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Kidney Week

Abstract: TH-OR52

Proteomics Reveals Extracellular Matrix Injury in the Glomeruli and Tubulointerstitium of Kidney Allografts with Early Antibody-Mediated Rejection

Session Information

Category: Transplantation

  • 1901 Transplantation: Basic

Authors

  • Clotet Freixas, Sergi, University Health Network, Toronto, Ontario, Canada
  • McEvoy, Caitriona M., University Health Network, Toronto, Ontario, Canada
  • Pastrello, Chiara, University Health Network, Toronto, Ontario, Canada
  • Kotlyar, Max, University Health Network, Toronto, Ontario, Canada
  • Arambewela, Madhurangi, University Health Network, Toronto, Ontario, Canada
  • Boshart, Alexander, University Health Network, Toronto, Ontario, Canada
  • Farkona, Sofia, University Health Network, Toronto, Ontario, Canada
  • Niu, Yun, University Health Network, Toronto, Ontario, Canada
  • Li, Yanhong, University Health Network, Toronto, Ontario, Canada
  • Chruscinski, Andrzej, University Health Network, Toronto, Ontario, Canada
  • John, Rohan, University Health Network, Toronto, Ontario, Canada
  • Konvalinka, Ana, University Health Network, Toronto, Ontario, Canada
Background

Antibody-mediated rejection (AMR) accounts for >50% of kidney allograft losses. AMR is caused by donor-specific antibodies (DSA) against HLA and non-HLA antigens in the glomeruli and the tubulointerstitium, which together with interferon gamma and tumor necrosis factor-alpha (TNFα), trigger graft injury. The reasons behind cell-specific injury in AMR remain unclear. Identifying compartment-specific proteome alterations may help uncover mechanisms of early antibody-mediated injury.

Methods

We studied 30 for-cause kidney biopsies with early AMR, acute cellular rejection (ACR) or acute tubular necrosis (ATN). We laser-captured microdissected glomeruli and tubulointerstitium and subjected them to unbiased proteome analysis.

Results

We found 107 glomerular and 112 tubulointerstitial proteins significantly differentially expressed in AMR vs. ACR. Similarly,112 (glomeruli) and 124 (tubulointerstitium) proteins were regulated in AMR vs. ATN. Basement membrane and extracellular matrix (ECM) proteins were decreased in both compartments in AMR, compared with ACR and ATN. We verified decreased glomerular and tubulointerstitial LAMC1 expression, and decreased glomerular NPHS1 and PTPRO expression in AMR. Cathepsin-V (CTSV) was predicted to cleave ECM-proteins in the AMR glomeruli. We identified galectin-1, an immunomodulatory protein upregulated in AMR glomeruli and linked to the ECM. Examination of publicly available data revealed that galectin-1 is increased at the gene level in AMR. Anti-HLA class-I significantly increased CTSV expression, and galectin-1 expression and secretion, in human glomerular endothelial cells. We also studied glutathione S-transferase omega-1 (GSTO1), an ECM-modifying enzyme, increased in the AMR tubulointerstitium. GSTO1 expression was significantly increased in TNFα-treated proximal tubular epithelial cells.

Conclusion

Basement membranes are often remodeled in chronic AMR, and we demonstrated that this remodeling begins early in glomeruli and tubulointerstitium. Targeting ECM-remodeling in AMR may represent a new therapeutic avenue.