FOXP3 mRNA profile prognostic of T cell mediated rejection and human kidney allograft survival

Background and objectivesT cell mediated rejection (TCMR) is the most frequent type of acute rejection and is associated with kidney allograft failure. Almost 40% of TCMR episodes fail to respond to anti-rejection therapy. FOXP3 is a specification factor for regulatory T cells and our single center study of 83 kidney allograft recipients showed that urinary cell FOXP3 mRNA level is diagnostic of TCMR and predicts TCMR reversibility and allograft survival. The objective of the current study is to determine whether our original findings could be replicated in an independent cohort of 480 kidney allograft recipients enrolled in the multicenter Clinical Trials of Organ Transplantation (CTOT)-04. Design, setting, participants, and measurementsWe measured levels of FOXP3 mRNA and levels of mRNA for CD25, CD3E, and perforin, and 18S rRNA in 3559 urines from 480 kidney allograft recipients prospectively enrolled in CTOT-04. RNA was isolated from the urinary cells and preamplification-enhanced real-time quantitative PCR assays were used to measure mRNAs. Results18S rRNA normalized levels of mRNA for FOXP3 (P=0.01, Kruskal-Wallis test), CD25 (P=0.01), CD3E (P<0.0001), and perforin (P<0.0001) distinguished patients with TCMR biopsies from those with No Rejection biopsies and those with stable graft function. FOXP3 mRNA level, but not the levels of mRNA for CD25, CD3E, or perforin, predicted TCMR reversal (AUC=0.764; 95% confidence interval, 0.611 to 0.917; P=0.008). Multivariable logistic regression analysis showed that FOXP3 mRNA level remains predictive after adjustment for potential cofounders. Kaplan-Meier survival curve analysis showed that FOXP3 mRNA level (P=0.0306) but not the levels of mRNA for CD25, CD3E, or perforin, is associated with kidney allograft survival. ConclusionIn the independent CTOT-04 cohort, we demonstrate that urinary cell level of FOXP3 mRNA is diagnostic of TCMR, predicts its reversibility, and is prognostic of kidney allograft survival following an episode of TCMR.