Total Defense + Repair: A Novel Concept in Solar Protection and Skin Rejuvenation.

ABSTRACT

For more than a century, solar radiation has been known to contribute significantly to the extrinsic aging of skin. Until recently, this was almost exclusively attributed to the photodamage caused by ultraviolet (UV) light. However, a growing body of evidence now indicates that both infrared (IR) and visible light may also contribute to extrinsic skin aging. Infrared radiation, comprised of IR-A, IR-B, and IR-C, accounts for 54.3% of the total solar radiation reaching the skin. Studies have shown that IR radiation is also responsible for skin aging. Thus, IR-A radiation regulates hundreds of genes in skin, with roles in extracellular matrix (ECM) homeostasis regulation, apoptosis, cell growth, and stress responses. IR-B and IR-C radiation are primarily responsible for the increase in skin temperature associated with solar exposure, and are implicated in heat-related skin destruction of collagen and elastin, which is characterized by an increase in the expression of matrix metalloproteinases (MMPs). The contribution of visible light to photoaging is less well understood; however, some preliminary indication associates visible light with the upregulation of MMPs' expression, DNA damage, and keratinocyte proliferation. Interestingly, the common denominator that links skin damage to the different solar wavelengths is the enhanced production of reactive molecule species (RMS) and therewith increased oxidative stress. SkinMedica® Total Defense + Repair (TD+R; SkinMedica Inc., an Allergan company, Irvine, CA) is a "superscreen," which combines broad spectrum UV protection with a unique blend of antioxidants (SOL-IR Advanced Antioxidant Complex™) that provide protection from IR radiation while promoting skin repair. Preclinical studies have indicated that TD+R SPF34 prevents the formation of UV-induced sunburn cells and cyclobutane pyrimidine dimers while preserving or improving the expression of ECM genes. In addition, it prevents IR-A-triggered fragmentation of elastin fibers and expression of MMP-1. Initial clinical studies indicate that TDR+R SPF34 reduces the increase in surface temperature seen with IR radiation. A significant improvement in the appearance of lines and wrinkles was reported as early as week 2 in patients using TDR+R SPF34. In summary, we observed that the unique blend of antioxidants present in TD+R acts in harmony with SPF active ingredients, expanding solar protection beyond UV radiation and counterbalancing the deleterious effects of free radicals on skin cells by promoting endogenous repair.