In Vitro Anti-Inflammatory Effects of Phenolic Compounds from Moraiolo Virgin Olive Oil (MVOO) in Brain Cells via Regulating the TLR4/NLRP3 Axis

Abstract

Neuroinflammation is a feature of many classic neurodegenerative diseases. In the healthy brain, microglia cells are distributed throughout the brain and are constantly surveilling the central nervous system (CNS). In response to CNS injury, microglia quickly react by secreting a wide array of apoptotic molecules. Virgin olive oil (VOO) is universally recognized as a symbol of the Mediterranean diet. In the current study, using lipopolysaccharide (LPS)-stimulated BV2 microglia, the anti-inflammatory effects of VOO phenolic extracts from Moraiolo cultivar (MVOO-PE) were investigated. The results showed that low concentration of MVOO-PE prevented microglia cell death and attenuated the LPS-induced activation of toll-like receptor 4 (TLR4)/NOD-like receptor pyrin domain-containing-3 (NLRP3) signaling cascade. The levels of TLR4 and NF-kB were diminished, as well as NLRP3 inflammasome and interleukin-1β (IL-1β) production. Cyclooxygenase-2 (COX-2) isoenzyme and ionized calcium binding adaptor molecule 1 (Iba-1) inflammatory mediator were also reduced. By modulating the TLR4/NLRP3 axis, MVOO-PE pretreatment was able to significantly down-regulate the mRNA expression of inflammatory mediators and suppress the cytokine secretion. Finally, we showed protective effect of MVOO-PE in a transwell neuron–microglia co-culture system. In conclusion, these results suggest that MVOO-PE could exerts anti-inflammatory activity on brain cells and become a promising candidate for preventing several neuroinflammatory diseases.