Kaempferol acts through mitogen‐activated protein kinases and protein kinase B/AKT to elicit protection in a model of neuroinflammation in BV2 microglial cells

Abstract

BACKGROUND AND PURPOSE Kaempferol, a dietary flavonoid and phyto‐oestrogen, is known to have anti‐inflammatory properties. Microglial activation has been implicated in various neurodegenerative diseases. Anti‐inflammatory effects of kaempferol and the underlying mechanisms were investigated by using LPS‐stimulated microglial BV2 cells. EXPERIMENTAL APPROACH Cell viability was measured using MTT and neutral red assays. elisa, Western blot, immunocytochemistry and electrophoretic mobility‐shift assay were used to analyse NO, PGE 2, TNF‐α and IL‐1β production, inducible NOS (iNOS), COX‐2 expression and the involvement of signalling pathways such as toll‐like receptor‐4 (TLR4), MAPK cascades, PKB (AKT) and NF‐κB. Accumulation of reaction oxygen species (ROS) was measured by nitroblue tetrazolium and 2′7′‐dichlorofluorescein diacetate assay. Matrix metalloproteinase activity was investigated by zymography and immunoblot assay. Phagocytotic activity was assessed by use of latex beads. KEY RESULTS Kaempferol significantly attenuated LPS‐induced NO, PGE 2, TNF‐α, IL‐1β and ROS production and phagocytosis in a concentration‐dependent manner. Kaempferol suppressed the expression of iNOS, COX‐2, MMP‐3 and blocked the TLR4 activation. Moreover, kaempferol inhibited LPS‐induced NF‐κB activation and p38 MAPK, JNK and AKT phosphorylation. CONCLUSION AND IMPLICATIONS Kaempferol was able to reduce LPS‐induced inflammatory mediators through the down‐regulation of TLR4, NF‐κB, p38 MAPK, JNK and AKT suggesting that kaempferol has therapeutic potential for the treatment of neuroinflammatory diseases.