Anti-Inflammatory Klotho Protein Serum Concentration Correlates with Interferon Gamma Expression Related to the Cellular Activity of Both NKT-like and T Cells in the Process of Human Aging

Klotho is a beta-glucuronidase that reveals both anti-inflammatory and anti-oxidative properties that have been associated with mechanisms of aging. The study aimed to analyze the relationships between the serum concentration of soluble a-Klotho and cellular activity of two populations of lymphocytes; T and NKT-like cells corresponding to the level of cytokine secretion; i.e., IFN-?, TNF-a, and IL-6. The studied population comprised three age groups: young individuals ('young'), seniors aged under 85 ('old'), and seniors aged over 85 ('oldest'). Both NKT-like and T cells were either non-cultured or cultured for 48 h and stimulated appropriately with IL-2, LPS or PMA with ionomycin to compare with unstimulated control cells. In all studied age groups non-cultured or cultured NKT-like cells revealed higher expressions of TNF-a, IL-6, and IFN-? than T cells. a-Klotho concentration in serum decreased significantly in the process of aging. Intriguingly, only IFN-? expression revealed a positive correlation with a-Klotho protein serum concentration in both non-cultured and cultured T and NKT-like cells. Since IFN-? is engaged in the maintenance of immune homeostasis, the observed relationships may indicate the involvement of a-Klotho and cellular IFN-? expression in the network of adaptive mechanisms developed during the process of human aging.