Immunosuppressive Neutrophils Modulate Alloimmune Responses After Lung Transplantation

Project Summary/Abstract This proposal outlines a 5-year research and career development plan to support Dr. Amit Bery’s transition to independence as a physician-scientist studying how innate immune cells affect adaptive immunity after lung transplantation. The proposed research project, which focuses on how interleukin-1β (IL-1β) promotes the differentiation, release, and trafficking of immunosuppressive neutrophils that downregulate alloimmune responses after lung transplantation, will take advantage of clinical and scientific expertise and unique resources available at Washington University School of Medicine. The proposed career development and training plan will strengthen Dr. Bery’s fund of knowledge and develop important skills in bioinformatics and advanced imaging techniques that will promote his successful transition to independence. Dr. Bery has generated preliminary data showing that recipients deficient IL-1β uniformly reject pulmonary allografts. These preliminary data show that IL-1β signaling is necessary for G-CSF release which results in an intragraft neutrophilia that is abrogated in IL-1β-deficient recipients. Dr. Bery has also shown that these graft infiltrating neutrophils express markers associated with an immunosuppressive phenotype and that these neutrophils can suppress T cell responses in vitro. The short-term goals of this proposal include evaluating mechanisms how IL-1β signaling induces the differentiation and release of these neutrophils from the bone marrow (Aim 1), and to define trafficking requirements that promote the homing of these neutrophils to pulmonary allografts (Aim 2). He will utilize the techniques of flow cytometry, histopathology, in vitro colony forming cell assays, and advanced downstream analyses of single cell RNA sequencing data (Aim 1) along with in vitro transmigration assays, flow cytometry, histopathology, and real-time intravital 2-photon imaging (Aim 2) to achieve these short-term goals. The long-term goal of this work is to develop immunosuppressive strategies that are tailored to the lung. While outcomes after lung transplantation rank the worst among all transplanted solid organs, immunosuppressive strategies for recipients of pulmonary allografts have been derived from studies in other organs, mainly kidney transplantation. Thus, there is a major need to identify lung-specific immunosuppressive strategies to improve the longevity of pulmonary allografts and overall survival after lung transplantation. As many lung transplant candidates and nearly all lung transplant recipients are treated with immunosuppressives that may limit their ability to mount an emergency myelopoietic response to transplantation, the proposed work carries the potential to influence how immunosuppression is utilized after lung transplantation and may provide new insights on the effects of therapies for lung transplant candidates on the waitlist.