Figure 1.

During lifetime, skin is exposed to numerous environmental stressors such as UVA and UVB, ionizing radiation and air pollutants, as well as to stressors that may originate from diet (e.g., high fat diets), internal sources (e.g., metabolism or tissue inflammation) and/or lifestyle (e.g., smoking). While young, these stressors are effectively neutralized by cell protective mechanisms (e.g., the antioxidant transcription factor Nrf2). During aging, defenses are compromised, resulting in accumulating ROS, genome and proteome damage; damage of biomolecules then disrupts normal cell signaling and homeodynamics, resulting in (among others) coarse wrinkles, hyperpigmentation and skin shallowness.