Coordinated circulating and tissue-based T cell responses precede xenograft rejection 2308959

Abstract

Abstract Introduction Despite the life-saving successes of solid organ transplantation, organ demand far exceeds availability. Porcine xenotransplantation, the use of pig organs in humans, holds promise, but acute rejection remains a barrier to long-term xenograft survival. Methods To investigate mechanisms of acute xenorejection, we used the first long-term (61-day) human decedent xenotransplantation model at NYU, in which a decedent received a kidney with a thymus autograft (“thymokidney”) from an α-1,3-galactosyltransferase knockout (GGTA1 KO) pig. This unique model allows serial thymokidney biopsies, paired blood draws, lymph node biopsies and exhibited antibody-mediated (AMR) and cellular rejection despite immunosuppression. We performed TCR sequencing on thymokidney biopsies and 5’ CITE-seq of blood. Xenoreactive clonotypes were identified by mixed lymphocyte reaction. We identified clonal families forming over time and across compartments. Results Longitudinal analysis of the thymokidney biopsies revealed human CD4 and CD8 T cell responses that formed clonotypic families. Circulating activated T cells increased 2 weeks before rejection, highlighting the potential as a cellular biomarker of rejection. Strikingly, a single xeno-reactive CD8 clonotype expanded dramatically in the blood before rejection and was also identified in the xenograft during rejection. T cell clonotypes were shared across xenograft, blood and lymph nodes and formed clonal families with known xeno-reactive clonotypes, suggesting a coordinated response to a limited set of antigenic targets. Serum CXCL13 and circulating T follicular helper cells increased before AMR, indicating formation of germinal centers which suggests therapeutic opportunities to treat impending rejection. Conclusion These findings establish a framework to track coordinated immune responses at cellular, clonal, and clonotypic family levels and identify potential biomarkers of xenorejection, offering new opportunities for early prediction and potential intervention. Funding Source National Institutes of Health (NIH) grant R01AI158617 (RSH) National Institutes of Health (NIH) grant U19AI082630 (RSH) National Institutes of Health (NIH) grant U19AI191396 (ADG, BJK, RAM) Topic Categories Transplantation Immunology (TRAN)