scholarly journals Mice overexpressing latent TGF-β1 are protected against renal fibrosis in obstructive kidney disease

2008 ◽  
Vol 295 (1) ◽  
pp. F118-F127 ◽  
Author(s):  
Xiao R. Huang ◽  
Arthur C. K. Chung ◽  
Xiao J. Wang ◽  
Kar Neng Lai ◽  
Hui Y. Lan
Keyword(s):  
Kidney Disease ◽  
Signaling Pathway ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Critical Factor ◽  
Collagen I ◽  
Collagen Iii ◽  
Renal Histology ◽  
Tgf Β1

Transforming growth factor (TGF)-β1, once activated, binds to its receptors and mediates renal fibrosis via the downstream Smad signaling pathway. We reported here that mice overexpressing latent TGF-β1 in keratinocytes were protected against renal fibrosis in a model of obstructive kidney disease. In normal mice, both transgenic (Tg) and wild-type (WT) mice had normal renal histology and function, despite a 10-fold increase in plasma latent TGF-β1 in Tg mice. A severe renal fibrosis was developed in WT mice at 7 days after urinary obstruction. Unexpectedly, renal fibrosis was prevented in Tg mice, although levels of latent TGF-β1 in both circulation and renal tissues remained high. Compared with the WT mice, quantitative real-time PCR showed that upregulation of renal α-smooth muscle actin (SMA), collagen I, and collagen III mRNA was inhibited in Tg mice (60–70% reduced, all P < 0.01). These were further confirmed by immunohistochemistry with a marked inhibition of tubulointerstitial accumulation of α-SMA+ fibroblasts, collagen I, and collagen III matrix in Tg mice (all P < 0.001). Further studies showed that inhibition of renal fibrosis in Tg mice was associated with a significant reduction in renal TGF-β1 and CTGF (60% reduced, P < 0.05), an increase in renal Smad7, a suppression of TSP-1 (a critical factor for TGF-β1 activation), and an inhibition of Smad2/3 activation (all P < 0.001). In conclusion, latent TGF-β may play a protective role in renal fibrosis. Inhibition of renal TGF-β1 expression and activation, thereby blocking the downstream TGF-β signaling pathway, may be a critical mechanism by which latent TGF-β1 protects against renal fibrosis.

Calycosin Inhibits Intestinal Fibrosis on CCD-18Co Cells via Modulating Transforming Growth Factor-β/Smad Signaling Pathway

Pharmacology ◽  
2019 ◽  
Vol 104 (1-2) ◽  
pp. 81-89 ◽  
Author(s):  
Jing Liu ◽  
Tan Deng ◽  
Yaxin Wang ◽  
Mengmeng Zhang ◽  
Guannan Zhu ◽  
...  
Keyword(s):  
Growth Factor ◽  
Signaling Pathway ◽  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Collagen I ◽  
Smad Pathway ◽  
Smad Signaling ◽  
Intestinal Fibrosis ◽  
Smad Signaling Pathway ◽  
Tgf Β1

Background: Intestinal fibrosis is the major complication of Crohn’s disease (CD). There are no other good treatments for CD except surgery and remains a refractory disease. Calycosin (CA), the active component of astragalus membranaceus, has been reported the potential effect on lung fibrosis and renal fibrosis. In this study, we aim to explore the effect of CA on intestinal fibrosis in vitro and the possible signal pathway. Methods: The antifibrotic effect of CA is investigated in human intestinal fibroblasts (CCD-18Co) cells induced by transforming growth factor-β1 (TGF-β1). MTT method was used to screen the concentration of CA. Real-time polymerase chain reaction and western blot analysis were used to evaluate the expression of α-smooth muscle actin (α-SMA), collagen I, and TGF-β/Smad pathway. Results: The results showed that the concentration of CA was 12.5, 25, 50 μmol/L. CA could inhibit the expression of α-SMA and collagen I. In addition, CA regulated the expression of TGF-β/Smad signaling pathway. Conclusion: This study demonstrated that CA could inhibit the activation of CCD-18Co cells and reduce the expression of extracellular matrix. Our study highlighted that CA-inhibited TGF-β/Smad pathway through inhibiting the expression of p-Smad2, p-Smad3, Smad4, and TGF-β1 and raised the Smad7 expression. Therefore, CA might inhibit intestinal fibrosis by inhibiting the TGF-β/Smad pathway.

scholarly journals Ameliorative Effects of Osthole on Experimental Renal Fibrosis in vivo and in vitro by Inhibiting IL-11/ERK1/2 Signaling

2021 ◽  
Vol 12 ◽  
Author(s):  
Fan Wu ◽  
Yan Zhao ◽  
Qingqing Shao ◽  
Ke Fang ◽  
Ruolan Dong ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Renal Fibrosis ◽  
Cell Model ◽  
Smooth Muscle Actin ◽  
Collagen I ◽  
Mrna Levels ◽  
Smad Signaling ◽  
Tgf Β1

Objectives: Natural product, osthole, has been proven to have a protective effect on organ fibrosis, including renal fibrosis. All of these studies are mainly focused on the regulation of TGF-β/Smad signaling pathway. However, due to the pleiotropic roles of TGF-β/Smad signaling, direct TGF-β-targeted treatments are unlikely to be therapeutically feasible in clinic. Recently, the downstream IL-11/ERK1/2 signaling of TGF-β has become an attractive therapeutic target without upstream disadvantages. Based on that, this study was designed to identify the potential effects of osthole on IL-11/ERK1/2 signaling pathway in renal fibrosis.Methods: The renal fibrosis model was established in vivo and in vitro, we investigated the effects of osthole on unilateral ureteral obstruction (UUO)-induced renal fibrosis and TGF-β-induced HK-2 cells. After preliminarily confirming the antifibrogenic effects of osthole and the link between its antifibrogenic effects and the inhibition of IL-11/ERK1/2 signaling, we applied a direct IL-11-induced HK-2 cells fibrosis model to further explore the inhibitory effects of osthole on IL-11/ERK1/2 signaling pathway.Results: Our results confirmed that osthole can decrease the secretion of fibrosis proteins, such as α-smooth muscle actin (α-SMA), collagen I, and fibronectin, ameliorate experimental renal fibrosis in vivo and in vitro, and the effect was associated with suppressing TGF-β1/Smad signaling. More importantly, we found that IL-11/ERK1/2 signaling in UUO-induced renal fibrosis and TGF-β-induced HK-2 cell model was obviously upregulated, and osthole treatment also significantly inhibited the abnormal IL-11/ERK1/2 signaling activation. Given the direct link between TGF-β/Smad signaling and IL-11/ERK1/2 signaling pathway, we have verified that osthole has a direct inhibitory effect on IL-11/ERK1/2 signaling independent of TGF-β signaling by using an IL-11-induced HK-2 cells fibrosis model. Osthole treatment decreased the protein expression of α-SMA, collagen I and fibronectin without changing their mRNA levels in IL-11-induced HK-2 cells. Moreover, it was observed that the IL-11/ERK1/2 inhibitor, U0126, partly blocked the antifibrogenic effects of osthole.Conclusion: In this study, we found that osthole has a previously unrecognized role in inhibiting IL-11/ERK1/2 signaling pathway. Our work demonstrated that the antifibrogenic effect of osthole is not only mediated by TGF-β/Smad2/3 signaling, but also directly mediated by IL-11/ERK1/2 signaling pathway independent of TGF-β1 signaling.

scholarly journals Transplantation of Telocytes Attenuates Unilateral Ureter Obstruction-Induced Renal Fibrosis in Rats

2018 ◽  
Vol 46 (5) ◽  
pp. 2056-2071 ◽  
Author(s):  
Long Zheng ◽  
Long Li ◽  
Guisheng Qi ◽  
Mushuang Hu ◽  
Chao Hu ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protective Effect ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Kidney Tissue ◽  
Collagen I ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mrna Levels ◽  
Mesenchymal Transition ◽  
Tgf Β1

Background/Aims: Previous studies imply that telocytes may have a protective effect on fibrosis in various organs, including the liver, colon, and heart. The effect of telocytes on renal fibrosis remains unknown. Herein, this study was designed to investigate the effect of telocytes on renal fibrosis and the potential mechanisms involved. Methods: In a unilateral ureteral obstruction (UUO)-induced renal fibrosis model, telocytes were injected via the tail vein every other day for 10 days. The degree of renal damage and fibrosis was determined using histological assessment. The expression of collagen I, fibronectin, epithelial-mesenchymal transition markers, and Smad2/3 phosphorylation was examined by western blot analyses. Real-time PCR and enzyme-linked immunosorbent assay were performed in vivo to detect the levels of transforming growth factor (TGF)-β1 and various growth factors. Results: Telocytes attenuated renal fibrosis, as evidenced by reduced interstitial collagen accumulation, decreased expression of fibronectin and collagen I, upregulation of E-cadherin, and downregulation of α-smooth muscle actin. Furthermore, telocytes decreased serum TGF-β1 levels, suppressed Smad2/3 phosphorylation, and increased the expression of hepatocyte growth factor (HGF) in rat kidney tissue following UUO. Blockage of HGF counteracted the protective effect of telocytes on UUO-treated kidneys. Through the detection of HGF mRNA levels in vitro, we found that telocytes had no effect on HGF expression compared with renal fibroblasts. Conclusion: Telocytes attenuated UUO-induced renal fibrosis in rats, likely through enhancing the expression of HGF in an indirect manner.

scholarly journals Macrophage-specific deletion of transforming growth factor-β1 does not prevent renal fibrosis after severe ischemia-reperfusion or obstructive injury

2013 ◽  
Vol 305 (4) ◽  
pp. F477-F484 ◽  
Author(s):  
Sarah C. Huen ◽  
Gilbert W. Moeckel ◽  
Lloyd G. Cantley
Keyword(s):  
Growth Factor ◽  
Kidney Disease ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Interstitial Fibrosis ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Transforming Growth Factor Β1 ◽  
Late Time ◽  
Tgf Β1

Macrophage infiltration is a prominent feature of the innate immune response to kidney injury. The persistence of macrophages is associated with tubulointerstitial fibrosis and progression of chronic kidney disease. Macrophages are known to be major producers of transforming growth factor-β1 (TGF-β1), especially in the setting of phagocytosis of apoptotic cells. TGF-β1 has long been implicated as a central mediator of tissue scarring and fibrosis in many organ disease models, including kidney disease. In this study, we show that homozygous deletion of Tgfb1 in myeloid lineage cells in mice heterozygous for Tgfb1 significantly reduces kidney Tgfb1 mRNA expression and Smad activation at late time points after renal ischemia-reperfusion injury. However, this reduction in kidney Tgfb1 expression and signaling results in only a modest reduction of isolated fibrosis markers and does not lead to decreased interstitial fibrosis in either ischemic or obstructive injury models. Thus, targeting macrophage-derived TGF-β1 does not appear to be an effective therapy for attenuating progressive renal fibrosis after kidney injury.

scholarly journals Deficiency of mPGES-1 exacerbates renal fibrosis and inflammation in mice with unilateral ureteral obstruction

2017 ◽  
Vol 312 (1) ◽  
pp. F121-F133 ◽  
Author(s):  
Renfei Luo ◽  
Yutaka Kakizoe ◽  
Feifei Wang ◽  
Xiang Fan ◽  
Shan Hu ◽  
...  
Keyword(s):  
Protein Expression ◽  
Ureteral Obstruction ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Collecting Duct ◽  
Unilateral Ureteral Obstruction ◽  
Prostaglandin E ◽  
Expression Levels ◽  
Collagen Iii ◽  
Tgf Β1

Microsomal prostaglandin E2 synthase-1 (mPGES-1), an inducible enzyme that converts prostaglandin H2 to prostaglandin E2 (PGE2), plays an important role in a variety of inflammatory diseases. We investigated the contribution of mPGES-1 to renal fibrosis and inflammation in unilateral ureteral obstruction (UUO) for 7 days using wild-type (WT) and mPGES-1 knockout (KO) mice. UUO induced increased mRNA and protein expression of mPGES-1 and cyclooxygenase-2 in WT mice. UUO was associated with increased renal PGE2 content and upregulated PGE2 receptor (EP) 4 expression in obstructed kidneys of both WT and mPGES-1 KO mice; EP4 expression levels were higher in KO mice with UUO than those in WT mice. Protein expression of NLRP3 inflammasome components ASC and interleukin-1β was significantly increased in obstructed kidneys of KO mice compared with that in WT mice. mRNA expression levels of fibronectin, collagen III, and transforming growth factor-β1 (TGF-β1) were significantly higher in obstructed kidneys of KO mice than that in WT mice. In KO mice, protein expression of fibronectin and collagen III was markedly increased in obstructed kidneys compared with WT mice, which was associated with increased phosphorylation of protein kinase B (AKT). EP4 agonist CAY10598 attenuated increased expression of collagen I and fibronectin induced by TGF-β1 in inner medullary collecting duct 3 cells. Moreover, CAY10598 prevented the activation of NLRP3 inflammasomes induced by angiotensin II in human proximal tubule cells (HK2). In conclusion, these findings suggested that mPGES-1 exerts a potentially protective effect against renal fibrosis and inflammation induced by UUO in mice.

scholarly journals Dihydromyricetin Reverses Thioacetamide-Induced Liver Fibrosis Through Inhibiting NF-κB-Mediated Inflammation and TGF-β1-Regulated of PI3K/Akt Signaling Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Yingchun Zhao ◽  
Xinglong Liu ◽  
Chuanbo Ding ◽  
Yan Gu ◽  
Wencong Liu
Keyword(s):  
Liver Fibrosis ◽  
Signaling Pathway ◽  
Cell Activation ◽  
Transforming Growth Factor ◽  
Histopathological Examination ◽  
Stellate Cell ◽  
Smooth Muscle Actin ◽  
Immunofluorescence Staining ◽  
Inflammatory Factors ◽  
Tgf Β1

As a natural active substance, dihydromyricetin (DHM) has been proven to have good hepatoprotective activity. However, the therapeutic effect of DHM on liver fibrosis, which has become a liver disease threatening the health of people around the world, has not been studied to date. The purpose of this study was to investigate the effect of DHM as a new nutritional supplement on thioacetamide (TAA)-induced liver fibrosis. The liver fibrosis model was established by intraperitoneal injection of TAA (200 mg/kg, every 3 days) for 8 weeks, and oral administration of DHM (20 mg/kg and 40 mg/kg, daily) after 4 weeks of TAA-induced liver fibrosis. The results showed that DHM treatment significantly inhibited the activities of alanine aminotransferase (ALT) (37.81 ± 7.62 U/L) and aspartate aminotransferase (AST) (55.18 ± 10.94 U/L) in serum of liver fibrosis mice, and increased the levels of superoxide dismutase (SOD) and glutathione (GSH) while reversed the level of malondialdehyde (MDA). In addition, histopathological examination illustrated that TAA induced the inflammatory infiltration, apoptosis and fibroatherosclerotic deposition in liver, which was further confirmed by western-blot and immunofluorescence staining. Moreover, DHM inhibited hepatocyte apoptosis by regulating the phosphorylation level of phosphatidylinositol 3-kinase (PI3K), protein kinase-B (AKT) and its downstream apoptotic protein family. Interestingly, immunofluorescence staining showed that DHM treatment significantly inhibited alpha smooth muscle actin (α-SMA), which was a marker of hepatic stellate cell activation, and regulated the expression of transforming growth factor (TGF-β1). Importantly, supplementation with DHM significantly inhibited the release of nuclear factor kappa-B (NF-κB) signaling pathway and pro-inflammatory factors in liver tissue induced by TAA, and improved liver fiber diseases, such as tumor necrosis factor alpha (TNF-α) and recombinant rat IL-1β (IL-1β). In conclusion, the evidence of this study revealed that DHM is a potential hepatoprotective and health factor, and which also provides the possibility for the treatment of liver fibrosis.

scholarly journals Poricoic acid A as a modulator of TPH-1 expression inhibits renal fibrosis via modulating protein stability of β-catenin and β-catenin-mediated transcription

2020 ◽  
Vol 11 ◽  
pp. 204062232096264
Author(s):  
Dan-Qian Chen ◽  
Xia-Qing Wu ◽  
Lin Chen ◽  
He-He Hu ◽  
Yan-Ni Wang ◽  
...  
Keyword(s):  
Protein Stability ◽  
Signaling Pathway ◽  
Renal Fibrosis ◽  
Cell Injury ◽  
Tryptophan Hydroxylase ◽  
Transforming Growth Factor ◽  
Lentiviral Vector ◽  
Luciferase Reporter ◽  
Key Enzyme ◽  
Tgf Β1

Background: Renal fibrosis is the common feature of chronic kidney disease (CKD). However, few drugs specifically target fibrogenesis due to the lack of an effective therapeutic target. Hence, it is urgent to find a therapeutic strategy that inhibits renal fibrosis. Here, we identified that poricoic acid A (PAA) as the modulator of tryptophan hydroxylase-1 (TPH-1), the key enzyme in tryptophan metabolism, exerted potent anti-fibrotic effects in the kidney. Methods: Lentiviral vector, luciferase reporter activity assay and co-immunoprecipitation were used. The animal model of unilateral ureteral obstruction and adenine-induced chronic renal failure as well as transforming growth factor (TGF)-β1-treated epithelial cells NRK-52E and fibroblasts NRK-49F were used. Results: TPH-1 was gradually decreased during CKD progression, while PAA treatment significantly increased TPH-1 expression to suppress renal fibrosis. Pharmacological overexpression of TPH-1 by PAA treatment exhibited anti-fibrosis and was linked to Wnt/β-catenin signaling activity. TPH-1 exhibited anti-fibrotic effects by suppressing epithelial cell injury and fibroblast activation, and PAA promoted TPH-1 expression and then suppressed the Wnt/β-catenin signaling pathway via regulating the protein stability of β-catenin and β-catenin-mediated transcription. TPH-1 overexpression enhanced the anti-fibrotic effects of PAA, while TPH-1 deficiency weakened the anti-fibrotic effects of PAA, indicating that TPH-1 was required for the anti-fibrotic effects of PAA. Conclusion: PAA as a modulator of TPH-1 expression attenuated renal fibrosis through regulating the Wnt/β-catenin signaling pathway by acting on the protein stability of β-catenin and β-catenin-mediated transcription. TPH-1 was required for PAA to exert anti-fibrosis.

scholarly journals Klotho prevents epithelial–mesenchymal transition through Egr-1 downregulation in diabetic kidney disease

2021 ◽  
Vol 9 (1) ◽  
pp. e002038
Author(s):  
Yang Li ◽  
Meng Xue ◽  
Fang Hu ◽  
Yijie Jia ◽  
Zongji Zheng ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Signaling Pathway ◽  
Diabetic Kidney Disease ◽  
Transforming Growth Factor ◽  
Epithelial Mesenchymal Transition ◽  
Diabetic Kidney ◽  
Mesenchymal Transition ◽  
Hk2 Cells ◽  
Tgf Β1

IntroductionAs a key event leading to tubulointerstitial fibrosis in diabetic kidney disease (DKD), epithelial–mesenchymal transition (EMT) has drawn increasing attention from researchers. The antiaging protein Klotho attenuates renal fibrosis in part by inhibiting ERK1/2 signaling in DKD. Early growth response factor 1 (Egr-1), which is activated mainly by ERK1/2, has been shown to play an important role in EMT. However, whether Klotho prevents EMT by inhibiting ERK1/2-dependent Egr-1 expression in DKD is unclear.The aim of this study was to investigate whether Klotho prevents EMT through Egr-1 downregulation by inhibiting the ERK1/2 signaling pathway in DKD.Research design and methodsMale C57BL/6J mice fed an high-fat diet for 4 weeks received 120 mg/kg streptozotocin (STZ), which was injected intraperitoneally. Klotho and Egr-1 expression was detected in the renal cortices of these mice on their sacrifice at 6 and 12 weeks after STZ treatment. In In vitro studies, we incubated HK2 cells under high-glucose (HG) or transforming growth factor-β1 (TGF-β1) conditions to mimic DKD. We then transfected the cells with an Klotho-containing plasmid, Klotho small interfering RNA.ResultsKlotho expression was significantly decreased in the renal cortices of mice with diabetes mellitus (DM) compared with the renal cortices of control mice at 6 weeks after treatment and even more significantly decreased at 12 weeks. In contrast, Egr-1 expression was significantly increased in mice with DM compared with control mice only at 12 weeks. We also found that Klotho overexpression downregulated Egr-1 expression and the (p-ERK1/2):(ERK1/2) ratio in HG-treated or TGF-β1-treated HK2 cells. Conversely, Klotho silencing upregulated Egr-1 expression and the (p-ERK1/2):(ERK1/2) ratio in HG-treated or TGF-β1-treated HK2 cells. Moreover, the effects of si-Klotho were abolished by the ERK1/2 inhibitor PD98059.ConclusionsKlotho prevents EMT during DKD progression, an effect that has been partially attributed to Egr-1 downregulation mediated by ERK1/2 signaling pathway inhibition.

scholarly journals Role of Human Primary Renal Fibroblast in TGF-β1-Mediated Fibrosis-Mimicking Devices

2021 ◽  
Vol 22 (19) ◽  
pp. 10758
Author(s):  
Seong-Hye Hwang ◽  
Yun-Mi Lee ◽  
Yunyeong Choi ◽  
Hyung Eun Son ◽  
Ji Young Ryu ◽  
...  
Keyword(s):  
Growth Factor ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Umbilical Vein ◽  
Smooth Muscle Actin ◽  
Interleukin 1 ◽  
Alpha Smooth Muscle Actin ◽  
Necrosis Factor Alpha ◽  
Tgf Β1 ◽  
Inhibitor Treatment

Renal fibrosis is a progressive chronic kidney disease that ultimately leads to end-stage renal failure. Despite several approaches to combat renal fibrosis, an experimental model to evaluate currently available drugs is not ideal. We developed fibrosis-mimicking models using three-dimensional (3D) co-culture devices designed with three separate layers of tubule interstitium, namely, epithelial, fibroblastic, and endothelial layers. We introduced human renal proximal tubular epithelial cells (HK-2), human umbilical-vein endothelial cells, and patient-derived renal fibroblasts, and evaluated the effects of transforming growth factor-β (TGF-β) and TGF-β inhibitor treatment on this renal fibrosis model. The expression of the fibrosis marker alpha smooth muscle actin upon TGF-β1 treatment was augmented in monolayer-cultured HK-2 cells in a 3D disease model. In the vascular compartment of renal fibrosis models, the density of vessels was increased and decreased in the TGF-β-treated group and TGF-β-inhibitor treatment group, respectively. Multiplex ELISA using supernatants in the TGF-β-stimulating 3D models showed that pro-inflammatory cytokine and growth factor levels including interleukin-1 beta, tumor necrosis factor alpha, basic fibroblast growth factor, and TGF-β1, TGF-β2, and TGF-β3 were increased, which mimicked the fibrotic microenvironments of human kidneys. This study may enable the construction of a human renal fibrosis-mimicking device model beyond traditional culture experiments.

scholarly journals Arecoline Enhances Phosphodiesterase 4A Activity to Promote Transforming Growth Factor-β-Induced Buccal Mucosal Fibroblast Activation via cAMP-Epac1 Signaling Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Bo Zhang ◽  
Lihua Gao ◽  
Chunsheng Shao ◽  
Mingsi Deng ◽  
Liangjian Chen
Keyword(s):  
Growth Factor ◽  
Signaling Pathway ◽  
Transforming Growth Factor ◽  
Clinical Investigation ◽  
Smooth Muscle Actin ◽  
Oral Submucous Fibrosis ◽  
Transforming Growth Factor Β ◽  
Type I ◽  
Camp Analog ◽  
Tgf Β1

Chewing areca nut (betel quid) is strongly associated with oral submucous fibrosis (OSF), a pre-cancerous lesion. Among the areca alkaloids, arecoline is the main agent responsible for fibroblast proliferation; however, the specific molecular mechanism of arecoline affecting the OSF remains unclear. The present study revealed that arecoline treatment significantly enhanced Transforming growth factor-β (TGF-β)-induced buccal mucosal fibroblast (BMF) activation and fibrotic changes. Arecoline interacts with phosphodiesterase 4A (PDE4A) to exert its effects through modulating PDE4A activity but not PDE4A expression. PDE4A silence reversed the effects of arecoline on TGF-β-induced BMFs activation and fibrotic changes. Moreover, the exchange protein directly activated by cAMP 1 (Epac1)-selective Cyclic adenosine 3′,5′-monophosphate (cAMP) analog (8-Me-cAMP) but not the protein kinase A (PKA)-selective cAMP analog (N6-cAMP) remarkably suppressed α-smooth muscle actin(α-SMA) and Collagen Type I Alpha 1 Chain (Col1A1) protein levels in response to TGF-β1 and arecoline co-treatment, indicating that cAMP-Epac1 but not cAMP-PKA signaling is involved in arecoline functions on TGF-β1-induced BMFs activation. In conclusion, arecoline promotes TGF-β1-induced BMFs activation through enhancing PDE4A activity and the cAMP-Epac1 signaling pathway during OSF. This novel mechanism might provide more powerful strategies for OSF treatment, requiring further in vivo and clinical investigation.

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