Basic Science Track

The Gastroenterology Basic Science Research Training Program at the University of North Carolina at Chapel Hill is designed to promote the development of promising MD and PhD postdoctoral fellows as independent investigators and future university faculty members who will investigate the pathogenesis of gastrointestinal and hepatic diseases. Training of the postdoctoral fellow is individualized, and the most important component is conducted by the trainee in the faculty mentor’s laboratory. Additional training includes didactic courses, seminars and conferences, and seminars on responsible conduct of research.

Overview

The training faculty consists of 27 funded investigators from 11 basic science and clinical departments at the University of North Carolina, who are all full-time members of the NIDDK-funded Center for Gastrointestinal Biology and Disease (CGIBD). These broadly based faculty members have a documented history of close interactions promoting multidisciplinary research. The postdoctoral fellows benefit from the unique strengths of digestive disease research at the University of North Carolina, which include the CGIBD with its research cores, a research-oriented Pediatric Gastroenterology Division, a coordinated research training program, animal models of digestive diseases, outstanding programs in gastrointestinal epidemiology and biostatistics, a Gene Therapy Center, and a Center for Alcohol Studies.

The program is funded by an NIH T32 Training Grant on which R Balfour Sartor, MD serves as Program Director and Susan J. Henning, PhD serves as Associate Program Director. The program recruits 1 to 2 new fellows each year from a pool of MD adult gastroenterology fellows, MD pediatric gastroenterology fellows, PhD postdoctoral fellows, and individuals holding DVM degrees.

For those individuals who wish to apply to our basic science program and who are not pursuing our basic science fellowship program as part of our general MD fellowship program through the Match, please provide CV, one page description of prior research experience, half page explanation of career goals, and three letters of reference including one from your prospective mentor to Dr. Balfour Sartor at rbs@med.unc.edu and Nancy Rohr at nancyr@med.unc.edu.  This information will be reviewed by our Training Program Advisory Committee. Candidates offered a position will be assigned a primary research mentor. To ensure safe arrival of all application materials, we strongly urge interested individuals to send information electronically.

Minorities are encouraged to apply. To be eligible for Training Grant support, applicants must be U.S. citizens or permanent residents.

Training Faculty

Ramon Bataller, M.D., Associate Professor, Medicine (GI) and Nutrition (School of Public health) and his group have been studying the mechanisms of alcoholic liver disease. Dr. Bataller´s research current research focuses on the molecular mechanisms of alcoholic hepatitis in order to identify new targets for therapy. Dr. Bataller is the overall PI of an NIH-funded international consortium to study alcoholic hepatitis (InTeam). Moreover, he belongs to the Bowles Center for Alcohol Studies. In the last years, Bataller´s team has identified several molecular driers of alcoholic hepatitis that can represent new targets for therapy (i.e. osteopontin, Fn14, CCL20, CXC chemokines). Moreover, they have developed the first histological classification of alcoholic hepatitis (AHHS). Currently, Dr. Bataller´s efforts are focused on identifying molecular signatures in patients with alcoholic hepatitis that predict response to therapy. He is building a large biorepository of livers from patients with alcoholic hepatitis linked with clinical data. By performing RNA deep sequencing and kinome analysis, Bataller´s team is trying to develop a molecular classification of these patients that can be used for a personalized medicine.

Albert Baldwin, Ph.D., Professor, Biology, Lineberger Cancer Center, studies the signaling pathways that activate the transcription factor NF-κB and the roles that NF-κB plays in promoting inflammation and cancer. The laboratory is studying mechanisms whereby oncogenic K-Ras activates NF-κB and the roles that NF-κB plays in driving Ras-induced oncogenesis. The laboratory has a particular interest in the involvement of inflammation in promoting cancer. Dr. Baldwin has worked extensively with Dr. Ting and comentored with Dr. Sartor.

Anthony Blikslager, DVM, Ph.D., Professor, Surgery and Gastroenterology, School of Veterinary Medicine, N.C. State University, explores mechanisms of repair of the small intestinal inter-epithelial tight junction. As a DVM/ PhD, he exposes trainees to the most appropriate models available to answer their hypotheses. Dr. Blikslager trained as a physiologist and combines state of the art molecular and genetic techniques with timehonored techniques such as the Ussing chamber. Following initial emphasis on repair of ischemic injury, he has studied other mechanisms of epithelial recovery following events such as stress and chemical injury (bile and acid). Future research plans will include microbial injury and associated inflammation, followed by studies of facilitating repair. Mentoring is augmented by graduate coursework at NC State University in gastroenterology, immunology, cell biology, genetics, and statistics.

Ian Carroll, PhD, Research Assistant Professor, Gastroenterology, School of Medicine (UNC). The goals of my research are to determine the mechanisms through which specific members of the intestinal microbiota influence gastrointestinal physiology, adiposity, and behavior. My laboratory has developed and validated techniques to collect and store biological human and murine samples for microbiological analyses. We have also developed a technique for isolating bacterial DNA from human fecal and colonic mucosal samples. Our research team characterizes the intestinal microbiota in human and murine biological samples and analyzes the resulting data using the Quantitative Insights Into Microbial Evolution (QIIME) pipeline. Our laboratory currently investigates the mechanism(s) by which enteric microbial communities lead to inflammatory bowels diseases (IBD) and adiposity and behavior dysregulation in anorexia nervosa (AN). Our experiments involve (i) collection and storage of human and murine fecal material in an appropriate manner for analyzing the intestinal microbiota; (ii) colonizing germ-free (GF) mice with enteric microbes; (iii) isolating fecal DNA and subsequent characterization of the intestinal microbiota via high-throughput sequencing of the 16S rRNA gene; and (iv) analysis of the resulting enteric microbiota data. Our investigations have the potential to direct how to test adjunct interventions in IBD and AN with pre-, pro-, anti-, or syn-biotics to enhance current approaches to improve treatment outcome in these illnesses.

Rosalind Coleman, MD is an expert in research related to children born with genetic problems in metabolizing carbohydrates and lipids, as well as those with abnormally high lipid levels in the blood. She studies lipid metabolism, particularly triacylglycerol biosynthesis and fatty acid metabolism in liver, heart, adipose and skeletal muscle. She is particularly interested in understanding the controls on triacylglycerol synthesis and acyl-CoA partitioning, processes linked to diabetes and obesity. Using recombinant forms of enzymes, knockout mice (mice bred with inactivation of specific genes), and cell culture models, members of her lab are identifying the control mechanisms that explain how acyl-CoAs, a group of fatty acid metabolites, are directed into the mitochondria for energy production or stored in lipid droplets as complex lipids. Her studies of knockout mice have provided strong evidence that insulin resistance in the liver is caused by glycerolipid intermediates that impair insulin signaling. An additional interest is the question of why specific enzymes of glycerolipid synthesis increase when cells become cancerous.  

Christopher Dekaney, Ph.D., Assistant Professor, Surgery, explores mechanisms that control intestinal stem cell proliferative status following damage. Recent improved understanding of how intestinal stem cells are controlled under homeostatic conditions indicate that there is exquisite control of entry and exit of intestinal stem cells into and out of the cell cycle under normal conditions. In contrast, very little is understood about how intestinal stem cells are controlled during intestinal stress such as following surgical resection or mucosal damage. He uses a model of chemotherapy-induced mucosal damage to study the response of intestinal stem cells during epithelial repair. His primary focus is to understand how fibroblast growth factors (FGF) mediate epithelial repair, and specifically what effects these factors have on intestinal stem cells. Expression of FGFs is transiently upregulated during repair and these FGFs can signal through one or more of the four FGF receptors. He uses in vivo and in vitro approaches to delineate the function of two of the FGF receptors (receptors 1 and 2) during repair. In other systems FGF receptor 1 activation promotes increased proliferation while FGF receptor 2- activation promotes cell survival and differentiation. Understanding how these receptors and their ligands function in promoting intestinal epithelial repair has significant clinical implications as both FGF-7 and FGF-10 (palifermin and repifermin, respectively) are used as treatments for chemotherapy-induced mucositis. 

J. Victor Garcia-Martinez, Professor, Medicine (Infectious Diseases), explores lymphocyte migration into effector tissues like the gut, which is the result of a series of poorly understood but highly complex interactions between cell adhesion molecules, integrins, chemokines, and chemokine receptors. He has investigated the migration of human lymphoid cells into the gastrointestinal tract of immunodeficient mice. Specifically, he uses bone marrow/liver/thymus (BLT) humanized mice. In BLT mice, the bone marrow is reconstituted with human hematopoietic stem cells producing all human lymphoid lineages resulting in systemic repopulation. In addition, bone marrow–derived T cell progenitors are produced that repopulate an implanted human organoid consisting of a piece of autologous fetal liver and thymus resulting in human MHC-restricted functional T cells. Results demonstrate the high degree of compatibility between the mouse and human systems that results in the appropriate repopulation of the mouse gut tissue with human lymphoid cells. For the most part, the reconstituted BLT gut clearly resembles human gut descriptions in the literature. Perhaps the most telling features were the presence of human CD4CD8αα cells, a T cell subset known only to exist in GALT, and the presence of abundant Peyer's patches in the small intestine and lymphoid follicular aggregates in the large intestine localized with human lymphocytes (T and B), macrophages, and DCs. In addition, human lymphocytes (T and B), macrophages, and DCs are found distributed throughout the effector lamina propria in humanized BLT mice suggesting that these mice have largely “normal human” GALT. Based on the remarkable similarities observed between the GALT of BLT mice and humans, we are in the process of testing humanized BLT mice as a model to study key aspects of human mucosal immunology and GALT development.

Ajay Gulati, M.D., Associate Professor, Pediatrics (GI), is focused on understanding interactions between the commensal microbiota of the gut and the host epithelium, particularly in the context of chronic inflammatory conditions such as IBD. Specifically, he is interested in determining how various susceptibility genes for IBD affect the structure and composition of the intestinal microbiota. His current work explores the influences of the IBD risk allele NOD2 on the intestinal microbiota. Using a NOD2 knockout mouse model, he is examining the effects of NOD2 deficiency on bacteria such as Faecalibacterium prausnitzii and Escherichia coli that have been implicated in the pathogenesis of human IBD. He is also studying possible mechanisms of this dysbiosis, such as alterations in antimicrobial peptide function in the NOD2-deficient mice. Finally, from a translational standpoint, he is assessing levels of relevant bacteria, particulary Faecalibacterium prausnitzii, Escherichia coli and Segmented Filamentous Bacteria in human tissue samples obtained from patients with different IBD genotypes and phenotypes. His hope is to identify patterns of dysbiosis in various subsets of IBD patients that will ultimately lead to patient-specific therapies for these disorders.

Jonathan Hansen, M.D., Ph.D., Assistant Professor, Medicine (GI). A widely accepted hypothesis is that inflammatory bowel diseases (IBD) are caused by overly-aggressive, T cell- mediated immune responses to bacterial products in genetically susceptible hosts. While the host response to bacterial products has been extensively studied, little is known about the subsequent effects of host inflammation on bacterial properties. Dr. Hansen’s overall goal is to determine how host-derived inflammatory factors affect commensal microbial physiology. He is dissecting these interactions using gnotobiotic IL-10-/- mice that develop chronic, immune-mediated colitis when selectively colonized with certain commensal bacteria such as E. coli NC101. He has shown that intestinal inflammation triggers NC101 to upregulate bacterial stressresponse genes, which help bacteria tolerate heat stress and potentially lethal levels of reactive oxygen species (ROS) such as those found in the inflamed intestine and macrophage phagolysosomes. He hypothesizes that the host inflammatory milieu upregulates bacterial stress response genes, which in turn allows bacteria to adapt to the environment and perpetuate inflammation by increasing their survival and virulence. He is testing this hypothesis using a variety of in vivo and in vitro approaches aimed at determining mechanisms by which the host communicates with these commensal microorganisms. Ultimately, these studies have the potential to reveal novel host-microbial interactions that could be targeted for therapeutic purposes.

Susan Henning, Ph.D., Professor, Medicine (GI) (Co-Director T32, Advisory Committee) is working to identify and characterize intestinal stem cells (ISC). The project is relevant to this training program because ISC play a central role in the ability of the small bowel to respond to various traumas such as resection, radiation, chemotherapy damage, etc. Although the presence of ISC has been inferred for many years, to date they have proven very difficult to isolate. Dr. Henning and colleagues have deployed a novel sorting approach in order to collect a “side population” of putative ISC and profiled the gene expression of this cell fraction by microarray. These studies together with high throughput in situ hybridization analyses identified new ISC markers which are being used to develop improved methods of isolation. Dr. Henning is currently exploring both in vivo graft models and in vitro culture models to assess the capacity of different ISC preparations for proliferation and differentiation. Ultimately the isolation and transplantation techniques developed in this project should have two applications: a) new therapies for various conditions in which the intestine is damaged; and b) use of the intestine as a site for gene therapy. 

Temitope Keku, Ph.D., Professor, Medicine (GI). Dr. Keku’s research involves translational research combining basic science with epidemiology to gain a better understanding of the etiology and pathogenesis of colorectal cancer. Her research interests are: genetic and molecular epidemiology of colorectal cancer; assessment of the contribution of genetic and non-genetic factors to colorectal cancer susceptibility; identification of germ-line or tumor characteristics associated with cancer risk and clinical outcomes (response to therapy and survival); identification of novel biomarkers for early detection to define risk groups for prevention; cancer health disparities; understanding the role of gut microflora in etiology of colorectal cancer. She is the lead PI of a NIH funded study investigating the role of the gut microbiota, inflammation and diet in colorectal cancer.

Stanley Lemon, M.D., Professor, Medicine (ID), Microbiology & Immunology (appointment 5/1/10) is a physician-scientist who is focused broadly on the molecular pathogenesis of acute and chronic hepatitis in humans due to hepatitis C virus (HCV) and hepatitis A virus (HAV). His research lies at the interface of molecular virology, innate immunity, inflammation and disease pathogenesis. His primary research interests include the molecular mechanisms by which these two hepatotropic viruses replicate their positive-strand RNA genomes, and how these viruses are recognized by host innate immune sensors. Dr. Lemon’s research aims to define how these viruses have evolved to evade innate antiviral defenses in the liver, and how these events influence the subsequent development of virus-specific adaptive immunity. Recent work has revealed how the HCV NS3/4A serine protease disrupts RIG-I and TLR3-mediated activation of IRF-3 and NF-κB, and how antiviral protease inhibitors counteract these effects. Recently, Dr. Lemon has discovered that two distinct processing intermediates of the HAV 3Cpro cysteine protease, 3ABC and 3CD, similarly disrupt interferon signaling, and is now interested in determining how these viral evasion tactics relate to the disparate outcomes of these two intra-hepatic virus infections. A parallel focus in his laboratory has been the interaction of HCV with cellular tumor suppressor proteins, including in particular the retinoblastoma tumor suppressor Rb, and how such virus-host interactions contribute to cell cycle dysregulation and hepatocellular carcinogenesis in chronic hepatitis C. A related focus of ongoing research is the interaction of HCV with the liver specific micro-RNA miR-122, itself a tumor suppressor, and the mechanism underlying HCV dependence on miR-122 for efficient genome amplification.

P. Kay Lund, Ph.D., Sarah Graham Kenan Professor, Cell and Molecular Physiology, Pediatrics and Nutrition (Executive Committee) has 25 years’ experience in the field of Physiology and Experimental Medicine with broad-based expertise in the areas of Gastroenterology, Molecular Biology, Nutrition, Endocrinology, Translational Research and Cancer Biology. Her laboratory has pioneered our understanding of the roles of the growth hormone/ insulin-like growth factor/ insulin axis in normal epithelial homeostasis, mucosal injury and repair and early stage development of cancer. A cross-discipline approach using cellular and molecular biology and mice with cell-specific deletion of components of this axis and downstream signaling molecules has permitted advances in understanding basic mechanisms of growth factor action and interaction, and translation to epidemiologic studies or clinical trials. Most recently Dr. Lund has made novel observations that suppressors of cytokine signaling (SOCS) serve as suppressors of growth factor signaling and sporadic or inflammation associated colon cancer in vivo. She is currently defining signaling molecules and gene targets that mediate SOC action and is exploring therapeutic SOCS mimetics. Dr. Lund is lead PI on 2 R01 grants from NIDDK, an R21, and grants from the North Carolina Biotechnology Center and University Cancer Research Fund, and coinvestigator on 2 other R01s and 2 U01 grants. She is leading a new initiative to use enzyme activated near infrared fluorescent (NIRF) probes to selectively and sensitively define different types of GI cancer or inflammatory lesions. Together with Dr. Helmrath, Dr. Lund has developed the first animal model of postsurgical intestinal inflammation and fibrosis. Her laboratory thus provides a rich environment for crossdiscipline basic and translational research. Dr. Lund is Editor in Chief of American Journal of Physiology GI and Liver and actively mentors trainees on all aspects of peer review.

Scott Magness, PhD, Gastroenterology, School of Medicine (UNC). Research focus is on elucidating genetic mechanisms underlying stemness and developing translational models to establish a finer understanding of stem cell-driven regeneration dynamics in homeostasis and injury. Using a combination of genetic mouse models and micro-frabricated bioengineered platforms, we are exploiting the self-renewal capacity and multipotency of ISCs to develop long-term ex vivo models of the intestine and colon with primary tissues. These biomimetic models offer new solutions for compound screening and cell-based therapies.

Edward Miao, MD, PhD, Assistant Professor, Microbiology and Immunology (UNC), The Miao lab studies how the innate immune system tells the difference between pathogenic bacteria as compared to bacteria that do not encode significant virulence factors. We have focused on the cytosolic sensors because many pathogens attempt to access the cytosolic compartment, either by toxins, type III secretion systems, or wholesale cytosolic invasion.  Amongst cytosolic sensors, the inflammasomes trigger IL-1b and IL-18 secretion as well as a unique form of cell death called pyroptosis. We previously demonstrated that pyroptosis is an innate immune defense mechanism in vivo, and are currently studying the molecular mechanisms in triggering this response.  We showed that the NLRC4 inflammasome specifically detects the activity of type III secretion systems, and this permits detection of Salmonella typhimurium in the intestinal tract.  However, S. typhimurium evades inflammasomes when it spreads systemically, which is a critical virulence trait; if S. typhimurium triggers inflammasome-dependent pyroptosis, it becomes avirulent. We have also found that caspase-11 specifically responds to cytosolic bacteria, and that this provides protection in vivo against cytosolic bacteria such as Burkholderia thailandensis and B. pseudomallei. However, hyperactivation of caspase-11 on a systemic level leads to sepsis and death.

Virginia Miller, Ph.D., Professor, Genetics and Microbiology and Immunology, uses Yersinia enterocolitica and Y. pestis as model systems to study bacterial pathogenesis. The long-term goals of her work are to understand the bacteria-host interaction at the molecular level to learn how this interaction affects the pathogenesis of infections, and to understand how these pathogens co-ordinate the expression of virulence determinants during an infection. To do this her laboratory uses genetic, molecular and immunological approaches, in conjunction with mouse models of infection. Projects in her lab have focused on understanding the regulation of virulence and using analysis of regulatory networks to help identify and then study new virulence determinants. Two such current projects include studies of the RovA regulon both in Y. enterocolitica and in Y. pestis (NIH AI052167), as well as studies of the chromosomally encoded type three secretion system (Ysa T3SS) of Y. enterocolitica (NIH AI063299). Regulation of the Ysa T3SS is complex and involves an unusual phosphorelay system; thus, recent collaboration with Dr. Bourrett has been helpful in moving this project forward. Other projects involve detailed analysis of the structure, mechanism of action and role in pathogenesis of a group of type V secreted proteins of Y. pestis – the Yaps (NIH U54 AI057157, NIH AI078930). Collaboration with Dr. Matt Redinbo’s laboratory in the Chemistry Department is underway to determine the crystal structure of a subset of the Yaps; this will be useful for future detailed structure-function analyses. Dr. Miller came to UNC-CH in 2008 as a Professor and Assistant Dean of Graduate Education. During her career she has trained 14 PhD students and 21 postdoctoral fellows (current and past), 2 masters students and 13 undergraduate students. New trainees will have the opportunity to study the molecular genetics and/or molecular pathogenesis of Y. Enterocolitica, an important enteric pathogen.

Roy Orlando, M.D., Distinguished Professor, Medicine (GI), focuses on the barrier and transport functions of esophageal epithelium, both squamous and Barrett’s specialized intestinal metaplasia, and how these functions serve to protect the epithelium from injury by luminal content, including acid-pepsin present within the gastroesophageal refluxate. He explores the pathogenetic mechanisms of gastroesophageal reflux disease and how Barrett’s epithelium serves as a protective adaptation against acid-peptic injury. The performance of this research is carried out in both animal (rabbit) and human esophageal epithelium using Ussing chambers (electrical and flux measurements), molecular (qRT-PCR, Western blots) and morphologic (immunohistochemistry, light and electron microscopy) techniques. The results of his studies continue to provide insights into the pathogenesis of reflux esophagitis and the means by which Barrett’s esophagus serves as an effective defense against acid-pepsin injury. Ongoing studies explore the ability of commensal bacteria to regulate esophageal mucosal defenses.

John Rawls, Ph.D., Associate Professor, Department of Molecular Genetics and Microbiology, Duke University, studies the vast and complex community of microorganisms (gut microbiota) that exerts a profound influence on our biology. The mechanisms by which gut microbes regulate distinct aspects of host biology are largely unresolved, and represent potential therapeutic targets for promoting and preserving human health. The overall objective of his research program is to exploit the transparency and genetic manipulability of the zebrafish to elucidate the mechanisms underlying evolutionarily-conserved host-microbe interactions in the intestine. The presence of a gut microbiota in mice results in a significant increase in body fat, caused by increased microbial digestion of dietary nutrients, and microbial suppression of intestinal transcription of Fasting-induced adipose factor (Fiaf/Angptl4). He finds that the zebrafish microbiota similarly stimulates nutrient digestion and suppresses fiaf expression in the intestinal mucosa. He is using transgenic reporter assays to identify discrete cis-regulatory elements at the zebrafish fiaf locus that mediate expression and microbial suppression in the intestinal epithelium. To facilitate testing the role of the zebrafish gut microbiota on fat storage, he has developed novel methods for visualizing zebrafish adipogenesis in vivo, and is using these methods to analyze zebrafish adipose tissue development as a function of microbial status. He has also identified individual bacterial species (e.g., Pseudomonas aeruginosa) that can recapitulate the effect of the normal microbiota on intestinal fiaf suppression. Efforts are now underway to test P. aeruginosa gene function on zebrafish fiaf expression. This knowledge would provide insights into the foundations of host-microbial mutualism in the intestine, and new strategies to control Fiaf levels and energy storage in humans.

R. Balfour Sartor, M.D., Distinguished Professor, Medicine (GI), Microbiology & Immunology, T32 Director, investigates mechanisms of gene-environment interactions between susceptible hosts, commensal bacteria and diet using genetically engineered rodents and defined bacterial species under gnotobiotic conditions. These studies investigate the role of endogenous IL-10 from antigen presenting cells in regulating innate and adaptive immune responses to commensal bacteria and mechanisms by which HLA B27 regulates APC and T cell responses to bacteria. He has demonstrated functional differences in various commensal E. coli strains that determine their ability to induce colitis in IL-10-/- mice, is identifying unique genes restricted to colitogenic E. coli strains and is selectively deleting these putative virulence genes in adherent/invasive E. coli to determine which bacterial genes mediate epithelial invasion, persistence within macrophages and induction of colitis. He is investigating mechanisms of intracellular and intraluminal bacterial killing by the host with defective function of NOD2 and IGRM using knockout mice. NOD2 and IGRM-1-mediated killing of luminal bacteria is being investigated by measuring differential expression of various antimicrobial peptides and altered commensal bacteria in KO mice. In addition, he is performing translational research with a consortium of institutions (Washington Univ., Mt. Sinai, U. Chicago, Mass. General, Mayo Clinic, Cedars Sinai) to determine the effect of NOD2 and ATG16L1 polymorphisms on enteric microbial composition in ileal biopsies from normal and Crohn’s disease patients. In addition, Dr. Sartor is investigating mechanisms by which dietary iron, aluminum, sucrose and fructose influence enteric microbiota composition and function and experimental colitis, providing insights that can be readily translated to human investigations.

Shehzad Z. Sheikh MD PhD, Assistant Professor of Medicine & Genetics. His research program focuses on the pathogenesis of the Inflammatory Bowel Disease (IBD), Crohn's disease and ulcerative colitis. In general terms, his laboratory seeks to understand how information is encoded and dynamically utilized in immune cells from healthy and disease prone intestines. They focus specifically on genes that regulate response to the bacteria that normally reside in our intestines. Many of these genes make products that regulate the immune system in the intestine. These products defend the intestine against the attack of foreign materials; such as bacteria that live in the intestine. Dr. Sheikh's group uses genome-sequencing technology to precisely identify regions throughout the genome that are potential ‘on’ or ‘off’ switches for these genes. There is a fine balance between the genes that produce inflammatory substances that are necessary to kill bacteria and genes that produce anti-inflammatory substances that are important to prevent damage to the intestine. If this balance between inflammatory and anti-inflammatory substance production in the intestine is disrupted, IBD may result. Dr. Sheikh's lab focuses on understanding how these important controllers of inflammation are turned on and off in IBD. They also study how inflammatory and anti-inflammatory signals impact disease severity, progression and response to therapy in individuals with IBD. This information has the potential to increase our understanding of causes of IBD (personalized medicine) and to contribute to the development of new treatments.

Rita Tamayo, Ph.D., Assistant Professor, Microbiology and Immunology, studies the molecular basis of intestinal colonization by Clostridium difficile and Vibrio cholerae. The mechanisms by which these human diarrheal pathogens interact with the host epithelium, a requisite step in establishing an infection, are poorly understood. The Tamayo laboratory aims to identify bacterial colonization factors that participate in adherence and determine how production of these factors is regulated during infection. In particular, the role of the intracellular signaling molecule cyclic diguanylate (c-di-GMP) in controlling production of candidate adhesins is being explored. Trainees use a combination of bacterial genetic, biochemical, animal modeling and other approaches to carry out this research. Ultimately, the characterization of the colonization mechanisms used by these pathogens may reveal preventive and therapeutic options for C. difficile and V. cholerae infections.

Jenny P.Y. Ting, Ph.D., Distinguished Professor, Microbiology & Immunology, focuses on the NLR (Nucleotidebinding domain, leucine-rich repeat containing) gene family that represents intracellular sensors of microbial and damage-associated molecular patterns. NLR proteins not only affect host response to pathogen infection, but are also known to affect inflammation and genetically-associated inflammatory disorders, such as Crohn’s disease, thus their impact on gastrointestinal disorders is enormous. Her recent work on the role of the NLR inflammasome on colitis and colitis-associated cancer (J. Exp. Med., epub, April 2010) shows that many more NLR genes are likely to affect gastrointestinal disorders.

Roland Tisch, Ph.D., Professor, Microbiology & Immunology, focuses on two aspects of T cell-mediated colitis. The first entails the development of immunotherapies that target colitogenic T cells for the treatment of intestinal inflammation. Currently, Dr. Tisch is assessing the efficacy of antibody-mediated CD4 and CD8 blockade. Secondly, efforts are ongoing to define the events that shape the repertoire of colitogenic T precursors. He has evidence that thymic production of colitogenic T precursors occurs in an age-dependent manner, and that in turn is regulated by temporal changes in the stimulatory capacity of thymic epithelial cells.

Paul Watkins, M.D., Professor, Medicine (GI), School of Pharmacy, and his group have been studying mechanisms that underlie rare but serious adverse reactions to medications, particularly idiosyncratic liver toxicity. Dr Watkins is founding director of the Hamner-UNC Institute for Drug Safety Sciences (IDSS), which offers outstanding training opportunities in basic and translational sciences. Examples of unique research and training opportunities utilized by the IDDS are two innovative mouse models: the Collaborative Cross and “humanized” mice. The Collaborative Cross, which is only available at UNC-Chapel Hill and NC State University, is a growing panel of inbred mice that mimic the genetic variation present in human patient populations. These mice should not only be able to identify drugs that would cause adverse events in rare patients, but also can be used to understand the fundamental reasons why these reactions occur. The “humanized mice” that are uniquely available in our region were developed by Dr. Lishan Su, a member of the LCCC at UNC-Chapel Hill, and contain both a human immune system and human liver. It is now known that toxic drug reactions often are caused by an abnormal immune  response to drug treatment, and it is possible to insert into these mice the immune systems from specific patients to directly study why they experienced adverse drug reactions. Notable accomplishments in the last year include demonstration that inbred mouse strains can be used to identify genetic determinants of adverse event susceptibility in man, identification of new biomarkers for drug induced liver injury in whole blood transcriptome and urine metabolome. Dr. Watkins also heads the steering and genetic committees of the Drug Induced Liver Injury Network, a national consortium of investigators studying mechanisms of idiosyncratic hepatotoxicity in response to commonly used medications. 

Steven Zeisel, M.D., Ph.D., Professor, Nutrition, School of Public Health (UNC) focuses on nutrients, especially choline, gene polymorphisms and liver function. His NIDDK grant explores how humans made deficient in choline develop fatty liver and hepatocyte apoptosis. He found that humans with SNP in a gene for choline biosynthesis or with a SNP in folate metabolism require more dietary choline. Also, he found that metabolomics profiling could identify individuals at baseline on normal diet who would develop fatty liver when deprived of choline. Currently he is determining whether individuals with biopsy proven fatty liver have increased incidence of SNPs on choline metabolism genes.

Stipends

The training program is funded by an Institutional National Research Service Award from the NIH. As such, the program abides by the rules established for these awards.

Stipends are established by the NIH. The current annual stipend for postdoctoral trainees is determined by the number of FULL years of relevant postdoctoral experience at the time of appointment. Relevant experience may include research experience (including industrial), teaching, internship, residency, clinical duties, or other time spent in full-time studies in a health-related field following the date of the qualifying doctoral degree.