Anales RANF

P9. P URINERGIC S IGNALING IN THE C ARDIOVASCULAR S YSTEM P.86 REGULATION OF IL-6 FORMATION IN THE HEART BY CD73- DERIVED ADENOSINE A.S. Henseler 1 , C.Alter 1 , Z.Ding 1 , E.Engelowski 1 , J.Scheller 1 , J.Schrader 1 1 Heinrich-Heine University Düsseldorf, North Rhine Westphalia, Germany Interleukin-6 (IL-6) is secreted by the infarcted heart showing a dual response: in the acute phase of myocardial infarction (MI) IL-6 is cardio-protective but can turn to be harmful when the IL-6 secretion becomes chronic. A previous study suggested the presence of a targetable adenosine–A2bR–IL-6-axis triggered by adenosine formed by the ischemic heart. We therefore studied A2bR signaling und functional relevance in monocytes/macrophages in the infarcted murine heart. IL-6 expression and secretion was analyzed in murine peritoneal macrophages as well as monocytes from healthy human donors after A2bR activation (BAY60-6583). Protein expression/secretion of several cytokines or regulatory proteins was analyzed by qPCR and Bioplex. We found that IL-6 expression and secretion was strongly induced by A2bR stimulation in murine macrophages and human monocytes. This effect was mediated by Gq-signaling, since a specific Gq-inhibitor (FR-900359(UBO-QIC)) strongly inhibited A2bR-induced IL-6 expression/secretion. We further analyzed the expression of IL-6 mRNA regulatory factors and found that in A2bR -/- macrophages, the expression of Regnase-1, an IL-6-mRNA destabilizing protein was significantly increased. To analyze the functional impact of T-cell derived adenosine on IL-6 formation in the infarcted heart, we analyzed the release of various cytokines into the effluent perfusate from isolated hearts (Langendorff) from mice lacking CD73 on T- cells (CD4 T-cells are known to be the main adenosine producers under these conditions). We found that IL6, MCP and MIP1β, were significantly reduced in CD4CD73 -/- mice. In summary this study shows that adenosine formed by CD73 on T-cells controls IL-6 secretion post MI, most likely involving A2bR stimulation of macrophages in a Gq- mediated manner. This opens the possibility that inhibitors of A2bR may be therapeutically beneficial in limiting cardiac IL-6 formation.