Localization of epidermal growth factor/transforming growth factor-α receptor in the human gastric mucosa

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Abstract
Current evidence indicates that epidermal growth factor (EGF) and transforming growth factor-α (TGF-α) play a pivotal role in the maintenance of gastric mucosal integrity, via binding to a common cell-surface receptor (EGF/TGF-α receptor). We examined the distribution and cellular sites of synthesis of EGF/TGF-α receptor in normal human gastric mucosa by immunohistochemical and in situ hybridization techniques. Intense EGF/TGF-α receptor immunoreactivity was observed in the basal cytoplasm and along basolateral membranes of mucus neck cells, foveolar columnar cells, and surface epithelial cells facing the gastric lumen. Parietal cells and mucus-secreting pyloric gland cells displayed a distinct basolateral immunostaining, whereas the luminal membrane was unstained. Immunoreactivity was also noted in spindle-shaped cells of the lamina propria and in smooth muscle cells of the muscularis mucosae and muscularis propria. In situ hybridization revealed EGF/TGF-α receptor RNA transcripts in all cell types displaying positive immunoreaction. These results suggest a physiological role for EFG/TGF-α in the regulation of multiple gastric functions. The receptor distribution at the luminal aspect of the gastric mucosa provides the anatomical basis for a possible interaction of gastric juice EGF (or TGF-α) with cells of the mucosal surface, whereas the expression of EGF/TFG-α receptor in cells which are not in direct contact with the gastric lumen is consistent with blood-mediated or paracrine/ autocrine mechanisms of EGF/TGF-α action on these cells.