Woon Yong Kwon

Niacin attenuates lung inflammation and improves survival during sepsis by downregulating the nuclear factor-κb pathway*

Objectives:To examine whether niacin attenuates lung inflammation and improves survival during sepsis and to determine whether the beneficial effects of niacin are associated with downregulation of the nuclear factor (NF)-&kgr;B pathway. Design:Prospective laboratory study. Setting:University laboratory. Subjects:Male Sprague-Dawley rats (n = 119). Interventions:To induce endotoxemia in rats, lipopolysaccharide (Escherichia coli, O26:B6) at a dosage of 10 mg/kg was injected into a tail vein and 10 mins later, vehicle, a low dose of niacin (360 mg/kg), or a high dose of niacin (1180 mg/kg) was administered once through an orogastric tube, respectively. Measurements and Main Results:We observed the survival of the subjects for 72 hrs. At 6 hrs postlipopolysaccharide, we euthanized animals and measured cytoplasmic phosphorylated inhibitor &kgr;B-&agr; and inhibitor &kgr;B-&agr; expressions, nuclear NF-&kgr;B p65 expression, NF-&kgr;B p65 DNA-binding activity, tumor necrosis factor-&agr;, and interleukin-6 gene expressions and histologic damages in lung tissues. We also measured nicotinamide adenine dinucleotide, reduced nicotinamide adenine dinucleotide phosphate, reduced glutathione, and malondialdehyde levels in lung tissues. High dose of niacin suppressed NF-&kgr;B activation and proinflammatory cytokine gene expressions in lung tissues, reduced histologic lung damages, and improved survival in endotoxemic rats. Furthermore, it increased nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and glutathione levels and decreased malondialdehyde level in lung tissues. Conclusions:High dose of niacin attenuated lung inflammation, reduced histologic lung damages, and improved survival during sepsis in rats. These therapeutic benefits were associated with downregulation of the NF-&kgr;B pathway.

Glutamine attenuates acute lung injury by inhibition of high mobility group box protein-1 expression during sepsis.

Heat shock protein 70 (HSP70) is reported as the main factor responsible for the beneficial effects of glutamine (GLN) and as a negative regulator of high mobility group box protein-1 (HMGB-1) expression. Our aim was to determine whether GLN attenuates acute lung injury (ALI) by the inhibition of HMGB-1 expression during sepsis. Male Sprague-Dawley rats were subjected to caecal ligation and puncture (CLP) to induce sepsis. GLN or saline was administered through tail vein 1 h after CLP. Then, quercetin (Q), an inhibitor of HSP70, was utilised to assess the role of the enhanced HSP70. We observed the survival of the subjects. At 24 h post-CLP, we measured lung HSP70, phosphorylated heat shock factor-1 (HSF-1-p) and HMGB-1 expressions, NF-kappaB DNA-binding activity and ALI occurrence. We also measured serum HSP70, IL-6 and HMGB-1 concentrations. GLN improved survival during sepsis. In GLN-treated rats, lung HSP70 and HSF-1-p expressions were enhanced, lung HMGB-1 expression and NF-kappaB DNA-binding activity were suppressed, and ALI was attenuated. Furthermore, in GLN-administered rats, serum HSP70 concentration was higher, and serum IL-6 and HMGB-1 concentrations were lower than those in non-treated rats. Q inhibited the enhancement of HSP70 and HSF-1-p expressions and abrogated the GLN-mediated benefits. In conclusion, GLN attenuated ALI and improved survival by the inhibition of HMGB-1 expression during sepsis in rats. These benefits were associated with the enhancement of HSP70 expression by GLN.

Protective effects of ethyl pyruvate treatment on paraquat-intoxicated rats

Although, numerous studies have attempted to reduce the oxygen radical injury induced by the antioxidants in paraquat intoxication, these antioxidant therapies have showed few survival benefits. Ethyl pyruvate (EP) may function as an effective scavenger of oxygen radicals, an anti-inflammatory agent and an energy source in many ischemia reperfusion models. The aim of this study was to evaluate the antioxidant and anti-inflammatory effects of EP on the lung and the liver tissues in paraquat-intoxicated rats. Rats were randomly given either a low (2 mg/kg i.p.) or high (40 mg/kg i.p.) EP dose, 30 min before or 1 h after paraquat (50 mg/kg i.p.) administration, and subsequently killed at 6 and 24 h. Glutathione (GSH) and malondialdehyde (MDA) levels of the lungs and the livers, and plasma nitric oxide (NO) concentrations were measured. Pretreatment of EP significantly decreased the MDA level in the lung and the liver tissues. EP also significantly decreased plasma NO concentrations at 6 h. EP pretreatment, however, failed to show significant change in GSH concentration. In post-treatment of EP, MDA levels in the lung tissue and plasma NO levels were significantly decreased. In conclusion, EP decreased the lipid peroxidation and seemed to exert an anti-inflammatory action in the paraquat intoxication rat model.

Induced Hypothermia Attenuates the Acute Lung Injury in Hemorrhagic Shock

BACKGROUND In previous animal studies, induction of therapeutic hypothermia (HT) in hemorrhagic shock (HS) had beneficial effects on the hemodynamic and metabolic parameters and on the survival. However, the effect of induced HT on acute lung injury (ALI) in HS has not been investigated. We sought to determine the effects of HT on ALI in HS. METHODS Male Sprague-Dawley rats (350-390 g; n = 8 per group) were randomized to the normothermia (NT; 36-37 degrees C) group or the moderate HT (27-30 degrees C) group and were subjected to volume-controlled (2 mL/100 g weight) HS (90 minutes) followed by 90 minutes of resuscitation. ALI score, lung malondialdehyde content, and myeloperoxidase activity were measured. The expression of glycogen synthase kinase 3beta (GSK-3beta), phosphorylated GSK-3beta, inducible nitric oxide synthase (iNOS), heat shock protein (HSP) 72, and nuclear factor-kappaB (NF-kappaB) in the lung were compared. RESULTS ALI score, lung malondialdehyde content, and myeloperoxidase were lower in the HT group. GSK-3beta and iNOS gene expressions in lung tissue were significantly decreased in the HT group (p < 0.05). On the contrary, the expression of phosphorylated GSK-3beta was increased in the HT group (p < 0.001). HSP 72 was expressed in the HT group but not in the NT group. The activated p65 NF-kappaB levels in lung nuclear extract were significantly lower in the NT group (p = 0.03). CONCLUSIONS HT attenuates HS-induced ALI in rats by the modulation of GSK, HSP 72, iNOS, and NF-kappaB.

Therapeutic hypothermia attenuates acute lung injury in paraquat intoxication in rats

AIM OF THE STUDY Paraquat intoxication induces acute lung injury and numerous fatalities have been reported. The mechanism of toxic effect of paraquat is oxidative injury and inflammation. Therapeutic hypothermia has been known to have antioxidant and anti-inflammatory effects. This study was designed to evaluate the effect of therapeutic hypothermia on paraquat intoxication. METHODS Male Sprague-Dawley rats were given 50 mg/kg of paraquat intraperitoneally and divided into the normothermia (36-38°C) group and the hypothermia (30-32°C) group after 1h of paraquat administration. The hypothermia group underwent 2 h of hypothermia followed by 2 h of rewarming. In the survival study, mortality was observed for 24 h after paraquat administration. An in the second experiment, lung tissues and plasma were harvested at 6 h after paraquat administration. RESULTS The 12 h survival rate was significantly higher in the hypothermia group than in the normothermia group (100% vs. 50%, p<0.05), but survival rates for 24 h were not different. Acute lung injury score was lower in the hypothermia group than in the normothermia group (p<0.05). Thmalondialdehyde contents of lung tissues, plasma interleukin-6 and nitrite/nitrate concentrations were significantly decreased in the HT group compared to the NT group (p<0.05). CONCLUSION Therapeutic hypothermia delayed early mortality and attenuated acute lung injury in paraquat intoxication.

Effect of N-acetylcysteine (NAC) on acute lung injury and acute kidney injury in hemorrhagic shock ,

AIM OF THE STUDY N-acetylcysteine (NAC) has been investigated to attenuate organ injury in various experimental and clinical studies. However, results in hemorrhagic shock (HS) were controversial. We determined the effects of continuous administration of NAC on acute lung injury (ALI) and acute kidney injury (AKI) in HS model. METHODS Twenty male Sprague-Dawley rats were used. Pressure controlled HS model defined by mean arterial pressure (MAP) 40±2 mmHg for 90 min followed by resuscitation and observation was used. Rats (n=10 per group) were randomized into 2 groups with NAC or dextrose. Intravenous NAC was given continuously from 15 min after induction of HS to the end of observation period (2 h). We measured serum IL-6, nitrite/nitrate concentration. NF-κB p65 DNA binding activity, expressions of cytoplasmic phosphorylated IκB-α (p-IκB-α) and IκB-α, malondialdehyde (MDA) and histopathological injury scores in lung and kidney were also evaluated. RESULTS MAP did not show any difference during the study period. NAC decreased histopathologic scores in both lung and kidney. Lung and kidney MDA levels were significantly lower in the NAC group compared to control group. Serum nitrite/nitrate and IL-6 were also significantly lower in the NAC group. The levels of lung cytoplasmic p-IκB-α expression was mitigated by NAC, and NF-κB p65 DNA binding activity was also significantly decreased in the NAC group. CONCLUSIONS Continuous infusion of NAC attenuated inflammatory response and acute lung and kidney injury after hemorrhagic shock in rats.

Effect of therapeutic hypothermia according to severity of sepsis in a septic rat model.

AIM OF STUDY The effects of therapeutic hypothermia (HT) during experimental sepsis may be influenced by disease severity. We experimentally investigated the effect of therapeutic HT on varying disease severity in a septic rat model. MATERIALS AND METHODS An adult male Sprague-Dawley rat model of intra-abdominal sepsis was used. To modify the disease severity, we used two different models; a moderate severe sepsis model (MSSM) and a severe septic shock model (SSSM). All rats were randomized to a hypothermia group (HT, 30-32°C) or a normothermia group (NT, 36-38°C) 1h after sepsis induction in each model. HT was maintained for 4h and rewarming was conducted for 2h. Survival time was recorded for up to 12h in the SSSM group and 24h in the MSSM group. Acute lung and liver injury, cytokine, and malondialdehyde (MDA) levels were investigated 7h after sepsis induction. Hemodynamic profiles were also evaluated. RESULTS In the SSSM, there were survival benefits and reduced acute lung and liver injury with therapeutic HT. Therapeutic HT was also associated with significantly reduced levels of plasma interleukin-6 and tissue malondialdehyde (MDA) levels in the liver and lung compared with the NT group in the SSSM. There was a tendency for the mean arterial pressure to be higher in the HT group compared to the NT group in the SSSM. In MSSM, however, there was no such beneficial effect. CONCLUSION In this rat model of severe septic shock, therapeutic HT showed beneficial effects. In contrast, therapeutic HT did not show protective effect in the moderate sepsis model.

Protective effects of therapeutic hypothermia in post-resuscitation myocardium☆

AIM OF THE STUDY Post-resuscitation therapeutic hypothermia has been recommended because of its neuroprotective effects. However, a few studies have reported the effects of therapeutic hypothermia on the heart, especially in ventricular fibrillation cardiac arrest. The aim of this study was to determine whether therapeutic hypothermia attenuates post-resuscitation myocardial injury in a swine cardiac arrest model. METHODS A prospective animal study was performed in the university hospital animal research laboratory. Ventricular fibrillation cardiac arrest was induced in domestic pigs weighing 35-40 kg. After 6 min of no flow time, cardiopulmonary resuscitation was provided to pigs, and the restoration of spontaneous circulation (ROSC) was achieved. The subjects were randomly allocated to a normothermic (NT group, n=5) or hypothermic (HT group, n=5) group. In the HT group, therapeutic hypothermia (core temperature 32-34 °C) was maintained for 24h, and rewarming was performed over a period of 8 h. In the NT group, core temperature was maintained at 37 °C throughout the experiments. Sixty hours after ROSC, blood and myocardial tissues were harvested. RESULTS Serum troponin I was not significantly different between the groups. However, myocardial histological damage was attenuated in the HT group. Myocardial ATP contents were higher in the HT group than in the NT group. Immunohistochemistry for apoptosis-related protein showed that survivin expression was higher in the HT group, and XAF1 and cleaved caspase-3 expressions were lower in the HT group than in the NT group. CONCLUSIONS Therapeutic hypothermia attenuated histological myocardial injury in ventricular fibrillation cardiac arrest model of pigs while preserving more ATP and decreased apoptosis.

4F, apolipoprotein AI mimetic peptide, attenuates acute lung injury and improves survival in endotoxemic rats.

BACKGROUND 4F, apolipoprotein AI mimetic peptide, mimics anti-inflammatory properties of high-density lipoprotein (HDL). The aim of this study was to investigate whether 4F attenuates acute lung injury and improves survival in endotoxemic rats and to determine whether the therapeutic benefits of 4F are associated with the stimulation of sphingosine-1-phosphate receptor 1 (S1P1), the activation of Akt, the down-regulation of the nuclear factor-&kgr;B (NF-&kgr;B) pathway, and the suppression of cell adhesion molecules. METHODS To induce endotoxemia in rats, lipopolysaccharide (LPS, 10 mg/kg) was injected into a tail vein and 10 minutes later, vehicle or 4F (10 mg/kg) was administered intraperitoneally, respectively. We observed the survival of subjects for 72 hours. At 6-hour post-LPS, we killed animals and measured S1P1 expression, phosphorylated Akt/Akt ratio, cytoplasmic phosphorylated inhibitor &kgr;B-&agr;/inhibitor &kgr;B-&agr; ratio, nuclear NF-&kgr;B p65 expression and DNA-binding activity, endothelial leukocyte adhesion molecule-1 (E-selectin) and intercellular adhesion molecule-1 expression, myeloperoxidase activity, and histologic damages in lung tissues. We also measured serum HDL cholesterol level. RESULTS 4F improved survival in endotoxemic rats. 4F restored LPS-induced diminution of serum HDL cholesterol level and increased lung S1P1 expression and phosphorylated Akt/Akt ratio in LPS-treated rats. Furthermore, 4F suppressed inhibitor &kgr;B-&agr; degradation, NF-&kgr;B activation, E-selectin and intercellular adhesion molecule-1 expression, and myeloperoxidase activity, and attenuated histologic damages in lung tissues. CONCLUSIONS 4F attenuated acute lung injury and improved survival in endotoxemic rats. The therapeutic benefits of 4F were found to be associated with the stimulation of S1P1, the activation of Akt, the down-regulation of the NF-&kgr;B pathway, and the suppression of cell adhesion molecules.

Antioxidant effects of selenium on lung injury in paraquat intoxicated rats

Context. Paraquat (PQ) causes lethal intoxication by inducing oxidant injury to the lung. Selenium is a cofactor for glutathione peroxidase (GPx), which is one of the major endogenous antioxidant enzymes. Objective. To determine whether selenium post-treatment activates GPx, decreases lung injury, and improves survival in PQ intoxicated rats. Materials and methods. Male Spraque–Dawley rats were categorized into three groups: sham (n = 6), PQ (n = 12), and PQ + Se (n = 12). In the PQ and PQ + Se groups, 50 mg/kg of PQ was administered intraperitoneally. After 10 minutes, 60 μg/kg of Se (PQ + Se) or saline (PQ) was administered via the tail vein. Six rats per group were euthanized 6 hours or 24 hours later. Lung tissues were harvested for the measurement of GPx activity, reduced glutathione (GSH), glutathione disulfide (GSSG) and malondialdehyde (MDA) and for histological analysis. Using separated set of rats, survival of PQ (n = 10) and PQ + Se (n = 10) were observed for 72 hours. Results. GPx activity in the PQ group at the 6-hour and 24-hour time points was lower than in the sham group (p < 0.006). GPx activity in the PQ + Se group at the 6-hour and 24-hour time points was higher than in the PQ group at the same time (p < 0.006). GPx activity in the PQ + Se group at 24 hours was higher than at 6-hour time point and also higher than in the sham group (p < 0.006). The GSH/GSSG ratio in the PQ + Se group at 24 hours was lower than that in the sham group (p < 0.006). MDA levels in the PQ group at 6 hours and 24 hours were higher than in the sham group (p < 0.006). MDA levels at 24 hours in the PQ + Se group was lower than in the PQ group (p < 0.006). Acute lung injury (ALI) scores in the PQ group at 6 hours and 24 hours were higher than in the sham group (p < 0.006). ALI scores at 24 hours in the PQ + Se group were lower than in the PQ group. Survival rates did not differ between PQ and PQ + Se (p = 0.869). Conclusion. Single dose of selenium post-treatment activates GPx and attenuates lipid peroxidation and lung injury early after paraquat intoxication, but does not improve 72 hours of survival.