Celiac disease (CD) occurs frequently, and is caused by ingestion of
prolamins from cereals in subjects with a
genetic predisposition. The small intestinal damage depends on an intestinal stress/innate immune response to certain
gliadin peptides (e.g., A-gliadin P31-43) in association with an adaptive immune response to other
gliadin peptides (e.g., A-gliadin P57-68).
Gliadin and
peptide P31-43 affect epithelial
growth factor receptor (EGFR) signaling and CD enterocyte proliferation. The reason why the stress/innate immune and proliferative responses to certain
gliadin peptides are present in CD and not in control intestine is so far unknown. The aim of this work is to investigate if, in CD, a constitutive alteration of enterocyte proliferation and signaling exists that may represent a predisposing condition to the damaging effects of
gliadin. Immunofluorescence and immunohistochemistry were used to study signaling in CD fibroblasts and intestinal biopsies. Western blot (WB) analysis, immunoprecipitation, and quantitative PCR were also used. We found in CD enterocytes enhancement of both proliferation and
Epidermal Growth Factor Receptor (EGFR)/
ligand system. In CD enterocytes and fibroblasts we found increase of the phosphorylated downstream signaling molecule
Extracellular Signal Regulated Kinase (ERK); block of the ERK activation normalizes enterocytes proliferation in CD mucosa. In conclusion the same pathway, which
gliadin and
gliadin peptide P31-43 can interfere with, is constitutively altered in CD cells. This observation potentially explains the specificity of the damaging effects of certain
gliadin peptides on CD intestine.