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.

DNMT1 deregulation of SOCS3 axis drives cardiac fibroblast activation in diabetic cardiac fibrosis.

Cardiac fibrosis is one of the main pathological manifestations of diabetic cardiomyopathy (DCM). Cardiac fibroblast activation is a key effector of cells resulting in diabetic cardiac fibrosis. However, the underlying mechanism of cardiac fibroblast activation and diabetic cardiac fibrosis remains unclear. Accumulating evidence suggests that DNA methylation alterations play a central role in cardiac fibroblast activation. In this study, we demonstrated that DNA methyltransferase 1 (DNMT1)-mediated suppression of cytokine signaling 3 (SOCS3) promoter hypermethylation leads to downregulation of SOCS3 expression in diabetic cardiac fibrosis. High glucose-induced expression of DNMT1 was increased in cardiac fibroblasts, while the expression of SOCS3 was decreased. Downregulation of SOCS3 facilitated activation of STAT3 to promote cardiac fibroblast activation and collagen deposition. Genetic or pharmacological inactivation of DNMT1 reversed the activated phenotype of cardiac fibroblasts. Clinically, we observed a significant inverse correlation between DNMT1 and SOCS3 expression levels, and loss of SOCS3 expression or increased expression of DNMT1. Taken together, these findings identify DNMT1 silencing of SOCS3 axis as a driver of cardiac fibroblast activation in diabetic cardiac fibrosis. These results provide a scientific and new explanation of the underlying mechanism of diabetic cardiac fibrosis.

DNA methyltransferase-1 inactivation of androgen receptor axis triggers homocysteine induced cardiac fibroblast autophagy in diabetic cardiac fibrosis.

Diabetic cardiac fibrosis is one of the main pathological manifestations of diabetic cardiomyopathy (DCM). Cardiac fibroblast autophagy plays critical roles in diabetic cardiac fibrosis, however, the underlying mechanism of cardiac fibroblast autophagy and diabetic cardiac fibrosis still largely unknown. The aim of the study was to investigate the mechanism of DNMT1 mediated DNA methylation alterations control cardiac fibroblast autophagy in diabetic cardiac fibrosis. We employed streptozotocin (STZ)-induced rats DCM, DCM patient and Hcy induced cardiac fibroblast autophagy. Heart tissue sections were stained with H&E, Sirius Red and Masson's trichrome stain. The expression of DNMT1, AR, Collagen genes mRNA was detected by qRT-PCR. MSP and BSP detected the methylation status of the AR promoter. The expression of DNMT1, AR, Collagen and autophagy-related proteins were detected by Western blotting, Immunofluorescence, Immunohistochemistry. Gain and loss function of AR and DNMT1 in cardiac fibroblast was analyzed. DNMT1 inhibition or knockdown elevated the expression of AR in cardiac fibroblast. Furthermore, we found that AR negatively regulation of Hcy induced cardiac fibroblast autophagy. We demonstrated that DNMT1 enhances cardiac fibroblast autophagy in diabetic cardiac fibrosis through inhibiting AR axis. In conclusion, our results provide new insight into the DNMT1 inactivation of AR axis triggers cardiac fibroblast autophagy in diabetic cardiac fibrosis.

MeCP2 inactivation of LncRNA GAS5 triggers cardiac fibroblasts activation in cardiac fibrosis.

Long non coding RNA growth arrest-specific transcript 5 (LncRNA GAS5) participate in the formation of fibrosis diseases. However, the key role of LncRNA GAS5 in the development of cardiac fibrosis remains unclear. Accumulating evidence suggests that DNA methylation alterations play a central role in cardiac fibroblast activation. In this study, we explored MeCP2 inactivation of LncRNA GAS5 leads to down regulation of LncRNA GAS5 expression in cardiac fibrosis. Gain and loss function of LncRNA GAS5 and MeCP2 was analyzed. The expression of LncRNA GAS5 was significantly decreased in cardiac fibrosis tissues, while MeCP2 was significantly increased. Moreover, the expression of MeCP2 was increased in TGF-ß1 induced cardiac fibroblasts, while the expression of LncRNA GAS5 was decreased. Down regulation of LncRNA GAS5 resulted in increasing cellular proliferation. In contrast, exogenous over expression of LncRNA GAS5 in cardiac fibroblasts inhibited cell proliferation. 5-AzadC or knockdown of MeCP2 treatment significantly restored LncRNA GAS5 expression in cardiac fibroblasts, while over expression of MeCP2 treatment significantly inhibited LncRNA GAS5 expression in cardiac fibroblasts. In summary, these results suggested that MeCP2 silencing of LncRNA GAS5 triggers cardiac fibroblasts activation in cardiac fibrosis.

DNMT1 Methylation of LncRNA GAS5 Leads to Cardiac Fibroblast Pyroptosis via Affecting NLRP3 Axis.

Cell death and inflammation play critical roles in cardiac fibrosis. During the fibrosis process, inflammation and tissue injury were triggered; however, the mechanisms initiating cardiac fibrosis and driving fibroblast pyroptosis remained largely unknown. In this study, we identified long non-coding RNA (LncRNA)-GAS5 as the key onset of cardiac fibroblast pyroptosis and cardiac fibrosis. Here, we detected ISO-induced cardiac fibrosis models and cardiac fibroblast pyroptosis model by stimulating with LPS. We found that the expression of pyroptosis-related proteins such as caspase 1, NLRP3, and DNMT1 was increased in cardiac fibrosis tissue, while the expression of GAS5 was decreased. The overexpressing of LncRNA GAS5 was shown to increase and inhibit cardiac fibroblast pyroptosis, as well as attenuate caspase 1 and NLRP3 expression in cardiac fibroblast. However, the silencing of GAS5 was also observed; it shows the opposite situation. Furthermore, further studies revealed that treatment of DNMT inhibitor, 5-aza-2-deoxycytidine, or downregulation of DNMT1 led to increased GAS5 expression by reversion of promoter hypermethylation in cardiac fibroblast. Importantly, we have demonstrated that DNMT1 methylation of LncRNA GAS5 leads to cardiac fibroblast pyroptosis via affecting NLRP3 axis. Our findings indicate a new regulatory mechanism for cardiac fibroblast pyroptosis under LPS stress, providing a novel therapeutic target for cardiac fibrosis. Graphical Abstract.

Extralobar pulmonary sequestration in a 55-year-old man.

Pulmonary sequestration is a rare congenital lung malformation that more commonly occurs in the left lung, mainly near the lower mediastinum. It is rarely observed in patients with extralobar sequestration in adulthood. We report the case of a 55-year-old man with recurrent fever and cough lasting for about 1 month, who was admitted to our hospital. His past history was unremarkable. The final diagnosis of extralobar sequestration was dependent on three-dimensional computed tomography angiography (3D CTA), which showed an abnormal blood supply vessel to the consolidation from the aortic arch. The patient underwent a left pulmonary sequestration resection, and the pathological examination also verified the diagnosis postoperatively. 3D CTA images can provide an aberrant vessel anatomy map for the surgeon and play a decisive role in the detection of pulmonary sequestration.

Evolution of tricuspid regurgitation after mitral valve surgery for patients with moderate-or-less functional tricuspid regurgitation.

OBJECTIVES: The purpose of this study was to evaluate the impact of moderate-or-less functional tricuspid regurgitation (TR) treatment on the clinical outcome of patients with mitral valve (MV) surgery. METHODS: From October 2001 to January 2005, 167 patients in our hospital with MV surgery and without organic tricuspid valve (TV) disease or pulmonary hypertension (PH) showed moderate-or-less functional TR preoperatively, and 41.9% of these patients were treated with TR (group T), compared with 58.1% untreated with TR (group no-T). According to tricuspid annulus dimension (TAD)/body surface area (BSA), these 167 patients were further divided into another 2 groups (A and B): group A (70 patients) represented TAD/BSA ≤ 21 mm/m2 with 32 patients from group T and 38 from group no-T, and group B (97 patients) represented TAD/BSA > 21 mm/m2 with 38 patients from group T and 59 patients from group no-T. There was no statistical difference in preoperative and operative variables between the 2 groups. Meanwhile, among the 167 patients with MV surgery, 157 patients were replaced with MV and 10 patients were repaired with MV, and De Vega technique was constantly used for TR treatment. All the results were estimated by multivariate analysis. RESULTS: The median follow-up time was 63 months (25th and 75th percentiles are 53 and 94 months, respectively); 30-day mortality was 3% (1.4% in group T versus 4.1% in group no-T; P = .31). Adjusted 5-year survival was 70.7% (66.6%-80.4%) with 85.3% (83.0%-93.4%) in group T and 64.7% (33.7%-58.3%) in group no-T, P = .001. Among the 70 patients with TAD/BSA ≤ 21 mm/m2, patients who received treatment of moderate-or-less TR and those who did not showed similar secondary TR grade at postoperative period (0.5 ± 0.6 in group T versus 0.9 ± 0.9 in group no-T; P = .2) and follow-up (1.3 ± 1.1 in group T versus 1.8 ± 1.1 in group no-T; P = .06). In subgroup B (TAD/BSA > 21 mm/m2), patients who received tricuspid valvoplasty manifested more significantly improved outcome than patients without functional TR at postoperative period (0.8 ± 0.8 in group T versus 1.6 ± 1.3 in group no-T; P = .03) and follow-up (2.0 ± 1.2 in group T versus 3.0 ± 1.1 in group no-T; P = .005). The multivariate analysis identified TAD/BSA > 21 mm/m2 and preoperative atrial fibrillation (AF) as the risk factors for lower survival at follow-up period. CONCLUSIONS: Patients with MV surgery have better midterm outcome when they receive either more aggressive and effective surgical treatment for functional TR or moderate-or-less TR preoperatively. Indexed TAD (TAD/BSA > 21 mm/m2) is a more reliable surgical guideline for the treatment of TR. Preoperative tricuspid annulus dilation and AF might be predictors of late lower survival.