Covalently bound lipids in reconstructed human epithelia

Area of Science:

• Dermatology
• Biochemistry
• Cell Biology

Background:

• The stratum corneum's lipid composition is crucial for skin barrier function.
• Understanding lipid differences in reconstructed epithelia is key for developing artificial skin and studying skin diseases.

Purpose of the Study:

• To investigate and compare the free and covalently bound lipid composition in reconstructed epithelia using normal human keratinocytes and transformed cell lines (HaCaT, SCC-12F2, SCC-13) against native human skin.
• To identify differences in lipid profiles that may correlate with altered skin barrier properties.

Main Methods:

• Lipid extraction using chloroform-methanol mixtures and alkaline hydrolysis.
• High-performance thin-layer chromatography (HPTLC) for analyzing solvent-extractable and non-extractable lipids.
• Gas-liquid chromatography (GLC) for assessing fatty acid profiles.

Main Results:

• Native and normal reconstructed epidermis share similar covalently bound lipids (omega-hydroxyceramides, omega-hydroxyacids, free fatty acids) and overall lipid composition.
• Epithelia reconstructed with transformed cell lines showed reduced ceramide content, absence of polar ceramides, low free fatty acids, and a near absence of covalently bound lipids.
• Relative proportions of omega-hydroxyceramides were similar in native and normal reconstructed stratum corneum.

Conclusions:

• Reconstructed epidermis using normal human keratinocytes closely mimics the lipid profile of native stratum corneum.
• Transformed cell lines lead to significant alterations in both free and bound epidermal lipids, suggesting impaired barrier function.
• Lipid profile imbalances in transformed cell-derived epithelia may explain differences in stratum corneum lipid phase behavior.