Resveratrol Reduces Amyloid Plaque Via Microglial Stabilization
Activation of microglia, the resident macrophages of the brain, around the amyloid plaques is a key hallmark of Alzheimer's disease (AD). Recent evidence in mouse models indicates that microglia are required for the neurodegenerative process of AD. Amyloid-β (Aβ) peptides, the core components of the amyloid plaques, can trigger microglial activation by interacting with several Toll-like receptors (TLRs), including TLR4. Here, we show that resveratrol, a natural polyphenol associated with anti-inflammatory effects and currently in clinical trials for AD, prevented the activation of murine RAW 264.7 macrophages and microglial BV-2 cells treated with the TLR4 ligand, lipopolysaccharide (LPS). Resveratrol preferentially inhibited NF-κB activation upon LPS stimulation by interfering with IKK and IκB phosphorylation, an effect that potently reduced the transcriptional stimulation of several NF-κB target genes, including TNF-α and IL-6. Consequently, downstream phosphorylation of STAT1 and STAT3 upon LPS stimulation was also inhibited by resveratrol. We found that resveratrol acted upstream in the activation cascade by interfering with TLR4 oligomerization upon receptor stimulation. Resveratrol treatment also prevented the pro-inflammatory effect of fibrillar Aβ on macrophages by potently inhibiting the effect of Aβ on IκB phosphorylation, activation of STAT1 and STAT3, and on TNF-α and IL-6 secretion. Importantly, orally administered resveratrol in a mouse model of cerebral amyloid deposition lowered microglial activation associated with cortical amyloid plaque formation. Together this work provides strong evidence that resveratrol has in vitro and in vivo anti-inflammatory effects against Aβ-triggered microglial activation. Further studies in cell culture systems showed that resveratrol acted via a mechanism involving the TLR4/NF-κB/STAT signaling cascade.
Capiralla H, Vingtdeux V, Zhao H, Sankowski R, Al-Abed Y, Davies P, Marambaud P. Resveratrol mitigates lipopolysaccharide- and Aβ-mediated microglial inflammation by inhibiting the TLR4/NF-κB/STAT signaling cascade. J Neurochem. 2011 November The Litwin-Zucker Research Center for the Study of Alzheimer's Disease The Laboratory of Medicinal Chemistry, The Feinstein Institute for Medical Research, Manhasset, NY, USA. The Department of Pathology, Albert Einstein College of Medicine, Bronx, NY, USA