Uncovering the Metabolic Mechanism of Salidroside AlleviatingMicroglial Hypoxia Inflammation Based on Microfluidic Chip-MassSpectrometry

Microglia are the main immune cells in the brain playing a critical rolein neuroinflammation, and numerous pieces of evidence have proved that energymetabolism is closely associated with inflammation in activated microglia. Salidroside(Sal) isolated from Tibetan medicineRhodiola crenulatecan inhibit microglialhypoxia inflammation (HI). However, whether the inhibition is due to theintervening energy metabolic process in microglia is not clear. In this work, thehypoxic microenvironment of BV2 microglial cells was simulated using deferoxamine(DFO)in vitroand the change of cell metabolites (lactate, succinate, malate, andfumarate) was real-time online investigated based on a cell microfluidic chip-massspectrometry (CM-MS) system. Meanwhile, for confirming the metabolic mechanismof BV2 cells under hypoxia, the level of HI-related factors (LDH, ROS, HIF-1 alpha, NF-Kappa B p65, TNF-alpha, IL-1 beta, and IL-6) was detected by molecular biotechnology.Integration of the detected results revealed that DFO-induced BV2 cell HI wasassociated with the process of energy metabolism, in which cell energy metabolismchanged from oxidative phosphorylation to glycolysis. Furthermore, administration of Sal treatment could effectively invert thischange, and two metabolites of Sal were identified: tyrosol and 4-hydroxyphenylacetic acid. In general, we illustrated a newmechanism of Sal for reducing BV2 cell HI injury and presented a novel analysis strategy that opened a way for real-time onlinemonitoring of the energy metabolic mechanism of the effect of drugs on cells and further provided a superior strategy to screennatural drug candidates for HI-related brain disease treatment.

Automated summary

This study elucidated a new mechanism of Salidroside in reducing hypoxia-induced inflammation in microglia by regulating cellular energy metabolism. The hypoxic microenvironment of BV2 microglial cells was simulated in vitro using a cell microfluidic chip-mass spectrometry (CM-MS) system, and the real-time change of cell metabolites was investigated. The levels of hypoxia-related factors were also detected to confirm the metabolic mechanism of BV2 cells under hypoxia. The study found that Salidroside could invert the changes in cellular energy metabolism and identified two metabolites of Salidroside.