Hiromi Fujii

Protective role of heme oxygenase-1 induction in carbon tetrachloride-induced hepatotoxicity.

Reductive metabolism of carbon tetrachloride (CCl(4)) is thought to cause lipid peroxidation which results in hepatic injury. Heme oxygenase-1 (HO-1) (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is known to be induced by oxidative stress and to confer protection against oxidative tissue injuries. In this study, we examined the role of HO-1 induction in a rat model of CCl(4)-induced acute liver injury. CCl(4) treatment (1 mL/kg, intraperitoneally) produced severe hepatic injury in rats as revealed by significant increases in serum alanine transaminase (ALT) (EC 2.6.1.2) activity and hepatic malondialdehyde (MDA) content, severe liver cell injury, and increases in hepatic tumor necrosis factor-alpha (TNF-alpha) mRNA expression and DNA binding activity of nuclear factor-kappa B (NF-kappa B). Following CCl(4) treatment, hepatic HO-1 expression was markedly increased both at transcriptional and protein levels in hepatocytes, especially around the central vein. HO-1 induction was mediated in part through a rapid increase in microsomal free heme concentration presumably derived from hepatic cytochrome P450. Inhibition of HO activity by tin-mesoporphyrin (Sn-MP), which resulted in a sustained increase in microsomal free heme concentration, exacerbated liver injury, as judged by the sustained increase in serum ALT activity, extensive hepatocytes injuries, a more pronounced expression of hepatic TNF-alpha mRNA and an enhanced NF-kappa B activation. These findings indicate that induction of HO-1 is an adaptive response to CCl(4) treatment, and it may be critical in the recovery of hepatocytes from injury. Our findings also suggest that HO-1 induction may play an important role in conferring protection on hepatocytes from oxidative damage caused by free heme.

Protective role of heme oxygenase-1 in the intestinal tissue injury in an experimental model of sepsis.

ObjectiveThe aim of this study was to examine the role of heme oxygenase-1 induction in the intestinal tissue injury in a rat model of sepsis. DesignRandomized, masked, controlled animal study. SettingUniversity-based animal research facility. SubjectsSprague-Dawley male rats, weighing 220–250 g (n = 126). InterventionsRats were injected with lipopolysaccharide (10 mg/kg) intraperitoneally. Another group of rats was injected with interleukin-6 (10 &mgr;g/kg) intravenously. In some rats, tin mesoporphyrin (1 &mgr;mol/kg) was administered intravenously 1 hr before lipopolysaccharide treatment. Measurements and Main ResultsFollowing lipopolysaccharide treatment, expression of heme oxygenase-1 and nonspecific &dgr;-aminolevulinate synthase (ALAS-N), the rate-limiting enzymes of heme catabolism and biosynthesis, respectively, was examined in various regions of the intestine. Lipopolysaccharide treatment markedly increased heme oxygenase-1 messenger RNA and protein concentrations in the mucosal epithelial cells in the duodenum and the jejunum, whereas its expression in the ileum and the colon was hardly detectable and was not influenced by the treatment. ALAS-N messenger RNA was also more markedly increased in the duodenum, the jejunum, and the ileum than in the colon following lipopolysaccharide treatment. Interleukin-6 administration also induced heme oxygenase-1 and ALAS-N gene expression in a pattern similar to that following lipopolysaccharide treatment. In contrast to the marked heme oxygenase-1 expression in the upper intestine, lipopolysaccharide-induced mucosal injury and inflammation in the upper intestine were far less than observed in the lower intestine as judged both by tumor necrosis factor-&agr; gene expression and by histologic analysis. Of note, inhibition of heme oxygenase activity by tin mesoporphyrin produced a significant tissue injury in the upper intestine of the lipopolysaccharide-treated animals. ConclusionsIntestinal heme oxygenase-1 and ALAS-N gene expression was regulated in a site-specific manner in a rat model of sepsis. Our findings also suggest that heme oxygenase-1 induction may play a fundamental role in protecting mucosal epithelial cells of the intestine from oxidative damages that occur in sepsis.

Correlation between the Distribution of Contrast Medium and the Extent of Blockade during Epidural Anesthesia

Background: If the epidural spread of contrast medium can be well correlated with the spread of local anesthetics, epidurography can predict the dermatomal distribution of the anesthetic block. The authors evaluated the relation between radiographic and analgesic spread. Methods: An epidural catheter was inserted in 90 patients, and predicted catheter tip position was recorded. The analgesic area was determined by pinprick after a 5-ml injection of 1.5% lidocaine, and epidurography was performed after a 5-ml injection of 240 mg I/ml iotrolan. Patients were assigned to three groups according to catheter tip position (group C: C–T4; group T: T5–T10; group L: T11–L), and patterns of spread were compared. In 16 of 90 subjects, radiographic and analgesic spread was further investigated after an additional 5-ml injection of iotrolan and lidocaine. Results: The total radiographic spread correlated well with analgesic spread (right side: Y = 0.84 X + 0.16, r = 0.92, P < 0.01; left side: Y = 0.78 X + 0.45, r = 0.91, P < 0.01). The mean radiographic spread in the cephalad and caudal directions from the catheter tip also correlated well with mean analgesic spread (r = 0.97, P < 0.01, each direction). The mean distance between the predicted catheter tip and radiographically determined positions was 1.0 ± 0.8 segments: the value in group T was significantly larger than that in groups C (P < 0.05) and L (P < 0.01). Although the correlation of radiographic spread with age was statistically significantly (r = 0.39, P < 0.01), great individual variation in spreading pattern was seen. In 16 subjects, mean radiographic spread correlated well with analgesic spread after 5- and 10-ml injections of iotrolan and lidocaine. Conclusions: Epidurography is useful to indicate epidural catheter position and can help to predict the exact dermatomal distribution of analgesic block.

Tin chloride pretreatment prevents renal injury in rats with ischemic acute renal failure.

Objective To investigate whether tin chloride pretreatment ameliorates renal injury in rats with ischemic acute renal failure (IARF) by virtue of its kidney-specific heme oxygenase-1 induction. Design Randomized, masked, controlled animal study. Setting University-based animal research facility. Subjects Sprague-Dawley male rats, weighing 200–230 g (n = 359). Interventions Rats were injected with tin chloride subcutaneously, because subcutaneous administration of tin chloride is known to specifically and potently induce renal heme oxygenase activity in the rat. Anesthetized rats were subjected to bilateral flank incisions, and the right kidney was removed. Renal ischemia for 40 mins was performed by left renal microvascular clamping, followed by reflow of the blood. Measurements and Main Results Tin chloride treatment specifically induced heme oxygenase-1 mRNA and protein in the proximal tubular epithelial cells of the kidney without apparent cell injury in the rat. Tin chloride treatment before renal ischemia augmented the induction of heme oxygenase-1 in IARF rats at both transcriptional and protein concentrations in the renal epithelial cells compared with IARF animals. Tin chloride pretreatment, which decreased microsomal heme concentration, ameliorated the ischemic renal injury as judged by the significant decrease in serum creatinine and blood urea nitrogen concentrations and the lesser tubular epithelial cell injuries. In contrast, inhibition of heme oxygenase activity by treatment with tin mesoporphyrin, which increased microsomal heme concentration, abolished the beneficial effect of tin chloride pretreatment. Conclusion These findings indicate that tin chloride pretreatment significantly ameliorates renal injury in rats with IARF by virtue of its specific heme oxygenase-1 induction in renal epithelial cells. These findings also suggest that heme oxygenase-1 induction plays an important role in protecting renal cells from oxidative damage caused by heme.

Increased Carbon Monoxide Concentration in Exhaled Air After Surgery and Anesthesia

Heme oxygenase-1 (HO-1) is induced by oxidative stress and is thought to confer protection against oxidative tissue injuries. HO-1 catalyzes the conversion of the heme moiety of hemeproteins, such as hemoglobin, myoglobin, and cytochrome P450, to biliverdin, liberating carbon monoxide (CO) in the process. CO reacts with hemoglobin to form carboxyhemoglobin. In this study, to examine the effect of anesthesia and/or surgery on endogenous CO production, we measured the amount of exhaled CO and the arterial carboxyhemoglobin concentration of patients who underwent surgery under general or spinal anesthesia. Both CO and carboxyhemoglobin concentrations were significantly larger on the day after surgery than during the preoperative period (P <0.05) and in the recovery room (P < 0.05), regardless of anesthesia. However, neither index differed between general and spinal anesthesia. These results suggest that oxidative stress caused by anesthesia and/or surgery may induce HO-1, which catalyzes heme to produce CO, leading to increased exhaled CO concentration.

A protective role of interleukin 11 on hepatic injury in acute endotoxemia

The liver is one of the major target organs affected in sepsis, and its failure always results in critical consequences. It has been reported that recombinant human interleukin 11 (rhIL-11), a pleiotropic cytokine, may be useful in the treatment of sepsis. However, the effect of IL-11 specifically on the hepatic failure in sepsis has not been evaluated. In the present study, we examined the effect of rhIL-11 on the hepatic injury in a rat endotoxemia model. Acute endotoxemia was induced in male Sprague-Dawley rats by intraperitoneal injection (i.p.) of bacterial lipopolysaccharide (LPS, 20 mg/kg). Immediately after injection of LPS, rats were treated with rhIL-11 (150 &mgr;g/kg, i.p.) or the vehicle. LPS treatment induced severe hepatic injury as revealed by marked increases in serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, extensive hepatocyte necrosis, tumor necrosis factor-&agr; (TNF-&agr;) mRNA, inducible nitric oxide synthase (iNOS) mRNA, and DNA-binding activity of nuclear factor-&kgr;B (NF-&kgr;B). In contrast, rhIL-11 treatment significantly ameliorated the LPS-induced hepatic injury, as judged by marked improvement in all these indices. In addition, rhIL-11 treatment markedly decreased LPS-induced mortality. These results indicate that rhIL-11 plays a significant protective role in LPS-induced hepatic injury in acute endotoxemia.

Increased heme oxygenase-1 gene expression in the livers of patients with portal hypertension due to severe hepatic cirrhosis

Surgical bleeding associated with splanchnic hyperaemia due to portal hypertension complicates the anaesthetic management of hepatic transplantation. Although the mechanism(s) of portal hypertension are not fully understood, carbon monoxide, a product of the heme oxygenase (HO) reaction, is thought to be one of the endogenous vasodilators in the liver. In this study, the expression of mRNA encoding inducible HO isozyme (HO-1) in the livers of patients with portal hypertension undergoing hepatic transplantation was determined in comparison with those without portal hypertension. HO-1 mRNA levels were significantly greater in the portal hypertension group than in the group without portal hypertension. In contrast with HO-1, the gene expression of non-specific δ-aminolevulinate synthase (ALAS-N), which is down-regulated by heme in the liver, was the same in both groups. These results suggest that HO-1 is up-regulated through heme-independent stimuli according to the development of portal hypertension, and that induced HO-1 plays a pathophysiological role in portal hypertension through carbon monoxide production.

An adult with ARDS managed with high-frequency oscillatory ventilation and prone position

tion. The preoperative chemotherapy had been started 11 days before the operation and had finished 9 days before the operation. On the first postoperative day, a chest radiograph revealed bilateral infiltrates, and he was diagnosed as having acute lung injury (ALI), or ARDS, according to the definition of the American-European consensus conference on ARDS [7]. On the second postoperative day, marked neutropenia was observed (neutrophils, 200/μl; leukocytes, 1800/μl), and granulocyte colonystimulating factor (G-CSF; 75μg/day) was administered subcutaneously for 2 days. On the third postoperative day, oxygenation and hemodynamics deteriorated after the second administration of G-CSF. One hour before the second administration of G-CSF, arterial oxygen tension (PaO2) was 73.3mmHg and arterial carbon dioxide tension (PaCO2) was 39.6 mmHg with pressure support ventilation; fractional inspired oxygen (FIO2) was 0.7, positive end-expiratory pressure (PEEP) was 7cmH2O, and pressure support, 18cmH2O (PaO2/FIO2 (P/F) ratio, 104.7). Two hours after the second G-CSF, PaO2 was 47.6mmHg and PaCO2 was 36.4mmHg with the same ventilator settings (P/F ratio, 68.0). Arterial blood pressure was 75/45mmHg, and central venous pressure was 15mmHg with dopamine, 5μg·kg 1·min 1 and dobutamine, 4 μg·kg 1·min 1. Although his hemodynamics improved with norepinephrine, 0.2μg·kg 1·min 1 and dopamine, 10μg·kg 1·min 1, urine output transiently decreased and continuous hemodiafiltration (CHDF) was started. Oxygenation did not improve and ventilation worsened in spite of the use of aggressive ventilator settings under conditions of sedation (continuous infusion of fentanyl and propofol) and muscle relaxation. PaO2 was 62.6 mmHg and PaCO2 was 52.4mmHg (pH 7.28) with pressure-controlled ventilation (PCV); FIO2, 1.0; PEEP, 10 cmH2O; distending pressure, 25 cmH2O; respiratory frequency, 30/min. This resulted in a tidal volume of 0.35 l, minute volume of 10.5 l/min, mean airway pressure (MAP) of 22.5 cmH2O,

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.