Uncover the secrets of the skin: Studies have shown that the formation of skin throughout the body is different

Why are some parts of the body more susceptible to skin diseases than others?

Two new studies by UC Davis Health explore how differences in skin composition can lead to skin diseases such as psoriasis and atopic dermatitis
.

"The skin doesn't have a uniform composition throughout the body," said
Emanual Maverakis, a professor of dermatology and molecular medicine microbiology at the University of California, Davis, and senior author of both studies.

Skin diseases affect about 84.

Body parts determine the structure and function of the skin and the susceptibility to disease

The skin is the largest organ
of the human body.

This layer must meet environmental challenges
specific to various parts of the body.

The composition of the skin depends on a variety of factors, including the structure of the skin barrier, cell types, and the genes
they express.

Until recently, little
was known about the cellular and molecular processes behind these differences.

The epidermis has a "brick and mortar" structure: molecules like ceramides, cholesterol and fatty acids make up the "mortar", and the cells called keratocytes are "bricks"
.

The researchers used single-cell sequencing to describe differences
in keratinocytes at different parts of the body.

Differences in the composition of skin lipids and proteins in different parts of the body can also explain why different skin diseases
occur in different parts.

"These findings will lead to non-diagnostic testing of common skin diseases," said
project scientist Alexander Merleev.

"These differences are also related to the future design of skin care products," said
Stephanie Le, a dermatologist resident and co-lead author of the study.

Psoriasis and the immune system

In the second study, the team looked at how skin cells interact
with the immune system.

Previously, it was known that keratinocytes could secrete substances
that increase and decrease inflammation.

The keratinocytes of the lowest layer of the epidermis secrete immunosuction and immune anti-inflammatory molecules
.

IL-36 is the main mediator
of a subtype of psoriasis, an inflammatory skin disease.

"We found that different layers of the skin secrete different immune mediators, which is an example
of how the skin interacts with the immune system.
When the molecules secreted by different skin layers are unbalanced, some people develop skin diseases such as psoriasis
.
Antonio Ji-Xu, a researcher at the University of California, Davis and co-lead author of the study, said
.

Both studies were published in JCI Insight
.

essay

Biogeographic and disease-specific alterations in epidermal lipid composition and single-cell analysis of acral keratinocytes