Resistance of C57BL/6 Mice to Different Artemisinin-sensitive Strains of PbK173 / 中国实验方剂学杂志

ObjectiveThe tolerance of C57BL/6 mice to artemisinin-sensitive and -resistant strains of Plasmodium berghei （Pb） K173 and the differences in blood parameters， spleen coefficient and spleen structure during infection were compared to explore whether the artemisinin resistance of Pb would aggravate malaria infection. MethodPbK173 artemisinin-sensitive and -resistant strains were tested in parallel. C57BL/6 mice were randomly divided into 1 control group， 4 artemisinin-sensitive strain groups and 4 artemisinin-resistant strain groups by body weight. Each infection group was simultaneously inoculated （ip） with 1×107 infected red blood cells （iRBCs） of sensitive/resistant strain. For the mice in the survival test group， the body weight was recorded every day post infection， and the tail vein blood smear was collected to calculate the Pb infection rate. In the other infection groups， peripheral blood and spleen were collected on 2， 5 and 9 d after infection. Peripheral blood parameters， spleen coefficient， pathological section of spleen and spleen cells were detected in each group. ResultOn 1-3 d after infection， the infection rate of the resistant strain （0.4±0.0， 0.8±0.1， 1.9±0.4）% was always higher than that of the sensitive strain （0.2±0.1， 0.4±0.1， 1.1±0.3）% （P<0.01）. From the 4th d of infection， the infection rate of the two groups gradually approached. The survival period of the sensitive strain group （20.5±1.2） d was shorter than that of the resistant strain group （23.3±1.4） d （P<0.01）. On the 9th d， the white blood cell count of the sensitive strain group （16.2±1.1）×109 cells/L was higher than that of the resistant strain group （10.6±1.8）×109 cells/L （P<0.01）. Flow cytometry analysis of spleen cells showed that the sensitive strain group （3.6±0.4） demonstrated a higher CD4+/CD8+ value than the resistant strain group （2.3±0.2） on the 9th d （P<0.01）. The spleen of C57BL/6 infected mice was gradually enlarged during infection， and on the 9th d， the resistant strain group （3.1±0.1）% showed a higher spleen coefficient than the sensitive strain group （2.7±0.2）% （P<0.01）. In the early stage of C57BL/6 infected mice， the red pulp of spleen was hyperemic and swollen. On the 9th d， the marginal area of the spleen disappeared and the structure of the red and white pulp was destroyed. ConclusionWithout drug treatment， the protective immune responses of peripheral blood and spleen of C57BL/6 mice were more sensitive to PbK173 artemisinin-sensitive strain. The artemisinin-resistant strain of PbK173 bred with mouse-to-mouse blood transmission and increased artemisinin dose exhibited shortened growth period and reduced toxicity.

Effect of Dihydroartemisinin on Oxidative Damage and Energy Metabolism of HepG2 Cells and Its Synergistic Effect with Sorafenib / 中国实验方剂学杂志

Objective:To explore the inhibitory effect of dihydroartemisinin （DHA） on the proliferation of HepG2 cells， elucidate the mechanism from the perspectives of oxidative damage and energy metabolism， and discuss the possibility of combined use of DHA with sorafenib （Sora）. Method:Cell counting kit-8 （CCK-8） assay was used to obtain the 50% inhibitory concentration （IC₅₀） of DHA and Sora on HepG2 and SW480 cells and Chou-Talalay method was used to obtain the combination index （CI） of DHA and Sora. HepG2 cells were classified into the control group， DHA group （10 µmol·L^-1）， Sora group （5 µmol·L^-1）， and DHA + Sora group （DHA 10 µmol·L^-1， Sora 5 µmol·L^-1） and then incubated with corresponding drugs for 8-12 h. Seahorse XF glycolytic rate assay kit and cell mito stress test kit were employed to respectively detect the glycolysis function of cells and oxidative phosphorylation function of mitochondria. DCFH-DA and lipid peroxidation MDA assay kit were separately used to analyze the intracellular levels of reactive oxygen species （ROS） and malondialdehyde （MDA）. Western blot was applied to determine the intracellular levels of heme oxygenase-1 （HO-1） and glutamate-cysteine ligase catalytic subunit （GCLC）. Result:Compared with the control group， DHA alone inhibited the ATP synthesis in mitochondrial oxidative phosphorylation and glycolysis （<italic>P</italic><0.01）， increased the levels of intracellular ROS and MDA （<italic>P<</italic>0.05）， and decreased the levels of HO-1 and GCLC （<italic>P<</italic>0.05） in HepG2 cells. DHA and Sora had synergistic inhibitory effect on proliferation of HepG2 and SW480 cells， with CI < 0.90. The DHA + Sora group showed stronger suppression of ATP synthesis in mitochondrial oxidative phosphorylation and glycolysis （<italic>P</italic><0.01）， higher levels of intracellular ROS and MDA （<italic>P<</italic>0.01）， and lower levels of intracellular antioxidation-related proteins HO-1 and GCLC in HepG2 cells （<italic>P<</italic>0.01） than the DHA group. Conclusion:DHA may increase the level of MDA by reducing HO-1 and GCLC and increasing ROS in HepG2 cells， which results in mitochondria oxidative damage， restricts cell glycolysis and mitochondrial oxidative phosphorylation， and thus finally inhibits the proliferation of HepG2 cells. DHA and Sora have synergistic inhibitory effect on the proliferation of HepG2 and SW480 cells， and the mechanism may be related to the synergistic oxidative damage that affects the mitochondrial electron transport chain and suppresses cell energy metabolism.