Congratulations to the Pilot and Feasibility Awardees for the 2019-2020 cycle:
Hossam Abdelsamed, PhD – Research Assistant Professor, Starzl Transplant Institute
“Epigenetic effector programs of Allo-reactive memory CD8 T cells in liver transplant patients”
The life-saving standard-of-care therapy for end-stage liver diseases is liver transplantation. Although in humans the liver is considered a tolerogenic organ, patients still require immunosuppressive drugs post-transplantation. One of the challenges in solid organ transplantation is the persistence of allo-reactive memory CD8 T cells and their resistance to immunosuppressive drug treatment, which represents a major hurdle against tolerance induction. Hence, understanding the molecular mechanisms underlying the development and maintenance of allo-reactive memory CD8 T cells will help us to develop future therapeutic interventions to enhance tolerance in liver transplantation, specifically in patients with recurrent rejection from weaning of immune suppressive drugs. To this end, there is a critical gap in our knowledge of the molecular mechanisms, specifically DNA methylation regulating immune tolerance. For instance, what role does DNA methylation play in memory CD8 T cell effector function in stable versus rejecting liver grafts? Furthermore, what are the molecular events upstream of DNA methylation? Memory CD8 T cells are endowed by two main cardinal features: (1) maintenance of their effector function in the steady state and (2) a rapid recall response upon antigen re-exposure. However, it is still not completely understood what role epigenetics plays in regulating both functions in the context of liver transplantation and allo-immunity. The major goal of this proposal is to understand the role of DNA methylation in allo-reactive memory CD8 T cell effector function from liver transplant patients with stable versus rejecting grafts. We believe that the proposed research is significant because it will give us a new insight and advance our understanding towards the molecular mechanisms, specifically DNA methylation in regulating the development and maintenance of allo-reactive memory CD8 T cell effector responses in the context of liver transplantation.
Andres Duarte-Rojo, MD, DSc – Associate Professor, Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition
“EL-FIT: a virtual tool to promote physical activity in advanced liver disease”
Physical activity and exercise are of paramount importance in patients with advanced liver disease as they counteract muscle loss, deconditioning, and frailty. We have developed a novel smartphone application called EL-FIT (Exercise and Liver FITness) to facilitate exercise prescription to patients with advanced liver disease waiting for a liver transplant. EL-FIT includes educational and exercise videos tailored to the patient’s degree of liver disease and physical function, as well as features allowing a physical trainer to remotely monitor patients, provide feedback to them, and create an interactive exercising community. Also, EL-FIT allows investigators to create databases with patient’s physical activity information, specifically cadence (steps per day), heart rate, and sleep time, in order to facilitate future research. As part of this project, we aim to: 1) obtain feedback regarding the usability of EL-FIT considering both the liver transplant candidate and physical therapist perspective; 2) determine the reliability of data transferred from a physical activity tracker to EL-FIT database, when compared to the data transferred by a commercial vendor; 3) explore an app-based pictorial rate of perceived exertion as an alternative to define exercise intensity in advanced liver disease; and 4) capture new insights from liver transplant candidates and other stakeholders on how to design virtual behavioral/motivational therapy to include in a future version of the app. Data collected from this project will be used to design a confirmatory study on the utility of EL-FIT to improve frailty and muscle loss in liver transplant candidates. The ultimate aim is for EL-FIT to provide hepatologists with an easy, safe, and effective tool for exercise prescription.
Christian Fernandez, PhD – Assistant Professor, Pharmaceutical Sciences
“Asparaginase hepatotoxicity is lipolysis-dependent”
Asparaginase (ASNase) is one of the main drugs used to cure pediatric acute lymphoblastic leukemia (ALL). However, ASNase has been avoided in adult leukemia treatment regimens due to the high risk of liver toxicity. Nevertheless, recent studies using ASNase in young adults demonstrate nearly 2-fold higher survival rates relative to adult treatment regimens that do not include ASNase. Therefore, identifying strategies to mitigate the risk of ASNase hepatotoxicity are urgently needed and will lead to better adult ALL survival rates. The proposed work will elucidate the mechanism of ASNase fatty liver and lead to strategies preventing the drug-induced toxicity. This project can lead to better adult ALL survival rates by identifying strategies to safely incorporate ASNase during the treatment of adult ALL.
Zachary Freyberg, MD, PhD – Assistant Professor, Department of Psychiatry
“Dynamic GPCR & Wnt modulation of hepatic zonation”
The liver plays a central role in the regulation of systemic metabolism. The zonal compartmentalization of metabolic functions across the hepatic lobule is critical for optimal function. This zonation is also responsible for the functional heterogeneity of hepatocytes and their capacity to engage differential metabolic functions. Zone-specific differences in gene expression are essential for establishing and maintaining metabolic zonation. It was originally conjectured that environmental differences between the three zones (e.g., gradients of blood oxygenation, nutrients and toxins) were the primary drivers for shaping hepatic zonation. More recently, it was shown that Wnt/β-catenin signaling is a fundamental regulator of hepatic zonation. Wnt/β-catenin signaling is zone-dependent, increasing from zone 1 (periportal) to zone 3 (pericentral). While this control of zonation is well established, more recent findings are incompletely understood; namely, Wnt/β-catenin signaling is also dynamically altered in response to a myriad of extrahepatic inputs, including nutritional changes, infections, drugs, hormones or systemic metabolic disturbances (e.g., metabolic syndrome). This potential impact of the modulation of Wnt/β-catenin signaling on metabolic zonation has never been studied. There is increasing evidence that Wnt/β-catenin signaling is modulated by G protein-coupled receptors (GPCRs) and intracellular β-arrestin-2 signaling downstream of these receptors. We found that GPCR activation triggers β-arrestin-2 signaling, which subsequently diminishes Wnt/β-catenindependent gene expression – a signaling mechanism highly conserved across tissues and species. Together, these GPCR/β-arrestin-2 signaling mechanisms can dynamically modify Wnt/β-catenin-dependent changes in gene expression in a highly conserved manner. Consistent with this, glucagon signaling via the glucagon receptor (GCGR), a GPCR abundantly expressed in the liver, has been recently shown to both modulate expression of several genes that are also regulated by the Wnt/β-catenin pathway. We hypothesize that GPCRs signal via the β-arrestin-2-dependent pathway dynamically modulate Wnt/β-catenin-driven gene expression. We also propose that this GPCR-mediated regulation is sensitive to changes in metabolic states, such as fasting or feeding. To address these hypotheses, we will focus on GCGR and the β-arrestin-2 signaling in modulating Wnt/β-catenin-dependent gene expression and its relevance to dynamic changes in metabolic zonation produced by different metabolic conditions: fasting, fed and fasting-refed states. Improved knowledge of GPCR/β-arrestin-2 signaling will facilitate better understanding of the fundamental mechanisms regulating metabolic zonation. Furthermore, this work will lay the foundation for future studies illnesses that alter metabolic zonation, such as metabolic syndrome and NAFLD/NASH.
Sungjin Ko, DVM, PhD – Research Instructor, Department of Pathology
“Elucidating the therapeutic effect of Sox9 and/or YAP inhibition in intrahepatic cholangiocarcinoma”
Anita McElroy, MD, PhD – Assistant Professor, Department of Pediatrics, Division of Infectious Disease
“Hepatocyte tropism in RVFV pathogenesis”
Rift Valley fever virus (RVFV) is a mosquito-borne virus that causes human and livestock disease in Africa and the Middle East. Most humans experience a benign, self-limiting febrile illness; however, in a subset of infected individuals the disease can be severe and even fatal. In these cases, the main clinical disease manifestation is often an acute hepatitis consistent with the tropism of the virus for hepatocytes. For many years, scientists have used a mouse model of RVFV to study pathogenesis; however, this model does not accurately recapitulate human disease since it is 100% lethal following a very low infectious dose. We hypothesize that this marked difference in outcome between humans and mice following RVFV infection is the result of differences in human versus murine innate immunity. Therefore, we propose to study this at the level of the hepatocyte, since this cell type is the primary target of the virus. We will take both a broad unbiased transcriptomic approach as well as a directed approach that focuses on key findings from the literature suggesting that innate immunity determines outcome in human hosts. If successful, we will identify the pathways that make mice exquisitely susceptible to RVFV disease and those that are critical for preventing severe disease in humans. These data will be useful to scientists who wish to establish mouse models that faithfully recapitulate human disease as well as clinicians who seek to understand how they can intervene to prevent severe RVFV disease in humans.
Marlies Meisel, PhD – Assistant Professor, Department of Immunology
“Role of gut microbial-induced Nlrp3 inflammasome in spontaneous liver disease”
Chronic inflammatory liver disease is a major public health issue and is the 12th leading cause of death in the US. Despite major advances in the field, a clear understanding of which individuals are at risk to develop liver disease remains elusive and few effective therapies exist. Microbial factors are critical players in liver disease development, and gut bacterial translocation is associated with severe liver disease. Nlrp3 Inflammasome activation has been recognized to play a central role in the development of inflammatory liver disease. Epigenetic changes are associated with liver disease and cardinal signs of liver disease are observed in patients with myeloid malignancies. However, the factors that drive liver disease in humans with myeloid malignancies remain elusive, and the exact mechanisms remain to be addressed. Here we show that the deficiency of an epigenetic gene leads to the development of spontaneous inflammatory liver disease with a concomitant increase in hepatic Nlrp3 inflammasome activation. In ongoing studies we will test if Nlrp3 inflammasome activation is required, and will test whether therapeutic interventions may be sufficient to revert liver disease in mice deficient of this epigenetic regulator. Moreover, by using germ free mice we will test whether gut bacteria are required and will characterize the local hepatic microbiome.
Sadeesh Ramakrishnan, DVM, PhD – Assistant Professor, Department of Medicine, Division of Endocrinology and Metabolism
“Role of Zonal Dysregulation of Hypoxia Signaling”
Nonalcoholic fatty liver disease (NAFLD) encompasses conditions from simple steatosis to nonalcoholic steatohepatitis, which may progress to cirrhosis and hepatocellular carcinoma. In NAFLD, patients often present with a nonhomogeneous accumulation of triglycerides, especially in the pericentral region of the liver. Currently, the mechanism that drives azonal steatosis is not clear. Metabolic zonation of the liver is partly driven by oxygen gradient. Loss of hepatic zonation in NAFLD and pericentral steatosis is associated with aberrant activation of hypoxia signaling. Consistently, mice model with liver-specific activation of HIF, especially HIF-2α results in dyslipidemia, pericentral steatosis leading to spontaneous steatohepatitis. Inhibition of HIF-2α by genetic and pharmacological approach ameliorated hepatic steatosis. Our preliminary data shows that amelioration of steatosis via disruption of hepatic HIF-2α is associated with a significant decrease in the expression of fatty acid transporter CD36. Since NAFLD results in significant induction of liver hypoxia, we hypothesize that the temporal activation of HIF-2α in the pericentral region induces CD36 expression and thereby promotes hepatic steatosis. This proposal will determine the pathways regulated by temporal activation of HIF-2α and the critical role of HIF-2α-induced CD36 in zonal TG accumulation in NAFLD.
Physician-Basic Scientist Team Award
Reben Raeman, PhD – Assistant Professor, Department of Pathology, Division of Experimental Pathology
Jaideep Behari, MD, PhD – Associate Professor, Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
“Role of gut-liver axis in NASH pathogenesis”
Nonalcoholic steatohepatitis (NASH) is an advanced and progressive form of nonalcoholic fatty liver disease (NAFLD) afflicting 50 million people worldwide and over 16 million people in North America. An estimated one in six patients with NASH progress to cirrhosis, and recent evidence links NASH to a higher incidence of hepatocellular carcinoma. Hepatic inflammation and fibrosis are the key features of NASH, with fibrosis emerging as the single most important indicator of disease progression and mortality. The pathogenesis of NASH is complex and multifactorial, but inflammation is central to the initiation and progression of fibrosis in NASH. The specific mechanisms driving inflammation in NASH are not fully understood, but there is mounting evidence that gut-derived antigens are a significant factor. Providing experimental proof-of-concept, we recently demonstrated that mice susceptible to Western diet (WD)-induced loss of intestinal epithelial barrier develop severe NASH within eight weeks of feeding the WD relative to control mice which developed mild hepatic steatosis. These pathological changes in the intestinal epithelial barrier in these mice were triggered by gut dysbiosis and mucosal inflammation, facilitating translocation of gut bacterial endotoxin, a potent inducer of hepatic inflammation. Our central hypothesis that hepatic inflammation and fibrosis in NASH results from gut microbial translocation subsequent to intestinal barrier dysfunction which is triggered by diet-induced mucosal inflammation. We will test this hypothesis in a mouse model of progressive NAFLD, and in NASH patients.
Multidisciplinary Team Awards
PI: Amir Borhani, MD – Assistant Professor, Department of Radiology
“Application of deep learning for non-invasive assessment of liver fibrosis in patients with NAFLD”
Non-alcoholic Fatty Liver Disease (NAFLD) is a major cause of chronic liver disease worldwide and in the United States. Assessment of fibrosis in these patients has significant prognostic importance. Liver biopsy, which is considered the gold standard for evaluation of fibrosis, is invasive and costly. Non-invasive assessment of liver fibrosis based on cross sectional imaging is challenging. The purpose of this study is to design and train a deep neural network learning algorithm for assessment of liver fibrosis via prediction of liver stiffness. This algorithm can be used as a computer-aided diagnosis tool to help the radiologists achieve more accurate and more confident detection of significant fibrosis on cross sectional imaging studies. This project is designed as a retrospective proof-of-concept study of patients with NAFLD who had liver MRI with MR elastography sequence (an MRI-based method for grading tissue stiffness) and will serve as a pilot study for future large-dataset validation studies.
Vikrant Rachakonda, MD – Assistant Professor, Department of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
“Ultrasound Radiomics in Acute Alcoholic Hepatitis”
Alcoholic hepatitis (AH) is a leading cause of liver failure and mortality, and prognosis is poor due to a lack of effective therapies and prognostic tools. There is an unmet need for reliable, non-invasive markers of severity and prognosis in AH patients, who have high risk of complications with invasive liver biopsy. The overall goal of this proposal is to evaluate ultrasound-derived morphologic and elastographic biomarkers of disease severity and monitor treatment responses using artificial neural network approaches to data analysis (termed Radiomics). Our central hypothesis is that ultrasound can provide accurate parameters for assessment of AH to provide an entirely non-invasive approach to assess prognosis.