Characterization of macrophage and neutrophil populations and their relationship to epithelial integrity in inflammatory bowel disease using a SignalStarTM multiplex immunohistochemistry assay 9308

Abstract Description Inflammatory bowel disease (IBD), typically characterized as either Crohn’s disease (CD) or ulcerative colitis (UC), is a chronic condition in which gut homeostasis, via breakdown of epithelial barrier function, is disrupted by excessive inflammation. Many subsets of immune cells are known to play roles in the pathogenesis of IBD. Higher numbers of pro-inflammatory M1 macrophages and neutrophils are present, while fewer anti-inflammatory M2 macrophages are observed. Increased neutrophil extracellular trap (NET) formation has also been found in UC, with mixed reports about NET levels in CD relative to normal controls. Neutrophils expressing CD177, a marker associated with migration and activation, are also reported to be present in higher proportions in both CD and UC, through their impact on disease severity is unclear. Here, we interrogate normal, CD, and UC colon tissues using an 8-plex SignalStar™ multiplex immunohistochemistry assay to compare M1 (CD68+CD86+) and M2 (CD68+CD206+) macrophages, CD177+ and CD177- neutrophils (MPO+S100A9+), and NETs (MPO+S100A9+citrullinated histone H3+) and evaluate the proximity of these cell types and features to one another. Pan-keratin is included to mark epithelial cells and may serve as a surrogate for epithelial integrity, with reduced levels reported in active UC. Characterization of these relationships is key to improving our understanding of IBD and potential therapeutic strategies to limit inflammation and promote resolution. Topic Categories Cellular Adhesion, Migration, and Inflammation (CAM)