Abstract
Introduction:
With ageing, the skin gradually loses its youthful appearance and functions
like wound healing and scar formation. The pathophysiological theory of
Advanced Glycation End products (AGEs) has gained traction during the last
decade. This review aims to document the influence of AGEs on the mechanical
and physiologic properties of the skin, how they affect dermal wound healing
and scar formation in high-AGE populations like elderly patients and
diabetics, and potential therapeutic strategies.
Methods:
This systematic literature study involved a structured search in Pubmed and
Web of Science with qualitative analysis of 14 articles after a three-staged
selection process with the use of in- and exclusion criteria.
Results:
Overall, AGEs cause shortened, thinned, and disorganized collagen fibrils,
consequently reducing elasticity and skin/scar thickness with increased
contraction and delayed wound closure. Documented therapeutic strategies
include dietary AGE restriction, sRAGE decoy receptors, aminoguanidine,
RAGE-blocking antibodies, targeted therapy, thymosin β4, anti-oxidant agents
and gold nanoparticles, ethyl pyruvate, Gal-3 manipulation and
metformin.
Discussion:
With lack of evidence concerning scars, no definitive conclusions can yet be
made about the role of AGEs on possible appearance or function of scar
tissue. However, all results suggest that scars tend to be more rigid and
contractile with persistent redness and reduced tendency towards hypertrophy
as AGEs accumulate.
Conclusion:
Abundant evidence supports the pathologic role of AGEs in ageing and dermal
wound healing and the effectiveness of possible therapeutic agents. More
research is required to conclude its role in scar formation and scar
therapy.
Our skin is the body’s first line of defense. It is the barrier that protects us
from chemical and biological threats such as viruses, bacteria or corrosive
liquids. It is the sensor that allows us to detect physical threats like extreme
temperatures, pressure and pain. And when these preventative measures fail, the
skin has yet another property: the ability to heal.
Skin changes visibly with age, most notably with the appearance of wrinkles.
However, there is more to ageing than meets the eye; invisible alterations cause
the decline of various functions of the skin, such as wound healing and scar
formation. An array of non-conclusive research has been done in this field. One
theory that has gained traction during the last decade is the Advanced Glycation
End products (AGEs) theory. The theory states that AGEs play an important role
in skin aging, wound healing and the effectiveness of different therapeutic
options. Their presence supposedly indicates a diminished ability for wound
healing and scar formation.
AGEs are proteins to which sugar molecule is bound. The sugar molecule inhibits
the original protein from functioning properly. As skin contains many proteins
like collagen, the formation of these AGEs could be a viable explanation for the
diminished functioning with ageing. In this review, we investigated whether the
accumulation of AGEs affects wound healing and scar formation.
Normal scar formation results in a thin scar. However, it may happen that
scarring results in thick, large, painful and itchy scars. We investigated
whether people with a high AGE content in their skin, like diabetics and
elderly, have difficulties forming aesthetically pleasing scars. Secondly, we
investigated which therapies reduce the AGE content and, if so, whether these
therapies can improve wound healing and scarring. This literature study involved
research in scientific databases with qualitative analysis of 14 articles after
a three-staged selection process with the use of set criteria.
We found the different ways in which AGEs affect skin properties and wound
healing. Collagen, one of the most important proteins in the skin, is affected
by these AGEs. Once a sugar binds to it, the collagen strings becomes thinner
and shorter, and the different collagen proteins cross-link with each other in
an unstructured way. The result of these alterations is a reduced elasticity,
i.e. the skin becomes stiffer. The scar will be thinner and the time for wounds
to close is longer. We also found strategies to diminish the AGE content,
including dietary AGE restriction and Metformin, a drug used in diabetes.
We can conclude that there is proof of AGEs playing an important role in skin
ageing, wound healing and the effectiveness of different therapeutic options.
However, more research is required to conclude the exact role of AGEs in scar
formation and scar therapy.
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