Approximately 30% of renal transplant patients develop recurrence of FSGS in the first kidney allograft. AT1R is expressed on podocytes; its expression is elevated in the proteinuric state. This prompted us to test the pre-transplant sera of patients with history of biopsy proven FSGS for AT1R antibody levels along and serum soluble urokinase-type plasminogen activator receptor (suPAR) as a biomarker for risk of recurrence of FSGS after transplant.

Methods: Pre-transplant sera of 39 patients (FSGS 28, polycystic kidney disease [PKD] 11 as controls) were collected and stored at -80oC until testing in batch for anti-AT1R and suPAR under an IRB approved protocol. AT1R antibody and suPAR levels were measured using ELISA (One Lambda®, Canoga Park, CA) and suPAR ELISA kit.

Results: Twelve patients had biopsy proven post-transplant FSGS recurrence at 1.5 months. No difference was found in the pre-transplant suPAR levels of FSGS patients (5993±2292pg./mL)vs.PKD (7334±4538pg./mL),(p= 0.23)..Serum suPAR levels in patients with FSGS recurrence (5786±1899pg./mL) vs. no FSGS recurrence(6149±2598pg./mL)(p= 0.69) were not different.. Mean AT1R antibody levels in patients with FSGS were 12.66±11.85 U/mL vs. 8.69±6.52 U/mL in PKD (p= 0.32), however, a difference was found in patients with 20.41±14.36 U/ml and without FSGS recurrence 6.84±4.181 U/mL (p<0.01). Area under curve for suPAR and AT1R to predict post-transplant FSGS recurrence was 0.51 and 0.84 respectively.

Conclusion: Pre-transplant anti-AT1R antibody levels appear to be a helpful biomarker in identifying patients at high risk of post-transplant FSGS recurrence. More studies are needed to confirm our findings.

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