As skin ages, hyaluronic acid (HA), the skin component responsible for serving as a natural moisturizing factor, decreases with age. Past studies show that a small amount of skin HA is correlated with the skin sagging index and wrinkle depth, as dermal HA helps skin maintain the extracellular matrix structure effectively. HA loss is caused by hyaluronidase HYAL1/2.    Recent studies revealed that in the dermis, HA is mainly degraded by HYBID, the novel HA cleavage enzyme. The expression ...