Toll-like receptor 7/8 agonist resiquimod induces late preconditioning in neonatal cardiac myocytes

• Published in: Acta pharmacologica Sinica 2011-05, Vol.32 (5), p.565-572
• Main Authors: Wang, Yong-yi, Liu, Sha, Lian, Feng, Yang, Wen-gang, Xue, Song
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Biomedical and Life Sciences; Biomedicine; Cardiotonic Agents - administration & dosage; Cardiotonic Agents - pharmacology; Cell Hypoxia; Dose-Response Relationship, Drug; Gene Knockdown Techniques; Hypoxia-Inducible Factor 1 - metabolism; Imidazoles - administration & dosage; Imidazoles - pharmacology; Immunology; Internal Medicine; Ischemic Preconditioning, Myocardial - methods; Medical Microbiology; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - pathology; NF-kappa B - metabolism; Nitric Oxide Synthase Type II - genetics; Original; original-article; Oxidative Stress - drug effects; Oxygen - administration & dosage; Pharmacology/Toxicology; Rats; Rats, Wistar; Reactive Oxygen Species - metabolism; Toll-Like Receptor 7 - agonists; Toll-Like Receptor 8 - agonists; Toll样受体; Vaccine; 心肌细胞; 新生儿; 核因子kappa; 活性氧清除剂; 激动剂; 诱导型一氧化氮合酶; 预处理
• ISSN: 1671-4083; 1745-7254
• DOI: 10.1038/aps.2011.6

Aim： To investigate whether R-848 （resiquimod, toll-like receptor 7/8 agonist） can induce late preconditioning in neonatal cardiac myocytes. Methods： The protective effects of R-848 on neonatal myocytes against anoxia-reoxygenation-induced injury were tested, and intracellular reactive oxygen species （ROS） were determined. The protein synthesis inhibitor cyclohexamide （CH） and the ROS scavenger N-acetylcysteine （NAC） were used in this model to test if new protein synthesis and oxidative stress were necessary for their cardioprotective effects. The activation of nuclear factor kappa B （NFKB） and hypoxia inducible factor 1 （HIF1） was investigated by electrophoretic mobility shift assays （EMSA）, and inducible nitric oxide synthase （iNOS） was assessed by immunoblotting. After iNOS was downregulated by small interfering RNA （siRNA） transfection, the cardioprotective effect was reassessed. Results： ROS were triggered soon after R-848 （0.01-1.0 pg/L） administration, however, the cardioprotective effect of which was induced 24 h later. This protection was abolished by CH or NAC pretreatment. NFKB and HIF1 activation and iNOS up-regulation were involved in this protective mechanism. The cardioprotective effect was also attenuated after iNOS was knocked down. Conclusion： R-848 provided a cardioprotective effect through a late preconditioning mechanism via a ROS/NFKB-HIF1/iNOS-dependent pathway.