Regulation of proteoglycan expression in fibrotic liver and cultured fat-storing cells

Gelatin-Based Hybrid Hydrogels as Matrices for Organoid Culture

The application of liver organoids is very promising in the field of liver tissue engineering; however, it is still facing some limitations. One of the current major limitations is the matrix in which they are cultured. The mainly undefined and murine-originated tumor matrices derived from Engelbreth-Holm-Swarm (EHS) sarcoma, such as Matrigel, are still the standard culturing matrices for expansion and differentiation of organoids toward hepatocyte-like cells, which will obstruct its future clinical application potential. In this study, we exploited the use of newly developed highly defined hydrogels as potential matrices for the culture of liver organoids and compared them to Matrigel and two hydrogels that were already researched in the field of organoid research [i.e., polyisocyanopeptides, enriched with laminin-entactin complex (PIC-LEC) and gelatin methacryloyl (GelMA)]. The newly developed hydrogels are materials that have a physicochemical resemblance with native liver tissue. Norbornene-modified dextran cross-linked with thiolated gelatin (DexNB-GelSH) has a swelling ratio and macro- and microscale properties that highly mimic liver tissue. Norbornene-modified chondroitin sulfate cross-linked with thiolated gelatin (CSNB-GelSH) contains chondroitin sulfate, which is a glycosaminoglycan (GAG) that is present in the liver ECM. Furthermore, CSNB-GelSH hydrogels with different mechanical properties were evaluated. Bipotent intrahepatic cholangiocyte organoids (ICOs) were applied in this work and encapsulated in these materials. This research revealed that the newly developed materials outperformed Matrigel, PIC-LEC, and GelMA in the differentiation of ICOs toward hepatocyte-like cells. Furthermore, some trends indicate that an interplay of both the chemical composition and the mechanical properties has an influence on the relative expression of certain hepatocyte markers. Both DexNB-GelSH and CSNB-GelSH showed promising results for the expansion and differentiation of intrahepatic cholangiocyte organoids. The stiffest CSNB-GelSH hydrogel even significantly outperformed Matrigel based on ALB, BSEP, and CYP3A4 gene expression, being three important hepatocyte markers.

The native liver as inspiration to create superior in vitro hepatic models

Drug induced liver injury (DILI) is one of the major reasons of drug withdrawal during the different phases of drug development. The later in the drug development a drug is discovered to be toxic, the higher the economical as well as the ethical impact will be. In vitro models for early detection of drug liver toxicity are under constant development, however to date a superior model of the liver is still lacking. Ideally, a highly reliable model should be established to maintain the different hepatic cell functionalities to the greatest extent possible, during a period of time long enough to allow for tracking of the toxicity of compounds. In the case of DILI, toxicity can appear even after months of exposure. To reach this goal, an in vitro model should be developed that mimics the in vivo liver environment, function and response to external stimuli. The different approaches for the development of liver models currently used in the field of tissue engineering will be described in this review. Combining different technologies, leading to optimal materials, cells and 3D-constructs will ultimately lead to an ideal superior model that fully recapitulates the liver.

Human Xylosyltransferase I-An Important Linker between Acute Senescence and Fibrogenesis

The human xylosyltransferase isoform XT-I catalyzes the initial step in proteoglycan biosynthesis and represents a biomarker of myofibroblast differentiation. Furthermore, XT-I overexpression is associated with fibrosis, whereby a fibrotic process initially develops from a dysregulated wound healing. In a physiologically wound healing process, extracellular matrix-producing myofibroblasts enter acute senescence to protect against fibrosis. The aim of this study was to determine the role of XT-I in acute senescent proto-myofibroblasts. Normal human dermal fibroblasts were seeded in a low cell density to promote myofibroblast differentiation and treated with H₂O₂ to induce acute senescence. Initiation of the acute senescence program in human proto-myofibroblasts resulted in a suppression of XYLT mRNA expression compared to the control, whereby the isoform XYLT1 was more affected than XYLT2. Moreover, the XT-I protein expression and enzyme activity were also reduced in H₂O₂-treated cells compared to the control. The examination of extracellular matrix remodeling revealed reduced expression of collagen I, fibronectin and decorin. In summary, acute senescent proto-myofibroblasts formed an anti-fibrotic phenotype, and suppression of XT-I during the induction process of acute senescence significantly contributed to subsequent ECM remodeling. XT-I therefore plays an important role in the switch between physiological and pathological wound healing.

Effect of Curcumin on Attenuation of Liver Cirrhosis via Genes/Proteins and Pathways: A System Pharmacology Study

Background: Liver cirrhosis is a life-threatening seqsuel of many chronic liver disorders of varying etiologies. In this study, we investigated protein targets of curcumin in liver cirrhosis based on a bioinformatics approach. Methods: Gene/protein associations with curcumin and liver cirrhosis were probed in drug−gene and gene−diseases databases including STITCH/DGIdb/DisGeNET/OMIM/DISEASES/CTD/Pharos and SwissTargetPrediction. Critical clustering groups (MCODE), hub candidates and critical hub genes in liver cirrhosis were identified, and connections between curcumin and liver cirrhosis-related genes were analyzed via Venn diagram. Interaction of hub genes with curcumin by molecular docking using PyRx-virtual screening tools was performed. Results: MCODE analysis indicated three MCODEs; the cluster (MCODE 1) comprised 79 nodes and 881 edges (score: 22.59). Curcumin database interactions recognized 318 protein targets. Liver cirrhosis genes and curcumin protein targets analysis demonstrated 96 shared proteins, suggesting that curcumin may influence 20 candidate and 13 hub genes, covering 81% of liver cirrhosis critical genes and proteins. Thirteen shared proteins affected oxidative stress regulation, RNA, telomerase activity, cell proliferation, and cell death. Molecular docking analysis showed the affinity of curcumin binding hub genes (Binding affinity: ΔG < −4.9 kcal/mol). Conclusions: Curcumin impacted on several critical liver cirrhosis genes mainly involved in extracellular matrix communication, focal adhesion, and the response to oxidative stress.

Development of Liver-on-Chip Integrating a Hydroscaffold Mimicking the Liver’s Extracellular Matrix

The 3Rs guidelines recommend replacing animal testing with alternative models. One of the solutions proposed is organ-on-chip technology in which liver-on-chip is one of the most promising alternatives for drug screening and toxicological assays. The main challenge is to achieve the relevant in vivo-like functionalities of the liver tissue in an optimized cellular microenvironment. Here, we investigated the development of hepatic cells under dynamic conditions inside a 3D hydroscaffold embedded in a microfluidic device. The hydroscaffold is made of hyaluronic acid and composed of liver extracellular matrix components (galactosamine, collagen I/IV) with RGDS (Arg-Gly-Asp-Ser) sites for cell adhesion. The HepG2/C3A cell line was cultured under a flow rate of 10 µL/min for 21 days. After seeding, the cells formed aggregates and proliferated, forming 3D spheroids. The cell viability, functionality, and spheroid integrity were investigated and compared to static cultures. The results showed a 3D aggregate organization of the cells up to large spheroid formations, high viability and albumin production, and an enhancement of HepG2 cell functionalities. Overall, these results highlighted the role of the liver-on-chip model coupled with a hydroscaffold in the enhancement of cell functions and its potential for engineering a relevant liver model for drug screening and disease study.

Flow-Based Three-Dimensional Co-Culture Model for Long-Term Hepatotoxicity Prediction

We developed concave microwell arrays to establish a size-controllable 3-D co-culture liver model for in vitro drug toxicity testing, to predict hepatotoxicity. The interaction of hepatocytes with hepatic stellate cells (HSCs) was investigated by co-culturing primary 3-D hepatocyte spheroids and HSCs (heterosphere), using 3-D liver-on-a-chip. The effect of HSCs was investigated during spheroid formation; they were involved in controlling the organization of spheroidal aggregates and the formation of tight cell–cell contacts. Scanning electron microscopy (SEM) images showed that co-cultured spheroids with smoother surfaces in the flow chip aggregated more tightly and rapidly, compared to mono-cultured spheroids, until 13 days. Metabolic function analysis revealed that heterospheres secreted 40% more albumin and urea than hepatospheres on day 13. Additionally, an acetaminophen (AAP) and isoniazid (INH) concentration-dependent increase in CYP3A4 expression was detected in the 3-D cultures, and an increase in Lactate dehydrogenase (LDH) release after AAP and INH treatment was observed. CYP1A2, Mrp1 and UGT1A5 mRNA expression levels in the heterospheres and hepatospheres were evaluated from days 3 to 13. To examine the potential for toxicity testing in the flow-conditioned culture of the heterospheres, we evaluated cytotoxicity using the endpoint LDH release in the heterospheres and hepatospheres. IC₅₀ values for AAP and INH after 24 h of exposure were calculated from the dose–response curves of the compounds. Flow-conditioned heterosphere culture results suggest that it may be suitable for long-term culture and cytotoxicity testing. Thus, our co-culture system closely resembles the in vivo environment and allows long-term in vitro hepatotoxicity prediction.

Diet-dependent function of the extracellular matrix proteoglycan Lumican in obesity and glucose homeostasis

Objective

Extracellular matrix remodeling is required for adipose expansion under increased caloric intake. In turn, inhibited expandability due to aberrant collagen deposition promotes insulin resistance and progression towards the metabolic syndrome. An emerging role for the small leucine-rich proteoglycan Lumican in metabolically driven nonalcoholic fatty liver disease sparks an interest in further understanding its role in diet-induced obesity and metabolic complications.

Methods

Whole body ablation of Lumican (Lum^−/−) gene and adeno-associated virus-mediated over-expression were used in combination with control or high fat diet to assess energy balance, glucose homeostasis as well as adipose tissue health and remodeling.

Results

Lumican was found to be particularly enriched in the stromal cells isolated from murine gonadal white adipose tissue. Likewise murine and human visceral fat showed a robust increase in Lumican as compared to fat from the subcutaneous depot. Lumican null female mice exhibited moderately increased fat mass, decreased insulin sensitivity and increased liver triglycerides in a diet-dependent manner. These changes coincided with inflammation in adipose tissue and no overt effects in adipose expandability, i.e. adipocyte formation and hypertrophy. Lumican over-expression in visceral fat and liver resulted in improved insulin sensitivity and glucose clearance.

Conclusions

These data indicate that Lumican may represent a functional link between the extracellular matrix, glucose homeostasis, and features of the metabolic syndrome.

•

The extracellular matrix proteoglycan Lumican (Lum) is particularly enriched in stromal cells within white adipose tissue.

•

Visceral fat from obese patients displays increased levels of Lum compared to subcutaneous fat.

•

Lum-Ko female mice exhibit decreased insulin sensitivity and increased triglycerides upon high-fat diet (HFD) feeding.

•

Lum-Ko female mice on HFD have increased inflammation in white fat in the absence of overt effects on adipocyte formation.

•

· Lum over-expression in visceral fat and liver resulted in improved insulin sensitivity and glucose clearance.

The multifaceted roles of perlecan in fibrosis

Perlecan, or heparan sulfate proteoglycan 2 (HSPG2), is a ubiquitous heparan sulfate proteoglycan that has major roles in tissue and organ development and wound healing by orchestrating the binding and signaling of mitogens and morphogens to cells in a temporal and dynamic fashion. In this review, its roles in fibrosis are reviewed by drawing upon evidence from tissue and organ systems that undergo fibrosis as a result of an uncontrolled response to either inflammation or traumatic cellular injury leading to an over production of a collagen-rich extracellular matrix. This review focuses on examples of fibrosis that occurs in lung, liver, kidney, skin, kidney, neural tissues and blood vessels and its link to the expression of perlecan in that particular organ system.

Engineering 3D Hydrogels for Personalized In Vitro Human Tissue Models

There is a growing interest in engineering hydrogels for 3D tissue and disease models. The major motivation is to better mimic the physiological microenvironment of the disease and human condition. 3D tissue models derived from patients' own cells can potentially revolutionize the way treatment and diagnostic alternatives are developed. This requires development of tissue mimetic hydrogels with user defined and tunable properties. In this review article, a recent summary of 3D hydrogel platforms for in vitro tissue and disease modeling is given. Hydrogel design considerations and available hydrogel systems are summarized, followed by the types of currently available hydrogel models, such as bulk hydrogels, porous scaffolds, fibrous scaffolds, hydrogel microspheres, hydrogel sandwich systems, microwells, and 3D bioprinted constructs. Although hydrogels are utilized for a wide range of tissue models, this article focuses on liver and cancer models. This article also provides a detailed section on current challenges and future perspectives of hydrogel-based tissue models.

The stellate cell system (vitamin A-storing cell system)

Past, present, and future research into hepatic stellate cells (HSCs, also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, or Ito cells) are summarized and discussed in this review. Kupffer discovered black-stained cells in the liver using the gold chloride method and named them stellate cells (Sternzellen in German) in 1876. Wake rediscovered the cells in 1971 using the same gold chloride method and various modern histological techniques including electron microscopy. Between their discovery and rediscovery, HSCs disappeared from the research history. Their identification, the establishment of cell isolation and culture methods, and the development of cellular and molecular biological techniques promoted HSC research after their rediscovery. In mammals, HSCs exist in the space between liver parenchymal cells (PCs) or hepatocytes and liver sinusoidal endothelial cells (LSECs) of the hepatic lobule, and store 50-80% of all vitamin A in the body as retinyl ester in lipid droplets in the cytoplasm. SCs also exist in extrahepatic organs such as pancreas, lung, and kidney. Hepatic (HSCs) and extrahepatic stellate cells (EHSCs) form the stellate cell (SC) system or SC family; the main storage site of vitamin A in the body is HSCs in the liver. In pathological conditions such as liver fibrosis, HSCs lose vitamin A, and synthesize a large amount of extracellular matrix (ECM) components including collagen, proteoglycan, glycosaminoglycan, and adhesive glycoproteins. The morphology of these cells also changes from the star-shaped HSCs to that of fibroblasts or myofibroblasts.

Elastin in the Liver

A characteristic feature of liver cirrhosis is the accumulation of large amounts of connective tissue with the prevailing content of type I collagen. Elastin is a minor connective tissue component in normal liver but it is actively synthesized by hepatic stellate cells and portal fibroblasts in diseased liver. The accumulation of elastic fibers in later stages of liver fibrosis may contribute to the decreasing reversibility of the disease with advancing time. Elastin is formed by polymerization of tropoelastin monomers. It is an amorphous protein highly resistant to the action of proteases that forms the core of elastic fibers. Microfibrils surrounding the core are composed of fibrillins that bind a number of proteins involved in fiber formation. They include microfibril-associated glycoproteins (MAGPs), microfibrillar-associated proteins (MFAPs) and fibulins. Lysyl oxidase (LOX) and lysyl oxidase-like proteins (LOXLs) are responsible for tropoelastin cross-linking and polymerization. TGF-β complexes attached to microfibrils release this cytokine and influence the behavior of the cells in the neighborhood. The role of TGF-β as the main profibrotic cytokine in the liver is well-known and the release of the cytokines of TGF-β superfamily from their storage in elastic fibers may affect the course of fibrosis. Elastic fibers are often studied in the tissues where they provide elasticity and resilience but their role is no longer viewed as purely mechanical. Tropoelastin, elastin polymer and elastin peptides resulting from partial elastin degradation influence fibroblastic and inflammatory cells as well as angiogenesis. A similar role may be performed by elastin in the liver. This article reviews the results of the research of liver elastic fibers on the background of the present knowledge of elastin biochemistry and physiology. The regulation of liver elastin synthesis and degradation may be important for the outcome of liver fibrosis.

Asian-Pacific Association for the Study of the Liver (APASL) consensus guidelines on invasive and non-invasive assessment of hepatic fibrosis: a 2016 update

Hepatic fibrosis is a common pathway leading to liver cirrhosis, which is the end result of any injury to the liver. Accurate assessment of the degree of fibrosis is important clinically, especially when treatments aimed at reversing fibrosis are being evolved. Despite the fact that liver biopsy (LB) has been considered the "gold standard" of assessment of hepatic fibrosis, LB is not favored by patients or physicians owing to its invasiveness, limitations, sampling errors, etc. Therefore, many alternative approaches to assess liver fibrosis are gaining more popularity and have assumed great importance, and many data on such approaches are being generated. The Asian Pacific Association for the Study of the Liver (APASL) set up a working party on liver fibrosis in 2007, with a mandate to develop consensus guidelines on various aspects of liver fibrosis relevant to disease patterns and clinical practice in the Asia-Pacific region. The first consensus guidelines of the APASL recommendations on hepatic fibrosis were published in 2009. Due to advances in the field, we present herein the APASL 2016 updated version on invasive and non-invasive assessment of hepatic fibrosis. The process for the development of these consensus guidelines involved review of all available published literature by a core group of experts who subsequently proposed consensus statements followed by discussion of the contentious issues and unanimous approval of the consensus statements. The Oxford System of the evidence-based approach was adopted for developing the consensus statements using the level of evidence from one (highest) to five (lowest) and grade of recommendation from A (strongest) to D (weakest). The topics covered in the guidelines include invasive methods (LB and hepatic venous pressure gradient measurements), blood tests, conventional radiological methods, elastography techniques and cost-effectiveness of hepatic fibrosis assessment methods, in addition to fibrosis assessment in special and rare situations.

Differential effects of hyaluronan synthase 3 deficiency after acute vs chronic liver injury in mice

Background

Hyaluronan (HA) is a ubiquitous extracellular matrix (ECM) glycosaminoglycan synthesized by three different enzymes, hyaluronan synthase (HAS)1, 2, and 3. HA synthesis mediated by HAS3 promotes inflammation and is pathogenic in animal models of human lung and intestinal disease. Liver fibrosis is a common endpoint to chronic liver injury and inflammation for which there is no cure. Although plasma HA is a commonly used biomarker for liver disease, if and how HA contributes to disease pathogenesis remains unclear. Here, we tested the hypothesis that HA synthesized by HAS3 enhances inflammation and fibrosis. To test this hypothesis, we exposed wild-type or Has3−/− mice to carbon tetrachloride (CCl₄) once (acute) or ten (chronic) times.

Results

HAS3-deficient mice exhibited increased hepatic injury and inflammatory chemokine production 48 h after acute CCl₄; this was associated with a threefold reduction in plasma HA levels and alterations in the proportions of specific molecular weight HA polymer pools. Hepatic accumulation of fibrosis-associated transcripts was also greater in livers from HAS3-deficient mice compared to controls after acute CCl₄ exposure. Surprisingly, fibrosis was not different between genotypes. Hepatic matrix metalloproteinase (MMP)13 mRNA and MMP13 activity was greater in livers from Has3-null mice after chronic CCl₄; this was prevented by a MMP13-specific inhibitor. Collectively, these data suggest that Has3, or more likely HA produced by HAS3, limits hepatic inflammation after acute injury and attenuates MMP13-mediated matrix metabolism after chronic injury.

Conclusions

These data suggest that HA should be investigated further as a novel therapeutic target for acute and chronic liver disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13069-016-0041-5) contains supplementary material, which is available to authorized users.

Hepatoprotective and Anti-fibrotic Agents: It's Time to Take the Next Step

Hepatic fibrosis and cirrhosis cause strong human suffering and necessitate a monetary burden worldwide. Therefore, there is an urgent need for the development of therapies. Pre-clinical animal models are indispensable in the drug discovery and development of new anti-fibrotic compounds and are immensely valuable for understanding and proofing the mode of their proposed action. In fibrosis research, inbreed mice and rats are by far the most used species for testing drug efficacy. During the last decades, several hundred or even a thousand different drugs that reproducibly evolve beneficial effects on liver health in respective disease models were identified. However, there are only a few compounds (e.g., GR-MD-02, GM-CT-01) that were translated from bench to bedside. In contrast, the large number of drugs successfully tested in animal studies is repeatedly tested over and over engender findings with similar or identical outcome. This circumstance undermines the 3R (Replacement, Refinement, Reduction) principle of Russell and Burch that was introduced to minimize the suffering of laboratory animals. This ethical framework, however, represents the basis of the new animal welfare regulations in the member states of the European Union. Consequently, the legal authorities in the different countries are halted to foreclose testing of drugs in animals that were successfully tested before. This review provides a synopsis on anti-fibrotic compounds that were tested in classical rodent models. Their mode of action, potential sources and the observed beneficial effects on liver health are discussed. This review attempts to provide a reference compilation for all those involved in the testing of drugs or in the design of new clinical trials targeting hepatic fibrosis.

Proteoglycans in liver cancer

Proteoglycans are a group of molecules that contain at least one glycosaminoglycan chain, such as a heparan, dermatan, chondroitin, or keratan sulfate, covalently attached to the protein core. These molecules are categorized based on their structure, localization, and function, and can be found in the extracellular matrix, on the cell surface, and in the cytoplasm. Cell-surface heparan sulfate proteoglycans, such as syndecans, are the primary type present in healthy liver tissue. However, deterioration of the liver results in overproduction of other proteoglycan types. The purpose of this article is to provide a current summary of the most relevant data implicating proteoglycans in the development and progression of human and experimental liver cancer. A review of our work and other studies in the literature indicate that deterioration of liver function is accompanied by an increase in the amount of chondroitin sulfate proteoglycans. The alteration of proteoglycan composition interferes with the physiologic function of the liver on several levels. This article details and discusses the roles of syndecan-1, glypicans, agrin, perlecan, collagen XVIII/endostatin, endocan, serglycin, decorin, biglycan, asporin, fibromodulin, lumican, and versican in liver function. Specifically, glypicans, agrin, and versican play significant roles in the development of liver cancer. Conversely, the presence of decorin could potentially provide protective effects.

Lumican binds ALK5 to promote epithelium wound healing

Lumican (Lum), a small leucine-rich proteoglycan (SLRP) family member, has multiple matricellular functions both as an extracellular matrix component and as a matrikine regulating cell proliferation, gene expression and wound healing. To date, no cell surface receptor has been identified to mediate the matrikine functions of Lum. This study aimed to identify a perspective receptor that mediates Lum effects on promoting wound healing. Transforming growth factor-β receptor 1 (ALK5) was identified as a potential Lum-interacting protein through in silico molecular docking and molecular dynamics. This finding was verified by biochemical pull-down assays. Moreover, the Lum function on wound healing was abrogated by an ALK5-specific chemical inhibitor as well as by ALK5 shRNAi. Finally, we demonstrated that eukaryote-specific post-translational modifications are not required for the wound healing activity of Lum, as recombinant GST-Lum fusion proteins purified from E. coli and a chemically synthesized LumC₁₃ peptide (the last C-terminal 13 amino acids of Lum) have similar effects on wound healing in vitro and in vivo.

Spheroid-based three-dimensional liver-on-a-chip to investigate hepatocyte-hepatic stellate cell interactions and flow effects

We have developed a three-dimensional (3D) liver-on-a-chip to investigate the interaction of hepatocytes and hepatic stellate cells (HSCs) in which primary 3D hepatocyte spheroids and HSCs are co-cultured without direct cell-cell contact. Here, we show that the 3D liver chip offers substantial advantages for the formation and harvesting of spheroids. The most important feature of this liver chip is that it enables continuous flow of medium to the cells through osmotic pumping, and thus requires only minimal handling and no external power source. We also demonstrate that flow assists the formation and long-term maintenance of spheroids. Additionally, we quantitatively and qualitatively investigated the paracrine effects of HSCs, demonstrating that HSCs assist in the maintenance of hepatocyte spheroids and play an important role in the formation of tight cell-cell contacts, thereby improving liver-specific function. Spheroids derived from co-cultures exhibited improved albumin and urea secretion rates compared to mono-cultured spheroids after 9 days. Immunostaining for cytochrome P450 revealed that the enzymatic activity of spheroids co-cultured for 8 days was greater than that of mono-cultured spheroids. These results indicate that this system has the potential for further development as a unique model for studying cellular interactions or as a tool that can be incorporated into other models aimed at creating hepatic structure and prolonging hepatocyte function in culture.

Increased expression of chondroitin sulphate proteoglycans in rat hepatocellular carcinoma tissues

AIM: To investigate the expression of chondroitin sulphate proteoglycans (CSPGs) in rat liver tissues of hepatocellular carcinoma (HCC).

METHODS: Thirty male Sprague Dawley rats were randomly divided into two groups: control group (n = 10) and HCC model group (n = 20). Rats in the HCC model groups were intragastrically administrated with 0.2% (w/v) N-diethylnitrosamine (DEN) every 5 d for 16 wk, whereas 0.9% (w/v) normal saline was administered to rats in the control group. After 16 wk from the initiation of experiment, all rats were killed and livers were collected and fixed in 4% (w/v) paraformaldehyde. All tissues were embedded in paraffin and sectioned. Histological staining (hematoxylin and eosin and Toluidine blue) was performed to demonstrate the onset of HCC and the content of sulphated glycosaminoglycan (sGAG). Immunohistochemical staining was performed to investigate the expression of chondroitin sulphate (CS)/dermatan sulphate (DS)-GAG, heparan sulphate (HS)-GAG, keratan sulphate (KS)-GAG in liver tissues. Furthermore, expression and distribution of CSPG family members, including aggrecan, versican, biglycan and decorin in liver tissues, were also immunohistochemically determined.

RESULTS: After 16 wk administration of DEN, malignant nodules were observed on the surface of livers from the HCC model group, and their hepatic lobule structures appeared largely disrupted under microscope. Toluidine blue staining demonstrated that there was an significant increase in sGAG content in HCC tissues when compared with that in the normal liver tissues from the control group [0.37 ± 0.05 integrated optical density per stained area (IOD/area) and 0.21 ± 0.01 IOD/area, P < 0.05]. Immunohistochemical studies demonstrated that this increased sGAG in HCC tissues was induced by an elevated expression of CS/DS (0.28 ± 0.02 IOD/area and 0.18 ± 0.02 IOD/area, P < 0.05) and HS (0.30 ± 0.03 IOD/area and 0.17 ± 0.02 IOD/area, P < 0.01) but not KS GAGs in HCC tissues. Further studies thereby were performed to investigate the expression and distribution of several CSPG components in HCC tissues, including aggrecan, versican, biglycan and decorin. Interestingly, there was a distinct distribution pattern for these CSPG components between HCC tissues and the normal tissues. Positive staining of aggrecan, biglycan and decorin was localized in hepatic membrane and/or pericellular matrix in normal liver tissues; however, their expression was mainly observed in the cytoplasm, cell membranes in hepatoma cells and/or pericellular matrix within HCC tissues. Semi-quantitative analysis indicated that there was a higher level of expression of aggrecan (0.43 ± 0.01 and 0.35 ± 0.03, P < 0.05), biglycan (0.32 ± 0.01 and 0.25 ± 0.01, P < 0.001) and decorin (0.29 ± 0.01 and 0.26 ± 0.01, P < 0.05) in HCC tissues compared with that in the normal liver tissues. Very weak versican positive staining was observed in hepatocytes near central vein in normal liver tissues; however there was an intensive versican distribution in fibrosis septa between the hepatoma nodules. Semi-quantitative analysis indicated that the positive rate of versican in hepatoma tissues from the HCC model group was much higher than that in the control group (33.61% and 21.28%, P < 0.05). There was no positive staining in lumican and keratocan, two major KSPGs, in either normal or HCC liver tissues.

CONCLUSION: CSPGs play important roles in the onset and progression of HCC, and may provide potential therapeutic targets and clinical biomarkers for this prevalent tumor in humans.

Increased serum xylosyltransferase activity in patients with liver fibrosis

BACKGROUND

We investigated the xylosyltransferase (XT) activity in the serum of liver fibrotic patients with hepatitis C virus induced liver fibrosis at different stages as determined according to the scoring system of Desmet and Scheuer.

METHODS

Measurement of XT activity was performed by liquid chromatography-tandem mass spectrometry.

RESULTS

We found that serum XT activity in males (n=59, median+/-SD, 27.2+/-2.8 mU/L, p<0.001) and females (n=54, 23.6+/-3.0 mU/L, p<0.01) with liver fibrosis is significantly elevated in comparison to a corresponding healthy control cohort of males (n=50, 23.9+/-2.8 mU/L) and females (n=52, 21.5+/-3.7 mU/L), respectively. Of note, independent from gender, serum XT activity positively correlated with the stage of fibrosis but declined again in patients with histologically proven cirrhosis.

CONCLUSIONS

XT activity is increased in the serum of patients with liver fibrosis at different stages, pointing to a possible pathogenetic role in elevated proteoglycan biosynthesis in fibrotic remodeling of this organ during chronic injury.

Thermodynamic insights into the structural basis governing the donor substrate recognition by human beta1,4-galactosyltransferase 7

Human beta1,4-GalT (galactosyltransferase)7 is involved in the biosynthesis of the tetrasaccharide linker protein region (GlcAbeta1-->3Galbeta1-->3Galbeta1-->4Xylbeta1) (where GlcA is glucuronic acid and Xyl is xylose) of proteoglycans, by catalysing the transfer of Gal (galactose) from the uridine 5'-diphosphogalactose to a Xyl residue. This reaction is rate-limiting in glycosaminoglycan biosynthesis. In the present study, we established a large-scale production system of beta1,4-GalT7 fused with the maltose-binding protein to study substrate recognition. Calorimetric binding studies showed that the binding of the donor substrate UDP-Gal largely promoted binding of the acceptor substrate. To identify the structural basis governing substrate recognition, we used a fragment-based approach involving the artificial breakdown of the donor substrate into smaller fragments and characterization of their respective binding to the enzyme by isothermal titration calorimetry. The beta-phosphate, and to a lesser extent the alpha-phosphate, largely contributed to the binding energy. However, the uridine moiety was found to be essential for the optimal positioning of the donor substrate within the binding site. Unexpectedly, the contribution of the Gal moiety in substrate recognition was found to be negligible. Indeed, UDP-Gal, but also various UDP-sugars, could bind to beta1,4-GalT7. Surprisingly, in contrast with other GalTs, soluble beta1,4-GalT7 was able to transfer Glc (glucose), Xyl and, to a lesser extent GlcA and GlcNAc (N-acetyl glucosamine), to acceptor sugars, whereas UDP-Man (mannose) and UDP-GalNAc (N-acetyl galactosamine) were not substrates.

Activation of TGF-beta within cultured hepatocytes and in liver injury leads to intracrine signaling with expression of connective tissue growth factor

Recently, synthesis and secretion of connective tissue growth factor (CTGF)/CYR61/CTGF/NOV-family member 2 (CCN2) in cultures of hepatocytes were shown, which are sensitively up-regulated by exogenous TGF-beta. In this study TGF-beta-dependent CTGF/CCN2 expression in hepatocytes cultured under completely TGF-beta-free conditions was analysed by Western-blots, metabolic labelling, and CTGF-reporter gene assays. In alkaline phosphatase monoclonal anti-alkaline phosphatase complex (APAAP)-staining of cultured hepatocytes it was demonstrated that latent TGF-beta within the hepatocytes becomes rapidly detectable during culture indicating an intracellular demasking of the mature TGF-beta antigen. Subsequent signaling to theCTGF/CCN2 promoter occurs via p-Smad2, whereas p-Smad3 does not seem to be involved. Cycloheximide did not abolish the rapid immunocytochemical appearance of mature TGF-beta, but calpain inhibitors partially suppressed intracellular TGF-beta activation and subsequently CTGF up-regulation. Calpain treatment had the reverse effect. None of the inhibitors of extracellular TGF-beta signalling was effective in the reduction of spontaneous CTGF synthesis, but intracellularly acting Alk 4-/Alk 5-specific inhibitor SB-431542 was able to diminish CTGF expression. The assumption that latent intracellular TGF-beta is activated by calpains during culture-induced stress or injurious conditions in the liver in vivo was further validated by a direct effect of calpains on the activation of recombinant latent TGF-beta. In conclusion, these data are the first to suggest the possibility of intracrine TGF-beta signalling due to calpain-dependent intracellular proteolytic activation leading to transcriptional activation of CTGF/CCN2 as a TGF-beta-sensitive reporter gene. This mechanism might be deleterious for keeping long-term hepatocyte cultures due to TGF-beta-induced apoptosis and, further, might be of relevance for induction of apoptosis or epithelial-mesenchymal transition of hepatocytes in injured liver.

Disruption of the latent transforming growth factor-beta binding protein-1 gene causes alteration in facial structure and influences TGF-beta bioavailability

Latent transforming growth factor-beta binding proteins are a family of extracellular matrix proteins comprising four isoforms (LTBP-1, -2, -3, -4) with different structures, tissue expression patterns and affinity for TGF-beta. So far, respective knockout models have highlighted some essential functions for LTBP-2, LTBP-3 and LTBP-4, while the physiological significance of LTBP-1 is only superficially known. Here we report for the first time the generation and characterization of a mouse model lacking both the long and short LTBP-1 isoform. Surprisingly, respective mice are viable and fertile. However, detailed X-ray analysis of the skull revealed a modified facial profile. In addition, the gene disruption induces a reduced biological activity of TGF-beta that became evident in an experimental model of hepatic fibrogenesis in which the LTBP-1 knockout animals were less prone to hepatic fibrogenesis. Furthermore, comparative cDNA microarray gene expression profiling of cultured hepatic stellate cells confirmed that respective nulls were less receptive to cellular activation and transdifferentiation into myofibroblasts. Therefore, we conclude that LTBP-1 has essential functions in the control of TGF-beta activation.

Adenovirus-mediated hepatic syndecan-1 overexpression induces hepatocyte proliferation and hyperlipidaemia in mice

BACKGROUND

Heparan sulfate proteoglycans (HSPGs) have been involved in the regulation of cell growth, apoptosis and lipid metabolism in vitro; however, their functional role in vivo remains unknown.

AIM

Here, we describe hepatic tissue and lipid metabolism changes after liver overexpression of syndecan-1 (SDC-1), the main hepatic HSPG, in mice induced by adenoviral gene transfer.

RESULTS

SDC-1 overexpression was associated with marked hepatocyte proliferation, cell-isolated apoptosis and increased plasma alanine aminotransferase (ALT) levels. Additionally, SDC-1 liver overexpression significantly raised plasma cholesterol and triglyceride concentrations due to an increase in all lipoprotein particles, including the appearance of large and apolipoprotein (apo) E-enriched high-density lipoprotein (HDL) particles. Hepatic very low-density lipoprotein (VLDL) production was not affected by SDC-1 overexpression, suggesting a delayed plasma clearance of apo B lipoproteins as the underlying hyperlipidaemic mechanism. These pleotropic effects were qualitatively equivalent, even though less intense, in mice overexpressing a cytoplasmic C-terminal domain-deleted SDC-1.

CONCLUSIONS

This is the first report in vivo of the biological effects induced by a specific HSPG in the liver, with potential implications in both regenerative biology and molecular lipidology.

Laser microdissection and microarray analysis of the hippocampus of Ras-GRF1 knockout mice reveals gene expression changes affecting signal transduction pathways related to memory and learning

We used manual macrodissection or laser capture microdissection (LCM) to isolate tissue sections of the hippocampus area of Ras-GRF1 wild type and knockout mice brains, and analyzed their transcriptional patterns using commercial oligonucleotide microarrays. Comparison between the transcriptomes of macrodissected and microdissected samples showed that the LCM samples allowed detection of significantly higher numbers of differentially expressed genes, with higher statistical rates of significance. These results validate LCM as a reliable technique for in vivo genomic studies in the brain hippocampus, where contamination by surrounding areas (not expressing Ras-GRF1) increases background noise and impairs identification of differentially expressed genes. Comparison between wild type and knockout LCM hippocampus samples revealed that Ras-GRF1 elimination caused significant gene expression changes, mostly affecting signal transduction and related neural processes. The list of 36 most differentially expressed genes included loci concerned mainly with Ras/G protein signaling and cytoskeletal organization (i.e. 14-3-3gamma/zeta, Kcnj6, Clasp2) or related, cross-talking pathways (i.e. jag2, decorin, strap). Consistent with the phenotypes shown by Ras-GRF1 knockout mice, many of these differentially expressed genes play functional roles in processes such as sensory development and function (i.e. Sptlc1, antiquitin, jag2) and/or neurological development/neurodegeneration processes affecting memory and learning. Indeed, potential links to neurodegenerative diseases such as Alzheimer disease (AD) or Creutzfeldt-Jacobs disease (CJD), have been reported for a number of differentially expressed genes identified in this study (Ptma, Aebp2, Clasp2, Hebp1, 14-3-3gamma/zeta, Csnk1delta, etc.). These data, together with the previously described role of IRS and insulin (known Ras-GRF1 activators) in AD, warrant further investigation of a potential functional link of Ras-GRF1 to neurodegenerative processes.

Global analysis of host tissue gene expression in the invasive front of colorectal liver metastases

Host cell reactions are a crucial determinant for tumor invasion. We analyzed on a genomewide scale gene expression differences between microdissected tissues taken from unaffected liver tissue of a human colorectal tumor (LS174) growing in the livers of nude mice and tissue from the host part of the invasive front. Due to the low degree of interspecies cross-hybridization of 15% as determined on Affymetrix microarrays, our xenograft model allowed for the distinction of genes of murine versus human origin even if the respective tissues could not be isolated separately. Using the gene ontology (GO) classification, we were able to determine patterns of up- and downregulated genes in the liver part of the invasive front. We observed a pronounced overrepresentation, e.g., of the GO terms "extracellular matrix," "cell communication," "response to biotic stimulus," "structural molecule activity" and "cell growth," indicating a very pronounced host cell response to tumor invasion. On the single gene level, hepatic stellate cell (HSC) activation markers were overrepresented in the liver part of the invasion front. Immunohistochemistry and qPCR confirmed an activation of HSC as well as an increased number of HSC in the invasive front as compared to the noninvaded liver tissue. In summary, our data demonstrate the feasibility of an interspecies differential gene expression approach on a genomewide scale.

Transforming growth factor-beta (TGF-beta) type I receptor/ALK5-dependent activation of the GADD45beta gene mediates the induction of biglycan expression by TGF-beta

We have recently shown that induction of biglycan (BGN) expression by transforming growth factor-beta1 (TGF-beta1) required sequential activation of both Smad and p38 mitogen-activated protein kinase signaling (Ungefroren, H., Lenschow, W., Chen, W.-B., and Kalthoff, H. (2003) J. Biol. Chem. 278, 11041-11049). Here, we have analyzed the receptors through which TGF-beta1 controls expression of BGN and GADD45beta, the latter of which is postulated to link early Smad signaling to delayed activation of p38. Ectopic expression of a dominant-negative mutant of the TGF-beta type II receptor in PANC-1 cells abrogated TGF-beta-induced BGN up-regulation. Similarly, inhibition of the TGF-beta type I receptor/ALK5 with either SB431542 or by enforced stable expression of a kinase-dead mutant greatly attenuated the TGF-beta effect on both BGN and GADD45beta expression in PANC-1 and MG-63 cells. The enhancing effect of ALK5 on TGF-beta-mediated GADD45beta and BGN expression and on GADD45beta promoter activity was also dependent on its ability to activate Smad signaling, because an ALK5 mutant defective in Smad activation (TbetaRImL45) but with an otherwise functional kinase domain failed to mediate these responses. The TGF-beta/ALK5 effect on p38 activation and BGN expression was mimicked by overexpression of GADD45beta alone (in the absence of TGF-beta stimulation) and suppressed upon antisense inhibition of GADD45beta expression. These results show that TGF-beta induces BGN expression through (the Smad-activating function of) ALK5 and GADD45beta and suggest that the sensitivity of MyD118 to activation by TGF-beta, which varies between tissues, ultimately determines the strength of the TGF-beta effect on BGN.

Association of differentially expressed genes with activation of mouse hepatic stellate cells by high-density cDNA mircoarray

AIM: To characterize the gene expression profiles associated with activation of mouse hepatic stellate cell (HSC) and provide novel insights into the pathogenesis of hepatic fibrosis.

METHODS: Mice HSCs were isolated from BALB/c mice by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient. Total RNA and mRNA of quiescent HSC and culture-activated HSC were extracted, quantified and reversely transcripted into cDNA. cDNAs from activated HSC were labeled with Cy5 and cDNAs from the quiescent HSC were labeled with Cy3, which were mixed with equal quantity, then hybridized with cDNA chips containing 4000 genes. Chips were washed, scanned and analyzed. Increased expression of 4 genes and decreased expression of one gene in activated HSC were confirmed by reverse transcription- polymerase chain reaction (RT-PCR).

RESULTS: A total of 835 differentially expressed genes were identified by cDNA chip between activated and quiescent HSC, and 465 genes were highly expressed in activated HSC. The differentially expressed genes included those involved in protein synthesis, cell-cycle regulation, apoptosis, and DNA damage response.

CONCLUSION: Many genes implicated in intrahepatic inflammation, fibrosis and proliferation were up-regulated in activated HSC. cDNA microarray is an effective technique in screening for differentially expressed genes between two different situations of the HSC. Further analysis of the obtained genes will help understand the molecular mechanism of activation of HSC and hepatic fibrosis.

Effects of Ginkgo biloba extract on liver fibrosis induced by carbon tetrachloride in rats

AIM: To study the effects of Ginko biloba extract (EGb) on hepato-fibrosis induced by carbon tetrachloride (Cl₄) in rat model.

METHODS: Rat liver fibrosis model was induced by Cl₄ administration. Wistar rats were randomly divided into 5 groups: normal control group, a model group, a interven-tional group, a therapeutic group, and a EGb group. The EGb interventional group, apart from administration of Cl₄, was treated concurrently with EGb 0.3 g/kg, ig once a day; the EGb therapeutic group was treated with EGb 0.3 g/kg, ig once a day after cirrhosis was induced successfully, and the EGb group was treated only with EGb 0.3 g/kg, ig once a day. At the end of wk 8 and 16, all the rats were sacrificed. The pathological changes of liver were observed by H-E and Von-Gieson staining.The expression of mRNA and proteins of collagen I/TGF₁ in liver were determined by RT-PCR and immunohistochemistry.

RESULTS: The degree of liver fibrosis and level of mRNA and proteins of collagen I/TGF₁ in liver were significantly reduced in the EGb interventional and therapeutic groups compared with those in the model group (type I collagen mRNA: 0.0 778±0.054 vs 0.2 361±0.113, 0.1 075±0.007 vs 0.2 361±0.113, P < 0.01; type I collagen proteins: 0.2 563±0.0 009 vs 0.2 885±0.0 025, 0.2 541±0.0 076 vs 0.2 885±0.0 025 , P < 0.01; TGF₁ mRNA: 0.523±0.015 vs 0.956±0.049 , 0.524±0.009 vs 0.956±0.049, P < 0.01; TGF₁ proteins: 0.2 785±0.0 012 vs 0.3 015±0.0 012, 0.2 791±0.0 016 vs 0.3 015±0.0 012, P < 0.01).The EGb group had the same results as the normal control group.

CONCLUSION: EGb has prophylactic and therapeutic effects on CCl₄-induced rat liver fibrosis, probably through its anti-lipoperoxidation, suppressing the activation of hepatic stellate cells and transition and reducing the synthesis of hepatic type I collagen and TGF₁.

Long-term culture of functional liver tissue: three-dimensional coculture of primary hepatocytes and stellate cells

One of the greatest challenges in the attempt to create functional liver tissue in vitro is the maintenance of hepatocyte-specific functions. The pharmaceutical industry has long awaited the development of engineered liver tissue, which could represent a long-term, inducible, high-fidelity model for high-throughput screening of new drug compounds. It is also anticipated that such engineered models could one day be used in liver transplants, where replacement is limited by chronic donor shortages. As isolated hepatocytes dedifferentiate rapidly in culture the use of hepatocytes in long-term studies has proved to be a difficult challenge. Here we report a system of rat hepatocytes cocultured with primary rat hepatic stellate cells on a biodegradable poly(DL-lactic acid) substratum. These coculture conditions were found to encourage the rapid self-organization of three-dimensional spheroids. The spheroids formed exhibit hepatocyte-specific functionality (CYP-450 activity and albumin secretion) after almost 2 months in static culture.

Smads 2 and 3 are differentially activated by transforming growth factor-beta (TGF-beta ) in quiescent and activated hepatic stellate cells. Constitutive nuclear localization of Smads in activated cells is TGF-beta-independent

Hepatic stellate cells are the primary cell type responsible for matrix deposition in liver fibrosis, undergoing a process of transdifferentiation into fibrogenic myofibroblasts. These cells, which undergo a similar transdifferentiation process when cultured in vitro, are a major target of the profibrogenic agent transforming growth factor-beta (TGF-beta). We have studied activation of the TGF-beta downstream signaling molecules Smads 2, 3, and 4 in hepatic stellate cells (HSC) cultured in vitro for 1, 4, and 7 days, with quiescent, intermediate, and fully transdifferentiated phenotypes, respectively. Total levels of Smad4, common to multiple TGF-beta superfamily signaling pathways, do not change as HSC transdifferentiate, and the protein is found in both nucleus and cytoplasm, independent of treatment with TGF-beta or the nuclear export inhibitor leptomycin B. TGF-beta mediates activation of Smad2 primarily in early cultured cells and that of Smad3 primarily in transdifferentiated cells. The linker protein SARA, which is required for Smad2 signaling, disappears with transdifferentiation. Additionally, day 7 cells demonstrate constitutive phosphorylation and nuclear localization of Smad 2, which is not affected by pretreatment with TGF-beta-neutralizing antibodies, a type I TGF-beta receptor kinase inhibitor, or activin-neutralizing antibodies. These results demonstrate essential differences between TGF-beta-mediated signaling pathways in quiescent and in vitro transdifferentiated hepatic stellate cells.

Gene expression patterns in human liver cancers

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Using cDNA microarrays to characterize patterns of gene expression in HCC, we found consistent differences between the expression patterns in HCC compared with those seen in nontumor liver tissues. The expression patterns in HCC were also readily distinguished from those associated with tumors metastatic to liver. The global gene expression patterns intrinsic to each tumor were sufficiently distinctive that multiple tumor nodules from the same patient could usually be recognized and distinguished from all the others in the large sample set on the basis of their gene expression patterns alone. The distinctive gene expression patterns are characteristic of the tumors and not the patient; the expression programs seen in clonally independent tumor nodules in the same patient were no more similar than those in tumors from different patients. Moreover, clonally related tumor masses that showed distinct expression profiles were also distinguished by genotypic differences. Some features of the gene expression patterns were associated with specific phenotypic and genotypic characteristics of the tumors, including growth rate, vascular invasion, and p53 overexpression.

Gene expression patterns in human liver cancers

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Using cDNA microarrays to characterize patterns of gene expression in HCC, we found consistent differences between the expression patterns in HCC compared with those seen in nontumor liver tissues. The expression patterns in HCC were also readily distinguished from those associated with tumors metastatic to liver. The global gene expression patterns intrinsic to each tumor were sufficiently distinctive that multiple tumor nodules from the same patient could usually be recognized and distinguished from all the others in the large sample set on the basis of their gene expression patterns alone. The distinctive gene expression patterns are characteristic of the tumors and not the patient; the expression programs seen in clonally independent tumor nodules in the same patient were no more similar than those in tumors from different patients. Moreover, clonally related tumor masses that showed distinct expression profiles were also distinguished by genotypic differences. Some features of the gene expression patterns were associated with specific phenotypic and genotypic characteristics of the tumors, including growth rate, vascular invasion, and p53 overexpression.

Adhesion between cells and extracellular matrix with special reference to hepatic stellate cell adhesion to three-dimensional collagen fibers

Hepatic stellate cells are located in the perisinusoidal space (space of Disse), and extend their dendritic, thin membranous processes and fine fibrillar processes into this space. The stellate cells coexist with a three-dimensional extracellular matrix (ECM) in the perisinusoidal space. In turn the three-dimensional structure of the ECM regulates the proliferation, morphology, and functions of the stellate cell. In this review, the morphology of sites of adhesion between hepatic stellate cells and extracellular matrix is described. Hepatic stellate cells cultured in polystyrene dishes spread well, whereas the cells cultured on or in type I collagen gel become slender and elongate their long cellular processes which adhere directly to the collagen fibers. Cells in type I collagen gel form a large number of adhesive structures, each adhesive area forming a face but not a point. Adhesion molecules, integrins, for the ECM are localized on the cell surface. Elongation of the cellular processes occurs via integrin-binding to type I collagen fibers. The signal transduction mechanism, including protein and phosphatidylinositol phosphorylation, is critical to induce and sustain the cellular processes. Information on the three-dimensional structures of ECM is transmitted via three-dimensional adhesive structures containing the integrins.

Decorin and actin expression and distribution in patients with chronic hepatitis C following interferon-alfa-2b treatment

BACKGROUND/AIMS

Chronic hepatitis C can lead to cirrhosis and hepatocellular carcinoma. Interferon-alfa therapy may prevent the progression of the disease. The expressions of decorin and alfa-smooth muscle cell actin of the extracellular matrix play a central role in liver fibrosis. We set out to assess the expressions of these proteins in chronic hepatitis C patients, and to evaluate how they can be modified by interferon-alfa therapy.

METHODS

Twenty chronic hepatitis C patients received interferon-alfa-2b therapy for 6 months (group I) or 12 months (group II). Liver biopsy samples were taken before and after the therapy. The alfa-smooth muscle actin-positive cells were determined with a monoclonal antibody, and decorin expression was detected with a polyclonal antibody. The cells were evaluated with a semiquantitative scoring method. For statistical analysis, non-parametric methods were used.

RESULTS

Before the therapy, alfa-smooth muscle actin-labeled cells and marked decorin expression were present throughout all the acinar zones. Interferon-alfa-2b therapy resulted in significant decreases in both the number of alfa-smooth muscle actin-positive cells and the decorin expression. The alfa-smooth muscle actin-positive cells and decorin expression correlated with the histological activity index (R=0.72, p<0.03, R=0.68, p<0.05).

CONCLUSIONS

This study demonstrates that a large number of alfa-smooth muscle actin-positive cells and a marked decorin expression are frequent findings in chronic hepatitis C. Treatment with interferon-alfa-2b for 12 months reduced the number of labeled cells and the decorin expression. The results suggest that interferon-alfa-2b is capable of interfering with fibrogenesis in an early and presumably still reversible phase of chronic hepatitis C.

Expression of lumican in human lungs

The collagen-elastin-proteoglycan (PG) matrix is the key constituent of lung parenchyma and plays a major role in the mechanical behavior of lung tissues. However, the exact composition of the PG matrix in lungs has not yet been fully determined. In the present study we report the expression of leucine-rich repeat PGs in adult human lungs. PG extraction was performed on peripheral lung tissue from patients undergoing therapeutic lung resections. The samples were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting using antipeptide antisera specific to human lumican, decorin, biglycan, and fibromodulin. Control experiments to verify antiserum reactivity were performed with an extract of adult human articular cartilage, which is known to contain all four PGs. In all lung extracts analyzed, a single component of molecular weight 65 to 90 kD was detected for lumican. Decorin, biglycan, and fibromodulin were either not detected or were barely detectable in the lung extracts, but were readily visualized in the cartilage samples. Immunohistochemistry showed that lumican was diffusely present in peripheral lung tissue, mainly in vessel walls. These results suggest that lumican is a major component of the PG matrix in adult human lungs.

The scarring processes in mucosal tissues after immune injury

OBJECTIVES

An important feature of the healing processes is scar formation which may be necessary for organism survival. If it proceeds to the pathological state, it may impair normal function. The purpose of this review is to focus on some of the factors that may influence this process after immune injury, comparing it in the skin and mucosa.

METHODS

A detailed literature search of peer-reviewed journals was conducted. Studies reported in all languages considered relevant and important were used, including humans, animals, and tissue culture.

RESULTS

Analysis of the data indicate that the scarring process is mainly dependent on (1) the type of the lesion, (2) the cause and duration of injury, and (3) the tissue involved and its microenvironment. Equally important is the large spectrum and heterogenicity in the biological activity of fibroblasts and their role in scar formation.

CONCLUSIONS

The process of scar formation is complex and multistep process and is affected and influenced by local and systemic factors. Although it appears irreversible, there are pharmacological agents available, and under investigation, that may minimize its detrimental effects.

Morphology of sites of adhesion between hepatic stellate cells (vitamin A-storing cells) and a three-dimensional extracellular matrix

BACKGROUND

Hepatic stellate cells lie in the perisinusoidal space in a three-dimensionally distributed extracellular matrix (ECM). This three-dimensional structure of the ECM regulates the proliferation, morphology, and functions of the stellate cell. To investigate how the three-dimensional structure of ECM regulates behavior of the cells, we cultured stellate cells two- or three-dimensionally and examined the morphology of the cells in both cases as well as the localization of cell-surface adhesion molecules specific for the ECM.

METHODS

Isolated rat stellate cells and human stellate cells were cultured in Dulbecco's modified Eagle's medium. Rat stellate cells were cultured in non-coated polystyrene culture dishes, or on or in type I collagen gels. The morphology of cell-ECM adhesion was examined under transmission and scanning electron microscopes. Localization of integrin alpha2 and integrin beta1 in human stellate cells was examined by immunoelectron microscopy. Immunostaining was performed with a mouse monoclonal anti-human integrin alpha2 or integrin beta1 antibody and goat anti-mouse IgG coupled with 10-nm immunogold.

RESULTS

Hepatic stellate cells cultured in polystyrene dishes spread well. However, the cells cultured on or in the type I collagen gel became slender. The cells extended long cellular processes onto or into the gel. The cellular processes were entangled three-dimensionally with the type I collagen fibers and directly adhered to these fibers. The cells inoculated in type I collagen gels formed a large number of adhesive structures that resembled focal adhesions. These adhesive structures were distributed not only on the lower side but also on the upper side of both the cell bodies and cellular processes. Moreover, each adhesive area formed a face but not a point. Integrin alpha2 and integrin beta1 were detected on the surfaces of cell bodies, cellular processes, and microprojections.

CONCLUSIONS

The cells cultured in type I collagen gel develop a three-dimensional adhesive structure.

Hepatic stellate cells (Ito cells) but not collagen IV may partly be responsible for lower portal pressure after reversing secondary biliary cirrhosis in the rat

BACKGROUND/AIMS

Chronic bile duct obstruction in the rat leads to biliary cirrhosis and portal hypertension. Biliary decompression with Rouxen-Y choledocho-jejunostomy (RY) reverses most but not all of these changes. The aim of the present study was to determine whether hepatic stellate cells, as a main source of extracellular matrix proteins, participate in this process.

METHODS

Sprague-Dawley rats were allocated to one of three groups: Bile duct ligation (BDL) for 3 weeks, BDL followed by RY and sham-operated animals as controls (SHAM). At the end of the experimental period, portal pressure was measured, livers subjected to random sampling and hepatocytes, bile ducts/ductules, hepatic stellate cells and collagen IV determined stereologically. Hepatic stellate cells and collagen IV were characterized immunohistochemically with an antibody against desmin and collagen IV, respectively.

RESULTS

Volume fraction of hepatocytes decreased from 65.6 +/- 5.3 in sham-operated animals to 27.9 +/- 8.8% in bile duct ligated animals (p < 0.05). In contrast, volume fraction of bile ducts/ductules increased from 0.4 +/- 0.2 in sham-operated animals to 25.3 +/- 8.6% in bile duct ligated ones; similarly, hepatic stellate cells increased from 0.4 +/- 0.2 in sham-operated animals to 2.6 +/- 0.9% in bile duct ligated ones (p < 0.01) and collagen IV from 10.0 +/- 2.3 in sham-operated animals to 24.5 +/- 8.0% (p < 0.01) in bile duct ligated animals. These changes were partially reversed by Roux-en-Y choledocho-jejunostomy; hepatocytes, bile ducts/ductules, hepatic stellate cells and collagen IV averaging 54.8 +/- 13.1, 6.1 +/- 6.8, 1.6 +/- 0.6 and 14.5 +/- 3.6%, respectively (p < 0.05 RY vs. BDL). Portal pressure in sham-operated animals, bile duct ligated animals and those with a Roux-en-Y choledocho-jejunostomy averaged 13.4 +/- 0.7, 20.1 +/- 2.7 and 16.9 +/- 1.6 cm H2O, respectively, and correlated significantly with the volume fraction of hepatic stellate cells (rS = 0.96; p < 0.001) and less with collagen IV (rS = 0.61; p < 0.007). However, by stepwise regression, collagen IV did not significantly add to the ability of the equation to predict portal pressure.

CONCLUSIONS

These results lend further support to the notion that hepatic stellate cells are prominently involved in fibrogenesis and in the reversibility of these changes, but hepatic stellate cells do not completely revert to normal even 4 weeks after successful decompression. Furthermore, our data suggest that hepatic stellate cells may be related to maintenance of portal hypertension.