An improved method for determining specific radioactivities of proline-14C and hydroxyproline-14C in collagen and in noncollagenous proteins

Curcumin inhibition of bleomycin-induced changes in lung collagen synthesis, deposition and assembly

BACKGROUND

Idiopathic pulmonary fibrosis is characterized by progressive lung tissue remodeling and disproportionate deposition of collagenous proteins with limited therapeutic interventions. The purpose of this study was to determine whether curcumin inhibits bleomycin (BLM)-induced increases in synthesis, degradation and cross-linking of lung collagen in rats.

METHODS AND RESULTS

Following a single intratracheal instillation of BLM to rats (0.75 U/100 g, sacrificed 3, 5, 7, 14 and 28 days post-BLM), lung collagen synthesis (determined by incorporation of ³H-proline) and deposition (determined by lung hydroxyproline content) progressively increased at days 7, 14 and 28 post-BLM injection. Lung lavage fluid hydroxyproline and collagenase levels (a measure of collagen turnover) were increased in BLM rats compared with control groups. In addition, BLM instillation resulted in increased concentrations of collagenase and collagenolytic cathepsin in the lungs. Furthermore, increased cross-linking (as determined by aldehyde content of acid soluble collagen), and decreased susceptibility of fibrotic lung insoluble collagen to denaturing agents occurred in BLM-injured lungs. Significant increases in alveolar macrophage (AM) release of transforming growth factor-β1 (TGF-β1) were noted at various time points (days 3, 5, 7, 14 and 28 post-BLM) during the development and progression of lung fibrosis in rats. Curcumin treatment to BLM rats (300 mg/kg 10 days before and daily thereafter throughout the experimental time period) was associated with marked reductions in lung collagen synthesis and deposition, BALF and lung collagenase activity, BALF hydroxyproline content and lung collagenolytic levels. Additionally, reduced levels of collagen cross-linking and enhanced susceptibility of insoluble lung collagen to denaturing agents were observed in curcumin-treated BLM rats. Finally, curcumin inhibited BLM-induced increases in AM production of TGF-β1.

CONCLUSIONS

Our data demonstrate for the first time that curcumin prevents fibrotic deposits by modulating collagen turnover, assembly and deposition in BLM-instilled rat lungs, and that curcumin treatment protects against BLM activation of macrophages by suppressing the release of TGF-β1.

Degradation of the extracellular matrix is part of the pathology of ulcerative colitis

The scientific value of re-analyzing existing datasets is often proportional to the complexity of the data. Proteomics data are inherently complex and can be analyzed at many levels, including proteins, peptides, and post-translational modifications to verify and/or develop new hypotheses. In this paper, we present our re-analysis of a previously published study comparing colon biopsy samples from ulcerative colitis (UC) patients to non-affected controls. We used a different statistical approach, employing a linear mixed-effects regression model and analyzed the data both on the protein and peptide level. In addition to confirming and reinforcing the original finding of upregulation of neutrophil extracellular traps (NETs), we report novel findings, including that Extracellular Matrix (ECM) degradation and neutrophil maturation are involved in the pathology of UC. The pharmaceutically most relevant differential protein expressions were confirmed using immunohistochemistry as an orthogonal method. As part of this study, we also compared proteomics data to previously published mRNA expression data. These comparisons indicated compensatory regulation at transcription levels of the ECM proteins we identified and open possible new avenues for drug discovery.

Interstitial collagen turnover during airway remodeling in acute and chronic experimental asthma

Asthma airway remodeling is characterized by the thickening of the basement membrane (BM) due to an increase in extracellular matrix (ECM) deposition, which contributes to the irreversibility of airflow obstruction. Interstitial collagens are the primary ECM components to be increased during the fibrotic process. The aim of the present study was to examine the interstitial collagen turnover during the course of acute and chronic asthma, and 1 month after the last exposure to the allergen. Guinea pigs sensitized to ovalbumin (OVA) and exposed to 3 further OVA challenges (acute model) or 12 OVA challenges (chronic model) were used as asthma experimental models. A group of animals from either model was sacrificed 1 h or 1 month after the last OVA challenge. Collagen distribution, collagen content, interstitial collagenase activity and matrix metalloproteinase (MMP)-1, MMP-13 and tissue inhibitor of metalloproteinase (TIMP)-1 protein expression levels were measured in the lung tissue samples from both experimental models. The results revealed that collagen deposit in bronchiole BM, adventitial and airway smooth muscle layers was increased in both experimental models as well as lung tissue collagen concentration. These structural changes persisted 1 month after the last OVA challenge. In the acute model, a decrease in collagenase activity and in MMP-1 concentration was observed. Collagenase activity returned to basal levels, and an increase in MMP-1 and MMP-13 expression levels along with a decrease in TIMP-1 expression levels were observed in animals sacrificed 1 month after the last OVA challenge. In the chronic model, there were no changes in collagenase activity or in MMP-13 concentration, although MMP-1 expression levels increased. One month later, an increase in collagenase activity was observed, although MMP-1 and TIMP-1 levels were not altered. The results of the present study suggest that even when the allergen challenges were discontinued, and collagenase activity and MMP-1 expression increased, fibrosis remained, contributing to the irreversibility of bronchoconstriction.

The chronic enteropathogenic disease schistosomiasis

Schistosomiasis is a chronic enteropathogenic disease caused by blood flukes of the genus Schistosoma. The disease afflicts approximately 240 million individuals globally, causing approximately 70 million disability-adjusted life years lost. Chronic infections with morbidity and mortality occur as a result of granuloma formation in the intestine, liver, or in the case of Schistosoma haematobium, the bladder. Various methods are utilized to diagnose and evaluate liver fibrosis due to schistosomiasis. Liver biopsy is still considered the gold standard, but it is invasive. Diagnostic imaging has proven to be an invaluable method in assessing hepatic morbidity in the hospital setting, but has practical limitations in the field. The potential of non-invasive biological markers, serum antibodies, cytokines, and circulating host microRNAs to diagnose hepatic fibrosis is presently undergoing evaluation. This review provides an update on the recent advances made with respect to gastrointestinal disease associated with chronic schistosomiasis.

Graptopetalum paraguayense ameliorates chemical-induced rat hepatic fibrosis in vivo and inactivates stellate cells and Kupffer cells in vitro

Background

Graptopetalum paraguayense (GP) is a folk herbal medicine with hepatoprotective effects that is used in Taiwan. The aim of this study was to evaluate the hepatoprotective and antifibrotic effects of GP on experimental hepatic fibrosis in both dimethylnitrosamine (DMN)- and carbon tetrachloride (CCl₄)-induced liver injury rats.

Methods

Hepatic fibrosis-induced rats were fed with the methanolic extract of GP (MGP) by oral administration every day. Immunohistochemistry, biochemical assays, and Western blot analysis were performed. The effects of MGP on the expression of fibrotic markers and cytokines in the primary cultured hepatic stellate cells (HSCs) and Kupffer cells, respectively, were evaluated.

Results

Oral administration of MGP significantly alleviated DMN- or CCl₄-induced liver inflammation and fibrosis. High levels of alanine transaminase, aspartate transaminase, bilirubin, prothrombin activity and mortality rates also decreased in rats treated with MGP. There were significantly decreased hydroxyproline levels in therapeutic rats compared with those of the liver-damaged rats. Collagen I and alpha smooth muscle actin (α-SMA) expression were all reduced by incubation with MGP in primary cultured rat HSCs. Furthermore, MGP induced apoptotic cell death in activated HSCs. MGP also suppressed lipopolysaccharide-stimulated rat Kupffer cell activation by decreasing nitric oxide, tumor necrosis factor-α and interleukin-6 production, and increasing interleukin-10 expression.

Conclusions

The results show that the administration of MGP attenuated toxin-induced hepatic damage and fibrosis in vivo and inhibited HSC and Kupffer cell activation in vitro, suggesting that MGP might be a promising complementary or alternative therapeutic agent for liver inflammation and fibrosis.

Truncated active human matrix metalloproteinase-8 delivered by a chimeric adenovirus-hepatitis B virus vector ameliorates rat liver cirrhosis

BACKGROUND

Liver cirrhosis is a potentially life-threatening disease caused by progressive displacement of functional hepatocytes by fibrous tissue. The underlying fibrosis is often driven by chronic infection with hepatitis B virus (HBV). Matrix metalloproteinases including MMP-8 are crucial for excess collagen degradation. In a rat model of liver cirrhosis, MMP-8 delivery by an adenovirus (Ad) vector achieved significant amelioration of fibrosis but application of Ad vectors in humans is subject to various issues, including a lack of intrinsic liver specificity.

METHODS

HBV is highly liver-specific and its principal suitability as liver-specific gene transfer vector is established. HBV vectors have a limited insertion capacity and are replication-defective. Conversely, in an HBV infected cell vector replication may be rescued in trans by the resident virus, allowing conditional vector amplification and spreading. Capitalizing on a resident pathogen to help in its elimination and/or in treating its pathogenic consequences would provide a novel strategy. However, resident HBV may also reduce susceptibility to HBV vector superinfection. Thus a size-compatible truncated MMP-8 (tMMP8) gene was cloned into an HBV vector which was then used to generate a chimeric Ad-HBV shuttle vector that is not subject to superinfection exclusion. Rats with thioacetamide-induced liver cirrhosis were injected with the chimera to evaluate therapeutic efficacy.

RESULTS

Our data demonstrate that infectious HBV vector particles can be obtained via trans-complementation by wild-type virus, and that the tMMP8 HBV vector can efficiently be shuttled by an Ad vector into cirrhotic rat livers. There it exerted a comparable beneficial effect on fibrosis and hepatocyte proliferation markers as a conventional full-length MMP-8Ad vector.

CONCLUSIONS

Though the rat cirrhosis model does not allow assessing in vivo HBV vector amplification these results advocate the further development of Ad-HBV vectors for liver-specific gene therapy, including and perhaps particularly for HBV-related disease.

Effect of antioxidant treatment on fibrogenesis in rats with carbon tetrachloride-induced cirrhosis

Aim. This study aimed to assess the antioxidant activity of quercetin (Q) in an experimental model of cirrhosis induced by CCl₄ inhalation. Materials and Methods. We used 25 male Wistar rats (250 g) that were divided into 3 groups: control (CO), CCl₄, and CCl₄ + Q. The rats were subjected to CCl₄ inhalation (2x/week) for 16 weeks, and they received phenobarbital in their drinking water at a dose of 0.3 g/dL as a P450 enzyme inducer. Q (50 mg/Kg) was initiated intraperitoneally at 10 weeks of inhalation and lasted until the end of the experiment. Statistical analysis was by ANOVA Student Newman-Keuls (mean ± SEM), and differences were considered statistically significant when P < 0.05. Results. After treatment with quercetin, we observed an improvement in liver complications, decreased fibrosis, as analyzed by picrosirius for the quantification of collagen, and decreased levels of matrix metalloproteinase 2 (MMP-2) compared with the CCl₄ group. It also reduced oxidative stress, as confirmed by the decrease of substances reacting to thiobarbituric acid (TBARS), the increased activity of antioxidant enzymes, and the reduced glutathione ratio and glutathione disulfide (GSH/GSSG). Conclusion. We suggest that the use of quercetin might be promising as an antioxidant therapy in liver fibrosis.

Use of a graft of demineralized bone matrix along with TGF-β1 leads to an early bone repair in dogs

Tibia fractures are common in small animal practice. Over the past decade, improvements to animal internal fracture fixation have been developed. TGF-β1 has been shown to be crucial in the development, induction and repair of bone. In present study, we investigate the effect of local application of a graft demineralized bone matrix (DBM) along with TGF-β1 in a model of open osteotomy induced experimentally in dogs. Tibia fracture was brought about by using an open osteotomy model in young male dogs. Fracture repair was evaluated by a histological and biochemical analysis. Collagen content, proteolytic activity and urokinase-type plasminogen activator (uPA) expression were analyzed at the end of the study. Radiographic analysis, alkaline phosphatase and hematological evaluation were performed weekly. At the fifth week, there was an improvement and restoration of bone architecture in animals treated with a graft containing TGF-β1 (5 ng/ml) compared with the control and graft groups, as was evidenced by the presence of an early formation of wide callus and bone regeneration. In addition, local application of TGF-β1 led to an increase in collagen and proteolytic activity. More immunopositive osteoclast and mesenchymal cells were found in bone tissue from animals treated with TGF-β1 as compared with the control group. No changes in alkaline phosphatase, hematological and clinical parameters were observed. This study shows that the combined use of DBM along with TGF-β1 is able to improve and accelerate the bone repair.

Melatonin protects the liver and erythrocytes against oxidative stress in cirrhotic rats

CONTEXT

Cirrhosis is a progressive chronic hepatopathy which constitutes an irreversible stage of liver dysfunction.

OBJECTIVES

To evaluate the oxidative stress in the blood of cirrhotic rats treated with the antioxidant melatonin.

METHODS

Cirrhosis was induced through inhalation of carbon tetrachloride. Liver integrity was evaluated by measuring serum enzymes, oxidative damage measured by lipoperoxidation, and antioxidant enzyme activity in erythrocytes. Lipoperoxidation, total nitrates, collagen, and histology by picrosirius staining were evaluated in the livers of these animals (n = 15), which were divided in three groups: control, carbon tetrachloride, and carbon tetrachloride + melatonin. Melatonin (20 mg/kg) was administered intraperitoneal from week 10 of carbon tetrachloride inhalation. In order to shorten the cirrhosis induction time, phenobarbital (0.3 g/L) was added to the animals' drinking water.

RESULTS

A significant impairment in the liver integrity of melatonin-treated animals as compared to cirrhotic animals was observed. In rat erythrocytes and liver, lipoperoxidation was significantly increased in the cirrhotic rats as compared to controls, as measured through thiobarbituric acid reactive substances, and significantly decreased in melatonin-treated animals as compared to cirrhotic ones. In blood, a decrease in superoxide dismutase and glutathione peroxidase enzymes was detected in the cirrhotic group as compared to the control group, with increased superoxide dismutase activity when melatonin was administered. A reduction in the levels of total nitrates was detected in the hepatic tissue of the animals in the carbon tetrachloride group as compared to the control group and an increase of these levels in the carbon tetrachloride + melatonin group. As for hepatic collagen, we found a significant increase in the carbon tetrachloride group as compared to the controls and a regression of these values in the treated group. In histology, the rats in the carbon tetrachloride group showed fibrosis and formation of fibrotic nodules, characterizing liver cirrhosis; there was reduction of nodules and fibrosis in the melatonin treated group.

CONCLUSION

The data allow us to suggest that the observed oxidative stress is related to the damages caused by carbon tetrachloride and that the use of melatonin can minimize these damages.

Combinatorial gene therapy renders increased survival in cirrhotic rats

Background

Liver fibrosis ranks as the second cause of death in México's productive-age population. This pathology is characterized by acummulation of fibrillar proteins in hepatic parenchyma causing synthetic and metabolic disfunction. Remotion of excessive fibrous proteins might result in benefit for subjects increasing survival index. The goal of this work was to find whether the already known therapeutical effect of human urokinase Plasminogen Activator and human Matrix Metalloprotease 8 extends survival index in cirrhotic animals.

Methods

Wistar rats (80 g) underwent chronic intoxication with CCl₄: mineral oil for 8 weeks. Cirrhotic animals were injected with a combined dose of Ad-delta-huPA plus Ad-MMP8 (3 × 10¹¹ and 1.5 × 10¹¹ vp/Kg, respectively) or with Ad-beta-Gal (4.5 × 10¹¹) and were killed after 2, 4, 6, 8 and 10 days. Then, liver and serum were collected. An additional set of cirrhotic animals injected with combined gene therapy was also monitored for their probability of survival.

Results

Only the cirrhotic animals treated with therapeutical genes (Ad-delta-huPA+Ad-MMP-8) showed improvement in liver fibrosis. These results correlated with hydroxyproline determinations. A significant decrement in alpha-SMA and TGF-beta1 gene expression was also observed. Cirrhotic rats treated with Ad-delta-huPA plus Ad-MMP8 had a higher probability of survival at 60 days with respect to Ad-beta-Gal-injected animals.

Conclusion

A single administration of Ad-delta-huPA plus Ad-MMP-8 is efficient to induce fibrosis regression and increase survival in experimental liver fibrosis.

Adenoviral delivery of dominant-negative transforming growth factor beta type II receptor up-regulates transcriptional repressor SKI-like oncogene, decreases matrix metalloproteinase 2 in hepatic stellate cell and prevents liver fibrosis in rats

BACKGROUND

Dominant-negative transforming growth factor beta type II receptor (TbetaRIIDeltacyt) is a protein that blocks transforming growth factor (TGF-beta) signaling. Because the consequences of blocking TGF-beta have not been completely elucidated in liver fibrosis, we analysed the effects of adenoviral delivery of TbetaRIIDeltacyt on profibrogenic genes and matrix metalloproteinase (MMP) proteins, as well as on TGF-beta signal repressor SKI-like oncogene (SnoN), in cultured hepatic stellate cells (HSCs) and in a rat model of liver fibrosis.

METHODS

To induce liver fibrosis, rats were treated with thioacetamide for 7 weeks and administrated once with Ad-TbetaRIIDeltacyt or Ad-betagal through the iliac vein. Fibrosis was measured by morphometric analysis. We evaluated SnoN by western blot, immunocytochemistry and immunohistochemistry; MMP activity was determined by zymography and profibrogenic gene expression by the real-time reverse transcriptase-polymerase chain reaction in cultured HSCs and liver tissue.

RESULTS

Profibrogenic gene expression of collagen alpha1 (I), TGF-beta1, platelet-derived growth factor-B, plasminogen activator inhibitor (PAI)-1, tissue inhibitor of matrix metalloproteinase-1 and MMP-2 was down-regulated; whereas MMP-3 was over-expressed in response to Ad-TbetaRIIDeltacyt in HSCs. Moreover, zymography assays corroborated MMP-2 and MMP-3 changes in activity. Surprisingly, anti-TGF-beta molecular intervention increased nuclear SnoN in HSCs. In vivo, Ad-TbetaRIIDeltacyt reduced liver fibrosis, increased nuclear SnoN in sinusoidal cells, and also produced significant suppression in collagen alpha1 (I), TGF-beta1, PAI-1, MMP-2 and over-expression in MMP-3 in thioacetamide-intoxicated animals.

CONCLUSIONS

The results obtained in the present study suggest that the molecular mechanism for the blocking effects of Ad-TbetaRIIDeltacyt in TGF-beta signaling acts via up-regulation of the transcriptional repressor SnoN, which antagonizes TGF-beta signaling (TGF-beta/Smad-pathway inhibitor). Consequently, profibrogenic genes are down-regulated.

Partial Hepatectomy–Induced Regeneration Accelerates Reversion of Liver Fibrosis Involving Participation of Hepatic Stellate Cells

Hepatic fibrosis underlies most types of chronic liver diseases and is characterized by excessive deposition of extracellular matrix (ECM), altered liver architecture, and impaired hepatocyte proliferation; however, the fibrotic liver can still regenerate after partial hepatectomy (PH). Therefore, the present study was aimed at addressing whether a PH-induced regeneration normalizes ECM turnover and the possible involvement of hepatic stellate cells (HSC) during resolution of a pre-established fibrosis. Male Wistar rats were rendered fibrotic by intraperitoneal administration of swine serum for 9 weeks and subjected afterwards to 70% PH or sham-operation. Histological and morphometric analyses were performed, and parameters indicative of cell proliferation, collagen synthesis and degradation, and activation of HSC were determined. Liver collagen content was reduced to 75% after PH in cirrhotic rats when compared with sham-operated cirrhotic rats. The regenerating fibrotic liver oxidized actively free proline and had diminished transcripts for α-1 (I) collagen mRNA, resulting in decreased collagen synthesis. PH also increased collagenase activity, accounted for by higher amounts of pro-MMP-9, MMP-2, and MMP-13, which largely coincided with a lower expression of TIMP-1 and TIMP-2. Therefore, an early decreased collagen synthesis, mild ECM degradation, and active liver regeneration were followed by higher collagenolysis and limited deposition of ECM, probably associated with increased mitochondrial activity. Activated HSC readily increased during liver fibrosis and remained activated after liver regeneration, even during fibrosis resolution. In conclusion, stimulation of liver regeneration through PH restores the balance in ECM synthesis/degradation, leading to ECM remodeling and to an almost complete resolution of liver fibrosis. As a response to the regenerative stimulus, activated HSC seem to play a controlling role on ECM remodeling during experimental cirrhosis in rats. Therefore, pharmacological approaches for the resolution of liver fibrosis by blocking HSC activation should also evaluate possible effects on liver cell proliferation.

Efeitos da quercetina na lesão pulmonar induzida por bleomicina: um estudo preliminar

OBJETIVO: Investigar os efeitos da quercetina em um modelo de inflamação pulmonar e fibrose induzidas por bleomicina. MÉTODOS: Setenta e nove hamsters machos adultos foram randomizados para aplicação de injeções pelas vias intratraqueal (IT) e intraperitoneal (IP) em quatro configurações: veículo IP/salina IT (grupo VS, n = 16); salina IT/quercetina IP (grupo QS, n = 16); bleomicina IT/veículo IP (grupo VB, n = 27); e bleomicina IT/quercetina IP (grupo QB, n = 20). A quercetina e a bleomicina foram aplicadas em doses de 30 mg/kg/dia e 10 U/kg, respectivamente.A quercetina foi iniciada/suspensa 3 dias antes/14 dias depois das injeções IT. RESULTADOS: A taxa de mortalidade do grupo VB foi significantemente superior à dos demais grupos (44% vs. VS: 0%; QS: 0%; QB: 15%). O grupo VB exibiu níveis pulmonares de substâncias reativas ao ácido tiobarbitúrico (× 10-2 nmol/mg) significativamente maiores (6,6 ± 1,3 vs. VS: 5,5 ± 0,8; QS: 2,5 ± 0,6; e QB: 5,8 ± 0,6).Os grupos VB/QB mostraram níveis pulmonares de glutationa reduzida (× 10-2 nmol/mg) significativamente menores que os dos grupos VS/QS (28,9 ± 13,8/28,6 ± 14,8 vs. 43,9 ± 16,0/51,1 ± 20,3) e níveis de hidroxiprolina (mg/g) significativamente maiores (201,6 ± 37,3/177,6 ± 20,3 vs. 109,6 ± 26,1/117,5 ± 32,0). CONCLUSÕES: Em um modelo animal de lesão pulmonar, a quercetina exibiu efeitos antiinflamatórios que são relacionados, pelo menos em parte, a suas propriedades antioxidantes.

Role of N-acetylcysteine on fibrosis and oxidative stress in cirrhotic rats

BACKGROUND: Hepatic cirrhosis is the final stage of liver dysfunction, characterized by diffuse fibrosis which is the main response to the liver injury. The inhalatory carbon tetrachloride is an effective experimental model that triggers cirrhosis and allows to obtain histological and physiological modifications similar to the one seen in humans. AIM: To investigate the effects of N-acetylcysteine (NAC) on the fibrosis and oxidative stress in the liver of cirrhotic rats, analyzing liver function tests, lipoperoxidation, activity of glutathione peroxidase enzyme, collagen quantification, histopathology, as well as the nitric oxide role. METHODS: The animals were randomly in three experimentals groups: control (CO); cirrhotic (CCl4) and CCl4 + NAC. Evaluate the lipid peroxidation, the glutathione peroxidase enzyme, the collagen and the expression of inducible nitric oxide synthase (iNOS). RESULTS: The cirrhotic group treated with N-acetylcysteine showed trough the histological analysis and collagen quantification lower degrees of fibrosis. This group has also shown less damage to the cellular membranes, less decrease on the glutathione peroxidase levels and less expression of inducible nitric oxide synthase when matched with the cirrhotic group without treatment. CONCLUSION: N-acetylcysteine seams to offer protection against hepatic fibrosis and oxidative stress in cirrhotic rat livers.

Genistein modifies liver fibrosis and improves liver function by inducing uPA expression and proteolytic activity in CCl4-treated rats

AIM

To evaluate the effect of genistein on the fibrosis and matrix degradation caused by experimentally induced fibrosis in rats.

METHODS

Hepatic fibrosis was brought about by chronic administration of carbon tetrachloride to rats. To evaluate the effect of genistein on liver fibrosis and function, total collagen content and proteolytic activity in the liver were quantified. Urokinase-type plasminogen activator (uPA) expression during experimental fibrosis was localized by immunohistochemistry. Histopathological changes were evaluated using light and electron microscopy.

RESULTS

Animals with fibrosis and treated with genistein showed an important reduction (73%) in hepatic collagen content as well as an improvement in liver function (p < 0.001). Genistein increased the capacity of the liver to degrade type I collagen and Matrigel (3.1- and 3.7-fold, respectively; p < 0.001) in animals with liver fibrosis. Genistein increased the number of uPA-immunoreactive cells. The increase in the uPA expression correlated with an increase in proteolytic activity. Histological analysis revealed a reduction in the number of fiber septa in pericentral and perisinusoidal areas. Transmission electron micrographs of livers from animals with fibrosis and treated with genistein showed a reduction in the number of hepatic stellate cells activated and a smaller number of collagen fibers.

CONCLUSION

Genistein is able to improve the liver after injury and fibrosis induced by chronic administration of carbon tetrachloride. This finding suggests that genistein has antifibrogenic potential and could therefore be useful for treating chronic liver disease.

Effects of low-level laser therapy (LLLT) on the nuclear factor (NF)-kappaB signaling pathway in traumatized muscle

BACKGROUND AND OBJECTIVE

To investigate the effects of low-level laser therapy (LLLT) on nuclear factor kappa B (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) expression in an experimental model of muscle trauma.

STUDY DESIGN/MATERIALS AND METHODS

Injury to the gastrocnemius muscle in the rat was produced by a single impact blunt trauma. A low-level galium arsenide (Ga-As) laser (904 nm, 45 mW, and 5 J/cm2) was applied for 35 seconds duration, continuously.

RESULTS

Histological abnormalities with increase in collagen concentration, and oxidative stress were observed after trauma. This was accompanied by activation of NF-kappaB and upregulation of iNOS expression, whereas protein concentration of I kappa B alpha decreased. These effects were blocked by LLLT.

CONCLUSION

LLLT reduced the inflammatory response induced by trauma and was able to block the effects of reactive oxygen species (ROS) release and the activation of NF-kappaB. The associated reduction of iNOS overexpression and collagen production suggest that the NF-kappaB pathway may be a signaling route involved in the pathogenesis of muscle trauma.

Nitric oxide production in striatum and pallidum of cirrhotic rats

Ammonium and manganese are neurotoxic agents related to brain metabolic disturbances observed after prolonged liver damage. The aim of this study was to assess the production of nitric oxide (NO) in the brain of cirrhotic rats exposed to manganese. We induced cirrhosis by bile duct ligation for 4 weeks in rats. From brain, striatum and globus pallidus were dissected out, and NO synthase activity and the content of nitrites plus nitrates (NOx) were determined. In pallidum we found a diminished constitutive NO synthase activity from cirrhotic rats, independently of manganese exposure. This result was confirmed by low levels of NOx in the same brain area (P<0.05, two-way ANOVA). This finding was not related to protein expression of NO synthase since no differences were observed in immunoblot signals between cirrhotic and sham-operated animals. Results from present study suggest that the production of NO is reduced in basal ganglia during cirrhosis.

Low-level laser therapy (LLLT) prevents oxidative stress and reduces fibrosis in rat traumatized Achilles tendon

BACKGROUND AND OBJECTIVES

The present study investigated the effects of low-level laser therapy (LLLT) on oxidative stress and fibrosis in an experimental model of Achilles tendon injury induced by a single impact trauma.

STUDY DESIGN/MATERIALS AND METHODS

Male Wistar rats were randomly divided into four groups (n = 8): control, trauma, trauma+LLLT for 14 days, and trauma+LLLT for 21 days. Achilles tendon traumatism was produced by dropping down a load with an impact kinetic energy of 0.544 J. A low level Ga-As laser was applied with a 904 nm wavelength, 45 mW average power, 5 J/cm(2) dosage, for 35 seconds duration, continuously. Studies were carried out at day 21.

RESULTS

Histology showed a loss of normal architecture, with inflammatory reaction, angiogenesis, vasodilatation, and extracellular matrix formation after trauma. This was accompanied by a significant increase in collagen concentration when compared the control group. Oxidative stress, measured by the concentration of thiobarbituric acid reactive substances and hydroperoxyde-initiated chemiluminiscence, was also significantly increased in the trauma group. Administration of LLLT for 14 or 21 days markedly alleviated histological abnormalities reduced collagen concentration and prevented oxidative stress. Superoxide dismutase activity was significantly increased by LLLT treatment over control values.

CONCLUSION

LLLT by Ga-As laser reduces histological abnormalities, collagen concentration, and oxidative stress in an experimental model of Achilles tendon injury. Reduction of fibrosis could be mediated by the beneficial effects on the oxidant/antioxidant balance.

Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis

The phosphodiesterase-4 (PDE4) inhibitors may be an important target in the treatment of several inflammatory conditions. The anti-inflammatory effect of PDE4 inhibitors bears similarities with that of steroids, without interfering with the hypophysary-adrenal-axis. We compared the effect of rolipram, a selective PDE4 inhibitor, with steroids on the clinical course of experimental colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). Three groups of rats (n = 20) received TNBS. One group received methylprednisolone from day 7, another group received rolipram from the same day, and control group received no further treatment. On days 14 and 21 after TNBS instillation, sets of 10 rats underwent colonic dialysis to measure eicosanoid release. Colonic lesions were blindly scored, and colons were homogenized for quantification of myeloperoxidase (MPO) activity and collagen content. Concentration of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta1 (TGF-beta1) in colonic tissue was also measured. Both treatments reduced significantly the eicosanoid release and MPO activity. On day 14, both rolipram and methylprednisolone significantly reduced TNF-alpha content, but TGF-beta1 was only inhibited by rolipram. On day 21, lesion scores and collagen content were significantly reduced only in rolipram-treated group. In conclusion, PDE4 inhibition by rolipram markedly ameliorates the course of chronic colitis and it is superior to methylprednisolone in preventing late collagen deposition.

Vitamin E attenuates biochemical and morphological features associated with development of chronic pancreatitis

The objective was to investigate the effects of vitamin E on collagen deposition induced by Cyclosporin A (CsA) administration in rats with caerulein (Cr) pancreatitis. CsA transforms the fully regenerative, self-limited form of Cr pancreatitis into a chroniclike disease in conjunction with increased transforming growth factor (TGF)-beta and myofibroblast proliferation. Vitamin E inhibits TGF-beta release in mesangial cells and reduces CsA cytotoxicity. Wistar rats received CsA daily (20 mg/kg), and CR pancreatitis was induced on days 1 and 8 (Cr + CsA group). In a separate group, vitamin E (600 mg.kg(-1).day(-1)) was administered starting 4 days before CsA. Three other groups received either vehicle, CsA, or Cr alone. Thiobarbituric acid-reactive substance (TBARS), 8-isoprostanes, and hyaluronic acid were measured in plasma obtained on the day the animals were killed (day 15). Pancreases were weighed and processed for light microscopy to assess connective tissue and myofibroblast number. Pancreatic homogenates were also assayed for collagen (hydroxyproline) and TBARS content. TBARS, 8-isoprostane, and TGF-beta were elevated in CsA and Cr + CsA rats. Vitamin E treatment greatly decreased these parameters. Vitamin E also decreased the fall in pancreatic weight observed in Cr + CsA pancreas. Pancreatic hydroxyproline and plasma hyaluronic acid were increased in Cr + CsA rats but were effectively reduced by vitamin E. Morphology showed improvement in fibrosis score and a decreased number of myofibroblasts in vitamin E-treated rats. Vitamin E reduces oxidative stress and collagen deposition during the development of experimental chronic pancreatitis. Adjuvant antioxidants may be of value in the treatment of chronic pancreatitis.

Pirfenidone effectively reverses experimental liver fibrosis

BACKGROUND/AIMS

Our group has been involved in searching for different strategies to ameliorate hepatic cirrhosis. The aim of this study was to evaluate the effect of Pirfenidone in the reversion or prevention of cirrhosis experimentally induced in rats by chronic administration of CCl(4) and bile-duct ligation (BDL).

METHODS

Male cirrhotic Wistar rats (8 weeks of intoxication and then hepatotoxin was discontinued) received either oral saline or Pirfenidone at 500 mg/kg per day.

RESULTS

High levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase decreased significantly (P<0.001) in animals treated with Pirfenidone (n=11) with regard to saline-administrated animals (n=9). Prothrombin activity and bilirubins were also reduced. Computerized fibrosis index demonstrated a 70% decrease (P<0.001) along with less hydroxyproline content, reduction in activated HSC and higher active cell regeneration. A rearrangement of the parenchyma was also noted and gene expression of collagens I, III and IV, transforming growth factor beta-1, Smad-7, TIMP-1 and PAI-1 decreased considerably in treated animals. Cirrhotic rats in which CCl(4) was not discontinued displayed 40% liver fibrosis reduction. In a different cirrhosis model, 4-week BDL rats treated with the drug showed a significant 50% reduction in hepatic fibrosis (P<0.01).

CONCLUSIONS

This new drug might be useful in healing human disease.

Effect of an alpha-blocker (Nicergoline) and of a beta-blocker (Acebutolol) on the in vitro biosynthesis of vascular extracellular matrix

The effect of an alpha-blocking agent and of a beta-blocking agent on the biosynthesis of extracellular matrix macromolecules of the arterial wall was investigated. Rabbit aorta explants were cultured up to 48 hours with radioactive proline, lysine or glucosamine. In presence of these drugs, at concentration shown to be effective for the inhibition of platelet-endothelial cell interactions (10(-7) M), the incorporation of 14C proline in total macromolecular proline was higher than in macromolecular hydroxyproline suggesting a relatively higher rate of biosynthesis of non-collagenous proteins as compared to collagens. The alpha-blocking increased the incorporation of 14C proline in collagenous and non-collagenous proteins after 18 hours of incubation. beta-blocking also increased the incorporation of proline in macromolecular proline and hydroxyproline as compared to control cultures. Both increased the incorporation of 3H glucosamine in newly synthesised glycosaminoglycans. beta-blocking increased mainly the neosynthesis of heparan sulphate, alpha-blocking that of hyaluronan. The incorporation of 14C-lysine in crosslinked, insoluble elastin was not modified. These experiments confirm that alpha and beta-blocking agents can influence not only the tonus of aortic smooth muscle cells but also the relative rates of biosynthesis of extracellular matrix macromolecules. This effect should be taken in consideration for the evaluation of the long range effect of alpha and beta-blocking drugs on the vascular wall.

The flavonoid quercetin ameliorates liver damage in rats with biliary obstruction

BACKGROUND/AIMS

Our aim was to investigate whether the antioxidant quercetin might protect against liver injury in chronically biliary obstructed rats.

METHODS

Secondary biliary cirrhosis was induced by 28 days of bile duct obstruction. Animals received quercetin at 75, 150 and 300 micromol x kg body wt(-1) x day(-1) i.p. through the experimental period or at 150 micromol x kg body wt(-1) x day(-1) i.p. for the last 2 weeks.

RESULTS

Bile duct obstruction resulted in a decrease in the activities of antioxidant enzymes. Liver oxidised/reduced (GSSG/GSH) glutathione ratio, hepatic and mitochondrial thiobarbituric acid reactive substances (TBARS) and collagen content were significantly increased and a marked fibrosis and bile ductular proliferation was observed. Quercetin corrected the reduction in glutathione concentration and partially prevented the increase in collagen concentration, TBARS and GSSG/GSH ratio. Treatment resulted in a significant preservation of the activities of antioxidant enzymes, a less pronounced fibrosis and a marked inhibition of bile ductular proliferation. Maximal effects were reached with the intermediate quercetin dose given for 2 or 4 weeks.

CONCLUSIONS

Quercetin reduces liver oxidative damage, ductular proliferation and fibrosis in biliary-obstructed rats. These effects suggest that it might be a useful agent to preserve liver function in patients with biliary obstruction.

Protective effect of aminoguanidine in a murine model of pulmonary fibrosis induced by bleomycin

Aminoguanidine is a drug known for more than a century, which has been attracting increasing interest in recent years due to the discovery of new pharmacological properties. This study investigated the effects of aminoguanidine on the fibrotic response induced by intratracheal administration of bleomycin to rats. Three groups of animals were studied: Group A (n = 19) corresponded to the control group. Group B (n = 20) received 10 IU/kg bleomycin intratracheal, and Group C (n = 12) received the same amount of bleomycin as Group B followed by 50 mg/kg/day aminoguanidine bicarbonate for 4 weeks. Aminoguanidine led to significant reductions in total hydroxyproline content of the lungs in Group C compared to Group B (Group A: 1.83+/-0.14 mg x Group B: 3.46+/-0.36 mg x Group C: 2.09+/-0.22 mg). Morphometric collagen studies carried out on histological sections stained with Sirius red F3BA showed that aminoguanidine promoted a significant reduction of the area occupied by collagen in the axial and septal zones of the lungs (Axial region = Group A: 4.29+/-1.31% x Group B: 19.30+/-4.86% x Group C: 8.52+/-1.96%; Septal region = Group A: 0.15+/-0.06% x Group B: 0.61+/-0.21% x Group C: 0.15+/-0.06%). These results suggest that aminoguanidine is a potential therapeutic agent for the treatment and prevention of pulmonary fibrosis which is associated with different clinical conditions.

Curcumin treatment modulates collagen metabolism in isoproterenol induced myocardial necrosis in rats

This study was carried out to evaluate whether curcumin, a potent antioxidant, had any specific role in the synthesis and degradation of collagen in rat heart with myocardial necrosis, induced by isoproterenol.HCI (ISO). Myocardial necrosis was induced by administration of ISO (30 mg/100 g body weight subcutaneously twice at an interval of 24 h) and studies on collagen metabolism were carried out with curcumin (200 mg/kg) pre-and co-treatment with ISO. The incorporation of 14C-proline into collagen was studied as an index of collagen synthesis. The heart weight/body weight ratio,heart RNA/DNA ratio and protein were found to increase significantly in ISO administered animals. Curcumin pre- and co-treatment with ISO reversed these changes and attenuated the development of cardiac hypertrophy two weeks after the second dose of ISO. Increased fractional synthesis rate and enhanced degradation of newly synthesized collagen were observed in ISO administered animals. Curcumin pre- and co-treatment with ISO was noticed to decrease the degree of degradation of the existing collagen matrix and collagen synthesis, two weeks after the second dose of ISO. The observed effects could be due to free radical scavenging capacity and inhibition of lysosomal enzyme release by curcumin.

Improvement in liver fibrosis, functionality and hemodynamics in CCI4-cirrhotic rats after injection of the Liver Growth Factor

BACKGROUND/AIMS

Most substances used in experimental models of cirrhosis are chosen either as protectors of lipid peroxidation, as antifibrogenic agents or as vitamins, among others. In this report, we analyze the improvement produced, in established cirrhosis (CCl4 plus phenobarbital) in rats, by intraperitoneal injection of Liver Growth Factor, a hepatic mitogen with activity both in vivo and in vitro.

METHODS

Following confirmation of CCl4-induced cirrhosis, Liver Growth Factor (4.5 microg per ratx2 injections/week for 3 weeks) was administered to one group of rats (Cirr+LGF). The remaining rats (Cirr) received saline. The groups were compared in terms of serum enzymes, tissue damage, total liver collagen, collagenase activity, microsomal enzyme activities, splanchnic and systemic hemodynamics and portosystemic shunting.

RESULTS

Treatment of rats presenting CCl4-induced cirrhosis with Liver Growth Factor decreased serum aminotransferase levels and increased levels of serum albumin and total protein. The Liver collagen content was lower in rats treated with Liver Growth Factor (2.96 vs. 4.32 mg/g liver, p<0.01). Microscopic studies revealed that the livers of rats receiving Liver Growth Factor showed decreases in fibrosis, necrosis and inflammatory infiltration, as well as a recovery of architectural integrity. Liver function was improved after treatment with Liver Growth Factor, as indicated by the rate constant for elimination of aminopyrine, which increased from 0.0063 to 0.0170 (p<0.05). This increase was accompanied by a higher total amount of cytochrome P-450 as well as of certain P-450 isoenzymes, especially those that are hormone-dependent, such as P-450 3A. The improved liver histology and function observed in Cirr+LGF rats was associated with decreases in portal pressure (14.4 vs. 9.4 mm Hg, p<0.01) and portosystemic shunting (55.8 vs. 11.5%, p<0.01), as well as increases in mean arterial pressure and systemic vascular resistance, and a reduction in ascites.

CONCLUSIONS

Administration of the hepatic mitogen, Liver Growth Factor, to CCl4-cirrhotic rats decreased liver collagen and reorganized the hepatic extracellular matrix, resulting in an improvement in liver function, reduced portal pressure and amelioration of ascites.

Biochemical and connective tissue changes in cyclophosphamide-induced lung fibrosis in rats

The present investigation was designed to characterize the biochemical and connective tissue components and to correlate the significance of morphological and biochemical perturbations in cyclophosphamide (CP)-induced lung fibrosis in rats. Lung fibrosis was induced in male Wistar rats by intraperitoneal injection of 20 mg/100 g body weight of CP, and their pneumotoxic derangements were characterized during an early destructive phase followed by a proliferative and synthetic phase. Serum angiotensin-converting enzyme (ACE) activity was higher in CP-treated rats at days 2, 3, 5, 7, and 11, but there was a significant decrease in lung ACE activity during the same time period. Elevated levels of beta-glucuronidase activity were observed in the lung lavage fluid of CP-administered rats days 2, 3, 5, and 7. Lung myeloperoxidase activity was higher in CP rats. Of significance was the presence of collagenase and collagenolytic cathepsin in the lavage fluid of CP rats, when compared with the barely detectable levels in controls. A similar increase in these enzyme activities was also noticed in the lung tissue of CP rats during the same experimental period. Lavage fluid hydroxyproline content was higher in CP rats when compared with controls. Similarly, lung protein and DNA levels were elevated significantly after treatment with CP. The pulmonary histamine and serotonin contents were significantly higher in CP rats. The incorporation of [3H]thymidine into lung total DNA, [3H]proline into lung hydroxyproline, and [35S]sulphate into lung glycosaminoglycan, measured as indicators of lung DNA, collagen, and glycosaminoglycan synthesis, respectively, was also higher in CP groups. Increased levels of hydroxyproline, elastin, hexosamine, total hexose, fucose, sialic acid, and uronic acid in the lungs of rats 14, 28, and 42 days after CP insult were characterized as biomarkers of CP-induced interstitial changes. These findings indicate that CP-induced lung fibrosis results in alterations not only in collagen synthesis and accumulation, but also in glycosaminoglycan and glycoprotein content.

Nitric oxide protection of rat liver from lipid peroxidation, collagen accumulation, and liver damage induced by carbon tetrachloride

The aim of this work was to determine if the inhibition or stimulation of NO synthesis modulates liver damage induced by the chronic administration of CCl4. CCl4 was administered three times a week for 8 weeks to male Wistar rats treated simultaneously with N omega-nitro-L-arginine methyl ester (L-NAME, 100 mg/kg, p.o., twice a day), aminoguanidine (AG, 4 g/L in the drinking water), or L-arginine (500 mg/kg, p.o., twice a day); appropriate controls were performed. Serum NO2- + NO3- increased in the groups treated with CCl4 and/or L-arginine, but the effect was prevented by either L-NAME or AG. In the liver, lipid peroxidation and collagen content increased, while glycogen content decreased in the CCl4-treated group (P < 0.05); L-NAME and AG accentuated these effects. Serum enzyme activities of alanine aminotransferase (ALT), alkaline phosphatase, and gamma-glutamyl transpeptidase (gamma-GTP) and bilirubin content increased about 2-, 3-, 2-, and 6-fold, respectively, after CCl4 intoxication (P < 0.05); L-NAME or AG cotreatment further increased the enzyme activities (P < 0.05). L-Arginine treatment protected the liver partially from the elevation of collagen, bilirubins, and alkaline phosphatase and from glycogen depletion induced by CCl4 intoxication (P < 0.05), but showed no significant effect on ALT, gamma-GTP, or lipid peroxidation. These results suggest that NO protects the liver against oxidative injury, because NO inhibition by L-NAME or AG increased lipid peroxidation and the other markers of liver injury studied herein.

Gelatinase A (MMP-2) and cysteine proteinases are essential for the degradation of collagen in soft connective tissue

The degradation of soft connective tissue collagen is considered to depend on the activity of various proteolytic enzymes, particularly those belonging to the group of matrix metalloproteinases and cysteine proteinases. In the present study, we investigated the contribution of these enzymes to this process. Using a general inhibitor of MMPs (SC44463), collagen degradation was strongly inhibited, by about 40% after 24 h and up to 80% after 72 h of culturing. Blockage of cysteine proteinase activity (with leupeptin or E-64) reduced breakdown at these time intervals by 50% and 20%, respectively. Given the abundant presence of gelatinases--in particular gelatinase A (MMP-2)--in the tissue, the effect of an inhibitor selective for gelatinases (CT1166) was studied. Gelatinase inhibition resulted in a dose-dependent decrease of collagen breakdown up to 90% after 48 h. The ability of gelatinase A to degrade collagens was demonstrated by the induction of breakdown in devitalized explants by addition of activated gelatinase A, or by activation of endogenous enzyme with 4-aminophenylmercuric acetate. This latter effect was not found with plasmin, an activator of MMPs other than gelatinase A. Finally, the relevance of gelatinase A to the in vivo degradation of soft connective tissue collagen was implicated by the significant correlation found between its activity and the collagen turnover rates of four soft connective tissues (tooth pulp, periodontal ligament, molar gingiva and skin). We conclude that collagen degradation in soft connective tissue is mediated by MMPs and to a lesser extent by cysteine proteinases. Our data are the first to attach a key role to gelatinase A in this process.

Stimulation of transforming growth factor beta1 by enteric bacteria in the pathogenesis of rat intestinal fibrosis

BACKGROUND & AIMS

Bacteria and their products stimulate inflammatory responses. Certain mediators, such as transforming growth factor beta1 (TGF-beta1), induce collagen synthesis. Excess collagen deposition results in bowel strictures. The aim of this study was to investigate the role of bacteria and TGF-beta1 in the pathogenesis of intestinal fibrosis.

METHODS

In rats with colitis, the effects of bowel decontamination with antibiotics on TGF-beta1, tumor necrosis factor alpha (TNF-alpha), and collagen content in colonic tissue were studied. In normal rats, bacteria of the predominant flora were inoculated into the colonic wall. The effect of neutralizing antibody to TGF-beta1 on tissue collagen deposition was studied.

RESULTS

Rats with chronic colitis showed increased levels of TGF-beta1, TNF-alpha, and collagen in the tissue and a high rate of bowel strictures. Antibiotic treatment significantly prevented the increase in TGF-beta1 and collagen and the formation of strictures. Inoculation of bacterial suspensions into the colonic wall increased tissue TGF-beta1 and collagen content. Neutralizing antibody to TGF-beta1 prevented collagen deposition. Colonic wall inoculations with single anaerobic strains (Clostridium ramosum, Bacteroides fragilis, and Bacteroides uniformis), but not with aerobes, induced collagen deposition.

CONCLUSIONS

Certain strains of the common flora stimulate TGF-beta1 and induce deposition of collagen in the colonic wall.

Polyenylphosphatidylcholine prevents carbon tetrachloride-induced lipid peroxidation while it attenuates liver fibrosis

BACKGROUND/AIMS

Polyenylphosphatidylcholine protects against alcoholic cirrhosis in the baboon and carbon tetrachloride-induced cirrhosis in rats. This study addresses the possible mechanism of the protective effect of polyenylphosphatidylcholine.

METHODS

For 8 weeks, rats were injected with either carbon tetrachloride in peanut oil or peanut oil alone (control), and pair-fed nutritionally adequate liquid diets with equivalent amounts of linoleic acid either as polyenylphosphatidylcholine or as safflower oil. Other rats were injected for 9 weeks with heterologous albumin and fed the same liquid diets. Lipid peroxidation was measured by F2-isoprostanes and 4-hydroxynonenal.

RESULTS

Carbon tetrachloride-induced lipid peroxidation was strikingly attenuated with polyenylphosphatidylcholine supplementation. Levels of hepatic F2-isoprostanes and 4-hydroxynonenal paralleled liver fibrotic scores and collagen accumulation. Polyenylphosphatidylcholine also attenuated the fibrosis induced in rats with human albumin, but in this case, levels of hepatic 4-hydroxynonenal did not change, nor were they significantly affected by polyenylphos-phatidylcholine. Neither carbon tetrachloride injection nor polyenylphosphatidylcholine treatment changed the arachidonic acid content (a major precursor of F2-isoprostanes and 4-hydroxynonenal) in liver phospholipids, and hepatic vitamin E was not significantly altered.

CONCLUSIONS

The hepatic protection of polyenylphosphatidylcholine against carbon tetrachloride appears to be due, at least in part, to an antioxidant effect, whereas the protection against heterologous albumin-induced fibrosis suggests that an additional mechanism, such as stimulation of collagenase activity, may also be responsible.

Differential effects between tauroursodeoxycholic and taurochenodeoxycholic acids in hepatic fibrosis: an assessment by primary cultured Ito and Kupffer cells from the rat liver

The pathogenesis of hepatic fibrosis in cholestasis is still unknown, except for endotoxaemia. There is a possibility that the elevation of serum bile acids in cholestasis may play an important role in hepatic fibrogenesis due to a reaction to perisinusoidal cells, such as Ito or Kupffer cells. To assess the effects of bile acids, we investigated the cell proliferation and collagen formation of primary cultured Ito cells that were incubated with a Kupffer cell conditioned medium (KCCM) treated with either taurochenodeoxycholic acid (TCDCA) or tauroursodeoxycholic acid (TUDCA) in short-term (8 h) or long-term (48 h) cultures. KCCM treated with TCDCA (100 mumol/L) but not with TUDCA increased cell proliferation of Ito cells in short-term cultures and also partially elevated collagen formation by Ito cells in long-term cultures. The release of tumour necrosis factor-alpha (TNF alpha) from Kupffer cells was increased by TCDCA in short-term cultures, but not in long-term cultures. The release of transforming growth factor-beta 1 (TGF beta 1) from Kupffer cells was increased by TCDCA in long-term cultures, but not in the short-term cultures. TUDCA showed no significant effect on the release of TNF alpha and TGF beta 1 from Kupffer cells. TUDCA or TCDCA itself showed no direct effect on the cell proliferation and collagen formation of Ito cells. In conclusion, these findings are thus considered to show the potentially important role of TCDCA on the development of hepatic fibrosis in the early phase of cholestasis without endotoxaemia.

Alpha-interferon prevents liver collagen deposition and damage induced by prolonged bile duct obstruction in the rat

BACKGROUND/AIMS

Interferons have been used to treat chronic viral hepatitis, due to their antiviral properties. However, interferons are now recognized also to inhibit collagen production. Since fibrosis has been associated with liver damage and dysfunction, the effects of interferon-alpha 2 b on biliary obstruction-induced fibrosis were investigated.

METHODS

Extrahepatic cholestasis was induced in male Wistar rats (around 200g) by double ligation and division of the common bile duct. Control rats were sham operated. Interferon-alpha 2b (IFN-alpha; 100,000 IU/rat) was administered subcutaneously, daily after surgery. The animals were killed after 4 weeks of bile duct ligation or sham operation. Liver damage and cholestasis was analyzed by histological, ultrastructural and biochemical techniques.

RESULTS

Biliary obstruction produced dilation of the bile canaliculi, disorganization of mitochondria and an increase in vacuolization. Bile duct ligation led to an important accumulation of collagen, determined, both histologically and as the hydroxyproline content of the liver. Bilirubin and serum enzyme activities (determined as markers of cholestasis) increased several-fold after bile duct ligation. Administration of IFN-alpha to bile duct ligated rats resulted in significant preservation of ultrastructure, histology, inhibition of collagen accumulation and in a partial improvement of serum markers of cholestasis.

CONCLUSIONS

It is concluded that interferons possess interesting beneficial effects on the liver not related to its antiviral properties but probably associated with its antifibrogenic properties.

Polyenylphosphatidylcholine attenuates non-alcoholic hepatic fibrosis and accelerates its regression

BACKGROUND/AIMS

Polyenylphosphatidylcholine protects against alcoholic cirrhosis in the baboon. This study assesses whether the antifibrotic effect also pertains to a species other than the baboon and to agents other than alcohol.

METHODS

Rats were injected with either CC14 in peanut oil or peanut oil alone, and pair-fed nutritionally adequate liquid diets, with or without polyenylphosphatidylcholine. Other rats were injected with heterologous albumin instead of CC14. To assess whether polyenylphosphatidylcholine is active on established fibrosis, rats were also given CC14 for 8 weeks, and then divided into two groups and pair-fed a diet with or without polyenylphosphatidylcholine.

RESULTS

After 8 weeks of CC14, the animals were sacrificed; chromotrope aniline blue and Sirius red stains of liver revealed fibrosis or cirrhosis in animals given CC14 alone, whereas the effect was attenuated in the polyenylphosphatidylcholine-supplemented animals. Hepatic collagen content was decreased by 25 to 32% (p < 0.05) and serum ALT and AST were significantly less increased. The expression of liver collagen type I mRNA was significantly increased in CC14 treated rats and was not significantly affected by polyenylphosphatidylcholine although there was a trend towards a lesser increase polyenylphosphatidylcholine also attenuated liver fibrosis produced by the injection of heterologous albumin. CC14-induced liver fibrosis regressed more rapidly in polyenylphosphatidylcholine-treated animals than controls, both histologically and by measurement of collagen (p < 0.05).

CONCLUSIONS

Polyenylphosphatidylcholine (a) attenuates hepatic fibrosis induced by CC14 or human albumin in rats; and (b) accelerates the regression of pre-existing fibrosis.

Collagen synthesis by vascular smooth muscle cells in the presence of antiproliferative polysaccharides

Production of various components of the extracellular matrix (ECM) modulates biological functions of the vascular tissue. This process is generally amplified in pathologic states as atherosclerosis. Atheroma originates from smooth muscle cells (SMC) which have migrated and proliferated in the vascular intima. In this study we investigated protein synthesis, collagen synthesis, and types I, III, and V collagen distribution by SMC in the presence of three families of watersoluble polysaccharides, heparin, fucans, and derivatized dextrans. We observed that fucan and derivatized dextran were able, as was heparin, to inhibit rat aortic SMC growth in culture. We then analyzed collagen modulation by measuring the incorporation of the radiolabeled precursor (3H)-proline into vascular SMC. Our results showed uncoupling of the antiproliferative capacity with collagen biosynthesis. However, fucan, the most antiproliferative polysaccharide, was also the most active in inhibiting protein and collagen synthesis. In addition, compounds that decreased total collagen synthesis preferentially increased the proportion of cell-associated collagen. Interestingly, only the antiproliferative polysaccharides inhibited significantly type V collagen biosynthesis. These new biomaterials appear to be valuable tools to study and control extracellular-matrix interactions with cells from the vascular walls.

Human myofibroblastlike cells obtained by outgrowth are representative of the fibrogenic cells in the liver

During human fibrogenesis, myofibroblastlike cells proliferate and are the main source of fibrosis components. We have used cultured myofibroblastlike cells obtained by outgrowth from explants of human liver to study the expression of extracellular matrix (ECM) components and matrix-metalloproteinase-2 (MMP-2) These cells contained types I, III, IV, and V procollagen messenger RNAs (mRNAs). They also expressed mRNAs for laminin B1 chain and for cellular and plasma fibronectin. The corresponding proteins were detected by immunocytochemistry. MMP-2 expression was shown by Northern blot and gelatin zymography. Because transforming growth factor beta 1 (TGF beta 1) is considered an important mediator in liver fibrogenesis, we examined its effect on expression of ECM components by cultural human myofibroblastlike cells. TGF beta 1 increased collagen mRNAs steady-state levels and total collagen secretion in the culture medium. It also increased fibronectin mRNA levels but had no effect on laminin mRNA or MMP-2 expression. In summary, cultured human myofibroblastlike cells express those ECM components that accumulate during hepatic fibrogenesis, indicating the usefulness of this model to study mechanisms of human liver fibrogenesis. In addition to the mitogenic effect of TGF beta 1 on human myofibroblastlike cells, we now demonstrate its stimulation of ECM accumulation in these cells, thus emphasizing the central role of TGF beta 1 and myofibroblastlike cells in the pathophysiology of human hepatic fibrosis.

Remission of liver fibrosis by interferon-alpha 2b

Fibrosis is a dynamic process associated with the continuous deposition and resorption of connective tissue, mainly collagen. Therapeutic strategies are emerging by which this dynamic process can be modulated. Since interferons are known to inhibit collagen production, the aim of this study was to investigate if the administration of interferon-alpha 2b (IFN-alpha) can restore the normal hepatic content of collagen in rats with established fibrosis. Fibrosis was induced by prolonged bile duct ligation. IFN-alpha (100,000 IU/rat/day; s.c.) was administered to fibrotic rats for 15 days. Bile duct ligation increased liver collagen content 6-fold. In addition, serum and liver markers of hepatic injury increased significantly; liver histology showed an increase in collagen deposition, and the normal architecture was lost, with large zones of necrosis being observed frequently. IFN-alpha administration reversed to normal the values of all the biochemical markers measured and restored the normal architecture of the liver. Our results demonstrated that IFN-alpha is useful in reversing fibrosis and liver damage induced by biliary obstruction in the rat. However, further investigations are required to evaluate the therapeutic relevance of interferons on non-viral fibrosis and cholestasis.

Adherence, proliferation and collagen turnover by human fibroblasts seeded into different types of collagen sponges

We describe an in vitro model that we have used to evaluate dermal substitutes and to obtain data on cell proliferation, the rate of degradation of the dermal equivalent, contractibility and de novo synthesis of collagen. We tested three classes of collagenous materials: (1) reconstituted non-crosslinked collagen, (2) reconstituted collagen that was chemically crosslinked with either glutaraldehyde, aluminium alginate or acetate, and (3) native collagen fibres, with or without other extracellular matrix molecules (elastin hydrolysate, hyaluronic acid or fibronectin). The non-crosslinked reconstituted collagen was degraded rapidly by human fibroblasts. The chemically crosslinked materials proved to be cytotoxic. Native collagen fibres were stable. In the absence of ascorbic acid, the addition of elastin hydrolysate to this type of matrix reduced the rate of collagen degradation. Both elastin hydrolysate and fibronectin partially prevented fibroblast-mediated contraction. Hyaluronic acid was only slightly effective in reducing the collagen degradation rate and more fibroblast-mediated contraction of the material was found than for the native collagen fibres with elastin hydrolysate and fibronectin. In the presence of ascorbate, collagen synthesis was enhanced in the native collagen matrix without additions and in the material containing elastin hydrolysate, but not in the material with hyaluronic acid. These results are indicative of the suitability of tissue substitutes for in vivo application.

Interferon alfa and gamma inhibit proliferation and collagen synthesis of human Ito cells in culture

During the course of ongoing liver fibrogenesis, Ito cells acquire myofibroblastic features, proliferate, and synthesize increased amounts of extracellular matrix components. Interferon (IFN) alfa and IFN gamma have been shown to elicit antiproliferative and/or antifibrogenic effects in various cell cultures of mesenchymal origin. The aim of this study was to investigate the effects of IFN-alpha and IFN-gamma on cultured human myofibroblastic Ito cells (MFBIC) proliferation and collagen synthesis and secretion. Serum-stimulated incorporation of [3H]-thymidine into DNA of MFBIC was dose-dependently decreased by both cytokines. IFN-alpha (10(4) U/mL) and IFN-gamma (10(3) U/mL) decreased DNA synthesis by 69% and 66%, respectively. Inhibition of cell proliferation was confirmed by cell counting. Similar results were observed when cell growth was stimulated with platelet-derived growth factor (PDGF-BB, PDGF-AA) or transforming growth factor (TGF)-beta 1. Collagen secretion per cell was inhibited by both cytokines, as assessed by [3H]-hydroxyproline incorporation. After a 6-day treatment, IFN-gamma showed a greater potency than IFN-alpha in inhibiting secretion of newly synthetized collagen (41% and 4% of control in the presence of 10(2) U/mL of IFN-gamma and 10(4) U/mL of IFN-alpha, respectively). Both IFN-alpha and IFN-gamma concurrently decreased steady-state expression of type I and type III procollagen messenger RNAs (mRNAs) in quiescent MFBIC. Viability assays ruled out cytotoxic effects of the two molecules. Finally, both IFNs decreased smooth muscle alpha-actin (SM alpha-actin) expression, whether assayed by immunoblotting or by Northern blot analysis. We conclude that IFN-alpha and IFN-gamma inhibit proliferation as well as collagen synthesis in human MFBIC.

Congenital soft tissue dysplasias: a morphological and biochemical study

The term congenital soft tissue dysplasias (CSTDs) regroups some localized malformations of covering soft tissues in children, presenting as various clinical entities, either recognized as particular syndromes (e.g., Parkes-Weber, Klippel-Trenaunay, Proteus) or, most often, appearing less stereotyped (e.g., segmental hypertrophy or gigantism, lymphedema, angiodysplasia, phakomatosis), with a common histopathological lesion, the hamartoma. The aim of this paper is to report a morphological and biochemical study of the extracellular matrix of skin and subcutaneous tissue in children with CSTD. For every patient, pathological tissues were compared with contralateral, symmetrical tissues, taken as controls. In all CSTDs, pathological samples were characterized by an increase in water and total glycosaminoglycan (GAG) content with a decrease in collagen content. Other results lead the authors to distinguish two main entities, segmental dysplasia (SeD) and neuroectodermal dysplasia (NeD). Elastic fiber content was increased in SeD and decreased in NeD. Hyaluronic acid (HA) and dermatan sulfate (DS) were increased in NeD, whereas in SeD, HA was decreased with an increase in the DS/HA ratio. Cultured fibroblasts from dysplastic skin had slower proliferation in vitro than fibroblasts from control skin, whereas their biosynthetic activity concerning collagen and GAGs was greater. The difference in the composition of extracellular matrix supports the clinical classification of CSTDs in two main groups: segmental dysplasia with or without gigantism and neuroectodermal dysplasia (in von Recklinghausen's disease and nevi).