Neuroinflammation is a fundamental feature in the pathogenesis of amyotrophic lateral sclerosis (ALS) and arises from the activation of astrocytes and microglial cells. Previously, we reported that Miyako Bidens pilosa extract (MBP) inhibited microglial activation and prolonged the life span in a human ALS-linked mutant superoxide dismutase-1 (SOD1G93A) transgenic mouse model of ALS (G93A mice). Herein, we evaluated the effect of MBP on microglial activation in the spinal cord of G93A mice and lipopolysaccharide-stimulated BV-2 microglial cells. The administration of MBP inhibited the upregulation of the M1-microglia/macrophage marker (interferon-γ receptor (IFN-γR)) and pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6) in G93A mice. However, MBP did not affect the increase in the M2-microglia/macrophage marker (IL-13R) and anti-inflammatory cytokines (transforming growth factor (TGF)-β and IL-10) in G93A mice. BV-2 cell exposure to MBP resulted in a decrease in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) reduction activity and bromodeoxyuridine incorporation, without an increase in the number of ethidium homodimer-1-stained dead cells. Moreover, MBP suppressed the production of lipopolysaccharide-induced pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in BV-2 cells. These results suggest that the selective suppression of M1-related pro-inflammatory cytokines is involved in the therapeutic potential of MBP in ALS model mice.
Keywords: Bidens pilosa; M1-microglia/macrophages; amyotrophic lateral sclerosis; pro-inflammatory cytokines; spinal cord.