The skin has varied composition throughout the body, which may affect the skin′s susceptibility to certain diseases. Aging, trauma and environmental and genetic factors can cause several skin conditions.

Two new UC Davis Health studies have best explained why certain body parts are more prone to skin diseases than others.

The first study explains that the compositional differences in the skin′s lipids and proteins across different body sites determine skin structure & function and disease susceptibility and may also explain why different skin diseases are found at different body sites. These differences will help in designing skin care products in the future.

The second study explains how skin cells interact with the immune system. We know that keratinocytes secrete substances that both increase and decrease inflammation. The researchers of the second study used single-cell sequencing to analyze each keratinocyte individually and observed the expression of these immune-modulating molecules in specific layers of the epidermis.

The researchers found the keratinocytes in the outer layer of the epidermis secreting proinflammatory molecules, particularly interleukin (IL)-36, which is the main mediator of a subtype of psoriasis. They also noticed that PCSK9 regulates the amount of IL-36 in the skin, and individuals with variations in their PCSK9 gene are at greater risk of developing psoriasis.

Source: Merleev AA, Le ST, Alexanian C, et al. Biogeographic and disease-specific alterations in epidermal lipid composition and single-cell analysis of acral keratinocytes. JCI Insight.2022;7(16):e159762.