TPNA10168, an Nrf2 activator, attenuates LPS-induced inflammation in microglia through modulation of MAPK and NF-κB pathways

The nuclear factor erythroid 2-related factor 2 (Nrf2)–antioxidant response element (ARE) pathway is a major cellular defense mechanism against oxidative stress through the induction of antioxidant proteins. Chemical inducers of Nrf2 often exhibit anti-inflammatory properties. TPNA10168, originally identified as an Nrf2–ARE activator, has previously been shown to attenuate interferon-γ-induced inflammatory responses in BV-2 microglial cells in an Nrf2-independent manner. However, its anti-inflammatory effects on primary microglia remain unclear. In this study, TPNA10168 significantly suppressed the lipopolysaccharide (LPS)-induced expression of inflammatory genes, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6, in primary microglia. The anti-inflammatory effects of TPNA10168 persisted even after Nrf2 knockdown. Mechanistic analysis revealed that TPNA10168 inhibited LPS-induced phosphorylation of extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and nuclear factor-κB (NF-κB) p65 without affecting NF-κB nuclear translocation. These findings indicate that TPNA10168 attenuates microglial activation by inhibiting proinflammatory signaling pathways, in part through Nrf2-independent pathways, and is a promising compound for modulating neuroinflammation.