2011 - IPITA - Prague


This page contains exclusive content for the member of the following sections: TTS, IPITA. Log in to view.

Parallel session 11 – Open oral presentations Topic: Experimental islet transplantation: Cell biology

11.9 - Protease-activated recetor-1 (PAR-1) activation by thrombin is protective in human islets if the endothelial protein C receptor (ECPR) is occupied

Presenter: H.S., Smith-Hurst, Sydney , Australia
Authors: H.S. Smith-Hurst, W.J. Hawthorne, P.J. O'Connell


Protease-activated recetor-1 (PAR-1) activation by thrombin is protective in human islets if the endothelial protein C receptor (ECPR) is occupied

H.S. Smith-Hurst, W.J. Hawthorne, P.J. O'Connell
University of Sydney (Westmead Hospital), Centre for Transplant and Renal Research, Sydney, Australia

Objectives: Our previous studies have indicated that Activated Protein C (APC) exerts anti-inflammatory activities during the Instant Blood Mediated Inflammatory Reaction (IBMIR). The mechanisms for the anti-inflammatory response are unclear. The aim of this study was to determine if APC leads to recruitment of PAR1 to protective signalling pathways through coupling of PAR1 to the Gi-protein.

Methods: Human Islet cells were exposed to specific PAR1 agonist peptides (PAR-APs). Receptor and protein expression was determined by RT-PCR and western blot assays analysis and measurement of pro-coagulant activity was performed by clotting assays.

Results: When protein C is bound to ECPR, PAR1 cleavage dependent protective signalling responses in islets can be mediated by thrombin or APC. To confirm that the occupancy of EPCR by its natural ligand protein C switches the signalling specificity of thrombin from a pro-inflammatory to anti-inflammatory response, we monitored the clotting of islets which were treated with PAR1-agonist peptides (PAR1-APs). Prior treatment of islets to block ECPR via APC with thrombin resulted in a protective effect in a concentration dependent manner by reducing clot formation 5-fold with optimal effect at 50nM. Clotting was also significantly reduced 4-fold when islets treated with PAR1-AP were reversed by the addition of APC. Thrombin in the presence of EPCR blocking inhibited clot formation with an optimal concentration of 20nM thrombin. The protective effects were PAR-1 and ECPR dependent since functional-blocking antibodies to either receptor abrogated the protective response of APC as well as thrombin with ECPR blocking. Islets treated with TNF-α induced apoptosis. APC inhibited cell death by a concentration dependent manner.

Conclusions: These results suggest that cleavage of PAR-1 by thrombin in human islets elicits protective responses if EPCR is occupied by protein C. The results provide new understanding of how PAR1 and APC participate in protective signalling events in IBMIR.


Important Disclaimer

By viewing the material on this site you understand and accept that:

  1. The opinions and statements expressed on this site reflect the views of the author or authors and do not necessarily reflect those of The Transplantation Society and/or its Sections.
  2. The hosting of material on The Transplantation Society site does not signify endorsement of this material by The Transplantation Society and/or its Sections.
  3. The material is solely for educational purposes for qualified health care professionals.
  4. The Transplantation Society and/or its Sections are not liable for any decision made or action taken based on the information contained in the material on this site.
  5. The information cannot be used as a substitute for professional care.
  6. The information does not represent a standard of care.
  7. No physician-patient relationship is being established.

Social

Contact

Staff Directory
+1-514-874-1717
info@tts.org

Address

The Transplantation Society
International Headquarters
740 Notre-Dame Ouest
Suite 1245
Montréal, QC, H3C 3X6
Canada