CTSZ and Alzheimer disease: Our results revealed that UA enhanced the enzymatic activity of cathepsins in BJ fibroblasts and HUVEC (Figure 6B and Figure S6E), aligning with a recent study which showed that UA supplementation improved cognitive functions and olfactory ability in an Alzheimer disease (AD) mouse model by restoring lysosomal function, particularly through the activity of CTSZ (cathepsin Z) [24].