LJ529 attenuates mast cell-related inflammation via A3R-PKCε-ALDH2 pathway after subarachnoid hemorrhage in rats

Exp Neurol. 2021 Jun:340:113686. doi: 10.1016/j.expneurol.2021.113686. Epub 2021 Mar 10.

Abstract

Background and purpose: Mast cells (MCs) has been recognized as an effector of inflammation or a trigger of inflammatory factors during stroke. LJ529 was reported to attenuate inflammation through a Gi protein-coupled Adenosine A3 receptor (A3R) after ischemia. Here, we aim to study the protective effect and its mechanism of LJ529 in subarachnoid hemorrhage (SAH) rat model for mast cell-related inflammation.

Methods: 155 Sprague-Dawley adult male rats were used in experiments. Endovascular perforation was used for SAH model. Intraperitoneal LJ529 was performed 1 h after SAH. Neurological scores were measured 24 h after SAH. Rotarod and morris water maze tests were evaluated for 21 days after SAH. Mast cell degranulation was assessed with Toluidine blue staining and Chymase/Typtase protein expressions. Mast cell-related inflammation was evaluated using IL-6, TNF-α and MCP-1 protein expressions. MRS1523, inhibitor of GPR18 and ε-V1-2, inhibitor of PKCε were respectively given intraperitoneally (i.p.) 1 h and 30 min before SAH for mechanism studies. Pathway related proteins were investigated with western blot and immunofluorescence staining.

Results: Expression of A3R, PKCε increased after SAH. LJ529 treatment attenuated mast cell degranulation and inflammation. Meanwhile, both short-term and long-term neurological functions were improved after LJ529 treatment. Administration of LJ529 resulted in increased expressions of A3R, PKCε, ALDH2 proteins and decreased expressions of Chymase, Typtase, IL-6, TNF-α and MCP-1 proteins. MRS1523 abolished the treatment effects of LJ529 on neurobehavior and protein levels. ε-V1-2 also reversed the outcomes of LJ529 administration through reduction in protein expressions downstream of PKCε.

Conclusions: LJ529 attenuated mast cell-related inflammation through inhibiting degranulation via A3R-PKCε-ALDH2 pathway after SAH. LJ529 may serve as a potential treatment strategy to relieve post-SAH brain injury.

Keywords: Adenosine A3 receptor; Inflammation; LJ529; Mast cells; Subarachnoid hemorrhage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / pharmacology
  • Adenosine / therapeutic use
  • Adenosine A3 Receptor Agonists / pharmacology
  • Adenosine A3 Receptor Agonists / therapeutic use*
  • Aldehyde Dehydrogenase, Mitochondrial / biosynthesis*
  • Animals
  • Dose-Response Relationship, Drug
  • Inflammation / metabolism
  • Inflammation / prevention & control
  • Male
  • Mast Cells / drug effects
  • Mast Cells / metabolism
  • Protein Kinase C-epsilon / biosynthesis*
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Adenosine A3 / biosynthesis*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Subarachnoid Hemorrhage / drug therapy*
  • Subarachnoid Hemorrhage / metabolism
  • Thionucleosides / pharmacology
  • Thionucleosides / therapeutic use*

Substances

  • 2-chloro-N(6)-(3-iodobenzyl)-5'-N-methylcarbamoyl-4'-thioadenosine
  • Adenosine A3 Receptor Agonists
  • Receptor, Adenosine A3
  • Thionucleosides
  • Aldehyde Dehydrogenase, Mitochondrial
  • Aldh2 protein, rat
  • Protein Kinase C-epsilon
  • Adenosine