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Kidney Week

Abstract: FR-OR63

Differential cfDNA Methylation in Kidney Allograft Rejection

Session Information

Category: Transplantation

  • 2102 Transplantation: Clinical

Authors

  • Spector, Benjamin L., University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States
  • Sante, Drinnan, University of Missouri Kansas City, Kansas City, Missouri, United States
  • Cheung, Warren A., Children's Mercy Research Institute, Kansas City, Missouri, United States
  • Koseva, Boryana S., Children's Mercy Research Institute, Kansas City, Missouri, United States
  • Kats, Alexander, Children's Mercy Kansas City, Kansas City, Missouri, United States
  • Wyckoff, Gerald J., University of Missouri Kansas City, Kansas City, Missouri, United States
  • Willig, Laurel K., Children's Mercy Kansas City, Kansas City, Missouri, United States
Background

Acute allograft rejection (AAR) is a risk for kidney allograft failure, however, knowledge of the molecular pathophysiology of rejection is lacking. Allograft life is limited and organ availability is scarce, emphasizing the need to understand rejection pathophysiology to preserve the primary allograft. Cell-free DNA (cfDNA) serves as a real-time marker of organ injury and immune response. DNA methylation patterns dictate gene expression. Generally, hypermethylation silences gene expression and hypomethylation indicates active transcription. We propose methylation changes in cfDNA during AAR inform the biologic pathways involved in its development and sequelae.

Methods

Methylation status of total plasma cfDNA samples from 20 pediatric kidney transplant recipients at the time of allograft biopsy was assessed using whole genome bisulfite sequencing. 7,789 differentially methylated CpG sites (DMCs) between individuals with vs without AAR were determined through logistic regression analysis (≥20% difference in methylation rate, q-value <0.05) and were assessed for gene associations and pathway/functional enrichments.

Results

AAR was present in 7 patients. 3,390 DMCs were relatively hypermethylated in the setting of AAR and 4,399 were relatively hypomethylated; these DMCs were associated with 114 and 138 genes, respectively. On enrichment analysis, “Relationship between inflammation, COX-2 and EGFR”, "Negative regulation of mononuclear cell proliferation”, “Regulation of cysteine-type endopeptidase activity in apoptotic process”, "Regulation of interleukin-8 production”, and “PID CD8 TCR Pathway” were among the most significant WikiPathways, canonical pathways, and Gene Ontology (GO) Terms in hypermethylated genes (P < 0.005). “Response to oxidative stress” and "Regulation of leukocyte mediated cytotoxicity” were among top GO Terms in hypomethylated genes (P ≤ 0.01).

Conclusion

Our data implicate differential immune responses in acute rejection compared to non-rejection in kidney transplant recipients. These differences include the innate and adaptive immune responses and involve the differential regulation of leukocytes and mediation of cytokines. These results provide evidence that methylation differences of cfDNA inform the mechanisms of AAR.

Funding

  • Private Foundation Support