Ethanol extracts of Cinnamomum migao H.W. Li attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways

Ethnopharmacological relevance: Cinnamomum migao H.W. Li, commonly known as migao (MG), is used in the Miao region of China for treating cardiovascular and cerebrovascular diseases, attributed to its detoxifying (Jiedu in Chinese), activating blood circulation (Huoxue in Chinese), and promoting Qi circulation (Tongqi in Chinese) properties. However, its therapeutic potential for ischemic stroke (IS) remains unexplored. Therefore, this study was to explore the protective effect of MG against cerebral ischemia-reperfusion injury caused by IS.

Aim of the study: The aim of this study was to investigate whether ethanol extract of MG (EEMG) attenuates cerebral ischemia-reperfusion injury, and explored the underlying mechanisms.

Materials and methods: Middle cerebral artery occlusion and reperfusion (MCAO/R) was established, and the efficacy of EEMG was evaluated using triphenyltetrazolium chloride (TTC), immunofluorescence, hematoxylin-eosin (HE) staining, and real-time quantitative PCR (qRT-PCR). Qualitative analysis of EEMG was analyzed for chemical composition by liquid chromatography-mass spectrometry (LC-MS). The molecular mechanism of EEMG was explored by metabolomics, network pharmacology, immunoblotting, immunofluorescence staining, gene knockdown, and agonist treatment.

Results: The results showed that EEMG alleviates ischemic injury in MCAO/R-operated rats and reduces neuronal damage of OGD/R-treated SH-SY5Y cells. Specifically, EEMG inhibited the release of inflammatory factors and reversed serum metabolic profile disorders of MCAO/R rats. Network pharmacology analysis showed that the PI3K-Akt and NF-κB signaling pathways play a role in the neuroprotective effects of EEMG against ischemic injury and in mitigating the inflammatory response. Consistent with our expectations, EEMG activated PI3K-AKT and suppressed NF-kB signaling pathways both in MCAO/R-operated rats and OGD/R-treated BV2 cells. The results showed that knockdown of TLR4 abolished the EEMG-mediated inhibition on neuroinflammation in OGD/R-treated BV2 cells. After treating BV2 cells with the TLR4 agonist neoseptin 3, EEMG showed a trend toward inhibiting neuroinflammation, though the effect was not statistically significant. Additionally, EEMG was found to improve liver injury caused by cerebral ischemia-reperfusion, which is associated with NF-κB signaling pathway in this study.

Conclusions: Collectively, this study demonstrated that EEMG attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways.