摘要
Background: Autoimmune gastritis (AIG) is the basis of gastric cancer (GC). Loss of parietal cells (PCs) causes the development of spasmolytic polypeptide-expressing metaplasia (SPEM), which is considered as important precancerous lesion. Previously, we demonstrated that parietal cell-selective Slc26a9 deficiency caused spontaneous SPEM to GC in mice (Liu et al., Cellular oncology; 2022; Liu et al., DDW2023,2024). The present study was undertaken to study a potential role of Slc26a9 downregulation in the development of AIG and how to progress to SPEM.
Methods: Slc26a9fl/fl mice were crossed with H+-K+-Atp4b-Cre to produce the PCs-specific Slc26a9 knockout in Slc26a9fl/fl/Atp4b-Cre mice in a mixed genomic background. Electron microscope, flow cytometry analysis, histopathological and immunohistochemical (IHC) analysis with specific markers were performed in Slc26a9fl/fl and Slc26a9fl/fl/Atp4b-Cre mice.
Results:
1.Compared with Slc26a9fl/fl mice, Slc26a9fl/fl/Atp4b-Cre mice exhibited strongly loss of parietal cells, oxyntic atrophy followed with lymphocyte infiltration, the mitochondria of PCs were significantly swollen, the cell membrane structure was blurred and damaged, and the cristae were broken and disappeared which was observed by electron microscope.
2.Furthermore, Slc26a9 deletion showed an accumulation of multiple pyroptosis factors, including of NRLP3, Caspase-1, ASC, Gasdermin D, IL-1βand IL-18, and activated Gasdermin D binded to mitochondrial cardiolipin and led to the release of mitochondrial mediators, including ACO2, Cyto C, indicating that mitochondrial damage related pyroptosis of PCs.
3.Moreover, Flow cytometry analysis showed that CD4 T+ cells that infiltrated the Slc26a9fl/fl/Atp4b-Cre stomach expressed the TCR (TCRVα2/TCRVβ2) specific for the H+/K+-ATPase peptide, followed with upregulation of CD4+ T mediated cytokines, including IFN-γ, IL-2, IL-11 and IL-17. Taken together, PCs selective Slc26a9 deletion in mice caused Gasdermin D mediates mitochondrial damage induced PCs initial loss, resulted in the development of AIG.
4.Furthermore, Slc26a9fl/fl/Atp4b-Cre mice showed that hypergastrinemia induced Tuft cell migration and mediated IL-25 release, followed with upregulation of ILC2 cell marker GATA3 and M2 macrophage polarized markers F4/80+ and CD163+ in the base of gastric mucosal of Slc26a9 fl/fl /Atp4b-Cre mice, indicating that PCs selective Slc26a9 deletion in mice caused PCs pyroptosis and followed with gastric regional immunity remodeling, resulted in the development of SPEM based on AIG.
Conclusions: PCs-selective Slc26a9 deletion in mice caused Gasdermin D mediates mitochondrial damage induced PC cells initial loss, and followed with activation of IL-25-ILC2- M2 macrophage axis, which is the key event to induce spontaneous AIG and progress to SPEM.
