Pharmacologic resuscitation decreases circulating cytokine-induced neutrophil chemoattractant-1 levels and attenuates hemorrhage-induced acute lung injury

The role of fatty acid metabolism in acute lung injury: a special focus on immunometabolism

Reputable evidence from multiple studies suggests that excessive and uncontrolled inflammation plays an indispensable role in mediating, amplifying, and protracting acute lung injury (ALI). Traditionally, immunity and energy metabolism are regarded as separate functions regulated by distinct mechanisms, but recently, more and more evidence show that immunity and energy metabolism exhibit a strong interaction which has given rise to an emerging field of immunometabolism. Mammalian lungs are organs with active fatty acid metabolism, however, during ALI, inflammation and oxidative stress lead to a series metabolic reprogramming such as impaired fatty acid oxidation, increased expression of proteins involved in fatty acid uptake and transport, enhanced synthesis of fatty acids, and accumulation of lipid droplets. In addition, obesity represents a significant risk factor for ALI/ARDS. Thus, we have further elucidated the mechanisms of obesity exacerbating ALI from the perspective of fatty acid metabolism. To sum up, this paper presents a systematical review of the relationship between extensive fatty acid metabolic pathways and acute lung injury and summarizes recent advances in understanding the involvement of fatty acid metabolism-related pathways in ALI. We hold an optimistic believe that targeting fatty acid metabolism pathway is a promising lung protection strategy, but the specific regulatory mechanisms are way too complex, necessitating further extensive and in-depth investigations in future studies.

Epigenetic regulation of pulmonary inflammation

Pulmonary disease such as chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis and pulmonary hypertension are the leading cause of deaths. More importantly, lung diseases are on the rise and environmental factors induced epigenetic modifications are major players on this increased prevalence. It has been reported that dysregulation of genes involved in epigenetic regulation such as the histone deacetylase (HDACs) and histone acetyltransferase (HATs) play important role in lung health and pulmonary disease pathogenesis. Inflammation is an essential component of respiratory diseases. Injury and inflammation trigger release of extracellular vesicles that can act as epigenetic modifiers through transfer of epigenetic regulators such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), proteins and lipids, from one cell to another. The immune dysregulations caused by the cargo contents are important contributors of respiratory disease pathogenesis. N6 methylation of RNA is also emerging to be a critical mechanism of epigenetic alteration and upregulation of immune responses to environmental stressors. Epigenetic changes such as DNA methylation are stable and often long term and cause onset of chronic lung conditions. These epigenetic pathways are also being utilized for therapeutic intervention in several lung conditions.

VALPROIC ACID INHIBITS CLASSICAL MONOCYTE-DERIVED TISSUE FACTOR AND ALLEVIATES HEMORRHAGIC SHOCK-INDUCED ACUTE LUNG INJURY IN RATS

ABSTRACT

Background: Monocytes and monocyte-derived tissue factor (TF) promote the development of sepsis-induced acute lung injury (ALI). Classical monocytes (C-Mcs) can be induced to express TF. Valproic acid (VPA) alleviates hemorrhagic shock (HS)-induced ALI (HS/ALI) and inhibits TF expression in monocytes. We hypothesized that C-Mcs and C-Mc-derived TF promoted HS/ALI and that VPA could inhibit C-Mc-derived TF expression and attenuate HS/ALI. Methods: Wistar rats and THP-1 cells were used to evaluate our hypothesis. Monocyte subtypes were analyzed by flow cytometry; mRNA expression was measured by fluorescence quantitative polymerase chain reaction; protein expression was measured by Western blotting, immunofluorescence, or immunohistology; inflammatory cytokines levels were measured by enzyme-linked immunosorbent assay; and ALI scores were used to determine the degree of ALI. Results: The blood %C-Mcs and C-Mcs/non-C-Mcs ratios, monocyte TF levels, serum and/or lung inflammatory cytokine levels, and ALI scores of HS rats were significantly increased ( P < 0.05). After monocyte depletion and thrombin inhibition, the inflammatory cytokine levels and ALI scores were significantly decreased ( P < 0.05). VPA reduced the %C-Mcs and C-Mc/non-C-Mc ratios, TF expression, inflammatory cytokine levels, and ALI scores during HS ( P < 0.05) and inhibited HS-induced monocyte Egr-1 and p-ERK1/2 expression ( P < 0.05). VPA inhibited hypoxia-induced TF expression in THP-1 cells by regulating the p-ERK1/2-Egr-1 axis. Conclusion: C-Mcs and C-Mc-derived TF accelerate the development of HS/ALI by increasing thrombin production. VPA inhibits HS-induced C-Mc production of TF by regulating the p-ERK1/2-Egr-1 axis and alleviates HS/ALI.

Histone deacetylase 2 inhibitor valproic acid attenuates bisphenol A-induced liver pathology in male mice

Accumulating evidence indicates the role of endocrine disruptor bisphenol A (BPA) in many pathological conditions. Histone deacetylase (HDAC) inhibition has potential for the treatment of many diseases/abnormalities. Using a mouse BPA exposure model, this study investigated the hepatoprotective effects of the Food and Drug Administration–approved HDAC2 inhibitor valproic acid (VPA) against BPA-induced liver pathology. We randomly divided 30 adult male Swiss albino mice (8 weeks old; N = 6) into five groups: group 1, no treatment (sham control (SC)); group 2, only oral sterile corn oil (vehicle control (VC)); group 3, 4 mg/kg/day of oral BPA (single dose (BPA group)); group 4, 0.4% oral VPA (VPA group); and group 5, oral BPA + VPA (BPA + VPA group). At the age of 10 weeks, the mice were euthanized for biochemical and histological examinations. BPA promoted a significant decrease in the body weight (BW), an increase in the liver weight, and a significant increase in the levels of liver damage markers aspartate aminotransferase and alanine aminotransferase in the BPA group compared to SC, as well as pathological changes in liver tissue. We also found an increase in the rate of apoptosis among hepatocytes. In addition, BPA significantly increased the levels of oxidative stress indices, malondialdehyde, and protein carbonylation but decreased the levels of reduced glutathione (GSH) in the BPA group compared to SC. In contrast, treatment with the HDAC2 inhibitor VPA significantly attenuated liver pathology, oxidative stress, and apoptosis and also enhanced GSH levels in VPA group and BPA + VPA group. The HDAC2 inhibitor VPA protects mice against BPA-induced liver pathology, likely by inhibiting oxidative stress and enhancing the levels of antioxidant-reduced GSH.

Peptidylarginine Deiminase 2 Knockout Improves Survival in hemorrhagic shock

BACKGROUND

The peptidylarginine deiminase (PAD) family converts arginine into citrulline through protein citrullination. PAD2 and PAD4 inhibitors can improve survival in hemorrhagic shock (HS). However, the impact of isoform-specific PAD inhibition in improving survival has not been studied. In this study, we utilize selective Pad2 knockout mice to elucidate loss of function of PAD2 leads to pro-survival effect in HS.

METHODS

HS: Pad2 and wild-type (WT) mice (n = 5/group) were subjected to lethal HS (55% volume hemorrhage). Survival was monitored over 7 days. Myocardial infarction (MI): Pad2 and WT mice (n = 9/group) were subjected to MI by permanent LAD ligation to examine the effect of ischemia on the heart. After 24 h cardiac function and infarct size were measured.

RESULTS

HS: Pad2 mice demonstrated 100% survival compared with 0% for WT mice (P = 0.002). In a sub-lethal HS model, cardiac β-catenin levels were higher in Pad2 compared with WT after 24 h. MI: WT mice demonstrated larger MI (75%) compared with Pad2 (60%) (P < 0.05). Pad2 had significantly higher ejection fraction and fractional shortening compared with WT (P < 0.05).

CONCLUSIONS

Pad2 improves survival in lethal HS. Possible mechanisms by which loss of PAD2 function improves survival include the activation of cell survival pathways, improved tolerance of cardiac ischemia, and improved cardiac function during ischemia. PAD2 is promising as a future therapeutic target for the treatment of HS and cardiac ischemia.

Visualization of three-dimensional microcirculation of rodents' retina and choroid for studies of critical illness using optical coherence tomography angiography

We developed a method to measure the relative blood flow speed using optical coherence tomography angiography (OCTA) in retina and choroid, and investigated the feasibility of this method for assessing microcirculatory function in rat models of sepsis and hemorrhagic shock. Two sepsis models, 6-h severe sepsis without treatment and 30-h moderate sepsis maintaining mean arterial pressure, and volume controlled hemorrhagic shock and fluid resuscitation model were used to see the change of microcirculation. The blood flow index (BFI), which was calculated from the OCTA images to represent the average relative blood flow, was decreasing during the 6-h severe sepsis model. Its change is in parallel with the mean arterial blood pressure (MAP) and blood lactate levels. In the 30-h moderate sepsis model, the BFI was decreased while maintaining MAP, and lactate was increased. In the hemorrhagic shock model, the change of BFI is in line with MAP and lactate levels. In all models, BFI change is more sensitive in choroid than in retina. This study presents the OCTA-based retinal and choroidal microcirculatory blood flow monitoring method and shows its utility for assessment of critical illness.

The Impact of Hemorrhagic Shock on Lung Ultrasound-Induced Pulmonary Capillary Hemorrhage

OBJECTIVES

Lung ultrasound (LUS) exposure can induce pulmonary capillary hemorrhage (PCH), depending on biological and physical exposure parameters. This study was designed to investigate the variation in the LUS induction of PCH due to hemorrhagic shock, which itself can engender pulmonary injury.

METHODS

Male rats were anesthetized with isoflurane in air. Shock was induced by withdrawal of 40% of the blood volume and assessed by the blood pressure detected by a femoral artery catheter and by blood glucose tests. B-mode ultrasound was delivered at 7.3 MHz with a low output (-20 dB) for aiming and with the maximal output (0 dB) for exposure. Pulmonary capillary hemorrhage was quantified by an assessment of comet tail artifacts in the LUS images and by measurement of PCH areas on the surface of fresh lung samples.

RESULTS

Tests without shock or catheterization surgery gave results for PCH similar to those of previous studies using different methods. Exposure before hemorrhagic shock gave a mean PCH area ± SE of 24.8 ± 9.2 mm² on the ultrasound scan plane, whereas exposure after shock gave 0 PCH (P < .001; n = 7).

CONCLUSIONS

The presence of hemorrhagic shock significantly reduces the occurrence of LUS-induced PCH.

Life on the battlefield: Valproic acid for combat applications

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

Molecular Mechanisms of Vascular Damage During Lung Injury

A variety of pulmonary and systemic insults promote an inflammatory response causing increased vascular permeability, leading to the development of acute lung injury (ALI), a condition necessitating hospitalization and intensive care, or the more severe acute respiratory distress syndrome (ARDS), a disease with a high mortality rate. Further, COVID-19 pandemic-associated ARDS is now a major cause of mortality worldwide. The pathogenesis of ALI is explained by injury to both the vascular endothelium and the alveolar epithelium. The disruption of the lung endothelial and epithelial barriers occurs in response to both systemic and local production of pro-inflammatory cytokines. Studies that evaluate the association of genetic polymorphisms with disease risk did not yield many potential therapeutic targets to treat and revert lung injury. This failure is probably due in part to the phenotypic complexity of ALI/ARDS, and genetic predisposition may be obscured by the multiple environmental and behavioral risk factors. In the last decade, new research has uncovered novel epigenetic mechanisms that control ALI/ARDS pathogenesis, including histone modifications and DNA methylation. Enzyme inhibitors such as DNMTi and HDACi may offer new alternative strategies to prevent or reverse the vascular damage that occurs during lung injury. This review will focus on the latest findings on the molecular mechanisms of vascular damage in ALI/ARDS, the genetic factors that might contribute to the susceptibility for developing this disease, and the epigenetic changes observed in humans, as well as in experimental models of ALI/ADRS.

Class IIa HDAC inhibitor TMP195 alleviates lipopolysaccharide-induced acute kidney injury

Sepsis-associated acute kidney injury (SA-AKI) is associated with high mortality rates, but clinicians lack effective treatments except supportive care or renal replacement therapies. Recently, histone deacetylase (HDAC) inhibitors have been recognized as potential treatments for acute kidney injury and sepsis in animal models; however, the adverse effect generated by the use of pan inhibitors of HDACs may limit their application in people. In the present study, we explored the possible renoprotective effect of a selective class IIa HDAC inhibitor, TMP195, in a murine model of SA-AKI induced by lipopolysaccharide (LPS). Administration of TMP195 significantly reduced increased serum creatinine and blood urea nitrogen levels and renal damage induced by LPS; this was coincident with reduced expression of HDAC4, a major isoform of class IIa HDACs, and elevated histone H3 acetylation. TMP195 treatment following LPS exposure also reduced renal tubular cell apoptosis and attenuated renal expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1, two biomarkers of tubular injury. Moreover, LPS exposure resulted in increased expression of BAX and cleaved caspase-3 and decreased expression of Bcl-2 and bone morphogenetic protein-7 in vivo and in vitro; TMP195 treatment reversed these responses. Finally, TMP195 inhibited LPS-induced upregulation of multiple proinflammatory cytokines/chemokines, including intercellular adhesion molecule-1, monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-1β, and accumulation of inflammatory cells in the injured kidney. Collectively, these data indicate that TMP195 has a powerful renoprotective effect in SA-AKI by mitigating renal tubular cell apoptosis and inflammation and suggest that targeting class IIa HDACs might be a novel therapeutic strategy for the treatment of SA-AKI that avoids the unintended adverse effects of a pan-HDAC inhibitor.

Histone Deacetylase Inhibitors: A Novel Strategy in Trauma and Sepsis

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

Sevoflurane reduces inflammatory factor expression, increases viability and inhibits apoptosis of lung cells in acute lung injury by microRNA-34a-3p upregulation and STAT1 downregulation

OBJECTIVE

Evidence has shown that sevoflurane plays a protective role in acute lung injury (ALI) due to its anti-inflammatory and apoptotic-regulating activity. Nevertheless, the mechanism of sevoflurane is still not completely understood. This study intends to discuss the mechanism of sevoflurane on ALI and the possible mechanisms involved.

METHODS

ALI model of rats was established through intravenous injection of endotoxin lipopolysaccharide. microRNA-34a-3p (miR-34a-3p) and signal transducers and activators of transcription 1 (STAT1) expression in lung tissues of ALI rats were detected. The optimal inhaled concentration of sevoflurane was screened, and then the modeled rats were injected with miR-34a-3p inhibitors, overexpressed STAT1 and inhaled 1.0 Minimum Alveolar Concentration (MAC) sevoflurane to determine mean arterial pressure (MAP) of rats, wet weight/dry weight ratio and myeloperoxidase (MPO) activity, oxidative stress- and inflammation-related factors in lung tissues of rats, along with lung cell viability and apoptosis.

RESULTS

MiR-34a-3p was downregulated while STAT1 was upregulated in ALI rats. Sevoflurane of 1.0 MAC was selected as the optimal inhalation concentration. Sevoflurane (1.0 MAC) increased MAP at T3 and reduced MPO activity, alleviated pathological damage, suppressed apoptosis, oxidative stress and inflammation, and induced cell viability in lung tissues of ALI rats. Down-regulated miR-34a-3p or up-regulated STAT reversed the functions of sevoflurane (1.0 MAC) on ALI rats.

CONCLUSION

Collectively, we demonstrate that sevoflurane reduces inflammatory factor expression, increases lung cell viability and inhibits lung cell apoptosis in ALI through upregulation of miR-34a-3p and downregulation of STAT1, which provides new clues for ALI treatment.

Comparative analysis of isoform-specific and non-selective histone deacetylase inhibitors in attenuating the intestinal damage after hemorrhagic shock

BACKGROUND

Isoform-specific histone deacetylase inhibitors (HDACIs) MC1568 and ACY1083 are comparable to the non-selective HDACI valproic acid (VPA) in improving survival in rodents undergoing lethal hemorrhage. However, the organ-specific properties of isoform-specific HDACIs have not been fully evaluated. Also, whether they can act synergistically is not known. We hypothesized that isoform-specific HDACIs are superior to VPA in attenuating intestinal injury and act synergistically when coadministered.

METHODS

Sprague Dawley rats were hemorrhaged (40% of total blood volume) and randomized to receive (n=4 per group) (1) MC1568 (5 mg/kg), (2) ACY1083 (30 mg/kg), (3) MC1568+ACY1083 (combination: 5 mg/kg + 30 mg/kg, respectively), (4) VPA (250 mg/kg), or (5) normal saline (NS; vehicle; 250 μL). Animals were observed for 3 hours, after which blood samples were collected and samples of the ileum were harvested. Expression of interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and cytokine-induced neutrophil chemoattractant 1 (CINC-1) was assessed in the tissues using enzyme-linked immunosorbent assay. Intestinal cleaved caspase 3 (c-caspase 3) levels were assessed as a marker of apoptosis, and histologic sections of the ileum were examined for signs of bowel injury. Levels of IL-1β and TNF-α were also measured in the serum as global markers of inflammation.

RESULTS

Treatments with MC1568, ACY1083, MC1568+ACY1083, and VPA were associated with decreased IL-1β levels in the intestine and serum compared with NS. IL-1β and TNF-α levels were significantly lower in the ACY1083 group compared with the VPA group. CINC-1 levels were significantly lower in the isoform-specific HDACI groups compared with the NS; however, no significant differences were seen with VPA. All treatment groups had a lower expression of intestinal c-caspase 3 compared with NS. Furthermore, MC1568 and ACY1083 groups had lower apoptosis compared with the VPA group. Bowel injury scores were significantly lower in the isoform-specific HDACI groups compared with the NS group; however, the attenuation in the VPA-treated animals did not reach statistical significance.

DISCUSSION

Isoform-specific HDACIs provide superior intestinal protection compared with VPA in a rodent model of hemorrhagic shock.

LEVEL OF EVIDENCE

Preclinical study.

Different resuscitation strategies and novel pharmacologic treatment with valproic acid in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death in young adults, and effective treatment strategies have the potential to save many lives. TBI results in coagulopathy, endothelial dysfunction, inflammation, cell death, and impaired epigenetic homeostasis, ultimately leading to morbidity and/or mortality. Commonly used resuscitation fluids such as crystalloids or colloids have several disadvantages and might even be harmful when administered in large quantities. There is a need for next-generation treatment strategies (especially in the prehospital setting) that minimize cellular damage, improve survival, and enhance neurological recovery. Pharmacologic treatment with histone deacetylase inhibitors, such as valproic acid, has shown promising results in animal studies of TBI and may therefore be an excellent example of next-generation therapy. This review briefly describes traditional resuscitation strategies for TBI combined with hemorrhagic shock and describes preclinical studies on valproic acid as a new pharmacologic agent in the treatment of TBI. It finally discusses limitations and future directions on the use of histone deacetylase inhibitors for the treatment of TBI.

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.

Aging increases the expression of lung CINCs and MCP-1 in senile patients with pneumonia

Objective

To explore the relationship between aging and the expression of monocyte chemoattractant protein (MCP) and cytokine-induced neutrophil chemoattractant (CINCs) in patients with pneumonia.

Results

Bacteria counts in senile group were significantly higher than non-senile group, and while white blood cell and neutrophil counts in senile group were observably lower than non-senile group. The concentration of MCP-1 was significantly higher in senile group compared with the non-senile group, and the expression of CINC-1 and CINC-2α was also higher in senile group. In all patients with different pathogens, expression of all the factors was significantly higher in senile group compared with the non-senile group. What’s more, expression of MCP-1, CINC-1 and CINC-2α showed significant difference in some patients with different pathogens. CINC-2β and CINC-3 expression was not detected in both groups.

Materials and methods

The present study included 800 patients with pneumonia who were hospitalized to the Department of Respiratory Medicine in Tongji Hospital during the period from December of 2014 to June of 2016. All patients were divided into two groups: senile pneumonia and non-senile pneumonia group. Bacteria, white blood cell and neutrophil counts were determined by automatic blood cell analyzer. The expression of MCP-1, CINC-1, CINC-2α, CINC-2β and CINC-3 was determined by ELISA assay.

Conclusions

Aging can increase the expression of MCP-1,CINC-1 and CINC-2α in patients with pneumonia, which may lead to increased risk of pneumonia in the elderly.

Regulation of Nitrogen Mustard-Induced Lung Macrophage Activation by Valproic Acid, a Histone Deacetylase Inhibitor

Nitrogen mustard (NM)-induced lung injury is associated with an accumulation of proinflammatory/cytotoxic M1 and antiinflammatory/wound repair M2 macrophages, which have been implicated in tissue injury and repair. Herein, we analyzed the effects of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor with antiinflammatory and antioxidant activity, on lung macrophages responding to NM. Treatment of rats with NM (0.125 mg/kg, i.t.) resulted in structural alterations in the lung and a macrophage-rich inflammatory cell infiltrate, at 3 d and 7 d. This was accompanied by expression of PCNA, a marker of proliferation, and CYPb5, HO-1, and MnSOD, markers of oxidative stress. Administration of VPA (300 mg/kg/day; i.p.), beginning 30 min after NM, reduced increases in PCNA, CYPb5, HO-1, and MnSOD. This was associated with increases in immature CD11b+CD43+ M1 macrophages in the lung, and decreases in mature CD11b+CD43- M2 macrophages 3 d post NM, suggesting delayed maturation and phenotypic switching. VPA also attenuated NM-induced increases in lung iNOS+ and CCR2+ M1 macrophages, a response correlated with downregulation of NOS2, IL12B, PTGS2, MMP-9, and CCR2 expression. Conversely, numbers of CD68+, CD163+ , and ATR-1α+ M2 macrophages increased after VPA, along with the expression of IL10, ApoE, and ATR-1A. NM exposure resulted in increased HDAC activity and upregulation of HDAC2 and acetylated H3K9 in the lung. Whereas VPA blunted the effects of NM on HDAC2 expression, histone H3K9 acetylation increased. These data suggest that alterations in the balance between histone acetylases and deacetylases contribute to lung macrophage maturation and activation following NM exposure.

Renal tissue pro-inflammatory gene expression is reduced by erythropoietin in rats subjected to hemorrhagic shock

BACKGROUND

Hemorrhagic shock (HS) is a condition produced by considerable loss of intravascular volume, which may eventually lead to organ damage and death.

OBJECTIVES

In the present study, the potential implication of the kidney tissue tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10) were evaluated in the protective effects of erythropoietin (EPO) during HS.

MATERIALS AND METHODS

Male Wistar rats were randomized into three experimental groups; Sham, HS (hemorrhagic shock and resuscitation), and EPO (erythropoietin). HS was induced by 50% blood volume hemorrhage over 30 minutes. After 2 hours, resuscitation was performed within 30 minutes. In the EPO group, EPO (300 IU/kg, i.v.) was administered 10 minutes before HS induction. Urine was collected to determine urinary N-acetyl-β-D-glucosaminidase (NAG) activity level. The kidney cytokines (TNF-α, IL-6 and IL-10) mRNA expressions were measured by real-time polymerase chain reaction (PCR).

RESULTS

HS rats showed significant increase in urinary NAG activity compared to the sham group. EPO significantly attenuated the rises in urinary NAG activity compared to the HS group. In the HS animals, renal TNF-α and IL-6 mRNA expressions increased whereas no difference was observed in IL-10 mRNA expression between the HS and sham groups. EPO was able to decrease renal TNF-α and IL-6 production and increase IL-10 mRNA expression.

CONCLUSIONS

In this study, we demonstrated that EPO attenuates kidney damage in rats subjected to HS. The beneficial effects of EPO may be at least partly mediated by modifications in the inflammatory cascade.

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

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

Comparison of Traditional and Integrated Digital Anesthetic Vaporizers

Recent efforts have focused on mitigating anesthetic gas emissions during laboratory animal experiments. A recently developed, digitally controlled, integrated digital vaporizer (IDV) using a syringe pump has been designed to use and administer anesthetic gas to mice and rats more efficiently. The entire IDV system can be placed on a laboratory bench, requires fewer charcoal filters to act as passive scavengers when used at a low gas flow rate, and does not need compressed gas to operate, a requirement for traditional passive systems. The objective of this study was to compare isoflurane usage between a traditional vaporizer (TdV) and an IDV system at both the same settings and those recommended by the manufacturer. We used 10 C57BL/6 male mice and administered isoflurane through either nose cones or tracheal tubes connected to a pulsatile ventilator. The results showed that isoflurane usage is highly dependent on the flow rate of the carrier gas, but the IDV system was more precise and handled low flow rates (150 mL/min) better than did the TdV system. We observed only slight differences in heart rate, respiration rate, core body temperature, time to loss of the righting reflex, and recovery time between group averages for both systems when set to manufacturer-recommended settings. Although observed decreased levels of waste anesthetic gas at low flow rates are expected from the IDV system, further work is needed to assess environmental anesthetic gas levels and exposure to laboratory personnel.

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.

Valproic acid attenuates acute lung injury induced by ischemia-reperfusion in rats

BACKGROUND

Evidence reveals that histone deacetylase (HDAC) inhibition has potential for the treatment of inflammatory diseases. The protective effect of HDAC inhibition involves multiple mechanisms. Heme oxygenase-1 (HO-1) is protective in lung injury as a key regulator of antioxidant response. The authors examined whether HDAC inhibition provided protection against ischemia-reperfusion (I/R) lung injury in rats by up-regulating HO-1 activity.

METHODS

Acute lung injury was induced by producing 40 min of ischemia followed by 60 min of reperfusion in isolated perfused rat lungs. The rats were randomly allotted to control group, I/R group, or I/R + valproic acid (VPA) group with or without an HO-1 activity inhibitor (zinc protoporphyrin IX) (n = 6 per group).

RESULTS

I/R caused significant increases in the lung edema, pulmonary arterial pressure, lung injury scores, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractant-1 concentrations in bronchoalveolar lavage fluid. Malondialdehyde levels, carbonyl contents, and myeloperoxidase-positive cells in lung tissue were also significantly increased. I/R stimulated the degradation of inhibitor of nuclear factor-κB-α, nuclear translocation of nuclear factor-κB, and up-regulation of HO-1 activity. Furthermore, I/R decreased B-cell lymphoma-2, heat shock protein 70, acetylated histone H3 protein expression, and increased the caspase-3 activity in the rat lungs. In contrast, VPA treatment significantly attenuated all the parameters of lung injury, oxidative stress, apoptosis, and inflammation. In addition, VPA treatment also enhanced HO-1 activity. Treatment with zinc protoporphyrin IX blocked the protective effect of VPA.

CONCLUSIONS

VPA protected against I/R-induced lung injury. The protective mechanism may be partly due to enhanced HO-1 activity following HDAC inhibition.

Effects of valproic acid and dexamethasone administration on early bio-markers and gene expression profile in acute kidney ischemia-reperfusion injury in the rat

Renal ischemia-reperfusion (IR) causes acute kidney injury (AKI) with high mortality and morbidity. The objective of this investigation was to ameliorate kidney IR injury and identify novel biomarkers for kidney injury and repair. Under general anesthesia, left renal ischemia was induced in Wister rats by occluding renal artery for 45 minutes, followed by reperfusion and right nephrectomy. Thirty minutes prior to ischemia, rats (n = 8/group) received Valproic Acid (150 mg/kg; VPA), Dexamethasone (3 mg/kg; Dex) or Vehicle (saline) intraperitoneally. Animals were sacrificed at 3, 24 or 120 h post-IR. Plasma creatinine (mg/dL) at 24 h was reduced (P<0.05) in VPA (2.7±1.8) and Dex (2.3±1.2) compared to Vehicle (3.8±0.5) group. At 3 h, urine albumin (mg/mL) was higher in Vehicle (1.47±0.10), VPA (0.84±0.62) and Dex (1.04±0.73) compared to naïve (uninjured/untreated control) (0.14±0.26) group. At 24 h post-IR urine lipocalin-2 (μg/mL) was higher (P<0.05) in VPA, Dex and Vehicle groups (9.61–11.36) compared to naïve group (0.67±0.29); also, kidney injury molecule-1 (KIM-1; ng/mL) was higher (P<0.05) in VPA, Dex and Vehicle groups (13.7–18.7) compared to naïve group (1.7±1.9). Histopathology demonstrated reduced (P<0.05) ischemic injury in the renal cortex in VPA (Grade 1.6±1.5) compared to Vehicle (Grade 2.9±1.1). Inflammatory cytokines IL1β and IL6 were downregulated and anti-apoptotic molecule BCL2 was upregulated in VPA group. Furthermore, kidney DNA microarray demonstrated reduced injury, stress, and apoptosis related gene expression in the VPA administered rats. VPA appears to ameliorate kidney IR injury via reduced inflammatory cytokine, apoptosis/stress related gene expression, and improved regeneration. KIM-1, lipocalin-2 and albumin appear to be promising early urine biomarkers for the diagnosis of AKI.

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.

Novel mechanisms of sildenafil in pulmonary hypertension involving cytokines/chemokines, MAP kinases and Akt

Pulmonary arterial hypertension (PH) is associated with high mortality due to right ventricular failure and hypoxia, therefore to understand the mechanism by which pulmonary vascular remodeling initiates these processes is very important. We used a well-characterized monocrotaline (MCT)-induced rat PH model, and analyzed lung morphology, expression of cytokines, mitogen-activated protein kinase (MAPK) phosphorylation, and phosphatidylinositol 3-kinase-Akt (PI-3k-Akt) pathway and nuclear factor (NF)-κB activation in order to elucidate the mechanisms by which sildenafil's protective effect in PH is exerted. Besides its protective effect on lung morphology, sildenafil suppressed multiple cytokines involved in neutrophil and mononuclear cells recruitment including cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2α/β, tissue inhibitor of metalloproteinase (TIMP)-1, interleukin (IL)-1α, lipopolysaccharide induced CXC chemokine (LIX), monokine induced by gamma interferon (MIG), macrophage inflammatory protein (MIP)-1α, and MIP-3α. NF-κB activation and phosphorylation were also attenuated by sildenafil. Furthermore, sildenafil reduced extracellular signal-regulated kinase (ERK)1/2 and p38 MAPK activation while enhanced activation of the cytoprotective Akt pathway in PH. These data suggest a beneficial effect of sildenafil on inflammatory and kinase signaling mechanisms that substantially contribute to its protective effects, and may have potential implications in designing future therapeutic strategies in the treatment of pulmonary hypertension.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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