The landscape of histone modification in organ fibrosis.

An increase in fibrous connective tissue and a decrease in parenchymal cells in organ tissues are the primary pathological alterations linked to organ fibrosis. If fibrosis is not treated, organ structure is destroyed, function can decline, or even fail, posing a serious risk to human life and health. Numerous organs develop fibrosis, and organ fibroproliferative illnesses account for almost 45% of patient deaths from various diseases in the industrialized world, as well as a major cause of disability and mortality in many other diseases. Recently, it has become evident that histone modification is an important way to regulate gene expression in organ fibrosis. Histone modifications alter the structure of chromatin, thereby affecting gene accessibility. Histone acetylation modifications relax chromatin, making it easier for gene transcription factors to access DNA, thereby promoting gene transcription. In addition, histone modifications recruit other proteins to interact with chromatin to form complexes that further regulate gene expression. Histone methylation modifications recruit methylation-reading proteins that recognize methylation marks and alter gene expression status. It not only affects the normal physiological function of cells, but also plays an important role in organ fibrosis. This article reviews the important role played by histone modifications in organ fibrosis and potential therapeutic approaches.

Epigenetic signatures in cardiac fibrosis: Focusing on noncoding RNA regulators as the gatekeepers of cardiac fibroblast identity.

Cardiac fibroblasts play a pivotal role in cardiac fibrosis by transformation of fibroblasts into myofibroblasts, which synthesis and secrete a large number of extracellular matrix proteins. Ultimately, this will lead to cardiac wall stiffness and impaired cardiac performance. The epigenetic regulation and fate reprogramming of cardiac fibroblasts has been advanced considerably in recent decades. Non coding RNAs (microRNAs, lncRNAs, circRNAs) regulate the functions and behaviors of cardiac fibroblasts, including proliferation, migration, phenotypic transformation, inflammation, pyroptosis, apoptosis, autophagy, which can provide the basis for novel targeted therapeutic treatments that abrogate activation and inflammation of cardiac fibroblasts, induce different death pathways in cardiac fibroblasts, or make it sensitive to established pathogenic cells targeted cytotoxic agents and biotherapy. This review summarizes our current knowledge in this field of ncRNAs function in epigenetic regulation and fate determination of cardiac fibroblasts as well as the details of signaling pathways contribute to cardiac fibrosis. Moreover, we will comment on the emerging landscape of lncRNAs and circRNAs function in regulating signal transduction pathways, gene translation processes and post-translational regulation of gene expression in cardiac fibroblast. In the end, the prospect of cardiac fibroblasts targeted therapy for cardiac fibrosis based on ncRNAs is discussed.

New aspects of the epigenetic regulation of EMT related to pulmonary fibrosis.

Pulmonary fibrosis is a chronic and progressive fibrotic disease that results in impaired gas exchange, ventilation, and eventual death. The pro-fibrotic environment is instigated by various factors, leading to the transformation of epithelial cells into myofibroblasts and/or fibroblasts that trigger fibrosis. Epithelial mesenchymal transition (EMT) is a biological process that plays a critical role in the pathogenesis of pulmonary fibrosis. Epigenetic regulation of tissue-stromal crosstalk involving DNA methylation, histone modifications, non-coding RNA, and chromatin remodeling plays a key role in the control of EMT. The review investigates the epigenetic regulation of EMT and its significance in pulmonary fibrosis.

Glycolytic reprogramming in organ fibrosis: New dynamics of the epigenetic landscape.

Accumulating evidence has shown that aerobic glycolysis is essential for the establishment and maintenance of the fibrotic phenotype, so treatments targeting glycolytic reprogramming may become an important strategy to reduce fibrosis. Here, we reviewed current evidence on the glycolytic reprogramming in organ fibrosis, new dynamics of the epigenetic landscape. Epigenetic regulation of the expression of specific genes involved mediates glycolytic reprogramming, thereby affecting fibrosis progression. A comprehensive understanding of the interplay between aerobic glycolysis and epigenetics holds great promise for the treatment and intervention of fibrotic diseases. This article aims to comprehensively review the effect of aerobic glycolysis on organ fibrosis, and to elucidate the relevant epigenetic mechanisms of glycolytic reprogramming in different organs.

METTL3 boosts mitochondrial fission and induces cardiac fibrosis by enhancing LncRNA GAS5 methylation.

Dysregulated mitochondrial metabolism occurs in several pathological processes characterized by cell proliferation and migration. Nonetheless, the role of mitochondrial fission is not well appreciated in cardiac fibrosis, which is accompanied by enhanced fibroblast proliferation and migration. We investigated the causes and consequences of mitochondrial fission in cardiac fibrosis using cultured cells, animal models, and clinical samples. Increased METTL3 expression caused excessive mitochondrial fission, resulting in the proliferation and migration of cardiac fibroblasts that lead to cardiac fibrosis. Knockdown of METTL3 suppressed mitochondrial fission, inhibiting fibroblast proliferation and migration for ameliorating cardiac fibrosis. Elevated METTL3 and N6-methyladenosine (m6A) levels were associated with low expression of long non-coding RNA GAS5. Mechanistically, METTL3-mediated m6A methylation of GAS5 induced its degradation, dependent of YTHDF2. GAS5 could interact with mitochondrial fission marker Drp1 directly; overexpression of GAS5 suppressed Drp1-mediated mitochondrial fission, inhibiting cardiac fibroblast proliferation and migration. Knockdown of GAS5 produced the opposite effect. Clinically, increased METTL3 and YTHDF2 levels corresponded with decreased GAS5 expression, increased m6A mRNA content and mitochondrial fission, and increased cardiac fibrosis in human heart tissue with atrial fibrillation. We describe a novel mechanism wherein METTL3 boosts mitochondrial fission, cardiac fibroblast proliferation, and fibroblast migration: METTL3 catalyzes m6A methylation of GAS5 methylation in a YTHDF2-dependent manner. Our findings provide insight into the development of preventative measures for cardiac fibrosis.

Mitochondrial quality control in cardiac fibrosis: Epigenetic mechanisms and therapeutic strategies.

Cardiac fibrosis (CF) is considered an ultimate common pathway of a wide variety of heart diseases in response to diverse pathological and pathophysiological stimuli. Mitochondria are characterized as isolated organelles with a double-membrane structure, and they primarily contribute to and maintain highly dynamic energy and metabolic networks whose distribution and structure exert potent support for cellular properties and performance. Because the myocardium is a highly oxidative tissue with high energy demands to continuously pump blood, mitochondria are the most abundant organelles within mature cardiomyocytes, accounting for up to one-third of the total cell volume, and play an essential role in maintaining optimal performance of the heart. Mitochondrial quality control (MQC), including mitochondrial fusion, fission, mitophagy, mitochondrial biogenesis, and mitochondrial metabolism and biosynthesis, is crucial machinery that modulates cardiac cells and heart function by maintaining and regulating the morphological structure, function and lifespan of mitochondria. Certain investigations have focused on mitochondrial dynamics, including manipulating and maintaining the dynamic balance of energy demand and nutrient supply, and the resultant findings suggest that changes in mitochondrial morphology and function may contribute to bioenergetic adaptation during cardiac fibrosis and pathological remodeling. In this review, we discuss the function of epigenetic regulation and molecular mechanisms of MQC in the pathogenesis of CF and provide evidence for targeting MQC for CF. Finally, we discuss how these findings can be applied to improve the treatment and prevention of CF.

Epigenetic reader MeCP2 repressed WIF1 boosts lung fibroblast proliferation, migration and pulmonary fibrosis.

Epigenetic has been implicated in pulmonary fibrosis. However, there is limited information regarding the biological role of the epigenetic reader MeCP2 in pulmonary fibrosis. The aim of this study was to investigate the role of MeCP2 and its target WIF1 in pulmonary fibrosis. The pathological changes and collagen depositions was analyzed by H&E, Masson's Trichrome Staining and Sirius Red staining. MeCP2, WIF1, α-SMA, Wnt1, ß-catenin, and collagen I expression were analyzed by western blotting, RT-qPCR, immunohistochemistry, immunofluorescence, respectively. The effects of MeCP2 on pulmonary fibrosis involve epigenetic mechanisms, using cultured cells, animal models, and clinical samples. Herein, our results indicated that MeCP2 level was up-regulated, while WIF1 was decreased in Bleomycin (BLM)-induced mice pulmonary fibrosis tissues, patients pulmonary fibrosis tissues and TGF-ß1-induced lung fibroblast. Knockdown of MeCP2 by siRNA can rescue WIF1 downregulation in TGF-ß1-induced lung fibroblast, inhibited lung fibroblast activation. The DNA methylation inhibitor 5-azadC-treated lung fibroblasts have increased WIF1 expression with reduced MeCP2 association. In addition, we found that reduced expression of WIF1 caused by TGF-ß1 is associated with the promoter methylation status of WIF1. Moreover, in vivo studies revealed that knockdown of MeCP2 mice exhibited significantly ameliorated pulmonary fibrosis, decreased interstitial collagen deposition, and increased WIF1 expression. Taken together, our study showed that epigenetic reader MeCP2 repressed WIF1 facilitates lung fibroblast proliferation, migration and pulmonary fibrosis.

Epigenetic control of LncRNA NEAT1 enables cardiac fibroblast pyroptosis and cardiac fibrosis.

Cardiac fibroblasts (CFs) drive extracellular matrix remodeling after inflammatory injury, leading to cardiac fibrosis and diastolic dysfunction. Recent studies described the role of epigenetics in cardiac fibrosis. Nevertheless, detailed reports on epigenetics regulating CFs pyroptosis and describing their implication in cardiac fibrosis are still unclear. Here, we found that DNMT3A reduces the expression of lncRNA Neat1 and promotes the NLRP3 axis leading to CFs pyroptosis, using cultured cells, animal models, and clinical samples to shed light on the underlying mechanism. We report that pyroptosis-related genes are increased explicitly in cardiac fibrosis tissue and LPS-treated CFs, while lncRNA Neat1 decreased. Mechanistically, we show that loss of DNMT3A or overexpression of lncRNA Neat1 in CFs after LPS treatment significantly enhances CFs pyroptosis and the production of pyroptosis-related markers in vitro. It has been demonstrated that DNMT3A can decrease lncRNA Neat1, promoting NLRP3 axis activation in CFs treated with LPS. In sum, this study is the first to identify that DNMT3A methylation decreases the expression of lncRNA Neat1 and promotes CFs pyroptosis and cardiac fibrosis, suggesting that DNMT3A and NEAT1 may function as an anti-fibrotic therapy target in cardiac fibrosis.

METTL3 boosts glycolysis and cardiac fibroblast proliferation by increasing AR methylation.

Dysregulated glycolysis has been noted in several pathological processes characterized by supporting cell proliferation. Nonetheless, the role of glycolysis reprogramming is not well appreciated in cardiac fibrosis which is accompanied by increased fibroblasts proliferation. In this study, we investigated the cause and consequence of glycolysis reprogramming in cardiac fibrosis, using clinical samples, animal models, and cultured cells. Herein, we report that methyltransferase-like 3 (METTL3) facilitates glycolysis and cardiac fibroblasts proliferation, leading to cardiac fibrosis. The augmentation of glycolysis, an essential event during cardiac fibroblasts proliferation, is dependent on an increased expression of METTL3. A knockdown of METTL3 suppressed glycolysis, and inhibited cardiac fibroblast proliferation and cardiac fibrosis. Mechanistically, METTL3 epigenetically repressed androgen receptor (AR) expression in an m6A-YTHDF2- dependent manner, by targeting the specific AR m6A site. AR could interact with the glycolysis marker HIF-1α, and down-regulation of AR activates HIF-1α signaling, resulting in enhanced glycolysis and cardiac fibroblast proliferation. In contrast, the overexpression of AR significantly reduced the HIF-1α axis, decreased expression of glycolytic enzymes HK3, inhibited glycolysis, and repressed cardiac fibroblasts proliferation. Notably, increased METTL3 and YTHDF2 levels, decreased AR expression, increased HIF-1α and Postn expression and augmented glycolysis, and increased cardiac fibrosis were detected in human atrial fibrillation heart tissues. Our results found a novel mechanism by which METTL3-catalyzed m6A modification in cardiac fibrosis, wherein it facilitated glycolysis and cardiac fibroblasts proliferation by increasing AR methylation in an m6A-YTHDF2- dependent manner and provided new insights strategies to intervene cardiac fibrosis.

MTHFR epigenetic derepression protects against diabetes cardiac fibrosis.

BACKGROUND: Diabetes cardiac fibrosis is associated with altered DNA methylation of fibrogenic genes; however, the underlying mechanisms remain unclear. OBJECTIVES: In this study, we investigate the critical role of DNA methylation aberration-associated suppression of MTHFR in diabetes cardiac fibrosis, and the protective effects of folate on diabetes cardiac fibrosis, using cultured cells, animal models, and clinical samples. METHODS AND RESULTS: Herein, we report that DNA methylation repression of MTHFR, critically involved in diabetes cardiac fibrosis, mediates the significant protective effects of folate in a mouse model of diabetes cardiac fibrosis induced by STZ. Heart MTHFR expression was markedly suppressed in diabetes cardiac fibrosis patients and mice, accompanied by increased DNMT3A and MTHFR promoter methylation. Knockdown of DNMT3A demethylated MTHFR promoter, recovered the MTHFR loss, and alleviated the diabetes cardiac fibrosis pathology and cardiac fibroblasts pyroptosis. Mechanistically, DNMT3A epigenetically repressed MTHFR expression via methylation of the promoter. Interestingly, folate supplementation can rescue the effect of MTHFR loss in diabetes cardiac fibrosis, suggesting that inactivation of MTHFR through epigenetics is a critical mediator of diabetes cardiac fibrosis. CONCLUSIONS: The current study identifies that MTHFR repression due to aberrant DNMT3A elevation and subsequent MTHFR promoter hypermethylation is likely an important epigenetic feature of diabetes cardiac fibrosis, and folate supplementation protects against diabetes cardiac fibrosis.

Anomalous Systemic Arterial Supply to the Lung: To Which Category Should This Belong?

BACKGROUND: The nomenclature of both intralobar pulmonary sequestration (ILS) and aortic origin of a pulmonary artery (AOPA) remains controversial. According to this review, both ILS and AOPA have an anomalous systemic arterial supply to all or part of the lung with venous drainage into the pulmonary veins, which leads to pulmonary hypertension, congestive heart failure, and fatal pulmonary haemorrhage. The purpose of this review was to consider whether these two rare congenital anomalies have similar anatomical, clinical and pathological characteristics. METHODS: This review was conducted by researching relevant literature using PubMed and MEDLINE databases to January 2019. All researched literature was related to the anatomical, associated anomalies, pathophysiology and clinical features of the extralobar pulmonary sequestration (ELS), ILS, and AOPA, and the therapeutic method for ILS and AOPA. RESULTS: Through research literature, it was found that ILS and AOPA may differ in terms of embryonic origin, but some of the anatomical, histopathological, physiological and clinical features of these two congenital malformations are similar. However, ELS and ILS have significant differences in their anatomical, histopathological, physiological, and clinical features. CONCLUSIONS: This study proposes that ILS and AOPA could be classified as one single condition - systemic arterialisation of the lung - and further divided into three subtypes, namely: types I, II and III. This new classification nomenclature permits the appropriate change of novel surgical techniques, which obviate the need for lobectomy or segmentectomy in specific cases, thereby minimising fatal postoperative complications.

Anomalous Systemic Arterial Supply to the Left Lung: To Which Category Should This Belong?

An anomalous systemic arterial supply to the normal lung parenchyma with normal bronchial connections is a rare malformation. We report a case of a systemic arterial supply to the normal basal segment of the left lower lobe. The patient underwent resection of the left lower lobe. Here, we propose a revised nomenclature for a systemic arterial supply to the normal lung with normal bronchial connections.

Repair of Hemitruncus With Irreversible Pulmonary Hypertension.

Anomalous origin of the pulmonary artery from the ascending aorta can lead to congestive heart failure in infancy, and with advancing age many patients will experience severe pulmonary hypertension. Surgical intervention has high mortality and morbidity risks if this happens. Strategies to manage these patients seem only limited to heart-lung transplantation or lung transplantation. Here, we successfully performed surgical intervention in an adult patient who had anomalous origin of the right pulmonary artery from the ascending aorta with high pressures in the ascending aorta and normally originating pulmonary artery.

Surgical repair of an aortico-left ventricular tunnel with acute infective endocarditis.

Aortic-left ventricular tunnel is a rare congenital cardiac anomaly, which always arises from the right coronary sinus and enters the left ventricle, occasionally the right ventricle and right atrium. However, aortic and left ventricular tunnel associated with infective endocarditis is rarely seen in literatures. Here, we present a case of aortic and left ventricular tunnel associated with infective endocarditis in a 47-year-old man.

Pulmonary lobectomy on delayed inhaled foreign body in adult: a case report.

We present the case of a 51 years old female who experienced foreign body aspiration 3 years before. The foreign body, which should be removed by bronchoscopy before, was lodged at the bifurcation of the right inferior bronchus and could only be removed via right lower lobectomy. The patient experienced a swift recovery and was well at follow-up 8 months later.

Early and midterm results of repair of Ebstein's anomaly with autologous pericardium.

BACKGROUND: The surgical management of Ebstein's anomaly represents a major challenge. METHODS: Thirty consecutive patients with Ebstein's anomaly received surgical treatment in the period from April 2002 to October 2009. Operations included annuloplasty, repair of the tricuspid valve using autologous pericardium and tricuspid valve replacement. In most cases, repair of the tricuspid valve was done using autologous pericardium instead of an annuloplasty with the anterior leaflet alone. Associated congenital malformations were also repaired during the operation. Follow-up ranged from 6 to 82 months. RESULTS: Intraoperative transesophageal echocardiography revealed no or only minimal tricuspid incompetence after cardiopulmonary bypass in 25 patients. Mild or moderate incompetence was observed in 3 and 2 patients, respectively. At the last follow-up echocardiography, 5 patients with mild and 2 patients with moderate tricuspid incompetence were detected. There was no sign of pericardial degeneration, tricuspid valve stenosis, or calcification of the pericardial patch in any patient during follow-up. CONCLUSIONS: Although further study is required to assess the long-term function of the reconstructed tricuspid valve, our early and midterm results from this current study indicate that repairing the tricuspid valve with autologous pericardium achieves reasonable outcomes in the majority of patients with Ebstein's anomaly, including pediatric and adult patients.

In-vitro seeding of human umbilical cord vein endothelial cells on hydroxyapatite for mechanical heart valve applications.

BACKGROUND AND AIM OF THE STUDY: Although heart valve replacement with either a mechanical or biological prosthesis is an effective method to treat valvular heart disease, both approaches have limitations, including thrombus formation, thromboembolism and degeneration problems. The study aim was to demonstrate the in-vitro endothelialization of hydroxyapatite (HAp) to be used as a biomaterial in heart valve prostheses. METHODS: The HAp samples were characterized using X-ray diffractometry to identify the crystalline phase, while the surface morphology of HAp discs was examined using scanning electron microscopy (SEM). Human umbilical vein endothelial cells (HUVECs) were cultured on HAp discs for 1, 3, 5, and 7 days, and on pyrolytic carbon discs for 7 days; cytotoxicity was assessed using the methyl thiazolyl tetrazolium (MTT) assay. The cells were incubated in three groups: (i) an experimental group (cultured with HAp extract); (ii) a negative control (cultured with high-density polyethylene chaff); and (iii) a positive control (culture medium containing 0.1% phenol solution). RESULTS: A morphological examination of the HAp discs revealed the presence of micropores on the disc surface, together with cultured HUVECs. After seven days of culture, the HUVECs began to form a confluent endothelial cell layer covering the HAp discs. There were no visible cells attached to the pyrolytic carbon surface. The MTT assay indicated that HAp did not exert any cytotoxic effect on HUVECs, and low optical density values were obtained in the positive controls. CONCLUSION: The study results showed that HUVECs were able to grow well on HAp discs, and that HAP possessed a good in-vitro bioactivity and biocompatibility towards these cells. Consequently, HAp might be used as a film on mechanical heart valve prostheses, and serve as a promising biomaterial for heart valve replacement.

Cytotoxicity evaluation of hydroxyapatite on human umbilical cord vein endothelial cells for mechanical heart valve prosthesis applications.

BACKGROUND: Valvular heart disease is a significant cause of morbidity and mortality worldwide. Artificial heart valves are currently the most widely accepted biomedical material. However, the material's blood compatibility is still not sufficient. Biomaterial with a good biocompatibility has not yet appeared. Our initial study was to evaluate the probable cytotoxicity of hydroxyapatite (HA) on human umbilical vein endothelial cells (HUVEC) for mechanical heart valve prosthesis applications. METHODS AND RESULTS: Cell growth was tested by MTT assay and the cell relative growth rate (RGR) was calculated. Cells were cultured in media consisting of either leaching extracts of hydroxyapatite at 37 degrees C or leaching extracts at 121 degrees C or a negative and a positive control group, respectively. The cytotoxicity was graded using generally accepted standards. The RGR of cell lines cultured in the culture media consisting of either normal or heat temperature leaching extracts of hydroxyapatite and the negative controls were higher than in the positive controls. For 24 h, 48 h, and 72 h cultures, the cytotoxicity grade of HA was 0 in the normal temperature leaching extracts of hydroxyapatite and 1 in the heat temperature leaching extracts of hydroxyapatite. CONCLUSIONS: Human umbilical cord endothelial cells grew well in the HA extracts. Our results indicate that HA possesses good IN VITRO bioactivity and biocompatibility with human umbilical cord endothelial cells and could be used as film on mechanical heart valve prostheses.

Outcome of heart transplantations done in our centre.

BACKGROUND: We have found no study conducted economic issues on patient outcomes after heart transplantation (HTx) in China for further development. MATERIAL/METHODS: From May 2004 to February 2006, there were 10 transplants performed in 9 male patients in our center: 1 heart lung recipient and 8 heart recipient. Among them, 7 lacked health insurance and 2 had insurance. RESULTS: Their ages were between 24 years and 43 years (mean 39 years). The number of hospitalizations, number of days in hospital per admission, number of emergency room visits and mean left ventricular ejection fraction (LVEF) in the year before operation were 5.5, 54, 8.1 and 0.19 respectively. After operation, these figures decreased significantly to 1.7 (P<0.05), 18 (P<0.05), 1.1 (P<0.05) and 0.70 (P<0.05) respectively. During the follow up of 370~930d, one of the 9 patients who lacked health insurance died of acute rejection due to stopping mycophenolate mofetil (MMF) 7 months after operation and the heart lung recipient who also lacked health insurance died of pulmonary infection 1 year later. All patients who lacked health insurance experience emotional distress. CONCLUSIONS: HTx is a good treatment for selected patients with end-stage heart failure (ESHF) and future research is to be expected in the fields of insurance coverage to improve the quality of life and the Chinese transplant group should be commended for their courageous work in the treatment of end stage heart disease under challenging circumstances.