Although the cause of IBD is not known, clinical observations have suggested that intestinal bacteria might trigger - and perhaps exacerbate - the inflammatory response. We have already shown that the total bacterial load in models of acute colitis is significantly higher than controls, suggesting the importance of bacteria. It would be more likely, however, that the pathogenesis of IBD is not associated with just one specific pathogen, but rather to bacterial products, some of which have already been detected in the gut of patients. What, then, is the role of bacteria and/or bacterial products in the pathogenesis of IBD? This is an important question that, as yet, remains unanswered.
PROJECTS
Our studies will address some of the key questions surrounding the involvement of Bacteria in the initiation and subsequent sustaining of inflammation; we are investigating the role of bacterial products, such as diarrhea. Secretory response and motility changes invoked by the bacterial peptide will be measured using colonic tissues mounted in specialized chambers. Effects on changes in the balance of the immune system will be ascertained by measuring cytokine levels and gene expression using RT-PCR and ELISA. Elucidation of these specific cellular pathways will help to solve the controversy over the effectiveness of antibiotics, probiotics and prebiotics in IBD. These studies may also identify new therapeutic targets.
This project utilizes many different techniques and the following equipment:
General procedures, animal model:
Scotsman ice machine, ductless fume hood FCR-1000, Elix 5, Water Purification System from Millipore, fixed angle Denver Microcentrifuge, Acculab analytical balance, high speed tissue homogenizer, -20 and -80 C º freezers.
Histological Procedures:
Histoembedder, Micron HM 340E Rotary Microtome, flotation bath, slide warmer, staining equipment, Trinocular light microscope.
Molecular Studies & ELISAs:
Eppendorf refrigerated centrifuge, PCR workstation, transilluminator, power supply and horizontal chamber for running agarose gels, Eppendorf Mastercycler gradient thermocycler, Dynex MRX revelation microplate reader. Access to multi-user RCMI Molecular Biology Core Facility.
Secretion Studies:
Binocular dissecting microscopes with dual illumination, Ussing chamber set-up consisting of 4 chambers, DVC 1000 2 channel amplifier/voltage/current clamp, 2-channel recorder, and heater-circulator pump.
Motility Studies:
Myobath 4 multi-channel tissue bath set-up consisting of transducers, baths, coil warmers, holders, and a TBM4M amplifier plus data acquisition system.
Other Research Projects being conducted within the Laboratory
The lack of a clinically relevant animal model which mimics the periods of remission and relapse seen in IBD has limited our understanding of the disease pathogenesis. A "reactivated" model of colitis is being used to investigate the role of various inflammatory mediators (supported by NIH-MBRS).
We are interested in ascertaining the underlying mechanisms involved in the motility changes associated with IBD and Irritable Bowel Syndrome (IBS), as well as the various secretory mechanisms that occur. This is important in understanding one of the major clinical symptoms - diarrhea. We are measuring regional variations in neurokinin receptor subtype contributions to muscularis mucosae and epithelial function in the rat colon, in both normal and inflamed tissue (chemicals donated by Sanofi-Synthelabo Recherche).
There is a great deal of overlap between the symptoms of IBD and endometriosis. This overlap often leads to misdiagnosis. We have established a model of intestinal endometriosis in rats in order to investigate the differences and similarities between endometriosis and IBD. More specifically, we are studying the role of TNF receptors and their associated signaling factors and adhesion molecules (supported by NIH-MBRS and an NIH predoctoral fellowship).
Colorectal cancers are the second leading cause of cancer-related deaths in USA. Patients with long term IBD have a significantly increased risk of developing colon cancer. Dysplasia in colitis is preceded by a long history of chronic inflammation. We are investigating the transition of inflammation to dysplasia and associated genetic mutations (supported by an NIH-predoctoral fellowship).
Anecdotal reports from local gastroenterologists have suggested that the incidence of IBD is increasing in Puerto Rico. We have carried out a cross-sectional epidemiological study which shows that the incidence and prevalence of IBD in Puerto Rico has risen over the last five years.
