Inhibition of collagen type I synthesis by skin fibroblasts of graft versus host disease and scleroderma patients: effect of halofuginone

Halofuginone: a potent inhibitor of critical steps in angiogenesis progression

We have previously demonstrated that halofuginone, a low molecular weight quinazolinone alkaloid, is a potent inhibitor of collagen alpha1(I) and matrix metalloproteinase 2 (MMP-2) gene expression. Halofuginone also effectively suppresses tumor progression and metastasis in mice. These results together with the well-documented role of extracellular matrix (ECM) components and matrix degrading enzymes in formation of new blood vessels led us to investigate the effect of halofuginone on the angiogenic process. In a variety of experimental system, representing sequential events in the angiogenic cascade, halofuginone treatment resulted in profound inhibitory effect. Among these are the abrogation of endothelial cell MMP-2 expression and basement membrane invasion, capillary tube formation, and vascular sprouting, as well as deposition of subendothelial ECM. The most conclusive anti-angiogenic activity of halofuginone was demonstrated in vivo (mouse corneal micropocket assay) by showing a marked inhibition of basic fibroblast growth factor (bFGF) -induced neovascularization in response to systemic administration of halofuginone, either i.p. or in the diet. The ability of halofuginone to interfere with key events in neovascularization, together with its oral bioavailability and safe use as an anti-parasitic agent, make it a promising drug for further evaluation in the treatment of a wide range of diseases associated with pathological angiogenesis.

Scleroderma and related disorders: therapeutic aspects

Improvements in management of systemic sclerosis have occurred through a growing understanding of pathogenic events accompanied by advances in diagnosis and assessment, as well as developments in organ-based therapeutics. Unfortunately, disease-modifying therapies of proven efficacy remain elusive and several agents in current use have been shown in well-controlled clinical trials to be of questionable benefit. More positively, there have been advances in the treatment of major visceral complications such as renal crisis, pulmonary fibrosis, pulmonary hypertension, gastrointestinal involvement and in the management of scleroderma-associated Raynaud's phenomenon. Current approaches are reviewed, evidence supporting or refuting the use of putative disease-modifying agents is discussed, and new strategies are described that are currently being considered for this fascinating but complex multisystem connective tissue disease.

Topical treatment of cutaneous chronic graft versus host disease with halofuginone: a novel inhibitor of collagen type I synthesis

BACKGROUND

In chronic graft-versus-host disease (cGvHD), skin fibrosis, contractures, and an increase in collagen content form the hallmark. We report a successful treatment of a cGvHD patient by topical application of halofuginone, an inhibitor of collagen alpha1(I) gene expression.

METHODS

Halofuginone-containing ointment was applied daily on the left side of the neck and shoulder of a cGvHD patient. Collagen alpha1(I) gene expression and collagen content in skin biopsy specimens were evaluated by in situ hybridization and sirius red staining, respectively.

RESULTS

After 3 and 6 months, a marked reduction in skin collagen synthesis was observed, accompanied with increase neck rotation on the treated side. After cessation of treatment, the sclerosis, skin tightness, and collagen alpha1(I) gene expression returned to baseline level. No adverse effects were observed, and no plasma levels of halofuginone could be detected.

CONCLUSIONS

Halofuginone may provide a promising novel and safe therapy for cGvHD patients.

Inhibition of neovascularization and tumor growth, and facilitation of wound repair, by halofuginone, an inhibitor of collagen type I synthesis

Halofuginone, an inhibitor of collagen alpha1(I) gene expression was used for the treatment of subcutaneously implanted C6 glioma tumors. Halofuginone had no effect on the growth of C6 glioma spheroids in vitro, and these spheroids showed no collagen alpha1(I) expression and no collagen synthesis. However, a significant attenuation of tumor growth was observed in vivo, for spheroids implanted in CD-1 nude mice which were treated by oral or intraperitoneal (4 microg every 48 hours) administration of halofuginone. In these mice, treatment was associated with a dose-dependent reduction in collagen alpha1(I) expression and dose- and time-dependent inhibition of angiogenesis, as measured by MRI. Moreover, halofuginone treatment was associated with improved re-epithelialization of the chronic wounds that are associated with this experimental model. Oral administration of halofuginone was effective also in intervention in tumor growth, and here, too, the treatment was associated with reduced angiogenic activity and vessel regression. These results demonstrate the important role of collagen type I in tumor angiogenesis and tumor growth and implicate its role in chronic wounds. Inhibition of the expression of collagen type I provides an attractive new target for cancer therapy.

Novel therapeutic strategies in scleroderma

Optimal management for scleroderma (systemic sclerosis) is likely to require treatment of the underlying disease process, which remains incompletely understood, and also of the organ-based complications of this heterogeneous condition. Clinical trials evaluating several potential agents have been completed recently, including D-penicillamine and interferon alpha. Unfortunately none of these studies has suggested significant efficacy. This article focuses on new treatment approaches using existing therapeutic agents, such as prostacyclin, and considers the potential usefulness of new agents (eg, relaxin, halofuginone) or strategies such as intensive immunosuppression with peripheral stem cell rescue. Ultimately, a better understanding of disease pathogenesis may facilitate the development of targeted therapy against key events or mediators, but for the present better evaluation of existing agents and a focus on optimizing protocols for organ-based complications, such as pulmonary vascular disease or hypertensive renal crisis, are important goals.

Pathophysiology and treatment of graft-versus-host disease

Acute graft-versus-host disease denotes a distinctive syndrome characterized by a triad of dermatitis (rash), hepatitis (jaundice), and gastroenteritis (abdominal pain, diarrhea) developing in the first 100 days after allogeneic hematopoietic cell transplantation. Chronic graft-versus-host disease designates a more diverse syndrome, usually presenting with multiorgan involvement and commonly developing 100 days after hematopoietic cell transplantation. This article discusses the pathophysiology, incidence and predictive factors, clinical manifestations, diagnosis and grading, prevention, and treatment for both types of the disease.

Liver fibrogenesis and the role of hepatic stellate cells: new insights and prospects for therapy

Hepatic fibrosis is a wound-healing response to chronic liver injury, which if persistent leads to cirrhosis and liver failure. Exciting progress has been made in understanding the mechanisms of hepatic fibrosis. Major advances include: (i) characterization of the components of extracellular matrix (ECM) in normal and fibrotic liver; (ii) identification of hepatic stellate cells as the primary source of ECM in liver fibrosis; (iii) elucidation of key cytokines, their cellular sources, modes of regulation, and signalling pathways involved in liver fibrogenesis; (iv) characterization of key matrix proteases and their inhibitors; (v) identification of apoptotic mediators in stellate cells and exploration of their roles during the resolution of liver injury. These advances have helped delineate a more comprehensive picture of liver fibrosis in which the central event is the activation of stellate cells, a transformation from quiescent vitamin A-rich cells to proliferative, fibrogenic and contractile myofibroblasts. The progress in understanding fibrogenic mechanisms brings the development of effective therapies closer to reality. In the future, targeting of stellate cells and fibrogenic mediators will be a mainstay of antifibrotic therapy. Points of therapeutic intervention may include: (i) removing the injurious stimuli; (ii) suppressing hepatic inflammation; (iii) down-regulating stellate cell activation; and (iv) promoting matrix degradation. The future prospects for effective antifibrotic treatment are more promising than ever for the millions of patients with chronic liver disease worldwide.

Halofuginone, an inhibitor of collagen type I synthesis, prevents postoperative adhesion formation in the rat uterine horn model

OBJECTIVE

The objective of this study was to evaluate the effects of halofuginone-a specific inhibitor of collagen type I synthesis-in preventing uterine horn adhesion formation in rats.

STUDY DESIGN

Adhesions were induced by scraping the rat uterine horns until capillary bleeding occurred. Halofuginone was either injected intraperitoneally or administered orally. The number and severity of the adhesions were scored. Collagen alpha1(I) gene expression was evaluated by in situ hybridization; total collagen was estimated by sirius red staining. Collagen synthesis in response to halofuginone was evaluated in cells cultured from the adhesions.

RESULTS

Regardless of the administration procedure, halofuginone reduced significantly the number and severity of the adhesions in a dose-dependent manner. Halofuginone prevented the increase in collagen alpha1(I) gene expression observed in the rats that underwent this procedure, thus affecting only the newly synthesized collagen but not the resident collagen. In cells derived from rat uterine horn adhesions, halofuginone induced dose-dependent inhibition of collagen synthesis.

CONCLUSIONS

Upregulation of collagen synthesis appears to play a critical role in the pathophysiologic mechanism of adhesion formation. Halofuginone could be used as an important means of understanding the role of collagen in adhesion formation and might become a novel and promising antifibrotic agent for preventing adhesion formation after pelvic surgery.

Halofuginone: a novel antifibrotic therapy

1. Fibrosis is characterized by extracellular matrix deposition, of which collagen type I is the major constituent. The progressive accumulation of connective tissue resulted in destruction of normal tissue architecture and function. 2. Fibrosis is a common response to various insults or injuries and can be the outcome of any perturbation in the cellular function of any tissue. 3. Halofuginone was found to inhibit collagen alpha 1(I) gene expression and collagen synthesis in a variety of cell cultures including human fibroblasts derived from patients with excessive skin collagen type I synthesis. 4. Halofuginone was found to inhibit collagen alpha 1(I) gene expression and collagen synthesis in animal models characterized by excessive deposition of collagen. In these models, fibrosis was induced in various tissues such as skin, liver, lung, etc. Halofuginone was injected intraperitoneally, added to the foodstuff or applied locally. 5. Halofuginone decreased skin collagen in a chronic graft-versus-host disease patient. 6. The ability of extremely low concentrations of halofuginone to inhibit collagen alpha 1(I) synthesis specifically and transiently at the transcriptional level suggests that this material fulfills the criteria for a successful and effective anti-fibrotic therapy.

Halofuginone--an inhibitor of collagen type I synthesis--prevents postoperative formation of abdominal adhesions

OBJECTIVE

To evaluate the effects of halofuginone, a specific inhibitor of collagen type I synthesis, on the postoperative formation of abdominal adhesions in rats.

SUMMARY BACKGROUND DATA

Postoperative adhesions remain the leading cause of small bowel obstruction in the Western world. Surgical trauma causes the release of a serosanguineous exudate that forms a fibrinous bridge between two organs. This becomes ingrown with fibroblasts, and subsequent collagen deposition leads to the formation of a permanent adhesion. Most of the drugs used have been clinically ineffective, and none has been specific to a particular extracellular matrix molecule. Therefore, there are serious concerns about the toxic consequences of interfering with the biosynthesis of other collagens, other matrix proteins, or vital collagen-like molecules.

METHODS

Adhesions were induced by scraping the cecum until capillary bleeding occurred. The adhesions were scored 21 days later. Halofuginone was either injected intraperitoneally (1 microg/25 g body weight) every day, starting on the day of operation, or added orally at concentrations of 5 or 10 mg/kg, starting 4 days before the operation. Collagen alpha1(I) gene expression was evaluated by in situ hybridization, total collagen was estimated by Sirius red staining, and collagen type III was detected by immunohistochemistry.

RESULTS

The adhesions formed between the intestinal walls were composed of collagen and were populated with cells expressing the collagen alpha1(I) gene. Regardless of the administration procedure, halofuginone significantly reduced the number and severity of the adhesions. Halofuginone prevented the increase in collagen alpha1(I) gene expression observed in the operated rats, thus reducing collagen content to the control level. In fibroblasts derived from abdominal adhesions, halofuginone induced dose-dependent inhibition of collagen alpha1(I) gene expression and collagen synthesis. Collagen type III levels were not altered by adhesion induction or by halofuginone treatment.

CONCLUSIONS

Upregulation of collagen synthesis appears to have a critical role in the pathophysiology of postoperative adhesions. Halofuginone, an inhibitor of collagen type I synthesis, could be used as an important tool in understanding the role of collagen in adhesion formation, and it may become a novel and promising antifibrotic agent for preventing postoperative adhesion formation.

The pathogenesis of cutaneous fibrosis

Cutaneous fibrosis is an integral component of a variety of human disorders including keloids, hypertrophic scar, and most notably, scleroderma. Each has its own etiology and unique clinical characteristics, but all involve the dysregulation of connective tissue metabolism, in particular, the activation of dermal fibroblasts. In this review, we examine various molecular events in scleroderma that may lead to fibroblast activation, and propose a new model to explain the persistence of such activation by scleroderma fibroblasts in the apparent absence of exogenous stimuli.

Halofuginone inhibits neointimal formation of cultured rat aorta in a concentration-dependent fashion in vitro

Halofuginone, an anticoccidial quinoazolinone, can specifically inhibit collagen type alpha1 (I) synthesis and gene expression, and also inhibits cultured smooth muscle cell proliferation. The aim of this study was to investigate the effect of halofuginone on neointimal formation of rat aorta after culture in a concentration-dependent manner in vitro. Thoracic aorta of Wistar rats was removed and manipulated to damage the endothelium under sterile conditions, and culture for 15 days in halofuginone-free or halofuginone-added culture medium (n = 20). Segments of cultured aorta were studied by histologic and immunohistochemical methods. Proliferation of neointimal layers consisting of loose multilayer cellular structure was observed in the halofuginone-free control group after 15 days of rat aorta culture, and neointimal formation was significantly decreased as an increasing concentration of halofuginone was added. As with precultured fresh aorta, no intimal proliferation was observed in the cultured segments of aorta with 500 ng/ml halofuginone added to culture medium. The proliferation of cell nuclear antigen index was significantly higher in the halofuginone-free control group than that in the halofuginone-added groups. The present results suggest that halofuginone can inhibit neointimal formation of rat aorta after culture in a concentration-dependent fashion in vitro.

Inhibition of glomerular mesangial cell proliferation and extracellular matrix deposition by halofuginone

Mesangial cell proliferation, increased deposition of collagen, and expansion of the mesangial extracellular matrix (ECM) are key features in the development of mesangioproliferative diseases. Halofuginone, a low molecular weight anti-coccidial quinoazolinone derivative, inhibits collagen type alpha 1(I) gene expression and synthesis. We investigated the effect of halofuginone on both normal and SV40 transformed mesangial cell proliferation, collagen synthesis, and ECM deposition. Proliferation of both cell types was almost completely inhibited in the presence of 50 ng/ml halofuginone. The cells were arrested in the late G1 phase of the cell cycle and resumed their normal growth rate following removal of the compound from the culture medium. The antiproliferative effect of halofuginone was associated with inhibition of tyrosine phosphorylation of cellular proteins. Similar results were obtained whether the mesangial cells were seeded on regular tissue culture plastic or in close contact with a naturally produced ECM resembling their local environment in vivo. Halofuginone also inhibited synthesis and deposition of ECM by mesangial cells as indicated by a substantial reduction in 14C-glycine and Na2(35)SO4 incorporation into the ECM, and by the inhibition of collagen type I synthesis and gene expression. It is proposed that by inhibiting collagen type I synthesis and matrix deposition, halofuginone exerts a potent antiproliferative effect that may be applied to inhibit mesangial cell proliferation and matrix expansion in a variety of chronic progressive glomerular diseases.

Halofuginone, a specific inhibitor of collagen type I synthesis, prevents dimethylnitrosamine-induced liver cirrhosis

BACKGROUND/AIMS

Hepatic cirrhosis is characterized by excessive deposition of collagen, resulting from an increase in type I collagen gene transcription. We evaluated the effect of halofuginone-a specific inhibitor of collagen type alpha 1(I) gene expression-on dimethylnitrosamine (DMN)-induced liver fibrosis/cirrhosis in rats.

METHODS

Fibrosis was induced by intraperitoneal injection of DMN. Halofuginone (5 mg/kg) was added to the diet. Collagen was stained with Sirius red and collagen alpha 1(I) gene expression was evaluated by in situ hybridization.

RESULTS

In control rats, a low level of collagen alpha 1(I) gene expression was observed. A high dose of DMN (1%) caused severe fibrosis, as indicated by induction of collagen alpha 1(I) gene expression and increased liver collagen content. Addition of halofuginone before the onset of fibrosis, almost completely prevented the increase in collagen type I gene expression and resulted in lower liver collagen content. Moreover, halofuginone partially prevented the marked decrease in liver weight and reduced the mortality rate. At a lower dose of DMN (0.25%), which causes mild fibrosis, halofuginone prevented the increase in collagen alpha 1(I) gene expression, prevented the increase in liver collagen deposition and reduced plasma alkaline phosphatase activity, all of which are characteristic of liver fibrosis/ cirrhosis.

CONCLUSIONS

These results suggest that halofuginone can be used as an important tool to understand the regulation of the collagen alpha 1(I) gene and may become a novel and promising antifibrotic agent for liver fibrosis/ cirrhosis.

Inhibition of collagen synthesis, smooth muscle cell proliferation, and injury-induced intimal hyperplasia by halofuginone

Proliferation of vascular smooth muscle cells (SMCs) and accumulation of extracellular matrix (ECM) components within the arterial wall in response to local injury are important etiologic factors in vascular proliferative disorders such as arteriosclerosis and restenosis after angioplasty. Fibrillar and nonfibrillar collagens are major constituents of the ECM that modulate cell shape and proliferative responses and thereby contribute to the pathogenesis of intimal hyperplasia. Halofuginone, an anticoccidial quinoazolinone derivative, inhibits collagen type I gene expression. We investigated the effect of halofuginone on (1) proliferation of bovine aortic endothelial cells and SMCs derived from the same specimen and maintained in vitro, (2) ECM deposition and collagen type I synthesis and gene expression, and (3) injury-induced intimal hyperplasia in vivo. DNA synthesis and proliferation of vascular SMCs in response to serum or basic fibroblast growth factor were abrogated in the presence of as little as 0.1 microgram/mL halofuginone; this inhibition was reversible upon removal of the compound. Under the same conditions, halofuginone exerted a relatively small antiproliferative effect on the respective vascular endothelial cells. Halofuginone also inhibited the synthesis and deposition of ECM components by vascular SMCs as indicated both by a substantial reduction in the amount of sulfated proteoglycans and collagen type I synthesis and gene expression. Local administration of halofuginone in the rabbit ear model of crush injury-induced arterial intimal hyperplasia resulted in a 50% reduction in intimal thickening as measured by a morphometric analysis of the neointima/media ratio. The differential inhibitory effect of halofuginone on vascular SMCs versus endothelial cells, its inhibition of ECM deposition and collagen type I synthesis, and its ability to attenuate injury-induced intimal hyperplasia may place halofuginone alone or in combination with other antiproliferative compounds as a potential candidate for prevention of arterial stenosis and accelerated atherosclerosis.