Association of increased B7 protein expression by infiltrating immune cells with progression of gastric carcinogenesis

B7 negative costimulatory molecules are a group of molecules associated with the occurrence, development, and therapy of cancers. Here, we aimed to determine the clinical significance of PD-L1, B7-H3, and B7-H4 and their expression in CD8 and CD68 positive cells at different stages of gastric carcinogenesis. We detected PD-L1, B7-H3, B7-H4, CD8, and CD68 expression in samples by immunohistochemical staining of 62 chronic superficial gastritis (CSG) samples, 72 chronic atrophic gastritis (CAG) samples, 68 low-grade intraepithelial neoplasia (LIN) samples, 65 high-grade intraepithelial neoplasia (HIN) samples obtained from gastroscopic biopsies and 50 gastric adenocarcinoma (GA) samples obtained from surgical resections. Then we statistically analyzed the expression differences and correlations. Our results indicated that B7 and CD68 expression on infiltrating immune cells was associated with disease progression. However, infiltration of CD8+ cells decreased with disease progression. B7-H3 expression was markedly enhanced at neoplasia and GA stages. B7-H3 in tumor cells was negatively correlated with CD8-expressing cells. Conversely, B7-H3 expression in tumor-infiltrating immune cells was positively correlated with CD68-expressing cells. B7-H4 expression was found in the cell membrane at the stages of gastritis and low-grade neoplasia and was gradually expressed in the cytoplasm at high-grade neoplasia and GA stages. High B7-H4 expression in infiltrating immune cells was also significantly associated with lower CD8-positive and higher CD68-positive cell densities. Increased B7 protein expression by infiltrating immune cells was associated with disease progression, and specifically, the level of B7-H3 expression and localization of B7-H4 expression differed significantly among different stages of gastric carcinogenesis.