Lay Summary
Proposal No. IBD-0094
Principal Investigator: Victor M. Morales, Ph.D.
Current Applicant Organization: University of Rochester (New York, U.S.A.)
Original Applicant Organization: Boston University Medical Center (Massachusetts, U.S.A.)
Project Title: Peptides recognized by T cell clones from inflammatory bowel disease patients
Period of Award: February 1, 2004 – September 30, 2006
Crohn’s disease is an inflammatory bowel disease (IBD) of unknown etiology. We know, however, that one of the components of the immune system that overreacts to intestinal microbial proteins in IBD is T cells. The T cells recognize and react to pieces of microbial proteins (peptides) through specialized receptors called T cell receptors (TCRs). The identification of the peptides recognized by the T cells will help us not only to understand the mechanisms of the initiation and maintenance of the disease, but also to devise therapies for it.
One of the problems in doing research with human intestinal T cells is that they are difficult to reproduce in quantities large enough for experimentation. We plan to circumvent this problem by producing a combination of human-mouse TCRs in a mouse cell line with enormous capacity for long-term growth. These reconstructed TCRs will behave identically to those found in diseased intestines of CD patients. These mouse cells bearing a reconstructed human TCR will be exposed to human cells that have each been treated with a pool from a positional scanning synthetic combinatorial peptide library (PS-SCL). This library will contain synthetic versions very similar or identical to most, if not all, peptides found in the human intestine. The effect of the peptides will be assessed by measuring the production of Interleukin-2 (IL-2), a small protein that immune cells produce when stimulated by the right peptide. Analysis of the scores of IL-2 production for all the pools in the library will yield the sequence of the optimal stimulating peptide for a particular clone of T cells. The findings will be confirmed by retesting the particular T cell clone for activation by a synthetic peptide with the predicted amino acid sequence. Searches of public protein sequence libraries will identify those that contain portions similar to the activating peptide; these will be candidates for the source of the activating peptide. Knowing which peptides activate the T cells will help in the design of ways to block them from causing inflammation and, perhaps, to achieve long term remission of this devastating inflammatory bowel disease.