22-oxacalcitriol protects myocardial ischemia-reperfusion injury by suppressing NF-κB/TNF-α pathway

MiR-495-3p depletion contributes to myocardial ischemia/reperfusion injury in cardiomyocytes by targeting TNC

Background

Tenascin-C (TNC) has been found to abnormally express in myocardial ischemia/reperfusion injury (MI/RI), but its effect on cardiomyocytes apoptosis is unknown and is worthy of investigation.

Methods

H9C2 cells were given hypoxia/reoxygenation (H/R) treatment to obtain the replica of MI/RI in vitro. The effect of H/R on viability, apoptosis and inflammation was studied by CCK-8 assay, flow cytometry, mitochondrial membrane potential (MMP) and Ca²⁺ measurements as well as enzyme linked immunosorbent assay. We applied bioinformatics analysis and luciferase reporter assay to screened and validated TNC-targeting miR-495-3p which was then mechanistically investigated by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. With the assistance of cell transfection, rescue assays were conducted.

Results

H9C2 cells showed diminished viability, accelerated apoptosis, elevated tumour necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β), and TNC overexpression in response to H/R induction, while silencing of TNC partially reversed the effect of H/R treatment on the H9C2 cells. TNC silencing reduced Ca²⁺ level and enhanced MMP level in the H/R-stimulated cells. MiR-495-3p targeted TNC and showed a low expression in the H/R-stimulated cells. The expression of TNC was negatively regulated by miR-495-3p. Inhibition of miR-495-3p repressed viability and MMP level, and facilitated apoptosis and levels of Ca²⁺, TNF-α and IL-1β in the H/R-stimulated cells. The effect of TNC silencing and miR-495-3p depletion on H/R-induced cardiomyocyte injury was mutually reversed in vitro.

Conclusion

MiR-495-3p targeted TNC to regulate the apoptosis and inflammation of cardiomyocytes in H/R induction, which was associated with Ca²⁺ overload.

L-Carnitine Reduces Myocardial Oxidative Stress and Alleviates Myocardial Ischemia-Reperfusion Injury by Activating Nuclear Transcription-Related Factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1) Signaling Pathway

Background

Myocardial ischemia-reperfusion injury (IRI) is an important injury mechanism of myocardial infarction. The purpose of this study was to explore the effects of L-carnitine (LC) on myocardial IRI and its mechanism.

Material/Methods

The IRI model was made by ligating the left anterior descending coronary artery. Then, we injected LC intraperitoneally into the rats of the experimental group to assess the effect of LC on IRI rats by use of serum markers, Western blot, and qRT-PCR. H9c2 cells were cultured and then treated with hypoxia-reoxygenation. The effect of LC on oxidative stress, apoptosis, and nuclear transcription-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway of H9c2 cells were detected by Western blot, RT-PCR, and flow cytometry.

Results

LC significantly reduced malondialdehyde (MDA), creatine kinase (CK), and lactate dehydrogenase (LDH) levels in rat myocardial tissue and increased superoxide dismutase (SOD) expression. LC also increased the expression of SOD1/2 and Bcl-2 in rat myocardial tissue and H9c2 cells and decreased the expression of caspase3/8 and Bax. In addition, LC increased the expression of Nrf2/HO-1 signaling pathway-related molecules in H9c2 cells and increased the activity of the Nrf2/HO-1 signaling pathway. Moreover, inhibition of the Nrf2/HO-1 signaling pathway attenuated the protective effect of LC on H9c2 cells.

Conclusions

LC can activate the Nrf2/HO-1 signaling pathway and reduce oxidative stress and apoptosis in cardiomyocytes, thereby reducing myocardial IRI.