Gastroenterology & GI Physiology
Andreas J. Baumler, PhD
SOM: Medical Microbiology and Immunology (see also: Immunology, Microbiology)
I am a microbiologist interested in the interaction of enteric pathogens with their hosts. We use mouse models to study Salmonella pathogenesis and host response. The main goals of this work are to interrogate mechanisms that enable typhoidal Salmonella serovars, such as Salmonella typhi, to evade innate immune recognition and mechanisms that enable non-typhoidal Salmonella serovars, such as Salmonella typhimurium, to take advantage of the host inflammatory response to edge out competing gut microbes. Furthermore, we use day-of-hatch chickens to investigate how Salmonella enteritidis colonizes the infant gut. We are also interested in how the gut microbiota confers colonization resistance against Escherichia coli and other commensal Enterobactericeae and in understanding the pathogenesis of colonic crypt hyperplasia caused by Citrobacter rodentium in mice, which is an animal model for infection with enterohaemorrhagic E. coli (EHEC).
Please visit Dr. Baumler's website for more information.
Lars Eckmann, M.D.*
Affiliated with UC Veterinary Medical Center – San Diego
Dr. Eckmann investigates the cellular and molecular pathogenesis of infections with enteric pathogens and the mechanisms underlying the regulation of intestinal inflammation. His studies employ animal models of intestinal infection and inflammation and apply molecular, microbiological and histological approaches to elucidate the key genes and cellular and molecular mechanisms that govern intestinal host defenses against enteric pathogens and regulate inflammatory responses in the gastrointestinal tract. Current studies define host defense mechanisms against the protozoan pathogen Giardia and the bacterial pathogens Escherichia coli and Salmonella.
Please contact Peter Ernst pernst@ucsd.edu or Christina Sigurdson csigurdson@ucsd.edu first for more information.
Peter Ernst, D.V.M., Ph.D.
Affiliated with UC Veterinary Medical Center – San Diego
Director of the Center of Veterinary Sciences and Comparative Medicine Director of the Division of Comparative Pathology and Medicine
Co-Director of UCVMC
Professor of Pathology, UC San Diego
Professor of Pathology, Microbiology, and Immunology, UC Davis
Our general research interests are in the area of comparative (human to mouse) mucosal immunology with specific projects in immune-epithelial cell interactions involved in the microbial pathogenesis of acute and chronic diseases of the gastrointestinal tract. Our current emphasis is on the role of adenosine as an anti-inflammatory mediator and how it protects from disruption in the microbiota that trigger disease.
Link to Dr. Ernst’s current publications
Link to Dr. Ernst’s website
Please contact Dr. Ernst for more information: pernst@ucsd.edu
Melanie Gareau, Ph.D.
Microbiota-gut-brain axis
VM: Anatomy, Physiology and Cell Biology
Dr. Gareau is a physiologist primarily interested in studying the microbiota-gut-brain axis. It is increasingly being recognized that the microbes that live the gastrointestinal tract, collectively referred to as the intestinal microbiota, can contribute to modulating cognition and mood. The research focus of her laboratory is in determining how manipulating the microbiota within the gut, using models of infection with bacterial pathogens or administration of beneficial probiotic bacteria, can change cognitive function, anxiety, and depression-like behaviors in mouse models of disease. Dr. Gareau has a particular interest in how the microbiota-gut-brain axis responds to stimulation with psychological stressors and under conditions of intestinal inflammation, such as in models of inflammatory bowel disease (IBD). Ongoing projects in the laboratory include studying behavior in mouse models of IBD and following pathogenic E. coli infection.
If interested, please contact Dr. Gareau: mgareau@ucdavis.edu
Maria Marco, PhD
Microbiota, obesity, IBD, prebiotics, probiotics
Department of Food Science & Technology
My research focuses on the roles of dietary and intestinal microorganisms in obesity and inflammatory bowel diseases. We are employing pre- and probiotic components to study the interactions between bacteria and the host that influence immune and metabolic function. The overarching goal of the research is to define the ecological basis and molecular mechanisms by which beneficial microorganisms contribute to maintaining good health. Examples of research projects include: application of pre-clinical models to evaluate the benefits of pre/probiotics to prevent pre-diabetic states or IBDs, the molecular analysis of host responses to probiotic bacteria and prebiotic fermentable dietary fiber; application of genetic analysis to investigate the function of specific probiotic Lactobacillus secreted factors in maintaining intestinal homeostasis; intestinal microbiome assessments using high-throughput DNA sequencing methods.
Dr. Marco can be reached via email at mmarco@ucdavis.edu.
Please visit Dr. Marco’s website for more information.
Stanley Marks , BVSc, PhD, Dip. ACVIM (Internal Medicine, Oncology), Dip. ACVN
VM: Medicine & Epidemiology
Dr. Marks is a veterinary gastroenterologist and nutritionist who runs the Companion Animal Gastrointestinal Laboratory. His research group have been characterizing enteric bacteria (Clostridial species, Campylobacter jejuni, Salmonella spp.) and protozoa (Giardia, Cryptosporidium, Tritrichomonas foetus) associated with diarrhea in dogs and cats, and evaluating diagnostic tests and therapeutic strategies to eradicate the organisms. Dr. Marks is also actively involved in research involving esophageal motility disorders and gastroesophageal reflux (GER), using high-resolution manometry (HRM), esophageal pH/impedance, videofluoroscopy swallow assessment, and esophagoscopy. His laboratory has multiple ongoing studies evaluating the effects of motility modifiers, acid suppressants, and anti-inflammatories on esophageal motility and GER.
Potential STAR projects for 2024 include:
- Evaluation of the effects of fecal microbiota transplantation for canine atopic dermatitis
- Evaluation of Esophageal Transit of Radiopaque Capsules in Healthy Dogs and Dogs with Acquired Idiopathic Megaesophagus
- Validation of a fecal scoring chart for kittens
Please contact Dr. Marks via email for more information
Sina Marsilio, Dr. med. vet., PhD, DACVIM (SAIM), DECVIM-CA
VM: Medicine and Epidemiology
(see also: Genetics and Genomics, Microbiology/Parasitology)
I am a small animal internist with a special clinical and research focus in small animal gastrointestinal diseases. My current research focuses on the intestinal microbiome and its disruption during acute and chronic intestinal diseases. In addition, I am currently launching several projects on the use of fecal microbiota transplantation as a therapeutic tool for intestinal disease. I am also actively involved in translational research using stem cells in animals with gastrointestinal disease. I am looking forward to mentor students with an active interest in small animal gastrointestinal and translational research and who would like to be involved in clinical research projects.
Please email Dr. Marsilio for more information: smarsilio@ucdavis.edu
Jon Ramsey, Ph.D.
Associate Professor
My research focuses on energy metabolism as it relates to obesity and aging. Calorie restriction, without malnutrition, is the only intervention that has consistently been shown to increase maximum life span in mammalian species. My research is investigating possible mechanisms for the retardation of aging with calorie restriction. In the area of obesity, my research focuses on the role alterations in energy expenditure play in either assisting or opposing weight loss. Also, I am interested in preventing obesity in companion animals by better determining the energy requirements of cats and dogs.
Dr. Ramsey can be reached via email at jjramsey@ucdavis.edu.
Helen Raybould
VM: Anatomy, Physiology & Cell Biology
My research interest focuses on neurobiology of the gastrointestinal tract. The overall goal of the research is aimed at understanding that mechanism by which neurons that innervate the gut are activated in response to luminal stimuli such as nutrients and how these mechanisms may be altered in disease such as obesity, inflammation and irritable bowel disease. We use a number of different techniques including integrative physiological measurement of GI function, neurotransmitter receptor expression and localization, cell culture and measurement of secretion from endocrine cells, electrophysiological experiments to record nerve activity.
Dr. Raybould can be reached via email at heraybould@ucdavis.edu.
Colin Reardon, Ph.D.
Immunology, IBD, T1D (see also: immunology)
VM: Anatomy, Physiology, & Cell Biology
Dr. Reardon is an immunologist specializing in the regulation of immunology. He is particularly interested in the mechanisms of communication between the nervous and immune systems. Although thought of as disparate fields of study, these two systems have co-evolved and are now appreciated to influence each other. Dr. Reardon’s research focuses on the modification of immune outcomes by neurotransmitters, and on the recently discovered production of the neurotransmitter acetylcholine (Ach) by B- and T-cells. Dr. Reardon’s research has previously identified that the commensal microbiota is involved in the regulation of Ach production by these immune cells. . Various projects are currently ongoing in the laboratory that will seek to establish the role of specific neurons in modulating immunopathologies, including inflammatory bowel disease and diabetes. Based on this, testing of small molecule agonists, and neurostimulator devices (in collaboration with biomedical engineers) to modulate immunopathologies will be performed in the laboratory. To accomplish this a variety of complementary techniques will be used including flow cytometry, confocal and intravital microscopy.
If interested, please contact Dr. Reardon creardon@ucdavis.edu.
Jesus Rivera-Nieves, M.D.*
Affiliated with UC Veterinary Medical Center – San Diego
Dr. Rivera-Nieves works on the pathogenesis of Crohn’s disease. Leukocytes of the granulocytic, monocytic and lymphocytic lineages are active participants in the chronic inflammatory process. Their recruitment from the circulation is regulated by adhesion molecules and chemokine receptors interacting with their respective ligands expressed or presented by intestinal endothelia cells. These adhesive interactions represent attractive therapeutic targets for the modulation of the destructive chronic inflammatory process. Proof of concept for the viability of this strategy has been provided by the efficacy of natalizumab, which interferes with integrin alpha-4-VCAM-1, MAdCAM-1 interactions. Using novel murine models of Crohn’s-like ileitis, Dr. Rivera-Nieves has continued to explore potential molecules that may be targeted, within the leukocyte recruitment cascade.
Please contact Peter Ernst pernst@ucsd.edu or Christina Sigurdson csigurdson@ucsd.edu first for more information.