Peripheral blood transcriptomic profiles of rejection and polyomavirus-associated nephropathy after kidney transplantation

Kidney transplant injury processes are associated with molecular changes in renal tissue, primarily related to immune cell activation and infiltration. How these processes are reflected by molecular alterations in circulating immune cells is poorly understood. We performed RNA-sequencing on 384 biobanked blood samples from four transplant centers, taken at time of a kidney allograft biopsy, selected for their phenotype (acute T cell- and antibody-mediated rejection, polyomavirus-associated nephropathy, and control). We performed differential expression analysis and pathway analysis per phenotype. In peripheral blood, differentially expressed genes in rejection vs. no rejection samples demonstrated upregulation of glucocorticoid receptor and NOD-like receptor signaling pathways. Pathways enriched in antibody-mediated rejection were strongly immune-specific, whereas pathways enriched in T cell-mediated rejection were less immune related. Differentially expressed genes in polyoma viremia and polyomavirus-associated nephropathy were similar and demonstrated upregulation of mitochondrial dysfunction and interferon signaling pathways. Our results highlight the immune activation pathways in peripheral blood leukocytes at time of antibody-mediated rejection and polyomavirus nephropathy and provide a framework for future therapeutic interventions. Overall design: RNAsequencing of 384 biobanked blood samples from four transplant centers, taken at time of a kidney allograft biopsy, selected for their phenotype (acute T cell- and antibody-mediated rejection, polyomavirus-associated nephropathy, and control).