Eine kontinuierliche Expression löslicher MHC-Spenderantigene mittels adenoviralem Vektor induziert eine Verlängerung der Überlebenszeit von Herztransplantaten im „High“-Respondermodell ACI zu Lewis

Abstract

Background: We have previously shown with ex vivo liposome-gene transfer that soluble donor MHC class I (sdMHCI) antigen prolongs heart transplant (Tx) survival in a donor-specific manner when combined with low-dose cyclosporine. The need for concurrent immunosuppression is likely related to the short duration and low-level of sdMHCI expression with this gene transfer method. Here our aim was to improve the immunosuppressive effect of sdMHCI by increasing expression via adenoviral gene transfer. Methods: Using the AdEasy System (B. Vogelstein, Johns Hopkins) we constructed an E1-E3-deleted, replication-deficient adenovirus containing the genes for a secreted form of the rat MHC class I molecule, RT1.A^a (Ad-RQ). An „empty“ adenovirus was used for controls. Lewis (RT1.A¹) rats were intravenously injected with 2×10⁹ fluorescence forming units of Ad-RQ and serum was tested for RT1.A^a by ELISA. Some animals were challenged with a fully allogeneic heterotopic ACI (RT1.A^a) heart Tx 14 days after Ad-RQ or „empty“ adenovirus injection, and allograft survival was determined. Results: Serum samples taken from Ad-RQ-injected rats showed a 100-fold higher expression of RT1.A^a till day 7 compared to the liposome-transfection we have used before. Over the next 7 days Ad- RQ-injected rats showed a 75-fold higher expression of RT1.A^a compared to the liposome-transfection method. Controls receiving „empty“ adenovirus showed no RTl.A^a signal. ACI heart Tx survival was prolonged to up to 4 days with Ad-RQ vs. „empty“ virus-injected controls. Conclusions: Adenoviral gene transfer produces in vivo serum RT1.A^a levels that are almost 100-fold higher after 7 days, compared to our previously reported ex vivo liposome gene transfer method. Prolongation of heart Tx survival without concurrent immunosuppression in a high-responder combination suggests a therapeutically useful effect of sdMHCI.