Vascular factors, angiogenesis and biliary tract disease

CXCL6 Reshapes Lipid Metabolism and Induces Neutrophil Extracellular Trap Formation in Cholangiocarcinoma Progression and Immunotherapy Resistance

The chemokine CXCL6 is identified as a pivotal regulator of biological processes across multiple malignancies. However, its function in cholangiocarcinoma (CCA) is underexplored. Tumor profiling for CXCL6 is performed using a public database. Both in vitro and in vivo experiments are utilized to evaluate the oncogenic effects of CXCL6 on CCA. Additionally, RNA-Seq is employed to detect transcriptomic changes related to CXCL6 expression in CCA cells and neutrophils. Molecular docking, fluorescence colocalization, and Co-IP are used to elucidate a direct interaction between JAKs and CXCR1/2. Additionally, LC-MS lipidomics and explored the impact of CXCL6 on immunotherapy in vivo. CXCL6 is upregulated in CCA tissues and promoted the proliferation and metastasis of CCA. Mechanistically, CXCL6 regulated the CXCR1/2-JAK-STAT/PI3K axis in CCA via autocrine signaling, leading to lipid metabolic reprogramming, and promoted neutrophil extracellular traps (NETs) formation by activating the RAS/MAPK pathway in neutrophils. Eventually, NETs formation induced immunotherapy resistance in CCA by blocking CD8+T cell infiltration. CXCL6 modulates CCA progression through the CXCR1/2-JAK-STAT/PI3K axis and reshaping its lipid metabolism. CXCL6 also mediates immunotherapy resistance through NETs, which may be a potential therapeutic target and biomarker for CCA.

A Pathological Assessment of the Microvasculature of Biliary Tract Neoplasms Referring to Pre-Existing Blood Vessels and Vessel Co-Option

There are several types of microvasculature supplying neoplasms: "newly formed blood vessels" (neoangiogenesis), which are a component of the tumor microenvironment (TME) of invasive carcinoma with wound healing-like reaction; and "pre-existing blood vessels", which are used as tumor-supplying vessels by neoplasms (co-option vessels) and are likely to develop in hypervascularized organs. We herein review the microvasculature of neoplasms of biliary tract with reference to pre-existing vessels and vessel co-options. In the hepatobiliary system, intrahepatic large and extrahepatic bile ducts (large bile ducts) and the gallbladder as well as hepatic lobules are highly vascularized regions. In large bile ducts, the biliary lining epithelia and underlining capillaries (peribiliary capillary plexus [PCP]) form the biliary epithelia-PCP alignment, whereas the hepatocyte-sinusoid alignment composes hepatic lobules. Cholangiocarcinoma (CCA) and gallbladder carcinoma (GBC) are the main biliary tract carcinomas. CCA is subdivided into distal (d/CCA), perihilar (pCCA), and intrahepatic (iCCA), and iCCA is subdivided into small duct type (SD-iCCA) and large duct type (LD-iCCA). High-grade biliary intraepithelial neoplasm (BilIN), intraductal papillary neoplasm of the bile duct (IPNB), pyloric gland adenoma (PGA), and intracholecystic papillary neoplasm (ICPN) have recently been proposed as the precursors of LD-iCCA, p/dCCA, and GBC. In the large bile ducts and gallbladder, all cases of high-grade BilIN and PGA, about half of IPNB, and one-third of ICPN with less-complicated structure were found to have hijacked the PCP as their supporting vessels (vessel co-option), while p/dCCA, LD-iCCA, and GBC were supplied by neo-angiogenetic vessels associated with fibrous stroma. The intraluminal components of the remaining cases of ICPN and IPNB with complicated structure presented sparse capillaries without fibrous stroma, a unique microvasculature different from that of co-option or neoangiogenesis. Regarding iCCA showing invasion into the hepatic lobules, some SD-iCCAs replaced hepatocytic cords and used pre-existing sinusoids as co-opted vessels. Visualization of pre-existing vessels could be a new pathological tool for the evaluation of malignant progression and of vascular supply in CCAs and its precursors.

Genetic Contributions to Biliary Atresia: A Developmental Cholangiopathy

Biliary atresia (BA) is the most prevalent serious liver disease of infancy and childhood, and the principal indication for liver transplantation in pediatrics. BA is best considered as an idiopathic panbiliary cholangiopathy characterized by obstruction of bile flow and consequent cholestasis presenting during fetal and perinatal periods. While several etiologies have been proposed, each has significant drawbacks that have limited understanding of disease progression and the development of effective treatments. Recently, modern genetic analyses have uncovered gene variants contributing to BA, thereby shifting the paradigm for explaining the BA phenotype from an acquired etiology (e.g., virus, toxin) to one that results from genetically altered cholangiocyte development and function. Herein we review recently reported genetic contributions to BA, highlighting the enhanced representation of variants in biological pathways involving ciliary function, cytoskeletal structure, and inflammation. Finally, we blend these findings as a new framework for understanding the resultant BA phenotype as a developmental cholangiopathy.

Cellular Homeostasis and Repair in the Biliary Tree

During biliary tree homeostasis, BECs are largely in a quiescent state and their turnover is slow for maintaining normal tissue homeostasis. BTSCs continually replenish new BECs in the luminal surface of EHBDs. In response to various types of biliary injuries, distinct cellular sources, including HPCs, BTSCs, hepatocytes, and BECs, repair or regenerate the injured bile duct. BEC, biliary epithelial cell; BTSC, biliary tree stem/progenitor cell; EHBD, extrahepatic bile ducts; HPC, hepatic progenitor cell.The biliary tree comprises intrahepatic bile ducts and extrahepatic bile ducts lined with epithelial cells known as biliary epithelial cells (BECs). BECs are a common target of various cholangiopathies for which there is an unmet therapeutic need in clinical hepatology. The repair and regeneration of biliary tissue may potentially restore the normal architecture and function of the biliary tree. Hence, the repair and regeneration process in detail, including the replication of existing BECs, expansion and differentiation of the hepatic progenitor cells and biliary tree stem/progenitor cells, and transdifferentiation of the hepatocytes, should be understood. In this paper, we review biliary tree homeostasis, repair, and regeneration and discuss the feasibility of regenerative therapy strategies for cholangiopathy treatment.

A Recent Ten-Year Perspective: Bile Acid Metabolism and Signaling

Bile acids are important physiological agents required for the absorption, distribution, metabolism, and excretion of nutrients. In addition, bile acids act as sensors of intestinal contents, which are determined by the change in the spectrum of bile acids during microbial transformation, as well as by gradual intestinal absorption. Entering the liver through the portal vein, bile acids regulate the activity of nuclear receptors, modify metabolic processes and the rate of formation of new bile acids from cholesterol, and also, in all likelihood, can significantly affect the detoxification of xenobiotics. Bile acids not absorbed by the liver can interact with a variety of cellular recipes in extrahepatic tissues. This provides review information on the synthesis of bile acids in various parts of the digestive tract, its regulation, and the physiological role of bile acids. Moreover, the present study describes the involvement of bile acids in micelle formation, the mechanism of intestinal absorption, and the influence of the intestinal microbiota on this process.

Clinical Course of Porto-Sinusoidal Vascular Disease Is Distinct From Idiopathic Noncirrhotic Portal Hypertension

BACKGROUND & AIMS

Porto-sinusoidal vascular disease (PSVD) was recently proposed as novel clinical entity characterized by typical histological changes with or without portal hypertension (PH) in the absence of cirrhosis. Thus, we aimed to describe clinical characteristics and the outcome of PSVD patients and to compare these to patients meeting traditional idiopathic non-cirrhotic portal hypertension (INCPH) criteria.

METHODS

Patients undergoing liver biopsy (baseline) ±hepatic venous pressure gradient (HVPG) measurement at the Vienna General Hospital between 2000-2019 were screened for PSVD and INCPH criteria.

RESULTS

91 patients were diagnosed with PSVD of which 28 (30.8%) also fulfilled INCPH criteria (INCPH+/PSVD+). Specific histological and specific clinical PH signs were found in 72 (79.1%) and 54 (59.3%) patients, respectively. INCPH+/PSVD+ showed higher Child-Pugh-scores (7±2 vs 6±1 points; P = .002) and a higher prevalence of decompensation (57.1% vs 28.6%; P = .009) than INCPH-/PSVD+ patients. Importantly, hepatic decompensation after three years (3Y) occurred in 11.2% of PSVD patients with specific clinical signs of PH, while no decompensation occurred in patients with only specific histological or with unspecific clinical/histological signs (P = .002). When categorizing by INCPH definition, 3Y decompensation was 13.4% in INCPH+/PSVD+ and 3.8% in INCPH-/PSVD+ (P = .120). While overall mortality was similar in INCPH+/PSVD+ (n = 6; 21.4%) and INCPH-/PSVD+ (n = 10; 15.9%) patients (P = .558), liver-related mortality tended to be higher in INCPH+/PSVD+ (6.9%) than in INCPH-/PSVD+ (0%; P = .078).

CONCLUSION

Novel PSVD criteria facilitate diagnosis. Compared to INCPH, clinical course of PSVD patients is more favorable. Importantly, specific signs of PH including varices and collaterals are associated with hepatic decompensation and mortality.

Angiogenesis in biliary tract cancer: targeting and therapeutic potential

Introduction: Biliary Tract Cancer (BTC) is a heterogeneous group of malignant neoplasms with a complex molecular pathogenesis. The prognosis of metastatic disease is dramatically dismal and therapeutic options are scarce. Systemic chemotherapy is the gold standard for the metastatic disease. However, because of the disappointing results with conventional chemotherapy, investigators have turned to new biological therapeutic options targeting the main molecular pathways, neo-angiogenesis, involved in the disease pathogenesis.Areas covered: This paper examines the rationale of using antiangiogenic therapies in this setting, evaluates the therapeutic implications, and highlights ongoing studies and future perspectives. A Pubmed systematic review of preclinical and clinical data was performed which enabled the composition of this paper.Expert opinion: Amore in-depth understanding of the interplay between the neo-angiogenesis pathways, and the microenvironment will could propel the design new therapeutic strategies. Nowadays, the combination of antiangiogenic drugs and immune check-point inhibitors looks promising, but further, more comprehensive data are necessary to gain afuller picture. In an era of novel technologies and techniques, which includes radiomics, the challenge is to identify the biomarkers of response to antiangiogenic drugs which will permit the selection of patients that are more likely to respond to antiangiogenic therapies.

Expression of vascular endothelial growth factor A in liver tissues of infants with biliary atresia

Aim of the study

Assessment of hepatic expression of vascular endothelial growth factor A (VEGF-A) in liver tissues of infants with biliary atresia (BA).

Material and methods

This retrospective study included 35 infants with BA (BA group), and 38 infants with cholestasis due to causes other than BA (non-BA group). All patients had undergone full history taking, through clinical examination, routine investigations and immunostaining of liver tissue for VEGF-A and cytokeratin 7 (CK7). The diagnosis of BA was confirmed by intraoperative cholangiography. In the non-BA group, other specific laboratory tests according to the expected etiology were done.

Results

Most of the BA group showed positive VEGF-A expression with variable degrees in both bile ducts (BDs; 80%), and arterial walls (AWs; 77.2%), while most of the non-BA group showed negative staining of VEGF in both BDs and AWs (89.5% and 86.8% respectively) (p < 0.0001). Positive VEGF expression in the portal structures in both BDs and AWs had 84.9% and 82.19% accuracy; respectively. The majority of BA group showed either grade II of positive cytokeratin-7 expression in liver tissues (45.7%) or grade III (34.3%), while most of the non-BA group showed grade I (71.1%) (p < 0.0001). Positive CK7 expression in > 25% of the liver tissues had 80.8% accuracy in discriminating between BA and non-BA.

Conclusions

VEGF-A expression in the portal structures in liver tissues in both BDs and AWs had very good accuracy in discriminating between BA and non-BA patients.

The interaction of LOXL2 with GATA6 induces VEGFA expression and angiogenesis in cholangiocarcinoma

Cholangiocarcinoma (CCA) is the second most common hepatobiliary cancer after hepatocellular carcinoma. Antiangiogenic therapy has been administered to patients with CCA, but the benefits of this therapy remain unsatisfactory. Improved understanding of the molecular mechanisms underlying angiogenesis in CCA is required. In the present study, the expression of GATA-binding protein 6 (GATA6), lysyl oxidase-like 2 (LOXL2) and vascular endothelial growth factor A (VEGFA), in addition to the microvessel density (MVD), were evaluated by performing immunohistochemical staining of human CCA microarrays. The expression of GATA6/LOXL2 was associated with poor overall survival (P=0.01) and disease-free survival (P=0.02), and was positively associated with VEGFA expression (P=0.02) and MVD (P=0.04). In vitro, western blotting, reverse transcription-quantitative PCR analysis and ELISAs revealed that altered GATA6 and LOXL2 expression regulated the expression levels of secreted VEGFA. Co-immunoprecipitation demonstrated a physical interaction between GATA6 and LOXL2 in CCA cell lines, and the scavenger receptor cysteine-rich domain of LOXL2 interacted with GATA6, which regulated VEGFA mRNA expression and protein secretion, and promoted tube formation. In vivo analyses further revealed that GATA6/LOXL2 promoted VEGFA expression, angiogenesis and tumor growth. The GATA6/LOXL2 complex represents a novel candidate prognostic marker for stratifying patients with CCA. Drugs targeting this complex may possess great therapeutic value in the treatment of CCA.

Role of the Angiogenic Factors in Cholangiocarcinoma

Angiogenesis plays a fundamental role in tumor growth and progression. It is regulated by several growth factors, including vascular endothelial growth factor protein family (VEGF) and its receptors, which are probably the most important factors responsible for the development of new vessels. The VEGF family includes several members: VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, placental growth factor (PlGF), and their receptors VEGFR-1, VEGFR-2 and VEGFR-3. Other relevant factors are represented by angiopoietins, thrombospondin-1, and endothelins. However, since the therapeutic benefit associated with VEGF-targeted therapy is really complex, a better understanding of these pathways will lead to future advances in the use of these agents for clinic management of tumors. Here we present a review regarding the role of angiogenic factors in cholangiocarcinoma, which arise from cholangiocytes, the epithelial cells of bile ducts. They are rare and aggressive neoplasms with a poor prognosis and limited treatment options, classified as intrahepatic, perihilar, and distal cholangiocarcinoma based on their anatomical location. Therefore, the identification of specific signaling pathways or new tumor biomarkers is crucial in order to develop more effective anti-angiogenic therapies.

Recovery of the Cholangiocytes After Ischemia and Reperfusion Injury: Ultra-Structural, Hystological and Molecular Assessment in Rats

INTRODUCTION

Ischemia-reperfusion (I/R) injury of the liver is a common area of interest to transplant and hepatic surgery. Nevertheless, most of the current knowledge of I/R of the liver derives from the hepatocyte and little is known of what happens to the cholangiocytes. Herein, we assess the sequence of early events involved in the I/R injury of the cholangiocytes.

METHODS

Sixty Wistar rats were randomized in a SHAM group and I/R group. Serum biochemistry, histopathology, immunohistochemistry, transmission electron microscopy (TEM) and laser capture microdissection (LCM) were used for group comparison.

RESULTS

There was peak of alkaline phosphatase 24 h after IR injury, and an increase of aspartate aminotransferase and alanine aminotransferase after 6 h of reperfusion, followed by a return to normal levels 24 h after injury. The I/R group presented the liver parenchyma with hepatocellular degeneration up to 6 h, followed by hepatocellular necrosis at 24 h. TEM showed cholangiocyte injury, including a progressive nuclear degeneration and cell membrane rupture, beginning at 6 h and peaking at 24 h after reperfusion. Cytokeratin-18 and caspase-3-positive areas were observed in the I/R group, peaking at 24-h reperfusion. Anti-apoptotic genes Bcl-2 and Bcl-xl activity were expressed from 6 through 24 h after reperfusion. BAX expression showed an increase for 24 h.

CONCLUSIONS

I/R injury to the cholangiocyte occurs from 6 through 24 h after reperfusion and a combination of TEM, immunohistochemistry and LCM allows a better isolation of the cholangiocyte and a proper investigation of the events related to the I/R injury. Apoptosis is certainly involved in the I/R process, particularly mediated by BAX.

Long-term effects of human amniotic membrane in a rat model of biliary fibrosis

Liver fibrosis is the most common outcome of chronic liver diseases, and its progression to cirrhosis can only be effectively treated with liver transplantation. The amniotic membrane (AM) has been studied as an alternative therapy for fibrosis diseases mainly for its favorable properties, including anti-inflammatory, anti-scaring and immunomodulatory properties. It was recently demonstrated that the AM reduces the progression of biliary fibrosis to its advanced stage, cirrhosis, when applied on the liver for 6 weeks after fibrosis induction. Here, we investigated the effects of AM on rat fibrotic liver, during a prolonged period of time. Fibrosis was induced by bile duct ligation (BDL), and at the same time, a fragment of AM was applied around the liver. After 1, 3, 6, and 9 weeks, the degree of fibrosis was assessed by qualitative Knodell scoring, and by quantitative image analysis to quantify the area of collagen deposition in hepatic tissue. While fibrosis progressed rapidly in untreated BDL animals, leading to cirrhosis within 6 weeks, AM-treated livers showed confined fibrosis at the periportal area with few and thin fibrotic septa, but without cirrhosis. In addition, collagen deposition was reduced to about 36 and 55% of levels observed in BDL at 6 and 9 weeks after BDL, respectively, which shows that the longer the period of AM application, the lower the collagen deposition. These results suggested that AM applied as a patch onto the liver surface for longer periods attenuated the severity of biliary fibrosis and protected against liver degeneration caused by excessive collagen deposition.

Functional and structural features of cholangiocytes in health and disease

Cholangiocytes are the epithelial cells that line the bile ducts. Along the biliary tree, two different kinds of cholangiocytes exist; small and large cholangiocytes. Each type has important differences in their biological role in physiological and pathological conditions. In response to injury, cholangiocytes become reactive and acquire a neuroendocrine-like phenotype with the secretion of a number of peptides. These molecules act in an autocrine/paracrine fashion to modulate cholangiocyte biology and determine the evolution of biliary damage. The failure of such mechanisms is believed to influence the progression of cholangiopathies, a group of diseases that selectively target biliary cells. Therefore, the understanding of mechanisms regulating cholangiocyte response to injury is expected to foster the development of new therapeutic options to treat biliary diseases. In the present review, we will discuss the most recent findings in the mechanisms driving cholangiocyte adaptation to damage, with particular emphasis on molecular pathways that are susceptible of therapeutic intervention. Morphogenic pathways (Hippo, Notch, Hedgehog), which have been recently shown to regulate biliary ontogenesis and response to injury, will also be reviewed. In addition, the results of ongoing clinical trials evaluating new drugs for the treatment of cholangiopathies will be discussed.

Disease control with sunitinib in advanced intrahepatic cholangiocarcinoma resistant to gemcitabine-oxaliplatin chemotherapy

Advanced cholangiocarcinoma is associated with poor prognostic survival and has limited therapeutic options available at present. The importance of angiogenesis and expression of pro-angiogenic factors in intrahepatic forms of cholangiocarcinoma suggest that therapies targeting angiogenesis might be useful for the treatment of this disease. Here we report three cases of patients with advanced intrahepatic cholangiocarcinoma progressive after standard chemotherapy and treated with sunitinib 50 mg/d in 6-wk cycles of 4 wk on treatment followed by 2 wk off treatment (Schedule 4/2). In all three patients, sunitinib treatment was associated with a sustained disease control superior to 4 mo, patients achieving either a partial response or stable disease. A reduction in tumor size and density was observed in all cases, suggesting tumor necrosis as a result of sunitinib treatment in these patients. In addition, sunitinib was generally well tolerated and the occurrence of side effects was managed with standard medical interventions, as required. Our results suggest that sunitinib therapy may be associated with favorable outcomes and tolerability in patients with advanced cholangiocarcinoma. Those observations contributed to launch a prospective phase II multicenter trial investigating sunitinib in advanced intrahepatic cholangiocarcinoma (SUN-CK study; NCT01718327).

Intraoperative management of a carbon dioxide embolus in the setting of laparoscopic cholecystectomy for a patient with primary biliary cirrhosis: A case report

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We discuss appropriate detection and management of a carbon dioxide embolus.

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We review the pathologic hepatic changes in patients with primary biliary cirrhosis.

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We postulate that cirrhosis may increase the risk of a carbon dioxide embolus.

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We share an understanding that more invasive monitoring may be helpful, but ultimately hypervigilance from the anesthesia team is the number one safeguard.

INTRODUCTION

Carbon dioxide (CO₂) embolism is a rare complication of laparoscopic cholecystectomy of which both surgeons and anesthesiologists must be aware. This paper presents a case of a CO₂ embolus that occurred in a patient with primary biliary cirrhosis (PBC) and discusses the possible correlation between these two events.

PRESENTATION OF CASE

Our patient with PBC presented with symptomatic biliary dyskinesia and was determined to be a good candidate for laparoscopic cholecystectomy. During this routine surgery a CO₂ embolus entered through the altered hepatic parenchyma and progressed to the heart leading to acute hemodynamic collapse. Rapid detection and management aided in the subsequent dissolution of the embolus and recovery of the patient.

DISCUSSION

In patients with PBC, pathological changes that have taken place in the liver may increase the risk of CO₂ embolism. Hepatic alterations that have been previously described include increased angiogenesis and vasodilation. Prior to the operation, the most appropriate method of monitoring should be determined for patients with known liver disease.

CONCLUSION

Both the surgical and anesthesia team must keep in mind the potential for CO₂ embolism during laparoscopic surgery. It is imperative that the medical staff be aware of the risks, signs, and subsequent management so this rare, but potentially fatal event can be managed appropriately.

miR-101 inhibits cholangiocarcinoma angiogenesis through targeting vascular endothelial growth factor (VEGF)

Recent evidence has suggested an important role of miRNAs in liver biology and diseases, although the implication of miRNAs in cholangiocarcinoma remains to be defined further. This study was designed to examine the biological function and molecular mechanism of miR-101 in cholangiocarcinogenesis and tumor progression. In situ hybridization and quantitative RT-PCR were performed to determine the expression of miR-101 in human cholangiocarcinoma tissues and cell lines. Compared with noncancerous biliary epithelial cells, the expression of miR-101 is decreased in 43.5% of human cholangiocarcinoma specimens and in all three cholangiocarcinoma cell lines used in this study. Forced overexpression of miR-101 significantly inhibited cholangiocarcinoma growth in severe combined immunodeficiency mice. miR-101-overexpressed xenograft tumor tissues showed decreased capillary densities and decreased levels of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2). The VEGF and COX-2 mRNAs were identified as the bona fide targets of miR-101 in cholangiocarcinoma cells by both computational analysis and experimental assays. miR-101 inhibits cholangiocarcinoma angiogenesis by direct targeting of VEGF mRNA 3'untranslated region and by repression of VEGF gene transcription through inhibition of COX-2. This study established a novel tumor-suppressor role of miR-101 in cholangiocarcinoma and it suggests the possibility of targeting miR-101 and related signaling pathways for future therapy.

Aquaporin-1 is associated with arterial capillary proliferation and hepatic sinusoidal transformation contributing to portal hypertension in primary biliary cirrhosis

Although aquaporins (AQPs) in normal hepatobiliary system have been studied, little is known about AQP localization and changes in the hepatic microvascular system including sinusoids in cholestatic liver. The present study aimed to clarify the localization of AQP-1 in the microvessels in normal human liver and in primary biliary cirrhosis (PBC). Human normal liver (control) and PBC liver specimens were obtained. Immunohistochemistry, Western blotting, in situ hybridization (ISH) and electron microscopic examination for AQP-1 were conducted. In control liver and stages I-II PBC liver, AQP-1 immunoreactivity was mainly localized in portal venules, hepatic arterioles and bile ducts in the portal tract, but was hardly detected in the sinusoids. However, AQP-1 expression was enhanced in the proliferated bile ductules in PBC. In stages III-IV PBC liver tissues, AQP-1 was aberrantly expressed in proliferated arterial capillaries opening into the sinusoids at the peripheral edge of regenerating hepatic nodules and in the fibrotic septa. Overexpression of AQP-1 at protein and mRNA levels was demonstrated by Western blot and ISH, respectively. Angiogenetic and fibrotic responses are probably induced by AQP-1, leading to enhanced pouring of arterial blood into the sinusoids; thus, contributing to progression of portal hypertension in PBC.

Cholangiocarcinoma pathogenesis: Role of the tumor microenvironment

Cholangiocarcinoma is a tumor that originates from the neoplastic transformation of the epithelial cells of the intrahepatic or extrahepatic bile ducts. This type of cancer is difficult to diagnose, extremely aggressive, and has very poor prognosis. It is also relatively resistant to chemotherapy and radiation therapy. Its pathogenesis is poorly understood, however it is known that the tumor microenvironment is a very important factor in the regulation of tumor angiogenesis, invasion, and metastasis. The current knowledge about the mechanisms by which these events are regulated as well as the role of the tumor microenvironment in the pathogenesis and classification of cholangiocarcinoma will be discussed.

Transcapsular arterial neovascularization after liver transplantation in pediatric patients indicates transplant failure

PURPOSE

To identify transcapsular arterial neovascularization with Doppler ultrasonography (US) in pediatric patients after liver transplantation and to assess the frequency of the finding, its underlying causes, and its relevance in terms of clinical outcome.

MATERIALS AND METHODS

The study was approved by the local ethics committee, with waived informed consent. All pediatric patients who underwent liver transplantation between January 2000 and December 2003 were retrospectively evaluated. Patients were followed up until June 2008, by using a predefined US protocol with prospective documentation. Of 182 consecutive liver transplantations performed in 162 patients (mean age, 4.5 years; range, 0.1-18.4 years) in this period, 25 patients with a total of 27 liver transplantations underwent US examinations conducted by multiple investigators and were primarily excluded. Student t tests and χ(2) tests were performed where appropriate. The Tarone-Ware test was used to compare transplant survival times.

RESULTS

Transcapsular arterial neovascularization was noticed in 13 of 137 patients (9.5%) and in 13 of 155 liver transplants (8.4%). The mean time until arterial neovessels appeared was 157 days after liver transplantation (median, 97 days; range, 19-477 days). Arterial neovascularization was associated with pronounced transplant malperfusion and inflammatory changes (P < .001). Patients with transcapsular arterial neovascularization had a significantly shorter mean transplant survival time (1426.4 days ± 244.5 [standard error], with 95% confidence interval: 947.23, 1905.23, vs 2526.4 days ± 92.1, with 95% confidence interval: 2345.84, 2706.97; P = .008) and a higher retransplantation rate (53.8% vs 19.7%, P = .009).

CONCLUSION

Transcapsular arterial neovascularization, detected with color Doppler US, occurred in 9.5% (13 of 137) of pediatric patients and 8.4% (13 of 155) of liver transplants and was associated with underlying malperfusion and inflammation. The diagnosis of transcapsular arterial neovascularization was associated with reduced graft survival times and a high retransplantation rate. The negative prognostic value of the sign may assist in a strategy of organ allocation.

Sorafenib therapy for hepatocellular carcinoma prior to liver transplant is associated with increased complications after transplant

This study compared post-transplant outcomes of patients with hepatocellular carcinoma (HCC) who took sorafenib prior to orthotopic liver transplantation (OLT) with those patients who were not treated with sorafenib. Thirty-three patients with HCC who were listed for liver transplantation were studied: 10 patients were treated with sorafenib prior to transplantation in an attempt to prevent progression of HCC while awaiting transplant. The remaining 23 patients were considered controls. The mean duration of sorafenib use was 19.2 (SD 25.2) weeks. Overall death rates were similar between the sorafenib group and control group (20% vs. 8.7%, respectively, P = 0.56). However, the patients in the sorafenib group had a higher incidence of acute cellular rejection following transplantation (67% vs. 22%, OR = 7.2, 95% CI 1.3-39.6, P = 0.04). The sorafenib group also had a higher rate of early biliary complications (67% vs. 17%, OR = 9.5, 1.6-55.0, P = 0.01). The use of sorafenib was found to be an independent predictor of post-transplant biliary complications (OR 12.6, 1.4-116.2, P = 0.03). Sorafenib administration prior to OLT appears to be associated with an increase in biliary complications and possibly in acute rejection following liver transplantation. Caution should be taken in this setting until larger studies are completed.

Recent advances in the regulation of cholangiocarcinoma growth

Cholangiocarcinomas arise after the neoplastic transformation of the cholangiocytes that line the intra- and extrahepatic biliary epithelium. Symptoms usually do not present until late in the course of the disease, at which time they are relatively resistant to chemotherapeutic agents and as such are difficult to treat and display a poor prognosis. Because of the relative rarity of this disease, the overall volume of research into the molecular pathophysiology associated with this disease is small compared with other more prevalent tumors. However, the incidence of this devastating cancer is on the rise and renewed efforts to understand the pathogenesis of cholangiocarcinoma is needed to design novel therapeutic strategies to combat this disease. This review summarizes the recent advances into our knowledge and understanding of cholangiocarcinoma and highlights potential novel therapeutic strategies that may prove useful to treat this deadly disease.