Sun-aged Skin is Chronically Inflamed

–Photoaging is a process resulting from chronic sun exposure and this article shows that the inflammation generated by Ultraviolet exposure continues as a somewhat chronic inflammatory process which persists even when UV exposure ceases.

Please see the abstract below.

Abstract
-Photoaging is a major senescence process in human skin, with changes such as rough texture, elastosis and irregular pigmentation.
-Previous reports demonstrated that repetitive UVB exposure for several months evoked irreversible changes in hairless mice, similar to that noted in photo aged skin, thus, treated mice became a photo aging model. Although the photoaging mechanism remains unclear, prolonged inflammation due to repetitive UVB irradiation is the suspected cause.

-To further study photo aging, we compared UVB-exposed and unexposed skin in individual mice using half-body exposure to repetitive UVB.

Results
-After 8 weeks, UVB-exposed area had a faint reddish and swollen appearance, with loss of texture. This change persisted  for more than 3 months after final exposure, and did not expand to involved peripheral areas.
-Persistent inflammation int he lesion was suggested by immunohistochemical analysis and observation of chronic reactive oxygen species (ROS) generation using a bioimager and intravenous injection of an ROS indicator. We next examined the distribution of phosphoglycerate mutase (PGAM), an aging marker that decreases in senescent cells.
-As expected, recruitment of fibroblasts and keratinocytes with specific decrease in PGAM was observed in the photo aged area, suggesting progression of cell aging. We also noted decrease of PGAM in inflammatory skin lesions unaccompanied by photo aging; chronic inflammation might result in decreased PGAM in photo aged skin.

These findings showed that chronic inflammation persisted in photo aged skin, and may evoke multiple changes along with progressive photo aging.

P12-15. Persistent inflammation in photo-aged skin. Yoshida M et al. Japanese Society for Investigative Dermatology 2016 – Sendai. Japan