Effects Of Toll-like Receptor 4 Gene Knockout On CD20~+ Cells And CD68~+ Cells In Myocardial Ischemia

Objective:Mice with toll-like receptor 4（TLR4）gene knockout and C57BL/6 wild-type mice were injected with isoprenaline to establish a myocardial ischemia model to observe whether TLR4gene knockout has certain protection against myocardial ischemia induced by ISO,and to explore the possibile mechanism of TLR4.Methods:20 C57BL/6 male mice and 20 TLR4 gene knockout male mice were randomly divided into the blank control group（NC）,myocardial ischemia group（MI）,TLR4^-/-control group(TLR4^-/-NC)and TLR4^-/-myocardial ischemia group(TLR4^-/-MI)with 10 mice in each group.The control group received intraperitoneal injection of 20mg/kg normal saline（NC）for 7 days.And the myocardial ischemia group also received intraperitoneal injection of 20mg/kg isoproterenol（ISO）for 7 days to established the myocardial ischemia model.After the MI model builded,the ejection fraction（EF）and left ventricular fractional shortening（LVFS）were mearsured by the cardiac ultrasound.The myocardial pathological change was observed by Hematoxylin-eosin（HE）staining and Sirius red staining.The level of apoptosis in myocardial tissue was detected by the method of terminal deoxynucleotidyl transferase dUTP nick end labeling（TUNEL）.And the content of CD20⁺cells and CD68⁺cells in spleen were detected by the flow cytometry（FCM）.Results:（1）Compared with the NC group,the myocardial injury,fibrosis and apoptosis in the MI group were aggravated,and the cardiac function was decreased.Compared with the MI group,the myocardial tissue injury,fibrosis and apoptosis degree of the TLR4^-/-MI group were decreased,and the cardiac function damage was reduced.（2）Compared with the NC group,the contents of CD20⁺cells and CD68⁺cells in the spleen of the MI group were increased（P<0.05）.Compared with MI group,the contents of CD20⁺cells and CD68⁺cells in the spleens of TLR4^-/-MI group were decreased（P<0.05）.Conclusions:TLR4 gene knockout has a protective effect on myocardial ischemia induced by ISO in mice.The effect of TLR4 on myocardial ischemia may be achieved by regulating CD20⁺cells and CD68⁺cells.