The Explorative Study Of Expression And Drug Intervention Of Cytoprotective Genes In Chronic Allograft Nephropathy

Objective Cytoprotective genes have shown to display potentanti-inflammatory and anti-apoptotic function and allow survival andphysiological function of cells. Multiple in vitro and in vivo evidence suggestthat A20, HO-1 and Bcl-X_L are strong cytoprotective genes. Inflammationand apoptosis have been shown to be associated with CAN. Enhancement ofexpression of cytoprotective genes might be helpful to protect renal allograftand postpone development of CAN. We analyzed expression of A20, HO-1and Bcl-X_L in human and rat renal allograft undergoing CAN andinvestigated the impact of drug intervention on their expression to elucidatethe rule of expression of cyto-protective genes and their influence factor andto go deep into the mechanism and rational use of immunosuppresants.Methods 1. Immunohistochemical analysis for expression of cytoprotectivegenes A20, HO-1 and Bcl-X_L was conducted to investigate human renalallografts undergoing CAN. 2. Sprague-Dawley rat renal grafts wereorthotopically transplanted into Wistar rats following the procedure of Kamada with our modification. The recipients were divided into fourgroups(each group n=8): Group A, pseudo OP; Group B, 4 weeks group;Group C, 8 weeks group and Group D, 12 weeks group (4, 8 or 12 weeksafter operation, the recipients were sacrificed to harvest the renal allografts.).The expression of cytoprotective genes, A20, HO-1 and Bcl-X_L wereanalyzed in these grafted kidneys by real time quantitative polymerase chainreaction (RT-PCR) and immunohistochemistry. 3. The same CAN model wasconducted as part 2. The recipients were divided into five oral treatmentgroups: control group (cyclosporine [CsA] 10mg/kg.d×10d); CsA group (CsA10mg/kg.d×10d followed by CsA 6mg/kg.d); FK506 group (CsA10mg/kg.d×10d followed by FK506 0.15mg/kg.d); mycophenolate mofetil(MMF) group (converted from CsA 10mg/kg.d×10d to MMF 20mg/kg.d onday 11); rapamycin (RAPA) group (CsA 10mg/kg.d×10d followed by Rapa0.8mg/kg.d). At the same times after transplantation, the rats were sacrificedto harvest the renal allografts. The expression of cytoprotective genes A20,HO-1 and Bcl-X_L were analyzed in these grafted kidneys by quantitativeRT-PCR and immunohistochemistry.Results 1. A20 was detected in human renal allografts undergoing CAN butnot in normal kidney. Expression of HO-1 was almost undetected in graftsundergoing CAN. Bcl-X_L expressed both in grafts undergoing CAN andnormal kidneys. 2. There is a negative relationship between expression ofcytoprotective genes and Banff scores. 3. Immunosuppresants can improveexpression of cytoprotective genes A20, HO-1 and Bcl-X_L (P＜0.05). Theexpressions of A20 in the MMF or RAPA groups were significantly higherthan those in the CsA or FK506 groups (P＜0.05). Conclusion We demonstrated expression of cytoprotective genes in humanrenal grafts undergoing CAN and the negative relationship betweenexpression of cytoprotective genes and Banff scores. We also demonstratedthat various immunosuppressive regimens have different effects on theexpression of cytoprotective genes, especially A20. Further researches arenecessary to clarify the direct protective function for renal allograts ofcytoprotective genes and the mechanism of different immunosuppressiveregimens.