Chronic Transplant Glomerulopathy and Regulation of Expression of Ephrin B1

Chronic transplant glomerulopathy (CTG) is a specific lesion of kidney transplantation and a poor prognostic factor affecting transplant survival. Diagnosis remains only microscopic and lesions are irreversible. Recent studies prove that there is a strong correlation between CTG and antibody mediated rejection (AMR) with a possible link with chronic aggression of the endothelial cell. However, for unknown reason, all AMR does not lead to a CTG. Our recent data on mice demonstrated that ephrin-B1 is expressed in the glomerular endothelial cells and knockout mice for the gene encoding ephrin-B1 develop progressively ultrastructural glomerular lesions close to modifications observed in CTG, as well as proteinuria and chronic renal failure, suggesting that ephrin B1 could participate to CTG. Moreover, in a preliminary study on human kidney transplant biopsy we observed decrease in ephrin-B1 immunofluorescence on glomerulus when CTG, even in low grade. These data, and ultrastructural modifications in Knock Out (KO) mice suggest that early regulation of kidney expression of ephrin-B1 in the glomerulus may occur during the process leading to the CTG as antibody-mediated kidney rejection (AMR).

The purpose of the study is to determinate if ephrin-B1 expression is modified in CTG.

Inclusion criteria

• Kidney transplant patient for whom renal biopsies are stored in the "collection of the University Hospital Toulouse" (collection N° DC-2009-989) and who received information on the purpose of the study, use of biopsies and who has not manifested any opposition.
• Kidney transplant patient with iterative biopsies with at least: post-surgery biopsy D0 (or early post-transplant biopsy D7 and at least one biopsy protocol. - Age> 18 years Case group: - Kidney transplant patient, followed up by "organ transplant unity" of CHU Toulouse, with antecedent of CMR progressing to CTG between 2006 and 2013. Control group: - Kidney transplant patient, followed up by "organ transplant unity" of CHU Toulouse, with antecedent of CMR without progressing to CTG between 2006 and 2013

Exclusion criteria

• patient with uncontrolled hypertension - patient with diabetes mellitus -
• patient treated or who was treated with mTOR inhibitor - recurrence of the initial glomerular pathology - de novo glomerulopathy - patient including in another study with an exclusion period still going