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DAVIS, Calif. — Have you ever wondered why certain parts of your body are more prone to skin diseases than others? Researchers say it’s because skin characteristics vary across different areas of the body, affecting their susceptibility to certain ailments. Researchers from UC Davis Health delved into the variations in skin composition and how they can contribute to conditions like psoriasis and atopic dermatitis.

The composition of skin is influenced by various factors, including the skin barrier’s structure, the types of cells present, and the genes they express. For instance, facial skin needs to be thin and flexible to accommodate facial expressions, while the skin on our heels requires thickness and rigidity to endure the force of walking and protect against stepping on objects.

Until recently, not much was known about the cellular and molecular processes that lead to these differences. However, the first study conducted by researchers used advanced techniques like single-cell sequencing to understand how keratinocytes, the building blocks of skin, differ at various body sites. They also examined the molecules that make up the “mortar” between the keratinocytes. The findings revealed how gene expression variations correlate with the compositional differences in lipids and proteins across body sites, providing insights into why our skin looks so distinct in different areas.

woman doing skincare
(Photo by Shiny Diamond on Unsplash)

“Our discovery that different layers of the skin secrete different immune mediators is an example of how the skin is highly specialized to interact with the immune system. Some people develop skin diseases, such as psoriasis, when there is an imbalance in the molecules secreted by the different layers of the skin,” says UC Davis research fellow Antonio Ji-Xu in a university release.

Interestingly, these variations in skin composition can also explain why certain skin diseases are more prevalent in specific locations of the body. By analyzing specific lipid alterations associated with different skin conditions, the researchers discovered that analyzing lipids collected from a piece of tape applied to the skin could help diagnose particular diseases.

“These differences are also relevant to the future design of skin care products,” adds Stephanie Le, a dermatology resident and co-lead author of the study. “They demonstrate how skin care products should be specifically formulated to match the particular body site that they will be applied to.”

The study is published in the journal JCI Insight.

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