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BACKGROUND: Myocardial infarction (MI) leads to enhanced activity of cardiac fibroblasts (CFs) and abnormal deposition of extracellular matrix proteins, resulting in cardiac fibrosis. Tartrate-resistant acid phosphatase 5 (ACP5) has been shown to promote cell proliferation and phenotypic transition. However, it remains unclear whether ACP5 is involved in the development of cardiac fibrosis after MI. The present study aimed to investigate the role of ACP5 in post-MI fibrosis and its potential underlying mechanisms. METHODS: Clinical blood samples were collected to detect ACP5 concentration. Myocardial fibrosis was induced by ligation of the left anterior descending coronary artery. The ACP5 inhibitor, AubipyOMe, was administered by intraperitoneal injection. Cardiac function and morphological changes were observed on Day 28 after injury. Cardiac CFs from neonatal mice were extracted to elucidate the underlying mechanism in vitro. The expression of ACP5 was silenced by small interfering RNA (siRNA) and overexpressed by adeno-associated viruses to evaluate its effect on CF activation. RESULTS: The expression of ACP5 was increased in patients with MI, mice with MI, and mice with Ang II-induced fibrosis in vitro. AubipyOMe inhibited cardiac fibrosis and improved cardiac function in mice after MI. ACP5 inhibition reduced cell proliferation, migration, and phenotypic changes in CFs in vitro, while adenovirus-mediated ACP5 overexpression had the opposite effect. Mechanistically, the classical profibrotic pathway of glycogen synthase kinase-3ß (GSK3ß)/ß-catenin was changed with ACP5 modulation, which indicated that ACP5 had a positive regulatory effect. Furthermore, the inhibitory effect of ACP5 deficiency on the GSK3ß/ß-catenin pathway was counteracted by an ERK activator, which indicated that ACP5 regulated GSK3ß activity through ERK-mediated phosphorylation, thereby affecting ß-catenin degradation. CONCLUSION: ACP5 may influence the proliferation, migration, and phenotypic transition of CFs, leading to the development of myocardial fibrosis after MI through modulating the ERK/GSK3ß/ß-catenin signaling pathway.

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After myocardial injury, cardiac fibroblasts (CFs) differentiate into myofibroblasts, which express and secrete extracellular matrix (ECM) components for myocardial repair, but also promote myocardial fibrosis. Recombinant fibroblast growth factor 2 (FGF2) protein drug with low molecular weight can promote cell survival and angiogenesis, and it was found that FGF2 could inhibit the activation of CFs, suggesting FGF2 has great potential in myocardial repair. However, the regulatory role of FGF2 on CFs has not been fully elucidated. Here, we found that recombinant FGF2 significantly suppressed the expression of alpha smooth muscle actin (α-SMA) in CFs. Through RNA sequencing, we analyzed mRNA expression in CFs and the differently expressed genes regulated by FGF2, including 430 up-regulated genes and 391 down-regulated genes. Gene ontology analysis revealed that the differentially expressed genes were strongly enriched in multiple biological functions, including ECM organization, cell adhesion, actin filament organization and axon guidance. The results of gene set enrichment analysis (GSEA) show that ECM organization and actin filament organization are down-regulated, while axon guidance is up-regulated. Further cellular experiments indicate that the regulatory functions of FGF2 are consistent with the findings of the gene enrichment analysis. This study provides valuable insights into the potential therapeutic role of FGF2 in treating cardiac fibrosis and establishes a foundation for further research to uncover the underlying mechanisms of CFs gene expression regulated by FGF2.

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AIM: To investigate the effect of liquorice extract on TGF-β1-induced myocardial fibroblast (CFs) fibrosis. METHODS: 10 ng/mL TGF-β1 induced CFs to establish myocardial fibrosis cell model. Fibrotic cells were treated with liquorice extract and the cell activity was detected by MTT assay. CCK-8 was used to detect the effect of liquorice extract on CFs proliferation. The expression of smooth muscle actin (α-SMA) was detected by immunofluorescence. Western blot was used to detect TGF-β1/Smad signaling pathway related proteins and p-Smad2, p-Smad3 expression levels. The mRNA expression levels of Smad2, Smad3 and Smad4 were detected by RT-PCR. RESULTS: Compared with the control group, there were statistically significant differences in cell activity (P<0.05). The cell proliferation rate of glycyrrhiza uralensis extract groups was significantly lower than that of TGF-β1 group (P<0.05). The expression levels of α-SMA and TGF-β1/Smad signaling pathway related proteins in 100 μg/mL liquorice extract were significantly lower than those in TGF-β1 group (P<0.05). CONCLUSION: Glycyrrhiza extract can improve the occurrence and development of TGF-β1-induced myocardial fibrosis, and its mechanism maybe related to the inhibition of TGF-β1/Smad signaling pathway.

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BACKGROUND: Myocardial fibrosis after myocardial infarction (MI) has been considered a core factor in the deterioration of cardiac function. Previous studies have shown that miRNA plays an important role in various pathophysiological processes of the heart. However, the role of miRNA in myocardial fibrosis regulation after MI remains unclear. In the present study, we documented that miR-218-5p was significantly decreased in myocardial fibroblasts after MI. METHODS: The miRNA expression profiles of MI were downloaded from GEO Datasets. The expression of a fibrosis-related gene in vivo and in vitro was analyzed by RT-PCR, western blotting, and immunohistochemical staining. RESULTS: Total 7 up- and 9 downregulated common miRNAs were found in the two profiles. Among these common genes, miR-218-5p was downregulated in the MI mice. MiR-218-5p mediated the myocardial fibrosis in vivo and in vitro. Mechanistically, we found that GJA1 (CX43) may be the target of miR218-5p, and overexpressed CX43 can partly block the function of miR-218-5p in fibrosis inhibition. CONCLUSION: Our results suggested that miR-218-5p plays an important role in myocardial fibrosis after MI by targeting CX43. Thus, miR-218-5p promises to be a potential diagnosis and treatment of myocardial fibrosis after MI.

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TRPC proteins form cation conducting channels regulated by different stimuli and are regulators of the cellular calcium homeostasis. TRPC are expressed in cardiac cells including cardiac fibroblasts (CFs) and have been implicated in the development of pathological cardiac remodeling including fibrosis. Using Ca2+ imaging and several compound TRPC knockout mouse lines we analyzed the involvement of TRPC proteins for the angiotensin II (AngII)-induced changes in Ca2+ homeostasis in CFs isolated from adult mice. Using qPCR we detected transcripts of all Trpc genes in CFs; Trpc1, Trpc3 and Trpc4 being the most abundant ones. We show that the AngII-induced Ca2+ entry but also Ca2+ release from intracellular stores are critically dependent on the density of CFs in culture and are inversely correlated with the expression of the myofibroblast marker α-smooth muscle actin. Our Ca2+ measurements depict that the AngII- and thrombin-induced Ca2+ transients, and the AngII-induced Ca2+ entry and Ca2+ release are not affected in CFs isolated from mice lacking all seven TRPC proteins (TRPC-hepta KO) compared to control cells. However, pre-incubation with GSK7975A (10 µM), which sufficiently inhibits CRAC channels in other cells, abolished AngII-induced Ca2+ entry. Consequently, we conclude the dispensability of the TRPC channels for the acute neurohumoral Ca2+ signaling evoked by AngII in isolated CFs and suggest the contribution of members of the Orai channel family as molecular constituents responsible for this pathophysiologically important Ca2+ entry pathway.

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Cardiac fibrosis plays a crucial role in the pathogenesis of myocardial infarction (MI). It has been found that differentiation of cardiac fibroblasts (CFs) into myofibroblasts is a major event in the process of cardiac fibrosis. In the present study, we aimed to investigate the effects of protocatechuic acid (PCA), a cardiac protective agent, on the CFs differentiation in vitro. The results showed that PCA exhibited inhibitory effects on the cell proliferation and migration in angiotensin II (Ang II)-induced CFs. PCA treatment suppressed the Ang II-induced expression of α-smooth muscle actin (α-SMA), which is a hallmark of myofibroblasts. In addition, the production of extracellular matrix (ECM) proteins, including type I collagen (Col I) and connective tissue growth factor (CTGF), were significantly decreased in the PCA-treated CFs. The Ang II-induced increased levels of matrix metalloproteinase (MMP)-2, and MMP-9 were reduced by PCA. Furthermore, PCA resulted in decrease in reactive oxygen species (ROS) generation, as well as the expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme 4 (NOX4) and p-p38 in Ang II-induced CFs. These findings showed that PCA treatment prevented the Ang II-induced cardiac fibrosis by inhibiting the NOX4/ROS/p38 signaling pathway in vitro, suggesting that PCA might be a therapeutic agent for MI.

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Cardiac fibrosis is a common pathological process presented in a variety of diseases, including hypertension and diabetes. Cardiac fibroblasts (CFs) have been identified as the most important participants in the development of cardiac fibrosis. Exposure of cultured CFs to high glucose (HG) or angiotensin II (Ang II) resulted in increased collagen synthesis. Resveratrol (Res) is a natural polyphenol exhibiting anti-fibrosis effects in a number of different organs fibrosis process, whether Res can prevent HG and Ang II induced fibrosis response in CFs remains unclear. The aim of this work was to evaluate the effects of Res in HG and Ang II induced fibrosis response in CFs. We cultured rat CFs in either normal glucose (5.6 mM) or HG (25 mM) media in the presence of Res or not and the changes in collagens synthesis and TGF-ß1 production were assessed by Real-time PCR, Western blotting, and enzyme linked immunosorbent assay (ELISA). Furthermore, normal and diabetic mice (induced by single dose of streptozotocin (100 mg/kg) via tail vein) receiving Res (10 mg/kg) were used to explore the effects of Res on cardiac fibrosis in vivo. Masson staining and immunohistochemistry were performed to visualize cardiac collagen deposition. Results indicate that CFs exposed to HG condition shows enhanced proliferation rate. Furthermore, in the presence of HG or Ang II, CFs exhibited increased collagens synthesis and TGF-ß1 production. And these effects were abolished by Res intervention. In vivo results show that diabetic mice exhibit increased collagen deposition in the cardiac compared with the normal mice. And this change was prevented by the treatment of Res. These results suggest that Res possesses a potential antifibrogenic effect in hypertension and diabetes-related cardiac fibrosis. Moreover, the action mechanism is probably associated with its ability to reduce TGF-ß1 content in CFs.

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