Low intensity vibration as a novel strategy to normalize age-related deficits in T cell proliferation, activation, and function.

Age related decline in number, activation, and function of T lymphocytes are hallmarks of immune dysfunction. Exercise is often described as the single best intervention to protect and promote robust immune function during aging. While these benefits are often presumed to be an indirect byproduct of increased metabolism, exercise may also deliver a direct benefit to the immune cell through its innate sensitivity to mechanical signals. We tested the hypothesis that mechanical stimulation, delivered non-invasively using low intensity vibration (LIV, at: 2 h of 30 Hz, 0.7 g) could augment T cell expansion without disrupting their phenotype, as well as improve the status of aged, dysfunctional, T cells. As compared to sham-handled controls, LIV increased proliferation 59% in T cells isolated from elderly patients (69.3y ± 2.6) while increasing expansion by only 13% in T cells harvested from young subjects (22.7y ± 3.8). T cell activation and production of pro-inflammatory cytokines (e.g., IL-2 by + 25%; p < 0.05) were also increased by LIV. Exploring whether this in vitro influence could translate to an in vivo model of aging, 4w of 30 min/d of LIV applied to 18-month-old mice resulted in significant increases in T cell activation as compared to sham-handled controls (102% increase in CD25 & 44.2% increase in CD69; p < 0.05). LIV also improved T cell anti-viral functionality, as 18-month-old mice pre-treated with 4w of LIV prior to infection with an Influenza A virus exhibited 18% less weight loss at 12d compared to sham-handled controls, a critical indication of a more robust immune system. These data suggest that extremely low magnitude mechanical signals, introduced non-invasively using LIV, represent a novel, non-drug therapeutic strategy for ameliorating age-related declines in immune function.