Vascular plexus around intrahepatic bile ducts in normal livers and portal hypertension

Relationships between congenital peritoneopericardial diaphragmatic hernia or congenital central diaphragmatic hernia and ductal plate malformations in dogs and cats

OBJECTIVE

To characterize the association between peritoneopericardial diaphragmatic hernia (PPDH) or congenital central diaphragmatic hernia (CCDH) and ductal plate malformations (DPMs) in dogs and cats.

ANIMALS

18 dogs and 18 cats with PPDH or CCDH and 19 dogs and 18 cats without PPDH or CCDH.

PROCEDURES

Evaluation of clinical details verified PPDH or CCDH and survival times. Histologic features of nonherniated liver samples were used to categorize DPM. Immunohistochemical staining for cytokeratin-19 distinguished bile duct profiles per portal tract and for Ki-67-assessed cholangiocyte proliferation. Histologic features of herniated liver samples from PPDH or CCDH were compared with those of pathological controls (traumatic diaphragmatic hernia, n = 6; liver lobe torsion, 6; ischemic hepatopathy, 2).

RESULTS

DPM occurred in 13 of 18 dogs with the proliferative-like phenotype predominating and in 15 of 18 cats with evenly distributed proliferative-like and Caroli phenotypes. Congenital hepatic fibrosis DPM was noted in 3 dogs and 2 cats and renal DPM in 3 dogs and 3 cats. No signalment, clinical signs, or clinicopathologic features discriminated DPM. Kaplan Meier survival curves were similar in dogs and cats. Bile duct profiles per portal tract in dogs (median, 5.0; range, 1.4 to 100.8) and cats (6.6; 1.9 to 11.0) with congenital diaphragmatic hernias significantly exceeded those in healthy dogs (1.4; 1.2 to 1.6) and cats (2.3; 1.7 to 2.6). Animals with DPM lacked active cholangiocyte proliferation. Histologic features characterizing malformative bile duct profiles yet without biliary proliferation were preserved in herniated liver lobes in animals with DPM.

CONCLUSIONS AND CLINICAL RELEVANCE

DPM was strongly associated with PPDH and CCDH. Because DPM can impact health, awareness of its coexistence with PPDH or CCDH should prompt biopsy of nonherniated liver tissue during surgical correction of PPDH and CCDH.

A new pathological classification of intrahepatic cholangiocarcinoma according to protein expression of SSTR2 and Bcl2

Background

No universal classification method for intrahepatic cholangiocarcinoma (IHCC) has been reported based on the embryological origin of biliary epithelial cells. The aim of this study was to classify IHCC according to protein expression levels of somatostatin receptor 2 (SSTR2) and b-cell leukemia/lymphoma 2 (Bcl2) and to elucidate the clinicopathological features of each group.

Methods

Fifty-two IHCC patients who underwent hepatic resection were enrolled in this study. Protein expression levels of SSTR2 and Bcl2 were examined using immunohistochemistry. Clinicopathological factors were compared between the three groups and prognostic factors were investigated.

Results

The patients were divided into three groups: SSTR2 positive and Bcl2 negative (p-Group H, n = 21), SSTR2 negative and Bcl2 positive (p-Group P, n = 14), and the indeterminate group (p-Group U, n = 17) for cases where SSTR2 and Bcl2 were both positive or both negative. All p-Group P cases displayed curability A or B. The 5-year survival rates of p-Group H and U patients were worse than those in p-Group P. p-Group H had higher T-factor, clinical stage, and incidence of periductal infiltration than p-Group P.

Conclusions

This method could be used to classify IHCC into peripheral and perihilar type by embryological expression patterns of SSTR2 and Bcl2.

Atherosclerosis of the right posterior hepatic artery in a patient with hilar cholangiocarcinoma undergoing left trisectionectomy: a case report of a therapeutic pitfall

BACKGROUND

We experienced a rare case of benign arterial stricture of the right posterior hepatic artery (RPHA) caused by atherosclerosis in a patient with hilar cholangiocarcinoma.

CASE PRESENTATION

A 75-year-old man was referred to our hospital for the detailed investigation of serum hepatobiliary enzyme elevation. The patient had a history of hypertension, type 2 diabetes mellitus, and an operative history of coronary artery bypass grafting 10 years before. Endoscopic retrograde cholangiography found strictures of the right and left hepatic ducts with involvement of right anterior and posterior bile ducts. Adenocarcinoma was evident by brush cytology. We diagnosed these findings as hilar cholangiocarcinoma and planned left trisectionectomy including bile duct reconstruction. Although the tumor and RPHA were not adjacent, preoperative multidetector computed tomography revealed a stricture of the RPHA that was 5.6 mm in length. We suspected that atherosclerosis caused the stricture, and we performed digital subtraction angiography and intravascular ultrasonography that showed stricture of the RPHA accompanied by thick plaques in the arterial wall. We placed a bare-metal stent in the RPHA and then performed left trisectionectomy. Since this patient developed bile leakage postoperatively, percutaneous drainage was performed. The bile leakage was successfully controlled, and the patient was discharged 3 months after surgery. Unfortunately, 4 months after hepatectomy, he was re-hospitalized with multiple pyogenic liver abscesses. We performed intensive multimodal treatment for the liver abscesses and stabilized the disease; however, we eventually lost this patient due to liver failure 14 months after surgery.

CONCLUSION

To the best of our knowledge, there is no previous literature on atherosclerosis of the RPHA, which was evident preoperatively in our case. Because arterial complications may lead to critical biliary complications in patients who undergo left trisectionectomy, we first performed prophylactic arterial stent placement. We speculate that existing chronic microscopic injury of the peribiliary plexus might have caused the liver abscesses. We successfully diagnosed atherosclerosis of the RPHA preoperatively. However, further investigation of patients is warranted to determine if left trisectionectomy is contraindicated in these patients.

An Imaging and Histological Study on Intrahepatic Microvascular Passage of Contrast Materials in Rat Liver

Background. Lipiodol has been applied for decades in transarterial chemoembolization to treat liver malignancies, but its intrahepatic pathway through arterioportal shunt (APS) in the liver has not been histologically revealed. This rodent experiment was conducted to provide evidence for the pathway of Lipiodol delivered through the hepatic artery (HA) but found in the portal vein (PV) and to elucidate the observed unidirectional APS. Methods. Thirty rats were divided into 5 groups receiving systemic or local arterial infusion of red-stained iodized oil (RIO) or its hydrosoluble substitute barium sulfate suspension (BSS), or infusion of BSS via the PV, monitored by real-time digital radiography. Histomorphology of serial frozen and paraffin sections was performed and quantified. Results. After HA infusion, RIO and BSS appeared extensively in PV lumens with peribiliary vascular plexus (PVP) identified as the responsible anastomotic channel. After PV infusion, BSS appeared predominantly in the PV and surrounding sinusoids and to a much lesser extent in the PVP and HA (P < 0.001). Fluid mechanics well explains the one-way-valve phenomenon of APS. Conclusions. Intravascularly injected rat livers provide histomorphologic evidences: (1) the PVP exists in between the HA and PV, which is responsible to the APS of Lipiodol; and (2) the intrahepatic vascular inflow appears HA-PVP-PV unidirectional without a physical one-way valve, which can be postulated by the fluid mechanics.

The Role of Humoral Alloreactivity in Liver Transplantation: Lessons Learned and New Perspectives

More than ten years after the initial description of the humoral theory of transplantation by Dr. Paul I. Terasaki, the significance of humoral alloimmunity in liver transplantation has yet to be clearly defined. The liver allograft has an inherent tolerogenic capacity which confers its resistance to cell-mediated as well as antibody-mediated rejection. Nevertheless, the protection against alloimmunity is not complete, and antibody-mediated tissue injury can occur in the liver graft under specific circumstances. In this article the evidence on the clinicopathologic effects of donor-specific alloantibodies in liver transplantation will be examined and interpreted in parallel with lessons learned from renal transplantation. The unique anatomic and immunologic features of the liver will be reviewed to gain new insights into the complex interactions between humoral immune system and the liver allograft.

Human ductal plate and its derivatives express antigens of cholangiocellular, hepatocellular, hepatic stellate/progenitor cell, stem cell, and neuroendocrine lineages, and proliferative antigens

Molecular mechanisms of human ductal plate (DP) development and differentiation (DD) are unclear. The author immunohistochemically investigated expressions of cholangiocellular antigens (CEA, CA19-9, EMA, MUC1, MUC2, MUC5AC, MUC6, mucins, CK7, and CK19), hepatocellular antigens (HepPar1, AFP, CK8, and CK18), hepatic stellate/progenitor cell (HSC) antigens or stem cell (SC) antigens (C-erbB2, CD56, chromogranin, synaptophysin, bcl2, NSE, NCAM, KIT, and PDGFRA), and proliferating antigen (Ki67) in 32 human fetal livers (HFL). The DD of human intrahepatic bile duct (IBD) could be categorized into four stages: DP, remodeling DP, remodeled DP, and immature IBD. All the molecules examined were expressed in the DP and DP derivatives. These results suggest that human DP or DP derivatives have capacities to differentiate into cholangiocellular, hepatocellular, HSC, SC, and neuroendocrine lineages. The data also suggest that NCAM, KIT/SC factor-signaling, NSE, HGF/MET signaling, PDGFa/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of DP and biliary cells of HFL. DP, DP derivatives, and IBD in HFL have proliferative capacity.

Ductal Plate Malformation in the Liver of Boxer Dogs: Clinical and Histological Features

Ductal plate malformations (DPMs) represent developmental biliary disorders with a wide phenotypic spectrum. This study characterizes DPM in 30 Boxer dogs. Median age was 1.5 (range, 0.3-10.0) years, with 12 dogs <1 year. Clinical features included increased serum levels of liver enzymes (28), gastrointestinal signs (16), poor body condition (14), abdominal effusion (9), and hepatic encephalopathy (2). Additional malformations included gallbladder atresia (8), atrophied left liver (2), absent quadrate lobe with left-displaced gallbladder (1), portal vasculature atresia (left liver, 1), intrahepatic portosystemic shunt (1), and complex intrahepatic arteriovenous malformation (1). All dogs had portal tracts dimensionally expanded by a moderate-to-severe multiple small bile duct phenotype embedded in abundant extracellular matrix; 80% displayed variable portal-to-portal bridging. Quantitative analysis confirmed significantly increased fibrillar collagen and a 3-fold increased portal tract area relative to 6 Boxer and 10 non-Boxer controls. Biliary phenotype was dominated by tightly formed CK19-positive ductules, typically 10 to 15 μm in diameter, with 3 to >30 profiles per portal tract, reduced luminal apertures, and negative Ki-67 immunoreactivity. CK19-positive biliary epithelium intersected directly with zone 1 hepatocytes as a signature feature when considered with other DPM characteristics. Phenotypic variation included a multiple small bile duct phenotype (all dogs), predominantly thin-walled sacculated ducts (4), well-formed saccular ducts (4), and sacculated segmental, interlobular, and intralobular ducts (Caroli malformation, 2 dogs, one with bridging portal fibrosis). Histologic evidence of portal venous hypoperfusion accompanied increased biliary profiles in every case. We propose that this spectrum of disorders be referred to as DPM with appropriate modifiers to characterize the unique phenotypes.

Altered intrahepatic microcirculation of idiopathic portal hypertension in relation to glutamine synthetase expression

AIM

Alteration in intrahepatic microcirculation of idiopathic portal hypertension (IPH) has been poorly understood. This study aimed to characterize altered intrahepatic microcirculation of IPH focusing on the expression pattern of glutamine synthetase (GS).

METHODS

Immunohistochemical staining of GS was performed using liver sections of IPH (n = 28). Serial section analysis was performed to determine microcirculatory disturbances of IPH.

RESULTS

Paraportal shunt vessels were observed in 20 cases of IPH, and they were divided into two types according to the GS staining pattern; hepatocytes surrounding the vessels were negative for GS (type 1) and positive for GS (type 2). All 20 cases had one or more type 1 vessels within a section, and 10 cases were further associated with type 2 vessels. The cases with type 2 vessels showed infrequent symptoms of esophageal varices. Regarding the GS staining as an indicator of hepatic veins, some type 2 vessels were supposed to represent portovenous shunts. Isolated arteries in hepatic parenchyma were present in 21 cases, and they were located around terminal hepatic venules in six cases, corresponding to centrizonal arteries. Broad hepatocellular GS staining in hyperplastic lesions was noted in five cases, whereas nodular regenerative hyperplasia lacked GS expression.

CONCLUSION

GS immunostaining revealed microcirculatory disturbances of IPH that were associated with abnormalities in both venous and arterial vessels.

Management of early hepatic artery occlusion after liver transplantation with failed rescue

Hepatic artery thrombosis is a serious complication after liver transplantation which often results in biliary complications, early graft loss, and patient death. It is generally thought that early hepatic artery thrombosis without urgent re-vascularization or re-transplantation almost always leads to mortality, especially if the hepatic artery thrombosis occurs within a few days after transplantation. This series presents 3 cases of early hepatic artery thrombosis after living donor liver transplantation, in which surgical or endovascular attempts at arterial re-vascularization failed. Unexpectedly, these 3 patients survived with acceptable graft function after 32 mo, 11 mo, and 4 mo follow-up, respectively. The literatures on factors affecting this devastating complication were reviewed from an anatomical perspective. The collective evidence from survivors indicated that modified nonsurgical management after liver transplantation with failed revascularization may be sufficient to prevent mortality from early hepatic artery occlusion. Re-transplantation may be reserved for selected patients with unrecovered graft function.

Ontogenic development of nerve fibers in human fetal livers: an immunohistochemical study using neural cell adhesion molecule (NCAM) and neuron-specific enolase (NSE)

The aim of the study was to investigate nerve fibers (NF) in human fetal livers. An immunohistochemical study was performed. NF were classified into portal tract innervation (PoI) and parenchymal innervation (PaI). The hilum area showed many Pol NF at 7 GW, and NF increased with gestational week (GW). Direct innervations to biliary epithelium were recognized. In large portal tracts, a few NCAM-positive mesenchymal cells were seen at 8 GW and many mesenchymal cells were noted around 12 GW. Apparent NF emerged around 15 GW, and NF increased with GW. Many NF plexuses were seen in 30-40 GW. In small portal tracts, no NF were seen in 7-10 GW. A few NCAM-positive mesenchymal cells emerged in 11 GW, and they increased thereafter. Apparent NF were seen around 20 GW and NF increased with GW. At term (40 GW), PoI NF were still immature. Ductal plate (DP) was positive for NCAM, NSE, chromogranin and synaptophysin, and direct innervations to DP were seen. The direct innervations to developing bile ducts and peribiliary glands were also seen. PaI NF were first seen at 21 GW and was consistent until 40 GW in which a few NF were seen in PaI. These observations suggest that PoI NF arise from committed portal mesenchyme. PaI NF are very immature at 40 GW. There are direct innervations to bile ducts, peribiliary glands, portal veins, hepatic arteries, and DP.

Human fetal ductal plate revisited. I. ductal plate expresses NCAM, KIT, MET, PDGFRA, and neuroendocrine antigens (NSE, chromogranin, synaptophysin, and CD56)

BACKGROUND

The molecular mechanisms of ductal plate (DP) development and differentiation (DD) in human fetal livers (HFLs) are unclear.

MATERIALS AND METHODS

The author immunohistochemically investigated expressions of NCAM, KIT, KIT, PDGFRA, and neuroendocrine antigens in 32 HFLs.

RESULTS

The processes of human intrahepatic bile duct (IBD) DD could be categorized into four stages: DP, remodeling DP, remodeled DP, and mature IBD. NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. The biliary elements were positive for cytokeratin (CK)7, 8, 18, and 19. The hepatoblasts were positive for CK8 and CD18, but negative for CK7 and CK19; however, periportal hepatoblasts showed biliary-type CKs (CK7 and CK19). NCAM was always expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. KIT was occasionally (12/32 cases) expressed in DP and remodeling DP, but not in remodeled DP and mature IBD. NCAM expression was also seen in some hepatoblasts and hematopoietic cells and neurons. KIT was also expressed in some hepatoblasts, hematopoietic cells, and mast cells. MET and PDGFRA were strongly expressed in DP, remodeling DP, remodeled DP, and mature IBD. MET and PDGFRA were also strongly expressed in hepatoblasts and hematopoietic cells. MET and PDGFRA were not expressed in portal mesenchyme, portal veins, sinusoids, and hepatic veins. DP showed immunoreactive chromogranin, synaptophysin, neuron-specific enolase (NSE), and CD56. Expressions of chromogranin and CD56 were infrequently seen in remodeling DP. No expressions of these four neuroendocrine antigens were seen in remodeled DP and mature IBD. The nerve fibers were consistently positive for chromogranin, synaptophysin, NSE, and CD56 in the portal mesenchyme in the stages of remodeling DP, remodeled DP, and mature IBDs.

CONCLUSIONS

The data suggest that NCAM, KIT/stem cell factor-signaling, NSE, hepatocyte growth factor/MET signaling, PDGFα/PDGFRA signaling, chromogranin, synaptophysin, and CD56 play important roles in DD of biliary cells of HFL. They also suggest that the DP cells having neuroendocrine molecules give rise to hepatic stem/progenitor cells.

Biliary tract anatomy and its relationship with venous drainage

Portal cavernoma develops as a bunch of hepatopetal collaterals in response to portomesenteric venous obstruction and induces morphological changes in the biliary ducts, referred to as portal cavernoma cholangiopathy. This article briefly reviews the available literature on the vascular supply of the biliary tract in the light of biliary changes induced by portal cavernoma. Literature pertaining to venous drainage of the biliary tract is scanty whereas more attention was focused on the arterial supply probably because of its significant surgical implications in liver transplantation and development of ischemic changes and strictures in the bile duct due to vasculobiliary injuries. Since the general pattern of arterial supply and venous drainage of the bile ducts is quite similar, the arterial supply of the biliary tract is also reviewed. Fine branches from the posterior superior pancreaticoduodenal, retroportal, gastroduodenal, hepatic and cystic arteries form two plexuses to supply the bile ducts. The paracholedochal plexus, as right and left marginal arteries, run along the margins of the bile duct and the reticular epicholedochal plexus lie on the surface. The retropancreatic, hilar and intrahepatic parts of biliary tract has copious supply, but the supraduodenal bile duct has the poorest vascularization and hence susceptible to ischemic changes. Two venous plexuses drain the biliary tract. A fine reticular epicholedochal venous plexus on the wall of the bile duct drains into the paracholedochal venous plexus (also called as marginal veins or parabiliary venous system) which in turn is connected to the posterior superior pancreaticoduodenal vein, gastrocolic trunk, right gastric vein, superior mesenteric vein inferiorly and intrahepatic portal vein branches superiorly. These pericholedochal venous plexuses constitute the porto-portal collaterals and dilate in portomesenteric venous obstruction forming the portal cavernoma.

Melatonin regulation of biliary functions

The intrahepatic biliary epithelium is a three-dimensional tubular system lined by cholangiocytes, epithelial cells that in addition to modify ductal bile are also the targets of vanishing bile duct syndromes (i.e., cholangiopathies) such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) that are characterized by the damage/proliferation of cholangiocytes. Cholangiocyte proliferation is critical for the maintenance of the biliary mass and secretory function during the pathogenesis of cholangiopathies. Proliferating cholangiocytes serve as a neuroendocrine compartment during the progression of cholangiopathies, and as such secrete and respond to hormones, neurotransmitters and neuropeptides contributing to the autocrine and paracrine pathways that regulate biliary homeostasis. The focus of this review is to summarize the recent findings related to the role of melatonin in the modulation of biliary functions and liver damage in response to a number of insults. We first provide a general background on the general function of cholangiocytes including their anatomic characteristics, their innervation and vascularization as well the role of these cells on secretory and proliferation events. After a background on the synthesis and regulation of melatonin and its role on the maintenance of circadian rhythm, we will describe the specific effects of melatonin on biliary functions and liver damage. After a summary of the topics discussed, we provide a paragraph on the future perspectives related to melatonin and liver functions.

Physiology of cholangiocytes

Cholangiocytes are epithelial cells that line the intra- and extrahepatic ducts of the biliary tree. The main physiologic function of cholangiocytes is modification of hepatocyte-derived bile, an intricate process regulated by hormones, peptides, nucleotides, neurotransmitters, and other molecules through intracellular signaling pathways and cascades. The mechanisms and regulation of bile modification are reviewed herein.

Recent advances in the morphological and functional heterogeneity of the biliary epithelium

This review focuses on the recent advances related to the heterogeneity of different-sized bile ducts with regard to the morphological and phenotypical characteristics, and the differential secretory, apoptotic and proliferative responses of small and large cholangiocytes to gastrointestinal hormones/peptides, neuropeptides and toxins. We describe several in vivo and in vitro models used for evaluating biliary heterogeneity. Subsequently, we discuss the heterogeneous proliferative and apoptotic responses of small and large cholangiocytes to liver injury and the mechanisms regulating the differentiation of small into large (more differentiated) cholangiocytes. Following a discussion on the heterogeneity of stem/progenitor cells in the biliary epithelium, we outline the heterogeneity of bile ducts in human cholangiopathies. After a summary section, we discuss the future perspectives that will further advance the field of the functional heterogeneity of the biliary epithelium.

Aquaporin-1 associated with hepatic arterial capillary proliferation on hepatic sinusoid in human cirrhotic liver

BACKGROUND

Aquaporins (AQPs) are key regulators not only of water transport in the cytoplasm but also of angiogenesis. Although AQPs in the normal hepatobiliary system have been studied in mammals, little is known about the localization and changes of AQPs in the hepatic microvascular system including sinusoids in cirrhotic liver, which might contribute to portal hypertension.

AIMS

We designed this study to examine the localization of AQP1 in human cirrhotic liver.

METHODS

Surgical wedge biopsy specimens were obtained from non-cirrhotic portions of human livers (normal control) and from cirrhotic livers (LC) (Child A-LC and Child C-LC). Immunostaining, Western blotting, in situ hybridization (ISH) and laser-captured microdissection (LCM) were conducted.

RESULTS

In control liver tissue, AQP1 was localized mainly in the portal venules, hepatic arterioles and bile ducts in the portal tract, although AQP1 was detected only slightly in the sinusoids. In cirrhotic liver tissue, AQP1 expression was evident, aberrantly observed on periportal sinusoidal endothelial cells corresponding to the capillarized sinusoids, on the proliferated arterial capillaries opening into the sinusoid in the generating hepatic nodule and on proliferated bile ductules at the peripheral edge of nodules and fibrotic septa. In cirrhotic liver, overexpression of AQP1 at protein and mRNA levels was demonstrated, respectively, using Western blot and ISH. AQP-1 of mRNA level in sinusoid was confirmed using LCM.

CONCLUSIONS

Aberrant expressions of AQP1 in periportal sinusoidal regions in human cirrhotic liver indicate the proliferation of arterial capillaries directly connected to the sinusoids, contributing to microvascular resistance in cirrhosis.

Portal blood flow via the peribiliary vascular plexus demonstrated by contrast-enhanced ultrasonography with Sonazoid

PURPOSE

We report two cases in which portal blood flow via the peribiliary vascular plexus (PBP) was clearly demonstrated using contrast-enhanced intra-operative ultrasonography (CE-IOUS).

METHODS

Two patients who underwent hemihepatectomies were investigated using CE-IOUS. Before injection of the contrast medium, both the hepatic arterial and portal venous flows of the hemiliver to be resected were interrupted by ligating those corresponding vessels at the hepatic hilum. Subsequently, the perfluorobutane microbubbles were injected intravenously.

RESULTS

In the early vascular phase, a remarkable intermittent flow was visualized in the lumen of the portal branches whose inflows were interrupted. The flow of the portal vein then disappeared as a result of ligating the hepatic duct concomitantly with the surrounding connective tissue. We considered that the portal venous flow appearing under the condition of total disruption of original inflow was supplied from the hepatic artery through the PBP.

CONCLUSIONS

This is the first report of blood flow via the PBP in human liver visualized by dynamic image study.

Monolobar ductal plate malformation disease of the liver

We herein report a unique monolobar hepatic disease composed of Caroli's disease, peribiliary cysts, ductal plate malformations, peribiliary gland proliferation, hepatolithiasis, and portal phlebosclerosis with thrombi. A 73-year-old man underwent abdominal imaging, which revealed multiple segmental dilations of the left intrahepatic bile ducts. Polycystic kidney diseases were absent. Intrahepatic cholangiocarcinoma was suspected, and extended left lobectomy of the liver was preformed. Grossly, the hepatic left lobe was atrophic, and partly replaced by fibrous tissue. The intrahepatic bile ducts were dilated (Caroli's disease), and showed small calcium bilirubinate hepatoliths. Microscopically, the intrahepatic bile duct showed non-obstructive segmental dilations (Caroli's disease), numerous peribiliary cysts, numerous ductal plate malformations, proliferation of intrahepatic peribiliary glands, and calcium bilirubinate hepatolithiasis. Portal veins showed phlebosclerosis with thrombi. Immunohistochemically, the various biliary epithelial cells were positive for cytokeratin (CK) 7, 8, 18, and 19, and for MUC6 and CD10. They were negative for MUC2 and MUC5AC. The ductal plate malformations were positive for fetal biliary antigen MUC1, but other biliary cell types were negative for MUC1. The present case resembles 'monolobar Caroli's disease'. We believe that the present monolobular liver disease was congenital in origin.

Monolobar hepatobiliary fibropolycystic disease

We herein report a case of monolobar hepatobiliary fibropolycystic disease. A 75-year-old woman presented with heartburn. Imaging modalities including US, CT, and MRI revealed marked atrophy and multiple biliary cysts of the hepatic left lobe. The hepatic right lobe was normal. ERCP and bile duct endoscopy revealed anomalous pancreaticobiliary union, choledochal dilation, dilation of left intrahepatic bile ducts, and small choledochal non-invasive adenocarcinoma. Polycystic kidney diseases were absent. The patient underwent pancreatico-duodenectomy and extended hepatic left lobectomy. Grossly, the hepatic left lobe was markedly atrophic, and studded with numerous biliary cysts. The left intrahepatic bile ducts were dilated (Caroli's disease) and the common bile duct showed type I choledochal dilation. The right hepatic lobe was normal. Histologically, the hepatic left lobe was replaced by fibroelastosis. The intrahepatic bile ducts showed ductal plate malformation such as irregular contours, invaginations, and protrusions. The numerous biliary cysts also showed ductal plate malformation. There were numerous persistent ductal plates and microhamartomas. Many hyalinized destructive biliary cysts and ductal plates were recognized. The liver parenchyma was scant and free of hepatocellular malformations. The portal veins showed old obliterative portal thrombosis. The right hepatic lobe was normal. Immunohistochemically, the biliary cells were positive for cytokeratin 7, 8, 18 and 19, and MUC6 and CD10, but negative for MUC2 and MUC5AC. The biliary cysts, persistent ductal plate, and microhamartomas were positive for fetal apomucin antigen MUC1.

Safety of combined resection of the middle hepatic artery in right hemihepatectomy for hilar biliary malignancy

BACKGROUND/PURPOSE

In patients with hilar biliary malignancies, preservation of the middle hepatic artery (MHA, segment IV artery) where it runs close to the tumor in the hepatic hilum may lead to resection with positive margins. This retrospective study assessed the safety of combined resection of the MHA with right hemihepatectomy, caudate lobectomy, and bile duct resection for hilar biliary malignancies.

METHODS

Of 61 patients with hilar biliary malignancies who underwent right hemihepatectomy, we classified the branching patterns of the MHA according to the origins and courses in the hilum. The MHA was resected without reconstruction in 16 patients in whom the artery ran close to the tumor. We compared the perioperative outcomes in these patients with those of patients who did not undergo resection of the artery.

RESULTS

Anatomically, the MHA ran on the right side of the umbilical portion of the portal vein in 40 (66%) patients. Perioperative data for the patients who underwent combined resection were similar to those in whom the MAH was preserved. There were no postoperative complications that could be directly related to the arterial resection.

CONCLUSIONS

Combined resection of the MHA during right hemihepatectomy for hilar biliary malignancies has a safe perioperative course.

Vascular development and differentiation during human liver organogenesis

The vascular architecture of the human liver is established at the end of a complex embryological history. The hepatic primordium emerges at the 4th week and is in contact with two major venous systems of the fetal circulation: the vitelline veins and the umbilical veins. The fetal architecture of the afferent venous circulation of the liver is acquired between the 4th and the 6th week. At the end of this process, the portal vein is formed from several distinct segments of the vitelline veins; the portal sinus, deriving from the subhepatic intervitelline anastomosis, connects the umbilical vein, which is the predominant vessel of the fetal liver, to the portal system; the ductus venosus connects the portal sinus to the vena cava inferior. At birth, the umbilical vein and the ductus venosus collapse; the portal vein becomes the only afferent vein of the liver. The efferent venous vessels of the liver derive from the vitelline veins and are formed between the 4th and the 6th week. The hepatic artery forms at the 8th week; intrahepatic arterial branches progressively extend from the central to the peripheral areas of the liver between the 10th and the 15th week. Hepatic sinusoids appear very early, as soon as hepatic cords invade the septum transversum at the 4th week. They then progressively acquire their distinctive structural and functional characters, through a multistage process. Vascular development and differentiation during liver organogenesis is, therefore, a unique process; many of the cellular and molecular mechanisms involved remain poorly understood.

Dynamics of the vascular profile of the finer branches of the biliary tree in normal and diseased human livers

BACKGROUND/AIMS

Results of our previous studies supported the concept that in the human liver, the smallest ramification of the biliary tree, the bile ductules, might contain hepatic progenitor cells. An insufficient proliferative response and loss of bile ductules preceded bile duct loss whereas preservation of bile ductules mitigated bile duct loss.

METHODS

Presently we investigated the vascular profile of the bile ductules in diseased human livers and livers showing normal histological features as controls, using CD34, CK7 and alphaSMA antibodies in a double immunolabeling technique. VEGF-A expression was also studied. In control livers bile ductules traversed the boundaries of the portal tract into the lobule as ductular-vascular units, in a pattern outlining the classic hexagonal lobule, following the vascular septa. The latter are thought to be extensions of portal veins. In diseased states the two structures reacted in unison. Increased or decreased numbers of ductules were consistently accompanied by similar changes of accompanying microvessels. Increased numbers of ductules and microvessels were paralleled by increased ductular expression of VEGF-A.

RESULTS

Our data support the concept that the smallest branches of the biliary tree might have their own vascular supply and that the ductules might in turn maintain their vasculature during regenerative processes.

Heterogeneity of the intrahepatic biliary epithelium

The objectives of this review are to outline the recent findings related to the morphological heterogeneity of the biliary epithelium and the heterogeneous pathophysiological responses of different sized bile ducts to liver gastrointestinal hormones and peptides and liver injury/toxins with changes in apoptotic, proliferative and secretory activities. The knowledge of biliary function is rapidly increasing because of the recognition that biliary epithelial cells (cholangiocytes) are the targets of human cholangiopathies, which are characterized by proliferation/damage of bile ducts within a small range of sizes. The unique anatomy, morphology, innervation and vascularization of the biliary epithelium are consistent with function of cholangiocytes within different regions of the biliary tree. The in vivo models [e.g., bile duct ligation (BDL), partial hepatectomy, feeding of bile acids, carbon tetrachloride (CCl₄) or α-naphthylisothiocyanate (ANIT)] and the in vivo experimental tools [e.g., freshly isolated small and large cholangiocytes or intrahepatic bile duct units (IBDU) and primary cultures of small and large murine cholangiocytes] have allowed us to demonstrate the morphological and functional heterogeneity of the intrahepatic biliary epithelium. These models demonstrated the differential secretory activities and the heterogeneous apoptotic and proliferative responses of different sized ducts. Similar to animal models of cholangiocyte proliferation/injury restricted to specific sized ducts, in human liver diseases bile duct damage predominates specific sized bile ducts. Future studies related to the functional heterogeneity of the intrahepatic biliary epithelium may disclose new pathophysiological treatments for patients with cholangiopathies.

Cholangiocytes and blood supply

The microvascular supply of the biliary tree, the peribiliary plexus (PBP), stems from the hepatic artery branches and flows into the hepatic sinusoids. A detailed three-dimensional study of the PBP has been performed by using the Scanning Electron Microscopy vascular corrosion casts (SEMvcc) technique. Considering that the PBP plays a fundamental role in supporting the secretory and absorptive functions of the biliary epithelium, their organization in either normalcy and pathology is explored. The normal liver shows the PBP arranged around extra- and intrahepatic biliary tree. In the small portal tract PBP was characterized by a single layer of capillaries which progressively continued with the extrahepatic PBP where it showed a more complex vascular network. After common duct ligation (BDL), progressive modifications of bile duct and PBP proliferation are observed. The PBP presents a three-dimensional network arranged around many bile ducts and appears as bundles of vessels, composed by capillaries of homogeneous diameter with a typical round mesh structure. The PBP network is easily distinguishable from the sinusoidal network which appears normal. Considering the enormous extension of the PBP during BDL, the possible role played by the Vascular Endothelial Growth Factor (VEGF) is evaluated. VEGF-A, VEGF-C and their related receptors appeared highly immunopositive in proliferating cholangiocytes of BDL rats. The administration of anti-VEGF-A or anti-VEGF-C antibodies to BDL rats as well as hepatic artery ligation induced a reduced bile duct mass. The administration of rVEGF-A to BDL hepatic artery ligated rats prevented the decrease of cholangiocyte proliferation and VEGF-A expression as compared to BDL control rats. These data suggest the role of arterial blood supply of the biliary tree in conditions of cholangiocyte proliferation, such as it occurs during chronic cholestasis. On the other hand, the role played by VEGF as a tool of cross-talk between cholangiocytes and PBP endothelial cells suggests that manipulation of VEGF release and function could represent a therapeutic strategy for human pathological conditions characterized by damage of hepatic artery or the biliary tree.

The finest branches of the biliary tree might induce biliary vascularization necessary for biliary regeneration

BACKGROUND/AIMS

The finer branches of the biliary tree play an important role in biliary regeneration. They are consistently escorted by microvessels. Defects in the vascularization of these structures could impair bile duct regeneration. Therefore, we investigated the pattern of the escorting microvessels during the development of bile duct loss in the human liver, using chronic rejection as a model.

METHODS

The number of interlobular bile ducts, bile ductules and extraportal biliary cells with and without escorting microvessels and the expression of VEGF-A were studied in follow-up biopsies of 12 patients with chronic rejection and 16 control patients with acute rejection without progression to chronic rejection.

RESULTS

The controls showed a proliferation of bile ductules at 1-week and 1-month. Proliferation of bile ductules without microvessels preceded proliferation of bile ductules with microvessels. Proliferation of the microvascular compartment followed biliary proliferation. This sequence of events was not observed in the chronic rejection group, in which all biliary structures decreased in time. VEGF-A expression was increased at 1-week and 1-month in both groups.

CONCLUSIONS

An immediate proliferative response of the finer branches of the biliary tree followed by proliferation of the microvascular compartment after biliary injury seems to be a prerequisite for bile duct regeneration.

Hepatic artery and portal vein remodeling in rat liver: vascular response to selective cholangiocyte proliferation

Three-dimensional reconstruction of the biliary tree, hepatic artery, and portal vein in normal rats and rats fed alpha-naphthylisothiocyanate (ANIT), a compound that causes selective proliferation of epithelial cells (ie, cholangiocytes) that line the bile ducts, was performed. All hepatic structures in ANIT-fed rats branched 1.5 times more often than in normal rats, reflecting an increased number of segments, whereas the length of the biliary tree, hepatic artery, and portal vein remain unchanged. The length of the proximal vessel segments was uniform in both groups of rats whereas the length of distal segments decreased twofold in ANIT-fed rats, suggesting that small vessels preferentially undergo proliferation. In contrast, the length of all bile duct segments decreased twofold, suggesting that ANIT induced proliferation of all compartments of the biliary tree. The total volume of the biliary tree, hepatic artery, and portal vein was increased 18, 4, and 3 times, respectively, after ANIT feeding. The diameters of the bile ducts (range, 20 to 259 microm) and arterial (range, 21 to 276 microm) segments in ANIT-fed rats did not differ from normal rats (range, 21 to 245 microm and 20 to 265 microm, respectively). In contrast, the diameters of proximal venous segments in ANIT-fed rats were significantly less (316 +/- 68 micro m versus 488 +/- 89 micro m, P < 0.001). The data suggest that after experimentally induced cholangiocyte proliferation, the hepatic artery and portal vein also undergo marked proliferation, presumably to support the increased nutritional and functional demands of the proliferated bile ducts. The molecular mechanisms of these vascular changes remain to be determined.

Ischemic bile duct injury as a serious complication after transarterial chemoembolization in patients with hepatocellular carcinoma

BACKGROUND

Bile duct injuries after transarterial chemoembolization (TACE) have been reported; however, the exact pathogenic mechanisms and clinical implications of the injuries remain to be clarified.

STUDY

A total of 950 consecutive patients with hepatocellular carcinoma (HCC) were studied. Among them, 807 were treated with TACE and the remaining 143 were treated with transarterial chemoinfusion (TACI) of cisplatin.

RESULTS

None of 143 patients with HCC treated with TACI were found to have any radiographic evidence of biliary injury. In contrast, of the 807 patients treated with TACE, 17 (2%) developed biliary complications. Of all complications, 12 (71%) were subcapsular bilomas; 3 (17%), focal strictures of the common hepatic duct or common bile duct; and 2 (12%), diffuse mild dilatation of the intrahepatic bile ducts. Interestingly, 2 of the 12 bilomas were found in the lobe that was not embolized with gelatin sponge particles. The median numbers of TACE tended to be greater in the patients with focal stricture than in those with bilomas (6.0 vs. 2.5; p = 0.08). All 3 patients with focal strictures and 4 of the 12 patients with bilomas had associated serious bacterial infections at presentation.

CONCLUSIONS

Bilomas seem to be caused by iodized oil rather than gelatin sponge particles; focal strictures of large bile ducts seem to be caused by gelatin sponge particles. We suggest that adjustments in the amounts of iodized oil or gelatin sponge particles and in the sites of embolization may reduce ischemic biliary injuries after TACE.

Three-dimensional observations of the human hepatic artery (Arterial system in the liver)

BACKGROUND/AIMS

We examined the three-dimensional structures of the hepatic artery.

MATERIALS/METHODS

A 39-year-old man who died of brain hemorrhage was autopsied. The liver was perfused with physiological saline and 20% formalin from the hepatic artery and portal vein. More than 700 serial sections were obtained from a paraffin-embedded block, and vascular reconstruction was performed under a light microscope.

RESULTS

The hepatic artery divides into the axial artery and the peribiliary branch given off from it. These two systems also connect to each other by a few anastomoses. The former systematically supplies arterial blood to all the parenchymal liver cells. The latter forms two layers of plexes around the bile duct. The inner capillary layer is afferent and the outer vascular layer is efferent to the bile duct.

CONCLUSION

To maintain constant sinusoidal blood flow, the terminal portions of the axial arteries may contract and thereby divert blood to peribiliary branches through bifurcations and anastomoses. The blood flow of the peribiliary capillary plexus may affect bile flow. The hepatic artery may act as a functional mediator between portal flow and bile excretion.

Hepatic arterioportal shunts not directly related to hepatocellular carcinoma: findings on CT during hepatic arteriography, CT arterial portography and dual phase spiral CT

AIM

To evaluate findings of arterioportal shunts not directly related to hepatocellular carcinoma (HCC) which were seen within third-order portal branches on computed tomography (CT) during hepatic arteriography (CTHA), arterial portography (CTAP), and dual phase spiral CT.

MATERIALS AND METHODS

At CTHA in 112 patients, we examined third-order portal vein branches to find arterioportal shunts not directly related to HCC. Six cases were found. We evaluated the findings of these shunts on CTHA and investigated whether CTAP (n = 6) and dual phase spiral CT (n = 5) showed perfusion defects in the corresponding areas on arterioportal shunts.

RESULTS

Five of six cases showed abrupt visualization of portal branches without visualization of the proximal portion of CTHA. Five of six cases showed no perfusion defect on CTAP and no hyperattenuating area on CTHA. Four of five cases showed no hyperattenuating area on hepatic arterial phase spiral CT.

CONCLUSION

Arterioportal shunts not directly related to HCC and occuring within third-order portal branches mainly showed abrupt visualization of portal branches on CTHA. These occurred frequently without perfusion defects on CTAP and without a hyperattenuating area on CTHA and hepatic arterial phase spiral CT.Park, C. M. (2000). Clinical Radiology55, 465-470.

Peribiliary capillary plexus around interlobular bile ducts in various chronic liver diseases: An immunohistochemical and morphometric study

Peribiliary capillary plexus (PCP) is a network of capillaries which arise from the hepatic artery surrounding the intrahepatic bile ducts. We immunohistochemically investigated the density of PCP around interlobular bile ducts in various chronic liver diseases including primary biliary cirrhosis (PBC) (n = 47), autoimmune hepatitis (AIH) (n = 12), chronic hepatitis B (n = 16), chronic hepatitis C (n = 19), liver cirrhosis due to hepatitis B virus (n = 13), liver cirrhosis due to hepatitis C virus (n = 20), alcoholic hepatitis (n = 20), alcoholic liver cirrhosis (n = 17), using human liver biopsies fixed in formalin and embedded in paraffin wax. PCP was immunohistochemically detected by an endothelial marker, the CD34 antigen. The number of PCP per duct was 1.21 +/- 0.18 in normal livers. Compared with normal liver, vasopenia was observed in PBC and AIH, the number in which was 0.93 +/- 0.34 (P < 0.0001) and 0.82 +/- 0.38 (P < 0.005) per duct, respectively. In contrast, increased number of PCP was observed in liver cirrhosis due to hepatitis B or C virus, alcoholic hepatitis, and alcoholic liver cirrhosis, the number in which were 1.59 +/- 0.37 (P < 0.005), 1.55 +/- 0.52 (P < 0. 02), 1.38 +/- 0.23 (P < 0.02) and 1.61 +/- 0.33 (P < 0.002) per duct, respectively. These data suggest that PCP may be destroyed in autoimmune liver diseases, including PBC and AIH, but PCP may proliferate in other inflammatory and alcoholic liver diseases.

Case report: secondary biliary cirrhosis possibly related to congenital hepatic fibrosis. Evidence for decreased number of portal branch veins and hypertrophic peribiliary vascular plexus

A 30-year-old man with presinusoidal portal hypertension was transplanted for cryptogenic cirrhosis. On the explanted liver, few intrahepatic stones, biliary cirrhosis, chronic cholangitis of the large bile ducts and a peculiar proliferation of small dilated bile ducts at the periphery of the portal tracts led to the diagnosis of secondary biliary cirrhosis and cholangitis, possibly linked to ductal plate malformation, including congenital hepatic fibrosis associated with a minor form of Caroli's disease. Ex vivo portogram and histology showed the paucity of portal vein branches and the hypertrophy of the peribiliary vascular plexus. This hypertrophy, which has been reported in livers with presinusoidal hypertension, is another indirect argument to suggest the diagnosis of congenital hepatic fibrosis.

Ischemic cholangitis

Ischemia-induced bile duct lesions have been collectively labeled as ischemic cholangitis. The biliary epithelium is dependent on arterial blood flow, unlike the hepatic parenchyma with its dual arterial and portal venous blood supply. As such, the biliary epithelium is susceptible to injury when arterial blood flow is compromised. This compromise can occur at the level of the major, named hepatic artery branches or at the microscopic, peribiliary capillary plexus level. Typically, ischemic cholangitis manifests as segmental strictures and cholangiectases with resultant mechanical impairment of bile flow and, occasionally, secondary infection of the biliary system. Ischemic cholangitis after liver transplantation is becoming an important problem and likely is attributable to numerous factors. Hepatic arterial infusion of chemotherapy and systemic vasculitis are other causes of ischemic cholangitis. The role of ischemia in other chronic biliary and ductopenic diseases remains speculative.

Peribiliary vascular plexus in primary sclerosing cholangitis and primary biliary cirrhosis

The peribiliary vascular plexus plays an important role in physiology of bile flow. Disturbance of the microcirculation may contribute to ductal injury, but little is known about alterations in the vascular supply of small bile ducts in liver disease. Immunoperoxidase stains for vascular endothelium (Ulex europaeus, factor VIII-related antigen, CD34) were used to study the peribiliary vascular plexus in 20 cases of primary sclerosing cholangitis (PSC) and 27 cases of primary biliary cirrhosis (PBC), two diseases characterized by bile duct destruction. Normal liver from 10 autopsy cases of sudden cardiac death was used as a control. Interlobular bile ducts (20- to 80-microm diameter) were identified on AE1/AE3 immunostain; vessels adjacent to the basement membrane of these ducts were counted. Normal interlobular bile ducts had an average of 2.15 vessels per duct (range, 1.68 to 2.71). Few PBC or PSC cases had a normal number of peribiliary vessels. There was a trend toward vasopenia at higher stage, although vascular loss was noted in early stages as well. The pattern of vascular loss was different for the two diseases; in PSC, the periductal capillaries were often preserved but were pushed away from the basement membrane by concentric deposits of collagen. Small residual vessels could be identified within fibrous scars of obliterated bile ducts in PSC. In 4 stage 3 or 4 PSC cases with little bile duct injury, vessel/duct ratio approached normal levels. In PBC, vessels were obliterated in areas of granulomatous inflammation and heavy lymphocytic infiltrate around bile ducts. In conclusion, loss of peribiliary vessels is common in PSC and PBC. Vessel loss is seen in early stages and may contribute an element of ischemia to continued small bile duct loss but is probably secondary to the inflammatory process.

Normal and abnormal development of the human intrahepatic biliary system: a review

Morphology and immunohistochemical features of the developmental process of the human intrahepatic biliary system (IBS) are reviewed. Human IBS arises from the ductal plate, a double-layered cylindrical structure located at the interface between portal mesenchyme and primitive hepatocytes. The ductal plate first appears from primitive hepatocytes (hepatoblasts) around 8 gestational weeks (GW), and its formation proceeds from the hepatic hilum to the periphery. The ductal plate gradually undergoes remodeling from 12 GW; some parts of the ductal plate disappear and other parts migrate into the portal mesenchyme. Around 20 GW, the migrated duct cells transform into immature bile ducts and peribiliary glands. Some immature peribiliary glands transform into pancreatic acinar cells around postnatal 3 months. The immature biliary elements express cytokeratins no. 7, 8, 18 and 19. Several growth factors (TGF-alpha, HGF) and their receptors (EGFR, MET, ERBB2) were expressed in the primitive IBS cells. Some extracellular matrix proteins including type IV collagen, laminin and tenascin are expressed in the mesenchyme around the primitive IBS. During IBS remodeling, apoptosis and cell proliferation occur with appropriate expression of apoptosis-related proteins (bcl-2, Fas, c-myc, Lewis(y)). Some pancreatic digestive enzymes (alpha-amylase, trypsinogen, lipase), cathepsin B, and matrix metalloproteinases (MMP-1, 2, 3, 9) and their inhibitors (TIMP-1, 2) are expressed in the remodeling IBS cells. Glycoconjugate residues of glycoproteins gradually appear during IBS development. The appropriate expression of these immunophenotypes may play an important role in the normal development of IBS.

Endocytosis in rat intrahepatic bile duct epithelial cells of horseradish peroxidase injected into the common bile duct or the portal vein

While recent data in intrahepatic bile duct epithelial cells (IBDECs) isolated from normal rat liver have established their ability to undergo endocytosis, few studies have assessed endocytosis in IBDECs in situ. Thus, to clarify the activity of IBDECs in situ on macro-molecules in bile and blood, we injected horseradish peroxidase (HRP) into either the common bile duct or the portal vein, and determined its intracellular distribution by electron microscopic cytochemistry. Successful retrograde injection into the common bile duct was achieved by resection of the liver surface so as to avoid HRP leakage from the bile duct on injection. IBDECs internalized HRP through both the apical and basolateral plasma membranes. By quantitative analysis, counting the number of HRP-positive vesicles in the cells, apical endocytosis was found more active than basolateral. HRP internalized through the apical membrane was either routed to the acid phosphatase-positive lysosomes for degradation or to extracellular space for transcytosis. HRP through the basolateral membrane was transferred to the organelles having lipid inclusion, which were expected to be lysosomes negative for acid phosphatase. Our results suggest that IBDECs in situ are actively engaged in endocytosis for degradation of macromolecules in bile and blood, and possibly engaged in the excretion of macromolecules into extracellular space.

Enhanced arsenite-induced hepatic morphological and biochemical changes in phenobarbital-pretreated rats

Changes in liver morphology and biochemistry have been assessed 16 hr after a sc injection of sodium arsenite [As(III), 75 mumol/kg] to control and phenobarbital (PB)-pretreated (80 mg/kg, ip daily for 3 days) adult male Wistar rats. As(III) administration to PB-pretreated rats [PB + As(III)] caused hydropic degeneration, total loss of glycogen, necrosis in some centrilobular zones, and an increase in lipid vacuoles around the periportal area. Electron microscopy showed an increased number of vacuoles and autophagosomes containing organelle-like material. There was a 30% decrease in total hepatic cytochrome P-450 (CYP450). O-dealkylation of ethoxy- and pentoxyresorufin and N-demethylation of benzphetamine decreased to 42, 32, and 30% of control values, respectively. 5-Aminolevulinic acid dehydrase decreased 25% from controls, and metal chelatase activities decreased to 25% of the PB-treated group. Injection of As(III) alone resulted in a mild increase in lipid-containing vacuoles around the periportal zone, a moderate loss of glycogen in midzonal areas, and, by electron microscopy, a dilatation of the bile canaliculi and an increase of the number of myelin-like structures. CYP450 content and the O-dealkylation of ethoxy- and pentoxyresorufin and N-demethylation of benzphetamine all decreased between 30 and 50%. These results demonstrate the greater susceptibility of the liver to injury following PB with compounds not requiring metabolic activation. The metabolic basis of these changes are unclear but may result from an increased demand for metabolic energy due to PB induction and decreased adenosine triphosphate synthesis caused by arsenic.

Cholangitis associated with paroxysmal nocturnal hemoglobinuria: another instance of ischemic cholangiopathy?

Ischemia is increasingly recognized as a cause of cholangiopathy. The aim of this study was to report a case of association of paroxysmal nocturnal hemoglobinuria with abrupt-onset cholangiopathy. Anomalies resembling sclerosing cholangitis were documented in a patient suffering from recurrent biliary pain. None of the conditions that have been associated with primary sclerosing cholangitis or other forms of cholangiopathy was present, but shortly thereafter, paroxysmal nocturnal hemoglobinuria occurred. Hepatic vein thrombosis later complicated the course of the disease. Because the fortuitous coincidence of these uncommon conditions is unlikely, this case indicates that paroxysmal nocturnal hemoglobinuria is a cause of ischemic cholangiopathy. Other thrombogenic conditions may also be implicated in some instances of apparently idiopathic cholangiopathy.

Alterations in bile ducts and peribiliary microcirculation in rats after common bile duct ligation

The chronological changes in ductular epithelium and peribiliary capillary plexuses (PBPs) after bile duct ligation are not well understood. Therefore, we examined alterations in both intrahepatic bile ductules and peribiliary microcirculation in rats after ligation of the common bile duct using immunohistochemistry, transmission electron microscopes (TEM), and scanning electron microscopes (SEM). Ductular proliferations appeared first in the peripheral areas of the portal spaces and then gradually advanced along with increasing jaundice. Distorted configuration of the hepatic parenchyma with interconnecting stroma rich in irregular ductules developed 4 weeks after the ligation. Numerous biliary cell types and cells of types intermediate between hepatocytes and biliary cells together with poorly fenestrated capillary-type vessels appeared in the periportal parenchyma, in association with an increased number of canalicular-ductular junctions on TEM. These biliary cells were often found within the lobules and apart from the stroma. SEM examination of hepatic microvascular casts using methacrylated resin showed formation of irregular portal and periportal capillary networks, partly derived from coarsened sinusoids. Direct connections between the newly formed capillary networks and the pre-existing PBPs or sinusoids were numerous, although there were few direct connections between the capillary networks and the hepatic arterial branches. Thus, these proliferated ductules and newly formed complicated capillary networks might play an important role in the effective transport of biliary materials between hepatocytes and native bile ducts or proliferated ductules through the altered microcirculation after bile duct ligation.

Small duct cholangitis induced by N-formyl L-methionine L-leucine L-tyrosine in rats

Primary sclerosing cholangitis (PSC) frequently accompanies inflammatory bowel diseases. In an attempt to increase our understanding of the pathogenesis of PSC, we studied bile duct changes in rats with colitis which had been given N-formyl L-methionine L-leucine L-tyrosine (fMLT) rectally; fMLT is one of the chemotactic peptides produced by Escherichia coli, and is secreted into the bile by hepatocytes after it enters the portal blood. Transrectal administration of fMLT induced a marked inflammation in the portal triad and mild hepatocyte necrosis on the 4th day. The infiltrating leukocytes in the portal tract were mostly mononuclear cells, which densely infiltrated around the bile ducts. These mononuclear cells appeared to attach to bile duct epithelial cells, and they were more numerous in the smaller bile ducts. Electron microscopy revealed that lymphocytes were in direct contact with bile duct lining cells and that some epithelial cells had degenerated or collapsed. These results suggest that this E. coli-derived peptide may induce cholangitis in the small bile duct through cell-mediated mechanisms. Since these pathologic changes resemble those of the bile duct observed in the early stage of PSC, it can be concluded that bacterial chemotactic peptides may play a role in the pathogenesis of small-duct PSC.

Intrahepatic peribiliary vascular plexus in various hepatobiliary diseases: a histological survey

The peribiliary vascular plexus (PVP) plays an important role in the pathophysiology of the biliary tree. We histologically examined vascular endothelial cells of the intrahepatic PVP in various hepatobiliary diseases by immunohistochemistry and lectin histochemistry with antibodies to factor VIII-related antigens (F-VIII-R-Ag) and Ulex europaeus agglutinin I (UEA-I). The PVP around the intrahepatic large bile ducts (LBDs) and septal bile ducts (SBDs) in normal livers consists of three layers: inner layer vessels immediately adjacent to the epithelium, intermediate layer vessels within the ductal wall, and outer layer vessels outside the ductal wall. In some bile ducts that show active inflammation in hepatolithiasis, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and extrahepatic biliary obstruction (EBO), vessels in the intermediate layer and, to a lesser degree, in the inner layer, are increased in number. In sclerotic bile ducts of PSC, EBO, and hepatolithiasis, the number of inner and intermediate layer vessels are markedly and variably reduced, respectively. In liver cirrhosis or chronic advanced liver diseases, the vessels in all three layers, particularly those in the outer layer, are increased in number and dilated, probably reflecting intrahepatic microcirculatory disturbance. The PVP showed several types of numerical and luminal changes, each of which may be related to disease processes in the intrahepatic biliary tree as well as to intrahepatic microcirculatory disturbance.

Portal cavernoma in congenital hepatic fibrosis. Angiographic reports of 10 pediatric cases

A retrospective pediatric study of 30 angiograms in congenital hepatic fibrosis (CHF) was undertaken to analyze the different aspects of the portal venous system in this disease. Besides the classical angiographic signs (hepatofugal veins and intrahepatic duplications), a hepatopetal venous network was present in ten children, contrasting with the patency of the portal venous system. Analysis of the medical charts for these ten patients showed that the clinical signs and outcome were similar to classical CHF. Liver biopsies were available in six cases and, in addition to the diagnostic features of CHF, demonstrated paucity or absence of portal venules. This unusual association of hepatopetal and hepatofugal collateral veins in an intrahepatic block could be explained by hypoplasia or thrombosis of portal venules. Thus, the association between hepatomegaly and hepatopetal collateral veins without portal obstruction should be suggestive of CHF.

Intrahepatic peribiliary glands of humans. I. Anatomy, development and presumed functions

The intrahepatic biliary tree is regarded as an excretory duct of two secretory units: hepatocytes and intrahepatic peribiliary glands. This review describes the anatomy, development and presumed functions of the latter. These glands are preferentially located around the intrahepatic large bile ducts, and are histologically divided into intramural and extramural structures. The former consist of simple tubular glands with much mucin, and are sparsely and irregularly distributed within the ductal wall. The latter are characterized by the presence of excretory units that consist of seromucinous acini and a conducting system in the periductal tissue. Pancreatic exocrine acini are occasionally admixed with extramural glands. These peribiliary glands appear in the late fetal period and complete their development about 15 years after birth. Extramural and intramural glands secrete neutral and acid mucin into the ductal lumen. Extramural glands contain several enzymes for digestion of protein and lipids. Neural and vascular supply of these glands may be related to the regulation of their secretion. Specific and non-specific immune responses within this glandular system may also be essential in the sterility of bile.

Intrahepatic peribiliary glands of humans. II. Pathological spectrum

The pathological spectrum of intrahepatic peribiliary glands is reviewed here. Several categories of histopathological changes such as necro-inflammation, cystic dilatation, hyperplasia and neoplasia have been identified in this glandular system. Necro-inflammation is associated with biliary tract diseases and chronic advanced liver diseases and may also appear in the livers of subjects with extrahepatic diseases such as sepsis. Cystic changes of microscopic sizes are not uncommon in autopsy livers of chronic advanced liver diseases, portal hypertensive diseases and also polycystic liver of adult type. Grossly recognizable cysts are, however, infrequent and occasionally cause compression of the adjoining bile ducts. Hyperplasia of these glands, which occurs consistently in hepatolithiasis and more variably in other conditions (e.g. biliary tract infection and submassive hepatic necrosis), may be associated with hypersecretion of seromucinous substances. Hyperplasia of peribiliary glands may then lead to mucin-related biliary diseases. In addition, these glands, particularly the hyperplastic ones, could be a precursor of cholangiocarcinoma. The pathological spectrum of the intrahepatic peribiliary glands is being expanded, although a clinical pathological correlation remains uncharted. Furthermore, age-related variations and non-specific reactive changes of these glands remain unexplored.

Histopathology of portal tracts in livers after transcatheter arterial chemo-embolization therapy for hepatocellular carcinoma

To study the influence of transcatheter arterial embolization therapy (TAE) on the portal tracts, 32 cases of hepatocellular carcinoma (HCC) with a history of TAE were examined. Portal tract elements are said to be mainly supplied by hepatic arterial blood, as is HCC. The following changes were found: peribile duct fibrosis; biliary epithelial injuries; bile duct necrosis; fibrous thickening of the intima and adventitia of arteries; thrombosis or stenosis of portal vein branches; and fibrosis of portal tract itself. We failed to correlate these histopathologic changes with the frequency of TAE or the interval between TAE therapy and surgery or autopsy. Semi-quantitative assessment disclosed that vessels of the peribiliary vascular plexus (PVP) which are known to be derived from hepatic arterial branches, were considerably decreased. There was little correlation between the degree of reduction of PVP and the observed histopathologic changes of portal tracts. It is suggested that TAE causes adverse effects on the elements of portal tracts and a reduction in the PVP in the vicinity of HCC, but the relationship between them is unclear.

Oxidative stress produced by suprahepatic occlusion and reperfusion

In this article the spontaneous chemiluminescence and the steady-state concentration of hydrogen peroxide were determined in rat liver as indicators of oxidative stress in the tissue. Hydroperoxide-initiated chemiluminescence and the activity of antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) were also measured to evaluate antioxidant defenses and serum activity of lactate dehydrogenase and aspartate aminotransferase. Mitochondrial morphology and mitochondrial respiratory control ratio were measured as indicators of cell and mitochondrial damage. Xanthine dehydrogenase and xanthine oxidase activities were determined as a possible source of oxyradicals. No significant changes were observed after 10 or 30 min of vena cava occlusion in any of the measured parameters. In contrast, 10 min of occlusion followed by 10 min of reperfusion increased chemiluminescence (from 18 +/- 3 to 32 +/- 5 cps/cm2), hydrogen peroxide (from 0.10 +/- 0.01 to 0.17 +/- 0.01 mumol/L), lactate dehydrogenase (from 80 +/- 2 to 330 +/- 30 U/L), and aspartate aminotransferase (from 42 +/- 2 to 100 +/- 10 U/L). Liver reperfusion was also associated with mitochondrial swelling and decreased mitochondrial respiratory control (from 5.6 +/- 0.3 to 2.6 +/- 0.1). The activity of the antioxidant enzymes and xanthine oxidase was instead without change. After 30 min of vena cava occlusion and 10 min of reperfusion a more marked increase in chemiluminescence (37 +/- 5 cps/cm2), hydrogen peroxide (0.30 +/- 0.01 mumol/L), lactate dehydrogenase (730 +/- 10 U/L) and aspartate aminotransferase (140 +/- 10 U/L) was observed. No further changes were found in either mitochondrial morphology or respiratory control (2.4 +/- 0.1) in isolated mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)