Eczema Pathophysiology: Inflammation and Skin Barrier Dysfunction

Atopic dermatitis (eczema) is driven by two intertwined defects:

1. Skin barrier dysfunction: Filaggrin mutations, reduced ceramides, elevated pH → increased transepidermal water loss, allergen/irritant penetration.
2. Immune dysregulation: Th2/Th22/Th17 skewing → IL-4, IL-13, IL-31, IL-22 → inflammation, pruritus, further barrier damage.

This creates a vicious cycle: barrier breach → immune activation → inflammation → more barrier damage. Therapy targets both: emollients restore barrier; topical/systemic immunomodulators suppress inflammation.