2019 Dermatol Res
VitroScreen Srl, Milan, Italy - Unired Srl, Padova, Italy - Unifarco SpA, Santa Giustina BL, Italy - Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy

Hard Water and Cleansers An In-Vitro Study of the Effects on Immature Reconstructed Human Epidermis

Background: Barrier function impairment resulting from increased exposure to daily use of surfactants in the presence of hard water (HW) has been identified as a relevant factor to the development of atopic dermatitis (AD), especially in infants.

Objectives: To investigate the effect of HW as such or in the presence of surfactants on skin barrier development as it occurs during infancy, using a 3D reconstructed immature (not fully differentiated) human epidermis model.

Materials and Methods: Reconstructed Human Epidermis (RHE) starting at the 13th day of differentiation was exposed to HW alone or in the presence of surfactants (Sodium Dodecyl Sulphate and a commercial cleansing oil) for 2 days (two topical exposure per day) followed by two days of recovery. The barrier structure and functional modifications have been assessed by evaluating epidermal morphology (H&E), tight junctions barrier functionality (TEER measure), proteins’ expression of claudin-1, filaggrin and involucrin by immunohistochemistry, inflammation by transcriptional activity of TNF-α and RHE ultrastructure (TEM analysis).

Results: HW itself has modified the differentiation process without influencing the barrier function structure (Claudin 1 was not significantly affected) but in presence of SDS, HW has induced inflammation, morphological modification in particular cell swelling and SC lamellar structure damages leading to a severe modification to the barrier structure in the final epidermal differentiation. The effects of the hard water are reduced in the presence of a mild cleansing oil including emollients.

Conclusion: The results obtained using the in-vitro RHE model are in agreement with the clinical observations
reported in the literature regarding the detrimental effect of the hard water on the skin of infants. Moreover, the invitro model can be a useful tool to evaluate the effects of both surfactant and cleansing formulation on impaired skin.