Immunohistochemical detection of S100A1 in the postmortem diagnosis of acute myocardial infarction

Forensic significance of intracardiac expressions of Nrf2 in acute myocardial ischemia

When exposed to oxidative and electrophilic stress, a protective antioxidant response is initiated by nuclear factor erythroid 2-related factor 2 (Nrf2). However, the extent of its importance in the forensic diagnosis of acute ischemic heart diseases (AIHD), such as myocardial infarction (MI), remains uncertain. On the other hand, immunohistochemical analyses of fibronectin (FN) and the terminal complement complex (C5b-9) prove valuable in identifying myocardial ischemia that precedes necrosis during the postmortem diagnosis of sudden cardiac death (SCD). In this study, we investigated the immunohistochemical levels of Nrf2, FN, and C5b-9 in human cardiac samples to explore their forensic relevance for the identification of acute cardiac ischemia. Heart samples were obtained from 25 AIHD cases and 39 non-AIHD cases as controls. Nrf2 was localized in the nuclei of cardiomyocytes, while FN and C5b-9 were detected in the myocardial cytoplasm. The number of intranuclear Nrf2 positive signals in cardiomyocytes increased in AIHD cases compared to control cases. Additionally, the grading of positive portions of cardiac FN and C5b-9 in the myocardium was also significantly enhanced in AIHD, compared to controls. Collectively, these results indicate that the immunohistochemical investigation of Nrf2 combined with FN, and/or C5b-9 holds the potential for identifying early-stage myocardial ischemic lesions in cases of SCD.

Immune-related biomarkers in myocardial infarction; diagnostic/prognostic value and therapeutic potential

The incidence of myocardial infarction (MI) is increasing worldwide on an annual basis. The incorporation of circulating biomarkers, along with electrocardiography, echocardiography, coronary angiograms, and other diagnostic techniques, is essential in the evaluation, prediction, and therapeutic efficacy assessment of patients afflicted with MI. Biomarker evaluation has been employed in the diagnosis of MI for over five decades. Further biomarker research can be carried out as newer biomarkers have been discovered in pathways such as inflammatory response, neurohormonal stimulation, or myocardial stress that initiate significantly earlier than myocyte necrosis and the diagnostic establishment of cardiac troponins. The assessment of biomarkers for MI is on the brink of a significant transformation due to advancements in comprehending the intricate pathophysiology of the condition. This has led to a pursuit of innovative biomarkers that could potentially overcome the limitations of current biomarkers. For individuals with a high-risk profile, this may facilitate tailoring of appropriate treatment. This review places emphasis on a diverse array of biomarkers that have the potential to offer diagnostic and prognostic information, as well as the latest clinical and preclinical evidence that is driving theoretical advancements in cardiovascular immunotherapy.

Recent perspectives on the early expression immunohistochemical markers in post-mortem recognition of myocardial infarction

Acute Myocardial Infarction (AMI) refers to the death of heart tissue in the absence ofperfusion. It is one of the top causes of death globally, particularly in middle andhigher-age groups. However, for the pathologist, the post-mortem macroscopic andmicroscopic diagnosis of early AMI remains challenging. In the early acute stage ofAMI, no microscopic visible signs of tissue alterations like necrosis and neutrophilinfiltration can be seen. In such a scenario, immunohistochemistry (IHC) accounts forthe most suitable and safest alternative to study early diagnostic cases by selectivelydetecting changes in the cell population. This systematic review focuses on themultiple causes/changes that lead to the privation of blood flow as well as tissuechanges induced by the absence of perfusion.We performed a systematic review of the last 10-15 years' publications that focused ondetecting immunohistochemical changes that appear in the cell population in case ofacute myocardial infarction. We found around 160 articles on AMI, which we narroweddown to 50 with the use of specific filters such as: "Acute Myocardial Infarction," "Ischemia," "Hypoxia," "Forensic," "Immunohistochemistry, and "Autopsy." The presentreview comprehensively highlights the current knowledge of specific IHC markers usedas gold standards during post-mortem investigation of acute myocardial infarction. Thepresent review comprehensively highlights the current knowledge of specific IHCmarkers used as gold standards during post-mortem investigation of acute myocardialinfarction, and some new potential immunohistochemical markers that can be used inthe early detection of myocardial infarction.

Traditional and novel diagnostic biomarkers for acute myocardial infarction

Background

Acute myocardial infarction (AMI) is a leading cause of death worldwide. The first hours of acute myocardial infarction are correlated with the highest risk of death. Therefore, early diagnosis of the infarction seriously affects the efficacy of the treatment administered to the patient. Misdiagnosing patients with chest pain often leads to inappropriate admission of them as acute myocardial infarction patients. The physical examination of the patient, the electrocardiogram, and the assessment of cardiac biomarkers all play an important role in the early diagnosis of acute ischemia, along with the patient's medical history.

Main body

The present review highlights a number of different biomarkers that are released and elevated in blood during an acute myocardial infarction.

Conclusions

Analysis of cardiac biomarkers has become the first-line diagnostic tool used in the diagnosis of acute myocardial infarction. Novel markers of acute myocardial infarction, when added to routinely used markers, can provide added value not only in the earlier detection of acute myocardial infarction but also in monitoring the clinical progress of the disease, predicting its consequences, evaluating its prognosis, detecting recurrence, and managing its treatment. This leads to a lower mortality rate associated with acute myocardial infarction.

cMyC, IMA, S100, and MicroRNAs can serve as markers of early diagnosis of acute myocardial infarction, whereas myeloperoxidase, sCD40L, PAPPA, and TNF-α can be used to monitor the clinical progress of the disease. In addition, H-FABP, GDF-15, F2 isoprostanes, and ST2 can serve as predictors of AMI complications and mortality. Copeptin, ST2, and SIRT can be useful as prognostic markers of acute myocardial infarction.

Forensic significance of intracardiac heme oxygenase-1 expression in acute myocardial ischemia

Heme oxygenase-1 (HO-1), an inducible stress-response protein, exerts anti-oxidant and anti-apoptotic effects. However, its significance in forensic diagnosis of acute ischemic heart diseases (AIHD) such as myocardial infarction (MI) is still unknown. We examined the immunohistochemical expression of HO-1 in the heart samples to discuss their forensic significance to determine acute cardiac ischemia. The heart samples were obtained from 23 AIHD cases and 33 non-AIHD cases as controls. HO-1 positive signals in cardiomyocyte nuclear were detected in 78.2% of AIHD cases, however, that were detected in only 24.2% control cases with statistical difference between AIHD and non-AIHD groups. In contrast to HO-1 protein expression, there was no significant difference in the appearance of myoglobin pallor regions and leukocyte infiltration in the hearts between AIHD and non-AIHD groups. From the viewpoints of forensic pathology, intracardiac HO-1 expression would be considered a valuable marker to diagnose AIHD as the cause of death.

Diagnostic and Prognostic Biomarkers for Myocardial Infarction

The incidence of myocardial infarction (MI) increases every year worldwide. Better diagnostic and prognostic biomarkers for clinical applications are the consistent pursuit of MI research. In addition to electrocardiogram, echocardiography, coronary angiography, etc., circulating biomarkers are essential for the diagnosis, prognosis, and treatment effect monitoring of MI patients. In this review, we assessed both strength and weakness of MI circulating biomarkers including: (1) originated from damaged myocardial tissues including current golden standard cardiac troponin, (2) released from non-myocardial tissues due to MI-induced systems reactions, and (3) preexisted in blood circulation before the occurrence of MI event. We also summarized newly reported MI biomarkers. We proposed that the biomarkers preexisting in blood circulation before MI incidents should be emphasized in research and development for MI prevention in near future.

S100A1 is a sensitive and specific cardiac biomarker for early diagnosis and prognostic assessment of acute myocardial infarction measured by chemiluminescent immunoassay

BACKGROUND

A member of the S100 family of Ca²⁺-binding proteins, S100A1 is highly expressed in cardiac muscle tissue. Although this protein is considered an indicator of acute myocardial infarction (AMI), high-throughput and sensitive detection methods are still urgently needed. We constructed a rapid and sensitive method for detecting S100A1 and to investigate the clinical utility of S100A1 as a biomarker for the early diagnosis of AMI and subsequent prognostic assessments. We developed an automated chemiluminescent immunoassay to detect S100A1. We then analyzed the performance of the newly developed assay including evaluation of the analytical sensitivity, analytical selectivity, linear range, accuracy and repeatability.

METHODS

We recruited 87 patients with AMI or angina pectoris to explore the value of this marker for the early diagnosis and prognostic assessment.

RESULTS

The chemiluminescent-immune-based S100A1 assay had functional analytical sensitivity with a detection limit of 0.13 ng/ml, and a wide linear range of 0.13-31.66 ng/ml. It also exhibited good repeatability with intra-assay and inter-assay findings of <5% and <15%, respectively. Plasma S100A1 was found to have a higher diagnostic sensitivity than conventional cardiac biomarkers (creatine kinase-MB and cardiac troponin T). The survival analysis showed that a higher concentration of plasma S100A1 (>1.02 ng/ml) was notably associated with the poor prognosis of AMI patients after first PCI.

CONCLUSIONS

Measurement of circulating S100A1 concentrations with our newly developed chemiluminescent-immune-based assay shows potential for use in the clinic. This assay could enable early identification and prognostic assessment of AMI.

Immunohistochemistry in the Detection of Early Myocardial Infarction: Systematic Review and Analysis of Limitations Because of Autolysis and Putrefaction

The postmortem diagnosis of acute myocardial infarction is one of the main problems in forensic practice, especially in cases in which death occurs soon after (from minutes to a few hours) the onset of the ischemic damage. Several authors have highlighted the possibility to overcome the limits of conventional histology in this diagnosis by utilizing immunohistochemistry. In the present research, we examined over 30 scientific studies and picked out over 20 main immunohistochemical antigens analyzed with a view to enabling the rapid diagnosis of early myocardial infarction. The aim of our review was to examine and summarize all the principal markers studied to date and also to consider their limitations, including protein alteration because of cadaveric autolysis and putrefaction.

Elevated plasma S100A1 level is a risk factor for ST-segment elevation myocardial infarction and associated with post-infarction cardiac function

AIM

To investigate the association between plasma S100A1 level and ST-segment elevation myocardial infarction (STEMI) and potential significance of S100A1 in post-infarction cardiac function.

METHODS

We examined the plasma S100A1 level in 207 STEMI patients (STEMI group) and 217 clinically healthy subjects for routine physical examination without a history of coronary artery disease (Control group). Baseline characteristics and concentrations of relevant biomarkers were compared. The relationship between S100A1 and other plasma biomarkers was detected using correlation analysis. The predictive role of S100A1 on occurrence of STEMI was then assessed using multivariate ordinal regression model analysis after adjusting for other covariates.

RESULTS

The plasma S100A1 level was found to be significantly higher (P<0.001) in STEMI group (3197.7±1576.0 pg/mL) than in Control (1423.5±1315.5 pg/mL) group. Furthermore, the correlation analysis demonstrated plasma S100A1 level was significantly associated correlated with hypersensitive cardiac troponin T (hs-cTnT) (r = 0.32; P < 0.001), creatine kinase MB (CK-MB) (r = 0.42, P < 0.001), left ventricular eject fraction (LVEF) (r = -0.12, P = 0.01), N-terminal prohormone of brain natriuretic peptide (NT-proBNP) (r = 0.61; P < 0.001) and hypersensitive C reactive protein (hs-CRP) (r = 0.38; P < 0.001). Moreover, the enrolled subjects who with a S100A1 concentration ≤ 1965.9 pg/mL presented significantly better cardiac function than the rest population. Multivariate Logistic regression analysis revealed that S100A1 was an independent predictor for STEMI patients (OR: 0.671, 95% CI 0.500-0.891, P<0.001). In addition, higher S100A1 concentration (> 1965.9 pg/mL) significantly increased the risk of STEMI as compared with the lower level (OR: 6.925; 95% CI: 4.15-11.375; P<0.001).

CONCLUSION

These results indicated that the elevated plasma S100A1 level is an important predictor of STEMI in combination with several biomarkers and also potentially reflects the cardiac function following the acute coronary ischemia.

Usability of Immunohistochemistry in Forensic Samples With Varying Decomposition

Immunohistochemistry (IHC) is an important diagnostic tool in anatomic and surgical pathology but is used less frequently in forensic pathology. Degradation of tissue because of postmortem decomposition is believed to be a major limiting factor, although it is unclear what impact such degradation actually has on IHC staining validity. This study included 120 forensic autopsy samples of liver, lung, and brain tissues obtained for diagnostic purposes. The time from death to autopsy ranged between 1 and more than 14 days. Samples were prepared using the tissue microarray technique. The antibodies chosen for the study included KL1 (for staining bile duct epithelium), S100 (for staining glial cells and myelin), vimentin (for endothelial cells in cerebral blood vessels), and CD45 (for pulmonary lymphocytes). Slides were evaluated by light microscopy. Immunohistochemistry reactions were scored according to a system based on the extent and intensity of the positive stain. An overall correlation between the postmortem interval and the IHC score for all tissue samples was found. Samples from decedents with a postmortem interval of 1 to 3 days showed positive staining with all antibodies, whereas samples from decedents with a longer postmortem interval showed decreased staining rates. Our results suggest that IHC analysis can be successfully used for postmortem diagnosis in a range of autopsy samples showing lesser degrees of decomposition.

Association between serum S100A1 level and Global Registry of Acute Coronary Events score in patients with non-ST-segment elevation acute coronary syndrome

Objective

Acute coronary syndrome (ACS) is associated with several clinical syndromes, one of which is acute non-ST-segment ACS (NSTE-ACS). S100A1 is a calcium-dependent regulator of heart contraction and relaxation. We investigated the association between the serum S100A1 level and the Global Registry of Acute Coronary Events (GRACE) risk score in patients with NSTE-ACS and the potential of using the serum S100A1 level to predict the 30-day prognosis of NSTE-ACS.

Methods

The clinical characteristics of 162 patients with NSTE-ACS were analyzed to determine the GRACE score. The serum S100A1 concentration was determined using fasting antecubital venous blood. The patients were divided into different groups according to the serum S100A1 level, and the 30-day NSTE-ACS prognosis was evaluated using Kaplan–Meier analysis.

Results

The serum S100A1 levels differed significantly among the groups. Correlation analysis showed that the serum S100A1 level was positively correlated with the GRACE score. Kaplan–Meier analysis revealed that the number of 30-day cardiac events was significantly higher in patients with an S100A1 level of >3.41 ng/mL.

Conclusions

S100A1 is a potential biomarker that can predict the progression of NSTE-ACS and aid in its early risk stratification and prognosis.

Immunohistochemical study on dystrophin expression in CAD-related sudden cardiac death: a marker of early myocardial ischaemia

The aims of this study were to assess if dystrophin can be a tool for the forensic evaluation of sudden cardiac death due to coronary atherosclerotic disease (CAD) and particularly if it can be a marker of early myocardial ischaemia. Then in this investigation, the dystrophin was compared to C5b-9 and fibronectin to analyze if there are some differences in the expression of these proteins. Two groups of CAD-related sudden cardiac death, respectively the group 1 with gross and/or histological evidence and the group 2 with no specific histological signs of myocardial ischaemia were used. A third group formed by cases of acute mechanical asphyxiation was used as a control. The immunohistochemical staining by dystrophin, C5b-9 and fibronectin antibodies was performed. Loss of sarcolemmal dystrophin was observed in different degrees according to more or less significant histological evidence of myocardial ischaemia. Moreover, the comparison between loss of dystrophin expression and fibronectin positivity showed significant differences in group 2. The results suggested that dystrophin can be used in forensic diagnosis of CAD-related sudden cardiac death and as marker of early myocardial ischaemia.

Early markers of myocardial ischemia: from the experimental model to forensic pathology cases of sudden cardiac death

The goal of this study was to assess whether early markers of myocardial ischemia, identified in a previous experimental work, can be applied in forensic pathology cases of sudden, ischemic cardiac death. These markers include desphosphorylated connexin 43 (Cx43), JunB, TUNEL assay, myoglobin, and troponin T. Fourteen cases of sudden cardiac death with gross and/or histological signs of myocardial infarction and 14 cases of sudden cardiac death with signs of early ischemia at histology and positive immunoreactions for fibronectin and C5b-9 were investigated. The control group was represented by 15 hanging (global hypoxia) cases. Immunohistochemical reactions were classified into four degrees and compared among groups. Cx43 and JunB were significantly more expressed in hanging than in ischemia/infarction, but they showed a different distribution in the tissue (sub-endocardial in ischemia/infarction, diffuse in hanging) and a different intensity of the signal. TUNEL assay was significantly more expressed in the group of early ischemia than in myocardial infarction. Myoglobin and troponin T did not show any significantly different expression among the three groups. Depletion markers have a limited application in forensic cases, and this is mostly because positive (depleted) areas are difficult to distinguish from artifactually paler areas. Nuclear markers (JunB and TUNEL), on the other hand, require a well-trained eye and a high magnification in order to be distinguished. Cx43, JunB, and TUNEL assays were confirmed to be early, sensitive markers for myocardial ischemia. Nonetheless, they are not specific, as they are expressed in global hypoxia as well, but with a different tissular distribution.

Immunohistochemical detection of early myocardial infarction: a systematic review

The postmortem diagnosis of early myocardial infarction is a challenge for forensic pathologists because the routine histology is neither specific. Many authors have suggested the use of the immunohistochemistry to fill the gaps in the histological diagnosis of early myocardial infarction. This review aims to analyse advances of immunohistochemical detection of early cardiac damage due to ischaemia. To this purpose, we reviewed experimental studies that investigated immunohistochemical markers and their estimated timing of expression. The review was performed according to specific inclusion and exclusion criteria, and a total of 23 studies assessing the immunohistochemical markers for the diagnosis and timing of early myocardial infarction were identified. The literature review highlights that the analysed markers are complement components, others being inflammatory mediators, cardiac cell proteins, plasma proteins, stress or hypoxia-induced factors and proteins associated with heart failure. All studies demonstrate the effectiveness of the tested markers in the early detection of myocardial infarction in both animal and human samples.

HMGB1, IL-1α, IL-33 and S100 proteins: dual-function alarmins

Our immune system is based on the close collaboration of the innate and adaptive immune systems for the rapid detection of any threats to the host. Recognition of pathogen-derived molecules is entrusted to specific germline-encoded signaling receptors. The same receptors have now also emerged as efficient detectors of misplaced or altered self-molecules that signal tissue damage and cell death following, for example, disruption of the blood supply and subsequent hypoxia. Many types of endogenous molecules have been shown to provoke such sterile inflammatory states when released from dying cells. However, a group of proteins referred to as alarmins have both intracellular and extracellular functions which have been the subject of intense research. Indeed, alarmins can either exert beneficial cell housekeeping functions, leading to tissue repair, or provoke deleterious uncontrolled inflammation. This group of proteins includes the high-mobility group box 1 protein (HMGB1), interleukin (IL)-1α, IL-33 and the Ca²⁺-binding S100 proteins. These dual-function proteins share conserved regulatory mechanisms, such as secretory routes, post-translational modifications and enzymatic processing, that govern their extracellular functions in time and space. Release of alarmins from mesenchymal cells is a highly relevant mechanism by which immune cells can be alerted of tissue damage, and alarmins play a key role in the development of acute or chronic inflammatory diseases and in cancer development.

Early markers for myocardial ischemia and sudden cardiac death

The post-mortem diagnosis of acute myocardial ischemia remains a challenge for both clinical and forensic pathologists. We performed an experimental study (ligation of left anterior descending coronary artery in rats) in order to identify early markers of myocardial ischemia, to further apply to forensic and clinical pathology in cases of sudden cardiac death. Using immunohistochemistry, Western blots, and gene expression analyses, we investigated a number of markers, selected among those which are currently used in emergency departments to diagnose myocardial infarction and those which are under investigation in basic research and autopsy pathology studies on cardiovascular diseases. The study was performed on 44 adult male Lewis rats, assigned to three experimental groups: control, sham-operated, and operated. The durations of ischemia ranged between 5 min and 24 h. The investigated markers were troponins I and T, myoglobin, fibronectin, C5b-9, connexin 43 (dephosphorylated), JunB, cytochrome c, and TUNEL staining. The earliest expressions (≤30 min) were observed for connexin 43, JunB, and cytochrome c, followed by fibronectin (≤1 h), myoglobin (≤1 h), troponins I and T (≤1 h), TUNEL (≤1 h), and C5b-9 (≤2 h). By this investigation, we identified a panel of true early markers of myocardial ischemia and delineated their temporal evolution in expression by employing new technologies for gene expression analysis, in addition to traditional and routine methods (such as histology and immunohistochemistry). Moreover, for the first time in the autopsy pathology field, we identified, by immunohistochemistry, two very early markers of myocardial ischemia: dephosphorylated connexin 43 and JunB.

Dityrosine as a marker of acute myocardial infarction? Experiments with the isolated Langendorff heart

The isolated Langendorff heart was used to evaluate dityrosine as a marker of acute myocardial infarctions. The animal model allowed the generation of local infarctions with defined survival times, as well as infarctions with and without reperfusion. The results showed that dityrosine, at least under the conditions of the animal model, occurs very shortly after early ischemia and infarctions, since positive staining results were already obtained after a survival time of only 5 min. Furthermore, it could be proved that the occurrence of dityrosine does not depend on a reperfusion of the ischemic muscle area and that there are no differences in the staining patterns of infarctions with and without reperfusion. Positive staining results for dityrosine in control hearts without infarctions had to be considered when evaluating the tissue samples of the study hearts. In part, the positive staining results of the control hearts seemed to be an artefact of the Langendorff system, easily identifiable by a distinctive staining pattern. Positive staining results in tissue samples of hearts that suffered from arrhythmia on the other hand implied that the occurrence of dityrosine is not specific for myocardial infarctions. Taking into account the results of previous works on human tissue samples, however, these findings did not question the use of dityrosine as a diagnostic tool; they simply showed that myocardial damage due to oxidative stress might occur under various pathologic conditions.

Cardiomyocytes, endothelial cells and cardiac fibroblasts: S100A1's triple action in cardiovascular pathophysiology

Over the past decade, basic and translational research delivered comprehensive evidence for the relevance of the Ca(2+)-binding protein S100A1 in cardiovascular diseases. Aberrant expression levels of S100A1 surfaced as molecular key defects, driving the pathogenesis of chronic heart failure, arterial and pulmonary hypertension, peripheral artery disease and disturbed myocardial infarction healing. Loss of intracellular S100A1 renders entire Ca(2+)-controlled networks dysfunctional, thereby leading to cardiomyocyte failure and endothelial dysfunction. Lack of S100A1 release in ischemic myocardium compromises cardiac fibroblast function, entailing impaired damage healing. This review focuses on molecular pathways and signaling cascades regulated by S100A1 in cardiomyocytes, endothelial cells and cardiac fibroblasts in order to provide an overview of our current mechanistic understanding of S100A1's action in cardiovascular pathophysiology.

Role of Cardiac Myocytes Heart Fatty Acid Binding Protein Depletion (H-FABP) in Early Myocardial Infarction in Human Heart (Autopsy Study)

BACKGROUND:

Many immunohistochemical markers have been used in the postmortem detection of early myocardial infarction.

AIM:

In the present study we examined the role of Heart-type fatty acid binding protein (H-FABP), in the detection of early myocardial infarction.

MATERIAL AND METHODS:

We obtained samples from 40 human autopsy hearts with/without histopathological signs of ischemia.

RESULTS:

All cases of definite and probable myocardial infarction showed a well-defined area of H-FABP depletion. All of the control cases showed strong H-FABP expression, except two markedly autolysed myocardial samples that showed affected antigenicity.

CONCLUSION:

Thus, we suggest H-FABP as being one of the valuable tools facing the problem of postmortem detection of early myocardial infarction/ischemia, but not in autolysis.

Inflammatory and fibrotic responses of cardiac fibroblasts to myocardial damage associated molecular patterns (DAMPs)

Cardiac fibroblasts (CF) are well-established as key regulators of extracellular matrix (ECM) turnover in the context of myocardial remodelling and fibrosis. Recently, this cell type has also been shown to act as a sensor of myocardial damage by detecting and responding to damage-associated molecular patterns (DAMPs) upregulated with cardiac injury. CF express a range of innate immunity pattern recognition receptors (TLRs, NLRs, IL-1R1, RAGE) that are stimulated by a host of different DAMPs that are evident in the injured or remodelling myocardium. These include intracellular molecules released by necrotic cells (heat shock proteins, high mobility group box 1 protein, S100 proteins), proinflammatory cytokines (interleukin-1α), specific ECM molecules up-regulated in response to tissue injury (fibronectin-EDA, tenascin-C) or molecules modified by a pathological environment (advanced glycation end product-modified proteins observed with diabetes). DAMP receptor activation on fibroblasts is coupled to altered cellular function including changes in proliferation, migration, myofibroblast transdifferentiation, ECM turnover and production of fibrotic and inflammatory paracrine factors, which directly impact on the heart's ability to respond to injury. This review gives an overview of the important role played by CF in responding to myocardial DAMPs and how the DAMP/CF axis could be exploited experimentally and therapeutically.

Clinical impact of circulating miR-26a, miR-191, and miR-208b in plasma of patients with acute myocardial infarction

Background

Aberrant expression of several types of miRNAs has been reported in acute myocardial infarction (AMI). The objective of our study was to compare miRNA expression in AMI patients and normal healthy people and determine whether miR-26a, miR-191, and miR-208b could be measured in plasma as indicators for AMI.

Methods

Detection of AMI patients and normal persons by using miRNA microarray chip analysis and miR-26a, miR-191, and miR-208b was screened out. Eighty-seven AMI patients and eighty-seven homogeneous healthy individuals were recruited. Total mRNA including miRNA was isolated and miR-26a, miR-191, and miR-208b expression were determined by qRT-PCR. Receiver operating characteristic curve analysis was performed to evaluate the instructive power of miR-26a, miR-191, and miR-208b for AMI. Dual-luciferase reporter assays indicated p21 is a direct target of miR-208b.

Results

miR-26a and miR-191 were low expressed in AMI compared with normal healthy people, but miR-208b was expressed at a high level in AMI. miR-26a showed an area under the curve (AUC) of 0.745, with a sensitivity of 73.6 % and a specificity of 72.4 %.The AUC for miR-191 was 0.669, with a sensitivity of 62.1 % and a specificity of 69.0 %.The AUC for miR-208b was 0.674, with a sensitivity of 59.8 % and a specificity of 73.6 %.

Conclusions

miR-208b was significantly increased in the AMI compared with healthy people, while miR-26a and miR-191 were decreased. miR-26a, miR-191, and miR-208b were potential indices of AMI, and miR-208b was more effective in patients with non-ST-elevation myocardial infarction.

Role of S100A1 in hypoxia-induced inflammatory response in cardiomyocytes via TLR4/ROS/NF-κB pathway

Objectives

S100A1 plays a crucial role in hypoxia-induced inflammatory response in cardiomyocytes. However, the role of S100A1 in hypoxia-induced inflammatory response in cardiomyocytes is still unknown.

Methods

enzyme-linked immunosorbent assay (ELISA) was performed for the determination of inflammatory cytokines. Immunocytochemistry and immunofluorescence, Western blot analysis and Real-time polymerase chain reaction (RT-PCR) were conducted to assess protein or mRNA expressions. Fluorogenic probe dihydroethidium (DHE) was used to evaluate the generation of reactive oxygen species (ROS) while Hoechst 33342 staining for apoptosis. Small interfering RNA (siRNA) for S100A1 was used to evaluate the role of S100A1.

Key findings

The levels of ROS and inflammatory cytokine including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-8 in H9c2 cells were increased remarkably by hypoxia. However, IL-37 protein or mRNA levels were decreased significantly. Both Toll-like receptor 4 (TLR4) inhibitor Ethyl (6R)-6-[N-(2-Chloro-4fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate (TAK-242) treatment or siRNA S100A1 downregulated TLR4 expression and inflammatory cytokine level and mRNA in H9c2 cells, as well as weakening ROS and phospho-p65 Nuclear factor (NF)-κB levels. Further, S100A1 treatment significantly reduced TNF-α protein or mRNA level whereas enhanced IL-37 protein or mRNA level, and could attenuate ROS and phospho-p65 NF-κB levels.

Conclusions

Our results demonstrate that S100A1 can regulate the inflammatory response and oxidative stress in H9C2 cells via TLR4/ROS/NF-κB pathway. These findings provide an interesting strategy for protecting cardiomyocytes from hypoxia-induced inflammatory response.

Can early myocardial infarction-related deaths be diagnosed using postmortem urotensin receptor expression levels?

PURPOSE

Myocardial infarction (MI) is one of the most prevalent causes of sudden adult death. It is difficult to diagnose early MI postmortem because there are no typical or characteristic changes in morphology. In this study, changes in the level of the mRNA for the urotensin receptor (UR) were investigated postmortem to determine the suitability of UR as a biomarker for diagnosis of early MI after death.

METHODS

An MI rat model was developed by injecting rats with isoproterenol (ISO) (lethal dose 850 mg/kg) or normal saline (control group). The hearts of rats in the control and ISO-induced MI groups were harvested at 0, 1, 3, 6, 12, 24, 48, and 72 h (h) postmortem. The hearts were then immediately submerged in 1 mL of RNA stabilization solution and stored at 4 °C for <1 week before RNA extraction. Relative UR expression analysis was performed using the StepOne Plus Real Time PCR System with cDNA synthesized from rat heart.

RESULTS

Postmortem UR mRNA expression was higher in the ISO-induced MI group than in the control group, at both 4 and 20 °C, at all of the time points examined except 72 h postmortem (p < 0.0001). The largest increases were observed at ambient temperature and 6 h postmortem.

CONCLUSIONS

Based on our findings, increased postmortem UR expression could serve as a biomarker to aid diagnosis of early MI.

Clinical impact of circulating miR-133, miR-1291 and miR-663b in plasma of patients with acute myocardial infarction

Background

Acute myocardial infarction (AMI) is one of the leading causes for death in both developed and developing countries and it is the single largest cause of death in the United States, responsible for 1 out of every 6 deaths. The objective of this study was to determine microRNA (miRNA) expression in AMI and determine whether miR-133, miR-1291 and miR-663b could be measured in plasma as a biomarker for recurrence.

Methods

Patients with AMI and those without AMI were retrospectively recruited for a comparison of their plasma miR-133, miR-1291 and miR-663b expression.

Results

miR-133, miR-1291 and miR-663b levels were significantly overexpressed in AMI compared with Non-AMI. MiR-133 showed an AUC of 0.912, with a sensitivity of 81.1% and a specificity of 91.2%. The AUC for miR-1291 was 0.695, with a sensitivity of 78.4% and a specificity of 89.5%. The AUC for miR-663b was 0.611, with a sensitivity of 72.4% and a specificity of 76.5%.

Conclusions

This study demonstrated that the levels of miR-133, miR-1291 and miR-663b are associated with AMI. The potential of these miRNAs as biomarkers to improve patient stratification according to the risk of AMI and as circulating biomarkers for the AMI progonos warrants further study.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/8183629061241474

S100A1 is released from ischemic cardiomyocytes and signals myocardial damage via Toll-like receptor 4

Members of the S100 protein family have been reported to function as endogenous danger signals (alarmins) playing an active role in tissue inflammation and repair when released from necrotic cells. Here, we investigated the role of S100A1, the S100 isoform with highest abundance in cardiomyocytes, when released from damaged cardiomyocytes during myocardial infarction (MI). Patients with acute MI showed significantly increased S100A1 serum levels. Experimental MI in mice induced comparable S100A1 release. S100A1 internalization was observed in cardiac fibroblasts (CFs) adjacent to damaged cardiomyocytes. In vitro analyses revealed exclusive S100A1 endocytosis by CFs, followed by Toll-like receptor 4 (TLR4)-dependent activation of MAP kinases and NF-κB. CFs exposed to S100A1 assumed an immunomodulatory and anti-fibrotic phenotype characterized i.e. by enhanced intercellular adhesion molecule-1 (ICAM1) and decreased collagen levels. In mice, intracardiac S100A1 injection recapitulated these transcriptional changes. Moreover, antibody-mediated neutralization of S100A1 enlarged infarct size and worsened left ventricular functional performance post-MI. Our study demonstrates alarmin properties for S100A1 from necrotic cardiomyocytes. However, the potentially beneficial role of extracellular S100A1 in MI-related inflammation and repair warrants further investigation.

A cause of Sudden Cardiac Deaths on Autopsy Findings; a Four-Year Report

INTRODUCTION

Incidence of sudden cardiac death (SCD) has been steadily increasing all over the world. While knowing the cause of SCD is one of the favorites of the physicians involved with these cases, it is very difficult and challenging task for the forensic physician. The present report is a prospective study regarding cause of SCDs on autopsy examination in four-year period, Bangalore, India.

METHODS

The present prospective study is based on autopsy observations, carried out for four-year period from 2008 to 2011, and analyzed for cause of SCDs. The cases were chosen as per the definition of sudden death and autopsied. The material was divided into natural and unnatural groups. Finally, on histopathology, gross examination, hospital details, circumstantial, and police reports the cause of death was inferred.

RESULTS

A total of 2449 autopsy was conducted of which 204 cases were due to SCD. The highest SCDs were reported in 50-60 years age group (62.24%; n-127), followed closely by the age group 60-69 (28.43%; n-58). Male to female ratio was around 10:1. The maximum number of deaths (n=78) was within few hours (6 hours) after the onset of signs and symptoms. In 24 (11.8%) cases major narrowing was noted in both the main coronaries, in 87 (42.6%) cases in the left anterior descending coronary artery (LAD), and in 18 (51.5%) cases in the right coronary artery (RCA). The major cardiac pathology resulting in sudden death was coronary artery disease (n-116; 56.86%) and myocardial infarction (n-104; 50.9%). most of the SCDs occurred in the place of residence (n-80; 39.2%) followed closely by death in hospital (n-49; 24.01%).

CONCLUSION

Coronary occlusion was the major contributory cause of sudden death with cardiac origin and the highest number of deaths were reported in the age 50-59 years with male to female ratio of 10:1.