Dupilumab Impact on Skin Resident Memory T Cells

Inclusion Criteria: * Subject over 18 years of age * Subject able to read, understand and give documented informed consent * Subject willing and able to comply with the protocol requirements for the duration of the study * Subject with health insurance coverage according to local regulations * For woman with childbearing potential : * Use of a highly effective method of birth control from at least 1 month prior to study enrollment until the last visit * Negative urine pregnancy test at inclusion visit A highly effective method of birth controlled is defined as one which results in a low failure rate (i.e. less than 1% per year) when used consistently and correctly, such as implants, combined oral contraceptives, intrauterine device, double barrier methods (e.g. condom with spermicide), sexual abstinence or vasectomized partner. Woman with no childbearing potential is defined as: woman with amenorrhea for at least 12 months (without an alternative medical cause); woman who had undergone a permanent sterilization method (eg bilateral tubal occlusion which includes tubal ligation procedures, hysterectomy, bilateral salpingectomy, bilateral oophorectomy); or otherwise be incapable of pregnancy. * Subject diagnosed with moderate-to-severe AD, defined as SCORAD≥20 and/or EASI≥7 (Eichenfield et al., 2014) * Subject with AD involvement of 10% (or more) Body Surface Area (BSA) according to component A of SCORAD * Subject with I, II, III or IV skin phototype (according to Fitzpatrick scale) * Subject accepting skin prick-tests and skin biopsies * Subject having a least one non lesional area on the body (off head and neck, feet and hands) * Subject eligible for systemic treatment * Failure, intolerance or contraindication to available systemic treatments (i.e. cyclosporine/methotrexate) Exclusion Criteria: * Pregnancy or breast-feeding women, or planning to become pregnant or breastfeed during the study * Women unwilling to use adequate birth control, if of reproductive potential and sexually active. * Subject currently experiencing or having a history of other concomitant skin conditions that would interfere with evaluation of AD * History of allergic reaction to local anesthetic product * History of wound healing disorders (e.g. hypertrophic scars, keloids) * Subject with known active infection to HBV, HCV or HIV * Subject with known helminth infection * Subject with known blood dyscrasia * Subject having an allergen immunotherapy within 3 months before study * Subject treated by antihistamine 5 days before study. Please note, antihistamine administered to treat allergic rhino conjunctivitis is allowed after V1. * Subject treated with an investigational drug within 8 weeks or within 5 half-life (if known), whichever is longer, before the baseline visit * Subject treated with cyclosporine, methotrexate oral corticosteroids, azathioprine, mycophenolate mofetil, and/or any other systemic immunosuppressor/immunomodulator within 4 weeks before the study * Subject treated by a biologic therapy within 5 half-life before the study * Subject treated with ultraviolet therapy within 4 weeks before study * Subject treated with a live (attenuated) vaccine within 12 weeks before baseline visit * Subject having a planned surgery during the study * Subject presenting clinically significant medical disease that is uncontrolled despite treatment that is likely, in the opinion of the investigator, to impact patient's ability to participate in the study or to impact the study efficacy or safety assessments * Subject with any additional condition that, in the opinion of the investigator, may interfere with the assessment or put the subject at risk * Linguistic or mentally incapacity to sign the consent form * Subject protect by the law (adult under guardianship, or hospitalized in a public or private institution for a reason other than study, or incarcerated) * Subject in an exclusion period from a previous study or who is participating in another clinical trial