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Abstract: FR-PO940

Plasma Circulating Factors in Recurrent Nephrotic Syndrome Increases Podocyte Motility via Signalling Pathways That Mimic PAR-1 Activation

Session Information

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Chesor, Musleeha, University of Bristol, Bristol, United Kingdom
  • May, Carl J., University of Bristol, Bristol, United Kingdom
  • Hayes, Bryony, University of Bristol, Bristol, United Kingdom
  • Welsh, Gavin Iain, University of Bristol, Bristol, United Kingdom
  • Saleem, Moin, University of Bristol, Bristol, United Kingdom
Background

Post-transplantation recurrence steroid resistant nephrotic syndrome (SRNS) is thought to be due to the presence of an unknown “circulating factor” the identity of which has so far remained elusive. Our previous work suggests that an unknown circulating protease in recurrent SRNS plasma signals to podocytes through protease activated receptor-1 (PAR-1), a G-protein-coupled-receptor and alters the actin cytoskeleton leading to increased podocyte motility via phosphorylation of vasodilator-stimulated phosphoprotein (VASP) a known actin cytoskeleton regulator. We have now further elaborated this signalling pathway in podocytes with the hypothesis that the circulating factor(s) in FSGS relapse plasma will initiate specific signalling pathways via PAR-1 receptor to the podocyte cytoskeleton and this consequently leads to increased podocyte motility and proteinuria.

Methods

Conditionally immortalised human podocytes (ciPods) were treated with 1) PAR-1 agonist; 2) Relapse and paired-remission plasma from FSGS patients, along with three different PAR-1 inhibitors, Vorapaxar, SCH 79797, and FR17113. A scratch assay was performed to determine the motility of ciPods after treatment with FSGS plasma. A mouse model of podocyte specific constitutively active PAR-1 was generated.

Results

We found that PAR-1 agonist and patient relapse disease plasma but not remission plasma from the same patient induced phosphorylation of VASP and JNK, a member of the mitogen-activated protein kinases (MAPK) superfamily in human podocytes, and increased motility compared to relevant controls. These changes were blocked by co-incubation of cells with certain PAR-1 inhibitors. These three PAR-1 inhibitors demonstrate distinct antagonistic properties and among 3 inhibitors, only FR17113 was effective, suggesting a non-canonical agonism of PAR-1 by disease plasma. The PAR1active mouse developed FSGS and upregulation of VASP, MAPK and JNK in podocytes by D8.

Conclusion

We reveal a consistent signalling pathway in ‘circulating factor’ SRNS that leads to increased podocyte motility and proteinuria and suggests direct therapeutic targets.

Funding

  • Government Support - Non-U.S.