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Key Points
- Use of topical products that contain DNA repair enzymes may be beneficial in shielding the skin from harmful effects of UV radiation, according to one study.
If course, chronic overexposure to ultraviolet (UV) light is one of the major causes of older-looking skin and, as a result, many skin rejuvenation procedures focus on correcting photo-aging effects. But according to one expert, future skin rejuvenation modalities may also include efforts to repair the DNA damage induced by UV rays — and here immunomodulation is key.
"It has become common knowledge that sun exposure causes direct damage to the DNA in our skin cells," says Elma Baron, M.D., assistant professor and director of the Skin Study Center, Department of Dermatology, Case Western Reserve University, Cleveland, Ohio. "Aside from the direct cancerous effects of unrepaired DNA damage, DNA damage also plays a major role in UV-induced immunosuppression. It is this DNA damage and the inadequate repair of this damage that lead to a suppression of the skin's immune system, which opens up Pandora's box in terms of the development of cutaneous carcinomas, as well as the photo-aging effects of the skin," Dr. Baron tells
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SUNSCREEN SUPPLEMENTS Although many skin care products are available to help rejuvenate the skin with pro-active enzymes, antioxidants and other "fountain of youth-like" ingredients, novel over-the-counter cosmeceuticals are also being developed that contain DNA repair enzymes to prevent UV suppression. These enzymes may also reverse the detrimental skin effects of overexposure to UV rays. But just how efficacious are such topicals?
Dr. Baron recently conducted a small study with Advanced Night Repair Concentrate (Estée Lauder Companies), a topical moisturizer containing DNA repair ingredients, in order to determine whether the DNA repair concentrate can prevent UV-induced suppression of contact hypersensitivity responses in vivo. The randomized, placebo-controlled study included a total of 20 healthy volunteers with a mean age of 29 years who received solar-simulated radiation on the targeted skin with and without treatment. Participants were then sensitized to a known topical allergen dinitrochlorobenzene (DNCB), and the level of the resulting contact hypersensitivity response was assessed two weeks later. "We found that with the use of this product that contains DNA repair ingredients, the participants were significantly less prone to the suppressive effects of UV light, compared to the study group who underwent the UV exposure without prior use of the product," Dr. Baron relates. "Essentially, those who received an application of the moisturizer containing DNA repair ingredients were able to recognize the allergen better than the control group."
According to Dr. Baron, the use of topical products that contain DNA repair enzymes such as that used in this study appears to be beneficial in shielding the skin from the harmful effects of UV radiation and is able to prevent the suppression of the skin's immune system. This important finding is particularly useful in those individuals who expose themselves to harmful UV radiation, as the application of such a moisturizer offers an added protection of the skin in addition to commonly used sunscreens.
A DELICATE BALANCE The main purpose of the skin's immune system is to provide immuno-surveillance, which increases the skin's resistance to the development of skin cancer, not necessarily to prevent photoaging. This is perhaps best illustrated in transplant patients who receive iatrogenic immunosuppression and who are much more susceptible to the development of cutaneous cancers than normal populations.
However, some of the mechanisms of UV-induced photoaging overlap with the development of skin cancer because as we age and receive more photo-damage, we also develop more skin cancers. In the process of mounting an adequate immune response to the harmful UV radiation, though, the skin defense systems begin to recruit and muster inflammatory cells such as macrophages, neutrophils and other cellular immune components that release enzymes that also have the potential to cause the degradation of various skin components such as collagen.
"There is a very delicate balance as to whether we want more of an immune response or less of an immune response to take place and keeping this fine balance is key in cutaneous homeostasis," Dr. Baron says. "Just where this fine line lies and how much of an immune response is good to hold that fine balance is currently still unknown. In terms of UV-induced aging, whether a decreased immune response is more beneficial or, contrarily, having a very avid immune response where inflammatory cells release hydrogen peroxide and other enzymes that can eventually degrade the skin's matrix (causing wrinkling and other signs of skin aging) is still a gray area."
