γδ T Cells Target and Ablate Senescent Cells in Aging and Alleviate Pulmonary Fibrosis

A variety of physiological and pathological stimuli elicit the cellular senescence response. Immune cells are known to execute surveillance of infected, cancerous, and senescent cells, and yet senescent cells accumulate with age and drive inflammation and age-related disease. Understanding the roles of different immune cells in senescent cell surveillance could enable the development of immunotherapies against biological aging and age-related disease. Here, we report the role of human gamma delta (γδ) T cells in eliminating senescent cells. Human donor Vγ9vδ2 T cells selectively remove senescent cells of different cell types and modes of induction while sparing healthy cells, with parallel findings in mouse cells. We find that senescent cells express high levels of multiple γδ T cell ligands, including cell-surface BTN3A1. Individually blocking NKG2D or γδ TCR of γδ T cells only partially reduces Vγ9vδ2 T cell cytotoxicity, evidencing their versatility in senescence removal. γδ T cells expand in response to the induction of a mouse model of idiopathic pulmonary fibrosis (IPF), accompanied by the emergence of senescent cells, and colocalize with senescent cells in lung tissue from patients with IPF. Finally, we show that adoptive cell transfer of γδ T cells into an IPF mouse model reduces the number of p21-expressing senescent cells in affected lung tissue and improves outcomes. γδ T cells or modalities that activate their surveillance activity present a potent approach for removing senescent cells and their attendant contribution to aging and disease.