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Purpose and Context: Proximal levels of excised remnants from youngest infants may reveal early features of biliary atresia (BA).Method: A targeted IHC survey was applied to 34 most proximal 2 levels in 17 BA remnants excised at age 10–74 days including 7 = <30 days old and 6 control hepatic ducts (HD).Key Results: Severity of inflammation and extent of active fibroplasia do not distinguish proximal remnants in younger (n = 7) and older (n = 10) infants. In 27/34 levels of 14/17 remnants, reactive stroma is focally SM-MHC-2 (+), marking smooth muscle myosin, termed reactive myogenesis (RM), that is absent in controls. RM facilitates identification of 3 novel hepatic duct remnants (HDR): an HD-like collagen collar lined by degenerating cholangiocytes (n = 5); erosion defects in loose reactive stroma (n = 14); solitary foci of hyperplastic squamoid epithelium (n = 4). Peribiliary glands are either hyperplastic or atretic and typically lack RM.Conclusion: Minimally inflammed end-stage lesions in BA remnants occur at youngest ages favoring prenatal onset. Three novel HDR are defined. RM, a useful surrogate for HDR, is a prevalent inappropriate stromal reaction in proximal remnants of uncertain biological significance. RM is the source of mature smooth muscle in BA remnants.

We report a newborn who presented with multiple limb and facial anomalies, endocrine disorders, and progressively worsening low-GGT cholestasis. A liver biopsy revealed hepatocellular cholestasis with giant cell transformation. Immunohistochemical staining revealed complete absence of BSEP protein compared to control liver. A large 2q24-32.2 deletion leading to loss of 78 OMIM genes. Multiple structural anomalies, epilepsy and endocrine anomalies have been described with hemizygous loss of these genes. This deletion also resulted in complete heterozygous deletion of ABCB11, which encodes the bile salt export pump (BSEP). Genetic analysis did not reveal any pathogenic variants, deletions, or duplications in the other ABCB11allele. A heterozygous variant in NR1H4,which causes the autosomal recessive progressive familial intrahepatic cholestasis type 5, was also detected. The possible explanations for the PFIC type 2 phenotype in heterozygous loss of ABCB11include genetic modifiers or di-genic disease with a compound ABCB11deletion and an NR1H4missense variant; or undetected pathogenic variants in the other ABCB11or NR1H4alleles.

Metastases of lung cancer are a major cause of treatment failure. To evaluate the therapeutic efficacy of gene therapy in metastatic lung cancer, we used adenoviral (ADV) mediated transfer of the herpes simplex virus thymidine kinase (HSV-tk) gene and the cytokine gene interleukin-2 (IL-2) to treat a murine model of metastatic lung cancer in the liver. Hepatic metastases were established by intrahepatic implantation of LL2 cells in syugeneic recipient mice. One week after tumor implantation, various replication defective ADV vectors were injected intratumorally. Treatment with a vector expressing the HSV-tk followed by ganciclovir administration with ADV.tk resulted in significant regression of tumor (p[is less than] 0.01) as well as prolongation of survival (p[is less than] 0.001). While a vector expressing mouse IL-2 ADV.IL-2 alone was ineffective, combination therapy with HSV-tk resulted in further tumor regression and improvement of animal survival (p[is less than] 0.05). These results demonstrate that suicide and cytokine genes can be utilized in combination to treat metastatic lung cancer in vivo. (CHEST 1997;112:1332-37) Key words: adenoviral vectors; cytokine gene; gene theraphy; liver metastases; lung cancer; suicide gene Abbreviations: ADV=adenoviral vector; β-Gal=β-galactosidase; GCV= ganciclovir; HSV-tk=herpes simplex virus thymidine kinase; IL-2=interleukin-2; moi=multiplicity of infection; PBS=phosphate-buffered saline solution pfu=plaque-forming unit; tk=thymidine kinase, Lung cancer which is the most prevalent malignancy worldwide, is the leading cause of cancer deaths in many countries.[1] The overall 5-year survival rate is between 10% and 13%, which [...]

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A tribute to Pepper's lasting contributions to Hepatopathology

Hepatic mesenchymal hamartoma is a rare benign neoplasm principally encountered in young children. Its origin is unknown. We report an unusual hepatic mesenchymal hamartoma in a 7-month-old girl, including histopathologic findings, immunophenotype, and karyotype. Chromosomal microarray analysis of tumoral tissue and circulating lymphocytes found 4 copies of a segment at 1q44 and fluorescence in situ hybridization indicated tandem triplication, ascribed to expansion of a paternal tandem duplication. This genetic abnormality may have played a role in pathogenesis.

Autopsy reports of 78 stillbirths and early infant deaths (up to age 8 weeks) were reviewed to investigate the prevalence of extrahepatic nonreticuloendothelial siderosis (EHNRS) in the context of neonatal liver failure. Of these, 10 liveborns (12.8%), M:F 3:2, with mean gestational age 37.6 weeks (range: 35–39) and mean age at the time of demise 19.1 days (range: 7–42), showed significant liver injury: infection (n = 7, viral > fungal), congenital malformations (n = 2), and ischemia (n = 1). None had maternal history of gestational alloimmune liver disease (GALD) or previous fetal/neonatal death due to liver failure. Seven of 10 cases (70%) showed EHNRS: pancreas (n = 6), kidneys (n = 4), thyroid and adrenal glands (n = 3), and bronchial glands and heart (n = 2). Iron deposition was most frequent in the pancreas (60%), most diffuse in the kidneys, and seen in at least 2 organs, with pancreas and kidney being the most frequent combination. Hepatic C5b-9 expression was variable (1+ to 4+) except 1 case (100% necrosis). The duration of illness and the mean age at the time of demise tended to be higher in those with EHNRS. In summary, hepatic and EHNRS, with or without C5b-9 expression, are not specific for GALD. Other causes of liver failure should be investigated as clinically and pathologically appropriate.

Hepatocellular carcinoma (HCC) has been linked to chronic viral or metabolic liver disease and other conditions. The characteristics of children with HCC have not been fully elucidated and outcomes in children with predisposing liver disease are not well defined. Patients ?21 years old with HCC managed at our institution and through external consultation between 1996 and 2016 were included. Demographics, clinical history, and pathology were tabulated. Fisher exact test and Wilcoxon test were employed for subgroup comparison, and survival differences were evaluated by Kaplan-Meier method. Sixty-one cases of HCC were identified. Seven of 16 patients (44%) at our institution and 18 of 45 consult patients (40%) had a predisposing condition: cryptogenic cirrhosis/steatosis (9), genetic (7), biliary pathology (4), viral hepatitis (1), and other (4). Thirteen of 27 patients with de novo HCC had fibrolamellar HCC. Clinical characteristics were grouped by presence or absence of predisposing conditions: age at diagnosis (7.2 vs 10.2 years, P< 0.05), metastatic disease at presentation (15% vs 44%, P= n.s), and tumor size >4 cm (20% vs 100%, P< 0.05). In patients treated at our institution, 5 of 7 with predisposing conditions received liver transplant and achieved complete remission, whereas only 3 of 9 patients with de novo HCC received curative surgery and this group had decreased median overall survival (P< 0.05). The majority of children with HCC did not have predisposing liver or associated disease. These patients were diagnosed later with more advanced stage disease and had significantly decreased overall survival.

Systematic study of allograft liver histology in children undergoing orthotopic liver transplantation (LT) for cystic fibrosis-related liver disease (CFLD). Retrospective clinicopathologic review of explants and allograft liver biopsies from 13 children and adolescents with CFLD. In this study, the median age at LT for CFLD was 15.7 years. Notably, 10 of 13 (77%) CF explants had >5% steatosis and 8 of 13 (61.5%) demonstrated variable fibrosis. The median age, sex, type of transplant (liver vs liver-lung), pancreatic insufficiency status, body mass index (BMI) percentile, genotype, and prevalence of diabetes were comparable in those with and without explant steatosis. More than half of allograft biopsies showed significant steatosis (17/31, 54.8%) and lobular inflammation (16/31, 51.6%). Hepatocyte ballooning was less frequent (5/31, 16.1%). Overall, 6 patients (46.2%) had allograft steatosis that worsened over time in 2 patients (33%). None had advanced fibrosis (=stage 3). Patients with allograft steatosis had significantly more biopsies, were more likely to be “liver only” recipients, had a shorter interval since transplant and higher body mass index percentile (although <85). Patients without explant steatosis never demonstrated allograft steatosis, whereas 60% of patients with explant steatosis (n = 6) developed varying degrees of allograft steatosis. The degree of explant steatosis did not predict its severity in allografts (P= 0.3). This is the first study highlighting the development of allograft steatosis in CF patients. Our findings suggest that allograft steatosis in patients with CF may be related to pre-existing steatosis in native livers, regardless of other risk factors and may have implications on patient management and long-term graft/patient survival.

Supplemental Digital Content is available in the text.Published histologic studies of the hilar plate or entire biliary remnant at the time of Kasai portoenterostomy (KHPE) have not provided deep insight into the pathogenesis of biliary atresia, relation to age at surgery, prognosis or the basis for successful drainage. We report detailed histologic findings in 172 centrally reviewed biliary remnants with an average of 6 sections per subject. Active lesions were classified as either necroinflammatory (rare/clustered in a few subjects) or active concentric fibroplasia with or without inflammation (common). Inactive lesions showed bland replacement by collagen and fibrous cords with little or no inflammation. Heterogeneity was common within a given remnant; however, relatively homogenous histologic patterns, defined as 3 or more inactive or active levels in the hepatic ducts levels, characterized most remnants. Homogeneity did not correlate with age at KHPE, presence/absence of congenital anomalies at laparotomy indicative of heterotaxy and outcome. Remnants from youngest subjects were more likely than older subjects to be homogenously inactive suggesting significantly earlier onset in the youngest subset. Conversely remnants from the oldest subjects were often homogenously active suggesting later onset or slower progression. More data are needed in remnants from subjects <30 days old at KHPE and in those with visceral anomalies. Prevalence of partially preserved epithelium in active fibroplastic biliary atresia lesions at all ages suggests that epithelial regression or injury may not be a primary event or that reepithelialization is already underway at the time of KHPE. We hypothesize that outcome after KHPE results from competition between active fibroplasia and reepithelialization of retained, collapsed but not obliterated lumens. The driver of active fibroplasia is unknown.

Pathogenic sequence variants in the nuclear bile acid receptor FXR, encoded by NR1H4, have been reported in a small number of children with low-?-glutamyl transferase (GGT) cholestasis progressing to liver failure. We describe 3 additional children from 2 unrelated families with cholestasis and liver failure because of pathologic variants in NR1H4. One patient underwent liver transplantation and has had good clinical outcomes in 6 years of follow-up. Although that patient has biochemical evidence of increased bile acid synthetic activity, he has not experienced post-transplant diarrhea or allograft steatosis, as has been reported among other transplanted patients.

Progressive familial intrahepatic cholestasis (PFIC) is a genetically heterogeneous disorder of bile flow disruption due to abnormal canalicular transport or impaired bile acid (BA) metabolism, causing excess BA accumulation and liver failure. We previously reported an intrahepatic cholestasis mouse model based on loss of function of both farnesoid X receptor (FXR; NR1H4) and a small heterodimer partner (SHP; NR0B2) [double knockout (DKO)], which has strong similarities to human PFIC5. We compared the pathogenesis of DKO livers with that of another intrahepatic cholestasis model, Bsep-/-, which represents human PFIC2. Both models exhibit severe hepatomegaly and hepatic BA accumulation, but DKO showed greater circulating BA and liver injury, and Bsep-/- had milder phenotypes. Molecular profiling of BAs uncovered specific enrichment of cholic acid (CA)-derived BAs in DKO livers but chenodeoxycholate-derived BAs in Bsep-/- livers. Transcriptomic and proteomic analysis revealed specific activation of CA synthesis and alternative basolateral BA transport in DKO but increased chenodeoxycholic acid synthesis and canalicular transport in Bsep-/-. The constitutive androstane receptor (CAR)/pregnane X receptor (PXR)-CYP2B/CYP2C axis is activated in DKO livers but not in other cholestasis models. Loss of this axis in Fxr:Shp:Car:Pxr quadruple knockouts blocked Cyp2b/Cyp2c gene induction, impaired bilirubin conjugation/elimination, and increased liver injury. Differential CYP2B expression in DKO and Bsep-/- was recapitulated in human PFIC5 and PFIC2 livers. In conclusion, loss of FXR/SHP results in distinct molecular pathogenesis and CAR/PXR activation, which promotes Cyp2b/Cyp2c gene transcription and bilirubin clearance. CAR/PXR activation was not observed in Bsep-/- mice or PFIC2 patients. These findings provide a deeper understanding of the heterogeneity of intrahepatic cholestasis.

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Cystic epithelium in mesenchymal hamartoma (MH) is typically biliary type. Mucinous differentiation of the epithelium and increased hepatocellular component may pose a diagnostic challenge. We studied MH in 7 children (6 M, 1 F; age 4 months to 8 years, median 1 year). Resected tumors varied from 3.0 to 17.0 cm. All tumors showed biliary epithelium in the cystic component with strong and diffuse reactivity for CK7 and CK19. Expression of CK20 and CDX2 was additionally seen in 2 tumors, rare/focal in 1, and diffuse with mucinous differentiation in the other. Strong and continuous nuclear reactivity for Sox9 was seen in the cyst epithelium in all 7 tumors including focal staining in mucinous areas. It was also positive in the hepatocellular component. CD56 and vimentin were variably positive in the cystic epithelium of all cases. Alpha-fetoprotein showed patchy weak staining in the hepatocellular component and was negative in the cystic epithelium. Hepar-1 showed focal staining in the cystic epithelium in 4/7 cases and diffuse in the hepatocellular component. Both patients showing CK20 and CDX2 expression had abnormal chromosomal analysis: one with balanced translocation between chromosomes 2 and 19 and other with loss of chromosome Y. Among others, one showed 46,XY,inv(9)(p11q12), one did not grow cells, and the remaining 3 had normal karyotype. Six patients underwent resection and one had liver transplantation. All were alive and well with a median follow-up of 1.5 years. In conclusion, mucinous epithelium can be seen in MH. Expression of Sox9 in the cyst epithelium and hepatocytes suggests a common origin for these components. Expression of vimentin indicates an overlapping epithelial-mesenchymal phenotype. Hepatic MH can show divergent epithelial differentiation including both foregut and hindgut phenotype, which may provide insights into the pathogenesis of this rare neoplasm but does not seem to affect the outcome in this limited series.

Liver disease in the neonate, infant, child, and adolescent may manifest differently depending on the type of disorder. These disorders show marked overlap clinically and on light microscopy. Histology and ultrastructural examination are used in tandem for the diagnosis of most disorders. A final diagnosis or interpretation of the pediatric liver biopsy depends on appropriate and adequate clinical history, laboratory test results, biochemical assays, and molecular analyses, as indicated by the light microscopic and ultrastructural examination.

The liver biopsy guides diagnostic investigation and therapy in infants with undiagnosed cholestasis. Histologic features in the liver may also have prognostic value in the patient with biliary atresia (BA). We assessed the relative value of histologic features in 227 liver needle biopsies in discriminating between BA and other cholestatic disorders in infants enrolled in a prospective Childhood Liver Disease Research Network (ChiLDReN) cohort study by correlating histology with clinical findings in infants with and without BA. In addition, we reviewed 316 liver biopsies from clinically proven BA cases and correlated histologic features with total serum bilirubin 6 months after hepatoportoenterostomy (the Kasai procedure, HPE) and transplant-free survival up to 6 years. Review pathologists were blinded to clinical information except age. Semiquantitative scoring of 26 discrete histologic features was based on consensus. Bile plugs in portal bile ducts/ductules, moderate to marked ductular reaction, and portal stromal edema had the largest odds ratio for predicting BA versus non-BA by logistic regression analysis. The diagnostic accuracy of the needle biopsy was estimated to be 90.1% (95% confidence interval [CI]: 85.2%, 94.9%), whereas sensitivity and specificity for a diagnosis of BA are 88.4% (95% CI: 81.4, 93.5) and 92.7% (95% CI: 84.8, 97.3), respectively. No histologic features were associated with an elevated serum bilirubin 6 months after HPE, although it (an elevated serum bilirubin) was associated with an older age at HPE. Higher stages of fibrosis, a ductal plate configuration, moderate to marked bile duct injury, an older age at HPE, and an elevated international normalized ratio were independently associated with a higher risk of transplantation.

Hepatoblastoma is the most common malignant liver tumor in childhood. It has been associated with a variety of constitutional syndromes and gene mutations. However, there are very few reports of associations with pediatric hepatocellular adenomas (HCAs) and no reported associations with pigmented HCAs (P-HCAs). We present a unique case of hepatoblastoma arising in a background of 2 β-catenin-activated HCAs, one of which is pigmented, in a 4-year-old child. The gross, histologic, and immunohistochemical features are described for each tumor. In addition, the literature is reviewed with specific emphasis on the clinical and pathologic features of B-HCAs. Although the potential of β-catenin-activated HCAs to progress to hepatocellular carcinoma has been well documented, there are very few reports of their potential to progress to hepatoblastoma. We not only present such a case, but, to our knowledge, we also present the first case of a P-HCA in a child.

Supplemental Digital Content is available in the text.Undifferentiated embryonal sarcoma of the liver (UESL) is a rare and aggressive pediatric malignancy. The purpose of this study was to review the clinical, radiologic, and pathologic features and outcome of children with UESL at our institution, in the United Network of Organ Sharing database and to review the existing literature to define the state of the art for children with UESL. Six children were diagnosed with UESL at the Texas Children’s Cancer Center between 1993 and 2014, 12 children underwent liver transplantation registered in the United Network of Organ Sharing database, and 198 children with UESL were described in 23 case series during 1978 to 2014. Patients were treated with multimodal treatment approaches including primary surgical resection, neoadjuvant and/or adjuvant chemotherapy, and liver transplantation resulting in overall survival reported between 20% and 100% with significant improvement over the recent years. We show that complete tumor removal remains the key element of treatment and our single-institutional experience and data in the published literature suggest that combination chemotherapy with ifosfamide and doxorubicin to facilitate complete surgical resection is an effective approach to cure children with UESL.

The C19MCgene on chromosome band 19q13.4 encodes a cluster of 46 microRNAs; those microRNAs are normally only expressed from the paternal allele and in the placenta. Placental expression correlates with selective demethylation of the paternal C19MCpromoter, in contrast to methylation of both maternal and paternal alleles in nonplacental tissues. Prior investigations demonstrated “ectopic” activation of this gene in most hepatic mesenchymal hamartomas, including sporadic tumors and others with androgenetic-biparental mosaicism (subset of cells are diploid, but contain only paternally derived chromosomes). In the present investigation of C19MCpromoter methylation status in a series of 14 mesenchymal hamartomas, a demethylated allele was identified in 6 tumors, including all 4 with androgenetic-biparental mosaicism. Conversely, only methylated alleles were cloned from sporadic hamartomas, including 3 tumors with chromosomal rearrangements thought likely to activate C19MCexpression independent of the native promoter. In conjunction with published data, the findings suggest multiple molecular mechanisms for C19MCactivation in hepatic mesenchymal hamartoma, including the existence of a normal placental imprinting pattern in mesenchymal cells in a subset of cases. Some or all of the latter hamartomas may result from placental “grafting,” a hypothesis supported by endothelial expression of the placental vascular marker, glucose transporter-1, in 1 of the 6 cases with a demethylated allele.

Teratomas of the liver are exceedingly rare. Neuroblastoma is the most common, extracranial solid tumor of infancy. We describe the case of a 2-month-old, female infant who presented with an abdominal mass arising in the right lobe of the liver, and a severe coagulopathy, which necessitated cryoprecipitate infusion. Biopsy was interpreted as hepatoblastoma. Following resection, difficulty classifying the mass led to several consultations, and an eventual diagnosis of teratoma. During follow-up, the patient was diagnosed with right adrenal neuroblastoma, which, in retrospect, had been present before the hepatic resection. To our knowledge, these 2 tumors have never been reported together, or in combination with isolated hypofibrinogenemia.

A 4-year-old girl diagnosed with stage III hepatoblastoma presented for tumor resection. She had received four neoadjuvant cycles of cisplatin, 5-fluorouracil, and doxorubicin with good response. On perioperative imaging, several ring-enhancing lesions were noted in the liver concerning for satellite lesions vs. infectious etiology. A biopsy revealed abscess due to Escherichia coli, so the patient was admitted to receive intravenous antibiotics. Ten days after admission, the liver lesions had decreased in size and a right hemihepatectomy was performed to resect the primary tumor. The patient recovered uneventfully on 7 additional days of antibiotics, with resolution of liver abscess on repeat imaging.

Adult liver progenitor cells are biliary-like epithelial cells that emerge only under injury conditions in the periportal region of the liver. They exhibit phenotypes of both hepatocytes and bile ducts. However, their origin and their significance to injury repair remain unclear. Here, we used a chimeric lineage tracing system to demonstrate that hepatocytes contribute to the progenitor pool. RNA-sequencing, ultrastructural analysis, and in vitro progenitor assays revealed that hepatocyte-derived progenitors were distinct from their biliary-derived counterparts. In vivo lineage tracing and serial transplantation assays showed that hepatocyte-derived proliferative ducts retained a memory of their origin and differentiated back into hepatocytes upon cessation of injury. Similarly, human hepatocytes in chimeric mice also gave rise to biliary progenitors in vivo. We conclude that human and mouse hepatocytes can undergo reversible ductal metaplasia in response to injury, expand as ducts, and subsequently contribute to restoration of the hepatocyte mass.

Severe congenital hypertriglyceridemia (HTG) is a rare disorder caused by mutations in genes affecting lipoprotein lipase (LPL) activity. Here we report a 5-week-old Hispanic girl with severe HTG (12,031 mgdL, normal limit 150 mgdL) who presented with the unusual combination of lower gastrointestinal bleeding and milky plasma. Initial colonoscopy was consistent with colitis, which resolved with reduction of triglycerides. After negative sequencing of the LPLgene, whole-exome sequencing revealed novel compound heterozygous mutations in GPIHBP1. Our study broadens the phenotype of GPIHBP1-associated HTG, reinforces the effectiveness of whole-exome sequencing in Mendelian diagnoses, and implicates triglycerides in gastrointestinal mucosal injury.

Liver tumors are rare in children, and their diagnoses may be challenging particularly because of the lack of a current consensus classification system. Systematic central histopathological review of these tumors performed as part of the pediatric collaborative therapeutic protocols has allowed the identification of histologic subtypes with distinct clinical associations. As a result, histopathology has been incorporated within the Children’s Oncology Group (COG) protocols, and only in the United States, as a risk-stratification parameter and for patient management. Therefore, the COG Liver Tumor Committee sponsored an International Pathology Symposium in March 2011 to discuss the histopathology and classification of pediatric liver tumors, and hepatoblastoma in particular, and work towards an International Pediatric Liver Tumors Consensus Classification that would be required for international collaborative projects. Twenty-two pathologists and experts in pediatric liver tumors, including those serving as central reviewers for the COG, European Société Internationale d’Oncologie Pédiatrique, Gesellschaft für Pädiatrische Onkologie und Hämatologie, and Japanese Study Group for Pediatric Liver Tumors protocols, as well as pediatric oncologists and surgeons specialized in this field, reviewed more than 50 pediatric liver tumor cases and discussed classic and newly reported entities, as well as criteria for their classification. This symposium represented the first collaborative step to develop a classification that may lead to a common treatment-stratification system incorporating tumor histopathology. A standardized, clinically meaningful classification will also be necessary to allow the integration of new biological parameters and to move towards clinical algorithms based on patient characteristics and tumor genetics, which should improve future patient management and outcome.

Total parenteral nutrition (TPN) is associated with the development of parenteral nutrition-associated liver disease (PNALD) in infants. Fish oil-based lipid emulsions can reverse PNALD, yet it is unknown if they can prevent PNALD. We studied preterm pigs administered TPN for 14 days with either 100% soybean oil (IL), 100% fish oil (OV), or a mixture of soybean oil, medium chain triglycerides (MCTs), olive oil, and fish oil (SL); a group was fed formula enterally (ENT). In TPN-fed pigs, serum direct bilirubin, gamma glutamyl transferase (GGT), and plasma bile acids increased after the 14 day treatment but were highest in IL pigs. All TPN pigs had suppressed hepatic expression of farnesoid X receptor (FXR), cholesterol 7-hydroxylase (CYP7A1), and plasma 7α-hydroxy-4-cholesten-3-one (C4) concentrations, yet hepatic CYP7A1 protein abundance was increased only in the IL versus ENT group. Organic solute transporter alpha (OSTα) gene expression was the highest in the IL group and paralleled plasma bile acid levels. In cultured hepatocytes, bile acid-induced bile salt export pump (BSEP) expression was inhibited by phytosterol treatment. We show that TPN-fed pigs given soybean oil developed cholestasis and steatosis that was prevented with both OV and SL emulsions. Due to the presence of phytosterols in the SL emulsion, the differences in cholestasis and liver injury among lipid emulsion groups in vivo were weakly correlated with plasma and hepatic phytosterol content.

Elevated bile acid levels increase hepatocellular carcinoma by unknown mechanisms. Here, we show that mice with a severe defect in bile acid homeostasis due to the loss of the nuclear receptors FXR and SHP have enlarged livers, progenitor cell proliferation, and Yes-associated protein (YAP) activation and develop spontaneous liver tumorigenesis. This phenotype mirrors mice with loss of hippokinases or overexpression of their downstream target, YAP. Bile acids act as upstream regulators of YAP via a pathway dependent on the induction of the scaffold protein IQGAP1. Patients with diverse biliary dysfunctions exhibit enhanced IQGAP1 and nuclear YAP expression. Our findings reveal an unexpected mechanism for bile acid regulation of liver growth and tumorigenesis via the Hippopathway.

Beneficial microbes and probiotics are promising agents for the prevention and treatment of enteric and diarrheal diseases in children; however, little is known about their in vivo mechanisms of action. We used a neonatal mouse model of rotavirus diarrhea to gain insight into how probiotics ameliorate acute gastroenteritis.

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in various diseases. This article reviews the most common metabolic disorders in humans that are associated with neoplasms, with a special emphasis on the molecular etiopathogenesis of this process. The cellular pathways driving carcinogenesis are poorly understood, but best known in tyrosinemia.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS; OMIM%249210) is a rare and severe form of congenital intestinal and urinary dysfunction and malformation. Histologic studies suggest that the predominant intestinal manifestation is smooth muscle myopathy. Molecular observations have linked the disease to the neuronal nicotinic acetylcholine receptor (ηAChR), namely the absence of a functional α3 subunit of the ηAChR in patients with MMIHS. We describe a case of MMIHS in association with a de novo deletion of the proximal long arm of chromosome 15 (15q11.2). Histologic evaluation revealed an appropriate light microscopic appearance of both the circular and longitudinal layers of the small bowel muscularis propria. Immunohistochemical staining for smooth muscle actin, however, was selectively absent in the circular layer, demonstrating isolated absence in a unique and previously undescribed pattern. These observations raise the possibility that the proximal long arm of chromosome 15 (15q11) may be of clinical significance in MMIHS.

Nested stromal epithelial tumor is a recently described primary neoplasm of the liver. This tumor is characterized by well-demarcated nests of spindle and epithelioid cells with occasional calcification and bone formation. An association between these tumors and Cushing syndrome has been described. Herein we report a case of a recurrent nested stromal epithelial tumor of the liver in a 17-year-old female with aggressive clinical behavior and an extrahepatic lymph node metastasis. Also, we provide the first detailed clinical, histologic, immunohistochemical, and cytogenetic comparison of the original and recurrent tumors. Initially, the patient presented with Cushingoid symptoms and epigastric pain, radiating to her back. A computed tomographic (CT) scan revealed a large lesion in the liver. After a partial hepatectomy, the Cushingoid features were resolved. A year later, a CT scan revealed multiple lesions within the liver, and positron emission tomographic/CT imaging showed a hypermetabolic lymph node. The patient underwent a cadaveric liver transplant. Histologically, both the original and recurrent tumors had similar characteristics, with different immunoreactivity, correlating with the absence of systemic hormonal symptoms. Electron microscopy of the original neoplasm revealed an abundance of rough cytoplasmic reticulum and mitochondria. No evidence of endocrine differentiation was found. Cytogenetics of the primary tumor was complex with an abnormal hypotriploid karyotype. Our data indicate that patients with nested stromal epithelial tumor of the liver must be carefully followed with imaging to detect hepatic recurrence and extrahepatic metastases.

We have investigated the in vivo safety, efficacy, and persistence of autologous Epstein Barr virus (EBV)–specific cytotoxic T lymphocytes (CTLs) for the treatment of solid organ transplant (SOT) recipients at high risk for EBV-associated posttransplantation lymphoproliferative disease (PTLD). EBV-CTLs generated from 35 patients expanded with normal kinetics contained both CD8 and CD4 lymphocytes and produced significant specific killing of autologous EBV-transformed B lymphoblastoid cell lines (LCLs). Twelve SOT recipients at high risk for PTLD, or with active disease, received autologous CTL infusions without toxicity. Real-time polymerase chain reaction (PCR) monitoring of EBV-DNA showed a transient increase in plasma EBV-DNA suggestive of lysis of EBV-infected cells, although there was no consistent decrease in virus load in peripheral-blood mononuclear cells. Interferon-γ enzyme-linked immunospot (ELISPOT) assay and tetramer analysis showed an increase in the frequency of EBV-responsive T cells, which returned to preinfusion levels after 2 to 6 months. None of the treated patients developed PTLD. One patient with liver PTLD showed a complete response, and one with ocular disease has had a partial response stable for over one year. These data are consistent with an expansion and persistence of adoptively transferred EBV-CTLs that is limited in the presence of continued immunosuppression but that nonetheless produces clinically useful antiviral activity.

Helper-dependent adenoviral vectors (HDAds) are attractive vectors for liver-directed gene therapy because they can mediate sustained, high-level transgene expression without chronic toxicity. However, high vector doses are required to achieve efficient hepatic transduction by systemic delivery because of a nonlinear dose response. Unfortunately, such high doses result in systemic vector dissemination and dose-dependent acute toxicity with potentially severe and lethal consequences. We hypothesize that the threshold to efficient hepatic transduction may be circumvented by delivering the vector into the surgically isolated liver via the portal vein. Total hepatic isolation was achieved by occluding hepatic inflow from the portal vein and hepatic artery and by occluding hepatic venous outflow at the inferior vena cava. We demonstrate in nonhuman primates that this approach resulted in significantly higher efficiency hepatic transduction with reduced systemic vector dissemination compared with systemic intravascular delivery. This method of delivery was associated with transient acute toxicity, the severity of which was variable. Importantly, stable, high levels of transgene expression were obtained for at least 665 days for one baboon and for at least 560 days for two baboons with no evidence of long-term toxicity.

Wilson disease is a severe genetic disorder associated with intracellular copper overload. The affected gene, ATP7B, has been identified, but the molecular events leading to Wilson disease remain poorly understood. Here, we demonstrate that genetically engineered Atp7b−/−mice represent a valuable model for dissecting the disease mechanisms. These mice, like Wilson disease patients, have intracellular copper accumulation, low-serum oxidase activity, and increased copper excretion in urine. Their liver pathology developed in stages and was determined by the time of exposure to elevated copper rather than copper concentration per se. The disease progressed from mild necrosis and inflammation to extreme hepatocellular injury, nodular regeneration, and bile duct proliferation. Remarkably, all animals older than 9 months showed regeneration of large portions of the liver accompanied by the localized occurrence of cholangiocarcinoma arising from the proliferating bile ducts. The biochemical characterization of Atp7b−/−livers revealed copper accumulation in several cell compartments, particularly in the cytosol and nuclei. The increase in nuclear copper is accompanied by marked enlargement of the nuclei and enhanced DNA synthesis, with these changes occurring before pathology development. Our results suggest that the early effects of copper on cell genetic material contribute significantly to pathology associated with Atp7binactivation.

Aldehyde reductase reduces a wide variety of toxic and physiological aldehydes with a marked preference for negatively charged substrates such as glucuronate. Reduction of glucuronate to gulonate is a step in inositol catabolism, a process specific to the kidney cortex. Administration of the aldehyde reductase inhibitor AL-1576 to mice increases urinary output of glucuronate and decreases output of vitamin C. Aldehyde reductase mRNA with a 319-bp 5′-untranslated region is expressed ubiquitously in murine tissues. A new isoform with a short 64-bp 5′-untranslated region is found predominantly in the kidney, resulting in 10-fold higher enzymatic activity observed in this organ compared with other tissues. A moderate level of the new transcript is found in liver, intestine, and stomach, whereas brain, heart, lung, spleen, ovary, and testis have low to insignificant levels. The short transcript is absent during embryonic development and is first observed in the murine kidney on postnatal day 6. The abundance of the short transcript and enzyme activity increase sigmoidally with age; the sharpest increase occurs during the third week of life. As shown by immunohistochemistry, aldehyde reductase expression is limited to the proximal tubules and parietal epithelium of Bowman’s capsule. In the mouse, the intensity of staining in tubules increases with age, suggesting that induction of aldehyde reductase expression is part of renal tubular maturation. The human kidney also exhibits proximal tubular localization and the two mRNA transcripts of aldehyde reductase. Immunoreactive protein is present in the 9-wk-old fetal kidney, indicating that the induction of aldehyde reductase in humans occurs early in development.

Epidemiologic studies indicate that the overall risk of malignancy among patients with cystic fibrosis (CF) is similar to that of the general population. However, these studies and a number of case reports suggest that patients with CF may be at increased risk for the development of specific gastrointestinal cancers. Tumors of the esophagus, stomach, small and large bowels, liver and biliary tracts, and pancreas have been described. Previous reports of pancreatic cancers among patients with CF have included only adenocarcinoma in adults. This is the first description of a mucinous cystadenocarcinoma of the pancreas in an adolescent with CF. The tumor developed within a pancreatic cyst that had been initially identified 13 years before resection. Our report highlights the increased risk of pancreatic malignancy among patients who have CF and illustrates the premalignant potential of pancreatic cysts in this at-risk population. Further, it reinforces the need for careful surveillance and suggests a role for more aggressive diagnostic and therapeutic interventions for patients with atypical findings on pancreatic imaging studies.

The evaluation of long-term cellular immunity to EBV in pediatric orthotopic liver transplant (OLT) recipients after treatment with the humanized anti-CD20 monoclonal antibody (Rituximab) has not yet been explored. At our institution, one child with EBV-related mononucleosis-like syndrome and five children with polymorphic-EBV-PTLD occurring 6–88 months after OLT were treated with Rituximab. Treatment was well tolerated. All children achieved complete remission. After Rituximab, B-lymphocytes were undetectable in the peripheral blood and EBV-load, monitored with real-time PCR, decreased to undetectable levels in all children from >4000 copies/μg DNA at diagnosis. Four to eight months after Rituximab, EBV-load increased (>4000 copies/μg DNA) in four children, and PTLD recurred in three. Their frequency of EBV-specific T-cell precursors, measured by Elispot analysis, remained lower than in healthy controls. Rituximab effectively induced regression of PTLD in OLT recipients. However, EBV-specific T-cell immunocompetence, which may be crucial for the long-term control of EBV-mediated proliferation, did not improve.

Deletion of αi2 subunit of heterotrimeric G proteins induces a 2–4-fold increase in the proportions of CD4 and CD8 single-positive (SP) thymocytes as compared with wild-type littermates, but how Gαi2 is involved in thymocyte development is unknown. To determine a role for Gαi2 in a specific developmental stage of thymocyte differentiation, we studied the ontogeny of thymocytes in Gαi2-deficient mice. Our data show that an accelerated transition from the double-positive (DP) to SP thymocytes, rather than impairment in thymic emigration, accounts for a high proportion of the SP thymocytes in the absence of Gαi2. Lack of Gαi2 greatly augmented a response of thymocytes to TCR-mediated stimulation, as evidenced by enhanced proliferation of the DP thymocytes upon ligation of the TCRs. The augmented response may be the reason behind the expedited transition from the DP to SP thymocytes in the animal. In accordance with this, effects of Gαi2 deficiency on CD8 or CD4 SP thymocyte differentiation required engagement of the TCRs with either MHC class I or MHC class II molecule. The abnormal thymocyte development resulted in an increase in positive selection, altered usage of TCR Vβ gene, aberrant development of CD4+CD25+ T regulatory cells and untimely thymic involution, the contribution of which to colitis development in the animal is discussed. These findings reveal a previously unappreciated role for Gαi2 protein in clonal selection and functionality of thymocytes.

Systemic intravascular delivery of adenoviral (Ad) vectors for liver-directed gene therapy has been widely employed because of its simplicity, noninvasiveness, and potential for high transduction. For first-generation Ad vectors (FGAd), this results in high but transient levels of transgene expression and long-term hepatotoxicity due to viral gene expression from the vector backbone. Furthermore, high doses also result in an acute innate inflammatory response with potentially lethal consequences. Unlike FGAd, helper-dependent Ad vectors (HDAd) contain no viral genes and can provide sustained, high-level transgene expression with negligible long-term toxicity. However, whether the absence of viral gene expression leads to any decrease of acute toxicity in nonhuman primates has yet to be determined. To address this, we injected one baboon with 5.6 × 1012 HDAd viral particles (VP)/kg and a second with 1.1 × 1013 VP/kg. Approximately 50% hepatocyte transduction, accompanied by mild and transient acute toxicity, was observed in the animal receiving the lower dose. In the animal receiving the higher dose, 100% hepatocyte transduction, accompanied by lethal acute toxicity, was observed. These results indicate that systemic delivery of HDAd, like FGAd, results in acute toxicity in baboons consistent with activation of the innate inflammatory response, the severity of which is dose dependent, and confirm the hypothesis that Ad-mediated acute toxicity is independent of viral gene expression.

During rodent development there are two surges of circulating corticosterone: one just prior to birth and then one in the third postnatal week. Prior studies have shown that the latter controls the rate of intestinal development in the postnatal period. To date, a role for the earlier surge in the prenatal phase of intestinal development has not been investigated. We hypothesized that the late fetal surge of circulating corticosterone is involved in both morphologic and functional maturation of the intestinal epithelium, and thus that such maturation would be delayed if glucocorticoid action was abrogated. The hypothesis was tested by studying intestinal development in mice lacking a functional glucocorticoid receptor (GR). After GR+/− mice were bred onto a C57Bl/6 background, heterozygote matings yielded the expected ratios of −/−, +/−, and +/+ offspring. Analysis of GR mRNA in intestines of +/+ and −/− fetuses confirmed expression in wild-type mice but not in the GR-null mice. Intestinal histology of GR+/+ and −/− littermates at E13.5, E15.5, and E18.5 showed no effect of GR genotype on morphologic development. Further studies at E18.5 showed that GR−/− mice have normal functional maturation of the intestinal epithelium as assessed by: lactase activity in the enterocyte lineage, normal numbers of goblet and enteroendocrine cells, and normal numbers of proliferating cells in the intestinal crypts. Neither the minerolocorticoid receptor (MR) nor the pregnane X receptor (PXR) showed compensatory up-regulation in GR−/− mice. We conclude that, in contrast to our original hypothesis, the rodent intestine passes through a phase of glucocorticoid independence (late fetal) prior to becoming responsive to glucocorticoids in the postnatal period. These findings have implications for the clinical use of corticosteroids to enhance intestinal maturation in preterm infants. © 2002 Wiley-Liss, Inc.

ABSTRACTHumans chronically infected with hepatitis B virus (HBV) are at further risk of liver cancer upon exposure to dietary aflatoxin B1 (AFB1), a carcinogenic product of the mold Aspergillus flavus.For the present study, we utilized double-transgenic mice (ATX mice) that express the HBV X protein (HBx) and possess a bacteriophage lambda transgene to evaluate the in vivo effect of HBx expression on AFB1-induced DNA mutations. The expression of HBx correlated with a 24% increase in mutation frequency overall and an approximately twofold increase in the incidence of G/C-to-T/A transversion mutations following AFB1 exposure. These results are consistent with a model in which expression of HBx during chronic HBV infection may contribute to the development of hepatocellular carcinoma following exposure to environmental carcinogens.

Recent work has convincingly demonstrated that adult bone marrow contains cells capable of differentiating into liver epithelial cells in vivo. However, the frequency and time course with which fully functional hepatocytes emerge after bone marrow transplantation remained controversial. Here, we used the fumarylacetoacetate hydrolase knockout mouse to determine the kinetics of hepatocyte replacement after complete hematopoietic reconstitution. Single donor-derived hepatocytes were first detected 7 weeks after lethal irradiation and bone marrow transplantation. Liver disease was not required for this transdifferentiation. In the presence of selective pressure the single cells evolved into hepatocyte nodules by 11 weeks after transplantation and resulted in 30% overall liver repopulation by 22 weeks. The frequency with which hepatocytes were produced was between 10−4and 10−6, resulting in only 50 to 500 repopulation events per liver. Hepatic engraftment was not observed without previous hematopoietic reconstitution even in the presence of liver injury. In addition, significant liver repopulation was completely dependent on hepatocyte growth selection. We conclude that hepatocyte replacement by bone marrow cells is a slow and rare event. Significant improvements in the efficiency of this process will be needed before clinical success can be expected.

ABSTRACTIn mammals, the catabolic pathway of phenylalanine and tyrosine is found in liver (hepatocytes) and kidney (proximal tubular cells). There are well-described human diseases associated with deficiencies of all enzymes in this pathway except for maleylacetoacetate isomerase (MAAI), which converts maleylacetoacetate (MAA) to fumarylacetoacetate (FAA). MAAI is also known as glutathione transferase zeta (GSTZ1). Here, we describe the phenotype of mice with a targeted deletion of the MAAI(GSTZ1) gene. MAAI-deficient mice accumulated FAA and succinylacetone in urine but appeared otherwise healthy. This observation suggested that either accumulating MAA is not toxic or an alternate pathway for MAA metabolism exists. A complete redundancy of MAAI could be ruled out because substrate overload of the tyrosine catabolic pathway (administration of homogentisic acid, phenylalanine, or tyrosine) resulted in renal and hepatic damage. However, evidence for a partial bypass of MAAI activity was also found. Mice doubly mutant for MAAIand fumarylacetoacetate hydrolase (FAH) died rapidly on a normal diet, indicating that MAA could be isomerized to FAA in the absence of MAAI. Double mutants showed predominant renal injury, indicating that this organ is the primary target for the accumulated compound(s) resulting from MAAI deficiency. A glutathione-mediated isomerization of MAA to FAA independent of MAAI enzyme was demonstrated in vitro. This nonenzymatic bypass is likely responsible for the lack of a phenotype in nonstressed MAAImutant mice.

ABSTRACTGroup A rotaviruses are major pathogens causing acute gastroenteritis in children and animals. To determine if group A rotavirus replicates and induces disease in rats, antibody-negative Lewis neonatal or adult rats were inoculated orally with tissue culture-adapted human (Wa, WI61, and HAL1166), simian (rhesus rotavirus [RRV] and SA11), bovine (WC3), lapine (ALA), or porcine (OSU) rotavirus strains, wild-type murine (ECwt) rotavirus strain, or phosphate-buffered saline (PBS). Rotavirus infection in rats was evaluated by (i) clinical findings, (ii) virus antigen shedding or infectious virus titers in the feces or intestinal contents measured by enzyme-linked immunosorbent assay or fluorescent-focus assay, (iii) histopathological changes in the small intestine, (iv) distribution of rotavirus antigen in small-intestine sections by immunofluorescence, and (v) growth rate. Rotavirus infection of 5-day-old but not =21-day-old rats resulted in diarrhea that lasted from 1 to 10 days postinoculation. The severity of disease and spread of infection to naI¨ve littermates differed depending on the virus strain used for inoculation. The duration of virus antigen shedding following infection was considerably prolonged (up to 10 days) in neonatal rats compared to that in 21-day-old rats (1 or 2 days). Based on lack of virus antigen shedding and disease induction, the murine ECwtrotavirus was the only strain tested that did not infect rats. Histopathological changes in the small-intestine mucosa of 5-day-old RRV-inoculated rats but not of PBS-inoculated rats was limited to extensive enterocyte vacuolation in the ileum. In RRV-inoculated neonatal rats, rotavirus antigen was detected in the epithelial cells on the upper half of the intestinal villi of the jejunum and ileum. In addition, infection of neonatal rats with RRV but not with PBS resulted in reduced weight gain. Rats infected with group A rotaviruses provide a new animal model with unique features amenable to investigate rotavirus pathogenesis and the molecular mechanisms of intestinal development, including physiological factors that may regulate age-dependent rotavirus-induced diarrhea.