Hypoxia-inducible factor-1 in myocardial ischaemia/reperfusion injury

Integrating UPLC-Q-Exactive Orbitrap/MS, network pharmacology and experimental validation to reveal the potential mechanism of Tibetan medicine Rhodiola granules in improving myocardial ischemia-reperfusion injury

ETHNOPHARMACOLOGY RELEVANCE

Rhodiola granules (RG) is a traditional Tibetan medicine prescription that can be used to improve the symptoms of ischemia and hypoxia in cardiovascular and cerebrovascular diseases. However, there is no report on its use to improve myocardial ischemia/reperfusion (I/R) injury, and its potential active ingredients and mechanism against myocardial ischemia/reperfusion (I/R) injury remain unclear.

AIM OF THE STUDY

This study aimed to reveal the potential bioactive components and underlying pharmacological mechanisms of RG in improving myocardial I/R injury through a comprehensive strategy.

MATERIALS AND METHODS

UPLC-Q-Exactive Orbitrap/MS technology was used to analyze the chemical components of RG, the potential bioactive components and targets were tracked and predicted by the SwissADME and SwissTargetPrediction databases, and the core targets were predicted through the PPI network, as well the functions and pathways were determined by GO and KEGG analysis. In addition, the molecular docking and ligation of the anterior descending coronary artery-induced rat I/R models were experimentally validated.

RESULTS

A total of 37 ingredients were detected from RG, including nine flavones, ten flavonoid glycosides, one glycoside, eight organic acids, four amides, two nucleosides, one amino acid, and two other components. Among them, 15 chemical components, such as salidroside, morin, diosmetin, and gallic acid were identified as key active compounds. Ten core targets, including AKT1, VEGF, PTGS2, and STAT3, were discovered through the analysis of the PPI network constructed from 124 common potential targets. These possible targets were involved in the regulation of oxidative stress and HIF-1/VEGF/PI3K-Akt signaling pathways. Furthermore, molecular docking confirmed that the potential bioactive compounds in RG have good potential binding abilities to AKT1, VEGFA, PTGS2, STAT3, and HIF-1α proteins. Then, the animal experiments showed that RG could significantly improve the cardiac function of I/R rats, reduce the size of myocardial infarction, improve the myocardial structure, and reduce the degree of myocardial fibrosis, inflammatory cell infiltration, and myocardial cell apoptosis rate in I/R rats. In addition, we also found that RG could decrease the concentration of AGE, Ox-LDL, MDA, MPO, XOD, SDH, Ca²⁺, and ROS, and increase the concentration of Trx, TrxR1, SOD, T-AOC, NO, ATP, Na⁺k⁺-ATPase, Ca²⁺-ATPase, and CCO. Moreover, RG could significantly down-regulate the expressions of Bax, Cleaved-caspase3, HIF-1α, and PTGS2, as well up-regulate the expressions of Bcl-2, VEGFA, p-AKT1, and p-STAT3.

CONCLUSION

In summary, we revealed for the first time the potential active ingredients and mechanisms of RG for myocardial I/R injury therapy through a comprehensive research strategy. RG may synergistically improve myocardial I/R injury through anti-inflammatory, regulating energy metabolism, and oxidative stress, improving I/R-induced myocardial apoptosis, which may be related to the HIF-1/VEGF/PI3K-Akt signaling pathway. Our study provides new insights into the clinical application of RG and also provides a reference for the development and mechanism research of other Tibetan medicine compound preparations.

Alpha-lipoic acid impedes myocardial ischemia-reperfusion injury, myocardial apoptosis, and oxidative stress by regulating HMGB1 expression

BACKGROUND

Inflammation, oxidative stress, and apoptosis contribute to myocardial ischemia/reperfusion injury (I/RI). Alpha-lipoic acid (ALA) plays a critical role in I/RI by impeding apoptosis and inflammation. Here, we aimed to explore the underlying mechanisms of ALA after I/RI.

METHODS

The left anterior descending coronary artery (LAD) was ligated, and H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to establish an I/RI model. Prior to this, H9c2 cells and rats were treated using an appropriate amount of ALA. The cardiac function, inflammatory factors, and myocardial pathology were assessed in vitro. We detected cell viability, apoptosis, and oxidative stress-related factors in vivo. Moreover, proteins of the HMGB1/TLR4/NF-κB signaling pathway were detected both in vivo and in vitro.

RESULTS

We observed that ALA increased cell viability in vitro and decreased apoptosis in vitro and in vivo. ALA inhibited reactive oxygen species production, decreased malondialdehyde, and increased superoxide dismutase activity to resist oxidative stress in vitro. ALA also reduced the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) in vivo. ALA also suppressed the levels of the apoptotic protein, Bax, and increased the expression of the anti-apoptotic protein Bcl-2, in vitro and in vivo. Moreover, we observed that ALA significantly inhibited the cytoplasmic localization of HMGB1, which might attenuate MI/RI or H/R via HMGB1/TLR4/NF-κB pathway.

CONCLUSION

ALA regulates HMGB1 translocation and attenuates I/R via the HMGB1/TLR4/NF-κB signaling pathway, thus impeding apoptosis, oxidation, and inflammation, and might be a potential target for myocardial ischemia/reperfusion injury.

Epigallocatechin-3-gallate protects cardiomyocytes from hypoxia-reoxygenation damage via raising autophagy related 4C expression

Myocardial ischemia/reperfusion (I/R) injury is a serious issue during the therapy of myocardial infarction. Herein, we explored the beneficial influence of Epigallocatechin-3-gallate (EGCG) on hypoxia/reoxygenation (H/R)-stimulated cardiomyocyte H9c2 cells damage, along with possible internal molecular mechanism related autophagy related 4C (ATG4C). H9c2 cells were subjected to H/R stimulation and/or EGCG treatment. ATG4C mRNA expression was measured via q-PCR assay. ATG4C overexpression plasmid (OE-ATG4C) was transfected to arise ATG4C level. Cell viability, apoptosis, reactive oxygen species (ROS) production, ATP level were tested via CCK-8 assay, Annexin V-FITC/PI staining, DCFH-DA staining and ATP Assay Kit, respectively. Western blotting was performed to test Cleaved-caspase 3, Cleaved-caspase 9, cytochrome C, and LC3B protein levels. H/R stimulation resulted in H9c2 cell viability loss, promoted cell apoptosis, and ROS overproduction, as well as lowered ATP level in cells. EGCG treatment alleviated H/R-resulted H9c2 cell viability loss, cell apoptosis, ROS overproduction, and reduction of ATP level. Moreover, H/R stimulation reduced the ATG4C expression in H9c2 cells, while EGCG raised the ATG4C expression. Overexpression of ATG4C strengthened the beneficial influence of EGCG on H/R-stimulated H9c2 cell viability, apoptosis and ROS production. Besides, ATG4C overexpression weakened the H/R-stimulated H9c2 cell autophagy via reducing LC3B II/I expression. EGCG exerted beneficial influence on H/R-stimulated cardiomyocytes, which protected cardiomyocytes from H/R-stimulated viability loss, apoptosis, and ROS overproduction via enhancing ATG4C expression.

HIF‑1α in myocardial ischemia‑reperfusion injury (Review)

Myocardial ischemia-reperfusion injury (MIRI) is a severe injury to the ischemic myocardium following the recovery of blood flow. Currently, there is no effective treatment for MIRI in clinical practice. Over the past two decades, biological studies of hypoxia and hypoxia-inducible factor-1α (HIF-1α) have notably improved understanding of oxygen homeostasis. HIF-1α is an oxygen-sensitive transcription factor that mediates adaptive metabolic responses to hypoxia and serves a pivotal role in MIRI. In particular, previous studies have demonstrated that HIF-1α improves mitochondrial function, decreases cellular oxidative stress, activates cardioprotective signaling pathways and downstream protective genes and interacts with non-coding RNAs. The present review summarizes the roles and associated mechanisms of action of HIF-1α in MIRI. In addition, HIF-1α-associated MIRI intervention, including natural compounds, exosomes, ischemic preconditioning and ischemic post-processing are presented. The present review provides evidence for the roles of HIF-1α activation in MIRI and supports its use as a therapeutic target.

Uhrf1 regulates H3K9me2 modification of mTOR to inhibit the effect of autophagy in myocardial ischemia-reperfusion injury

The regulation of mTOR and the dimethylation of histone H3 on lysine 9 (H3K9me2) H3K9me2 by Uhrf1 and the mechanism of autophagy regulation in myocardial ischemia-reperfusion injury (MIRI) were studied in vivo and in vitro.

An in vitro I/R injury model was established using the primary mouse cardiomyocytes treated with H₂O₂. Subsequent analysis by qRT-PCR, western blot, and immunofluorescence indicated that overexpression of Uhrf1 significantly inhibited apoptosis of the H₂O₂-treated cardiomyocytes, reduced expression of apoptosis factors caspase-3 and Bax, and increased expression of apoptosis inhibitory factor Bcl-2. Furthermore, Uhrf1 was found to increase cardiomyocyte proliferation and promote the expression of mTOR, while the four expression peaks of H3K9me2 on the mTOR gene were inhibited by overexpression of Uhrf1. The expression of autophagy factors LC3, Beclin-1, and p-mTOR in Uhrf1-overexpressed cardiomyocytes was dramatically increased, and P62 expression was dramatically decreased. When an H3K9me2 inhibitor was added to the Uhrf1-knockdown cardiomyocytes, the expression of mTOR was increased, the expression of LC3, Beclin-1, and p-mTOR was decreased, and P62 expression was significantly increased.

In the present study, Uhrf1 exhibits a protective function in MIRI, reducing the apoptosis of cardiomyocytes while increasing their proliferation and viability.

Vascular endothelial growth factor regulation of endothelial nitric oxide synthase phosphorylation is involved in isoflurane cardiac preconditioning

Aims

Previous studies indicate that nitric oxide derived from endothelial nitric oxide synthase (eNOS) serves as both trigger and mediator in anaesthetic cardiac preconditioning. The mechanisms underlying regulation of eNOS by volatile anaesthetics have not been fully understood. Therefore, this study examined the role of vascular endothelial growth factor (VEGF) in isoflurane cardiac preconditioning.

Methods and results

Wistar rats underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion. Isoflurane given prior to ischaemia/reperfusion significantly decreased myocardial infarct size from 60 ± 1% in control to 40 ± 3% (n = 8 rats/group, P < 0.05). The beneficial effects of isoflurane were blocked by neutralizing antibody against VEGF (nVEGF). Coronary arterial endothelial cells (ECs) alone or together with cardiomyocytes (CMs) were subjected to hypoxia/reoxygenation injury. The expression of VEGF and eNOS was analysed by western blot, and nitric oxide was measured by ozone-based chemiluminescence. In co-cultured CMs and ECs, isoflurane administered before hypoxia/reoxygenation attenuated lactate dehydrogenase activity and increased the ratio of phosphorylated eNOS/eNOS and nitric oxide production. The protective effect of isoflurane on CMs was compromised by nVEGF and after VEGF in ECs was inhibited with hypoxia inducible factor-1α short hairpin RNA (shRNA). The negative effect of hypoxia inducible factor-1α shRNA was restored by recombinant VEGF.

Conclusion

Isoflurane cardiac preconditioning is associated with VEGF regulation of phosphorylation of eNOS and nitric oxide production.

Mst1: Function and Mechanism in Brain and Myocardial Ischemia Reperfusion Injury

Mammalian STE20-like kinase-1 (Mst1) is a generally expressed apoptosis-promoting kinase and a key bridgebuilder of apoptotic signaling in the etiology of tissue injury. Despite the fact that the biological function of Mst1 and its role in the cell's signalling network have yet to be determined, however, there is a lot of evidence that Mst1 plays an important role in cell death which results from tissue injury. Previous studies have shown that Mst1 is not only a target for some apoptosis- related molecules such as caspase 3 and P53, but also act as an activator of these proteinases to magnify apoptosis signal pathways. This article reviews the role of Mst1 in the signaling pathways which is related with the neuronal cell apoptosis or microglia activation following myocardial and brain injury. Therefore, this work contributes to better understanding of the pathological process of myocardial and brain injury.