Cutaneous barrier function after cold exposure in hairless mice: a model to demonstrate how cold interferes with barrier homeostasis among workers in the fish-processing industry

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Abstract
Dry skin and eczema only seldomly occur in workers in the Danish fish-processing industry (FPI) during work, when their fingers and palms have a low skin surface temperature, low transepidermal water loss (TEWL), and a high capacitance. However, shortly after work, when the skin temperature has become normal, TEWL levels increase to above normal, and capacitance decreases to below normal, followed by the development of dry skin or chapping, which subsequently revert to normal over a period of hours. These observations suggest that workers in the FPI may have a delect in skin barrier function, which is, however, masked by a low skin temperature, resulting in misleadingly low TEWL levels during work. To test this hypothesis, we disrupted the permeability barrier in hairless mice with topical acetone, and exposed the treated skin to ice for 3–5h. Although TEWL rates immediately after cold exposure were low, suggesting normal barrier recovery, TEWL increased to levels slightly above pre-cold exposure levels (i.e. levels just after the barrier was disrupted with acetone) when the skin temperature reverted to normal (≥ 15min). The changes in TEWL were paralleled by equivalent changes in percutaneous penetration of the electron-dense tracer lanthanum nitrate. This indicates that cold masks a defective barrier, and inhibits barrierrepair. After a few hours at ambient temperatures, normal barrier recovery was observed. Electron microscopy revealed empty or partially empty lamellar bodies during the first 30 min post-cold exposure. After 1 h the majority of nascent LBs displayed normal morphology. Moreover, histochemical studies showed a delayed reappearance of stratum corneum intercellular lipids following cold exposure. These results demonstrate that cold exposure prevents barrier recovery after acetone disruption, and provide an explanation for the occupatonal dermatosis observed in the fish-processing industry and related occupations.