The protective effect of Luteolin on myocardial ischemia/reperfusion (I/R) injury through TLR4/NF-κB/NLRP3 inflammasome pathway

The purpose of the present study was to investigate the effect of Luteolin(Lut) on myocardial ischemia reperfusion injury and explore the underlying mechanism. Myocardial ischemia reperfusion injury (I/R) model was induced with 30min of left anterior descending (LAD) occlusion followed by 24h of reperfusion. In vivo, the rats were randomly divided into 5 groups: (1)Sham, (2)I/R, (3)I/R+Lut(40mg/kg), (4)I/R+Lut(80mg/kg) and (5)I/R+Lut(160mg/kg). In vitro, the H9c2 cells were assigned to five groups: (1)control, (2)hypoxia-reoxygenation(H/R), (3)H/R+Lut(5μM), (4)H/R+Lut(10μM) and (5)H/R+Lut(20μM). The H9c2 cells were stimulated with H/R protocol in the presence or absence of TAK-242, a TLR4 inhibitor. As a result, Lut ameliorated myocardial ischemia reperfusion injury and hypoxia-reoxygenation as evidenced by triphenyl tetrazolium chloride (TTC) staining and MTT assay, respectively. Lut was founded to decrease the levels of aspartate transaminase(AST), creatine phosphokinase-isoenzyme (CK-MB) and lactate dehydrogenase (LDH) in serum. Moreover, Lut could reduce the contents of interleukin-1β(IL-1β), interleukin-18 (IL-18) and tumor necrosis factor-α (TNF-α) in serum of rats and supernant of H9c2 cells. In addition, Lut remarkably downregulated the expressions of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and nuclear factor kappa B (NF-κB). Lut also inhibited the upregulations of inflammasome components, such as NOD-like receptor 3(NLRP3), apoptosis-associated speck-like protein containing CARD(ASC) in I/R-induced rats and H/R-induced H9c2 cells. In conclusion, Lut exhibited strong favorable cardioprotective effect on myocardial I/R injury which might be related to the down-regulation of the TLR4-meidated NF-κB/NLRP3 inflammasome in vivo and in vitro.