Subclinical effects of remote ischaemic conditioning in human kidney transplants revealed by quantitative proteomics

Background: Remote ischaemic conditioning (RIC) is currently being explored as a non-invasive method to attenuate ischaemia/reperfusion injuries in organs. A randomised clinical study (CONTEXT) evaluated the effects of RIC compared to non-RIC controls in human kidney transplants. Methods: RIC was induced prior to kidney reperfusion by episodes of obstruction to arterial flow in the l eg opposite the transplant using a tourniquet (4 x 5min). Although RIC did not lead to clinical improvement of transplant outcomes, we explored whether RIC induced molecular changes through precision analysis of CONTEXT recipient plasma and kidney tissue samples by high-resolution tandem mass spectrometry (MS/MS). Results: We observed an accumulation of muscle derived proteins in kidney tissue proteomes and altered mitochondrial proteins, likely provoked by RIC, which was not reflected in plasma. In addition, MS/MS analysis demonstrated transient upregulation of several acute phase response proteins (SAA1, SAA2, CRP) in plasma, 1 and 5 days post-transplant. RIC showed a lower magnitude change when compared to non-RIC. However, RIC did not have a consistent effect on the magnitude of acute inflammation following clinical intervention. Conclusions: Together, our results indicate sub-clinical systemic and organ-localised effects of RIC.