WNT Pathway Signalling in Kidney Transplants with Microvascular Injury

Kidney transplant recipients with biopsy-proven microvascular injury (MVI) have increased risk for allograft failure. MVI is often caused by antibody-mediated injury that is resistant to available treatments. Current diagnostic methods are also inadequate, with interobserver variability in traditional pathology reads, variable assessment of circulating donor-specific antibody between HLA laboratories, and peritubular capillary C4d staining. Molecular assessments of kidney biopsies can provide improved sensitivity for diagnosing MVI and other allograft pathology, while improving reproducibility and objectivity. Most molecular classifiers have been based on whole genome sequencing to develop diagnostic tests, but have provided limited therapeutic targets. In this study, we pursued a candidate gene approach to measure WNT pathway genes in residual clinical FFPE biopsies with and without MVI. We focused on the WNT pathway because of previous translational studies that implicated this pathway in chronic renal allograft injury as well as vascular injury in native chronic kidney disease. Case-control study of 95 residual FFPE biopsies with MVI (g+ptc score >= 2, n=50) or Stable (g+ptc score < 2 and no other major abnormalities, n=45). Biopsies were retrieved from a biorepository of over 500 kidney transplant biopsies. We compared expression of 180 WNT pathway genes and 30 custom skipe-in targets (derived from previous studies of endothelial injury in transplantation) between MVI and Stable groups, with correction for multiple comparisons using FDR < 5%.