Kidney Week

Abstract: SA-PO608

Hes1, a Newly Identified Downstream Mediator of α7nAChR on Macrophages in the Cholinergic Anti-Inflammatory Pathway, Plays a Protective Role in AKI

Session Information

• AKI: Other Mechanisms and Cell Cultures
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Inoue, Tsuyoshi, University of Virginia, Charlottesville, United States

Tsuyoshi Inoue,

• Abe, Chikara, Gifu University, Gifu, Japan

Chikara Abe,

• Tanaka, Shinji, University of Virginia, Charlottesville, Virginia, United States

Shinji Tanaka,

• Rosin, Diane L., University of Virginia, Charlottesville, Virginia, United States

Diane L. Rosin,

• Nangaku, Masaomi, The University of Tokyo, Tokyo, Japan

Masaomi Nangaku,

• Wada, Youichiro, The University of Tokyo, Tokyo, Japan

Youichiro Wada,

• Okusa, Mark D., University of Virginia, Charlottesville, Virginia, United States

Mark D. Okusa,

Background

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. The CAP involves splenic alpha7-nicotinic acetylcholine receptor (α7nAChR)-positive macrophages although their detailed role in vivo has yet to be established.

Methods

RNA-seq using peritoneal macrphages from WT and α7nAChRKO 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 ELISA and RAW 264.7 cells were used as macrophages for the experiments requiring modifications of gene expression.

Results

Adoptive transfer of 1x10⁵ nicotine-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 extracted by 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.

Conclusion

These data demonstrate that Hes1 is a new downstream signaling molecule of α7nAChR in the CAP.

Funding

• NIDDK Support