Single-Cell Analyses Identify Dysfunctional CD16+ CD8 T Cells in Smokers

Abstract

Tobacco smoke exposure impacts immune response, leukocyte subtypes, DNA methylation, and gene expression. We performed single-cell RNA sequencing (scRNAseq) on >45,000 human peripheral blood immune cells from smokers and nonsmokers. Transcriptomes revealed a subpopulation of FCGR3A (CD16)-expressing Natural Killer (NK)-like T lymphocytes that increased in smokers. Mass cytometry confirmed an increase in the frequency of CD16+ CD8 T cells in smokers. The majority of CD16+ CD8 T cells were CD45RA positive, indicating an effector memory re-expressing CD45RA T cell (T_EMRA) phenotype. Smokers’ CD8 T cells were biased toward differentiated cells and had a lower frequency of naïve cells, an indication of immune aging. FCGR3A-expressing CD8 T cells were inferred as the most differentiated cluster and expressed senescence markers. Smokers expressed senescence-linked genes in other immune populations and had elevated Tregs, which induce senescence. Our results suggest that smoking-induced, senescence-associated immune cell dysregulation contributes to smoking-mediated pathologies.

Keywords: single-cell, Mass Cytometry, Tobacco Smoke, Immune Aging, CD8 T cells, senescence, Cytolytic Potential, Dysfunctional T Cells, atherosclerosis