Biomarkers for the Diagnosis of the Stable Kidney Transplant and Chronic Transplant Injury Using the ProtoArray® Technology

Transplant glomerulopathy (TG), a form of chronic renal transplant rejection, carries a poor prognosis. It must be differentiated from the entity defined by the Banff '05 classification, interstitial fibrosis/tubular atrophy (IF/TA). Sequential transplant biopsies have shown that these lesions are subclinical long before clinical manifestations. The availability of biomarkers may provide an earlier diagnosis and subsequent treatment. The aim of our study was to identify serum biomarkers in kidney recipients showing TG compared with IF/TA or stable patients, using protein microarray technology. This technology detects auto- or alloantibodies in patient sera. With a high degree of statistical significance, we identified 18 antibody reactivities specific for TG; 11 for IF/TA; and 10 among stable patients. Target proteins were involved in signal transduction, transcription regulation, DNA replication and repair, cell cycle, endocytosis, cell redox, as well as glycolysis. Some markers, such as podocan and collagen XXIII among TG and tubular cell ion channels among IF/TA, possibly provide insights into the pathogenesis of the lesions.