Effect of heat shock protein 27 on the cardiac dysfunction induced by endotoxemia

Objective To study the effects of heat shock proetin 27(Hsp27)on the cardiac dysfunction induced by endotoxemia.Method All experiments were performed in the geriatric lab of the First Affiliated Hospital Of Nanjing Medical University,and in the Animal Model Center of Nanjing University.The genotyping of the transgenic mice with cardiac-specific overexpression of Hsp27(Hsp27 Tg)was assayed by PCR and the expression of Hsp27 was determined by western blot.Hsp27 Tg and its wild type littermates(WT)were intraperitoneally injected with LPS(10 mg/kg),and 24 hours later,cardiac function was measured by echocardiography(n=6/group).The accumulated mice mortality was recorded within 70 hous after intraperitoneal injection of LPS(20mg/kg)(n=37/WT,n=27/Hsp27Tg).The NF-kB activity for cardiac-tissue samples was analyzed by electrophoretic mobility shift assay(ENSA)and for cell culture samples by dual-reporter gene assay(n=4/group).The comparison of multiple groups was performed by one-way analysis of variance(ANOVA),and comparison of two groups was performed by Scheffe-test.Survival curves were analyzed by the log-rank test.P＜0.05 wns considered to be significant.Results The high expression of Hsp27 exhibited in myocardium of Hsp27 Tg,whereas not in myocardium of WT.LPS significantly reduced the cardiac function both in Hsp27 Tg and WT.However,compaled with LPS-treated WT,cardiac function was more significantly improved as evidenced by the increases of EF by 27.33%and FS by 37.09%(P＜0.01 or P＜0.05).Seventy hours after LPS injection,the mortality was 11.11% in Hsp27 Tg and 37.84% in WT.Compared with WT,the survival rate of Hsp27 Tg significantly increased(P＜0.05).The NF-kB activation was significantly inhibited by Hsp27(P＜0.01 or P＜0.05).Conclusions The high cardiac-specific expression of Hsp27 significantly inhibits cardiac dysfunction induced by endotoxemia,and at the same time improve the survival rate.The mechanism may be connected with Hsp27 downregulating NF-kB-activation induced by LPS. Key words: Heat shock protein; Endotoxemia; Cardiac dysfunction; Mortality; Inflammation