Innovative strategies to enhance DCreg function and promote IS drug-free kidney transplant survival

University Of Pittsburgh At Pittsburgh, Pittsburgh PA

Investigators

Abstract

P01 Project 1 Summary Therapeutic regulation of innate immunity remains underexplored. Our overall hypothesis is that graft survival can be extended and immunosuppression (IS) withdrawn in NHP kidney transplantation by innovative strategies incorporating cutting-edge technologies to enable 1) selective inhibitory targeting of DCs in situ, or 2) adoptive transfer of autologous regulatory DCs (DCregs) pulsed with donor small extracellular vesicles (sEVs). The regimens we propose (co-ordinated by administrative Core A, synergistic with Project 2 and dependent on each scientific Core) will (i) provide new mechanistic insight into the induction and maintenance/stability of donor- specific unresponsiveness and (ii) potentially identify novel predictive biomarkers. In due course, our findings may provide opportunities to interact with/participate in NIAID-funded clinical trials, such as those currently assessing DCreg therapy in organ transplantation at the University of Pittsburgh. Recent data show that activation of the inhibitory leukocyte immunoglobulin-like receptor B (LILRB) family member LILRB3 (ILT5; CD85a) that is highly expressed on DCs, confers profound immunoinhibitory functions on myeloid cells that induce T cell tolerance to alloAgs in humanized mice. We will test our hypothesis that an agonistic LILRB3 mAb can extend graft survival/allow IS withdrawal. An alternative novel approach to selective targeting DCs in situ is use of Ab-directed DC-targeting nanobiologics. We hypothesize that nanoparticles (NP) functionalized with mAb against the endocytic receptor DEC205 and loaded with the mTOR inhibitor rapamycin (mTORi-NP) will promote Treg generation, extend graft survival and allow IS withdrawal. We discovered that acquisition of donor MHC Ag via small extracellular vesicles (sEVs) and upregulation of co-inhibitory/anti-inflammatory molecules by recipient DCs subverts anti-donor T cell responses in mouse liver transplant tolerance. In patients, infusion of DCreg results in acquisition (via sEVs) of donor MHC, co-expressed with enhanced levels of co-inhibitory molecules on host DCs. We hypothesize that infusion of autologous DCregs pulsed with donor sEVs (sEV-DCs) will extend graft survival/allow IS withdrawal. Our Specific Aims: Aim 1: To determine whether agonistic LILRB3 mAb combined with baseline immunosuppression can extend kidney graft survival/allow IS withdrawal (n=12 transplants) Aim 2: To ascertain whether selective targeting of DCs in situ using novel DC (DEC205)-directed nanoparticles (mTORi-NPs) can extend graft survival/allow IS withdrawal (n=6 transplants) Aim 3: To assess whether post-transplant infusion of autologous DCregs pulsed with donor sEVs (sEV- DCregs) can extend graft survival/allow IS withdrawal (n=12 transplants) This proposal incorporates the opportunity to further enhance overall program synergy by combining a DC- targeting strategy shown to be effective here in Project 1 (we propose DEC205-directed mTORi-NPs; alternatively, agonistic LILRB3 mAb) with donor alloreactive CARTregs, as described in Project 2, Aim 3.