Objective
Despite decades of research, no drugs targeting disease associated cellular protein functions are available to treat type 1 diabetes. Apart from the mainstream treatment of insulin injection, other previous approaches to treat the disease involve invasive approaches such as surgical supplementation of insulin producing beta cells from a deceased donor or injection of antibodies against T cells. Our objective was to find a novel therapeutic target and non invasive approach to treat autoimmunity, the root cause of type 1 diabetes. We found a novel molecular mechanism in which high glucose increases sugar modification of a protein called c-Rel and alters its activity that may promote T cell-mediated autoimmunity. The c-Rel protein act as key regulator of autoimmunity in diabetes and is a leading pharmaceutical target. However, drugs that inhibit total c-Rel protein will elicit broad side effects. Hence, specific targeting of only the sugar modified c-Rel protein holds the potential for therapeutics with minimal side effects and high specificity to treat diabetes. Based on this, the major objective of this study is to develop the first-of-its kind compounds targeting sugar modified c-Rel as a potential break-through approach to control autoimmunity. We are proposing to design compounds called peptoids, a class of chemicals similar to short protein fragments, with the ability to enter the cells and show high stability in body fluids, enabling longer life and activity as drugs. We already have developed a lead compound and are generating additional ones to study their effects in type 1 diabetes patient’s cells and mouse model of autoimmune diabetes. This objective is expected to yield drugs that have the potential to reach clinical trials as first non-invasive long-sought-after oral medication for type 1 diabetes, which is the most child-friendly route of drug administration.
Background Rationale
The etiology of type 1 diabetes remains unknown. Several anecdotal evidences relates the origin to a viral or bacterial infection triggering T cell mediated immune response, which when remains uncontrolled, diverts toward attacking self tissue, a phenomenon called autoimmunity. These self reactive T cells kill beta cells in the body that produce insulin. A commonly adopted treatment for type 1 diabetes is ciclosporin, an immunosuppressive agent targeting T cells, which delays the necessity for insulin injections. This suggests the existence of severe T cell immune reaction, which could be targeted to diminish autoimmunity. However, attempts to control T cell autoreactivity in general, have not yielded fruitful results thus far. Our studies show that high blood sugar increases the autoimmune functions of T cells through attachment of a sugar to the protein called c-Rel, changing its functions. Thus, once diabetes and hyperglycemia originates due to genetic or environmental reasons, it will increase the sugar modification of c-Rel protein. It plays a dual role in positively regulating the bad autoreactive T cell function and negatively regulating the good T regulatory cell function, that suppresses autoimmunity. This dual role of sugar modification of c-Rel protein may play a role in exacerbating autoimmunity and cause faster progression of the disease. Hence, blocking the function of sugar modified c-Rel protein is expected to suppress the progress of autoimmunity in type 1 diabetes. This is expected to decrease T cell mediated killing of beta cells, providing an environment for the survival of beta cells.
Description of Project
Type 1 diabetes (T1D) is a chronic, lifelong disease with approximately 80 people, predominantly children, diagnosed everyday in the United States. Past decade has seen a rise of 25% in the incidence of type 1 diabetes. Currently, more than 200,000 children in the U.S. are living with type 1 diabetes. According to U.S. Centers for Disease Control and Prevention estimates, this number is predicted to rise to 600,000 by 2050. The disease symptoms start as early as 10 days after birth and stay as a lifelong disease reducing life expectancy by 20%. The current health care costs associated with type 1 diabetes is ~$15 billion each year.
In T1D, specific white blood cells (B and T cells) in the immune system become self-reactive (a phenomenon called autoimmunity) and attack the insulin producing beta cells in the pancreas. Insulin is a hormone that controls blood sugar (glucose) levels, and without the appropriate level of insulin, patients develop high blood glucose levels and secondary complications such as blindness, nerve damage, renal failure and amputations. Knowledge of the root cause for T1D is limited, and despite decades of research, currently there is no cure available. Since 1920, the disease management strategy relies on exogenous insulin injections. Insulin over dose, incorrect timing or combination with other drugs such as aspirin can cause hypoglycemia leading to a coma and even death, especially in children. None of the other approaches to diminish autoimmunity offer promise, warranting urgent need of research to reveal new disease mechanisms to develop novel therapies to control autoimmunity in type 1 diabetes.
We discovered a novel mechanism promoting autoimmunity in T1D. We found that high glucose levels modify a protein called c-Rel in T cells through a biochemical process called O-GlcNAcylation. This process attaches a sugar residue called N-acetylglucosamine to the c-Rel protein and causes it to become hyperactive. This in turn, may drive the T cell to attack and destroy the beta cells needed to produce insulin. We also found that the increased sugar modification of c-Rel suppresses the production of a protein called forkhead box P3 (FOXP3), which controls the function of T regulatory (Treg) cells, another type of T cell that suppresses the self-reactivity of the T cells. Thus, the sugar modification of c-Rel has a dual role in type 1 diabetes; 1. Increase the activity of T cells to attack the beta cells, and 2. Decrease the activity of Treg cells that would normally stop T cell over-activity. Here we propose a unique approach to control this destructive autoimmune mechanism that exacerbates the progress of the disease. This new direction of our research focuses on targeting the sugar modified c-Rel protein using novel compounds called peptoids to block its function that promotes autoimmunity. This will prohibit or inhibit the subsequent beta cell destruction and represents a novel breakthrough approach to reverse or diminish autoimmunity in T1D. We already have developed a lead compound and performed proof-of-concept studies. We propose here to conduct further preclinical studies using T1D patient cells and mouse model of the diabetes. This study matches with the mission of JDRF, i.e. to study novel T1D mechanisms and develop new investigative methodologies and tools with future translational potential to treat T1D. Knowledge gained through this research has the future potential to lead to an oral medication, which to a great extent, will reduce the dependence of children with type 1 diabetes on exogenous insulin and improve their glucose control, mitigating needle tests and daily injections as well as long-term organ damage.
Anticipated Outcome
Based on our preliminary studies, we expect that blocking the function of sugar modified c-Rel protein will decrease the T cell mediated autoimmunity in type 1 diabetes. This project is unique because it proposes a drug development based on our new solid scientific discovery, which contributes to the disease severity. Because the mechanism is defined and the approach is not based on a hit or miss screening, we expect that the peptoids that we develop targeting sugar modified c-Rel (a) will function to decrease autoimmune functions in T cells isolated from type 1 diabetes patients and (b) will not affect normal health and function of other cells in the body. We expect to develop additional peptoids and validate them in dose response, toxicity, and cellular uptake assays as well as their specific effect to block sugar modified c-Rel function. This will generate variants of peptoids to improve their function than the lead compound. We expect to achieve successful inhibition of enhanced autoimmune function of diabetes patient’s T cells and in mouse model. We expect that the peptoid treatment will decrease the function of autoreactive T cells, increase the function of T regulatory cells, decrease the killing of pancreatic beta cells by autoreactive T cells and thereby block autoimmune diabetes in mice. We expect that successful completion of this study, will lead to the development of the first and long-sought-after oral therapeutic targeting a molecular mechanism associated with type 1 diabetes, holding the promise of a better life for children suffering from this incurable disease. Research based on peptoids as drugs is emerging and has never been explored before in the context of type 1 diabetes or autoimmunity and thus, this study is expected to be a break-through approach in type 1 diabetes treatment.
Relevance to T1D
Development of clinically successful therapeutics to diminish autoimmunity in type 1 diabetes is an urgent need to improve the lives of millions of children suffering from the disease and improve their later life with minimal or no secondary complications. This study discovered a novel mechanism in which attachment of a sugar to a protein called c-Rel promote autoimmunity in type 1 diabetes and that blocking the sugar modified c-Rel function suppress autoimmune T cell functions. We are conducting experiments using blood samples obtained from children with type 1 diabetes registered at our University Hospitals/Rainbow Babies and Children’s hospital. Current technologies enable identification of children at risk of developing type 1 diabetes by screening for genetic markers and autoantibodies in the blood. However, no strategy to block the progression of autoimmunity has been proved clinically successful to date. The options such as transplantation of insulin producing pancreatic beta cells requires a deceased donor and life-long immunosuppressive drugs to prevent rejection of foreign cells. However, such cell transfer is approved only for patients over 18 years of age, leaving children without a therapeutic option. Our approach to target sugar modified c-Rel using peptoids to limit self reactivity of T cells and promote T regulatory cell function offers a double-edged treatment to diminish autoimmunity. This will enable the survival of insulin producing beta cells. The peptoids may be formulated as an oral medication, the most child-friendly way to treat type 1 diabetes. This treatment holds the potential to prevent the progression of autoimmunity in children with new onset disease or decrease the severity of autoimmunity in children with established disease.
Once the preclinical studies are completed with this funding support, we will initiate clinical trials lead by physicians at Rainbow Pediatric Endocrine Division at University Hospitals, who has access to over 1000 children with type 1 diabetes.