The Immune-Autonomic Interface in Aging: Baseline Immune Profile Shapes Cardiac Autonomic Response to Exercise

Area of Science:

• Gerontology
• Immunology
• Cardiovascular Physiology

Background:

• Aging is associated with decreased physiological resilience, marked by declines in cardiac autonomic control (Heart Rate Variability, HRV) and immune function (immunosenescence, inflammaging).
• Existing research highlights static links between immune and autonomic systems, but the dynamic influence of baseline immune status on autonomic responses to acute stress in aging is not well understood.

Purpose of the Study:

• To investigate the association between baseline immune cell profiles and dynamic HRV changes in older adults during rest, acute exercise, and recovery.
• To determine how pre-existing immune status modulates the cardiac autonomic response to physiological stress.

Main Methods:

• Quantification of baseline lymphocyte subsets (B-cells, T-cells, CD4+/CD8+ ratio, NK cells).
• Assessment of Heart Rate Variability (HRV) during a graded exercise test including rest, exercise, and recovery phases.
• Analysis using Bayesian mixed-effects models to link immune profiles with HRV dynamics.

Main Results:

• Acute exercise significantly altered HRV, as expected.
• Baseline levels of specific immune cell subsets (B-cells, T-cells, CD4+/CD8+ ratio, NK cells) were significantly associated with the pattern and magnitude of exercise-induced HRV changes.
• These findings indicate that the pre-existing immune state dynamically modulates the cardiac autonomic response to acute stress.

Conclusions:

• The pre-existing immune cell profile significantly modulates dynamic cardiac autonomic responses to acute exercise in older adults.
• Immune-autonomic crosstalk plays a critical role in physiological resilience during aging.
• Understanding these interactions offers insights into individual differences in exercise responses and potential personalized health strategies.