As a bioactive absorbed compound of rhubarb,
Rhein is applied for the treatment of
brain injury. However, the underlying pharmacological mechanisms remain unclear. In this study, we aimed to explore antineuroinflammatory functions and underlying mechanisms of
Rhein in vitro. BV2 microglia cells were chosen and irritated by LPS. The influence of
Rhein on cell viability was determined using MTT assay. We finely gauged the proinflammatory
cytokines of TNF-α and IL-1β through tests of immunofluorescence staining, ELISA, RT-qPCR, and western blot. Additionally, mediators including
IL-6,
IL-12, iNOS, and
IL-10 were surveyed by ELISA. Furthermore,
protein levels of the underlying signaling pathways (PI3K/Akt, p38, ERK1/2, and TLR4/NF-κB) were tested adopting western blot. We found that
Rhein reduced the secretion of pivotal indicators including TNF-α and IL-1β, effectively restraining their
mRNA and
protein expression in LPS-activated BV2 microglial cells. Besides,
Rhein treatment demoted the production of
IL-6,
IL-12, and iNOS and promoted the excretion of
IL-10. Subsequent mechanistic experiments revealed that
Rhein obviously downregulated the phosphorylation levels of PI3K, Akt, p38, and ERK1/2 and simultaneously upregulated the PTEN expression. In addition,
Rhein antagonized the increase of TLR4, p-IκBα, and NF-κB. In summary,
Rhein suppresses
neuroinflammation via multiple signaling pathways (PI3K/Akt, p38, ERK1/2, and TLR4/NF-κB) in LPS-stimulated BV2 microglia cells. This study highlights a natural agent for prevention and treatment of
neuroinflammation.