Nuclear factor of activated T cells as potential pharmacodynamic biomarker for the risk of acute and subclinical rejection in de novo liver recipients

Background & Aims Nuclear factor of activated T cell-regulated gene expression (NFAT-RGE) has been proposed as a pharmacodynamic biomarker for tacrolimus (Tac) and cyclosporine (CsA). Our aim was to evaluate the role of NFAT-RGE in modulating intralymphocytary IL-2 and IFN-gamma expression and its clinical utility as an early non-invasive predictive biomarker for the risk of acute rejection (AR) and infection in de novo liver transplant (LT) recipients. Methods Fifty-six LT recipients treated with Tac or CsA [with and without mycophenolate mofetil (MMF)] were included: 30 free of rejection or infection, 11 rejectors (T cell-mediated acute rejection), 5 with subclinical rejection (SCR) and 10 with cytomegalovirus (CMV) infection. Within the first 3 months after transplantation, NFAT-RGE of IL-2, IFN-gamma and GM-CSF and intralymphocytary synthesis of IL-2 and IFN-gamma were evaluated by real-time PCR and flow cytometry respectively. Results A significant increase in NFAT-RGE was observed in patients who experienced TCMAR (75% [42-100%]) or SCR (41% [18-78%]) compared with patients without rejection or infection (14% [2-23%]). Positive correlations between the %NFAT-RGE-IFN and both the %CD8CD69IFN-gamma and %CD4CD69IFN-gamma and between the %NFAT-RGE-IL2 and the %CD8CD69IL2 were observed. NFAT-RGE was significantly lower in CMV+ patients than in non-infected patients. Finally, an inverse correlation between the Tac or CsA concentration and inhibition of NFAT-RGE were observed. Conclusions Sequential post-transplantation NFAT-RGE monitoring combined with intralymphocytary IL-2 and IFN-gamma before transplantation and at the first and third month post-transplantation may be key predictive and diagnostic biomarkers for the risk of TCMAR and SCR and better guide CNi therapy in LT patients.