Excessive apoptosis of naïve T cells resulting hyperactivation as a cause of mammalian aging

Abstract

In mammals, the most remarkable T cell variations with aging are the shrinking of naive T cell pool and enlargement of memory T cell pool, which are partially caused by thymic involution. However, it remains an enigma whether these T-cell-related changes are consequences or causes of mammalian aging. In this study, we find that the T-cell specific Rip1 KO mice present similar age-related T cell changes and exhibit signs of accelerated aging, including inflammation, multiple age-related diseases and a shorter lifespan. Mechanistically, T cells lacking RIP1 displayed excessive apoptosis, leading to T cell compensatory proliferation, hyperactivation, increased inflammation, and ultimately premature death. Consistent with this, blocking apoptosis by co-deletion of Fadd in Rip1 deficient T cells significantly recovered the lymphopenia and imbalance between naive and memory T cell, substantially restored ageing-related phenotypes, and prolonged life span in T-cell specific Rip1 KO mice. These results suggest that changes in T cells play a causal role in mammalian aging. Therefore, replenishing or blocking apoptosis of naive T cells could offer new therapeutic approaches for aging and age-related diseases.