Anti-inflammatory Effect of AZD6244 on Acrolein-Induced Neuroinflammation
Clinically, high levels of acrolein (a highly reactive α, β-unsaturated aldehyde) and acrolein adducts are detected in the brain of patients with CNS neurodegenerative diseases, including Alzheimer’s disease and spinal cord injury. Our previous study supports this notion by showing acrolein as a neurotoxin in a Parkinsonian animal model. In the present study, the effect of AZD6244 (an ATP non-competitive MEK1/2 inhibitor) on acrolein-induced neuroinflammation was investigated using BV-2 cells and primary cultured microglia. Our immunostaining study showed that lipopolysaccharide (LPS, an inflammation inducer as a positive control) increased co-localized immunoreactivities of phosphorylated ERK and ED-1 (a biomarker of activated microglia) in the treated BV-2 cells. Similar elevation in co-localized immunoreactivities of phosphorylated ERK and ED-1 was detected in the acrolein-treated BV-2 cells. Furthermore, Western blot assay showed increases in phosphorylated ERK in BV-2 cells subjected to LPS (1 μg/mL) or acrolein (30 μM); these increases were blocked by AZD6244 (10 μM). At the same time, AZD6244 attenuated LPS-induced TNF-α (a pro-inflammatory cytokine) and cyclooxygenase-II (COX II, a pro-inflammatory enzyme). Consistently, AZD6244 reduced acrolein-induced elevations in COX-II mRNA and COX-II protein expression. In addition, AZD6244 inhibited acrolein-induced increases in activated caspase 1 (a biomarker of inflammasome activation) and heme oxygenase-1 (a redox-regulated chaperone protein) in BV-2 cells. Using a transwell migration assay, AZD6244 attenuated acrolein (5 μM)-induced migration of BV-2 cells and primary cultured microglia. In conclusion, our study shows that acrolein is capable of inducing neuroinflammation which involved ERK activation in microglia. Furthermore, AZD6244 is capable of inhibiting acrolein-induced neuroinflammation. Our study suggests that ERK inhibition may be a neuroprotective target against acrolein-induced neuroinflammation in the CNS neurodegenerative diseases.
KeywordsAcrolein Neuroinflammation ERK pathway AZD6244 BV-2 cells
The authors express their gratitude to Dr. C.Y. Chai at Institute of Biomedical Sciences, Academia Sinica, for his encouragement and support. Special thanks are due Dr. R.K. Freund at the Department of Pharmacology, University of Colorado, Anschutz, CO., USA, for editing this paper.
This study was financially supported MOST107-2320-B-010-019-MY3, MOST106-2320-B-010-004, and V106C-046, Taipei, Taiwan, R.O.C.
Compliance with Ethical Standards
The animals were supplied by the National Laboratory Animal Breeding and Research Center, Taipei, Taiwan, R.O.C. One animal was individually housed in an air-conditioned room (22 ± 2 °C) on a 12-h light/dark cycle (07:00–19:00 h light) and had free access to food and water. The use of animals has been approved by the Institutional Animal Care and Use Committee of Taipei Veterans General Hospital, Taipei, Taiwan, R.O.C. The approval number is IACUC2017-242. All experiments were performed in accordance with relevant guidelines and regulation.
Conflict of Interest
The authors declare that they have no conflicts of interest.
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