Ann Marie T Baine

Occludin is regulated by epidermal growth factor receptor activation in brain endothelial cells and brains of mice with acute liver failure.

Mechanisms of brain edema in acute liver failure (ALF) are not completely understood. We recently demonstrated that matrix metalloproteinase 9 (MMP‐9) induces significant alterations to occludin in brain endothelial cells in vitro and in brains of mice with experimental ALF (Hepatology 2009;50:1914). In this study we show that MMP‐9‐induced transactivation of epidermal growth factor receptor (EGFR) and p38 MAPK/NFκB (mitogen‐activated protein kinase/nuclear factor‐kappa B) signals participate in regulating brain endothelial occludin level. Mouse brain endothelial bEnd3 cells were exposed to MMP‐9 or p38 MAPK up‐regulation in the presence and absence of EGFR inhibitor, p38 MAPK inhibitor, NFκB inhibitor, and/or appropriate small interfering RNA. Reverse‐transcription polymerase chain reaction (RT‐PCR) and western blotting were used for messenger RNA and protein expression analyses. Immunohistochemical staining and confocal microscopy were used to demonstrate cellular EGFR activation. Intraperitoneal azoxymethane was use to induce ALF in mice. Brains of comatose ALF mice were processed for histological and biochemical analyses. When bEnd3 cells were exposed to MMP‐9, EGFR was significantly transactivated, followed by p38 MAPK activation, I‐kappa B alpha (IκBα) degradation, NFκB activation, and suppression of occludin synthesis and expression. Similar EGFR activation and p38 MAPK/NFκB activation were found in the brains of ALF mice, and these changes were attenuated with GM6001 treatment. Conclusion: EGFR activation with p38 MAPK/NFκB signaling contributes to the regulation of tight junction integrity in ALF. EGFR activation may thus play an important role in vasogenic brain edema in ALF. (HEPATOLOGY 2011;)

TIMP-1 attenuates blood-brain barrier permeability in mice with acute liver failure

Blood-brain barrier (BBB) dysfunction in acute liver failure (ALF) results in increased BBB permeability that often precludes the patients from obtaining a life-saving liver transplantation. It remains controversial whether matrix metalloproteinase-9 (MMP-9) from the injured liver contributes to the deregulation of BBB function in ALF. We selectively upregulated a physiologic inhibitor of MMP-9 (TIMP-1) with a single intracerebroventricular injection of TIMP-1 cDNA plasmids at 48 and 72 hours, or with pegylated-TIMP-1 protein. Acute liver failure was induced with tumor necrosis factor-α and D-(+)-galactosamine in mice. Permeability of BBB was assessed with sodium fluorescein (NaF) extravasation. We found a significant increase in TIMP-1 within the central nervous system (CNS) after the administration of TIMP-1 cDNA plasmids and that increased TIMP-1 within the CNS resulted in an attenuation of BBB permeability, a reduction in activation of epidermal growth factor receptor and p38 mitogen-activated protein kinase signals, and a restoration of the tight junction protein occludin in mice with experimental ALF. Pegylated TIMP-1 provided similar protection against BBB permeability in mice with ALF. Our results provided a proof of principle that MMP-9 contributes to the BBB dysfunction in ALF and suggests a potential therapeutic role of TIMP-1 in ALF.

Simple and reproducible hepatectomy in the mouse using the clip technique.

AIM To investigate the reliability of massive hepatectomy models by using clip techniques. METHODS We analyzed anatomical findings in 100 mice following massive hepatectomy induced by liver reduction > 70%. The impact of various factors in the different models was also analyzed, including learning curves, operative time, survival curves, and histopathological findings. RESULTS According to anatomical results, models with 75%, 80%, and 90% hepatectomy produced massive hepatectomy. Learning curves and operative times were most optimal with the clip technique. Each hepatectomy performed using the clip technique produced a reasonable survival curve, and there were no differences in histopathological findings between the suture and clip techniques. CONCLUSION Massive hepatectomy by the clip technique is simple and can provide reliable and relevant data.

Oxidative stress and extracellular matrices after hepatectomy and liver transplantation in rats

AIM To investigate oxidative stress (OS)-mediated damage and the behavior of extracellular matrices in various rat models because shear stress with portal hypertension and cold ischemia/warm reperfusion injury trigger the liver regeneration cascade after surgery. These injuries also cause fatal liver damage. METHODS Rats were divided into four groups according to the surgery performed: control; hepatectomy with 40% liver remnant (60% hepatectomy); orthotopic liver transplantation (OLT) with whole liver graft (100% OLT); and split OLT (SOLT) with 40% graft (40% SOLT). Survival was evaluated. Blood and liver samples were collected at 6 h after surgery. Biochemical and histopathological examinations were performed. OS-induced damage, 4-hydroxynonenal, ataxia-telangiectasia mutated kinase, histone H2AX, phosphatidylinositol 3-kinase (PI3K) and Akt were evaluated by western blotting. Behavior of extracellular matrices, matrix metalloproteinase (MMP)-9, MMP-2, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were also evaluated by western blotting and zymography. RESULTS Although 100% OLT survived, 60% hepatectomy and 40% SOLT showed poor survival. Histopathological, immunohistological, biochemical and protein assays revealed that 60% hepatectomy, 100% OLT and 40% SOLT showed liver damage. PI3K and Akt were decreased in 60% hepatectomy and 40% SOLT. For protein expression, 40% SOLT showed differences in MMP-9, MMP-2 and TIMP-2. TIMP-1 showed differences in 60% hepatectomy and 40% SOLT. For protein activity, MMP-9 demonstrated significant differences in 60% hepatectomy, 100% OLT and 40% SOLT. CONCLUSION Under conditions with an insufficient liver remnant, prevention of OS-induced damage via the Akt/PI3K pathway may be key to improve the postoperative course. MMP-9 may be also a therapeutic target after surgery.

Pretreatment of liver grafts in vivo by γ-aminobutyric acid receptor regulation reduces cold ischemia/warm reperfusion injury in rat.

BACKGROUND Gamma-aminobutyric acid (GABA) is found throughout the body. The regulation of GABA receptor (GABAR) reduces oxidative stress (OS). Ischemia/reperfusion injury after orthotopic liver transplantation (OLT) causes OS-induced graft damage. The effects of GABAR regulation in donors in vivo were investigated. MATERIAL AND METHODS Donor rats received saline, a GABAR agonist or GABAR antagonist 4 h before surgery. Recipient rats were divided into four groups according to the donor treatments: laparotomy, OLT with saline, OLT with GABAR agonist and OLT with GABAR antagonist. Histopathological, biochemical and immunohistological examinations were performed at 6, 12 and 24 h after OLT. Protein assays were performed at 6 h after OLT. The 4-hydroxynonenal (4-HNE), ataxia-telangiectasia mutated kinase (ATM), phosphorylated histone H2AX (gammaH2AX), phosphatidylinositol-3 kinase (PI3K), Akt and superoxide dismutase (SOD) were assessed by western blot analysis. RESULTS In the univariate analysis, histopathological and biochemical profiles verified that the GABAR agonist reduced graft damage. Immunohistology revealed that the GABAR agonist prevented the induction of apoptosis. Measurement of 4-4-HNE levels confirmed OS-induced damage after OLT, and the GABAR agonist improved this damage. In the gammaH2AX, PI3K, Akt and antioxidant enzymes (SODs), ATM and H2AX were greatly increased after OLT, and were reduced by the GABAR agonist. In the multivariate analyses between multiple groups, histopathological assessment, aspartate aminotransferase level, immunohistological examinations for apoptotic induction and gammaH2AX showed statistical differences. CONCLUSIONS A specific agonist demonstrated regulation of GABAR in vivo in the liver. This activation in vivo reduced OS after OLT via the ATM/H2AX pathway.

Effect of specific activation of γ‐aminobutyric acid receptor in vivo on oxidative stress‐induced damage after extended hepatectomy

Aim:  γ‐Aminobutyric acid (GABA) is a multifunctional molecule with various physiological effects throughout the body. The regulation of GABA receptor (GABAR) plays a key role in reducing the damage mediated by oxidative stress (OS). Extended hepatectomy causes fatal OS‐induced injury in the liver remnant. We aimed to investigate the effect of a GABAR agonist in extended hepatectomy.

Investigation of Endocytic Pathways for the Internalization of Exosome-Associated Oligomeric Alpha-Synuclein.

Misfolding and aggregation of alpha-synuclein (αsyn) resulting in cytotoxicity is a hallmark of Parkinsons disease (PD) and related synucleinopathies. The recent body of evidence indicates that αsyn can be released from neuronal cells by nonconventional exocytosis involving extracellular vesicles (EVs) such as exosomes. The transfer of αsyn between cells has been proposed to be an important mechanism of disease propagation in PD. To date, exosome trafficking mechanisms, including release and cell-cell transmission, have not been fully described. To gain insight into the mechanisms involved, exosomes were purified from conditioned media of stable cells secreting αsyn oligomers. A novel bimolecular protein complementation assay was used to detect exosomes containing αsyn oligomers. Recipient cells were treated with exosomes containing αsyn oligomers or “free” non-exosome-associated αsyn oligomers and internalization was monitored. We demonstrate that cell-derived exosome-associated αsyn oligomers can be efficiently internalized by recipient cells. Interestingly exosome-free αsyn oligomers isolated from conditioned medium were not internalized but remained bound to the extracellular surface. To investigate the endocytic pathway(s) required for the exosome uptake different pharmacological inhibitors of caveolin-dependent, clathrin-dependent, and macropinocytosis pathways were utilized. Surprisingly, none of these pathways appear to play a significant role in the internalization of exosome-associated αsyn oligomers. Finally, the role of heparin sulfate proteoglycans (HSPGs) in exosome-associated αsyn internalization was investigated using genetic approach. Despite previous studies showing HSPGs can modulate internalization of fibrillar αsyn, genetic manipulations did not attenuate internalization of exosome-associated αsyn oligomers in our hands, suggesting that exosome-associated αsyn is internalized via an alternative endocytic pathway(s) that has yet to be elucidated.

Liver Transplantation for Congenital Biliary Dilatation: A Single-Center Experience

Background: Congenital biliary dilatation is a rare disease. Although the possibility of refractory cholangitis and/or the frequency of malignant tumors legitimize hepatobiliary surgery, repeated cholangitis and biliary obstruction result in secondary liver cirrhosis even after polysurgery. There are no definitive guidelines on liver transplantation for congenital biliary dilatation. Patients: A total of 1,101 liver transplantation recipients were enrolled in this study. Eleven patients with congenital biliary dilatation including 5 patients with Caroli’s disease were retrospectively analyzed in detail. Results: Nine of 11 patients underwent initial operations before liver transplantation while 2 patients with Caroli’s disease received liver transplantation as initial surgery, with good outcomes. All patients had intractable symptoms caused by liver cirrhosis, and growth delay was considerable in patients aged <20 years. Histopathological analysis of the native liver revealed hepatic fibrosis (≧F2). One patient with ABO incompatibility died. One patient with Caroli’s disease accompanied with intrahepatic carcinoma survives 11.8 years after liver transplantation without any recurrences. Conclusions: Patients with congenital biliary dilatation with refractory symptoms and complications secondary to liver failure are appropriate candidates for liver transplantation. We suggest that liver transplantation is an effective therapeutic option for patients with congenital biliary dilatation with due consideration to many accompanying factors, such as clinical course, growth delay, image findings and histopathological analysis.

Matrix metalloproteinase-9 as a therapeutic target for the progression of fulminant liver failure with hepatic encephalopathy: A pilot study in mice

If progressive liver injury and subsequent hepatic encephalopathy can be prohibited in fulminant liver failure (FLF), it would be ideal for intensive care of FLF and provide an expanded opportunity for liver transplantation (LT). We hypothesized that matrix metalloproteinase (MMP)‐9 plays an important role in FLF progression, and investigated MMP‐9 behaviors in a murine FLF model, especially at the coma stage.

Impact of Hepatic Arterial Reconstruction on Orthotopic Liver Transplantation in the Rat

ABSTRACT Orthotopic liver transplantation (OLT) models in rats have been investigated in many studies, but detailed information on the impact of hepatic artery (HA) reconstruction on postoperative factors remains to be investigated. HA reconstruction also requires advanced skills. The effect of the reconstruction of the HA by a hand-suture technique in rats with a whole-liver syngeneic graft was investigated. Long-term survival, histopathological assessment, immunohistological evaluation, and blood biochemistry were investigated until postoperative day (POD) 28. From the early postoperative period, significant differences between OLTs with or without HA reconstruction were found in graft parenchymal damage, induction of apoptosis, and transaminase levels, though survival curves and the coagulation profile showed no differences. In OLT without HA reconstruction, biliary proliferation was decreased at POD 5–14, and total bilirubin level was increased at PODs 10 and 14. The study indicates that HA reconstruction is required for reliable OLT in rats.