Typically, Klotho content decreases during aging, and reduced Klotho expression has been consistently noted in various pathological conditions, including Alzheimer’s disease, chronic obstructive pulmonary disease (COPD), chronic renal disease (CKD), cardio-cerebrovascular disease and diabetes, which are all highly related to aging (6, 7). This evidence concerns the gene KL and chronic obstructive pulmonary disease.