We also found that circulating PGE2 carried by nanoparticles is stable, and that these nanoparticles are A33+. A33+ is a marker of intestinal epithelial cells, which suggests that the nanoparticles are see more derived from the intestine. Mice treated with PGE2 associated with intestinal mucus-derived exosome-like nanoparticles (IDENs) induced NKT cell anergy. PGE2 treatment leads to activation of the Wnt/β-catenin pathway by inactivation of glycogen synthase kinase 3β of NKT cells. IDEN-associated PGE2 also induces NKT cell anergy through modification of the ability of dendritic cells to induce interleukin-12 and interferon-β in the context of both glycolipid
presentation and Toll-like receptor–mediated pathways. Conclusion: These findings demonstrate that IDEN-associated PGE2 serves as an endogenous immune modulator between the liver and intestines and maintains liver NKT cell homeostasis. This finding has implications for development of NKT cell–based
immunotherapies. (HEPATOLOGY 2013) Unlike T cells, natural killer T (NKT) cells respond to lipid-based antigens including self and foreign glycolipid and phospholipid antigens1 presented by CD1d-restricted antigen-presenting cells (APCs). Among these lipid-based antigens, alpha-galactosylceramide (α-GalCer) is a synthetic glycosphingolipid derived from the marine sponge, Agelas mauritianus, and is commonly used in mice and human NKT studies as a potent activator of NKT cells in vivo or in Ivacaftor concentration vitro.2 A single injection of the exogenous α-GalCer leads to NKT cell activation followed, by long-term anergy, thereby limiting its therapeutic use.3 A number of potential endogenous glycolipids derived from dietary metabolic products and lipids derived from some intestinal bacteria migrate constantly into the liver,4-6 and these lipids can activate liver NKT cells in vitro.7 It is, therefore, remarkable that liver NKT cells are normally quiescent even though they are constantly exposed to intestinal-derived
products. The molecular mechanisms that underlie induction of liver NKT cell anergy regulated by either Buspirone HCl exogenous α-GalCer or endogenous lipids are largely unknown. The gut communicates extensively with the liver8 through a number of gut-derived molecules that are constantly migrating into the liver. Prostaglandin E2 (PGE2) and Wnt ligands are enriched in the gut, and whether they migrate into the liver and subsequently contribute to induction of liver NKT anergy has not been fully investigated. Both PGE29 and Wnt10 regulated pathways are known to play a crucial role in immune tolerance; however, a direct link between these two key pathways remains to be identified, although recent studies have proposed involvement of the Wnt pathway in regulating T cells11,12 and dendritic cell (DC)10 activation.