Transmural gradient of leukocyte-endothelial interaction in the rat gastrointestinal tract

Abstract

-Gastrointestinal injury usually starts in the superficial mucosa. We investigated whether leukocyteendothelial interactions were greater in the gastrointestinal mucosa than the submucosa and muscularis in control tissue and after upregulation of adhesion molecules with endotoxin and after chemical insult with nonsteroidal anti-inflammatory drugs. Inactin-anesthetized rats were given either endotoxin, flurbiprofen, or nitric oxide (NO)-flurbiprofen, after which ICAM-1 and P-selectin expression was measured with the dual-label antibody technique. Leukocyte-endothelial interactions in the different gastric layers were assessed after endotoxin using intravital microscopy. Endotoxin caused a two-to threefold increase in ICAM-1 expression in the stomach and duodenum. There was, however, a gradient in expression across the gut wall with the level of expression in the superficial mucosa (per g) being only 10 -25% of that in the deeper layers in both control and endotoxin-treated animals. Constituitive expression of P-selectin in control animals was barely detectable. Endotoxin caused a modest increase in mucosal P-selectin but a very significant increase in the deeper layers. Flurbiprofen caused a slight upregulation of ICAM-1 in the gastric mucosa and duodenum, whereas NO-flurbiprofen had no affect on expression. Intravital microscopy revealed no adhesion and virtually no leukocyte rolling in the vessels of the gastric mucosa despite endotoxin treatment. There was, however, some adhesion and significant leukocyte rolling in the submucosa and muscularis. Thus the superficial gastric and duodenal mucosal microcirculations have a much lower density of ICAM-1 and P-selectin and less leukocyteendothelial interactions than occurs in the deeper layers of the gut wall even during stimulated upregulation with endotoxin. intracellular adhesion molecule 1; P-selectin; endotoxin; flurbiprofen; intravital microscopy MANY FORMS of gastrointestinal injury such as that caused by ischemia-reperfusion or nonsteroidal anti-inflammatory drugs (NSAID) are initiated by erosion of the superficial mucosa. Leukocytes appear to play a key role in these forms of injury (7,9,(23)(24)(25). Smith et al. (21) showed that ischemiareperfusion induced gastric mucosal erosion and bleeding in the rat. This injury was largely prevented when circulating neutrophils were depleted with antiserum. In the cat, administration of antibodies against leukocyte adhesion prevented the increase in mucosal permeability and net fluid secretion observed in the small bowel after ischemia-reperfusion (13).The NSAID indomethacin can cause severe mucosal injury. Asako et al. (1) demonstrated that clinically relevant concentrations of indomethacin induced leukocyte rolling and adhesion (but not emigration) through an leukotriene B4 (LTB4)-dependent mechanism. Wallace and co-workers then showed that the gastric injury induced by indomethacin in both the rat (25) and rabbit (23) could be markedly reduced by immunoneutralization of the adhesion molecule CD11/CD18. They also f...

Lactobacillus reuteriprevents colitis by reducing P-selectin-associated leukocyte- and platelet-endothelial cell interactions

“…These results do, however, agree with earlier studies from our laboratory showing that the superficial gastric and duodenal mucosal microcirculation have much lower density of intercellular adhesion molecule-1 and P-selectin and also less leukocyteendothelial interactions than occur in the deeper layers of the gut wall (39). This was true even during stimulated upregulation with endotoxin.…”

“…Values were obtained for leukocyte adhesion and rolling as previously described (39). Leukocytes were regarded as adherent if they remained stationary for 30 s and longer and rolling if they moved with a lower velocity than red blood cells.…”

Intravital Microscopy of Lipopolysaccharide-Induced Inflammatory Changes in Different Organ Systems—A Scoping Review

“…Mangell et al investigated the role of P-selectin-dependent leukocyte recruitment in LPS-induced intestinal barrier dysfunction in mice [40]. This study is particularly important as it showed that LPS-induced leukocyte recruitment is mediated by P-selectin.…”