FIGURE 2.

Age‐related thymic involution mechanisms. Both positive and negative regulators of thymic involution have been identified. Positive regulators include Foxn1, E2F3, myc, Wnt4, FGF21, KGF, IL‐7, IL‐22, miR‐181a‐5p, Lamin‐B1, Leptin, GH, IGF‐1, Ghrelin, and GHSR, which exhibit reduced activity with age. Negative regulators include Axin, LIF, OSM, IL‐6, SCF, IL‐1β, miR‐125a‐5p, miR‐205‐5p, and follistatin, which exhibit increased activity with age. In addition, CR can attenuate age‐related thymic involution, while obesity and sex hormones exacerbate age‐related thymic involution