Characterizing arterial lesions in cardiac allograft vasculopathy rejected grafts using NanoString GeoMx digital spatial profiling

Abstract

Cardiac allograft vasculopathy (CAV) is the leading cause of graft failure following heart transplantation. Donor specific antibodies (DSA) contribute to CAV by triggering vessel inflammation and endothelial cell injury. This results in thickening of the arterial intima and vessel occlusion. In this study, we aim to define the innate and adaptive immune cells mediating inflammation and vessel neointima formation using CAV+DSA+ rejected cardiac explants (N=3) and GeoMx digital spatial profiling (DSP). Arterial regions containing macrophages (CD68+CD163+) within vessels (CD34+) were selected for whole genome sequencing and a 76-protein panel. Arteries were scored as containing ‘low’ or ‘high’ neointima based on H&E. A total of 41 proteins including markers of inflammation and apoptosis were found to be expressed in all arteries. The expression of CD8, CD56, CD20, CD127, and CD11c exhibited a significantly positive correlation with RNA counterparts. A total of 15 differentially expressed proteins (e.g., T-cell makers: CD8, CD45RO, and CD127), and high expression of genes related to inflammation (ITGAX), and apoptosis (TP63), along with pathways for antigen presentation were elevated in arteries with low neointima. High neointima arteries showed higher SMA protein expression and increased genes related to cell growth (LECT2), complement regulation (CFHR3) and anti-inflammatory factors (FNDC4). Enriched pathways in high neointimal arteries included platelet activation/degranulation and cell migration. Our results provide insight into the mechanisms mediating CAV progression seen by inflammatory profiles in arteries with low neointima followed by pro-fibrotic/reparative phenotypes in high neointima arteries. This work is funded by the Ruth L. Kirschstein National Research Service Award (NRSA) T32HL069766 (UCLA Vascular Biology Training grant), the Eugene V. Cota Robles Fellowship and NIH Grant 441450 ER 29762