Atopic eczema
A defective skin barrier, often driven by filaggrin deficiency, lets water escape and irritants and allergens penetrate, triggering a Th2 immune response, so treatment restores the barrier first and calms the inflammation second.
First principles
Eczema begins with a broken barrier, not an overactive immune system
The stratum corneum normally acts as a brick-and-mortar wall: keratinocytes (bricks) held together by lipids (mortar), with filaggrin breakdown products keeping the surface hydrated. Many people with atopic eczema carry loss-of-function filaggrin mutations, or simply have a thinner lipid barrier, so the wall is leaky. Water escapes outward (transepidermal water loss) and irritants, allergens and microbes get in. Everything else in eczema follows from this structural defect.
Educational content pending clinical review. Not medical advice.