Gene expression during chemically induced liver fibrosis: effect of halofuginone on TGF-beta signaling

Acetaldehyde Dehydrogenase 2 Deficiency Aggravates Lung Fibrosis through Mitochondrial Dysfunction and Aging in Fibroblasts

Idiopathic pulmonary fibrosis, a fatal interstitial lung disease, is characterized by fibroblast activation and aberrant extracellular matrix accumulation. Effective therapeutic development is limited because of incomplete understanding of the mechanisms by which fibroblasts become aberrantly activated. Here, we show acetaldehyde dehydrogenase 2 (ALDH2) in fibroblasts as a potential therapeutic target for pulmonary fibrosis. A decrease in ALDH2 expression was observed in patients with idiopathic pulmonary fibrosis and bleomycin-treated mice. ALDH2 deficiency spontaneously induces collagen accumulation in the lungs of aged mice. Furthermore, young ALDH2 knockout mice exhibited exacerbated bleomycin-induced pulmonary fibrosis and increased mortality compared with that in control mice. Mechanistic studies revealed that transforming growth factor (TGF)-β1 induction and ALDH2 depletion constitute a positive feedback loop that exacerbates fibroblast activation. TGF-β1 down-regulated ALDH2 through a TGF-β receptor 1/Smad3-dependent mechanism. The subsequent deficiency in ALDH2 resulted in fibroblast dysfunction that manifested as impaired mitochondrial autophagy and senescence, leading to fibroblast activation and extracellular matrix production. ALDH2 overexpression markedly suppressed fibroblast activation, and this effect was abrogated by PTEN-induced putative kinase 1 (PINK1) knockdown, indicating that the profibrotic effects of ALDH2 are PINK1- dependent. Furthermore, Alda-1-induced ALDH2 activation reversed the established pulmonary fibrosis in both young and aged mice. In conclusion, ALDH2 expression inhibits the pathogenesis of pulmonary fibrosis. Strategies to up-regulate or activate ALDH2 expression could be potential therapies for pulmonary fibrosis.

Induction of ATF4-Regulated Atrogenes Is Uncoupled from Muscle Atrophy during Disuse in Halofuginone-Treated Mice and in Hibernating Brown Bears

Activating transcription factor 4 (ATF4) is involved in muscle atrophy through the overexpression of some atrogenes. However, it also controls the transcription of genes involved in muscle homeostasis maintenance. Here, we explored the effect of ATF4 activation by the pharmacological molecule halofuginone during hindlimb suspension (HS)-induced muscle atrophy. Firstly, we reported that periodic activation of ATF4-regulated atrogenes (Gadd45a, Cdkn1a, and Eif4ebp1) by halofuginone was not associated with muscle atrophy in healthy mice. Secondly, halofuginone-treated mice even showed reduced atrophy during HS, although the induction of the ATF4 pathway was identical to that in untreated HS mice. We further showed that halofuginone inhibited transforming growth factor-β (TGF-β) signalling, while promoting bone morphogenetic protein (BMP) signalling in healthy mice and slightly preserved protein synthesis during HS. Finally, ATF4-regulated atrogenes were also induced in the atrophy-resistant muscles of hibernating brown bears, in which we previously also reported concurrent TGF-β inhibition and BMP activation. Overall, we show that ATF4-induced atrogenes can be uncoupled from muscle atrophy. In addition, our data also indicate that halofuginone can control the TGF-β/BMP balance towards muscle mass maintenance. Whether halofuginone-induced BMP signalling can counteract the effect of ATF4-induced atrogenes needs to be further investigated and may open a new avenue to fight muscle atrophy. Finally, our study opens the way for further studies to identify well-tolerated chemical compounds in humans that are able to fine-tune the TGF-β/BMP balance and could be used to preserve muscle mass during catabolic situations.

Tartrate-resistant acid phosphatase 5 promotes pulmonary fibrosis by modulating β-catenin signaling

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with limited therapeutic options. Tartrate-resistant acid phosphatase 5 (ACP5) performs a variety of functions. However, its role in IPF remains unclear. Here, we demonstrate that the levels of ACP5 are increased in IPF patient samples and mice with bleomycin (BLM)-induced pulmonary fibrosis. In particular, higher levels of ACP5 are present in the sera of IPF patients with a diffusing capacity of the lungs for carbonmonoxide (DLCO) less than 40% of the predicted value. Additionally, Acp5 deficiency protects mice from BLM-induced lung injury and fibrosis coupled with a significant reduction of fibroblast differentiation and proliferation. Mechanistic studies reveal that Acp5 is upregulated by transforming growth factor-β1 (TGF-β1) in a TGF-β receptor 1 (TGFβR1)/Smad family member 3 (Smad3)-dependent manner, after which Acp5 dephosphorylates p-β-catenin at serine 33 and threonine 41, inhibiting the degradation of β-catenin and subsequently enhancing β-catenin signaling in the nucleus, which promotes the differentiation, proliferation and migration of fibroblast. More importantly, the treatment of mice with Acp5 siRNA-loaded liposomes or Acp5 inhibitor reverses established lung fibrosis. In conclusions, Acp5 is involved in the initiation and progression of pulmonary fibrosis and strategies aimed at silencing or suppressing Acp5 could be considered as potential therapeutic approaches against pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a fatal lung disease with limited treatment options. Here the authors show that tartrate-resistant acid phosphatase 5 (Acp5) promotes lung fibrosis by enhancing beta-catenin signaling and that inhibition of Acp5 can reverse stablished pulmonary fibrosis.

Halofuginone, a promising drug for treatment of pulmonary hypertension

BACKGROUND AND PURPOSE

Halofuginone is a febrifugine derivative originally isolated from Chinese traditional herb Chang Shan that exhibits anti-hypertrophic, anti-fibrotic and anti-proliferative effects. We sought to investigate whether halofuginone induced pulmonary vasodilation and attenuates chronic hypoxia-induced pulmonary hypertension (HPH).

EXPERIMENTAL APPROACH

Patch-clamp experiments were conducted to examine the activity of voltage-dependent Ca²⁺ channels (VDCCs) in pulmonary artery smooth muscle cells (PASMCs). Digital fluorescence microscopy was used to measure intracellular Ca²⁺ concentration in PASMCs. Isolated perfused and ventilated mouse lungs were used to measure pulmonary artery pressure (PAP). Mice exposed to hypoxia (10% O₂ ) for 4 weeks were used as model of HPH for in vivo experiments.

KEY RESULTS

Halofuginone increased voltage-gated K⁺ (K_v ) currents in PASMCs and K⁺ currents through KCNA5 channels in HEK cells transfected with KCNA5 gene. HF (0.03-1 μM) inhibited receptor-operated Ca²⁺ entry in HEK cells transfected with calcium-sensing receptor gene and attenuated store-operated Ca²⁺ entry in PASMCs. Acute (3-5 min) intrapulmonary application of halofuginone significantly and reversibly inhibited alveolar hypoxia-induced pulmonary vasoconstriction dose-dependently (0.1-10 μM). Intraperitoneal administration of halofuginone (0.3 mg·kg^-1 , for 2 weeks) partly reversed established PH in mice.

CONCLUSION AND IMPLICATIONS

Halofuginone is a potent pulmonary vasodilator by activating K_v channels and blocking VDCC and receptor-operated and store-operated Ca²⁺ channels in PASMCs. The therapeutic effect of halofuginone on experimental PH is probably due to combination of its vasodilator effects, via inhibition of excitation-contraction coupling and anti-proliferative effects, via inhibition of the PI3K/Akt/mTOR signalling pathway.

Halofuginone ameliorates inflammation in severe acute hepatitis B virus (HBV)-infected SD rats through AMPK activation

The hepatitis B virus (HBV) has caused acute and chronic liver diseases in ~350 million infected people worldwide. Halofuginone (HF) is a plant alkaloid which has been demonstrated to play a crucial role in immune regulation. Our present study explored the function of HF in the immune response of HBV-infected Sprague Dawley (SD) rats. Plasmid containing pCDNA3.1-HBV1.3 was injected in SD rats for the construction of an acute HBV-infected animal model. Our data showed that HF reduced the high concentrations of serum hepatitis B e-antigen, hepatitis B surface antigen, and HBV DNA induced by HBV infection. HF also reduced the number of T helper (Th)17 cells and the expression of interleukin (IL)-17 compared with the pCDNA3.1-HBV1.3 group. Moreover, pro-inflammatory cytokine levels (IL-17, IL-23, interferon-γ, and IL-2) were downregulated and anti-inflammatory cytokine levels (IL-4 and IL-13) were upregulated by HF. Through further research we found that the expression of AMP-activated protein kinase (AMPK) and IKBA which suppressed NF-κB activation was increased while the expression of p-NF-κB P65 was decreased in pCDNA3.1-HBV1.3+HF group compared with pCDNA3.1-HBV1.3 group, indicating that HF may work through the activation of AMPK. Finally, our conjecture was further verified by using the AMPK inhibitor compound C, which counteracted the anti-inflammation effect of HF, resulting in the decreased expression of AMPK, IKBA and increased expression of p-NF-κB P65 and reduced number of Th17 cells. In our present study, HF was considered as an anti-inflammatory factor in acute HBV-infected SD rats and worked through AMPK-mediated NF-κB p65 inactivation. This study implicated HF as a potential therapeutic strategy for hepatitis B.

Low‑dose halofuginone inhibits the synthesis of type I collagen without influencing type II collagen in the extracellular matrix of chondrocytes

Full‑thickness and large area defects of articular cartilage are unable to completely repair themselves and require surgical intervention, including microfracture, autologous or allogeneic osteochondral grafts, and autologous chondrocyte implantation. A large proportion of regenerative cartilage exists as fibrocartilage, which is unable to withstand impacts in the same way as native hyaline cartilage, owing to excess synthesis of type I collagen in the matrix. The present study demonstrated that low‑dose halofuginone (HF), a plant alkaloid isolated from Dichroa febrifuga, may inhibit the synthesis of type I collagen without influencing type II collagen in the extracellular matrix of chondrocytes. In addition, HF was revealed to inhibit the phosphorylation of mothers against decapentaplegic homolog (Smad)2/3 and promoted Smad7 expression, as well as decrease the synthesis of type I collagen synthesis. Results from the present study indicated that HF treatment suppressed the synthesis of type I collagen by inhibiting the transforming growth factor‑β signaling pathway in chondrocytes. These results may provide an alternative solution to the problems associated with fibrocartilage, and convert fibrocartilage into hyaline cartilage at the mid‑early stages of cartilage regeneration. HF may additionally be used to improve monolayer expansion or 3D cultures of seed cells for the tissue engineering of cartilage.

Response of an ovine laryngeal injury model to a novel fibrosis inhibitor

BACKGROUND

Vocal fold injury results in severe voice alteration that limits occupational function and social interaction. An ovine model of laryngeal injury has been developed, validated and utilized to examine laryngeal wound healing and the effect of a novel collagen inhibitor (halofuginone) on surgical wound healing. The study design includes basic research and animal model.

METHODS

An ovine laryngeal model was utilized to study controlled vocal fold injury and healing. Twenty-five sheep were divided into five groups. Sheep underwent right vocal fold injury preceded or followed by administration of halofuginone orally, topically or intralesionally. Biopsies were taken at commencement, 1 month and larynges explanted at 3 months. Specimens were examined for elastin and collagen density and epithelial changes. Pearson correlation statistics and Student's t-tests were used to assess inter-relationships.

RESULTS

All sheep tolerated halofuginone. One sheep death occurred in an untreated sheep. Vocal fold tissue demonstrated a predictable histological response to injury. Elastin was significantly reduced post-injury in the glottis. Halofuginone administered orally for 10 weeks prevented elastin loss and demonstrated a trend of reducing collagen density post-injury.

CONCLUSION

In an ovine laryngeal injury model, administration of a fibrosis inhibitor resulted in altered elastin and collagen deposition after injury in the glottis. Further investigation is warranted to examine whether these tissue changes affect vocal fold dynamics.

Halofuginone suppresses growth of human uterine leiomyoma cells in a mouse xenograft model

STUDY QUESTION

Does halofuginone (HF) inhibit the growth of human uterine leiomyoma cells in a mouse xenograft model?

SUMMARY ANSWER

HF suppresses the growth of human uterine leiomyoma cells in a mouse xenograft model through inhibiting cell proliferation and inducing apoptosis.

WHAT IS KNOWN ALREADY

Uterine leiomyomas are the most common benign tumors of the female reproductive tract. HF can suppress the growth of human uterine leiomyoma cells in vitro. The mouse xenograft model reflects the characteristics of human leiomyomas.

STUDY DESIGN, SIZE, DURATION

Primary leiomyoma smooth muscle cells from eight patients were xenografted under the renal capsule of adult, ovariectomized NOD-scid IL2Rγ(null) mice (NSG). Mice were treated with two different doses of HF or vehicle for 4 weeks with six to eight mice per group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mouse body weight measurements and immunohistochemical analysis of body organs were carried out to assess the safety of HF treatment. Xenografted tumors were measured and analyzed for cellular and molecular changes induced by HF. Ovarian steroid hormone receptors were evaluated for possible modulation by HF.

MAIN RESULTS AND THE ROLE OF CHANCE

Treatment of mice carrying human UL xenografts with HF at 0.25 or 0.50 mg/kg body weight for 4 weeks resulted in a 35-40% (P < 0.05) reduction in tumor volume. The HF-induced volume reduction was accompanied by increased apoptosis and decreased cell proliferation. In contrast, there was no significant change in the collagen content either at the transcript or protein level between UL xenografts in control and HF groups. HF treatment did not change the expression level of ovarian steroid hormone receptors. No adverse pathological effects were observed in other tissues from mice undergoing treatment at these doses.

LIMITATIONS, REASONS FOR CAUTION

While this study did test the effects of HF on human leiomyoma cells in an in vivo model, HF was administered to mice whose tolerance and metabolism of the drug may differ from that in humans. Also, the longer term effects of HF treatment are yet unclear.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study showing the effectiveness of HF in reducing UL tumor growth by interfering with the main cellular processes regulating cell proliferation and apoptosis are in agreement with previous studies on the effects of HF on other fibrotic diseases. HF can be considered as a candidate for reducing the size of leiomyomas, particularly prior to surgery.

STUDY FUNDING/COMPETING INTERESTS

This project was funded by NIH PO1HD057877 and R01 HD064402. Authors report no competing interests.

Halofuginone alleviates acute viral myocarditis in suckling BALB/c mice by inhibiting TGF-β1

Viral myocarditis (VMC) is an inflammation of heart muscle in infants and young adolescents. This study explored the function of halofuginone (HF) in Coxsackievirus B3 (CVB3) -treated suckling mice. HF-treated animal exhibited higher survival rate, lower heart/body weight, and more decreased blood sugar concentration than CVB3 group. HF also reduced the expressions of interleukin(IL)-17 and IL-23 and the numbers of Th17 cells. Moreover, HF downregulated pro-inflammatory cytokine levels and increased anti-inflammatory cytokine levels. The expressions of transforming growth factor(TGF-β1) and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) p65/ tumor necrosis factor-α (TNF-α) proteins were decreased by HF as well. Finally, the overexpression of TGF-β1 counteracted the protection effect of HF in CVB3-treated suckling mice. In summary, our study suggests HF increases the survival of CVB3 suckling mice, reduces the Th17 cells and pro-inflammatory cytokine levels, and may through downregulation of the TGF-β1-mediated expression of NF-κB p65/TNF-α pathway proteins. These results offer a potential therapeutic strategy for the treatment of VMC.

Cytoglobin as a Marker of Hepatic Stellate Cell-derived Myofibroblasts

Myofibroblasts play important roles in inflammation, fibrosis and tumorigenesis in chronically inflamed liver. Liver myofibroblasts originate from hepatic stellate cells, portal fibroblasts or mesothelial cells, and they are localized in and around fibrotic septum and portal tracts. Liver myofibroblasts are the source of extracellular matrix materials, including type I collagen and multiple fibrogenic growth factors, such as transforming growth factor-β and vascular endothelial growth factor. Although a detailed characterization of the function of individual myofibroblasts has not been conducted, owing to the lack of appropriate cell markers, recent lineage-tracing technology has revealed the limited contribution of myofibroblasts that are derived from portal fibroblasts to various types of liver fibrosis, as compared with the contribution of hepatic stellate cells. In addition, cytoglobin, which is the fourth globin in mammals and function as a local gas sensor, provides a new perspective on the involvement of stellate cells in fibrosis and carcinogenesis, possibly through its anti-oxidative properties and is a promising new marker that discriminates between myofibroblasts derived from stellate cells and those from portal fibroblasts.

Halofuginone attenuates osteoarthritis by inhibition of TGF-β activity and H-type vessel formation in subchondral bone

Objectives

Examine whether osteoarthritis (OA) progression can be delayed by halofuginone in anterior cruciate ligament transection (ACLT) rodent models.

Methods

3-month-old male C57BL/6J (wild type; WT) mice and Lewis rats were randomised to sham-operated, ACLT-operated, treated with vehicle, or ACLT-operated, treated with halofuginone. Articular cartilage degeneration was graded using the Osteoarthritis Research Society International (OARSI)-modified Mankin criteria. Immunostaining, flow cytometry, RT-PCR and western blot analyses were conducted to detect relative protein and RNA expression. Bone micro CT (μCT) and CT-based microangiography were quantitated to detect alterations of microarchitecture and vasculature in tibial subchondral bone.

Results

Halofuginone attenuated articular cartilage degeneration and subchondral bone deterioration, resulting in substantially lower OARSI scores. Specifically, we found that proteoglycan loss and calcification of articular cartilage were significantly decreased in halofuginone-treated ACLT rodents compared with vehicle-treated ACLT controls. Halofuginone reduced collagen X (Col X), matrix metalloproteinase-13 and A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS 5) and increased lubricin, collagen II and aggrecan. In parallel, halofuginone-attenuated uncoupled subchondral bone remodelling as defined by reduced subchondral bone tissue volume, lower trabecular pattern factor (Tb.pf) and increased thickness of subchondral bone plate compared with vehicle-treated ACLT controls. We found that halofuginone exerted protective effects in part by suppressing Th17-induced osteoclastic bone resorption, inhibiting Smad2/3-dependent TGF-β signalling to restore coupled bone remodelling and attenuating excessive angiogenesis in subchondral bone.

Conclusions

Halofuginone attenuates OA progression by inhibition of subchondral bone TGF-β activity and aberrant angiogenesis as a potential preventive therapy for OA.

Halofuginone - the multifaceted molecule

Halofuginone is an analog of febrifugine-an alkaloid originally isolated from the plant Dichroa febrifuga. During recent years, halofuginone has attracted much attention because of its wide range of beneficial biological activities, which encompass malaria, cancer, and fibrosis-related and autoimmune diseases. At present two modes of halofuginone actions have been described: (1) Inhibition of Smad3 phosphorylation downstream of the TGFβ signaling pathway results in inhibition of fibroblasts-to-myofibroblasts transition and fibrosis. (2) Inhibition of prolyl-tRNA synthetase (ProRS) activity in the blood stage of malaria and inhibition of Th17 cell differentiation thereby inhibiting inflammation and the autoimmune reaction by activation of the amino acid starvation and integrated stress responses. This review deals with the history and origin of this natural product, its synthesis, its known modes of action, and it's various biological activities in pre-clinical animal models and in humans.

The mitochondrial cardiolipin remodeling enzyme lysocardiolipin acyltransferase is a novel target in pulmonary fibrosis

RATIONALE

Lysocardiolipin acyltransferase (LYCAT), a cardiolipin-remodeling enzyme regulating the 18:2 linoleic acid pattern of mammalian mitochondrial cardiolipin, is necessary for maintaining normal mitochondrial function and vascular development. We hypothesized that modulation of LYCAT expression in lung epithelium regulates development of pulmonary fibrosis.

OBJECTIVES

To define a role for LYCAT in human and murine models of pulmonary fibrosis.

METHODS

We analyzed the correlation of LYCAT expression in peripheral blood mononuclear cells (PBMCs) with the outcomes of pulmonary functions and overall survival, and used the murine models to establish the role of LYCAT in fibrogenesis. We studied the LYCAT action on cardiolipin remodeling, mitochondrial reactive oxygen species generation, and apoptosis of alveolar epithelial cells under bleomycin challenge.

MEASUREMENTS AND MAIN RESULTS

LYCAT expression was significantly altered in PBMCs and lung tissues from patients with idiopathic pulmonary fibrosis (IPF), which was confirmed in two preclinical murine models of IPF, bleomycin- and radiation-induced pulmonary fibrosis. LYCAT mRNA expression in PBMCs directly and significantly correlated with carbon monoxide diffusion capacity, pulmonary function outcomes, and overall survival. In both bleomycin- and radiation-induced pulmonary fibrosis murine models, hLYCAT overexpression reduced several indices of lung fibrosis, whereas down-regulation of native LYCAT expression by siRNA accentuated fibrogenesis. In vitro studies demonstrated that LYCAT modulated bleomycin-induced cardiolipin remodeling, mitochondrial membrane potential, reactive oxygen species generation, and apoptosis of alveolar epithelial cells, potential mechanisms of LYCAT-mediated lung protection.

CONCLUSIONS

This study is the first to identify modulation of LYCAT expression in fibrotic lungs and offers a novel therapeutic approach for ameliorating lung inflammation and pulmonary fibrosis.

The chemistry and biology of febrifugine and halofuginone

The trans-2,3-disubstituted piperidine, quinazolinone-containing natural product febrifugine (also known as dichroine B) and its synthetic analogue, halofuginone, possess antimalarial activity. More recently studies have also shown that halofuginone acts as an agent capable of reducing fibrosis, an indication with clinical relevance for several disease states. This review summarizes historical isolation studies and the chemistry performed which culminated in the correct structural elucidation of naturally occurring febrifugine and its isomer isofebrifugine. It also includes the range of febrifugine analogues prepared for antimalarial evaluation, including halofuginone. Finally, a section detailing current opinion in the field of halofuginone's human biology is included.

Targeting TGFβ signaling to inhibit fibroblast activation as a therapy for fibrosis and cancer: effect of halofuginone

The fibroblast to myofibroblast transition in wound healing, fibrosis and cancer has emerged as a viable target for pharmacological intervention. The myofibroblasts acquire specific characteristics because of differences in origin and localization, but also share common properties, such as TGFβ signaling. Halofuginone, an inhibitor of the Smad3 phosphorylation, downstream of the TGFβ signaling, inhibits the activation of fibroblasts and their ability to synthesize the extracellular matrix, regardless of their origin or location. Halofuginone prevented the new and stimulated resolution of pre-existing fibrosis of several organs and inhibited the development and progression of various tumors. Moreover, halofuginone synergizes with chemotherapy and reduces the need for high doses of toxic compounds without impairing the treatment efficacy. In fibrosis, where the myofibroblasts are the major participant, halofuginone can be used as a single therapy, whereas in cancer it should be considered in combination with other therapies that affect the tumor cells via different modalities.

The involvement of collagen triple helix repeat containing 1 in muscular dystrophies

Fibrosis is the main complication of muscular dystrophies. We identified collagen triple helix repeat containing 1 (Cthrc1) in skeletal and cardiac muscles of mice, representing Duchenne and congenital muscle dystrophies (DMD and CMD, respectively), and dysferlinopathy. In all of the mice, Cthrc1 was associated with high collagen type I levels; no Cthrc1 or collagen was observed in muscles of control mice. High levels of Cthrc1 were also observed in biopsy specimens from patients with DMD, in whom they were reversibly correlated with that of β-dystroglycan, whereas collagen type I levels were elevated in all patients with DMD. At the muscle sites where collagen and Cthrc1 were adjacent, collagen fibers appeared smaller, suggesting involvement of Cthrc1 in collagen turnover. Halofuginone, an inhibitor of Smad3 phosphorylation downstream of the transforming growth factor-β signaling, reduced Cthrc1 levels in skeletal and cardiac muscles of mice, representing DMD, CMD, and dysferlinopathy. The myofibroblasts infiltrating the dystrophic muscles of the murine models of DMD, CMD, and dysferlinopathy were the source of Cthrc1. Transforming growth factor-β did not affect Cthrc1 levels in the mdx fibroblasts but decreased them in the control fibroblasts, in association with increased migration of mdx fibroblasts and dystrophic muscle invasion by myofibroblasts. To our knowledge, this is the first demonstration of Cthrc1 as a marker of the severity of the disease progression in the dystrophic muscles, and as a possible target for therapy.

Involvement of host stroma cells and tissue fibrosis in pancreatic tumor development in transgenic mice

Introduction

Stroma cells and extracellular matrix (ECM) components provide the pivotal microenvironment for tumor development. The study aimed to evaluate the importance of the pancreatic stroma for tumor development.

Methods

Pancreatic tumor cells were implanted subcutaneously into green fluorescent protein transgenic mice, and stroma cells invading the tumors were identified through immunohistochemistry. Inhibition of tumor invasion by stroma cells was achieved with halofuginone, an inhibitor of TGFβ/Smad3 signaling, alone or in combination with chemotherapy. The origin of tumor ECM was evaluated with species-specific collagen I antibodies and in situ hybridization of collagen α1(I) gene. Pancreatic fibrosis was induced by cerulean injection and tumors by spleen injection of pancreatic tumor cells.

Results

Inhibition of stroma cell infiltration and reduction of tumor ECM levels by halofuginone inhibited development of tumors derived from mouse and human pancreatic cancer cells. Halofuginone reduced the number only of stroma myofibroblasts expressing both contractile and collagen biosynthesis markers. Both stroma myofibroblasts and tumor cells generated ECM that contributes to tumor growth. Combination of treatments that inhibit stroma cell infiltration, cause apoptosis of myofibroblasts and inhibit Smad3 phosphorylation, with chemotherapy that increases tumor-cell apoptosis without affecting Smad3 phosphorylation was more efficacious than either treatment alone. More tumors developed in fibrotic than in normal pancreas, and prevention of tissue fibrosis greatly reduced tumor development.

Conclusions

The utmost importance of tissue fibrosis and of stroma cells for tumor development presents potential new therapy targets, suggesting combination therapy against stroma and neoplastic cells as a treatment of choice.

Cytoglobin: biochemical, functional and clinical perspective of the newest member of the globin family

Since the discovery of cytoglobin (Cygb) a decade ago, growing amounts of data have been gathered to characterise Cygb biochemistry, functioning and implication in human pathologies. Its molecular roles remain under investigation, but nitric oxide dioxygenase and lipid peroxidase activities have been demonstrated. Cygb expression increases in response to various stress conditions including hypoxia, oxidative stress and fibrotic stimulation. When exogenously overexpressed, Cygb revealed cytoprotection against these factors. Cygb was shown to be upregulated in fibrosis and neurodegenerative disorders and downregulated in multiple cancer types. CYGB was also found within the minimal region of a hereditary tylosis with oesophageal cancer syndrome, and its expression was reduced in tylotic samples. Recently, Cygb has been shown to inhibit cancer cell growth in vitro, thus confirming its suggested tumour suppressor role. This article aims to review the biochemical and functional aspects of Cygb, its involvement in various pathological conditions and potential clinical utility.

Targeting the tumor microenvironment by immunotherapy: part 2

Cancer therapy was traditionally centered on the neoplastic cells. This included mainly surgery, radiation, and chemotherapy, in some cases hormone therapy and to a lesser extent immunotherapy – all traditionally targeted to the highly proliferating mutated tumor cells. In view of our present understanding of the powerfull influence of the tumor microenvironment (TME) on cancer behavior and response – and lack of response – to treatment, this previously ignored constituent of cancer now has to be considered as an important, even indispensable target for therapy. The TME may be targeted both to its immune and to its nonimmune components. The various immune evasion elements of the TME should be targeted as well.

Halofuginone has anti-proliferative effects in acute promyelocytic leukemia by modulating the transforming growth factor beta signaling pathway

Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα) expression in acute promyelocytic leukemia (APL) impairs transforming growth factor beta (TGFβ) signaling, leading to cell growth advantage. Halofuginone (HF), a low-molecular-weight alkaloid that modulates TGFβ signaling, was used to treat APL cell lines and non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice subjected to transplantation with leukemic cells from human chorionic gonadotrophin-PML-RARα transgenic mice (TG). Cell cycle analysis using incorporated bromodeoxyuridine and 7-amino-actinomycin D showed that, in NB4 and NB4-R2 APL cell lines, HF inhibited cellular proliferation (P<0.001) and induced apoptosis (P = 0.002) after a 24-hour incubation. Addition of TGFβ revealed that NB4 cells were resistant to its growth-suppressive effects and that HF induced these effects in the presence or absence of the cytokine. Cell growth inhibition was associated with up-regulation of TGFβ target genes involved in cell cycle regulation (TGFB, TGFBRI, SMAD3, p15, and p21) and down-regulation of MYC. Additionally, TGFβ protein levels were decreased in leukemic TG animals and HF in vivo could restore TGFβ values to normal. To test the in vivo anti-leukemic activity of HF, we transplanted NOD/SCID mice with TG leukemic cells and treated them with HF for 21 days. HF induced partial hematological remission in the peripheral blood, bone marrow, and spleen. Together, these results suggest that HF has anti-proliferative and anti-leukemic effects by reversing the TGFβ blockade in APL. Since loss of the TGFβ response in leukemic cells may be an important second oncogenic hit, modulation of TGFβ signaling may be of therapeutic interest.

Microarray profiling reveals the integrated stress response is activated by halofuginone in mammary epithelial cells

BACKGROUND

The small molecule Halofuginone (HF) is a potent regulator of extracellular matrix (ECM ) gene expression and is unique in its therapeutic potential. While the basis for HF effects is unknown, inhibition of TGFβ signaling and activation of the amino acid restriction response (AAR) have been linked to HF transcriptional control of a number of ECM components and amelioration of fibrosis and alleviation of autoimmune disease by regulation of Th17 cell differentiation, respectively. The aim of this study was to generate a global expression profile of HF targets in epithelial cells to identify potential mediators of HF function in this cell type.

RESULTS

We report that HF modulation of the expression of the ECM remodeling protein Mmp13 in epithelial cells is separable from previously reported effects of HF on TGFβ signal inhibition, and use microarray expression analysis to correlate this with transcriptional responses characteristic of the Integrated Stress Response (ISR).

CONCLUSIONS

Our findings suggest activation of the ISR may be a common mechanism underlying HF biological effects.

S-Nitroso-N-acetylcysteine induces de-differentiation of activated hepatic stellate cells and promotes antifibrotic effects in vitro

Nitric oxide (NO) has been shown to act as a potent antifibrogenic agent by decreasing myofibroblast differentiation. S-Nitroso-N-acetylcysteine (SNAC), a NO donor, attenuates liver fibrosis in rats, but the cellular and molecular mechanisms on liver myofibroblast-like phenotype still remain unknown. Here, we investigate the antifibrotic effects of SNAC on hepatic stellate cells, the major fibrogenic cell type in the liver. A murine GRX cell line was incubated with SNAC (100μM) or vehicle (control group) for 72h. Cell viability was measured by MTT colorimetric assay and the conversion of myofibroblast into quiescent fat-storing cell phenotype was evaluated by Oil-Red-O staining. TGFβ-1, TIMP-1, and MMP-13 levels were measure in the supernatant by ELISA. Profibrogenic- and fibrolytic-related gene expression was quantified using real-time qPCR. SNAC induced phenotype conversion of myofibroblast-like phenotype into quiescent cells. SNAC decreased gene and protein expression of TGFβ-1 and MMP-2 compared to control groups. Besides, SNAC down-regulated profibrogenic molecules and up-regulated MMP-13 gene expression, which plays a key role in the degradation of interstitial collagen in liver fibrosis. In conclusion, these findings demonstrate that SNAC efficiently can modulate the activation and functionality of murine hepatic stellate cells and could be considered as an antifibrotic treatment to human liver fibrosis.

Phase II AIDS Malignancy Consortium trial of topical halofuginone in AIDS-related Kaposi sarcoma

Using a novel blinded intrapatient vehicle control design, we conducted a phase II study of topically administered halofuginone, an angiogenesis inhibitor that inhibits collagen type-I and matrix metalloproteinases (MMPs), in patients with AIDS-related Kaposi sarcoma. Serial Kaposi sarcoma biopsies assessed treatment effects on angiogenic factors and Kaposi sarcoma herpesvirus-latency associated nuclear antigen-1 (KSHV-LANA). We observed marked heterogeneity of KSHV-LANA expression. Although the small number of subjects whose response could be evaluated precluded definitive assessment of halofuginone's efficacy, we observed a significant decrease in type-I collagen only in halofuginone-treated lesions, but no effect on MMP-2. The trial design is applicable to future studies of topical agents.

Inhibition of pancreatic stellate cell activation by halofuginone prevents pancreatic xenograft tumor development

OBJECTIVES

Most solid tumors consist of neoplastic and nonneoplastic cells and extracellular matrix components. In the pancreas, activated stellate cells (PSCs) are the source of the extracellular matrix proteins. We evaluated the significance of PSC activation in tumor establishment and development in mouse xenografts.

METHODS

Xenografts were established by implanting human pancreatic cancer cells (MiaPaca-2) subcutaneously or orthotopically by injecting them into the spleen. Fibrosis was induced by cerulein. Collagen level was evaluated by Sirius red staining. Prolyl 4-hydroxylase β and stellate cell activation-associated protein (Cygb/STAP) were determined by immunohistochemistry.

RESULTS

Halofuginone inhibited subcutaneous tumor development implanted with Matrigel and reduced collagen and prolyl 4-hydroxylase β levels. Few tumors, which developed slowly, were observed after MiaPaca-2 implantation without Matrigel. Increase in tumor number and rate of development were observed with addition of PSCs from control pancreas, and further increase was observed when the PSCs were from cerulein-treated mice. Preincubation of the PSCs with halofuginone elicited Cygb/STAP level reduction and tumor growth inhibition. More tumors developed orthotopically in cerulein-treated mice than in controls; this was prevented by halofuginone.

CONCLUSIONS

Extracellular matrix production by activated PSCs is essential for tumor establishment and growth. Thus, inhibition of PSC activation is a viable means of reducing pancreatic tumor development.

Fibrosis inhibition and muscle histopathology improvement in laminin-alpha2-deficient mice

In muscular dystrophies (MD) the loss of muscle and its ability to function are associated with fibrosis. We evaluated the efficacy of halofuginone in reducing fibrosis in the dy(2J)/dy(2J) mouse model of congenital MD. Mice were injected intraperitoneally with 5 microg of halofuginone 3 times a week for 5 or 15 weeks, starting at the age of 3 weeks. Halofuginone caused a reduction in collagen synthesis in hindlimb muscles. This was associated with reductions in the degenerated area, in cell proliferation, in the number of myofibers with central nuclei, with increased myofiber diameter, and with enhanced motor coordination and balance. Halofuginone caused a reduction in infiltrating fibroblasts that were located close to centrally nucleated myofibers. Our results suggest that halofuginone reduced the deleterious effects of fibrosis, thus improving muscle integrity. Halofuginone meets the criteria for a novel antifibrotic therapy for MD patients.

Halofuginone inhibits Smad3 phosphorylation via the PI3K/Akt and MAPK/ERK pathways in muscle cells: effect on myotube fusion

Halofuginone, a novel inhibitor of Smad3 phosphorylation, has been shown to inhibit muscle fibrosis and to improve cardiac and skeletal muscle functions in the mdx mouse model of Duchenne muscular dystrophy. Here, we demonstrate that halofuginone promotes the phosphorylation of Akt and mitogen-activated protein kinase (MAPK) family members in a C2 muscle cell line and in primary myoblasts derived from wild-type and mdx mice diaphragms. Halofuginone enhanced the association of phosphorylated Akt and MAPK/extracellular signal-regulated protein kinase (ERK) with the non-phosphorylated form of Smad3, accompanied by a reduction in Smad3 phosphorylation levels. This reduction was reversed by inhibitors of the phosphoinositide 3'-kinase/Akt (PI3K/Akt) and MAPK/ERK pathways, suggesting their specific role in mediating halofuginone's inhibitory effect on Smad3 phosphorylation. Halofuginone enhanced Akt, MAPK/ERK and p38 MAPK phosphorylation and inhibited Smad3 phosphorylation in myotubes, all of which are crucial for myotube fusion. In addition, halofuginone increased the association Akt and MAPK/ERK with Smad3. As a consequence, halofuginone promoted myotube fusion, as reflected by an increased percentage of C2 and mdx myotubes containing high numbers of nuclei, and this was reversed by specific inhibitors of the PI3K and MAPK/ERK pathways. Together, the data suggest a role, either direct or via inhibition of Smad3 phosphorylation, for Akt or MAPK/ERK in halofuginone-enhanced myotube fusion, a feature which is crucial to improving muscle function in muscular dystrophies.

Halofuginone inhibits TH17 cell differentiation by activating the amino acid starvation response

A central challenge for improving autoimmune therapy is preventing inflammatory pathology without inducing generalized immunosuppression. T helper 17 (TH17) cells, characterized by their production of interleukin-17, have emerged as important and broad mediators of autoimmunity. Here we show that the small molecule halofuginone (HF) selectively inhibits mouse and human TH17 differentiation by activating a cytoprotective signaling pathway, the amino acid starvation response (AAR). Inhibition of TH17 differentiation by HF is rescued by the addition of excess amino acids and is mimicked by AAR activation after selective amino acid depletion. HF also induces the AAR in vivo and protects mice from TH17-associated experimental autoimmune encephalomyelitis. These results indicate that the AAR pathway is a potent and selective regulator of inflammatory T cell differentiation in vivo.

Inhibition of transforming growth factor beta signaling by halofuginone as a modality for pancreas fibrosis prevention

OBJECTIVES

Chronic pancreatitis is characterized by inflammation and fibrosis. We evaluated the efficacy of halofuginone, an inhibitor of collagen synthesis and myofibroblast activation, in preventing cerulein-induced pancreas fibrosis.

METHODS

Collagen synthesis was evaluated by in situ hybridization and staining. Levels of prolyl 4-hydroxylase beta (P4Hbeta), cytoglobin/stellate cell activation-associated protein (Cygb/STAP), transgelin, tissue inhibitors of metalloproteinases, serum response factor, transforming growth factor beta (TGFbeta), Smad3, and pancreatitis-associated protein 1 (PAP-1) were determined by immunohistochemistry. Metalloproteinase activity was evaluated by zymography.

RESULTS

Halofuginone prevented cerulein-dependent increase in collagen synthesis, collagen cross-linking enzyme P4Hbeta, Cygb/STAP, and tissue inhibitors of metalloproteinase 2. Halofuginone did not affect TGFbeta levels in cerulein-treated mice but inhibited serum response factor synthesis and Smad3 phosphorylation. In culture, halofuginone inhibited pancreatic stellate cell (PSC) proliferation and TGFbeta-dependent increase in Cygb/STAP and transgelin synthesis and metalloproteinase 2 activity. Halofuginone increased c-Jun N-terminal kinase phosphorylation in PSCs derived from cerulein-treated mice. Halofuginone prevented the increase in acinar cell proliferation and further increased the cerulein-dependent PAP-1 synthesis.

CONCLUSIONS

Halofuginone inhibits Smad3 phosphorylation and increases c-Jun N-terminal kinase phosphorylation, leading to the inhibition of PSC activation and consequent prevention of fibrosis. Halofuginone increased the synthesis of PAP-1, which further reduces pancreas fibrosis. Thus, halofuginone might serve as a novel therapy for pancreas fibrosis.

Myofibroblasts in pulmonary and brain metastases of alveolar soft-part sarcoma: a novel target for treatment?

Alveolar soft-part sarcoma (ASPS) is a rare neoplasm with chromosomal translocation that results in ASPL-TFE3 fusion. It is a slow-growing lesion associated with a high incidence of pulmonary and brain metastases indicating poor survival. We demonstrated that the ASPS metastases include also stromal myofibroblasts. These cells proliferate, express smooth-muscle genes, and synthesize extracellular matrix proteins, all of which are characteristics of activated myofibroblasts. The tumor cells also exhibited stromal components such as transforming growth factor beta (TGFbeta)-dependent, hypoxia-regulated cytoglobin (stellate cell activation association protein, cytg/STAP) and prolyl 4-hydroxylase, a collagen cross-linking enzyme. The pulmonary ASPS myofibroblasts synthesize serum response factor (SRF), a repressor of Smad3-mediated TGFbeta signaling essential for myofibroblast differentiation and Smad3. The phosphorylated active Smad3 was found mostly in the tumor cells. The brain tumor cells express cytg/STAP, but in contrast to the lung metastases, they also express SRF, Smad3, and phospho-Smad3. Halofuginone, an inhibitor of myofibroblasts' activation and Smad3 phosphorylation, inhibited tumor development in xenografts derived from renal carcinoma cells harboring a reciprocal ASPL-TFE3 fusion transcript. This inhibition was associated with the inhibition of TGFbeta/SRF signaling, with the inhibition of myofibroblasts' activation, and with the complete loss in TFE3 synthesis by the tumor cells. These results suggest that the myofibroblasts may serve as a novel target for treatment of ASPS metastases.

Targeting liver myofibroblasts: a novel approach in anti-fibrogenic therapy

Chronic liver disease results in a liver-scarring response termed fibrosis. Excessive scarring leads to cirrhosis, which is associated with high morbidity and mortality. The only treatment for liver cirrhosis is liver transplantation; therefore, much attention has been directed toward therapies that will slow or reverse fibrosis. Although anti-fibrogenic therapies have been shown to be effective in experimental animal models, licensed therapies have yet to emerge. A potential problem for any anti-fibrogenic therapy in the liver is the existence of the body’s major drug metabolising cell (the hepatocyte) adjacent to the primary fibrosis-causing cell, the myofibroblast. This article reviews the development of a human recombinant single-chain antibody (scAb) that binds to the surface of myofibroblasts. This antibody binds specifically to myofibroblasts in fibrotic mouse livers. When conjugated with a compound that stimulates myofibroblast apoptosis, the antibody directs the specific apoptosis of myofibroblasts with greater specificity and efficacy than the free compound. The antibody also reduces the adverse effect of liver macrophage apoptosis and—in contrast to the free compound—reversed fibrosis in the sustained injury model used. These data suggest that specifically stimulating the apoptosis of liver myofibroblasts using a targeting antibody has potential in the treatment of liver fibrosis.

A review of the foreign-body response to subcutaneously-implanted devices: the role of macrophages and cytokines in biofouling and fibrosis

The biological response to implanted biomaterials in mammals is a complex series of events that involves many biochemical pathways. Shortly after implantation, fibrinogen and other proteins bind to the device surface, a process known as biofouling. Macrophages then bind to receptors on the proteins, join into multinucleated giant cells, and release transforming growth factor beta and other inflammatory cytokines. In response to these signals, quiescent fibroblasts are transformed into myofibroblasts, which synthesize procollagen via activation of Smad mediators. The procollagen becomes crosslinked after secretion into the extracellular space. Mature crosslinked collagen and other extracellular matrix proteins gradually contribute to formation of a hypocellular dense fibrous capsule that becomes impermeable or hypopermeable to many compounds. Porous substrates and angiogenic growth factors can stimulate formation of microvessels, which to some extent can maintain analyte delivery to implanted sensors. However, stimulation by vascular endothelial growth factor alone may lead to formation of leaky, thin-walled, immature vessels. Other growth factors are most probably needed to act upon these immature structures to create more robust vessels.During implantation of foreign bodies, the foreign-body response is difficult to overcome, and thousands of biomaterials have been tested. Biomimicry (i.e., creating membranes whose chemical structure mimics natural cellular compounds) may diminish the response, but as of this writing, it has not been possible to create a stealth material that circumvents the ability of the mammalian surveillance systems to distinguish foreign from self.

Prevention of muscle fibrosis and improvement in muscle performance in the mdx mouse by halofuginone

Fibrosis is a known feature of dystrophic muscles, particularly the diaphragm, in the mdx mouse. In this study we evaluated the effect of halofuginone, a collagen synthesis inhibitor, on collagen synthesis in various muscles of young wild-type (C57/BL/6J) and mdx mice. Halofuginone prevented the age-dependent increase in collagen synthesis in the diaphragms of mdx with no effect on wild-type mice (n = 5 for each time point). This was associated with a decrease in the degenerated areas and number of central nuclei. Halofuginone also inhibited collagen synthesis in cardiac muscle. Moreover, enhanced motor coordination, balance and improved cardiac muscle function were observed implying reduced muscle injury. Halofuginone inhibited Smad3 phosphorylation downstream of TGFbeta in the diaphragm and cardiac muscles, in C2 cell line and in primary mouse myoblast cultures representing various muscular dystrophies. We suggest that via its effect on Smad3 phosphorylation, halofuginone inhibits muscle fibrosis and improves cardiac and skeletal muscle functions in mdx mice.

Halofuginone upregulates the expression of heparanase in thioacetamide-induced liver fibrosis in rats

Advanced hepatic fibrosis is characterized by excessive extracellular matrix deposition, where collagen and proteoglycans are the main constituents of scar tissue. In previous studies, we showed that heparanase, a heparan sulfate-degrading enzyme, and vascular endothelial growth factor (VEGF) play an important role during liver development and remodeling. In this communication, we investigated the relationship between heparanase and VEGF in thioacetamide-induced liver fibrosis in rats. Our study shows that heparanase mRNA expression levels correlate with those of VEGF during the induction and recovery stages of liver fibrosis. We further demonstrated that treating fibrotic rat livers with halofuginone (HF), a multipotent antifibrogenic drug, and subsequently subjecting them to hydrodynamics-based transfection with human VEGF-165 resulted in elevated expression of heparanase mRNA. Moreover, these rats demonstrated an improved capacity to regenerate following 70% partial hepatectomy. In vitro, HF stimulated heparanase and VEGF mRNA expression in hepatic stellate cells. Taken together, our results suggest that in addition to the known multiple functions of HF, it also enhances heparanase and VEGF expression and promotes liver regeneration. Accordingly, HF seems to possess ideal properties required to become an excellent antifibrogenic agent in humans.

Inhibition of inducible nitric oxide synthase activity prevents liver recovery in rat thioacetamide-induced fibrosis reversal

BACKGROUND

Stimulation of nitric oxide (NO) synthesis similar to the application of NO donors could be of benefit in liver fibrosis. Many authors believe that activation of NO synthesis by pharmacological agents is promising in the treatment of liver fibrosis. However, there is considerable controversy in understanding the role of NO in fibrogenesis and fibrolysis. The aims of our study were to evaluate the effects of L-arginine, as an NO metabolic precursor, and those of NO synthase (NOS) inhibitors, L-nitroarginine methyl ester (L-NAME) and aminoguanidine (AG) in rats with thioacetamide (TAA)-induced liver fibrosis reversal.

MATERIALS AND METHODS

Male Wistar rats, 230-240 g, received TAA (200 mg kg(-1), intraperitoneally) twice a week for 3 months. Liver resolution was simulated by withdrawal of TAA administration. Thereafter the animals were subdivided into five groups and treated by intragastric intubation with: L-arginine (100 and 300 mg kg(-1)); L-NAME as an inhibitor of both constitutively expressed NOS (eNOS) and inducible NOS (iNOS) (20 mg kg(-1)), AG as a specific inhibitor of iNOS (100 mg kg(-1)) or placebo. The severity of liver fibrosis was assessed by morphometric evaluation of liver slides stained with Azan-Mallory, hydroxyproline (Hyp) determination and mRNA steady state levels of collagen I, transforming growth factor (TGF)-beta1, metalloproteinases (MMP)-13, -14, tissue inhibitor of MMP (TIMP)-1 and plasminogen activator inhibitor (PAI)-1 were quantified by real time PCR. The activities of serum marker enzyme, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, were measured.

RESULTS

TAA treatment during 3 months induced micronodular liver fibrosis with a pronounced deposition of collagen fibres. L-Arginine did not affect this deposition nor did it affect both relative and total liver hydroxyproline content. Both NOS inhibitors significantly increased the square of the liver connective tissue stained by Azan-Mallory and the above parameters characterizing liver hydroxyproline content. Both NOS inhibitors up-regulated procollagen alpha1 (I), MMP-13, TIMP-1 and PAI-1 mRNA expression. The AG effects were more pronounced. than those of L-NAME. AG treatment also increased mRNA expression of TGF-beta1 and PAI-1.

CONCLUSIONS

Both NOS inhibitors developed a clear pro-fibrotic effect in the liver. Aminoguanidine was more fibrotic than L-NAME. Our data suggest a significant anti-fibrotic role for iNOS rather than for eNOS. L-Arginine did not show any anti-fibrotic properties in the TAA-model used.

Functional resolution of fibrosis in mdx mouse dystrophic heart and skeletal muscle by halofuginone

The effect of halofuginone (Halo) on established fibrosis in older mdx dystrophic muscle was investigated. Mice (8 to 9 mo) treated with Halo (or saline in controls) for 5, 10, or 12 wk were assessed weekly for grip strength and voluntary running. Echocardiography was performed at 0, 5, and 10 wk. Respiratory function and exercise-induced muscle damage were tested. Heart, quadriceps, diaphragm, and tibialis anterior muscles were collected to study fibrosis, collagen I and III expression, collagen content using a novel collagenase-digestion method, and cell proliferation. Hepatocyte growth factor and α-smooth muscle actin proteins were assayed in quadriceps. Halo decreased fibrosis (diaphragm and quadriceps), collagen I and III expression, collagen protein, and smooth muscle actin content after 10 wk treatment. Muscle-cell proliferation increased at 5 wk, and hepatocyte growth factor increased by 10 wk treatment. Halo markedly improved both cardiac and respiratory function and reduced damage and improved recovery from exercise. The overall impact of established dystrophy and dysfunction in cardiac and skeletal muscles was reduced by Halo treatment. Marked improvements in vital-organ functions implicate Halo as a strong candidate drug to reduce morbidity and mortality in Duchenne muscular dystrophy.

The liver pharmacological and xenobiotic gene response repertoire

We have used a supervised classification approach to systematically mine a large microarray database derived from livers of compound-treated rats. Thirty-four distinct signatures (classifiers) for pharmacological and toxicological end points can be identified. Just 200 genes are sufficient to classify these end points. Signatures were enriched in xenobiotic and immune response genes and contain un-annotated genes, indicating that not all key genes in the liver xenobiotic responses have been characterized. Many signatures with equal classification capabilities but with no gene in common can be derived for the same phenotypic end point. The analysis of the union of all genes present in these signatures can reveal the underlying biology of that end point as illustrated here using liver fibrosis signatures. Our approach using the whole genome and a diverse set of compounds allows a comprehensive view of most pharmacological and toxicological questions and is applicable to other situations such as disease and development.

Emerging drugs for complications of end-stage liver disease

BACKGROUND

The prevalence of end-stage liver disease is rising rapidly and constitutes a major healthcare burden currently. Many cases are diagnosed at a later stage when liver transplantation is the only effective treatment option. There is thus an urgent need for novel treatments to reverse the earlier stages of cirrhosis as well as to treat the many associated life-threatening complications.

OBJECTIVES

To review the current drugs available for treating the complications of advanced liver disease. To address novel treatment strategies that are in development, with particular reference to the rapidly developing area of antifibrotic therapy. To assess how the obstacles that have so far impeded the development of effective new drugs for end-stage liver disease may be overcome in the future.

METHODS

The literature was reviewed to define current therapies and therapies in clinical trials. We used the current models of the molecular basis of liver fibrogenesis to determine potential new therapeutic targets for antifibrotic therapy.

CONCLUSIONS

Insights into the pathogenesis of liver injury and fibrosis have opened up new avenues for therapy and there are now candidates and targets with real potential for the development of a new generation of antifibrotic therapies.

Transforming growth factor-β and fibrosis

Transforming growth factor-β (TGF-β), a prototype of multifunctional cytokine, is a key regulator of extracellular matrix (ECM) assembly and remodeling. Specifically, TGF-β isoforms have the ability to induce the expression of ECM proteins in mesenchymal cells, and to stimulate the production of protease inhibitors that prevent enzymatic breakdown of the ECM. Elevated TGF-β expression in affected organs, and subsequent deregulation of TGF-β functions, correlates with the abnormal connective tissue deposition observed during the onset of fibrotic diseases. During the last few years, tremendous progress has been made in the understanding of the molecular aspects of intracellular signaling downstream of the TGF-β receptors. In particular, Smad proteins, TGF-β receptor kinase substrates that translocate into the cell nucleus to act as transcription factors, have been studied extensively. The role of Smad3 in the transcriptional regulation of typeIcollagen gene expression and in the development of fibrosis, demonstrated both in vitro and in animal models with a targeted deletion of Smad3, is of critical importance because it may lead to novel therapeutic strategies against these diseases. This review focuses on the mechanisms underlying Smad modulation of fibrillar collagen expression and how it relates to fibrotic processes.