Project description:Liver dysfunction and cirrhosis affect vasculature in several organ systems and cause impairment of organ functions, thereby increasing morbidity and mortality. If a mouse model of hepatopulmonary syndrome (HPS) could be established, greater insight into the genetic basis of the disease would be gained. Our objectives were to establish a mouse model of lung injury after common bile duct ligation (CBDL) and to investigate pulmonary pathogenesis for application in future therapeutic approaches. Balb/c mice were subjected to CBDL. Immunohistochemical analyses and real-time quantitative reverse transcriptional polymerase chain reaction were performed on pulmonary tissues. The presence of HPS markers were detected by western blot and microarray analyses. We observed extensive proliferation of CD31-positive pulmonary vascular endothelial cells 2 weeks after CBDL, and identified 11 up-regulated and 8 down-regulated proteins that were associated with angiogenesis. MMP-9 protein was highly expressed at 3 weeks after CBDL, and less expressed in lungs of the control group. Contrary to our expectation, lung pathology in our mouse model exhibited differences from that of rat models, and the mechanisms responsible for these differences are unknown. This phenomenon may be explained by contrasting processes related to TNF induction of angiogenic signaling pathways in the inflammatory phase; thus, we suggest that our mouse model can be applied to pulmonary pathological analyses in the inflammatory phase, i.e., to systemic inflammatory response syndrome, acute lung injury, and MOD syndrome. After induction of anesthesia, a median abdominal incision was made and the common bile duct was identified. The duct was dissected carefully under a microscope, and doubly ligated with 7-0 Prolene and transected. In the sham operation (control) group, the duct was dissected without common bile duct ligation. Mice were sacrificed at 2 and 3 weeks after surgery. CD31-positive cells were assembled from three mice in each group.
Project description:Adherens junctions, consisting of cadherins and catenins, are a group of cell-to-cell junctions that mediate mechanistic linkage between neighboring cells. By doing so, adherens junctions ensure direct intercellular contact and play an indispensable role in maintaining tissue architecture. Considering these critical functions, it is not surprising that adherens junctions are frequently involved in disease. In the present study, the effects of bile duct ligation-a surgical procedure to experimentally induce cholestatic and fibrotic liver pathology-on hepatic adherens junctions were investigated in mice. In essence, it was found that liver mRNA and protein levels of E-cadherin, ?-catenin and ?-catenin drastically increase following bile duct ligation. These results could suggest a cytoprotective role for hepatic adherens junctions following bile duct ligation.
Project description:Male Sprague-Dawley rats weighing 250-300 g were purchased from Japan SLC Co. (Shizuoka, Japan). The animals were housed under a daily controlled 12-h light and 12-h dark cycle at 23 °C with free access to rat chow (Japan SLC Co.) and water for 1 week prior to the experiments. Rats were laparotomized under ether anesthesia in each experiment, and the common bile duct of each rat was ligated between the liver hilus and small intestine. Control animals underwent a sham operation with exposure but without ligation of the common bile duct. After the CBDL or sham operation, animals were allowed access to food and water ad libitum. Groups of three rats were sacrificed under ether anesthesia at 1, 3 and 12 hr after the CBDL or sham operation. At the time of sacrifice, the right lateral liver lobe was removed and flash-frozen in liquid nitrogen and stored at -80 °C. Total RNA isolated from frozen livers using TRIzol reagent (Invitrogen Co., Carlsbad, CA) was mixed to minimize variation among animals. Poly(A) RNA was purified using Oligotex-dT30 (Takara Shuzo Co., Ltd., Kyoto, Japan) in accordance with manufacturer’s instructions. Fluorescence-labeled probes were prepared by reverse transcription using a superscript II reverse transcriptase (Invitrogen Co.) and cyanine-3- and cyanine-5-dUTP (Perkin-Elmer Inc., Wellesley, MA). Poly(A) RNAs derived from rats that has undergone CBDL and from those that has undergone a sham operation were labeled with cyanine-3 and cyanine-5, respectively, and vise varsa. Fluorescence-labeled probes were purified using a MinElute PCR Products Purification Kit (Quiagen GmbH, Hilden, Germany) in accordance with manufacturer’s instructions. Each purified probe was suspended in hybridization buffer containing 1.6 mg/mL poly(A) (Roche Diagnostics, Basel, Switzerland) and yeast tRNA (Roche Diagnostics), 0.67 mg/mL herring sperm, 16% 20 x SSC and 0.3% SDS and applied to a cDNA microarray containing 1,800 rat genes on a slide glass (Asahi Technoglass Co., Tokyo, Japan). Three house-keeping genes (GAPDH, HPRT and b-actin) and rat unrelated traits (Lambda DNA) were also spotted on the slide as internal positive and negative controls, respectively. Hybridization was carried out twice to eliminate any dye bias. In one experiment, duplicate slides were hybridized with probes derived from CBDL and control rats that had been labeld with cyanine-3 and cyanine-5, respectively. In a replicate experiment, other duplicate slides were hybridized with probes derived from CBDL rats and control rats that had been labeled with cyanine-5 and cyanine-3, respectively (color swap). Then, the slides were cover-slipped and incubated in a sealed chamber (Asahi Technoglass Co.) for 16 hrs under a humidified (65 °C) condition. After being washed in low-stringency buffer (2 x SSC and 0.1% SDS), high-stringency buffer (0.2 x SSC and 0.1% SDS) and 0.2 x SSC and then rinsing with 99.5% ethanol, the slide was dried by centrifugation at low speed and used for scanning. Fluorescence was scanned by using a ScanArray 4000 (Packard BioChip Technologies, Billerica, MA) and quantified by using QuantArray Software (Packard BioChip Technologies, Billerica, MA). Keywords: time-course
Project description:The blood brain barrier tightly regulates the passage of molecules into the brain and becomes leaky following obstructive cholestasis. The aim of this study was to determine if increased serum bile acids observed during cholestasis permeabilize the blood brain barrier.Rats underwent bile duct ligation or deoxycholic or chenodeoxycholic acid injections and blood brain barrier permeability assessed. In vitro, the permeability of rat brain microvessel endothelial cell monolayers, the expression and phosphorylation of occludin, ZO-1 and ZO-2 as well as the activity of Rac1 was assessed after treatment with plasma from cholestatic rats, or bile acid treatment, in the presence of a Rac1 inhibitor.Blood brain barrier permeability was increased in vivo and in vitro following bile duct ligation or treatment with bile acids. Associated with the bile acid-stimulated increase in endothelial cell monolayer permeability was elevated Rac1 activity and increased phosphorylation of occludin. Pretreatment of endothelial cell monolayers with a Rac1 inhibitor prevented the effects of bile acid treatment on occludin phosphorylation and monolayer permeability.These data suggest that increased circulating serum bile acids may contribute to the increased permeability of the blood brain barrier seen during obstructive cholestasis via disruption of tight junctions.
Project description:Portal vein ligation (PVL) induces atrophy/hypertrophy complex (AHC). We hypothesised that simultaneous bile duct and portal vein ligation (BPL) might induce proper bile acid (BA) retention to enhance AHC by activating BA-mediated FXR signalling in the intact liver and promoting apoptosis in the ligated liver. We established rat models of 90% BPL and 90% PVL and found that BPL was well-tolerated and significantly accelerated AHC. The enhanced BA retention in the intact liver promoted hepatocyte proliferation by promoting the activation of FXR signalling, while that in the ligated liver intensified caspase3-mediated apoptosis. Decreasing the BA pools in the rats that underwent BPL could compromise these effects, whereas increasing the bile acid pools of rats that underwent PVL could induce similar effects. Second-stage resection of posterior-caudate-lobe-spearing hepatectomy was performed 5 days after BPL (B-Hx), PVL (V-Hx) or sham (S-SHx), as well as whole-caudate-lobe-spearing hepatectomy 5 days after sham (S-Hx). The B-Hx group had the most favourable survival rate (93.3%, the S-SHx group 0%, the S-Hx group 26.7%, the V-Hx group 56.7%, P < 0.01) and the most sustained regeneration. We conclude that BPL is a safe and effective method, and the acceleration of AHC was bile acid-dependent.
Project description:Human chronic cholestatic liver diseases are characterized by cholangiocyte proliferation, hepatocyte injury, and fibrosis. Yes-associated protein (YAP), the effector of the Hippo tumor-suppressor pathway, has been shown to play a critical role in promoting cholangiocyte and hepatocyte proliferation and survival during embryonic liver development and hepatocellular carcinogenesis. Therefore, the aim of this study was to examine whether YAP participates in the regenerative response after cholestatic injury. First, we examined human liver tissue from patients with chronic cholestasis. We found more-active nuclear YAP in the bile ductular reactions of primary sclerosing cholangitis and primary biliary cirrhosis patient liver samples. Next, we used the murine bile duct ligation (BDL) model to induce cholestatic liver injury. We found significant changes in YAP activity after BDL in wild-type mice. The function of YAP in the hepatic response after BDL was further evaluated with liver-specific Yap conditional deletion in mice. Ablating Yap in the mouse liver not only compromised bile duct proliferation, but also enhanced hepatocyte necrosis and suppressed hepatocyte proliferation after BDL. Furthermore, primary hepatocytes and cholangiocytes isolated from Yap-deficient livers showed reduced proliferation in response to epidermal growth factor in vitro. Finally, we demonstrated that YAP likely mediates its biological effects through the modulation of Survivin expression.Our data suggest that YAP promotes cholangiocyte and hepatocyte proliferation and prevents parenchymal damage after cholestatic injury in mice and thus may mediate the response to cholestasis-induced human liver disease.
Project description:Increasing evidence point to the relevance of intestinal disfunction and changes in the microbiome composition during chronic liver disease. More specifically, recent studies have highlighted that cholestatic diseases associate with a reduction in the microbiome diversity in patients. Still, the dynamics of the changes in the microbiome composition observed, as well as their implication in contributing to the pathogenesis of this disease remain largely undefined. Hence, experimental mouse models resembling the human pathogenesis are crucial to move forward our understanding on the mechanisms underpinning cholestatic disease and to enable the development of effective therapeutics. Our results show that the bile duct ligation (BDL) experimental model of cholestasis leads to rapid and significant changes in the microbiome diversity, with more than 100 OTUs being significantly different in faecal samples obtained from WT mice at 3 days and 7 days after BDL when compared to control animals. Changes in the microbial composition in mice after BDL included the enrichment of Akkermansia, Prevotella, Bacteroides and unclassified Ruminococcaceae in parallel with a drastic reduction of the presence of Faecalibacterium prausnitzii. In conclusion, our results support that bile duct ligation induces changes in the microbiome that partly resemble the gut microbial changes observed during human cholestatic disease.
Project description:Liver fibrosis is a consequence of chronic liver disorders which lead to the accumulation of extracellular matrix (ECM). Particularly, there is an increased accumulation of collagen in the fibrotic liver. We have therefore used a triplex forming oligonucleotide (TFO) against the type ?1(I) collagen and evaluated, whether it can attenuate liver fibrosis induced by common bile duct ligation (CBDL) in rats. There was a significant decrease in hydroxyproline levels and Masson's trichrome staining for collagen in TFO-treated CBDL groups compared to non-treated CBDL group. There was over expression of type ?1(I) collagen, ?-smooth muscle actin (?-SMA) and TGF-?1 expression in the CBDL group compared to TFO-treated CBDL group. Also, the serum alanine transaminase (ALT) and aspartate transaminase (AST) concentrations were less in the TFO treated group compared to non-treated CBDL group. There was also less neutrophils accumulation in TFO treated CBDL group assayed by myeloperoxidase (MPO) assay. These results suggests that TFO can be used to downregulate type 1 collagen gene expression and can alleviate liver fibrosis induced by common bile duct ligation.