Lipid Metabolism & Microbiome of Dry Skin

• Application of a body lotion improves skin barrier properties
• Skin ceramide profile is affected by prolonged application
• Skin microbiome changes upon the 5 weeks application


XEROSIS, known as dry skin, affects one-third of the population worldwide, causing itching, irritation, and cracking or peeling. The external skin layer, the stratum corneum, is essential for skin barrier properties, allowing maintaining hydration and regulating trans-epidermal water loss. Here and further, when we talk about skin, we mean the stratum corneum layer. Particular lipids play an essential role in maintaining the skin lipid barrier functions, and lipidome alterations upon application of skin moisturizer can shed the light on the effectiveness of a body lotion. Finally, the skin microbiome has an impact on the condition of the skin. Both parameters, microbiome, and lipidome, are to be analyzed to evaluate the effect of a body lotion on (dry) skin.

A recent study by Murphy and Mayes addresses the changes in skin barrier functions, dryness, cohesivity, alteration of dry skin lipids, and skin microbiome before and after the application of a moisturizing body lotion containing glycerol, free fatty acids (FFAs) and a small number of occlusives. Study participants were examined before a body lotion application to set the baseline, and the follow-up examination was performed 5 weeks after the regular body lotion application.

Post-intervention the skin hydration status, measured by a corneometer, showed significant improvement, as well as cohesivity. Further, changes in stratum corneum lipids were investigated by measuring cholesterol, ceramides, and free fatty acid compositions in tape strips obtained from study participants to investigate skin lipid profile variability.

Free fatty acids levels were measured in the outer-most 5 tape strips for both, baseline and a follow-up time point. Total FFA level increased from 51,05 to 134,05 pmol/ug. Detailed FFA analysis revealed significant increases in FFAs from C14:0 to C20:0 chain length. Cholesterol level increased from 29,85 to 32,35 pmol/ug for the outer-most 5 strips, while for the 16-20 strips cholesterol level increased from 40,94 to 63,34 (pmol/ug).

Changes of total FFA level prior and post intervention, measured in the outer-most 5 tape strips: The total FFA level significantly increased within 5 weeks of the body lotion application. B Changes of cholesterol level prior and post intervention, measured in the outer-most 5 tape strips and strips 16-20: While the cholesterol level on strips 1-5 did not change, the 16-20 strips a significant increase in cholesterol within 5 weeks of the body lotion application.
Murphy, et al. Sci Rep 12, 5223 (2022). 10.1038/s41598-022-09231-8

Total ceramides level increased from 2,85 to 3,80 (pmol/ug) upon intervention. 358 ceramide species were measured and assigned to 12 classes, where 9 out of 12 classes significantly increased upon intervention.

Changes of total ceramides level prior and post intervention, measured in 20 strips: Total level of ceramides increased after the body lotion application for 5 weeks. B Changes in each ceramide subclass: A significant increase upon the body lotion treatment was detected in AdS**, AH**, AP**, AS**, EOH***, EOS*, NH**, NP*, and NS** ceramide subclasses. *, P < 0.05; **, P < 0.01; ***, P < 0.001.
Murphy, et al. Sci Rep 12, 5223 (2022). 10.1038/s41598-022-09231-8

Overall, changes in stratum corneum lipids, in free fatty acids (r = 0.79, p < 0.0001) and ceramides (r = 0.44, p = 0.007) levels, are positively correlated to skin hydration measured by corneometer.

Lastly, the dry skin microbiome pre- and post-intervention was assessed and revealed no major changes after the treatment.

In general, it is challenging to robustly measure the skin microbiome changes because of its high level of inter-individual variation, especially with regards to less dominant microbial community members. However, a single genus (Xanthomonas) and species (Xanthomonas campestris) were found to be more abundant in participants post-intervention, as well as S. epidermidis. Further analysis showed the differences in particular biosynthetic pathways 5 weeks after application.

Analysis of microbiome pathways identified at baseline and Week 5: The upregulation of oleate, palmitoate, mycolate, stearate, dodecanoate, and palmitoate biosynthesis pathways is observed.
Murphy, et al. Sci Rep 12, 5223 (2022). 10.1038/s41598-022-09231-8

This study investigated the dry skin lipid composition, as well as the skin microbiome, and its alterations upon a moisturizing body lotion. Stratum corneum lipid barrier experiences changes in the ceramides, FFA, and cholesterol composition upon treatment, resulting in the hydration level increase. Changes in stratum corneum lipid biosynthesis were detected in oleate, palmitate, stearate, and other pathways. The results of this study allows to quantify the effect of lotions on skin microbiome and skin lipidome.

Lipotype Lipidomics technology can be used to characterize the lipid profile of skin. These data can provide insight into a wide variety of conditions, including xerosis, atopic dermatitis, acne, and others.