The role of human CD46 in early xenoislet engraftment in a dual transplant model

• Published in: Xenotransplantation (Københaven) 2019-11, Vol.26 (6), p.e12540-n/a
• Main Authors: Samy, Kannan P., Gao, Qimeng, Davis, Robert Patrick, Song, Mingqing, Fitch, Zachary W., Mulvihill, Michael S., MacDonald, Andrea L., Leopardi, Frank V., How, Tam, Williams, Kyha D., Devi, Gayathri R., Collins, Bradley H., Luo, Xunrong, Kirk, Allan D.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Genetically Modified - immunology; Antibodies - immunology; Apoptosis; Caspase-3; CD46; CD46 antigen; Complement Activation - immunology; Complement component C3b; Elastase; Genotypes; Graft rejection; Graft Rejection - immunology; Humans; Immunoglobulin G; Immunoglobulin M; Immunohistochemistry; Inflammation; Inflammation - immunology; instant blood‐mediated inflammatory reaction; Insulin; islet transplantation; Islets of Langerhans - immunology; Islets of Langerhans Transplantation - methods; Macaca mulatta - immunology; Membrane cofactor protein; Membrane Cofactor Protein - immunology; Membrane proteins; Neonates; Neutrophils; Platelets; Transplantation, Heterologous - methods; Transplants - immunology; Xenografts; Xenotransplantation
• ISSN: 0908-665X; 1399-3089; 1399-3089
• DOI: 10.1111/xen.12540

Background Membrane cofactor protein CD46 attenuates the complement cascade by facilitating cleavage of C3b and C4b. In solid organ xenotransplantation, organs expressing CD46 have been shown to resist hyperacute rejection. However, the incremental value of human CD46 expression for islet xenotransplantation remains poorly defined. Methods This study attempted to delineate the role of CD46 in early neonatal porcine islet engraftment by comparing Gal‐knocked out (GKO) and hCD46‐transgenic (GKO/CD46) islets in a dual transplant model. Seven rhesus macaques underwent dual transplant and were sacrificed at 1 hour (n = 4) or 24 hours (n = 3). Both hemilivers were recovered and fixed for immunohistochemistry (CD46, insulin, neutrophil elastase, platelet, IgM, IgG, C3d, C4d, CD68, Caspase 3). Quantitative immunohistochemical analysis was performed using the Aperio Imagescope. Results Within 1 hour of intraportal infusion of xenografts, no differences were observed between the two types of islets in terms of platelet, antibody, or complement deposition. Cellular infiltration and islet apoptotic activity were also similar at 1 hour. At 24 hours, GKO/CD46 islets demonstrated significantly less platelet deposition (P = 0.01) and neutrophil infiltration (P = 0.01) compared to GKO islets. In contrast, C3d (P = 0.38) and C4d (P = 0.45) deposition was equal between the two genotypes. Conclusions Our findings suggest that expression of hCD46 on NPIs potentially provides a measurable incremental survival advantage in vivo by reducing early thrombo‐inflammatory events associated with instant blood‐mediated inflammatory reaction (IBMIR) following intraportal islet infusion.