Elastin changes during chronological and photo‐ageing: the important role of lysozyme.

11 November 2006

Abstract

Background

Cutaneous ageing, as a result of combined chronological and photo-ageing in sun-exposed areas, is accompanied by major modifications of the elastic fibres.

Aim

We aimed to investigate qualitative and quantitative changes of dermal elastin fibres during cutaneous chronological and photo-ageing and the involvement of lysozyme in these processes.

Methods

Morphological, age-related changes and variations in the relative elastin content in sun-protected (buttock) and sun-exposed (forearm and face) skin of healthy volunteers were studied (145 samples). The deposition of lysozyme in elastin fibres was studied using light and immuno-electron microscopy and taking into consideration the relative efficacy of different UV wavebands (UVA or SSR (solar simulated radiation)). Our studies also included the proteolytic degradation of elastin by human leucocyte elastase (HLE) in situ.

Results

Our results indicate a reduction of elastin content with age in sun-protected and sun-exposed skin, associated for the latter with high elastin content, resulting in elastosis. Total UVA (320–400 nm), and in particular long wave UVA (UVA-1, 340–400 nm), induces lysozyme deposition in elastin fibres to a higher extent than solar simulated radiation (SSR, 280–400 nm). Immuno-electron microscopy revealed lysozyme association with the electron-dense granular amorphous elastin structures, corresponding to a basophilic degeneration induced by sun exposure. Lysozyme has no elastolytic activity in situ; however, its binding to elastin limits elastin degradation by human leucocyte elastase (HLE). In addition, a direct inhibitory effect of lysozyme on HLE was observed.

Conclusion

Our data suggest that lysozyme prevents elastin degradation by HLE after binding to the damaged parts of the elastin network and by direct lysozyme–HLE interaction, which reduces HLE proteolytic activity. These observations contribute to a better understanding of the chronological and photo-induced changes of the dermal elastic network.

Citation

Seite, S., Zucchi, H., Septier, D., Igondjo‐Tchen, S., Senni, K. and Godeau, G., 2006. Elastin changes during chronological and photo‐ageing: the important role of lysozyme. Journal of the European Academy of Dermatology and Venereology, 20(8), pp.980-987.

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