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Abstract: TH-OR51

A Single-Nucleus RNA-Sequencing of Human Kidney Transplant Biopsies Identifies a Novel Role of Pericytes and Endothelium in Cellular Rejection

Session Information

Category: Transplantation

  • 2001 Transplantation: Basic

Authors

  • Halawi, Ahmad, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • El Kurdi, Abdullah Bilal, American University of Beirut, Beirut, Lebanon
  • Vernon, Katherine Anne, Q32 BIO, Cambridge, Massachusetts, United States
  • Solhjou, Zhabiz, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Choi, John Yongjoon, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Saad, Anis Joseph, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Younis, Nour Khaled, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Deban, Christa A., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Khoueiry, Pierre, American University of Beirut, Beirut, Lebanon
  • Greka, Anna, Broad Institute, Cambridge, Massachusetts, United States
  • Azzi, Jamil R., Harvard Medical School, Boston, Massachusetts, United States
Background

Immunosuppressive therapies in kidney transplantation were developed based on their effect on T-cell activation rather than alloimmunity mechanisms. Thus, understanding the role of different cells during rejection is essential to identifying directed therapies.

Methods

Single nucleus RNA sequencing was done on non-rejecting allograft, borderline, and T-cell mediated rejection (TCMR) samples.
Data analysis was done using RStudio and Seurat. Pathway analysis was performed using Enrichr and Gene Sets Enrichment Analysis. Ligand-Receptor (LR) analysis was performed using SingleCellSignalR.

Results

Pathway analysis of T-cells in borderline and TCMR samples showed enrichment for allograft rejection and IFN-gamma response pathways, suggesting that our borderline sample reflects an early rejection. Hence, this allows for studying the early stages of cellular rejection.
Pathway analysis of endothelial cells (ECs) of borderline and non-rejecting samples showed that focal adhesion and IFN-gamma pathways were significantly enriched compared to TCMR. Furthermore, LR analysis found that in borderline rejection, ECs increase NOTCH4 response to JAG1, among others. These interactions potentiate pericytes' ability to stabilize ECs and protect the allograft from lymphocyte invasion in the borderline rejection, but not in TCMR. Furthermore, ECs upregulate TLR4 in borderline rejection and not TCMR, which interacts with T-cells’ HMGB1 suggesting a role for TLR4 in early rejection. To support our findings, we performed biopsy staining from borderline and TCMR and in vitro analysis of HUVEC exposed to IFN-gamma and T-cells.

Conclusion

ECs are involved in the early rejection process by upregulating IFN-gamma response, focal adhesion pathway, and TLR4 interacting with HMGB1 secreted by T-cells.