Transforming growth factor-beta 1-induced activation of the ERK pathway/activator protein-1 in human lung fibroblasts requires the autocrine induction of basic fibroblast growth factor

Skin perfusion and oxygen saturation after mastectomy and radiation therapy in breast cancer patients

The pathophysiological mechanism behind complications associated with postmastectomy radiotherapy (PMRT) and subsequent implant-based breast reconstruction are not completely understood. The aim of this study was to examine if there is a relationship between PMRT and microvascular perfusion and saturation in the skin after mastectomy and assess if there is impaired responsiveness to a topically applied vasodilator (Methyl nicotinate - MN). Skin microvascular perfusion and oxygenation >2 years after PMRT were measured using white light diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF) in the irradiated chest wall of 31 women with the contralateral breast as a control. In the non-irradiated breast, the perfusion after application of MN (median 0.84, 25th-75th centile 0.59-1.02 % RBC × mm/s) was higher compared to the irradiated chest wall (median 0.51, 25th-75th centile 0.21-0.68 % RBC × mm/s, p < 0.001). The same phenomenon was noted for saturation (median 91 %, 25th-75th centile 89-94 % compared to 89 % 25th-75th centile 77-93 %, p = 0.001). Eight of the women (26%) had a ≥10 % difference in skin oxygenation between the non-irradiated breast and the irradiated chest wall. These results indicate that late microvascular changes caused by radiotherapy of the chest wall significantly affect skin perfusion and oxygenation.

Asarinin attenuates bleomycin-induced pulmonary fibrosis by activating PPARγ

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease that lacks effective treatment modalities. Once patients are diagnosed with IPF, their median survival is approximately 3-5 years. PPARγ is an important target for the prevention and treatment of pulmonary fibrosis. Asarinin is a lignan compound that can be extracted from food plant Asarum heterotropoides. In this study, we investigated the therapeutic effects of asarinin in a pulmonary fibrosis model constructed using bleomycin in mice and explored the underlying mechanisms. Intraperitoneal administration of asarinin to mice with pulmonary fibrosis showed that asarinin effectively attenuated pulmonary fibrosis, and this effect was significantly inhibited by the PPARγ inhibitor GW9662. Asarinin inhibited TGF-β1-induced fibroblast-to-myofibroblast transition in vitro, while GW9662 and PPARγ gene silencing significantly inhibited this effect. In addition, asarinin inhibited not only the canonical Smad pathway of TGF-β but also the non-canonical AKT and MAPK pathways by activating PPARγ. Our study demonstrates that asarinin can be used as a therapeutic agent for pulmonary fibrosis, and that PPARγ is its key target.

XIST/let-7i/HMGA1 axis maintains myofibroblasts activities in oral submucous fibrosis

Long non-coding RNA XIST promotes the development of various types of head and neck cancers, but its role in the progression of precancerous oral submucous fibrosis (OSF) has not been determined yet. As such, we aimed to examine whether XIST implicates in the regulation of myofibroblast activation. Our results showed that the expression of XIST was upregulated in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs), and the silencing of XIST downregulated several myofibroblasts features. We demonstrated that elevation of let-7i after inhibition of XIST may lead to reduced myofibroblast activation. On the contrary, overexpression of high mobility group AT-Hook 1 (HMGA1) following the suppression of let-7i may result in enhanced myofibroblast activities. Moreover, we showed that the suppressive effect of silencing of XIST on myofibroblasts hallmarks was reversed by let-7i inhibition or HMGA1 overexpression, suggesting the pro-fibrotic property of XIST was mediated by downregulation of let-7i and upregulation of HMGA1. These findings revealed that myofibroblast activation of fBMFs may attribute to the alteration of the XIST/let-7i/HMGA1 axis. Therapeutic approaches to target this axis may serve as a promising direction to ameliorate the malignant progression of OSF.

2-Methoxyestradiol TPGS Micelles Attenuate Cyclosporine A-Induced Nephrotoxicity in Rats through Inhibition of TGF-β1 and p-ERK1/2 Axis

The immunosuppressant cyclosporine A (CSA) has been linked to serious renal toxic effects. Although 2-methoxyestradiol (2ME) possesses a wide range of pharmacological abilities, it suffers poor bioavailability after oral administration. The purpose of this study was to evaluate the potential of 2ME loaded D-ɑ-tocopheryl polyethylene glycol succinate (TPGS) micelles to prevent CSA-induced nephrotoxicity in rats. A 2ME-TPGS was prepared and showed particle size of 44.3 ± 3.5 nm with good entrapment efficiency and spherical structures. Male Wistar rats were divided into 5 groups, namely: Control, Vehicle, CSA, CSA + 2ME-Raw, and CSA + 2ME-Nano. CSA was injected daily at a SC dose of 20 mg/kg. Both 2ME-Raw and 2ME-Nano were given daily at oral doses of 5 mg/kg. Treatments continued for three successive weeks. 2ME-TPGS exerted significant protective effects against CSA nephrotoxicity. This was evidenced in ameliorating deterioration of renal functions, attenuation of pathological changes in kidney tissues, exerting significant anti-fibrotic, antioxidant, and anti-inflammatory effects together with significant anti-apoptotic effects. Western blot analyses showed both 2ME-Raw and 2ME-Nano significantly inhibited protein expression of TGF-β1 and phospho-ERK (p-ERK). It was observed that 2ME-TPGS, in almost all experiments, exerted superior protective effects as compared with 2ME-Raw. In conclusion, 2ME loaded in a TPGS nanocarrier possesses significant protective activities against CSA-induced kidney injury in rats. This is attributable to 2ME anti-fibrotic, antioxidant, anti-inflammatory, and anti-apoptotic activities which are mediated at least partly by inhibition of TGF-β1/p-ERK axis.

TGF‑β1: Gentlemanly orchestrator in idiopathic pulmonary fibrosis (Review)

Idiopathic pulmonary fibrosis (IPF) is a worldwide disease characterized by the chronic and irreversible decline of lung function. Currently, there is no drug to successfully treat the disease except for lung transplantation. Numerous studies have been devoted to the study of the fibrotic process of IPF and findings showed that transforming growth factor-β1 (TGF-β1) plays a central role in the development of IPF. TGF-β1 promotes the fibrotic process of IPF through various signaling pathways, including the Smad, MAPK, and ERK signaling pathways. There are intersections between these signaling pathways, which provide new targets for researchers to study new drugs. In addition, TGF-β1 can affect the fibrosis process of IPF by affecting oxidative stress, epigenetics and other aspects. Most of the processes involved in TGF-β1 promote IPF, but TGF-β1 can also inhibit it. This review discusses the role of TGF-β1 in IPF.

Early Moderate Intensity Aerobic Exercise Intervention Prevents Doxorubicin-Caused Cardiac Dysfunction Through Inhibition of Cardiac Fibrosis and Inflammation

Doxorubicin (DOX) is known as an effective drug in the fight against various cancers. However, one of the greatest impediments is DOX-induced cardiomyopathy, which may potentially lead to heart failure. Accumulating evidence has shed light on the pathological mechanism of DOX-induced cardiotoxicity, but treatments to mitigate the cardiac damage are still required. In an attempt to address this issue, we evaluated whether exercise provides cardioprotective effects on the DOX-induced cardiotoxicity. We showed that treadmill exercise (3 times/week; 1-week of exercise acclimatization and 4-weeks of endurance exercise) during the DOX treatment successfully prevented the cardiac dysfunction. The DOX-stimulated expression of IκBα, NF-κB, COX-2, and IL-8 were all downregulated by exercise as well as the fibrosis factors (TGF-β1, phosphorylated ERK, Sp1, and CTGF). Moreover, we showed that treadmill exercise diminished the expression of several cardiac remodeling-associated factors, such as FGF2, uPA, MMP2, and MMP9. These results were in line with the finding that exercise intervention reduced cardiac fibrosis and restored cardiac function, with higher values of ejection fraction and fractional shortening compared to the DOX-treated group. Two commonly used indicators of cardiac injury, lactate dehydrogenase, and creatine kinase-MB, were also decreased in the exercise group. Collectively, our results suggested that it may be beneficial to prescribe treadmill exercise as an adjunct therapy to limit cardiac damage caused by DOX.

A new FGFR inhibitor disrupts the TGF-β1-induced fibrotic process

Pulmonary fibrosis (PF) is chronic and irreversible damage to the lung characterized by fibroblast activation and matrix deposition. Although recently approved novel anti‐fibrotic agents can improve the lung function and survival of patients with PF, the overall outcomes remain poor. In this study, a novel imidazopurine compound, 3‐(2‐chloro‐6‐fluorobenzyl)‐1,6,7‐trimethyl‐1H‐imidazo[2,1‐f]purine‐2,4(3H,8H)‐dione (IM‐1918), markedly inhibited transforming growth factor (TGF)‐β‐stimulated reporter activity and reduced the expression of representative fibrotic markers, such as connective tissue growth factor, fibronectin, collagen and α‐smooth muscle actin, on human lung fibroblasts. However, IM‐1918 neither decreased Smad‐2 and Smad‐3 nor affected p38MAPK and JNK. Instead, IM‐1918 reduced Akt and extracellular signal‐regulated kinase 1/2 phosphorylation increased by TGF‐β. Additionally, IM‐1918 inhibited the phosphorylation of fibroblast growth factor receptors 1 and 3. In a bleomycin‐induced murine lung fibrosis model, IM‐1918 profoundly reduced fibrotic areas and decreased collagen and α‐smooth muscle actin accumulation. These results suggest that IM‐1918 can be applied to treat lung fibrosis.

Anlotinib attenuated bleomycin-induced pulmonary fibrosis via the TGF-β1 signalling pathway

OBJECTIVES

Anlotinib hydrochloride (AL3818) is a novel multitarget tyrosine kinase inhibitor which has the same targets as nintedanib, an effective drug has been approved for the treatment of idiopathic pulmonary fibrosis. Here, we examined whether anlotinib could also attenuate bleomycin-induced pulmonary fibrosis in mice and explored the antifibrosis mechanism.

METHODS

We have evaluated the effect of anlotinib on bleomycin-induced pulmonary fibrosis in mice. Inflammatory cytokines in alveolar lavage fluid including IL-1β, IL-4, IL-6 and TNF-α were determined by ELISA. Biomarkers of oxidative stress were measured by corresponding kit. Histopathologic examination was analysed by H&E staining and immunohistochemistry. In vitro, we investigated whether anlotinib inhibited TGFβ/Smad3 and non-Smad pathways by luciferase assay or Western blotting. We also evaluated whether anlotinib inhibited TGF-β1-induced epithelial-mesenchymal transition (EMT) and promoted myofibroblast apoptosis in order to explore the possible molecular mechanism.

KEY FINDINGS

The results indicated that anlotinib treatment remarkably attenuated inflammation, oxidative stress and pulmonary fibrosis in mouse lungs. Anlotinib could inhibit the TGF-β1 signalling pathway. Additionally, anlotinib not only profoundly inhibited TGF-β1-induced EMT in alveolar epithelial cells, but also simultaneously reduced the proliferation and promoted the apoptosis in fibroblasts.

CONCLUSIONS

In summary, the results suggest that anlotinib-mediated suppression of pulmonary fibrosis is related to the inhibition of TGF-β1 signalling pathway.

Integration of inflammation, fibrosis, and cancer induced by carbon nanotubes

Carbon nanotubes (CNTs) are nanomaterials with unique physicochemical properties that are targets of great interest for industrial and commercial applications. Notwithstanding, some characteristics of CNTs are associated with adverse outcomes from exposure to pathogenic particulates, raising concerns over health risks in exposed workers and consumers. Indeed, certain forms of CNTs induce a range of harmful effects in laboratory animals, among which inflammation, fibrosis, and cancer are consistently observed for some CNTs. Inflammation, fibrosis, and malignancy are complex pathological processes that, in summation, underlie a major portion of human disease. Moreover, the functional interrelationship among them in disease pathogenesis has been increasingly recognized. The CNT-induced adverse effects resemble certain human disease conditions, such as pneumoconiosis, idiopathic pulmonary fibrosis (IPF), and mesothelioma, to some extent. Progress has been made in understanding CNT-induced pathologic conditions in recent years, demonstrating a close interconnection among inflammation, fibrosis, and cancer. Mechanistically, a number of mediators, signaling pathways, and cellular processes are identified as major mechanisms that underlie the interplay among inflammation, fibrosis, and malignancy, and serve as pathogenic bases for these disease conditions in CNT-exposed animals. These studies indicate that CNT-induced pathological effects, in particular, inflammation, fibrosis, and cancer, are mechanistically, and in some cases, causatively, interrelated. These findings generate new insights into CNT adverse effects and pathogenesis and provide new targets for exposure monitoring and drug development against inflammation, fibrosis, and cancer caused by inhaled nanomaterials.

Transforming growth factor-β downregulates sGC subunit expression in pulmonary artery smooth muscle cells via MEK and ERK signaling

TGFβ activation during newborn lung injury decreases the expression of pulmonary artery smooth muscle cell (PASMC)-soluble guanylate cyclase (sGC), a critical mediator of nitric oxide signaling. Using a rat PASMC line (CS54 cells), we determined how TGFβ downregulates sGC expression. We found that TGFβ decreases sGC expression through stimulating its type I receptor; TGFβ type I receptor (TGFβR1) inhibitors prevented TGFβ-1-mediated decrease in sGCα1 subunit mRNA levels in the cells. However, TGFβR1-Smad mechanisms do not regulate sGC; effective knockdown of Smad2 and Smad3 expression and function did not protect sGCα1 mRNA levels during TGFβ-1 exposure. A targeted small-molecule kinase inhibitor screen suggested that MEK signaling regulates sGC expression in TGFβ-stimulated PASMC. TGFβ activates PASMC MEK/ERK signaling; CS54 cell treatment with TGFβ-1 increased MEK and ERK phosphorylation in a biphasic, time- and dose-dependent manner. Moreover, MEK/ERK activity appears to be required for TGFβ-mediated sGC expression inhibition in PASMC; MEK and ERK inhibitors protected sGCα1 mRNA expression in TGFβ-1-treated CS54 cells. Nuclear ERK activity is sufficient for sGC regulation; heterologous expression of a nucleus-retained, constitutively active ERK2-MEK1 fusion protein decreased CS54 cell sGCα1 mRNA levels. The in vivo relevance of this TGFβ-MEK/ERK-sGC downregulation pathway is suggested by the detection of ERK activation and sGCα1 protein expression downregulation in TGFβ-associated mouse pup hyperoxic lung injury, and the determination that ERK decreases sGCα1 protein expression in TGFβ-1-treated primary PASMC obtained from mouse pups. These studies identify MEK/ERK signaling as an important pathway by which TGFβ regulates sGC expression in PASMC.

Interactions between TGF-β1, canonical WNT/β-catenin pathway and PPAR γ in radiation-induced fibrosis

Radiation therapy induces DNA damage and inflammation leading to fibrosis. Fibrosis can occur 4 to 12 months after radiation therapy. This process worsens with time and years. Radiation-induced fibrosis is characterized by fibroblasts proliferation, myofibroblast differentiation, and synthesis of collagen, proteoglycans and extracellular matrix. Myofibroblasts are non-muscle cells that can contract and relax. Myofibroblasts evolve towards irreversible retraction during fibrosis process. In this review, we discussed the interplays between transforming growth factor-β1 (TGF-β1), canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPAR γ) in regulating the molecular mechanisms underlying the radiation-induced fibrosis, and the potential role of PPAR γ agonists. Overexpression of TGF-β and canonical WNT/β-catenin pathway stimulate fibroblasts accumulation and myofibroblast differentiation whereas PPAR γ expression decreases due to the opposite interplay of canonical WNT/β-catenin pathway. Both TGF-β1 and canonical WNT/β-catenin pathway stimulate each other through the Smad pathway and non-Smad pathways such as phosphatidylinositol 3-kinase/serine/threonine kinase (PI3K/Akt) signaling. WNT/β-catenin pathway and PPAR γ interact in an opposite manner. PPAR γ agonists decrease β-catenin levels through activation of inhibitors of the WNT pathway such as Smad7, glycogen synthase kinase-3 (GSK-3 β) and dickkopf-related protein 1 (DKK1). PPAR γ agonists also stimulate phosphatase and tensin homolog (PTEN) expression, which decreases both TGF-β1 and PI3K/Akt pathways. PPAR γ agonists by activating Smad7 decrease Smads pathway and then TGF-β signaling leading to decrease radiation-induced fibrosis. TGF-β1 and canonical WNT/β-catenin pathway promote radiation-induced fibrosis whereas PPAR γ agonists can prevent radiation-induced fibrosis.

Pulmonary fibrosis requires cell-autonomous mesenchymal fibroblast growth factor (FGF) signaling

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive pulmonary scarring, decline in lung function, and often results in death within 3-5 five years after diagnosis. Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of IPF; however, the mechanism through which FGF signaling contributes to pulmonary fibrosis remains unclear. We hypothesized that FGF receptor (FGFR) signaling in fibroblasts is required for the fibrotic response to bleomycin. To test this, mice with mesenchyme-specific tamoxifen-inducible inactivation of FGF receptors 1, 2, and 3 (Col1α2-CreER; TCKO mice) were lineage labeled and administered intratracheal bleomycin. Lungs were collected for histologic analysis, whole lung RNA and protein, and dissociated for flow cytometry and FACS. Bleomycin-treated Col1α2-CreER; TCKO mice have decreased pulmonary fibrosis, collagen production, and fewer α-smooth muscle actin-positive (αSMA+) myofibroblasts compared with controls. Freshly isolated Col1α2-CreER; TCKO mesenchymal cells from bleomycin-treated mice have decreased collagen expression compared with wild type mesenchymal cells. Furthermore, lineage labeled FGFR-deficient fibroblasts have decreased enrichment in fibrotic areas and decreased proliferation. These data identify a cell autonomous requirement for mesenchymal FGFR signaling in the development of pulmonary fibrosis, and for the enrichment of the Col1α2-CreER-positive (Col1α2+) mesenchymal lineage in fibrotic tissue following bleomycin exposure. We conclude that mesenchymal FGF signaling is required for the development of pulmonary fibrosis, and that therapeutic strategies aimed directly at mesenchymal FGF signaling could be beneficial in the treatment of IPF.

Fine-tuning vascular fate during endothelial-mesenchymal transition

In the heart and other organs, endothelial-mesenchymal transition (EndMT) has emerged as an important developmental process that involves coordinated migration, differentiation, and proliferation of the endothelium. In multiple disease states including cancer angiogenesis and cardiovascular disease, the processes that regulate EndMT are recapitulated, albeit in an uncoordinated and dysregulated manner. Members of the transforming growth factor beta (TGFβ) superfamily are well known to impart cellular plasticity during EndMT by the timely activation (or repression) of transcription factors and miRNAs in addition to epigenetic regulation of gene expression. On the other hand, fibroblast growth factors (FGFs) are reported to augment or oppose TGFβ-driven EndMT in specific contexts. Here, we have synthesized the currently understood roles of TGFβ and FGF signalling during EndMT and have provided a new, comprehensive paradigm that delineates how an autocrine and paracrine TGFβ/FGF axis coordinates endothelial cell specification and plasticity. We also provide new guidelines and nomenclature that considers factors such as endothelial cell heterogeneity to better define EndMT across different vascular beds. This perspective should therefore help to clarify why TGFβ and FGF can both cooperate with or oppose one another during the complex process of EndMT in both health and disease. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Myofibroblasts and lung fibrosis induced by carbon nanotube exposure

Carbon nanotubes (CNTs) are newly developed materials with unique properties and a range of industrial and commercial applications. A rapid expansion in the production of CNT materials may increase the risk of human exposure to CNTs. Studies in rodents have shown that certain forms of CNTs are potent fibrogenic inducers in the lungs to cause interstitial, bronchial, and pleural fibrosis characterized by the excessive deposition of collagen fibers and the scarring of involved tissues. The cellular and molecular basis underlying the fibrotic response to CNT exposure remains poorly understood. Myofibroblasts are a major type of effector cells in organ fibrosis that secrete copious amounts of extracellular matrix proteins and signaling molecules to drive fibrosis. Myofibroblasts also mediate the mechano-regulation of fibrotic matrix remodeling via contraction of their stress fibers. Recent studies reveal that exposure to CNTs induces the differentiation of myofibroblasts from fibroblasts in vitro and stimulates pulmonary accumulation and activation of myofibroblasts in vivo. Moreover, mechanistic analyses provide insights into the molecular underpinnings of myofibroblast differentiation and function induced by CNTs in the lungs.

In view of the apparent fibrogenic activity of CNTs and the emerging role of myofibroblasts in the development of organ fibrosis, we discuss recent findings on CNT-induced lung fibrosis with emphasis on the role of myofibroblasts in the pathologic development of lung fibrosis. Particular attention is given to the formation and activation of myofibroblasts upon CNT exposure and the possible mechanisms by which CNTs regulate the function and dynamics of myofibroblasts in the lungs. It is evident that a fundamental understanding of the myofibroblast and its function and regulation in lung fibrosis will have a major influence on the future research on the pulmonary response to nano exposure, particle and fiber-induced pneumoconiosis, and other human lung fibrosing diseases.

Baicalin attenuates bleomycin-induced pulmonary fibrosis via adenosine A2a receptor related TGF-β1-induced ERK1/2 signaling pathway

BACKGROUND

Baicalin has been reported to have anti-fibrosis effect; however, its mechanism still remains to be elucidated. Adenosine A2a receptor (A2aR) is a novel inflammation regulator, and transforming growth factor-β1 (TGF-β1)-induced extracellular signal regulated kinase1/2 (ERK1/2) signaling pathway plays an important role in idiopathic pulmonary fibrosis (IPF). This study was to explore the relationship of A2aR and TGF-β1-induced ERK1/2 in bleomycin (BLM)-induced pulmonary fibrosis in mice, and to investigate whether A2aR mediate the anti-fibrosis effect of Baicalin on BLM-induced pulmonary fibrosis.

METHODS

The A2aR-/- and A2aR+/+ mice were respectively divided into three groups: control group, model group, baicalin group. Pulmonary fibrosis was induced in mice of model groups by intratracheal instillation of bleomycin, and baicalin was administered in mice of baicalin groups daily for 28 days. Histopathological and ultrastructural changes of lung tissues were evaluated. Lung coefficient and the levels of hydroxyproline (HYP) in lung tissues were measured at the same time. The levels of serum TGF-β1 were measured by ELISA. The expression of TGF-β1, ERK1/2, p-ERK1/2 and A2aR were detected by western blot and immunohistochemical staining techniques.

RESULTS

Severe lung fibrosis was observed in the bleomycin-treated mice on day 28. The histopathological findings and collagen content of lung tissues were much severer/higher in A2aR-/- mice than in A2aR+/+ mice. We also showed that TGF-β1 and p-ERK1/2 were upregulated in bleomycin-treated mice and expressed higher in A2aR-/- mice compared to A2aR+/+ mice. Besides, bleomycin-treated A2aR+/+ mice had increased A2aR level in lungs. However, long-term treatment with baicalin in A2aR-/- and A2aR+/+ mice significantly ameliorated the histopathological changes in lungs. Moreover, Increased TGF-β1 and p-ERK1/2 expressions in bleomycin-treated A2aR-/- and A2aR+/+ mice were obviously diminished by baicalin. The baicalin-treated A2aR-/- mice had severer lung fibrosis and higher expressions of TGF-β1 and p-ERK1/2 than A2aR+/+ mice. Baicalin has also upregulated the expression of A2aR in A2aR+/+ mice.

CONCLUSIONS

Genetic inactivation of A2aR exacerbated the pathological processes of bleomycin-induced pulmonary fibrosis. Together, baicalin could inhibit BLM-induced pulmonary fibrosis by upregulating A2aR, suggesting A2aR as a therapeutic target of baicalin for the treatment of pulmonary fibrosis.

Hydroxysafflor yellow A inhibits TGF-β1-induced activation of human fetal lung fibroblasts in vitro

Objective

Hydroxysafflor yellow A (HSYA) is one of the chemical component isolated from Chinese medicine Carthamus tinctorius L. Our preliminary study confirmed that HSYA attenuated bleomycin-induced pulmonary fibrosis in mice. In this study, we evaluated the effect of HSYA on TGF-β1-induced activation of human fetal lung fibroblasts (MRC-5) and explored the underlying mechanisms of its activity.

Method

MRC-5 cells activated by TGF-β1 were incubated with HSYA and/or the TGF-β type I receptor inhibitor, SB431542. TGF-β1-induced cell proliferation, α-smooth muscle actin, collagen I alpha 1 and fibronectin expression, Smad, mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase/Akt signalling pathway activation were observed.

Key findings

Hydroxysafflor yellow A significantly inhibited TGF-β1-induced cell proliferation and the expression, both mRNA and protein, of α-smooth muscle actin, collagen I alpha 1 and fibronectin. HSYA also suppressed TGF-β1 activation of Smad signal transduction via inhibition of Smad2 and Smad3 phosphorylation, their nuclear translocation and the binding activity of Smad3 to type I collagen promoter in MRC-5 cells. In addition, HSYA inhibited TGF-β1-induced phosphorylation of extracellular signal-regulated kinase (ERK). The inhibitory effects of HSYA were similar to SB431542.

Conclusion

These findings suggest that HSYA inhibits TGF-β1-induced activation of MRC-5 cells associated with TGF-β1/Smad and ERK/MAPK signalling pathways.

NADPH oxidase 4 deficiency leads to impaired wound repair and reduced dityrosine-crosslinking, but does not affect myofibroblast formation

NADPH oxidases (NOX) mediate redox signaling by generating superoxide and/or hydrogen peroxide, which are involved in biosynthetic pathways, e.g. thyroid hormone generation, dityrosine crosslinking, as well as bacterial killing. Data investigating the role of NOX enzymes in cutaneous wound repair is limited and specifically their function in skin myofibroblast expression is unknown. The isoform NOX4 was recently shown to be a pre-requisite for the differentiation of cardiac and pulmonary myofibroblasts. In this study we investigate the role of NOX4 in wound repair using a wound model in NOX4 knockout mice (n=16) and wildtype mice (n=16). Wounds were photographed daily until complete wound closure. Mice were sacrificed at day 3, 7, 14; wound tissue was harvested. NOX4-deficient mice healed significantly slower (22 days, SD=1.9) than wild-type mice (17 days, SD=1.4, p<0.005). However, there was no difference in myofibroblast expression. Strong dityrosine formation was observed, but was significantly weaker in NOX4-/- mice (p<0.05). NOX2, HIF1α and CD31 expression was significantly weaker in NOX4-/- mice (p<0.05). In this study we show for the first time that NOX4 plays a role in cutaneous wound repair. Our data suggests that NOX4 mediates HIF1α expression and neoangiogenesis during wound repair. NOX4 deletion led to a decreased expression of NOX2, implying a role of NOX4 in phagocytic cell recruitment. NOX4 was required for effective wound contraction but not myofibroblast expression. We suggest that myofibroblast contraction in NOX4-deficient mice is less effective in contracting the wound because of insufficient dityrosine-crosslinking of the ECM, providing the first indication for a physiological function of dityrosine crosslinking in higher animals.

Enhanced Expression of Integrin αvβ3 Induced by TGF-β Is Required for the Enhancing Effect of Fibroblast Growth Factor 1 (FGF1) in TGF-β-Induced Epithelial-Mesenchymal Transition (EMT) in Mammary Epithelial Cells

Epithelial-to-mesenchymal transition (EMT) plays a critical role in cancer metastasis, and is regulated by growth factors such as transforming growth factor β (TGF-β) and fibroblast growth factors (FGF) secreted from the stromal and tumor cells. However, the role of growth factors in EMT has not been fully established. Several integrins are upregulated by TGF-β1 during EMT. Integrins are involved in growth factor signaling through integrin-growth factor receptor crosstalk. We previously reported that FGF1 directly binds to integrin αvβ3 and the interaction was required for FGF1 functions such as cell proliferation and migration. We studied the role of αvβ3 induced by TGF-β on TGF-β-induced EMT. Here, we describe that FGF1 augmented EMT induced by TGF-β1 in MCF10A and MCF12A mammary epithelial cells. TGF-β1 markedly amplified integrin αvβ3 and FGFR1 (but not FGFR2). We studied if the enhancing effect of FGF1 on TGF-β1-induced EMT requires enhanced levels of both integrin αvβ3 expression and FGFR1. Knockdown of β3 suppressed the enhancement by FGF1 of TGF-β1-induced EMT in MCF10A cells. Antagonists to FGFR suppressed the enhancing effect of FGF1 on EMT. Integrin-binding defective FGF1 mutant did not augment TGF-β1-induced EMT in MCF10A cells. These findings suggest that enhanced integrin αvβ3 expression in addition to enhanced FGFR1 expression is critical for FGF1 to augment TGF-β1-induced EMT in mammary epithelial cells.

The anti-fibrotic effects of microRNA-153 by targeting TGFBR-2 in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial fibrotic lung disease with an undefined etiology and no effective treatments. By binding to cell surface receptors, transforming growth factor-β (TGF-β) plays a pivotal role in lung fibrosis. Therefore, the screening of microRNAs (miRNAs), especially those interrupting the effects of TGF-β, may provide information not only on the pathomechanism, but also on the treatment of this disease. In the present study, we found that miR-153 expression was dysregulated in the lungs of mice with experimental pulmonary fibrosis and TGF-β1 decreased miR-153 expression in pulmonary fibroblasts. Moreover, increased miR-153 levels attenuated, whereas the knock down of miR-153 promoted the pro-fibrogenic activity of TGF-β1, and miR-153 reduced the contractile and migratory activities of fibroblasts. In addition, TGFBR2, a transmembrane serine/threonine kinase receptor for TGF-β, was identified as a direct target of miR-153. Furthermore, by post-transcriptional regulation of the expression of TGFBR2, phosphorylation of SMAD2/3 was also influenced by miR-153. These data suggest that miR-153 disturbs TGF-β1 signal transduction and its effects on fibroblast activation, acting as an anti-fibrotic element in the development of pulmonary fibrosis.

Radiation-induced fibrosis: mechanisms and implications for therapy

PURPOSE

Radiation-induced fibrosis (RIF) is a long-term side effect of external beam radiation therapy for the treatment of cancer. It results in a multitude of symptoms that significantly impact quality of life. Understanding the mechanisms of RIF-induced changes is essential to developing effective strategies to prevent long-term disability and discomfort following radiation therapy. In this review, we describe the current understanding of the etiology, clinical presentation, pathogenesis, treatment, and directions of future therapy for this condition.

METHODS

A literature review of publications describing mechanisms or treatments of RIF was performed. Specific databases utilized included PubMed and clinicaltrials.gov, using keywords "Radiation-Induced Fibrosis," "Radiotherapy Complications," "Fibrosis Therapy," and other closely related terms.

RESULTS

RIF is the result of a misguided wound healing response. In addition to causing direct DNA damage, ionizing radiation generates reactive oxygen and nitrogen species that lead to localized inflammation. This inflammatory process ultimately evolves into a fibrotic one characterized by increased collagen deposition, poor vascularity, and scarring. Tumor growth factor beta serves as the primary mediator in this response along with a host of other cytokines and growth factors. Current therapies have largely been directed toward these molecular targets and their associated signaling pathways.

CONCLUSION

Although RIF is widely prevalent among patients undergoing radiation therapy and significantly impacts quality of life, there is still much to learn about its pathogenesis and mechanisms. Current treatments have stemmed from this understanding, and it is anticipated that further elucidation will be essential for the development of more effective therapies.

TGFβ Signaling in Tumor Initiation, Epithelial-to-Mesenchymal Transition, and Metastasis

Retaining the delicate balance in cell signaling activity is a prerequisite for the maintenance of physiological tissue homeostasis. Transforming growth factor-beta (TGFβ) signaling is an essential pathway that plays crucial roles during embryonic development as well as in adult tissues. Aberrant TGFβ signaling activity regulates tumor progression in a cancer cell-autonomous or non-cell-autonomous fashion and these effects may be tumor suppressing or tumor promoting depending on the cellular context. The fundamental role of this pathway in promoting cancer progression in multiple stages of the metastatic process, including epithelial-to-mesenchymal transition (EMT), is also becoming increasingly clear. In this review, we discuss the latest advances in the effort to unravel the inherent complexity of TGFβ signaling and its role in cancer progression and metastasis. These findings provide important insights into designing personalized therapeutic strategies against advanced cancers.

Fibroblast growth factor 2 is required for epithelial recovery, but not for pulmonary fibrosis, in response to bleomycin

The pathogenesis of pulmonary fibrosis involves lung epithelial injury and aberrant proliferation of fibroblasts, and results in progressive pulmonary scarring and declining lung function. In vitro, fibroblast growth factor (FGF) 2 promotes myofibroblast differentiation and proliferation in cooperation with the profibrotic growth factor, transforming growth factor-β1, but the in vivo requirement for FGF2 in the development of pulmonary fibrosis is not known. The bleomycin model of lung injury and pulmonary fibrosis was applied to Fgf2 knockout (Fgf2(-/-)) and littermate control mice. Weight loss, mortality, pulmonary fibrosis, and histology were analyzed after a single intranasal dose of bleomycin. Inflammation was evaluated in bronchoalveolar lavage (BAL) fluid, and epithelial barrier integrity was assessed by measuring BAL protein and Evans Blue dye permeability. Fgf2 is expressed in mouse and human lung epithelial and inflammatory cells, and, in response to bleomycin, Fgf2(-/-) mice have significantly increased mortality and weight loss. Analysis of BAL fluid and histology show that pulmonary fibrosis is unaltered, but Fgf2(-/-) mice fail to efficiently resolve inflammation, have increased BAL cellularity, and, importantly, deficient recovery of epithelial integrity. Fgf2(-/-) mice similarly have deficient recovery of club cell secretory protein(+) bronchial epithelium in response to naphthalene. We conclude that FGF2 is not required for bleomycin-induced pulmonary fibrosis, but rather is essential for epithelial repair and maintaining epithelial integrity after bleomycin-induced lung injury in mice. These data identify that FGF2 acts as a protective growth factor after lung epithelial injury, and call into question the role of FGF2 as a profibrotic growth factor in vivo.

SMAD-independent down-regulation of caveolin-1 by TGF-β: effects on proliferation and survival of myofibroblasts

Transforming growth factor-β (TGF-β) mediates growth-inhibitory effects on most target cells via activation of the canonical SMAD signaling pathway. This growth-inhibitory activity may be coupled with cellular differentiation. Our studies demonstrate that TGF-β1 inhibits proliferation of primary, non-transformed human lung fibroblasts in association with the induction of myofibroblast differentiation. Differentiated myofibroblasts maintain the capacity to proliferate in response to exogenous mitogenic stimuli and are resistant to serum deprivation-induced apoptosis. These proliferative and anti-apoptotic properties of myofibroblasts are related, in part, to the down-regulation of caveolin-1 (Cav-1) by TGF-β1. Cav-1 down-regulation is mediated by early activation of p38 MAPK and does not require SMAD signaling. In contrast, myofibroblast differentiation is dependent on activation of the SMAD pathway, but not on p38 MAPK. Thus, combinatorial signaling by TGF-β1 of myofibroblast differentiation and down-regulation of Cav-1 by SMAD and p38 MAPK pathways, respectively, confer proliferative and apoptosis-resistant properties to myofibroblasts. Selective targeting of this SMAD-independent, p38-MAPK/Cav-1-dependent pathway is likely to be effective in the treatment of pathological conditions characterized by TGF-β signaling and myofibroblast activation.

Role of TGFβ in regulation of the tumor microenvironment and drug delivery (review)

Deregulation of cell signaling homeostasis is a predominant feature of cancer initiation and progression. Transforming growth factor β (TGFβ) is a pleiotropic cytokine, which regulates numerous biological processes of various tissues in an autocrine and paracrine manner. Aberrant activity of TGFβ signaling is well known to play dual roles in cancer, depending on tumor stage and cellular context. The crucial roles of TGFβ in modulating the tumor microenvironment, its contribution to the accumulation of mechanical forces within the solid constituents of a tumor and its effects on the effective delivery of drugs are also becoming increasingly clear. In this review, we discuss the latest advances in the efforts to unravel the effects of TGFβ signaling in various components of the tumor microenvironment and how these influence the generation of forces and the efficacy of drugs. We also report the implications of tumor mechanics in cancer therapy and the potential usage of anti-TGFβ agents to enhance drug delivery and augment existing therapeutic approaches. These findings provide new insights towards the significance of targeting TGFβ pathway to enhance personalized tumor treatment.

Smad-independent pathway involved in transforming growth factor β1-induced Nox4 expression and proliferation of endothelial cells

NADPH oxidase-derived reactive oxygen species are important for various cellular functions, including proliferation. Endothelial cells predominantly express the Nox4 isoform of NADPH oxidase, but it is not entirely clear how it is regulated. In this study, we investigated the signalling pathways involved in transforming growth factor-β1 (TGF-β1)-induced Nox4 expression and the proliferation of human microvascular endothelial cells (HMECs). TGF-β1 stimulated Nox4 messenger RNA and protein expression in HMECs. TGF-β1-induced Nox4 also increased hydrogen peroxide production, which was inhibited by diphenyleneiodonium and EUK134. The acute treatment of HMECs with TGF-β1 enhanced the phosphorylation of Smad2 and extracellular signal-regulated kinase (ERK) 1/2, without affecting p38MAPK, Akt, or Jun N-terminal kinase 1/2 (JNK1/2) pathways. Further, inhibition of Smad2 signalling using an inhibitor of activin receptor-linked kinase 5 SB431542 reduced TGF-β1-induced Nox4 expression, while inhibition of ERK1/2 with the inhibitor of mitogen-activated protein kinase kinase 1/2 U0126 decreased both basal and TGF-β1-induced Nox4 expression. Inhibition of ERK1/2 phosphorylation with U0126 did not affect Smad2 phosphorylation. Finally, TGF-β1 enhanced endothelial cell proliferation, which was reduced by U0126 but not by SB431542. These findings suggest that the non-canonical pathway ERK1/2 regulates Nox4 expression and may be involved in TGF-β1-induced proliferation of endothelial cells, which is vital during angiogenesis and vascular development.

Nicotine stimulates nerve growth factor in lung fibroblasts through an NFκB-dependent mechanism

RATIONALE

Airway hyperresponsiveness (AHR) is classically found in asthma, and persistent AHR is associated with poor asthma control. Although airway smooth muscle (ASM) cells play a critical pathophysiologic role in AHR, the paracrine contributions of surrounding cells such as fibroblasts to the contractile phenotype of ASM cells have not been examined fully. This study addresses the hypothesis that nicotine promotes a contractile ASM cell phenotype by stimulating fibroblasts to increase nerve growth factor (NGF) secretion into the environment.

METHODS

Primary lung fibroblasts isolated from wild type and α7 nicotinic acetylcholine receptor (α7 nAChR) deficient mice were treated with nicotine (50 µg/ml) in vitro for 72 hours. NGF levels were measured in culture media and in bronchoalveolar lavage (BAL) fluid from asthmatic, smoking and non-smoking subjects by ELISA. The role of the NFκB pathway in nicotine-induced NGF expression was investigated by measuring NFκB nuclear translocation, transcriptional activity, chromatin immunoprecipitation assays, and si-p65 NFκB knockdown. The ability of nicotine to stimulate a fibroblast-mediated, contractile ASM cell phenotype was confirmed by examining expression of contractile proteins in ASM cells cultured with fibroblast-conditioned media or BAL fluid.

RESULTS

NGF levels were elevated in the bronchoalveolar lavage fluid of nicotine-exposed mice, current smokers, and asthmatic children. Nicotine increased NGF secretion in lung fibroblasts in vitro in a dose-dependent manner and stimulated NFκB nuclear translocation, p65 binding to the NGF promoter, and NFκB transcriptional activity. These responses were attenuated in α7 nAChR deficient fibroblasts and in wild type fibroblasts following NFκB inhibition. Nicotine-treated, fibroblast-conditioned media increased expression of contractile proteins in ASM cells.

CONCLUSION

Nicotine stimulates NGF release by lung fibroblasts through α7 nAChR and NFκB dependent pathways. These novel findings suggest that the nicotine-α7 nAChR-NFκB- NGF axis may provide novel therapeutic targets to attenuate tobacco smoke-induced AHR.

[Salvianolic acid B inhibits ERK signal transduction pathway activated by transforming growth factor-β1 in rat hepatic stellate cells]

OBJECTIVE

To investigate the effects of salvianolic acid B (SA-B) on extracellular signal-regulated kinase (ERK) signal transduction pathway activated by transforming growth factor-β1 (TGF-β1) in rat hepatic stellate cells (HSCs).

METHODS

HSCs were isolated from male Sprague-Dawley rats by in situ perfusion and Nycodenz density-gradient centrifugation method. TGF-β1 and SA-B were directly added to the serum-free medium of HSCs. Total and phosphorylated ERK, MEK, Raf and α-smooth muscle actin (α-SMA) and type I collagen were assayed by Western blotting.

RESULTS

Phosphorylation of MEK in HSCs with or without TGF-β1 was inhibited by SA-B; however, phosphorylation of Raf in HSCs with or without TGF-β1 was not inhibited by SA-B. Expression of α-SMA in HSCs with TGF-β1 was inhibited by SA-B. Combination of SA-B and the inhibitors of ERK (PD98059) can effectively inhibit the expression of α-SMA. SA-B also inhibited synthesization of type I collagen in HSCs with or without TGF-β1.

CONCLUSION

The action point of SA-B inhibiting ERK signaling induced by TGF-β1 in HSCs is the inhibition of the phosphorylation of MEK. SA-B reduces the increase of expression of α-SMA and protein synthesization of type I collagen induced by TGF-β1 by means of inhibiting ERK signaling in activated HSCs of rats.

Inhibition of α-SMA by the ectodomain of FGFR2c attenuates lung fibrosis

The soluble ectodomain of fibroblast growth factor receptor-IIIc (sFGFR2c) is able to bind to fibroblast growth factor (FGF) ligands and block the activation of the FGF-signaling pathway. In this study, sFGFR2c inhibited lung fibrosis dramatically in vitro and in vivo. The upregulation of α-smooth muscle actin (α-SMA) in fibroblasts by transforming growth factor-β1 (TGF-β1) is an important step in the process of lung fibrosis, in which FGF-2, released by TGF-β1, is involved. sFGFR2c inhibited α-SMA induction by TGF-β1 via both the extracellular signal-regulated kinase 1/2 (ERK1/2) and Smad3 pathways in primary mouse lung fibroblasts and the proliferation of mouse lung fibroblasts. In a mouse model of bleomycin (BLM)-induced lung fibrosis, mice were treated with sFGFR2c from d 3 or d 10 to 31 after BLM administration. Then we used hematoxylin and eosin staining, Masson staining and immunohistochemical staining to evaluate the inhibitory effects of sFGFR2c on lung fibrosis. The treatment with sFGFR2c resulted in significant attenuation of the lung fibrosis score and collagen deposition. The expression levels of α-SMA, p-FGFRs, p-ERK1/2 and p-Smad3 in the lungs of sFGFR2c-treated mice were markedly lower. sFGFR2c may have potential for the treatment of lung fibrosis as an FGF-2 antagonist.

miR-31 is a negative regulator of fibrogenesis and pulmonary fibrosis

Aberrant expression of miRNAs is closely associated with initiation and progression of pathological processes, including diabetes, cancer, and cardiovascular disease. However, the role of miRNAs in lung fibrosis is not well characterized. We sought to determine the role of miR-31 in regulating the fibrogenic, contractile, and migratory activities of lung fibroblasts and modulating of pulmonary fibrosis in vivo. In vivo lung fibrosis models and ex vivo cell culture systems were employed. Real-time PCR and Western blot analysis were used to determine gene expression levels. miR-31 mimics or inhibitors were transfected into pulmonary fibroblasts. Fibrogenic, contractile, and migratory activities of lung fibroblasts were determined. We found that miR-31 expression is reduced in the lungs of mice with experimental pulmonary fibrosis and in IPF fibroblasts. miR-31 inhibits the profibrotic activity of TGF-β1 in normal lung fibroblasts and diminishes the fibrogenic, contractile, and migratory activities of IPF fibroblasts. In these experiments, miR-31 was shown to directly target integrin α(5) and RhoA, two proteins that have been shown to regulate activation of fibroblasts. We found that levels of integrin α(5) and RhoA are up-regulated in fibrotic mouse lungs. Knockdown of integrin α(5) and RhoA attenuated fibrogenic, contractile, and migratory activities of IPF fibroblasts, in a manner similar to that observed with miR-31. We also found that introduction of miR-31 ameliorated experimental lung fibrosis in mice. Our data suggest that miR-31 is an important regulator of the pathological activities of lung fibroblasts and may be a potential target in the development of novel therapies to treat pathological fibrotic disorders, including pulmonary fibrosis.

Radiation damage and radioprotectants: new concepts in the era of molecular medicine

Exposure to ionising radiation results in mutagenesis and cell death, and the clinical manifestations depend on the dose and the involved body area. Reducing carcinogenesis in patients treated with radiotherapy, exposed to diagnostic radiation or who are in certain professional groups is mandatory. The prevention or treatment of early and late radiotherapy effects would improve quality of life and increase cancer curability by intensifying therapies. Experimental and clinical data have given rise to new concepts and a large pool of chemical and molecular agents that could be effective in the protection and treatment of radiation damage. To date, amifostine is the only drug recommended as an effective radioprotectant. This review identifies five distinct types of radiation damage (I, cellular depletion; II, reactive gene activation; III, tissue disorganisation; IV, stochastic effects; V, bystander effects) and classifies the radioprotective agents into five relevant categories (A, protectants against all types of radiation effects; B, death pathway modulators; C, blockers of inflammation, chemotaxis and autocrine/paracrine pathways; D, antimutagenic keepers of genomic integrity; E, agents that block bystander effects). The necessity of establishing and funding central committees that guide systematic clinical research into evaluating the novel agents revealed in the era of molecular medicine is stressed.

Conditioned media from lung cancer cell line A549 and PC9 inactivate pulmonary fibroblasts by regulating protein phosphorylation

Pulmonary fibrosis is a devastating condition resulting from excess extracellular matrix deposition that leads to progressive lung destruction and scarring. In the pathogenesis of fibrotic diseases, activation of myofibroblasts by transforming growth factor-β (TGF-β) plays a crucial role. Since no effective therapy for pulmonary fibrosis is currently recognized, finding an effective antifibrotic agent is an important objective. One approach might be through identification of agents that inactivate myofibroblasts. In the current study we examined the potential of conditioned medium obtained from several types of cells to exhibit myofibroblast inactivating activity. Conditioned media from lung cancer cell lines A549 and PC9 were found to have this action, as shown by its ability to decrease α-smooth muscle actin expression in MRC-5 cells. Subsequently the inhibitory factor was purified from the medium and identified as 5'-deoxy-5'-methylthioadenosine (MTA), and its mechanism of action elucidated. Activation of protein kinase A and cAMP responsive element binding protein (CREB) were detected. MTA inhibited TGF-β-induced mitogen-activated protein kinase activation. Furthermore, the gain-of-function mutant CREB caused inactivation of myofibroblasts. These results show that A549 and PC9 conditioned media have the ability to inactivate myofibroblasts, and that CREB-phosphorylation plays a central role in this process.

Participation of miR-200 in pulmonary fibrosis

Excessive extracellular matrix production by fibroblasts in response to tissue injury contributes to fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF). Epithelial-mesenchymal transition, involving transition of alveolar epithelial cells (AECs) to pulmonary fibroblasts, appears to be an important contributory process to lung fibrosis. Although aberrant expression of microRNAs (miRs) is involved in a variety of pathophysiologic processes, the role of miRs in fibrotic lung diseases is less well understood. In the present study, we found that miR-200a, miR-200b, and miR-200c are significantly down-regulated in the lungs of mice with experimental lung fibrosis. Levels of miR-200a and miR-200c were reduced in the lungs of patients with IPF. miR-200 had greater expression in AECs than in lung fibroblasts, and AECs from mice with experimental pulmonary fibrosis had diminished expression of miR-200. We found that the miR-200 family members inhibit transforming growth factor-β1-induced epithelial-mesenchymal transition of AECs. miR-200 family members can reverse the fibrogenic activity of pulmonary fibroblasts from mice with experimental pulmonary fibrosis and from patients with IPF. Indeed, the introduction of miR-200c diminishes experimental pulmonary fibrosis in mice. Thus, the miR-200 family members participate importantly in fibrotic lung diseases and suggest that restoring miR-200 expression in the lungs may represent a novel therapeutic approach in treating pulmonary fibrotic diseases.

Characterization of ERK activation in human mast cells stimulated by contact with T cells

Close physical proximity between mast cells and T cells has been demonstrated in several human conditions. We have identified and characterized a novel mast cell activation pathway initiated by contact with T cells, and showed that this pathway is associated with cytokine release. It has been shown recently that Ras is activated in this pathway. Thus, in the present study we further explore the downstream events associated with Ras activation and cytokine release in human mast cells stimulated by contact with T cells. ERK activation in human mast cells stimulated by either contact with T cells or by crosslinking the FC epsilon receptor was studied. Photobleaching experiments were used to study ERK localization. Enzyme linked immunosorbent assay was used to study the cytokine release by human mast cells. We show that stimulation of human mast cells by contact with activated T cells results is sustained ERK activation. Furthermore, sustained ERK activation in these cells is associated with increased dwell time at the nucleus and with IL-8 release. Interestingly, when mast cells were stimulated by crosslinking the FC epsilon receptor I, ERK activation was transient. ERK activation was associated with a shorter dwell time at the nucleus and with TNF-alpha release. Thus, retaining ERK in the nucleus might be a mechanism utilized by human mast cells to generate different cytokines from a single signaling cascade.

Focal adhesion kinase (FAK)-related non-kinase inhibits myofibroblast differentiation through differential MAPK activation in a FAK-dependent manner

Transforming growth factor (TGF)-beta1 induces fibroblast transdifferentiation to myofibroblasts, a process that requires the involvement of integrin-mediated signaling and focal adhesion kinase (FAK). FAK-related non-kinase (FRNK) is known for its role in inhibiting integrin-mediated cell migration; however, its role in myofibroblast differentiation has not been defined. Here, we report that FRNK abrogates TGF-beta1-induced myofibroblast differentiation in vitro and in vivo. TGF-beta1 can induce alpha-smooth muscle actin (alpha-SMA) expression in the presence or absence of FAK; however, TGF-beta1-induced alpha-SMA expression is reduced (approximately 73%) in FAK-deficient fibroblasts. Although both ERK and p38 MAPK activation is required for maximal TGF-beta1-induced alpha-SMA expression, ERK is the major signaling intermediate in cells that express FAK. In contrast, p38 MAPK is the dominant mediator of TGF-beta1-induced alpha-SMA expression in FAK-deficient cells. FRNK overexpression blocks TGF-beta1-induced ERK or p38 MAPK activation in the presence, and surprisingly, in the absence of FAK. The loss of FRNK was tested in vivo during experimentally induced pulmonary fibrosis in mice. FRNK knock-out mice have a greater increase in alpha-SMA-expressing cells in response to a pulmonary fibrotic stimulus in vivo, as compared with congenic wild type mice. This is the first time that FRNK loss has been shown to modify the pathobiology in any animal disease model. Together, the data demonstrate that FRNK negatively regulates myofibroblast differentiation in vitro and in vivo. These data further suggest that modulation FRNK expression may be a novel avenue for therapeutic intervention in tissue fibrosis.

Factors released from cholestatic rat livers possibly involved in inducing bone marrow hepatic stem cell priming

Previous studies have shown that bone marrow beta 2m(-)/Thy-1+ hepatic stem cells (BMHSCs) were able to engraft in vivo and differentiate into functioning hepatocytes in vitro. Our transcriptomic profiling on BMHSCs derived from rats subjected to common bile duct ligation (CBDL) demonstrated CBDL-derived beta 2m(-)/Thy-1+ BMHSCs expressed hepatocyte-like genes and shared more commonly expressed genes with hepatocytes, suggesting that an "on-site" priming of BMHSCs into hepatocyte lineage was initiated under the condition of CBDL. In this paper, transcriptomic profiling was carried out on livers from rats with CBDL to identify candidate factors released from cholestatic livers possibly involved in the priming of BMHSCs using Affymetrix Rat Genome U34A arrays. In CBDL rat livers, 1,091 probe sets were differentially expressed, of which 188 up-regulated probe sets were annotated as "extracellular" components. Gene ontology analysis showed many up-regulated genes belonged to cytokines, chemokines and growth factors, including Il1b, Il18, Ptn, Spp1, Grn, Ccl2, Cxcl1, Pf4, Tgfb, and Tgfb3. Cell differentiation and proliferation regulation factors such as Dmbt1, Efna1, Lgals1, Lep, Pmp2, and Gas6 were also induced in CBDL livers. Furthermore, many proteolysis and peptidolysis genes such as Mmp2, Mmp12, Mmp14, and Mmp23 were up-regulated in CBDL livers. Gene expression profiling showed that many cytokine-, chemokine-, growth factor- as well as certain extracellular protein-related genes were induced in CBDL livers, suggesting that these genes may be involved in hepatic BMHSCs priming.

Inhibition of NF-kappaB-dependent Bcl-xL expression by clusterin promotes albumin-induced tubular cell apoptosis

Apoptosis and inflammation, important contributors to the progression of chronic kidney disease, can be influenced by clusterin (a secreted glycoprotein that regulates apoptosis) and nuclear factor-kappaB (NF-kappaB, a transcription factor modifying the expression of inflammatory genes). We studied proteinuria-induced renal disease and its influence on clusterin-mediated apoptosis. Exposure of cultured mouse proximal tubule epithelial cells to bovine serum albumin (BSA) resulted in activation of NF-kappaB and activator protein-1 (AP-1) within hours followed by a decline in their activation, decreased activation of extracellular signal-regulated kinases (ERK1/2), decreased cell-associated antiapoptotic Bcl-xL protein but increased apoptosis. Clusterin progressively increased in the media over a 3 day period. Clusterin siRNA blocked protein production, increased NF-kappaB activation, and significantly increased cellular Bcl-xL protein, thereby reducing spontaneous and BSA-induced apoptosis. An siRNA to the NF-kappaB inhibitor IkappaBalpha had similar results. BSA-stimulated NF-kappaB activation reciprocally decreased AP-1 activity by preventing ERK1/2 phosphorylation. These in vitro studies suggest that clusterin inhibits NF-kappaB-mediated antiapoptotic effects by the apparent stabilization of IkappaBalpha switching from promoting inflammation to apoptosis during proteinuria.

Transforming growth factor-beta receptor antagonism attenuates myocardial fibrosis in mice with cardiac-restricted overexpression of tumor necrosis factor

The mechanisms that are responsible for the development of myocardial fibrosis in inflammatory cardiomyopathy are unknown. We have previously generated lines of transgenic mice with cardiac-restricted overexpression of tumor necrosis factor (MHCsTNF mice), a pro-inflammatory cytokine. The MHCsTNF mice develop a heart failure phenotype that is characterized by progressive myocardial fibrosis, as well as increased levels transforming growth factor-beta (TGF-beta)(mRNA and protein. In order to determine whether TGF-beta-mediated signaling was responsible for the myocardial fibrosis observed in the MHCsTNF mice, we treated MHCsTNF and littermate control mice from 4 to 12 weeks of age with a novel orally available TGF-beta receptor antagonist (NP-40208). At the time of terminal study, myocardial collagen content was determined using the picrosirius red technique, and left ventricular (LV) systolic and diastolic function were determined using the Langendorff method. Treatment with NP-40208 resulted in a significant (P < 0.05) 65% decrease in nuclear translocation of Smad 2/3, a significant (P < 0.05), decrease in the heart-weight to body-weight ratio from 6.5 to 5.7, a approximately 37% decrease in fibrillar collagen content (P < 0.01) and a significant (P < 0.05) decrease in the LV chamber stiffness by approximately 25% in the MHCsTNF mice when compared to diluent-treated controls. Treatment with NP-40208 had no discernable effect on LV systolic function, nor any effect on cardiac myocyte size or fetal gene expression in the MHCsTNF mice. Taken together, these observations suggest that sustained pro-inflammatory signaling in the adult heart is associated with a pro-fibrotic phenotype that arises, at least in part, from TGF-beta-mediated signaling, with resultant activation of Smad 2/3, leading to increased myocardial fibrosis and increased LV diastolic chamber stiffness.

Synergistic activation of extracellular signal-regulated kinase in human dermal fibroblasts by human telomerase reverse transcriptase and transforming growth factor-beta1

BACKGROUND

Human telomerase reverse transcriptase (hTERT) is primarily known for its ability to elongate telomeres for maintaining chromosomal integrity and delaying cellular senescence. Recently, hTERT has emerged as having a role in promoting cellular proliferation that is independent of telomere elongation. How hTERT elicits this novel function is a fundamental question in cell biology. Understanding this question may have therapeutic implications in regenerative medicine for patients with damaged organs or tissues, cardiovascular disorders, stroke, ischemic chronic wounds, and other ischemia-reperfusion injuries. Toward this end, we treated hTERT-transfected human dermal fibroblasts (HDFs) with transforming growth factor (TGF)-beta1 and investigated the activation of extracellular signal-regulated kinase (ERK) 1/2, vital mediators of cell proliferation.

MATERIALS AND METHODS

Primary HDFs were transfected with either recombinant adenovirus expressing hTERT (Ad-hTERT) or control adenovirus (Ad-NULL) and subsequently treated with TGF-beta1 (2 pg/mL). ERK 1/2 activation was determined by Western blotting using an antibody recognizing only activated ERK 1/2 that is dually phosphorylated at Thr(202) and Tyr(204). TGF-beta1, TGFbeta-RI, TGFbeta-RII, and Col1 A1 mRNA levels were analyzed by real-time PCR.

RESULTS

Ad-hTERT-transfected HDFs showed more than 7-fold up-regulation of phospho-ERK 1/2 over Ad-NULL-transfected HDFs upon TGF-beta1 treatment. The synergistic ERK 1/2 activation in Ad-hTERT-transfected HDFs occurred as early as 10 min and was sustained for at least 30 min after TGF-beta1 treatment. There were no statistically significant differences in TGF-beta1, TGFbeta-RI, TGFbeta-RII, and Col1 A1 mRNA levels between HDFs that were transfected with Ad-hTERT and those that were transfected with Ad-NULL after TGF-beta1 treatment.

CONCLUSIONS

hTERT and extremely low concentrations of TGF-beta1 (2 pg/mL) synergistically activate ERK 1/2 in HDFs by a mechanism that is independent of the autocrine TGF-beta1 loop.

Flashlamp pulsed-dye laser suppressed TGF-beta1 expression and proliferation in cultured keloid fibroblasts is mediated by MAPK pathway

BACKGROUND AND OBJECTIVES

Our previous clinical study indicated that transforming growth factor-beta1 (TGF-beta1) and mitogen-activated protein kinases (MAPK) are both involved in keloid regression following flashlamp pulsed-dye laser (PDL). To further characterize of this involvement, this work examined whether PDL suppression of TGF-beta1 expression was mediated through MAPK pathway in cultured keloid fibroblasts (KF).

STUDY DESIGN/MATERIALS AND METHODS

Primary culture of KF harvested from keloid patients received various dosages of PDL treatment in 585-nm wavelength. TGF-beta1 expressions in KF following various dosages of PDL were assessed. Additionally, MAPK pathway activities were studied using the PD98059 (an ERK inhibitor), SB203580 (a p38 kinase inhibitor), and SP600125 (a JNK inhibitor), to determine the role in keloid following PDL treatment. Activator protein-1 (AP-1), a transcription factor of TGF-beta, was analyzed by electrophoretic mobility shift assay (EMSA). Phosphorylated c-Jun, one of the components of AP-1, was also detected.

RESULTS

The observation results demonstrated that optimal dosages of PDL significantly suppressed KF proliferation and TGF-beta1 expression. EMSA study identified PDL downregulation of super-shift of AP-1. Three subtypes of MAPK cascades were augmented between 30 minutes and 4 hours following PDL treatment, particularly phosphorylation of ERK1/2 and p38. Pre-treatment with PD98059, SB203580, but not SP600125, markedly inhibited the downregulating effects of TGF-beta1 and phosphorylated c-Jun expression following PDL treatment.

CONCLUSION

PDL induced keloid regression is mediated by triggering MAPK cascades and blockade of AP-1 transcription and TGF-beta expression. Modulation of TGF-beta and MAPK interaction in keloids may provide specific targets for therapeutic intervention.

EGFR signaling is required for TGF-beta 1 mediated COX-2 induction in human bronchial epithelial cells

Cyclooxygenase-2 (COX-2) is a key enzyme in the production of prostaglandins and thromboxanes from free arachidonic acid. Increasing evidence suggests that COX-2 plays a role in tumorigenesis. A variety of stimuli induce COX-2 and it is overexpressed in many tumors, including non-small cell lung cancer (NSCLC). We studied the regulation of COX-2 expression in immortalized human bronchial epithelial cells (HBECs) by transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF) because these two growth factors are present in both the pulmonary milieu of those at risk for lung cancer as well as in the tumor microenvironment. EGF significantly enhanced TGF-beta1-mediated induction of COX-2 and corresponding prostaglandin E2 (PGE2) production. TGF-beta1 and EGF induced COX-2 at the transcriptional and post-transcriptional levels. EGF receptor (EGFR) inhibition, neutralizing antibody against amphiregulin, or mitogen-activated protein kinase kinase (MEK) inhibition blocked TGF-beta1-mediated COX-2 induction. COX-2 induction by TGF-beta1 depended upon Smad3 signaling and required the activity of EGFR or its downstream mediators. Autocrine amphiregulin signaling maintains EGFR in a constitutively active state in HBECs, allowing for COX-2 induction by TGF-beta1. Thus, EGFR ligands, which are abundant in the pulmonary microenvironment of those at risk for lung cancer, potentiate and are required for COX-2 induction by TGF-beta1 in HBEC. These findings emphasize the central role of EGFR signaling in COX-2 induction by TGF-beta1 and suggest that inhibition of EGFR signaling should be investigated further for lung cancer prevention.

Transforming growth factor-beta1 effects on endothelial monolayer permeability involve focal adhesion kinase/Src

Transforming growth factor (TGF)-beta1 activity has been shown to increase vascular endothelial barrier permeability, which is believed to precede several pathologic conditions, including pulmonary edema and vessel inflammation. In endothelial monolayers, TGF-beta1 increases permeability, and a number of studies have demonstrated the alteration of cell-cell contacts by TGF-beta1. We hypothesized that focal adhesion complexes also likely contribute to alterations in endothelial permeability. We examined early signal transduction events associated with rapid changes in monolayer permeability and the focal adhesion complex of bovine pulmonary artery endothelial cells. Western blotting revealed rapid tyrosine phosphorylation of focal adhesion kinase (FAK) and Src kinase in response to TGF-beta1; inhibition of both of these kinases using pp2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), ameliorates TGF-beta1-induced monolayer permeability. Activation of FAK/Src requires activation of the epidermal growth factor receptor downstream of the TGF-beta receptors, and is blocked by the epidermal growth factor receptor inhibitor AG1478. Immunohistochemistry showed that actin and the focal adhesion proteins paxillin, vinculin, and hydrogen peroxide-inducible clone-5 (Hic-5) are rearranged in response to TGF-beta1; these proteins are released from focal adhesion complexes. Rearrangement of paxillin and vinculin by TGF-beta1 is not blocked by the FAK/Src inhibitor, pp2, or by SB431542 inhibition of the TGF-beta type I receptor, anaplastic lymphoma kinase 5; however, pp1 (4-Amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), which inhibits both type I and type II TGF-beta receptors, does block paxillin and vinculin rearrangement. Hic-5 protein rearrangement requires FAK/Src activity. Together, these results suggest that TGF-beta1-induced monolayer permeability involves focal adhesion and cytoskeletal rearrangement through both FAK/Src-dependent and -independent pathways.

Proinflammatory effects of tumour necrosis factor-like weak inducer of apoptosis (TWEAK) on human gingival fibroblasts

Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of the TNF family, is a multi-functional cytokine that regulates cellular proliferation, angiogenesis, inflammation and apoptosis. In this study, we investigated TWEAK expression in periodontally diseased tissues and the effect of TWEAK on human gingival fibroblasts (HGF). Reverse transcription-polymerase chain reaction (RT-PCR) analysis and immunohistochemistry revealed that TWEAK and the TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14), mRNA and protein were expressed in periodontally diseased tissues. HGF expressed Fn14 and produced interleukin (IL)-8 and vascular endothelial growth factor (VEGF) production upon TWEAK stimulation in a dose-dependent manner. The IL-8 and VEGF production induced by TWEAK was augmented synergistically by simultaneous stimulation with transforming growth factor (TGF)-beta1 or IL-1beta. IL-1beta and TGF-beta1 enhanced Fn14 expression in a dose-dependent manner. Moreover, TWEAK induced intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression on HGF in a dose-dependent manner. The ICAM-1 expression induced by TWEAK was augmented by TGF-beta1. On the other hand, the TWEAK-induced VCAM-1 expression was inhibited by TGF-beta1. Phosphatidylinositol 3-kinase (PI3K) and nuclear factor-kappaB (NF-kappaB) inhibitor inhibit both ICAM-1 and VCAM-1 expression induced by TWEAK. However, mitogen-activated protein kinase (MEK) and c-Jun NH2-terminal kinase (JNK) inhibitor enhanced only VCAM-1 expression on HGF. These results suggest that TWEAK may be involved in the pathophysiology of periodontal disease. Moreover, in combination with IL-1beta or TGF-beta1, TWEAK may be related to the exacerbation of periodontal disease to induce proinflammatory cytokines and adherent molecules by HGF.