Abstract 12560: Single Cell RNA Sequencing Signature of Cardiac Allograft Vasculopathy

Abstract

Background: Cardiac allograft vasculopathy (CAV) is one of the major causes of death after heart transplantation (HTx). However, immunological mechanisms of CAV remain incompletely understood. This study aimed to determine distinct immune profiles of CAV compared to HTx patients with normal graft function (CONTROL). Methods: Peripheral blood mononuclear cells (PBMC) obtained from the International Society for Heart and Lung Transplant grade 2 or 3 CAV (n=6), and CONTROL (n=12) patients were analyzed using single cell RNA sequencing (498 genes) on the BD Rhapsody platform combined with 56 protein markers (CITE-seq) and VDJ-seq. Cells were clustered into major cell types using 18 protein markers. Targeted clustering was then performed to determine subclusters using proteomic and transcriptomic data. Results: Proportions of memory B cell (0.5±0.4% vs 1.4±0.8%, p=0.01) and CD16+CD56+ TEMRA CD8 T cell (0.5±0.3% vs 1.0±1.7%, p=0.007) were decreased and proportion of C1q+ nonclassical monocyte (1.0±0.5% vs 0.4±0.3%, p=0.01) was increased in CAV patients compared to CONTROL. In Th1 effector memory CD4 T cell cluster, CAV had a significantly higher proportion of clonally expanded cells (24.1±10.0% vs 11.3±9.2%, p=0.01) characterized by higher expression of NKG7, GZMH, CCL5, and CST7 compared to non-expanded cells in this cluster. Signature genes with the highest positive coefficients determined by LASSO regression to predict CAV (72.2% accuracy) included IFITM3, LAIR2, CD52, IFITM2, NKG7, NAMPT, CD74, F13A1, IL3RA, and RNASE2. IFITM3 and LAIR2 were the best positive predictors for CAV and overexpressed predominantly in CD4 T and CD8 T cells (Figure). Conclusion: CAV demonstrates distinct immune cellular and transcriptomic phenotypes compared to CONTROL. IFITM3 and LAIR2 overexpression in PBMCs may predict severe CAV in HTx patients.