Atopic dermatitis (AD) is an inflammatory pruritic chronic skin disease, notably involving the cytokine Thymic Stromal Lymphopoietin (TSLP) directly implicated in the AD-pruritus and in the impaired quality of life. We aim to characterize the efficacy of a combination of 18β-glycyrrhetinic acid (GA) and polyphenols from a Tambourissa trichophylla extract (TE) on in vitro TSLP production by Normal Human Epidermal Keratinocytes (NHEK) and the efficacy of a topical spray containing these two actives ingredients in vivo. Quantification of TSLP secretion by NHEK cultured in medium without hydrocortisone were performed. NHEK were stimulated 24 hours by inflammatory factors: Poly:IC, TNF-α and IL-4. Dexamethasone was used as a positive control of inhibition. The clinical study was performed on 48 AD infants aged between 4 months and 4 years affected by itching. The product was applied for 21 days as often as necessary on the affected zones. The SCORing Atopic Dermatitis (SCORAD) index, the Infant’s Dermatitis Quality of life index (IDQOL) and the Dermatitis Family Impact Questionnaire (DFIQ) were assessed on the inclusion day (D0) and during the final visit (D21). TSLP overexpression by NHEK was inhibited in inflammatory conditions by GA and TE alone from 73.3% (p<0.001) to 20.7 (p<0.05) and from 57.2% to 27.9% (p<0.001) respectively according to tested doses and in association up to 81.6%, (p<0.001). Maximum of dexamethasone inhibition was 67.4%. Regarding the clinical study, the topical spray induces a 51% reduction of the SCORAD (p<0.01), including a 51% reduction of the pruritus index (p<0.01) and a 53% reduction of the sleeplessness index (p<0.01). The IDQOL and the DFIQ score were reduced by 33% and 37% respectively (p<0.01). Thus the topical spray, targeting the overexpression of TSLP, effectively decreases the AD pruritus and improves the quality of life of AD infants.

Efficacy of a novel complex of active ingredients on Thymic Stromal Lymphopoietin production and on the improvement of pruritus and daily life of infants with atopic dermatitis