Essential role of receptor for advanced glycation end products (RAGE) in the inflammatory response and mucosal injury after hemorrhagic shock (HS)

Abstract

Introduction: Activation of RAGE by alarm ligands including HMGB1 stimulates the inflammatory response. We hypothesized that HS activates RAGE in injured tissues, specifically the intestinal epithelium. We previously showed that soluble(s) RAGE blocks ligand-RAGE interactions and prevents HS-induced mucosal damage/inflammation. We utilized RAGE deficient (KO) animals to definitively test the hypothesis that RAGE mediates intestinal injury following HS. Methods: RAGE KO mice and controls (n = 5/group) underwent 3h HS followed by 24h resuscitation. Intestinal mucosal permeability to fluorescein-labeled dextran (FD4) was determined using everted gut sacs; bacterial translocation (BT) to mesenteric lymph nodes was quantified. Serum IL-6 and IL-10 levels were measured by ELISA. In vitro, Caco-2 enterocytic monolayers grown in bicameral diffusion chambers were subjected to 16h hypoxia (0.2%O2) and reoxygenation. Monolayers were pretreated with sRAGE or anti-RAGE antibody; FD4 permeability was measured. Using ANOVA, p<0.05 significant. Results: RAGE KO mice post-HS had significant reductions in both HS-induced injury and inflammation vs controls. Permeability (pL/min/cm) was 0.0620 ± 0.008 vs 0.130 ± 0.02, 52%-(p<.001), BT(cfu/g) was 102 ± 50 vs 1280 ± 407, 92%-(p<.001). IL-6, a pro-inflammatory cytokine, was suppressed in HS RAGE KO. IL-10, an anti-inflammatory cytokine, was increased in HS RAGE KO vs controls. In vitro, pretreatment with sRAGE or anti-RAGE antibody prior to hypoxia dramatically reduced monolayer permeability to FD4 after 24h reoxia vs hypoxia/reoxia alone (17.5 ± 2.9, 18.3 ± 3.9 vs 44.65 ± 5.4-p<0.001). Conclusions: These studies identify RAGE as an essential receptor for inflammatory response induction and gut mucosal injury following HS. Preventing the RAGE-ligand interaction is critical for maintaining gut barrier function after HS; RAGE may represent a new therapeutic target to prevent end-organ damage in HS.