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Abstract: PO1989

Noncanonical PAR-1 Signalling Leads to Profibrotic Effects in Podocytes in Response to Steroid-Resistant Nephrotic Syndrome Disease Plasma

Session Information

  • Podocyte Biology
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Chesor, Musleeha, University of Bristol, Bristol, Bristol, United Kingdom
  • Tuffin, Jack P., University of Bristol, Bristol, Bristol, United Kingdom
  • May, Carl J., University of Bristol, Bristol, Bristol, United Kingdom
  • Welsh, Gavin Iain, University of Bristol, Bristol, Bristol, United Kingdom
  • Saleem, Moin, University of Bristol, Bristol, Bristol, United Kingdom

Group or Team Name

  • Bristol Renal
Background

Post-transplant recurrence of 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 works suggest a role for protease-activated receptor-1 (PAR-1) involving an unknown circulating protease leading to increased podocyte motility. We have now further elaborated the signalling pathways downstream of PAR-1, which suggests pro-fibrotic activation in podocytes.

Methods

Conditionally immortalised human podocytes (ciPods) were treated with PAR-1 agonist peptide or post-transplant SRNS relapse and paired-remission plasma with or without PAR-1 antagonists, RWJ 56110, SCH 79797, Vorapaxar, and FR171113. ciPods were also treated with TGF-β1 or SRNS plasma along with SB-43152, an effective TGF- β1 receptor inhibitor. A new 3D co-culture glomerular spheroid model was used to study both signalling pathways and podocyte loss.

Results

We found that PAR-1 agonist and patient relapse disease plasma, but not paired remission plasma significantly induced the phosphorylation of VASP, JNK, and proteins involved in pro-fibrotic pathways. These changes were inhibited by co-incubation of ciPods with certain PAR-1 inhibitors, but not by TGFb1 inhibitor. These four PAR-1 inhibitors demonstrate distinct antagonistic properties and among 4 inhibitors, only FR17113 was effective in inhibiting effects of relapse plasma, suggesting a non-canonical agonism of PAR-1 by disease plasma. The phosphorylation of VASP and JNK on a 3D spheroid model corroborates the finding from a 2D ciPods model. Functionally, the circulating factor enhanced podocyte motility and podocyte loss.

Conclusion

We propose that the SRNS circulating factor acts as a pro-fibrotic effector that can activate PAR-1 leading to increased podocyte injury. A greater understanding of these signalling pathways will lead to the identification of novel therapeutic targets for this disease.

Funding

  • Government Support - Non-U.S.