Nitika Gupta

Glucagon-like peptide-1 receptor is present on human hepatocytes and has a direct role in decreasing hepatic steatosis in vitro by modulating elements of the insulin signaling pathway.

Glucagon‐like peptide 1 (GLP‐1) is a naturally occurring peptide secreted by the L cells of the small intestine. GLP‐1 functions as an incretin and stimulates glucose‐mediated insulin production by pancreatic β cells. In this study, we demonstrate that exendin‐4/GLP‐1 has a cognate receptor on human hepatocytes and that exendin‐4 has a direct effect on the reduction of hepatic steatosis in the absence of insulin. Both glucagon‐like peptide 1 receptor (GLP/R) messenger RNA and protein were detected on primary human hepatocytes, and receptor was internalized in the presence of GLP‐1. Exendin‐4 increased the phosphorylation of 3‐phosphoinositide‐dependent kinase‐1 (PDK‐1), AKT, and protein kinase C ζ (PKC‐ζ) in HepG2 and Huh7 cells. Small interfering RNA against GLP‐1R abolished the effects on PDK‐1 and PKC‐ζ. Treatment with exendin‐4 quantitatively reduced triglyceride stores compared with control‐treated cells. Conclusion: This is the first report that the G protein–coupled receptor GLP‐1R is present on human hepatocytes. Furthermore, it appears that exendin‐4 has the same beneficial effects in vitro as those seen in our previously published in vivo study in ob/ob mice, directly reducing hepatocyte steatosis. Future use for human nonalcoholic fatty liver disease, either in combination with dietary manipulation or other pharmacotherapy, may be a significant advance in treatment of this common form of liver disease. (HEPATOLOGY 2010)

NASPGHAN Practice Guidelines: Diagnosis and Management of Hepatitis C Infection in Infants, Children, and Adolescents

Hepatitis C virus (HCV) is an RNA virus that affects >180 million individuals worldwide with a high propensity for chronic infection. Children with HCV infection differ from adults in several ways including some modes of transmission, rates of clearance, progression of fibrosis, and the duration of potential chronic infection when acquired at birth. Since the discovery of HCV in 1989, there have been significant advances in the understanding of the virology and natural history of chronic HCV infection in children. In addition, there are now several treatment options for children with chronic hepatitis C infection and many new therapies on the horizon. As a consequence, the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition brought together experts in pediatric hepatology to review the available data in children and provide clinicians with approaches to the diagnosis, management, and prevention of HCV infection in children and adolescents. The guideline details the epidemiology and natural history of HCV infection in children, the diagnostic workup, monitoring and treatment of disease, and provides an update on future treatment options and areas of research.

Adiponectin activation of AMPK disrupts leptin‐mediated hepatic fibrosis via suppressors of cytokine signaling (SOCS‐3)

Adiponectin is an adipocytokine that was recently shown to be anti‐fibrogenic in hepatic fibrosis. Leptin, on the other hand, promotes hepatic fibrosis. The purpose of the present study was to elucidate a mechanism (or mechanisms) whereby adiponectin dampens leptin signaling in activated hepatic stellate cells (HSCs), and prevents excess extracellular matrix production. Activated HSCs, between passages 2 and 5, were cultured and exposed to recombinant human adiponectin and recombinant leptin. Immunoblot analysis for SOCS‐3, TIMP‐1, and the phosphorylated species of Stat3 and adenosine monophosphate‐activated protein kinase (AMPK) were conducted. We also examined MMP‐1 activity by immunosorbant fluorimetric analysis. In HSCs, adiponectin‐induced phosphorylation of AMPK, and subsequently suppressed leptin‐mediated Stat3 phosphorylation and SOCS‐3 induction. Adiponectin also blocked leptin‐stimulated secretion of TIMP‐1, and significantly increased MMP‐1 activity, in vitro. To extend this study, we treated adiponectin knockout mice (Ad−/−) daily with 5 mg/kg recombinant leptin and/or carbon tetrachloride (2 ml/kg) for 6 weeks. Post‐necropsy analysis was performed to examine for inflammation, and histological changes in the Ad−/− and wild‐type mice. There was no significant difference in inflammation, or aminotransferases, between mice receiving carbon tetrachloride and leptin versus carbon tetrachloride alone. As anticipated, the combination of leptin and CCl4 enhanced hepatic fibrosis in both wild‐type and Ad−/− mice, as estimated by amount of collagen in injured livers, but wild‐type mice had significantly higher levels of SOCS‐3 and significantly lower levels of TIMP‐1 mRNA and protein than did adiponectin KO mice exposed to both CCl4 and leptin. We therefore conclude that the protective effects of adiponectin against liver fibrosis require AMPK activation, and may occur through inhibition of the Jak‐Stat signal transduction pathway. J. Cell. Biochem. 110: 1195–1207, 2010. Published 2010 Wiley‐Liss, Inc.

Mitigation of autophagy ameliorates hepatocellular damage following ischemia-reperfusion injury in murine steatotic liver

Ischemia-reperfusion injury (IRI) is a common clinical consequence of hepatic surgery, cardiogenic shock, and liver transplantation. A steatotic liver is particularly vulnerable to IRI, responding with extensive hepatocellular injury. Autophagy, a lysosomal pathway balancing cell survival and cell death, is engaged in IRI, although its role in IRI of a steatotic liver is unclear. The role of autophagy was investigated in high-fat diet (HFD)-fed mice exposed to IRI in vivo and in steatotic hepatocytes exposed to hypoxic IRI (HIRI) in vitro. Two inhibitors of autophagy, 3-methyladenine and bafilomycin A1, protected the steatotic hepatocytes from HIRI. Exendin 4 (Ex4), a glucagon-like peptide 1 analog, also led to suppression of autophagy, as evidenced by decreased autophagy-associated proteins [microtubule-associated protein 1A/1B-light chain 3 (LC3) II, p62, high-mobility group protein B1, beclin-1, and autophagy-related protein 7], reduced hepatocellular damage, and improved mitochondrial structure and function in HFD-fed mice exposed to IRI. Decreased autophagy was further demonstrated by reversal of a punctate pattern of LC3 and decreased autophagic flux after IRI in HFD-fed mice. Under the same conditions, the effects of Ex4 were reversed by the competitive antagonist exendin 9-39. The present study suggests that, in IRI of hepatic steatosis, treatment of hepatocytes with Ex4 mitigates autophagy, ameliorates hepatocellular injury, and preserves mitochondrial integrity. These data suggest that therapies targeting autophagy, by Ex4 treatment in particular, may ameliorate the effects of IRI in highly prevalent steatotic liver.

Invasive intracranial pressure monitoring is a useful adjunct in the management of severe hepatic encephalopathy associated with pediatric acute liver failure

Objective: Pediatric acute liver failure is often accompanied by hepatic encephalopathy, cerebral edema, and raised intracranial pressure. Elevated intracranial pressure can be managed more effectively with intracranial monitoring, but acute-liver-failure-associated coagulopathy is often considered a contraindication for invasive monitoring due to risk for intracranial bleeding. We reviewed our experience with use of early intracranial pressure monitoring in acute liver failure in children listed for liver transplantation. Design and Patients: Retrospective review of all intubated pediatric acute liver failure patients with grade III and grade IV encephalopathy requiring intracranial pressure monitoring and evaluated for potential liver transplant who were identified from an institutional liver transplant patient database from 1999 to 2009. Interventions: None. Measurements and Main Results: A total of 14 patients were identified who met the inclusion criteria. Their ages ranged from 7 months to 20 yrs. Diagnoses of acute liver failure were infectious (three), drug-induced (seven), autoimmune hepatitis (two), and indeterminate (two). Grade III and IV encephalopathy was seen in ten (71%) and four (29%) patients, respectively. Computed tomography scans before intracranial pressure monitor placement showed cerebral edema in five (35.7%) patients. Before intracranial pressure monitor placement, fresh frozen plasma, vitamin K, and activated recombinant factor VIIa were given to all 14 patients, with significant improvement in coagulopathy (p < .04). The initial intracranial pressure ranged from 5 to 50 cm H2O; the intracranial pressure was significantly higher in patients with cerebral edema by computed tomography (p < .05). Eleven of 14 (78%) patients received hypertonic saline, and three (22%) received mannitol for elevated intracranial pressure. Eight of 14 (56%) monitored patients were managed to liver transplant, with 100% surviving neurologically intact. Four of 14 (28%) patients had spontaneous recovery without liver transplant. Two of 14 (14%) patients died due to multiple organ failure before transplant. One patient had a small 9-mm intracranial hemorrhage but survived after receiving a liver transplant. No patient developed intracranial infection. Conclusions: In our series of patients, intracranial pressure monitoring had a low complication rate and was associated with a high survival rate despite severe hepatic encephalopathy and cerebral edema in the setting of pediatric acute liver failure. In our experience, monitoring of intracranial pressure allowed interventions to treat increased intracranial pressure and provided additional information regarding central nervous system injury before liver transplant. Further study is warranted to confirm if monitoring allows more directed intracranial pressure therapy and improves survival in pediatric acute liver failure.

Undifferentiated Embryonal Sarcoma of the Liver is Associated with Mesenchymal Hamartoma and Multiple Chromosomal Abnormalities: A Review of Eleven Cases

Undifferentiated embryonal sarcoma (UES) of the liver is a primitive mesenchymal, malignant neoplasm occurring in children. The link between UES and mesenchymal hamartoma (MH) is controversial. Whether they share the same histiogenesis, representing 2 ends of a spectrum, or are distinct entities is unclear. The genetic aberrations of these neoplasms are not well understood, although a common breakpoint (19q13.4) was recently identified. The purpose of this study was to elucidate immunohistochemical markers that may establish a link between the 2 tumors by reviewing cases of UES and MH. Cases of UES from 1990 to 2008 were identified. Clinical demographics were reviewed. Hematoxylin and eosin staining and immunohistochemical staining for vimentin, alpha-1 antitrypsin, and alpha-fetoprotein were performed. Eleven children were diagnosed with UES. Five cases were seen arising in association with MH, and transitional zones were evident. The mean age at presentation was 10 years. To our knowledge, the 11-month-old patient is the youngest reported case of UES in concurrence with MH. All UES tumor cells were positive for vimentin, diastase-resistant periodic acid–Schiff stain, and alpha-1 antitrypsin. Chromosomal analysis of 3 UES cases, 2 arising with MH, showed complex karyotypes with no involvement of 19q13.4. We suggest a continuum between UES and MH. Although a chromosomal anomaly of 19q13.4 was not identified, a submicroscopic involvement of this locus cannot be excluded. Additionally, our analyses suggest that multiple chromosomal aberrations may be associated with the MH/UES spectrum.

Pediatric hepatopulmonary syndrome is seen with polysplenia/interrupted inferior vena cava and without cirrhosis

Hepatopulmonary syndrome (HPS) is a triad of liver dysfunction, hypoxemia, and intrapulmonary vascular dilatation. We describe the prevalence and clinical features of HPS at a pediatric liver transplant center. Patients referred to Childrens Healthcare of Atlanta/Emory University transplant program from February 1999 to May 2005 were reviewed. Oxygen saturation in room air was screened by percutaneous pulse oximetry. HPS cases were compared with similar age non‐HPS recipients (n = 38) to determine differences in clinical characteristics, Pediatric End‐Stage Liver Disease (PELD) scores, and posttransplantation survival. Of 211 patients referred and 114 patients transplanted, 7 met criteria for HPS (3.3% and 6.1%, respectively). Patients with HPS had lower PELD score (−0.4 ± 5.9 vs. 11 ± 11; P = 0.01) and total bilirubin (1.7 ± 1.1 vs. 11.2 ± 10.1; P = 0.02) at the time of transplantation. Four of 7 patients with HPS had polysplenia/interrupted inferior vena cava (PS/IVC) compared with 0 of 38 age‐matched controls (P = 0.0002). Three patients with HPS did not have cirrhosis; 2 of these 3 had PS/IVC. All HPS cases normalized room air oxygen saturation by 6 months, and survival after transplantation in HPS cases was 100%. Marked hepatic synthetic or biochemical dysfunction may not be present, and cirrhosis is not a requirement for the development of HPS in children. HPS in children is frequently associated with PS/IVC. Histologic evidence of abnormal intrahepatic portal vein flow and the demonstration of portosystemic communications at any level should be sought in children presenting with unexplained intrapulmonary vascular dilatation. Liver transplantation for HPS in childhood may be appropriate even in the absence of cirrhosis. Liver Transpl 13:680–686, 2007.

The glucagon-like peptide-1 receptor agonist Exendin 4 has a protective role in ischemic injury of lean and steatotic liver by inhibiting cell death and stimulating lipolysis.

Nonalcoholic fatty liver disease is an increasingly prevalent spectrum of conditions characterized by excess fat deposition within hepatocytes. Affected hepatocytes are known to be highly susceptible to ischemic insults, responding to injury with increased cell death, and commensurate liver dysfunction. Numerous clinical circumstances lead to hepatic ischemia. Mechanistically, specific means of reducing hepatic vulnerability to ischemia are of increasing clinical importance. In this study, we demonstrate that the glucagon-like peptide-1 receptor agonist Exendin 4 (Ex4) protects hepatocytes from ischemia reperfusion injury by mitigating necrosis and apoptosis. Importantly, this effect is more pronounced in steatotic livers, with significantly reducing cell death and facilitating the initiation of lipolysis. Ex4 treatment leads to increased lipid droplet fission, and phosphorylation of perilipin and hormone sensitive lipase - all hallmarks of lipolysis. Importantly, the protective effects of Ex4 are seen after a short course of perioperative treatment, potentially making this clinically relevant. Thus, we conclude that Ex4 has a role in protecting lean and fatty livers from ischemic injury. The rapidity of the effect and the clinical availability of Ex4 make this an attractive new therapeutic approach for treating fatty livers at the time of an ischemic insult.

The natural history of primary sclerosing cholangitis in 781 children: A multicenter, international collaboration

There are limited data on the natural history of primary sclerosing cholangitis (PSC) in children. We aimed to describe the disease characteristics and long‐term outcomes of pediatric PSC. We retrospectively collected all pediatric PSC cases from 36 participating institutions and conducted a survival analysis from the date of PSC diagnosis to dates of diagnosis of portal hypertensive or biliary complications, cholangiocarcinoma, liver transplantation, or death. We analyzed patients grouped by disease phenotype and laboratory studies at diagnosis to identify objective predictors of long‐term outcome. We identified 781 patients, median age 12 years, with 4,277 person‐years of follow‐up; 33% with autoimmune hepatitis, 76% with inflammatory bowel disease, and 13% with small duct PSC. Portal hypertensive and biliary complications developed in 38% and 25%, respectively, after 10 years of disease. Once these complications developed, median survival with native liver was 2.8 and 3.5 years, respectively. Cholangiocarcinoma occurred in 1%. Overall event‐free survival was 70% at 5 years and 53% at 10 years. Patient groups with the most elevated total bilirubin, gamma‐glutamyltransferase, and aspartate aminotransferase‐to‐platelet ratio index at diagnosis had the worst outcomes. In multivariate analysis PSC–inflammatory bowel disease and small duct phenotypes were associated with favorable prognosis (hazard ratios 0.6, 95% confidence interval 0.5‐0.9, and 0.7, 95% confidence interval 0.5‐0.96, respectively). Age, gender, and autoimmune hepatitis overlap did not impact long‐term outcome. Conclusion: PSC has a chronic, progressive course in children, and nearly half of patients develop an adverse liver outcome after 10 years of disease; elevations in bilirubin, gamma‐glutamyltransferase, and aspartate aminotransferase‐to‐platelet ratio index at diagnosis can identify patients at highest risk; small duct PSC and PSC–inflammatory bowel disease are more favorable disease phenotypes. (Hepatology 2017;66:518–527).

The SPLIT research agenda 2013.

This review focuses on active clinical research in pediatric liver transplantation with special emphasis on areas that could benefit from studies utilizing the SPLIT infrastructure and data repository. Ideas were solicited by members of the SPLIT Research Committee and sections were drafted by members of the committee with expertise in those given areas. This review is intended to highlight priorities for clinical research that could successfully be conducted through the SPLIT collaborative and would have significant impact in pediatric liver transplantation.