Contribution of DNA methylation in chronic stress-induced cardiac remodeling and arrhythmias in mice

Mechanistic Insights into Suanzaoren Decoction's Improvement of Cardiac Contractile Function in Anxiety-Induced Cardiac Insufficiency

ETHNOPHARMACOLOGICAL RELEVANCE

According to traditional Chinese medicine, Anxiety-induced cardiac blood insufficiency leads to palpitations and restlessness. Suanzaoren Decoction (SD) is effective in replenishing blood and promoting blood circulation. Clinical practice has shown that it has a better therapeutic effect on cardiac insufficiency. However, its mechanism of action is still unclear.

AIM OF THE STUDY

The study aims to determine the mechanism by which SD treats chronic restraint stress (CRS)-induced anxiety-induced cardiac insufficiency (ACI).

MATERIALS AND METHODS

SD was orally administered to mice with CRS-induced ACI. Firstly, we constructed an anxiety model in mice by CRS. Subsequently, SD was investigated to assess cardiac function and pathological changes through echocardiography, H&E staining, and Masson staining. Thirdly, the function of sympathetic and parasympathetic nerves was evaluated using enzyme-linked immunosorbent assay (ELISA) and enzyme activity assays. Network pharmacology and molecular docking were employed to predict potential targets for SD treatment of cardiac insufficiency. CaMKII expression was scrutinized utilizing publicly accessible databases. CaMKII was identified as a target through immunohistochemistry and Western Blot analysis in mouse hearts. Finally, the therapeutic mechanism of SD was confirmed in injured cardiomyocytes via Western Blot and quantitative PCR.

RESULTS

SD exerted anxiolytic effects by increasing the frequency of entries into and the duration spent in open arms while reducing the time spent in the light chamber and increasing the number of transitions between light and dark chambers. Additionally, it mitigated cardiac insufficiency, as evidenced by the enhancement of left ventricular ejection fraction (LVEF) and attenuation of cardiomyocyte damage and inflammatory infiltration. However, SD did not alleviate the elevated norepinephrine (NE) and decreased Acetylcholine (Ach) in anxiety states. To investigate the mechanism of action of SD, we constructed a Drug-Component-Target-Disease network, identifying 13 potential active compounds. Additionally, leveraging bioinformatics analysis and molecular docking targeting heart diseases characterized by clinical left ventricular ejection fraction (LVEF), we focused on the CaMKII target. The ability of SD to modulate CaMKII expression and phosphorylation in the mouse heart was investigated using immunohistochemistry and Western blotting. SD was found to alleviate NE-injured cardiomyocytes by modulating the Ca2+/CaMKII/MEF2 and GATA4 pathways.

CONCLUSION

SD is a potential formula for the treatment of chronic restraint stress (CRS)-induced ACI that ameliorates cardiomyocyte injury and improves cardiac function. Its efficacy is associated with the inhibition of the Ca2+/ CaMKII /MEF2 and GATA4 signaling pathways.

Changes in DNA methylation associated with a specific mode of delivery: a pilot study

Background

The mode of delivery represents an epigenetic factor with potential to affect further development of the individual by multiple mechanisms. DNA methylation may be one of them, representing a major epigenetic mechanism involving direct chemical modification of the individual's DNA. This pilot study aims to examine whether a specific mode of delivery induces changes of DNA methylation by comparing the umbilical cord blood and peripheral blood of the newborns.

Methods

Blood samples from infants born by vaginal delivery and caesarean section were analysed to prepare the Methylseq library according to NEBNext enzymatic Methyl-seq Methylation Library Preparation Kit with further generation of target-enriched DNA libraries using the Twist Human Methylome Panel. DNA methylation status was determined using Illumina next-generation sequencing (NGS).

Results

We identified 168 differentially methylated regions in umbilical cord blood samples and 157 regions in peripheral blood samples. These were associated with 59 common biological, metabolic and signalling pathways for umbilical cord and peripheral blood samples.

Conclusion

Caesarean section is likely to represent an important epigenetic factor with the potential to induce changes in the genome that could play an important role in development of a broad spectrum of disorders. Our results could contribute to the elucidation of how epigenetic factors, such as a specific mode of delivery, could have adverse impact on health of an individual later in their life.

Pro-arrhythmic role of adrenergic spatial densities in the human atria: An in-silico study

Chronic stress among young patients (≤ 45 years old) could result in autonomic dysfunction. Autonomic dysfunction could be exhibited via sympathetic hyperactivity, sympathetic nerve sprouting, and diffuse adrenergic stimulation in the atria. Adrenergic spatial densities could alter atrial electrophysiology and increase arrhythmic susceptibility. Therefore, we examined the role of adrenergic spatial densities in creating arrhythmogenic substrates in silico. We simulated three 25 cm2 atrial sheets with varying adrenergic spatial densities (ASD), activation rates, and external transmembrane currents. We measured their effects on spatial and temporal heterogeneity of action potential durations (APD) at 50% and 20%. Increasing ASD shortens overall APD, and maximum spatial heterogeneity (31%) is achieved at 15% ASD. The addition of a few (5% to 10%) adrenergic elements decreases the excitation threshold, below 18 μA/cm2, while ASDs greater than 10% increase their excitation threshold up to 22 μA/cm2. Increase in ASD during rapid activation increases APD50 and APD20 by 21% and 41%, respectively. Activation times of captured beats during rapid activation could change by as much as 120 ms from the baseline cycle length. Rapidly activated atrial sheets with high ASDs significantly increase temporal heterogeneity of APD50 and APD20. Rapidly activated atrial sheets with 10% ASD have a high likelihood (0.7 ± 0.06) of fragmenting otherwise uniform wavefronts due to the transient inexcitability of adrenergically stimulated elements, producing an effective functional block. The likelihood of wave fragmentation due to ASD highly correlates with the spatial variations of APD20 (ρ = 0.90, p = 0.04). Our simulations provide a novel insight into the contributions of ASD to spatial and temporal heterogeneities of APDs, changes in excitation thresholds, and a potential explanation for wave fragmentation in the human atria due to sympathetic hyperactivity. Our work may aid in elucidating an electrophysiological link to arrhythmia initiation due to chronic stress among young patients.

Epigenetic Changes Associated with Different Types of Stressors and Suicide

Stress is associated with various epigenetic changes. Some stress-induced epigenetic changes are highly dynamic, whereas others are associated with lasting marks on the epigenome. In our study, a comprehensive narrative review of the literature was performed by investigating the epigenetic changes that occur with acute stress, chronic stress, early childhood stress, and traumatic stress exposures, along with examining those observed in post-mortem brains or blood samples of suicide completers and attempters. In addition, the transgenerational effects of these changes are reported. For all types of stress studies examined, the genes Nr3c1, OXTR, SLC6A4, and BDNF reproducibly showed epigenetic changes, with some modifications observed to be passed down to subsequent generations following stress exposures. The aforementioned genes are known to be involved in neuronal development and hormonal regulation and are all associated with susceptibility to mental health disorders including depression, anxiety, personality disorders, and PTSD (post-traumatic stress disorder). Further research is warranted in order to determine the scope of epigenetic actionable targets in individuals suffering from the long-lasting effects of stressful experiences.

Adult hypertensive rats are more prone to gut microflora perturbation and fibrosis in response to moderate restraint stress

Hypertension (HTN) is a common endpoint for numerous cardiovascular diseases, the prevalence of which has been quickly increasing due to a wide range of reasons. Previous research has found that following stress, ELISA and 16S rDNA sequencing indicated substantial changes in plasma cytokines or hormones, as well as alterations in gut microbiota in juvenile hypertensive rats. However, it remains still unclear how such interaction modifications affect microbial populations and organismal function. Stress-related hormones show a significant drop. Similar to earlier research, the stress group had dramatically increased release of pro-inflammatory cytokines such as IL-17. Importantly, a unified collection of tools that allows for deep and comprehensive colonic structural investigation has been developed. Stress may limit the transition of macrophages (Mφs) to M1Mφs while increasing the transfer to M2Mφs. Evidence highlighted that tight junction proteins were decreased along with enhancement in intestinal permeability. Morphological analysis revealed that the SHR-S group exhibited considerably higher levels of morphological alterations and fibrosis in colon, heart, and thoracic aorta tissues.Significant improvements in bacteria linked with short-chain fatty acid synthesis, such as Prevotella and Ruminococcus, were discovered by metagenomic analysis. Adult hypertensive rats are more susceptible to gut microbiota disruption and fibrosis as a result of mild restraint stress. This might contribute to some innovative ideas for HTN both treatment and prevention.

Stress-induced body weight loss and improvements in cardiometabolic risk factors do not translate to improved myocardial ischemic tolerance in western diet-fed mice

Although both diet-induced obesity and psychological stress are recognized as significant independent contributors to cardiometabolic and behavioral disorders, our understanding of how these two disorders interact and influence cardiometabolic risk and myocardial ischemic tolerance is limited. The aim of this study was to assess the combined effects of an obesogenic diet and psychological stress on cardiometabolic risk factors (body weight, dyslipidemia, insulin sensitivity) and postischemic cardiovascular outcomes. C57Bl/6J mice (n = 48) were subject to a combination of 22 weeks of western diet (WD) feeding and chronic restraint stress (CRS) for the last 4 weeks. Metabolic and behavioral changes were assessed using glucose tolerance tests and open field tests (OFTs), respectively. After 22 weeks, cardiac function and ischemic tolerance were assessed in Langendorff perfused hearts. WD feeding increased body weight and worsened blood lipids and insulin sensitivity. WD-fed mice also exhibited reduced exploratory behavior within the OFT. CRS reduced body weight and increased locomotion in both dietary groups and had differential effects on fasting glucose metabolism in the two dietary groups while not impacting non-fasting insulin. Although the WD only marginally reduced reperfusion left ventricular developed pressure recovery, CRS worsened reperfusion diastolic dysfunction in both dietary groups. Interestingly, despite WD+CRS animals exhibiting improved cardiometabolic parameters compared to the WD group, these changes did not translate to marked improvements to postischemic cardiac outcomes. In conclusion, in this study, combined WD feeding and CRS did not act synergistically to worsen cardiometabolic risk factors but instead improved them. Despite these cardiometabolic improvements, WD+CRS increased reperfusion end diastolic pressure which may be indicative of worsened ischemia/reperfusion injury.

A dataset of dual calcium and voltage optical mapping in healthy and hypertrophied murine hearts

Pathological hypertrophy underlies sudden cardiac death due to its high incidence of occurrence of ventricular arrhythmias. The alteration of transmural electrophysiological properties in hypertrophic cardiac murine tissue has never been explored previously. In this dataset, we have for the first time conducted high-throughput simultaneous optical imaging of transmembrane potential and calcium transients (CaT) throughout the entire hypertrophic murine hearts at high temporal and spatial resolution. Using ElectroMap, we have conducted multiple parameters analysis including action potential duration/calcium transient duration, conduction velocity, alternans and diastolic interval. Voltage-calcium latency was measured as time difference between action potential and CaT peak. The dataset therefore provides the first high spatial resolution transmural electrophysiological profiling of the murine heart, allowing interrogation of mechanisms driving ventricular arrhythmias associated with pathological hypertrophy. The dataset allows for further reuse and detailed analyses of geometrical, topological and functional analyses and reconstruction of 2-dimensional and 3-dimentional models.

Amlexanox and Forskolin Prevents Isoproterenol-Induced Cardiomyopathy by Subduing Cardiomyocyte Hypertrophy and Maladaptive Inflammatory Responses

Chronic catecholamine stress (CCS) induces the occurrence of cardiomyopathy-pathological cardiac hypertrophy (PCH), which is characterized by left ventricular systolic dysfunction (LVSD). Recently, mounting evidence has implicated myocardial inflammation in the exacerbation of pathological cardiac remodeling. However, there are currently no well-defined treatment interventions or regimes targeted at both the attenuation of maladaptive myocardial hypertrophy and inflammation during CCS to prevent PCH. G protein-coupled receptor kinase 5 (GRK5) and adenylyl cyclases (ACs)-cAMP mediates both cardiac and inflammatory responses. Also, GRK5 and ACs are implicated in stress-induced LVSD. Herein, we aimed at preventing PCH during CCS via modulating adaptive cardiac and inflammatory responses by inhibiting GRK5 and/or stimulating ACs. Isoproterenol-induced cardiomyopathy (ICM) was modeled using 0.5 mg/100 g/day isoproterenol injections for 40 days. Alterations in cardiac and inflammatory responses were assessed from the myocardia. Similarities in the immunogenicity of cardiac troponin I (cTnI) and lipopolysaccharide under CCS were assessed, and Amlexanox (35 μM/ml) and/or Forskolin (10 μM/ml) were then employed in vitro to modulate adaptive inflammatory responses by inhibiting GRK5 or activating ACs-cAMP, respectively. Subsequently, Amlexanox (2.5 mg/100 g/day) and/or Forskolin (0.5 mg/100 g/day) were then translated into in vivo during CCS to modulate adaptive cardiac and inflammatory responses. The effects of Amlexanox and Forskolin on regulating myocardial systolic functions and inflammatory responses during CCS were ascertained afterward. PCH mice had excessive myocardial hypertrophy, fibrosis, and aggravated LVSD, which were accompanied by massive CD68⁺ inflammatory cell infiltrations. In vitro, Forskolin-AC/cAMP was effective than Amlexanox-GRK5 at downregulating proinflammatory responses during stress; nonetheless, Amlexanox and Forskolin combination demonstrated the most efficacy in modulating adaptive inflammatory responses. Individually, the translated Amlexanox and Forskolin treatment interventions were ineffective at subduing the pathological remodeling and sustaining cardiac function during CCS. However, their combination was potent at preventing LVSD during CCS by attenuating maladaptive myocardial hypertrophy, fibrosis, and inflammatory responses. The treatment intervention attained its potency mainly via Forskolin-ACs/cAMP-mediated modulation of cardiac and inflammatory responses, coupled with Amlexanox inhibition of GRK5 mediated maladaptive cascades. Taken together, our findings highlight the Amlexanox and Forskolin combination as a potential therapeutic intervention for preventing the occurrence of pathological cardiac hypertrophy during chronic stress.

Epitranscriptomics in the Heart: a Focus on m6A

PURPOSE OF REVIEW

Post-transcriptional modifications are key regulators of gene expression that allow the cell to respond to environmental stimuli. The most abundant internal mRNA modification is N6-methyladenosine (m⁶A), which has been shown to be involved in the regulation of RNA splicing, localization, translation, and decay. It has also been implicated in a wide range of diseases, and here, we review recent evidence of m⁶A's involvement in cardiac pathologies and processes.

RECENT FINDINGS

Studies have primarily relied on gain and loss of function models for the enzymes responsible for adding and removing the m⁶A modification. Results have revealed a multifaceted role for m⁶A in the heart's response to myocardial infarction, pressure overload, and ischemia/reperfusion injuries. Genome-wide analyses of mRNAs that are differentially methylated during cardiac stress have highlighted the importance of m⁶A in regulating the translation of specific categories of transcripts implicated in pathways such as calcium handling, cell growth, autophagy, and adrenergic signaling in cardiomyocytes. Regulation of gene expression by m⁶A is critical for cardiomyocyte homeostasis and stress responses, suggesting a key role for this modification in cardiac pathophysiology.

Cardiomyopathies in China: A 2018-2019 state-of-the-art review

Cardiomyopathies are diseases of the cardiac muscle and are often characterized by ventricular dilation, hypertrophy, and cardiac arrhythmia. Patients with cardiomyopathies often experience sudden death and cardiac failure and require cardiac transplantation during the course of disease progression. Early diagnosis, differential diagnosis, and genetic consultation depend on imaging techniques, genetic testing, and new emerging diagnostic tools such as serum biomarkers. The molecular genetics of cardiomyopathies has been widely studied recently. The discovery of mechanisms underlying heterogeneity and overlapping of the phenotypes of cardiomyopathies has revealed the existence of disease modifiers, and this has led to the emergence of novel disease-modifying therapy. This 2018-2019 state-of-the-art review outlines the pathogenesis, diagnosis, and treatment of cardiomyopathies in China.

Plasma cell-free DNA methylation combined with tumor mutation detection in prognostic prediction of patients with non-small cell lung cancer (NSCLC)

BACKGROUND

Lung Cancer is one of the most common cancers with high degree of malignancy, is a devastating disease with a poor prognosis worldwide. prognostic prediction for patients with non small-cell lung cancer (NSCLC) is still challenge.

MATERIAL AND METHODS

The cohort consisted of 64 consecutive patients with NSCLC identified from June1, 2014, to June 30, 2018. Liquid biopsy samples were collected. Genomic mutation DNA was calculated by including all substitutions and indels over the entire somatic, coding, sequencing length. statistical evaluations were carried out using SPSS software.

RESULTS

Quantity of total ctDNA was successfully determined in all 64 patients from whom baseline circulating DNA was available. ctDNA concentration ranged from 4000 to 3,562,000 genome equivalents per milliliter. Treatments induced a significant decrease in cancer specific markers in most patients with response to treatments, while the methylated DNA demonstrated favorable prediction efficiency regardless of the response status. Patients with ctDNA mutation and methylated DNA decreasing have favorable overall survival (P < .05). combination of genetic and methylated DNA decreasing had high reliability in predicting overall survival of patients with NSCLC.

CONCLUSIONS

We have detected both tumor mutations and methylated DNA in plasma of patients with NSCLC. Combined genetic and methylated DNA decreasing after treatment was an independent risk factor for prognosis of patients with NSCLC. Meanwhile, it had favorable predict value and had potential to be defined as a novel biomarker for patients with NSCLC.

Nitric oxide-dependent expansion of erythroid progenitors in a murine model of chronic psychological stress

Anaemia occurs frequently in patients with heart failure and its current treatment lacks clear targets. Emerging evidence suggests that erythroid progenitor cell expansion is an integral part of physiological response to anaemia associated with chronic stress. Understanding the underlying mechanism may provide a novel approach to anaemia management. In this study, we aimed to examine a role for nitric oxide (NO) in the regulation of bone marrow erythroid progenitor response to chronic stress. For this purpose, adult male mice were subjected to 2 h daily restraint stress for 7 or 14 consecutive days. The role of NO was assessed by subcutaneous injection with NG-nitro-L-arginine methyl ester, 30 min prior to each restraint. Chronic exposure to stress resulted in significantly increased number of bone marrow erythroid progenitors, and blockade of NO biosynthesis prior to daily stress completely prevented stress-induced erythroid progenitor cell expansion. Furthermore, chronic stress exposure led to altered expression of neural, endothelial and inducible nitric oxide synthases (NOS) in the bone marrow, both on mRNA and protein level. Decreased expression of neural and endothelial NOS, as well as reduced expression of NF-kappaB/p65 in bone marrow nuclear cell fraction, was accompanied by elevated bone marrow expression of inducible NOS in chronically stressed animals. This is the first study to demonstrate a role for NO in adaptive response of erythroid progenitors to chronic stress. Targeting NO production may be beneficial to improve bone marrow dysfunction and reduced erythroid progenitor cell expansion in chronic heart failure patients.