Effect of Microcystis aeruginosa Lipopolysaccharide (LPS) on Neonatal Rat Brain Microglia Cytokine and Chemokine release

Abstract

Neuroinflammation has been hypothesized to involve release by brain microglia (BMG) of the inflammatory cytokines interleukin 1 α(IL‐1α) and interleukin 6 (IL‐6), the chemokine macrophage inflammatory protein 2 α(MIP‐2), as well as the anti‐inflammatory cytokine transforming growth factor β1 (TGF‐β1). We have reported that M. aeruginosa LPS (MaLPS) stimulated BMG to release TNF‐α, TXB2, O2− and MMP‐9 (The Toxicologist 102(1):254, 2008). The purpose of this investigation was to determine the effect of MaLPS on BMG priming and release of IL‐1α, IL‐6, TGF‐β1, MIP‐2 and lactate dehydrogenase (LDH) in vitro. MaLPS (1.075 x 105 endotoxin units/mg) was isolated from M. aeruginosa strain UTCC 299 by hot phenol/water extraction. BMG isolated from neonatal rats were treated in vitro with MaLPS or Escherichia coli LPS (EcLPS) for 17 hours. IL‐1α, IL‐6, TGF‐β1 and MIP‐2 were determined by immunoassay, and LDH by enzyme activity. Results were the following (n=3‐4): LDH: release was observed at > 0.1 ng/mL MaLPS; IL‐6, & MIP‐2: concentration‐dependent release was detected at > 0.1 ng/mL MaLPS; IL‐1α: release was observed at > 1 ng/mL; and in contrast no release TGF‐β1 was observed. MaLPS appeared less potent than EcLPS. We conclude that MaLPS stimulates rat BMG cytokine and chemokine release in a concentration‐ and time‐dependent manner. Further characterization of BMG response to MaLPS at both the functional and molecular level is ongoing in our laboratories. Supported by Midwestern[P1] University and Florida International University.