Objective
In this project, we aim to comprehensively define the landscape of antigens targeted by T cells in NOD mice and T1D patients. We will use a novel T cell antigen discovery method developed by our lab, combined with high throughput TCR cloning methods, to define the antigens that are targeted by T cells that infiltrate the pancreatic islets. The overall approach is:
1) Use high throughput cloning methods to catalog TCRs derived from CD4+ helper and CD8+ cytotoxic T cells from the pancreatic ilsets of NOD mice and T1D patients.
2) Build large antigen discovery libraries presenting thousands of antigens derived from published protein profiling datasets.
3) Perform antigen discovery screens using the catalogued TCRs to determine the antigenic landscape and discovery novel antigens
4) Perform mechanistic studies to understand how targeting specific antigens affects the function of T cells in T1D.
Background Rationale
Type 1 Diabetes (T1D), affects 1.6 million individuals in the United States, with the disease burden projected to increase to 5 million individuals by 2050. Despite an estimated $1.6 billion in healthcare costs, less than a third of T1D patients have controlled blood glucose levels (source: Juvenile Diabetes Research Foundation). In T1D patients, insulin production is irreversibly diminished due to the progressive destruction of pancreatic beta cells. T1D onset is difficult to predict, and frequently, patients have progressed too far to restore tolerance by the time a diagnosis is made. The current standard of care is lifelong administration of insulin coupled with constant monitoring of blood glucose levels, which can result in either escalating healthcare costs, secondary complications, or non-compliance. Immune-focused interventions such as antigen-specific restoration of tolerance to islet antigens represent a promising strategy for the prevention of T1D. However, immune interventions need to be applied before significant loss of beta cell mass occurs. The lack of a comprehensive definition of therapeutically relevant antigens and early disease biomarkers has limited these immune-focused approaches. In this proposal, we will use innovative approaches to identify the antigens recognized by T cells in T1D.
Description of Project
Type 1 Diabetes (T1D) is caused by the destruction of Insulin-producing pancreatic beta cells by a patient’s own immune system. In T1D patients, immune cells known as T cells, infiltrate the pancreatic islets, and destroy beta cells. In a healthy human immune system, T cells are ‘educated’ in the thymus to tolerate any self tissue. However, in T1D, this tolerance is lost, leading to autoimmunity. T cells recognize protein antigens presented on the surface of beta cells, which is crucial for their ability to mediate beta cell killing. T cells are equipped to recognize antigens using their surface T cell receptor (TCR). Each T cell has a unique TCR that recognizes a distinct antigen with high specificity. Therefore, to understand why T cells behave abnormally in T1D and to develop therapies that prevent their abnormal behavior, it is critical to know which antigens they recognize. We know several antigens, such as Insulin, that are targeted by T cells. However, the antigens recognized by the majority of T cells in T1D are unknown. This has been due to a lack of efficient approaches for antigen discovery. Our laboratory has developed an efficient method, called SABR libraries, to ‘fish’ for antigens from large pooled libraries. In this project, we propose to use SABR libraries to comprehensively identify the antigens recognized by T cells in T1D. We will perform these studies in a mouse model of T1D, NOD mice, as well as in T1D patients. We aim to uncover novel self-antigens targeted by T cells and define the landscape of antigen recognition. By identifying the landscape of antigens targeted by T cells, we aim to understand the mechanisms of disease development better, to develop antigen-specific immune therapies, and to develop diagnostic biomarkers for catching autoimmunity early.
Anticipated Outcome
Through these studies, we will identify novel auto- and neo-antigens in T1D in NOD mice and in human T1D patients. We anticipate being able to comprehensively define which antigen are targeted in Type 1 Diabetes. These studies will enhance our understanding of the immune mechanisms in T1D, inform the development of antigen-specific interventions, and lead to novel diagnostic markers of T1D.
Relevance to T1D
Type 1 Diabetes (T1D), affects 1.6 million individuals in the United States, with the disease burden projected to increase to 5 million individuals by 2050. Despite an estimated $1.6 billion in healthcare costs, less than a third of T1D patients have controlled blood glucose levels (source: Juvenile Diabetes Research Foundation). In T1D patients, insulin production is irreversibly diminished due to the progressive destruction of pancreatic beta cells. Immune-focused interventions such as antigen-specific restoration of tolerance to islet antigens represent a promising strategy for the prevention of T1D. However, immune interventions need to be applied before significant loss of beta cell mass occurs. The lack of a comprehensive definition of therapeutically relevant antigens and early disease biomarkers has limited these immune-focused approaches. In this proposal, we will use innovative approaches to identify the antigens recognized by T cells in T1D. These studies will enhance our understanding of the immune mechanisms in T1D, inform the development of antigen-specific interventions, and lead to novel diagnostic markers of T1D.