Alon Monsonego

Aging is characterized by the progressive deterioration of tissue structure and function, leading to increased vulnerability to diseases. Senescent cells (SCs) accumulate with age, but how the immune system regulates their burden is unclear. Here we show that CD4 T cells differentiate into Eomesodermin (Eomes)⁺CCL5⁺ T lymphocytes (CD4-Eomes) in a SC-rich environment and that a reduction in the SC load, achieved using senolytic drugs, was sufficient to halt this differentiation. We further demonstrate that eliminating CD4-Eomes cells at advanced age by selectively deleting the Eomes transcription factor in CD4 T cells results in increased accumulation of SCs, profound physical deterioration and a decreased lifespan. In liver cirrhosis, a model of localized chronic inflammation, CD4-Eomes cell elimination increased fibrosis, SC load and worsened the disease. Collectively, our findings demonstrate the fundamental role of CD4-Eomes cells in modulating tissue senescence, with implications for age-related diseases and longevity.