Preclinical Atopic Dermatitis in Infants

Atopic dermatitis (AD) – a common chronic skin condition in children, which is often linked with other atopic disorders like asthma and allergic rhinitis. While AD is well-diagnosed with established criteria, the preclinical stage, where infants are at risk of developing AD, is less understood. Skin that appears normal in these infants often shows subtle changes that can indicate future AD. 

A recent study explored the structural, immunologic, and microbiome characteristics of the preclinical AD phase, aiming to identify markers that might predict AD development and guide preventive interventions.

AD typically emerges within the first year of life in 60% of cases and can precede other atopic conditions. The concept of the "atopic march" suggests that early skin barrier disruptions and antigen exposures increase the risk of developing atopic disorders. While barrier dysfunction is a known risk factor, it is not the sole contributor, as shared genetic and environmental factors also play important roles.

Research on preventative strategies––such as emollients use to enhance skin barrier function––has shown mixed results. Although initial studies suggested potential benefits, larger trials like BEEP and PreventADALL found no significant effect of emollients on AD prevention. In contrast, the STOP-AD study indicated some benefits from early emollient use.

Skin maturation involves complex changes, including the breakdown of filaggrin (FLG) and changes in lipid composition, which are crucial for barrier function. Variations in lipid profiles and free sphingoid bases have been linked to AD risk. Specific lipid biomarkers have shown potential in predicting AD development. Immune responses in AD skin reveal distinct patterns, with heightened Th2 and Th17 activity in infants compared to adults.

The skin microbiome also shifts prior to AD onset, with reductions in microbial diversity and increased prevalence of certain bacteria, such as Staphylococcus aureus. Studies suggest that early-life microbiome changes might contribute to AD risk. Additionally, changes in the gut microbiome have been linked to atopic conditions, though findings are still evolving.

In inference, understanding the preclinical phase of AD through biomarkers and microbiome profiles could enhance prevention strategies and reduce the severity of the condition.

Source: Paller AS, Scharschmidt TC, Kezic S, et al. Journal of Investigative Dermatology. 2024 Apr 3.