Pinitol Prevents Lipopolysaccharide (LPS)-Induced Inflammatory Responses in BV2 Microglia Mediated by TREM2

Microglia-involved neuroinflammation in the central nervous system (CNS) has been shown to aggravate brain damage and is associated with the pathogenesis of various neurodegenerative diseases. Thus, suppression of microglial activity has the potential to be a strategy for the treatment of neurodegenerative diseases. Pinitol, a methylated product of D-chiro-inositol, has been used as a treatment for blood-sugar metabolism and as an anti-tumor agent via its anti-inflammatory effects in cancer. However, whether or not pinitol can inhibit microglia-associated neuroinflammation is still unknown. This study aims to determine the effects of pinitol on inflammatory responses in BV2 microglia induced by LPS. Here, we found that the presence of pinitol ameliorates LPS-induced oxidative stress by reducing the production of ROS. Pinitol suppresses the expression and secretion of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. Notably, pinitol prevents the production of NO and PGE2 by inhibiting the expression of iNOS and COX-2. Mechanistically, our findings demonstrate that pinitol inhibits the phosphorylation and degradation of IκBα and subsequent activation of NF-κB. Furthermore, we show that pinitol increases the expression of TREM2 in BV2 microglia, and silencing of TREM2 abolished the anti-inflammatory effects of pinitol. These findings suggest that TREM2 mediates the protective effects of pinitol against LPS in microglia. In summary, our results display that pinitol possesses a robust and beneficial effect against the LPS-induced inflammatory response in microglia.