Proteomic mapping of proteins released during necrosis and apoptosis from cultured neonatal cardiac myocytes

MG53: A new protagonist in the precise treatment of cardiomyopathies

Cardiomyopathies (CMs) are highly heterogeneous progressive heart diseases characterised by structural and functional abnormalities of the heart, whose intricate pathogenesis has resulted in a lack of effective treatment options. Mitsugumin 53 (MG53), also known as Tripartite motif protein 72 (TRIM72), is a tripartite motif family protein from the immuno-proteomic library expressed primarily in the heart and skeletal muscle. Recent studies have identified MG53 as a potential cardioprotective protein that may play a crucial role in CMs. Therefore, the objective of this review is to comprehensively examine the underlying mechanisms mediated by MG53 responsible for myocardial protection, elucidate the potential role of MG53 in various CMs as well as its dominant status in the diagnosis and prognosis of human myocardial injury, and evaluate the potential therapeutic value of recombinant human MG53 (rhMG53) in CMs. It is expected to yield novel perspectives regarding the clinical diagnosis and therapeutic treatment of CMs.

Multipronged regulation of autophagy and apoptosis: emerging role of TRIM proteins

TRIM proteins are characterized by their conserved N-terminal RING, B-box, and coiled-coil domains. These proteins are efficient regulators of autophagy, apoptosis, and innate immune responses and confer immunity against viruses and bacteria. TRIMs function as receptors or scaffold proteins that target substrates for autophagy-mediated degradation. Most TRIMs interact with the BECN1-ULK1 complex to form TRIMosomes, thereby efficiently targeting substrates to autophagosomes. They regulate the functions of ATG proteins through physical interactions or ubiquitination. TRIMs affect the lipidation of MAP1LC3B1 to form MAP1LC3B2, which is a prerequisite for phagophore and autophagosome formation. In addition, they regulate MTOR kinase and TFEB, thereby regulating the expression of ATG genes. TRIM proteins are efficient regulators of apoptosis and are crucial for regulating cell proliferation and tumor formation. Many TRIM proteins regulate intrinsic and extrinsic apoptosis via the cell surface receptors TGFBR2, TNFRSF1A, and FAS. Mitochondria modulate the anti- and proapoptotic functions of BCL2, BAX, BAK1, and CYCS. These proteins use a multipronged approach to regulate the intrinsic and extrinsic apoptotic pathways, culminating in coordinated activation or inhibition of the initiator and executor CASPs. Furthermore, TRIMs can have a dual effect in determining cell fate and are therefore crucial for cellular homeostasis. In this review, we discuss mechanistic insights into the role of TRIM proteins in regulating autophagy and apoptosis, which can be used to better understand cellular physiology. These findings can be used to develop therapeutic interventions to prevent or treat multiple genetic and infectious diseases.

Methylomic, Proteomic, and Metabolomic Correlates of Traffic-Related Air Pollution in the Context of Cardiorespiratory Health: A Systematic Review, Pathway Analysis, and Network Analysis

A growing body of literature has attempted to characterize how traffic-related air pollution (TRAP) affects molecular and subclinical biological processes in ways that could lead to cardiorespiratory disease. To provide a streamlined synthesis of what is known about the multiple mechanisms through which TRAP could lead to cardiorespiratory pathology, we conducted a systematic review of the epidemiological literature relating TRAP exposure to methylomic, proteomic, and metabolomic biomarkers in adult populations. Using the 139 papers that met our inclusion criteria, we identified the omic biomarkers significantly associated with short- or long-term TRAP and used these biomarkers to conduct pathway and network analyses. We considered the evidence for TRAP-related associations with biological pathways involving lipid metabolism, cellular energy production, amino acid metabolism, inflammation and immunity, coagulation, endothelial function, and oxidative stress. Our analysis suggests that an integrated multi-omics approach may provide critical new insights into the ways TRAP could lead to adverse clinical outcomes. We advocate for efforts to build a more unified approach for characterizing the dynamic and complex biological processes linking TRAP exposure and subclinical and clinical disease and highlight contemporary challenges and opportunities associated with such efforts.

The role of glycolytic metabolic pathways in cardiovascular disease and potential therapeutic approaches

Cardiovascular disease (CVD) is a major threat to human health, accounting for 46% of non-communicable disease deaths. Glycolysis is a conserved and rigorous biological process that breaks down glucose into pyruvate, and its primary function is to provide the body with the energy and intermediate products needed for life activities. The non-glycolytic actions of enzymes associated with the glycolytic pathway have long been found to be associated with the development of CVD, typically exemplified by metabolic remodeling in heart failure, which is a condition in which the heart exhibits a rapid adaptive response to hypoxic and hypoxic conditions, occurring early in the course of heart failure. It is mainly characterized by a decrease in oxidative phosphorylation and a rise in the glycolytic pathway, and the rise in glycolysis is considered a hallmark of metabolic remodeling. In addition to this, the glycolytic metabolic pathway is the main source of energy for cardiomyocytes during ischemia-reperfusion. Not only that, the auxiliary pathways of glycolysis, such as the polyol pathway, hexosamine pathway, and pentose phosphate pathway, are also closely related to CVD. Therefore, targeting glycolysis is very attractive for therapeutic intervention in CVD. However, the relationship between glycolytic pathway and CVD is very complex, and some preclinical studies have confirmed that targeting glycolysis does have a certain degree of efficacy, but its specific role in the development of CVD has yet to be explored. This article aims to summarize the current knowledge regarding the glycolytic pathway and its key enzymes (including hexokinase (HK), phosphoglucose isomerase (PGI), phosphofructokinase-1 (PFK1), aldolase (Aldolase), phosphoglycerate metatase (PGAM), enolase (ENO) pyruvate kinase (PKM) lactate dehydrogenase (LDH)) for their role in cardiovascular diseases (e.g., heart failure, myocardial infarction, atherosclerosis) and possible emerging therapeutic targets.

Saponins of Panax japonicus ameliorates cardiac aging phenotype in aging rats by enhancing basal autophagy through AMPK/mTOR/ULK1 pathway

Heart disease is a significant health concern for elderly individuals, with heart aging being the primary cause. Recent studies have shown that autophagy can play a protective role in preventing cardiac aging. Our previous research confirmed that Chikusetsu saponin IVa, a fundamental component of Saponins of Panax japonics (SPJ), can enhance basic autophagy levels in cardiomyocyte of isoproterenol induced cardiac fibrosis mice. However, it remains unclear whether SPJ possesses a protective effect on cardiac dysfunction during the natural aging process. Rats were randomly divided into four groups: adult control group (6 months old), aging group (24 months old), aging group treated with 10 mg/kg SPJ, and aging group treated with 30 mg/kg SPJ. The heart function, blood pressure, and heart mass index (HMI) were measured. Hematoxylin and eosin staining (H&E) and Wheat Germ Agglutinin (WGA) staining were used to observe the changes in morphology, while Masson staining was used to examine collagen deposition in the rat hearts and CD45 immunohistochemistry was conducted to examine the macrophage infiltration in heart tissues. TUNEL kit was used to detect apoptosis level of cardiomyocyte, and western blot was used to evaluate autophagy-related proteins as well as AMPK/mTOR/ULK1 pathway-related markers. SPJ treatment improved the cardiac function, reduced HMI, attenuated myocardial fiber disorder, inhibited inflammatory cell infiltration, and decreased collagen deposition and cardiomyocyte apoptosis in aging rats. Additionally, SPJ treatment decreased the expression of aging-related proteins and restored the expression of autophagy-related markers. SPJ activated autophagy through the activation of AMPK, which in turn increased the phosphorylation of ULK1(Ser555), while inhibited the phosphorylation of mTOR and ULK1(Ser757). Our study demonstrates that SPJ improves the cardiac function of aging rats by enhancing basal autophagy through the AMPK/mTOR/ULK1 pathway. These results offer a theoretical foundation and empirical evidence to support the clinical advancement of SPJ in enhancing age-related cardiac dysfunction.

Methylomic, proteomic, and metabolomic correlates of traffic-related air pollution: A systematic review, pathway analysis, and network analysis relating traffic-related air pollution to subclinical and clinical cardiorespiratory outcomes

A growing body of literature has attempted to characterize how traffic-related air pollution (TRAP) affects molecular and subclinical biological processes in ways that could lead to cardiorespiratory disease. To provide a streamlined synthesis of what is known about the multiple mechanisms through which TRAP could lead cardiorespiratory pathology, we conducted a systematic review of the epidemiological literature relating TRAP exposure to methylomic, proteomic, and metabolomic biomarkers in adult populations. Using the 139 papers that met our inclusion criteria, we identified the omic biomarkers significantly associated with short- or long-term TRAP and used these biomarkers to conduct pathway and network analyses. We considered the evidence for TRAP-related associations with biological pathways involving lipid metabolism, cellular energy production, amino acid metabolism, inflammation and immunity, coagulation, endothelial function, and oxidative stress. Our analysis suggests that an integrated multi-omics approach may provide critical new insights into the ways TRAP could lead to adverse clinical outcomes. We advocate for efforts to build a more unified approach for characterizing the dynamic and complex biological processes linking TRAP exposure and subclinical and clinical disease, and highlight contemporary challenges and opportunities associated with such efforts.

Expression of intra-tumoral necrosis-associated cytokine pattern correlated with prognosis and immune status in glioma

Intra-tumoral necrosis (ITN) is reported to be an independent prognostic factor in glioma. However, knowledge of ITN is mainly limited to pseudopalisadwe, while its other aspects were neglected. Therefore, a deeper understanding of ITN could be valuable for understanding its exact role in glioma. The only reliable ITN model was time-dependently achieved with the GL261 syngeneic mouse model. The ITN-associated expression pattern was enriched from RNA sequencing. TCGA glioma samples were clustered into a high-expression group (HEG) and a low-expression group (LEG) based on their pattern and their association with prognosis, clinical status, immune status, and therapeutic responsiveness were compared. Mouse glioma with ITN demonstrated invasive histology. Cytokine signaling was significantly enriched in necrotic mouse glioma compared with non-necrotic glioma tissues. Nine pro-inflammatory (IL6, PPBP, IL1A, TNFSF11, CXCL11, CXCL9, CXCL10, CXCL3, and CCL8) and two anti-inflammatory cytokine (IL1RN and IL10) genes were found to be related to ITN-associated cytokine patterns. Comparative analysis showed that HEG had a significantly shorter survival time, five differentially distributed clinical statuses, more infiltrated immune cells, greater expression of immune checkpoints, and better therapeutic responsiveness than LEG. In conclusion, the ITN-associated cytokine pattern is characteristically expressed in glioma with ITN and might indicate necrosis missed in histology diagnosis. Its expression pattern could predict the prognosis, tumor grade, immune status, and therapeutic responsiveness of glioma patients.

Vaping additives cannabinoid oil and vitamin E acetate adhere to and damage the human airway epithelium

E-cigarette, or vaping product use-associated lung injury (EVALI), is a severe respiratory disorder that caused a sudden outbreak of hospitalized young people in 2019. Using cannabis oil containing vaping products, including vitamin E acetate contaminants, was found to be strongly associated with EVALI. However, the underlying tissue impacts of the condition are still largely unknown. Here, we focused on the vehicle cannabinoid oil (CBD oil) and contaminant vitamin E acetate (VEA) effects on airway epithelial cells. Primary human bronchial epithelial (HBE) cultures were exposed to e-liquid aerosols that contained CBD oil and VEA in combination or the common e-liquid components PG/VG with and without nicotine. Cell viability analysis indicated dramatically increased cell death counts after 3 days of CBD exposure, and this effect was even higher after CBD + VEA exposure. Microscopic examination of the cultures revealed cannabinoid and VEA depositions on the epithelial surfaces and cannabinoid accumulation in exposed cells, followed by cell death. These observations were supported by proteomic analysis of the cell secretions that exhibited increases in known markers of airway epithelial toxicity, such as xenobiotic enzymes, factors related to oxidative stress response, and cell death indicators. Overall, our study provides insights into the association between cannabinoid oil and vitamin E acetate vaping and lung injury. Collectively, our results suggest that the adherent accumulation of CBD oil on airway surfaces and the cellular uptake of both CBD oil- and VEA-containing condensates cause elevated metabolic stress, leading to increased cell death rates in human airway epithelial cultures.

ROR2 promotes epithelial-mesenchymal transition by hyperactivating ERK in melanoma

Receptor tyrosine kinase-like orphan receptor 2 (ROR2) is a protein with important functions during embryogenesis that is dysregulated in human cancer. An intriguing feature of this receptor is that it plays opposite roles in different tumor types either promoting or inhibiting tumor progression. Understanding the complex role of this receptor requires a more profound exploration of both the altered biological and molecular mechanisms. Here, we describe that ROR2 promotes Epithelial-Mesenchymal Transition (EMT) by inducing cadherin switch and the upregulation of the transcription factors ZEB1, Twist, Slug, Snail, and HIF1A, together with a mesenchymal phenotype and increased migration. We show that ROR2 activates both p38 and ERK mitogen-activated protein kinase pathways independently of Wnt5a. Further, we demonstrated that the upregulation of EMT-related proteins depends on the hyperactivation of the ERK pathway far above the typical high constitutive activity observed in melanoma. In addition, ROR2 also promoted ERK phosphorylation, EMT, invasion, and necrosis in xenotransplanted mice. ROR2 also associates with EMT in tumor samples from melanoma patients where analysis of large cohorts revealed that increased ROR2 levels are linked to EMT signatures. This important role of ROR2 translates into melanoma patient' s prognosis since elevated ROR2 levels reduced overall survival and distant metastasis-free survival of patients with lymph node metastasis. In sum, these results demonstrate that ROR2 contributes to melanoma progression by inducing EMT and necrosis and can be an attractive therapeutic target for melanoma.

Diabetes modulation of the myocardial infarction- acute kidney injury axis

Since there is crosstalk in functions of the heart and kidney, acute or chronic injury in one of the two organs provokes adaptive and/or maladaptive responses in both organs, leading to cardiorenal syndrome (CRS). Acute kidney injury (AKI) induced by acute heart failure is referred to as type 1 CRS, and a frequent cause of this type of CRS is acute myocardial infarction (AMI). Diabetes mellitus increases the risk of AMI and also the risk of AKI of various causes. However, there have been only a few studies in which animal models of diabetes were used to examine how diabetes modulates AMI-induced AKI. In this review, we summarize findings regarding the mechanisms of type 1 CRS and the impact of diabetes on both AMI and renal susceptibility to AKI and we discuss mechanisms by which diabetes modulates AMI-induced AKI. Hemodynamic alterations induced by AMI could be augmented by diabetes via its detrimental effect on infarct size and contractile function of the non-infarcted region in the heart. Diabetes increases susceptibility of renal cells to hypoxia and oxidative stress by modulation of signaling pathways that regulate cell survival and autophagy. Recent studies have shown that diabetes mellitus even at early stage of cardiomyopathy/nephropathy predisposes the kidney to AMI-induced AKI, in which activation of toll-like receptors and reactive oxygen species derived from NADPH oxidases are involved. Further analysis of crosstalk between diabetic cardiomyopathy and diabetic kidney disease is necessary for obtaining a more comprehensive understanding of modulation of the AMI-AKI axis by diabetes.

Differentiating necrotizing soft tissue infections from cellulitis by soft tissue infectious fluid analysis: a pilot study

Background

We conducted this study to evaluate the characteristics of the infectious fluid in soft tissue infection and investigate the utility of the biochemical tests and Gram stain smear of the infectious fluid in distinguishing necrotizing soft tissue infection (NSTI) from cellulitis.

Methods

This retrospective cohort study was conducted in a tertiary care hospital in Taiwan. From April 2019 to October 2020, patients who were clinically suspected of NSTI with infectious fluid accumulation along the deep fascia and received successful ultrasound-guided aspiration were enrolled. Based on the final discharge diagnosis, the patients were divided into NSTI group, which was supported by the surgical pathology report, or cellulitis group. The t test method and Fisher’s exact test were used to compare the difference between two groups. The receiver–operator characteristic (ROC) curves and area under the ROC curve (AUC) were used to evaluate the discriminating ability.

Results

Total twenty-five patients were enrolled, with 13 patients in NSTI group and 12 patients in cellulitis group. The statistical analysis showed lactate in fluid (AUC = 0.937) and LDH in fluid (AUC = 0.929) had outstanding discrimination. The optimal cut-off value of fluid in lactate was 69.6 mg/dL with corresponding sensitivity of 100% and specificity of 76.9%. The optimal cut-off value of fluid in LDH was 566 U/L with corresponding sensitivity of 83.3% and a specificity of 92.3%. In addition, albumin in fluid (AUC = 0.821), TP in fluid (AUC = 0.878) and pH in fluid (AUC = 0.858) also had excellent diagnostic accuracy for NSTI. The Gram stain smear revealed 50% bacteria present in NSTI group and all the following infectious fluid culture showed bacteria growth.

Conclusions

The analysis of infectious fluid along the deep fascia might provide high diagnostic accuracy to differentiate NSTI from cellulitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13017-022-00404-4.

Cardiac effects and clinical applications of MG53

Heart disease remains the leading cause of mortality globally, so further investigation is required to identify its underlying mechanisms and potential targets for treatment and prevention. Mitsugumin 53 (MG53), also known as TRIM72, is a TRIM family protein that was found to be involved in cell membrane repair and primarily found in striated muscle. Its role in skeletal muscle regeneration and myogenesis has been well documented. However, accumulating evidence suggests that MG53 has a potentially protective role in heart tissue, including in ischemia/reperfusion injury of the heart, cardiomyocyte membrane injury repair, and atrial fibrosis. This review summarizes the regulatory role of MG53 in cardiac tissues, current debates regarding MG53 in diabetes and diabetic cardiomyopathy, as well as highlights potential clinical applications of MG53 in treating cardiac pathologies.

Phosphorylation Ratio Determination in Fresh-Frozen and Formalin-Fixed Paraffin-Embedded Tissue with Targeted Mass Spectrometry

Formalin-fixed paraffin-embedded (FFPE) tissues are routinely prepared and collected for diagnostics in pathology departments. These are, therefore, the most accessible research sources in pathology archives. In this study we investigated whether we can apply a targeted and quantitative parallel reaction monitoring (PRM) method for FFPE tissue samples in a sensitive and reproducible way. The feasibility of this technical approach was demonstrated for normal brain and glioblastoma multiforme tissues. Two methods were used: PRM measurement of a tryptic digest without phosphopeptide enrichment (Direct-PRM) and after Fe-NTA phosphopeptide enrichment (Fe-NTA-PRM). With these two methods, the phosphorylation ratio could be determined for four selected peptide pairs that originate from neuroblast differentiation-associated protein (AHNAK S5448-p), calcium/calmodulin-dependent protein kinase type II subunit delta (CAMK2D T337-p), eukaryotic translation initiation factor 4B (EIF4B S93-p), and epidermal growth factor receptor (EGFR S1166-p). In normal brain FFPE tissues, the Fe-NTA-PRM method enabled the quantification of targeted phosphorylated peptides with high reproducibility (CV < 14%). Our results indicate that formalin fixation does not impede relative quantification of a phospho-site and its phosphorylation ratio in FFPE tissues. The developed workflow combining these methods opens ways to study archival FFPE tissues for phosphorylation ratio determination in proteins.

Mesencephalic astrocyte-derived neurotrophic factor is an ER-resident chaperone that protects against reductive stress in the heart

We have previously demonstrated that ischemia/reperfusion (I/R) impairs endoplasmic reticulum (ER)-based protein folding in the heart and thereby activates an unfolded protein response sensor and effector, activated transcription factor 6α (ATF6). ATF6 then induces mesencephalic astrocyte-derived neurotrophic factor (MANF), an ER-resident protein with no known structural homologs and unclear ER function. To determine MANF's function in the heart in vivo, here we developed a cardiomyocyte-specific MANF-knockdown mouse model. MANF knockdown increased cardiac damage after I/R, which was reversed by AAV9-mediated ectopic MANF expression. Mechanistically, MANF knockdown in cultured neonatal rat ventricular myocytes (NRVMs) impaired protein folding in the ER and cardiomyocyte viability during simulated I/R. However, this was not due to MANF-mediated protection from reactive oxygen species generated during reperfusion. Because I/R impairs oxygen-dependent ER protein disulfide formation and such impairment can be caused by reductive stress in the ER, we examined the effects of the reductive ER stressor DTT. MANF knockdown in NRVMs increased cell death from DTT-mediated reductive ER stress, but not from nonreductive ER stresses caused by thapsigargin-mediated ER Ca²⁺ depletion or tunicamycin-mediated inhibition of ER protein glycosylation. In vitro, recombinant MANF exhibited chaperone activity that depended on its conserved cysteine residues. Moreover, in cells, MANF bound to a model ER protein exhibiting improper disulfide bond formation during reductive ER stress but did not bind to this protein during nonreductive ER stress. We conclude that MANF is an ER chaperone that enhances protein folding and myocyte viability during reductive ER stress.

Eleutheroside E decreases oxidative stress and NF-κB activation and reprograms the metabolic response against hypoxia-reoxygenation injury in H9c2 cells

Ischemia-reperfusion (I/R) injury causes cardiac dysfunction through several mechanisms including oxidative stress and pro-inflammation. Eleutheroside E (EE) has protective effects in ischemia tissue and anti-inflammatory action. However, the effect of EE on I/R-injured cardiomyocytes is unknown. In this study, we used in vitro H9c2 cell model to investigate the favorable role of EE on myocardial I/R injury. We found that EE administration attenuated the cardiomyocyte apoptosis induced by hypoxia-reoxygenation (H/R) injury. Further, pre-treatment with EE dramatically inhibited mitochondrial oxidative stress, IκBα phosphorylation and nuclear factor kappa B (NF-κB) subunit p65 translocation into nuclei. EE might suppress the MAPK signaling pathway to inhibit the H/R-induced NF-κB activation. Moreover, we had analyzed the metabolomic profile of H/R-injured and H/R + 100 EE-treated H9c2 cells and found that the abundance of most metabolites changed by H/R could be re-modulated by EE treatment. Pathway analysis highlighted the inhibition of fatty acid biosynthesis and alternation of arginine and proline metabolism as two potential links to the favorable effect of EE on H/R-injured cardiomyocytes. The further demonstration showed that nitric oxide (NO), a product that is solely catabolized by l-arginine and has profound anti-oxidative stress activity during H/R in cardiomyocytes, was augmented by EE. Altogether, our results provide evidence that EE may be a potential drug for myocardial I/R injury by reducing oxidative stress, NF-κB activation, and metabolic reprogramming.

Reactive Oxygen Species (ROS)-Activatable Prodrug for Selective Activation of ATF6 after Ischemia/Reperfusion Injury

We describe here the design, synthesis, and biological evaluation of a reactive oxygen species (ROS)-activatable prodrug for the selective delivery of 147, a small molecule ATF6 activator, for ischemia/reperfusion injury. ROS-activatable prodrug 1 and a negative control unable to release free drug were synthesized and examined for peroxide-mediated activation. Prodrug 1 blocks activity of 147 by its inability to undergo metabolic oxidation by ER-resident cytochrome P450 enzymes such as Cyp1A2, probed directly here for the first time. Biological evaluation of ROS-activatable prodrug 1 in primary cardiomyocytes demonstrates protection against peroxide-mediated toxicity and enhances viability following simulated I/R injury. The ability to selectively target ATF6 activation under diseased conditions establishes the potential for localized stress-responsive signaling pathway activation as a therapeutic approach for I/R injury and related protein misfolding maladies.

Glomerular filtrate proteins in acute cardiorenal syndrome

Acute cardiorenal syndrome (CRS-1) is a morbid complication of acute cardiovascular disease. Heart-to-kidney signals transmitted by "cardiorenal connectors" have been postulated, but investigation into CRS-1 has been limited by technical limitations and a paucity of models. To address these limitations, we developed a translational model of CRS-1, cardiac arrest and cardiopulmonary resuscitation (CA/CPR), and now report findings from nanoscale mass spectrometry proteomic exploration of glomerular filtrate 2 hours after CA/CPR or sham procedure. Filtrate acquisition was confirmed by imaging, molecular weight and charge distribution, and exclusion of protein specific to surrounding cells. Filtration of proteins specific to the heart was detected following CA/CPR and confirmed with mass spectrometry performed using urine collections from mice with deficient tubular endocytosis. Cardiac LIM protein was a CA/CPR-specific filtrate component. Cardiac arrest induced plasma release of cardiac LIM protein in mice and critically ill human cardiac arrest survivors, and administration of recombinant cardiac LIM protein to mice altered renal function. These findings demonstrate that glomerular filtrate is accessible to nanoscale proteomics and elucidate the population of proteins filtered 2 hours after CA/CPR. The identification of cardiac-specific proteins in renal filtrate suggests a novel signaling mechanism in CRS-1. We expect these findings to advance understanding of CRS-1.

2-aminoethoxydiphenyl borate provides an anti-oxidative effect and mediates cardioprotection during ischemia reperfusion in mice

Excessive levels of reactive oxygen species (ROS) and impaired Ca2+ homeostasis play central roles in the development of multiple cardiac pathologies, including cell death during ischemia-reperfusion (I/R) injury. In several organs, treatment with 2-aminoethoxydiphenyl borate (2-APB) was shown to have protective effects, generally believed to be due to Ca2+ channel inhibition. However, the mechanism of 2-APB-induced cardioprotection has not been fully investigated. Herein we investigated the protective effects of 2-APB treatment against cardiac pathogenesis and deciphered the underlying mechanisms. In neonatal rat cardiomyocytes, treatment with 2-APB was shown to prevent hydrogen peroxide (H2O2) -induced cell death by inhibiting the increase in intracellular Ca2+ levels. However, no 2-APB-sensitive channel blocker inhibited H2O2-induced cell death and a direct reaction between 2-APB and H2O2 was detected by 1H-NMR, suggesting that 2-APB chemically scavenges extracellular ROS and provides cytoprotection. In a mouse I/R model, treatment with 2-APB led to a considerable reduction in the infarct size after I/R, which was accompanied by the reduction in ROS levels and neutrophil infiltration, indicating that the anti-oxidative properties of 2-APB plays an important role in the prevention of I/R injury in vivo as well. Taken together, present results indicate that 2-APB treatment induces cardioprotection and prevents ROS-induced cardiomyocyte death, at least partially, by the direct scavenging of extracellular ROS. Therefore, administration of 2-APB may represent a promising therapeutic strategy for the treatment of ROS-related cardiac pathology including I/R injury.

Proteomics Research in Cardiovascular Medicine and Biomarker Discovery

Proteomics is a systems physiology discipline to address the large-scale characterization of protein species within a biological system, be it a cell, a tissue, a body biofluid, an organism, or a cohort population. Building on advances from chemical analytical platforms (e.g., mass spectrometry and other technologies), proteomics approaches have contributed powerful applications in cardiovascular biomedicine, most notably in: 1) the discovery of circulating protein biomarkers of heart diseases from plasma samples; and 2) the identification of disease mechanisms and potential therapeutic targets in cardiovascular tissues, in both preclinical models and translational studies. Contemporary proteomics investigations offer powerful means to simultaneously examine tens of thousands of proteins in various samples, and understand their molecular phenotypes in health and disease. This concise review introduces study design considerations, example applications and use cases, as well as interpretation and analysis of proteomics data in cardiovascular biomedicine.

ATF6 Decreases Myocardial Ischemia/Reperfusion Damage and Links ER Stress and Oxidative Stress Signaling Pathways in the Heart

RATIONALE

Endoplasmic reticulum (ER) stress causes the accumulation of misfolded proteins in the ER, activating the transcription factor, ATF6 (activating transcription factor 6 alpha), which induces ER stress response genes. Myocardial ischemia induces the ER stress response; however, neither the function of this response nor whether it is mediated by ATF6 is known.

OBJECTIVE

Here, we examined the effects of blocking the ATF6-mediated ER stress response on ischemia/reperfusion (I/R) in cardiac myocytes and mouse hearts.

METHODS AND RESULTS

Knockdown of ATF6 in cardiac myocytes subjected to I/R increased reactive oxygen species and necrotic cell death, both of which were mitigated by ATF6 overexpression. Under nonstressed conditions, wild-type and ATF6 knockout mouse hearts were similar. However, compared with wild-type, ATF6 knockout hearts showed increased damage and decreased function after I/R. Mechanistically, gene array analysis showed that ATF6, which is known to induce genes encoding ER proteins that augment ER protein folding, induced numerous oxidative stress response genes not previously known to be ATF6-inducible. Many of the proteins encoded by the ATF6-induced oxidative stress genes identified here reside outside the ER, including catalase, which is known to decrease damaging reactive oxygen species in the heart. Catalase was induced by the canonical ER stressor, tunicamycin, and by I/R in cardiac myocytes from wild-type but not in cardiac myocytes from ATF6 knockout mice. ER stress response elements were identified in the catalase gene and were shown to bind ATF6 in cardiac myocytes, which increased catalase promoter activity. Overexpression of catalase, in vivo, restored ATF6 knockout mouse heart function to wild-type levels in a mouse model of I/R, as did adeno-associated virus 9-mediated ATF6 overexpression.

CONCLUSIONS

ATF6 serves an important role as a previously unappreciated link between the ER stress and oxidative stress gene programs, supporting a novel mechanism by which ATF6 decreases myocardial I/R damage.

Comparative mRNA and MicroRNA Profiling during Acute Myocardial Infarction Induced by Coronary Occlusion and Ablation Radio-Frequency Currents

The ligation of the left anterior descending coronary artery is the most commonly used experimental model to induce myocardial infarction (MI) in rodents. A high mortality in the acute phase and the heterogeneity of the size of the MI obtained are drawbacks recognized in this model. In an attempt to solve the problem, our group recently developed a new MI experimental model which is based on application of myocardial ablation radio-frequency currents (AB-RF) that yielded MI with homogeneous sizes and significantly reduce acute mortality. In addition, cardiac structural, and functional changes aroused by AB-RF were similar to those seen in animals with MI induced by coronary artery ligation. Herein, we compared mRNA expression of genes that govern post-MI milieu in occlusion and ablation models. We analyzed 48 mRNAs expressions of nine different signal transduction pathways (cell survival and metabolism signs, matrix extracellular, cell cycle, oxidative stress, apoptosis, calcium signaling, hypertrophy markers, angiogenesis, and inflammation) in rat left ventricle 1 week after MI generated by both coronary occlusion and AB-RF. Furthermore, high-throughput miRNA analysis was also assessed in both MI procedures. Interestingly, mRNA expression levels and miRNA expressions showed strong similarities between both models after MI, with few specificities in each model, activating similar signal transduction pathways. To our knowledge, this is the first comparison of genomic alterations of mRNA and miRNA contents after two different MI procedures and identifies key signaling regulators modulating the pathophysiology of these two models that might culminate in heart failure. Furthermore, these analyses may contribute with the current knowledge concerning transcriptional and post-transcriptional changes of AB-RF protocol, arising as an alternative and effective MI method that reproduces most changes seem in coronary occlusion.

Short ischemia induces rat kidney mitochondria dysfunction

Renal artery clamping itself induces renal ischemia which subsequently causes renal cell injury and can lead to renal failure. The duration of warm ischemia that would be safe for postoperative kidney function during partial nephrectomy remains under investigations. Mitochondria play an important role in pathophysiology of ischemia-reperfusion induced kidney injury, however relation between ischemia time and mitochondrial dysfunction are not fully elucidated. Thus, the effects of renal ischemia (20 min, 40 min and 60 min) on mitochondrial functions were investigated by using in vitro rat ischemia model. Thus, electronmicroscopy showed that at short (20 min) ischemia mitochondria start to swell and the damage increases with the duration of ischemia. In accordance with this, a significant decrease in mitochondrial oxidative phosphorylation capacity was observed already after 20 min of ischemia with both, complex I dependent substrate glutamate/malate (52%) and complex II dependent substrate succinate (44%) which further decreased with the prolonged time of ischemia. The diminished state 3 respiration rate was associated with the decrease in mitochondrial Complex I activity and the release of cytochrome c. Mitochondrial Ca(2+) uptake was diminished by 37-49% after 20-60 min of ischemia and caspase-3 activation increased by 1.15-2.32-fold as compared to control. LDH activity changed closely with increasing time of renal ischemia. In conclusion, even short time (20 min) of warm ischemia in vitro leads to renal mitochondrial injury which increases progressively with the duration of ischemia.

Monitoring Changes in the Redox State of Myoglobin in Cardiomyocytes by Raman Spectroscopy Enables the Protective Effect of NO Donors to Be Evaluated

Raman microspectroscopy has been used to monitor changes in the redox and ligand-coordination states of the heme complex in myoglobin during the preconditioning of ex vivo cardiomyocytes with pharmacological drugs that release nitric oxide (NO). These chemical agents are known to confer protection on heart tissue against ischemia-reperfusion injury. Subsequent changes in the redox and ligand-coordination states during experimental simulations of ischemia and reperfusion have also been monitored. We found that these measurements, in real time, could be used to evaluate the preconditioning treatment of cardiomyocytes and to predict the likelihood of cell survival following a potentially lethal period of ischemia. Evaluation of the preconditioning treatment was done at the single-cell level. The binding of NO to myoglobin, giving a 6-coordinate ferrous-heme complex, was inferred from the measured Raman bands of a cardiomyocyte by comparison to pure solution of the protein in the presence of NO. A key change in the Raman spectrum was observed after perfusion of the NO-donor was completed, where, if the preconditioning treatment was successful, the bands corresponding to the nitrosyl complex were replaced by bands corresponding to metmyoglobin, Mb(III). An observation of Mb(III) bands in the Raman spectrum was made for all of the cardiomyocytes that recovered contractile function, whereas the absence of Mb(III) bands always indicated that the cardiomyocyte would be unable to recover contractile function following the simulated conditions of ischemia and reperfusion in these experiments.

Expression of calcineurin, calpastatin and heat shock proteins during ischemia and reperfusion

Objective

Calcineurin (CaN) interacts with calpains (Calpn) and causes cellular damage eventually leading to cell death. Calpastatin (Calp) is a specific Calpn inhibitor, along with CaN stimulation has been implicated in reduced cell death and self-repair. Molecular chaperones, heat shock proteins (Hsp70 and Hsp90) acts as regulators in Calpn signaling. This study aims to elucidate the role of CaN, Calp and Hsps during induced ischemia and reperfusion in primary cardiomyocyte cultures (murine).

Methods and results

Protein expression was analyzed concurrently with viability using flow cytometry (FACS) in ischemia- and reperfusion-induced murine cardiomyocyte cultures. The expression of Hsp70 and Hsp90, both being molecular chaperones, increased during ischemia with a concurrent increase in death of cells expressing these proteins. The relative expression of Hsp70 and Hsp90 during ischemia with respect to CaN was enhanced in comparison to Calp. Reperfusion slightly decreased the number of cells expressing these chaperones. There was no increase in death of cells co-expressing Hsp70 and Hsp90 along with CaN and Calp. CaN expression peaked during ischemia and subsequent reperfusion reduced its expression and cell death. Calp expression increased both during ischemia and subsequent reperfusion but cell death decreased during reperfusion.

Conclusion

The present study adds to the existing knowledge that Hsp70, Hsp90, CaN and Calp interact with each other and play significant role in cardio protection.

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Differential expression of calcineurin and calpastatin during ischemia and reperfusion.

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Enhanced ischemia induced cell death in cells expressing Hsp70 and Hsp90.

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Cardio protective role of calcineurin, calpastatin, Hsp70 and Hsp90.

Transformative Impact of Proteomics on Cardiovascular Health and Disease: A Scientific Statement From the American Heart Association

The year 2014 marked the 20th anniversary of the coining of the term proteomics. The purpose of this scientific statement is to summarize advances over this period that have catalyzed our capacity to address the experimental, translational, and clinical implications of proteomics as applied to cardiovascular health and disease and to evaluate the current status of the field. Key successes that have energized the field are delineated; opportunities for proteomics to drive basic science research, facilitate clinical translation, and establish diagnostic and therapeutic healthcare algorithms are discussed; and challenges that remain to be solved before proteomic technologies can be readily translated from scientific discoveries to meaningful advances in cardiovascular care are addressed. Proteomics is the result of disruptive technologies, namely, mass spectrometry and database searching, which drove protein analysis from 1 protein at a time to protein mixture analyses that enable large-scale analysis of proteins and facilitate paradigm shifts in biological concepts that address important clinical questions. Over the past 20 years, the field of proteomics has matured, yet it is still developing rapidly. The scope of this statement will extend beyond the reaches of a typical review article and offer guidance on the use of next-generation proteomics for future scientific discovery in the basic research laboratory and clinical settings.

Protection by the NO-Donor SNAP and BNP against Hypoxia/Reoxygenation in Rat Engineered Heart Tissue

In vitro assays could replace animal experiments in drug screening and disease modeling, but have shortcomings in terms of functional readout. Force-generating engineered heart tissues (EHT) provide simple automated measurements of contractile function. Here we evaluated the response of EHTs to hypoxia/reoxygenation (H/R) and the effect of known cardiocytoprotective molecules. EHTs from neonatal rat heart cells were incubated for 24 h in EHT medium. Then they were subjected to 180 min hypoxia (93% N₂, 7% CO₂) and 120 min reoxygenation (40% O₂, 53% N₂, 7% CO₂), change of medium and additional follow-up of 48 h. Time-matched controls (40% O₂, 53% N₂, 7% CO₂) were run for comparison. The following conditions were applied during H/R: fresh EHT medium (positive control), the NO-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 10^-7, 10^-6, 10^-5 M) or the guanylate cyclase activator brain type natriuretic peptide (BNP, 10^-9, 10^-8, 10^-7 M). Frequency and force of contraction were repeatedly monitored over the entire experiment, pH, troponin I (cTnI), lactate dehydrogenase (LDH) and glucose concentrations measured in EHT medium. Beating activity of EHTs in 24 h-medium ceased during hypoxia, partially recovered during reoxygenation and reached time-control values during follow-up. H/R was accompanied by a small increase in LDH and non-significant increase in cTnI. In fresh medium, some EHTs continued beating during hypoxia and all EHTs recovered faster during reoxygenation. SNAP and BNP showed small but significant protective effects during reoxygenation. EHTs are applicable to test potential cardioprotective compounds in vitro, monitoring functional and biochemical endpoints, which otherwise could be only measured by using in vivo or ex vivo heart preparations. The sensitivity of the model needs improvement.

Comparative Proteome Profiling during Cardiac Hypertrophy and Myocardial Infarction Reveals Altered Glucose Oxidation by Differential Activation of Pyruvate Dehydrogenase E1 Component Subunit β

Cardiac hypertrophy and myocardial infarction (MI) are two etiologically different disease forms with varied pathological characteristics. However, the precise molecular mechanisms and specific causal proteins associated with these diseases are obscure to date. In this study, a comparative cardiac proteome profiling was performed in Wistar rat models for diseased and control (sham) groups using two-dimensional difference gel electrophoresis followed by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry. Proteins were identified using Protein Pilot™ software (version 4.0) and were subjected to stringent statistical analysis. Alteration of key proteins was validated by Western blot analysis. The differentially expressed protein sets identified in this study were associated with different functional groups, involving various metabolic pathways, stress responses, cytoskeletal organization, apoptotic signaling and other miscellaneous functions. It was further deciphered that altered energy metabolism during hypertrophy in comparison to MI may be predominantly attributed to induced glucose oxidation level, via reduced phosphorylation of pyruvate dehydrogenase E1 component subunit β (PDHE1-B) protein during hypertrophy. This study reports for the first time the global changes in rat cardiac proteome during two etiologically different cardiac diseases and identifies key signaling regulators modulating ontogeny of these two diseases culminating in heart failure. This study also pointed toward differential activation of PDHE1-B that accounts for upregulation of glucose oxidation during hypertrophy. Downstream analysis of altered proteome and the associated modulators would enhance our present knowledge regarding altered pathophysiology of these two etiologically different cardiac disease forms.

Mechanistic biomarkers in acetaminophen-induced hepatotoxicity and acute liver failure: from preclinical models to patients

INTRODUCTION

Drug hepatotoxicity is a major clinical issue. Acetaminophen (APAP) overdose is especially common. Serum biomarkers used to follow patient progress reflect either liver injury or function, but focus on biomarkers that can provide insight into the basic mechanisms of hepatotoxicity is increasing and enabling us to translate mechanisms of toxicity from animal models into humans.

AREAS COVERED

We review recent advances in mechanistic serum biomarker research in drug hepatotoxicity. Specifically, biomarkers for reactive drug intermediates, mitochondrial dysfunction, nuclear DNA damage, mode of cell death and inflammation are discussed, as well as microRNAs. Emphasis is placed on APAP-induced liver injury.

EXPERT OPINION

Several serum biomarkers of reactive drug intermediates, mitochondrial damage, nuclear DNA damage, apoptosis and necrosis and inflammation have been described. These studies have provided evidence that mitochondrial damage is critical in APAP hepatotoxicity in humans, while apoptosis has only a minor role, and inflammation is important for recovery and regeneration after APAP overdose. Additionally, mechanistic serum biomarkers have been shown to predict outcome as well as, or better than, some clinical scores. In the future, such biomarkers will help determine the need for liver transplantation and, with improved understanding of the human pathophysiology, identify novel therapeutic targets.