Upregulation of microRNA-451 attenuates myocardial I/R injury by suppressing HMGB1

Targeting high-mobility-group-box-1-mediated inflammation: a promising therapeutic approach for myocardial infarction

Myocardial ischemia, resulting from coronary artery blockage, precipitates cardiac arrhythmias, myocardial structural changes, and heart failure. The pathophysiology of MI is mainly based on inflammation and cell death, which are essential in aggravating myocardial ischemia and reperfusion injury. Emerging research highlights the functionality of high mobility group box-1, a non-histone nucleoprotein functioning as a chromosomal stabilizer and inflammatory mediator. HMGB1's release into the extracellular compartment during ischemia acts as damage-associated molecular pattern, triggering immune reaction by pattern recognition receptors and exacerbating tissue inflammation. Its involvement in signaling pathways like PI3K/Akt, TLR4/NF-κB, and RAGE/HMGB1 underscores its significance in promoting angiogenesis, apoptosis, and reducing inflammation, which is crucial for MI treatment strategies. This review highlights the complex function of HMGB1 in the pathogenesis of myocardial infarction by summarizing novel findings on the protein in ischemic situations. Understanding the mechanisms underlying HMGB1 could widen the way to specific treatments that minimize the severity of MI and enhance patient outcomes.

Postmortem analyses of myocardial microRNA expression in sepsis

BACKGROUND

Sepsis can lead to myocardial depression, playing a significant role in sepsis pathophysiology, clinical care, and outcome. To gain more insight into the pathophysiology of the myocardial response in sepsis, we investigated the expression of microRNA in myocardial autopsy specimens in critically ill deceased with sepsis and non-septic controls.

MATERIALS AND METHODS

In this retrospective observational study, we obtained myocardial tissue samples collected during autopsy from adult patients deceased with sepsis (n = 15) for routine histological examination. We obtained control myocardial tissue specimens (n = 15) from medicolegal autopsies of cadavers whose cause of death was injury or who were found dead at home and the cause of death was coronary artery disease with sudden cardiac arrest. RNA was isolated from formalin-fixed paraffin- embedded (FFPE) cardiac samples using the RecoverAll Total Nucleic Acid Isolation Kit for FFPE (Invitrogen). Differentially expressed miRNAs were identified using edgeR v3.32. MicroRNA was considered up- or down-regulated if the false discovery rate was < 0.05 and logarithmic fold change (log2FC) ≥ 1 for up-regulated or log2FC ≤ -1 for down-regulated miRNAs. The mean difference and 95% confidence interval (CI) were calculated for normalized read counts. Predicted miRNA targets were retrieved using Ingenuity Pathway Analysis (IPA) software, and pathway enrichment and classification were performed using PantherDB. For miRNA - mRNA interaction analysis, differentially expressed genes were analyzed by 3`mRNA sequencing.

RESULTS

Differential expression analysis identified a total of 32 miRNAs in the myocardial specimens. Eight miRNAs had a significant change in the mean difference based on the 95% CI, with the largest increase in mean counts in septic samples with hsa-miR-12136 and the highest fold change with hsa-miR-146b-5p. The threshold for down-regulated miRNAs in sepsis compared to controls was obtained with hsa-miR-144-5p and hsa-miR-451a, with the latter having the largest decrease in mean counts and fold decrease. The miRNA - mRNA interaction analysis identified eight miRNAs with target genes also differentially expressed in septic hearts. The highest number of potential targets were identified for hsa-miR-363-3p.

CONCLUSIONS

Several regulatory miRNAs were up-or down-regulated in the myocardial tissue of patients deceased with sepsis compared to non-septic subjects. The predicted target genes of miRNAs and miRNA-mRNA interaction analysis are associated with biological functions related to cardiovascular functions, cell viability, cell adhesion, and regulation of inflammatory and immune response.

β stimulator induces upregulation of miR-27a in the rat heart one hour after the injection

MicroRNAs (miRs) are non-coding small RNA containing 18 to 22 nucleotides, that post-transcriptionally regulates mRNA expression. Chronic injection of β stimulator is known to induce cardiac injury and change of miRs expression level in the heart with some pathological changes such as fibrosis, heart failure, myocardial infarction. We investigated the changes in the expression level of miRs in the rat heart one hour after isoproterenol (a β stimulator) injection. Male Sprague-Dawley rats were assigned into three groups and received subcutaneous injection of normal sarin (NS) or 0.1 mg/kg isoproterenol (ISO-0.1) or 10 mg/kg isoproterenol (ISO-10). After one hour, we collected their heart and plasma. Total RNA was extracted from the left ventricle and used for deep miRNA sequencing. Based on the results of miRNA sequencing, we performed real-time polymerase chain reaction (RT-PCR) using 8 miR primers. Cardiac injury was evaluated by hematoxylin and eosin, and phosphotungstic acid-hematoxylin staining and measuring troponin-I levels in plasma. Troponin-I was significantly increased in ISO-0.1 and ISO-10 groups, but histological observation did not show any cardiac necrosis. miRNA sequencing identified 14 upregulated miRs and 12 downregulated miRs. Of the 26 miRs, RT-PCR confirmed miR-144-3p/5p and miR-451-5p were decreased, and that 5 miRs (miR-27a-5p, miR-30b-3p, miR-92a-1-5p, miR-132-5p, miR-582-3p) were upregulated. This study showed that β stimulus causes downregulation of miR-144/451 cluster and increases expression of five 5 miRs in the heart, especially 6.5-fold upregulation of miR-27a-5p as early as one hour after isoproterenol injection. Therefore, these miRs might be good biomarkers for cardiac injury.

CCCTC-binding factor-mediated microRNA-340-5p suppression aggravates myocardial injury in rats with severe acute pancreatitis through activation of the HMGB1/TLR4 axis

BACKGROUND

Severe acute pancreatitis (SAP) is a life-threatening disorder associated with multisystem organ failure. This study aimed to investigate the function of high mobility group box 1 (HMGB1) in SAP-induced myocardial injury.

METHODS

A rat model with SAP was induced. The pathological changes in rat pancreatic and cardiac tissues were examined by HE staining. Cardiomyocyte apoptosis in rat cardiac tissues, and the serum levels of myocardial injury markers and pro-inflammatory cytokines were examined. Rat primary cardiomyocytes were treated with H2O2 for in vitro experiments. The regulatory molecules of HMGB1 were predicted by bioinformatics analysis. Altered expression of HMGB1, microRNA (miR)-340-5p and CCCTC-binding factor (CTCF) was introduced in rats or cells to investigate their roles in myocardial injury.

RESULTS

CTCF and HMGB1 were highly expressed but miR-340-5p was poorly expressed in cardiac tissues of rats with SAP. HMGB1 silencing reduced toll-like receptor 4 (TLR4) expression to promote proliferation and reduce apoptosis of H2O2-treated cardiomyocytes. miR-340-5p targeted HMGB1 mRNA, while CTCF suppressed miR-340-5p transcription. CTCF upregulation or miR-340-5p downregulation blocked the effects of HMGB1 silencing on cardiomyocytes. In vivo, CTCF silencing alleviated injury in rat pancreatic and cardiac tissues and reduced the expression of creatine kinase-MB (CK-MB), lactic dehydrogenase, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in rat serum. But further overexpression of HMGB1 or inhibition of miR-340-5p aggravated the symptoms in rats.

CONCLUSION

This study demonstrated that CTCF reduces transcription of miR-340-5p to promote HMGB1 expression, which activates TLR4 expression and promotes myocardial injury in rats with SAP.

Corilagin induces apoptosis and inhibits autophagy of HL‑60 cells by regulating miR‑451/HMGB1 axis

Corilagin is the primary active component of the Euphorbia phyllanthus plant and has significant anti-cancer properties. However, the biological effects and mechanisms of corilagin on acute myeloid leukemia (AML) have not been clarified. The Cell Counting Kit-8 and Carboxyfluorescein Diacetate Succinimidyl Ester assay results showed that corilagin significantly inhibited proliferation of the AML cell line HL-60 in a time- and dose-dependent manner. Western blotting and flow cytometry analysis were performed to determine the levels of apoptosis in HL-60 cells. The protein levels of cleaved caspase-3 and Bak were upregulated, while Bcl-xl was downregulated in cells treated with corilagin. The percentage of early- and late-stage apoptotic cells increased following corilagin treatment in a dose-dependent manner, indicating that the intrinsic mitochondrial apoptosis pathway was activated by corilagin. Simultaneously, western blotting and immunofluorescence results revealed that autophagy was suppressed; this was accompanied by a decrease in light chain 3-II (LC3-II) conversion and autophagosomes. MicroRNA (miRNA/miR) profile analysis showed that corilagin elevated the expression of the tumor suppressor miR-451, while the mRNA and protein levels of high mobility group protein B1 (HMGB1), the target of miR-451, decreased following exposure to corilagin. Knockdown of miR-451 decreased the downregulation of HMGB1 caused by corilagin, indicating negative regulation of HMGB1 by miR-451 during corilagin treatment. Furthermore, knockdown of miR-451 also attenuated corilagin-induced proliferation inhibition of HL-60 cells, implying that miR-451 was essential for the proliferation inhibitory effect of corilagin. In conclusion, these results indicated that corilagin induced apoptosis and inhibited autophagy in HL-60 cells by regulating the miR-451/HMGB1 axis, and corilagin may be a novel therapeutic drug for the treatment of AML.

Remifentanil protects heart from myocardial ischaemia/reperfusion (I/R) injury via miR-206-3p/TLR4/NF-κB signalling axis

OBJECTIVES

Myocardial I/R injury is one of the most serious complications after reperfusion therapy in patients with myocardial infarction. Remifentanil has been found to protect the heart against I/R injury. However, its underlying mechanism remains uncertain in myocardial I/R injury.

METHODS

The myocardial I/R injury rat model was established by 30 min of ischaemia followed by 24 h of reperfusion. The animal model was evaluated by the levels of TC, ALT and AST and H&E staining. The binding of miR-206-3p and TLR4 was predicted and verified using TargetScan software, luciferase reporter and RNA pull-down assays. The functional role and mechanism of remifentanil were identified by ultrasonic echocardiography, oxidative stress markers, H&E, Masson and TUNEL staining and western blot.

KEY FINDINGS

The rat myocardial I/R injury model displayed a significantly high level of TC, ALT, AST, TLR4, p-IκBα and p-p65 and the presence of disorganized cells and inflammatory cell infiltration. The model also showed increased levels of LVEDD, LVESD, MDA, fibrosis and apoptosis and decreased levels of EF, FS, SOD and GSH, which were reversed with remifentanil treatment. Knockdown of miR-206-3p damaged cardiac function and aggravated oxidative stress. miR-206-3p could directly bind to TLR4. TLR4 overexpression destroyed cardiac function, exacerbated oxidative stress, increased levels of p-IκBα and p-p65 and aggravated pathology manifestation affected by remifentanil.

CONCLUSIONS

Our results elucidated that remifentanil alleviated myocardial I/R injury by miR-206-3p/TLR4/NF-κB signalling axis.

CircUBXN7 mitigates H/R-induced cell apoptosis and inflammatory response through the miR-622-MCL1 axis

BACKGROUND

Hypoxia/reoxygenation (H/R)-mediated apoptosis and inflammation are major causes of tissue injury in acute myocardial infarction (AMI). Exploring the underlying mechanisms of cardiomyocyte injury induced by H/R is important for AMI treatment. Circular RNAs have been demonstrated to paly vital roles in the pathogenesis of AMI. Our study aimed to explore the function of circular RNA UBXN7 (circUBXN7) in regulating H/R-induced cardiomyocyte injury.

METHODS

H/R-treated H9c2 cells and a mouse model of AMI were used to investigate the function of circUBXN7 in H/R damage and AMI. The expressions of circUNXN7, miR-622 and MCL1 were analyzed by RT-qPCR. CCK-8 was used for examining cell viability. Cell apoptosis was evaluated with caspase 3 activity and Annexin V/PI staining. MCL1, Bax, Bcl-2 and cleaved-caspase 3 were examined with western blot. ELISA was used to examine the secretion of IL-6, TNF-α and IL-1β.

RESULTS

CircUBXN7 was downregulated in patients and mice with AMI, as well as in H/R-treated cells. Overexpression of circUBXN7 mitigated H/R-mediated apoptosis and secretion of inflammatory factors including IL-6, TNF-α and IL-1β. CircUBXN7 suppressed cell apoptosis and inflammatory reaction induced by H/R via targeting miR-622. MiR-622 targeted MCL1 to restrain its expression in H9c2 cells. Knockdown of MCL1 abrogated circUBXN7-mediated alleviation of apoptosis and inflammation after H/R treatment.

CONCLUSION

CircUBXN7 mitigates cardiomyocyte apoptosis and inflammatory reaction in H/R injury by targeting miR-622 and maintaining MCL1 expression. Our study provides novel potential therapeutic targets for AMI treatment.

Interactions between noncoding RNAs as epigenetic regulatory mechanisms in cardiovascular diseases

Cardiovascular diseases (CVDs) represent the foremost cause of mortality in the United States and worldwide. It is estimated that CVDs account for approximately 17.8 million deaths each year. Despite the advances made in understanding cellular mechanisms and gene mutations governing the pathophysiology of CVDs, they remain a significant cause of mortality and morbidity. A major segment of mammalian genomes encodes for genes that are not further translated into proteins. The roles of the majority of such noncoding ribonucleic acids (RNAs) have been puzzling for a long time. However, it is becoming increasingly clear that noncoding RNAs (ncRNAs) are dynamically expressed in different cell types and have a comprehensive selection of regulatory roles at almost every step involved in DNAs, RNAs and proteins. Indeed, ncRNAs regulate gene expression through epigenetic interactions, through direct binding to target sequences, or by acting as competing endogenous RNAs. The profusion of ncRNAs in the cardiovascular system suggests that they may modulate complex regulatory networks that govern cardiac physiology and pathology. In this review, we summarize various functions of ncRNAs and highlight the recent literature on interactions between ncRNAs with an emphasis on cardiovascular disease regulation. Furthermore, as the broad-spectrum of ncRNAs potentially establishes new avenues for therapeutic development targeting CVDs, we discuss the innovative prospects of ncRNAs as therapeutic targets for CVDs.

LncRNA CHRF aggravates myocardial ischemia/reperfusion injury by enhancing autophagy via modulation of the miR-182-5p/ATG7 pathway

Myocardial ischemia/reperfusion (I/R) injury is a very frequent cardiovascular disease and one of the leading causes of death. Abundant evidence has shown that long noncoding RNAs (lncRNAs) are crucial players in myocardial I/R injury. LncRNA cardiac hypertrophy-related factor (CHRF) has been revealed as an important modulator in cardiac disease. However, the function of CHRF in myocardial I/R injury is unclear. In our current work, we found that the expression of CHRF was upregulated in myocardial I/R injury models. Suppression of CHRF relieved myocardial I/R injury in vivo. In addition, in vitro silencing of CHRF enhanced cell viability and attenuated lactate dehydrogenase activity (LDH) as well as apoptosis in H9C2 cells treated with hypoxia/reoxygenation injury. Autophagy has been studied to play an important role in myocardial I/R injury. Thus, experiments related to autophagy were done, and the results showed that CHRF knockdown decreased autophagy. For the exploration of the regulatory mechanism, we found that CHRF sequestered and negatively regulated miR-182-5p to release its inhibition on ATG7. Findings from rescue assays revealed that ATG7 overexpression could suppress the effects of CHRF silence on cell viability, LDH level, apoptosis, and autophagy. To sum up, our results suggested that CHRF exacerbated myocardial I/R injury by enhancing autophagy via modulation of the miR-182-5p/ATG7 pathway. Therefore, this competing endogenous RNA axis may be a potential therapeutic biomarker for myocardial I/R injury.