2022 JDRF Post-Doctoral Fellowship
BACKGROUND: Current treatment for type 1 diabetes (T1D) involves the injection of insulin to replace that which is lost from the destruction of insulin-producing pancreatic beta cells. While permitting individuals with T1D to survive, this therapy strategy tends to mimic the function of beta cells of non-diabetic subjects very poorly. Insulin therapy is dangerous and burdensome, requiring constant dosing decisions to prevent dangerous episodes of low or high blood sugar levels and long-term complications including heart disease, kidney failure, and blindness. Therefore, several decades of research have been performed in the pursuit of therapies to prevent the development of T1D altogether by blocking the immune cells responsible for the killing of beta cells. A few immune therapies have shown success in preventing continued beta cell damage in recently diagnosed T1D subjects by targeting the major subset of immune cells responsible for beta cell damage, T cells. Of these successful immune therapies, the most effective was low-dose anti-thymocyte globulin (ATG), which has been shown to promote the death of T cells. However, individual response to low-dose ATG is highly variable, with only a portion of subjects showing preservation of beta cell function after drug treatment. Importantly, those who show favorable responses to low-dose ATG treatment tend to also demonstrate enhanced drug action, as observed through increased T cell depletion by ATG. While genetic variations have previously been associated with response to similar therapies in the cancer field, it is unclear how genetic variants may impact efficacy of low-dose ATG therapy specifically.
OBJECTIVE: The objective of this proposal is to identify and validate the genetic variants responsible for altering individual response to low-dose ATG therapy. To address this goal, we will perform experiments to test our hypothesis that low-dose ATG efficacy may vary according to variants associated with expression of genes that alter the likelihood of T cell death upon exposure to ATG.
APPROACH: We will collect whole blood and isolate T cells from multiple human subjects prior to culturing with ATG as a means to model what occurs when a patient receives low-dose ATG treatment. Statistical tests will be performed to associate genetic variants observed in the subjects with levels of T cell death. To understand why certain variants are associated with altered T cell death in response to low-dose ATG treatment, we will monitor the activation of cell signaling pathways which regulate cell death. Lastly, we will induce mutations in T cells to interrupt the expression of genes nearby to variants of interest and repeat the previously described experiments to validate the impact of such genetic variants on T cell depletion by ATG.
ANTICIPATED OUTCOMES: The extent of low-dose ATG-mediated T cell death is expected to be associated with genetic variants affecting expression of genes involved in the various methods by which ATG kills T cells. These genetic variants are anticipated to translate to differing efficacy of low-dose ATG in T cell depletion and thus, beta cell preservation, in subjects with or at-risk for T1D who are treated with this drug. Our findings may also prove useful in organ transplantation and an immune-related form of anemia where ATG is already clinically used for prevention of transplant rejection and red blood cell depletion, respectively. Ultimately, the results of this work will allow for improved recruitment of subjects for future clinical trials and eventual enhancement of therapy decisions by physicians, by informing a strategy to predict who may benefit from low-dose ATG treatment in the prevention or suspension of T1D development.