Defective T Memory Cell Differentiation after Varicella Zoster Vaccination in Older Individuals

Area of Science:

• Immunology
• Vaccinology
• Gerontology

Background:

• Live attenuated varicella zoster virus (VZV) vaccination offers protection against zoster reactivation but exhibits incomplete efficacy, particularly in elderly populations.
• Understanding the molecular basis of variable vaccine responses is crucial for improving vaccine strategies, especially for aging individuals.
• T- and B-cell dynamics following VZV vaccination are key indicators of adaptive immunity and vaccine effectiveness.

Purpose of the Study:

• To investigate the molecular mechanisms governing differential T- and B-cell responses to VZV vaccination across various age groups.
• To identify age-related factors influencing the generation and maintenance of long-lived antigen-specific T cell memory.
• To explore potential therapeutic targets for enhancing vaccine-induced T cell memory in older adults.

Main Methods:

• Analysis of T- and B-cell responses, including VZV-specific antibodies and antigen-specific T cells, in individuals of different ages and identical twin pairs.
• Assessment of T cell loss and expansion dynamics following VZV vaccination.
• Gene expression profiling of activated CD4 T cells during the peak response phase to identify molecular correlates of T cell memory generation.

Main Results:

• Antigen-specific T cell responses to VZV vaccination were significantly influenced by genetic factors, unlike antibody induction.
• Older individuals exhibited diminished generation of long-lived memory T cells, primarily due to increased T cell attrition post-peak response, not impaired expansion.
• Gene expression analysis revealed cell cycle regulation and DNA repair pathways correlated with T cell contraction and subsequent memory formation.

Conclusions:

• Inherited factors play a significant role in shaping VZV-specific T cell memory responses.
• Age-related T cell loss, rather than reduced expansion, underlies the impaired generation of long-lived memory T cells in older vaccine recipients.
• Modulating cell cycle regulatory mechanisms presents a potential strategy to mitigate T cell attrition and enhance antigen-specific T cell memory, particularly in the elderly.