RAGE and ICAM-1 cooperate in mediating leukocyte recruitment during acute inflammation in vivo

Abstract

The receptor for advanced glycation end products (RAGE) contributes to the inflammatory response in many acute and chronic diseases. In this context, RAGE has been identified as a ligand for the ␤ 2 -integrin Mac-1 under static in vitro conditions. Because intercellular adhesion molecule (ICAM)-1 also binds ␤ 2 -integrins, we studied RAGE ؊/؊ , Icam1 ؊/؊ , and RAGE ؊/؊ Icam1 ؊/؊ mice to define the relative contribution of each ligand for leukocyte adhesion in vivo. We show that trauma-induced leukocyte adhesion in cremaster muscle venules is strongly dependent on RAGE and ICAM-1 acting together in an overlapping fashion. Additional in vivo experiments in chimeric mice lacking endothelium-expressed RAGE and ICAM-1 located the adhesion defect to the endothelial compartment. Using microflow chambers coated with P-selectin, CXCL1, and soluble RAGE (sRAGE) demonstrated that sRAGE supports leukocyte adhesion under flow conditions in a Mac-1-but not LFA-1-dependent fashion. A static adhesion assay revealed that wild-type and RAGE ؊/؊ neutrophil adhesion and spreading were similar on immobilized sRAGE or fibrinogen. These observations indicate a crucial role of endotheliumexpressed RAGE as Mac-1 ligand and uncover RAGE and ICAM-1 as a new set of functionally linked adhesion molecules, which closely cooperate in mediating leukocyte adhesion during the acute traumainduced inflammatory response in vivo. IntroductionLeukocyte recruitment into inflamed tissue follows a well-defined cascade of events, beginning with the capture of free-flowing leukocytes to the vessel wall and subsequent leukocyte rolling along and adhesion to the inflamed endothelial layer. 1,2 During rolling, leukocytes get into close contact with the endothelial surface, which allows endothelial bound chemokines to interact with their specific receptors on the leukocyte surface. This triggers the activation of integrins, which leads to firm leukocyte arrest on the endothelium. In addition, integrindependent signaling events induce cytoskeletal rearrangements and cell polarization, modifications necessary in helping to prepare the attached leukocyte to spread and crawl in search for its way out of the vasculature into tissue. [2][3][4][5][6] Recent evidence has shown that the ␤ 2 -integrin Mac-1 is crucially involved in transducing Syk-dependent signaling events necessary for sustained leukocyte adhesion. [7][8][9] The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor that has been identified to be a major player in chronic inflammatory conditions. 10,11 This has been mainly attributed to its strong effects on perpetuating nuclear factor-B (NF-B) activation and NF-Bdependent signaling 10,11 and its ability to induce its own expression. 10,12 Besides its function as a signaling molecule, RAGE also binds to Mac-1, which has been demonstrated under in vitro conditions. 13 In addition, a reduction of leukocyte extravasation into the inflamed peritoneal cavity was found in RAGE Ϫ/Ϫ mice after intraperitoneal application of th...

The Mammalian Actin-Binding Protein 1 Is Critical for Spreading and Intraluminal Crawling of Neutrophils under Flow Conditions

“…Thus, unlike Syk, mAbp1 seems to be only required when mechanical force is applied on the b 2 integrins. Intraluminal crawling of neutrophils is a postarrest step of the recruitment cascade, which has been shown to be mediated by interaction of Mac-1 and endothelial ICAM-1 in mice in vivo (8,48,59). This was also true in our experimental setting using isolated murine PMN migrating on immobilized ICAM-1 under shear stress conditions.…”

“…In unstimulated cremaster muscle venules, rolling flux fraction observed within the first 30 min after cremaster muscle exteriorization was similar between the two groups (Fig. 3A, 0.32 6 0.02 in mAbp1 +/+ mice and 0.33 6 0.03 in mAbp1 2/2 mice), suggesting that mAbp1 was dispensable for leukocyte rolling at least in this setting, where rolling was induced by surgical trauma and dependent on P-selectin (48). Next, we analyzed leukocyte adhesion in unstimulated cremaster muscle venules (pre) and found no significant difference in the number of adherent leukocytes between mAbp1 +/+ mice (200 6 24/mm 2 ) and mAbp1 2/2 mice (236 6 28/mm 2 ) (Fig.…”

“…To study intraluminal leukocyte crawling, murine TNF-a (500 ng per mouse) was injected intrascrotally 2-4 h prior to intravital microscopy. Leukocyte crawling was defined as displacement of the cell by at least one cell diameter within the observation period of 10 min, and was analyzed offline using Image J software plugin Manual Tracking and the Chemotaxis and Migration tool (48). Percentage of cells migrating in the direction of blood flow was defined as the number of leukocytes migrating within an angle of 60˚in the direction of blood flow in the venule compared with the number of all migrating leukocytes in the given vessel segment.…”

The Role of Receptor for Advanced Glycation Endproducts (RAGE) in Infection

“…1, indicated by the blue line and blue "+"). Furthermore, a recent report shows that endothelial expressed RAGE acts in concert with ICAM-1 in mediating β 2 integrin-dependent leukocyte adhesion during acute trauma-induced infl ammation [28] (Fig. 1, indicated by the green line and green "+").…”

“…Furthermore, lateral (in cis) RAGE-Mac-1 interaction on the leukocyte surface is mediated by HMGB1 and activates Mac-1-intercellular adhesion molecule (ICAM)-1 dependent adhesion and migration and augments leukocyte recruitment [27] (indicated by the blue line and blue "+"). Moreover, a recent report shows that endothelially expressed RAGE acts in concert with ICAM-1 in mediating β 2 integrin-dependent leukocyte adhesion during acute trauma-induced infl ammation [28] (indicated by the green line and green "+"). One possibility is that RAGE uses as yet unknown adaptors framing a whole `new' signaling cascade to NF-κB.…”