Effectiveness of a standardized skin care regimen to prevent atopic dermatitis in infants at risk for atopy: a randomized, pragmatic, parallel-group study.

BACKGROUND: It has been proposed that regular emollient application in early life could enhance skin barrier function and prevent atopic dermatitis (AD) especially in predisposed infants. This hypothesis was supported by evidence from exploratory and pilot trials showing protective effects in terms of reduced cumulative atopic dermatitis incidence with the use of daily emollient therapy starting immediately after birth. OBJECTIVES: To investigate the effectiveness of a standardized skin care regimen for infants on the development of AD compared to not structured skin care regimen in infants with atopic predisposition. METHODS: Prospective, parallel group, randomized, pragmatic, investigator-blinded intervention trial including 160 infants with 52 weeks intervention and 52 weeks follow up phase up to the age of two years. Infants were randomly assigned to receive a standardized skin care regimen including once daily leave-on product application (lipid content 21%) or skin care as preferred by the parents. RESULTS: Using the intention to treat approach, the cumulative AD incidence was 10.6% after one year, and 19.5% after two years in the total sample. There were no statistical significant differences between intervention and control groups. Skin barrier parameters between the intervention and control groups were comparable. AD severity was higher and quality of life was more affected in the control group. CONCLUSIONS: Regular emollient application during the first year of life does not prevent the development of atopic dermatitis. A standardized skin care regimen does not delay skin barrier development or causes side effects.

A molecular rheostat adjusts auxin flux to promote root protophloem differentiation.

Auxin influences plant development through several distinct concentration-dependent effects 1 . In the Arabidopsis root tip, polar auxin transport by PIN-FORMED (PIN) proteins creates a local auxin accumulation that is required for the maintenance of the stem-cell niche2-4. Proximally, stem-cell daughter cells divide repeatedly before they eventually differentiate. This developmental gradient is accompanied by a gradual decrease in auxin levels as cells divide, and subsequently by a gradual increase as the cells differentiate5,6. However, the timing of differentiation is not uniform across cell files. For instance, developing protophloem sieve elements (PPSEs) differentiate as neighbouring cells still divide. Here we show that PPSE differentiation involves local steepening of the post-meristematic auxin gradient. BREVIS RADIX (BRX) and PROTEIN KINASE ASSOCIATED WITH BRX (PAX) are interacting plasma-membrane-associated, polarly localized proteins that co-localize with PIN proteins at the rootward end of developing PPSEs. Both brx and pax mutants display impaired PPSE differentiation. Similar to other AGC-family kinases, PAX activates PIN-mediated auxin efflux, whereas BRX strongly dampens this stimulation. Efficient BRX plasma-membrane localization depends on PAX, but auxin negatively regulates BRX plasma-membrane association and promotes PAX activity. Thus, our data support a model in which BRX and PAX are elements of a molecular rheostat that modulates auxin flux through developing PPSEs, thereby timing PPSE differentiation.