Human skin is increasingly exposed to infrared radiation (IRR), both from natural sunlight and artificial sources used for esthetic or medical purposes. IRR represents a nonionizing electromagnetic radiation whose wavelength ranges between 760 nm and 1 mm, and can be further classified in IRA (760-1440 nm), IRB (1440-3000 nm) and IRC (3000 nm-1 mm). IRR accounts for more than a half (54.3%) of sun total energy reaching human skin. Short wavelength in IRA range reaches the subcutaneous tissue without increasing the surface temperature of the skin markedly, whereas IRC is absorbed completely in the epidermal layers and causes an increase in skin temperature. Recent results suggest an important role for IRA, which seems to be involved, similarly to ultraviolet (UV) radiation, in dermal inflammation, photoaging and potentially in photocarcinogenesis. Changes in dermis cells and extracellular matrix (collagen degradation and accumulation of abnormal elastic fibers) contribute significantly to photoaging. These alterations follow expression variations of several genes, in particular matrix metalloproteinases (MMPs), which are induced by IRA, as well as UVA and UVB. It has been shown that IRA irradiation of human skin fibroblasts leads to an increased expression of MMP-1 without a parallel expression increase of its specific endogenous inhibitor, the tissue inhibitor of metalloproteinase-1 (TIMP-1). Such unbalanced upregulation of MMP-1 indicates that IRA, as well as UV radiation, can elicit the molecular response underlying skin photoaging. Several other cellular and physiological reactions to IRA are known, such as neoangiogenesis (another prominent feature of photoaged human skin), decrease in epidermal proliferation, Langerhans cell density and contact hypersensitivity reaction in mice, as well as an influence on cutaneous wound repair and on ferritin expression. Besides detrimental features, IRR also has some beneficial effects on human skin: significant reduction in UVB-induced keratinocytes apoptosis and UVA and UVB-induced fibroblasts death. In order to better understand its beneficial effects and to minimize its detrimental ones, it is mandatory to further study IRR mode of action. It is also crucial that photoprotection strategies must encompass measures against IRA radiation.
|Translated title of the contribution||Infrared radiation and skin|
|Number of pages||4|
|Journal||Annali Italiani di Dermatologia Allergologica Clinica e Sperimentale|
|Publication status||Published - 2013|
ASJC Scopus subject areas
- Immunology and Allergy