Regulation of left atrial fibrosis induced by mitral regurgitation by SIRT1

Left ventricular remodeling and its correlation with serum cardiac troponin I in patients with end-stage renal disease treated

OBJECTIVE

To investigate the effects of different blood purification modes on left ventricular remodeling and its relationship with serum cardiac troponin I (cTnI) in patients with end-stage renal disease (ESRD).

METHOD

A total of 108 patients with ESRD were selected, 55 cases were divided into hemodialysis combined with hemoperfusion (HD + HP) group, in which patients participants accepted routine hemodialysis for three times/week and hemoperfusion for three times/month; 53 cases in hemodialysis combined with hemodialysis filtration (HD + HDF) group, routine hemodialysis three times/week + hemodialysis filtration three times/month. The total duration of dialysis in the study was 1 year. Cardiac troponin I (cTnI) levels were measured before dialysis and 1 year after treatment, and related parameters were measured by echocardiography, including ventricular septal thickness (IVST), left ventricular posterior wall thickness (LVPWT), left ventricular end diastolic diameter (LVEDd), left ventricular end systolic diameter (LVEDs), and left ventricular myocardial mass index (LVMI). The paired t test was used within the group. Correlation analysis was performed using Spearman correlation analysis.

RESULT

After treatment, the levels of cTnI, IVST, LVPWT, LVEDd, LVEDs, and LVMI in the two groups were increased, and the results were statistically significant (all p < 0.05). In addition, cTnI of the two groups was significantly correlated with IVST, LVPWT, LVEDd, LVEDs, and LVMI (all p < 0.05).

CONCLUSION

Left ventricular remodeling is common in patients with ESRD, HD + Hp, and HD + HDF cannot reduce the phenomenon of left ventricular remodeling, cTnI can be used as a predictor of left ventricular hypertrophy and enlargement.

Multiomic study of the protective mechanism of Persicaria capitata (Buch.-Ham. ex D.Don) H.Gross against streptozotocin-induced diabetic nephropathy in Guizhou miniature pigs

BACKGROUND

Persicaria capitata (Buch.-Ham. ex D.Don) H.Gross (P. capitata, PCB), a traditional drug of the Miao people in China, is potential traditional drug used for the treatment of diabetic nephropathy (DN).

PURPOSE

The purpose of this study is to investigate the function of P. capitata and clarify its protective mechanism against DN.

METHODS

We induced DN in the Guizhou miniature pig with injections of streptozotocin, and P. capitata was added to the pigs' diet to treat DN. In week 16, all the animals were slaughtered, samples were collected, and the relative DN indices were measured. 16S rRNA sequencing, metagenomics, metabolomics, RNA sequencing, and proteomics were used to explore the protective mechanism of P. capitata against DN.

RESULTS

Dietary supplementation with P. capitata significantly reduced the extent of the disease, not only in term of the relative disease indices but also in hematoxylin-eosin-stained tissues. A multiomic analysis showed that two microbes (Clostridium baratii and Escherichia coli), five metabolites (oleic acid, linoleic acid, 4-phenylbutyric acid, 18-β-glycyrrhetinic acid, and ergosterol peroxide), four proteins (ENTPD5, EPHX1, ARVCF and TREH), four important mRNAs (encoding ENTPD5, EPHX1, ARVCF, and TREH), six lncRNAs (TCONS_00024194, TCONS_00085825, TCONS_00006937, TCONS_00070981, TCONS_00074099, and TCONS_00097913), and two circRNAs (novel_circ_0001514 and novel_circ_0017507) are all involved in the protective mechanism of P. capitata against DN.

CONCLUSIONS

Our results provide multidimensional theoretical support for the study and application of P. capitata.

Downregulation of SIRT1 and GADD45G genes and left atrial fibrosis induced by right ventricular dependent pacing in a complete atrioventricular block pig model

The molecular and genetic mechanisms underlying left atrial (LA) enlargement and atrial fibrosis following right ventricular (RV) dependent pacing remain unclear. Our objective was to investigate genetic expressions in the LA of pigs subjected to RV pacing for atrioventricular block (AVB), as well as to identify the differential gene expressions affected by biventricular (BiV) pacing. We established an AVB pig model and divided the subjects into three groups: a sham control group, an RV pacing group, and a BiV pacing group. Differential expression genes (DEGs) analyses conducted through next-generation sequencing (NGS) and enrichment analyses were employed to identify genes with altered expression in the LA myocardium. The RV pacing group showed a significant increase in extracellular fibrosis in the LA myocardium compared to the control group. NGS analysis revealed suppressed expression of the sirtuin signaling pathway in the RV pacing group. Among the DEGs within this pathway, GADD45G was found to be downregulated in the RV pacing group and upregulated in the BiV pacing group. Remarkably, the BiV pacing group exhibited elevated levels of GADD45G protein. In our study, we observed significant downregulation of SIRT1 and GADD45G genes, which are associated with the sirtuin signaling pathway, in the LA myocardium of the RV pacing group when compared to the control group. Moreover, these genes, which were downregulated in the RV pacing group, displayed a noteworthy upregulation in the BiV pacing group when compared to the RV pacing group.

The role and implications of left atrial fibrosis in surgical mitral valve repair as assessed by CMR: the ALIVE study design and rationale

Background

Patients with mitral regurgitation (MR) commonly suffer from left atrial (LA) remodeling. LA fibrosis is considered to be a key player in the LA remodeling process, as observed in atrial fibrillation (AF) patients. Literature on the presence and extent of LA fibrosis in MR patients however, is scarce and its clinical implications remain unknown. Therefore, the ALIVE trial was designed to investigate the presence of LA remodeling including LA fibrosis in MR patients prior to and after mitral valve repair (MVR) surgery.

Methods

The ALIVE trial is a single center, prospective pilot study investigating LA fibrosis in patients suffering from MR in the absence of AF (identifier NCT05345730). In total, 20 participants will undergo a CMR scan including 3D late gadolinium enhancement (LGE) imaging 2 week prior to MVR surgery and at 3 months follow-up. The primary objective of the ALIVE trial is to assess the extent and geometric distribution of LA fibrosis in MR patients and to determine effects of MVR surgery on reversed atrial remodelling.

Implications

This study will provide novel insights into the pathophysiological mechanism of fibrotic and volumetric atrial (reversed) remodeling in MR patients undergoing MVR surgery. Our results may contribute to improved clinical decision making and patient-specific treatment strategies in patients suffering from MR.

Cardiomyocyte-targeting exosomes from sulforaphane-treated fibroblasts affords cardioprotection in infarcted rats

BACKGROUND

Exosomes (EXOs), tiny extracellular vesicles that facilitate cell-cell communication, are being explored as a heart failure treatment, although the features of the cell source restrict their efficacy. Fibroblasts the most prevalent non-myocyte heart cells, release poor cardioprotective EXOs. A noninvasive method for manufacturing fibroblast-derived exosomes (F-EXOs) that target cardiomyocytes and slow cardiac remodeling is expected. As a cardioprotective isothiocyanate, sulforaphane (SFN)-induced F-EXOs (SFN-F-EXOs) should recapitulate its anti-remodeling properties.

METHODS

Exosomes from low-dose SFN (3 μM/7 days)-treated NIH/3T3 murine cells were examined for number, size, and protein composition. Fluorescence microscopy, RT-qPCR, and western blot assessed cell size, oxidative stress, AcH4 levels, hypertrophic gene expression, and caspase-3 activation in angiotensin II (AngII)-stressed HL-1 murine cardiomyocytes 12 h-treated with various EXOs. The uptake of fluorescently-labeled EXOs was also measured in cardiomyocytes. The cardiac function of infarcted male Wistar rats intramyocardially injected with different EXOs (1·10¹²) was examined by echocardiography. Left ventricular infarct size, hypertrophy, and capillary density were measured.

RESULTS

Sustained treatment of NIH/3T3 with non-toxic SFN concentration significantly enhances the release of CD81 + EXOs rich in TSG101 (Tumor susceptibility gene 101) and Hsp70 (Heat Shock Protein 70), and containing maspin, an endogenous histone deacetylase 1 inhibitor. SFN-F-EXOs counteract angiotensin II (AngII)-induced hypertrophy and apoptosis in murine HL-1 cardiomyocytes enhancing SERCA2a (sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a) levels more effectively than F-EXOs. In stressed cardiomyocytes, SFN-F-EXOs boost AcH4 levels by 30% (p < 0.05) and significantly reduce oxidative stress more than F-EXOs. Fluorescence microscopy showed that mouse cardiomyocytes take in SFN-F-EXOs ~ threefold more than F-EXOs. Compared to vehicle-injected infarcted hearts, SFN-F-EXOs reduce hypertrophy, scar size, and improve contractility.

CONCLUSIONS

Long-term low-dose SFN treatment of fibroblasts enhances the release of anti-remodeling cardiomyocyte-targeted F-EXOs, which effectively prevent the onset of HF. The proposed method opens a new avenue for large-scale production of cardioprotective exosomes for clinical application using allogeneic fibroblasts.

Pirfenidone for Idiopathic Pulmonary Fibrosis and Beyond

Pirfenidone (PFD) slows the progression of idiopathic pulmonary fibrosis (IPF) by inhibiting the exaggerated fibrotic response and possibly through additional mechanisms, such as anti-inflammatory effects. PFD has also been evaluated in other fibrosing lung diseases. Myocardial fibrosis is a common feature of several heart diseases and the progressive deposition of extracellular matrix due to a persistent injury to cardiomyocytes may trigger a vicious cycle that leads to persistent structural and functional alterations of the myocardium. No primarily antifibrotic medications are used to treat patients with heart failure. There is some evidence that PFD has antifibrotic actions in various animal models of cardiac disease and a phase II trial on patients with heart failure and preserved ejection fraction has yielded positive results. This review summarises the evidence about the possible mechanisms of IPF and modulation by PFD, the main results about IPF or non-IPF interstitial pneumonias and also data about PFD as a potential protective cardiac drug.

Cardiac Imaging for the Assessment of Left Atrial Mechanics Across Heart Failure Stages

The left atrium (LA) is emerging as a key element in the pathophysiology of several cardiac diseases due to having an active role in contrasting heart failure (HF) progression. Its morphological and functional remodeling occurs progressively according to pressure or volume overload generated by the underlying disease, and its ability of adaptation contributes to avoid pulmonary circulation congestion and to postpone HF symptoms. Moreover, early signs of LA dysfunction can anticipate and predict the clinical course of HF diseases before the symptom onset which, particularly, also applies to patients with increased risk of HF with still normal cardiac structure (stage A HF). The study of LA mechanics (chamber morphology and function) is moving from a research interest to a clinical application thanks to a great clinical, prognostic, and pathophysiological significance. This process is promoted by the technological progress of cardiac imaging which increases the availability of easy-to-use tools for clinicians and HF specialists. Two-dimensional (2D) speckle tracking echocardiography and feature tracking cardiac magnetic resonance are becoming essential for daily practice. In this context, a deep understanding of LA mechanics, its prognostic significance, and the available approaches are essential to improve clinical practice. The present review will focus on LA mechanics, discussing atrial physiology and pathophysiology of main cardiac diseases across the HF stages with specific attention to the prognostic significance. Imaging techniques for LA mechanics assessment will be discussed with an overlook on the dynamic (under stress) evaluation of the chamber.