Skin is the outermost organ, acting as a protective barrier against constant and cumulative exposure to damaging environmental factors (extrinsic aging), which magnify the effects of biological (intrinsic) skin aging.1 Among the extrinsic factors, chronic solar exposure, in addition to being vital for many biochemical processes, is known as a major trigger for photoaging.
Sunlight encompasses a wide spectrum of radiation, including high-energy ultraviolet wavelengths (UV, 280-400 nm), visible light (400-700 nm) and infrared (IR, 700 nm-1 mm). While the deleterious effects of UV radiation, which accounts for only about 7% of the radiation reaching skin, are considered the main cause of photoaging,2 increasing evidence suggests high-energy visible light (HEV), also known as blue light, and IR significantly contribute to photoaging.3-6
Notably, in addition to sunlight, other artificial sources such as smartphones, tablets and computers contribute to our daily exposure to HEV light. During the COVID-19 pandemic, the usage of these blue- light-emitting devices enormously increased.7 In addition to well-known chronobiological effects in skin linked to blue light exposure,8 recent observations have described photodamage following blue light exposure as a consequence of an increased production of free radicals;3, 9, 10 impairment of skin barrier functioning; and skin hyperpigmentation.11
IR accounts for more than half of the solar radiation reaching skin and it can penetrate deeper than UV, thus triggering damage in both epidermal and dermal layers. Several molecular mechanisms have been described behind IR-promoted photoaging, including oxidative stress mainly due to mitochondrial dysfunction.12-15 Oxidative stress together with the increase in temperature in skin have been found to: promote the overexpression of the molecular sensor of adverse stimuli—the TRPV-1 (Transient Receptor Potential vanilloid type 1) channel;3, 16, 17 upregulate matrix metalloproteinases (MMP);18, 19 and reduce type I pro-collagen gene expression.19
These studies showed that at a molecular level, blue light and IR play a significant role in the photoaging process through common or distinctive mechanisms affecting epidermal homeostasis.5 This gained knowledge has sparked interest for cosmetic products that are able to prevent oxidative stress and counteract other cellular damage caused by IR and blue light exposure that are not neutralized by sunscreen actives.20
In relation, the work described here sought to determine the preventive efficacy of a Pelargonium capitatum hydrosoluble extract (PcHE) to counteract the activation of skin-damaging pathways triggered by IR, HEV and UV-irradiation. The ingredient is derived from a stem cell culture from Pelargonium capitatum leaves, a medicinal perennial branched herb belonging to the Geraniaceae family, also known as rose geranium...
- Krutmann, J., Bouloc, A., Sore, G., Bernard, B.A. and Passeron, T. (2017). The skin aging exposome. J Dermatological Science 85(3) 152-161.
- Gromkowska-K¸epka, K.J., Pu´scion-Jakubik, A., Markiewicz-.Zukowska, R. and Socha, K. (2021). The impact of ultraviolet radiation on skin photoaging—Review of in vitro studies. J Cos Derm 20(11) 3427-3431.
- Dupont, E., Gomez, J. and Bilodeau, D. (2013). Beyond UV radiation: A skin under challenge. Intl J Cos Sci 35(3) 224-232.
- Grether-Beck, S., Marini, A., Jaenicke, T. and Krutmann, J. (2014). Photoprotection of human skin beyond ultraviolet radiation. Photodermatology, Photoimmunology & Photomedicine 30(2-3) 167-174.
- Hudson, L., Rashdan, E., Bonn, C.A., Chavan, B., Rawlings, D. and Birch-Machin, M.A. (2020). Individual and combined effects of the infrared, visible, and ultraviolet light components of solar radiation on damage biomarkers in human skin cells. FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology 34(3) 3874-3883.
- Pourang, A., Tisack, A., Ezekwe, N., Torres, A.E., Kohli, I., Hamzavi, I.H. and Lim, H.W. (2021). Effects of visible light on mechanisms of skin photoaging. Available at https://pubmed.ncbi.nlm.nih.gov/34585779/
- Jakhar, D., Kaul, S. and Kaur, I. (2020). Increased usage of smartphones during COVID-19: Is that blue light causing skin damage? J Cos Derm 19(10) 2466-2467.
- Dong, K., Goyarts, E.C., Pelle, E., Trivero, J. and Pernodet, N. (2019). Blue light disrupts the circadian rhythm and creates damage in skin cells. Intl J Cos Sci 41(6) 558–562.
- Vandersee, S., Beyer, M., Lademann, J. and Darvin, M.E. (2015). Blue-violet light irradiation dose dependently decreases carotenoids in human skin, which indicates the generation of free radicals. Oxidative Medicine and Cellular Longevity 579675.
- Nakashima, Y., Ohta, S. and Wolf, A.M. (2017). Blue light-induced oxidative stress in live skin. Free Radical Biology & Medicine 108 300–310.
- Regazzetti, C., Sormani, L., ... Passeron, T., et al. (2018). Melanocytes sense blue light and regulate pigmentation through opsin-3. JID 138(1) 171-178.
- Schroeder, P., Pohl, C., Calles, C., Marks, C., Wild, S. and Krutmann, J. (2007). Cellular response to infrared radiation involves retrograde mitochondrial signaling. Free Radical Biology and Medicine 43(1) 128-135.
- Krutmann, J. and Schroeder, P. (2009). Role of mitochondria in photoaging of human skin: The defective powerhouse model. JID Symposium Proceedings 14(1) 44-49.
- Darvin, M.E., Haag, S.F., Lademann, J., Zastrow, L., Sterry, W. and Meinke, M.C. (2010). Formation of free radicals in human skin during irradiation with infrared light. JID 130(2) 629-631.
- Kawamura, K., Qi, F. and Kobayashi, J. (2018). Potential relationship between the biological effects of low-dose irradiation and mitochondrial ROS production. J Radiation Research 59(suppl_2) ii91–ii97.
- Akhalaya, M.Y., Maksimov, G.V., Rubin, A.B., Lademann, J. and Darvin, M.E. (2014). Molecular action mechanisms of solar infrared radiation and heat on human skin. Aging Res Reviews 16 1-11.
- Hsu, W.-L. and Yoshioka, T. (2015). Role of TRP channels in the induction of heat shock proteins (Hsps) by heating skin. Biophysics (Nagoya-Shi, Japan) 11 25-32.
- Lee, Y.M., Li, W.H., Kim, Y.K., Kim, K.H. and Chung, J.H. (2008). Heat-induced MMP-1 expression is mediated by TRPV1 through PKCalpha signaling in HaCaT cells. Exper Derm 17(10) 864-870.
- Cho, S., Shin, M.H., Kim, Y.K., Seo, J.-E., Lee, Y.M., Park, C.-H. and Chung, J.H. (2009). Effects of infrared radiation and heat on human skin aging in vivo. JID Symposium Proceedings 14(1) 15-19.
- Haywood, R., Volkov, A., Andrady, C. and Sayer, R. (2012). Measuring sunscreen protection against solar-simulated radiation-induced structural radical damage to skin using ESR/spin trapping: Development of an ex vivo test method. Free Radical Res 46(3) 265-275.