Abstract
BackgroundMyocarditis, an inflammatory disease of the myocardium, is a serious hazard to human life due to the expansion of inflammatory lesions in the myocardium. The aim of this study was to investigate the role of hypoxia-inducible transcription factor (HIF)-1α and its inhibitor topotecan in the pathogenesis of myocarditis.MethodsH9c2 cardiomyoblasts was stimulated with lipopolysaccharide (LPS) to simulate myocarditis model in vitro. The levels of myocardial damage markers were determined using commercially available kits. Western blotting was used to evaluate HIF-1α expression after LPS challenge. Then, after HIF-1α silencing, the contents of inflammatory factors were determined with enzyme-linked immunosorbent assay (ELISA). Cell viability was tested by means of a cell counting kit-8 (CCK-8) assay. Cell apoptosis was assessed by flow cytometry, and the expression of apoptotic proteins was examined using western blot analysis. Subsequently, HIF-1α was overexpressed and topotecan was employed to treat H9c2 cells under LPS exposure condition. The biological functions were detected again.ResultsLPS significantly elevated the levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) and cardiac troponin-I (cTn-I) in supernatant of H9c2 cell lysates. Additionally, LPS led to the notably upregulated expression of HIF-1α. HIF-1α-knockdown markedly decreased the concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-8 compared with the LPS-induced group. Moreover, the cell viability was conspicuously enhanced and cell apoptotic ratio was remarkably reduced, accompanied by downregulated expression of Bax, Bim, caspase 3 and caspase 9 after HIF-1α silencing. Consistently, HIF-1α gain-of-function significantly promoted the production of inflammatory cytokines and cell apoptosis, which was partially counteracted by topotecan administration.ConclusionTo conclude, these findings demonstrated that HIF-1α inhibition by topotecan ameliorates LPS-induced myocarditis in vitro, providing a new approach in the treatment of myocarditis.
Highlights
Myocarditis, an inflammatory disease of the myocardium, is a serious hazard to human life due to the expansion of inflammatory lesions in the myocardium
We aimed to explore the roles of hypoxia-inducible transcription factor (HIF)-1α and topotecan in the inflammation and apoptosis of cardiomyocytes induced by LPS, which is an in vitro cell model to simulate myocarditis followed by Gram-negative bacterial infection
HIF‐1α is highly expressed in LPS‐stimulated H9c2 cells Subsequently, the expression of HIF-1α in H9c2 cells exposed to LPS was examined by means of reverse transcription-quantitative PCR (RT-qPCR)
Summary
Myocarditis, an inflammatory disease of the myocardium, is a serious hazard to human life due to the expansion of inflammatory lesions in the myocardium. The aim of this study was to investigate the role of hypoxia-inducible transcription factor (HIF)-1α and its inhibitor topotecan in the pathogenesis of myocarditis. Myocarditis, known as inflammatory cardiomyopathy, is a disease featured by the existence of inflammatory infiltrates in myocardial tissue in the clinic and histology with a wide range of symptoms in children and young adults [1]. Persistent myocarditis potentially contributes to the structural and functional abnormalities in cardiomyocytes, which is the leading cause of acute cardiac failure, dilated cardiomyopathy and sudden cardiac death [2]. Myocarditis is mainly induced by infectious and noninfectious factors, including bacterial infection, viral infection, drug reaction and autoimmune disease [3]. LPS is widely used to simulate myocardial cytotoxicity in a large number of studies on the pathogenesis of myocarditis [5, 6]
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