Entanglement of GSK-3β, β-catenin and TGF-β1 signaling network to regulate myocardial fibrosis

Bromfenac Inhibits TGF-β1-Induced Fibrotic Effects in Human Pterygium and Conjunctival Fibroblasts

Purpose

Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown antifibrotic effects on several diseases. The aims of the present in vitro study were to investigate the antifibrotic effects of bromfenac (a kind of NSAID) on primary human pterygium fibroblasts (HPFs) and primary human conjunctival fibroblasts (HConFs), as well as to explore the possible mechanisms of these effects.

Methods

The cells used in this study were primary HPFs and HConFs, and profibrotic activation was induced by transforming growth factor-beta1 (TGF-β1). Western blot, quantitative real-time PCR, and immunofluorescence (IF) assays were used to detect the effects of TGF-β1 and bromfenac on the synthesis of fibronectin (FN), type III collagen (COL3), and alpha-smooth muscle actin (α-SMA) in HPFs and HConFs; the changes of signaling pathways were detected by Western blot; cell migration ability was detected by wound healing assay; cell proliferation ability was detected by CCK-8 assay; and pharmaceutical inhibitions of the downstream signaling pathways of TGF-β1 were used to assess their possible associations with the effects of bromfenac.

Results

Bromfenac suppressed the TGF-β1-induced protein expression of FN (0.59 ± 0.07 folds, P = 0.008), COL3 (0.48 ± 0.08 folds, P = 0.001), and α-SMA (0.61 ± 0.03 folds, P = 0.008) in HPFs. Bromfenac also attenuated TGF-β1-induced cell migration (0.30 ± 0.07 folds, P < 0.001), cell proliferation (0.64 ± 0.03 folds, P = 0.002) and the expression levels of p-AKT (0.66 ± 0.08 folds, P = 0.032), p-ERK1/2 (0.69 ± 0.11 folds, P = 0.003), and p-GSK-3β-S9 (0.65 ± 0.10 folds, P = 0.002) in HPFs. PI3K/AKT inhibitor (wortmannin) and MEK/ERK inhibitor (U0126) reduced the TGF-β1-induced synthesis of FN, COL3, and α-SMA in HPFs. All the results were similar in HConFs.

Conclusions

Bromfenac protects against TGF-β1-induced synthesis of FN, α-SMA, and COL3 in HPFs and HConFs at least in part by inactivating the AKT and ERK pathways.

Modulation of miR-10a-mediated TGF-β1/Smads signaling affects atrial fibrillation-induced cardiac fibrosis and cardiac fibroblast proliferation

Atrial fibrillation (AF) rat models and rat cardiac fibroblasts (CFs) with overexpressed or inhibited miR-10a were used to investigate the possible role of miR-10a-mediated transforming growth factor-β (TGF-β1)/Smads signaling in cardiac fibrosis and fibroblast proliferation in rats with AF. Gene ontology and pathway enrichment analyses were used to identify the possible function of miR-10a in cardiac fibrosis. The results showed that overexpressed miR-10a significantly prolonged the duration of AF, further elevated the collagen volume fraction (CVF), and increased the viability of CFs in AF rats; these findings were in contrast with the findings for rats with inhibition of miR-10a (all P<0.05). Moreover, miR-10a overexpression could promote miR-10a, collagen-I, collagen III, α-SMA, and TGF-β1 protein expression and increase the levels of hydroxyproline but reduced Smad7 protein expression in atrial tissues and CFs in AF rats. Not surprisingly, inhibiting miR-10a led to completely contrasting results (all P<0.05). Moreover, TGF-β1 treatment could reverse the inhibitory effect of miR-10a down-regulation on cardiac fibrosis in CFs. Bioinformatics analysis and luciferase reporter assay results demonstrated that miR-10a bound directly to the 3′-UTR of BCL6, which is involved in cell growth and proliferation. Thus, our study indicate that down-regulation of miR-10a may inhibit collagen formation, reduce atrial structure remodeling, and decrease proliferation of CFs, eventually suppressing cardiac fibrosis in AF rats via inhibition of the TGF-β1/Smads signaling pathway.

Silymarin ameliorates diabetic cardiomyopathy via inhibiting TGF-β1/Smad signaling

Diabetic cardiomyopathy (DCM) is the leading cause of morbidity and mortality in diabetes mellitus (DM) patients. Previous studies have shown that the transforming growth factor-beta 1 (TGF-β1)/Smad signaling pathway plays a key role in the development of myocardial fibrosis in DCM. Silymarin (SMN) is used clinically to treat liver disorders and acts by influencing TGF-β1. However, the possible effects of silymarin on DCM remain to be elucidated. In our study, the DM animal model was induced by streptozotocin (STZ) injection. Fasting blood glucose level was measured, and the structure and function of the heart were measured by hematoxylin and eosin (H&E) and Masson staining, echocardiography, and transmission electron microscopy (TEM). Western blot was used to detect the expression of TGF-β1, Smad2/3, phosphorylation Smad2/3(p-Smad2/3), and Smad7. Our results showed that silymarin downregulated blood glucose level and significantly improved cardiac fibrosis and collagen deposition in DM rats detected by H&E, Masson staining, and TEM assays. The echocardiography results showed that silymarin administration attenuated cardiac dysfunction in DM rats. Additionally, compared with untreated DM rats, levels of TGF-β1 and p-Smad2/3 were decreased, whereas Smad7 was increased following silymarin administration. These data demonstrate that silymarin ameliorates DCM through the inhibition of TGF-β1/Smad signaling, suggesting that silymarin may be a potential target for DCM treatment.

Cardiomyocyte SMAD4-Dependent TGF-β Signaling is Essential to Maintain Adult Heart Homeostasis

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SMAD4 is the central intracellular mediator of TGF-β pathway.

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CM-specific loss of SMAD4 causes cardiac dysfunction independent of fibrotic remodeling.

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Deletion CM-SMAD4 affects CM survival.

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CM-SMAD4 loss leads to down-regulation of several ion channels’ genes, resulting in cardiac conduction abnormalities.

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CM-SMAD4 deletion alters sarcomere shortening kinetics, in parallel with reduction in cardiac myosin-binding protein C levels.

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These results demonstrate a fundamental role for CM-SMAD4–dependent TGF-β signaling in adult heart homeostasis.

The role of the transforming growth factor (TGF)-β pathway in myocardial fibrosis is well recognized. However, the precise role of this signaling axis in cardiomyocyte (CM) biology is not defined. In TGF-β signaling, SMAD4 acts as the central intracellular mediator. To investigate the role of TGF-β signaling in CM biology, the authors deleted SMAD4 in adult mouse CMs. We demonstrate that CM-SMAD4–dependent TGF-β signaling is critical for maintaining cardiac function, sarcomere kinetics, ion-channel gene expression, and cardiomyocyte survival. Thus, our findings raise a significant concern regarding the therapeutic approaches that rely on systemic inhibition of the TGF-β pathway for the management of myocardial fibrosis.

Expression of ADAMTS-1 mRNA in myocardium of viral heart disease mice and its clinical significance

The expression of ADAMTS-1 mRNA in myocardium of viral heart disease (VHD) mice was investigated to explore its role in myocardial fibrosis. A total of 150 purebred inbred Balb/c mice were used in this study. According to the principle of similar body weight, 50 mice were selected to make an acute viral myocarditis (VMC) animal model (acute VMC group), and 50 mice were selected to make a chronic VMC animal model (chronic VMC group), and the remaining 50 mice were selected as a control group. RT-qPCR was used to detect the relative expression of transforming growth factor-β1 (TGF-β1) mRNA and ADAMTS-1 mRNA in myocardial tissue of three groups of mice, and their relationship in myocardial fibrosis was analyzed. Compared with the control group, the collagen volume fraction (CVF) in the myocardial tissue of the acute VMC group was significantly increased, and the increase of CVF in the myocardial tissue of the chronic VMC group was the most significant (p<0.001). Compared with the control group, the relative expression of TGF-β1 mRNA and ADAMTS-1 mRNA in myocardial tissue of the mice in the acute and chronic VMC group were significantly increased (p<0.001). The relative expression of TGF-β1 mRNA and ADAMTS-1 mRNA in myocardial tissue of chronic VMC group was significantly higher than that of acute VMC group (p<0.001). Pearson's correlation test results showed that ADAMTS-1 mRNA was positively correlated with CVF and TGF-β1 mRNA, and the correlation coefficients were (r=0.351, p<0.01, r=0.401, p<0.01). ADAMTS-1 is involved in the occurrence and development of myocardial fibrosis, and it is positively correlated with CVF and TGF-β1. It may play a role in promoting myocardial fibrosis during the development of VHD. It can be used as a biological index for predicting myocardial fibrosis.

Signaling Mechanisms of Myofibroblastic Activation: Outside-in and Inside-Out

Myofibroblasts are central mediators of fibrosis. Typically derived from resident fibroblasts, myofibroblasts represent a heterogeneous population of cells that are principally defined by acquired contractile function and high synthetic ability to produce extracellular matrix (ECM). Current literature sheds new light on the critical role of ECM signaling coupled with mechanotransduction in driving myofibroblastic activation. In particular, transforming growth factor β1 (TGF-β1) and extra domain A containing fibronectin (EDA-FN) are thought to be the primary ECM signaling mediators that form and also induce positive feedback loops. The outside-in and inside-out signaling circuits are transmitted and integrated by TGF-β receptors and integrins at the cell membrane, ultimately perpetuating the abundance and activities of TGF-β1 and EDA-FN in the ECM. In this review, we highlight these conceptual advances in understanding myofibroblastic activation, in hope of revealing its therapeutic anti-fibrotic implications.

Heart Disease and Relaxin: New Actions for an Old Hormone

The hormone relaxin has long been recognized for its involvement in maternal adaptation during pregnancy. However, discoveries during the past two decades on the mechanism of action of relaxin, its family of receptors, and newly described roles in attenuating ischemia/reperfusion (I/R) injury, inflammation, and arrhythmias have prompted vast interest in exploring its therapeutic potential in cardiovascular disease. These observations inspired recently concluded clinical trials in patients with acute heart failure. This review discusses our current understanding of the protective signaling pathways elicited by relaxin in the heart, and highlights important new breakthroughs about relaxin signaling that may pave the way to more carefully designed future trials.

[Tumor necrosis factor-α and transforming growth factor-β1 balance liver stem cell differentiation in cholestatic cirrhosis]

OBJECTIVE

To investigate the changes of tumor necrosis factor-α (TNF-α) and transforming growth factor-β₁ (TGF-β₁) in mice with cholestatic cirrhosis and their role in regulating the balance of liver stem cell differentiation.

METHODS

Balb/c mice were subjected to bile duct ligation (BDL), and serum biochemical parameters were measured and hepatic histopathology was observed using HE staining to evaluate the modeling of cholestatic cirrhosis. Immunohistochemistry and Western blotting were used to detect the changes of TNF-α and TGF-β₁ in the mice after modeling. Mouse embryonic hepatic stem cells (HP14-19) were treated with different concentrations of TNF-α and TGF-β₁, and the cell differentiation was assessed using Western blotting, real-time PCR, and PAS staining.

RESULTS

The mice receiving BDL showed significantly increased blood biochemical parameters (P<0.05), and HE staining revealed obviously increased collagen fibers in the liver with significantly increased expressions of TNF-α and TGF-β₁ (P<0.05). In HP14-19 cells, induction with TNF-α and TGF-β₁ for 3 days did not cause significant changes in cell differentiation, but induction for 5 days resulted in significantly increases intensity of PAS staining in the cells. The cells induced with 20, 40, and 80 ng/mL TNF-α for 5 days exhibited a significantly stronger expression of cytokeratin 18 than cytokeratin 19 (P<0.05), while induction with 20, 40, and 80 ng/mL TGF-β₁ produced opposite changes in cytokeratin 18 and cytokeratin 19 expressions. Further induction of the cells with TNF-α and TGF-β₁ for 10 days, did not alter the expression patterns of cytokeratin 18 and cytokeratin 19 observed on day 5, but their protein expression levels and PAS staining intensity of the cells were enhanced and their mRNA expressions became lowered.

CONCLUSION

Common bile duct ligation can induce conditions simulating cholestatic cirrhosis in mice. TNF-α and TGF-β₁ are elevated in cholestatic cirrhosis and play opposite roles in regulating the differentiation balance of liver stem cells: the former promotes the differentiation of liver stem cells into hepatocytes, while the latter promotes the cell differentiation into colangiocytes.

Cardiomyocyte-specific deletion of GSK-3β leads to cardiac dysfunction in a diet induced obesity model

BACKGROUND AND RATIONALE

Obesity, an independent risk factor for the development of myocardial diseases is a growing healthcare problem worldwide. It's well established that GSK-3β is critical to cardiac pathophysiology. However, the role cardiomyocyte (CM) GSK-3β in diet-induced cardiac dysfunction is unknown.

METHODS

CM-specific GSK-3β knockout (CM-GSK-3β-KO) and littermate controls (WT) mice were fed either a control diet (CD) or high-fat diet (HFD) for 55weeks. Cardiac function was assessed by transthoracic echocardiography.

RESULTS

At baseline, body weights and cardiac function were comparable between the WT and CM-GSK-3β-KOs. However, HFD-fed CM-GSK-3β-KO mice developed severe cardiac dysfunction. Consistently, both heart weight/tibia length and lung weight/tibia length were significantly elevated in the HFD-fed CM-GSK-3β-KO mice. The impaired cardiac function and adverse ventricular remodeling in the CM-GSK-3β-KOs were independent of body weight or the lean/fat mass composition as HFD-fed CM-GSK-3β-KO and controls demonstrated comparable body weight and body masses. At the molecular level, on a CD, CM-GSK-3α compensated for the loss of CM-GSK-3β, as evident by significantly reduced GSK-3αs21 phosphorylation (activation) resulting in a preserved canonical β-catenin ubiquitination pathway and cardiac function. However, this protective compensatory mechanism is lost with HFD, leading to excessive accumulation of β-catenin in HFD-fed CM-GSK-3β-KO hearts, resulting in adverse ventricular remodeling and cardiac dysfunction.

CONCLUSION

In summary, these results suggest that cardiac GSK-3β is crucial to protect against obesity-induced adverse ventricular remodeling and cardiac dysfunction.

The Optimal Intervention Time of Bone Marrow Mesenchymal Stem Cells in Ameliorating Cardiac Fibrosis Induced by Viral Myocarditis: A Randomized Controlled Trial in Mice

Bone marrow-derived mesenchymal stem cells (BMSCs) have recently been introduced to treat cardiovascular diseases, such as myocardial infarction and dilated cardiomyopathy. Nevertheless, there are few researches focused on the application of BMSCs in treating viral myocarditis, not to mention its optimal intervention timer potential mechanisms. In our study, we concentrated on finding an optimal time window to perform BMSCs treatment in a murine model of myocarditis induced by coxsackievirus B3 (CVB3). On the 1st day, 3rd day, 7th day, and 14th day after BALB/c mice were infected by CVB3, we intravenously injected equivalent BMSCs into the treatment groups. With a 28-day follow-up after inoculation, we found that the ventricular function was significantly improved in the BMSCs treatment group and cardiac fibrosis markedly ameliorated, especially when BMSCs were injected between 1 and 2 weeks after CVB3 inoculation. Furthermore, we demonstrated that after BMSCs treatment, the expressions of TGF-β, col1α1, and col3α1 were significantly decreased. Therefore, we conclude that BMSCs may have a potential to improve CVB3-induced myocarditis by ameliorating cardiac fibrosis through the inhibition of TGF-β expression.