Ganoderic Acids Alleviate Neuroinflammation by Targeting Myeloid Differentiation Factor 2 for Ischemic Stroke Therapy

Neuroinflammation plays a critical role in cerebral ischemic injury, making it an important therapeutic target for stroke treatment. Ganoderic acids (GAs), the primary bioactive compounds isolated from Ganoderma lucidum, exhibit well-demonstrated anti-inflammatory properties. This study aimed to investigate the neuroprotective potential of GAs in the context of ischemic stroke. Mice subjected to transient middle cerebral artery occlusion (tMCAO) served as an in vivo model of focal cerebral ischemia, while LPS-treated microglial cells were utilized as an in vitro model to evaluate microglial activation. GAs treatment significantly alleviated cerebral ischemic injury, inhibited microglial overactivation, and decreased inflammatory cytokine expression in both in vitro and in vivo models. Mechanistically, eight principal monomers in GAs, particularly GA-K, were found to target myeloid differentiation protein 2 (MD2), thereby preventing its interaction with Toll-like Receptor 4 (TLR4), and subsequently inhibiting MAPK and NF-κB pathways. MD2 was found to be overexpressed under ischemic conditions. In MD2-deficient mice, microglial activation was inhibited, and neuroprotection against ischemic injury was observed, unaffected by GAs. These findings suggest that GAs, particularly GA-K, provide neuroprotection in ischemic stroke by modulating microglia-mediated neuroinflammation through MD2, which may serve as a promising therapeutic target for stroke patients.