Real-Time Infrared Spectroscopic Measurement of Natural Moisturizing Factor

Highly accurate, noninvasive early identification of infants with a filaggrin loss-of-function mutation by in vivo Raman spectroscopy, followed from birth to 12 months

BACKGROUND

Loss-of-function FLG mutation (FLGmut) carriers are at an increased risk of developing atopic dermatitis (AD), characterized by earlier onset and more severe disease. AD is driven by a complex interplay between skin barrier function, TH2 and TH2-dominant immune dysregulation, and dysbiosis. Results from the Short-Term Topical Application for Prevention of Atopic Dermatitis study suggest 2 early initiating AD pathogenetic pathways: an FLGmut-related skin barrier deficiency pathway and an immune function-related inflammatory pathway. The Short-Term Topical Application for Prevention of Atopic Dermatitis study suggested that early preventative intervention with specialized emollients for barrier function augmentation may benefit newborns with FLGmut. This requires early identification of FLGmut carriers, for which noninvasive Raman spectroscopic determination of natural moisturizing factor (NMF) levels in the stratum corneum of the thenar eminence provides a surrogate marker.

OBJECTIVE

To identify strategies for early identification of infants with FLGmut.

METHODS

FLG sequencing was performed on 253 infants, and NMF concentrations were measured in the stratum corneum of the palmar eminence (pSC-NMF) using noninvasive Raman spectroscopy at 6 time points after birth. Furthermore, the pSC-NMF concentrations were obtained from both parents of 150 infants.

RESULTS

Babies are born with little to no NMF. In the first days after birth, NMF levels rapidly increase and 65% of newborns with FLG wild type already reach pSC-NMF concentrations, which excludes them as FLGmut carriers with high specificity. At 2 weeks of age, FLGmut carriers could be distinguished from newborns with FLG wild type with high sensitivity (97%) and specificity (97%). In addition, parent pSC-NMF concentrations offer the possibility to exclude their newborn as FLGmut carriers with high specificity.

CONCLUSION

Noninvasive Raman spectroscopy enables the accurate early identification of infants with FLGmut.

Association between skin barrier development and early-onset atopic dermatitis: A longitudinal birth cohort study

BACKGROUND

A diagnosis of atopic dermatitis (AD) is common during infancy; however, it is unclear whether differential skin barrier development defines this period and signals disease onset in predisposed individuals.

OBJECTIVE

We sought to study (NCT03143504) and assess the feasibility of remote skin testing from birth to monitor skin barrier maturation and model association with an AD diagnosis by age 12 months.

METHODS

Biophysical testing and infrared spectroscopy were conducted at the maternity ward and family home. Tape stripping collected samples for desquamatory protease and natural moisturizing factor analysis. The 4 common European filaggrin risk alleles were screened.

RESULTS

A total of 128 infants completed the study, with 20% developing mild disease. Significant changes in permeability barrier function, desquamatory protease activity, and molecular composition assessed spectroscopically were observed longitudinally, but only subtle evidence of differential skin barrier development was noted between infant subgroups. Common filaggrin risk alleles were strongly associated with early-onset disease and conferred a significant reduction in natural moisturizing factor and water content by age 4 weeks. Accounting for a family history of atopy, these parameters alongside a greater lipid/protein ratio and reduced chymotrypsin-like activity at birth were associated with AD. Measured in ambient conditions, transepidermal water loss did not signal disease risk at any stage.

CONCLUSIONS

Skin barrier dysfunction lacked an acquired modality but was considered proportional to cohort severity and suggests that a portfolio of tests used in a community setting has the potential to improve current AD risk evaluations from birth.