SAT-137 NON-CANONICAL CHOLINERGIC ANTI-INFLAMMATORY PATHWAY-MEDIATED ACTIVATION OF PERITONEAL MACROPHAGES INDUCES HES1 AND BLOCKS KIDNEY INJURY

Abstract

The cholinergic anti-inflammatory pathway (CAP) links the nervous and immune systems and modulates innate and adaptive immunity. Activation of the CAP by vagus nerve stimulation (VNS) exerts protective effects in a wide variety of clinical disorders including rheumatoid arthritis and Crohn’s disease,and in murine models of acute kidney injury including ischemia/ reperfusion injury (IRI). The canonical CAP pathway involves activation of splenic alpha7-nicotinic acetylcholine receptor (α7nAChR)-positive macrophages by splenic β2-adrenergic receptor-positive CD4+ T cells. However, detailed role of these immune cells in vivohas yet to be established. RNA-seq using peritoneal macrphages from WT andα7nAChRKO mice was performed after nicotine and/or LPS treatment. Kidney IRI (bilateral, 26 mins) was used as an acute kidney injury model and was performed 24 hr after VNS (left side, 5 Hz, 50 μA for 10 min) treatment or adoptive transfer of treated-macrophages. Kidney injury was evaluated 24 hr later using plasma creatinine, kidney Kim-1 mRNA expression and histology (H&E).TNF level in the media was measured by ELISAand RAW 264.7 cells were used as macrophages for the experiments requiring modifications of gene expression. Adoptive transfer of 1x105nicotine-treated peritoneal macrophages from α7nAChR+/+(α7WT; progeny control) but not from α7nAChR-/-(α7KO) mice protected kidneys of recipient mice from IRI, showing the importance of α7nAChR on macrophages. Nicotine-induced genes whose expressions were lower (<1/2 compared to α7nAChR+/+-derived cells) in α7nAChR-/--derived peritoneal macrophages were extractedby RNA-seq. We focused on hairy and enhancer of split-1 (Hes1), a basic helix-loop-helix (bHLH) transcription factor that acts as a transcriptional repressor of genes that require a bHLH protein for their transcription.VNS induced Hes1 expression in peritoneal macrophags. siRNA against Hes1 inhibited nicotine-induced TNF suppression, and Hes1 overexpression suppressed LPS-stimulated TNF induction in RAW 264.7 cells. Hes1 overexpression in RAW 264.7 cells mainly induced macrophage M2 markers (anti-inflammatory). Lastly we found that adoptive transfer of Hes1-overexpressing RAW 264.7 cells protected the kidney from IRI. These data demonstrate that Hes1 is a new downstream signaling molecule of α7nAChR in the CAP.