Background: Fibulin- 5 was recently found as a secreted extracellular matrix protein that functions as a scaffold for elasticfibres. However, the distribution of fibulin- 5 in human skin and its changes during the ageing process are not known. Objectives: To explore the involvement of fibulin- 5 in skin ageing, the age- dependent changes in fibulin- 5 localization in human skin were examined compared with those of other elastic fibre components including elastin, fibrillin- 1 and fibulin- 2. Methods: The distribution of elastin, fibrillin- 1, fibrillin- 2, fibulin- 2 and fibulin- 5 was investigated by means of immunohistochemistry using their specific antibodies. Skin samples were recovered from 12 healthy subjects undergoing plastic surgery. Ultraviolet (UV) B- irradiated or control nonirradiated buttock skin samples were obtained from two healthy volunteers at 2 days after the irradiation at 2 minimal erythemal doses. Results: In the reticular dermis of young sun- protected skin from the upper arm, fibulin- 5 colocalized with the other elastic fibre components, while in the papillary dermis fibulin- 5 showed candelabra- like structures perpendicular to the epidermiswith an unstained area just beneath the epidermis, which was similar to that of elastin but not fibrillin- 1. Fibulin- 5 in the reticular dermis decreased and disappeared with age even in sun- protected skin from the thigh, abdomen and upper arm. In sun- exposed skin, fibulin- 5 was extremely reduced in the dermis of cheek skin even from a 20- year- old man. UVB irradiation reduced fibulin- 5, fibulin- 2 and elastin markedly, moderately and weakly, respectively, compared with levels in control nontreated skin. Interestingly, the deposition of fibulin- 5 was increased in solar elastosis, like that of other elastic fibre components. Conclusions: These results suggest that fibulin- 5 is a good marker of skin ageing and that the earlier loss of fibulin- 5 may involve age- dependent changes in other elastic fibre components.
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