T cell senescence

T cell senescence is a cellular state characterized by permanent cell cycle arrest and functional decline in T lymphocytes, typically triggered by telomere shortening (replicative senescence) or extrinsic stressors such as chronic antigen exposure, oxidative stress, and DNA damage (Lowe et al., 2020). Unlike exhausted T cells, which are often reversible, senescent T cells are resistant to apoptosis and remain metabolically active, frequently adopting a Senescence-Associated Secretory Phenotype (SASP) that releases pro-inflammatory cytokines, proteases, and growth factors (Larbi et al., 2017). This state is molecularly governed by the activation of the p53/p21Cip1 and p16INK4a/Rb pathways and is marked by the loss of costimulatory receptors like CD27 and CD28 and the gain of markers such as CD57 and KLRG1 (Xu et al., 2021). \n\nIn clinical pathology, the accumulation of senescent T cells contributes to 'inflammaging,' reduced vaccine efficacy, and the progression of chronic infections and cancers, where they help establish an immunosuppressive tumor microenvironment (Zou et al., 2021). Therapeutic interventions currently under development include senolytic drugs (e.g., Navitoclax) to selectively clear these cells, senomorphic agents (e.g., Metformin) to blunt their inflammatory output, and specialized CAR-T cells designed to target the surface marker uPAR to rejuvenate the immune landscape by eliminating the senescent population (Amor et al., 2020).

Other names

T-lymphocyte senescenceImmunosenescence (T-cell specific)T-cell agingReplicative senescence of T cellsTerminal differentiation of T cells

Therapeutic strategies targeting T cell senescence involve 'senolysis' (selective induction of apoptosis in senescent cells by inhibiting anti-apoptotic pathways like BCL-2/BCL-XL), 'senomorphism' (suppression of the pro-inflammatory Senescence-Associated Secretory Phenotype (SASP) via mTOR or JAK/STAT inhibition), or rejuvenation (inhibiting p38 MAPK or ATM signaling to restore proliferative capacity). Additionally, engineered CAR-T cells can be used to physically eliminate senescent cells by targeting upregulated surface markers such as uPAR (Amor et al., 2020; Kirkland & Tchkonia, 2020).