Gene expression profile analysis of regenerating liver after portal vein ligation in rats by a cDNA microarray system

Hepatectomy-Induced Alterations in Hepatic Perfusion and Function - Toward Multi-Scale Computational Modeling for a Better Prediction of Post-hepatectomy Liver Function

Liver resection causes marked perfusion alterations in the liver remnant both on the organ scale (vascular anatomy) and on the microscale (sinusoidal blood flow on tissue level). These changes in perfusion affect hepatic functions via direct alterations in blood supply and drainage, followed by indirect changes of biomechanical tissue properties and cellular function. Changes in blood flow impose compression, tension and shear forces on the liver tissue. These forces are perceived by mechanosensors on parenchymal and non-parenchymal cells of the liver and regulate cell-cell and cell-matrix interactions as well as cellular signaling and metabolism. These interactions are key players in tissue growth and remodeling, a prerequisite to restore tissue function after PHx. Their dysregulation is associated with metabolic impairment of the liver eventually leading to liver failure, a serious post-hepatectomy complication with high morbidity and mortality. Though certain links are known, the overall functional change after liver surgery is not understood due to complex feedback loops, non-linearities, spatial heterogeneities and different time-scales of events. Computational modeling is a unique approach to gain a better understanding of complex biomedical systems. This approach allows (i) integration of heterogeneous data and knowledge on multiple scales into a consistent view of how perfusion is related to hepatic function; (ii) testing and generating hypotheses based on predictive models, which must be validated experimentally and clinically. In the long term, computational modeling will (iii) support surgical planning by predicting surgery-induced perfusion perturbations and their functional (metabolic) consequences; and thereby (iv) allow minimizing surgical risks for the individual patient. Here, we review the alterations of hepatic perfusion, biomechanical properties and function associated with hepatectomy. Specifically, we provide an overview over the clinical problem, preoperative diagnostics, functional imaging approaches, experimental approaches in animal models, mechanoperception in the liver and impact on cellular metabolism, omics approaches with a focus on transcriptomics, data integration and uncertainty analysis, and computational modeling on multiple scales. Finally, we provide a perspective on how multi-scale computational models, which couple perfusion changes to hepatic function, could become part of clinical workflows to predict and optimize patient outcome after complex liver surgery.

Advances in Research on the Cardiovascular Complications of Acromegaly

Cardiovascular-related complications are one of the most common complications in patients with acromegaly, and can lead to an increased risk of death. Hypertension and cardiomyopathy are the main cardiovascular complications. The characteristics of acromegalic cardiomyopathy are concentric biventricular hypertrophy and diastolic dysfunction. In addition, arrhythmia and heart valve disease are common cardiac complications in acromegaly. Although the underlying pathophysiology has not been fully elucidated, the spontaneous overproduction of GH and IGF-1, increasing age, prolonged duration of disease and the coexistence of other cardiovascular risk factors are crucial to cardiac complications in patients with acromegaly. Early diagnosis and appropriate treatment of acromegaly might be beneficial for the prevention of cardiomyopathy and premature death.

RNA-Seq transcriptome profiling in three liver regeneration models in rats: comparative analysis of partial hepatectomy, ALLPS, and PVL

The liver is a unique organ that has a phenomenal capacity to regenerate after injury. Different surgical procedures, including partial hepatectomy (PH), intraoperative portal vein ligation (PVL), and associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) show clinically distinct recovery patterns and regeneration. The observable clinical differences likely mirror some underlying variations in the patterns of gene activation and regeneration pathways. In this study, we provided a comprehensive comparative transcriptomic analysis of gene regulation in regenerating rat livers temporally spaced at 24 h and 96 h after PH, PVL, and ALPPS. The time-dependent factors appear to be the most important determinant of post-injury alterations of gene expression in liver regeneration. Gene expression profile after ALPPS showed more similar expression pattern to the PH than the PVL at the early phase of the regeneration. Early transcriptomic changes and predicted upstream regulators that were found in all three procedures included cell cycle associated genes (E2F1, CCND1, FOXM1, TP53, and RB1), transcription factors (Myc, E2F1, TBX2, FOXM1), DNA replication regulators (CDKN1A, EZH2, RRM2), G1/S-transition regulators (CCNB1, CCND1, RABL6), cytokines and growth factors (CSF2, IL-6, TNF, HGF, VEGF, and EGF), ATM and p53 signaling pathways. The functional pathway, upstream, and network analyses revealed both unique and overlapping molecular mechanisms and pathways for each surgical procedure. Identification of molecular signatures and regenerative signaling pathways for each surgical procedure further our understanding of key regulators of liver regeneration as well as patient populations that are likely to benefit from each procedure.

Bioinformatics microarray analysis and identification of gene expression profiles associated with cirrhotic liver

Cirrhosis is the endpoint of liver fibrosis that is accompanied by limited regeneration capacity and complications and is the ultimate cause of death in many patients. Despite this, few studies have thoroughly looked at the gene expression profiles in the cirrhotic liver. Hence, this study aims to identify the genes that were differentially expressed in the cirrhotic liver and to explore the putative related signaling pathway and interaction networks. The gene expression profiles of cirrhotic livers and noncirrhotic livers were examined and compared using microarray gene analysis. Proteins encoded by the differentially expressed genes were analyzed for functional clustering and signaling pathway involvement using MetaCore bioinformatics analyses. The Gene Ontology analysis as well as the Kyoto encyclopedia of Genes and Genomes pathway analysis were also performed. A total of 213 significant genes were differentially expressed at more than a two-fold change in cirrhotic livers as compared to noncirrhotic livers. Of these, 105 upregulated genes and 63 downregulated genes were validated through MetaCore bioinformatics analyses. The signaling pathways and major functions of proteins encoded by these differentially expressed genes were further analyzed; results showed that the cirrhotic liver has a unique gene expression pattern related to inflammatory reaction, immune response, and cell growth, and is potentially cancer related. Our findings suggest that the microarray analysis may provide clues to the molecular mechanisms of liver cirrhosis for future experimental studies. However, further exploration of areas regarding therapeutic strategy might be possible to support metabolic activity, decrease inflammation, or enhance regeneration for liver cirrhosis.

Purinergic signalling in the liver in health and disease

Purinergic signalling is involved in both the physiology and pathophysiology of the liver. Hepatocytes, Kupffer cells, vascular endothelial cells and smooth muscle cells, stellate cells and cholangiocytes all express purinoceptor subtypes activated by adenosine, adenosine 5'-triphosphate, adenosine diphosphate, uridine 5'-triphosphate or UDP. Purinoceptors mediate bile secretion, glycogen and lipid metabolism and indirectly release of insulin. Mechanical stress results in release of ATP from hepatocytes and Kupffer cells and ATP is also released as a cotransmitter with noradrenaline from sympathetic nerves supplying the liver. Ecto-nucleotidases play important roles in the signalling process. Changes in purinergic signalling occur in vascular injury, inflammation, insulin resistance, hepatic fibrosis, cirrhosis, diabetes, hepatitis, liver regeneration following injury or transplantation and cancer. Purinergic therapeutic strategies for the treatment of these pathologies are being explored.

Proteomic analysis of regenerating mouse liver following 50% partial hepatectomy

Background

Although 70% (or 2/3) partial hepatectomy (PH) is the most studied model for liver regeneration, the hepatic protein expression profile associated with lower volume liver resection (such as 50% PH) has not yet been reported. Therefore, the aim of this study was to determine the global protein expression profile of the regenerating mouse liver following 50% PH by differential proteomics, and thereby gaining some insights into the hepatic regeneration mechanism(s) under this milder but clinically more relevant condition.

Results

Proteins from sham-operated mouse livers and livers regenerating for 24 h after 50% PH were separated by SDS-PAGE and analyzed by nanoUPLC-Q-Tof mass spectrometry. Compared to sham-operated group, there were totally 87 differentially expressed proteins (with 50 up-regulated and 37 down-regulated ones) identified in the regenerating mouse livers, most of which have not been previously related to liver regeneration. Remarkably, over 25 differentially expressed proteins were located at mitochondria. Several of the mitochondria-resident proteins which play important roles in citric acid cycle, oxidative phosphorylation and ATP production were found to be down-regulated, consistent with the recently-proposed model in which the reduction of ATP content in the remnant liver gives rise to early stress signals that contribute to the onset of liver regeneration. Pathway analysis revealed a central role of c-Myc in the regulation of liver regeneration.

Conclusions

Our study provides novel evidence for mitochondria as a pivotal organelle that is connected to liver regeneration, and lays the foundation for further studies on key factors and pathways involved in liver regeneration following 50% PH, a condition frequently used for partial liver transplantation and conservative liver resection.

Unique early gene expression patterns in human adult-to-adult living donor liver grafts compared to deceased donor grafts

Because of inherent differences between deceased donor (DD) and living donor (LD) liver grafts, we hypothesize that the molecular signatures will be unique, correlating with specific biologic pathways and clinical patterns. Microarray profiles of 63 biopsies in 13 DD and 8 LD liver grafts done at serial time points (procurement, backbench and postreperfusion)were compared between groups using class comparisons, network and biological function analyses. Specific genes were validated by quantitative PCR and immunopathology. Clinical findings were also compared. Following reperfusion, 579 genes in DD grafts and 1324 genes in LDs were differentially expressed (p < 0.005). Many upregulated LD genes were related to regeneration, biosynthesis and cell cycle, and a large number of downregulated genes were linked to hepatic metabolism and energy pathways correlating with posttransplant clinical laboratory findings. There was significant upregulation of inflammatory/immune genes in both DD and LD, each with a distinct pattern. Gene expression patterns of select genes associated with inflammation and regeneration in LD and DD grafts correlated with protein expression. Unique patterns of early gene expression are seen in LD and DD liver grafts, correlating with protein expression and clinical results, demonstrating distinct inflammatory profiles and significant downregulation of metabolic pathways in LD grafts.

Variations in Interferon Gamma Receptor Gene Expression during Liver Regeneration after Partial Hepatectomy in Rats

Cell-mediated immunity, which includes interferon gamma (IFN-γ) expression, is activated during the process of liver regeneration; however, the genetic pathway of this activation is still unclear. The present study evaluated variations in the interferon gamma receptor (IFN-γR) gene and its mRNA expression during liver regeneration after partial hepatectomy (PH). Male Wistar rats weighing approximately 200 g were subjected to PH (70 or 40%). IFN-γR gene expression in the remnant liver was measured by cDNA microarray, and mRNA expression was verified by real-time quantitative reverse transcription-polymerase chain reaction (Q-PCR) preoperatively and at 2, 4, 6,12, 24, and 72 hours and 7 days postoperatively. The ratio of remnant liver weight to body weight increased markedly after 70 per cent PH and more gradually after 40 per cent PH. It reached near 90 per cent of the preoperative level at 72 hours after PH in both groups. The scanned spots of the genomic survey on the cDNA microarray chips were uneven and increased irregularly in number and density after PH. IFN-γR gene expression increased markedly in a single peak pattern, up to more than double the preoperative level, at 6 hours after 70 per cent PH. The curve in the 40 per cent PH group was flat and peaked at only 1.6 times the preoperative level. The variations in IFN-γR-related mRNA expression were verified by Q-PCR. Elevations in IFN-γR gene and mRNA expression were shown during the early stage of liver regeneration after PH. The genetic pathway of IFN-γ/IFN-γR expression is activated during liver regeneration.

Beneficial effects of Kampo medicine Inchin-ko-to on liver function and regeneration after hepatectomy in rats

AIM

Inchin-ko-to (ICKT), Kampo medicine, is known to inhibit hepatocyte apoptosis as well as promote the secretion and excretion of bile. The aim of this study is to clarify the effects of ICKT on liver function and hepatic regeneration after massive hepatectomy in rats.

METHODS

Male Wistar rats received 2 g/kg ICKT from 3 days preoperatively and underwent 90% hepatectomy. Liver sections were stained using immunohistochemistry (hemeoxygenase-1 [HO-1], alpha-smooth muscle actin [SMA], and proliferating cell nuclear antigen [PCNA]).

RESULTS

The survival period was significantly prolonged, and the remnant liver/body weight ratio was significantly increased postoperatively in the ICKT group. The values of transaminase, total bile acid, and total bilirubin were significantly improved in the ICKT group. In the ICKT group, PCNA and HO-1 were strongly expressed early postoperatively, but the expression of alpha-SMA was weak.

CONCLUSION

The preoperative administration of ICKT has been suggested to provide beneficial effects in promoting hepatic regeneration and preventing postoperative hepatic failure. The reduced activation of stellate cells may be involved in their mechanisms.

Portal blood flow regulates volume recovery of the rat liver after partial hepatectomy: molecular evaluation

BACKGROUND/AIM

Liver regeneration is a finely tuned process that is closely regulated by multiple cell cycle steps. Although the portal blood flow affects liver regeneration, the molecular mechanism by which the blood flow regulates gene expression and liver function is largely unknown. The aim of this study was to investigate the molecular effect of portal blood flow on hepatocyte proliferation and gene regulation during liver regeneration.

MATERIALS AND METHODS

We developed a simple surgical rat model to investigate the relation between portal blood flow and liver regeneration by partially ligating the portal trunk with 8-0 Proline sutures under microscopy to reduce the blood flow by 40%. We investigated recovery of liver volume, DNA synthesis, and gene expression associated with cell cycle regulators, comparing partially hepatectomized (PH) rats without (PH group; n = 30) and with partial portal ligation (PHPL group; n = 30) for 7 days after the operation.

RESULTS

The hepatic tissue blood flow and the recovery ratio between liver weight and body weight in the PHPL group were significantly lower than in the PH group after hepatectomy. The peak 5-bromo-2'-deoxyuridine labeling index in the PHPL group was delayed and weak compared with the PH group. The expression of CT-1 and cyclin D, E, and B mRNAs indicated that the liver regeneration in the PHPL group was delayed and weak. In addition, there was reciprocal expression of C/EBPalpha and C/EBPbeta mRNAs, an observation supported by their nuclear protein levels. Furthermore, the cytochrome P-450 protein level in the PHPL group was higher than that in the PH group 1 day after hepatectomy.

CONCLUSION

The portal blood flow regulates the activity of liver regeneration and the gene expression associated with cell cycle regulators, while the functions are maintained.

Treatment for multiple bilobar liver metastases of colorectal cancer

BACKGROUND

Recent advances have extended indications for hepatectomy to include multiple bilobar colorectal liver metastases (CLM). Staging systems based on the biological malignancy of primary and metastatic tumors provide appropriate indications for hepatectomy in CLM. However, suitability for resection in patients with complex and extensive hepatic metastases is controversial.

METHODS

A medline search was performed to identify papers reporting the resection for CLM. Techniques, indication, and results were reviewed.

RESULTS

If the anticipated remnant liver volume is small (25-40% of total), suggesting a high risk of postoperative liver failure, portal vein embolization (PVE) is recommended prior to hepatectomy. However, curative resections are not always possible. Specifically in synchronous multiple bilobar CLM, two-stage hepatectomy, comprising bilateral hepatectomy and primary resection with or without PVE, can prevent growth of ipsilateral metastatic nodules in the remnant liver and reduce surgical risk. Several local ablation techniques can complement surgery if hepatic resection alone increases the risk of postoperative liver failure or is not curative. Chemotherapy combined with targeted treatment can suppress recurrence and extend indications for hepatectomy by reducing the size and number of primary irresectable tumors.

CONCLUSION

PVE or staged procedure combining with local ablation or neoadjuvant, downstaging or adjuvant therapies extends indications for hepatectomy to include multiple bilobar CLM. The 5-year survival rate for multiple bilobar CLM treated with alternating hepatectomy and chemotherapy is comparable to the values reported for single and hemilateral CLM.

Tumor growth-promoting cellular host response during liver atrophy after portal occlusion

BACKGROUND/AIMS

Clinical observations suggest cancer progression after preoperative segmental portal vein occlusion, a procedure to prevent liver failure after major hepatic resections. The aim of this study was to determine whether portal occlusion induces host reactions which promote cancer invasion and angiogenesis.

METHODS

The rat model of portal branch ligation (PBL) was compared with partial hepatectomy (PH) and sham operation (SO) and evaluated for the expression of heat shock protein-70 (hsp70), heme oxygenase-1 (hmox1), early growth response gene-1 (Egr-1) and urokinase-type plasminogen activator (uPA), its inhibitor (PAI-1) and receptor (uPAR).

RESULTS

Portal deprivation after PBL was associated with a regression of liver tissue to 25% of its original mass within 8 days with only modest fibrotic changes. During the progression of atrophy, there were significant inductions of hsp70-, hmox1- and Egr-1-mRNA in comparison with regenerating liver tissue. PAI-1-specific mRNA was transiently elevated at 3 - 48 h after PBL in the atrophying lobes, whereas uPA and uPAR were unaffected in comparison with PH or SO.

CONCLUSION

Hepatic atrophy caused by PBL is associated with increased expression of genes known to promote tumor growth. These host events represent a possible explanation for the tumor progression after portal occlusion and require further evaluation.