Quantification of interstitial fibrosis by image analysis on routine renal biopsy 1 year after transplantation in patients managed by C2 monitoring of cyclosporine microemulsion.

BACKGROUND

Renal interstitial fibrosis (IF), the main histopathologic feature of chronic allograft nephropathy (CAN), may be an important surrogate endpoint for patient follow-up. IF is currently assessed by semiquantitative analysis, but automatic color image analysis may be a more reliable, reproducible method to evaluate IF. We performed a retrospective analysis to calculate IF on routine renal biopsies 1 year after transplantation.

METHODS

Data were obtained from MO2ART, a prospective multicenter trial in which the cyclosporine microemulsion dose was adjusted based on C(2) levels. We included 26 patients in whom routine renal biopsy at 1 year was available from two centers. For each biopsy, a section was analyzed by a program of color segmentation image that automatically extracted green-colored areas characteristic of IF. Results were expressed as percent IF and grade namely grade I, <25%; grade II, 25% to 50%; and grade III, >50%. The results were compared according to clinical and biological data.

RESULTS

The 26 patients had a mean IF score of 0.35 +/- 0.04. We observed 34.6% CAN grade I; 46.1%, grade II; and 19.2%, grade III. Serum creatinine at 3 years was greater in the higher grade of automated IF by repeated ANOVA.

CONCLUSION

Automatic quantification of IF on routine biopsy at 1 year after transplantation was predictive of renal outcome. This technique may provide an interesting tool for the early diagnosis of CAN after renal transplantation.