Generation of immunologically invisible organs through ex vivo MHC silencing to prevent rejection in a miniature swine lung transplantation model
Final Report Abstract
Despite major progresses, currently lung grafts continue to show worse long-term survival rates in comparison to other organs after allogeneic transplantation. Human Leukocyte Antigen (HLA) disparities between donor and recipients remain a major hurdle in allogeneic organ transplantation as they trigger immune responses that cause graft dysfunction and rejection. However, the lack of donors, the high variability of HLA loci and minor histocompatibility antigens makes impossible in most of the cases to find a completely HLA and minor histocompatibility antigens donor for a specific recipient. Therefore, in this study we aimed at the evaluation of the effect of downregulating the expression of Swine Leukocyte Antigen (SLA, equivalent to HLA) class I and II on graft survival after allogeneic lung transplantation in a porcine model. In addition, we aimed at the characterization of the allogeneic immune responses after transplantation of SLA-expressing and SLA-downregulated pulmonary grafts. Lentiviral vectors were constructed to express short hairpin RNAs targeting β2-microglobulin (shβ2m) and the class II transactivator (CIITA) to silence SLA class I and II, respectively. Lentiviral vectors encoding for non-specific shRNAs were used as a control. Minipig donor lungs were perfused en bloc for 2-3h under normothermic conditions and the left lung was transplanted. Lungs with unmodified SLA expression (control group, n=7) or with modified SLA expression (treatment group, n=7) were used to evaluate the effects of SLA knockdown on allograft survival and on the nature and strength of immune responses after terminating an initial four-week period of immunosuppression post-lung transplantation. While all grafts in the control group were rejected within 3 months, the treatment group achieved a graft survival rate of 71.4% (5/7 recipients) without immunosuppression during the two-year immunomonitoring period and animals are currently still alive. Compared to the control group, SLA- silenced lung recipients had lower serum IgG levels as well as weaker alloreactive T-cell responses and pro-inflammatory cytokine levels. Bronchoalveolar lavage fluid cell composition analyses showed significantly lower frequencies of NK cells, helper and cytotoxic T cells in SLA-silenced lung recipients. Our data demonstrate a remarkable survival benefit of SLA- downregulated lung transplants, even in the absence of immunosuppression. This study shows that genetic engineering opens up entirely new horizons in transplant medicine and offers with MHC knockdown the potential to overcome the disadvantages of immunosuppression.
Publications
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Immunoengineering of the Vascular Endothelium to Silence MHC Expression During NormothermicEx VivoLung Perfusion. Human Gene Therapy, 30(4), 485-496.
Figueiredo, Constanca; Carvalho, Oliveira Marco; Chen-Wacker, Chen; Jansson, Katharina; Höffler, Klaus; Yuzefovych, Yuliia; Pogozhykh, Olena; Jin, Zhu; Kühnel, Mark; Jonigk, Danny; Wiegmann, Bettina; Sommer, Wiebke; Haverich, Axel; Warnecke, Gregor & Blasczyk, Rainer
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Genetically engineered lungs are protected from immune rejection in the absence of immunosuppression. 31. Jahrestagung der DTG 2022 in Erlangen
Figueiredo C.; Chen-Wacker C.; Salman J.; Carvalho-Oliveira M.; Siemeni Monthé T.; Höffler K.; Rother T.; Hacker K.; Pogozhykh O.; Hammer S.; Sommer W.; Valdivia E.; Wenzel N.; Yuzefvych Y.; Haverich A.; Warnecke G. & Blasczyk R.
