Teprenone alleviates LPS-induced inflammatory response and cardiac dysfunction through E3 ubiquitin ligase CHIP
AIM:To explore the therapeutic effect of teprenone(geranylgeranylacetone,GGA)on lipopolysac-charide(LPS)-induced cardiac dysfunction and its mechanism.METHODS:(1)Eight-week-old male C57BL/6 wild-type mice and carboxyl terminus of heat shock protein 70(HSP70)-interacting protein(CHIP)gene knockout mice were randomly divided into control group,LPS group,LPS+GGA group and GGA group,with 8 mice in each group.The model was established by intraperitoneal injection of LPS(25 mg/kg),and 1 h after LPS stimulation,mice were given intraperito-neal injection of GGA(100 mg/kg).The technique of high-resolution ultrasonography system was used to evaluate the car-diac function of mice.The serum of mice from each group were collected to detect the levels of creatine kinase-MB(CK-MB)and lactate dehydrogenase(LDH).HE staining was performed to observe histological changes of cardiac tissues.ELISA was used to detect the levels of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in cardiac tissues.West-ern blot was used to detect the protein levels of HSP70,CHIP,karyopherin-α 2(KPNA2),myeloperoxidase(MPO),vas-cular cell adhesion molecule(VCAM),intercellular cell adhesion molecule(ICAM),and nuclear factor-κB(NF-κB)in cardiac tissues.(2)In vitro cell inflammation model was established using mouse myocardial cells HL-1 stimulated with LPS.ELISA was used to detect the levels of TNF-α and IL-6 in cell supernatants.Western blot was used to detect the pro-tein expression levels of HSP70,CHIP,and KPNA2 in myocardial cells.Immunofluorescence staining was performed to observe the content of nuclear NF-κB.RESULTS:(1)GGA effectively improved cardiac function of LPS-stimulated mice,significantly increased ejection fraction and left ventricular fractional shortening(P<0.01),reduced serum levels of CK-MB and LDH(P<0.01),and alleviated myocardial injury.(2)GGA significantly reduced the release of TNF-α and IL-6 caused by LPS(P<0.01),as well as nuclear translocation of NF-κB,decreased the levels of KPNA2,MPO,VCAM and ICAM in cardiac tissues,and increased the levels of HSP70 in cardiac tissues and cells(P<0.01).(3)In CHIP knockout myocardial cells and mice,GGA failed to inhibit LPS-induced inflammatory response and lost its effect on im-proving cardiac function.CONCLUSION:The protective effect of GGA against LPS-caused cardiac dysfunction of mice is related to increasing expression of HSP70 and promoting CHIP activation,which inhibits the translocation of NF-κB into nucleus and suppresses inflammatory factor release.CHIP knockout abolishes the effects of GGA on reducing LPS-induced inflammatory response and myocardial injury.
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