Ceramides are composed of sphingosine analogs and long-chain fatty acids bound by amide bonds, and are the most important of the sphingolipid compounds. Ceramide is synthesized and secreted by lamellar vesicles, which together with cholesterol (25%) and free fatty acids (15%) constitute the intercellular lipids (ceramide 50%) involved in maintaining the skin barrier function. It also has various physiological and pharmacological functions, such as regulation of cellular immunity, delaying aging, and antitumor.
Ceramides and skin
Mechanism of skin barrier maintenance and enhancement: Ceramide is broken down in the epidermis by lamellar vesicles that transport glucosylceramide from the granular layer to the stratum corneum. During this process, ATP-binding cassette transporter superfamily A12 (ABCA12) promotes the aggregation of glucosylceramide in lamellar vesicles. It has been shown that ABCA12 deficiency leads to the development of ugly angle-like ichthyosis. Ceramide containing ω-OH can covalently bind to the endothelin of the keratinized envelope of keratinized cells, linking the lipid matrix and keratinized cells, enhancing the barrier function of the skin, reducing the entry of harmful substances into the skin through pores and sweat glands, and thus having anti-allergic effects.
Anti-aging effect and mechanism: The carbon chain of sphingosine in ceramide has double bonds and terminal hydroxyl groups, indicating that it is easily oxidized to break the double bonds and has antioxidant effect. Studies have shown that low concentration of ceramide can stimulate fibroblast proliferation and inhibit the expression of matrix metalloproteinases, so ceramide has certain anti-aging effects.
Moisturizing effect and mechanism: Ceramide has two long-chain hydrocarbon groups (one in LCB and one in FA), which are hydrophobic. The two to three hydroxyl groups in LCB are hydrophilic with the amide bond in the binding site of FA and LCB, and these two properties are important for its water retention in the stratum corneum. In addition, ceramide significantly promotes the expression levels of filament polymeric protein mRNA and protein. Among them, the filament polymeric proteinogen is converted into polycarboxylic acids with moisturizing effect after a series of enzymatic hydrolysis when it enters the stratum corneum from the granular layer.
Ceramide and obesity
Obesity is mainly due to the body's excess caloric intake over consumption, excess energy is stored in the body in the form of fat, leading to ectopic or excessive accumulation of fat, resulting in metabolic symptoms such as elevated blood glucose levels and disorders of lipid metabolism. In addition to providing cellular structural integrity, ceramide, a sphingolipid metabolite, plays a role as a second messenger in the cell signaling process. Ceramide levels have been found to be significantly higher in obese patients compared to non-obese individuals. The main mechanisms by which ceramide regulates the development of obesity and related diseases are as follows: ceramide inhibits insulin signaling and hinders glucose metabolism; induces apoptosis; impairs mitochondrial function and induces mitochondrial autophagy.
Ceramide and Cardiovascular Diseases
Elevated ceramide concentrations can lead to apoptosis of vascular endothelial cells and regulate platelet activation and coagulation, leading to thrombosis. It also regulates angiotensin, which can lead to atherosclerosis and a number of cardiovascular diseases such as hypertension.
Studies have shown that plasma ceramide can effectively predict the risk of atherosclerosis, myocardial infarction, ischemic heart disease, hypertension, stroke, type 2 diabetes, insulin resistance, etc. in the next 1-5 years. The higher the level of ceramide in a patient's blood, the higher their chances of developing cardiovascular symptoms.
Creative Proteomics uses LC-MS/MS technology to simultaneously determine the content of more than 30 ceramides, providing technical support for comprehensive ceramide assay. This method is highly sensitive and fast, allowing efficient and accurate detection of ceramide content changes.
Reference
Shabbir, M. A., Mehak, F., et al. (2021). Interplay between ceramides and phytonutrients: New insights in metabolic syndrome. Trends in Food Science & Technology, 111, 483-494.
