Paeoniflorin attenuates Aβ1-42-induced inflammation and chemotaxis of microglia in vitro and inhibits NF-κB- and VEGF/Flt-1 signaling pathways

Abstract Alzheimer׳s disease (AD) is a neurodegenerative disease with elusive pathogenesis, which accounts for most cases of dementia in the aged population. It has been reported that persistent inflammatory responses and excessive chemotaxis of microglia stimulated by beta-amyloid (Aβ) oligomers in the brain may accelerate the progression of AD. The present study was conducted to explore whether paeoniflorin (PF), a water-soluble monoterpene glycoside isolated from the root of Paeonia lactiflora Pallas , could attenuate Aβ 1-42 -induced toxic effects on primary and BV-2 microglial cells in vitro . Our data showed that PF pretreatment inhibited Aβ 1-42 -induced production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in rodent microglia. Also, the nuclear translocation of nuclear factor kappa B (NF-κB) subunit p65 and the phosphorylation of NF-κB inhibitor alpha (IκBα) in Aβ 1-42 -stimulated microglial cells were suppressed by PF administration. Moreover, PF treatment reduced the release of chemokine (C–X–C motif) ligand 1 (CXCL1) and chemokine (C–C motif) ligand 2 (CCL-2) from Aβ 1-42 -stimulated microglia. Additionally, application of PF inhibited the increases in vascular endothelial growth factor (VEGF) and VEGF receptor 1 (Flt-1) triggered by Aβ 1-42 , and resulted in a concomitant reduction in microglial chemotaxis. Restoration of VEGF was noted to counteract the inhibitory effect of PF, suggesting that PF mitigated Aβ 1-42 -elicited microglial migration at least partly by suppressing the VEGF/Flt-1 axis. In summary, in presence of Aβ 1-42 , PF pretreatment inhibited the excessive microglial activation and chemotaxis.