Sun is ambivalent: essential to health, on the one hand and a source of risks on the other hand. Its effects are beneficial for the mood through the endorphin synthesis, on health with the induction of the vitamin D synthesis, but it can also cause severe damages to the skin and eyes.
In Western countries, behaviours and habits concerning sun exposure have evolved considerably in recent decades. From the 1930s, the traditional mistrust to sun gradually gave way to the desire of being tanned resulting in an increased exposure to sun then correlated with an increase in immunosuppression, in the number of skin cancers and in the acceleration of skin aging.
Antioxidants and photo-aging
Regarding photo-aging, the simplest markers, according to Dr. Marwin Edeas, President of the SFA, are "free radicals and ROS (reactive oxygen species), but a decrease in the length of telomeres and in mitochondrial deterioration can also be observed."
Sun radiations, depending of their nature penetrate more or less deeply in the skin layers generating photo-products and free radicals. The measurements of the products resulting from this oxidative stress are of great interest to researchers wishing to know the reactivity of induced mechanisms and thus provide the skin with adapted antioxidants.
"We have enough mechanistic, epidemiological and pathophysiological data to confirm the existing link between oxidative stress and skin diseases," confirmed Dr. Olivier Sorg from the Dermato-Toxicology Service at the University of Geneva. He considers, however, that "providing antioxidants to the skin is of no value if they are not well chosen and administered at the appropriate time and place."
A real challenge. Especially when we know that studies showing the value of the topical application of these molecules often result from in vitro tests. Very few clinical studies exist and Dr. Sorg is convinced that "the in vitro reactivity of molecules is different in an in vivo system, the micro environment being very important."
Another difficulty arises from the non-standardization of measurement methods on oxidation products "Methods used such as tissue assays, photometry, spectroscopic measurements... differ depending of the system used," explained Dr. Olivier Sorg.
However, scientists generally agree on the high potential of antioxidant molecules. For Dr. Marwin Edeas the stimulation of the endogenous synthesis of antioxidants could help reach difficult targets such as mitochondria, and adjust dosage according to the individual. Indeed "each person has its own needs in anti-oxidants, depending of their morphology and metabolism."
A clever balance must be found, especially since all free radicals must not be fought: a small fraction of them playing a part in the cellular mechanisms required for the proper functioning of the body. An ambivalent nature which is also found, according to Matthias Schafer from the Department of Biology which is part of the Institute of Cell Biology ETH Zurich, in the Nrf2 transcription factor. Depending of the conditions under which it is activated, it protects the skin from oxidative stress, but it can also disturb cellular functions in the epidermis, hair follicles and sebaceous glands.
And for tomorrow?
Would not all these issues on photo-aging find an answer by forgetting about aging? In any rate this is the track explored by Stéphanie Lacour, from the Bertarelli Foundation Chair in Neuroprosthetic Technology in Lausanne. With her team, she is working on a skin substitute called electronic skin whose goal is to mimic the sensory functions of the skin and to connect it with the neuronal system. To date, this research work is at the development stage of sensors with a capacity towards deformation similar to that of skin. To achieve this, technologies in microelectronics were adapted to super flexible sensors.
Meanwhile, Nicolas Fortunel from the "Stem Cells and radiation" service of the Genopôle in Evry demonstrated the huge regeneration potential of tissue stem cells, particularly of keratinocytes through clonogenic assays, of tissue reconstruction capacity in 2D and 3D. According to Fortunel "the cell does not need to rejuvenate but to preserve its cellular environment" bearing in mind that ionizing radiations and UVs are great sources of genotoxic stress.
To end the day, the Berkem company unveiled its new active, Origa’light, the Laboratorios Cinfa its Be Cell Energy Booster while the ICDD (Innovative Concept in Drug Development) presented a Mitosafe® method to assess the action of an antioxidant on mitochondrial functions.
