Researchers at Binghamton University in New York have discovered that ultraviolet radiation can weaken bonds in the stratum corneum layer of the skin, impairing the skin barrier.
Results of the study, “Ultraviolet light degrades the mechanical and structural properties of human stratum corneum,” were published online ahead of print in the Journal of the Mechanical Behavior of Biomedical Materials (Aug. 22, 2019).
Dr. Guy K. German, assistant professor of biomedical engineering, and Zachary W. Lipsky, a biomedical engineering PhD candidate at Binghamton University, aimed to uncover which kind of ultraviolet radiation is the worst for the skin and how the sun damages it.
“The cosmetics industry is a huge multibillion-dollar business, and they are all trying different things to add to their sunscreens to make them better at protecting skin,” Dr. German said in a press release. “Up until this point, however, there have been a lot of studies about skin damage, but none that properly look at how UV affects the mechanical integrity of skin.”
The Binghamton University study looked at samples of female breast skin. Researchers focused on this area since it is typically exposed only to low levels of sunlight and is subjected to various wavelengths of UV radiation. The study found no UV range is more harmful than another, but the damage scales up with the amount of UV energy that the skin absorbs.
The more significant finding was the observation that UV weakens the bonds between cells in the stratum corneum by affecting proteins in corneodesmosomes that help the cells to adhere together. That’s why sunburn leads to skin peeling.
“What we noticed when we applied more and more UV radiation is that the dispersion of these corneodesmosomes was increasing,” Lipsky said. “They are supposed to be these nice little distinct points surrounding cells, but with more irradiation, they essentially look exploded, moving away from their position. We conclude that because of the disruption of these corneodesmosomes, it damages the skin’s structural integrity.”
Lipsky and Dr. German are currently conducting further research into how UV radiation affects deeper layers of the skin.
According to Lipsky, the most significant takeaway is that skin protection is important no matter what season of the year it is.
“We’re trying to push the message to use sunscreen not just for preventing skin cancer, but also to keep the integrity of your skin so you don’t get infections or other problems,” he said. “The stratum corneum is the first barrier to the outside environment, so we need to protect it against all these different bacteria and nasty stuff that can get into our bodies.”