MicroRNA 26a inhibits HMGB1 expression and attenuates cardiac ischemia-reperfusion injury

Investigation of miR-26a-5p and miR-19a-3p expression levels in angiographically confirmed coronary artery disease

BACKGROUND

MicroRNAs have been found to have an essential role in cardiovascular diseases. In previous experiments, the changed expressions of miR-26a-5p and miR-19a-3p were confirmed in patients with severe coronary atherosclerosis by miRNA microarrays. However, the role of two miRNAs in coronary artery diseases (CAD) still needs to be investigated further. Our current study aimed to analyse two miRNAs in angiographically confirmed CAD and non-CAD with insignificant coronary stenosis. This study aimed to identify the potential diagnostic value of circulating miRNA with CAD.

METHODS

The CAD patients (n = 50) and non-CAD controls (n = 43) were studied. miRNAs (miR-26a-5p and miR-19a-3p) were quantified by TaqMan miRNA assays using real-time PCR. We subsequently assessed the diagnostic value of the miRNAs and correlations of miRNA with clinical parameters. Target prediction tools were utilised to identify miRNA target genes.

RESULTS

The expression of miR-26a-5p was significantly increased in CAD compared to non-CAD controls (p < 0.05). Tertile groups were formed according to the expression levels of miRNAs, and high expression tertile (T3) was compared with low expression tertile (T1). It was found that CAD presence was more prevalent in T3 of miR-26a-5p, and the frequency of diabetes was higher in T3 of miR-19a-3p. There were significant correlations between miRNAs and diabetes risk factors such as HbA1c, glucose levels, and BMI (p < 0.05).

CONCLUSIONS

Our findings show that miR-26a-5p expression is altered in CAD presence while miR-19a-3p expression is different in diabetes. Both miRNAs are closely related to risk factors of CAD, therefore, could be therapeutic targets for CAD treatment.

Impact of the Main Cardiovascular Risk Factors on Plasma Extracellular Vesicles and Their Influence on the Heart's Vulnerability to Ischemia-Reperfusion Injury

The majority of cardiovascular deaths are associated with acute coronary syndrome, especially ST-elevation myocardial infarction. Therapeutic reperfusion alone can contribute up to 40 percent of total infarct size following coronary artery occlusion, which is called ischemia-reperfusion injury (IRI). Its size depends on many factors, including the main risk factors of cardiovascular mortality, such as age, sex, systolic blood pressure, smoking, and total cholesterol level as well as obesity, diabetes, and physical effort. Extracellular vesicles (EVs) are membrane-coated particles released by every type of cell, which can carry content that affects the functioning of other tissues. Their role is essential in the communication between healthy and dysfunctional cells. In this article, data on the variability of the content of EVs in patients with the most prevalent cardiovascular risk factors is presented, and their influence on IRI is discussed.

Downregulation of lncRNA TUG1 attenuates inflammation and apoptosis of renal tubular epithelial cell induced by ischemia-reperfusion by sponging miR-449b-5p via targeting HMGB1 and MMP2

We aimed to evaluate the functions of long non-coding RNA taurine upregulated gene 1 (lncRNA TUG1) in renal ischemia-reperfusion (I/R) injury and identify the potential mechanisms. Pathological changes of renal tissues were examined using H&E staining after mimic renal I/R injury in vivo. The contents of serum renal functional parameters and inflammatory factors were measured. The expression of TUG1 and miR-449b-5p in renal tissues and HK-2 cells stimulated by I/R were detected. Then, the effects of TUG1 silencing on inflammation and apoptosis of cells were evaluated. Dual luciferase reporter assays were executed for determining the correlation between miR-449b-5p and TUG1, high mobility group box 1 (HMGB1), or matrix metalloproteinase 2 (MMP2). Subsequently, cells were co-transfected with miR-449b-5p mimic and pcDNA3.1 TUG1. The levels of inflammation, apoptosis, and the expression of HMGB1 and MMP2 were detected. The results revealed that renal tissues were obviously damaged after I/R accompanied by changes in renal functional markers and inflammatory factors. TUG1 was highly expressed whereas miR-449b-5p was lowly expressed. TUG1 silencing reduced the inflammation and apoptosis. Dual luciferase reporter assays confirmed that miR-449b-5p was a target of TUG1 as well as HMGB1 and MMP2 were direct targets of miR-449b-5p. Meanwhile, miR-449b-5p mimic presented the same results with TUG1 silencing, which were reversed after TUG1 overexpression. Moreover, MMP2 and HMGB1 expression was decreased after miR-449b-5p overexpression while that of was increased after TUG1 overexpression. These findings demonstrated that TUG1 silencing attenuates I/R-induced inflammation and apoptosis via targeting miR-449b-5p and regulating HMGB1 and MMP2 expression.

MicroRNAs in Acute ST Elevation Myocardial Infarction-A New Tool for Diagnosis and Prognosis: Therapeutic Implications

Despite diagnostic and therapeutic advances, coronary artery disease and especially its extreme manifestation, ST elevation myocardial infarction (STEMI), remain the leading causes of morbidity and mortality worldwide. Early and prompt diagnosis is of great importance regarding the prognosis of STEMI patients. In recent years, microRNAs (miRNAs) have emerged as promising tools involved in many pathophysiological processes in various fields, including cardiovascular diseases. In acute coronary syndromes (ACS), circulating levels of miRNAs are significantly elevated, as an indicator of cardiac damage, making them a promising marker for early diagnosis of myocardial infarction. They also have prognostic value and great potential as therapeutic targets considering their key function in gene regulation. This review aims to summarize current information about miRNAs and their role as diagnostic, prognostic and therapeutic targets in STEMI patients.

Sevoflurane Postconditioning Attenuates Hepatic Ischemia-Reperfusion Injury by Limiting HMGB1/TLR4/NF-κB Pathway via Modulating microRNA-142 in vivo and in vitro

Preconditioning of sevoflurane (Sevo) has been demonstrated to protect the liver from ischemia/reperfusion (I/R) injury. However, it is unknown whether it has hepatoprotective when given at the onset of reperfusion (postconditioning), a protocol with more clinical impact. The present study aimed to explore the hepatoprotective effects of Sevo postconditioning against hepatic IR injury in vivo and in vitro and the possible mechanisms. Using a mouse model of hepatic I/R, Sevo postconditioning significantly improved hepatic injury after reperfusion, as demonstrated by reduced AST, ALT, and LDH serum levels and reduced histologic damage in liver tissues. Furthermore, Sevo postconditioning could suppress the apoptosis, inhibit oxidative stress and inflammatory response in liver tissue of HIRI mice, as well as improve the survival rate of HIRI mice. Through analyzing GSE72314 from the gene expression omnibus (GEO) database, it was demonstrated that microRNA (miR)-142 is downregulated by HIRI, which was reversed by Sevo treatment. Further investigation showed that agomiR-142 injection could enhance the hepatoprotective effects of Sevo postconditioning on I/R injury, while antagomiR-142 reversed these effects in mice. Notably, high mobility group box 1 (HMGB1), an important inflammatory factor, was directly targeted by miR-142 in hepatic cells, and we further found that Sevo could inhibit the expression of HMGB1 through up-regulating miR-142 expression in HIRI mice model. In addition, we found that I/R injury induced the activation of TLR4/NF-κB inflammatory pathway was partially suppressed by Sevo postconditioning, and miR-142 mediated the regulatory role of Sevo postconditioning. In line with the in vivo results, Sevo treatment improved the cell viability, inhibited cell apoptosis, oxidative stress and inflammatory response in vitro HIRI model, while these effects were reversed by antagomiR-142 transfection. Collectively, our findings demonstrated that Sevo postconditioning counteracts the downregulation of miR-142 provoked by I/R, in turn decreased the expression of HMGB1, blocking TLR4/NF-κB pathway activation, thus improving hepatic I/R injury. Our data suggest that Sevo may be a valuable alternative anaesthetic agent in liver transplantation and major liver surgeries.

Knockdown of miR-1275 protects against cardiomyocytes injury through promoting neuromedin U type 1 receptor

The present study aimed to assess the role of miR-1275 in cardiac ischemia reperfusion injury. H9 human embryonic stem cell (hESC)-derived cardiomyocytes stimulated by oxygen-glucose deprivation/reoxygenation (OGD/R) were used to simulate myocardial injury in vitro. miR-1275 expression levels in cells were measured by RT-qPCR. The release of lactate dehydrogenase (LDH) and creatine kinase (CK) was examined through LDH and CK ELISA kits. Cell apoptosis was detected through flow cytometry. A Fura-2 Calcium Flux Assay Kit and a Fluo-4 assay kit were used to determine the Ca²⁺ concentration. Expression levels of proteins were tested by Western blotting. The binding effect of miR-1275 and neuromedin U type 1 receptor (NMUR1) was detected by dual-luciferase activity assay. The results showed that miR-1275 was upregulated in OGD/R-stimulated cardiomyocytes. Inhibition of miR-1275 suppressed the increased activity of LDH and CK, cell apoptosis, reactive oxygen species (ROS) production, intracellular Ca²⁺ concentration and sarcoplasmic reticulum (SR) Ca²⁺ leak induced by OGD/R treatment in cardiomyocytes. miR-1275 directly targets 3'UTR of NMUR1 and negatively regulates NMUR1 expression. Silence of NMUR1 abolished the protecting effect of the miR-1275 antagomir on myocardial OGD/R injury. Our study indicated that the miR-1275 antagomir protects cardiomyocytes from OGD/R injury through the promotion of NMUR1.

Sterile inflammation in thoracic transplantation

The life-saving benefits of organ transplantation can be thwarted by allograft dysfunction due to both infectious and sterile inflammation post-surgery. Sterile inflammation can occur after necrotic cell death due to the release of endogenous ligands [such as damage-associated molecular patterns (DAMPs) and alarmins], which perpetuate inflammation and ongoing cellular injury via various signaling cascades. Ischemia-reperfusion injury (IRI) is a significant contributor to sterile inflammation after organ transplantation and is associated with detrimental short- and long-term outcomes. While the vicious cycle of sterile inflammation and cellular injury is remarkably consistent amongst different organs and even species, we have begun understanding its mechanistic basis only over the last few decades. This understanding has resulted in the developments of novel, yet non-specific therapies for mitigating IRI-induced graft damage, albeit with moderate results. Thus, further understanding of the mechanisms underlying sterile inflammation after transplantation is critical for identifying personalized therapies to prevent or interrupt this vicious cycle and mitigating allograft dysfunction. In this review, we identify common and distinct pathways of post-transplant sterile inflammation across both heart and lung transplantation that can potentially be targeted.

Non-coding RNAs participate in the ischemia-reperfusion injury

Ischemia, being defined as blood supply deficiency is involved in the pathogenesis of a number of life-threatening conditions such as myocardial infarction and cerebral stroke. Assessment of the molecular pathology of these conditions has led to identification of the role of reperfusion in induction and aggravation of tissue injury and necrosis. Thus, the term "ischemia/ reperfusion (I/R) injury" has been introduced. This process involves aberrant regulation of the mitochondrial function, apoptotic and autophagic pathways and signal transducers. More recently, non-coding RNAs including long non-coding RNAs (lncRNAs) ad microRNAs (miRNAs) have been shown to influence I/R injury. Animal studies and clinical investigations have shown up-/down-regulation of tens of lncRNAs and miRNAs in this process. In the current study, we summarize the role of these transcripts in the pathophysiology of I/R injury and their potential as biomarkers for detection of extent of tissue injury.

Necroptosis in renal ischemia/reperfusion injury: A major mode of cell death?

Ischemic acute kidney injury (AKI) is a frequent complication resulting from a myriad of conditions that decrease effective arterial blood volume to the kidneys including myocardial ischemia, sepsis, and hypovolemia. Following acute ischemic insult, restoration of renal blood flow inevitably leads to the aggravation of renal injury due to a widely researched condition known as ischemia/reperfusion (I/R) injury. For decades, apoptosis and necrosis have been proposed as being the two cell death pathways responsible for the pathogenesis of renal ischemic AKI. There is recent evidence to show that necrosis could be regulated in a caspase-independent manner. This regulated or programmed necrosis is termed necroptosis. Necroptotic markers such as receptor-interacting serine/threonine-protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain like pseudokinase (MLKL) have been identified in both in vitro and in vivo models of renal I/R injury, suggesting that necroptosis might be a potential therapeutic target to limit renal I/R injury. In this review, available reports from in vitro, in vivo and clinical reports regarding the association of necroptosis in renal I/R injury, along with its therapeutic potential, has been comprehensively summarized and discussed. Understanding this contributory mechanism could pave ways to improve therapeutic strategies in combating renal I/R injury.

Effects of Circulating HMGB-1 and Histones on Cardiomyocytes-Hemadsorption of These DAMPs as Therapeutic Strategy after Multiple Trauma

Background and purpose: The aim of the study was to determine the effects of post-traumatically released High Mobility Group Box-1 protein (HMGB1) and extracellular histones on cardiomyocytes (CM). We also evaluated a therapeutic option to capture circulating histones after trauma, using a hemadsorption filter to treat CM dysfunction. Experimental Approach: We evaluated cell viability, calcium handling and mitochondrial respiration of human cardiomyocytes in the presence of HMGB-1 and extracellular histones. In a translational approach, a hemadsorption filter was applied to either directly eliminate extracellular histones or to remove them from blood samples obtained from multiple injured patients. Key results: Incubation of human CM with HMGB-1 or histones is associated with changes in calcium handling, a reduction of cell viability and a substantial reduction of the mitochondrial respiratory capacity. Filtrating plasma from injured patients with a hemadsorption filter reduces histone concentration ex vivo and in vitro, depending on dosage. Conclusion and implications: Danger associated molecular patterns such as HMGB-1 and extracellular histones impair human CM in vitro. A hemadsorption filter could be a therapeutic option to reduce high concentrations of histones.

Vascular Signaling in Allogenic Solid Organ Transplantation - The Role of Endothelial Cells

Graft rejection remains the major obstacle after vascularized solid organ transplantation. Endothelial cells, which form the interface between the transplanted graft and the host’s immunity, are the first target for host immune cells. During acute cellular rejection endothelial cells are directly attacked by HLA I and II-recognizing NK cells, macrophages, and T cells, and activation of the complement system leads to endothelial cell lysis. The established forms of immunosuppressive therapy provide effective treatment options, but the treatment of chronic rejection of solid organs remains challenging. Chronic rejection is mainly based on production of donor-specific antibodies that induce endothelial cell activation—a condition which phenotypically resembles chronic inflammation. Activated endothelial cells produce chemokines, and expression of adhesion molecules increases. Due to this pro-inflammatory microenvironment, leukocytes are recruited and transmigrate from the bloodstream across the endothelial monolayer into the vessel wall. This mononuclear infiltrate is a hallmark of transplant vasculopathy. Furthermore, expression profiles of different cytokines serve as clinical markers for the patient’s outcome. Besides their effects on immune cells, activated endothelial cells support the migration and proliferation of vascular smooth muscle cells. In turn, muscle cell recruitment leads to neointima formation followed by reduction in organ perfusion and eventually results in tissue injury. Activation of endothelial cells involves antibody ligation to the surface of endothelial cells. Subsequently, intracellular signaling pathways are initiated. These signaling cascades may serve as targets to prevent or treat adverse effects in antibody-activated endothelial cells. Preventive or therapeutic strategies for chronic rejection can be investigated in sophisticated mouse models of transplant vasculopathy, mimicking interactions between immune cells and endothelium.

MiR-433 Regulates Myocardial Ischemia Reperfusion Injury by Targeting NDRG4 Via the PI3K/Akt Pathway

BACKGROUND AND PURPOSE

Myocardial ischemia reperfusion (IR) injury is a serious issue in the treatment of myocardial infarction. MiR-433 is upregulated in myocardial IR injury, but its specific effects remain unclear. In this study, we explored the effect and mechanism of miR-433 in myocardial IR injury.

METHODS

The expression of miR-433 was measured by qRT-PCR. H9c2 cells were transfected with miR-433 mimic and inhibitor after exposure to HR, respectively. Cell viability was detected by MTT. Cell apoptosis was measured by flow cytometry. Protein expression was assessed by western blot. Dual-luciferase reporter assay was performed to assess the target reaction between miR-433 and NDRG4. In vivo rat model of IR was used, and antagomiR-433 was injected to IR rats.

RESULTS

The qRT-PCR results showed that miR-433 expression increased in H9c2 cardiomyocytes after exposure to HR. Transfection with miR-433 inhibitor significantly increased cell viability, reduced LDH and apoptosis, downregulated Bax level, and upregulated Bcl-2 level. In contrast, the miR-433 mimic significantly augmented the HR-induced effects. Dual-luciferase reporter assay and western blot analysis suggested that miR-433 directly targeted NDRG4. NDRG4 silencing abrogated the protection of miR-433 inhibition on HR injury in H9c2 cells. It also reversed PI3K/Akt pathway activation that was induced by miR-433 inhibition. MiR-433 inhibition significantly decreased CK-MB and LDH serum level in IR rats. And NDRG4, p-PI3K, and p-Akt protein expression was elevated by antagomiR-433 injection in vivo.

CONCLUSION

MiR-433 regulated myocardial IR injury by targeting NDRG4 and modulating PI3K/Akt signal pathway.

miR-26a attenuates cardiac apoptosis and fibrosis by targeting ataxia-telangiectasia mutated in myocardial infarction

Apoptosis and fibrosis play a vital role in myocardial infarction (MI) induced tissue injury. Although microRNAs have been the focus of many studies on cardiac apoptosis and fibrosis in MI, the detailed effects of miR-26a is needed to further understood. The present study demonstrated that miR-26a was downregulated in ST-elevation MI (STEMI) patients and oxygen-glucose deprivation (OGD)-treated H9c2 cells. Downregulation of miR-26a was closely correlated with the increased expression of creatine kinase, creatine kinase-MB and troponin I in STEMI patients. Further analysis identified that ataxia-telangiectasia mutated (ATM) was a target gene for miR-26a based on a bioinformatics analysis. miR-26a overexpression effectively reduced ATM expression, apoptosis, and apoptosis-related proteins in OGD-treated H9c2 cells. In a mouse model of MI, the expression of miR-26a was significantly decreased in the infarct zone of the heart, whereas apoptosis and ATM expression were increased. miR-26a overexpression effectively reduced ATM expression and cardiac apoptosis at Day 1 after MI. Furthermore, we demonstrated that overexpression of miR-26a improved cardiac function and reduced cardiac fibrosis by the reduced expression of collagen type I and connective tissue growth factor (CTGF) in mice at Day 14 after MI. Overexpression of miR-26a or ATM knockdown decreased collagen I and CTGF expression in cultured OGD-treated cardiomyocytes. Taken together, these data demonstrate a prominent role for miR-26a in linking ATM expression to ischemia-induced apoptosis and fibrosis, key features of MI progression. miR-26a reduced MI development by affecting ATM expression and could be targeted in the treatment of MI.

LncRNA TUG1 protects against cardiomyocyte ischaemia reperfusion injury by inhibiting HMGB1

The aim of this study was to investigate whether lncRNA TUG1 could mediate the progression of ischemia-reperfusion injury following acute myocardial infraction. Mouse cardiomyocytes HL-1 cells were subjected to oxygen glucose deprivation followed by reperfusion (OGD/R) to induce myocardial I/R injury. The expression of TUG1 was detected by real-time PCR. Overexpression or down expression of TUG1 was performed in mouse HL-1 cardiomyocytes. The myocardial cell viability and apoptosis were respectively detected. In addition, the expression levels of inflammatory factors, apoptosis-related proteins and HMGB1 proteins were detected. Besides, an inhibitor of HMGB1 was used to treat cells to verify the relationship between TUG1 and HMGB1 protein. The expression of TUG1 was significantly up-regulated in OGD/R-induced myocardial HL-1 cells. The overexpression of TUG1-induced inflammation and apoptosis in OGD-R-induced myocardial HL-1 cells. Knock down of TUG1 protected OGD/R-induced myocardial I/R injury by inhibiting HMGB1 expression. Suppression of lncRNA TUG1 may prevent myocardial I/R injury following acute myocardial infarction via inhibiting HMGB1 expression.

Paeonol attenuates inflammation by targeting HMGB1 through upregulating miR-339-5p

Sepsis is a life-threatening disease caused by infection. Inflammation is a key pathogenic process in sepsis. Paeonol, an active ingredient in moutan cortex (a Chinese herb), has many pharmacological activities, such as anti-inflammatory and antitumour actions. Previous studies have indicated that paeonol inhibits the expression of HMGB1 and the transcriptional activity of NF-κB. However, its underlying mechanism is still unknown. In this study, microarray assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results confirmed that paeonol could significantly up-regulate the expression of miR-339-5p in RAW264.7 cells stimulated by LPS. Dual-luciferase assays indicated that miR-339-5p interacted with the 3′ untranslated region (3′-UTR) of HMGB1. Western blot, immunofluorescence and enzyme-linked immunosorbent assay (ELISA) analyses indicated that miR-339-5p mimic and siHMGB1 both negatively regulated the expression and secretion of inflammatory cytokines (e.g., HMGB1, IL-1β and TNF-α) in LPS-induced RAW264.7 cells. Studies have confirmed that IKK-β is targeted by miR-339-5p, and we further found that paeonol could inhibit IKK-β expression. Positive mutual feedback between HMGB1 and IKK-β was observed when we silenced HMGB1 or IKK-β. These results indicated that paeonol could attenuate the inflammation mediated by HMGB1 and IKK-β by upregulating miR-339-5p expression. In addition, we constructed CLP model mice by cecal ligation and puncture. Paeonol was used to intervene to investigate its anti-inflammatory effect in vivo. The results showed that paeonol could improve the survival rate of sepsis mice and protect the kidney of sepsis mice.

miR- 26a Sensitizes Melanoma Cells To Dabrafenib Via Targeting HMGB1-Dependent Autophagy Pathways

Background

Melanoma is known as the most aggressive and lethal type of cutaneous cancer due to its rapid development of drug resistance to chemotherapy drugs.

Methods

In our study, we conducted a variety of studies, including quantitative PCR, Western blot, and autophagy and apoptosis assays to investigate the involvement of miR-26a and HMGB1 in modulation of dabrafenib sensitivity in human melanoma cell lines.

Results

Our studies revealed that the expressions of miR-26a and HMGB1 were altered in two melanoma cell lines after dabrafenib treatment. Additionally, dabrafenib caused autophagy in melanoma and this autophagic process was regulated by miR-26a via modifying HMGB1 expression. Furthermore, silencing HMGB1-inhibited autophagy induced by dabrafenib in melanoma cells. Last, we verified that treatment with a miR-26a mimic and HMGB1 shRNA could increase the efficacy of dabrafenib in melanoma cells.

Conclusion

Taken together, we showed that miR-26a is involved in the regulation of dabrafenib efficacy via a HMGB1-dependent autophagy pathway in melanoma cells. These results shed light on a novel treatment for conventional dabrafenib-based chemotherapy for melanoma.

Long noncoding MIAT acting as a ceRNA to sponge microRNA-204-5p to participate in cerebral microvascular endothelial cell injury after cerebral ischemia through regulating HMGB1

This study is applied to the investigation of the long noncoding RNA myocardial infarction associated transcript's (MIAT's) role in regulating the expression of high-mobility group box 1 (HMGB1) in cerebral microvascular endothelial cell (CMEC) injury after cerebral ischemia by serving as a competitive endogenous RNA (ceRNA) to sponge microRNA-204-5p (miR-204-5p). The cerebral ischemia model of middle cerebral artery occlusion (MCAO) in rats was established by the suture method, in which rats were injected with empty plasmids and MIAT siRNA plasmids. The cerebral ischemia injury model in vitro was established through oxygen glucose deprivation (OGD) in primary cultured CMECs in rats. The cells were transfected with empty plasmids and MIAT siRNA plasmids. The MIAT/miR-204-5p/HMGB1 axis' function in damage and angiogenesis of CMECs were explored. The binding site between MIAT and miR-204-5p along with that between miR-204-5p and HMGB1 was determined. MIAT was overexpressed in MCAO rats' brain tissue and inhibited MIAT attenuated the injury of brain tissue in MCAO rats. Inhibition of MIAT promoted angiogenesis, promoted miR-204-5p expression and inhibited HMGB1 expression in brain tissue of MCAO rats. Inhibition of MIAT reduced CMEC damage, induced angiogenesis of CMECs, increased the number of surviving neurons, promoted miR-204-5p expression and inhibited HMGB1 expression in CMECs treated with OGD. MIAT promoted HMGB1 expression by competitive binding to miR-204-5p to regulate the injury of CMECs after cerebral ischemia. Our study showed that MIAT promoted HMGB1 expression by competitively binding to miR-204-5p to regulate the injury of CMECs after cerebral ischemia.

miR-26a prevents neural stem cells from apoptosis via β-catenin signaling pathway in cardiac arrest-induced brain damage

Neural stem cells (NSCs) transplantation is one of the most promising strategies for the treatment of CA-induced brain damage. The transplanted NSCs could differentiate into new neuron and replace the damaged one. However, the poor survival of NSCs in severe hypoxic condition is the limiting step to make the best use of this kind of therapy. In the present study, we investigated whether the overexpression of miR-26a improves the survival of NSCs in hypoxic environment in vitro and in vivo. In vitro hypoxia injury model is established in NSCs by CoCl₂ treatment, and in vivo cardiac arrest (CA) model is established in Sprague-Dawley (SD) rats. Quantitative real-time polymerase chain reaction is used to detect the mRNA level and Western blot is used to examine the protein level of indicated genes. TUNEL staining and flow cytometry are applied to evaluate apoptosis. Dual-luciferase reporter assay is utilized to analyze the target gene of miR-26a. The expression of miR-26a is reduced in both in vitro and in vivo hypoxic model. MiR-26a directly targets 3′-UTR of glycogen synthase kinase 3β (GSK-3β), resulting in increased β-catenin expression and decreased apoptosis of NSCs. Overexpression of miR-26a in transplanted NSCs improves the survival of NSCs and neurological function in CA rats. MiR-26a prevents NSCs from apoptosis by activating β-catenin signaling pathway in CA-induced brain damage model. Modulating miR-26a expression could be a potential strategy to attenuate brain damage induced by CA.

Overexpression of miR-758 inhibited proliferation, migration, invasion, and promoted apoptosis of non-small cell lung cancer cells by negatively regulating HMGB

Non-small cell lung cancer (NSCLC) is one of the most fatal types of cancer with significant mortality and morbidity worldwide. MicroRNAs (miRs) have been confirmed to have positive functions in NSCLC. In the present study, we try to explore the role of miR-758 in proliferation, migration, invasion, and apoptosis of NSCLC cells by regulating high-mobility group box (HMGB) 3 (HMGB3.) NSCLC and adjacent tissues were collected. Reverse transcription quantitative PCR (RT-qPCR) was employed to detect expression of miR-758 and HMGB3 in NSCLC and adjacent tissues, in BEAS-2B cells and NSCLC cell lines. The targetted relationship between miR-758 and HMGB3 was identified by dual luciferase reporter gene assay. The effects of miR-758 on proliferation, migration, invasion, cell cycle, and apoptosis of A549 cells. MiR-758 expression was lower in NSCLC tissues, which was opposite to HMGB3 expression. The results also demonstrated that miR-758 can target HMGB3. The cells transfected with miR-758 mimic had decreased HMGB3 expression, proliferation, migration, and invasion, with more arrested cells in G₁ phase and increased apoptosis. Our results supported that the overexpression of miR-758 inhibits proliferation, migration, and invasion, and promotes apoptosis of NSCLC cells by negative regulating HMGB2. The present study may provide a novel target for NSCLC treatment.

Downregulation of MALAT1 alleviates saturated fatty acid-induced myocardial inflammatory injury via the miR-26a/HMGB1/TLR4/NF-κB axis

Purpose: The increased level of saturated fatty acids (SFAs) is found in patients with diabetes, obesity, and other metabolic disorders. SFAs can induce lipotoxic damage to cardiomyocytes, but the mechanism is unclear. The long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acts as a key regulator in palmitic acid (PA)-induced hepatic steatosis, but its role in PA-induced myocardial lipotoxic injury is still unknown. The aim of this study was to explore the role and underlying mechanism of MALAT1 in PA-induced myocardial lipotoxic injury. Methods: MALAT1 expression in PA-treated human cardiomyocytes (AC16 cells) was detected by RT-qPCR. The effect of MALAT1 on PA-induced myocardial injury was measured by Cell Counting Kit-8, lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) assays. Apoptosis was detected by flow cytometry. The activities of cytokines and nuclear factor (NF)-κB were detected by enzyme-linked immunosorbent assay. The interaction between MALAT1 and miR-26a was evaluated by a luciferase reporter assay and RT-qPCR. The regulatory effects of MALAT1 on high mobility group box 1 (HMGB1) expression were evaluated by RT-qPCR and western blotting. Results: MALAT1 was significantly upregulated in cardiomyocytes after PA treatment. Knockdown of MALAT1 increased the viability of PA-treated cardiomyocytes, decreased apoptosis, and reduced the levels of LDH, CK-MB, TNF-α, and IL-1β. Moreover, we found that MALAT1 specifically binds to miR-26a and observed a reciprocal negative regulatory relationship between these factors. We further found that the downregulation of MALAT1 represses HMGB1 expression, thereby inhibiting the activation of the Toll-like receptor 4 (TLR4)/NF-κB-mediated inflammatory response. These repressive effects were rescued by an miR-26a inhibitor. Conclusion: We demonstrate that MALAT1 is induced by SFAs and its downregulation alleviates SFA-induced myocardial inflammatory injury via the miR-26a/HMGB1/TLR4/NF-κB axis. Our findings provide new insight into the mechanism underlying myocardial lipotoxic injury.

The exogenous delivery of microRNA-449b-5p using spermidine-PLGA nanoparticles efficiently decreases hepatic injury

A notable liver ischemia/reperfusion (I/R) injury is observed during liver transplantation, shock, trauma and other systemic diseases. The main aim of the present study was to evaluate the fact that HMGB1 acts as an early mediator of inflammation in hepatic injury and the potential of the miR-449b-5p mimic in the restoration of liver disorders. Herein, a miR-449b-5p-loaded spermidine/PLGA nanoparticle system was successfully formulated to improve the systemic delivery and performance of encapsulated miRNA. The major findings of the present study were as follows: (i) the HMGB1 levels were elevated upon the occurrence of I/R in vitro and in vivo; (ii) the inhibition of HMGB1 prevented the spread of inflammation; (iii) miR-449b-5p (PN-miR mimic) increased the cell viability of hepatic cells and decreased cell apoptosis; and (iv) the protective ability of the PN-miR mimic was attributed to the inhibition of the pNF-κB and p-p65 pathways. Compared to the case of the I/R group, the serum AST and ALT levels were significantly reduced in the group treated with miR-449b-5p (PN-miR mimic), indicating the extent of reduction in liver inflammation. The present study highlighted the importance of miR-449b-5p in the treatment of hepatic injury and could serve as a guide to effectively attenuate liver disorders. The application of the proposed nanoparticle system in the systemic delivery of miR-449b-5p further enhances the prospect of this treatment strategy.

The present study highlights the importance of miR-449b-5p in the inhibition of HMGB1 and thereby it's treatment potential in hepatic injury.

HMGB1 and repair: focus on the heart

High-mobility group box 1 (HMGB1) is one of the most abundant proteins in eukaryotes and the best characterized damage-associated molecular pattern (DAMP). The biological activities of HMGB1 depend on its subcellular location, context and post-translational modifications. Inside the nucleus, HMGB1 is engaged in many DNA events such as DNA repair, transcription regulation and genome stability; in the cytoplasm, its main function is to regulate the autophagic flux while in the extracellular environment, it possesses more complicated functions and it is involved in a large variety of different processes such as inflammation, migration, invasion, proliferation, differentiation and tissue regeneration. Due to this pleiotropy, the role of HMGB1 has been vastly investigated in various pathological diseases and a large number of studies have explored its function in cardiovascular pathologies. However, in this contest, the precise mechanism of action of HMGB1 and its therapeutic potential are still very controversial since is debated whether HMGB1 is involved in tissue damage or plays a role in tissue repair and regeneration. The main focus of this review is to provide an overview of the effects of HMGB1 in different ischemic heart diseases and to discuss its functions in these pathological conditions.

Nrf2 activation and down-regulation of HMGB1 and MyD88 expression by amnion membrane extracts in response to the hypoxia-induced injury in cardiac H9c2 cells

BACKGROUND

human Amniotic Membrane (hAM) extracts contain bioactive molecules such as growth factors and cytokines. Studies have confirmed the ability of hAM in reduction of post-operative dysfunction in patients with cardiac surgery. However, the function of Amniotic Membrane Proteins (AMPs), extracted from hAM, against hypoxia-induced H9c2 cells injury have never been investigated. In this study, we aimed to appraise the protective impact of AMPs on H9c2 cells under hypoxia condition.

METHODS

Cardiomyocyte cells were pre-incubated with AMPs and subjected to 24 h hypoxia to elucidate its effects on expression of Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1(HO-1). Furthermore, the high mobility group box-1 (HMGB1) and Myeloid differentiation primary response 88 (MyD88) expressions were detected by qPCR and western-blotting. The mitochondrial membrane potential (ΔΨm) was estimated by JC-1 using fluorescent microscopy and fluorimetry. Moreover, the cell apoptosis and intracellular calcium levels were measured by flow cytometry.

RESULTS

Pre-treatment of AMPs resulted in significant induction in cell viability and decreased the LDH release under hypoxic condition in H9c2 cells. Accordingly, these protective effects of AMPs were associated with a reduction in apoptosis rates and intracellular Ca2+, meanwhile, ΔΨm was increased. Pre-treatment with AMPs resulted in degradation of HMGB1 and MyD88 levels and depicted pro-survival efficacy of AMPs against hypoxia-induced cell damage through induction of HO-1 and Nrf2.

CONCLUSION

The data indicated that AMPs mediated HO-1 regulation by Nrf2 activation and plays critical protective effects in hypoxia-induced H9c2 injury in vitro by the inhibition of myocardial HMGB1 and MyD88 inflammatory cascade.

Downregulation of growth arrest‑specific transcript 5 alleviates palmitic acid‑induced myocardial inflammatory injury through the miR‑26a/HMGB1/NF‑κB axis

Palmitic acid (PA) can induce lipotoxic damage to cardiomyocytes, although its precise mechanism of action has not been completely elucidated. Growth arrest‑specific transcript 5 (GAS5) is a long noncoding RNA that serves a regulatory role in several pathological processes, including tumorigenesis, stroke, cardiac fibrosis and osteoarthritis; however, its role in PA‑induced myocardial injury remains elusive. The present study aimed to explore the role and underlying mechanism of GAS5 on PA‑induced myocardial injury. The expression of GAS5 in PA‑treated cardiomyocytes (H9c2 cells) was detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), and its effects on PA‑induced myocardial injury were measured by Cell Counting Kit‑8 and lactate dehydrogenase (LDH) assays. The activities of cytokines and nuclear factor (NF)‑κB were also detected by enzyme‑linked immunosorbent assay, while interactions between GAS5 and microRNA (miR)‑26a were evaluated by luciferase reporter assay and RT‑qPCR. The regulation of GAS5 on high mobility group box 1 (HMGB1) expression was detected by RT‑qPCR and western blotting. The results demonstrated that GAS5 was significantly upregulated in cardiomyocytes following treatment with PA. GAS5‑knockdown increased the viability of PA‑treated cardiomyocytes and reduced the activity of LDH, tumor necrosis factor‑α and interleukin‑1β. Furthermore, the present study identified that GAS5 specifically binds to miR‑26a, and a reciprocal negative regulation exists between the two. The present study also demonstrated that GAS5 downregulation inhibited HMGB1 expression and NF‑κB activation, while these suppressive effects were mediated by miR‑26a. In conclusion, the present study demonstrated that PA can induce GAS5 expression and that the downregulation of GAS5 alleviated PA‑induced myocardial inflammatory injury through the miR‑26a/HMGB1/NF‑κB axis. These data may provide a novel insight into the mechanism of myocardial lipotoxic injury.

Effect of microRNA-26a on vascular endothelial cell injury caused by lower extremity ischemia-reperfusion injury through the AMPK pathway by targeting PFKFB3

Vascular endothelial cell (VEC) dysfunction plays an important role in the ischemia-reperfusion injury (IRI)-related diseases, and microRNAs (miRNAs) are key factors during this process. We conducted this study to investigate whether miRNA-26a (miR-26a) has effect on the IRI-induced VEC injury via the AMPK pathway by targeting 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3). IRI rat models were successfully constructed by an abdominal incision. Additionally, the cultured VECs were further treated with miR-26a mimic or inhibitor, and si-PFKFB3. Both the reverse-transcription quantitative polymerase chain reaction and the western blot assay method were carried out to examine the expressions of PFKFB3, endothelial nitric oxide synthase (eNOS), and 5'-adenosine monophosphate-activated protein kinase (AMPK) α1, as well as the extent of the AMPK α1 phosphorylation levels in vascular tissues. Circulating endothelial cell (CEC), von Willebrand factor (VWF), thrombomodulin (TM), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), and endothelin (ET) were all measured. In the rat model of an IRI, a poorly expressed miR-26a and contrarily highly expressed PFKFB3 were identified in vascular tissues. In response to an overexpression of miR-26a or to the PFKFB3 gene silencing, decreased CEC number, TM, VWF, MDA, and ET contents, increased AMPK α1, and eNOS levels, as well as the extent of AMPK α1 phosphorylation coordinate with both increased SOD and NO contents based on the restoration of the AMPK pathway. Overexpression of the miR-26a or si-PFKFB3 provides an elevation in cell proliferation. Our study suggests that the miR-26a RNA alleviates lower extremity IRI-induced VEC injury in rats through the activation of the AMPK pathway by inhibiting PFKFB3.

Detection of Myocardial Injury Using miRNAs Expression as Genetic Biomarkers in Acute Cardiac Care

Cardiovascular disease is a leading cause of death globally. At present, there are many ways to diagnose this pathophysiology. The greatest disadvantages related to current biomarkers are their low specificity, low selectivity and low accuracy. A new method, extensively studied recently, is the expression of miRNAs, used as genetic biomarkers for the early diagnosis of cardiovascular diseases. This paper presents an update of miRNAs species expression that can serve as early diagnostic biomarkers and for the continuous monitoring of patients with cardiovascular disease.