Project description:Assessment and treatment of severe ischaemia-reperfusion-injury (IRI) remains an unmet challenge in kidney transplantation. Normothermic machine perfusion (NMP) recapitulates IRI ex situ, but there is limited understanding of the transcriptional pathways, and the associated cellular landscape, driving IRI during NMP and determining its severity. Such knowledge is essential for therapeutic targeting and organ resuscitation during machine perfusion. Using tissue obtained at the time of NMP from kidneys subsequently transplanted as part of a randomised controlled trial, we undertook in-depth transcriptomic analyses comparing kidneys suffering severe IRI, manifesting clinically as the development of delayed graft function (DGF), to kidneys with mild IRI (defined by immediate graft function, IGF) post-transplantation. We validated upregulation of previously described pro-inflammatory and immune transcriptomic pathways, including TNFa via NFkB signaling, Allograft Rejection and Inflammatory Response. Going further, we identified innate immune system driven processes at the core of the transcriptional signature in kidneys suffering severe IRI, such as recruitment and migration of myeloid leucocytes, macrophage activation, phagocytosis and inflammasome activation. Deconvolution using single-cell-RNAseq data showed kidneys with severe IRI and post-transplant DGF were enriched for pro-inflammatory mononuclear phagocytes, myofibroblasts and fibroblasts, but depleted of tubuloepithelial, cell signatures. These transcriptional findings were recapitulated in tissue biopsies obtained during NMP from an external cohort comparing kidneys with high acute tubular injury and severe IRI to kidneys with low acute tubular injury and mild IRI; these kidneys were histologically similar to the DGF/IGF kidneys, respectively. Together, our study characterises the transcriptional signature of severe IRI during NMP, suggesting the role of pro-inflammatory innate/pro-fibrotic cells in this process. We describe a transcriptomic signature that may support future prospective therapeutic trials as a potential efficacy endpoint, and highlight potential cellular targets for therapeutic intervention during NMP in an era of precision medicine.

Project description:Delayed graft function (DGF) is associated with a reduced long-term graft survival. Ischemia-reperfusion damage and donors' features have been always considered as key pathogenic factors in this setting. The aim of our study was to evaluate the role of recipients' characteristics in the development of DGF to discover early genomics biomarkers in peripheral blood mononuclear cells (PBMC) in order to identify patients at risk. We prospectively enrolled 932 kidney graft recipients from 466 donors for both kidneys. A total of 226 recipients experienced DGF. Among the 466 donors, 290 couples of recipients both patients presented with early graft function (EGF, group A), 50 couples experienced DGF (group B) and 126 couples of recipients were discordant as one presented DGF and the other promptly recovered graft function (group C). In group C we randomly selected 10 couples of DGF/EGF recipients. Peripheral blood mononuclear cells (PBMC) were harvested before transplantation; their transcriptomic profile was investigated by a microarray approach and microarray results were validated by qPCR in an independent group (DGF n=25; EGF n=25). In the whole study group, DGF was independently associated with both donors’ and recipient’s features. Moreover, group A, B and C presented significant differences in both donors’ and recipients’ characteristics. In group C of patients, DGF was significantly associated with body mass index, dialysis modality and number of mismatches. Two-hundred and seventy-three genes were differentially expressed before transplantation in discordant EGF/DGF patients of group C. Their main biological functions were immune dysfunction and inflammation. Among the differentially expressed genes, we observed a significant increase in the expression of CCR2, the MCP-1 receptor, in DGF patients. CCR-2 and MCP-1 up-regulation was confirmed in an independent cohort of patients. Our results suggest that recipients' clinical and immunological features, potentially modulated by dialysis modality, are associated with the development of DGF independently of donors' features.

Project description:The frequency of delayed function of kidney transplants varies greatly and is associated with the quality of graft, donor age, and the duration of cold ischemia time. Body weight differences between donor and recipient can affect primary graft function. The underlying mechanism is poorly understood. Here, we have transplanted kidney grafts from commensurate body weight (L-WD) or reduced body weight (H-WD) donor rats into syngeneic or allogeneic recipients. 24 hours post-transplantation, serum creatinine level in H-WD recipients was significantly higher compared to that of L-WD recipients indicating impaired primary graft function. We detected a 10 fold higher transcription of IL-6 and dramatically increased tubular destruction in grafts from H-WD recipients. This was accompanied by decreased expression of genes associated with kidney function and an up-regulation of other genes such as cytochrome P450 isoforms, FosL and Trib3 as revealed by DNA microarray analysis. A single application of IL-6 into L-WD recipients is sufficient to impair primary graft function and to cause tubular damage. Whereas, immediate neutralization of IL-6 receptor signaling rescued primary graft function resulting in low serum creatinine levels, well-preserved kidney graft architecture and a normalized gene expression profile. These findings have strong clinical implication as anti-IL6R treatment of patients receiving grafts from lower-weight donors could be used to improve primary graft function. The dataset comprises eight samples divided into four sample groups. Each group represents rat kidneys collected after allogeneic transplantation under a certain condition and includes two biological replicates. The first group is characterized by a high body weight difference between donor and recipient, rats in the second group exhibit a low weight difference. Group three and four are similar to group one, but underwent an additional treatment with anti-IL6R mAb or prednisolone immediately after transplantation.

Dataset Information

CosMx 6175 human gene for human kidney delayed graft function (DGF) and immediate graft function (IGF)

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