Sunburn Is Consequence Of RNA Damage To Skin Cells

Date: Jul-09-2012Our skin goes red and hurts when we sunburn as a result of RNA damage to skin cells, scientists from the University of California, San Diego School of Medicine, reported in Nature Medicine. In the report the scientists explained the biological mechanism of sunburn, when our skin goes red and hurts, and why there is an inflammatory response. They added that their research may help find a way of eventually stopping the inflammatory response from occurring.

Richard L. Gallo, MD, PhD, principal investigator, added that their findings may be useful in research for other medical conditions and treatments.

The authors explained as background information that UVB radiation from the sun can cause sunburn, carcinogenesis and premature aging. Scientists have not understood which mechanisms are responsible for acute skin inflammation - so, they set out to find out.

Dr. Gallo said:

"For example, diseases like psoriasis are treated by UV light, but a big side effect is that this treatment increases the risk of skin cancer.

Our discovery suggests a way to get the beneficial effects of UV therapy without actually exposing our patients to the harmful UV light. Also, some people have excess sensitivity to UV light, patients with lupus, for example. We are exploring if we can help them by blocking the pathway we discovered."
Elements of non-coding micro-RNA tangled and fractured by UVB radiation
Dr. Gallo, first author Jamie J. Bernard, and team discovered that UVB radiation "fractures and tangles elements of non-coding micro-RNA (special type of RNA) inside the cell that does not directly make proteins."

Cells which are irradiated release this mutated RNA, making neighboring, healthy cells trigger a process which leads to an inflammatory response. The inflammatory response occurs as an attempt to rid the skin of sun-damaged cells.
What is UV radiation?
UV radiation, known as ultraviolet radiation, consists of invisible rays that form part of the energy that comes from the sun - they cause sunburn, and can raise the risk of skin cancer. UV radiation is made up of three kinds of rays:
UVA - ultraviolet A
UVB - ultraviolet B
UVC - ultraviolet C

UVC, the most dangerous kind of ultraviolet light is no threat to humans because it cannot protect our planet's protective ozone layer. UVA and AVB do penetrate. UVB is stronger than UVA, but UVA can penetrate further into the skin.

Humans and many animals see and feel the whole process as sunburn.
The inflammatory response starts the healing process after cell death
Gallo said:

"The inflammatory response is important to start the process of healing after cell death. We also believe the inflammatory process may clean up cells with genetic damage before they can become cancer. Of course, this process is imperfect and with more UV exposure, there is more chance of cells becoming cancerous."

Sunburn is part of an inflammatory response, which is important to start the process of healing after cell death

The authors added that they are still not sure how skin pigmentation, people's individual genetic makeup, and gender impact on the mechanism of sunburn.

Our genetic makeup is closely associated with how we defend ourselves from UV damage; it also impacts on our chances of developing skin cancer, the authors explained. In their mice genetic models, they found that certain genes change the way mice get sunburn.

Gallo said:

"Humans have similar genes, but it is not known if people have mutations in these genes that affect their sun response."

Written by Christian Nordqvist

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