Rapamycin protects against myocardial ischemia-reperfusion injury through JAK2-STAT3 signaling pathway

Xiaoxuming decoction enhanced neuroprotection after cerebral ischemia/reperfusion via the JAK2/STAT3 signaling pathway based on UPLC/HRMS, network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Xiao-xu-ming decoction (XXMD), a prominent traditional Chinese medicinal formula historically revered for stroke treatment, demonstrates pronounced efficacy in ameliorating ischemic stroke injury.

AIM OF THE STUDY

This study aims to investigate the effects and mechanisms of XXMD on neuroprotection subsequent to cerebral ischemia/reperfusion in vivo and in vitro.

MATERIALS AND METHODS

Neurobehavioral test, TTC staining, HE staining and nissl staining were used to examine the neuroprotective effect of XXMD on cerebral ischemia-reperfusion injury induced by middle cerebral artery occlusion (MCAO) in rats. Additionally, we assessed cell viability and injury with CCK8 and lactate dehydrogenase (LDH) assays. The changes in neuronal ultra-structure were observed after oxygen-glucose deprivation and reoxygenation (OGD/R) by transmission electron microscopy (TEM). Network analysis combined with ultrahighperformance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) predicted the mechanism of XXMD on ischemic stroke injury. Furthermore, the expression of neuroplasticity-related proteins neurofilament 200 (NF200), microtubule-associated protein 2 (MAP2), postsynaptic density protein 95 (PSD95), synaptophysin (SYN), phosphorylated Janus kinase2 (p-JAK2), and phosphorylated signal transduction and activator of transcription 3 (p-STAT3) was evaluated by immunofluorescence staining and Western blot analyses.

RESULTS

XXMD significantly improved Ethology, infarct area and pathological changes after MCAO and reperfusion, reducing morphological and ultrastructural alterations and decreased cell viability in HT22 cells induced by OGD/R. Network pharmacology showed that 1153 compounds of XXMD were matched. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that XXMD treated ischemia stroke mainly regulating inflammation reaction-related signaling pathways, atherosclerosish-related signaling pathways. Molecular docking results showed that TP53, AKT1, STAT3, and IL6 are closely bound to the corresponding active ingredients. XXMD treatment significantly reversed the above alternations. XXMD or AG490 up-regulated the expression of neuroplasticity-associated proteins, and reduced phosphorylation of JAK2, STAT3 expression following OGD/R.

CONCLUSION

XXMD exerts neuroprotective effects by promoting neural plasticity via regulating the JAK2/STAT3 pathway, indicating a promising alternative therapeutic strategy for ischemic stroke.

Integrated serum pharmacochemistry with network pharmacology and pharmacological validation to elucidate the mechanism of yiqitongmai decoction (YQTMD) against myocardial infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Yiqitongmai decoction (YQTMD), a classic TCM, has been widely used in clinical treatment for MI. However, it is still difficult to clarify the potential active compounds and pharmacological mechanisms of it in treating MI.

AIM OF THE STUDY

To explore the active ingredients, pharmacological effects, potential targets and mechanisms of YQTMD against MI.

MATERIALS AND METHODS

Serum pharmacochemistry by UPLC-MS/MS was applied to analyze the phytochemical components in serum from YQTMD. These components were then used to predict the potential targets using network pharmacology approach and molecular dynamics simulations, and then the protective effect of them on H9c2 cells following hypoxic conditions was assessed. Afterwards, the pharmacological effects of YQTMD on MI in mice were tested by determining electrocardiogram (ECG), echocardiography, cardiac biomarkers, oxidative stress, inflammation and pathophysiological changes. The protein levels involving STAT3 signal were detected using Western blot and immunofluorescence assays. Furthermore, STAT3 inhibitor Sttatic was employed to further elucidate the underlying mechanisms.

RESULTS

Totally, 26 compounds derived from YQTMD were identified in mice serum, and 201 genes associated with the compounds were collected. The compounds including safflomin A, ferulic acid, gypenoside XVII, ginsenoside Rg1 and glycyrrhizic acid were identified as the critical compounds of YQTMD to regulate STAT3 pathway. In vitro, compounds combination significantly enhanced the viability of H9c2 cells and reduced ROS level compared to model cells. The in vivo results showed that YQTMD effectively reduced myocardial injury, as evidenced by the decreased serum cardiac injury markers, reduction in the size of myocardial infarct, restoration of abnormal alterations in ECG and decrease in cardiomyocyte apoptosis. Additionally, YQTMD attenuated MI-induced cardiac dysfunction, alleviated pathological changes, reduced MDA levels, and enhanced SOD and GSH levels compared with model mice. Significantly, the levels of IL-6, IL-1β, and TNF-α were observed to decrease in the YQTMD group. The expression levels of key proteins (p-STAT3, HIF-1α, NOX2, TLR5 and Caspase3) in STAT3 pathway were also regulated by YQTMD. However, the cardioprotective effects of YQTMD on MI were attenuated by STAT3 inhibitor Sttatic.

CONCLUSIONS

This study investigated the active ingredients and potential mechanisms of YQTMD for MI treatment based on serum pharmacochemistry and network pharmacology approaches, revealing that YQTMD exerts its therapeutic effects on MI by alleviating oxidative stress, inflammation and apoptosis through adjusting STAT3 signaling pathway.

L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice

BACKGROUND

L-theanine is a unique non-protein amino acid in tea that is widely used as a safe food additive. We investigated the cardioprotective effects and mechanisms of L-theanine in myocardial ischemia-reperfusion injury (MIRI).

METHODS

The cardioprotective effects and mechanisms of L-theanine and the role of Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling were investigated in MIRI mice using measures of cardiac function, oxidative stress, and apoptosis.

RESULTS

Administration of L-theanine (10 mg/kg, once daily) suppressed the MIRI-induced increase in infarct size and serum creatine kinase and lactate dehydrogenase levels, as well as MIRI-induced cardiac apoptosis, as evidenced by an increase in Bcl-2 expression and a decrease in Bax/caspase-3 expression. Administration of L-theanine also decreased the levels of parameters reflecting oxidative stress, such as dihydroethidium, malondialdehyde, and nitric oxide, and increased the levels of parameters reflecting anti-oxidation, such as total antioxidant capacity (T-AOC), glutathione (GSH), and superoxide dismutase (SOD) in ischemic heart tissue. Further analysis showed that L-theanine administration suppressed the MIRI-induced decrease of phospho-JAK2 and phospho-STAT3 in ischemic heart tissue. Inhibition of JAK2 by AG490 (5 mg/kg, once daily) abolished the cardioprotective effect of L-theanine, suggesting that the JAK2/STAT3 signaling pathway may play an essential role in mediating the anti-I/R effect of L-theanine.

CONCLUSIONS

L-theanine administration suppresses cellular apoptosis and oxidative stress in part via the JAK2/STAT3 signaling pathway, thereby attenuating MIRI-induced cardiac injury. L-theanine could be developed as a potential drug to alleviate cardiac damage in MIRI.

Macrophage Ontogeny, Phenotype, and Function in Ischemia Reperfusion-Induced Injury and Repair

AKI is characterized by a sudden, and usually reversible, decline in kidney function. In mice, ischemia-reperfusion injury (IRI) is commonly used to model the pathophysiologic features of clinical AKI. Macrophages are a unifying feature of IRI as they regulate both the initial injury response as well as the long-term outcome following resolution of injury. Initially, macrophages in the kidney take on a proinflammatory phenotype characterized by the production of inflammatory cytokines, such as CCL2 (monocyte chemoattractant protein 1), IL-6, IL-1 β , and TNF- α . Release of these proinflammatory cytokines leads to tissue damage. After resolution of the initial injury, macrophages take on a reparative role, aiding in tissue repair and restoration of kidney function. By contrast, failure to resolve the initial injury results in prolonged inflammatory macrophage accumulation and increased kidney damage, fibrosis, and the eventual development of CKD. Despite the extensive amount of literature that has ascribed these functions to M1/M2 macrophages, a recent paradigm shift in the macrophage field now defines macrophages on the basis of their ontological origin, namely monocyte-derived and tissue-resident macrophages. In this review, we focus on macrophage phenotype and function during IRI-induced injury, repair, and transition to CKD using both the classic (M1/M2) and novel (ontological origin) definition of kidney macrophages.

Research progress on rodent models and its mechanisms of liver injury

The liver is the most important organ for biological transformation in the body and is crucial for maintaining the body's vital activities. Liver injury is a serious pathological condition that is commonly found in many liver diseases. It has a high incidence rate, is difficult to cure, and is prone to recurrence. Liver injury can cause serious harm to the body, ranging from mild to severe fatty liver disease. If the condition continues to worsen, it can lead to liver fibrosis and cirrhosis, ultimately resulting in liver failure or liver cancer, which can seriously endanger human life and health. Therefore, establishing an rodent model that mimics the pathogenesis and severity of clinical liver injury is of great significance for better understanding the pathogenesis of liver injury patients and developing more effective clinical treatment methods. The author of this article summarizes common chemical liver injury models, immune liver injury models, alcoholic liver injury models, drug-induced liver injury models, and systematically elaborates on the modeling methods, mechanisms of action, pathways of action, and advantages or disadvantages of each type of model. The aim of this study is to establish reliable rodent models for researchers to use in exploring anti-liver injury and hepatoprotective drugs. By creating more accurate theoretical frameworks, we hope to provide new insights into the treatment of clinical liver injury diseases.

Integrated Analysis of lncRNA-miRNA-mRNA Regulatory Network in Rapamycin-Induced Cardioprotection against Ischemia/Reperfusion Injury in Diabetic Rabbits

The inhibition of mammalian target of rapamycin (mTOR) with rapamycin (RAPA) provides protection against myocardial ischemia/reperfusion (I/R) injury in diabetes. Since interactions between transcripts, including long non-coding RNA (lncRNA), microRNA(miRNA) and mRNA, regulate the pathophysiology of disease, we performed unbiased miRarray profiling in the heart of diabetic rabbits following I/R injury with/without RAPA treatment to identify differentially expressed (DE) miRNAs and their predicted targets of lncRNAs/mRNAs. Results showed that among the total of 806 unique miRNAs targets, 194 miRNAs were DE after I/R in diabetic rabbits. Specifically, eight miRNAs, including miR-199a-5p, miR-154-5p, miR-543-3p, miR-379-3p, miR-379-5p, miR-299-5p, miR-140-3p, and miR-497-5p, were upregulated and 10 miRNAs, including miR-1-3p, miR-1b, miR-29b-3p, miR-29c-3p, miR-30e-3p, miR-133c, miR-196c-3p, miR-322-5p, miR-499-5p, and miR-672-5p, were significantly downregulated after I/R injury. Interestingly, RAPA treatment significantly reversed these changes in miRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated the participation of miRNAs in the regulation of several signaling pathways related to I/R injury, including MAPK signaling and apoptosis. Furthermore, in diabetic hearts, the expression of lncRNAs, HOTAIR, and GAS5 were induced after I/R injury, but RAPA suppressed these lncRNAs. In contrast, MALAT1 was significantly reduced following I/R injury, with the increased expression of miR-199a-5p and suppression of its target, the anti-apoptotic protein Bcl-2. RAPA recovered MALAT1 expression with its sponging effect on miR-199-5p and restoration of Bcl-2 expression. The identification of novel targets from the transcriptome analysis in RAPA-treated diabetic hearts could potentially lead to the development of new therapeutic strategies for diabetic patients with myocardial infarction.

Regulation of mTOR Signaling: Emerging Role of Cyclic Nucleotide-Dependent Protein Kinases and Implications for Cardiometabolic Disease

The mechanistic target of rapamycin (mTOR) kinase is a central regulator of cell growth and metabolism. It is the catalytic subunit of two distinct large protein complexes, mTOR complex 1 (mTORC1) and mTORC2. mTOR activity is subjected to tight regulation in response to external nutrition and growth factor stimulation. As an important mechanism of signaling transduction, the 'second messenger' cyclic nucleotides including cAMP and cGMP and their associated cyclic nucleotide-dependent kinases, including protein kinase A (PKA) and protein kinase G (PKG), play essential roles in mediating the intracellular action of a variety of hormones and neurotransmitters. They have also emerged as important regulators of mTOR signaling in various physiological and disease conditions. However, the mechanism by which cAMP and cGMP regulate mTOR activity is not completely understood. In this review, we will summarize the earlier work establishing the ability of cAMP to dampen mTORC1 activation in response to insulin and growth factors and then discuss our recent findings demonstrating the regulation of mTOR signaling by the PKA- and PKG-dependent signaling pathways. This signaling framework represents a new non-canonical regulation of mTOR activity that is independent of AKT and could be a novel mechanism underpinning the action of a variety of G protein-coupled receptors that are linked to the mTOR signaling network. We will further review the implications of these signaling events in the context of cardiometabolic disease, such as obesity, non-alcoholic fatty liver disease, and cardiac remodeling. The metabolic and cardiac phenotypes of mouse models with targeted deletion of Raptor and Rictor, the two essential components for mTORC1 and mTORC2, will be summarized and discussed.

Single-Dose Treatment with Rapamycin Preserves Post-Ischemic Cardiac Function through Attenuation of Fibrosis and Inflammation in Diabetic Rabbit

Robust activation of mTOR (mammalian target of rapamycin) signaling in diabetes exacerbates myocardial injury following lethal ischemia due to accelerated cardiomyocyte death with cardiac remodeling and inflammatory responses. We examined the effect of rapamycin (RAPA, mTOR inhibitor) on cardiac remodeling and inflammation following myocardial ischemia/reperfusion (I/R) injury in diabetic rabbits. Diabetic rabbits (DM) were subjected to 45 min of ischemia and 10 days of reperfusion by inflating/deflating a previously implanted hydraulic balloon occluder. RAPA (0.25 mg/kg, i.v.) or DMSO (vehicle) was infused 5 min before the onset of reperfusion. Post-I/R left ventricular (LV) function was assessed by echocardiography and fibrosis was evaluated by picrosirius red staining. Treatment with RAPA preserved LV ejection fraction and reduced fibrosis. Immunoblot and real-time PCR revealed that RAPA treatment inhibited several fibrosis markers (TGF-β, Galectin-3, MYH, p-SMAD). Furthermore, immunofluorescence staining revealed the attenuation of post-I/R NLRP3-inflammasome formation with RAPA treatment as shown by reduced aggregation of apoptosis speck-like protein with a caspase recruitment domain and active-form of caspase-1 in cardiomyocytes. In conclusion, our study suggests that acute reperfusion therapy with RAPA may be a viable strategy to preserve cardiac function with the alleviation of adverse post-infarct myocardial remodeling and inflammation in diabetic patients.

Autophagy, innate immunity, and cardiac disease

Autophagy is an evolutionarily conserved mechanism of cell adaptation to metabolic and environmental stress. It mediates the disposal of protein aggregates and dysfunctional organelles, although non-conventional features have recently emerged to broadly extend the pathophysiological relevance of autophagy. In baseline conditions, basal autophagy critically regulates cardiac homeostasis to preserve structural and functional integrity and protect against cell damage and genomic instability occurring with aging. Moreover, autophagy is stimulated by multiple cardiac injuries and contributes to mechanisms of response and remodeling following ischemia, pressure overload, and metabolic stress. Besides cardiac cells, autophagy orchestrates the maturation of neutrophils and other immune cells, influencing their function. In this review, we will discuss the evidence supporting the role of autophagy in cardiac homeostasis, aging, and cardioimmunological response to cardiac injury. Finally, we highlight possible translational perspectives of modulating autophagy for therapeutic purposes to improve the care of patients with acute and chronic cardiac disease.

Induction of JAK2/STAT3 pathway contributes to protective effects of different therapeutics against myocardial ischemia/reperfusion

Insufficiency in coronary blood supply results in myocardial ischemia and consequently, various clinical syndromes and irreversible injuries. Myocardial damage occurs as a result of two processes during acute myocardial infarction (MI): ischemia and subsequent reperfusion. According to the available evidence, oxidative stress, excessive inflammation reaction, reactive oxygen species (ROS) generation, and apoptosis are crucial players in the pathogenesis of myocardial ischemia/reperfusion (IR) injury. There is emerging evidence that Janus tyrosine kinase 2 (JAK2) signal transducer and activator of the transcription 3 (STAT3) pathway offers cardioprotection against myocardial IR injury. This article reviews therapeutics that exert cardioprotective effects against myocardial IR injury through induction of JAK2/STAT3 pathway.

Bioactives and functional food ingredients with promising potential for the management of cerebral and myocardial ischemia: a comprehensive mechanistic review

Ischemia is a deadly disease featured by restricted perfusion to different organs in the body. An increase in the accumulation of reactive oxygen species and cell debris is the driving force for inducing many oxidative, inflammatory and apoptotic signaling pathways. However, the number of therapeutics existing for ischemic stroke patients is limited and there is insufficient data on their efficiency, which warrants the search for novel therapeutic candidates from natural sources. Herein, a comprehensive survey was done on the reported functional food bioactives (ca. 152 compounds) to manage or protect against health consequences of myocardial and cerebral ischemia. Furthermore, we reviewed the reported mechanistic studies for their anti-ischemic potential. Subsequently, network pharmacology- and in silico-based studies were conducted using the reported myocardial and cerebral ischemia-relevant molecular targets to study their complex interactions and highlight key targets in disease pathogenesis. Subsequently, the most prominent 20 compounds in the literature were used in a comprehensive in silico-based analysis (inverse docking, ΔG calculation and molecular dynamics simulation) to determine other potential targets for these compounds and their probable interactions with different signaling pathways relevant to this disease. Many functional food bioactives, belonging to different chemical classes, i.e., flavonoids, saponins, phenolics, alkaloids, iridoids and carotenoids, were proven to exhibit multifactorial effects in targeting the complex pathophysiology of ischemic conditions. These merits make them valuable therapeutic agents that can outperform the conventional drugs, and hence they can be utilized as add-ons to the conventional therapy for the management of different ischemic conditions; however, their rigorous clinical assessment is necessary.

Plants with Therapeutic Potential for Ischemic Acute Kidney Injury: A Systematic Review

Acute kidney injury (AKI) is a complex condition which has an intricate pathology mostly involving hemodynamic, inflammatory, and direct toxic effects at the cellular level with high morbidity and mortality ratios. Renal ischemic reperfusion injury (RIRI) is the main factor responsible for AKI, most often observed in different types of shock, kidney transplantation, sepsis, and postoperative procedures. The RIRI-induced AKI is accompanied by increased reactive oxygen species generation together with the activation of various inflammatory pathways. In this context, plant-derived medicines have shown encouraging nephroprotective properties. Evidence provided in this systemic review leads to the conclusion that plant-derived extracts and compounds exhibit nephroprotective action against renal ischemic reperfusion induced-AKI by increasing endogenous antioxidants and decreasing anti-inflammatory cytokines. However, there is no defined biomarker or target which can be used for treating AKI completely. These plant-derived extracts and compounds are only tested in selected transgenic animal models. To develop the results obtained into a therapeutic entity, one should apply them in proper vertebrate multitransgenic animal models prior to further validation in humans.

Cardioprotection by selective SGLT-2 inhibitors in a non-diabetic mouse model of myocardial ischemia/reperfusion injury: a class or a drug effect?

Major clinical trials with sodium glucose co-transporter-2 inhibitors (SGLT-2i) exhibit protective effects against heart failure events, whereas inconsistencies regarding the cardiovascular death outcomes are observed. Therefore, we aimed to compare the selective SGLT-2i empagliflozin (EMPA), dapagliflozin (DAPA) and ertugliflozin (ERTU) in terms of infarct size (IS) reduction and to reveal the cardioprotective mechanism in healthy non-diabetic mice. C57BL/6 mice randomly received vehicle, EMPA (10 mg/kg/day) and DAPA or ERTU orally at the stoichiometrically equivalent dose (SED) for 7 days. 24 h-glucose urinary excretion was determined to verify SGLT-2 inhibition. IS of the region at risk was measured after 30 min ischemia (I), and 120 min reperfusion (R). In a second series, the ischemic myocardium was collected (10th min of R) for shotgun proteomics and evaluation of the cardioprotective signaling. In a third series, we evaluated the oxidative phosphorylation capacity (OXPHOS) and the mitochondrial fatty acid oxidation capacity by measuring the respiratory rates. Finally, Stattic, the STAT-3 inhibitor and wortmannin were administered in both EMPA and DAPA groups to establish causal relationships in the mechanism of protection. EMPA, DAPA and ERTU at the SED led to similar SGLT-2 inhibition as inferred by the significant increase in glucose excretion. EMPA and DAPA but not ERTU reduced IS. EMPA preserved mitochondrial functionality in complex I&II linked oxidative phosphorylation. EMPA and DAPA treatment led to NF-kB, RISK, STAT-3 activation and the downstream apoptosis reduction coinciding with IS reduction. Stattic and wortmannin attenuated the cardioprotection afforded by EMPA and DAPA. Among several upstream mediators, fibroblast growth factor-2 (FGF-2) and caveolin-3 were increased by EMPA and DAPA treatment. ERTU reduced IS only when given at the double dose of the SED (20 mg/kg/day). Short-term EMPA and DAPA, but not ERTU administration at the SED reduce IS in healthy non-diabetic mice. Cardioprotection is not correlated to SGLT-2 inhibition, is STAT-3 and PI3K dependent and associated with increased FGF-2 and Cav-3 expression.

Bilateral Superior Cervical Sympathectomy Activates Signal Transducer and Activator of Transcription 3 Signal to Alleviate Myocardial Ischemia-Reperfusion Injury

Background

There is growing evidence about the effect of bilateral superior cervical sympathectomy on myocardial ischemia-reperfusion (I/R) injury. Studies have increasingly found that the signal transducer and activator of transcription 3 (STAT3) plays a protective role in myocardial I/R injury. However, the precise mechanism is unknown. The present study explored the bilateral superior cervical sympathectomy’s effect and potential mechanism in mice myocardial I/R injury.

Methods

The left heart I/R injury model was created by ligating the anterior descending branch of the coronary artery for 30 min followed by reperfusion. Bilateral superior cervical sympathectomy was performed before myocardial I/R injury. To evaluate the effect of bilateral superior cervical sympathectomy on the myocardium, we examined the myocardial infarct size and cardiac function. Then, myocardial apoptosis, inflammation, and oxidative stress were detected on the myocardium. Furthermore, the expression of STAT3 signal in myocardial tissue was measured by western blotting. To further examine the cardioprotective effect of STAT3 after bilateral superior cervical sympathectomy, the STAT3 inhibitor (static) was utilized to inhibit the phosphorylation of STAT3.

Results

The results showed that the myocardial I/R injury decreased and the cardiac function recovered in the myocardial I/R injury after cervical sympathectomy. Meanwhile, cervical sympathectomy reduced the myocardial distribution of the sympathetic marker tyrosine hydroxylase (TH) and systemic sympathetic tone. And levels of oxidative stress, inflammatory markers, and apoptosis were reduced in myocardial tissue. We also found that the STAT3 signal was activated in myocardial tissue after cervical sympathectomy. STAT3 inhibitor can partially reverse the myocardial protective effect of cervical sympathectomy.

Conclusion

Bilateral superior cervical sympathectomy significantly alleviated myocardial I/R injury in mice. And activation of the STAT3 signal may play an essential role in this.

The Anti-diabetic Drug Gliquidone Modulates Lipopolysaccharide-Mediated Microglial Neuroinflammatory Responses by Inhibiting the NLRP3 Inflammasome

The sulfonylurea drug gliquidone is FDA approved for the treatment of type 2 diabetes. Binding of gliquidone to ATP-sensitive potassium channels (SUR1, Kir6 subunit) in pancreatic β-cells increases insulin release to regulate blood glucose levels. Diabetes has been associated with increased levels of neuroinflammation, and therefore the potential effects of gliquidone on micro- and astroglial neuroinflammatory responses in the brain are of interest. Here, we found that gliquidone suppressed LPS-mediated microgliosis, microglial hypertrophy, and proinflammatory cytokine COX-2 and IL-6 levels in wild-type mice, with smaller effects on astrogliosis. Importantly, gliquidone downregulated the LPS-induced microglial NLRP3 inflammasome and peripheral inflammation in wild-type mice. An investigation of the molecular mechanism of the effects of gliquidone on LPS-stimulated proinflammatory responses showed that in BV2 microglial cells, gliquidone significantly decreased LPS-induced proinflammatory cytokine levels and inhibited ERK/STAT3/NF-κB phosphorylation by altering NLRP3 inflammasome activation. In primary astrocytes, gliquidone selectively affected LPS-mediated proinflammatory cytokine expression and decreased STAT3/NF-κB signaling in an NLRP3-independent manner. These results indicate that gliquidone differentially modulates LPS-induced microglial and astroglial neuroinflammation in BV2 microglial cells, primary astrocytes, and a model of neuroinflammatory disease.

The Role of the Signaling Pathways Involved in the Protective Effect of Exogenous Hydrogen Sulfide on Myocardial Ischemia-Reperfusion Injury

Ischemia/reperfusion (I/R) injury refers to the functional and structural changes in the process of blood flow recovery after ischemia. In addition to ischemia, the blood flow recovery can also lead to very harmful damage, such as the obvious cell swelling and the irreversible cell necrosis. I/R injury is related with many diseases, including myocardial I/R injury. Myocardial I/R injury refers to the aggravation of ischemic myocardial tissue injury due to sudden disorder of blood circulation. Although there are many studies on myocardial I/R injury, the exact mechanism is not fully understood. Hydrogen sulfide (H₂S), like carbon monoxide and nitric oxide, is an important gas signal molecule. It plays an important role in many physiological and pathological processes. Recent studies indicate that H₂S can improve myocardial I/R injury, however, its mechanism is not fully understood, especially the involved signal pathways. In this review, we summarize the related researches about the role of the signaling pathways involved in the protective effects of exogenous H₂S on myocardial I/R injury, so as to provide theoretical reference for the future in-depth researches.

LncRNA MIAT knockdown alleviates oxygen-glucose deprivation‑induced cardiomyocyte injury by regulating JAK2/STAT3 pathway via miR-181a-5p

BACKGROUND

Coronary artery disease (CAD) is a common heart disease with high incidence and mortality. Myocardial ischemia is the main type of CAD, which negatively affects health worldwide. The aim of the present study was to investigate the function and mechanism of myocardial infarction-associated transcript (MIAT) in myocardial ischemia.

METHODS

Human cardiomyocytes (HCM) were treated with oxygen-glucose deprivation (OGD) to set the in vitro model and mouse myocardial ischemia/reperfusion (I/R) was set for in vivo model. Cell viability and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, flow cytometry, and immunofluorescence analysis. Inflammatory cytokines levels were detected by enzyme-linked immunosorbent assay. Gene and protein expressions were identified by quantitative real time-polymerase chain reaction or Western blotting. The interaction of MIAT, miR-181a-5p, and janus kinase 2 (JAK2) was identified by dual-luciferase report assay. Mouse heart tissues histopathological condition were observed by hematoxylin and eosin assays.

RESULTS

Expression of MIAT and JAK2 were increased in OGD-treated HCM and mice of I/R model group, and miR-181a-5p was decreased. MIAT silencing could reverse the OGD treatment induced cell proliferation inhibition, cleaved caspase-3 and Bcl2-associated X (Bax) levels increased, while those of B-cell lymphoma-2 (Bcl-2) and mitochondria's cyt-C decreased. Besides, MIAT knockdown attenuated the OGD-induced increase of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 levels. Moreover, MIAT targeted miR-181a-5p to enhance the expression of JAK2 and signal Transducer and Activator of Transcription 3 (STAT3), and miR-181a-5p overexpression promoted proliferation, whereas it inhibited apoptosis in OGD-induced cardiomyocytes. Furthermore, the regulatory effects of MIAT knockdown in cell proliferation, apoptosis, and inflammatory injury was reversed by inhibition of miR-181a-5p or overexpression of JAK2 in OGD-treated HCM. Knockdown of MIAT reduced myocardial injury caused by I/R treatment in vivo.

CONCLUSION

MIAT knockdown inhibited apoptosis and inflammation by regulating JAK2/STAT3 signaling pathway via targeting miR-181a-5p in myocardial ischemia model. MIAT can be a possible therapeutic target for controlling the progression of myocardial ischemia.

Punicalagin Protects Against Diabetic Cardiomyopathy by Promoting Opa1-Mediated Mitochondrial Fusion via Regulating PTP1B-Stat3 Pathway

Aims: This study aims to explore the efficacy of punicalagin (PG) on diabetic cardiomyopathy (DCM), with a specific focus on the mechanisms underlying the effects of PG on mitochondrial fusion/fission dynamics. Results: Cardiac structural and functional abnormalities were ameliorated in diabetic rats receiving PG administration as evidenced by increased ejection fraction, and attenuated myocardial fibrosis and hypertrophy. PG enhanced mitochondrial function and inhibited mitochondria-derived oxidative stress by promoting Opa1-mediated mitochondrial fusion. The benefits of PG could be abrogated by knockdown of Opa1 in vivo and in vitro. Inhibitor screening and chromatin immunoprecipitation analysis showed that Stat3 directly regulated the transcriptional expression of Opa1 by binding to its promoter and was responsible for PG-induced Opa1-mediated mitochondrial fusion. Moreover, pharmmapper screening and molecular docking studies revealed that PG embedded into the activity pocket of PTP1B and inhibited the activity of PTP1B. Overexpression of PTP1B blocked the promoting effect of PG on Stat3 phosphorylation and Opa1-mediated mitochondrial fusion, whereas knockdown of PTP1B mimicked the benefits of PG in high-glucose-treated cardiomyocytes. Innovation: Our study is the first to identify PG as a novel mitochondrial fusion promoter against hyperglycemia-induced mitochondrial oxidative injury and cardiomyopathy by upregulating Opa1 via regulating PTP1B-Stat3 pathway. Conclusion: PG protects against DCM by promoting Opa1-mediated mitochondrial fusion, a process in which PG interacts with PTP1B and inhibits its activity, which in turn increases Stat3 phosphorylation and then enhances the transcriptional expression of Opa1. These results suggest that PG might be a promising new therapeutic approach against diabetic cardiac complication. Antioxid. Redox Signal. 35, 618-641.

Self-eating and Heart: The Emerging Roles of Autophagy in Calcific Aortic Valve Disease

Autophagy is a self-degradative pathway by which subcellular elements are broken down intracellularly to maintain cellular homeostasis. Cardiac autophagy commonly decreases with aging and is accompanied by the accumulation of misfolded proteins and dysfunctional organelles, which are undesirable to the cell. Reduction of autophagy over time leads to aging-related cardiac dysfunction and is inversely related to longevity. However, despite the increasing interest in autophagy in cardiac diseases and aging, the process remains an undervalued and disregarded object in calcific valvular disease. Neither the nature through which autophagy is triggered nor the interplay between autophagic machinery and targeted molecules during aortic valve calcification are fully understood. Recently, the upregulation of autophagy has been shown to result in cardioprotective effects against cell death as well as its origin. Here, we review the evidence that shows how autophagy can be both beneficial and detrimental as it pertains to aortic valve calcification in the heart.

Rapamycin-Preactivated Autophagy Enhances Survival and Differentiation of Mesenchymal Stem Cells After Transplantation into Infarcted Myocardium

Stem cell transplantation has been limited by poor survival of the engrafted cells in hostile microenvironment of the infarcted myocardium. This study investigated cytoprotective effect of rapamycin-preactivated autophagy on survival of the transplanted mesemchymal stem cells (MSCs). MSCs isolated from rat bone marrow were treated with 50 nmol/L rapamycin for 2 h, and then the cytoprotective effect of rapamycin was examined. After intramyocardial transplantation in rat ischemia/reperfusion models, the survival and differentiation of the rapamycin-pretreated calls were accessed. After treatment with rapamycin, autophagic activities and lysososme production of the cells were increased significantly. In the condition of short-term or long-term hypoxia and serum deprivation, the apoptotic cells in rapamycin-pretreated cells were less, and secretion of HGF, IGF-1, SCF, SDF-1 and VEGF was increased. After transplantation of rapamycin-pretreated cells, repair of the infarcted myocardium and restoration of cardial function were enhanced dramatically. Expression of HGF, IGF-1, SCF, SDF-1, VEGF, HIF-1α and IL-10 in the myocardium was upregulated, while expression of IL-1β and TNF-α was downregulated. Tracing of GFP and Sry gene showed that the survival of rapamycin-pretreated cells was increased. Cardiomyogenesis and angiogenesis in the infarcted myocardium were strengthened. Some rapamycin-pretreated cells differentiated into cardiomyocytes or endothelial cells. These results demonstrate that moderate preactivation of autophagy with rapamycin enhances the survival and differentiation of the transplanted MSCs. Rapamycin-primed MSCs can promote repair of the infarcted myocardium and improvement of cardiac function effectively.

Rapamycin Alternatively Modifies Mitochondrial Dynamics in Dendritic Cells to Reduce Kidney Ischemic Reperfusion Injury

Dendritic cells (DCs) are unique immune cells that can link innate and adaptive immune responses and Immunometabolism greatly impacts their phenotype. Rapamycin is a macrolide compound that has immunosuppressant functions and is used to prevent graft loss in kidney transplantation. The current study evaluated the therapeutic potential of ex-vivo rapamycin treated DCs to protect kidneys in a mouse model of acute kidney injury (AKI). For the rapamycin single (S) treatment (Rapa-S-DC), Veh-DCs were treated with rapamycin (10 ng/mL) for 1 h before LPS. In contrast, rapamycin multiple (M) treatment (Rapa-M-DC) were exposed to 3 treatments over 7 days. Only multiple ex-vivo rapamycin treatments of DCs induced a persistent reprogramming of mitochondrial metabolism. These DCs had 18-fold more mitochondria, had almost 4-fold higher oxygen consumption rates, and produced more ATP compared to Veh-DCs (Veh treated control DCs). Pathway analysis showed IL10 signaling as a major contributing pathway to the altered immunophenotype after Rapamycin treatment compared to vehicle with significantly lower cytokines Tnfa, Il1b, and Il6, while regulators of mitochondrial content Pgc1a, Tfam, and Ho1 remained elevated. Critically, adoptive transfer of rapamycin-treated DCs to WT recipients 24 h before bilateral kidney ischemia significantly protected the kidneys from injury with a significant 3-fold improvement in kidney function. Last, the infusion of DCs containing higher mitochondria numbers (treated ex-vivo with healthy isolated mitochondria (10 µg/mL) one day before) also partially protected the kidneys from IRI. These studies demonstrate that pre-emptive infusion of ex-vivo reprogrammed DCs that have higher mitochondria content has therapeutic capacity to induce an anti-inflammatory regulatory phenotype to protect kidneys from injury.

Acute glucose fluctuation promotes in vitro intestinal epithelial cell apoptosis and inflammation via the NOX4/ROS/JAK/STAT3 signaling pathway

High blood glucose commonly occurs in patients with diabetes mellitus, but little is known of its effects on intestinal epithelial cells, or its associated mechanisms of action therein. In the present study, intestinal epithelial cells were assigned to five groups: i) The normal glucose (NG) group, incubated in 5.0 mmol/l glucose; ii) the constant high glucose (CHG) group, treated with 25.0 mmol/l glucose; iii) the intermittent high glucose (IHG) group, treated with alternating doses of 5.0 and 25.0 mmol/l glucose every 8 h; iv) the mannose group, cultured in 25.0 mmol/l mannose (the osmotic control); and v) the IHG glucose + GKT137831 group, pretreated with 100 nmol/l NADPH oxidase 4 (NOX4) inhibitor, GKT137831, and then exposed to IHG. TNF-α, IL-1 and IL-6 levels were quantified using ELISA kits. Intestinal epithelial cell apoptosis was assessed by flow cytometry and oxidative stress was evaluated by reactive oxygen species (ROS) and malondialdehyde (MDA) detection. The expression levels of proteins associated with apoptosis and involved in the signal transduction of Janus kinase (JAK)/STAT3 pathway were assessed using western blot analysis. The results indicated that NOX4 expression was significantly higher in the CHG group than in the NG group (P<0.01), but lower than in the IHG group (P<0.001). The IHG group exhibited apoptosis and oxidative stress accompanied by the most significant increase in MDA, ROS and inflammatory cytokine levels (P<0.001), which was followed by that of the CHG group. Additionally, the IHG group exhibited reduced Bcl-2, as well as enhanced Bax and cleaved caspase-3 levels compared with the CHG group (P<0.001). Furthermore, the level of phosphorylated (p-)JAK/p-STAT3 was increased to a greater extent in the IHG group than in the CHG group (P<0.001). In conclusion, the findings of the present study indicated that CHG may trigger intestinal epithelial cell apoptosis and inflammation through the NOX4/ROS/JAK/STAT3 pathway, which may be aggravated by acute glucose fluctuation.

Hypertrophy-Reduced Autophagy Causes Cardiac Dysfunction by Directly Impacting Cardiomyocyte Contractility

Cardiac remodeling and contractile dysfunction are leading causes in hypertrophy-associated heart failure (HF), increasing with a population's rising age. A hallmark of aged and diseased hearts is the accumulation of modified proteins caused by an impaired autophagy-lysosomal-pathway. Although, autophagy inducer rapamycin has been described to exert cardioprotective effects, it remains to be shown whether these effects can be attributed to improved cardiomyocyte autophagy and contractility. In vivo hypertrophy was induced by transverse aortic constriction (TAC), with mice receiving daily rapamycin injections beginning six weeks after surgery for four weeks. Echocardiographic analysis demonstrated TAC-induced HF and protein analyses showed abundance of modified proteins in TAC-hearts after 10 weeks, both reduced by rapamycin. In vitro, cardiomyocyte hypertrophy was mimicked by endothelin 1 (ET-1) and autophagy manipulated by silencing Atg5 in neonatal cardiomyocytes. ET-1 and siAtg5 decreased Atg5-Atg12 and LC3-II, increased natriuretic peptides, and decreased amplitude and early phase of contraction in cardiomyocytes, the latter two evaluated using ImageJ macro Myocyter recently developed by us. ET-1 further decreased cell contractility in control but not in siAtg5 cells. In conclusion, ET-1 decreased autophagy and cardiomyocyte contractility, in line with siAtg5-treated cells and the results of TAC-mice demonstrating a crucial role for autophagy in cardiomyocyte contractility and cardiac performance.

mTOR-mediated calcium transients affect cardiac function in ex vivo ischemia-reperfusion injury

The mechanistic target of rapamycin (mTOR) is a key mediator of energy metabolism, cell growth, and survival. While previous studies using transgenic mice with cardiac-specific overexpression of mTOR (mTOR-Tg) demonstrated the protective effects of cardiac mTOR against ischemia-reperfusion (I/R) injury in both ex vivo and in vivo models, the mechanisms underlying the role of cardiac mTOR in cardiac function following I/R injury are not well-understood. Torin1, a pharmacological inhibitor of mTOR complex (mTORC) 1 and mTORC2, significantly decreased functional recovery of LV developed pressure in ex vivo I/R models (p < 0.05). To confirm the role of mTOR complexes in I/R injury, we generated cardiac-specific mTOR-knockout (CKO) mice. In contrast to the effects of Torin1, CKO hearts recovered better after I/R injury than control hearts (p < 0.05). Interestingly, the CKO hearts had exhibited irregular contractions during the reperfusion phase. Calcium is a major factor in Excitation-Contraction (EC) coupling via Sarcoplasmic Reticulum (SR) calcium release. Calcium is also key in opening the mitochondrial permeability transition pore (mPTP) and cell death following I/R injury. Caffeine-induced SR calcium release in isolated CMs showed that total SR calcium content was lower in CKO than in control CMs. Western blotting showed that a significant amount of mTOR localizes to the SR/mitochondria and that GSK3-β phosphorylation, a key factor in SR calcium mobilization, was decreased. These findings suggest that cardiac mTOR located to the SR/mitochondria plays a vital role in EC coupling and cell survival in I/R injury.

Binge-like ethanol drinking activates anaplastic lymphoma kinase signaling and increases the expression of STAT3 target genes in the mouse hippocampus and prefrontal cortex

Alcohol use disorder (AUD) has a complex pathogenesis, making it a difficult disorder to treat. Identifying relevant signaling pathways in the brain may be useful for finding new pharmacological targets to treat AUD. The receptor tyrosine kinase anaplastic lymphoma kinase (ALK) activates the transcription factor STAT3 in response to ethanol in cell lines. Here, we show ALK activation and upregulation of known STAT3 target genes (Socs3, Gfap and Tnfrsf1a) in the prefrontal cortex (PFC) and ventral hippocampus (HPC) of mice after 4 days of binge-like ethanol drinking. Mice treated with the STAT3 inhibitor stattic drank less ethanol than vehicle-treated mice, demonstrating the behavioral importance of STAT3. To identify novel ethanol-induced target genes downstream of the ALK and STAT3 pathway, we analyzed the NIH LINCS L1000 database for gene signature overlap between ALK inhibitor (alectinib and NVP-TAE684) and STAT3 inhibitor (niclosamide) treatments on cell lines. These genes were then compared with differentially expressed genes in the PFC of mice after binge-like drinking. We found 95 unique gene candidates, out of which 57 had STAT3 binding motifs in their promoters. We further showed by qPCR that expression of the putative STAT3 genes Nr1h2, Smarcc1, Smarca4 and Gpnmb were increased in either the PFC or HPC after binge-like drinking. Together, these results indicate activation of the ALK-STAT3 signaling pathway in the brain after binge-like ethanol consumption, identify putative novel ethanol-responsive STAT3 target genes, and suggest that STAT3 inhibition may be a potential method to reduce binge drinking in humans.

Effect of Quercetin-Loaded Mesoporous Silica Nanoparticles on Myocardial Ischemia-Reperfusion Injury in Rats and Its Mechanism

BACKGROUND

Quercetin has potential value in treating cardiovascular diseases, but it is not suitable for clinical application due to its own water solubility. The limitation of quercetin can be distinctly ameliorated by delivering it with nanocarriers.

OBJECTIVE

To determine the effect of quercetin-loaded mesoporous silica nanoparticles (Q-MSNs) on myocardial ischemia-reperfusion injury in rats and its mechanism.

METHODS

Q-MSNs were synthesized, and the morphology of Q-MSNs and MSNs was characterized by transmission electron microscopy and dynamic light scattering technique, respectively. Healthy rats were enrolled and randomly divided into a sham operation control group, an ischemia-reperfusion (IR) group, an IR+Q group, an IR+Q-MSNs group, and an MSNs group (each n = 10). Rats in the sham operation group were not treated with ischemia reperfusion, but given normal perfusion meantime. Rats in the sham operation control group, IR group, and MSNs group were given normal saline for 10 days before ischemia reperfusion, and rats in the IR+Q group and IR+Q-MSNs group were given drugs by gavage for 10 days before ischemia reperfusion. Primary myocardial cells were sampled from SD neonatal rats to construct hypoxia/reoxygenation myocardial cell models. The myocardial cells were assigned to a control group, IR group, quercetin (Q) group, Q-MSNs group, and MSNs group. Except for the control group, all the other groups were treated with hypoxia/reoxygenation. Cells in the Q group were treated with quercetin (10 μM, 20 μM, 40 μM) for 24 h in advance and then treated with measures to cause hypoxia-reoxygenation injury. Cells in the Q-MSNs group were treated with the same concentration of loaded quercetin and the same method used for the Q group. The myocardial apoptosis, myocardial infarction, ventricular remodeling, hemodynamic indexes, physiological and biochemical indexes, and JAK2/STAT3 pathway expression of each group were detected, and the apoptosis, viability, oxidative stress, and JAK2/STAT3 pathway expression of primary myocardial cells in each group were also detected.

RESULTS

Quercetin significantly activated the JAK2/STAT3 pathway in vivo and in vitro, and MSNs intensified the activation. Compared with quercetin, Q-MSNs were more effective in inhibiting cell apoptosis and oxidative stress, reducing myocardial infarction size, improving ventricular remodeling and cardiac function-related biochemical indexes, and promoting the recovery of cardiac blood flow.

CONCLUSION

Q-MSNs can significantly enhance the activation effect of quercetin on JAK2/STAT3 pathway, thus enhancing its protection on the heart of MIRI rats.

The complex network of mTOR signaling in the heart

The mechanistic target of rapamycin (mTOR) integrates several intracellular and extracellular signals involved in the regulation of anabolic and catabolic processes. mTOR assembles into two macromolecular complexes, named mTORC1 and mTORC2, which have different regulators, substrates and functions. Studies of gain- and loss-of-function animal models of mTOR signaling revealed that mTORC1/2 elicit both adaptive and maladaptive functions in the cardiovascular system. Both mTORC1 and mTORC2 are indispensable for driving cardiac development and cardiac adaption to stress, such as pressure overload. However, persistent and deregulated mTORC1 activation in the heart is detrimental during stress and contributes to the development and progression of cardiac remodeling and genetic and metabolic cardiomyopathies. In this review, we discuss the latest findings regarding the role of mTOR in the cardiovascular system, both under basal conditions and during stress, such as pressure overload, ischemia and metabolic stress. Current data suggest that mTOR modulation may represent a potential therapeutic strategy for the treatment of cardiac diseases.

MTORC1-Regulated Metabolism Controlled by TSC2 Limits Cardiac Reperfusion Injury

RATIONALE

The mTORC1 (mechanistic target of rapamycin complex-1) controls metabolism and protein homeostasis and is activated following ischemia reperfusion (IR) injury and by ischemic preconditioning (IPC). However, studies vary as to whether this activation is beneficial or detrimental, and its influence on metabolism after IR is little reported. A limitation of prior investigations is their use of broad gain/loss of mTORC1 function, mostly applied before ischemic stress. This can be circumvented by regulating one serine (S1365) on TSC2 (tuberous sclerosis complex) to achieve bidirectional mTORC1 modulation but only with TCS2-regulated costimulation.

OBJECTIVE

We tested the hypothesis that reduced TSC2 S1365 phosphorylation protects the myocardium against IR and is required for IPC by amplifying mTORC1 activity to favor glycolytic metabolism.

METHODS AND RESULTS

Mice with either S1365A (TSC2^SA; phospho-null) or S1365E (TSC2^SE; phosphomimetic) knockin mutations were studied ex vivo and in vivo. In response to IR, hearts from TSC2^SA mice had amplified mTORC1 activation and improved heart function compared with wild-type and TSC2^SE hearts. The magnitude of protection matched IPC. IPC requited less S1365 phosphorylation, as TSC2^SE hearts gained no benefit and failed to activate mTORC1 with IPC. IR metabolism was altered in TSC2^SA, with increased mitochondrial oxygen consumption rate and glycolytic capacity (stressed/maximal extracellular acidification) after myocyte hypoxia-reperfusion. In whole heart, lactate increased and long-chain acylcarnitine levels declined during ischemia. The relative IR protection in TSC2^SA was lost by lowering glucose in the perfusate by 36%. Adding fatty acid (palmitate) compensated for reduced glucose in wild type and TSC2^SE but not TSC2^SA which had the worst post-IR function under these conditions.

CONCLUSIONS

TSC2-S1365 phosphorylation status regulates myocardial substrate utilization, and its decline activates mTORC1 biasing metabolism away from fatty acid oxidation to glycolysis to confer protection against IR. This pathway is also engaged and reduced TSC2 S1365 phosphorylation required for effective IPC. Graphic Abstract: A graphic abstract is available for this article.

Short- and long-term effects of rapamycin on ischemic damage and apoptotic changes in torsion of rat testes

Rapamycin has antioxidant defense mechanisms and immune suppressive effects. To detect the short- and long-term effects of rapamycin on ischemic damage and apoptotic changes in torsion of rat testes, mature male albino Wistar rats (n = 48) were included in the study as control, sham, early torsion-detorsion (T/D), early rapamycin treatment, early rapamycin control, late T/D, late rapamycin treatment, and late rapamycin control. The right testis was rotated 720° in a clockwise direction during 4 h in operation groups. Rapamycin was administered orally three times: 30 min before detorsion and 24 and 48 h after detorsion. The animals were killed on the third day in early groups and on the tenth day in late groups after detorsion. Statistically significant differences among all groups were detected for SOD and TBARS, mean seminiferous tubule diameter (MSTD) and Cosentino's histologic score (CHS), caspase 3, bax, average number of apoptotic cells per tubule (ANPCT), and percentage of apoptotic tubule (PAT) values. ANPCT values ​​were 10% lower in the rapamycin treatment groups compared with the untreated T/D groups, and the PAT values ​​were also approximately 1.3 times lower. Although short-term usage of rapamycin may reduce to the tubular injury caused by I/R conversely to apoptosis in the testicular tissue after testicular torsion, rapamycin may have the potential to increase the long-term apoptosis with/without testicular torsion and a subsequent regression in fertility.

Deciphering key regulators involved in epilepsy-induced cardiac damage through whole transcriptome and proteome analysis in a rat model

OBJECTIVE

Sudden unexpected death in epilepsy (SUDEP) is a major outcome of cardiac dysfunction in patients with epilepsy. In continuation of our previous work, the present study was envisaged to explore the key regulators responsible for cardiac damage associated with chronic seizures using whole transcriptome and proteome analysis in a rat model of temporal lobe epilepsy.

METHODS

A standard lithium-pilocarpine protocol was used to induce recurrent seizures in rats. The isolated rat heart tissue was subjected to transcriptomic and proteomic analysis. An integrated approach of RNA-Seq, proteomics, and system biology analysis was used to identify key regulators involved in seizure-linked cardiac changes. The analyzed differential expression patterns and network interactions were supported by gene and protein expression studies.

RESULTS

Altogether, 1157 differentially expressed genes and 1264 proteins were identified in the cardiac tissue of epileptic animals through RNA-Seq and liquid chromatography with tandem mass spectrometry-based proteomic analysis, respectively. The network analysis revealed seven critical genes-STAT3, Myc, Fos, Erbb2, Erbb3, Notch1, and Mapk8-that could play a role in seizure-mediated cardiac changes. The LC-MS/MS analysis supported the activation of the transforming growth factor β (TGF-β) pathway in the heart of epileptic animals. Furthermore, our gene and protein expression studies established a key role of STAT3, Erbb, and Mapk8 to develop cardiac changes linked with recurrent seizures.

SIGNIFICANCE

The present multi-omics study identified STAT3, Mapk8, and Erbb as key regulators involved in seizure-associated cardiac changes. It provided a deeper understanding of molecular, cellular, and network-level operations of the identified regulators that lead to cardiac changes in epilepsy.

The Role of iPSC Modeling Toward Projection of Autophagy Pathway in Disease Pathogenesis: Leader or Follower

Autophagy is responsible for degradation of non-essential or damaged cellular constituents and damaged organelles. The autophagy pathway maintains efficient cellular metabolism and reduces cellular stress by removing additional and pathogenic components. Dysfunctional autophagy underlies several diseases. Thus, several research groups have worked toward elucidating key steps in this pathway. Autophagy can be studied by animal modeling, chemical modulators, and in vitro disease modeling with induced pluripotent stem cells (iPSC) as a loss-of-function platform. The introduction of iPSC technology, which has the capability to maintain the genetic background, has facilitated in vitro modeling of some diseases. Furthermore, iPSC technology can be used as a platform to study defective cellular and molecular pathways during development and unravel novel steps in signaling pathways of health and disease. Different studies have used iPSC technology to explore the role of autophagy in disease pathogenesis which could not have been addressed by animal modeling or chemical inducers/inhibitors. In this review, we discuss iPSC models of autophagy-associated disorders where the disease is caused due to mutations in autophagy-related genes. We classified this group as "primary autophagy induced defects (PAID)". There are iPSC models of diseases in which the primary cause is not dysfunctional autophagy, but autophagy is impaired secondary to disease phenotypes. We call this group "secondary autophagy induced defects (SAID)" and discuss them. Graphical abstract.

STAT3-miR-17/20 signalling axis plays a critical role in attenuating myocardial infarction following rapamycin treatment in diabetic mice

AIMS

Deregulation of mTOR (mammalian target of rapamycin) signalling occurs in diabetes, which exacerbates injury following myocardial infarction (MI). We therefore investigated the infarct-limiting effect of chronic treatment with rapamycin (RAPA, mTOR inhibitor) in diabetic mice following myocardial ischaemia/reperfusion (I/R) injury and delineated the potential protective mechanism.

METHODS AND RESULTS

Adult male diabetic (db/db) or wild-type (WT) (C57) mice were treated with RAPA (0.25 mg/kg/day, intraperitoneal) or vehicle (5% DMSO) for 28 days. The hearts from treated mice were subjected to global I/R in Langendorff mode. Cardiomyocytes, isolated from treated mice, were subjected to simulated ischaemia/reoxygenation (SI/RO) to assess necrosis and apoptosis. Myocardial infarct size was increased in diabetic heart following I/R as compared to WT. Likewise, enhanced necrosis and apoptosis were observed in isolated cardiomyocytes of diabetic mice following SI/RO. Treatment with RAPA reduced infarct size as well as cardiomyocyte necrosis and apoptosis of diabetes and WT mice. RAPA increased STAT3 phosphorylation and miRNA-17/20a expression in diabetic hearts. In addition, RAPA restored AKT phosphorylation (target of mTORC2) but suppressed S6 phosphorylation (target of mTORC1) following I/R injury. RAPA-induced cardioprotection against I/R injury as well as the induction of miR-17/20a and AKT phosphorylation were abolished in cardiac-specific STAT3-deficient diabetic mice, without alteration of S6 phosphorylation. The infarct-limiting effect of RAPA was obliterated in cardiac-specific miRNA-17-92-deficient diabetic mice. The post-I/R restoration of phosphorylation of STAT3 and AKT with RAPA were also abolished in miRNA-17-92-deficient diabetic mice. Additionally, RAPA suppressed the pro-apoptotic prolyl hydroxylase (Egln3/PHD3), a target of miRNA-17/20a in diabetic hearts, which was abrogated in miRNA-17-92-deficient diabetic mice.

CONCLUSION

Induction of STAT3-miRNA-17-92 signalling axis plays a critical role in attenuating MI in RAPA-treated diabetic mice. Our study indicates that chronic treatment with RAPA might be a promising pharmacological intervention for attenuating MI and improving prognosis in diabetic patients.

Caloric restriction mimetics for the treatment of cardiovascular diseases

Caloric restriction mimetics (CRMs) are emerging as potential therapeutic agents for the treatment of cardiovascular diseases. CRMs include natural and synthetic compounds able to inhibit protein acetyltransferases, to interfere with acetyl coenzyme A biosynthesis, or to activate (de)acetyltransferase proteins. These modifications mimic the effects of caloric restriction, which is associated with the activation of autophagy. Previous evidence demonstrated the ability of CRMs to ameliorate cardiac function and reduce cardiac hypertrophy and maladaptive remodelling in animal models of ageing, mechanical overload, chronic myocardial ischaemia, and in genetic and metabolic cardiomyopathies. In addition, CRMs were found to reduce acute ischaemia-reperfusion injury. In many cases, these beneficial effects of CRMs appeared to be mediated by autophagy activation. In the present review, we discuss the relevant literature about the role of different CRMs in animal models of cardiac diseases, emphasizing the molecular mechanisms underlying the beneficial effects of these compounds and their potential future clinical application.

STAT3 inhibition protects against neuroinflammation and BACE1 upregulation induced by systemic inflammation

Abnormal activation of the transcriptional factor STAT3 (signal transducer and activator of transcription 3) was recently associated with Alzheimer Disease (AD). STAT3 phosphorylation is critical for cytokine secretion linked to neuroinflammation. Moreover, STAT3 may act as a transcriptional regulator of BACE1 (β-APP cleaving enzyme-1), the key enzyme in amyloid β (Aβ) production. We have previously shown that neuroinflammation and increased brain BACE1 levels triggered by LPS-induced systemic inflammation in wild-type mice are associated with an enhanced STAT3 activation. Using this LPS model, the goal of this study was to investigate if a STAT3 inhibitor administration could be protective against neuroinflammation and abnormal BACE1 regulation. Our results show that intraperitoneal injection of Stattic, a molecule that selectively inhibits the activation of STAT3, decreases LPS-induced microglial activation in the hippocampus. In addition, STAT3 inhibition reduced brain levels of cytokines IL-6, IL-1β and TNF-α triggered by LPS systemic administration. A significant reduction of BACE1 levels was observed in the hippocampus of mice treated with LPS and Stattic compared to those exposed to LPS alone. Taking together, our results show that Stattic can protect hippocampus against two pathological hallmarks of AD, and pave the way for further explorations of the therapeutic potential of STAT3 inhibition in AD.

Downregulation of LAPTM4B Contributes to the Impairment of the Autophagic Flux via Unopposed Activation of mTORC1 Signaling During Myocardial Ischemia/Reperfusion Injury

RATIONALE

Impaired autophagic flux contributes to ischemia/reperfusion (I/R)-induced cardiomyocyte death, but the underlying molecular mechanisms remain largely unexplored.

OBJECTIVE

To determine the role of LAPTM4B (lysosomal-associated transmembrane protein 4B) in the regulation of autophagic flux and myocardial I/R injury.

METHODS AND RESULTS

LAPTM4B was expressed in murine hearts but downregulated in hearts with I/R (30 minutes/2 hours) injury and neonatal rat cardiomyocytes with hypoxia/reoxygenation (6 hours/2 hours) injury. During myocardial reperfusion, LAPTM4B-knockout (LAPTM4B^-/-) mice had a significantly increased infarct size and lactate dehydrogenase release, whereas adenovirus-mediated LAPTM4B-overexpression was cardioprotective. Concomitantly, LAPTM4B^-/- mice showed higher accumulation of the autophagy markers LC3-II (microtubule-associated protein 1A/1B-light chain 3), but not P62, in the I/R heart, whereas they did not alter chloroquine-induced further increases of LC3-II and P62 in both sham and I/R hearts. Conversely, LAPTM4B-overexpression had opposite effects. The hypoxia/reoxygenation-reduced viability of neonatal rat cardiomyocytes, ratio of autolysosomes/autophagosomes, and function of lysosomes were further decreased by LAPTM4B-knockdown but reversed by LAPTM4B-overexpression. Moreover, the LAPTM4B-overexpression-mediated benefits were abolished by knockdown of lysosome-associated membrane protein-2 (an autophagosome-lysosome fusion protein) in vivo and by the autophagy inhibitor bafilomycin A1 in vivo. In contrast, rapamycin (Rapa) successfully restored the impaired autophagic flux in LAPTM4B^-/- mice and the subsequent myocardial I/R injury. Mechanistically, LAPTM4B regulated the activity of mTORC1 (mammalian target of rapamycin complex 1) via interacting with mTOR through its EC3 (extracelluar) domain. Thus, mTORC1 was overactivated in LAPTM4B^-/- mice, leading to the repression of TFEB (transcription factor EB), a master regulator of lysosomal and autophagic genes, during myocardial I/R. The mTORC1 inhibition or TFEB-overexpression rescued the LAPTM4B^-/--induced impairment in autophagic flux and I/R injury, whereas TFEB-knockdown abolished the LAPTM4B-overexpression-mediated recovery of autophagic flux and cardioprotection.

CONCLUSIONS

The downregulation of LAPTM4B contributes to myocardial I/R-induced impairment of autophagic flux via modulation of the mTORC1/TFEB pathway. Graphic Abstract: A graphic abstract is available for this article.

Electroacupuncture Pretreatment Attenuates Intestinal Injury after Autogenous Orthotopic Liver Transplantation in Rats via the JAK/STAT Pathway

Background

Liver transplantation induces self-injury and affects remote organs, such as the lung, kidney, and intestine. Postoperative intestinal dysfunction has been associated with prolonged hospitalization and affects a patient's health and quality of life. Electroacupuncture (EA) has been proven effective in multiple organ protection. However, the potential mechanism underlying the protective effects of EA on intestinal injury after liver transplantation remains unclear.

Methods

After establishing an autogenous orthotopic liver transplantation (AOLT) model, we studied the effects of EA pretreatment on intestinal injury after AOLT. We used the JAK2-specific inhibitor AG490 to explore the underlying mechanism. Histological analysis and apoptosis assays were used to evaluate intestinal injury. Oxidative stress index and inflammatory response were also measured after AOLT. Furthermore, we detected the phosphorylation levels of JAK2, STAT1, and STAT3 by Western blot.

Results

We found that pretreatment with EA alleviated intestinal injury after AOLT, as shown by HE staining and TUNEL methods. EA pretreatment inhibited the expressions of p-JAK2, p-STAT1, and p-STAT3 in the intestines after AOLT. Upon treatment with JAK2-specific inhibitor AG490, intestinal injury was balanced.

Conclusion

The data indicated EA pretreatment alleviated intestinal injury after AOLT by inhibiting the JAK/STAT signaling pathway. These results provide basic evidence to support the potential therapeutic efficacy of EA.

MiR-375 Mediates Chondrocyte Metabolism and Oxidative Stress in Osteoarthritis Mouse Models through the JAK2/STAT3 Signaling Pathway

OBJECTIVE

The aim of this work was to determine the effect of miR-375 on chondrocyte metabolism and oxidative stress in osteoarthritis (OA) mouse models through the JAK2/STAT3 signaling pathway.

METHODS

Chondrocytes were divided into control, IL-1β, IL-1β + miR-375 mimic, IL-1β + miR-375 inhibitor, IL-1β + miR-NC (negative control), and IL-1β + miR-375 inhibitor + siJAK2 groups. The chondrocyte proliferation was determined by MTT assay, the superoxide dismutase (SOD) and malondialdehyde (MDA) levels by corresponding kits, and the chondrocyte apoptosis by TUNEL staining. Furthermore, OA mouse models were divided into Sham, OA + miR-NC, and OA + miRNA-375 antagomir groups. The pathological changes were observed, and the expressions of miR-375 and the JAK2/STAT3 pathway were determined by qRT-PCR and Western blotting, respectively.

RESULTS

IL-1β-induced chondrocytes had significant increases in miR-375 and MDA, with decreased proliferation and SOD levels, as compared to the control group. Meanwhile, they also exhibited elevated apoptosis, with upregulations of ADAMTS-5 and MMP-13 and downregulations of COL2A1 and ACAN, as well as decreased p-JAK2/JAK2, p-STAT3/STAT3, and Bcl-2/Bax. However, these changes were significantly improved after transfection with miR-375 inhibitor, but transfection with miR-375 mimic resulted in severer exacerbation. Notably, the improvement of miR-375 inhibitor could be abolished by transfection with siJAK2. Furthermore, miR-375 antagomir significantly alleviated OA progression in OA mice in vivo.

CONCLUSION

MiR-375 suppression enhanced the ability of chondrocyte to antagonize the oxidative stress and maintained the homeostasis of extracellular matrix metabolism to protect chondrocytes from OA via activation of the JAK2/STAT3 pathway, indicating that miR-375 is a potential molecular target for OA treatment.

κ-opioid receptor activation promotes mitochondrial fusion and enhances myocardial resistance to ischemia and reperfusion injury via STAT3-OPA1 pathway

Mitochondrial dynamics, determining mitochondrial morphology, quality and abundance, have recently been implicated in myocardial ischemia and reperfusion (MI/R) injury. The roles of κ-opioid receptor activation in cardioprotection have been confirmed in our previous studies, while the underlying mechanism associated with mitochondrial dynamics remains unclear. This study aims to investigate the effect of κ-opioid receptor activation on the pathogenesis of MI/R and its underlying mechanisms. MI/R mouse model and hypoxia-reoxygenation cardiomyocyte model were established in this study. Mitochondrial dynamics were analyzed with transmission electron microscopy in vivo and confocal microscopy in vitro. STAT3 phosphorylation and OPA1 expression were detected by Western blotting. We show here that κ-opioid receptor activation with its selective receptor agonist U50,488H promoted mitochondrial fusion and enhanced myocardial resistance to MI/R injury, while these protective effects were blockaded by nor-BNI, a selective κ-opioid receptor antagonist. In addition, κ-opioid receptor activation increased STAT3 phosphorylation and OPA1 expression, which were blockaded by nor-BNI. Furthermore, inhibition of STAT3 phosphorylation by stattic, a specific STAT3 inhibitor, repressed the effects of κ-opioid receptor activation on promoting OPA1 expression and mitochondrial fusion, as well as inhibiting cell apoptosis and oxidative stress both in vivo and in vitro during MI/R injury. Overall, our data for the first time provide evidence that κ-opioid receptor activation promotes mitochondrial fusion and enhances myocardial resistance to MI/R injury via STAT3-OPA1 pathway. Targeting the pathway regulated by κ-opioid receptor activation may be a potential therapeutic strategy for MI/R injury.

α7nAChR Deletion Aggravates Myocardial Infarction and Enhances Systemic Inflammatory Reaction via mTOR-Signaling-Related Autophagy

Alpha7 nicotinic acetylcholine receptor (α7nAChR) has been previously reported to play an alleviative role in myocardial infarction (MI). In this study, we investigated its specific mechanism. α7nAChR^-/- mice and its control (α7nAChR^+/+) were used for the study of α7nAChR. Left anterior descending coronary artery occlusion was conducted for the creation of mice MI model and lipopolysaccharide (LPS) was used as inflammatory stressor in murine peritoneal macrophages. Triphenyltetrazolium chloride (TTC) staining and echocardiography was used for the detection of infarct size and cardiac function, respectively. Western blot was conducted for the testing of autophagy-related proteins and enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR) was used for the testing of proinflammatory cytokines. Rapamycin was used for the induction of autophagy through inhibiting mammalian target of rapamycin (mTOR)-related signaling. We found that knocking out α7nAChR enhanced the cardiac infarct size and damaged cardiac function in MI. α7nAChR deficiency increased the levels of several proinflammatory cytokines in serum and spleen from MI mice as well as murine macrophages under inflammatory stress. α7nAChR deletion decreased the level of autophagy in spleen from MI mice and macrophages under inflammatory stress. Rapamycin alleviated the cardiac function and systemic inflammatory reaction in MI mice as well as inflammatory reaction in macrophages under inflammatory stress, which was attenuated by knocking out α7nAChR. Our current study investigated the mechanism of α7nAChR-mediated cardio-protective and anti-inflammatory effect related to mTOR-related autophagy, which might provide a novel insight in the treatment of MI.

Protective Role of mTOR in Liver Ischemia/Reperfusion Injury: Involvement of Inflammation and Autophagy

Liver ischemia/reperfusion (IR) injury is a common phenomenon after liver resection and transplantation, which often results in liver graft dysfunction such as delayed graft function and primary nonfunction. The mammalian target of rapamycin (mTOR) is an evolutionarily highly conserved serine/threonine protein kinase, which coordinates cell growth and metabolism through sensing environmental inputs under physiological or pathological conditions, involved in the pathophysiological process of IR injury. In this review, we mainly present current evidence of the beneficial role of mTOR in modulating inflammation and autophagy under liver IR to provide some evidence for the potential therapies for liver IR injury.

New Insights Into the Role of mTOR Signaling in the Cardiovascular System

The mTOR (mechanistic target of rapamycin) is a master regulator of several crucial cellular processes, including protein synthesis, cellular growth, proliferation, autophagy, lysosomal function, and cell metabolism. mTOR interacts with specific adaptor proteins to form 2 multiprotein complexes, called mTORC1 (mTOR complex 1) and mTORC2 (mTOR complex 2). In the cardiovascular system, the mTOR pathway regulates both physiological and pathological processes in the heart. It is needed for embryonic cardiovascular development and for maintaining cardiac homeostasis in postnatal life. Studies involving mTOR loss-of-function models revealed that mTORC1 activation is indispensable for the development of adaptive cardiac hypertrophy in response to mechanical overload. mTORC2 is also required for normal cardiac physiology and ensures cardiomyocyte survival in response to pressure overload. However, partial genetic or pharmacological inhibition of mTORC1 reduces cardiac remodeling and heart failure in response to pressure overload and chronic myocardial infarction. In addition, mTORC1 blockade reduces cardiac derangements induced by genetic and metabolic disorders and has been reported to extend life span in mice. These studies suggest that pharmacological targeting of mTOR may represent a therapeutic strategy to confer cardioprotection, although clinical evidence in support of this notion is still scarce. This review summarizes and discusses the new evidence on the pathophysiological role of mTOR signaling in the cardiovascular system.

Hydroxysafflor Yellow A mitigated myocardial ischemia/reperfusion injury by inhibiting the activation of the JAK2/STAT1 pathway

Hydroxysafflor Yellow A (HSYA) may reduce ischemia/reperfusion (I/R) injury. However, the underlying molecular mechanisms remain unclear. The present study explored the effect and the mechanisms of HSYA on myocardial injury in vivo and in vitro. Myocardial infarct size was assessed by Evans blue/2,3,5‑triphenyltetrazoliumchloride staining. Levels of cardiac troponin I (cTnI), interleukin‑6 (IL‑6), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured using commercial kits. Alteration of mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) generation was determined by fluorescent signals. Apoptosis was detected by terminal deoxynucleotidyl‑transferase‑mediated dUTP nick‑end labeling staining, flow cytometry assay and caspase‑3 activity. Expression levels of the apoptosis‑associated proteins were detected by reverse transcription quantitative polymerase chain reaction and western blot analysis. In vivo, animals treated with HSYA presented less severe myocardial injury and decreased janus kinase 2 (JAK2)/signal transducer and activator of transcription 1 (STAT1) activity, improved antioxidant capacity and decreased apoptosis. In vitro, compared with the hypoxia (H)/reoxygenation (R) + HSYA group, AG490 and S1491 treatment decreased the releases of cTnI, IL‑6 and LDH and enhanced the resistance to oxidative stress by maintaining MMP and decreasing ROS generation. In addition, AG490 and S1491 were also identified to alleviate the H/R‑induced apoptosis by inhibiting caspase 3 activity and modulating the expression levels of cleaved caspase‑3, tumor necrosis factor receptor superfamily member 6 (Fas), Fas ligand, B‑cell lymphoma 2 (Bcl‑2) and Bcl‑2‑associated X protein. These data suggested that inactivation of the JAK2/STAT1 pathway strengthened the HSYA‑induced protective effect in H/R‑induced myocardial injury. In conclusion, the treatment of HSYA was effective in decreasing IR‑induced myocardial injury, and this may be largely dependent on the JAK2/STAT1 pathway. Therefore, the present study provided a potential strategy to prevent myocardial I/R injury.

Up-regulation of ANXA1 suppresses polymorphonuclear neutrophil infiltration and myeloperoxidase activity by activating STAT3 signaling pathway in rat models of myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is recognized as a major cause of morbidity and mortality which is commonly associated with coronary artery disease. In recent studies, annexin A1 gene (ANXA1) has been discovered to be involved in the treatment for MIRI. In this study, the primary focus was on the molecular mechanism of ANXA1 in polymorphonuclear neutrophil (PMN) infiltration and myeloperoxidase (MPO) activity in rats with MIRI. Initially, microarray analysis was carried out in order to identify differentially expressed genes. Moreover, a rat model of MIRI was established for evaluating the expression of ANXA1, signal transducer and activator of transcription 3 (STAT3) and vascular endothelial growth factor (VEGF) in myocardial tissues. Following this, the ANXA1 vector, siRNA-ANXA1, and Stattic (inhibitor of STAT3 signaling pathway) were utilized for analyzing the regulatory role of ANXA1 in physiological indexes, hemodynamic parameters, inflammatory factors, myocardial infarct size, MPO activity, PMN infiltration, and apoptosis of PMNs. Furthermore, the relationship between ANXA1 and STAT3 signaling pathway was analyzed. Initially, a reduction in the expression of ANXA1, STAT3 and VEGF in myocardial tissues of MIRI rats was found. To elaborate, overexpressed ANXA1 inhibited levels of inflammatory factors, the activation of PMN infiltration, reduced the degree of PMN infiltration, and decreased the apoptosis of PMNs. More importantly, down-regulated ANXA1 inhibited the activation of STAT3 signaling pathway, which thereby suppressed VEGF expression. With this all taken into account, the present study presents that up-regulated ANXA1 inhibits PMN infiltration and MPO activity by activation of STAT3 signaling pathway in rats with MIRI.

Long noncoding RNA C2dat1 protects H9c2 cells against hypoxia injury by downregulating miR-22

Myocardial ischemia is accompanied with hypoxia injury in myocardial cells. Long noncoding RNAs (lncRNA) CAMK2D-associated transcript 1 (C2dat1) C2dat1) has been linked with several ischemic diseases. However, the investigation regarding its role in myocardial ischemia is relatively rare. The aim of this study was to examine the role of C2dat1 in hypoxia response in H9c2 cells. H9c2 cells were subjected to hypoxia to evoke cell damage. Expressions of C2dat1, miR-22, and VEGF in H9c2 cells were altered by transfection, and then cell survival, migration, and invasion were respectively assessed posttransfection. Regulatory relationship between C2dat1, miR-22, and VEGF, as well as the involvement of PI3K/AKT/mTOR and JAK/STAT3 pathways in H9c2 cells injury was then studied. C2dat1 upregulation ameliorated hypoxia injury in H9c2 cells due to the increased viability, migration, and invasion, as well as the decreased apoptosis. miR-22 was negatively regulated by C2dat1. The effects of C2dat1 on H9c2 cells injured by hypoxia were attenuated when miR-22 was overexpressed. VEGF was a target gene of miR-22, and VEGF exerted similar protective effects to C2dat1. Finally, we found that silence of C2dat1 deactivated PI3K/AKT/mTOR and JAK/STAT3 pathways via regulating miR-22 and its downstream gene VEGF. C2dat1-miR-22-VEGF axis could regulate hypoxia injury in H9c2 cells. C2dat1 alleviated hypoxia injury possibly via downregulating miR-22, then upregulating VEGF, which further enhancing the activation of PI3K/AKT/mTOR and JAK/STAT3 pathways.

Apigenin Alleviates Myocardial Reperfusion Injury in Rats by Downregulating miR-15b

Background

We investigated whether apigenin could mitigate myocardial reperfusion injury in rats, and a possible mechanism was proposed.

Material/Methods

The I-R injury model was established in rats along with a sham group as control, and the expressions of microRNA-15b (miR-15b), JAK2, and p-JAK2 in the myocardia of the 2 groups were detected. Apoptosis and reactive oxygen species (ROS) were also detected. Rats in the I-R injury model were divided into 3 groups in vivo: the 1I-R group, the 2I-R+solvent group, and the 3I-R+apigenin group. Expression of miR-15b, JAK2, p-JAK2, STAT3, and p-STAT3 in the myocardia of the 3 groups were detected. ROS content, apoptosis, MDA content, SOD, and CAT activities were detected. Rat myocardial H9C2 cells were cultured in vitro and divided into 5 treatment groups in vitro; expressions of miR-15b, JAK2, p-JAK2, STAT3, and p-STAT3 in H9C2 cells were detected, and the apoptosis and ROS content were detected by flow cytometry.

Results

We found that the increased miR-15b expression during myocardial I-R injury in rats downregulated the expression of JAK2 and activity of the JAK2-STAT3 pathway, promoted myocardial apoptosis and ROS production, and aggravated myocardial I-R injury. Apigenin treatment can downregulate miR-15b expression, increase the expression of JAK2 and the activity of JAK2-STAT3 pathway, reduce myocardial apoptosis and ROS production, and alleviate myocardial I-R injury.

Conclusions

Api treatment downregulated the expression of miR-15b and upregulated the expression of JAK2 and the activity of the JAK2-STAT3 pathway, thereby alleviating myocardial I-R injury, cardiomyocyte apoptosis, and ROS production in vitro.