Interlobular Ducts Research Articles

S1871 The Association of Low Level of Both Vitamin a and Retinol Binding Protein With the Liver Complications in Patients With Primary Sclerosing Cholangitis

Background/Aims: There has been increased interest in the potential role of B cells and antimitochondrial antibodies in PBC. Indeed a new paradigm in PBC includes the potential of B cells to act as both regulatory elements and as components of the inflammasone induced by apoptosis of biliary cells. We submit that a rigorous dissection of the inflammatory infiltrate in PBC will provide further insight on these issues. Materials and Methods: We took advantage of well-characterized Mabs to CD3, CD4, CD8, CD20, CD38, CD56, CD68, and pan-keratin antigens, and immunohistochemistry (IHC), to study the distribution of liver infiltrating CD38-positive plasma cells in 26 consecutive patients with PBC (AMA positive in 20 and negative in 6), all of whom had detailed staged clinical data. All data was “blindly” evaluated. We simultaneously studied 10 ageand gender-matched patients with chronic hepatitis C as a control. Results: Noteworthy within the IHC data was the presence of an intense coronal arrangement (CR) of CD38-positive cells around interlobular bile ducts, generally in specimens with chronic non-suppurative destractive cholangitis (CNSDC). In contrast, CD20-positive B lymphocytes (precursor cells of plasma cells) were found scattered and/or aggregated within the lymphoplasmocytic infiltration. Such CD20positive B cells also occasionally formed follicle-like aggregations but importantly were not observed in the proximity of CNSDC. PBC patients with CR demonstrated significantly higher titers of AMA (119.5±16.1 vs. 59.7±17.1, p=0.018) and lower levels of total cholesterol (TC) (195.1±9.0 vs. 223.6±9.6, p=0.04) than those without CR. Interestingly the CR correlated with titer of AMA (r=0.46), IgM (r=0.32), the presence of CNSDC (r=0.32) and inversely with age (r=-0.37), γ-GTP (r=-0.38) and TC (r=-0.41). In contrast, CD4and CD8-positive T lymphocyte infiltration was noted either in proximity of, or within the degenerated cholangioepithelium, suggesting the participation of these cells in the destructive processes of interlobular bile ducts. No CR was found in control subjects. Conclusion: The presence of CD38+ plasma cells surrounding biliary epithelium has clinical and serologic significance; further it correlates with disease progression exemplified by TC decrease and the development of florid duct lesions. These data further highlight the functional significance of B cells/ plasma cells; it also reflects a multilineage loss of tolerance in PBC. We submit that study of B cells in PBC should go beyond simple measurement of AMA titer and include rigorous phenotypical and functional dissection of the liver specific B cell lineage populations.

S1874 Drug-Induced Autoimmune Hepatitis: Clinical Characteristics and Prognosis

Background/Aims: There has been increased interest in the potential role of B cells and antimitochondrial antibodies in PBC. Indeed a new paradigm in PBC includes the potential of B cells to act as both regulatory elements and as components of the inflammasone induced by apoptosis of biliary cells. We submit that a rigorous dissection of the inflammatory infiltrate in PBC will provide further insight on these issues. Materials and Methods: We took advantage of well-characterized Mabs to CD3, CD4, CD8, CD20, CD38, CD56, CD68, and pan-keratin antigens, and immunohistochemistry (IHC), to study the distribution of liver infiltrating CD38-positive plasma cells in 26 consecutive patients with PBC (AMA positive in 20 and negative in 6), all of whom had detailed staged clinical data. All data was “blindly” evaluated. We simultaneously studied 10 ageand gender-matched patients with chronic hepatitis C as a control. Results: Noteworthy within the IHC data was the presence of an intense coronal arrangement (CR) of CD38-positive cells around interlobular bile ducts, generally in specimens with chronic non-suppurative destractive cholangitis (CNSDC). In contrast, CD20-positive B lymphocytes (precursor cells of plasma cells) were found scattered and/or aggregated within the lymphoplasmocytic infiltration. Such CD20positive B cells also occasionally formed follicle-like aggregations but importantly were not observed in the proximity of CNSDC. PBC patients with CR demonstrated significantly higher titers of AMA (119.5±16.1 vs. 59.7±17.1, p=0.018) and lower levels of total cholesterol (TC) (195.1±9.0 vs. 223.6±9.6, p=0.04) than those without CR. Interestingly the CR correlated with titer of AMA (r=0.46), IgM (r=0.32), the presence of CNSDC (r=0.32) and inversely with age (r=-0.37), γ-GTP (r=-0.38) and TC (r=-0.41). In contrast, CD4and CD8-positive T lymphocyte infiltration was noted either in proximity of, or within the degenerated cholangioepithelium, suggesting the participation of these cells in the destructive processes of interlobular bile ducts. No CR was found in control subjects. Conclusion: The presence of CD38+ plasma cells surrounding biliary epithelium has clinical and serologic significance; further it correlates with disease progression exemplified by TC decrease and the development of florid duct lesions. These data further highlight the functional significance of B cells/ plasma cells; it also reflects a multilineage loss of tolerance in PBC. We submit that study of B cells in PBC should go beyond simple measurement of AMA titer and include rigorous phenotypical and functional dissection of the liver specific B cell lineage populations.

Cellular Senescence in Livers from Children with End Stage Liver Disease

BackgroundSenescent cells occur in adults with cirrhotic livers independent of the etiology. Aim: Investigate the presence rate of cellular senescence and expression of cell cycle check points in livers from children with end stage disease.Methodology/Principal FindingsLivers of five children aged three years or less undergoing liver transplantation due to tyrosinemia (n = 1), biliary atresia (n = 2), or fulminant hepatitis (n = 2) were analyzed for senescence associated β-galactosidase (SA-βgal) activity and p16INK4a, p21cip1 and p53. All livers displayed positive cellular staining for SA-βgal in the canals of Hering and interlobular biliary ducts. In the presence of cirrhosis (3/5 cases) SA-βgal was found at the cholangioles and hepatocytes surrounding the regenerative nodules. Children with fulminant hepatic failure without cirrhosis had significant ductular transformation with intense SA-βgal activity. No SA-βgal activity was evident in the fibrous septa. Staining for p53 had a similar distribution to that observed for SA-βgal. Staining for p16INK4a and p21cip1 was positive in the explanted liver of the patient with tyrosinemia, in the hepatocytes, the canals of Hering, cholangioles and interlobular bile ducts. In the livers with fulminant hepatitis, p21cip1 staining occurred in the areas of ductular transformation and in the interlobular bile ducts.Conclusions/SignificanceCellular senescence in livers of children with end stage disease is associated with damage rather than corresponding to an age dependent phenomenon. Further studies are needed to support the hypothesis that these senescence markers correlate with disease progression.

BILE DUCT SYSTEM MALFORMATION - EMBRYOLOGICAL AND PATHOLOGICAL ASSOCIATION. TREATMENT /REVIEW ARTICLE/

Cystic diseases of the liver which are in most cases hereditary, are related to an embryonic disorder know as ductal plate malformation. These diseases correspond to partial or total arrest of remodeling of the ductal plate, leading to more or less complete persistence of the excess of embryonic biliary structures. The ductal plate malformation may concern different segments of the intrahepatic biliary tree (segmental bile ducts, interlobular bile ducts and the smallest bile duct ramifications) leading to various pathoclinical entities Congenital cystic lesions of bile ducts may affect intra or extrahepatic bile ducts. Intrahepatic lesions include five entities: congenital hepatic fibrosis, Caroli’s syndrome, von Meyenburg complexes, simple cyst of the liver and polycystic liver disease. Congenital hepatic fibrosis and von Meyenburg complexes are secondary to ductal plate malformation affecting the smallest intrahepatic bile ducts. Choledocal cysts, Caroli’s disease and Caroli’s syndrome belong to the some family of congenital malformations of the large bile ducts (1). The former affects the extrahepatic bile duct (including occasionally the left and right branch of the hepatic duct) while the latter affects segmental intrahepatic bile ducts. Both are extremely rare (in the order of 1:10.000 or 100.000 and 1:1.000.000 births respectively.

Erythropoietic Protoporphyria

A 34-year-old woman with a history of photosensitivity reaction was admitted to our hospital for epigastralgia and jaundice, which had persisted for 1 month. She had no history of alcohol consumption, and had regularly been taking ferric oxide for the treatment of anemia. Physical examination revealed that the skin and conjunctiva were icteric; abdominal tenderness and palpable liver and spleen were noted. Blood examination revealed anemia (hemoglobin 9.2 g/dL), and liver dysfunction (international normalized ratio, 1.54; total bilirubin, 4.4 mg/dL; alanine aminotransferase, 90 IU/L; y-glutamyltransferase, 159 IU/L). The results of serologic examination for hepatitis B and C virus were negative. An abdominal computed tomography scan showed hepatosplenomegaly. For further investigation, needle biopsy of the liver was performed.On hematoxylin-eosin staining (Figure A), the liver specimen showed slightly distorted lobular architecture. It contained deposits of dark reddish-brown pigment localized in the cytoplasm of the hepatocytes and Kupffer cells in the lumen of the dilated canaliculi and/or interlobular ducts. All the deposits exhibited striking birefringence on polarization microscopic examination (Figure B). Characteristically, some globular deposits appeared bright red and had a centrally-located Maltese cross (arrow). Further, a significant increase was noted in the protoporphyrin levels in the patient's red blood cell count (8578 μg/dL). These findings led to the diagnosis of erythropoietic protoporphyria (EPP).EPP is an inborn error of haem biosynthesis caused by mutations in the gene encoding the mitochondrial enzyme ferrochelatase, which is the final enzyme in the haem biosynthetic pathway. Defects in ferrochelatase lead to an excess of protoporphyrin in the plasma, which in turn induces photosensitivity. Liver damage occurs due to cholestasis caused by excess protoporphyrin and/or exposure to protoporphyrin itself. Protoporphyrin-induced hepatotoxicity is a rare condition occurring in 1%–5% of EPP patients1Anstey A.V. Hift R.J. Liver disease in erythropoietic protoporphyria: insights and implications for management.Gut. 2007; 56: 1009-1018PubMed Google Scholar; however, in patients with deteriorating liver disease, EPP may be irreversible, and such patients require liver transplantation.2McGuire B.M. Bonkovsky H.L. Carithers R.L. et al.Liver transplantation for erythropoietic protoporphyria liver disease.Liver Transpl. 2005; 11: 1590-1596Crossref PubMed Scopus (111) Google Scholar A 34-year-old woman with a history of photosensitivity reaction was admitted to our hospital for epigastralgia and jaundice, which had persisted for 1 month. She had no history of alcohol consumption, and had regularly been taking ferric oxide for the treatment of anemia. Physical examination revealed that the skin and conjunctiva were icteric; abdominal tenderness and palpable liver and spleen were noted. Blood examination revealed anemia (hemoglobin 9.2 g/dL), and liver dysfunction (international normalized ratio, 1.54; total bilirubin, 4.4 mg/dL; alanine aminotransferase, 90 IU/L; y-glutamyltransferase, 159 IU/L). The results of serologic examination for hepatitis B and C virus were negative. An abdominal computed tomography scan showed hepatosplenomegaly. For further investigation, needle biopsy of the liver was performed. On hematoxylin-eosin staining (Figure A), the liver specimen showed slightly distorted lobular architecture. It contained deposits of dark reddish-brown pigment localized in the cytoplasm of the hepatocytes and Kupffer cells in the lumen of the dilated canaliculi and/or interlobular ducts. All the deposits exhibited striking birefringence on polarization microscopic examination (Figure B). Characteristically, some globular deposits appeared bright red and had a centrally-located Maltese cross (arrow). Further, a significant increase was noted in the protoporphyrin levels in the patient's red blood cell count (8578 μg/dL). These findings led to the diagnosis of erythropoietic protoporphyria (EPP). EPP is an inborn error of haem biosynthesis caused by mutations in the gene encoding the mitochondrial enzyme ferrochelatase, which is the final enzyme in the haem biosynthetic pathway. Defects in ferrochelatase lead to an excess of protoporphyrin in the plasma, which in turn induces photosensitivity. Liver damage occurs due to cholestasis caused by excess protoporphyrin and/or exposure to protoporphyrin itself. Protoporphyrin-induced hepatotoxicity is a rare condition occurring in 1%–5% of EPP patients1Anstey A.V. Hift R.J. Liver disease in erythropoietic protoporphyria: insights and implications for management.Gut. 2007; 56: 1009-1018PubMed Google Scholar; however, in patients with deteriorating liver disease, EPP may be irreversible, and such patients require liver transplantation.2McGuire B.M. Bonkovsky H.L. Carithers R.L. et al.Liver transplantation for erythropoietic protoporphyria liver disease.Liver Transpl. 2005; 11: 1590-1596Crossref PubMed Scopus (111) Google Scholar

Atorvastatin-Induced Prolonged Cholestasis with Bile Duct Damage

We report a case of acute-onset, long-lasting cholestasis induced by atorvastatin. This antihyperlipidaemic drug was taken for 40 days by a 72-year-old male as a treatment for his mixed dyslipidaemia. At that point, the patient presented with asthenia, nausea, painless icterus, acholic stools and hyperchromic urine with biochemical analyses showing a dramatic increase in bilirubin (total bilirubin 22 mg/dL; direct bilirubin 21 mg/dL) and alkaline phosphatase (up to 4-fold over the normal level) with less marked increases in transaminases. Liver histology showed a pattern of cholestasis with evident signs of cholangiolitis and damage of the interlobular bile ducts. Serum transaminase and bilirubin levels returned to normal within 5 months after atorvastatin withdrawal while alkaline phosphatase normalized after only 8 months. Scores on both the Maria and Victorino clinical scale for the diagnosis of drug-induced hepatitis and the Naranjo Adverse Drug Reaction Probability Scale indicated that atorvastatin was the probable cause of prolonged cholestasis in this patient. This is a rare case of cholestasis probably caused by atorvastatin and unusually characterized by bile duct damage.

Management of Large Hepatocellular Carcinoma in Adult Patients with Alagille Syndrome: A Case Report and Review of Literature

Alagille syndrome is a multi-system developmental disorder associated with paucity of interlobular bile ducts and cholestasis, rarely associated with hepatocellular carcinoma. Associated syndromic co-morbidities may complicate surgical management. As such, we herein review the modern management of a large hepatocellular carcinoma in an adult patient with Alagille syndrome and review the literature of adult Alagille patients with hepatocellular carcinoma. A 29-year-old woman with a history of Alagille syndrome was referred with biopsy-proven 12×8cm hepatocellular carcinoma replacing her right liver. Biopsy of the contralateral liver demonstrated findings consistent with Alagille syndrome, but no underlying cirrhosis. CT volumetrics demonstrated a future liver remnant of 40%. Extensive hematologic and cardiac work-up was performed pre-operatively, given the syndrome's associated bleeding dyscrasias and cardiac abnormalities. The patient underwent a margin-negative right hepatectomy using the "hanging" technique through a thoracoabdominal approach. The patient developed a transient hyperbilirubinemia but no hepatic insufficiency and did well post-operatively. Since Alagille syndrome affects multiple organ systems, preoperative evaluation of cardiac, hematologic, and hepatic function should be considered. This case illustrates the peri-operative management of an Alagille patient, and highlights several key technical points that contributed to a successful resection.

Glomerular basement membrane lipidosis in Alagille syndrome

Alagille syndrome is characterized by a paucity of interlobular bile ducts with chronic cholestasis, cardiac, skeletal, and eye abnormalities and is associated predominantly with JAG1 mutations. Various renal abnormalities have been sporadically described. The classic renal histopathology described in Alagille syndrome is mesangiolipidosis, with lipid deposits predominately confined to the mesangium and minimal deposition within the glomerular basement membrane (GBM). We report a 5-year-old girl with Alagille syndrome who presented with persistent subnephrotic proteinuria and renal tubular acidosis. A renal biopsy showed GBM irregularities (mimicking membranous glomerulonephritis), mesangial sclerosis, and focal segmental glomerulosclerosis (FSGS) on light microscopy. Electron microscopy revealed few lipid inclusions within the mesangium but extensive inclusions along the GBM. These findings are mostly consistent with those reported previously in Alagille syndrome. However, the histologic distribution of lipid vacuoles is seemingly reversed in this patient and is uniquely accompanied by FSGS, emphasizing the spectrum of renal histopathology seen in Alagille syndrome. The proteinuria observed in this patient is likely attributed to significant GBM lipid deposition, which over time may contribute to the development of FSGS.

Congenital Hepatic Fibrosis in 5 Dogs

Congenital hepatic fibrosis is a disorder of biliary system development histologically characterized by diffuse periportal to bridging fibrosis with numerous small often-irregular bile ducts and reduction in the number of portal vein branches. The condition results from abnormal development of the ductal plate, the embryonic precursor to the interlobular bile ducts. It has rarely been reported in veterinary species, and it has never been reported in dogs. This article describes 5 cases of a ductal plate malformation in dogs consistent with congenital hepatic fibrosis. On light microscopy, all 5 livers had severe bridging fibrosis with a marked increase in the number of small bile ducts, which often had irregular, dilated profiles reminiscent of the developing ductal plate. In addition, 80% (4 of 5) of cases lacked typical portal vein profiles. Cytokeratin 7 and proliferating cell nuclear antigen immunohistochemistry was performed on the 3 cases for which paraffin-embedded tissue was available. The bile duct profiles were strongly positive for cytokeratin 7 in all 3 cases, and they were negative for proliferating cell nuclear antigen or only had rare positive cells. All 5 dogs presented with clinical signs of portal hypertension. Congenital hepatic fibrosis should be considered in the differential diagnosis in young dogs that present with portal hypertension and lesions that may have been interpreted as bridging biliary hyperplasia or extrahepatic biliary obstruction.

An unusual cause of hypertension and renal failure: a case series of a family with Alagille syndrome

Alagille Syndrome (OMIM 118450) is a multisystem developmental disorder inherited in an autosomal dominant pattern with variable expression. It commonly manifests in children with early cholestatic jaundice due to paucity of interlobular biliary ducts. Renal involvement is less common but can take various forms including renovascular disease, renal agenesis or hypoplasia, cystic renal disease, mesangiolipidosis, tubulointerstitial nephritis and renal tubular acidosis. We describe a family of Alagille syndrome with JAG 1 mutation running through at least two generations, affecting four members with variable phenotypic expressions and disease severity. Alagille syndrome should be considered in the differential diagnosis of adults with renovascular disease and children with agenesis/dysgenesis of kidney and reflux nephropathy even in the absence of hepatic disease. Renal transplant can be successful in these patients although living related donation may not be appropriate given the high penetrance and variable expression of this condition. This syndrome may cause symptomatic bradyarrhythmias as described in our series.

Immunocytochemical Localization of Sex Steroid Hormone Receptors in Normal Human Mammary Gland

The sex steroids, estrogens, progesterone, and androgens, all play a role in mammary development and function. To precisely identify the sites of action of these steroids, we studied the localization of the estrogen receptor alpha (ERalpha) and ERbeta, the progesterone receptor A (PRA) and PRB, and androgen receptors (AR) in the normal human mammary gland. Immunocytochemical localization of ERalpha, ERbeta, PRA, PRB, and AR was performed with reduction mammoplasty specimens from premenopausal women. ERalpha, PRA, PRB, and AR were localized mostly to the inner layer of epithelial cells lining acini and intralobular ducts, as well as to myoepithelial cells scattered in the external layer of interlobular ducts. AR was also found in some stromal cells. ERbeta staining was more widespread, resulting in epithelial and myoepithelial cells being labeled in acini and ducts as well as stromal cells. These results suggest that all sex steroids can directly act on epithelial cells to modulate development and function of the human mammary gland. Estrogens and androgens can also indirectly influence epithelial cell activity by an action on stromal cells.

Architectural and Immunohistochemical Characterization of Biliary Ductules in Normal Human Liver

The canals of Hering or biliary ductules have been described to connect the bile canaliculi with the interlobular bile ducts, and thus forming the distal part of the biliary tree. Studies in the last two decades suggested that the cells constructing these ductules could behave as hepatic progenitor cells. The canals of Hering are confined to the periportal space in the rat, while they have been reported to spread beyond the limiting plate in human liver. The distribution of the distal biliary ductules in normal human hepatic tissue has been investigated in our recent experiments. We could demonstrate the presence of interlobular connective tissue septa in a rudimentary form in healthy livers. The canals of Hering run in these septa in line with the terminal branches of the portal vein and hepatic arteries. This arrangement develops in the postnatal period but regresses after early childhood. The canals of Hering can be identified by the unique epithelial membrane antigen (EMA)-/CD56+/CD133+ immunophenotype. The canals of Hering leave the periportal space and spread into the liver parenchyma along rudimentary interlobular septa outlining the hepatic lobules. Our observations refine the original architectural description of the intraparenchymal portion of the canals of Hering in the human liver. The distinct immunophenotype supports their unique biological function.

Expression of contactin associated protein-like 2 in a subset of hepatic progenitor cell compartment identified by gene expression profiling in hepatitis B virus-positive cirrhosis

Hepatic progenitor cells (HPC), a cell compartment capable of differentiating into hepatocytic and biliary lineages, may give rise to the formation of intermediate hepatobiliary cells (IHBC) or ductular reactions (DR). The aim of this study was to analyse the gene expression profiles of DR in cirrhosis and further investigate novel proteins expressed by HPC and their intermediate progeny. DR in hepatitis B virus (HBV)-positive cirrhotic liver tissues adjacent to hepatocellular carcinoma and interlobular bile ducts (ILBDs) in normal liver tissues were isolated by laser capture microdissection and then subjected to microarray analysis. Differential gene expression patterns were verified by quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry on serial sections. HPC and their intermediate progeny were recognized by immunostaining with hepatocytic and biliary markers [HepPar1, cytokeratin (CK)7, CK19, neural cell adhesion molecule (NCAM), epithelial cell adhesion molecule (EpCAM)]. A total of 88 genes showed upregulation in DR compared with ILBDs. Gene ontology analyses revealed that these upregulated genes were mostly associated with cell adhesion, immune response and the metabolic process. Contactin associated protein-like 2 (CNTNAP2) was first confirmed to be a novel protein expressed in a subpopulation of DR that was positive for CK7, NCAM or EpCAM. In addition, immunoreactivity for CNTNAP2 was also noted in a subset of isolated CK7-positive HPC as well as some ductular IHBC positive for CK19 and HepPar1 in DR. CNTNAP2 is specifically associated with the emergence of ductular populations and may be identified as a novel protein for defining a subset of HPC and their intermediate progeny in cirrhosis.

High glucose inhibits HCO 3 − and fluid secretion in rat pancreatic ducts

Cellular mechanisms underlying the impairment of pancreatic fluid and electrolyte secretion in diabetes were examined using interlobular ducts isolated from rat pancreas. Fluid secretion was assessed by monitoring changes in luminal volume. HCO3(-) uptake across the basolateral membrane was estimated from the recovery of intracellular pH following an acid load. Exposure to high glucose concentrations inhibited fluid secretion and reduced the rate of basolateral HCO3(-) uptake in secretin-stimulated ducts isolated from normal rats. In ducts isolated from streptozotocin-treated diabetic rats, fluid secretion and basolateral HCO3(-) uptake were also severely impaired but could be largely reversed by incubation in normal-glucose solutions. Sodium-dependent glucose cotransporter 1 (SGLT1), glucose transporter (GLUT)1, GLUT2, and GLUT8 transcripts were detected by reverse transcriptase polymerase chain reaction in isolated ducts. Raising the luminal glucose concentration in microperfused ducts caused a depolarization of the membrane potential, consistent with the presence of SGLT1 at the apical membrane. Unstimulated ducts filled with high-glucose solutions lost luminal fluid by a phlorizin-sensitive mechanism, indicating that pancreatic ducts are capable of active glucose reabsorption from the lumen via SGLT1. In ducts exposed to high glucose concentrations, continuous glucose diffusion to the lumen and active reabsorption via SGLT1 would lead to elevation of intracellular Na+ concentration and sustained depolarization of the apical membrane. These two factors would tend to inhibit the basolateral uptake and apical efflux of Cl(-) and HCO3(-) and could therefore account for the impaired fluid and electrolyte secretion that is observed in diabetes.

Concurrent Course of Transient Neonatal Diabetes with Cholestasis and Paucity of Interlobular Bile Ducts: A Case Report

We report for the first time a patient with both transient neonatal diabetes mellitus (TNDM) and idiopathic neonatal cholestasis, with both features resolving over a similar time course. Cholestasis was due to paucity of interlobular bile ducts (PILBD). Genetic analysis was consistent with a uniparental disomy of chromosome 6. Paucity of interlobular bile ducts is common in Alagille syndrome but also occurs by unknown mechanisms in a wide spectrum of other diseases. We propose a shared explanation for this patient's TNDM and PILBD mediated by the noted chromosomal abnormality. We suggest that hepatobiliary function be evaluated in patients with TNDM to determine the prevalence and course of cholestasis of the disease.

Ducts isolated from the pancreas of CFTR-null mice secrete fluid

The pancreatic pathology in cystic fibrosis (CF) is normally attributed to the failure of ductal fluid secretion resulting from the lack of functional CF transmembrane conductance regulator (CFTR). However, murine models of CF show little or no pancreatic pathology. To resolve this dichotomy we analysed the transport mechanisms involved in fluid and electrolyte secretion by pancreatic ducts isolated from CFTR-null mice. Experiments were performed on cultured interlobular duct segments isolated from the pancreas of the Cftr(tm1Cam) strain of CFTR-null mouse. Fluid secretion to the closed luminal space was measured by video microscopy. The secretory response of ducts isolated from CF mice to cAMP-elevating agonists forskolin and secretin was significantly reduced compared with wild type but not abolished. The Cl(-)- and HCO(3) (-) -dependent components of the ductal secretion were affected equally by the absence of CFTR. The secretory response to carbachol stimulation was unaltered in CF ducts. Loading the ductal cells with the Ca2+ chelator BAPTA completely abolished carbachol-evoked secretion, but did not affect forskolin-evoked secretion in CF or wild-type ducts. We conclude that pancreatic duct cells from CF mice can secrete a significant amount of water and electrolytes by a cAMP-stimulated mechanism that is independent of CFTR and cannot be ascribed to the activation of calcium-activated chloride channels.

HCO3 − Transport in Interlobular Pancreatic Ducts Isolated From ΔF Mice and SLC26A6 Null Mice

膵導管細胞からのHCO3-の分泌は，cystic fibrosis transmembrane conductance regulator（CFTR）に依存する．導管細胞の管腔膜には，CFTR陰イオンチャネルの他に，Na+-H+ exchangerとSLC26陰イオン交換輸送体が存在する．ΔF508変異CFTRを導入したΔFマウスの単離小葉間膵管では，cAMP刺激による膵液分泌が消失し，管腔膜のNa+-H+ exchange活性が増強していた．膵嚢胞線維症では，管腔膜のNa+-H+ exchangerが膵液を酸性化している可能性がある．slc26a6ノックアウトマウスの単離膵管では，管腔内Cl-⇔細胞内HCO3-の交換活性が低下していたが，in vivoの膵液量とpHは影響されなかった．より高濃度のHCO3-を分泌するモルモットの単離膵管を用いてSLC26輸送体の役割を検討する必要がある．

Suppression of Lymphocyte Proliferation and Regulation of Dendritic Cell Phenotype by Soluble Mediators from Rat Lacrimal Epithelial Cells

Lacrimal epithelial cells appear to constitutively secrete autoantigens to their underling stroma. The present experiments address the hypothesis that they also secrete soluble factors that regulate immune responses. Epithelial cells, spleen cells and lymphocytes were obtained from rabbits or rats and cultured in various configurations. Monocytes from rat bone marrow were matured to dendritic cells (DC) ex vivo. Proliferation was measured by [3H]-thymidine incorporation; surface MHC Class II and CD86 using flow cytometry; and mRNA relative abundances using real time RT-PCR. Microporous culture inserts containing rat lacrimal cells inhibited proliferation of rabbit lymphocytes co-cultured with autologous lacrimal cells and of rat lymphocytes co-cultured with TNF-alpha-stimulated DC. They inhibited CD86 and MHC Class II surface expression by maturating DC and reversed surface expression of CD86 but not MHC Class II by partially matured DC. Subsequent exposure of partially matured DC to mediators from rat lacrimal cells reversed the ability to stimulate lymphocyte proliferation. TGF-beta(1) and IL-10 mRNAs increased somewhat when rat lacrimal cells were isolated but decreased markedly in rabbit lacrimal cells. Antibodies to TGF-beta prevented soluble factors from rat lacrimal cells from inhibiting proliferation of rabbit lymphocytes co-cultured with rabbit lacrimal cells, but recombinant TGF-beta alone did not mimic the soluble factors. IL-10 immunopositivity was detected in epithelial cells of interlobular ducts and occasional interstitial cells in rabbit lacrimal gland. Rat lacrimal epithelial cells secrete TGF-beta and other factors that synergize to suppress lymphocyte proliferation and regulate DC maturation. Interlobular duct epithelial cells in rabbit lacrimal glands may express similar functions.

Functional coupling of apical Cl−/HCO3− exchange with CFTR in stimulated HCO3− secretion by guinea pig interlobular pancreatic duct

Pancreatic ductal epithelium produces a HCO(3)(-)-rich fluid. HCO(3)(-) transport across ductal apical membranes has been proposed to be mediated by both SLC26-mediated Cl(-)/HCO(3)(-) exchange and CFTR-mediated HCO(3)(-) conductance, with proportional contributions determined in part by axial changes in gene expression and luminal anion composition. In this study we investigated the characteristics of apical Cl(-)/HCO(3)(-) exchange and its functional interaction with Cftr activity in isolated interlobular ducts of guinea pig pancreas. BCECF-loaded epithelial cells of luminally microperfused ducts were alkalinized by acetate prepulse or by luminal Cl(-) removal in the presence of HCO(3)(-)-CO(2). Intracellular pH recovery upon luminal Cl(-) restoration (nominal Cl(-)/HCO(3)(-) exchange) in cAMP-stimulated ducts was largely inhibited by luminal dihydro-DIDS (H(2)DIDS), accelerated by luminal CFTR inhibitor inh-172 (CFTRinh-172), and was insensitive to elevated bath K(+) concentration. Luminal introduction of CFTRinh-172 into sealed duct lumens containing BCECF-dextran in HCO(3)(-)-free, Cl(-)-rich solution enhanced cAMP-stimulated HCO(3)(-) secretion, as calculated from changes in luminal pH and volume. Luminal Cl(-) removal produced, after a transient small depolarization, sustained cell hyperpolarization of approximately 15 mV consistent with electrogenic Cl(-)/HCO(3)(-) exchange. The hyperpolarization was inhibited by H(2)DIDS and potentiated by CFTRinh-172. Interlobular ducts expressed mRNAs encoding CFTR, Slc26a6, and Slc26a3, as detected by RT-PCR. Thus Cl(-)-dependent apical HCO(3)(-) secretion in pancreatic duct is mediated predominantly by an Slc26a6-like Cl(-)/HCO(3)(-) exchanger and is accelerated by inhibition of CFTR. This study demonstrates functional coupling between Cftr and Slc26a6-like Cl(-)/HCO(3)(-) exchange activity in apical membrane of guinea pig pancreatic interlobular duct.

A Methodological Approach to Tracing Cell Lineage in Human Epithelial Tissues

Methods for lineage tracing of stem cell progeny in human tissues are currently not available. We describe a technique for detecting the expansion of a single cell's progeny that contain clonal mitochondrial DNA (mtDNA) mutations affecting the expression of mtDNA-encoded cytochrome c oxidase (COX). Because such mutations take up to 40 years to become phenotypically apparent, we believe these clonal patches originate in stem cells. Dual-color enzyme histochemistry was used to identify COX-deficient cells, and mutations were confirmed by microdissection of single cells with polymerase chain reaction sequencing of the entire mtDNA genome. These techniques have been applied to human intestine, liver, pancreas, and skin. Our results suggest that the stem cell niche is located at the base of colonic crypts and above the Paneth cell region in the small intestine, in accord with dynamic cell kinetic studies in animals. In the pancreas, exocrine tissue progenitors appeared to be located in or close to interlobular ducts, and, in the liver, we propose that stem cells are located in the periportal region. In the skin, the origin of a basal cell carcinoma appeared to be from the outer root sheath of the hair follicle. We propose that this is a general method for detecting clonal cell populations from which the location of the niche can be inferred, also affording the generation of cell fate maps, all in human tissues. In addition, the technique allows analysis of the origin of human tumors from specific tissue sites.