The Clinical Significance of the Hypoxia Inducible Factor-1 alpha and C4d in Implantation Renal Biopsies and Post-transplant Biopsies

Kim, Soo Jin; Kim, Doo Jin; Kim, Joo Seop; Park, Sung Gil; Oh, Ji Eun; Nam, Eun Sook; Lee, Samuel

Abstract

PURPOSE: Hypoxia inducible factor-1 alpha (HIF-1 alpha) is induced in response to ischemic states and in turn activates transcription of several growth factors implicated in cell survival. These growth factors have been recognized as role players in the development of chronic allograft nephropathy (CAN). C4d depositions in the peritubular capillaries of renal allografts have been reported to be sensitive markers of acute humoral rejection. The purpose of this study was to determine the effects of HIF-1 alpha expression and C4d deposition in implantation biopsies of renal allografts.
METHODS
Implantation biopsies and 22 rejection proven biopsies of 54 renal transplantation recipients (Male:Female=31:23) in Kangdong Sacred Heart Hospital from December 1996 to July 1999 were done. Immunohistochemical studies were performed using mouse monoclonal antibody (1:1000, Novus Biological Inc., Littleton, CO, USA) as the primary antibody and CSA (Catalyzed Signal Amplification System, Dako, Denmark) as the secondary antibody for HIF-1 alpha. Rabbit polyclonal antibody (1:200 Biogenesis, UK) and DAB kit (Dako) were used for C4d detection. Expression of HIF-1 alpha was defined as positive nuclei staining under 10 HPF (high power field) and C4d deposition was defined as 1+ when the pericapillary deposition was under 50% and 2+ when over 50% and 0 when there were no traces of depo sition.
RESULTS
HIF-1 alpha was demonstrated in 19 cases (35%) of the 54 implantation biopsy cases. The expression of HIF-1 alpha was statistically higher in the deceased donor group compared to the living donor group. The HIF-1 alpha positive group had a longer mean cold ischemic time than the HIF-1 alpha negative group but was not statistically significant. The age of the donor and HIF-1 alpha expression showed no correlation. Expression of HIF-1 alpha of the implantation biopsies also showed no difference in the rejection group (n=22) compared to the non-rejection group (n=32). There was no significant difference of HIF-1 alpha expression in the graft loss group (n=7) and the graft functioning group (n=47). C4d deposition was detected in one implantation allograft biopsy (1.9%). The C4d positive patient developed acute accelerated rejection on the fourth postoperative day. HIF-1 alpha and C4d were demonstrated in 22 (100%) and 11 (50%) of the 22 rejection biopsies, respectively. In patients who showed rejection, HIF-1 alpha expression was significantly higher in the rejection biopsies compared to the implantation biopsy group. HIF-1 alpha expression of the patients who showed rejection within one month and those with rejection later than three months after engraftment showed no significant difference.
CONCLUSION
Expression of HIF-1 alpha in implantation biopsies showed significant correlation with deceased kidney donors. The relation with cold ischemic time was not statistically proven but the HIF-1 alpha positive group showed a tendency of longer cold ischemic time. Biopsies from the renal allografts with rejection showed significantly higher expression of HIF-1 alpha compared to the implantation biopsies. The deposition rate of C4d was extremely low in implantation biopsies that we could not prove any relevance with acute rejection.