Chaowen Zheng1, Mohamad Mahdi Sleiman2, Xiaofeng Yang2, Songqing He3, Carl Atkinson4, Stephen Tomlinson5. 1. Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina; Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China. 2. Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina. 3. Division of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China. 4. Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina; The Lee Patterson Allen Transplant Immunobiology Laboratory, Department of Transplant Surgery, Medical University of South Carolina, Department of Surgery, Charleston, South Carolina; Department of Surgery, Medical University of South Carolina, Charleston, South Carolina; Department of Pulmonary Medicine, University of Florida, Gainesville, Florida. 5. Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina; Ralph H Johnson VA Medical Center, Charleston, South Carolina. Electronic address: tomlinss@musc.edu.
Abstract
BACKGROUND: Post-transplant ischemia reperfusion injury (IRI) is a recognized risk factor for subsequent organ dysfunction, alloresponsiveness, and rejection. The complement system is known to play a role in IRI and represents a therapeutic target. Complement is activated in transplanted grafts when circulating IgM antibodies bind to exposed ischemia-induced neoepitopes upon reperfusion, and we investigated the targeting of a human complement inhibitor, CR1, to a post-transplant ischemia-induced neoepitope. METHODS: A fragment of human CR1 was linked to a single chain antibody construct (C2 scFv) recognizing an injury-specific neoepitope to yield C2-CR1. This construct, along with a soluble untargeted counterpart, was characterized in a cardiac allograft transplantation model of IRI in terms of efficacy and safety. RESULTS: CR1 was similarly effective against mouse and human complement. C2-CR1 provided effective protection against cardiac IRI at a lower dose than untargeted CR1. The increased efficacy of C2-CR1 relative to CR1 correlated with decreased C3 deposition, and C2-CR1, but not CR1, targeted to cardiac allografts. At a dose necessary to reduce IRI, C2-CR1 had minimal impact on serum complement activity, in contrast to CR1 which resulted in a high level of systemic inhibition. The circulatory half-life of CR1 was markedly longer than that of C2-CR1, and whereas a minimum therapeutic dose of CR1 severely impaired host susceptibility to infection, C2-CR1 had no impact. CONCLUSION: We show the translational potential of a human complement inhibitor targeted to a universal ischemia-induced graft-specific epitope, and demonstrate advantages compared to an untargeted counterpart in terms of efficacy and safety. Published by Elsevier Inc.
BACKGROUND: Post-transplant ischemia reperfusion injury (IRI) is a recognized risk factor for subsequent organ dysfunction, alloresponsiveness, and rejection. The complement system is known to play a role in IRI and represents a therapeutic target. Complement is activated in transplanted grafts when circulating IgM antibodies bind to exposed ischemia-induced neoepitopes upon reperfusion, and we investigated the targeting of a human complement inhibitor, CR1, to a post-transplant ischemia-induced neoepitope. METHODS: A fragment of human CR1 was linked to a single chain antibody construct (C2 scFv) recognizing an injury-specific neoepitope to yield C2-CR1. This construct, along with a soluble untargeted counterpart, was characterized in a cardiac allograft transplantation model of IRI in terms of efficacy and safety. RESULTS: CR1 was similarly effective against mouse and human complement. C2-CR1 provided effective protection against cardiac IRI at a lower dose than untargeted CR1. The increased efficacy of C2-CR1 relative to CR1 correlated with decreased C3 deposition, and C2-CR1, but not CR1, targeted to cardiac allografts. At a dose necessary to reduce IRI, C2-CR1 had minimal impact on serum complement activity, in contrast to CR1 which resulted in a high level of systemic inhibition. The circulatory half-life of CR1 was markedly longer than that of C2-CR1, and whereas a minimum therapeutic dose of CR1 severely impaired host susceptibility to infection, C2-CR1 had no impact. CONCLUSION: We show the translational potential of a human complement inhibitor targeted to a universal ischemia-induced graft-specific epitope, and demonstrate advantages compared to an untargeted counterpart in terms of efficacy and safety. Published by Elsevier Inc.