Expression data from biopsies of TGP patients. Homo sapiens

We study the global gene expression profiles of TGP patients with or without graft loss to determine if a clinical and/or gene expression profile can predict allograft survival. Transplant glomerulopathy (TGP) carries a poor prognosis and is associated with decreased allograft survival. In a large series of kidney transplant recipients, graft loss was observed in 38% of TGP patients at 5 years compared to 5% in patients without TGP. Among patients with TGP, predictors of poor outcome included C4d deposition in the peritubular capillaries, higher serum creatinine and proteinuria at diagnosis, the severity of interstitial fibrosis, and GBM duplication (higher Banff ‘chronic glomerulopathy [cg]’ score), and the presence of DSA. However, the importance of microvascular inflammation determined by peritubular capillaritis (ptc) and glomerulitis (g) scores and the strength of DSA has not been explored thoroughly. We have recently reported the intragraft gene expression profiles of TGP patients, with or without DSA. However, the association between gene expression profiles of biopsies and the allograft survival has not been investigated. In this study, in addition to known clinical and demographic factors associated with poor outcomes in TGP, we specifically aimed to investigate if intragraft gene expression profiles by microarrays, microvascular inflammation scores, and the strength of DSA determined by mean fluorescence intensity (MFI) values could predict allograft loss in TGP patients. Overall design: The study population was derived from renal allograft biopsies diagnosed with TGP at Montefiore Medical Center, Bronx, NY from January 2009 to December 2012. All biopsies were clinically indicated for elevated creatinine or proteinuria. A retrospective chart review was conducted to record clinical, demographic, immunological, and histopathological parameters and graft outcomes. Graft loss was defined as requiring dialysis and/or retransplantation during follow-up. Of the 525 patients who underwent clinically indicated transplant kidney biopsies, 52 patients (10%) had diagnosis of TGP. Median follow up time after the biopsy was 23 months (range, 1-46). Seventeen patients (32%) lost their allografts (defined by return to dialysis or re-transplantation) at a median time of 16 months (range, 1-44). A subgroup of patients who were enrolled in the IRB-approved “Immune Monitoring Study” and had clinically indicated biopsy samples were included in the analysis. A total of 28 biopsy samples (8 graft loss and 20 functioning allograft) were used for gene expression profiling.