Are skin senescence and immunosenescence linked within individuals?

With advancing age, many organs exhibit functional deterioration. The age-associated accumulation of senescent cells is believed to represent one factor contributing to this phenomenon. While senescent cells are found in several different organ systems, it is not known whether they arise independently in each organ system or whether their prevalence within an individual reflects that individual's intrinsic aging process. To address this question, we studied senescence in two different organ systems in humans, namely skin and T cells in 80 middle-aged and older individuals from the Leiden Longevity Study. Epidermal p16INK4a positivity was associated with neither CD4⁺ nor CD8⁺ T-cell immunosenescence phenotype composites (i.e., end-stage differentiated/senescent T cells, including CD45RA⁺ CCR7^- CD28^- CD27^- CD57⁺ KLRG1⁺ T cells). Dermal p16INK4a positivity was significantly associated with the CD4⁺ , but not with the CD8⁺ immunosenescence composite. We therefore conclude that there is limited evidence for a link between skin senescence and immunosenescence within individuals.