[Myocardial fibrosis: Current aspects of the problem]

Beraprost sodium attenuates the development of myocardial fibrosis after myocardial infarction by regulating GSK-3β expression in rats

OBJECTIVE

The aim of this study was to elucidate the mechanism of beraprost sodium (BPS) in the intervention of myocardial fibrosis after myocardial infarction (MI) through glycogen synthase kinase-3β (GSK-3β) and to provide new ideas for intervention in myocardial fibrosis.

MATERIALS AND METHODS

MI model rats given BPS and cardiac fibroblasts (CFs) treated with BPS and TGF-β. HE staining and Masson staining were used to detect the pathological changes of myocardial tissue. Fibrotic markers were detected by immunohistochemical staining. The expressions of GSK-3β, cAMP response element binding protein (CREB), and p-CREB were analyzed by qPCR and western blot analysis. EDU staining was used to detect the proliferation of CFs. The promoter activity of GSK-3β was detected by luciferase assay. Chromatin immunoprecipitation assay was used to detect the binding levels of GSK-3β promoter and Y-box binding protein 1 (YBX1). The levels of intracellular cyclic adenosine monophosphate (cAMP) were analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

After operation, BPS improved myocardial fibrosis and upregulated GSK-3β protein expression in male SD rats. BPS can down-regulate α-smooth muscle actin (α-SMA) level and up-regulate GSK-3β protein expression in CFs after TGF-β stimulation. Furthermore, GSK-3β knockdown can reverse the effect of BPS on TGF-β-activated CFs, enhance α-SMA expression, and promote the proliferation of CFs. BPS could regulate GSK-3β expression by promoting the binding of GSK-3β promoter to YBX1. BPS induced upregulation of p-CREB and cAMP, resulting in reduced fibrosis, which was reversed by the knockdown of GSK-3β or prostaglandin receptor (IPR) antagonists.

CONCLUSION

BPS treatment increased the binding of YBX1 to the GSK-3β promoter, and GSK-3β protein expression was upregulated, which further caused the upregulation of p-CREB and cAMP, and finally inhibited myocardial fibrosis.

Jatrorrhizine reduces myocardial infarction-induced apoptosis and fibrosis through inhibiting p53 and TGF-β1/Smad2/3 pathways in mice

PURPOSE

To explore the mechanism of jatrorrhizine on apoptosis and fibrosis induced by myocardial infarction (MI) in an animal model.

METHODS

The left anterior descending branch of coronary artery was surgically ligated to duplicate the mouse model of MI. The sham and infarcted mice were treated with normal saline once a day, while mice in experimental groups received low-dose (LD) and high-dose (HD) jatrorrhizine once a day respectively. Two weeks later, cardiac function was detected by echocardiography, and histopathological examination was performed using hematoxylin and eosin (H&E) and Masson staining. The expressions of p53, TGF-β1, Smad/2/3, Bax, Bcl-2, collagen I and collagen III were quantified using qRT-PCR and western blot assays.

RESULTS

Jatrorrhizine significantly improved left ventricular ejection fraction (LVEF) and left ventricle end-systolic (LVES) in mice. Histopathological, administration of jatrorrhizine weakened infiltration of inflammatory cells and cardiac fibrosis in myocardium of mice caused by MI. Additionally, jatrorrhizine suppressed cardiomyocyte apoptosis exhibited as its capability to reverse changes of Bax and Bcl-2 levels in myocardium caused by MI. Jatrorrhizine statistically significantly downregulated expression of collagen I and collagen III, as well as TGF-β1, Smad2/3 and p53.

CONCLUSIONS

Jatrorrhizine reduce cardiomyocyte apoptosis and fibrosis through inhibiting p53/Bax/Bcl-2 and TGF-β1/Smad2/3 signaling pathways.

Inflammatory continuum in the pathogenesis of atrial fibrillation after coronary bypass surgery

Atrial fibrillation (AF) after coronary bypass surgery is recorded in 20- 60% of patients and increase the early and long-term postoperative mortality. The aim of the review is to analyze the studies on causal relationships between damaging factors and the development of myocardial inflammation at each stage of surgical treatment in patients with multivessel coronary artery disease. In the review, myocardial inflammation is considered from the point of view of a continuum  — a chronic process that originates from the coronary endothelium damage and continuously proceeds within the AF pathogenesis after coronary bypass surgery. For the first time, the concept of inflammatory continuum for postoperative AF is introduced. The review discusses the main and latest laboratory and instrumental markers of local and systemic inflammatory response, which are informative in terms of severity and promising for improving approaches to the diagnosis and prevention of postoperative AF. The review was prepared using available materials from Russian and foreign library databases (PubMed, Medline, Web of Science and Cochrane Library). The search depth was >25 years since 1996. Based on the analysis of available studies, we concluded that inflammation is not just evidence of AF, but plays a causal role in its pathogenesis at each stage of surgical myocardial revascularization.

[The role of atherosclerotic coronary arteries lesions in development of new-onset atrial fibrillation after coronary artery bypass surgery]

Aim    To study the relationship between the type of circulation, severity and localization of atherosclerotic damage of coronary arteries, results of laboratory and instrumental tests, and historical data in patients with multivascular coronary lesions and atrial fibrillation (AF) that developed after coronary bypass surgery.Material and methods    This was a novel, retrospective study of data of patients after elective coronary bypass surgery at the Cardiac Surgery Department #1 of the N.V. Sklifosofsky Research Institute of Emergency Care from December, 2018 through December, 2020. The study included 100 patients. The main group consisted of 20 patients whose early postoperative period (first 7 days after surgery) was complicated with postoperative atrial fibrillation (POAF) (mean age, 65.15±9.7 years). The comparison group included 80 patients without the POAF complication during the early postoperative period (mean age, 62.0±9.16 years). Prior to the coronary bypass surgery, all patients underwent clinical, laboratory, and instrumental examination. Based on data of selective coronary angiography, localization, severity of coronary atherosclerotic damage (according to angiographic classification), number of affected arteries, and the type of circulation were taken into account.Results    Intergroup differences in the incidence and localization of myocardial infarctions in history, severity of arterial hypertension in history, class of chronic heart failure (according to the New York Heart Association, NYHA, classification), and heart rate were absent. 100 % of patients had left atrial (LA) dilatation not correlated with the development of AF in the early postoperative period. According to data of coronary angiography, there was no statistically significant association between the type of circulation and the development of POAF. The right type of myocardial blood supply prevailed in patients of both groups. There was no correlation between the severity and localization of coronary atherosclerotic lesions and the development of AF in the early postoperative period.Conclusion    The development of AF following coronary bypass surgery was not associated with features of coronary atherosclerotic lesions, which may indicate active development of inter- and intra-systemic anastomoses in patients with long-term history of chronic coronary atherosclerosis.

N-terminal propeptide of type III procollagen for predicting diastolic dysfunction in patients with myocardial infarction and preserved ejection fraction

Aim. To study changes in the level of fibrotic scarring marker — the N-terminal propeptide type III procollagen (PIIINP) and structural and functional parameters with the assessment of diastolic function in patients a year after ST segment elevation myocardial infarction (STEMI) and preserved left ventricle (LV) contractility.

Material and methods. At first, the study included 120 (100%) STEMI patients. Next, patients with an LV ejection fraction (EF) ≥50% were selected. The final analysis included 86 STEMI patients. Upon hospitalization, the patients underwent routine diagnostic tests, coronary angiography with stenting of culprit artery. Echocardiography and determination of venous blood PIIINP and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels was on the 1st (time point 1) and 12th day (time point 2) of disease and after a year (time point 3). To compare the obtained values of fibrotic scarring markers, a control group was formed, including 20 (100%) healthy volunteers, identical in age and sex with the studied sample.

Results. On the first day of MI, 25 (29,1%) patients with signs of diastolic dysfunction (DD) were identified among those with preserved LVEF. After 1 year, the number of such patients increased by 10% (n=9). Initially increased (relative to the control group) concentration of PIIINP on the first day (311,2 [220,1; 376,3] ng/ml) decreased by the 12th day (223,3 [195,3; 312,1] ng/ml) and returned to the initial values a year after the MI (312,6 [228,0; 383,8] ng/ml). The NT-proBNP concentration during the hospitalization period did not exceed the reference values and did not differ between 1 and 2 time points (p=0,127). One year later, the NT-proBNP concentration significantly exceeded the values of the previous determinations and amounted to 124,4 pg/ml (p=0,043). According to the ROC analysis, with a PIIINP ≥387,8 ng/ml on the first day, the risk of DD increases (p=0,050, sensitivity, 84,62%, specificity, 55,56%) within a year after STEMI with preserved LVEF.

Conclusion. The threshold of PIIINP (≥387,8 ng/ml) was established for the first day of MI, at which the risk of DD increases one year after the index event. An increase in NT-proBNP concentration one year after STEMI indicates the progression of heart failure.

 

[Dynamics of Parameters of Transmitral Blood Flow and Markers of Myocardial Fibrosis in Patients with Myocardial Infarction]

Aim      To study possible correlations between echocardiography (EchoCG) indexes and markers of myocardial fibrosis, procollagen I C-terminal propeptide (PICP) and procollagen III N-terminal propeptide (PIIINP) during one year following ST-segment elevation myocardial infarction (STEMI).Material and methods  120 patients with STEMI were evaluated. EchoCG was used to assess dimensions and volumes of heart chambers, left ventricular (LV) systolic function, mean pulmonary arterial pressure (mPAP), and indexes of LV diastolic function (Em, early diastolic lateral mitral annular velocity; e', peak early diastolic septal mitral annular velocity; E / e', ratio of peak early diastolic transmitral inflow velocity and mitral annular velocity  -, Е / А, ratio of peak early and late transmitral inflow velocities; DT, deceleration time of LV early diastolic filling). EchoCG indexes and serum concentrations of PICP and PIIINP were determined at 1 (point 1) and 12 (point 2) days of disease and one year after STEMI (point 3). The sample was divided into two groups: group 1 (n=86; 71.7 %) included patients with a LV ejection fraction (EF) ≥50 % and group 2 (n=34; 28.3 %) consisted of patients with LV EF ≤49 %.Results At one year, the number of patients with signs of diastolic dysfunction increased by 10% in group 1 whereas myocardial systolic dysfunction worsened in both groups. LV EF decreased in 15 (17.4%) patients of group 1 and in 4 (11.8%) patients of group 2. Concentrations of PIIINP were correlated with Em, E / e', mPAP, PICP, e', and LV EF.Conclusion      Direct correlations between PIIINP concentrations and Em, E / e', and mPAP were found in the group with LV EF ≥50 %. In the group with LV EF <50 %, correlations were observed between PICP concentrations, LV EF, and e'. Also, in this group, the increase in PIIINP was statistically more significant. These results indicate continuing formation of myocardial fibrosis in a year following MI, which may underlie progression of chronic heart failure.

ST2 PLASMA LEVEL IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION WITHOUT ST ELEVATION AND DIFFERENT CLINICAL CHARACTERISTICS

The aim. Estimation of ST2 plasma level in patients with acute myocardial infarction without ST elevation (NSTEMI) and its relationship with different clinical characteristics. Materials and methods. 165 patients aged from 35 to 79 (average of 60.7±0.8 years) with various forms of coronary artery disease (CAD) with and without arterial hypertension were examined. The variability of plasma ST2 level in different forms of CAD and in NSTEMI group was analyzed depending on gender-age and clinical characteristics and features of the disease course. Results: The results of the present investigation were that the ST2 level in the main cohort was in range from 5.5 to 233.9 (in the middle – 49.8±3.5 ng / ml (median indicator – 34.7 and the interquartile range – 21.9 and 59.1 respectively). Significantly higher ST2 levels were found in patients with NSTEMI, unlike the comparison group, in the median analysis (35.9 vs. 27.7 ng/ml, p=0.047) and no statistical differences were observed in the mean values. In patients with NSTEMI, a certain association of ST2 level in plasma with the MI course was detected. A higher level of neurohormone is registered with anterior unlike posterior ECG localization of MI; at high unlike moderate risk on the GRACE scale; when complicated unlike the uncomplicated course of MI; in the case of acute HF and cardiac arrhythmias unlike patients with the absence of these manifestations in the acute period of MI. Conclusions. High variability of ST2 level in plasma was demonstrated in patients with NSTEMI on the first day after destabilization (minimum and maximum values – 12.7 and 233.9 respectively, median – 35.9 and interquartile range – 25.9 and 55.7 ng / ml). It is shown that significantly higher ST2 level in plasma is determined in patients with acute MI regardless of its variant among different clinical forms of CAD. It is found that significantly higher level of ST2 in patients with NSTEMI is recorded in the case of concomitant HTN and type 2 diabetes, with smoking and heavy cardiovascular heredity. Proved influence of the character of MI course on the level of ST2 in plasma, significantly higher level of neurohormone was determined with anterior localization of MI, high risk on the GRACE scale (≥ 140 points), complicated course of MI, development of cardiac arrhythmias and HF in the acute period of MI.