Background: Spermidine, a naturally occurring polyamine, displays a wide variety of internal biological activities including cell growth and proliferation. However, the molecular mechanisms responsible for its anti-inflammatory activity have not yet been elucidated.
Methods: The anti-inflammatory properties of spermidine were studied using lipopolysaccharide (LPS)-stimulated murine BV2 microglia model. As inflammatory parameters, the production of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin (IL)-6 and tumor necrosis factor (TNF)-α were evaluated. We also examined the spermidine's effect on the activity of nuclear factor-kappaB (NF-κB), and the phosphoinositide 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs) pathways.
Results: Pretreatment with spermidine prior to LPS treatment significantly inhibited excessive production of NO and PGE2 in a dose-dependent manner, and was associated with down-regulation of expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Spermidine treatment also attenuated the production of pro-inflammatory cytokines, including IL-6 and TNF-α, by suppressing their mRNA expressions. The mechanism underlying spermidine-mediated attenuation of inflammation in BV2 cells appeared to involve the suppression of translocation of NF-κB p65 subunit into the nucleus, and the phosphorylation of Akt and MAPKs.
Conclusions: The results indicate that spermidine appears to inhibit inflammation stimulated by LPS by blocking the NF-κB, PI3K/Akt and MAPKs signaling pathways in microglia.