Abstract 1028: Cytotoxic CD4+ T Cells: Unraveling The Residual Risk In Lipid Lowering For Type 2 Diabetes Patients

Abstract

Type 2 Diabetes (T2D) significantly increases the risk of cardiovascular diseases (CVDs), marked by severe plaque pathology resistant to standard cholesterol-lowering treatments. While the roles of the innate immune system and macrophages in CVDs are well-established, T cell alterations, particularly involving cytotoxic CD4 T cells (CD4 CTLs), remain unexplored in human atherosclerotic plaques. In our study, we aimed to identify the phenotype and function of CD4 CTLs in blood & plaque tissue, in the context of T2D. Using unbiased single-cell RNA sequencing (scRNA-seq) analysis, we examined over 70,000 immune cells from 22 plaques of patients undergoing carotid endarterectomy (T2D: n=12, Non-Diabetic (ND): n=10), & peripheral blood mononuclear cells (PBMCs) from the CHORD study (NCT04369664) (T2D: n=12, ND: n=4). scRNA-seq analysis revealed a diverse population of CD4 T cells, like naïve, central memory (CM), effector memory (EM), tissue resident memory (Trm), T regulatory (Tregs), & two clusters of cytotoxic (CTL) T cells expressing canonical cytotoxicity-related genes. Cluster 5 expressed GZMB, GNLY, PRF1 , whereas Cluster 10 expressed GZMA, GZMK . Cell-cell communication analysis demonstrated that both CTL clusters received signaling from dendritic cells and macrophages, including TREM2+ macrophages. CTL T cells reciprocally communicated with clusters of EM and EMRA CD8 T cells, underscoring their central role in plaque cell-cell communication. Notably, Cluster 5, one of these two CTL clusters, was expanded in T2D plaque samples (p=0.032) and expressed genes involved in chemotaxis, IL-2 signaling, & transcription factors (e.g., RUNX3, TBX21 ) involved in T cell activation. The equivalent of CD4 CTL phenotype was found to be expanded in T2D individuals compared to controls, & these elevated levels persisted in T2D patients following intensive lipid-lowering therapy, indicating resistance to the treatment regimen. In summary, our study emphasizes the crucial role of CD4 CTLs in the immune dynamics of atherosclerotic plaques. The observed resistance of CTLs to lipid-lowering interventions underscores the necessity for targeted therapeutic strategies to address the distinctive immune changes in T2D-associated cardiovascular diseases.