CXC chemokine receptor 1 (CXCR1) is expressed mainly by neutrophils in inflamed gut and stomach tissues.

CXC chemokine receptor 1 (CXCR1) is one of the important receptors for CXC chemokines with ELR motif, of which interleukin 8 (IL-8; CXCL8) is representative. To identify the cell type(s) of CXCR1-expressing cells in inflamed stomach and gut tissues, we performed immunoperoxidase method using pre-fixed frozen sections. In chronic gastritis associated with Helicobacter pylori infection (7 cases), CXCR1 was positive in neutrophils (polymorphonuclear leucocytes) in the lamina propria near the neck region and those in pit abscess. In ulcerative colitis (6 cases) and Crohn's disease (5 cases), CXCR1 was sporadically expressed by neutrophils in the mucosa, and particularly CXCR1+ neutrophils were abundantly distributed in inflammatory granulation tissue in ulcer base. Double staining confirmed co-localization of CXCR1 and neutrophil elastase. Neither CD3+ T lymphocytes nor CD68+ macrophages were positive for CXCR1. Immunoelectron microscopy confirmed the cell surface localization of CXCR1. Neutrophils protect the host from microbial pathogens. However, they also cause damages to host tissues in chronic inflammation. Therefore, our study underscores the importance of CXCR1 expression in inflammatory processes.