High Mobility Group Box 1 Promotes Myocardial Damage And Influences CD4~+T,CD8~+T Cell And IL-17 Through Toll Like Receptor 4 In Ischemia Myocardial

Objective:C57BL/6 wild type（WT）mice and TLR4 knockout(TLR4^-/-)mice,and high-dose isoproterenol（ISO）was used to construct mouse acute MI model.（1）Changes of cardiac function,myocardial apoptosis,myocardial tissue necrosis,myocardial tissue fibrosisand,HMGB1 expression,CD4⁺T,CD8⁺T lymphocyte proportion and interleukin（IL）-17proportion in myocardial ischemia in mice were observed.（2）After administration of recombinant high mobility protein B1,the changes of cardiac function,myocardial apoptosis and CD4⁺T,CD8⁺T lymphocyte proportion and interleukin IL-17 proportion in myocardial ischemia were observed.Methods:（1）30 wild-type（WT）and 30 TLR4 knockout(TLR4^-/-)C57BL/6 mice were randomly divided into the control group,isoproterenol induced ischemia myocardial group（ISO）and ISO+rHMGB1 group.（2）This experiment used a mouse high-dose ISO（20mg/kg/day,continuous injection for seven days）to establish an acute myocardial ischemia model.WT mice and TLR4^-/-mice were randomly divided into the following groups of 10mice each.The Control group:intraperitoneal injection of 0.9%sodium chloride injection20mg/kg/day for 7 consecutive days;ISO group:20 mg/kg/day ISO for 7 consecutive days of intraperitoneal injection;ISO combination+HMGB1（recombinan HMGB1,rHMGB1）group:mice were given intraperitoneal injection of 10μg/kg of rHMGB1 12 h before induction of MI injury.（3）Cardiac function,myocardium histopathological changes and myocardial apoptosis index were evaluated by echocardiography,HE,sirius red staining,and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling（TUNEL）,Myocardial tissue HMGB1 was detected by immunohistochemistry.Flow cytometry was applied to detect the proportion CD4⁺T,CD8⁺T cells,and IL-17 of spleen.Results:（1）Compared to the control group,ISO group caused cardiac function impairment,myocardial tissue necrosis and fibrosis,cardiomyocyte apoptosis,increased expression of HMGB1,elavated CD4⁺T cells proportion and IL-17 proportion,and CD4⁺/CD8⁺ratio in vivo（P<0.05）.（2）Compared to the ISO group,ISO+rHMGB1 group had worse cardiac function,myocardial tissue necrosis and fibrosis,cardiomyocyte apoptosis,increased expression of HMGB1,higher CD4⁺T cells proportion and IL-17 proportion,and CD4⁺/CD8⁺ratio in vivo（P<0.05）.（3）Compared to the WT-ISO group,TLR4^-/--ISO group had better cardiac function,alleviative myocardial tissue necrosis and fibrosis,cardiomyocyte apoptosis,reduced proportion of HMGB1,lower CD4⁺T cells proportion and IL-17 proportion,and CD4⁺/CD8⁺ratio in vivo（P<0.05）.（4）Compared to the WT-ISO+rHMGB1 group,TLR4^-/--ISO+rHMGB1 group had better cardiac function,alleviative myocardial tissue necrosis and fibrosis,cardiomyocyte apoptosis,reduced expression of HMGB1,lower CD4⁺T cells proportion and IL-17 proportion,and CD4⁺/CD8⁺ratio in vivo（P<0.05）.Conclusion:1.rHMGB1 can aggravate myocardial ischemic injury through toll like receptor 4.2.During myocardial ischemia,the HMGB1/TLR4 signaling pathway may be involved in the regulation of CD4⁺T cells,CD8⁺T cells,and IL-17.