Research Techniques Made Simple: Lipidomic Analysis in Skin Research

The heterogeneity and complexity of skin surface lipids in human skin health and disease

The outermost epidermal layer of the skin, the stratum corneum, is not simply a barrier that safeguards skin integrity from external insults and invaders, it is also a delicately integrated interface composed of firm, essentially dead corneocytes and a distinctive lipid matrix. Together, the stratum corneum lipid matrix and sebum lipids derived from sebaceous glands give rise to a remarkably complex but quite unique blend of skin surface lipids that demonstrates tremendous heterogeneity and provides the skin with its indispensable protective coating. The stratum corneum lipid matrix is composed primarily of three major lipid classes: ceramides, non-esterified fatty acids and cholesterol, whereas sebum is a waxy mixture predominantly composed of acylglycerols, wax esters, non-esterified fatty acids, squalene, cholesterol and cholesterol esters. The balance of these skin surface lipids in terms of their relative abundance, composition, molecular organisation and dynamics, and their intricate interactions play a crucial role in the maintenance of healthy skin. For that reason, even minuscule alterations in skin surface lipid properties or overall lipid profile have been implicated in the aetiology of many common skin diseases including atopic dermatitis, psoriasis, xerosis, ichthyosis and acne. Novel lipid-based interventions aimed at correcting the skin surface lipid abnormalities have the potential to repair skin barrier integrity and the symptoms associated with such skin diseases, even though the exact mechanisms of lipid restoration remain elusive.

Electroacupuncture promotes skin wound repair by improving lipid metabolism and inhibiting ferroptosis

Lipid metabolism plays an important role in the repair of skin wounds. Studies have shown that acupuncture is very effective in skin wound repair. However, there is little knowledge about the mechanism of electroacupuncture. Thirty-six SD rats were divided into three groups: sham-operated group, model group and electroacupuncture group, with 12 rats in each group. After the intervention, local skin tissues were collected for lipid metabolomics analysis, wound perfusion and ferroptosis-related indexes were detected and finally the effect of electroacupuncture on skin wound repair was comprehensively evaluated by combining wound healing rate and histology. Lipid metabolomics analysis revealed 37 differential metabolites shared by the three groups, mainly phospholipids, lysophospholipids, glycerides, acylcarnitine, sphingolipids and fatty acids, and they could be back-regulated after electroacupuncture. The recovery of blood perfusion and wound healing was faster in the electroacupuncture group than in the model group (p < 0.05). The levels of GPX4, FTH1, SOD and GSH-PX, which are related to ferroptosis, were higher in the electroacupuncture group than in the model group (p < 0.05). The levels of ACSL4 and MDA were lower in the electroacupuncture group than in the model group (p < 0.05). Electroacupuncture may promote skin wound repair by improving lipid metabolism and inhibiting ferroptosis in local tissues.