Study protocol to investigate the environmental and genetic aetiology of atopic dermatitis: the Indonesian Prospective Study of Atopic Dermatitis in Infants (ISADI)

Novel Interactions of Myristic Acid and FADS3 Variants Predict Atopic Dermatitis among Indonesian Infants

Fatty acids exert a range of different biological activities that could be relevant in the development of atopic dermatitis (AD). This study investigated the association of glycerophospholipid fatty acids (GPL-FA) with AD, and their interactions with single nucleotide polymorphisms (SNP) of the FADS1-3 gene cluster. Among 390 infants of the Indonesian ISADI study, GPL-FA were measured in umbilical plasma (P-0y) and in buccal cells at birth (B-0y), and again in buccal cells at AD onset or one year (B-1y). Prospective and cross-sectional associations with AD were assessed by logistic regression. Interactions of GPL-FA with 14 SNP were tested assuming an additive model. AD was diagnosed in 15.4% of participants. In B-1y, C18:2n-6 was inversely associated with AD; and positive associations were observed for C18:1n-9, C20:4n-6, C22:6n-3 and C20:4n-6/C18:2n-6. There were no prospective associations with AD, however, a significant interaction between the SNP rs174449 and B-0y C14:0 (myristic acid) was observed. This study indicates that Indonesian infants with AD have increased rates of endogenous long-chain polyunsaturated fatty acid production, as well as higher C18:1n-9 levels. GPL-FA measured at birth do not predict later AD incidence; however, genotype interactions reveal novel effects of myristic acid, which are modified by a FADS3 variant.

Vitamin D, cytokine profiles, and disease severity in infants with atopic dermatitis: a single centre, cross-sectional study

Introduction

Atopic dermatitis (AD) is an immune-mediated inflammatory skin disease and generally develops in infancy. Studies evaluating the role of vitamin D in immune mechanims in AD showed varying results.

Aim

To assess the association between serum vitamin D, cytokine profiles, and disease severity in infants with AD.

Material and methods

A cross-sectional study was conducted on infants aged 0–12 months with AD in the Paediatric Allergy and Immunology Department, Saiful Anwar Hospital, Indonesia. The disease severity was assessed by the Scoring of Atopic Dermatitis (SCORAD) index. Blood was drawn to evaluate the total eosinophil count (TEC), total immunoglobulin E (tIgE), 25-hydroxyvitamin D (25(OH)D), interleukin-4 (IL-4), IL-17A, and IL-22 levels.

Results

This study enrolled 36 infants including 19 with mild AD and 17 with moderate AD. Vitamin D deficiency and insufficiency were found in 18 (50%) and 9 (25%) subjects, respectively. The mean 25(OH)D level was lower and the mean IL-4, IL-17A, and IL-22 levels were higher in the moderate AD group than in the mild AD group (p < 0.05). A lower level of 25(OH)D was associated with a higher level of IL-17A (r = –0.315, p = 0.041). The SCORAD index was negatively correlated with 25(OH)D (r = –0.714, p < 0.001) and positively correlated with IL-17A (r = 0.522, p = 0.001) and IL-22 (r = 0.612, p < 0.001) but not IL-4 (r = 0.325, p = 0.053).

Conclusions

There was a high prevalence of vitamin D deficiency and insufficiency in infants with AD, and a low vitamin D level was correlated with the severity of AD, dependently on IL-17A.

Early nutrition in combination with polymorphisms in fatty acid desaturase gene cluster modulate fatty acid composition of cheek cells' glycerophospholipids in school-age children

Variants in the human genes of fatty acid (FA) desaturase 1 (FADS1), 2 (FADS2) and 3 (FADS3) are associated with PUFA blood levels. We explored if maternal prenatal supplementation and children's genetic variation in seventeen SNP of the FADS1, FADS2 and FADS3 gene cluster influence twenty-one of the most relevant cheek cells' derived FA in glycerophospholipids (GPL-FA). The study was conducted in 147 Spanish and German mother-children pairs participating in the Nutraceuticals for a Healthier Life (NUHEAL) study at 8, 9 and 9·5 years. Linear and mixed model longitudinal regression analyses were performed. Maternal fish-oil (FO) or FO+5-methyltetrahydrofolate (5-MTHF) supplementation during pregnancy was associated with a significant decrease of arachidonic acid (AA) concentrations in cheek cell GPL in the offspring, from 8 to 9·5 years; furthermore, maternal FO+5-MTHF supplementation was associated with higher n-6 docosapentaenoic acid concentrations in their children at age 8 years. FADS1 rs174556 polymorphism and different FADS2 genotypes were associated with higher concentrations of linoleic and α-linolenic acids in children; moreover, some FADS2 genotypes determined lower AA concentrations in children's cheek cells. It is suggested an interaction between type of prenatal supplementation and the offspring genetic background driving GPL-FA levels at school age. Prenatal FO supplementation, and/or with 5-MTHF, seems to stimulate n-3 and n-6 FA desaturation in the offspring, increasing long-chain PUFA concentrations at school age, but depending on children's FADS1 and FADS2 genotypes. These findings suggest potential early nutrition programming of FA metabolic pathways, but interacting with children's FADS polymorphisms.

The association of fatty acid desaturase gene polymorphisms on long-chain polyunsaturated fatty acid composition in Indonesian infants

Background

Adequate availability of long-chain polyunsaturated fatty acids (LC-PUFAs) is important for human health from pregnancy to adulthood. Previous studies on fatty acid desaturase (FADS) gene single-nucleotide polymorphisms (SNPs) have been performed predominantly in Western populations and showed that FADS SNPs had a marked impact on LC-PUFA composition in blood and tissues.

Objectives

We aimed to investigate the influence of fetal FADS genotypes on LC-PUFA composition in umbilical artery plasma lipids in Indonesian infants.

Design

We performed a cross-sectional study to assess for these associations.

Results

A total of 12 cord plasma n-6 (ω-6) and n-3 (ω-3) fatty acids were analyzed for associations with 18 FADS gene cluster SNPs from 390 women with single parturition from the Indonesian Prospective Study of Atopic Dermatitis in Infants (ISADI). Fetal FADS genotypes influenced cord plasma LC-PUFA composition, but, in contrast to previous studies from Western populations, the quantitatively predominant SNPs were associated with lower LC-PUFA content.

Conclusion

To our knowledge, this study was the first in South East Asia on FADS genotypes and arterial cord blood fatty acids to show an association between fetal LC-PUFA composition and fetal FADS SNPs. The FADS genotype distribution differs markedly between different geographical populations. This trial was registered at clinicaltrials.gov as NCT02401178.