Early research suggests that linoleic acid, a fatty acid common in western diets, may contribute to sensations of heat and pain in psoriatic lesions.
These findings come from a paper published in JID Innovations (Dec. 25, 2022).
Metabolites of linoleic acid—common in vegetable oils, nuts and seeds—were found to bind to receptors on sensory neurons.
“We noticed high levels of two types of lipids derived from linoleic acid in psoriatic lesions,” said the study’s corresponding author Santosh Mishra, PhD, in a press release. “That led us to wonder whether the lipids might affect how sensory neurons in these lesions communicate. We decided to investigate whether their presence could be related to the temperature or pain hypersensitivity that many psoriasis patients report.” Dr. Mishra is an associate professor of neuroscience at North Carolina State University in Raleigh, N.C.
The research team used mass spectrometry to create lipid profiles of skin from psoriatic lesions. They focused on two types of linoleic acid-derived lipids: 13-hydroxy-9,10-epoxy octadecenoate (9,13-EHL) and 9,10,13-trihydroxy-octadecenoate (9,10,13-THL). The first form, 9,13-EHL, can convert into the more stable 9,10,13-THL form via interaction with certain enzymes.
Investigators found that while both forms bind to receptors on sensory neurons within the skin, the more stable form—9,10,13-THL—had a longer-lasting effect than 9,13-EHL.
They also found that once the lipids bind to the neuronal receptor, they activate the neurons expressing TRPA1 and TRPV1 receptors that are involved in temperature and pain hypersensitivity, opening communications channels to the central nervous system. However, the lipids did not have any effect on itch.
“It was surprising that these lipids could create hypersensitivity but not impact itch sensation, which is usually the most troublesome symptom associated with psoriasis,” Dr. Mishra said. “This most likely has to do with how the neuron is activated—a mechanism we still haven’t uncovered.”
The researchers want to further explore exactly how the association between these fatty acids and the temperature and pain sensitivity response is being created. They say they hope the answers may lead to solutions that can relieve these symptoms in psoriasis patients.
“We know that this lipid moves from one form to another, but don’t yet know what causes that,” Dr. Mishra said. “We also know what protein the lipids are binding to, but not where the bond occurs. Answering these questions may hopefully lead to new therapies or dietary solutions for some psoriasis sufferers.”
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