Determinants of Vascular Calcification in Chronic Renal Failure : Impact of Pyrophosphate Levels After Renal Transplantation

Arterial calcifications (AC) are constant lesions in patients with Chronic Kidney Diseases (CKD). Renal transplantation would reduce their progression compared to dialysis. AC pathophysiology is a complex and finely regulated process that involves many local and systemic factors, both pro- and anti-calcification. The progression of the CKD is accompanied by an increase in phosphate levels as the renal excretion capacity of inorganic phosphates (Pi) decreases while their digestive absorption remains unchanged. Hyperphosphatremia is a well-identified calcifying factor contributing to ACs in the CKD. On the other hand, pyrophosphate (PPi) is an anti-calcifying factor from the hydrolysis of extracellular ATP by ectonucleotidases. While there are many factors that may contribute to a protective effect against AC progression of renal transplantation, no study has been yet analysed the role of PPi. Plasma concentration of PPi is decreased in dialysis patients compared to non-kidney failure patients.

The main objective of this monocentric, prospective and interventional pilot study will be to compare the progression of CA and [PPi]pl between a group of renal transplant patients over the past 24 months and a group of dialysis patients over the same period of time. The secondary objectives will be to compare the progression of ACs and the ratio[PPi]pl/[Pi]pl between transplanted and dialysis patients. Transplanted patients will be included within 24 (±3) months of transplant. Dialysis patients will be included at 24 (±3) months of the CT scan performed during the pre-transplant check-up. At inclusion, all patients will benefit from a CT scan without injection and a plasma dose of PPi, Pi and other factors involved in controlling calcification.