Expression of claudin-1, -2, -3, -4, -5, -6, -7, -8, -10 and -18 in endoscopic gastric biopsy samples from dogs with lymphocytic gastritis

Lymphocytic gastritis is the most common type of chronic gastritis in dogs. The aim of the present study was to investigate the expression of claudin-1, -2, -3, -4, -5, -6, -7, -8, -10 and -18 in the fundic and pyloric gastric mucosa of dogs suffering from lymphocytic gastritis. In the case of mild, moderate and severe lymphocytic gastritis intense, linear, membranous claudin-18 positivity was detected in the surface gastric cells and in the epithelial cells of the gastric glands both in the fundic and pyloric stomach regions. The mucous neck cells in the apical part of the glands, furthermore the parietal cells and chief cells of the basal part of the gland were all positive for claudin-18, in the same way as the enteroendocrine cells. Cells of the basal part of the pyloric glands showed intense, linear, membranous claudin-2 positivity in the case of mild, moderate and severe lymphocytic gastritis, but cells of the superficial portion of these glands, and the surface gastric cells in this region were claudin-2 negative. Fibroblasts, endothelial cells, lymphocytes of the propria layer, the smooth muscle cells and vegetative neurons were all negative for claudin-2. All gastric epithelial cells were negative for claudin-1, -3, -4, -5, -6, -7, -8, and -10. The endothelial cells of the propria layer had intense claudin-5 positivity. Conclusion: The claudin-1, -2, -3, -4, -5, -6, -7, -8, -10 and -18 expression of chronic lymphocytic gastritis does not differ from healthy canine stomach.