Expression of retinoid receptors in multiple cell lineages in the gastric mucosae of mice and humans

Background and Aim: In mice and humans, the gastric epithelial progenitors undergo proliferation and bipolar migration from the isthmus associated with their differentiation into mucus-, acid- and pepsinogen-secreting cell lineages. Little is known about factors that control the dynamics of these isthmal progenitor cells. Retinoids have long been known as chemopreventive agents against gastric mucosal damage and carcinogenesis. The aim of the present study was to examine the cellular localization of the various retinoid receptors proteins (RAR and RXR) in the gastric epithelium of mice and humans. Methods: Gastric antral biopsies of normal individuals and the oxyntic and antral regions of the mouse stomach were processed for immunohistochemistry using anti-RAR and anti-RXR antibodies. To label the progenitor cell zone, some sections were also probed with antibodies specific for proliferating cell nuclear antigen. Results: The immunoprobed oxyntic mucosal sections of the mice showed that RXRβ protein was present in the epithelial isthmal cells, neck cells, zymogenic cells and some pit and parietal cells. In addition, RARβ was found in isthmal and neck cells, and RARγ was mainly found in neck cells. In the mouse antrum, only RXRβ was detected in the isthmal cells and their pit and gland cell descendents. In humans, immunoprobed antral sections showed that RARβ, RARγ, RXRα and RXRγ proteins are expressed in the isthmal, pit and gland cells. Conclusions: Retinoid receptors are expressed in multiple cell lineages of the mouse and human gastric epithelium and may, therefore, account for the possible effects of retinoids on gastric epithelial cell proliferation and differentiation.