The effect of season of birth on atopic dermatitis and food allergy

Maternal Allergic Disease Phenotype and Infant Birth Season Influence the Human Milk Microbiome

Early infancy is a critical period for immune development. In addition to being the primary food source during early infancy, human milk also provides multiple bioactive components that shape the infant gut microbiome and immune system and provides a constant source of exposure to maternal microbiota. Given the potential interplay between allergic diseases and the human microbiome, this study aimed to characterise the milk microbiome of allergic mothers. Full-length 16S rRNA gene sequencing was performed on milk samples collected at 3 and 6 months postpartum from 196 women with allergic disease. Multivariate linear mixed models were constructed to identify the maternal, infant, and environmental determinants of the milk microbiome. Human milk microbiome composition and beta diversity varied over time (PERMANOVA R2 = 0.011, p = 0.011). The season of infant birth emerged as the strongest determinant of the microbiome community structure (PERMANOVA R2 = 0.014, p = 0.011) with impacts on five of the most abundant taxa. The milk microbiome also varied according to the type of maternal allergic disease (allergic rhinitis, asthma, atopic dermatitis, and food allergy). Additionally, infant formula exposure reduced the relative abundance of several typical oral taxa in milk. In conclusion, the milk microbiome of allergic mothers was strongly shaped by the season of infant birth, maternal allergic disease phenotype, and infant feeding mode. Maternal allergic disease history and infant season of birth should therefore be considered in future studies of infant and maternal microbiota. Trial Registration: ClinicalTrials.gov identifier: ACTRN12606000281594.

Detecting common allergens in dogs with atopic dermatitis in South Korean Provinces using a serological immunoglobulin E-specific allergen test

Background and Aim:

Canine atopic dermatitis (CAD) is a hereditary susceptibility to the development of allergic symptoms in response to repeated exposure to generally innocuous substances known as “allergens.” Allergens can be plants, animals, mold, mites, or milk. At present, serological enzyme-linked immunoassay (ELISA) kits are used for immunoglobulin E (IgE)-specific allergen detection due to their simplicity and accuracy. This study aimed to detect allergens in dogs with CAD and determine how they differ according to season, breed, age, and sex using a serological test in six provinces in South Korea for 12 months. This will allow practitioners to easily understand the risk factors related to CAD.

Materials and Methods:

In this study, IgE allergen-specific ELISA kits were used. The allergens were detected in serum samples collected from different regions considering season, sex, breed, and age. Allergens were divided into the following Ten categories: 1. Dairy, yeast, and egg, 2. grains, 3. vegetables, 4. meat, 5. seafood, 6. animals, 7. mold, 8. insects, 9. mites, and 10. trees.

Results:

The percentage of allergens detected in males (54.8%) was higher than that of females (45.2%); 54.2% of allergens occurred in 3-year-old dogs or older. Moreover, regarding frequency, 65.6% of overall allergens occur during autumn; Chungcheongnam-do and Jeollabuk-do showed 20.7% and 20.9%, respectively. Additionally, among allergens categories, notable allergen occurrence was as follows: 38.3% corn; 28.7% potatoes; 22.7% duck; 24.4%,codfish; 31.2% animal wool; 95.6% Aspergillus fumigatus; 31.9% flea; 41.8% oak; and 25.0% sheep’s sorrel grass.

Conclusion:

This study showcases the frequency of 60 allergens in six provinces detected in dogs with CAD; most likely from food or the environment using serological ELISA kits. Environmental sensitizer results can be considered for humans suffering from allergies to avoid a similar environment. A large-scale study can be performed to evaluate the allergens in the state. However, neither a skin test nor feed analysis was conducted, which is a limitation of this study.

Transient Receptor Potential Vanilloid 1 Plays a Major Role in Low Temperature-Mediated Skin Barrier Dysfunction

BACKGROUND

Children born in the fall and winter are at increased risk for developing atopic dermatitis (AD) and food allergy (FA). Since these seasons are associated with low temperature, we hypothesized that low temperature exposure may compromise keratinocyte differentiation and contribute to skin barrier dysfunction.

OBJECTIVE

To examine whether low temperature causes skin barrier dysfunction.

METHODS

Primary human epidermal keratinocytes (HEKs) were differentiated in 1.3mM CaCl₂ media and cultured at different temperatures. The cells were transfected with transient receptor potential cation channel subfamily V member 1 (TRPV1) or signal transducer and activator of transcription (STAT) 3 small-interfering RNA (siRNA) to examine the effects of these gene targets in HEKs exposed to low temperature. Gene expression of TRPV1, epidermal barrier proteins, and keratinocyte-derived cytokines were evaluated. Organotypic skin equivalents were generated using HEKs transfected with control or TRPV1 siRNA and grown at 25^oC or 37^oC. Transepidermal water loss (TEWL) and levels of epidermal barrier proteins were evaluated.

RESULTS

Filaggrin (FLG) and loricrin (LOR) expression, but not keratin (KRT)-1 and KRT-10 expression, was downregulated in HEKs incubated at 25^oC while TRPV1 silencing increased intracellular Ca²⁺ influx (keratinocyte differentiation signal) and enhanced the expression of epidermal differentiation proteins. Interleukin (IL)-1β and thymic stromal lymphopoietin (TSLP) induced by low temperature inhibited FLG expression in keratinocytes through the TRPV1/STAT3 pathway. Moreover, low temperature-mediated inhibition of FLG and LOR was recovered, and TEWL was decreased in organotypic skin transfected with TRPV1 siRNA.

CONCLUSION

TRPV1 is critical in low temperature-mediated skin barrier dysfunction. Low temperature exposure induced TSLP, an alarmin implicated in epicutaneous allergen sensitization.

CLINICAL IMPLICATIONS

Low temperature causes skin barrier dysfunction through TRPV1 and TSLP, which may explain the pathways involved in promoting allergic sensitization through the skin.

Origin of Allergy From In Utero Exposures to the Postnatal Environment

As the incidence of atopic conditions continues to increase, emphasis has been placed on understanding the origin of allergy with hope that prevention measures can be achieved. The perinatal environment is important for this understanding, given that both the immune system and microbiome start forming prenatally. Maternal exposure can greatly impact on fetal health. Additionally, the dysfunctional epithelial barrier is influential in allowing allergens and irritants to penetrate the skin or mucosa, leading to the release of proinflammatory cytokines and mediators to drive type 2 tissue inflammation and the onset of allergy. There are numerous factors related to skin, airway, and gut epithelial barriers dysfunction, and genetic predispositions are also present. Comprehensive birth cohort studies and further mechanistic studies will be keys to understanding the origin of allergy.

Influence of climate factors on pediatric alopecia areata flares in Philadelphia, Pennsylvania

Patients with alopecia areata (AA) may experience episodic disease flares characterized by increasing hair loss that follow a seasonal pattern. However, no studies have examined whether specific climate factors contribute to the seasonal pattern of AA flares. Using Spearman rank correlation analyses, we assessed the association between climate variables and AA flare frequency per month in 336 children with AA in Philadelphia, Pennsylvania. Region-specific monthly values for average ambient temperature, air pressure, cloudiness, hours of sunlight, relative humidity, number of days with sun, number of days with rain, volume of precipitation, wind gust, wind speed, and UV index from January 2015 to December 2017 were obtained from World Weather Online. We found significant (P < 0.05) correlations between AA flare frequency and UV index (R = − 0.66), precipitation (R = − 0.66), number of days with rain (R = − 0.70), number of days with sun (R = 0.62), and air pressure (R = 0.80). Stratified analyses showed even stronger associations with UV index and precipitation in patients with an atopic comorbidity. New significant correlations appeared with temperature, wind speed, and UV index of the prior month. However, in patients who did not have atopic comorbidities, we generally observed weaker and non-significant correlations between climate and AA flare frequency. This study suggests that certain climate factors may mediate the seasonal pattern of AA flares and may contribute to AA pathogenesis. Atopic AA patients may be more susceptible to the influence of climate compared to those with no history of atopy.

Effects of an emollient application on newborn skin from birth for prevention of atopic dermatitis: a randomized controlled study in Thai neonates

BACKGROUND

Enhancing the skin barrier in high-risk neonates by daily use of emollients during infancy might prevent atopic dermatitis (AD); however, there have been no studies on this topic in a country with a tropical climate. Climate may affect the results of the use of emollients in neonates for AD prevention and possible adverse cutaneous eruptions.

OBJECTIVES

To test the hypothesis that emollients used during infancy can prevent AD in high-risk neonates in a country with a tropical climate and to evaluate other possible adverse cutaneous eruptions in this population.

METHODS

This was a randomized controlled study in a tertiary care hospital with a 6 months' duration. Eligible neonates were randomly assigned to receive either emollient and skincare advice (emollient group) or skincare advice only (control group). The intervention was started within 3 weeks of birth.

RESULTS

The emollient group showed a significant reduction in the cumulative incidence of AD at 6 months (relative risk, 0.39; 95% CI 0.24-0.64; P < 0.001). The emollient group started to develop AD later and had a lower severity of AD than the control group (P < 0.001). Compared to moderate adherence, low adherence to emollient application was associated with a lower number of patients with AD (P = 0.008). Potentially emollient-related cutaneous eruptions, such as miliaria, and suspected cutaneous infections, such as impetigo, were more frequent in the emollient group. Exposure to passive smoking showed a significant difference in the development of AD compared to non-smoking exposure, both during pregnancy and after the child's birth (P < 0.001).

CONCLUSIONS

This study suggests that, in a tropical climate, emollient applied to the skin of at-risk neonates on an 'as needed' basis (depending on environmental factors, level of skin dryness), rather than on a 'daily basis', can provide a substantial benefit for AD prevention.