Spatial Multi-omics of Arterial Regions from Cardiac Allograft Vasculopathy Rejected Grafts

Background Cardiac allograft vasculopathy (CAV) is a major cause of late-graft failure and mortality following heart transplantation. The mechanisms underlying vascular remodeling are poorly understood. A major immune risk factor associated with the development of CAV is the presence of donor-specific antibodies (DSA) that induce chronic endothelial cell (EC) injury, leukocyte recruitment and inflammation resulting in thickening of arterial intima. Here, we molecularly characterized innate and adaptive immune cells present in the arteries of rejected cardiac allografts with DSA and identified protein and transcriptomic signatures distinguishing early and late CAV lesions. Methods Arterial areas of interest (AOIs) from CAV+DSA+ rejected cardiac allografts (N=3; 2 females, 1 male) were subjected to GeoMx digital spatial profiling (DSP). AOIs were scored on the level of CAV progression/neointimal thickening (22 AOIs total; 11 high and 11 low neointima) and were subjected to whole transcriptome and protein profiling. Results AOIs with low neointima significantly increased markers for activated inflammatory infiltrates, transcripts of EC activation and gene modules involved in activating metalloproteinases and TP53 regulation of caspases. Inflammatory and apoptotic protein markers significantly correlated with inflammatory modules in AOIs with low neointima. AOIs with high neointima increased TGFβ-regulated transcripts and modules enriched for platelet activation/aggregation. Proteins encoding SMCs and growth factors/survival correlated with modules enriched for proliferation/repair in AOIs with high neointima. Key transcripts in promoting proliferation, migration, and EndoMT were significantly associated with increasing neointima scores. Conclusion Our results reveal new protein and transcriptomic signatures associated with CAV progression. Lesions exhibiting inflammatory profiles appear to be early lesions that transition to later proliferative/pro-fibrotic phenotype CAV lesions. These findings should form the foundation for the identification of improved biomarkers to guide CAV treatment. ### Competing Interest Statement The authors have declared no competing interest. * CAV : cardiac allograft vasculopathy AMR : antibody-mediated Rejection DSA : donor specific HLA antibodies EC : Endothelial cell HLA : human leukocyte antigen AOIs : areas of interest EMT : Epithelial-to-mesenchymal transition EndoMT : Endothelial-to-mesenchymal transition