Diagnostic and Prognostic Utility of Circulating Cytochrome c in Acute Myocardial Infarction

Study on the mechanism of action of colchicine in the treatment of coronary artery disease based on network pharmacology and molecular docking technology

Objective: This is the first study to explore the mechanism of colchicine in treating coronary artery disease using network pharmacology and molecular docking technology, aiming to predict the key targets and main approaches of colchicine in treating coronary artery disease. It is expected to provide new ideas for research on disease mechanism and drug development. Methods: Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), Swiss Target Prediction and PharmMapper databases were used to obtain drug targets. GeneCards, Online Mendelian Inheritance in Man (OMIM), Therapeutic Target Database (TTD), DrugBank and DisGeNET databases were utilized to gain disease targets. The intersection of the two was taken to access the intersection targets of colchicine for the treatment of coronary artery disease. The Sting database was employed to analyze the protein-protein interaction network. Gene Ontology (GO) functional enrichment analysis was performed using Webgestalt database. Reactom database was applied for Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Molecular docking was simulated using AutoDock 4.2.6 and PyMOL2.4 software. Results: A total of 70 intersecting targets of colchicine for the treatment of coronary artery disease were obtained, and there were interactions among 50 targets. GO functional enrichment analysis yielded 13 biological processes, 18 cellular components and 16 molecular functions. 549 signaling pathways were obtained by KEGG enrichment analysis. The molecular docking results of key targets were generally good. Conclusion: Colchicine may treat coronary artery disease through targets such as Cytochrome c (CYCS), Myeloperoxidase (MPO) and Histone deacetylase 1 (HDAC1). The mechanism of action may be related to the cellular response to chemical stimulus and p75NTR-mediated negative regulation of cell cycle by SC1, which is valuable for further research exploration. However, this research still needs to be verified by experiments. Future research will explore new drugs for treating coronary artery disease from these targets.

Extracellular vesicle-packaged mitochondrial disturbing miRNA exacerbates cardiac injury during acute myocardial infarction

Mounting evidence suggests that extracellular vesicles (EVs) are effective communicators in biological signalling in cardiac physiology and pathology. However, the role of EVs in cardiac injury, particularly in ischemic myocardial scenarios, has not been fully elucidated. Here, we report that acute myocardial infarction (AMI)‐induced EVs can impair cardiomyocyte survival and exacerbate cardiac injury. EV‐encapsulated miR‐503, which is enriched during the early phase of AMI, is a critical molecule that mediates myocardial injury. Functional studies revealed that miR‐503 promoted cardiomyocyte death by directly binding to peroxisome proliferator‐activated receptor gamma coactivator‐1β (PGC‐1β) and a mitochondrial deacetylase, sirtuin 3 (SIRT3), thereby triggering mitochondrial metabolic dysfunction and cardiomyocyte death. Mechanistically, we identified endothelial cells as the primary source of miR‐503 in EVs after AMI. Hypoxia induced rapid H3K4 methylation of the promoter of the methyltransferase‐like 3 gene (METTL3) and resulted in its overexpression. METTL3 overexpression evokes N6‐methyladenosine (m⁶A)‐dependent miR‐503 biogenesis in endothelial cells. In summary, this study highlights a novel endogenous mechanism wherein EVs aggravate myocardial injury during the onset of AMI via endothelial cell‐secreted miR‐503 shuttling.

Outcomes of hyperlactatemia on admission in critically ill patients with acute myocardial infarction: A retrospective study from MIMIC-IV

BACKGROUND

It has not been verified whether there is a correlation between admission hyperlactatemia and outcomes in critically ill patients with acute myocardial infarction (AMI), especially in large data studies, which we aimed to do in this study.

METHODS

For this retrospective study, we extracted analysis data from a famous online intensive care unit database, the Medical Information Mart for Intensive Care (MIMIC)-IV. Included patients were divided into four groups according to the serum lactate level on admission. Hospital mortality and mortality over time were the main outcomes. To explore the relationship between admission hyperlactatemia and outcomes in critically ill patients with AMI, logistic regression, Cox regression, Kaplan-Meier curves, and subgroup analyses were used.

RESULTS

2171 patients matching the selection criteria were enrolled in this study. After adjusting for potential confounding factors, hyperlactatemia on admission contributed to increased short-term mortality in critically ill patients with AMI. The adjusted odds ratio for hospital mortality were 1.62, 3.46 and 5.28 in the mild, moderate, and severe hyperlactatemia groups (95% CI: 1.20-2.18, 2.15-5.58, and 2.20-12.70, respectively). The adjusted hazard ratio for 7-day and 30-day mortality were 1.99 and 1.35 (95% CI: 1.45-2.73 and 1.09-1.67) in the mild hyperlactatemia group, 3.33 and 2.31 (95% CI: 2.22-4.99 and 1.72-3.10) in the moderate hyperlactatemia group, 4.81 and 2.91 (95% CI: 2.86-8.08 and 1.88-4.50) in the severe hyperlactatemia group. The adjusted hazard ratio for 1-year and 5-year mortality were 2.03 and 1.93 (95% CI: 1.58-2.62 and 1.52-2.47) in the moderate hyperlactatemia group, 1.92 and 1.74 (95% CI: 1.28-2.89 and 1.17-2.59) in the severe hyperlactatemia group. Subgroup analyses indicated that the positive correlation between serum lactate level on admission and short-term mortality of critically ill patients with AMI was similar in the subgroups of cardiogenic shock and acute heart failure (P for interaction > 0.05).

CONCLUSION

Hyperlactatemia, especially moderate and severe hyperlactatemia, on admission is closely related to higher short-term mortality incidence in critically ill patients with AMI. The relationship between serum lactate level on admission and short-term mortality of critical AMI patients is stable in subgroups of cardiogenic shock and acute heart failure.

Mitochondrial Damage-associated Molecular Patterns as Potential Biomarkers in DCD Heart Transplantation: Lessons From Myocardial Infarction and Cardiac Arrest

Heart transplantation with donation after circulatory death (DCD) has become a real option to increase graft availability. However, given that DCD organs are exposed to the potentially damaging conditions of warm ischemia before procurement, new strategies for graft evaluation are of particular value for the safe expansion of DCD heart transplantation. Mitochondria-related parameters are very attractive as biomarkers because of their intimate association with cardiac ischemia-reperfusion injury. In this context, a group of mitochondrial components, called mitochondrial damage-associated molecular patterns (mtDAMPs), released by stressed cells, holds great promise. mtDAMPs may be released at different stages of DCD cardiac donation and may act as indicators of graft quality. Because of the lack of information available for DCD grafts, we consider that relevant information can be obtained from other acute cardiac ischemic conditions. Thus, we conducted a systematic review of original research articles in which mtDAMP levels were assessed in the circulation of patients with acute myocardial infarction and cardiac arrest. We conclude that 4 mtDAMPs, ATP, cytochrome c, mitochondrial DNA, and succinate, are rapidly released into the circulation after the onset of ischemia, and their concentrations increase with reperfusion. Importantly, circulating levels of mtDAMPs correlate with cardiac damage and may be used as prognostic markers for patient survival in these conditions. Taken together, these findings support the concept that mtDAMPs may be of use as biomarkers to assess the transplant suitability of procured DCD hearts, and ultimately aid in facilitating the safe, widespread adoption of DCD heart transplantation.

HDAC9 exacerbates myocardial infarction via inactivating Nrf2 pathways

OBJECTIVES

Myocardial infarction (MI) is the leading cause of death worldwide. Histone deacetylases (HDACs) collectively participate in the initiation and progression of heart diseases, including MI. This study aimed to investigate the roles of histone deacetylase 9 (HDAC9) in the development of MI.

METHODS

In vivo and in vitro assays were conducted to determine the effects of HDAC9 on heart function and MI. qRT-PCR was applied to determine the mRNA level. Western blot was performed for protein expression. Immunofluorescence was applied to detect the fluorescence tensity of Myog and Myod. CCK-8, flow cytometry and transwell assays were carried out for function analysis.

KEY FINDINGS

HDAC9 was upregulated in MI models in vivo and in vitro. Downregulated HDAC9 modulated the changes in left ventricle ejection fraction (LVEF), left ventricle fractional shortening (LVFS) and left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD). Moreover, HDAC9 knockdown activated NFE2-related factor 2 (Nrf2)/Keap1/HO-1 pathways. Additionally, HDAC9/Nrf2 axis modulated the proliferation, apoptosis and myogenesis of cardiomyocytes.

CONCLUSIONS

Taken together, HDAC9 knockout induced the activation of Nrf2 and protected heart from MI injury. Thus, the HDAC9/Nrf2 axis can be a novel marker for the treatment of MI.

Mitochondrial Biomarkers in Patients with ST-Elevation Myocardial Infarction and Their Potential Prognostic Implications: A Prospective Observational Study

Background: Mitochondrial biomarkers have been investigated in different critical settings, including ST-elevation myocardial infarction (STEMI). Whether they provide prognostic information in STEMI, complementary to troponins, has not been fully elucidated. We prospectively explored the in-hospital and long-term prognostic implications of cytochrome c and cell-free mitochondrial DNA (mtDNA) in STEMI patients undergoing primary percutaneous coronary intervention. Methods: We measured cytochrome c and mtDNA at admission in 466 patients. Patients were grouped according to mitochondrial biomarkers detection: group 1 (−/−; no biomarker detected; n = 28); group 2 (−/+; only one biomarker detected; n = 283); group 3 (+/+; both biomarkers detected; n = 155). A composite of in-hospital mortality, cardiogenic shock, and acute pulmonary edema was the primary endpoint. Four-year all-cause mortality was the secondary endpoint. Results: Progressively lower left ventricular ejection fractions (52 ± 8%, 49 ± 8%, 47 ± 9%; p = 0.006) and higher troponin I peaks (54 ± 44, 73 ± 66, 106 ± 81 ng/mL; p = 0.001) were found across the groups. An increase in primary (4%, 14%, 19%; p = 0.03) and secondary (10%, 15%, 23%; p = 0.02) endpoint rate was observed going from group 1 to group 3. The adjusted odds ratio increment of the primary endpoint from one group to the next was 1.65 (95% CI 1.04–2.61; p = 0.03), while the adjusted hazard ratio increment of the secondary endpoint was 1.55 (95% CI 1.12–2.52; p = 0.03). The addition of study group allocation to admission troponin I reclassified 12% and 22% of patients for the primary and secondary endpoint, respectively. Conclusions: Detection of mitochondrial biomarkers is common in STEMI and seems to be associated with in-hospital and long-term outcome independently of troponin.

Legumain is a predictor of all-cause mortality and potential therapeutic target in acute myocardial infarction

The prognostic impact of extracellular matrix (ECM) modulation and its regulatory mechanism post-acute myocardial infarction (AMI), require further clarification. Herein, we explore the predictive role of legumain—which showed the ability in ECM degradation—in an AMI patient cohort and investigate the underlying mechanisms. A total of 212 AMI patients and 323 healthy controls were enrolled in the study. Moreover, AMI was induced in mice by permanent ligation of the left anterior descending artery and fibroblasts were adopted for mechanism analysis. Based on the cut-off value for the receiver-operating characteristics curve, AMI patients were stratified into low (n = 168) and high (n = 44) plasma legumain concentration (PLG) groups. However, PLG was significantly higher in AMI patients than that in the healthy controls (median 5.9 μg/L [interquartile range: 4.2–9.3 μg/L] vs. median 4.4 μg/L [interquartile range: 3.2–6.1 μg/L], P < 0.001). All-cause mortality was significantly higher in the high PLG group compared to that in the low PLG group (median follow-up period, 39.2 months; 31.8% vs. 12.5%; P = 0.002). Multivariate Cox regression analysis showed that high PLG was associated with increased all-cause mortality after adjusting for clinical confounders (HR = 3.1, 95% confidence interval (CI) = 1.4–7.0, P = 0.005). In accordance with the clinical observations, legumain concentration was also increased in peripheral blood, and infarcted cardiac tissue from experimental AMI mice. Pharmacological blockade of legumain with RR-11a, improved cardiac function, decreased cardiac rupture rate, and attenuated left chamber dilation and wall thinning post-AMI. Hence, plasma legumain concentration is of prognostic value in AMI patients. Moreover, legumain aggravates cardiac remodelling through promoting ECM degradation which occurs, at least partially, via activation of the MMP-2 pathway.

High-Sensitivity C-Reactive Protein and Acute Kidney Injury in Patients with Acute Myocardial Infarction: A Prospective Observational Study

Background. Accumulating evidence suggests that inflammation plays a key role in acute kidney injury (AKI) pathogenesis. We explored the relationship between high-sensitivity C-reactive protein (hs-CRP) and AKI in acute myocardial infarction (AMI). Methods. We prospectively included 2,063 AMI patients in whom hs-CRP was measured at admission. AKI incidence and a clinical composite of in-hospital death, cardiogenic shock, and acute pulmonary edema were the study endpoints. Results. Two-hundred-thirty-four (11%) patients developed AKI. hs-CRP levels were higher in AKI patients (45 ± 87 vs. 16 ± 41 mg/L; p < 0.0001). The incidence and severity of AKI, as well as the rate of the composite endpoint, increased in parallel with hs-CRP quartiles (p for trend <0.0001 for all comparisons). A significant correlation was found between hs-CRP and the maximal increase of serum creatinine (R = 0.23; p < 0.0001). The AUC of hs-CRP for AKI prediction was 0.69 (p < 0.001). At reclassification analysis, addition of hs-CRP allowed to properly reclassify 14% of patients when added to creatinine and 8% of patients when added to a clinical model. Conclusions. In AMI, admission hs-CRP is closely associated with AKI development and severity, and with in-hospital outcomes. Future research should focus on whether prophylactic renal strategies in patients with high hs-CRP might prevent AKI and improve outcome.

Circulating Mitochondrial DNA as Predictor of Mortality in Critically Ill Patients: A Systematic Review of Clinical Studies

BACKGROUND

Despite numerous publications on mitochondrial DNA (mtDNA) in the last decade it remains to be seen whether mtDNA can be used clinically. We conducted a systematic review to assess circulating cell-free mtDNA as a biomarker of mortality in critically ill patients.

METHODS

This systematic review was registered with PROSPERO (CRD42016046670). PubMed, CINAHL, the Cochrane Library, Embase, Scopus, and Web of Science, and reference lists of retrieved articles were searched. Studies measuring circulating cell-free mtDNA and reporting on all-cause mortality in critically ill adult and pediatric patients were included. The primary and secondary outcomes were mortality and morbidity, respectively.

RESULTS

Of the 1,566 initially retrieved publications, 40 studies were included, accounting for 3,450 critically ill patients. Substantial differences between studies were noted in how mtDNA was isolated and measured. Sixteen of the 40 included studies (40%) explored the association between mtDNA levels and mortality; of those 16 studies, 11 (68.8%) reported a statistically significant association. The area under the receiver operating characteristic (AUROC) curve for mtDNA and mortality was calculated for 10 studies and ranged from 0.61 to 0.95.

CONCLUSIONS

There is growing interest in mtDNA as a predictor of mortality in critically ill patients. Most studies are small, lack validation cohorts, and utilize different protocols to measure mtDNA. When reported, AUROC analysis usually suggests a statistically significant association between mtDNA and mortality. Standardization of mtDNA protocols and the completion of a large, prospective, multicenter trial may be warranted to firmly establish the clinical usefulness of mtDNA.

Mitochondrial integrity during early reperfusion in an isolated rat heart model of donation after circulatory death-consequences of ischemic duration

BACKGROUND

Cardioprotection and graft evaluation after ischemia-reperfusion (IR) are essential in facilitating heart transplantation with donation after circulatory death. Given the key role of mitochondria in IR, we aimed to investigate the tolerance of cardiac mitochondria to warm, global ischemia and to determine the predictive value of early reperfusion mitochondria-related parameters for post-ischemic cardiac recovery.

METHODS

Isolated, working rat hearts underwent 0, 21, 24, 27, 30, or 33 minutes of warm, global ischemia, followed by 60 minutes of reperfusion. Functional recovery (developed pressure × heart rate) was determined at 60 minutes of reperfusion, whereas mitochondrial integrity was measured at 10 minutes of reperfusion.

RESULTS

Functional recovery at 60 minutes of reperfusion decreased with ≥ 27 minutes of ischemia vs no ischemia (n = 7-8/group; p < 0.01). Cytochrome c, succinate release, and mitochondrial Ca²⁺ content increased with ≥ 27 minutes of ischemia vs no ischemia (p < 0.05). Ischemia at ≥ 21 minutes decreased mitochondrial coupling, adenosine 5'-triphosphate content, mitochondrial Ca²⁺ retention capacity, and increased oxidative damage vs no ischemia (p < 0.05). Reactive oxygen species (ROS) from reverse electron transfer increased with 21 and 27 minutes of ischemia vs no ischemia and 33 minutes of ischemia (p < 0.05), whereas ROS from forward electron transfer increased only with 33 minutes of ischemia vs no ischemia (p < 0.05). Mitochondrial coupling and adenosine 5'-triphosphate content correlated positively and cytochrome c, succinate, oxidative damage, and mitochondrial Ca²⁺ content correlated negatively with cardiac functional recovery (p < 0.05).

CONCLUSIONS

Mitochondrial dysfunction occurs with shorter periods of ischemia than cardiac dysfunction. Mitochondrial coupling, ROS emission from reverse electron transfer, and calcium retention are particularly sensitive to early reperfusion injury, reflecting potential targets for cardioprotection. Indicators of mitochondrial integrity may be of aid in evaluating suitability of donation after circulatory death grafts for transplantation.

FoxO4 promotes myocardial ischemia-reperfusion injury: the role of oxidative stress-induced apoptosis

Myocardial cell apoptosis is the main pathophysiological process underlying ischemia-reperfusion (I/R) injury. FoxO4, which was initially identified as a tumor suppressor that limits cell proliferation and induces apoptosis, plays diverse roles in cardiovascular diseases. However, its contribution to myocardial I/R injury remains unclear. The present study was undertaken to explore the role of FoxO4 in apoptosis during myocardial I/R injury and its underlying mechanisms in vivo. Rats were subjected to ligation/restoration of the left anterior descending branch of the coronary artery and 30 min of ischemia, followed by 4 h of reperfusion. Then, triphenyltetrazolium chloride (TTC) staining was performed to evaluate the infarct size. Transthoracic echocardiography was performed to evaluate cardiac function. Terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) staining was performed to assess cell death in the myocardium. Real-time PCR was performed to measure FoxO4 mRNA expression. Western blots were performed to assess expression levels of the FoxO4 and cleaved caspase 3 proteins. Immunofluorescence staining was performed to measure cleaved caspase 3 expression levels. The hydroxylamine and TBA methods were performed to evaluate malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity, respectively. Dihydroethidium (DHE) staining was performed to measure reactive oxygen species (ROS) generation. We successfully established a rat model of myocardial I/R injury and observed an increase in FoxO4 expression in the myocardium. FoxO4 knockdown significantly protected rats from myocardial I/R injury, as indicated by a marked decrease in infarct sizes and improvements in cardiac function. Mechanistically, I/R induced excessive oxidative stress in rat hearts, most likely as a result of increased FoxO4 levels, and these effects contributed to inducing apoptosis. In conclusion, the FoxO4/ROS pathway represents a potentially novel mechanism underlying apoptosis during myocardial I/R injury. Therapeutic strategies targeting FoxO4 might represent new treatments for myocardial I/R injury.

Plasma Cytochrome c Detection Using a Highly Sensitive Electrochemiluminescence Enzyme-Linked Immunosorbent Assay

Background

Cytochrome c is an intermembrane mitochondrial protein that is released to the bloodstream following mitochondrial injury.

Methods and results

We developed an electrochemiluminescence immunoassay to measure cytochrome c in human and rat plasma, which showed high sensitivity with broad dynamic range (2-1200 ng/mL in humans and 5-500 ng/mL in rat) and high assay reproducibility (inter-assay coefficient <6% in humans and <10% in rat). In patients after blunt trauma, plasma cytochrome c directly correlated with injury severity. In rats after cardiac resuscitation, plasma cytochrome c inversely correlated with survival and responsiveness to mitochondrial protective interventions.

Conclusions

The cytochrome c assays herein presented have high sensitivity, wide dynamic range, and high reproducibility well suited for biomarker of mitochondrial injury.