Rachel Sheridan

IL-17 signaling accelerates the progression of nonalcoholic fatty liver disease in mice

Inflammation plays a central pathogenic role in the pernicious metabolic and end‐organ sequelae of obesity. Among these sequelae, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the developed world. The twinned observations that obesity is associated with increased activation of the interleukin (IL)‐17 axis and that this axis can regulate liver damage in diverse contexts prompted us to address the role of IL‐17RA signaling in the progression of NAFLD. We further examined whether microbe‐driven IL‐17A regulated NAFLD development and progression. We show here that IL‐17RA−/− mice respond to high‐fat diet stress with significantly greater weight gain, visceral adiposity, and hepatic steatosis than wild‐type controls. However, obesity‐driven lipid accumulation was uncoupled from its end‐organ consequences in IL‐17RA−/− mice, which exhibited decreased steatohepatitis, nicotinamide adenine dinucleotide phosphate (NADPH)‐oxidase enzyme expression, and hepatocellular damage. Neutralization of IL‐17A significantly reduced obesity‐driven hepatocellular damage in wild‐type mice. Further, colonization of mice with segmented filamentous bacteria (SFB), a commensal that induces IL‐17A production, exacerbated obesity‐induced hepatocellular damage. In contrast, SFB depletion protected from obesity‐induced hepatocellular damage. Conclusion: These data indicate that obesity‐driven activation of the IL‐17 axis is central to the development and progression of NAFLD to steatohepatitis and identify the IL‐17 pathway as a novel therapeutic target in this condition. (Hepatology 2014;59:1830–1839)

Thermoneutral housing exacerbates nonalcoholic fatty liver disease in mice and allows for sex-independent disease modeling

Nonalcoholic fatty liver disease (NAFLD), a common prelude to cirrhosis and hepatocellular carcinoma, is the most common chronic liver disease worldwide. Defining the molecular mechanisms underlying the pathogenesis of NAFLD has been hampered by a lack of animal models that closely recapitulate the severe end of the disease spectrum in humans, including bridging hepatic fibrosis. Here we demonstrate that a novel experimental model employing thermoneutral housing, as opposed to standard housing, resulted in lower stress-driven production of corticosterone, augmented mouse proinflammatory immune responses and markedly exacerbated high-fat diet (HFD)-induced NAFLD pathogenesis. Disease exacerbation at thermoneutrality was conserved across multiple mouse strains and was associated with augmented intestinal permeability, an altered microbiome and activation of inflammatory pathways that are associated with the disease in humans. Depletion of Gram-negative microbiota, hematopoietic cell deletion of Toll-like receptor 4 (TLR4) and inactivation of the IL-17 axis resulted in altered immune responsiveness and protection from thermoneutral-housing-driven NAFLD amplification. Finally, female mice, typically resistant to HFD-induced obesity and NAFLD, develop full disease characteristics at thermoneutrality. Thus, thermoneutral housing provides a sex-independent model of exacerbated NAFLD in mice and represents a novel approach for interrogation of the cellular and molecular mechanisms underlying disease pathogenesis.

Multimodal therapy including liver transplantation for hepatic undifferentiated embryonal sarcoma

The outcomes of hepatic undifferentiated embryonal sarcoma (HUES) have historically been limited by persistent, unresectable disease and the subsequent development of disease resistance and dissemination. We present our institutional experience with HUES and assess current treatment trends and outcomes in the era of liver transplantation. We conducted a retrospective chart review of cases presenting with HUES at our institution over the past 10 years. The collected data included age, sex, presenting symptoms, imaging and the associated Pretreatment Extent of Disease (PRETEXT) score, pathology, chemotherapy, surgical interventions, and outcomes. Approval was obtained from the institutional review board of the Cincinnati Childrens Hospital Medical Center. HUES was identified in 6 patients (4 males and 2 females) with a median age at diagnosis of 11 years (range = 7‐13 years). Initial imaging was available for all but 1 patient. The PRETEXT stage for these patients ranged from II to III. One patient was diagnosed with lung metastases. Two patients underwent upfront resection, and 1 patient received neoadjuvant therapy and then conventional resection. Three patients were treated with orthotopic liver transplantation (OLT) after neoadjuvant chemotherapy (primary OLT in 2 cases and salvage OLT for local recurrence in 1 case). Two patients received posttransplant adjuvant chemotherapy. All 6 patients remained in clinical remission with a mean follow‐up of 35 months (range = 12‐84 months). In conclusion, OLT has rarely been reported as a treatment option for HUES. The addition of liver transplantation as a surgical option for treating patients with HUES can result in improved survival for patients whose tumors are initially unresectable or recur. Liver Transpl 20:191‐199, 2014.

Multifocal hepatic neoplasia in 3 children with APC gene mutation.

Hepatoblastoma (HB), the most common hepatic neoplasm in children is associated with germline mutations in adenomatous polyposis coli tumor-suppressor gene that cause familial adenomatous polyposis syndrome. Individuals with familial adenomatous polyposis have a 750 to 7500× the risk of developing HB. We report 3 children with APC gene mutation, who underwent resection or liver transplant for HB. In addition to HB, all 3 patients had multiple independent adenoma-like nodules lacking qualities of intrahepatic metastases. Twenty-five nodules were subjected to immunohistochemical analysis using a panel of antibodies including glypican-3 (GPC3), &bgr;-catenin, cytokeratin AE1/AE3, CD34, Ki-67, glutamine synthetase (GS), and fatty acid binding protein. The nodules were round, ranged in size from 0.2 to 1.5 cm, and paler than the background liver. All lacked the chemotherapy effect. The nodules were circumscribed but nonencapsulated and composed of well-differentiated hepatocytes with occasional minor atypical features and absent or rare portal tracts. One lesion displayed a “nodule-within-nodule” pattern. The nodules demonstrated diffuse GS overexpression. Nine (36%) nodules were focally reactive for GPC3, and 1 (4%) displayed focal nuclear &bgr;-catenin expression. The associated HB showed diffuse expression of GS, GPC3, and &bgr;-catenin nuclear staining. We interpret these nodules as neoplastic with most being adenomas (GPC3 negative) that show features of independent origin and represent early stages of carcinogenesis, implying potential to progress to HB or hepatocellular carcinoma. To our knowledge, this is the first report of multifocal neoplasms in patients with HB and APC gene mutation.

von Hippel-Lindau–Dependent Patterns of RNA Polymerase II Hydroxylation in Human Renal Clear Cell Carcinomas

Purpose: We have previously shown that von Hippel-Lindau (VHL) regulates ubiquitylation and proline 1465 hydroxylation of the large subunit of RNA polymerase II, Rpb1, in human renal clear cell carcinoma (RCC) cell lines. Here, our goal was to determine the effect of this VHL function and the status of P1465 hydroxylation in human RCC tumors. Experimental Design: Primary human tumors and matched normal kidney samples were probed for expression levels of the large subunit of RNA polymerase II (Rpb1), Rpb1 hydroxylated on P1465 [Rpb1(OH)], Rpb1 phosphorylated on Ser5 [Rpb1(S5P)], and proline hydroxylases PHD1, PHD2, and PHD3. Results from RCC tumors were categorized according to the status of VHL gene. Mechanistic analysis was performed in orthotopic xenograft model using 786-O RCC cells with wild-type (WT) VHL and knockdown of PHD2, characterized by high levels of Rpb1(OH) and PHD1. Results: Levels of Rpb1(OH), PHD1, and PHD2 were significantly higher in RCC tumors compared with normal kidneys. RCC tumors with WT VHL had higher levels of Rpb1(OH) and PHD1 and lower levels of PHD2 than tumors with VHL gene alterations. Levels of Rpb1(OH) significantly correlated with levels of PHD1 in tumors and normal kidneys. Knockdown of PHD2 in 786-O VHL(+) cells resulted in a more malignant phenotype in orthotopic xenografts and higher expression of specific cell cycle regulators (CDC25A, cyclin-dependent kinase 2, CCNA2) compared with VHL(−) RCC cells. Conclusions: Elevated PHD1 concomitant with decreased PHD2 are causatively related to Rpb1 hydroxylation and oncogenesis in human RCC tumors with WT VHL gene. Thus, P1465-hydroxylated Rpb1 and PHD1 represent attractive drug targets for new RCC treatments. Clin Cancer Res; 16(21); 5142–52. ©2010 AACR.

Integrative genomics identifies candidate microRNAs for pathogenesis of experimental biliary atresia

BackgroundBiliary atresia is a fibroinflammatory obstruction of extrahepatic bile duct that leads to end-stage liver disease in children. Despite advances in understanding the pathogenesis of biliary atresia, very little is known about the role of microRNAs (miRNAs) in onset and progression of the disease. In this study, we aimed to investigate the entire biliary transcriptome to identify miRNAs with potential role in the pathogenesis of bile duct obstruction.ResultsBy profiling the expression levels of miRNA in extrahepatic bile ducts and gallbladder (EHBDs) from a murine model of biliary atresia, we identified 14 miRNAs whose expression was suppressed at the times of duct obstruction and atresia (≥2 fold suppression, P < 0.05, FDR 5%). Next, we obtained 2,216 putative target genes of the 14 miRNAs using in silico target prediction algorithms. By integrating this result with a genome-wide gene expression analysis of the same tissue (≥2 fold increase, P < 0.05, FDR 5%), we identified 26 potential target genes with coordinate expression by the 14 miRNAs. Functional analysis of these target genes revealed a significant relevance of miR-30b/c, -133a/b, -195, -200a, -320 and −365 based on increases in expression of at least 3 target genes in the same tissue and 1st-to-3rd tier links with genes and gene-groups regulating organogenesis and immune response. These miRNAs showed higher expression in EHBDs above livers, a unique expression in cholangiocytes and the subepithelial compartment, and were downregulated in a cholangiocyte cell line after RRV infection.ConclusionsIntegrative genomics reveals functional relevance of miR-30b/c, -133a/b, -195, -200a, -320 and −365. The coordinate expression of miRNAs and target genes in a temporal-spatial fashion suggests a regulatory role of these miRNAs in pathogenesis of experimental biliary atresia.

Lampe1: An ENU-Germline Mutation Causing Spontaneous Hepatosteatosis Identified through Targeted Exon-Enrichment and Next-Generation Sequencing

Using a small scale ENU mutagenesis approach we identified a recessive germline mutant, designated Lampe1 that exhibited growth retardation and spontaneous hepatosteatosis. Low resolution mapping based on 20 intercrossed Lampe1 mice revealed linkage to a ∼14 Mb interval on the distal site of chromosome 11 containing a total of 285 genes. Exons and 50 bp flanking sequences within the critical region were enriched with sequence capture microarrays and subsequently analyzed by next-generation sequencing. Using this approach 98.1 percent of the targeted DNA was covered with a depth of 10 or more reads per nucleotide and 3 homozygote mutations were identified. Two mutations represented intronic nucleotide changes whereas one mutation affected a splice donor site in intron 11–12 of Palmitoyl Acetyl-coenzyme A oxygenase-1 (Acox1), causing skipping of exon 12. Phenotyping of Acox1Lampe1 mutants revealed a progression from hepatosteatosis to steatohepatitis, and ultimately hepatocellular carcinoma. The current approach provides a highly efficient and affordable method to identify causative mutations induced by ENU mutagenesis and animal models relevant to human pathology.

The dendritic cell–T helper 17–macrophage axis controls cholangiocyte injury and disease progression in murine and human biliary atresia

Biliary atresia (BA) is a fibroinflammatory obstruction of the extrahepatic biliary tree in neonates. While intrahepatic bile duct proliferation is universal at diagnosis, bile duct paucity develops later. We hypothesized that polarized T helper lymphocyte responses orchestrate progression of intrahepatic biliary injury in this disease. Interleukin 17A (IL‐17A)‐green fluorescent protein, cluster of differentiation 11c (CD11c)/diphtheria toxin receptor, and IL‐17 receptor A−/− mice were used to examine T‐lymphocyte polarization, inflammatory leukocyte recruitment, and biliary injury in rhesus rotavirus–induced BA. Multiparameter flow cytometry and automated image analysis of immunostaining were applied to liver tissue samples from infants with BA. In the mouse model, activated CD4+ lymphocytes started to emerge in the liver on day 8 after viral challenge, while innate immune responses were waning. Plasma IL‐17A levels rose concomitantly with hepatic accumulation of T helper 17 lymphocytes and myeloid dendritic cells. Targeted depletion of CD11c+ dendritic cells diminished hepatic IL‐17A production and ameliorated intrahepatic bile duct injury. Recombinant IL‐17A induced expression of chemokine (C‐C motif) ligand 2 in neonatal cholangiocytes in vitro, and blockade of the corresponding chemokine (C‐C motif) receptor 2 reduced recruitment of inflammatory macrophages to the liver in vivo. Genetic disruption of IL‐17A signaling was associated with down‐regulation of hepatic Ccl2/Ccr2 messenger RNA expression, reduced infiltration of the liver with inflammatory Ly6Chi macrophages, and improved survival. In the liver of infants with BA, cholangiocytes were found to express IL‐17 receptor A, and the prevalence of IL‐17A+ cells was positively correlated with the degree of CD68+ macrophage infiltration at diagnosis. Hepatic CD4+ lymphocytes were chief producers of IL‐17A in patients with progressive disease undergoing liver transplantation. Conclusion: These findings identify the dendritic cell–T helper 17–macrophage axis as a target for the development of strategies to block progression of intrahepatic bile duct injury in patients with BA. (Hepatology 2017;65:174‐188).

FXR-Gankyrin axis is involved in development of pediatric liver cancer

The development of hepatoblastoma (HBL) is associated with failure of hepatic stem cells (HSC) to differentiate into hepatocytes. Despite intensive investigations, mechanisms of the failure of HSC to differentiate are not known. We found that oncogene Gankyrin (Gank) is involved in the inhibition of differentiation of HSC via triggering degradation of tumor suppressor proteins (TSPs) Rb, p53, C/EBPα and HNF4α. Our data show that the activation of a repressor of Gank, farnesoid X receptor, FXR, after initiation of liver cancer by Diethylnitrosamine (DEN) prevents the development of liver cancer by inhibiting Gank and rescuing tumor suppressor proteins. We next analyzed FXR-Gank-Tumor suppressor pathways in a large cohort of HBL patients which include 6 controls and 53 HBL samples. Systemic analysis of these samples and RNA-Seq approach revealed that the FXR-Gank axis is activated; markers of hepatic stem cells are dramatically elevated and hepatocyte markers are reduced in HBL samples. In the course of these studies, we found that RNA binding protein CUGBP1 is a new tumor suppressor protein which is reduced in all HBL samples. Therefore, we generated CUGBP1 KO mice and examined HBL signatures in the liver of these mice. Micro-array studies revealed that the HBL-specific molecular signature is developed in livers of CUGBP1 KO mice at very early ages. Thus, we conclude that FXR-Gank-TSPs-Stem cells pathway is a key determinant of liver cancer in animal models and in pediatric liver cancer. Our data provide a strong basis for development of FXR-Gank-based therapy for treatment of patients with hepatoblastoma.

Lysosomal Acid Lipase Deficiency Unmasked in Two Children With Nonalcoholic Fatty Liver Disease

Lysosomal acid lipase deficiency (LAL-D) is a classic lysosomal storage disorder characterized by accumulation of cholesteryl ester and triglyceride. Although it is associated with progressive liver injury, fibrosis, and end-stage liver disease in children and adolescents, LAL-D frequently presents with nonspecific signs that overlap substantially with other, more common, chronic conditions like nonalcoholic fatty liver disease (NAFLD), metabolic syndrome, and certain inherited dyslipidemias. We present 2 children with NAFLD who achieved clinically significant weight reduction through healthy eating and exercise, but who failed to have the anticipated improvements in aminotransferases and γ-glutamyl transferase. Liver biopsies performed for these “treatment failures” demonstrated significant microvesicular steatosis, prompting consideration of coexisting metabolic diseases. In both patients, lysosomal acid lipase activity was low and LIPA gene testing confirmed LAL-D. We propose that LAL-D should be considered in the differential diagnosis when liver indices in patients with NAFLD fail to improve in the face of appropriate body weight reduction.