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

SelSA-1, a novel HDAC inhibitor demonstrates enhanced chemotherapeutic potential by redox modulation

Colorectal cancer (CRC) is a multistep disorder resulting from genetic and epigenetic genome changes. It is the third most common malignancy in developed nations accounting for roughly 600,000 deaths annually. Persistent gut inflammation, as observed in inflammatory bowel disease (IBD), is a key risk factor for CRC development. From an epigenetic viewpoint, the pharmacological inhibition of HDACs using HDAC inhibitors such as SAHA has emerged as a suitable anticancer strategy in the recent past. However, the clinical success of these strategies is limited and has risk factors associated with their uses. Thus, considering the critical involvement of epigenetic regulation of key molecular mechanisms in carcinogenesis as well as HDAC inhibitory and anti-tumorigenic properties of Selenium (Se), we aimed to explore the potentially safer and enhanced chemotherapeutic potential of a Se derivative of SAHA namely SelSA-1, in an experimental model of colitis-associated experimental cancer (CAC) model and mechanism involved therein. The in vitro study indicated improved efficiency, specificity, and better safety margin in terms of lower IC50 value of SelSA-1 than SAHA in both NIH3T3 (9.44 and 10.87 µM) and HCT 115 (5.70 and 7.49 µM) cell lines as well on primary colonocytes (5.61 and 6.30 µM) respectively. In an in vivo experimental model, SelSA-1 efficiently demonstrated amelioration of the multiple plaque lesions (MPLs), tumor burden/incidence, and modulation of various histological and morphological parameters. Further, redox-mediated alterations in apoptotic mediators suggested induction of cancer cell apoptosis by SelSA-1. These findings indicate the enhanced chemotherapeutic and pro-resolution effects of SelSA-1 in part mediated through redox modulation of multiple epigenetic and apoptotic pathways.

Selenium-Based Novel Epigenetic Regulators Offer Effective Chemotherapeutic Alternative with Wider Safety Margins in Experimental Colorectal Cancer

Colorectal cancer (CRC) is a major cause of morbidity and mortality worldwide. Despite the critical involvement of epigenetic modifications in CRC, the studies on the chemotherapeutic efficacy of various epigenetic regulators remain limited. Considering the key roles of histone deacetylases (HDACs) in the regulation of diverse cellular processes, several HDAC inhibitors are implied as effective therapeutic strategies. In this context, suberoylanilide hydroxamic acid (SAHA), a 2^nd-generation HDAC inhibitor, showed limited efficacy in solid tumors. Also, side effects associated with SAHA limit its clinical application. Based on the redox-modulatory and HDAC inhbitiory activities of essential trace element selenium (Se), the anti-carcinogenic potential of Se substituted SAHA, namely, SelSA-1 (25 mg kg^-1), was screened for it enhanced anti-tumorigenic role and wider safety profiles in DMH-induced CRC in Balb/c mice. A multipronged approach such as in silico, biochemical, and pharmacokinetics (PK) has been used to screen, characterize, and evaluate these novel compounds in comparison to existing HDAC inhibitor SAHA. This is the first in vivo study indicating the chemotherapeutic potential of Se-based novel epigenetic regulators such as SelSA-1 in any in vivo experimental model of carcinogenesis. Pharmcological and toxicity data indicated better safety margins, bioavailability, tolerance, and elimination rate of SelSA-1 compared to classical HDAC inhibitor SAHA. Further, histological and morphological evidence demonstrated enhanced chemotherapeutic potential of SelSA-1 even at lower pharmacological doses than SAHA. This is the first in vivo study suggesting Se-based novel epigenetic regulators as potential chemotherapeutic alternatives with wider safety margins and enhanced anticancer activities.

HPA Axis in the Pathomechanism of Depression and Schizophrenia: New Therapeutic Strategies Based on Its Participation

The hypothalamic-pituitary-adrenal (HPA) axis is involved in the pathophysiology of many neuropsychiatric disorders. Increased HPA axis activity can be observed during chronic stress, which plays a key role in the pathophysiology of depression. Overactivity of the HPA axis occurs in major depressive disorder (MDD), leading to cognitive dysfunction and reduced mood. There is also a correlation between the HPA axis activation and gut microbiota, which has a significant impact on the development of MDD. It is believed that the gut microbiota can influence the HPA axis function through the activity of cytokines, prostaglandins, or bacterial antigens of various microbial species. The activity of the HPA axis in schizophrenia varies and depends mainly on the severity of the disease. This review summarizes the involvement of the HPA axis in the pathogenesis of neuropsychiatric disorders, focusing on major depression and schizophrenia, and highlights a possible correlation between these conditions. Although many effective antidepressants are available, a large proportion of patients do not respond to initial treatment. This review also discusses new therapeutic strategies that affect the HPA axis, such as glucocorticoid receptor (GR) antagonists, vasopressin V1B receptor antagonists and non-psychoactive CB1 receptor agonists in depression and/or schizophrenia.

Transfusion Strategies are Associated with Epigenetic Changes Following Blunt Trauma

INTRODUCTION

Epigenetics has been identified in multiple diseases. The effect of transfusion strategy on epigenetics is unknown. We hypothesized that expression of epigenetic regulating genes would be associated with resuscitation strategy following blunt trauma.

METHODS

Retrospective study using the inflammation in host response to injury (glue grant) dataset. Volume transfused over 24 h of packed red blood cells (PRBC), fresh frozen plasma (FFP), platelets (PLT) as well as crystalloids was extracted along with leucocyte microarray data of genes with known epigenetic modulating activity from day 1 after injury.Principal component analysis (PCA) was used to identify principal components (PC) within the transcriptomic dataset. Multiple regression associated these with volume of blood products and crystalloids while controlling for confounders. Genes co-expressed with genes central genes in the identified PCs were furthermore subjected to pathway analysis using the reactome database.

RESULTS

PCA identified seven components. PRBC and crystalloid volumes were positively associated with PC1, implicating histone acetylation (HAT1), DNA and histone methylation (KDM6B, SET1DB) and histone phosphorylation (RPS6KA5). Conversely, PLT volume was negatively associated with PC1,5 and 6, implicating DNA methylation (DNMT1) as well as histone acetylation (HAT1) and phosphorylation (RPSKA3).FFP was negatively associated with PC3, implicating histone methylation (SETD1B) and phosphorylation (RPS6KA5).Co-expression network analysis identified downstream pathways relevant to inflammation and the innate immune response, including Toll-like receptor, interleukin and mitogen activated protein kinase activation.

CONCLUSIONS

Resuscitation strategy was associated with epigenetic transcriptomic alterations, especially for PRBC and PLT transfusions. Downstream effects may include pertubations of pathways involved in immune signaling and cellular survival.

Tubastatin A prevents hemorrhage-induced endothelial barrier dysfunction

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

From amino acids polymers, antimicrobial peptides, and histones, to their possible role in the pathogenesis of septic shock: a historical perspective

This paper describes the evolution of our understanding of the biological role played by synthetic and natural antimicrobial cationic peptides and by the highly basic nuclear histones as modulators of infection, postinfectious sequelae, trauma, and coagulation phenomena. The authors discuss the effects of the synthetic polymers of basic poly α amino acids, poly l-lysine, and poly l-arginine on blood coagulation, fibrinolysis, bacterial killing, and blood vessels; the properties of natural and synthetic antimicrobial cationic peptides as potential replacements or adjuncts to antibiotics; polycations as opsonizing agents promoting endocytosis/phagocytosis; polycations and muramidases as activators of autolytic wall enzymes in bacteria, causing bacteriolysis and tissue damage; and polycations and nuclear histones as potential virulence factors and as markers of sepsis, septic shock, disseminated intravasclar coagulopathy, acute lung injury, pancreatitis, trauma, and other additional clinical disorders.

Treatment of cardiovascular pathology with epigenetically active agents: Focus on natural and synthetic inhibitors of DNA methylation and histone deacetylation

Cardiovascular disease (CVD) retains a leadership as a major cause of human death worldwide. Although a substantial progress was attained in the development of cardioprotective and vasculoprotective drugs, a search for new efficient therapeutic strategies and promising targets is under way. Modulation of epigenetic CVD mechanisms through administration epigenetically active agents is one of such new approaches. Epigenetic mechanisms involve heritable changes in gene expression that are not linked to the alteration of DNA sequence. Pathogenesis of CVDs is associated with global genome-wide changes in DNA methylation and histone modifications. Epigenetically active compounds that influence activity of epigenetic modulators such as DNA methyltransferases (DNMTs), histone acetyltransferases, histone deacetylases (HDACs), etc. may correct these pathogenic changes in the epigenome and therefore be used for CVD therapy. To date, many epigenetically active natural substances (such as polyphenols and flavonoids) and synthetic compounds such as DNMT inhibitors or HDAC inhibitors are known. Both native and chemical DNMT and HDAC inhibitors possess a wide range of cytoprotective activities such as anti-inflammatory, antioxidant, anti-apoptotic, anti-anfibrotic, and anti-hypertrophic properties, which are beneficial of treatment of a variety of CVDs. However, so far, only synthetic DNMT inhibitors enter clinical trials while synthetic HDAC inhibitors are still under evaluation in preclinical studies. In this review, we consider epigenetic mechanisms such as DNA methylation and histone modifications in cardiovascular pathology and the epigenetics-based therapeutic approaches focused on the implementation of DNMT and HDAC inhibitors.

Effectiveness of Periodic Treatment of Quercetin against Influenza A Virus H1N1 through Modulation of Protein Expression

Kimchi, a traditional fermented food regularly consumed in Korea, contains various types of antimicrobial compounds. Among the tested compounds present in common spices used in Kimchi, quercetin showed the highest selectivity index against influenza A virus (IAV) H1N1. In this study, the effect of pretreatment and periodic treatment with quercetin against IAV in Madin-Darby canine kidney cells was observed. Compared to pretreatment, periodic treatment resulted in significantly higher cell viability but lower relative expression of the IAV PA gene and total apoptosis and cell death. To explain the mechanisms underlying the antiviral effects of quercetin treatment, a comparative proteomic analysis was performed in four samples (mock, quercetin-treated, IAV-infected, and quercetin-treated IAV-infected). Among the 220 proteins, 56 proteins were classified nonhierarchically into three clusters and were differentially modulated by quercetin treatment in IAV-infected cells. Post-translational modifications were identified in 68 proteins. In conclusion, periodic treatment with quercetin is effective in reducing IAV infection, and differentially regulates the expression of key proteins, including heat shock proteins, fibronectin 1, and prohibitin to reduce IAV replication.

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.

Inhibition of histone deacetylase 6 improves long-term survival in a lethal septic model

BACKGROUND

We recently demonstrated that suberoylanilide hydroxamic acid, a broad-spectrum histone deacetylase (HDAC) inhibitor that inhibits HDACs 1, 2, 3, and 6, improves survival in a mouse model of cecal ligation and puncture (CLP)-induced lethal sepsis. The current study was undertaken to determine the effect of selective inhibition of HDAC isoform on survival, key cytokine production, organ injury, bacteria clearance, and cell apoptosis.

METHODS

In Experiment 1, C57BL/6J mice were subjected to CLP and, 1 hour later, given intraperitoneal injections of (1) Tubastatin A (inhibitor of HDAC6) dissolved in dimethyl sulfoxide (DMSO), (2) MS-275 (inhibitor of HDACs 1, 2, and 3) in DMSO, and (3) DMSO only. Survival was monitored for 10 days. In Experiment 2, 1 hour after CLP, animals were treated with DMSO vehicle or Tubastatin A. Sham-operated animals served as control. Peritoneal fluid and blood samples were collected for measurement of cytokines at 24 hours or 48 hours. Blood at 48 hours was also used to determine bacteria load. Liver was harvested to evaluate acute liver injury. In Experiment 3, Primary splenocytes were used to assess cytokine responses and phagocytosis. Macrophages were cultured and harvested 3 hours and 6 hours after lipopolysaccharide stimulation in the absence or presence of Tubastatin A to analyze cell apoptosis.

RESULTS

Animals treated with Tubastatin A, but not MS-275, displayed a significant improvement in survival. Moreover, Tubastatin A significantly inhibited cytokine production in peritoneal fluid and plasma as well as in supernatant from splenocytes stimulated with lipopolysaccharide. Tubastatin A significantly attenuated acute liver injury, increased blood bacteria clearance and splenocyte phagocytosis, and decreased macrophage apoptosis.

CONCLUSION

HDAC6 inhibition significantly improves survival, reduces "cytokine storm," attenuates acute livery injury, increases bacteria clearance and immune cell phagocytosis, and inhibits macrophage apoptosis in a lethal mouse CLP model.

Histone deacetylase inhibitor-temozolomide co-treatment inhibits melanoma growth through suppression of Chemokine (C-C motif) ligand 2-driven signals

Target-specific agents used in melanoma are not curative, and chemokines are being implicated in drug-resistance to target-specific agents. Thus, the use of conventional agents in rationale combinations may result in optimization of therapy. Because histone deacetylases participate in tumor development and progression, the combination of the pan-inhibitor SAHA and temozolomide might provide a therapeutic advantage. Here, we show synergism between the two drugs in mutant BRAF cell lines, in association with decreased phosphorylation of cell survival proteins (e.g., C-Jun-N-terminal-kinase, JNK). In the spontaneous ret transgenic mouse melanoma model, combination therapy produced a significant disease onset delay and down-regulation of Chemokine (C-C motif) ligand 2 (CCL2), JNK, and of Myeloid-derived suppressor cell recruitment. Co-incubation with a CCL2-blocking-antibody enhanced in vitro cell sensitivity to temozolomide. Conversely, recombinant CCL2 activated JNK in human tumor melanoma cells. In keeping with these results, the combination of a JNK-inhibitor with temozolomide was synergistic. By showing that down-regulation of CCL2-driven signals by SAHA and temozolomide via JNK contributes to reduce melanoma growth, we provide a rationale for the therapeutic advantage of the drug combination. This combination strategy may be effective because of interference both with tumor cell and tumor microenvironment.

Effects of aminoguanidine, a potent nitric oxide synthase inhibitor, on myocardial and organ structure in a rat model of hemorrhagic shock

Background:

Nitric oxide (NO) has been shown to increase following hemorrhagic shock (HS). Peroxynitrite is produced by the reaction of NO with reactive oxygen species, leads to nitrosative stress mediated organ injury. We examined the protective effects of a potent inhibitor of NO synthase, aminoguanidine (AG), on myocardial and multiple organ structure in a rat model of HS.

Materials and Methods:

Male Sprague Dawley rats (300-350 g) were assigned to 3 experimental groups (n = 6 per group): (1) Normotensive rats (N), (2) HS rats and (3) HS rats treated with AG (HS-AG). Rats were hemorrhaged over 60 min to reach a mean arterial blood pressure of 40 mmHg. Rats were treated with 1 ml of 60 mg/kg AG intra-arterially after 60 min HS. Resuscitation was performed in vivo by the reinfusion of the shed blood for 30 min to restore normo-tension. Biopsy samples were taken for light and electron microscopy.

Results:

Histological examination of hemorrhagic shocked untreated rats revealed structural damage. Less histological damage was observed in multiple organs in AG-treated rats. AG-treatment decreased the number of inflammatory cells and mitochondrial swollen in myocardial cells.

Conclusion:

AG treatment reduced microscopic damage and injury in multiple organs in a HS model in rats.

Histone deacetylase inhibitor treatment attenuates coagulation imbalance in a lethal murine model of sepsis

BACKGROUND

Sepsis has a profound impact on the inflammatory and hemostatic systems. In addition to systemic inflammation, it can produce disseminated intravascular coagulation, microvascular thrombosis, consumptive coagulopathy, and multiple organ failure. We have shown that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDACI), improves survival in a lethal model of cecal ligation and puncture (CLP) in mice, but its effect on coagulation remains unknown. The goal of this study was to quantify the impact of SAHA treatment on coagulopathy in sepsis.

METHODS

C57BL/6J mice were subjected to CLP, and 1 hour later given intraperitoneally either SAHA dissolved in dimethyl sulfoxide (DMSO) or DMSO only. Sham-operated animals were handled in similar manner without CLP. Blood samples were collected by cardiac puncture and evaluated using the TEG 5000 Thrombelastograph Hemostasis Analyzer System.

RESULTS

Compared with the sham group, all animals in DMSO vehicle group died within 72 hours, and developed coagulopathy that manifested as prolonged initial fibrin formation and fibrin cross-linkage time, and decreased clot formation speed, platelet function, and clot rigidity. SAHA treatment significantly improved survival and was associated with improvement in fibrin cross-linkage and clot formation, as well as platelet function and clot rigidity, without a significant impact on the clot initiation parameters.

CONCLUSION

SAHA treatment enhances survival and attenuates sepsis-associated coagulopathy by improving fibrin cross-linkage, rate of clot formation, platelet function, and clot strength. HDACI may represent a novel therapeutic strategy for correcting sepsis-associated coagulopathy.

Citrullinated histone H3: a novel target for the treatment of sepsis

INTRODUCTION

We have recently demonstrated that in a rodent model of lipopolysaccharide (LPS)-induced shock, an increase in circulating citrullinated histone H3 (Cit H3) is associated with lethality of sepsis, and treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor (HDACI), significantly improves survival. However, the role of Cit H3 in pathogenesis and therapeutics of sepsis are largely unknown. The present study was designed to test whether treatment with HDACI could inhibit cellular Cit H3 production, and inhibition of peptidylarginine deiminase (PAD, an enzyme producing Cit H3) with Cl-amidine (PAD inhibitor) or neutralization of blood Cit H3 with anti-Cit H3 antibody could improve survival in a clinically relevant mouse model of cecal ligation and puncture (CLP)-induced septic shock.

METHODS

Three experiments were carried out. In experiment I, HL-60 neutrophilic cells grown on a coverslip were treated with LPS (100 ng/mL) in the presence or absence of SAHA (5 μmol) for 3 hours, and subjected to immunostaining with anti-Cit H3 antibody to assess effect of SAHA on Cit H3 production under a fluorescence microscope. The ratio of Cit H3 positive cells was calculated as mean values ± SD (n = 3). In experiment II, male C57BL/6J mice were subjected to CLP, and 1 hour later randomly divided into 2 groups for intraperitoneal injection as follows: (1) Dimethyl sulfoxide (DMSO), (2) SAHA (50 mg/kg) in DMSO, and (3) Cl-amidine (80 mg/kg) in DMSO (n = 10/group). In experiment III, male C57BL/6J mice were divided into control and treatment groups, and subjected to CLP. Two hours later, immunoglobulin (Ig)G and Cit H3 antibody (20 mg/kg IV; n = 5/group) were injected into the control and treatment groups, respectively. Survival was monitored for ≤10 days.

RESULTS

In experiment I, LPS induced Cit H3 production in the HL-60 cells, and SAHA treatment inhibited H3 citrullination significantly (P < .05). In experiment II, all vehicle-injected mice died within 3 days with increased circulating Cit H3 levels, whereas treatment with HDACI or Cl-amidine notably improved long-term survival (P < .01). In experiment III, administration of IgG did not improve survival, but a single treatment with Cit H3 specific antibody significantly improved survival (P < .014).

CONCLUSION

Inhibition of HDAC or PAD significantly suppresses Cit H3 production in vitro and improves survival in vivo. Neutralization of Cit H3 significantly improves survival in septic mice. Collectively, our findings indicate for the first time that Cit H3 could not only serve as a potential biomarker, but also a novel therapeutic target in sepsis.

Valproate ameliorates thioacetamide-induced fibrosis by hepatic stellate cell inactivation

Valproic acid (VPA) has been reported as inhibitor of histone deacetylases (HDACs). Several reports indicated that HDACs play a crucial role in the pathogenesis of fibrosis and hepatic stellate cell (HSC) activation. The present study was aimed to evaluate the anti-fibrotic effect of VPA against thioacetamide (TAA)-induced hepatic fibrosis and activation of the HSC in rat. VPA and TAA were administrated intraperitoneally at the dose of 400 and 200 mg/kg each at 2 days interval, respectively for a period of 6 weeks. Administration of TAA significantly increased the absolute and relative liver weight, aspartate aminotransferase and alanine aminotransferase levels, which were significantly decreased by VPA treatment as compared to TAA control. VPA treatment prevents the TAA-induced activation of HSC and decreases collagen deposition and infiltration of inflammatory cells as revealed by Sirius red and H&E staining. Interestingly, VPA co-treatment led to significantly increase the DNA damage and apoptosis in the activated HSC as compared to TAA control. Further, TAA decreased the expression of matrix metalloproteinase-2 (MMP-2), while VPA co-treatment significantly increased the expression of MMP-2 as compared to respective control. The present study clearly demonstrated that VPA treatment significantly alleviates TAA-induced activation of HSC and subsequent hepatic fibrosis.

Sodium valproate, a histone deacetylase inhibitor ameliorates cyclophosphamide-induced genotoxicity and cytotoxicity in the colon of mice

Abstract Background: Cyclophosphamide (CP) is an alkylating anticancer drug used for the treatment of various cancer and noncancer disorders. Toxicity of CP is well characterized using different test systems. However, its intestinal genotoxicity and cytotoxicity are the least explored and the mechanism is not fully investigated. Valproic acid (VPA) has been reported as a histone deacetylase (HDAC) inhibitor, which modulates the cytotoxicity of anticancer drugs. The present study aimed to investigate the influence of VPA on CP-induced genotoxicity and cytotoxicity in the colon of mice. Methods: In the 16-day experiment, animals were treated with VPA alone (500 mg/kg/day), CP alone (50 mg/kg, on the 4th, 8th, 12th, and 16th days), and the combination of CP and VPA, while in the 28-day experiment, animals were treated with VPA alone (300 mg/kg/day, 5 days/week), CP alone (100 mg/kg/week), and the combination of low and high dose of VPA (VPA150+CP and VPA300+CP). Animals were sacrificed 24 h after the administration of the last dose. The influence of VPA treatment on CP-induced genotoxicity and cytotoxicity was assessed by the evaluation of oxidative stress, DNA damage, histology, and the expression of 8-hydroxy-guanosine and phosphorylated histone H2AX by immunohistochemistry. Results and conclusions: The present study's results demonstrated that VPA treatment significantly decreased the CP-induced DNA damage, cytotoxicity, and expression of γH2AX in the colon as revealed by the comet assay and histological as well as immunohistochemical evaluation. VPA treatment significantly ameliorated the CP-induced DNA damage and cytotoxicity in the colon of mice.

Novel pharmacologic treatment attenuates septic shock and improves long-term survival

BACKGROUND

We have demonstrated previously that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in a lipopolysaccharide-induced lethal model of endotoxemia. The goal of this study was to investigate the impact of SAHA on survival in a more clinically relevant model of cecal ligation and puncture (CLP)-induced septic shock and to elucidate changes in cytokine responses and organ injury.

METHODS

C57BL/6J mice were subjected to CLP, and 1 hour later were given intraperitoneally either SAHA dissolved in dimethyl sulfoxide or dimethyl sulfoxide only. Survival was monitored for 10 days. In a second study, livers were harvested for evaluation of acute liver injury, and peritoneal fluid and blood samples were collected for cytokine assays. In addition, RAW264.7 and bone marrow-derived macrophages were used to assess effects of SAHA on cytokine responses.

RESULTS

SAHA-treated animals displayed a substantial improvement in survival. In addition, SAHA also attenuated cytokine levels in blood and peritoneal fluid compared with vehicle animals, as well as in culture supernatant of macrophages stimulated with bacterial components (lipopolysaccharide or Pam3CSK4). Moreover, SAHA-treated animals showed a substantial decrease in acute liver injury.

CONCLUSION

SAHA treatment improves survival, decreases "cytokine storm," and prevents distant organ damage in a lethal septic model.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Vorinostat, a HDAC inhibitor, showed anti-osteoarthritic activities through inhibition of iNOS and MMP expression, p38 and ERK phosphorylation and blocking NF-κB nuclear translocation

Overproduction of nitric oxide (NO) and matrix metalloproteinases (MMPs) plays an important role in the pathogenesis of osteoarthritis (OA). In present study, we investigated whether vorinostat can inhibit the catabolic effects of IL-1β in vitro, especially the inhibition of MMPs and inducible nitric oxide synthase (iNOS) through the attenuation of nuclear factor kappa-B (NF-κB) and mitogen activated protein kinase (MAPK) pathways in human chondrocytes. Human OA chondrocytes were either left untreated or treated with various concentrations of vorinostat followed by incubation with IL-1β (5ng/mL). Effects of vorinostat on IL-1β-induced gene and protein expression of iNOS, MMP-1, MMP-13 and tissue inhibitors of metalloproteinase-1 (TIMP-1) were verified by quantitative real time-PCR and Western blot analysis. Production of NO, MMP-1, MMP-13 and TIMP-1 released in culture supernatant was estimated using commercially available kits. The roles of NF-κB and MAPK pathways in the regulation of targeted genes and the mechanism involved in vorinostat mediated modulation of these genes were determined by Western blot using specific antibodies. We found that vorinostat down-regulated iNOS, MMP-1 and MMP-13 expression and up-regulated TIMP-1 expression in human OA chondrocytes. In addition, the release of NO, MMP-1 and MMP-13 secreted from IL-1β stimulated chondrocytes was also suppressed by vorinostat. Interestingly, vorinostat selectively inhibited IL-1β-induced p38 and ERK1/2 activation without affecting JNK activation. Furthermore, we observed that vorinostat inhibited NF-κB pathway by suppressing the degradation of I-κBα and attenuating NF-κB p65 translocation to the nucleus. These results suggest that vorinostat may be a promising therapeutic agent for the prevention and treatment of OA.