Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Transplant. Sep 24, 2016; 6(3): 573-582
Published online Sep 24, 2016. doi: 10.5500/wjt.v6.i3.573
Pharmacological Tie2 activation in kidney transplantation
Kristina Thamm, Florence Njau, Paul Van Slyke, Daniel J Dumont, Joon-Keun Park, Hermann Haller, Sascha David
Kristina Thamm, Florence Njau, Joon-Keun Park, Hermann Haller, Sascha David, Department of Nephrology and Hypertension, Medical School Hannover, 30625 Hannover, Germany
Paul Van Slyke, Daniel J Dumont, Vasomune Therapeutics Inc, Toronto M5G 1L7, Canada
Paul Van Slyke, Daniel J Dumont, Biological Sciences, Sunnybrook Research Institute, Toronto M4N 3M5, Canada
Author contributions: Thamm K, Njau F and Park JK performed research study; Van Slyke P and Dumont DJ contributed important reagents; Thamm K, Van Slyke P, Dumont DJ, Haller H and David S analyzed data; Thamm K and David S wrote the manuscript; David S designed the study.
Supported by The Else-Kröner Fresenius Stiftung, No. 2013_A154; and the German Research Foundation, No. DA 1209/4-1 (to David S).
Institutional review board statement: The study was reviewed and approved by the MHH Institutional Review Board.
Institutional animal care and use committee statement: All experiments were approved by the local authorities and conducted in accordance with institutional and governmental guidelines (AZ12/0843).
Conflict-of-interest statement: Vasculotide has been patented and is being commercialized by Vasomune Therapeutics. Van Slyke P and Dumont DJ are co-inventors of Vasculotide and Van Slyke P is the Chief Scientific Officer, while Dumont DJ sits on the Scientific Advisory Board. The remaining authors have disclosed that they do not have any potential conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Sascha David, MD, Department of Nephrology and Hypertension, Medical School Hannover, Carl Neuberg-Straße 1, 30625 Hannover, Germany. david.sascha@mh-hannover.de
Telephone: +49-511-5326319 Fax: +49-511-552366
Received: March 30, 2016
Peer-review started: March 31, 2016
First decision: May 17, 2016
Revised: June 24, 2016
Accepted: July 14, 2016
Article in press: July 18, 2016
Published online: September 24, 2016
Processing time: 177 Days and 13.9 Hours
Abstract
AIM

To investigate the therapeutic potential of vasculotide (VT) - a Tie2 activating therapeutic - in kidney transplantation.

METHODS

We performed a murine MHC-mismatched renal transplant model (C57Bl/6 male into Balb/c female) with 60 min cold and 30 min warm ischemia time. 500 ng VT was administered i.p. to donor mice 1 h before organ removal. In addition, recipients received 500 ng VT i.p. directly and 3 d after surgery. Survival was monitored and remaining animals were sacrificed 28 d after transplantation. In this model, we analyzed: (1) organ function; (2) Kaplan-Meier survival; (3) organ damage (periodic acid Schiff staining) via semi-quantitative scoring [0-4 (0 = no injury/inflammation to 4 = very severe injury/inflammation)]; (4) expression of renal endothelial adhesion molecules (ICAM-1) via immunofluorescence (IF) staining, immunoblotting and qPCR; (5) infiltration of inflammatory cells (IF Gr-1, F4/80); and (6) fibrosis via staining of α-smooth muscle actin (αSMA), Sirius red staining and immunoblotting of SMAD3 activation.

RESULTS

Exogenous activation of Tie2 with VT resulted in diminished expression of peritubular and glomerular endothelial adhesion molecules. Consequently, infiltration of inflammatory cells (analyzed as ICAM-1, Gr-1 and F4/80 positive cells) was reduced in VT-treated mice compared to controls. Additionally, VT was protective against fibrogenesis after kidney transplantation. Trends towards lower serum creatinine (vehicle: 142 ± 17 μmol/L vs VT: 94 ± 23 μmol/L), urea (vehicle: 76 ± 5 mmol/L vs VT: 60 ± 8 mmol/L) and lactate dehydrogenase (vehicle: 1288 ± 383 iU vs VT: 870 ± 275 iU) were observed on day 6 after transplantation. Kaplan-Meier survival analysis showed improved survival rates in the VT-treated mice that did not reach statistical significance (27% vs 54%, P = 0.24, n = 11 per group). Exogenous activation of Tie2 via VT might reduce infiltration of inflammatory cells into renal tissue thereby protecting the transplant from early graft dysfunction potentially affecting long-term function.

CONCLUSION

Protection of the endothelial microvasculature via the Tie2 axis in the early transplant setting might hold promise as a therapeutic target.

Keywords: Vasculotide; Tie2; Kidney transplantation; Endothelium; Angiopoietin

Core tip: Activation of the Tie2 receptor has been shown to be beneficial in different models of disease. Here, we demonstrate that agonistic stimulation of Tie2 via the drug-like putative therapeutic termed “vasculotide” (VT) ameliorates outcome in a murine MHC-mismatched kidney transplant model. VT treatment (i.e., activation of endothelial Tie2) prevented inflammation and fibrosis thereby preserving graft function. Moreover, single administration at the time of transplantation was also sufficient to prolong survival compared to control group.