villous atrophy
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The gut's carpet worn down to bare floor — the central structural damage of celiac disease.
The small intestine's inner lining is covered in thousands of tiny finger-like projections called villi. They exist to maximize surface area for absorbing nutrients — a healthy gut has the absorptive area of a tennis court, largely because of villi. In celiac disease, the sustained immune attack flattens and eventually destroys them. This is villous atrophy.
What Causes It
The inflammatory cascade — driven by cd4-t-cells responding to gliadin presented on hla-dq2-dq8 molecules — releases cytokines-celiac that damage the epithelial lining. il-15 may also drive damage via the innate immune arm independently of T cells. As villi shrink, the body attempts to compensate by enlarging the crypts of Lieberkühn, the glands that produce replacement cells — but replacement can't keep pace with destruction.
Grading
Villous atrophy is graded on the marsh-classification scale:
- Marsh 3a — mild atrophy
- Marsh 3b — moderate atrophy
- Marsh 3c — complete atrophy (flat mucosa)
The Marsh scale also captures earlier-stage damage (elevated intraepithelial-lymphocytes only, or crypt hyperplasia without atrophy yet).
Consequences
Villous atrophy is the direct structural cause of malabsorption. With less absorptive surface, the gut fails to extract iron, calcium, folate, zinc, vitamin D, and B12 from food — driving the cascade of systemic symptoms described in symptoms.
Reversibility
Villous atrophy is reversible on a strict gluten-free-diet. Mucosal healing typically takes months to years — slower in adults than children. Persistent atrophy despite GFD adherence is the defining feature of refractory-celiac.
Related Concepts
villi | malabsorption | crypt-hyperplasia | intraepithelial-lymphocytes | marsh-classification | tissue-transglutaminase | refractory-celiac