Kidney Week

Abstract: FR-OR48

Cyclosporine-Induced Endothelial Injury and Complement Activation Is Caused by Impaired Complement Factor H Binding to the Glycocalyx

Session Information

• In-Depth Look at Transplantation: Basic and Translational
  October 23, 2020 | Location: Simulive
  Abstract Time: 05:00 PM - 07:00 PM

Category: Transplantation

• 1901 Transplantation: Basic

Authors

• Teoh, Chia Wei, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Chia Wei Teoh, MBChB



Dr Chia Wei Teoh is a paediatric nephrologist at The Hospital for Sick Children and Assistant Professor in the Department of Paediatrics at the University of Toronto. His clinical and research interests focuses on complement-mediated injury in transplantation and improving long-term outcomes in paediatric kidney transplantation.

• Ortiz, Carolina, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Carolina Ortiz,

• Riedl Khursigara, Magdalena, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Magdalena Riedl Khursigara,

• Bruno, Valentina, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Valentina Bruno,

• Robinson, Lisa, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Lisa Robinson,

• Licht, Christoph, The Hospital for Sick CHildren, Toronto, Ontario, Canada

Christoph Licht,

Background

Calcineurin inhibitors are associated with nephrotoxicity, endothelial cell (EC) dysfunction and thrombotic microangiopathy. Evolving evidence suggests a central role for complement dysregulation in the pathogenesis of CNI-induced thrombotic microangiopathy. However, the exact mechanism of calcineurin-induced complement-mediated injury remains unknown.

Methods

In an in-vitro model utilising Blood Outgrowth EC (BOEC) from healthy donors, we evaluated the effects of cyclosporine (CsA) on EC injury, complement activation (C3c, C9) and regulation (CD46, CD55, CD59 and complement factor H [CFH]) on EC surfaces, and on the EC glycocalyx, utilising flow cytometry, Western blot, and immunofluorescence imaging. Functional activity of CFH was assessed via CFH co-factor assay. Co-immunoprecipitation of Angiopoietin-2 (Angpt-2), Angiopoietin-1 (Angpt-1) and Tie2 was assessed by Western blot.

Results

CsA resulted in a dose and time dependent enhancement of EC complement deposition and EC death. CsA (10 µg/ml for 24 h) led to upregulation of CD46, CD55 and CD59 on EC surface. CsA led to Angpt-2 mediated breakdown of the EC glycocalyx, which was mitigated by Angpt-1. This EC glycocalyx breakdown led to decrease in CFH surface binding and surface cofactor activity.

Conclusion

Our findings confirm a role for complement in CsA-induced EC injury, and suggest Angpt-2 mediated glycocalyx abolishment, induced by CsA, as a mechanism leading to complement alternative pathway dysregulation via decreased CFH surface binding. Insights into this mechanism may provide a potential therapeutic target that might lead to improved patient outcomes which is subject to further studies. It might also apply to other thrombotic microangiopathies, in which a role for complement has so far not been recognized.