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 SnCl_₂ 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 SnCl_₂ 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, SnCl_₂-pretreated rats showed no significant increase in the indices. However, additional treatment of SnMP abolished the beneficial effect of SnCl_₂. 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.

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-1β genes, and the expression of interleukin-1β 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.

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.

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.

TAK1 kinase determines TRAIL sensitivity by modulating reactive oxygen species and cIAP

TNF-related apoptosis-inducing ligand (TRAIL) is a potent inducer of cell death in several cancer cells, but many cells are resistant to TRAIL. The mechanism that determines sensitivity to TRAIL-killing is still elusive. Here we report that deletion of TAK1 kinase greatly increased activation of caspase-3 and induced cell death following TRAIL stimulation in keratinocytes and fibroblasts as well as cancer cells. Although TAK1 kinase is involved in NF-κB pathway, ablation of NF-κB did not alter sensitivity to TRAIL. We found that TRAIL could induce accumulation of reactive oxygen species (ROS) when TAK1 was deleted. Furthermore, we found that TAK1 deletion induces TRAIL-dependent downregulation of cIAP, which enhances activation of caspase-3. These results demonstrate that TAK1 deletion facilitates TRAIL-induced cell death by activating caspase through ROS and downregulation of cIAP. Thus, inhibition of TAK1 can be an effective approach to increase TRAIL sensitivity.

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.

Site- and cell-type- specific induction of intestinal inducible nitric oxide synthase in a rat model of endotoxemia

The intestine is one of the major organs that are involved in sepsis. The inducible isoform of nitric oxide synthase (iNOS) is known to play a critical role in the pathogenesis of septic tissue injury by generating excess amount of nitric oxide (NO) in response to cytokines and endotoxin. In this study, we examined changes in gene expression of iNOS in various regions of the intestine as well as the distribution of iNOS protein in the intestinal cells in a rat model of endotoxemia produced by intraperitoneal injection of lipopolysaccharide (LPS; 10 mg/kg). While iNOS mRNA was undetectable in the intestine of untreated control animals, it underwent marked induction following LPS treatment. Induction of iNOS mRNA in the ileum was marked and biphasic, while it was also marked but monophasic in the jejunum. The induction of iNOS mRNA was maximal in the ileum. The administration of interleukin-6 (IL-6) upregulated intestinal iNOS gene expression specifically in the ileum. Consistent with enhanced iNOS gene expression, iNOS protein was markedly expressed in the ileum after LPS treatment, exclusively in the mucosal epithelium both at crypt and villus cells, although more prominently in the former. These findings suggested that intestinal iNOS expression was upregulated both at transcriptional and protein levels not only in a site-specific, but also in a cell type-specific manner in a rat model of endotoxemia, possibly through increasing serum IL-6 levels. Differential regulation of iNOS expression along the longitudinal and crypt-villus axes of the gut might be a determinant of the pattern of sepsis-induced intestinal damage.

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.