Widely expressed in the sensory nerve endings of the skin, Transient Receptor Potential Vanilloid 1 (TRPV1) is a receptor that plays an important role in the perception of pain and pruritus but also in skin inflammation, primarily by inducing the local release of several neuropeptides.

Although the mechanisms by which TRPV1-sensitizing inflammatory mediators in damaged skin have received considerable attention, the role of TRPV1 in psoriasis has so far been little explored.

However, two studies have reported that ablation of sensory nerves expressing TRPV1 reduced psoriasiform skin inflammation, demonstrating the neuronal contribution to inflammation in psoriasis.

However, the expression of TRPV1 is not limited to neurons alone. TRPV1 is also expressed by epidermal keratinocytes and skin microvessels.

For example, in 2018, transcriptomic analysis of psoriatic patient skins (by definition devoid of neuron nuclei) revealed that TRPV1 expression was increased in the skin of psoriatic patients suffering from itching (pruritus).

Regarding human keratinocytes, it is recognized that the activation of TRPV1 present on their surface induces the release of pro-inflammatory factors such as cyclooxygenase-2. In addition, the investigators have demonstrated that TRPV1 has a pivotal role in the keratinocyte production of inflammatory mediators, which is mediated by the protease-activated receptor-2 (PAR-2). However, the role of vascular TRPV1 in inflammation is not described.

The investigators hypothesize that in addition to neuronal TRPV1, non-neuronal TRPV1 receptors of non-neuronal cells (keratinocytes and endothelial cells) may be involved in the vicious circle of the inflammatory process characteristic of psoriasis. Putting TRPV1 at the center of the deregulation of the homeostatic balance including epithelial, neuronal and vascular inflammation in psoriasis is totally innovative.

Each patient will have a sample taken in the dermatology department:

• 4 skin biopsies
• A blood sample.

Patients with psoriasis will be recruited from the dermatology department. There will be no further visits, so the duration of the study is 1 day.

The samples taken will be used to determine the pleiotropic role of TRPV1 in Psoriasis Inflammation.

Inclusion Criteria:

• Patients over 18 years old with psoriasis, with or without itching (pruritus).
• Presence of lesional and non lesional zones, in unexposed areas and surface area (outside the face and folds) large enough to allow the biopsies to be performed
• Patients who have given written consent

Exclusion Criteria:

• Patients with physical or psychological incapacity to sign consent
• Patients not covered by the Social Security system
• Patients with topical treatments for psoriasis,
• Patients with systemic treatments for psoriasis,
• Patients allergic to lidocaine
• Patients over the age of majority who are subject to legal protection or who are unable to give consent
• Patients deprived of liberty by a judicial or administrative decision
• Pregnant women, parturients and breastfeeding mothers

All collected data that underlie results in a publication

Data will be available beginning three years and ending fifteen years following the final study report completion

Data access requests will be reviewed by the internal committee of Brest UH. Requestors will be required to sign and complete a data access agreement.