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Extrinsic Ageing – The role of the sun.

May 28, 2012

Our obsession with holding back the ravages of time has lead to us spending billions of dollars on anti-ageing products.  As you can’t change your genes, most of the efficacy in anti-ageing comes from protecting the skin against the ravages of the environmental excess.

Intrinsic ageing = blame your mother (it’s nothing personal, it’s in the genes).  Extrinsic ageing = sun + pollution + lifestyle choices. 

Collagen and Elastin are the skins scaffolding, a collapse or weakening of this leads to dermal atrophy or wrinkles.  Excessive sun exposure over and above the level that the skin can comfortably tolerate (at or below the MED) we start to see changes in the skin metabolism.

The suns role in extrinsic ageing

There is an increased in MMP activity.  MMP or Matrix Metalloproteinase is an enzyme that works to break down the structural proteins in the skin.  In non sun-exposed skin it is present in low levels where it works to destroy tissues that are mal-functioning or no longer required. In sun damaged skin it becomes over active and destroys otherwise good tissue.

GAGs and Hyaluronic acid – essential components of the extracellular matrix, which fill the gaps between the structural proteins in the skin, function to keep it hydrated and ordered.  The activity of these two chemicals has been found to be greatly reduced and disordered when exposed to excessive UV radiation.  The implications of this are that the skin, our largest organ comprised of 70% water is left dry and exposed which in turn leaves us susceptible to microbial and environmental attack.

AP-1 or (activator protein 1) and TGF (transforming growth factor beta) are transcription factors that regulates gene expression including cytokines and growth factors.  Importantly in the skin it controls apoptosis or cell death, which is of vital importance for the general health and wellbeing of the skin.  An out-of-balance AP-1 or TGF factor could lead to damaged cells living on and replicating while healthy cells are attacked and destroyed. Either way the result will be prematurely aged skin.

While the scientist in the laboratory may be able to identify, measure and categorize photo biological effects, it is only when the knowledge is applied and observed in-vivo (on real skin rather than in a test tube)  that we gain meaning and perspective.  That is one reason why in focusing on ‘fixing’ an individual pathways the cosmetic chemist may fail to achieve the desired result.

When it comes to truth, the eyes have it 🙂

Enjoy your sun safely and beautifully.



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