Endogenous regeneration of the thymus is a crucial function that allows for renewal of immune competence following infection, shock, cytoreductive chemo- or radiation therapy and other causes of thymic injury. Thymic regenerative capacity diminishes with age and remains a poorly understood area. One of the major goals of this project is to elucidate the processes of endogenous thymic regeneration so that they may be exploited into clinically relevant strategies for immune rejuvenation. This is particularly relevan for recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT), who experience prolonged post-transplant T cell deficiency caused by cytoreductive conditioning and graft-versus-host disease (GVHD), which results in increased morbidity and mortality from infections and malignant relapse. Interleukin-22 (IL-22) is produced by T-helper (Th)17 cells and innate lymphoid cells (ILCs) and promotes innate immunity and homeostasis of epithelial cells in the intestines, lung and skin. We have found a novel role for IL-22 in the endogenous regeneration of thymic epithelial cells (TECs) after thymic damage. We found that IL-22 was redundant for steady-state thymopoiesis but following thymic damage a) absolute levels of IL-22 in the thymus were increased, b) IL-22 production by thymic ILCs (tILCs) was increased, c) IL-23 production by thymic dendritic cells (tDCs) was increased and could enhance IL-22 production by innate lymphoid cells, and d) IL-22 administration could enhance overall thymic cellularity and proliferation and survival of TECs. Our preliminary findings also suggest that IL-22 can affect T cell development as early as bone marrow (BM) hematopoietic stem and progenitor cells (HSPCs). Based on these findings, we hypothesize that (a) IL-22 plays an important role in endogenous T cell regeneration following thymic insult, (b) IL-22 promotes differentiation and commitment of HSPCs to the lymphoid lineage, and (c) IL- 22 can be utilized as a therapeutic strategy in the clinic to boost thymic function following immune depletion. Our proposal has the following aims: (1) To study the role of IL-22 in endogenous regeneration of thymopoiesis, (2) To study the role of IL-22 in pre-thymic lymphoid commitment and development, and (3) To study the potential for IL-22 administration to improve T cell reconstitution following allo-HSCT. The mechanistic and pre-clinical studies outlined in this proposal have the potential to define an important novel pathway in thymic regeneration, which could result in clinical approaches to enhance T cell immunity, not only for recipients of allo-HSCT, but also for individuals with T cell deficiencies due to aging (lymphoid atrophy), autoimmune diseases, infectious diseases, shock, radio- or chemo-therapy and radiation injury (nuclear accident or terrorism).
Despite being exquisitely sensitive to injury, the thymus (which is fundamental for the development of T cells and the immune system in general) is remarkably resilient in young healthy animals. Understanding the processes involved with this natural regeneration can help us overcome the barriers to repair imposed by age, infection, shock or repeated treatments of chemotherapy or radiation. This proposal aims to further investigate a new framework of natural thymic repair based on a recently identified cytokine, IL-22, and seeks to exploit this process as an innovative clinical strategy for immune regeneration.
|Staffas, Anna; Burgos da Silva, Marina; Slingerland, Ann E et al. (2018) Nutritional Support from the Intestinal Microbiota Improves Hematopoietic Reconstitution after Bone Marrow Transplantation in Mice. Cell Host Microbe 23:447-457.e4|
|Velardi, Enrico; Tsai, Jennifer J; Radtke, Stefan et al. (2018) Suppression of luteinizing hormone enhances HSC recovery after hematopoietic injury. Nat Med 24:239-246|
|Wertheimer, Tobias; Velardi, Enrico; Tsai, Jennifer et al. (2018) Production of BMP4 by endothelial cells is crucial for endogenous thymic regeneration. Sci Immunol 3:|
|Weber, Daniela; Jenq, Robert R; Peled, Jonathan U et al. (2017) Microbiota Disruption Induced by Early Use of Broad-Spectrum Antibiotics Is an Independent Risk Factor of Outcome after Allogeneic Stem Cell Transplantation. Biol Blood Marrow Transplant 23:845-852|
|Ito, Reiko; Hale, Laura P; Geyer, Susan M et al. (2017) Late Effects of Exposure to Ionizing Radiation and Age on Human Thymus Morphology and Function. Radiat Res 187:589-598|
|Shono, Yusuke; van den Brink, Marcel R M (2017) Empiric antibiotic use in allogeneic hematopoietic cell transplantation: should we avoid anaerobe coverage? Blood Adv 1:2325-2328|
|Matsuzawa-Ishimoto, Yu; Shono, Yusuke; Gomez, Luis E et al. (2017) Autophagy protein ATG16L1 prevents necroptosis in the intestinal epithelium. J Exp Med 214:3687-3705|
|Dudakov, Jarrod A; Mertelsmann, Anna M; O'Connor, Margaret H et al. (2017) Loss of thymic innate lymphoid cells leads to impaired thymopoiesis in experimental graft-versus-host disease. Blood 130:933-942|
|Staffas, Anna; Burgos da Silva, Marina; van den Brink, Marcel R M (2017) The intestinal microbiota in allogeneic hematopoietic cell transplant and graft-versus-host disease. Blood 129:927-933|
|Chaudhry, Mohammed S; Velardi, Enrico; Malard, Florent et al. (2017) Immune Reconstitution after Allogeneic Hematopoietic Stem Cell Transplantation: Time To T Up the Thymus. J Immunol 198:40-46|
Showing the most recent 10 out of 35 publications