Protective effect of suberoylanilide hydroxamic acid against LPS-induced septic shock in rodents

Identification of citrullinated histone H3 as a potential serum protein biomarker in a lethal model of lipopolysaccharide-induced shock

BACKGROUND

Circulating proteins may serve as biomarkers for the early diagnosis and treatment of shock. We have recently demonstrated that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, significantly improves survival in a rodent model of lipopolysaccharide (LPS)-induced septic shock. Preliminary proteomic data showed that LPS-induced shock altered a number of proteins in circulation, including histone H3 (H3) and citrullinated histone H3 (Cit H3). The present study was designed to confirm these findings and to test whether the pro-survival phenotype could be detected by an early alteration in serum biomarkers.

METHODS

Three experiments were performed. In experiment I, Western blotting was performed on serum samples from male C57B1/6J mice (n = 9, 3/group) that belonged to the following groups: (a) LPS (20 mg/kg)-induced septic shock, (b) SAHA-treated septic shock, and (c) sham (no LPS, no SAHA). In experiment II, HL-60 granulocytes were cultured and treated with LPS (100 ng/m1) in the absence or presence of SAHA (10 μmol/L). Sham (no LPS, no SAHA) granulocytes served as controls. The medium and cells were harvested at 3 hours, and proteins were measured with Western blots. In experiment III, a large dose (LD, 35 mg/kg) or small dose (SD, 10 mg/kg) of LPS was injected intraperitoneally into the C57B1/6J mice (n = 10 per group). Blood was collected at 3 hours, and serum proteins were determined by Western blots or enzyme-linked immunosorbent assay (ELISA). All of the Western blots were performed with antibodies against H3, Cit H3, and acetylated H3 (Ac H3). ELISA was performed with antibody against tumor necrosis factor (TNF)-α. Survival rates were recorded over 7 days.

RESULTS

In experiment I, intraperitoneal (IP) injection of LPS (20 mg/kg) significantly increased serum levels of H3, which was prevented by SAHA treatment. In experiment II, LPS (100 ng/mL) induced expression and secretion of Cit H3 and H3 proteins in neutrophilic HL-60 cells, which was decreased by SAHA treatment. In experiment III, administration of LPS (LD) caused a rise in serum H3 and Cit H3 but not Ac H3 at 3 hours, and all of these animals died within 23 hours (100% mortality). Decreasing the dose of LPS (SD) significantly reduced the mortality rate (10% mortality) as well as the circulating levels of Cit H3 (non detectable) and H3. An increase in serum TNF-α was found in both LPS (LD) and (SD) groups, but in a non-dose-dependent fashion.

CONCLUSION

Our results reveal for the first time that Cit H3 is released into circulation during the early stages of LPS-induced shock. Moreover, serum levels of Cit H3 are significantly associated with severity of LPS-induced shock. Therefore, Cit H3 could serve as a potential protein biomarker for early diagnosis of septic shock, and for predicting its lethality.

The effect of valproic acid in alleviating early death in burn shock

The aim of this study was to examine whether administration of valproic acid (VPA) improves blood circulation and survival after lethal burn shock. Forty adult male Beagle dogs underwent a 50% TBSA full-thickness flame injury. In the first 24 h after burn, animals were randomly divided into four groups: NR group received no treatment. VPA group and 2M2P(2-methyl-2-pentenoic acid) group received either VPA or 2M2P (100 mg of the either drug in 20 mL of normal saline) intravenously. VR group received intravenous infusion of lactated Ringer's solution according to Parkland formula. In the second 24 h after burn the animals of all groups received delayed IV fluid resuscitation. Hemodynamic variables and biochemical parameters were determined with animals in the conscious and cooperative state. From 4 h after burn on, the levels of mean arterial pressure, cardiac index, plasma volume and intestinal mucosal blood perfusion in VPA group were significantly higher, and the levels of parameters of organ function and serum tumor necrosis factor-α were lower than those in NR group and 2M2P group (all P<0.05). Survival at 72 h after burn was in following order: VR (100%)>VPA (60%)>2M2P (30%)>NR (10%). Our results showed that histone deacetylace inhibitor (HDACI) valproic acid significantly improved hemodynamics, intestinal perfusion, and the survival rate after lethal burn shock. The mechanism may be attributable partly to the lowering of the level of proinflammatory factors, ameriolation of vasopermeability-induced visceral edema, reduction of blood volume loss, and protection of vital organs through inhibition of histone deacetylase activity of cell of vital organs.

HDAC inhibitor SAHA normalizes the levels of VLCFAs in human skin fibroblasts from X-ALD patients and downregulates the expression of proinflammatory cytokines in Abcd1/2-silenced mouse astrocytes

X-adrenoleukodystrophy (X-ALD) is a peroxisomal metabolic disorder caused by mutations in the ABCD1 gene encoding the peroxisomal ABC transporter adrenoleukodystrophy protein (ALDP). The consistent metabolic abnormality in all forms of X-ALD is an inherited defect in the peroxisomal β-oxidation of very long chain FAs (VLCFAs >C22:0) and the resultant pathognomic accumulation of VLCFA. The accumulation of VLCFA leads to a neuroinflammatory disease process associated with demyelination of the cerebral white matter. The present study underlines the importance of a potent histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA) in inducing the expression of ABCD2 [adrenoleukodystrophy-related protein (ALDRP)], and normalizing the peroxisomal β-oxidation, as well as the saturated and monounsaturated VLCFAs in cultured human skin fibroblasts of X-ALD patients. The expression of ELOVL1, the single elongase catalyzing the synthesis of both saturated VLCFA (C26:0) and monounsaturated VLCFA (C26:1), was also reduced by SAHA treatment. In addition, using Abcd1/Abcd2-silenced mouse primary astrocytes, we also examined the effects of SAHA in VLCFA-induced inflammatory response. SAHA treatment decreased the inflammatory response as expression of inducible nitric oxide synthase, inflammatory cytokine, and activation of NF-κB in Abcd1/Abcd2-silenced mouse primary astrocytes was reduced. These observations indicate that SAHA corrects both the metabolic disease of VLCFA as well as secondary inflammatory disease; therefore, it may be an ideal drug candidate to be tested for X-ALD therapy in humans.

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.

Histone deacetylase inhibitors attenuate acute lung injury during cecal ligation and puncture-induced polymicrobial sepsis

BACKGROUND

The histone deacetylase (HDAC) inhibitors have emerged as the useful reagents that epigenetically modulate the expression of various genes. In the present study, the effects of HDAC inhibitors on the expression of inflammation-related genes and lung injury during sepsis were investigated.

METHODS

Mice were pretreated with two structurally unrelated HDAC inhibitors, Trichostatin A (TSA) and sodium butyrate (SB). Thirty minutes later, mice underwent cecal ligation and puncture (CLP)-induced sepsis. Lung injury and the expression of inflammation-related molecules were determined. In addition, survival was assessed post-CLP.

RESULTS

Our results indicated that administration of TSA or SB alleviated sepsis-induced lung injury. This was accompanied by reduced neutrophil infiltration, decreased intercellular adhesion molecule-1 (ICAM-1) and E-selectin expression in lung tissue, and lower interleukin-6 (IL-6) level in plasma. In addition, treatment with HDAC inhibitors significantly prolonged the survival time of CLP mice.

CONCLUSIONS

These data indicated that the HDAC inhibitors, based on modulating the key enzymes linked to acetylation modification, effectively attenuate intrapulmonary inflammatory response, thus significantly alleviating lung injury during sepsis.

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

Histone deacetylases (HDACs) play a key role in homeostasis of protein acetylation in histone and nonhistone proteins and in regulating fundamental cellular activities. In this paper we review and discuss intriguing recent developments in the use of histone deacetylase inhibitors (HDACIs) to combat some critical conditions in an animal model of hemorrhagic and septic shock. HDACIs have neuroprotective, cardioprotective, renal-protective, and anti-inflammatory properties; survival improvements have been significantly shown in these models. We discuss the targets and mechanisms underlying these effects of HDACIs and comment on the potential new clinical applications for these agents in the future. This paper highlights the emerging roles of HDACIs as acetylation modulators in models of hemorrhagic and septic shock and explains some contradictions encountered in previous studies.

Rationale for HDAC inhibitor therapy in autoimmunity and transplantation

While there are currently more than 70 ongoing clinical trials of inhibitors of so-called classical HDACs (HDACi) as anticancer therapies, given their potency as antiproliferative and angiostatic agents, HDACi also have considerable therapeutic potential as anti-inflammatory and immunosuppressive drugs. The utility of HDACi as anti-inflammatory agents is dependent upon their proving safe and effective in experimental models. Current pan-HDACi compounds are not well suited to this role, given the broad distribution of target HDACs and their complex and multifaceted mechanisms of action. In contrast, the development of isoform-selective HDACi may provide important new tools for therapy in autoimmunity and transplantation. This chapter discusses which HDACs are worthwhile targets in inflammation and progress toward their therapeutic inhibition, including the use of HDAC subclass and isoform-selective HDACi to promote the functions of Foxp3+ T regulatory cells.

Advances in resuscitation strategies

Shock, regardless of etiology is characterized by decreased delivery of oxygen and nutrients to the tissues and our interventions are directed towards reversing the cellular ischemia and preventing its consequences. The treatment strategies that are most effective in achieving this goal obviously depend upon the different types of shock (hemorrhagic, septic, neurogenic and cardiogenic). This brief review focuses on the two leading etiologies of shock in the surgical patients: bleeding and sepsis, and addresses a number of new developments that have profoundly altered the treatment paradigms. The emphasis here is on new research that has dramatically altered our treatment strategies rather than the basic pathophysiology of shock.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Treatment with histone deacetylase inhibitor attenuates MAP kinase mediated liver injury in a lethal model of septic shock

BACKGROUND

Despite global efforts to improve the treatment of sepsis, it remains a leading cause of morbidity and mortality in intensive care units. We have previously shown that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, markedly improves survival in a murine model of lipopolysaccharide (LPS)-induced shock. SAHA has anti-inflammatory properties that have not been fully characterized. The liver plays an important role in the production of acute phase reactants involved in the inflammatory cascade and is also one of the major organs that can become dysfunctional in septic shock. The purpose of this study was to assess the effect of SAHA treatment on MAP kinases and associated inflammatory markers in murine liver after LPS-induced injury.

METHODS

C57B1/6J mice were randomly divided into three groups: (A) experimental-given intraperitoneal (i.p.) SAHA (50 mg/kg) in dimethyl sulfoxide (DMSO) vehicle solution (n = 12); (B) control- given vehicle only (n = 12), and; (C) sham-given no treatment (n = 7). Two hours later, experimental and control mice were injected with LPS (20 mg/kg, i.p.) and experimental mice received a second dose of SAHA. Livers were harvested at 3, 24, and 48 h for analysis of inflammatory markers using Western Blot, Polymerase Chain Reaction (PCR), and Enzyme-Linked Immunosorbent Assay (ELISA) techniques.

RESULTS

After 3 h, the livers of animals treated with SAHA showed significantly (P < 0.05) decreased expression of the pro-inflammatory MAP kinases phosphorylated p38, phosphorylated ERK, myeloperoxidase and interleukin-6, and increased levels of the anti-inflammatory interleukin-10 compared with controls. Phospho-p38 expression remained low in the SAHA treated groups at 24 and 48 h.

CONCLUSION

Administration of SAHA is associated with attenuation of MAPK activation and alteration of inflammatory and anti-inflammatory markers in murine liver after a lethal LPS insult. The suppression of MAPK activity is rapid (within 3 h), and is sustained for up to 48 h post-treatment. These results may in part account for the improvement in survival shown in this model.

Surviving lethal septic shock without fluid resuscitation in a rodent model

BACKGROUND

We have recently demonstrated that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, before a lethal dose of lipopolysaccharide (LPS) improves survival in mice. The purpose of the present study was to determine whether SAHA treatment would attenuate LPS-induced shock and improve survival when given postinsult in a rodent model.

METHODS

C57BL/6J mice were intraperitoneally (IP) injected with LPS (30 mg/kg), and 2 hours later randomized into 2 groups: (1) vehicle animals (n = 10) received dimethyl sulfoxide (DMSO) solution only; and (2) SAHA animals (n = 10) were given SAHA (50 mg/kg, IP) in DMSO solution. Survival was monitored over the next 7 days. In a second study, LPS-injected mice were treated with either DMSO or SAHA as described, and normal (sham) animals served as controls. Lungs were harvested at 4, 6, and 8 hours after LPS injection for analysis of gene expression. In addition, RAW264.7 mouse macrophages were cultured to assess the effects of SAHA post-treatment on LPS-induced inflammation using enzyme-linked immunosorbent assay.

RESULTS

All LPS-injected mice that received the vehicle agent alone died within 24 hours, whereas the SAHA-treated animals displayed a significant improvement in 1 week survival (80% vs 0%; P < .001). LPS insult significantly enhanced gene expression of MyD88, tumor necrosis factor (TNF)-alpha and interleukin (IL)-6, and was associated with an increased protein secretion of TNF-alpha and IL-6 into the cell culture medium. In contrast, SAHA treatment significantly attenuated all of these LPS-related alterations.

CONCLUSION

We report for the first time that administration of SAHA (50 mg/kg IP) after a lethal dose of LPS significantly improves long-term survival, and attenuates expression of the proinflammatory mediators TNF-alpha and IL-6. Furthermore, our data suggest that the anti-inflammatory effects of SAHA may be due to downregulation of the MyD88-dependent pathway, and decreased expression of associated proinflammatory genes.

Fluid resuscitation: past, present, and the future

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