Atopic dermatitis and the atopic march revisited.

Area of Science:

• Immunology
• Dermatology
• Allergology

Background:

• Atopic dermatitis (AD) prevalence is rising, often preceding other allergic diseases in a phenomenon known as the atopic march.
• The causal link between AD and subsequent allergies is debated, with confounding factors like genetics and early wheeze proposed.
• Longitudinal studies increasingly support an independent association between AD and other allergies, challenging confounding hypotheses.

Purpose of the Study:

• To review the evidence for and against a causal relationship in the atopic march.
• To explore potential biological mechanisms driving the atopic march.
• To highlight the need for prevention trials and identify environmental modifiers.

Main Methods:

• Review of longitudinal studies and human/animal research on AD and allergic diseases.
• Analysis of hypotheses regarding biological mechanisms, including skin barrier dysfunction and inflammatory mediators.
• Discussion of the role of prevention trials and environmental factors.

Main Results:

• Evidence suggests the association between AD and other allergies is independent of confounding factors.
• Defective skin barrier function and specific inflammatory mediators (e.g., thymic stromal lymphopoietin) are plausible biological mechanisms.
• Prevention trials are crucial for confirming causality, and environmental modifiers are an emerging research area.

Conclusions:

• The atopic march, the progression from AD to other allergies, shows increasing evidence of a causal link.
• Understanding biological mechanisms and environmental influences is key to developing secondary prevention strategies.
• The atopic march remains a critical area for research to reduce the global burden of allergic conditions.