LOXEPI

"Characterisation, synthesis and functional investigation of epidermal lipoxygenase products in inflammation"

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 Obiettivo del progetto (Objective)

'The skin has many protective functions, acting as a barrier to physical and biological threats from the external environment while regulating water loss and body temperature. Loss of the normal skin function results in inflammation and associated diseases such as psoriasis, alopecia and ichthyosis. The skin is highly-enriched in lipids and fatty acids, which can be converted by lipoxygenase (LOX) enzymes to bioactive mediators, termed eicosanoids. LOXs are a family of non heme iron enzymes of which several isoforms are present in skin. A role for several LOX isoforms in regulating epidermal integrity has been proposed, however, the detailed mechanisms involved are unknown. We recently found that LOXs can generate novel lipids comprising eicosanoids attached to membrane phospholipids in immune cells, and preliminary evidence has shown that similar lipids are present in healthy mouse skin, but the detailed structures and functions of these are yet to be characterised. This fellowship will investigate the hypothesis that esterified eicosanoids generated by LOX are involved in the physiological and pathophysiological regulation of the epidermis. Novel esterified LOX products will be structurally characterised using mass spectrometry and chromatographic approaches in both healthy mouse skin, mice deficient in a LOX isoform and a series of recombinant epidermal LOX enzymes. Purified lipid standards will be synthesised for quantification and studies of biological action. Finally, studies using wild type mice and a strain with an inflammatory hair loss phenotype will determine the role of esterified eicosanoids from LOX in regulating epidermal physiology and disease. The proposed studies will utilise genetic, chemical and structural biochemistry approaches to increase our understanding of skin physiology and may lead to design of novel treatments for inflammatory skin disorders.'

Introduzione (Teaser)

The skin acts as the first barrier to infections and to other threats from the environment, while it regulates body water content and temperature. Characterisation of its lipid content could reveal important information on how it maintains these functions.

Descrizione progetto (Article)

Loss of normal skin function results in inflammation and diseases such as psoriasis and alopecia. The skin is rich in lipids and fatty acids which get converted by lipoxygenase (LOX) enzymes to bioactive mediators, termed eicosanoids.

LOX enzymes catalyse the addition of oxygen moieties to fatty acids and could maintain skin integrity. Recently they were discovered to synthesise novel lipids attached to the surface of immune cells. However, the structural and mechanistic details underlying this process remain elusive.

The key objective of the EU-funded LOXEPI project was to investigate how LOX enzymes are involved in the physiological and pathophysiological regulation of the epidermis. To this end, scientist examined human and pig skin for the presence of such esterified eicosanoid products using high-performance liquid chromatography and mass-spectrometry methods. This led to the identification of novel LOX oxidised products which form from the consecutive action of different LOX enzymes on linoleic acid (LA).

A considerable part of the work was dedicated to the development of appropriate methods and the chemical synthesis of analytical standards that could be used in skin assays. Examination of the location of specific lipids within the epidermal tissue led to interesting observations which could link lipid localisation with function.

Using adhesive tape, scientists were able to isolate individual layers of human skin and analyse the LOX products. This provided an overview of the levels and their distribution within normal healthy skin, alongside their role in inflammation and immunity through interaction with possible receptors.

Collectively, the LOXEPI study provided an unprecedented characterisation of the lipid content of the human skin. In the long run this will lead to a better understanding of the physiological and pathophysiological regulation of the epidermis and ultimately to the design of novel treatments for inflammatory skin disorders.