Expression and Polarization of Intercellular Adhesion Molecule-1 on Human Intestinal Epithelia: Consequences for CD11b/CD18-Mediated Interactions with Neutrophils

Abstract

Background: Epithelial dysfunction and patient symptoms in inflammatory intestinal diseases such as ulcerative colitis and Crohn's disease correlate with migration of neutrophils (PMN) across the intestinal epithelium. In vitro modeling of PMN transepithelial migration has revealed distinct differences from transendothelial migration. By using polarized monolayers of human intestinal epithelia (T84), PMN transepithelial migration has been shown to be dependent on the leukocyte integrin CDllb/CD18 (Mac-i), but not on CD11a/CD18 (LFA-1). Since intercellular adhesion molecule-i (ICAM-1) is an important endothelial counterreceptor for these integrins, its expression in intestinal epithelia and role in PMN-intestinal epithelial interactions was investigated. Materials and Methods: A panel of antibodies against different domains of ICAM-1, polarized monolayers of human intestinal epithelia (T84), and natural human colonic epithelia were used to examine the polarity of epithelial ICAM-1 surface expression and the functional role of ICAM-1 in neutrophil-intestinal epithelial adhesive interactions. Results: While no surface expression of ICAM-1 was detected on unstimulated T84 cells, interferon-y (IFNy) elicited a marked expression of ICAM-1 that selectively polarized to the apical epithelial membrane. Similarly, apically restricted surface expression of ICAM-1 was detected in natural human colonic epithelium only in association with active inflammation. With or without IFN,y pre-exposure, physiologically directed (basolateralto-apical) transepithelial migration of PMN was unaffected by blocking monoclonal antibodies (mAbs) to ICAM-1. In contrast, PMN migration across IFNy-stimulated monolayers in the reverse (apical-to-basolateral) direction was inhibited by anti-ICAM-1 antibodies. Adhesion studies revealed that T84 cells adhered selectively to purified CDllb/CD18 and such adherence, with or without IFNy pre-exposure, was unaffected by ICAM-1 mAb. Similarly, freshly isolated epithelial cells from inflamed human intestine bound to CD llb/CD18 in an ICAM-i-independent fashion. Conclusions: These data indicate that ICAM-1 is strictly polarized in intestinal epithelia and does not represent a counterreceptor for neutrophil CD1 lb/CD 18 during physiologically directed transmigration, but may facilitate apical membrane-PMN interactions after the arrival of PMN in the intestinal lumen.

Short exposure of intestinal epithelial cells to TNF-α and histamine induces Mac-1-mediated neutrophil adhesion independent of protein synthesis

“…In preliminary experiments, we have obtained almost the same results using other intestinal epithelial cell lines (T84 and Caco-2, data not shown). Together these observations suggest that neutrophil Mac-1 but not LFA-1 is possibly involved in the interactions between neutrophils and apical surface of intestinal epithelium, and intestinal ICAM-1 molecule is not likely to be utilized as a counter-receptor for Mac-1 during short-duration stimulation (30 min) with TNF-␣ or histamine, although ICAM-1 is demonstrated to be selectively expressed on the apical intestinal epithelial membrane [42]. The possibility is further supported by the findings that neutrophil adhesion to intestinal epithelial cells is increased by stimulation of neutrophils with IL-8 or TNF-␣, which up-regulates neutrophil Mac-1 expression.…”

“…It has been reported that neutrophil adhesion to the basolateral surface of intestinal epithelium is dependent on neutrophil Mac-1 (CD11b/CD18) but not on LFA-1 (CD11a/CD18), and that ICAM-1 (CD54), a counter-receptor for Mac-1 and LFA-1, is little expressed on the basolateral surface of intestinal epithelium [42]. Furthermore, transepithelial migration is reported to be mediated by neutrophil and epithelial CD47 molecules [12].…”

Dimerization and the effectiveness of ICAM-1 in mediating LFA-1-dependent adhesion

“…ICAM-1 mAbs R6.5 (35), CA-7 (27), CL203 (36), and CBRIC1͞11 (37), and the LFA-1 blocking mAb TS1͞22 (38) have been described. Within ICAM-1, mAb R6.5 maps to domain 2 (26), mAb CBRIC1͞11 maps to domain 3 (37), mAb CL203 maps to domain 4 (26), and mAb CA-7 maps to domain 5 (27). mAb 2H11 was a generous gift from Ellis L. Reinherz (Dana-Faber Institute, Boston) (39).…”

Neutrophil-Epithelial Interactions

“…Years ago, it was reported that primary epithelial cells and certain epithelial cell lines express little intercellular adhesion molecule 1 except under inflammatory conditions, 86e89 where its up-regulated expression was limited in a polarized manner to the apical epithelial membrane. 88 Although the functional role of apically expressed intercellular adhesion molecule 1 under such conditions remained under question for several years, recent investigations have suggested that migrated neutrophils can bind to apically expressed intercellular adhesion molecule 1, resulting in myosin light-chain kinaseemediated actin reorganization, increased epithelial permeability, enhanced neutrophil transepithelial migration, and epithelial cell proliferative responses. 90,91 There is also evidence of interactions of migrated neutrophils with another apical epithelial receptor termed decay accelerating factor (CD55) that results in retention of neutrophils on the luminal surface.…”