Photoaging (Extrinsic Aging, solar elastosis)


Skin Aging can be Understood by considering two concepts

Cumulative acute stress through chronic mechanisms: three stages:

  • -degeneration of macromolecules
  • -Altered cell function
  • -Modified Structure and function of organs



Mitochondrial DNA mutation: increased oxidative stress generation:

  • -characterized by 4977 base pairs (double-stranded)
  • -deletion mutations cause premature ageing (Trifunovicz, Nature 2004: progeria in mice, Kujoth, Science)



Concerning humans, our understanding of mt mitochondrial mutation is circumstancial:

  • -photoaged skin is characterized by increased mitochondrial DNA mutations
  • -irradition in vitro and in in Vivo of fibroblasts with UV exposure



How does Reactive oxidative stress lead to skin ageing ?

The team of the presenter used human unirradiated fibroblasts with mtDNA deletion mutation:

  • -these can be extracted from patients with Kearns-Sayre Syndrome: all the cells carry the deletion (ptosis is a symptom and the patients die before reaching  the age of 10)
  • -increases ROS (Reactive Oxgen Species or Free Radicals) and lysyl oxidase enzyme levels initially



Levels at which the changes occur:

  • -dermis: after 1-6 weeks: overexpression of MMP 1 and 2 and VEGF, decrease of TIMP-1: all of this increases collagen breakdown which correlates with wrinkles (destruction of picrosirius expression)
  • -also epidermal atrophy: (immunohistochemical staining of KSS shows after 2 weeks that epidermis is thinner and stratified than normal counterparts): increase of filaggrin, increase in lipid enzymes (glkccer) and decrease of hbd-2 (antimicrobial peptase)



How to prevent and cure photoaging ?

Improvement of mitochondrial function and integrity-novel ingredients, revert symptoms of skin aging

Concretely, Environmental factors play a role:

  • -Ultraviolet radiation by the sun
  • -Pollution: Ambient Particulate Matter (PM): air pollution=incomplete exhast fumes. Diesel engines (diesel) (Soot): increased risks of pigment spots=Epidemiological observation (Polyhydrocarbon particles attach to AhR which increases MMP-1 and melanin synthesis)



Krutmann J, Aging and Photoaging – 22nd World Congress of Dermatology (WCD) – Seoul, South Korea