BACKGROUND: Delayed xenograft rejection is associated with endothelial cell activation, platelet sequestration, and subsequent thrombosis. We evaluated whether human platelets could directly activate porcine endothelium (PEC), and if so, whether this was mediated by an interaction between platelet-bound CD154 and PEC CD40. METHODS: Platelet activation was achieved by thrombin exposure and confirmed by evaluation of up-regulated CD62P and CD154. Co-incubation of platelets or D1.1 cells with PEC was performed, and PEC activation was evaluated by up-regulation of CD62E. RESULTS: Co-incubation of resting platelets that lacked significant expression of CD62P and were void of CD154 did not activate PEC. In contrast, thrombin-activated human platelets expressing considerable amounts of both CD62P and CD154 induced PEC activation. This activation could be completely inhibited by coincubation with a humanized monoclonal antibody directed at human CD154 (hu5c8). Similarly, human D1.1 cells expressing CD154 were shown to activate PEC in a CD154-dependent manner. CONCLUSION: Human CD154 expressed on activated human platelets or on T cells interacts with CD40 expressed on PEC leading to PEC activation. This interaction can be inhibited by a monoclonal antibody directed against CD154, suggesting that an interaction between human CD154 and PEC CD40 is at least in part responsible for PEC activation seen in delayed xenograft rejection. These data strengthen the rationale for the use of CD154-directed therapy in discordant xenotransplantation.
BACKGROUND: Delayed xenograft rejection is associated with endothelial cell activation, platelet sequestration, and subsequent thrombosis. We evaluated whether human platelets could directly activate porcine endothelium (PEC), and if so, whether this was mediated by an interaction between platelet-bound CD154 and PEC CD40. METHODS: Platelet activation was achieved by thrombin exposure and confirmed by evaluation of up-regulated CD62P and CD154. Co-incubation of platelets or D1.1 cells with PEC was performed, and PEC activation was evaluated by up-regulation of CD62E. RESULTS: Co-incubation of resting platelets that lacked significant expression of CD62P and were void of CD154 did not activate PEC. In contrast, thrombin-activated human platelets expressing considerable amounts of both CD62P and CD154 induced PEC activation. This activation could be completely inhibited by coincubation with a humanized monoclonal antibody directed at humanCD154 (hu5c8). Similarly, human D1.1 cells expressing CD154 were shown to activate PEC in a CD154-dependent manner. CONCLUSION:HumanCD154 expressed on activated human platelets or on T cells interacts with CD40 expressed on PEC leading to PEC activation. This interaction can be inhibited by a monoclonal antibody directed against CD154, suggesting that an interaction between humanCD154 and PEC CD40 is at least in part responsible for PEC activation seen in delayed xenograft rejection. These data strengthen the rationale for the use of CD154-directed therapy in discordant xenotransplantation.
Authors: A Page; S Srinivasan; K Singh; M Russell; K Hamby; T Deane; S Sen; L Stempora; F Leopardi; A A Price; E Strobert; K A Reimann; A D Kirk; C P Larsen; L S Kean Journal: Am J Transplant Date: 2011-09-19 Impact factor: 8.086
Authors: Burcin Ekser; Chih C Lin; Cassandra Long; Gabriel J Echeverri; Hidetaka Hara; Mohamed Ezzelarab; Vladimir Y Bogdanov; Donna B Stolz; Keiichi Enjyoji; Simon C Robson; David Ayares; Anthony Dorling; David K C Cooper; Bruno Gridelli Journal: Transpl Int Date: 2012-05-30 Impact factor: 3.782
Authors: A H Charafeddine; E J Kim; D M Maynard; H Yi; T A Weaver; M Gunay-Aygun; M Russell; W A Gahl; A D Kirk Journal: Am J Transplant Date: 2012-09-04 Impact factor: 8.086
Authors: Hayato Iwase; Burcin Ekser; Hidetaka Hara; Carol Phelps; David Ayares; David K C Cooper; Mohamed B Ezzelarab Journal: Xenotransplantation Date: 2013-11-05 Impact factor: 3.907