Objective
The purpose of this grant is to improve immune-therapy for T1D by developing strategies that do not cause immune suppression, and do not require long-term depletion of immune cells. This grant is based on therapeutic strategies that have been adopted by the cancer field, in which a cancer cell is sensitized in a way that makes it more susceptible to death but leaves heathy cells unharmed. Autoreactive cells in T1D are under increased stress, and in T1D these cells have developed mechanisms to resist this stress that would otherwise delete them in individuals without T1D. This grant will dissect the pathways that can be targeted to reduce that resistance to stress and allow autoreactive cells to be deleted while allowing normal B cells to continue to develop unharmed.
Background Rationale
The proposed work in this grant is driven by two principles; 1) the immune system possesses its own mechanisms for preventing autoimmunity that do not inhibit normal immunity and 2) these mechanisms fail in autoimmunity and can be corrected. The development of approaches to strengthen these self-regulating mechanisms present attractive alternatives to long-term immune suppression therapy. B lymphocytes are key cell types that drive T1D and it is clear that their development is broken from the start. Even though it has been demonstrated that autoreactive B cells receive some instructive developmental signals in T1D, they seem to respond to this signal inappropriately. This grant hypothesizes that this inappropriate response is due to an increase in resistance to cellular stress that is mediated by reactive-oxygen species (ROS) that drives autoreactive cell deletion in people without T1D. This grant will determine what pathways are most important for creating resistance to ROS and target those pathways so the autoreactive B cells can again respond to these deletion signals in appropriate ways. This grant is novel in the approach as the therapeutic goal is not to deliver a compound that in and of itself is toxic to lymphocytes but rather to re-sensitize cells to the exquisite self-regulation processes that already exist. The work is based on therapeutically decreasing the resistance of developing cells to ROS in T1D to the same levels seen in B cells in healthy individuals. This approach will allow for cells to respond normally to signals that they receive during development. It should not harm the development of non-autoreactive B cells as their ROS burden is relatively lower. In all this approach will correct a broken pathway in B cell development and do so in a way that will not hamper or suppress normal immunity.
Description of Project
Curative therapy that does not permanently suppress the immune system is sorely needed in Type 1 Diabetes (T1D). B lymphocytes produce autoantibodies that reliably predict disease; these autoantibodies are evidence of collaboration between B lymphocytes and T lymphocytes that leads to destruction of islets in T1D. Therapies that deplete either B or T lymphocytes (Rituximab or Teplizumab, respectively) lead to temporary reversal of T1D only while the therapy is being given. After the therapy is stopped, T1D resumes. While we don’t know why T cell depletion (Teplizumab) doesn’t stably reverse T1D, studies with B cell therapy Rituximab suggest that this therapy depletes harmful cell mature B cells but does not prevent the development of new harmful cell B lymphocytes after treatment stops. In people without T1D these developing harmful (autoreactive) B lymphocytes receive signals during development to remove themselves from the immune system, often via deletion. In T1D autoreactive B lymphocytes respond incorrectly to these deletion signals and survive to maturity where they cause disease. These instructive signals lead to the production of Reactive-Oxygen Species (ROS) in autoreactive B lymphocytes. ROS boosts signals and cellular processes that promote autoreactive cell death. My studies indicate that autoreactive B cells in T1D have processes to resist and dampen the impact of ROS, and thus survive, a strategy that many cancers cells also adopt. Like cancer therapies have previously demonstrated, we will determine whether increasing the sensitivity of B cells to ROS will allow for removal of autoreactive cells in T1D. Importantly, we believe this strategy will spare developing healthy, non-autoreactive cells as they do not receive ROS-producing signaling during development. Overall we hope this project will determine how to target the production of ROS to boost the removal of disease-causing autoreactive B lymphocytes while leaving normal B lymphocytes to develop to maturity. This approach will provide a safe and efficacious way to overcome resistance to B cell targeting therapies in T1D.
Anticipated Outcome
I anticipate the aims in this grant will provide a pathway to prevent the reemergence of autoreactive B cells, a problem that hampers progress in current B cell-directed therapies in T1D. I will accomplish this by understanding how reactive oxygen species (ROS)-resistance promotes the survival of autoreactive cells. All the information discovered in this grant can be applied to develop new therapeutics or modify existing therapies for use in T1D. By the end of this project, I will define the pathways that contribute to ROS production in developing B cells and how these pathways are broken in T1D. I will also be able to define therapeutics that can increase ROS production in autoreactive B cells and develop tools that can be used clinically to define whether these therapies are successful in boosting ROS in B lymphocytes n T1D.
Relevance to T1D
This work has immediate relevance to T1D, as this proposal studies a previously unrecognized component of the autoimmune pathology. I will identify reactive-oxygen species (ROS) resistance pathways that contribute to the development and survival of autoreactive B cells in T1D. This will provide a new understanding to the mechanisms that cause T1D. This grant also seeks to mechanistically correct a problem that has become apparent in immune therapy in T1D, namely that depletion of B lymphocytes does not correct the broken development of B lymphocytes. This grant will couple the use of compounds that boost-ROS production with new strategies that allow us to determine the mechanistic impact of these drugs on immune cells. This means that dosage and treatment can be altered or customized to provide a strategy that will allow for the best possible outcome. Additionally, the fact that non-autoreactive cells experience relatively less ROS stress and thus shouldn’t be harmed by this therapeutic strategy makes this an ideal avenue of research for immune intervention in T1D. With renewed interest in a clinical trials using B cell depletion, it is important to understand the mechanistic reasons B cells are abnormal in T1D. This proposal will define those mechanisms and determine how they regulate the development of pathogenic autoreactive B cells in T1D. At the same time, these insights will advance a new therapy that may treat T1D without immune suppression, making immune therapy safer for long-term administration and for use during unexpected events like the current pandemic.