Cytokines Evaluation in Early Calcineurin Inhibitors Withdrawn on Renal Transplant

Overview

Currently, acute kidney injury is diagnosed by increased serum creatinine. However, creatinine is not a reliable marker for acute changes in renal function. The biology of the renal graft is influenced by chemokines from reperfusion (just after the kidney transplant) and throughout its course, when acute and chronic inflammatory changes occurs. Moreover, the evaluation of changes in urinary cytokines reflects kidney interstitial patterns, and can predict renal function, acute rejection episodes and their response to treatment. Today there are several studies comparing the relative immunosuppression of renal function, but few noticed its relationship with cytokines and chemokines. Thus, we proposed studying the inflammatory consequences of early calcineurin inhibitors (ICN) withdrawing in transplant patients by urine analysis. Kidney biopsy was done before ICN withdrawn and replaced by everolimus (3 months after transplant), and 1 year after transplant.

1. Research objectives OBJECTIVES Main Objectives: • Evaluate the urinary chemokines in kidney transplant patients taking prednisone, tacrolimus and mycophenolate sodium compared to those in use prednisone, mycophenolate sodium and everolimus as maintenance immunosuppression. Secondary Objectives: • Assess renal function (serum creatinine and its clearance estimated by the Cockcroft-Gault) and a composite outcome (acute rejection, graft loss, death and abandonment of the study) in patients taking prednisone, tacrolimus and mycophenolate sodium compared to those taking prednisone, mycophenolate sodium and everolimus as maintenance immunosuppression. 2. Scientific background, relevance and justification of the research In current clinical practice, acute kidney injury is typically diagnosed by measuring serum creatinine. Unfortunately, creatinine is an unreliable indicator during acute changes in kidney function. First, serum creatinine concentrations may not change until about 50% of kidney function has already been lost. Second, serum creatinine does not accurately depict kidney function until a steady state has been reached, which may require several days. Chemokines can influence at least three aspects of the biology of the renal graft: 1 - the restoration of blood flow in the graft can lead to injury type ischemia / reperfusion in which chemokines recruit leukocytes; 2 - receptor responses to infection during immune suppression involve chemokines and 3 - the inflammatory components in the acute rejection (RA) and interstitial fibrosis / tubular atrophy (IF/TA) are controlled by chemokines. Current data have showed urinary cytokines predicting renal function by months in renal transplanted patients. In the evaluation of urinary cytokines and chemokines in the presence of acute rejection, taken together the studies reported elevations of urinary levels of Protein-3 alpha (MIP-3α/CCL20), interleuxin-8 (IL-8/CXCL8), interleuxin-6 (IL-6), tumoral necrosis factor (TNF), interleukin- 10 (IP-10), interferon (IFN), monocyte chemoattractant protein-1 (MCP-1 / CCL2), Interferon gamma-induced protein 10 (IL-10), Monokine induced by gamma interferon (MIG/CXCL9), Interferon-inducible T-cell alpha chemoattractant (I-TAC/CXCL11), regulated upon activation normal T cell expressed and secreted (RANTES/CCL5). As predictors of complications and future changes in renal function, levels of Transforming growth factor beta (TGF-β) and interferon-gamma inducible protein 10 (IP-10/CXCL10) were associated with renal function 6 months and 4 years after transplantation (15-16). IP-10/CXCL10, MIG/CXCL9, G protein-coupled receptor 9 (GPR9/CXCR3), RANTES/CCL5 and the percentage of binding of interleukin-2 (IL-2) were associated with the occurrence of RA. IP-10/CXCL10 and MIG/CXCL9 were also considered useful as predictors of response to treatment of RA. Nankivell et al reported in 2003 that after 1year of renal transplant, 94% of patients present with chronic rejection grade I (BANFF score) and 76% present with calcineurin nephrotoxicity, although there is insufficient data about urinary cytokines at these situations. And adding new information, Hu et al reported in 2009 urinary major intrinsic protein-delta (MIP-δ), osteoprotegerin (OPG), IP-10/CXCL10, MIG/CXCL9 as good biomarkers for acute renal rejection and IF/TA. Nowadays there is a lot of studies comparing immunosuppression in relation to renal function but not so much in relation to chemokines and cytokines, which are more representative of allograft inflammation and fibrosis. So, we proposed studying the inflammatory consequences of early CNI withdrawn in renal transplant patients before the immunosuppression modification (3 months after transplant) and 1 year after kidney transplant.