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Biomedical subjects

A Desmoulière

Publications and source records attributed to A Desmoulière.

At least 19 recordsLinked to original sources
PubMed2005

Investigation of liver fibrosis in clinical practice.

The liver is composed of different hepatic fibrogenic cells: hepatic stellate cells, portal fibroblasts, fibroblasts of the Glisson capsule surrounding the liver and vascular smooth muscle cells and the second layer cells present around centrolobular veins. During liver disease, one or several populations of these cells are activated, transformed into myofibroblasts and secrete the extra-cellular matrix. There are markers to identify hepatic stellate cells either quiescent (CRBP-1) or activated (alpha-smooth muscle actin). Liver biopsy, the current "gold-standard" to estimate liver fibrosis cannot be used anymore as a "gold standard". Furthermore, it is a costly procedure with adverse effects feared by patients and clinicians. Alternative to liver biopsy using non-invasive-tests or technics include FibroTest-ActiTest, transient-elastography, hepatic vein transit time using contrast ultrasonography, magnetic resonance imaging. As a routine test, the FibroTest-ActiTest is a validated one for patients with chronic hepatitis C. The advantage of the non-invasive tests or technics is that they provide a rapid and quantitative estimation of fibrosis. With these new methods, it is possible to follow the progression of the disease and its regression either spontaneously or under treatment. In conclusion, clinicians have in their hands several painless tools to explore liver fibrosis that can be easily repeated.

Journal Article↗
PubMed2004

A role for thrombin in liver fibrosis.

BACKGROUND/AIM: Several lines of evidence incriminate the serine proteinase thrombin in liver fibrogenesis either through its procoagulant function or its signaling via cell-surface receptors. The aim of this study was therefore to evaluate the effect of thrombin inhibition on experimental liver fibrosis. METHODS: Fibrosis was induced in rats by administration of CCl4 for either three or seven weeks. Oral administration of the thrombin antagonist SSR182289 started one week after the start of CCl4 intoxication. Fibrosis and the area occupied by alpha smooth muscle actin (ASMA) positive cells were quantified with histomorphometry. Expression of fibrosis related genes was measured by real time RT-PCR. RESULTS: After three weeks of CCl4, treatment with SSR182289 did not significantly decrease the area of fibrosis but significantly decreased the area of ASMA positive cells by 22% (p = 0.03) and the expression of TIMP-1 mRNA by 52% (p = 0.02). There was no effect on gene expression of collagen I, MMP-2, or TIMP-2. After seven weeks of CCl4, treatment with SSR182289 resulted in a significant decrease in fibrosis (-30%, p = 0.04) and ASMA positive areas (-35%, p = 0.05). SSR182289 alone had no effect on the measured parameters. Additionally, it did not alleviate the acute toxicity of CCl4 as shown by measuring levels of serum aminotransferases and the area of necrosis. CONCLUSIONS: These data provide evidence that thrombin antagonism can reduce liver fibrogenesis. The early effect of SSR182289 on ASMA and TIMP-1 expression suggests that it is beneficial in reducing fibrogenic cell activation.

Actins↗
PubMed2003

Validation of a morphometric method for evaluating fibroblast numbers in normal and pathologic tissues.

The aim of this work was to validate an image analysis method, based on cell nuclei form factor determination, for counting fibroblasts within human dermis. We first used reconstructed dermal equivalents in which fibroblasts can also be counted directly after lysis of the collagen matrix. We found a good correlation between the results of direct counting and those of image analysis from day 10 to day 28 of culture. When applied to young normal donors' skin biopsies fixed in Bouin's solution and embedded in paraffin, the image analysis method yielded mid-dermis fibroblast counts of between 2100 and 4100 per mm3 of fresh tissue. A nuclear form factor (FF) comprised between 0.35 and 0.84 was found to be a biologic marker of fibroblasts. This was confirmed after fibroblast discrimination from other cell types, which had rounder nuclei (FF >/= 0.85) and were identified either by their location (e.g. endothelial cells) or by labeling with specific antibodies (e.g. lymphocytes and monocytes/macrophages). Similar results were obtained with seven healthy donors' skin biopsies that had been frozen in nitrogen liquid and cryostat-sectioned, showing that this counting method is independent of the histologic procedure. Finally, analysis of samples of hypertrophic scars from two patients revealed that fibroblast density in some parts of the dermis was more than twice the value found in other parts presenting a fibroblast density almost normal, showing that this cell counting method can also be used to assess fibroblast heterogeneity within a given tissue.

Cell Count↗
PubMed2002

[Mechanisms of hepatic fibrogenesis].

Hepatic fibrosis is a scaring process leading to cirrhosis, a major complication of numerous chronic liver diseases. Hepatic stellate cells play a central role in the fibrotic process. After parenchymal or biliary injury, cytokines and growth factors allow the recruitment, proliferation, and activation, of stellate cells toward myofibroblasts, which secrete the extracellular matrix. Fibrosis, resulting from the failure of the balance between synthesis and degradation of extracellular matrix, is an evolutive and potentially reversible process. Histological examination is the main investigation to quantify fibrosis. Serological tests are warranted to allow a non invasive follow up of patients. Development of antifibrotic therapies should soon permit to slow down the evolution toward cirrhosis, limiting the needs for hepatic transplantation.

Cell Division↗
PubMed2001

Expression of hepatocyte growth factor in human hepatocellular carcinoma.

BACKGROUND/AIMS: We have shown that hepatocyte growth factor, secreted by human liver myofibroblasts, promoted in vitro invasion of human hepatocellular carcinoma cell lines. The aim of this work was to measure hepatocyte growth factor expression in 29 human hepatocellular carcinomas and the corresponding peri-tumoral livers. METHODS: We used reverse transcription-polymerase chain reaction, in situ hybridization, ELISA and Western blot. RESULTS: Sixty-two of tested hepatocellular carcinomas were positive by reverse transcription-polymerase chain reaction. With in situ hybridization, a signal was found in every sample. In many cases, the signal was localized in cells labeled with an anti-smooth muscle alpka-actin antibody, while hepatocytes were mostly non-labeled. ELISA, performed in 15 pairs of hepatocellular carcinomas and surrounding livers, detected hepatocyte growth factor in every sample with wide variations. Hepatocellular carcinomas that had developed in non-cirrhotic livers contained essentially the same amount of hepatocyte growth factor as the matching non-tumoral liver. In cirrhotic livers, the hepatocyte growth factor content of the tumors was significantly lower than that of the surrounding cirrhotic livers. CONCLUSIONS: These data indicate that hepatocyte growth factor is expressed at significant levels in every hepatocellular carcinoma tested and that its expression takes place in the stromal myofibroblasts.

Carcinoma, Hepatocellular↗
PubMed2001

Expression and cellular localization of fibrillin-1 in normal and pathological human liver.

BACKGROUND: The expression and the distribution of fibrillin-1 and elastin were studied in normal and pathological human liver samples. METHODS: As controls, histologically normal/subnormal liver samples (n = 24) were used. Pathological samples corresponded to seven cirrhosis and eight hepatocellular carcinomas (HCC) developed on cirrhotic (four) or noncirrhotic (four) liver. RESULTS: In normal liver, fibrillin-1 and elastin co-localized in vessel walls and portal tract connective tissue. Fibrillin-1 alone was detected along sinusoids and in portal spaces at the interface with the limiting hepatocytic plates and close to the basement membrane of bile ducts. By transmission electron microscopy, typical bundles of microfibrils were detected both in Disse space and in portal zones. Cirrhotic nodules were usually rich in fibrillin-1 along sinusoids; fibrillin-1 and elastin were co-localized in fibrotic septa surrounding nodules. In HCC, fibrillin-1 was present between tumoral hepatocytes; stromal reaction around the tumors contained both fibrillin-1 and elastin. CONCLUSIONS: Fibrillin-1 was associated with elastin in portal mesenchyme and vessel walls of normal liver, in fibrotic septa around cirrhotic nodules and stromal reaction around HCC, but was expressed alone in the perisinusoidal space. The functional roles for fibrillin-1 in non-elastic tissues, such as the liver, remain to be elucidated.

Adult↗
PubMed2001

Trans-resveratrol, a grapevine-derived polyphenol, blocks hepatocyte growth factor-induced invasion of hepatocellular carcinoma cells.

We have shown that liver myofibroblasts stimulate in vitro invasion of hepatocellular carcinoma cell lines through a hepatocyte growth factor/urokinase-dependent mechanism. Resveratrol, a grapevine-derived polyphenol, has been shown to inhibit cellular events associated with tumor initiation, promotion and progression. The aim of this study was to evaluate the effects of trans-resveratrol on invasion of the human hepatoma cell line HepG2. Cell invasion was assessed using a Boyden chamber assay. Activation of the HGF signal transduction pathways was evaluated by Western blot with phospho-specific antibodies. Urokinase expression was measured by RT-PCR and zymography. Trans-resveratrol decreased hepatocyte growth factor-induced cell scattering and invasion. It also decreased cell proliferation without evidence for cytotoxicity or apoptosis. Trans-resveratrol did not decrease the level of the hepatocyte growth factor receptor c-met and did not impede the hepatocyte growth factor-induced increase in c-met precursor synthesis. Moreover, trans-resveratrol did not decrease hepatocyte growth factor-induced c-met autophosphorylation, or Akt-1 or extracellular-regulated kinases-1 and -2 activation. Finally, it did not decrease urokinase expression and did not block the catalytic activity of urokinase. In conclusion, our results demonstrate that trans-resveratrol decreases hepatocyte growth factor-induced HepG2 cell invasion by an as yet unidentified post-receptor mechanism.

Antineoplastic Agents, Phytogenic↗
PubMed2001

Early activation of hepatic stellate cells and perisinusoidal extracellular matrix changes during ex vivo pig liver perfusion.

In previous works, we observed during liver transplantation procedure, the early activation of hepatic stellate cells (HSC) which acquire alpha-smooth muscle (SM) actin expression. In this study, we evaluated changes in HSC and in perisinusoidal extracellular matrix during ex vivo pig liver perfusion. Under general anesthesia, pig livers were flushed and removed, and then perfused ex vivo for 6 h with homologous blood. Liver biopsies were taken before and after washout, at 5 min perfusion, and then hourly. Tissues were processed for immunohistochemistry, immunofluorescence, confocal microscopy, in situ hybridization and electron microscopy. Before and after liver washout, alpha-SM actin was present in vessel walls but in very few lobular HSC. After 1 h perfusion, a strong reactivity for alpha-SM actin was present in HSC, particularly along dilated sinusoids. At the ultrastructural level, numerous microfilament bundles appeared in HSC cytoplasmic processes. During perfusion, type I and type IV collagens, type III procollagen, and fibronectin acquired a looser organisation in relation with the enlargement of perisinusoidal spaces; laminin appeared in perisinusoidal spaces around portal areas and fibrillin deposits increased. In situ hybridization studies showed an increase of the type I procollagen mRNA expression mainly in portal tracts and septa. Ex vivo liver perfusion induces: 1) an early activation of HSC which acquire the expression of alpha-SM actin, and 2) significant changes in the perisinusoidal extracellular matrix. These results are compatible with the view that HSC function as liver specific pericytes participating in the regulation of sinusoidal blood pressure.

Actin Cytoskeleton↗
PubMed2000

Paradoxical pro-invasive effect of the serine proteinase inhibitor tissue factor pathway inhibitor-2 on human hepatocellular carcinoma cells.

We have previously shown that human liver myofibroblasts promote in vitro invasion of human hepatocellular carcinoma (HCC) cells through a hepatocyte growth factor (HGF)/urokinase/plasmin-dependent mechanism. In this study, we demonstrate that myofibroblasts synthesize the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2). Despite the fact that recombinant TFPI-2 readily inhibits plasmin, we show that it potentiates HGF-induced invasion of HCC cells and is capable of inducing invasion on its own. Furthermore, HCC cells stably transfected with a TFPI-2 expression vector became spontaneously invasive. HCC cells express tissue factor and specifically factor VII. Addition of an antibody to factor VII abolished the pro-invasive effect of TFPI-2. We suggest that TFPI-2 induces invasion following binding to a tissue factor-factor VIIa complex preformed on HCC cells. Our data thus demonstrate an original mechanism of cell invasion that may be specific for liver tumor cells.

Animals↗
PubMed2000

Deactivation of cultured human liver myofibroblasts by trans-resveratrol, a grapevine-derived polyphenol.

Liver myofibroblasts are major actors in the development of liver fibrosis and cancer progression. There is a large interest in drugs that might deactivate these cells. Many studies have shown that the grapevine-derived polyphenol, trans-resveratrol, and other stilbenes have therapeutic potential in some diseases. In this work, we have studied the effect of grapevine polyphenols on cultured human liver myofibroblasts. We have shown that trans-resveratrol profoundly affects myofibroblast phenotype. Trans-resveratrol induced morphological modifications. It markedly reduced proliferation of myofibroblasts in a dose-dependent manner. Trans-resveratrol also decreased the expression of alpha smooth muscle actin (alpha-SMA) without affecting vimentin or beta-cytoplasmic actin expression. It decreased myofibroblast migration in a monolayer wounding assay. We also showed that trans-resveratrol inhibited the messenger RNA (mRNA) expression of type I collagen. Finally, it decreased the secretion of matrix metalloproteinase 2 (MMP-2). We conclude that trans-resveratrol can deactivate human liver myofibroblasts. In the second part of this study, we have shown that neither trans-piceid (a glycosylated analog) nor trans-piceatannol (a hydroxylated analog) reproduces trans-resveratrol effects on liver myofibroblasts. We finally show that, although trans-resveratrol decreases the proliferation of skin fibroblast and vascular smooth muscle cells, it does not affect their expression of alpha-SMA, which indicates some cell specificity.

Actins↗
PubMed2000

Role of myofibroblasts during normal tissue repair and excessive scarring: interest of their assessment in nephropathies.

Following injury, tissue repair process takes place involving inflammation, granulation tissue formation and scar constitution. Granulation tissue develops from the connective tissue surrounding the damaged area and contains vessels, inflammatory cells, fibroblasts and myofibroblasts. Myofibroblasts play an important role in many tissue injuries and fibrocontractive diseases. The process of normal wound repair after tissue injury follows a closely regulated sequence including the activation and the proliferation of fibroblastic cells. In pathological situations, the normal resolution stages are abrogated and the proliferation of myofibroblasts continues, inducing excessive accumulation of extracellular matrix. The differentiation of fibroblastic cells into myofibroblasts is an early event in the development of tissue fibrosis. Myofibroblastic cells express smooth muscle cytoskeletal markers (alpha-smooth muscle actin in particular) and participate actively in the production of extracellular matrix. The evaluation of myofibroblast differentiation in renal biopsies would be useful for histopathologists to appreciate the intensity of tissue injury and particularly to predict the long term outcome of some nephropathies. Immunohistochemical studies for alpha-smooth muscle actin should be made systematically in renal tissue biopsies. Myofibroblastic differentiation appears to play a significant role in the progression of renal failure and seems to be a useful marker of progressive disease.

Animals↗
PubMed1999

Mechanical forces induce scar remodeling. Study in non-pressure-treated versus pressure-treated hypertrophic scars.

Reparative process of second and third degree burns usually results in hypertrophic scar formation that can be treated by pressure. Although this method is efficient, its mechanisms of action are not known. In this work, we have studied the histological organization of hypertrophic scars submitted to pressure. Skin biopsies were performed 2 to 7 months after the onset of treatment in two adjacent regions of the scar, non-pressure- or pressure-treated and analyzed by immunohistochemistry and transmission electron microscopy for extracellular matrix organization and cellular morphology. In non-pressure-treated regions, fibrillin deposits did not present the classical candelabra-like pattern under epidermis and were reduced in dermis; in pressure-treated regions the amount was increased compared to non-pressure-treated regions but the organization was still disturbed. In non-pressure-treated regions, elastin was present in patch deposits; in pressure-treated regions elastin formed fibers, smaller than in normal dermis. Tenascin was present in the whole dermis in non-pressure-treated regions, whereas in pressure-treated regions it was observed only under epidermis and around vessels, as in normal skin. alpha-Smooth muscle actin-expressing myofibroblasts were absent in normal skin, present in large amounts in non-pressure-treated regions, and almost absent in pressure-treated regions. The disturbed ultrastructural organization of dermal-epidermal junction observed in non-pressure-treated regions disappeared after pressure therapy; typical features of apoptosis in fibroblastic cells and morphological aspects of collagen degradation were observed in pressure-treated regions. Our results show that, in hypertrophic scars, pressure therapy restores in part the extracellular matrix organization observed in normal scar and induces the disappearance of alpha-smooth muscle actin-expressing myofibroblasts, probably by apoptosis. We suggest that the pressure acts by accelerating the remission phase of the postburn reparative process.

Adolescent↗
PubMed1999

Direct evidence that hepatocyte growth factor-induced invasion of hepatocellular carcinoma cells is mediated by urokinase.

BACKGROUND/AIMS: We have shown that hepatocyte growth factor secreted by human hepatic myofibroblasts increased the in vitro invasion of the hepatocarcinoma cell line HepG2 through Matrigel. Our aim in this study was to evaluate the role of urokinase in this process. METHODS: Expression of urokinase in HepG2 cells was measured by Northern blot and zymography, and plasminogen activation was shown by a chromogenic substrate assay. Cell invasion was assayed on Matrigel-coated filters. Urokinase and urokinase receptor transcripts in hepatocarcinoma were detected by reverse transcription-polymerase chain reaction. Activated hepatocyte growth factor was detected by Western blot with a hepatocyte growth factor-beta chain-specific antibody. RESULTS: HepG2 cells expressed urokinase mRNA and secreted active urokinase. Urokinase expression was enhanced by hepatocyte growth factor at the protein and mRNA level. Notably, cell-surface-associated urokinase was increased 22-fold by hepatocyte growth factor. Hepatocyte growth factor also increased urokinase receptor mRNA expression. B428, a urokinase inhibitor, decreased by up to 70% HepG2 invasion induced by myofibroblasts and by 90% that induced by recombinant hepatocyte growth factor. This was not due to a decrease in the generation of activated hepatocyte growth factor by myofibroblasts. Finally, all 17 hepatocarcinoma samples tested expressed urokinase and urokinase receptor transcripts. CONCLUSION: Hepatocyte growth factor-dependent, myofibroblasts-induced invasion of HepG2 cells is secondary to the induction of urokinase expression on tumor cells.

Carcinoma, Hepatocellular↗
PubMed1999

Effect of pentoxifylline on early proliferation and phenotypic modulation of fibrogenic cells in two rat models of liver fibrosis and on cultured hepatic stellate cells.

BACKGROUND/AIMS: During liver fibrosis, different fibroblastic cells, i.e. hepatic stellate cells (HSCs) or portal fibroblasts, are involved in the development of lesions, and acquire myofibroblastic differentiation. We investigated, in the rat, whether pentoxifylline can influence the early phase of fibrogenesis in two animal models of fibrosis induced by either carbon tetrachloride (CCl4) plus acetone (given twice) or bile duct ligation. METHODS: The fibroproliferative response and myofibroblastic phenotypic modulation were evaluated by PCNA and alpha-smooth muscle (alpha-SM) actin immunohistochemistry, respectively, in livers taken 24 h after the last CCl4 treatment or 72 h after bile duct ligation. Desmin expression was also measured, and inflammation was evaluated by ED-1 staining. Furthermore, proliferation and alpha-SM actin expression were studied in cultured HSCs after pentoxifylline treatment. RESULTS: In the CCl4-acetone groups, pretreatment with pentoxifylline decreased the proliferative response and expression of alpha-SM actin in the HSCs. Similarly, pentoxifylline reduced the proliferation and myofibroblastic differentiation of portal fibroblasts after bile duct ligation. Pentoxifylline reduced ED-1 expression, particularly in the CCl4 model, where there was significant inflammation. In cultured pentoxifylline-treated HSCs, both proliferation and alpha-SM actin expression were decreased. CONCLUSIONS: In both animal models of fibrosis, during the early stages of tissue injury, pentoxifylline was able to reduce fibroproliferation and myofibroblastic differentiation and to reduce hepatocellular damage and the inflammatory response, particularly in the toxin-induced model. In culture, alpha-SM actin expression decreased in both growing and quiescent HSCs treated with pentoxifylline, indicating that the drug may also exert a direct effect on hepatic fibrogenic cells.

Acetone↗
PubMed1999

Long-term administration of interferon-alpha in non-responder patients with chronic hepatitis C: follow-up of liver fibrosis over 5 years.

In chronic hepatitis C, previous data have shown that short-term treatment with interferon-alpha (IFN-alpha) can reduce collagen deposition in the liver independently of the viral response. The aim of this work was to determine, in non-responder patients, the long-term effect of IFN-alpha on liver fibrosis according to the total administered dose and the fibrotic stage. Fibrosis was investigated on liver biopsies from 24 non-responder patients with chronic hepatitis C retreated with successive courses of IFN-alpha. The degree of liver fibrosis was assessed on three successive biopsies, performed before IFN-alpha treatment and 1 and 5 years later, in 13 and 11 patients, respectively, treated for less (mean: 7.5 months, 313 MU) and more (mean: 21.8 months, 791 MU) than 1 year. For each biopsy, fibrosis was assessed using a histological semiquantitative fibrosis scoring system and by morphometry after picrosirius red staining. Regardless of the dose and duration of IFN-alpha therapy, a slight decrease of fibrosis was observed in patients 5 years after starting treatment. In cirrhotic patients, a short treatment induced an improvement followed by a relapse of fibrosis in 57%, and only 43% of patients showed constant collagen regression over the 5 years of follow-up. On the contrary, after prolonged therapy, a progressive and significant decrease occurred throughout the follow-up period in all patients (P = 0.045). Long-term treatment with IFN-alpha is therefore associated with regression of liver fibrosis, particularly in cirrhotic patients. These promising results need to be confirmed in a larger series of patients.

Adult↗