Korean J Transplant.  2023 Nov;37(Suppl 1):S200. 10.4285/ATW2023.F-7898.

Deciphering immunogenic diversity via glycan antigen characterization in genetically modified pigs for xenotransplantation

• Oh MJ
• Lee D
• Shim J
• Cho K
• An HJ

• KMID: 2551820
• DOI: http://doi.org/10.4285/ATW2023.F-7898

Abstract

Clinical application of xenogeneic tissue holds great potential to overcome human donor organ shortage. However, porcine xenografts are rejected by human antibodies that bind to pig antigens due to species differences. Notably, glycan antigens such as N-glycolylneuraminic acid (NeuGc), Sda, and terminal-gal antigens, are highly influential in driving tissue immunogenicity due to immense variability, both within and between species. Genetically engineered pigs lacking the expression of glycan antigens were produced to address the rejection mechanism and construct safer xenografts. To investigate the association between genotype and glycophenotype, glycan analysis was conducted using isomer-sensitive PGC LC/MS/MS. Isomeric glycan compositions with identical masses but different structures were separated on a PGC-based column and annotated based on retention time, accurate masses, MS/MS fragmentations, and previously reported structures. We characterized the structural diversity and expression levels of immunogenic glycans, encompassing NeuGc, Sda, and terminal-gal antigens in cardiac and renal tissues from WT and triple knockout (CMAH/GGTA/B4GALNT2B) pigs TKO. Our findings showed that Gal, Neu5Gc, and Sd(a) were markedly expressed in all the examined tissues in WT pigs but barely detected in TKO pigs. These results indicate that the glycan antigen of TKO pig is significantly reduced and the remaining xenoantigens on porcine tissues can be eliminated via a gene targeting approach. Moreover, our investigations uncovered significant intra- and interspecies differences in immunogenic glycan diversity and expression levels. Our study underscores the importance of investigating tissue-specific immunogenic glycans and suggests potential strategies for mitigating xenotransplantation-induced immune rejection by engineering the glycans of pig grafts.