Objective
Our objective is to establish an engineered cell therapy approach to oppose immune responses directed against biochemically modified beta cell proteins in Type 1 Diabetes. We have developed novel fluorescent reagents to visualize the harmful immune cells that recognize modified protein fragments from pancreatic beta cells and a custom pipeline for single cell analysis of self-reactive T cells to efficiently define their T cell receptor sequences. Once defined, these T cell receptor sequences can be inserted into recipient cell lines to confer the desired specificity. These cells can then be engineered to irreversibly exhibit regulatory functions that oppose autoimmune beta cell destruction. We hypothesize that cells engineered to target stress-related immune targets will preferentially home to inflamed islets to potently inhibit beta cell destruction where such activity is most needed. The result would be a potent cell therapy approach to re-establish and maintain self-tolerance.
Background Rationale
Type I diabetes is an disease in which the insulin-producing cells of the pancreas are recognized and destroyed by immune cells due to inappropriate recognition of self-proteins. Recent studies demonstrate that self-proteins undergo enzymatic modification that is triggered by inflammation and cellular stress and that such modifications can trigger immune recognition. These processes have been shown to play important roles in other autoimmune diseases and accumulating evidence supports their importance in T1D. Work by our group and others demonstrates that subjects with Type 1 Diabetes have increased immune recognition of modified proteins from their pancreatic beta cells. A key pathway that has the potential to oppose inappropriate self-reactive T cell respnses and restore tolerance is the activity of regulatory T cells. Recently published work by our collaborators demonstrates that a dual editing strategy allows development of engineered regulatory T cells with enforced expression of a T cell receptor that targets a beta-cell pattern and a master regulator protein (FoxP3) that confers a stable regulatory program. The resulting cells were shown to have potent immunosuppressive function, enforcing robust regulation of autoreactive T cells. This combined knowledge positions us to develop stable engineered regulatory cells with the ability to enforce self-tolerance in inflamed islets.
Description of Project
The Development of type 1 diabetes is caused by T cell mediated destruction of insulin producing beta cells. Beta cell stress and injury contribute to disease progression by initiating unfavorable changes that decrease its function and increase immune recognition. We have identified specific biochemically modified proteins that form within insulin producing beta cells. This collaborative project seeks to identify specific T cell receptor sequences that preferentially recognize stress-modified beta cell proteins and to leverage these to develop an engineered cell therapy capable of halting the progression of type 1 diabetes. We will utilize culture based assays and single cell approaches to identify relevant T cell specificities and to determine corresponding T cell receptors. We will re-express those receptors in cell lines, verify their specificity and function, and then apply gene editing approaches to irreversibly confer a regulatory phenotype. Finally, we will perform in vitro and in vivo screens to quantify the regulatory function of these engineered regulatory T cells and assess their ability to home to the pancreas and oppose beta cell destruction. Based on those findings we will identify lead candidates to advance toward the development of a cell-based clinical therapeutic.
Anticipated Outcome
We expect to defince stress related neo-epitopes and corresponding T cell receptors that result in T cell trafficking to inflamed islets. Implementing a duel editing stratety will then allow us to target engineered regulatory cells to enforce self-tolerance in inflamed islets. We further expect to develop effective engineered T cells corresponding to multiple self-epitope specificities, allowing us to compare their relative capacity to suppress immune attack of stressed β-cells. The end result of this work will be the establishment of multiple engineered Tregs that can be advanced toward clinical application.
Relevance to T1D
Self-destructive immune responses are key contributors to the development and pathogenesis of Type 1 Diabetes. These immune responses accelerate over time, eventually destroying the insulin producing cells of the pancreas. In some subjects, the onset of diabetes can occur rapidly, necessitating a rapid and effective intervention. The proposed research would develop a new engineered cell therapy deigned to potently oppose the self-reactive immune responses that destroy insulin producing beta cells, targeting their activity where it is needed most. Because this work will utilize blood samples and cell lines from human subjects, the results will be immediately applicable to human disease. A successful outcome would confirm that this cell engineering approach can effectively oppose beta cell destruction and would support further clinical development of this potentially transformative therapeutic strategy. The ultimate goal would be to translate this idea ito clinical practice to halt disease progression in at risk subjects and as an adjunct to beta cell replacement, resulting in a longterm restoration of insulin secretion.