Cutaneous Microcirculation and Nervous Sensitivity in Psoriasis

Study Overview
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Brief Summary
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Psoriasis is a chronic inflammatory cutaneous disease, affecting 3% of the French population. Among psoriatic patients, 80% feel pain or cutaneous discomfort related to their pathology. Neurogenic inflammation's role in psoriasis has recently been put forward by a study showing that TRPV1 ion channels are necessary to establish psoriasiform inflammation in mice. The investigators hypothesize that there is a link between cutaneous sensory neuropathies and altered cutaneous microcirculation during psoriasis. In order to test this hypothesis, local vasodilators will be delivered to patients by iontophoresis and their skin blood flow in response to these molecules will be followed by laser Doppler recordings. Two recordings will be performed for each patient, both on a psoriasis plaque and on uninvolved skin, in order for the patient to be his own internal control.

Official Title
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Cutaneous Microcirculation and Nervous Sensitivity in Psoriasis

Conditions
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Psoriasis

Intervention / Treatment
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* Other: Acetylcholine iontophoresis
* Other: Sodium Nitroprussiate iontophoresis
* Other: ppi water iontophoresis
* Other: Laser Doppler recording


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Type I psoriasis Psoriasis plaques on the patient's back Exclusion Criteria: BMI > 25 Diabetic patient Arteriovenous disease history Ongoing anti-inflammatory treatment Major cardiovascular history (<3 months) Hypertension Topical treatment on the back skin (<7 days) Systemic treatment (steroids, methotrexate, retinoids, cyclosporine) or phototherapy (<1 month) Pregnant women Subject within exclusion period following a previous or ongoing biomedical study

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Healthy skin<br>Local vasodilators (acetylcholine, sodium nitroprussiate and ppi water as control) will be delivered to patients by iontophoresis on healthy skin. The skin blood flow in response to these molecules will be followed by laser Doppler recordings. | Other: Acetylcholine iontophoresis<br>* Acetylcholine will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: Sodium Nitroprussiate iontophoresis<br>* Sodium Nitroprussiate will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: ppi water iontophoresis<br>* ppi water will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: Laser Doppler recording<br>* Skin blood flow will be recorded by laser Doppler during 2 minutes before iontophoresis, and during 30 minutes following iontophoretic delivery of vasodilators.<br>|
| Experimental: Psoriasis plaque<br>Local vasodilators (acetylcholine, sodium nitroprussiate and ppi water as control) will be delivered to patients by iontophoresis on a psoriasis plaque (on the patient's back). The skin blood flow in response to these molecules will be followed by laser Doppler recordings. | Other: Acetylcholine iontophoresis<br>* Acetylcholine will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: Sodium Nitroprussiate iontophoresis<br>* Sodium Nitroprussiate will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: ppi water iontophoresis<br>* ppi water will be locally delivered to patients by iontophoresis successively on healthy skin and on psoriasis plaque (order determined by randomization).<br>Other: Laser Doppler recording<br>* Skin blood flow will be recorded by laser Doppler during 2 minutes before iontophoresis, and during 30 minutes following iontophoretic delivery of vasodilators.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| skin blood flow variation | Skin blood flow variation on healthy skin and on psoriasis plaque will be measured by Laser Doppler in response to iontophoretic delivery of vasodilator substances (sodium nitroprussiate and acetylcholine) and ppi water. Skin blood flow will be recorded during 2 minutes before iontophoresis, and during 30 minutes following iontophoretic delivery of vasodilators. | at the latest 3 months after inclusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensory detection threshold | Increasing size of Von Frey filaments will be placed onto patients' skin to assess sensory detection threshold. | at the latest 3 months after inclusion | 
| Potential discomfort sensation thresholds | Increasing size of Von Frey filaments will be placed onto patients' skin to assess potential discomfort sensation threshold. | at the latest 3 months after inclusion | 
| Heat sensitivity | Heat sensitivity will be assessed using hot (50°C) and cold (4°C) water | at the latest 3 months after inclusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Psoriasis, Microcirculation, TRPV1