Single-cell RNA and CITE-seq analysis of human CD4+ T cells reveals age-associated upregulation of IL-32 2259951

Introduction Aging profoundly alters the human immune system, leading to increased vulnerability to infection, autoimmunity, and cardiovascular disease. Methods To define how aging reshapes CD4+ T-cell phenotypes and transcriptional programs, we performed single-cell RNA sequencing combined with CITE-seq (51 surface proteins) on peripheral blood mononuclear cells from 61 patients with angiographically confirmed presence or absence of coronary artery disease (CAD). Results We identified 139,343 high-quality single cells, including 40,821 CD4+ T cells distributed across 16 transcriptionally and phenotypically distinct clusters. The proportions of a central memory (TCM) subset and a cluster of TEMRA cells increased significantly with age, particularly in CAD patients, whereas a MMP9+ CD4+ subset declined with age. Transcriptomic analysis revealed 56 genes that were significantly upregulated with aging, many shared among clusters. Notably, IL32 was consistently increased with age, especially in individuals with low CAD burden. IL32 expression was highest in T cells and NK cells, with regulatory T cells (Tregs) showing the strongest IL32 signal among CD4+ T cells. Conclusion These results suggest that aging drives selective expansion of effector-memory and IL32-expressing subsets. Together, our study provides a single-cell framework for understanding age-associated remodeling of human CD4+ T-cell immunity in the context of atherosclerotic disease.