuin 1

BACKGROUND AND PURPOSE

Ring finger protein 219 (RNF219), a protein containing the C₃ HC₄ -type RING-HC motif, has been identified as a binding partner of the histone deacetylase sirtuin 1 (SIRT1). To explore the functions of RNF219, we examined its possible roles in the cellular responses to inflammation.

EXPERIMENTAL APPROACH

Effects of RNF219 on SIRT1 were studied in vitro using RAW264.7 cells and in male BALB/c mice, treated with LPS or IFN-γ. Western blots, RT-PCR, co-immunoprecipitation and ubiquitination assays were used, along with LC-MS/MS analysis. In vivo, survival and serum cytokines and tissue levels of RNF219 and SIRT1 were measured.

KEY RESULTS

Binding of RNF219 to SIRT1 inhibited degradation of SIRT1 by preventing its ubiquitination, thereby prolonging SIRT1-mediated anti-inflammatory signalling. LPS caused RNF219 deacetylation, leading to instability of RNF219 and preventing its association with SIRT1. Accordingly, the acetylation status of RNF219 is a critical determinant in its interaction with SIRT1, affecting the response to inflammatory stimuli. The deacetylase inhibitor trichostatin A, increased acetylation and stability of RNF219 and survival of mice injected with LPS, through the interaction of RNF219 with SIRT1.

CONCLUSION AND IMPLICATIONS

RNF219 is involved in a novel mechanism to stabilize SIRT1 protein by protein-protein interaction, leading to the resolution of cellular inflammation. These observations provide new insights into the function of RNF219 in modulation of cellular inflammation, and may aid and encourage the development of new anti-inflammatory drugs.

ATP Binding Cassette Transporter A1 is Involved in Extracellular Secretion of Acetylated APE1/Ref-1

Acetylation of nuclear apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE1/Ref-1) is associated with its extracellular secretion, despite the lack of an N-terminal protein secretion signal. In this study, we investigated plasma membrane targeting and translocation of APE1/Ref-1 in HEK293T cells with enhanced acetylation. While APE1/Ref-1 targeting was not affected by inhibition of the endoplasmic reticulum/Golgi-dependent secretion, its secretion was reduced by inhibitors of ATP-binding cassette (ABC) transporters, and siRNA-mediated down-regulation of ABC transporter A1. The association between APE1/Ref-1 and ABCA1 transporter was confirmed by proximal ligation assay and immunoprecipitation experiments. An APE1/Ref-1 construct with mutated acetylation sites (K6/K7R) showed reduced co-localization with ABC transporter A1. Exposure of trichostatin A (TSA) induced the acetylation of APE1/Ref-1, which translocated into membrane fraction. Taken together, acetylation of APE1/Ref-1 is considered to be necessary for its extracellular targeting via non-classical secretory pathway using the ABCA1 transporter.

Annexin A1 Bioactive Peptide Promotes Resolution of Neuroinflammation in a Rat Model of Exsanguinating Cardiac Arrest Treated by Emergency Preservation and Resuscitation

Neuroinflammation initiated by damage-associated molecular patterns, including high mobility group box 1 protein (HMGB1), has been implicated in adverse neurological outcomes following lethal hemorrhagic shock and polytrauma. Emergency preservation and resuscitation (EPR) is a novel method of resuscitation for victims of exsanguinating cardiac arrest, shown in preclinical studies to improve survival with acceptable neurological recovery. Sirtuin 3 (SIRT3), the primary mitochondrial deacetylase, has emerged as a key regulator of metabolic and energy stress response pathways in the brain and a pharmacological target to induce a neuronal pro-survival phenotype. This study aims to examine whether systemic administration of an Annexin-A1 bioactive peptide (ANXA1sp) could resolve neuroinflammation and induce sirtuin-3 regulated cytoprotective pathways in a novel rat model of exsanguinating cardiac arrest and EPR. Adult male rats underwent hemorrhagic shock and ventricular fibrillation, induction of profound hypothermia, followed by resuscitation and rewarming using cardiopulmonary bypass (EPR). Animals randomly received ANXA1sp (3 mg/kg, in divided doses) or vehicle. Neuroinflammation (HMGB1, TNFα, IL-6, and IL-10 levels), cerebral cell death (TUNEL, caspase-3, pro and antiapoptotic protein levels), and neurologic scores were assessed to evaluate the inflammation resolving effects of ANXA1sp following EPR. Furthermore, western blot analysis and immunohistochemistry were used to interrogate the mechanisms involved. Compared to vehicle controls, ANXA1sp effectively reduced expression of cerebral HMGB1, IL-6, and TNFα and increased IL-10 expression, which were associated with improved neurological scores. ANXA1sp reversed EPR-induced increases in expression of proapoptotic protein Bax and reduction in antiapoptotic protein Bcl-2, with a corresponding decrease in cerebral levels of cleaved caspase-3. Furthermore, ANXA1sp induced autophagic flux (increased LC3II and reduced p62 expression) in the brain. Mechanistically, these findings were accompanied by upregulation of the mitochondrial protein deacetylase Sirtuin-3, and its downstream targets FOXO3a and MnSOD in ANXA1sp-treated animals. Our data provide new evidence that engaging pro-resolving pharmacological strategies such as Annexin-A1 biomimetic peptides can effectively attenuate neuroinflammation and enhance the neuroprotective effects of EPR after exsanguinating cardiac arrest.

Complete and Partial Aortic Occlusion for the Treatment of Hemorrhagic Shock in Swine

Hemorrhage remains the leading cause of preventable deaths in trauma. Endovascular management of non-compressible torso hemorrhage has been at the forefront of trauma care in recent years. Since complete aortic occlusion presents serious concerns, the concept of partial aortic occlusion has gained a growing attention. Here, we present a large animal model of hemorrhagic shock to investigate the effects of a novel partial aortic balloon occlusion catheter and compare it with a catheter that works on the principles of complete aortic occlusion. Swine are anesthetized and instrumented in order to conduct controlled fixed-volume hemorrhage, and hemodynamic and physiological parameters are monitored. Following hemorrhage, aortic balloon occlusion catheters are inserted and inflated in the supraceliac aorta for 60 min, during which the animals receive whole-blood resuscitation as 20% of the total blood volume (TBV). Following balloon deflation, the animals are monitored in a critical care setting for 4 h, during which they receive fluid resuscitation and vasopressors as needed. The partial aortic balloon occlusion demonstrated improved distal mean arterial pressures (MAPs) during the balloon inflation, decreased markers of ischemia, and decreased fluid resuscitation and vasopressor use. As swine physiology and homeostatic responses following hemorrhage have been well-documented and are like those in humans, a swine hemorrhagic shock model can be used to test various treatment strategies. In addition to treating hemorrhage, aortic balloon occlusion catheters have become popular for their role in cardiac arrest, cardiac and vascular surgery, and other high-risk elective surgical procedures.

Complement inhibition ameliorates blast-induced acute lung injury in rats: Potential role of complement in intracellular HMGB1-mediated inflammation

BACKGROUND AND OBJECTIVE

Complement activation as an early and important inflammatory process contributes to multiple organ dysfunction after trauma. We have recently shown that complement inhibition by decay-accelerating factor (DAF) protects brain from blast-overpressure (BOP)-induced damage. This study was conducted to determine the effect of DAF on acute lung injury induced by BOP exposure and to elucidate its possible mechanisms of action.

METHODS

Anesthetized adult male Sprague-Daley rats were exposed to BOP (120 kPa) from a compressed air-driven shock tube. Rats were randomly assigned to three experimental groups: 1) Control (no BOP and no DAF treatment), 2) BOP (120 kPa BOP exposure), and 3) BOP followed by treatment with rhDAF (500μg/kg, i.v) at 30 minutes after blast. After a recovery period of 3, 24, or 48 hours, animals were euthanized followed by the collection of blood and tissues at each time point. Samples were subjected to the assessment of cytokines and histopathology as well as for the interaction of high-mobility-group box 1 (HMGB1) protein, NF-κB, receptor for advanced glycation end products (RAGE), C3a, and C3aR.

RESULTS

BOP exposure significantly increased in the production of systemic pro- and anti-inflammatory cytokines, and obvious pathological changes as characterized by pulmonary edema, inflammation, endothelial damage and hemorrhage in the lungs. These alterations were ameliorated by early administration of rhDAF. The rhDAF treatment not only significantly reduced the expression levels of HMGB1, RAGE, NF-κB, C3a, and C3aR, but also reversed the interaction of C3a-C3aR and nuclear translocation of HMGB1 in the lungs.

CONCLUSIONS

Our findings indicate that early administration of DAF efficiently inhibits systemic and local inflammation, and mitigates blast-induced lung injury. The underlying mechanism might be attributed to its potential modulation of C3a-C3aR-HMGB1-transcriptional factor axis. Therefore, complement and/or HMGB1 may be potential therapeutic targets in amelioration of acute lung injury after blast injury.

Lung Protective Effects of Low-Volume Resuscitation and Pharmacologic Treatment of Swine Subjected to Polytrauma and Hemorrhagic Shock

Hemorrhage is a common cause of death in the battlefield. Valproic acid (VPA) has been associated with improved outcomes in multiple models of trauma, when combined with isotonic fluid resuscitation. However, isotonic fluid administered in this setting is logistically impractical and may be associated with complications. In this study, we sought to evaluate the feasibility and immunologic impact of combining VPA treatment with low-volume hypertonic saline (HTS). In vivo: female Yorkshire swine were subjected to hemorrhage (40% total blood volume) and polytrauma (rib fracture and delayed liver injury). Animals were kept in shock for 30 minutes and resuscitated with (1) normal saline (NS, 3× hemorrhaged volume), (2) HTS (7.5% saline, 4 mL/kg), or (3) HTS + VPA (4 mg/kg; 150 mg/kg; n = 3/cohort). After 18 hours of observation, animals were euthanized and the lungs evaluated for acute injury and expression of myeloperoxidase (MPO) and caveolin-1 (Cav-1). In vitro: human umbilical vein endothelial cells (HUVECs) were exposed to anoxic conditions (5% CO₂, 95% N₂) for 16 hours in (1) normosmotic, (2) hyperosmotic (400 mOsm), or (3) hyperosmotic + VPA (4 mM) media. Immunohistochemistry and Western blots were performed to determine Cav-1 expression. Lungs from VPA-treated animals demonstrated decreased acute injury, MPO expression, and endothelial expression of Cav-1 when compared to lungs from animals resuscitated with NS or HTS alone. Similarly, HUVECs cultured in hyperosmotic media containing VPA demonstrated decreased expression of Cav-1. This study demonstrates that combined treatment with VPA and HTS is a viable strategy in hemorrhagic shock and polytrauma. Attenuation of lung injury following VPA treatment may be related to modulation of the inflammatory response.

Effect of Histone Acetylation on N-Methyl-D-Aspartate 2B Receptor Subunits and Interleukin-1 Receptors in Association with Nociception-Related Somatosensory Cortex Dysfunction in a Mouse Model of Sepsis

Whole-body inflammation (i.e., sepsis) often results in brain-related sensory dysfunction. We previously reported that interleukin (IL)-1 resulted in synaptic dysfunction of septic encephalopathy, but the underlying molecular mechanisms remain unknown, as do effective treatments. Using mice, we examined immunohistochemistry, co-immunoprecipitation, enzyme-linked immunosorbent assay, and behavior analyses, and investigated the role of the N-methyl-D-aspartate 2B subunit (NR2B) of NMDA receptor, IL-1 receptor, and histone acetylation in the pathophysiology underlying sensory dysfunction induced by lipopolysaccharide (LPS). Mice groups of sham-operated, LPS, LPS with an NR2B antagonist, or LPS with resveratrol (a histone acetylation activator) were analyzed. We found that LPS increased NR2B and interleukin-1 receptor (IL-1R) immunoreactivity. The expression of Iba1, a marker for microglia and/or macrophages, increased more significantly in the brain than in the spinal cord, implicating NR2B and IL-1R in brain inflammation. Immunoprecipitation with NR2B and IL-1R revealed related antibodies. Blood levels of IL-1β (i.e., the IL-1R ligand) increased, though not significantly, suggesting that inflammation peaked at 20 h. Behavioral assessments of central (CNS) and peripheral sensory (PNS) function indicated that LPS delayed CNS but not PNS escape latency. Finally, NR2B antagonist or resveratrol in the lateral ventricle antagonized the effects of LPS in the brain and improved animal survival. In summary, histone acetylation may control expression of NR2B and IL-1R, alleviating inflammation-induced sensory neuronal dysfunction caused by LPS.

Valproic acid attenuates the risk of acute respiratory failure in patients with subarachnoid hemorrhage

BACKGROUND

Valproic acid (VPA) has shown potent anti-inflammatory effect and attenuates acute lung injury.

AIM

To determine whether the use of VPA is associated with a decreased risk of acute respiratory failure (ARF) in patients with subarachnoid hemorrhage (SAH).

DESIGN

The Taiwan National Health Insurance Research Database was used to analyse all patients newly diagnosed with SAH from 2000 to 2010. The VPA users were matched for age, gender and index date in 1:2 ratios with randomly selected non-VPA users as a comparison group.

METHODS

Multivariate Cox regression was used to identify the predictors of ARF and to compare the incidence rates of ARF among SAH patients using and not using VPA.

RESULTS

The study cohort included 16 228 newly diagnosed SAH patients, from which 521 VPA users and 1042 matched non-VPA-exposed individuals were selected. In the VPA-treated cohort and the non-VPA-treated cohort, 117 and 289 patients developed ARF, respectively. Any use of VPA was associated with a 16% decreased risk of ARF requiring mechanical ventilation in 30-day tracking of the SAH patients (adjusted hazard ratio [HR], 0.840, 95% confidence interval [CI], 0.676-0.945). Age, sepsis and pneumonia were identified as independent predictors of ARF in patients with SAH. After stratification, VPA users showed a lower risk of ARF among SAH patients complicated with pneumonia compared with non-users of VPA (adjusted HR, 0.816, 95% CI, 0.652-0.921).

CONCLUSIONS

Any use of VPA was associated with a reduced risk of ARF in patients with SAH. VPA may be beneficial for decreasing the risk of pneumonia-induced ARF in patients with SAH.

HSP72 functionally inhibits the anti-neoplastic effects of HDAC inhibitors

BACKGROUND

The anticancer effects of histone deacetylase inhibitors (HDACi) vary between patients, and their molecular mechanisms remain poorly understood. Previously, we have identified heat shock 70 kDa protein 1A (HSPA1A, also known as HSP72) as the most overexpressed protein in valproic acid (VPA)-resistant cell lines. KNK437, an inhibitor of heat shock proteins, enhanced the cytotoxic effects of not only VPA but also vorinostat, another HDACi. However, the mechanisms underlying the role of HSP72 in resistance against HDACi remain largely unknown.

OBJECTIVE

The purpose of this study was to identify the mechanisms underlying the role of HSP72 in HDACi resistance.

METHODS

We established an HSP72-overexpressing Jurkat cell line and used it to assess the functional role of HSP72 following treatment with the HDACi vorinostat and VPA.

RESULTS

HDACi-induced apoptosis, assessed using annexin V assays, sub-G1 fraction analysis, and PARP cleavage, was significantly lower in HSP72-overexpressing cells than in control cells. The HDACi-induced upregulation in caspase-3, -8, and -9 activity, as well as the HDACi-induced reduction in mitochondrial membrane potential, were also suppressed following HSP72 overexpression. The basal expression levels of Bcl-2, phosphorylated Bad, and XIAP increased in HSP72-overexpressing cells, whereas HDACi-induced Bid truncation and the suppression of Bad expression. Furthermore, vorinostat-induced histone hyperacetylation was also diminished in HSP72-overexpressing cells.

CONCLUSION

These findings clearly demonstrate that HSP72 inhibits HDACi-induced apoptosis.

Metabolomics in Sepsis and Its Impact on Public Health

Sepsis, with its often devastating consequences for patients and their families, remains a major public health concern that poses an increasing financial burden. Early resuscitation together with the elucidation of the biological pathways and pathophysiological mechanisms with the use of "-omics" technologies have started changing the clinical and research landscape in sepsis. Metabolomics (i.e., the study of the metabolome), an "-omics" technology further down in the "-omics" cascade between the genome and the phenome, could be particularly fruitful in sepsis research with the potential to alter the clinical practice. Apart from its benefit for the individual patient, metabolomics has an impact on public health that extends beyond its applications in medicine. In this review, we present recent developments in metabolomics research in sepsis, with a focus on pneumonia, and we discuss the impact of metabolomics on public health, with a focus on free/libre open source software.

Mitochondrial dysfunction in rat splenocytes following hemorrhagic shock

The regulation of mitochondrial function is critical in cellular homeostasis following hemorrhagic shock. Hemorrhagic shock results in fluid loss and reduced availability of oxygen and nutrients to tissues. The spleen is a secondary lymphoid organ playing a key role in 'filtering the blood' and in the innate and adaptive immune responses. To understand the molecular basis of hemorrhagic shock, we investigated the changes in splenocyte mitochondrial respiration, and concomitant immune and metabolic alterations. The hemorrhagic injury (HI) in our rat model was induced by bleeding 60% of the total blood volume followed by resuscitation with Ringers lactate. Another group of animals was subjected to hemorrhage, but did not receive fluid resuscitation. Oxygen consumption rate of splenocytes were determined using a Seahorse analyzer. We found a significantly reduced oxygen consumption rate in splenocytes following HI compared to sham operated rats. The mitochondrial stress test revealed a decreased basal oxygen consumption rate, ATP production, maximal respiration and spare respiratory capacity. The mitochondrial membrane potential, and citrate synthase activity, were also reduced in the splenocytes following HI. Hypoxic response in the splenocyte was confirmed by increased gene expression of Hif1α. Elevated level of mitochondrial stress protein, hsp60 and induction of high mobility group box1 protein (HMGB1) were observed in splenocytes following HI. An increased inflammatory response was demonstrated by significantly increased expression of IL-6, IFN-β, Mip-1α, IL-10 and NFκbp65. In summary, we conclude that splenocyte oxidative phosphorylation and metabolism were severely compromised following HI.

Timing of valproic acid in acute lung injury: prevention is the best therapy?

BACKGROUND

Acute lung injury and respiratory distress syndrome is characterized by uncontrolled inflammation of the lungs after a severe inflammatory stimulus. We have previously demonstrated an ameliorated syndrome and improved survival in mice with early administration of valproic acid (VPA), a broad-spectrum histone deacetylase inhibitor, while studies in humans have shown no benefit when anti-inflammatories are administered late. The current study tested the hypothesis that early treatment would improve outcomes in our gram-negative pneumonia-induced acute lung injury.

MATERIALS AND METHODS

Mice (C57BL/6) had 50 × 10⁶ Escherichia coli (strain 19,138) instilled endotracheally and VPA (250 mg/kg) administered intraperitoneally 3, 4, 6, and 9 h (n = 12/group) later. Six hours after VPA administration, the animals were sacrificed, and bronchoalveolar lavage (BAL) fluid interleukin-6 (IL-6), tumor necrosis factor, neutrophils and macrophages as well as the E coli colony-forming units were quantified. Plasma IL-6 was also measured. A separate group of mice (n = 12/group) were followed prospectively for 7 days to assess survival.

RESULTS

BAL IL-6 and tumor necrosis factor as well as plasma IL-6 were significantly lower in the animals administered VPA within 3 h (P < 0.05) but not when administered later (4, 6, 9 h). There was no difference in the BAL E coli colony-forming units, macrophage, or neutrophil numbers at any time point. Survival improved only when VPA was administered within 3 h.

CONCLUSIONS

A narrow therapeutic window exists in this murine model of gram-negative pneumonia-induced acute lung injury and likely explains the lack of response in studies with late administration of anti-inflammatory therapies in clinical studies.

Inhibition of histone deacetylase 6 restores intestinal tight junction in hemorrhagic shock

BACKGROUND

We recently discovered that Tubastatin-A, a histone deacetylase (HDAC6) inhibitor, can improve survival in a rodent model of hemorrhagic shock (HS), but mechanisms remain poorly defined. In this study, we investigated whether Tubastatin-A could protect intestinal tight junction (TJ) in HS.

METHODS

In an in-vivo study with Wistar-Kyoto rats, the rats underwent HS (40% blood loss) followed by Tubastatin-A (70 mg/kg) treatment, without fluid resuscitation. The experimental groups were (1) sham (no hemorrhage, no treatment), (2) control (hemorrhage, without treatment), and (3) treatment (hemorrhage with Tubastatin-A administration). Six hours after hemorrhage, ileum was harvested. Whole cell lysate were analyzed for acetylated α-tubulin (Ac-tubulin), total tubulin, acetylated histone 3 at lysine 9 (Ac-H3K9), β-actin, claudin-3 and zonula occludens 1 (ZO-1) proteins by Western blot. Histological effects of Tubastatin-A on small bowel were examined. In an in-vitro study, human intestinal epithelial cells (Caco-2) were divided into three groups: (1) sham (normoxia), (2) control (anoxia, no treatment), and (3) treatment (anoxia, treatment with Tubastatin-A). After 12 hours in an anoxia chamber, the cells were examined for Ac-tubulin and Ac-H3K9, cellular viability, cytotoxicity, claudin-3 and ZO-1 protein expression, and transwell permeability study.

RESULTS

Tubastatin-A treatment significantly attenuated HS-induced decreases of Ac-tubulin, Ac-H3K9, ZO-1 and claudin-3 proteins in small bowel in-vivo (p < 0.05). In cultured Caco-2 cells, anoxia significantly decreased cellular viability (p < 0.001) and increased cytotoxicity (p < 0.001) compared to the sham group, while Tubastatin-A treatment offered significant protection (p < 0.0001). Moreover, expression of claudin-3 was markedly decreased in vitro compared to the sham group, whereas this was significantly attenuated by Tubastatin-A (p < 0.05). Finally, anoxia markedly increased the permeability of Caco-2 monolayer cells (p < 0.05), while Tubastatin-A significantly attenuated the alteration (p < 0.05).

CONCLUSION

Inhibition of HDAC6 can induce Ac-tubulin and Ac-H3K9, promote cellular viability, and prevent the loss of intestinal tight junction proteins during HS and anoxia.

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.

Inhibition of histone deacetylase 6 restores innate immune cells in the bone marrow in a lethal septic model

BACKGROUND

We have previously demonstrated that Tubastatin A, a selective inhibitor of histone deacetylase 6 (HDAC6), improves survival and increases circulating monocyte count and bacterial clearance in a lethal model of cecal ligation and puncture (CLP) in mice. The aim of the present study was to characterize the effects of inhibition of HDAC6 on the bone marrow cell population.

METHODS

C57BL/6J mice were subjected to CLP and, 1 hour later, given an intraperitoneal injection of either Tubastatin A (70 mg/kg) dissolved in DMSO or DMSO alone (n = 9 per group). Sham-operated animals were treated in an identical fashion, without CLP. Forty-eight hours later, bone marrow cells were flushed out from the femurs and tibias. Erythrocytes were lysed, and a single-cell suspension was made for analysis. Cells were washed; blocked with antimouse CD16/32; stained with antimouse B220 PE-Cy7, CD3 APC-eFluor 780, CD11b FITC, Gr-1 PerCP-Cy5.5, and F4/80 Antigen APC; and subjected to flow cytometry. Data were acquired on an LSRII Flow Cytometer (BD Biosciences, San Jose, CA) and analyzed with FlowJo (Flowjo, LLC, Ashland, OR).

RESULTS

In comparison with the sham group, CLP animals showed decreased percentage of innate immune cells (CD11b, 62.1% ± 3.1% vs. 32.9% ± 4.9%, p = 0.0025) and macrophages (CD11bF4/80, 44.6% ± 3.4% vs. 19.8% ± 2.6%, p = 0.0002) as well as increased percentage of T lymphocytes (CD3, 1.1% ± 0.2% vs. 3.3% ± 0.4%, p = 0.0082) in the bone marrow 48 hours after CLP. Treatment with Tubastatin A restored the innate immune cells (32.9% ± 4.9% vs. 54.0% ± 4.1%, p = 0.0112) and macrophages (19.8% ± 2.6% vs. 47.1% ± 4.6%, p = 0.0001) and increased the percentage of neutrophils (CD11bGr-1, 28.4% ± 3.9% vs. 48.0% ± 4.0%, p = 0.0075). The percentages of B (B220) and T lymphocytes were not significantly altered by Tubastatin A, compared with the vehicle-treated CLP animals.

CONCLUSION

Selective inhibition of HDAC6 in this lethal septic model restored the innate immune cell and macrophage populations and increased the neutrophil composition in the bone marrow. These results may explain the previously reported beneficial effects of Tubastatin A treatment in a septic model.

Trichostatin A Protects Liver against Septic Injury through Inhibiting Toll-Like Receptor Signaling

Sepsis, a serious clinical problem, is characterized by a systemic inflammatory response to infection and leads to organ failure. Toll-like receptor (TLR) signaling is intimately implicated in hyper-inflammatory responses and tissue injury during sepsis. Histone deacetylase (HDAC) inhibitors have been reported to exhibit anti-inflammatory properties. The aim of this study was to investigate the hepatoprotective mechanisms of trichostatin A (TSA), a HDAC inhibitor, associated with TLR signaling pathway during sepsis. The anti-inflammatory properties of TSA were assayed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Polymicrobial sepsis was induced in mice by cecal ligation and puncture (CLP), a clinically relevant model of sepsis. The mice were intraperitoneally received TSA (1, 2 or 5 mg/kg) 30 min before CLP. The serum and liver samples were collected 6 and 24-h after CLP. TSA inhibited the increased production of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in LPS-stimulated RAW264.7 cells. TSA improved sepsis-induced mortality, attenuated liver injury and decreased serum TNF-α and IL-6 levels. CLP increased the levels of TLR4, TLR2 and myeloid differentiation primary response protein 88 (MyD88) protein expression and association of MyD88 with TLR4 and TLR2, which were attenuated by TSA. CLP increased nuclear translocation of nuclear factor kappa B and decreased cytosolic inhibitor of kappa B (IκB) protein expression, which were attenuated by TSA. Moreover, CLP decreased acetylation of IκB kinase (IKK) and increased association of IKK with IκB and TSA attenuated these alterations. Our findings suggest that TSA attenuates liver injury by inhibiting TLR-mediated inflammatory response during sepsis.

Inhibition of peptidylarginine deiminase attenuates inflammation and improves survival in a rat model of hemorrhagic shock

BACKGROUND

We have recently shown that inhibition of peptidylarginine deiminase (PAD) improves survival in a rodent model of lethal cecal ligation and puncture. The roles of PAD inhibitors in hemorrhagic shock (HS), however, are largely unknown. The goal of this study was to investigate the effects of YW3-56, a novel PAD inhibitor, on survival after severe HS.

METHODS

Mouse macrophages were exposed to hypoxic conditions followed by reoxygenation in the presence or absence of YW3-56. Enzyme-linked immunosorbent assay (ELISA) was performed to measure levels of secreted tumor necrosis factor α and interleukin-6 in the culture medium. Cell viability was determined by methyl thiazolyl tetrazolium assay. In the survival experiment, anesthetized male Wistar-Kyoto rats (n = 10/group) were subjected to 55% blood loss, and treated with or without YW3-56 (10 mg/kg, intraperitoneally). Survival was monitored for 12 h. In the nonsurvival experiment, morphologic changes of the lungs were examined. Levels of circulating cytokine-induced neutrophil chemoattractant 1 (CINC-1) and myeloperoxidase (MPO) in the lungs were measured by ELISA. Expression of lung intercellular adhesion molecules-1 (ICAM-1) was also determined by Western blotting.

RESULTS

Hypoxia/reoxygenation (H/R) insult induced tumor necrosis factor α and interleukin-6 secretion from macrophages, which was significantly attenuated by YW3-56 treatment. YW3-56 treatment also increased cell viability when macrophages were exposed to H/R up to 6/15 h and improved survival rate from 20% to 60% in lethal HS rat model. Compared to the sham groups, pulmonary MPO activity and ICAM-1 expression in the HS group were significantly increased, and acute lung injury was associated with a higher degree of CINC-1 levels in serum. Intraperitoneal delivery of YW3-56 significantly reduced pulmonary MPO and ICAM-1 expression and attenuated acute lung injury.

CONCLUSIONS

Our results demonstrate for the first time that administration of YW3-56, a novel PAD inhibitor, can improve survival in a rat model of HS and in a cell culture model of H/R. The survival advantage is associated with an attenuation of local and systemic pro-inflammatory cytokines and the protection against acute lung injury after hemorrhage. Thus, PAD inhibition may represent a novel and promising therapeutic strategy for severe HS.

Histone cleavage as a mechanism for epigenetic regulation: current insights and perspectives

Discovered over a century ago, histones constitute one of the oldest families of proteins and have been remarkably conserved throughout eukaryotic evolution. However, only for the past 30 years have histones demonstrated that their influence extends far beyond packaging DNA. To create the various chromatin structures that are necessary for DNA function in higher eukaryotes, histones undergo posttranslational modifications. While many such modifications are well documented, others, such as histone tail cleavage are less understood. Recent studies have discovered several proteases that cleave histones and have suggested roles for clipped histones in stem cell differentiation and aging in addition to infection and inflammation; the underlying mechanisms, however, are uncertain. One histone class in particular, histone H3, has received outstanding interest due to its numerous N-terminal modification sites and prevalence in regulating homeostatic processes. Here, with special consideration of H3, we will discuss the novel findings regarding histone proteolytic cleavage as well as their significance in the studies of immunology and epigenetics.

Are the paradigms in trauma disease changing?

Despite an annual trauma mortality of 5 million people worldwide, resulting in countless physical disabilities and enormous expenses, there are no standardized guidelines on trauma organization and management. Over the last few decades there have been very notorious improvements in severe trauma care, though organizational and economical aspects such as research funding still need to be better engineered. Indeed, trauma lags behind other serious diseases in terms of research and organization. The rapid developments in trauma care have produced original models available for research projects, initial resuscitation protocols and radiological procedures such as CT for the initial management of trauma patients, among other advances. This progress underscores the need for a multidisciplinary approach to the initial management and follow-up of this complicated patient population, where intensivists play a major role in both the patient admission and subsequent care at the trauma unit.

Effects of sodium butyrate on aversive memory in rats submitted to sepsis

Epigenetic mechanisms are involved in normal behavior and are implicated in several brain neurodegenerative conditions, psychiatric and inflammatory diseases as well. Moreover, it has been demonstrated that sepsis lead to an imbalance in acetylation of histones and that histone deacetylase inhibitors (HDACi) can reverse this condition. In the present study, we evaluated the effects of a microinjection of sodium butyrate (SB, HDACi) into cerebral ventricle on aversive memory in rats submitted to the sepsis. Rats were given a single intraventricular injection of artificial cerebrospinal fluid (ACSF) or SB and immediately after the stereotaxic surgery and the drug infusion, the animals were subjected to cecal ligation and perforation (CLP). The animals were killed twenty four hours or ten days after sepsis induction and the prefrontal cortex, hippocampus, striatum and cortex were obtained to the determination of histone deacetylase activity. In a separate cohort of animals 10 days after sepsis induction, it was performed the inhibitory avoidance task. SB administration was able to reverse the impairment in aversive memory and inhibited the HDAC activity in prefrontal cortex and hippocampus 10 days after CLP. These support a role for an epigenetic mechanism in the long-term cognitive impairments observed in sepsis survivors animals.

Protection against reperfusion lung injury via aborgating multiple signaling cascades by trichostatin A

Trichostatin A (TSA) is a histone deacetylase inhibitor with anti-inflammatory effects. Nonetheless, little information is available about the effect of TSA in ischemia-reperfusion (IR)-induced lung injury. In a perfused rat lung model, IR was induced by 40min of ischemia followed by 60min of reperfusion. The rat lungs were randomly divided into several groups including control, control+TSA (0.1mg/kg), IR, and IR+various dosages of TSA (0.05, 0.075, 0.1mg/kg). Bronchoalveolar lavage fluids and lung tissues were obtained and examined at the end of the experiment. TSA dose-dependently diminished IR-induced increased vascular permeability and edema, pulmonary artery pressure, and histological changes in the lungs. Additionally, TSA suppressed lavage tumor necrosis factor-α and cytokine-induced neutrophil chemoattractant concentrations, cell infiltration, and myeloperoxidase-positive cells in the lung tissue. Furthermore, TSA attenuated the phosphorylation of extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase, degradation of the inhibitor of nuclear factor (NF)-κB, and nuclear NF-κB levels. TSA also decreased poly (ADP-ribose) polymerase but enhanced acetylated histone H3 acetylation, Bcl-2, and mitogen-activated protein kinase phosphatase-1 (MKP-1) expression in IR lung tissue. Therefore, TSA exerted a protective effect on IR-induced lung injury via increasing histone acetylation and MKP-1 protein expression, repressing NF-κB, mitogen-activated protein kinase, and apoptosis signaling pathways.

Protective effect of suberoylanilide hydroxamic acid against lipopolysaccharide-induced liver damage in rodents

BACKGROUND

Lipopolysaccharide (LPS) has a deleterious effect on several organs, including the liver, and eventually leads to endotoxic shock and death. LPS-induced hepatotoxicity is characterized by disturbed intracellular redox balance and excessive reactive oxygen species (ROS) accumulation, leading to liver injury. We have shown that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in a murine model of LPS-induced shock, but the protective effect of SAHA against liver damage remains unknown. The goal of this study was to investigate the mechanism underlying SAHA action in murine livers.

METHOD

Male C57BL/6J mice (6-8 wk), weighing 20-25 g, were randomly divided into three groups: (A) a sham group was given isotonic sodium chloride solution (10 μL/g body weight, intraperitoneal, i.p.) with dimethyl sulfoxide (DMSO; 1 μL/g body weight, i.p.); (B) an LPS group was challenged with LPS (20 mg/kg, i.p.) dissolved in isotonic sodium chloride solution with DMSO; (C) and an LPS plus SAHA group was treated with SAHA (50 mg/kg, i.p.) dissolved in DMSO immediately after injection of LPS (20 mg/kg, i.p.). Mice were anesthetized, and their livers were harvested 6 or 24 h after injection to analyze whether SAHA affected production of ROS and activation of apoptotic proteins in the liver cells of challenged mice.

RESULTS

SAHA counteracted LPS-induced production of ROS (thiobarbituric acid reactive substances and nitrite) and reversed an LPS-induced decrease in antioxidant enzyme, glutathione. SAHA also attenuated LPS-induced hepatic apoptosis. Moreover, SAHA inhibited activation of the redox-sensitive kinase, apoptosis signal-regulating kinase-1, and the mitogen-activated protein kinases, p38 and Jun N-terminal kinase.

CONCLUSIONS

Our data indicate, for the first time, that SAHA is capable of alleviating LPS-induced hepatotoxicity and suggest that a blockade of the upstream events required for apoptosis signal-regulating kinase-1 action may serve as a new therapeutic option in the treatment of LPS-induced inflammatory conditions.

Creating a prosurvival phenotype through a histone deacetylase inhibitor in a lethal two-hit model

OBJECTIVES

Hemorrhagic shock (HS) can initiate an exaggerated systemic inflammatory response and multiple organ failure, especially if followed by a subsequent inflammatory insult ("second hit"). We have recently shown that histone deacetylase inhibitors can improve survival in rodent models of HS or septic shock, individually. In the present study, we examined whether valproic acid (VPA), a histone deacetylase inhibitor, could prolong survival in a rodent "two-hit" model: HS followed by septic shock from cecal ligation and puncture (CLP).

METHODS

Male Sprague-Dawley rats (250-300 g) were subjected to sublethal HS (40% blood loss) and then randomly divided into two groups (n = 7/group): VPA and control. The VPA group was treated intraperitoneally with VPA (300 mg/kg in normal saline [NS], volume = 750 μL/kg). The control group was injected with 750 μL/kg NS. After 24 h, all rats received CLP followed immediately by injection of the same dose of VPA (VPA group) or NS (vehicle group). Survival was monitored for 10 days. In a parallel study, serum and peritoneal irrigation fluid from VPA- or vehicle-treated rats were collected 3, 6, and 24 h after CLP, and enzyme-linked immunosorbent assay was performed to analyze myeloperoxidase activity and determine tumor necrosis factor α and interleukin 6 concentrations. Hematoxylin-eosin staining of lungs at 24-h time point was performed to investigate the grade of acute lung injury.

RESULTS

Rats treated with VPA (300 mg/kg) showed significantly higher survival rates (85.7%) compared with the control (14.3%). Moreover, VPA significantly suppressed myeloperoxidase activity (marker of neutrophil-mediated oxidative damage) and inhibited levels of proinflammatory cytokine tumor necrosis factor α and interleukin 6 in the serum and peritoneal cavity. Meanwhile, the severity of acute lung injury was significantly reduced in VPA-treated animals.

CONCLUSIONS

We have demonstrated that VPA treatment improves survival and attenuates inflammation in a rodent two-hit model.

Effect of valproic acid and injury on lesion size and endothelial glycocalyx shedding in a rodent model of isolated traumatic brain injury

BACKGROUND

In isolated traumatic brain injury (TBI), little is known about the endothelial response and the effects of endothelial glycocalyx shedding. We have previously shown that treatment with valproic acid (VPA) improves outcomes following TBI and hemorrhagic shock.In this model, we hypothesized that severe isolated TBI would cause shedding of the endothelial glycocalyx, as measured by serum syndecan-1 (sSDC-1) levels. We further hypothesized that VPA treatment would reduce this response and reduce lesion size volume.

METHODS

Forty Sprague-Dawley rats were allocated to TBI + VPA (n = 8), TBI + saline vehicle control infusion (n = 8), sham + saline vehicle control infusion (n = 6), or sham + VPA (n = 8). TBI animals were subjected to severe controlled cortical impact and killed 6 hours after injury. VPA 300 mg/kg was given as an intravenous bolus 30 minutes after injury. Serum samples were analyzed for sSDC-1, and lesion size was determined on Nissl-stained cryosections.

RESULTS

sSDC-1 was significantly elevated in injured compared with uninjured animals at 3 hours (p = 0.0009) and 6 hours (p = 0.0007) after injury. This effect was significantly more pronounced in the animals treated with VPA (p = 0.019) 3 hours after injury, in which sSDC-1 levels were also significantly inversely correlated with lesion size (ρ = -0.55, p = 0.038).Lesion size was significantly smaller in TBI + VPA (40.45 mm ± 13.83 mm) as compared with vehicle control (59.57 mm ± 16.83 mm) (p = 0.023).

CONCLUSION

Severe isolated TBI caused shedding of the endothelial glycocalyx. Treatment with VPA was associated with increased glycocalyx shedding and reduced lesion size volume in injured animal.

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.

Modern resuscitation of hemorrhagic shock: what is on the horizon?

PURPOSE

Mortality rates among the severely injured remain high. The successful treatment of hemorrhagic shock relies on expeditious control of bleeding through surgical ligation, packing, or endovascular techniques. An important secondary concern in hemorrhaging patients is how to respond to the lost blood volume. A single method that is able to adequately address all needs of the exsanguinating patient has not yet been agreed upon, despite a large growth of knowledge regarding the causative factors of traumatic shock.

METHODS

A review of relevent literature was performed.

CONCLUSIONS

Many different trials are currently underway to discriminate ways to improve outcomes in the severely injured and bleeding patient.  This paper will review: (1) recent advances in our understanding of the effects hemorrhagic shock has on the coagulation cascade and vascular endothelium, (2) recent research findings that have changed resuscitation, and (3) resuscitation strategies that are not widely used but under active investigation.

Effects of histone deacetylase inhibition on 24-hour survival and end-organ injury in a porcine trauma model: a prospective, randomized trial

BACKGROUND

Valproic acid (VPA) is a histone deacetylase inhibitor that has been shown to improve early resuscitation from hemorrhagic shock. We sought to examine whether there is a sustained benefit of VPA in a survival model of severe injury.

METHODS

Yorkshire swine (n = 36) were randomized to three groups as follows: (a) control, (b) VPA (single dose), and (c) VPA (two doses at 12 hours apart). Animals underwent a 35% volume-controlled hemorrhage, followed by aortic cross-clamping for 50-minute duration, at which time VPA (400 mg/kg) was administered intravenously. Animals then underwent protocol guided resuscitation with crystalloid and vasopressor infusions for up to 24 hours. The primary end point was animal survival; secondary end points included hemodynamics, physiology, and histologic evidence of end-organ injury.

RESULTS

Mean duration of survival was significantly longer in the control group (15.8 hours, n = 11) compared with single-dose VPA (12.6 hours, n = 9, p < 0.02). Redosing VPA at 12 hours provided no survival benefit. During cross-clamp, animals that received VPA required significantly less lidocaine compared with the control animals (32.8 mg vs. 159.4 mg, p = 0.03). Animals that received VPA also required significantly greater quantities of intravenous fluids per hour (p < 0.01) and higher epinephrine doses (p = 0.01). VPA administration was associated with earlier evidence of cardiac suppression (decreased cardiac output, increased pulmonary wedge pressures, and systemic vascular resistance; p < 0.05). VPA was associated with renal end-organ histologic protection and improved levels of blood urea nitrogen and creatinine at all time points (p < 0.05).

CONCLUSION

Despite previous reports citing improved early outcomes with VPA administration, VPA did not improve resuscitation or mortality in a survival model with severe injury. VPA did show some evidence of prolonged renal protection. No benefit of redosing VPA was identified. VPA had a cardiac depressant effect that may be dose dependent and should be studied further.

Neutrophil extracellular traps, damage-associated molecular patterns, and cell death during sepsis

In addition to pathogen-associated molecular patterns from invasive microorganisms, alarmins, which are major components of host defense mechanisms, are involved in the pathophysiology of sepsis. In fact, the magnitude of the insult is defined according to the damage-associated molecular pattern (DAMP), which is composed of alarmins as well as pathogen-associated molecular patterns, such as those involving nucleosomes, histones, and DNA. Regarding the antimicrobial mechanism of neutrophils, an alternative non-phagocytic mechanism was first recognized as "NETosis" in 2004. In this mechanism, microorganisms are trapped and eliminated by neutrophil extracellular traps (NETs). These NETs are composed of histones and DNA that have been expelled from the nucleus as well as antimicrobial proteases, including elastase and myeloperoxidase. NETosis, a cell death pathway reported to be distinct from apoptosis, is an active area of research. As NETs are composed of deleterious substances, they are extremely harmful to the host cells once they are released into the circulating blood. Therefore, the meanings and putative roles of these components in sepsis have attracted much attention.

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.

Beneficial effects of histone deacetylase inhibition with severe hemorrhage and ischemia-reperfusion injury

BACKGROUND

Valproic acid (VPA) is a histone deacetylase inhibitor that may decrease cellular metabolic needs following traumatic injury. We hypothesized that VPA may have beneficial effects in preventing or reducing the cellular and metabolic sequelae of ischemia-reperfusion injury.

METHODS

Twenty-eight Yorkshire swine underwent 35% blood volume hemorrhage, followed by a lethal truncal ischemia-reperfusion injury and 6 h of resuscitation. Physiologic and laboratory parameters were closely measured and the pigs divided into four groups: sham, control (injury protocol), VPA dosing before cross-clamp (VPA-B), and VPA dosing after cross-clamp (VPA-A).

RESULTS

All animals developed significant coagulopathy, acidosis, and anemia. Animals receiving VPA-A had decreased acidosis and coagulopathy as measured by pH (P = 0.016) and international normalized ratio (P = 0.013) over the resuscitation. VPA-A pigs had a decreased requirement for crystalloid (P = 0.007) and epinephrine (P < 0.0001) during resuscitation. Pathologic analysis demonstrated decreased liver injury with VPA administration. VPA administration increased levels of acetylated proteins in liver and lung tissues, and was associated with increased expression of heat shock protein 70 versus controls.

CONCLUSIONS

Valproic acid conferred a significant cardiovascular, metabolic, and pathologic protective effect in a model of severe injury. Earlier administration (VPA-B) was significantly less effective compared with dosing after initial hemorrhage control.

Synergistic effects of hypertonic saline and valproic acid in a lethal rat two-hit model

BACKGROUND

Hemorrhagic shock (HS) followed by an infection ("second hit") can lead to severe systemic inflammatory response and multiple-organ failure. Studies have shown that resuscitation with hypertonic saline (HTS) can blunt the inflammatory response. We demonstrated that large doses of valproic acid (VPA, 300 mg/kg), a histone deacetylase inhibitor, improves survival in a rodent two-hit model (HS followed by cecal ligation and puncture [CLP]). In the present study, we examined whether combination of HTS with VPA would allow us to achieve survival advantage at a lower dose of VPA (200 mg/kg).

METHODS

Male Sprague-Dawley rats were subjected to HS (50% blood loss) and randomized into five groups (n = 7-8 per group) as follows: (1) isotonic sodium chloride solution (ISCS), (2) 7.5% saline, (3) VPA, (4) ISCS + VPA, and (5) HTS + VPA. After 24 hours, they underwent CLP, followed by the same doses of ISCS, HTS, and/or VPA and were monitored for 10 days. In a parallel experiment, blood, peritoneal irrigation fluid and lung homogenate were subjected to enzyme-linked immunosorbent assay 3 hours and 24 hours after CLP to measure myeloperoxidase activity and proinflammatory cytokines tumor necrosis factor α and interleukin 1β levels. Western blotting was performed to investigate the expression of pentraxin 3 protein in the lung homogenate at 24 hours after CLP. Hematoxylin and eosin staining of lungs at the 24 hours were performed to quantify the degree of acute lung injury.

RESULTS

HTS + VPA treatment significantly improved survival (87.5%), compared with the other groups (14.3%; p < 0.05), while attenuating peritoneal myeloperoxidase levels and proinflammatory cytokine tumor necrosis factor α and interleukin 1β levels in the serum, peritoneal cavity, and lung. The degree of acute lung injury and expression of pentraxin 3 in the lung were significantly reduced in the HTS + VPA group.

CONCLUSION

This is the first study to show that VPA and HTS can work synergistically to attenuate inflammation and improve survival in a lethal two-hit model.

Histone deacetylase inhibitor suberoylanilide hydroxamic acid attenuates Toll-like receptor 4 signaling in lipopolysaccharide-stimulated mouse macrophages

OBJECTIVE

We have previously demonstrated that pretreatment and posttreatment of animals with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, can improve survival in a mouse model of lipopolysaccharide (LPS)-induced severe shock. This study was designed to assess whether SAHA affects LPS/Toll-like receptor 4 signaling through acetylation of heat shock protein 90 (HSP90) and degradation of its client protein interleukin-1 receptor-associated kinase 1 (IRAK1).

METHODS

RAW264.7 cells were exposed to LPS (1 μg/mL) for 2 h, followed by treatment with SAHA (10 μM) or geldanamycin (3 μM), an inhibitor of HSP90. Sham (no SAHA, no LPS) macrophages served as a control. The cells were harvested at different time points, and time zero served as the reference point.

RESULTS

LPS dramatically increased protein expression of myeloid differentiation factor 88 and IRAK1, and stimulated nuclear translocation of nuclear factor κB, leading to an increases of gene expression and protein production of tumor necrosis factor α and interleukin-6. Treatment with SAHA significantly attenuated these LPS-stimulated alterations. LPS or SAHA did not change the levels of HSP90 protein, but immunoprecipitation studies demonstrated that SAHA treatment enhanced acetylation of HSP90, and increased the dissociation of IRAK1, compared to the LPS control.

CONCLUSIONS

SAHA suppresses LPS/Toll-like receptor 4 signaling in LPS-stimulated macrophages through multiple potential mechanisms. It inhibits the function of HSP90 through hyperacetylation of the chaperone protein, which results in dissociation and degradation of the client protein IRAK1 and, at least in part, leads to a decrease in nuclear translocation of nuclear factor κB and attenuation of key proinflammatory cytokine expression.

Translational barriers and opportunities for emergency preservation and resuscitation in severe injuries

BACKGROUND

Hypothermia is commonly used for organ and tissue preservation in multiple clinical settings, but its role in the management of injured patients remains controversial. There is no doubt that temperature modulation is a powerful tool, and hypothermia has been shown to protect cells during ischaemia and reperfusion, decrease organ damage and improve survival. Yet hypothermia is a double-edged sword: unless carefully managed, its induction can be associated with a number of complications.

METHODS

A literature review was performed to include important papers that address the impact of hypothermia on key biological processes, and explore the potential therapeutic role of hypothermia in trauma/haemorrhage models.

RESULTS

No clinical studies have been conducted to test the therapeutic benefits of hypothermia in injured patients. However, numerous well designed animal studies support this concept. Despite excellent preclinical data, there are several potential barriers to translating hypothermia into clinical practice.

CONCLUSION

Therapeutic hypothermia is a promising life-saving strategy. Appropriate patient selection requires a thorough understanding of how temperature modulation affects various biological mechanisms.

Anti-inflammatory properties of histone deacetylase inhibitors: a mechanistic study

BACKGROUND

We have demonstrated that postshock administration of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, can significantly improve early survival in a highly lethal model of hemorrhagic shock. As the primary insult in hemorrhagic shock is cellular hypoxia, and transcription factor hypoxia-inducible factor-1α (HIF-1α) controls proinflammatory gene expression in macrophages, we hypothesized that SAHA would attenuate the HIF-1α associated proinflammatory pathway in a hypoxic macrophage model.

METHODS

Mouse macrophages were exposed to hypoxic conditions (0.5% O2, 10% CO2, and 89.5% N2) at 37°C in the presence or absence of SAHA (10 μmol/L). The cells and culture medium were harvested at 1 hour, 4 hours, and 8 hours. Sham (no hypoxia, no SAHA) served as a control. Western blots were performed to assess protein levels of prolyl hydroxylase 2 (PHD2), HIF-1α, and inducible nitric oxide synthase (iNOS) in the cells. Colorimetric biochemical assay and enzyme-linked immunosorbent assay were used to analyze the release of nitric oxide (NO) and secretion of tumor necrosis factor α (TNF-α), respectively, in the cell culture medium.

RESULTS

Hypoxia significantly increased cellular level of HIF-1α (1 hour and 4 hours), gene transcription of iNOS (4 hours and 8 hours), iNOS protein (8 hours), NO production (8 hours), and TNF-α secretion (4 hours and 8 hours). SAHA treatment attenuated all of the above hypoxia-induced alterations in the macrophages. In addition, SAHA treatment significantly increased cellular level of PHD2, one of the upstream negative regulators of HIF-1α, at 1 hour.

CONCLUSIONS

Treatment with SAHA attenuates hypoxia-HIF-1α-inflammatory pathway in macrophages and suppresses hypoxia-induced release of proinflammatory NO and TNF-α. SAHA also causes an early increase in cellular PHD2, which provides, at least in part, a new explanation for the decrease in the HIF-1α protein levels.

Histone deacetylase inhibitors enhance endothelial cell sprouting angiogenesis in vitro

BACKGROUND

Treatment with histone deacetylases inhibitors (HDACi) such as valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA) has been shown to improve survival after lethal insults through mechanisms that are incompletely understood. Cell survival under adverse conditions requires a healthy network of capillaries to ensure adequate oxygen delivery. Angiogenic activation of endothelial cells to migrate and form sprouts is associated with characteristic changes in gene expression profiles. Because HDACi can modulate expression of various genes involved in angiogenic activity, we investigated the effect of these agents on capillary-like sprout formation in this study.

METHODS

Human umbilical vein endothelial cells (HUVECs) were cultured as multicellular spheroids within a type I collagen matrix, which promotes formation of sprouts resembling angiogenesis in vitro. HUVECs were cultured as multicellular spheroids within a type I collagen matrix, which promotes formation of sprouts (in vitro angiogenesis). Cells were cultured under the following conditions: Control (no growth factors); VPA (1 mmol/L); vascular endothelial growth factor (VEGF; 10 ng/mL); VPA + VEGF; SAHA (5 mmol/L), and SAHA + VEGF. After 24 hours of treatment, the length of spheroid sprouting and cell migration was assessed quantitatively. The levels of acetylated histone H3, phosphor-extracellular signal-regulated kinase (ERK)1/2, and β-catenin in HUVECs were measured by Western blotting at 6 hours after treatment.

RESULTS

High levels of acetylated histone H3 were detected in VPA and SAHA treated-groups. Compared with the VEGF-alone treated group (2379 ± 147.1 μm), the spheroid sprouting was 1.7 times increased with VPA and VEGF combined treatment (3996 ± 192.5 μm; P < .01). Cell migrations did not show a significant difference after addition of VPA, whereas SAHA suppressed migration. Expression of β-catenin was significantly increased by VPA and SAHA treatments. Addition of VPA greatly enhanced expression of phosphor-ERK1/2.

CONCLUSION

Exposure of HUVECs to VPA and SAHA increased the expression of β-catenin and enhanced spheroid sprout formation in vitro. Modulation of HDAC-dependent pathways may offer a novel approach to alter angiogenic processes and provide a useful therapeutic target.

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.