Abstract
BACKGROUND: Histologic evaluation of baseline kidney biopsies is an inconsistent tool to predict graft outcomes, which might be assisted by gene expression analysis. METHODS: We evaluated 49 consecutive kidney graft biopsies obtained post-reperfusion in 18 deceased donors (DD) and 31 living donors (LD) at our center. Biopsies were evaluated and scored using Banff criteria. Low-density real-time polymerase chain reaction arrays were used to measure intragraft expression of 95 genes associated with programmed cell death, fibrosis, innate and adaptive immunity and oxidative stress signaling. A pool of 25 normal kidney biopsies was used as control. We applied a stepwise forward selection procedure to build a multiple regression model predicting estimated glomerular filtration rate (eGFR) at 1 year after transplant using baseline clinical characteristics and gene expression levels. RESULTS: DD grafts displayed a pattern of gene expression remarkably different from LD, including an increased expression of complement protein C3, and chemokines, CXCL1 and CXCL2, consistent with the proinflammatory setting of ischaemia-reperfusion injury. There was no association between any of the reperfusion biopsy histological features and either renal function at 1 year post-transplant or risk of acute rejection. Conversely, older donor age (R(2) = 0.17, P < 0.001) and higher integrin β2 gene expression levels (incremental R(2) versus Donor Age-only model = 0.23, P < 0.001) jointly predicted lower eGFR at 1 year after transplant (multiple regression R(2) = 0.40). Patients with higher ITGβ2 expression levels in baseline biopsies showed lower eGFR, higher levels of proteinuria and more transplant glomerulopathy on the 1-year per-protocol biopsies. CONCLUSION: ITGβ2 gene expression in reperfusion biopsies may represent a prognostic marker for kidney transplant recipients, potentially helpful in shaping patients' treatment. Further studies are needed to confirm our findings.