Study reveals secret behind sunburn

Soaking up sun has always entailed an ironic amalgamation of fire and water. How fitting then, that more dichotomy has been found to carry over into the most likely result of unprotected sunbathing — sunburn.

According to a study published July 8 in Nature Medicine, sunburn is the immune system’s response to RNA damage. When skin assumes that familiar red hue, it’s a sign that the body has begun orchestrating the process to shed sun-damaged skin, a schema that has the potential to be surprisingly advantageous. Understanding these red flags could mean the discovery of a method by which doctors and medical professionals can deter inflammation and therein halt a number of medical conditions, such as psoriasis, according to the research.

But whereas one ailment could meet its demise, another malady stands to ascend by way of the same beam.

“Diseases like psoriasis are treated by UV [ultraviolet] light, but a big side effect is that this treatment increases the risk of skin cancer," lead investigator Dr. Richard Gallo, a professor of medicine at UCSD and Veterans Affairs San Diego Healthcare System, said in news release.

"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," he continued.

Gallo and his colleagues performed experiments on human skin cells and mice subjects, finding that ultraviolet B radiation fractures elements of non-coding micro-RNA. Thus, when these harrier versions of RNA meet the salacious sun, the match is far from celestial, with surrounding healthy cells opting for an inflammatory response to be rid of their impaired counterparts. It is this portion of the procedure that makes sunburns such pains.

"The inflammatory response is important to start the process of healing after cell death," explained 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."

Further study should be conducted on how sunburn as a healing process could relate to different physical and social variables like gender, skin pigmentation and individual genetics; Gallo and his comrades were unable to distinguish any sort of correlation between the benefits of sunburn and the above factors. Nevertheless, Gallo hypothesized that some unexplored elements could play more pivotal roles than others:

"Genetics is closely linked to the ability to defend against UV damage and develop skin cancers," he said. "We know in our mouse genetic models that specific genes will change how the mice get sunburn. Humans have similar genes, but it is not known if people have mutations in these genes that affect their sun response."

Other contributors to the study include first author Jamie J. Bernard, a post-doctoral researcher, as well as co-authors Christopher Cowing-Zitron, Teruakai Nakatsuji, Beda Muehleisen, Jun Muto, Andrew W. Borkowski and Benjamin D. Yu, Division of Dermatology, UC San Diego; Laisel Martinez, Miami Veterans Affairs Medical Center; and Eric L. Greidinger, Miami Veterans Affairs Medical Center and Division of Rheumatology, University of Miami Miller School of Medicine.

Funding for the research was provided in part by the National Institutes of Health, a Veteran Affairs Merit Award, the National Institute of Environmental Health Sciences Training Grant, the Department of Veteran Affairs, and the Lupus Research Institute. 

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