LLDT-8 protects against cerebral ischemia/reperfusion injury by suppressing post-stroke inflammation

(5R)-5-Hydroxytriptolide (LLDT-8), an analogue of triptolide, displays lower toxicity compared to triptolide and has comparable immunosuppressive effects. We investigated the anti-inflammatory and neuroprotective effects of LLDT-8 on cerebral ischemia/reperfusion injury. Nitric oxide production from microglia was assessed by measuring the nitrite concentration in the culture medium with Griess reagent. Microglial cells and ischemic brain tissues were examined for the expression of proinflammatory mediators by qPCR and western blot. Infarct volumes were assessed with TTC histology. The TLR4/NF-κB signaling pathway was analyzed with western blot and immunocytochemistry. LLDT-8 significantly reduced infarct sizes and expression of pro-inflammatory cytokines in the ischemic cortex. LLDT-8 inhibited NO release and expression of TNF-α, IL-1β and iNOS in BV-2 microglia and primary microglia treated with LPS. In addition, LLDT-8 suppressed expression of TLR4, degradation of IκBα and nuclear translocation of NF-κB. LLDT-8 exerted anti-inflammatory effects and protected against acute cerebral ischemia/reperfusion injury possibly by acting through the IκB/NF-κB cascade to suppress microglia-mediated neuroinflammation.