RP105 alleviates myocardial ischemia reperfusion injury via inhibiting TLR4/TRIF signaling pathways

The Toll-like receptor 4 (TLR4) signal pathway-induced inflammation is considered to be a crucial link to myocardial ischemia reperfusion injury (MIRI). Our previous study proved that radioprotective 105 kDa protein (RP105), a negative regulator of TLR4, performed a protective role in MIRI by anti-apoptosis approach. However, the mechanism of RP105 cardioprotection of anti-inflammation is still unclear. This study aimed to explore the underlying mechanism of RP105 anti-inflammation effect in MIRI. We established a rat model of MIRI induced by ligation of the left anterior descending coronary artery for 30 min followed by 2 h reperfusion. Animals were pre-infected with Ad-EGFP-RP105, Ad-EGFP or saline at the apex of the heart. All rats were sacrificed to collect blood samples and myocardial tissue and assessed by immunofluorescence, blood biochemical analysis, Evans blue/triphenyltetrazolium chloride (TTC), hematoxylin and eosin (H&E) staining, enzyme-linked immuno sorbent assay (ELISA), western blot analysis, quantitative PCR and electrophoretic mobility shift assay (EMSA). RP105 overexpression with adenovirus vectors reduced serum myocardial enzyme (CK-MB and LDH) activities, decreased myocardial infarct size, mitigated inflammatory factors interferon-β and tumor necrosis factor-α during MIRI. We also found that Ad-RP105 group exerted distinct repression of TLR4/TRIF signal pathway related proteins and mRNAs (TRIF, TBK-1, IRF3 and p-IRF3) with a low transcriptional activity of IRF3. These findings first expounded that RP105 could alleviate the ischemia reperfusion induced inflammatory status in heart via inhibiting TLR4/TRIF signaling pathway and provided a theoretical foundation of RP105 gene in MIRI.