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

Prolonging the therapeutic window for valproic acid treatment in a swine model of traumatic brain injury and hemorrhagic shock

BACKGROUND

It has previously been shown that administration of valproic acid (VPA) can improve outcomes if given within an hour following traumatic brain injury (TBI). This short therapeutic window (TW) limits its use in real-life situations. Based upon its pharmacokinetic data, we hypothesized that TW can be extended to 3 hours if a second dose of VPA is given 8 hours after the initial dose.

METHOD

Yorkshire swine (40-45 kg; n = 10) were subjected to TBI (controlled cortical impact) and 40% blood volume hemorrhage. After 2 hours of shock, they were randomized to either (1) normal saline resuscitation (control) or (2) normal saline-VPA (150 mg/kg × two doses). First dose of VPA was started 3 hours after the TBI, with a second dose 8 hours after the first dose. Neurologic severity scores (range, 0-36) were assessed daily for 14 days, and brain lesion size was measured via magnetic resonance imaging on postinjury day 3.

RESULTS

Hemodynamic and laboratory parameters of shock were similar in both groups. Valproic acid-treated animals had significantly less neurologic impairment on days 2 (16.3 ± 2.0 vs. 7.3 ± 2.8) and 3 (10.9 ± 3.6 vs. 2.8 ± 1.1) postinjury and returned to baseline levels 54% faster. Magnetic resonance imaging showed no differences in brain lesion size on day 3. Pharmacokinetic data confirmed neuroprotective levels of VPA in the circulation.

CONCLUSION

This is the first study to demonstrate that VPA can be neuroprotective even when given 3 hours after TBI. This expanded TW has significant implications for the design of the clinical trial.

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.

Intense Light Pretreatment Improves Hemodynamics, Barrier Function and Inflammation in a Murine Model of Hemorrhagic Shock Lung

INTRODUCTION

Hemorrhagic shock is a primary injury amongst combat casualties. Hemorrhagic shock can lead to acute lung injury, which has a high mortality rate. Based on studies showing the role of intense light for organ-protection, we sought to evaluate if intense light pretreatment would be protective in a murine model of hemorrhagic shock lung.

MATERIALS AND METHODS

After exposure to standard room light or to intense light (10 000 LUX), mice were hemorrhaged for 90 minutes to maintain a mean arterial pressure (MAP) of 30-35 mmHg. Mice were then resuscitated with their blood and a NaCl infusion at a rate of 0.2 ml/h over a 3-hour period. During resuscitation, blood pressure was recorded. At the end of resuscitation, bronchoalveolar lavage was analyzed for alveolar epithelial barrier function and inflammation. To get insight into the relevance of intense light for humans, we performed a proteomics screen for lung injury biomarkers in plasma from healthy volunteers following intense light therapy.

RESULTS

We found that intense light pretreated mice had improved hemodynamics and significantly lower albumin, IL-6, and IL-8 levels in their bronchoalveolar lavage than controls. We further discovered that intense light therapy in humans significantly downregulated proinflammatory plasma proteins that are known to cause acute lung injury.

CONCLUSIONS

Our data demonstrate that mice exposed to intense light before hemorrhagic shock lung have less lung inflammation and improved alveolar epithelial barrier function. We further show that intense light therapy downregulates lung injury promoting proteins in human plasma. Together, these data suggest intense light as a possible strategy to ameliorate the consequences of a hemorrhagic shock on lung injury.

Isoform 6-selective histone deacetylase inhibition reduces lesion size and brain swelling following traumatic brain injury and hemorrhagic shock

BACKGROUND

Nonselective histone deacetylase (pan-HDAC) inhibitors, such as valproic acid (VPA), have demonstrated neuroprotective properties in trauma models. However, isoform-specific HDAC inhibitors may provide opportunity for more effective drug administration with fewer adverse effects. We investigated HDAC6 inhibition with ACY-1083 in an in vitro and an in vivo large animal model of injury.

METHODS

Mouse hippocampal cells were subjected to oxygen-glucose deprivation (0% O2, glucose-free and serum-free medium, 18 hours) and reoxygenation (21% O2, normal culture media, 4 hours) with/without VPA (4 mmol/L) or ACY-1083 (30 nmol/L, 300 nmol/L). Cell viability was measured by methylthiazolyl tetrazolium assay. Expression of hypoxia-inducible factor-1α, heat shock protein 70, and effectors in the phosphoinositide-3 kinase/mammalian target of rapamycin pathway were measured by Western blot analysis. Additionally, swine were subjected to combined traumatic brain injury and hemorrhagic shock and randomized to three treatment groups (n = 5/group): (i) normal saline (NS; 3× hemorrhage volume); (ii) NS + VPA (NS; 3× hemorrhage volume, VPA; 150 mg/kg), and (iii) NS + ACY-1083 (NS; 3× hemorrhage volume, ACY-1083; 30 mg/kg). After 6 hours, brain tissue was harvested to assess lesion size and brain swelling.

RESULTS

Significant improvement in cell viability was seen with both HDAC inhibitors in the in vitro study. ACY-1083 suppressed hypoxia-inducible factor-1α expression and up-regulated phosphorylated mammalian target of rapamycin and heat shock protein 70 in a dose-dependent manner. Lesion size and brain swelling in animals treated with pharmacologic agents (VPA and ACY-1083) were both smaller than in the NS group. No differences were observed between the VPA and ACY-1083 treatment groups.

CONCLUSIONS

In conclusion, selective inhibition of HDAC6 is as neuroprotective as nonselective HDAC inhibition in large animal models of traumatic brain injury and hemorrhagic shock.

Epigenetics Mechanisms in Multiorgan Dysfunction Syndrome

Epigenetic mechanisms including deoxyribonucleic acid (DNA) methylation, histone modifications (eg, histone acetylation), and microribonucleic acids (miRNAs) have gained much scientific interest in the last decade as regulators of genes expression and cellular function. Epigenetic control is involved in the modulation of inflammation and immunity, and its dysregulation can contribute to cell damage and organ dysfunction. There is growing evidence that epigenetic changes can contribute to the development of multiorgan dysfunction syndrome (MODS), a leading cause of mortality in the intensive care unit (ICU). DNA hypermethylation, histone deacetylation, and miRNA dysregulation can influence cytokine and immune cell expression and promote endothelial dysfunction, apoptosis, and end-organ injury, contributing to the development of MODS after a critical injury. Epigenetics processes, particularly miRNAs, are emerging as potential biomarkers of severity of disease, organ damage, and prognostic factors in critical illness. Targeting epigenetics modifications can represent a novel therapeutic approach in critical care. Inhibitors of histone deacetylases (HDCAIs) with anti-inflammatory and antiapoptotic activities represent the first class of drugs that reverse epigenetics modifications with human application. Further studies are required to acquire a complete knowledge of epigenetics processes, full understanding of their individual variability, to expand their use as accurate and reliable biomarkers and as safe target to prevent or attenuate MODS in critical disease.