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Abstract: SA-PO1129

Angiotensin II Type I Receptor (AT1R) Antibody-Associated Collapsing FSGS in a Renal Allograft

Session Information

Category: Trainee Case Report

  • 1902 Transplantation: Clinical

Authors

  • Pandit, Amar, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Agrawal, Nikhil, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Malvar, Grace, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Cardarelli, Francesca, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Heher, Yael K., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Aala, Amtul, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
Introduction

Post renal transplant de novo collapsing FSGS could be associated with AT1R antibody.

Case Description

A 66-year-old man with type 2 diabetes mellitus underwent pre-emptive renal transplant for CKD of unproven etiology. He was HLA high risk with low level donor-specific DP1 antibodies and was induced with ATG and maintained on mycophenolate, tacrolimus and prednisone. Cytotoxic and flow cytometry cross matches were negative. Four weeks later he was noted to have proteinuria, which soon progressed to nephrotic range, while creatinine remained at baseline (1 mg/dl). Kidney biopsy was suggestive of acute humoral rejection with G1 glomerulitis, mild PTCitis and 60% C4d. HLA screen showed persistent low-level antibodies against DR52. Endothelial cell cross match was positive, indicating a non-HLA antibody mediated process. Treatment was initiated with pulse steroids, IVIG, plasmapheresis. AT1R antibody level was 14 units/ml (borderline) at 2 weeks and progressed to >40 units/ml at 4 weeks, following which he was started on Losartan and PLEX extended to 15 sessions. 3 months after the transplant, nephrotic range proteinuria persisted (10-12 g), however further escalation of immunosuppression was prevented by disseminated trichophyton infection and recurrent surgical site abscesses. Creatinine had increased to 2.4 mg/dl and a repeat biopsy showed diffuse collapsing glomerulopathy. C4d remained diffusely positive. Allograft function continued to decline and he returned to dialysis 8 months post-transplant.

Discussion

AT1R receptor is highly expressed on endothelial cells and podocytes and antibodies against it are known to cause acute humoral rejection. AT1R antibodies could potentially cause FSGS by enhancing the effects of AT II, which regulates matrix synthesis and cell proliferation. It also enhances the expression of transient receptor potential cation channel 6, which leads to FSGS in animal models. This report illustrates a case of AT1R antibody mediated humoral rejection with progression to an unusual clinical presentation (de novo collapsing FSGS), which was resistant to aggressive therapy.