Here’s something to think about the next time you’re soaking up some rays at the beach or pool: Scientists have determined the biological mechanism of sunburn is actually a consequence of RNA damage to skin cells and a visible sign of the body’s protective immune response to ultraviolet radiation.
The findings, reported by researchers at the University of California-San Diego School of Medicine in the journal Nature Medicine, may point the way to eventually blocking that inflammatory process – an advance that could have significant implications for a range of medical conditions and treatments.
"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," said lead researcher Dr. Richard L. Gallo. "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."
For the study, Gallo and colleagues studied human skin cells and mice for clues to UV’s impacts. They found UVB radiation fractures and tangles a type of RNA inside cells, which provokes an inflammatory response from healthy neighboring skin cells designed to remove sun-damaged cells.
We see and feel that process as sunburn, Gallo said.
"The inflammatory response is important to start the process of healing after cell death," said Gallo. "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."
Gallo said it's still not known how gender, skin pigmentation and individual genetics effect sunburn and the body’s immune response.
"Genetics is closely linked to the ability to defend against UV damage and develop skin cancers," he said.
The study was funded, in part, by the National Institutes of Health.