Ethanol extract of propolis protects macrophages from oxidized low-den-sity lipoprotein-induced apoptosis by inhibiting caspase-12 / 中国病理生理杂志

ABSTRACT

AIM:To investigate the inhibitory effect of ethanol extract of propolis (EEP) on oxidized low-den-sity lipoprotein ( ox-LDL )-induced macrophage apoptosis and the underlying molecular mechanisms . METHODS:RAW264.7 macrophages were pretreated with EEP (7.5, 15 and 30 mg/L), 4-phenylbutyric acid (PBA, 5 mmol/L) or diphenyleneiodonium ( DPI, 5μmol/L) for 1 h and then treated with ox-LDL (100 mg/L) or tunicamycin ( TM, 4 mg/L) for 24 h.The cell viability and apoptosis were determined by MTT assay and Annexin V-FITC apoptosis detection kit , re-spectively.The activity of superoxide dismutase (SOD), and the levels of reactive oxygen species (ROS) and malondial-dehyde (MDA) in the cells were measured.The protein levels of caspase-12, a proapoptotic molecule under endoplasmic reticulum stress ( ERS) , were examined by Western blot analysis .RESULTS:Like PBA ( an ERS inhibitor ) , EEP pro-tected RAW264.7 macrophages from ox-LDL-induced injury in a dose-dependent manner , as assessed by the increased cell viability and the decreased apoptotic rate .The decrease in cell viability and increase in apoptotic rate induced by TM , an ERS inducer, were also attenuated by EEP .Moreover, EEP suppressed ox-LDL-induced oxidative stress as revealed by the decreased generation of ROS and MDA as well as elevated SOD activity , which were similar to DPI , an oxidative stress in-hibitor.Furthermore, EEP significantly suppressed ox-LDL-or TM-induced activation of caspase-12.Similar results were observed in the cells pretreated with PBA or DPI and then treated with ox-LDL.CONCLUSION: EEP may protect RAW264.7 macrophages from ox-LDL-induced apoptosis and the mechanism is at least partially involved in the ability of EEP to suppress oxidative stress and subsequent activation of caspase -12.