Aim: The interaction of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) with integrin alpha4beta7 mediates lymphocyte recruitment into mucosa-associated lymphoid tissue (MALT). Nodular gastritis is characterized by a unique military pattern on endoscopy representing increased numbers of lymphoid follicles with germinal center, strongly associated with H pylori infection. The purpose of this study was to address the implication of the MAdCAM-1/integrin beta7 pathway in NG.
Methods: We studied 17 patients with NG and H pylori infection and 19 H pylori-positive and 14 H pylori-negative controls. A biopsy sample was taken from the antrum and snap-frozen for immunohistochemical analysis of MAdCAM-1 and integrin beta7. In simultaneous viewing of serial sections, the percentage of MAdCAM-1-positive to von Willebrand factor-positive vessels was calculated. We also performed immunostaining with anti-CD20, CD4, CD8 and CD68 antibodies to determine the lymphocyte subsets co-expressing integrin beta7.
Results: Vascular endothelial MAdCAM-1 expression was more enhanced in gastric mucosa with than without H pylori infection. Of note, the percentages of MAdCAM-1-positive vessels were significantly higher in the lamina propria of NG patients than in H pylori-positive controls. Strong expression of MAdCAM-1 was identified adjacent to lymphoid follicles and dense lymphoid aggregates. Integrin beta7-expressing mononuclear cells, mainly composed of CD20 and CD4 lymphocytes, were associated with vessels lined with MAdCAM-1-expressing endothelium.
Conclusion: Our results suggest that the MAdCAM-1/integrin alpha4beta7 homing system may participate in gastric inflammation in response to H pylori-infection and contributes to MALT formation, typically leading to the development of NG.