Promoting skin barrier function and anti-microbial defences: a role for the enzyme arginase.

What is it about?

Atopic dermatitis (‘AD’ for short) is a common skin condition. AD causes problems with the skin barrier (known as the ‘epidermis’). These problems can lead to infections that worsen symptoms. A healthy skin barrier involves a balance between cells multiplying (‘proliferating’) and changing their function (‘differentiating’). A key feature of AD is a disruption of this balance. A protein enzyme called arginase (or ‘ARG’) could control this process, as it influences skin barrier regulation and damage repair. This study aimed to investigate the role of ARG in the skin barrier. We examined the function of ARG using laboratory techniques and analysing human skin samples. The largest amount of ARG was found in the top layers of human skin. In cell culture of skin cells, the amount of ARG increased as the skin cells differentiated. ARG also increased the amount of some other proteins that help protect the upper layers of the skin barrier and antimicrobial proteins in the skin. Together, this suggests that ARG is involved in how the skin barrier works and its defence against microbes. Importantly, cells without ARG activity worked less well. The study also looked in a model of AD and showed skin cells expressed much less ARG than normal healthy skin suggesting that ARG activity is dampened in AD. This study identifies a role for ARG in the antimicrobial function of skin and promoting the differentiation of skin barrier cells. As the amount of ARG produced in people with AD is less, controlling the activity of ARG might help in the treatment of AD.

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Photo by Nsey Benajah on Unsplash

Photo by Nsey Benajah on Unsplash

Why is it important?

Arginase 1 (ARG1) is an enzyme expressed by skin cells (keratinocytes) that drives several functions linked to skin barrier regulation. Atopic dermatitis (AD) is linked to impaired skin barrier via altered keratinocyte differentiation and susceptibility to infection. ARG1 promotes keratinocyte differentiation and antimicrobial responses. Supplementation with downstream products of ARG1 activity could restore barrier proteins and antimicrobial peptides. Targeting ARG1 might contribute to disease management for conditions with aberrant keratinocyte barrier function such as atopic dermatitis.

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