Common fatty acids cause increased temperature and pain in psoriasis skin lesions

A common fatty acid found in the Western diet breaks down into compounds, resulting in increased temperature and painful (but not itchy) sensitivity of psoriasis skin lesions
.
This finding may contribute to a better understanding of how lipids communicate with sensory neurons and potentially improve pain and sensitivity treatments
for psoriasis patients.

Linoleic acid is a fatty acid found in vegetable oils, nuts, and seeds and is one of
the main fatty acids in the Western diet.
Metabolites of linoleic acid—products formed when the body breaks down linoleic acid through digestion—play a role
in the skin's barrier function.

Santosh Mishra, associate professor of neuroscience at North Carolina State University and corresponding author of the study, said: "We noticed that two types of lipids from linoleic acid are high
in psoriasis lesions.
" "This led us to wonder if lipids affect how sensory neurons in these lesions communicate
.
" We decided to investigate whether their presence is related to
temperature or pain allergies reported by many psoriasis patients.
”

The team used mass spectrometry to establish a lipid profile
of psoriasis skin lesions.
They focused on two types of linoleic acid-derived lipids, or oxidized lipids: 13-hydroxy-9,10-epoxyoctadecynoate (9,13-EHL) and 9,10,13-trihydroxyoctadecenoate (9,10,13-THL).

The first form, 9,13-EHL, can be converted to a more stable form of 9,10,13-THL by interacting with certain enzymes
.

The researchers found that while both forms bind to receptors on sensory neurons within the skin, the more stable 9,10,13-THL had a longer-lasting effect
than 9,13-EHL.

They also found that once lipids bind to neuronal receptors, they activate neurons expressing TRPA1 and TRPV1 receptors, which are associated with temperature and pain hypersensitivity reactions, opening communication pathways
with the central nervous system.

Interestingly, lipids have no effect
on itching.

"Surprisingly, these lipids cause allergies but do not affect the itching sensation, which is often the most troublesome symptom
of psoriasis," Mishra said.
"This most likely has something to do with how neurons are activated — a mechanism
that we haven't discovered yet.
"

Now that the link between linoleic acid and hypersensitivity to temperature and pain has been established, the researchers wanted to further explore how this response occurs
.
They hope that the answers to these questions can help relieve these symptoms
in psoriasis patients.

"We know that this lipid is transferred from one form to another, but we don't yet know what causes it
," Mishra said.
"We also know what proteins lipids bind to, but we don't know where
.
Answering these questions may lead to new treatments or dietary solutions
for some psoriasis patients.
”

The study was published in the journal JID Innovation and was supported
by the National Institute on Aging and the National Institutes of Health.
Josh Wheeler, a postdoctoral researcher at North Carolina State University, is the first author
.