Transplantation is the best therapy for end stage failure of many organs including kidney, heart and lungs. While short term outcomes of transplants are excellent, graft half-lives are suboptimal in large part because of chronic immune mediated injury. Our long term goal is to identify novel mechanisms of transplant injury so as to be able to apply them to develop therapuetic strategies to prolong transplant survival. Increasing evidence indicates that regulatory T cells (Tregs) could be harnessed to inhibit pathogenic anti-transplant immunity (in the absence of immune suppression) but mechanisms to accomplish this goal are hampered by inadequate understanding. Extending our previous work, our combined published and preliminary data demonstrate that complement components C3a and C5a (initially thought to be important only for innate immunity) signal via their receptors on both mouse and human Treg inhibiting induction, activation, and function whereas blockade markedly augments Treg induction, activation, function. To decipher the mechanistic connections between complement and Treg in transplantation we propose a series of studies using mouse and human cells and multiple in vivo transplant models in mice. We will use knockout and transgenic mice along with pharmacological inhibitors, blocking antibodies and knockdown technologies to a) determine the in vivo effects of C3aR/C5aR signaling on Treg in transplantation and b) To determine mechanisms linking C3aR/C5aR signaling with Treg induction and function. The expected outcomes are that we will delineate the effects of immune cell C3aR/C5aR signaling on the function of mouse Tregs in transplantation, define the molecular signaling pathways and mechanisms that explain the observed effects, and test how the murine findings translate to human Tregs. Together, the results are likely to identify novel and unanticipated immune mechanisms (innovation), and have a positive impact because they will provide new, mechanistic insight into Treg function and stability, and identify new therapeutic targets that have the potential to prolong transplant survival in humans.

Public Health Relevance

Immune mediated diseases including transplant rejection cause significant morbidity. Our studies will provide new information on how to control such immune responses in transplantation but the findings could be used to design therapies to treat T cell mediated autoimmune disease as well as to enhance protective immune responses, for example to infectious agents and or cancer (all relevant to the NIH mission)

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI071185-08
Application #
8881053
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Kehn, Patricia J
Project Start
2006-07-01
Project End
2016-07-31
Budget Start
2015-08-01
Budget End
2016-07-31
Support Year
8
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Icahn School of Medicine at Mount Sinai
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
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A Verghese, Divya; Demir, Markus; Chun, Nicholas et al. (2018) T Cell Expression of C5a Receptor 2 Augments Murine Regulatory T Cell (TREG) Generation and TREG-Dependent Cardiac Allograft Survival. J Immunol 200:2186-2198
Llaudo, Ines; Fribourg, Miguel; Medof, M Edward et al. (2018) C5aR1 regulates migration of suppressive myeloid cells required for costimulatory blockade-induced murine allograft survival. Am J Transplant :
Chun, N; Fairchild, R L; Li, Y et al. (2017) Complement Dependence of Murine Costimulatory Blockade-Resistant Cellular Cardiac Allograft Rejection. Am J Transplant 17:2810-2819
Sheen, Joong-Hyuk; Strainic, Michael G; Liu, Jinbo et al. (2017) TLR-Induced Murine Dendritic Cell (DC) Activation Requires DC-Intrinsic Complement. J Immunol 199:278-291
Purroy, Carolina; Fairchild, Robert L; Tanaka, Toshiaki et al. (2017) Erythropoietin Receptor-Mediated Molecular Crosstalk Promotes T Cell Immunoregulation and Transplant Survival. J Am Soc Nephrol 28:2377-2392
Stamatiades, Efstathios G; Tremblay, Marie-Eve; Bohm, Mathieu et al. (2016) Immune Monitoring of Trans-endothelial Transport by Kidney-Resident Macrophages. Cell 166:991-1003
Chun, Nicholas; Heeger, Peter S (2016) Blurring the Lines Between Innate and Adaptive Immunity. Transplantation 100:1789-1790
Sheen, Joong Hyuk; Heeger, Peter S (2015) Effects of complement activation on allograft injury. Curr Opin Organ Transplant 20:468-75
Cravedi, Paolo; Heeger, Peter S (2015) Corrigendum. Complement as a multifaceted modulator of kidney transplant injury. J Clin Invest 125:1365

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