Trajectory of stratum corneum lipid subclasses in the first year of life and associations with atopic dermatitis: A prospective cohort study.

BACKGROUND: Trajectories of stratum corneum (SC) lipid subclasses and their associations with infant atopic dermatitis (AD) are unclear. This study aimed to quantify the trajectories of 15 SC subclasses and carbon chain lengths and their associations with AD within 12 months. METHODS: In total, 213 newborns were enrolled at birth with nonlesional skin samples collected from the inner forearm at birth, 42 days, 3, 6, and 12 months, respectively. Lesional skin samples were collected from 120 AD patients at clinic with the disease onset within the first year of life. Mass spectrometry was applied to assess relative contents of 12 ceramide (CER), three free fatty acid (FFA) subclasses, and average carbon chain length (CCL). AD incident within 1 year old was diagnosed by dermatologists according to UK criteria. RESULTS: Sixty-four (30.0%) cases of ADs occurred in the cohort. All SC lipid subclasses and CCLs, but EOP varied significantly during the first year. AD infants showed lower NP but higher NS, NH, AP, hydroxy FFA, and CCL of FFAs compared with nonaffected infants. After normalization by age, the differences remained and were more pronounced in lesional skin of clinical AD infants compared with non-ADs. NS, NH, and CCL of FFAs in lesional skin of AD infants showed positive and significant correlations with the levels of transepidermal water loss at 3 month; some evidence supports a negative correlation for NP. CONCLUSIONS: We provide an overview of developmental trajectories of 15 CER and FFA subclasses across the first year of healthy infants and a link between the imbalance of some subclasses with the development of AD.

Dynamic trends in skin barrier function from birth to age 6 months and infantile atopic dermatitis: A Chinese prospective cohort study.

BACKGROUND: Skin barrier functions develop after birth and may be related to skin disorders in infants. We aimed to assess associations between dynamic trends of four skin barrier functional parameters in early life with infant atopic dermatitis (AD). METHODS: Based on the prospective cohort MKNFOAD (NCT02889081), we examined transepidermal water loss (TEWL), stratum corneum hydration (SCH), skin pH, and sebum content at five anatomical sites (cheek, forehead, forearm, abdomen, and lower leg) in 418 term infants at birth, 42 days, and 6 months. Trend differences by sex and association with AD at age 1 year were tested using variance analyses. Associations of the parameters with AD risk were tested using discrete time survival analysis, adjusting extensive covariates including parental history of allergy, infant's sex, birth weight (kg), and delivery mode. Odds ratios (ORs) and 95% confidence interval (CIs) were reported. RESULTS: Overall TEWL and SCH appeared trends of increase while skin surface pH and sebum content showed trends of decrease within the first six postnatal months. Sex differences were significant for sebum content only (p < 0.001). After adjustment for parental and children covariates, cheek TEWL at birth (OR = 1.26, 95% CI 1.00-1.57, p = 0.045) and 42 days (OR = 1.52, 95% CI 1.17-1.97, p = 0.002) were significantly associated with increased AD risk. Associations were not observed between SCH, skin pH, and sebum content at birth or 42 days with AD. CONCLUSIONS: Skin barrier functions of Chinese term infants varied nonlinearly after birth. Higher postnatal TEWL levels in early life indicate higher risk of early-onset AD.

A Novel Effect of Lipids Extracted from Vernix Caseosa on Regulation of Filaggrin Expression in Human Epidermal Keratinocytes

BACKGROUND: Vernix caseosa (VC), which is known as a unique human substance, is a biofilm that covers the skin of most human newborns. VC has many biological functions including anti-infective, skin cleansing and skin barrier repair. OBJECTIVE: In the study, we purpose to investigate the novel effect of lipids extracted from VC on the regulation of filaggrin (FLG) expression and anti-inflammation in normal human epidermal keratinocyte (NHEK) cells. METHODS: The lipids were extracted by chloroform/methanol (Folch method) and the major properties of fatty acid methyl esters were determined with gas chromatography-mass spectrometer. The relative viability of NHEK cells was evaluated by Cell Counting Kit 8 assay. The related expression of skin barrier protein was accessed with real-time quantitative polymerase chain reaction, Western blot and Immunofluorescence in NHEK cells with or without poly (I:C). Meanwhile, the changes of thymic stromal lymphopoietin (TSLP) and tumor necrosis factor alpha (TNF-α) are analyzed by enzyme-linked immunosorbent assay. RESULTS: VC lipids mostly contained saturated and branched chains fatty acids. The expression of mRNA and protein of FLG were significantly increased after the supplement with lipid in NHEK cells. Meanwhile, lipids reversed the inhibition of poly (I:C) on FLG. Moreover, lipids suppressed the over secretion of TSLP and TNF-α induced by poly (I:C). CONCLUSION: These results indicate that lipids extracted from VC has positive effects on the expression of FLG and anti-inflammation, suggesting that lipids of VC may be used for a reference for novel therapeutic method in reducing and remedying skin disease like atopic disease.