Effects of Receptor for Advanced Glycation End-Products (RAGE) Signaling on Intestinal Ischemic Damage in Mice

Superior mesenteric artery ischemia and nonocclusive mesenteric ischemia are representative diseases of the vascular emergency known as irreversible transmural intestinal necrosis (ITIN). The receptor for advanced glycation end-products (RAGE) belongs to the immunoglobulin superfamily of extracellular ligands, which also includes high-mobility group box 1 (HMGB-1) and proteins of the S100 family. The HMGB-1 ligands have been implicated in the pathogenesis of various inflammatory disorders. This study was designed to investigate the relation between RAGE and ITIN in a murine acute intestinal ischemic model.

ITIN was induced by clipping the cranial mesenteric artery and the peripheral blood vessels. Mucosal and blood samples were collected and analyzed by reverse-transcription PCR and immunohistochemistry for mucosal inflammation and levels of RAGE-related proteins. The influence of RAGE signaling on intestinal cell reproduction was investigated using the cell scratch test, an in vitro wound-healing assay. Finally, RAGE-related proteins and their respective inhibitors were administered intraperitoneally to ITIN model mice to determine their effects.

RAGE-expressing cells were located at the base of the intestinal crypts at day 0. As ITIN progressed, most of the damaged intestinal cells expressed RAGE, and ligands of RAGE such as HMGB-1, S100 A8/A9, and S100β were present in the crypt cells from the bottom to the top. The quantities of S100 A8/A9 and S100β were particularly high, above the levels found in other diseases. When S100 A8/A9 and S100β were applied to small intestinal epithelial cells in vitro, regeneration was significantly impeded. Inflammatory Gr1+ neutrophils and F4/80+ macrophages are involved in tissue ischemia. S100 A8/A9 enhances inflammatory myeloid cell influx.

RAGE-related proteins are elevated in ITIN model mice and impede intestinal regeneration in vitro. RAGE-related proteins may be a new therapeutic target or a new marker for ITIN.