Dexmedetomidine improves acute lung injury by activating autophagy in a rat hemorrhagic shock and resuscitation model.

Dexmedetomidine (DEX) can reduce lung injury in a hemorrhagic shock (HS) resuscitation (HSR) model in rats by inhibiting inflammation. Here, we aimed to investigate if these effects of DEX are due to autophagy activation. Therefore, we established HSR rat models and divided them into four groups. HS was induced using a blood draw. The rats were then resuscitated by reinjecting the drawn blood and saline. The rats were sacrificed 24 h after resuscitation. Lung tissues were harvested for histopathological examination, determination of wet/dry lung weight ratio, and detection of the levels of autophagy-related marker proteins LC3, P62, Beclin-1, and the ATG12-ATG5 conjugate. The morphological findings of hematoxylin and eosin staining in lung tissues and the pulmonary wet/dry weight ratio showed that lung injury improved in HSR + DEX rats. However, chloroquine (CQ), an autophagy inhibitor, abolished this effect. Detecting the concentration of autophagy-related proteins showed that DEX administration increased LC3, ATG12-ATG5, and Beclin-1 expression and decreased P62 expression. The expression levels of these proteins were similar to those in the HSR group after CQ + DEX administration. In summary, DEX induced autophagic activation in an HSR model. These findings suggest that DEX administration partially ameliorates HSR-induced lung injury via autophagic activation.

Protective effect of tin chloride on rhabdomyolysis-induced acute kidney injury in rats.

The heme component of myoglobin plays a crucial role in the pathogenesis of rhabdomyolysis-associated acute kidney injury (RM-AKI). Heme oxiganenase-1 (HO-1) is the rate-limiting enzyme of heme catabolism, and its metabolites, iron, biliverdin, and carbon monoxide, have antioxidant properties. Tin chloride (SnCl2) is a kidney specific HO-1 inducer. In this study, we examined whether the induction of HO-1 in the kidney by SnCl2 pretreatment ameliorates RM-AKI in rats and if the effect is due to the degradation of excess renal free heme. We developed an RM-AKI rat (male Sprague-Dawley rats) model by injecting glycerol (Gly) in the hind limbs. RM-AKI rats were pretreated with saline or SnCl2 or additional SnMP (tin mesoporphyrin, a specific HO inhibitor) followed by Gly treatment. Serum blood urea nitrogen (BUN) and creatinine (Crea) were measured as indicators of renal function. Renal free heme level was assessed based on the levels of δ-aminolevulinate synthase (ALAS1), a heme biosynthetic enzyme, and nuclear BTB and CNC homology 1 (Bach1), an inhibitory transcription factor of HO-1. Elevated free heme levels lead to decreases in ALAS1 and nuclear Bach1. After 24 h of Gly injection, serum BUN and Crea levels in saline-pretreated rats were significantly higher than those in untreated control rats. In contrast, SnCl2-pretreated rats showed no significant increase in the indices. However, additional treatment of SnMP abolished the beneficial effect of SnCl2. Renal ALAS1 mRNA levels and renal nuclear Bach1 protein levels in the saline pretreated rats were significantly lower than those in control rats 3 h after Gly injection. In contrast, the levels in SnCl2-pretreated rats were not altered. The findings indicate that SnCl2 pretreatment confers protection against RM-AKI by virtue of HO-1 induction in the renal system, at least in part through excess free heme degradation.

Role of the Transcription Factor BTB and CNC Homology 1 in a Rat Model of Acute Liver Injury Induced by Experimental Endotoxemia.

Hepatic oxidative stress plays an important role in the pathogenesis of several acute liver diseases, and free heme is thought to contribute to endotoxemia-induced acute liver injury. The heme oxygenase 1 (HO-1) gene is upregulated and the δ-aminolevulinate synthase (ALAS1) gene is downregulated in the rat liver following lipopolysaccharide (LPS) treatment. BTB and CNC homology 1 (Bach1) is a heme-responsive transcription factor that normally represses HO-1 expression. In this study, we evaluated the changes in HO-1, ALAS1, and Bach1 expression and nuclear Bach1 expression in rat livers following intravenous LPS administration (10 mg/kg body weight). LPS significantly upregulated HO-1 mRNA and downregulated ALAS1 mRNA in the rat livers, suggesting that hepatic free heme concentrations are increased after LPS treatment. Bach1 mRNA was strongly induced after LPS injection. In contrast, nuclear Bach1 was significantly but transiently decreased after LPS treatment. Rats were also administered hemin (50 mg/kg body weight) intravenously to elevate heme concentrations, which decreased nuclear Bach1 levels. Our results suggest that elevated hepatic free heme may be associated with a decline of nuclear Bach1, and induction of Bach1 mRNA may compensate for the decreased nuclear Bach1 after LPS treatment in the rat liver.

Therapeutic effect of carbon monoxide-releasing molecule-3 on acute lung injury after hemorrhagic shock and resuscitation.

Hemorrhagic shock and resuscitation (HSR) induces a pulmonary inflammatory response and frequently causes acute lung injury. Carbon monoxide-releasing molecule-3 (CORM-3) has been reported to liberate and deliver CO under physiological conditions, which exerts organ-protective effects during systemic insults. The present study aimed to determine whether the administration of CORM-3 following HSR exerts a therapeutic effect against HSR-induced lung injury without any detrimental effects on oxygenation and hemodynamics. To induce hemorrhagic shock, rats were bled to a mean arterial blood pressure of 30 mmHg for 45 min and then resuscitated with the shed blood. CORM-3 or a vehicle was intravenously administered immediately following the completion of resuscitation. The rats were divided into four groups, including sham, HSR, HSR/CORM-3 and HSR/inactive CORM-3 groups. Arterial blood gas parameters and vital signs were recorded during HSR. The histopathological changes to the lungs were evaluated using a lung injury score, while pulmonary edema was evaluated on the basis of the protein concentration in bronchoalveolar lavage fluid and the lung wet/dry ratio. We also investigated the pulmonary expression levels of inflammatory mediators and apoptotic markers such as cleaved caspase-3 and transferase-mediated dUTP-fluorescein isothiocyanate nick-end labeling (TUNEL) staining. Although HSR caused significant lung histopathological damage and pulmonary edema, CORM-3 significantly ameliorated this damage. CORM-3 also attenuated the HSR-induced upregulation of tumor necrosis factor-α, inducible nitric oxide synthase and interleukin-1ß genes, and the expression of interleukin-1ß and macrophage inflammatory protein-2. In addition, the expression of interleukin-10, an anti-inflammatory cytokine, was inversely enhanced by CORM-3, which also reduced the number of TUNEL-positive cells and the expression of cleaved caspase-3 following HSR. Although CORM-3 was administered during the acute phase of HSR, it did not exert any influence on arterial blood gas analysis data and vital signs during HSR. Therefore, treatment with CORM-3 ameliorated HSR-induced lung injury, at least partially, through anti-inflammatory and anti-apoptotic effects, without any detrimental effects on oxygenation and hemodynamics.

Dynamic changes in Bach1 expression in the kidney of rhabdomyolysis-associated acute kidney injury.

Free heme, a pro-oxidant released from myoglobin, is thought to contribute to the pathogenesis of rhabdomyolysis-associated acute kidney injury (RM-AKI), because renal overexpression of heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, confers protection against RM-AKI. BTB and CNC homology 1 (Bach1) is a heme-responsive transcription factor that represses HO-1. Here, we examined the changes with time in the gene expression of Bach1, HO-1, and δ-aminolevulinate synthase (ALAS1, a heme biosynthetic enzyme) in the rat kidney using an RM-AKI model induced by the injection of 50% glycerol (10 mL/kg body weight) into bilateral limbs. We also examined the protein expression of Bach1 in the nucleus and cytosol, and HO-1 in the rat kidney. Glycerol treatment induced significant elevation of serum creatinine kinase and aspartate aminotransferase levels followed by the marked elevation of serum blood urea nitrogen and creatinine levels, which caused serious damage to renal tubules. Following glycerol treatment, HO-1 mRNA and protein levels were significantly up-regulated, while ALAS1 mRNA expression was down-regulated, suggesting an increase in the free renal heme concentration. The Bach1 mRNA level was drastically increased 3 h after glycerol treatment, and the increased level was maintained for 12 h. Nuclear Bach1 protein levels were significantly decreased 3 h after treatment. Conversely, cytosolic Bach1 protein levels abruptly increased after 6 h. In conclusion, we demonstrate the dynamic changes in Bach1 expression in a rat model of RM-AKI. Our findings suggest that the increase in Bach1 mRNA and cytosolic Bach1 protein expression may reflect de novo Bach1 protein synthesis to compensate for the depletion of nuclear Bach1 protein caused by the induction of HO-1 by free heme.

Induction of hepatic Bach1 mRNA expression by carbon tetrachloride-induced acute liver injury in rats.

Hepatic oxidative stress is a major contributor to the pathogenesis of several acute liver diseases. Diagnostic markers of hepatic oxidative stress may facilitate early detection and intervention. Bach1 is an oxidative stress-responsive transcription factor that represses heme oxygenase 1 (HO-1), the rate-limiting enzyme in the catabolism of heme, a potent pro-oxidant. We previously demonstrated that carbon tetrachloride (CCl4) causes oxidative hepatic injury in rats, exacerbated by free heme, suggesting that CCl4 may affect Bach1 gene expression. In the present study, we used northern blot analysis to measure Bach1, HO-1 and δ-aminolevulinate synthase (ALAS1; a heme biosynthesis enzyme) mRNA expression levels during acute hepatic injury induced by CCl4 (at doses of 0.1, 1.0 and 2.0 ml/kg body weight). Oxidative injury was assessed by measuring serum alanine aminotransferase (ALT), hepatic malondialdehyde (MDA) and glutathione (GSH) content. Treatment with CCl4 induced a significant dose-dependent increase in Bach1 mRNA 1-3 h after administration. Bach1 mRNA peaked at 6 h after CCl4 treatment (1 ml/kg), followed by a rapid decrease and gradual return to baseline by 12 h after treatment. The timecourse of transient Bach1 mRNA induction roughly mirrored that of HO-1 mRNA, while ALAS1 mRNA was inversely downregulated. Serum ALT levels and hepatic MDA concentration were significantly increased at 24 h after CCl4 treatment, while the hepatic GSH content was significantly reduced within 3 h of treatment. Serum ALT levels were positively correlated with Bach1 mRNA levels. These findings indicate that Bach1 mRNA is transiently induced in rat liver by CCl4, possibly as a regulatory mechanism to restore HO-1 to baseline following free heme catabolism. Our findings also suggest that Bach1 mRNA expression may be a novel indicator of the extent of oxidative hepatic injury caused by free heme.

Effects of biliverdin administration on acute lung injury induced by hemorrhagic shock and resuscitation in rats.

Hemorrhagic shock and resuscitation induces pulmonary inflammation that leads to acute lung injury. Biliverdin, a metabolite of heme catabolism, has been shown to have potent cytoprotective, anti-inflammatory, and anti-oxidant effects. This study aimed to examine the effects of intravenous biliverdin administration on lung injury induced by hemorrhagic shock and resuscitation in rats. Biliverdin or vehicle was administered to the rats 1 h before sham or hemorrhagic shock-inducing surgery. The sham-operated rats underwent all surgical procedures except bleeding. To induce hemorrhagic shock, rats were bled to achieve a mean arterial pressure of 30 mmHg that was maintained for 60 min, followed by resuscitation with shed blood. Histopathological changes in the lungs were evaluated by histopathological scoring analysis. Inflammatory gene expression was determined by Northern blot analysis, and oxidative DNA damage was assessed by measuring 8-hydroxy-2' deoxyguanosine levels in the lungs. Hemorrhagic shock and resuscitation resulted in prominent histopathological damage, including congestion, edema, cellular infiltration, and hemorrhage. Biliverdin administration prior to hemorrhagic shock and resuscitation significantly ameliorated these lung injuries as judged by histopathological improvement. After hemorrhagic shock and resuscitation, inflammatory gene expression of tumor necrosis factor-α and inducible nitric oxide synthase were increased by 18- and 8-fold, respectively. Inflammatory gene expression significantly decreased when biliverdin was administered prior to hemorrhagic shock and resuscitation. Moreover, after hemorrhagic shock and resuscitation, lung 8-hydroxy-2' deoxyguanosine levels in mitochondrial DNA expressed in the pulmonary interstitium increased by 1.5-fold. Biliverdin administration prior to hemorrhagic shock and resuscitation decreased mitochondrial 8-hydroxy-2' deoxyguanosine levels to almost the same level as that in the control animals. We also confirmed that biliverdin administration after hemorrhagic shock and resuscitation had protective effects on lung injury. Our findings suggest that biliverdin has a protective role, at least in part, against hemorrhagic shock and resuscitation-induced lung injury through anti-inflammatory and anti-oxidant mechanisms.

Inhalation of carbon monoxide following resuscitation ameliorates hemorrhagic shock-induced lung injury.

Even after successful resuscitation, hemorrhagic shock frequently causes pulmonary inflammation that induces acute lung injury (ALI). We previously demonstrated that when CO is inhaled at a low concentration both prior to and following hemorrhagic shock and resuscitation (HSR) it ameliorates HSR-induced ALI in rats due to its anti-inflammatory effects. In the present study, we administered CO to the same model of ALI only after resuscitation and examined whether it exerted a therapeutic effect without adverse events on HSR-induced ALI, since treatment of animals with CO prior to HSR did not prevent lung injury. HSR were induced by bleeding animals to achieve a mean arterial pressure of 30 mmHg for 1 h followed by resuscitation with the removed blood. HSR resulted in the upregulation of inflammatory gene expression and increased the rate of apoptotic cell death in the lungs. This was determined from an observed increase in the number of cells positive for transferase-mediated dUTP-fluorescein isothiocyanate (FITC), nick-end labeling staining and activated caspase-3. HSR also resulted in prominent histopathological damage, including congestion, edema, cellular infiltration and hemorrhage. By contrast, CO inhalation for 3 h following resuscitation significantly ameliorated these inflammatory events, demonstrated by reduced histological damage, inflammatory mediators and apoptotic cell death. The protective effects of CO against lung injury were notably associated with an increase in the protein expression level of peroxisome proliferator-activated receptor (PPAR)-γ, an anti-inflammatory transcriptional regulator in the lung. Moreover, CO inhalation did not affect the hemodynamic status or tissue oxygenation during HSR. These findings suggest that inhalation of CO at a low concentration exerts a potent therapeutic effect against HSR-induced ALI and attenuates the inflammatory cascade by increasing PPAR-γ protein expression.

Protective effect of carbon monoxide inhalation on lung injury after hemorrhagic shock/resuscitation in rats.

BACKGROUND: Hemorrhagic shock and resuscitation (HSR) induces pulmonary inflammation that leads to acute lung injury. Carbon monoxide (CO), a by-product of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. The aim of this study was to examine the effects of CO inhalation at low concentration on lung injury induced by HSR in rats. METHODS: Rats were subjected to HSR by bleeding to achieve mean arterial pressure of 30 mm Hg for 60 minutes followed by resuscitation with shed blood and saline as needed to restore blood pressure. HSR animals were either maintained in room air or were exposed to CO at 250 ppm for 1 hour before and 3 hours after HSR. RESULTS: HSR caused an increase in the DNA binding activity of nuclear factor-kappaB and activator protein-1 in the lung followed by the up-regulation of pulmonary gene expression of tumor necrosis factor-alpha, inducible nitric oxide synthase, and interleukin (IL)-10. HSR also resulted in an increase in myeloperoxidase activity and wet weight to dry weight ratio in the lung, and more prominent histopathologic changes including congestion, edema, cellular infiltration, and hemorrhage. In contrast, CO inhalation significantly ameliorated these inflammatory events as judged by fewer histologic changes, less up-regulation of inflammatory mediators, and less activation of nuclear factor-kappaB and activator protein-1. Interestingly, the protective effects against lung injury afforded by CO were associated with further increases in mRNA expression of IL-10 in the lung. CONCLUSIONS: These findings suggest that inhaled CO at a low concentration ameliorated HSR-induced lung injury and attenuated inflammatory cascades by up-regulation of anti-inflammatory IL-10.

Role of heme oxygenase-1 in protection of the kidney after hemorrhagic shock.

Hemorrhagic shock followed by resuscitation (HSR) causes oxidative stress, which results in multiple organ damage. The kidney is one of the target organs of HSR-mediated oxidative tissue injury. Heme oxygenase (HO)-1, the rate-limiting enzyme in heme catabolism, is induced by oxidative stress; it protects against oxidative tissue injuries. The aim of the present study was to examine the role of renal HO-1 induction after HSR. Rats were subjected to hemorrhagic shock to achieve a mean arterial pressure of 30 mmHg for 60 min, followed by resuscitation with the shed blood. HSR resulted in a significant increase in functional HO-1 protein in the tubular epithelial cells of the kidney, whereas HSR resulted in only a slight increase in gene expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS), and in protein expression of activated caspase-3 solely in renal cells where HO-1 expression was absent. HSR also resulted in a significant increase in Bcl-2 gene expression. Pretreatment of HSR animals with tin-mesoporphyrin (0.5 micromol/kg), a specific competitive inhibitor of HO activity, resulted in a significant decrease in HO activity and exacerbated tissue inflammation and apoptotic cell death as judged by the marked increase in expression of TNF-alpha and iNOS, and in activated caspase-3-positive cells, and the significant reduction in Bcl-2 expression, respectively. These findings indicate that HO-1 induction is an adaptive response to HSR-induced oxidative stress and is essential for protecting tubular epithelial cells from oxidative damage through its anti-inflammatory and anti-apoptotic properties.

Responses to surgical stress after esophagectomy: Gene expression of heat shock protein 70, toll-like receptor 4, tumor necrosis factor-α and inducible nitric oxide synthase.

The progression and interrelationship of mediators that are released, activated or suppressed after major surgery appear to play an important role in responses to surgical stress. Heat shock protein 70 (HSP70) is stress-induced and acts like a cytokine to modulate pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS), by stimulating toll-like receptor 4 (TLR4) signaling. We hypothesized that this effect would occur after major surgery, such as esophagectomy. We therefore measured the expression of HSP70, TLR4, TNF-α and iNOS mRNA in peripheral blood mononuclear cells (PBMCs) from 11 patients who underwent esophagectomy with thoracoabdominal procedures at postoperative day (POD) 1 and POD3 using real-time polymerase chain reaction, and compared the results to expression levels in 6 healthy adult volunteers (controls). We also measured plasma cortisol as a well-known stress hormone. The expression of HSP70 mRNA in PBMCs was 2.1-fold higher on POD1 compared to the controls (P=0.041) and was positively correlated with TLR4 mRNA (r2=0.45, P=0.0007). The expression of TNF-α mRNA tended to be lower on POD1 (P=0.055) and was significantly decreased on POD3 (P=0.016), and iNOS mRNA were significantly lower on POD1 (P=0.0015) and POD3 (P=0.0003) compared to the controls. Moreover, there was a positive correlation between the expression of TLR4 mRNA and plasma cortisol levels (r2=0.24, P=0.021). The expression of HSP70 mRNA in PBMCs in the early postoperative period was significantly higher and positively correlated with TLR4 mRNA. This suggests that HSP70-TLR4 signaling has an important role in postoperative inflammatory responses. However, the expression of pro-inflammatory mediators, including TNF-α and iNOS mRNA, was significantly decreased postoperatively. This may be caused by the anti-inflammatory mechanism of cortisol. Our findings indicate that responses to surgical stress reflect simultaneous pro-inflammatory and anti-inflammatory responses, and are complex.

Prevention of hemorrhagic shock-induced intestinal tissue injury by glutamine via heme oxygenase-1 induction.

Hemorrhagic shock (HS) is an oxidative stress that causes intestinal tissue injury. Heme oxygenase 1 (HO-1) is induced by oxidative stress and is thought to play an important role in the protection of tissues from oxidative injury. We previously reported the ileum to be the most susceptible to HS-induced tissue injury site in the intestine because HO-1 induction is the lowest at this site. We also previously demonstrated that glutamine (GLN) significantly induced HO-1 in the lower intestinal tract. In the present study, we investigated whether GLN pretreatment improves HS-induced intestinal tissue injury in the ileum by HO-1 induction. Treatment of rats with GLN (0.75 g/kg, i.v.) markedly induced functional HO-1 protein in mucosal epithelial cells in the ileum. Glutamine treatment before HS (MAP of 30 mmHg for 60 min) significantly ameliorated HS-induced mucosal inflammation and apoptotic cell death in the ileum, as judged by significant decreases in gene expression of TNF-alpha, iNOS, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1, myeloperoxidase activity, the number of infiltrated neutrophils, DNA fragmentation by in situ oligo ligation assay, and activated caspase-3 expression, and by increases in gene expression of IL-10 and Bcl-2. In contrast, treatment with tin mesoporphyrin, a specific inhibitor of HO activity, abolished the beneficial effect of GLN pretreatment. These findings indicate that GLN pretreatment significantly ameliorated tissue injury in the ileum after HS by inducing HO-1. Glutamine treatment may thus protect mucosal cells from HS-induced oxidative damage via the anti-inflammatory and antiapoptotic properties of HO-1.

Site-specific induction of intestinal hypoxia-inducible factor-1α after hemorrhagic shock.

The intestine is a major target organ in hemorrhagic shock (HS)-induced tissue injury. Hypoxia-inducible factor (HIF)-1α is the primary transcription factor responsible for regulating cellular response to changes in oxygen tension. Since HS is an acute hypoxic insult, the present study examined changes in the gene expression of HIF-1α in various regions of the intestine, as well as the distribution of HIF-1α protein in the intestinal cells of a rat model of HS. Levels of HIF-1α mRNA were marginally detectable in the intestine of sham-operated control animals, but obviously induced following HS. Duodenal, jejunal and colonic levels of HIF-1α mRNA robustly increased and reached a maximum during the ischemic phase of HS, followed by a rapid decrease almost to control levels during the early phase of resuscitation. The induction of HIF-1α mRNA was maximal in the duodenum. In contrast to the duodenum, jejunum and colon, in the ileum the HIF-1α mRNA level did not increase after HS. Consistent with enhanced HIF-1α gene expression, HIF-1α protein was expressed in the mucosal cells of the duodenum, jejunum and colon, but not in the ileum following HS. These findings indicate that intestinal HIF-1α expression was up-regulated at both the transcriptional and protein level in a site-specific manner in this rat model of HS. Differential regulation of HIF-1α expression along the longitudinal axes of the intestine might be a determinant of the adaptive response to HS-induced intestinal damage.

Protective role of heme oxygenase 1 in the intestinal tissue injury in hemorrhagic shock in rats.

Heme oxygenase (HO) 1 is inducible by a variety of oxidative stress and is thought to play an important role in the protection of tissues from oxidative injuries. Because hemorrhagic shock (HS) is an oxidative stress that results in tissue injury, we examined in this study the role of HO-1 induction in intestinal tissue injuries in a rat model of HS. The levels of HO-1 were significantly increased after HS both at transcriptional and protein levels in mucosal epithelial cells in the duodenum, jejunum, and colon, whereas their expression in the ileum was hardly detectable and not increased at all by the treatment. In contrast, HS-induced mucosal inflammation and apoptotic cell death in the duodenum, jejunum, and colon were far less than those observed in ileum as judged by the levels of expression of TNF-alpha, iNOS, activated caspase 3, and Bcl-2. Of note, inhibition of HO activity by tin-mesoporphyrin resulted in an aggravation of HS-induced tissue inflammation and apoptotic cell death. These findings indicate that HO-1 expression in the intestine is regulated in a highly site-specific manner after HS, and that HO-1 induction plays a fundamental role in protecting mucosal cells of the intestine from oxidative damages induced by HS.

A neutrophil elastase inhibitor, sivelestat, ameliorates lung injury after hemorrhagic shock in rats.

Hemorrhagic shock followed by resuscitation (HSR) causes neutrophil sequestration in the lung which leads to acute lung injury (ALI). Neutrophil elastase (NE) is thought to play a pivotal role in the pathogenesis of ALI. This study investigated whether sivelestat, a specific NE inhibitor, can attenuate ALI induced by HSR in rats. Male Sprague-Dawley rats were subjected to hemorrhagic shock by withdrawing blood so as to maintain a mean arterial blood pressure of 30+/-5 mm Hg for 60 min followed by resuscitation with the shed blood. HSR-treated animals received a bolus injection of sivelestat (10 mg/kg) intravenously at the start of resuscitation followed by continuous infusion for 60 min (10 mg/kg/h) during the resuscitation phase, or the vehicle. Lung injury was assessed by pulmonary histology, lung wet-weight to dry-weight (W/D) ratio, myeloperoxidase (MPO) activity, gene expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS), DNA binding activity of nuclear factor (NF)-kappaB, and immunohistochemical analysis of intercellular adhesion molecule (ICAM)-1. HSR treatment induced lung injury, as demonstrated by pulmonary edema with infiltration of neutrophils, the increase in lung W/D ratio, MPO activity, gene expression of TNF-alpha and iNOS, and DNA-binding activity of NF-kappaB, and enhanced expression of ICAM-1. In contrast, sivelestat treatment significantly ameliorated the HSR-induced lung injury, as judged by the marked improvement in all these indices. These results indicate that sivelestat attenuated HSR-induced lung injury at least in part through an inhibition of the inflammatory signaling pathway, in addition to the direct inhibitory effect on NE.

Prevention of hemorrhagic shock-induced lung injury by heme arginate treatment in rats.

Hemorrhagic shock followed by resuscitation (HSR) induces oxidative stress, which leads to acute lung injury. Heme oxygenase (HO)-1 (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is inducible by oxidative stress and is thought to play an important role in the protection from oxidative tissue injuries. In this study, we examined expression of HO-1 as well as tissue injuries in the lung, liver, and kidney after HSR in rats. We also pretreated animals with heme arginate (HA), a strong inducer of HO-1, and examined its effect on the HSR-induced lung injury. HO-1 expression significantly increased in the liver and kidney following HSR, while its expression in the lung was very low and unchanged after HSR. In contrast to HO-1 expression, tissue injury and tumor necrosis factor-alpha (TNF-alpha) gene expression was more prominent in the lung compared with those in the liver and kidney. HA pretreatment markedly induced HO-1 in pulmonary epithelial cells, and ameliorated the lung injury induced by HSR as judged by the improvement of histological changes, while it decreased TNF-alpha and inducible nitric oxide synthase gene expression, lung wet weight to dry weight ratio, and myeloperoxidase activity. In contrast, inhibition of HO-1 by tin-mesoporphyrin administration abolished the beneficial effect of HA pretreatment. These findings suggest that tissues with higher HO-1 may be better protected than those with lower HO-1 from oxidative tissue injury induced by HSR. Our findings also indicate that HA pretreatment can significantly suppress the HSR-induced lung injury by virtue of its ability to induce HO-1.

The lower intestinal tract-specific induction of heme oxygenase-1 by glutamine protects against endotoxemic intestinal injury.

OBJECTIVE: The aim of the present study was to investigate whether glutamine pretreatment improves intestinal injury in rats with endotoxemia by its heme oxygenase-1 induction in the lower intestinal tract. DESIGN: Randomized, blinded, controlled animal study. SETTING: University-based animal research facility. SUBJECTS: Sprague-Dawley male rats, weighing 220-250 g (n = 201). INTERVENTIONS: Rats were treated with glutamine (0.75 g/kg) dissolved in lactated Ringer's solution via the tail vein. Endotoxemia was induced in rats by intraperitoneal injection of lipopolysaccharide (10 mg/kg or 20 mg/kg for survival study). Lipopolysaccharide-treated animals were pretreated with glutamine or lactated Ringer's solution 9 hrs before lipopolysaccharide treatment. Some of the glutamine-pretreated animals further received tin mesoporphyrin (1 micromol/kg), a specific inhibitor of heme oxygenase activity, 1 hr before lipopolysaccharide treatment. MEASUREMENTS AND MAIN RESULTS: Glutamine treatment markedly induced heme oxygenase-1 messenger RNA and protein in the mucosal epithelial cells as well as in the lamina propria cells in the ileum and the colon, whereas its expression in the duodenum and the jejunum was not influenced by the treatment. Glutamine treatment before lipopolysaccharide administration significantly ameliorated lipopolysaccharide-induced mucosal injury, inflammation, and apoptotic cell death in the ileum and the colon, as judged by significant decreases in tumor necrosis factor-alpha gene expression, histologic damage scores, and expression of activated caspase-3 and by an increase in gene expression of Bcl-2. In addition, glutamine treatment markedly decreased lipopolysaccharide-induced mortality. In contrast, treatment with tin mesoporphyrin abolished the beneficial effect of glutamine pretreatment. CONCLUSIONS: Glutamine pretreatment significantly ameliorated intestinal tissue injury of rats following lipopolysaccharide treatment. The same treatment also improved the survival of animals from endotoxemia. The protective effect of glutamine is mediated by its lower intestine-specific induction of heme oxygenase-1, since its inhibition by tin mesoporphyrin completely abolished the beneficial effect of glutamine.