Neonates with the highest transepidermal water loss at birth, likely mediated through an impaired epidermal barrier, show significantly elevated chymotrypsinlike protease activity and reduced levels of filaggrin-derived natural moisturizing factors, which may predispose them to the development of atopic dermatitis, according to a report published online in the British Journal of Dermatology.

John Chittock of the University of Sheffield, England, and his colleagues assessed the biophysical, biologic, and functional properties of the developing neonatal stratum corneum (SC) from birth to 4 weeks of age in 115 healthy, full-term (at least 37 weeks’ gestation) neonates from the OBSERVE (Oil in Baby Skincare) randomized study birth cohort recruited at Saint Mary’s Hospital, Central Manchester NHS Foundation Trust, between September 2013 and June 2014.

For comparative purposes, an unrelated cohort of 20 adults with healthy skin was recruited from the local community between January and April 2015 ( Br J Dermatol. 2016 Mar 19. doi: 10.1111/bjd.14568 ).

The researchers found that the biophysical properties of the neonatal SC are transitional from birth. For example, overall transepidermal water loss (TEWL) increased significantly during the first 4 weeks of infant life. Compared with adult skin, the newborn infant SC was found to be drier and more alkaline. In addition, levels of superficial chymotrypsinlike protease activity at birth did not differ between newborns and adults, while levels of filaggrin-derived natural moisturizing factors (NMF) were significantly lower at birth than in adulthood.

The increased chymotrypsinlike protease activity and NMF at 4 weeks of age exceeded levels found in healthy adults, rather than reaching their mature state. Compared with adult skin, the skin of infants is functionally immature, with undeveloped mechanisms of desquamation and differentiation, the investigators noted.

Further analysis revealed a correlation between TEWL and both superficial chymotrypsinlike protease activity and filaggrin-derived NMF at birth.

To explore that link, the researchers stratified the neonatal cohort according to TEWL percentile. The neonates in the 76th-100th percentile, the highest TEWL at birth, showed significantly elevated chymotrypsinlike protease activity and reduced levels of filaggrin-derived NMF, compared with neonates in lower percentiles. Therefore, those neonates are at highest risk for developing atopic dermatitis, the study authors said.

The findings indicate a need for infant skin care regimens that protect and support normal barrier development from birth, the researchers noted. They also suggested that clinical strategies targeting the early mechanisms of barrier breakdown could act as preventive measures in neonates at increased risk of developing atopic dermatitis.

The research was funded jointly by the University of Sheffield and a doctoral research fellowship supported by the National Institute for Health Research. The authors declared no conflicts of interest.