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

Abstract

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.

Keywords: Immunosenescence; Inflamm-aging; Influenza; Older adults; Oleuropein; Vaccine.

Fig. 1

Example of gating strategies used for immunophenotype analysis on PBMCs collected from 20 subjects, including 9 young individuals (aged 18–35 years) and 11 older adults (aged > 60 years), before the administration of the influenza vaccine (T0) and 21–28 days post-vaccination (T1)

Fig. 2

96-well plate template showing culture conditions tested for each donor. HA = hemagglutinin protein pool of peptides; NC = negative control; NP = nucleocapsid protein pool of peptides; MP1 = matrix protein 1 pool of peptides; PC = positive control

Fig. 3

Examples of gating strategies for identifying cytokine-positive CD4 + and CD8 + T cells (TNF-α, IFN-γ, and IL-10) following in vitro stimulation. a) Positive control (Cytostim); b) Blank (Unstimulated cells); c) Peptivators (PepTivator^® Influenza A peptide pools)

Fig. 4

Description of antibody titers at different recruitment time points across age groups. Age group of young: a, anti-H1N1 Ab titer; c, anti-H3N2 Ab titer; e, anti-PhuketB Ab titer; g, anti-Bx-85cB Ab titer. Age group of older adults: b, anti-H1N1 Ab titer; d, anti-H3N2 Ab titer; f, anti-PhuketB Ab titer; h, anti-Bx-85cB Ab titer. Ab = antibody; T0 = Time zero; T1 = Time 1 (21–28 days after vaccination); T2 = Time 2 (56 days after vaccination)

Fig. 5

Comparison of H1N1 antibody titers across age groups based on different recruitment times. a, T0; b, T1; c, T2. Ab = antibody; T0 = Time zero; T1 = Time 1 (21–28 days after vaccination); T2 = Time 2 (56 days after vaccination)

Fig. 6

Comparison of the young and older adults age groups and recruitment time points (T0 and T1) within CD4 + and CD8 + T cell populations. a, CD4 + naïve; c, CD4 + TCM; e, CD4 + TEM; g, CD4 + TEMRA; b, CD8 + naïve; d, CD8 + TCM; f, CD8 + TEM; h, CD8 + TEMRA; TCM = T central memory; TEM = T effector memory; TEMRA = T effector memory cells re-expressing CD45RA; T0 = Time zero; T1 = Time 1 (21–28 days after vaccination)

Fig. 7

Description of cytokine-producing CD4 + T cell populations in the different culture conditions. Young age group: a, CD4 + TNF-α + T cells; c, CD4 + IFN-γ + T cells; e, CD4 + IL-10 + T cells. Older adults age group: b, CD4 + TNF-α + T cells; d, CD4 + IFN-γ + T cells; f, CD4 + IL-10 + T cells. PEPs = PepTivator^® Influenza A (basal stimulus); OLE = oleuropein; BIRB = BIRB 796; OLE + BIRB = combination of oleuropein + BIRB 796; PEPs + OLE/BIRB/OLE + BIRB = PepTivator^® Influenza A + oleuropein/BIRB 796/oleuropein + BIRB 796

Fig. 8

Description of cytokines producing CD8 + T cell populations in culture conditions. Young age group: a, CD8 + TNF-α + T cells; c, CD8 + IFN-γ + T cells; e, CD8 + IL-10 + T cells. Older adults age group: b, CD8 + TNF-α + T cells; d, CD8 + IFN-γ + T cells; f, CD8 + IL-10 + T cells. PEPs = PepTivator^® Influenza A; OLE = oleuropein; BIRB = BIRB 796; OLE + BIRB = combination of oleuropein + BIRB 796; PEPs + OLE/BIRB/OLE + BIRB = PepTivator^® Influenza A + oleuropein/BIRB 796/oleuropein + BIRB 796

Fig. 9

Comparison of RFU levels of ROS/RNS across different culture conditions in the two age groups. a, T0; b, T1. RFU = relative fluorescence units. PEPs = PepTivator^® Influenza A; OLE = oleuropein; BIRB = BIRB 796; OLE + BIRB = combination of oleuropein + BIRB 796; T0 = Time zero; T1 = Time 1 (21–28 days after vaccination)