Predicting Diagnostic Gene Biomarkers Associated With Immune Checkpoints, N6-Methyladenosine, and Ferroptosis in Patients With Acute Myocardial Infarction

An integrated signature of clinical metrics and immune-related genes as a prognostic indicator for ST-segment elevation myocardial infarction patient survival

Background

The immune-inflammatory pathway plays a critical role in myocardial infarction development. However, few studies have systematically explored immune-related genes in relation to myocardial infarction prognosis using bioinformatic analysis. Our study aims to identify differentially expressed immune-related genes(DEIRGs) in ST-segment elevation myocardial infarction (STEMI) patients and investigate their association with clinical outcomes.

Materials and methods

We conducted a systematic review of Gene Expression Omnibus datasets, selecting GSE49925, GSE60993, and GSE61144 for analysis. DEIRGs were identified using GEO2R and overlapped across the chosen datasets. Functional enrichment analysis elucidated the DEIRGs' biological functions and pathways. We established an optimal prognostic prediction model using LASSO penalized Cox proportional hazards regression. The signature's clinical utility was evaluated through survival analysis, ROC curve assessment, and decision curve analysis. Additionally, we constructed a prognostic nomogram for survival rate prediction. External validation was performed using our own plasma samples.

Results

The resulting prognostic signature integrated two dysregulated DEIRGs (S100A12 and IL2RB) and two clinical variables (serum creatinine level and Gensini score). This signature effectively stratified patients into low- and high-risk groups. Survival analysis, ROC curve analysis, and decision curve analysis demonstrated its robust predictive performance and clinical utility within the first two years post-disease onset. External validation confirmed significant outcome differences between risk groups.

Conclusions

Our study establishes a prognostic signature that combines DEIRGs and clinical variables for STEMI patients. The signature exhibits promising predictive capabilities for patient stratification and survival risk assessment.

FPR1: A critical gatekeeper of the heart and brain

G protein-coupled receptors (GPCRs) are currently the most widely focused drug targets in the clinic, exerting their biological functions by binding to chemicals and activating a series of intracellular signaling pathways. Formyl-peptide receptor 1 (FPR1) has a typical seven-transmembrane structure of GPCRs and can be stimulated by a large number of endogenous or exogenous ligands with different chemical properties, the first of which was identified as formyl-methionine-leucyl-phenylalanine (fMLF). Through receptor-ligand interactions, FPR1 is involved in inflammatory response, immune cell recruitment, and cellular signaling regulation in key cell types, including neutrophils, neural stem cells (NSCs), and microglia. This review outlines the critical roles of FPR1 in a variety of heart and brain diseases, including myocardial infarction (MI), ischemia/reperfusion (I/R) injury, neurodegenerative diseases, and neurological tumors, with particular emphasis on the milestones of FPR1 agonists and antagonists. Therefore, an in-depth study of FPR1 contributes to the research of innovative biomarkers, therapeutic targets for heart and brain diseases, and clinical applications.

The Association Between S100A12 Protein and C-Reactive Protein with Malignant Ventricular Arrhythmias Following Acute Myocardial Infarction in the Elderly

Objective

To investigate the association of S100A12 protein and C-reactive protein (CRP) with the onset of malignant ventricular arrhythmias (MVA) after acute myocardial infarction (AMI) in the elderly.

Methods

A total of 159 elderly AMI patients admitted to Chongming Hospital affiliated to Shanghai University of Medicine & Health Sciences from January 2018 to January 2023 were enrolled in the study. CRP levels were determined using an automatic biochemical analyzer, and S100A12 levels were measured using enzyme-linked immunosorbent assay (ELISA). Patients were categorized based on the Lown classification into groups without MVA and with MVA. Univariate analysis was initially performed to identify independent variables, followed by multivariate logistic regression to determine the risk factors for malignant ventricular arrhythmias post-AMI. The predictive value of S100A12 protein and CRP for malignant ventricular arrhythmias after acute myocardial infarction in the elderly was analyzed using the receiver operating characteristic (ROC) curve.

Results

Among the 159 patients with AMI, 27 (17%) had MVA. Multivariate logistic regression analysis indicated that both S100A12 protein and CRP could be independent risk factors for malignant ventricular arrhythmias following acute myocardial infarction in the elderly (p < 0.05). The area under the ROC curve showed the area under the curve (AUC) for S100A12 protein to be 0.7147, for CRP 0.7356, and for the combined diagnosis 0.8350 (p < 0.05).

Conclusion

S100A12 protein and CRP are independent risk factors for MVA after MI in the elderly. The combined application of S100A12 protein and CRP has higher diagnostic sensitivity and specificity.

EGCG attenuated acute myocardial infarction by inhibiting ferroptosis via miR-450b-5p/ACSL4 axis

BACKGROUND

Epigallocatechin gallate (EGCG) has multiple biological effects such as anti-tumor multiple drug resistance, antioxidation and anti-inflammatory properties. Ferroptosis is the main driving factor of ischemic heart injury, thus inhibiting ferroptosis may prove to be an effective treatment strategy for cardiovascular diseases. However, the role of EGCG on ferroptosis in ischemic myocardium and underlying mechanisms remain uncertain.

PURPOSE

This study was aimed to investigate the effects and potential mechanisms of EGCG on myocardial ischemic-induced ferroptosis both in vitro and in vivo.

METHODS

Cardiomyocyte hypoxia model and mouse acute myocardial infarction (AMI) model were established in vitro and in vivo. MiR-450b-5p and ACSL4 silencing or overexpression plasmids were transfected, with or without EGCG pretreatment. Cell viability was determined by the CCK-8 assay. Hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM) were used to evaluate the morphologic alterations. TTC staining was used to observe the infarction area, and echocardiography was adopted to appraise the heart function. Using flow cytometry, the presence of reactive oxygen species (ROS) was assessed. The content of cardiac troponin I (cTn I), glutathione (GSH), malondialdehyde (MDA), divalent iron ions (Fe2+) and superoxide dismutase (SOD) were detected using reagent kits. A luciferase activity assay was performed to assess the binding ability of miR-450b-5p to ACSL4. Expressions of related genes and proteins were measured by RT-qPCR and western blotting respectively.

RESULTS

EGCG attenuated AMI-induced ferroptosis and improved myocardial ischemia injury, which was associated with reducing iron deposition and cTn I, inhibition of lipid peroxidation, decreasing TFR1 and ACSL4, and upregulating SLC7A11, FTH1 and GPX4. Meanwhile, EGCG pretreatment increased miR-450b-5p expression in ischemic myocardium. Further researches discovered that knockdown of miR-450b-5p partially compromised EGCG-generated protective effect in hypoxia HL-1 cells, while combination with miR-450b-5p mimic could strengthen the potency of EGCG on ischemic myocardium. The dual-luciferase test demonstrated that miR-450b-5p has binding to ACSL4. Furthermore, silencing of ACSL4 synergistically increased the cardioprotective effect of EGCG. More significantly, EGCG treatment regulated the ferroptosis-related proteins expression via miR-450b-5p/ACSL4 axis.

CONCLUSION

In summary, the present study evidently demonstrated that EGCG attenuates myocardial ischemia injury by targeting ferroptosis. Our work revealed the role of miR-450b-5p/ACSL4 axis in AMI for the first time. Further, it also elucidated the molecular mechanisms of EGCG on inhibiting ferroptosis greatly depend on the miR-450b-5p/ACSL4 axis, suggesting that EGCG may act as a novel anti-ferroptosis agent and exert a therapeutic role in AMI.

ALKBH5 ALLEVIATES HYPOXIA POSTCONDITIONING INJURY IN d -GALACTOSE-INDUCED SENESCENT CARDIOMYOCYTES BY REGULATING STAT3

ABSTRACT

Ischemic postconditioning (I/Post) reduces I/R injury by activating endogenous cardioprotection mechanisms, such as the JAK/signal transducer and activator of transcription 3 (STAT3) and PI3K/Akt pathways, which offer a traditional approach to myocardial protection. According to a previous study, cardioprotection by I/Post may be lost in aged mice, and in our previous research, hypoxic postconditioning (H/Post) lacked a protective effect in senescent cardiomyocytes, which was associated with low expression of long noncoding RNA H19. The N6-methyladenosine (m 6 A) modification is a dynamic and reversible process that has been confirmed to play a role in cardiovascular diseases. However, the mechanisms of m 6 A modification in myocardial I/Post remain to be explored. Neonatal cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats, and senescence was induced by d -galactose, followed by stimulation of hypoxia-reoxygenation and H/Post. Hypoxic injury was evaluated by cell viability and the Bcl-2/Bax protein ratio. Total m 6 A levels were measured using a colorimetric m 6 A RNA Methylation Quantification Kit, and the m 6 A modified and differentially expressed mRNA was determined by MeRIP (methylated RNA immunoprecipitation). We found that H/Post increased m 6 A methylation and decreased RNA mA demethylase alkB homolog 5 (ALKBH5) expression in aged cardiomyocytes. Furthermore, ALKBH5 knockdown exacerbated injury following H/Post in senescent cardiomyocytes. In addition, ALKBH5 regulated STAT3 expression by mediating its m 6 A modification and long noncoding RNA H19/miR-124-3p. ALKBH5 also alleviated the H/Post injury induced by the low expression of STAT3 in senescent cardiomyocytes.

CXCR1 and its downstream NF-κB inflammation signaling pathway as a key target of Guanxinning injection for myocardial ischemia/reperfusion injury

Guanxinning Injection (GXNI) is used clinically to treat cardiac injury, but its active components and mode of action remains unclear. Therefore, a myocardial ischemia/reperfusion injury (MIRI) model-based integrated strategy including function evaluation, RNA-seq analysis, molecular docking, and cellular thermal shift assay (CETSA) was employed to elucidate the effect and mechanism of GXNI and its main ingredient on cardiac injury. These results revealed that GXNI significantly improved cardiac dysfunction and myocardial injury in I/R mice. RNA-seq analysis clarified that CXCR1-mediated interleukin-8 pathway played a critical role in MIRI. Molecular docking screening identified danshensu (DSS) as the major active components of GXNI targeting CXCR1 protein, which was confirmed in an oxygen-glucose deprivation/reoxygenation-induced cardiomyocytes damage model showing that GXNI and DSS reduced the protein expression of CXCR1 and its downstream NF-κB, COX-2, ICAM-1 and VCAM-1. CETSA and isothermal dose-response fingerprint curves confirmed that DSS combined with CXCR1 in a dose-dependent manner. Furthermore, GXNI and DSS significantly decreased the expression levels of IL-6, IL-1β and TNF-α and the number of neutrophils in post I/R myocardial tissue. In conclusion, this study revealed that GXNI and its active components DSS exert inhibitory effects on inflammatory factor release and leukocyte infiltration to improve I/R-induced myocardial injury by down-regulating CXCR1-NF-κB-COX-2/ICAM-1/VCAM-1 pathway.

Inflammation and Oxidative Stress Role of S100A12 as a Potential Diagnostic and Therapeutic Biomarker in Acute Myocardial Infarction

Acute myocardial infarction (AMI) is one of the most serious cardiovascular diseases with high morbidity and mortality. Numerous studies have indicated that S100A12 may has an essential role in the occurrence and development of AMI, and in-depth studies are currently lacking. The purpose of this study is to investigate the effect of S100A12 on inflammation and oxidative stress and to determine its clinical applicability in AMI. Here, AMI datasets used to explore the expression pattern of S100A12 in AMI were derived from the Gene Expression Omnibus (GEO) database. The pooled standard average deviation (SMD) was calculated to further determine S100A12 expression. The overlapping differentially expressed genes (DEGs) contained in all included datasets were recognized by the GEO2R tool. Then, functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, were carried out to determine the molecular function of overlapping DEGs. Gene set enrichment analysis (GSEA) was conducted to determine unrevealed mechanisms of S100A12. Summary receiver operating characteristic (SROC) curve analysis and receiver operating characteristic (ROC) curve analysis were carried out to identify the diagnostic capabilities of S100A12. Moreover, we screened miRNAs targeting S100A12 using three online databases (miRWalk, TargetScan, and miRDB). In addition, by comprehensively using enzyme-linked immunosorbent assay (ELISA), real-time quantitative PCR (RT-qPCR), Western blotting (WB) methods, etc., we used the AC16 cells to validate the expression and underlying mechanism of S100A12. In our study, five datasets related to AMI, GSE24519, GSE60993, GSE66360, GSE97320, and GSE48060 were included; 412 overlapping DEGs were identified. Protein-protein interaction (PPI) network and functional analyses showed that S100A12 was a pivotal gene related to inflammation and oxidative stress. Then, S100A12 overexpression was identified based on the included datasets. The pooled standard average deviation (SMD) also showed that S100A12 was upregulated in AMI (SMD = 1.36, 95% CI: 0.70-2.03, p = 0.024). The SROC curve analysis result suggested that S100A12 had remarkable diagnostic ability in AMI (AUC = 0.90, 95% CI: 0.87-0.92). And nine miRNAs targeting S100A12 were also identified. Additionally, the overexpression of S100A12 was further confirmed that it maybe promote inflammation and oxidative stress in AMI through comprehensive in vitro experiments. In summary, our study suggests that overexpressed S100A12 may be a latent diagnostic biomarker and therapeutic target of AMI that induces excessive inflammation and oxidative stress. Nine miRNAs targeting S100A12 may play a crucial role in AMI, but further studies are still needed. Our work provides a positive inspiration for the in-depth study of S100A12 in AMI.

N(6)-methyladenosine modification: A vital role of programmed cell death in myocardial ischemia/reperfusion injury

N(6)-methyladenosine (m⁶A) modification is closely associated with myocardial ischemia/reperfusion injury (MIRI). As the most common modification among RNA modifications, the reversible m⁶A modification is processed by methylase ("writers") and demethylase ("erasers"). The biological effects of RNA modified by m⁶A are regulated under the corresponding RNA binding proteins (RBPs) ("readers"). m⁶A modification regulates the whole process of RNA, including transcription, processing, splicing, nuclear export, stability, degradation, and translation. Programmed cell death (PCD) is a regulated mechanism that maintains the internal environment's stability. PCD plays an essential role in MIRI, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. However, the relationship between PCD modified with m⁶A and MIRI is still not clear. This review summarizes the regulators of m⁶A modification and their bioeffects on PCD in MIRI.

N6-methyladenosine modifications of mRNAs and long noncoding RNAs in oxygen-induced retinopathy in mice

Retinal neovascular diseases are major causes of blindness worldwide. As a common epitranscriptomic modification of eukaryotic RNAs, N⁶-methyladenosine (m⁶A) is associated with the pathogenesis of many diseases, including angiogenesis, through the regulation of RNA metabolism and functions. The aim of this study was to identify m⁶A modifications of mRNAs and long noncoding RNAs (lncRNAs) and determine their potential roles in retinal neovascularization. The transcriptome-wide m⁶A profiles of mRNAs and lncRNAs in the retinal tissues of mice with oxygen-induced retinopathy (OIR) and controls were identified by microarray analysis of immunoprecipitated methylated RNAs. The m⁶A methylation levels of mRNAs and lncRNAs identified in the microarray data were validated by MeRIP-qPCR. A total of 1321 mRNAs (151 hypermethylated and 1170 hypomethylated) and 192 lncRNAs (15 hypermethylated and 177 hypomethylated) were differentially methylated with the m⁶A modification in OIR and control mice. Gene ontology analysis showed that hypermethylated mRNAs were enriched in the regulation of multicellular organismal process, intracellular organelle, and protein binding, while hypomethylated mRNAs were enriched in cellular metabolic process, intracellular process, and binding. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that hypermethylated mRNAs were involved in dopaminergic synapses, glutamatergic synapse, and PI3K-Akt signaling pathway, while hypomethylated mRNAs were involved in autophagy, ubiquitin-mediated proteolysis, and spliceosome. Moreover, the altered levels of m⁶A methylation of ANGPT2, GNG12, ROBO4, and ENSMUST00000153785 were validated by MeRIP-qPCR. The results revealed an altered m⁶A epitranscriptome in OIR retinas. These methylated RNAs may act as novel modulators and targets in retinal neovascularization.