Keita Terui

Stat3 protects against Fas-induced liver injury by redox-dependent and -independent mechanisms

Signal transducer and activator of transcription-3 (Stat3) is one of the most important molecules involved in the initiation of liver development and regeneration. In order to investigate the hepatoprotective effects of Stat3, we examined whether Stat3 protects against Fas-mediated liver injury in the mouse. A constitutively activated form of Stat3 (Stat3-C) was adenovirally overexpressed in mouse liver by intravenous injection, and then a nonlethal dose of Fas agonist (Jo2) was injected intraperitoneally into the mouse (0.3 microg/g body wt). Stat3-C dramatically suppressed both apoptosis and necrosis induced by Jo2. In contrast, liver-specific Stat3-knockout mice failed to survive following Jo2 injection. Stat3-C upregulated expression of FLICE inhibitor protein (FLIP), Bcl-xL, and Bcl-2, and accordingly downregulated activities of FLICE and caspase-3 that were redox-independent. Interestingly, Stat3-C also upregulated the redox-associated protein redox factor-1 (Ref-1) and reduced apoptosis in liver following Jo2 injection by suppressing oxidative stress and redox-sensitive caspase-3 activity. These findings indicate that Stat3 activation protects against Fas-mediated liver injury by inhibiting caspase activities in redox-dependent and -independent mechanisms.

Preventing hypoxia/reoxygenation damage to hepatocytes by p66shc ablation : Up-regulation of anti-oxidant and anti-apoptotic proteins

BACKGROUND/AIMS Ischemia/reperfusion damage to the liver remains a serious concern in many clinical situations. Major mechanisms for this certainly include oxidative stress. METHODS The effects of ablating the p66 isoform of ShcA (p66(shc)) on hypoxia/reoxygenation (H/R)-induced oxidative stress and cell injury in hepatocytes were investigated. RESULTS Immediately after reoxygenation, AML12 cells were clearly under oxidative stress; many cells underwent apoptosis. However, knockdown of p66(shc) by specific RNAi markedly decreased cellular oxidative stress and H/R-induced apoptosis, as well as conferring resistance to H(2)O(2) insult. These data suggest that prevention of apoptosis conferred by ablation of p66(shc) results from changed ROS-scavenging, but not inhibition of ROS generation. These data were also confirmed in fibroblasts from p66(shc) knockout mice. Anti-oxidant molecules, such as MnSOD and Ref-1 and the anti-apoptotic molecule Bcl-xL were up-regulated, and pro-apoptotic FLICE was down-regulated, by ablation of p66(shc). Interestingly, catalase expression was not affected in p66(shc)-knockdown-AML12 cells although it is a major target in other cell types. CONCLUSIONS Our findings suggest that in hepatocytes, ablation of p66(shc) is cytoprotective against H/R-induced oxidative stress, with MnSOD and Ref-1 playing critical roles, and with up-regulation of Bcl-xL and down-regulation of FLICE contributing jointly to preventing cells from undergoing oxidant-induced apoptosis.

Hypoxia/re-oxygenation-induced, redox-dependent activation of STAT1 (signal transducer and activator of transcription 1) confers resistance to apoptotic cell death via hsp70 induction

STAT1 (signal transducer and activator of transcription 1) is potentially involved in cell survival, as well as cell death, in different types of cells. The present study was designed to examine the effects of STAT1 on hypoxia/re-oxygenation (H/R)-induced cell death and/or survival, and the underlying mechanisms of any such effects. H/R was shown to induce apoptotic cell death of rat hepatocytes. The addition of a STAT1-specific inhibitor, fludarabine, significantly increased the fraction of apoptotic cells after H/R. Following H/R, STAT1 was activated and sequential phosphorylation of Tyr701 and Ser727 was observed, which could be inhibited by the antioxidant N-acetyl-L-cysteine. Tyrosine and serine phosphorylation of STAT1 was mediated by Janus kinase 2 and phosphoinositide 3-kinase/Akt kinase respectively in a redox-dependent manner following H/R. STAT1-induced HSP70 (heat-shock protein 70) expression and the suppression of apoptosis occurred concomitantly. In conclusion, STAT1 activation, in a redox-dependent manner, following H/R may play crucial roles in cell survival, at least partly via HSP70 induction.

Induction of Wnt5a -Expressing Mesenchymal Cells Adjacent to the Cloacal Plate Is an Essential Process for Its Proximodistal Elongation and Subsequent Anorectal Development

Anorectal malformations encompass a broad spectrum of congenital defects and are related to the development of the genital tubercle, including the cloacal plate and urorectal septum. To explore the cellular and molecular basis of anorectal malformations, we analyzed the pathogenetic process using two mouse models: Danforths short tail (Sd) and all-trans retinoic acid (ATRA)-treated mice. Embryologically, the cloacal plate may be divided into distal and proximal parts, with the distal part subdivided into ventral and dorsal parts. In the two mouse models, anorectal malformations occur due to improper development of the proximal part of the cloacal plate. At 10.5 days postcoitus (dpc), in Sd homozygotes, there was a lack of Shh expression only in the cloacal plate and the endoderm around the cloacal plate. In addition, Wnt5a was not expressed in the mesoderm adjacent to the cloacal plate in the two mouse models, and Axin2, which is regulated by Wnt signaling, was not expressed in the dorsal part of the cloacal plate at 12.5 dpc. Based on these results, we suggest that Wnt5a, which is downstream of Shh signaling, and Axin2 affect the development of the proximal part of the cloacal plate.

Role of pediatric endoscopic retrograde cholangiopancreatography in an era stressing less-invasive imaging modalities.

Background:The significance of pediatric endoscopic retrograde cholangiopancreatography (ERCP) according to age or disease variation is inconclusive. This study aimed to evaluate the usefulness of pediatric ERCP in diagnosing or treating small children with pancreaticobiliary disorders, including choledochal cyst (CC) and biliary atresia (BA). Methods:From 1980 to 2011, 235 ERCPs were performed in 220 pediatric patients (median age, 2 years) at our institution. Underlying pathology was CC in 92 patients (3 years), BA in 62 patients (55 days), and others in 66 patients. Success and complication rates, and ERCP findings were retrospectively analyzed. Results:The overall success rate was 96%. Rates for individual pathologies were 99% for CC, 92% for BA, and 96% for others. The success rate was 100% among children >3 years, but 92% when limited to infants. Post-ERCP hyperamylasemia and duodenal perforation occurred in 9% and 0.4% of cases, respectively. Regarding preoperative evaluation of the pancreaticobiliary system in CC, ERCP clearly delineated pancreaticobiliary maljunction (79%) and the pancreatic duct (94%), whereas it visualized the common bile duct and intrahepatic bile duct at relatively low rates (77% and 33%, respectively). ERCP successfully identified 16 cases (18%) with non-BA of 90 patients with suspected BA. Moreover, ERCP demonstrated only pancreatic duct in 70% of all BA. Conclusions:ERCP among children including infants with CC and BA can be performed with fairly satisfactory results. Although pediatric ERCP can also help describe the pancreaticobiliary system in detail, its indication should be deliberately considered when anatomical information from less-invasive imaging modalities is insufficient.

Risk Factors for the Recurrence of the Congenital Diaphragmatic Hernia—Report from the Long-Term Follow-Up Study of Japanese CDH Study Group

AIM OF THE STUDY Few follow-up studies focused on the recurrence regarding the postoperative course of congenital diaphragmatic hernia (CDH) survivors. The aim of this study was to report on risk factor for CDH patients who had the recurrence during the follow-up. MATERIALS AND METHODS A multicenter retrospective survey was conducted on neonates diagnosed to have CDH between January 2006 and December 2010. Follow-up survey was conducted between September 2013 and October 2013 (ethical approval: No. 25-222). Nine institutions agreed to participate in this survey. Out of 228, 182 (79.8%) patients were alive and 180 patients were included in this study. Two patients were excluded because the defect had not repaired at the primary operation. The patients were divided into the recurrence group (n=21) and the nonrecurrence group (n=159). Postnatal and postoperative variables were compared between these two groups. Baseline variables which showed significance in univariate analysis were entered into multiple logistic regression analysis for analyzing the recurrence. A value of p<0.05 was considered to be statistically significant by using the JMP software program (version 9; SAS Institute, Inc, Cary, North Carolina, United States). MAIN RESULTS Out of 180, 21 (11.7%) CDH neonates had the recurrence during the course of the follow-up. Five (2.8%) patients had the recurrence before primary discharge and 16 (8.9%) patients had the recurrence after discharge. Univariate analysis showed that liver herniation (crude odds ratio [OR], 7.4; 95% confidence interval [CI], 2.73-23.68), defect size C and D, proposed by the CDH Study Group (crude OR, 7.09; 95% CI, 2.73-19.99) and patch repair (crude OR, 5.00; 95% CI, 1.91-14.70) were risk factors. Multivariate logistic regression analysis showed liver herniation (adjusted OR, 3.96; 95% CI, 1.01-16.92) was the risk factor for the recurrence. CONCLUSION A wide spectrum of the disease severity and the rarity of the disease mask the risk of the recurrence for CDH patients. This study showed the only factor to predict the recurrence was the liver herniation. These data will be helpful for providing information for the long-term follow-up of the CDH patients.

Endoscopic sphincterotomy is a useful preoperative management for refractory pancreatitis associated with pancreaticobiliary maljunction.

BACKGROUND Pancreatitis associated with pancreaticobiliary maljunction (PBM) is commonly treated nonoperatively before surgery. It is, however, sometimes uncontrollable, and little has been reported about the management. METHODS Focusing on the preoperative management, we reviewed clinical courses of 4 PBM cases (ages 1 to 7 years old). Each had pancreatitis that was totally resistant to medical treatment and was applied endoscopic sphincterotomy (ES). RESULTS The first case underwent percutaneous transhepatic catheter drainage (PTCD) primarily. In spite of daily lavage using the drainage tube for a week, plugs located in the common channel were not removed, and clinical findings were not improved. Therefore, ES followed by removal of protein plugs was performed to improve pancreatitis dramatically. Through this experience, 3 subsequent cases with refractory pancreatitis all underwent successful ES primarily soon after the medical treatments turned out to be ineffective. In all 4 cases, protein plugs were impacted in common channels, and ES could successfully remove the plugs that were impossible to remove by using PTCD. Improved preoperative pancreaticobiliary decompression by ES shortens the duration of recalcitrant acute pancreatitis associated with PBM allowing for a subsequent safe operation. CONCLUSIONS Endoscopic sphincterotomy is one of the useful preoperative managements for refractory pancreatitis associated with PBM.

Endoscopic management for congenital esophageal stenosis: A systematic review

Congenital esophageal stenosis (CES) is an extremely rare malformation, and standard treatment have not been completely established. By years of clinical research, evidence has been accumulated. We conducted systematic review to assess outcomes of the treatment for CES, especially the role of endoscopic modalities. A total of 144 literatures were screened and reviewed. CES was categorized in fibromuscular thickening, tracheobronchial remnants (TBR) and membranous web, and the frequency was 54%, 30% and 16%, respectively. Therapeutic option includes surgery and dilatation, and surgery tends to be reserved for ineffective dilatation. An essential point is that dilatation for TBR type of CES has low success rate and high rate of perforation. TBR can be distinguished by using endoscopic ultrasonography (EUS). Overall success rate of dilatation for CES with or without case selection by using EUS was 90% and 29%, respectively. Overall rate of perforation with or without case selection was 7% and 24%, respectively. By case selection using EUS, high success rate with low rate of perforation could be achieved. In conclusion, endoscopic dilatation has been established as a primary therapy for CES except TBR type. Repetitive dilatation with gradual step-up might be one of safe ways to minimize the risk of perforation.

Use of preoperative, 3-dimensional magnetic resonance cholangiopancreatography in pediatric choledochal cysts

BACKGROUND Standard choledochal cyst (CC) operations involve dilated extrahepatic bile duct excision followed by biloenterostomy. However, biliary variants and associated intrahepatic bile duct (IHBD) stenoses or dilatations triggering postoperative sequelae require additional procedures. The usefulness of preoperative 3-dimensional magnetic resonance cholangiopancreatography (3D MRCP) and virtual cholangioscopy (VES) for observing biliary morphology and pancreaticobiliary maljunction (PBM) was evaluated. METHODS In 16 pediatric CC patients (age range, 4 months to 9 years; median, 3 years), visualization of PBM and aberrant bile duct anatomy and IHBD morphology at the hepatic hilum (HH), umbilical portion (UP), and posterior branch (POST) were compared between 3D-MRCP and intraoperative cholangiography (IOC). VES and intraoperative cholangioscopy (IOS) findings were compared. RESULTS HH, UP, and POST visualization rates were 100%, 94%, and 94%, respectively, by 3D-MRCP, and 100%, 69%, and 69%, respectively, by IOC. IHBD stenosis detection rates at each region were 38%, 13%, and 13%, respectively, by 3D-MRCP, and 25%, 0%, and 9%, respectively, by IOC. IHBD dilatation detection rates at each part were 75%, 47%, and 60%, respectively, by 3D-MRCP, and 88%, 82%, and 91%, respectively, by IOC. PBM was confirmed in 56% and 93% of cases on 3D-MRCP and IOC, respectively. Both 3D-MRCP and IOC showed biliary variants in 5 cases (31%). VES showed membranous strictures at HH, UP, and POST in 6, 2, and 2 cases, respectively, whereas IOS did so at HH in 4 cases and POST in 2. CONCLUSION Preoperative 3D-MRCP and VES accurately depict biliary morphology, allowing concrete operative planning in pediatric CC patients, complementing IOC and IOS.

Prediction of postnatal outcomes in congenital diaphragmatic hernia using MRI signal intensity of the fetal lung.

Objective:Prognostic prediction in prenatally diagnosed congenital diaphragmatic hernia (CDH) is needed. The aim of the study was to evaluate magnetic resonance imaging (MRI) signal intensity of the fetal lung as a predictor of prognosis in CDH.Study Design:The subjects consisted of 12 fetuses with prenatally diagnosed CDH, who were treated soon after the birth in our institution. They all underwent MRI at 29 to 37 weeks of gestation. The ratio of the lung signal intensity to the spinal fluid signal intensity (L/SF) was calculated using region-of-interest analysis of T2-weighted images. The relationship between L/SF and clinical data was then examined.Result:L/SF were significantly larger in survivors compared with deaths (0.815 vs 0.614, P<0.05). In survivors, L/SF significantly correlated with duration of tracheal intubation (rs=−0.938, P<0.01).Conclusion:L/SF is a unique factor to predict the survival prognosis and likely to quantify the degree of pulmonary hypoplasia in CDH.