atl-146e and Acute-Kidney-Injury

The role of monocytes/macrophages in the pathogenesis of ischemia-reperfusion injury (IRI) is unknown. We sought to determine whether activation of macrophage adenosine 2A (A(2A)) receptors (A(2A)Rs) mediates tissue protection. We subjected C57Bl/6 mice infused with clodronate [dichloromethylene bisphosphonate (Cl(2)MBP)] to IRI (32 min of ischemia followed by 24 h of reperfusion) to deplete them of macrophages. IRI induced an elevation of plasma creatinine that was reduced with Cl(2)MBP (26% of control). Adoptive transfer of murine RAW 264.7 cells reconstituted injury, an effect blocked significantly by A(2A) agonists (27% of plasma creatinine from mice reconstituted with macrophages). Macrophages subjected to A(2A) knockout by small interfering RNA were adoptively transferred to macrophage-depleted mice and reconstituted injury (110% of control mice); however, the increase in plasma creatinine was blocked by A(2A) agonists (20% of vehicle treatment). Finally, the A(2A) agonist effect on IRI was blocked in macrophage-depleted A(2A)-knockout mice reconstituted with wild-type RAW 264.7 cells. RNase protection assays 24 h after IRI demonstrated that macrophages are required for IL-6 and TGF-beta mRNA induction. However, A(2A) agonist-mediated tissue protection is independent of IL-6 and TGF-beta mRNA. We conclude that the full extent of IRI requires macrophages and that A(2A) agonist-mediated tissue protection is independent of activation of macrophage A(2A)Rs.

Topics: Acute Kidney Injury; Adenosine A2 Receptor Agonists; Animals; Antimetabolites; Cell Line; Clodronic Acid; Cyclohexanecarboxylic Acids; Cytokines; Humans; Kidney; Liposomes; Macrophages; Mice; Mice, Inbred C57BL; Purines; Receptor, Adenosine A2A; Reperfusion Injury; RNA, Messenger; Transfection

We previously demonstrated in rats and mice that agonists of A(2A)-adenosine receptors (A(2A)-ARs) reduce renal injury following ischemia-reperfusion. We now extend these studies and examine the effects of ATL-146e (formerly DWH-146e), an A(2A)-AR agonist, and rolipram, a type IV phosphodiesterase (PDE 4) inhibitor, on murine renal injury following ischemia-reperfusion.. C57BL/6 mice were treated with rolipram, ATL-146e, or both compounds combined and were subjected to renal ischemia for 32 minutes and reperfusion for 24 to 48 hours. In vitro studies were performed on suspended and adhering human neutrophils.. Continuous delivery of rolipram or ATL-146e during reperfusion reduced renal injury in a dose-dependent manner. Maximal protection was observed when ATL-146e was infused for six hours during reperfusion. Elevated plasma creatinine and myeloperoxidase activity produced by ischemia-reperfusion were reduced by rolipram (0.1 ng/kg/min) and ATL-146e (10 ng/kg/min) by up to approximately 60% and 70%, respectively. Co-infusion of both compounds produced a maximum reduction of plasma creatinine of approximately 90% and myeloperoxidase activity. In vitro studies on suspended and adhering human neutrophils demonstrated that selective stimulation of A(2A)-ARs by ATL-146e increased cAMP accumulation, reduced oxidative activity of activated neutrophils, and decreased activated neutrophil adherence. These responses were potentiated by rolipram.. We conclude that the combined infusion of ATL-146e and rolipram leads to enhanced renal tissue protection from ischemia-reperfusion by mechanisms that may include reduced neutrophil adherence/recruitment and release of reactive oxygen species.

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; Acute Kidney Injury; Animals; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 4; Cyclohexanecarboxylic Acids; Dose-Response Relationship, Drug; Drug Therapy, Combination; Humans; Mice; Mice, Inbred C57BL; Neutrophils; Peroxidase; Phosphodiesterase Inhibitors; Purinergic P1 Receptor Agonists; Purines; Reactive Oxygen Species; Receptor, Adenosine A2A; Receptors, Purinergic P1; Reperfusion Injury; Respiratory Burst; Rolipram