Tiliroside Produced Anti-Neuroinflammatory Effects Through Interference With NF-κB And MAPK Signalling In LPS+ IFN-γ Stimulated BV-2 Microglia.

Tiliroside is a glycosidic flavonoid, which possesses anti-inflammatory,
antioxidant, anticarcinogenic and hepatoprotective activities. It is contained in
several dietary plants like linden, rosehip, raspberry and strawberry [1, 2]. In this
study the effects of tiliroside on the production of prostaglandin E2 (PGE2) and
nitric oxide (NO) from LPS+ IFN-γ stimulated BV-2 microglia as well as its
interference with NF-κB and MAP kinase signaling cascades were
investigated.BV-2 cells were stimulated with LPS (100ng/ml) and IFN-γ (5ng/ml)
in the presence or absence of tiliroside (2-6µM). After 24 hours, supernatants were
collected to measure PGE2 and NO production. MTT assay was used to determine
the effect of tiliroside on BV-2 microglia viability. Cyclooxygenase-2 (COX-2)
and inducible nitric oxide synthase (iNOS) protein expressions were evaluated in
LPS+ IFN-γ activated BV-2 microglia by western blot. NF-κB transcriptional
activity was evaluated using the luciferase reporter gene assay. Protein expressions
of phosphorylated IκB, IKK, p38 and MAPKAPK2 in the presence or absence of
tiliroside were evaluated using western blots after one hour stimulation with LPS
(100ng/ml) and IFN-γ (5ng/ml). Tiliroside (2-6µM) dose dependently (p<0.05)
inhibited PGE2 and NO production without effecting viability of BV-2 cells.
Tiliroside (6µM) caused a significant (p<0.05) inhibition of COX-2 expression by
27±4.3% and iNOS protein expression by 60.3±1.2% compared to LPS+ IFN-γ
control. Further experiments revealed significant (p<0.05) inhibition of nuclear
translocation of activated NF-κB by 26.3±3.1% with 6µM tiliroside. The
compound (6µM) produced significant (p<0.05) inhibition of IκB and IKK
phosphorylation by 51.9±3% and 54.9±4.1%. At 6µM, tiliroside significantly
(p<0.05) inhibited p38 phosphorylation by 65.8±2%. Further, tiliroside (6µM)
inhibited MAPKAPK2 phosphorylation by 39.9±1%. Taken together, these results
suggest that tiliroside suppresses neu