CD4 T cell therapy counteracts inflammaging and senescence by preserving gut barrier integrity

Healthy aging relies on a symbiotic host–microbiota relationship. The age-associated decline of the immune system can pose a threat in this delicate equilibrium. In this work, we investigated how the functional deterioration of T cells can impact host–microbiota symbiosis and gut barrier integrity and the implications of this deterioration for inflammaging, senescence, and health decline. Using the Tfamfl/flCd4Cre mouse model, we found that T cell failure compromised gut immunity leading to a decrease in T follicular and regulatory T (Treg) cells and an accumulation of highly proinflammatory and cytotoxic T cells. These alterations were associated with intestinal barrier disruption and gut dysbiosis. Microbiota depletion or adoptive transfer of total CD4 T cells or a Treg cell–enriched pool prevented gut barrier dysfunction and mitigated premature inflammaging and senescence, ultimately enhancing healthspan in this mouse model. Thus, a competent CD4 T cell compartment is critical to ensure healthier aging by promoting host–microbiota mutualism and gut barrier integrity.