Enhancing flu vaccine responses in older adults: preliminary insights from the ISOLDA study on immunosenescence and antioxidant and anti-inflammatory approaches

Aging is frequently characterized by an inadequate primary vaccine response, likely due to immunosenescence and inflamm-aging, a low-level, chronic inflammatory state. Both aspects increase the susceptibility of older adults to viral and bacterial infections, resulting in a higher frequency and severity of infectious diseases. In this preliminary study, a cohort of 52 individuals was recruited and divided into two groups: young (age range 21-35) and older adults (> 60 years old). Peripheral blood mononuclear cells (PBMCs) were collected before (time 0, T0) and after (time 1, T1) the immunization with a tetravalent influenza vaccine. Then, T cell immunophenotyping analysis was conducted to investigate how aging and influenza vaccination influence T cell responses. Additionally, the anti-inflammatory and antioxidant effects of oleuropein (OLE), a secoiridoid extracted from extra virgin olive oil, alone or in combination with BIRB 796, a potent inhibitor of p38 MAPK, were explored to enhancing the impact of influenza virus on T cell activation, aiming to identify potential alternatives or complementary strategies to improve traditional flu-vaccine formulations. Statistically significant observations were noted for a decrement in CD8 + T naïve and an increase of effector memory between the young and older adults after flu-vaccination. Moreover, preliminary findings indicate anti-inflammatory and antioxidant properties of OLE and BIRB 796 on T cell responses, particularly regarding Reactive Oxygen Species/Reactive Nitrogen Species modulation, with a trend toward the decrease of pro-inflammatory cytokines (i.e., Interferon-γ (INF-γ), Tumor Necrosis Factor-α (TNF-α)), αalthough without statistical significance.