Abstract 4142867: Dysregulated AP-1 Expression in Monocyte in Recurrent In-Stent Restenosis: Insights from Human Coronary Artery Blood Single-Cell Sequencing

Aims: Recurrent in-stent restenosis (RISR) refers to a second event of ISR after successful revascularization procedures of an initial ISR lesion. However, due to its unclear pathogenesis, effective treatment methods are lacking in clinical practice. Therefore, this study aims to investigate the potential mechanisms underlying RISR pathogenesis from an immunological perspective using single-cell RNA sequencing (scRNA-seq), to provide theoretical support for clinical interventions. Methods: Single-cell RNA sequencing was conducted to profile coronary blood mononuclear cells (CBMCs) obtained from 10 patients with recurrent in-stent restenosis (RISR) and 10 control individuals without ISR one year after stent implantation. The potential pathogenic pathway was identified through comprehensive bioinformatics analyses and further validated at the cellular level by isolating monocytes via flow cytometry from the coronary blood of patients in the RISR validation cohort (n=8). Results: RISR altered the proportion of monocyte subtypes, including an increasing trend in FCGR3A+ Monos and a decrease in MHC-II+ Monos. And a marked elevation of activator protein-1 (AP-1) complex within monocytes was identified as key contributor to the unique transcript profile observed in RISR. Evidence at both the RNA and protein levels demonstrated that in RISR patients, CCL5 secreted by T cells can specifically interact with CCR1 of monocytes, thereby upregulating the p38 MAPK/AP-1/inflammatory cytokine axis. Furthermore, co-culture experiments revealed that these monocytes with heightened expression of inflammatory cytokines can indeed promote the proliferation and migration of endothelial cells (EC) and smooth muscle cells (SMC), thus contributing to the occurrence and progression of RISR. Conclusion: Our study provides the first depiction of immunological landscape in the coronary blood of RISR patients. The upregulation of the CCR1/p38 MAPK/AP-1/cytokine axis in monocytes is a critical mechanism that facilitates RISR. Our study fills the gap in the understanding of RISR pathogenesis and holds significant implications for guiding clinical interventions.