Role of heat shock protein 22 in the protective effect of geranylgeranylacetone in response to oxidized-LDL.

OBJECTIVE: The aim was to investigate the role and potential mechanism of geranylgeranylacetone (GGA) in the development of atherosclerosis, and to explore the role of heat shock protein 22 (HSP22) in mediating GGA effect. METHODS: Human coronary artery endothelial cell (HCAEC) was used for in vitro study. RNA interference was applied to suppress HSP22 in the cells. Cellular apoptosis and intracellular level of reactive oxygen species (ROS) were detected by flow cytometer, and proteins of HSP22, NF-κB, eNOS, and ICAM-1 were assessed by immunoblotting. HSP22-/-//ApoE-/-, and HSP22+/+//ApoE-/- mice were used to investigate the effect of GGA in the animal model of atherosclerosis. Atherosclerotic lesion of the mice aortas was evaluated by Oil Red O staining and H&E staining. RESULTS: GGA significantly inhibited HCAEC apoptosis in response to oxidized-LDL (ox-LDL), but stimulated HSP22 synthesis in the cells. Transfection of HSP22-siRNA in the cells resulted in complete blockage of the GGA effect on apoptosis. GGA also significantly inhibited ROS, NF-κB, and ICAM-1 in the cells transfected control siRNA, but not in the cells transfected with HSP22-siRNA. Atherosclerotic plaque in the aorta was significantly less in the wild type (WT) animals treated with GGA as stained either by Oil Red O or by H&E staining, but not in the HSP22-KO mice. GGA significantly inhibited expression of NF-κB and ICAM-1 in the WT mice, but not in the HSP22-KO mice. CONCLUSION: GGA-induced HSP22, and inhibited ox-LDL-induced apoptosis as well as expression of NF-κB and ICAM-1 in the HCAECs. GGA also attenuated formation of atherosclerotic plaques in mice aorta. Suppression of HSP22 by siRNA resulted in blockage of the GGA inhibition on apoptosis or stimulation on NF-κB and ICAM-1. These findings suggested that GGA protects endothelial cells from injury in response to ox-LDL and block atherosclerotic development in mice aorta through induction of HSP22.

Atorvastatin downregulates HSP22 expression in an atherosclerotic model in vitro and in vivo.

One of the pathological functions of heat shock protein 22 (HSP22) is the association with inflammatory diseases and atherosclerosis. However, the effects of a high­fat diet (HFD) or oxidized low­density lipoprotein (ox­LDL) combined with atorvastatin (ATV) on HSP22 expression are entirely unknown. The present study investigated the effects of ATV on HSP22 expression in HFD­induced atherosclerotic apolipoprotein E­deficient (ApoE­/­) mice and in ox­LDL­induced human umbilical vein endothelial cells (HUVECs). Furthermore, the influence of HSP22­knockdown on the HFD- or ox­LDL­induced atherosclerotic model was also examined. It was found that HFD or ox­LDL treatment significantly increased HSP22 expression in the serum and aorta, accompanied by decreased phosphorylated (p)­endothelial nitric oxide synthase (p-eNOS) activity and activated p38 mitogen­activated protein kinase (MAPK). However, these effects were suppressed by treatment with ATV. Furthermore, HSP22-knockdown showed reduced ox­LDL­induced lesions, evidenced by increased p­eNOS activity and inactivated p38 MAPK, while suppression of cell proliferation inhibition and cell cycle arrest were also observed. Taken together, the results of this study suggest that HFD or ox­LDL increased the expression of HSP22 and p­p38 MAPK, and decreased the p­eNOS activity in vitro and in vivo, and ATV could reduce the effects by downregulating HSP22 expression.

A network-based method for mechanistic investigation of Shexiang Baoxin Pill's treatment of cardiovascular diseases.

Shexiang Baoxin Pill (SBP), a traditional Chinese medicine formula, is commonly used to treat cardiovascular disease (CVD) in China. However, the complexity of composition and targets has deterred our understanding of its mechanism of action. Using network pharmacology-based approaches, we established the mechanism of action for SBP to treat CVD by analyzing protein-protein interactions and pathways. The computational results were confirmed at the gene expression level in microarray-based studies. Two of the SBP's targets were further confirmed at the protein level by Western blot. In addition, we validated the theory that SBP's plasma absorbed compounds play major therapeutic role in treating CVD.