Replicative senescence of CD8 T cells: effect on human ageing

Area of Science:

• Immunology
• Gerontology
• Cellular Biology

Background:

• Lifelong pathogen exposure shapes T cell populations in the elderly.
• Replicative senescence leads to CD8 T cell dysfunction, characterized by cell cycle arrest and loss of CD28 expression.

Purpose of the Study:

• To investigate the characteristics and health implications of senescent CD8 T cells in aging.
• To explore the association between senescent CD8 T cells and immune function, mortality risk, and bone homeostasis.

Main Methods:

• Analysis of CD8 T cell populations in elderly individuals.
• In vitro studies on CD8 T cell proliferation and senescence markers.
• Correlation studies linking senescent T cells to clinical outcomes like vaccination response, mortality, and fractures.

Main Results:

• Senescent CD8 T cells exhibit irreversible cell cycle arrest, loss of CD28, and altered stress responses.
• High proportions of CD28-negative CD8 T cells correlate with poor influenza vaccine response and increased mortality risk in the elderly.
• Senescent CD8 T cells are associated with increased osteoporotic fractures and may negatively impact bone homeostasis.

Conclusions:

• Senescent CD8 T cells contribute to immune dysfunction and are linked to adverse health outcomes in aging.
• These aged T cells may exert pleiotropic negative effects on both immune and non-immune systems, including bone health.