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Kidney Week

Abstract: PO0245

Immunological Changes Following Cholinergic Anti-Inflammatory Pathway Stimulation

Session Information

  • AKI Mechanisms - 3
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Nash, William, University of Virginia School of Medicine, Charlottesville, Virginia, United States
  • Tanaka, Shinji, University of Virginia School of Medicine, Charlottesville, Virginia, United States
  • Okusa, Mark D., University of Virginia School of Medicine, Charlottesville, Virginia, United States
Background

The cholinergic anti-inflammatory pathway (CAP) protect mice from ischemia reperfusion injury (IRI). The interactions and mechanisms that regulate this effect are of great interest as targets for clinical intervention. Vagus nerve stimulation (VNS) induces neurotransmitter cascades that culminate in release of norepinephrine (NE) in the spleen. NE stimulates CD4+ T cells to produce acetylcholine via the choline acetyltransferase enzyme. Acetylcholine then stimulates anti-inflammation via splenic immune cells that express the α7 nicotinic acetylcholine receptor (α7nAChR). Adoptive transfer of splenic cells from VNS-treated mice protects kidneys from IRI. However, the downstream effects on splenic structure and function that lead to protection are still not fully understood. The goal of this study is to profile immune cells following CAP stimulation and identify key downstream mechanisms.

Methods

VNS was performed on mice in vivo and nicotine stimulation on immune cells ex vivo. Vagus nerve stimulation was triggered optogenetically using blue light to target the vagus nerve of mice expressing channelrhodopsin-2 under control of the vesicular glutamate transporter 2 promoter. Cells were collected from the spleen between 24- and 48-hours post-stimulation. A concentration of 50 μM nicotine in culture media was used to stimulate α7nAChR-expressing immune cells collected from the peritoneum of mice. Analysis of immune cell populations was performed with flow cytometry and single cell RNA sequencing.

Results

Overall optogenetic VNS led to a reduced number of CD45+ cells from the spleen. Within the CD45+ population, B1 cells and macrophages exhibited increased representations of ~30% and 60%, respectively. Monocyte and neutrophil representation remained relatively stable, but eosinophils displayed a marked reduction of ~60%. Single cell RNA sequencing showed increased novel gene expression in subpopulations of macrophages, including cell-cell adhesion genes (Spa17) and guanine nucleotide exchange factors (Arhgef5) that could regulate function.

Conclusion

Cholinergic stimulation triggers reorganization of immune cell populations and alterations in gene expression that are likely important for regulating the inflammatory environment. Additional characterization and functional studies are currently underway to fully identify the importance of observed changes.

Funding

  • NIDDK Support