Infrared radiation-induced matrix metalloproteinase in human skin: implications for protection.
Schroeder P, Lademann J, Darvin ME et al.
J Invest Dermatol, 2008, 128, 2491-2497
Photodamage is one of the leading contributors to skin ageing and the formation of fine lines and wrinkles, and the mechanism by which this occurs is under intense investigation. Infrared radiation (760-1440nm) is a major component of sunlight, with approximately 30% of total solar energy reaching the earth's surface within the IR range . In addition, human skin may be exposed to infrared radiation from UV or IR irradiation devices, which are increasingly being used for medical purposes and tanning. A careful study of the clinical relevance of infrared irradiation of human skin is lacking. Although recently published data indicate that infrared radiation triggers a different group of pathways compared to UVB in skin, in fact infrared radiation causes the formation of reactive oxygen species (ROS) within the mitochondria since it can be inhibited by the antioxidant MitoQ , with a concomitant increase in the expression of matrix metalloproteinase 1 (MMP-1). As there is no associated increase in the tissue-specific inhibitor of MMP-1 (TIMP), the imbalance results in destruction of types I and III collagen, as well as of elastin, which is known to contribute to the signs of photoageing. To date, this has been demonstrated in vitro and this study is the first to investigate these pathways in vivo, and with the use of Raman spectroscopic measurement of the cutaneous concentration of carotenoid antioxidants in skin, provides evidence that the effect of infrared radiation in vivo may be mediated by an oxidative stress response.
In this work, buttock skin was exposed to a single dose of infrared radiation at 360-720 J/[cm.sup.2] emitting light between 760 and 1440nm. This was compared to untreated skin. There was an infrared radiation-induced increase in dermal MMP-1, measured by three different assays: an increase in MMP mRNA by real-time PCR, an increase in protein expression using immunofluorescence microscopy, and western blot analysis. There was no obvious correlation between skin type of the donor and infrared radiation response, however, there was interindividual variation in response to infrared radiation with 20% of individuals not showing any response. The infrared radiation produced a significant decline in antioxidant content of skin measured by Raman spectroscopy within 5 minutes of treatment. At later time points (e.g. 24-h post irradiation) skin antioxidant capacity had fully recovered. Several antioxidants were tested for their ability to mitigate the infrared radiation-induced response; and those found to provide a benefit included vitamin C, epicatechin and epigallocatechin gallate, while vitamin E did not. A mixture of antioxidants (made from grape seed extract, ubiquinone, vitamin C, vitamin E) was also tested. This mixture diminished infrared radiation-induced MMP-1 mRNA expression in a highly reproducible dose-dependent manner. However, when applied in vivo prior to infrared radiation, the response was reduced by 25-100%.
Based on the data presented, the authors recommend that the use of artificial infrared radiation devices such as those used in this study is unethical and should be legally restricted. The authors comment that similar devices are promoted and sold for fat reduction and skin rejuvenation techniques.
[1.] Kochevar IE, Taylor CR, Krutmann J. Fundamentals of cutaneous photobiology and photoimmunology. In Fitzpatrick's Dermatology in General Medicine (Wolff K, Goldsmith LA, Katz SI et al., eds). 7th edn. McGraw-HIll, New York, 2007.
[2.] Schroeder P, Pohl C, Calles et al. Cellular response to infrared radiation involves retrograde mitochondrial signaling. Free Radic Biol Med, 2007, 43, 128-135.
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|Date:||Dec 1, 2008|
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