Fibronectin protects from excessive liver fibrosis by modulating the availability of and responsiveness of stellate cells to active TGF-β

Reactive Oxygen Species and its Manipulation Strategies in Cancer Treatment

Cancer is one of the serious diseases of modern times, occurring in all parts of the world and shows a wide range of effects on the human body. Reactive Oxygen Species (ROS) such as oxide and superoxide ions have both advantages and disadvantages during the progression of cancer, dependent on their concentration. It is a necessary part of the normal cellular mechanisms. Changes in its normal level can cause oncogenesis and other relatable problems. Metastasis can also be controlled by ROS levels in the tumor cells, which can be prevented by the use of antioxidants. However, ROS is also used for the initiation of apoptosis in cells by different mediators. There exists a cycle between the production of oxygen reactive species, their effect on the genes, role of mitochondria and the progression of tumors. ROS levels cause DNA damage by the oxidation process, gene damage, altered expression of the genes and signalling mechanisms. They finally lead to mitochondrial disability and mutations, resulting in cancer. This review summarizes the important role and activity of ROS in developing different types of cancers like cervical, gastric, bladder, liver, colorectal and ovarian cancers.

Ameliorating lung fibrosis and pulmonary function in diabetic mice: Therapeutic potential of mesenchymal stem cell

This study aimed to investigate the potential of mesenchymal stem cells (MSCs) in alleviating diabetic lung injury by decreasing inflammation, fibrosis and recovering tissue macrophage homeostasis. To induce pulmonary injuries in an in vivo murine model, we utilized a streptozotocin (STZ), and high-fat diet (HFD) induced diabetic C57 mouse model. Subsequently, human umbilical cord-derived MSCs (hUC-MSCs) were administered through the tail vein on a weekly basis for a duration of 4 weeks. In addition, in vitro experiments involved co-culturing of isolated primary abdominal macrophages from diabetic mice and high glucose-stimulated MLE-12 cells with hUC-MSCs. The objective was to evaluate if hUC-MSCs co-culturing could effectively mitigate cell inflammation and fibrosis. Following hUC-MSCs injection, diabetic mice displayed enhanced pulmonary functional parameters, reduced pulmonary fibrosis, and diminished inflammation. Notably, the dynamic equilibrium of lung macrophages shifted from the M1 phenotype to the M2 phenotype, accompanied by a notable reduction in various indicators associated with inflammation and fibrosis. Results from cell co-culturing experiments further supported this trend, demonstrating a reduction in inflammatory and fibrotic indicators. In conclusion, our findings suggest that hUC-MSCs treatment holds promise in mitigating diabetic pulmonary injury by significantly reducing inflammation, fibrosis and maintain tissue macrophage homeostasis within the lungs. This study sheds light on the therapeutic potential of hUC-MSCs in managing diabetic complications affecting the pulmonary system.

Insights into the metastatic bone marrow niche gained from fibronectin and β1 integrin transgenic mice

Tumor cells can migrate from a primary cancer and form metastases by localizing to niches within other organs including the bone marrow, where tumor cells may exploit the hematopoietic stem cell niche. The precise composition of the premetastatic and the hematopoietic niches and the degree of overlap between them remain elusive. Because the extracellular matrix protein fibronectin is expressed in the pre-metastatic lung microenvironment, we evaluated the implications of its loss, as well as those of loss of its primary receptor subunit, β1 integrin, in various bone marrow cell types both in breast cancer bone metastasis and hematopoiesis. Using eight transgenic mouse models, we established that fibronectin production by osterix-expressing marrow cells, or β1 integrin expression (on vav, mx, or leptin receptor expressing cells), affects MDA-MB-231 breast cancer cell numbers in the bone marrow. Additionally, we identified stromal subpopulations that modulate transmigration through blood vessel walls. Not the number of tumor cells, but rather the changes in the microenvironment dictated whether the tumor progresses. Furthermore, hematopoiesis, particularly myelopoiesis, was affected in some of the models showing changes in tumor homing. In conclusion, there is partial overlap between the pre-metastatic and the hematopoietic niches in the bone marrow. Moreover, we have delineated a cascade starting with fibronectin secreted by pre-osteoblastic cells, which potentially acts on β1 integrin in specific stromal cell subsets, thereby inhibiting the formation of new breast cancer lesions in the bone marrow. This work therefore sheds light on the role of various stromal cell subpopulations that influence tumor behavior and affect hematopoiesis.

Combinatorial Microgels for 3D ECM Screening and Heterogeneous Microenvironmental Culture of Primary Human Hepatic Stellate Cells

Nonalcoholic fatty liver disease affects 30% of the United States population and its progression can lead to nonalcoholic steatohepatitis (NASH), and increased risks for cirrhosis and hepatocellular carcinoma. NASH is characterized by a highly heterogeneous liver microenvironment created by the fibrotic activity of hepatic stellate cells (HSCs). While HSCs have been widely studied in 2D, further advancements in physiologically relevant 3D culture platforms for the in vitro modeling of these heterogeneous environments are needed. In this study, the use of stiffness-variable, extracellular matrix (ECM) protein-conjugated polyethylene glycol microgels as 3D cell culture scaffolds to modulate HSC activation is demonstrated. These microgels as a high throughput ECM screening system to identify HSC matrix remodeling and metabolic activities in distinct heterogeneous microenvironmental conditions are further employed. The 6 kPa fibronectin microgels are shown to significantly increase HSC matrix remodeling and metabolic activities in single or multiple-component microenvironments. Overall, heterogeneous microenvironments consisting of multiple distinct ECM microgels promoted a decrease in HSC matrix remodeling and metabolic activities compared to homogeneous microenvironments. The study envisions this ECM screening platform being adapted to a broad number of cell types to aid the identification of ECM microenvironments that best recapitulate the desired phenotype, differentiation, or drug efficacy.

Combinatorial Microgels for 3D ECM Screening and Heterogeneous Microenvironmental Culture of Primary Human Hepatic Stellate Cells

Non-alcoholic fatty liver disease affects 30% of the United States population and its progression can lead to non-alcoholic steatohepatitis (NASH), which can result in cirrhosis and hepatocellular carcinoma. NASH is characterized by a highly heterogeneous liver microenvironment created by the fibrotic activity of hepatic stellate cells (HSCs). While HSCs have been widely studied in 2D, further advancements in physiologically-relevant 3D culture platforms for the in vitro modeling of these heterogeneous environments are needed. In this study, we have demonstrated the use of stiffness-variable, ECM protein-conjugated polyethylene glycol microgels as 3D cell culture scaffolds to modulate HSC activation. We further employed these microgels as a high throughput ECM screening system to identify HSC matrix remodeling and metabolic activities in distinct heterogeneous microenvironmental conditions. In particular, 6 kPa fibronectin microgels were shown to significantly increase HSC matrix remodeling and metabolic activities in single or multiple component microenvironments. Overall, heterogeneous microenvironments consisting of multiple distinct ECM microgels promoted a decrease in HSC matrix remodeling and metabolic activities compared to homogeneous microenvironments. We envision this ECM screening platform being adapted to a broad number of cell types to aid the identification of ECM microenvironments that best recapitulate the desired phenotype, differentiation, or drug efficacy.

Proteome Profiling Identifies Serum Biomarkers in Rheumatoid Arthritis

Rheumatoid arthritis (RA) causes serious disability and productivity loss, and there is an urgent need for appropriate biomarkers for diagnosis, treatment assessment, and prognosis evaluation. To identify serum markers of RA, we performed mass spectrometry (MS)-based proteomics, and we obtained 24 important markers in normal and RA patient samples using a random forest machine learning model and 11 protein-protein interaction (PPI) network topological analysis methods. Markers were reanalyzed using additional proteomics datasets, immune infiltration status, tissue specificity, subcellular localization, correlation analysis with disease activity-based diagnostic indications, and diagnostic receiver-operating characteristic analysis. We discovered that ORM1 in serum is significantly differentially expressed in normal and RA patient samples, which is positively correlated with disease activity, and is closely related to CD56dim natural killer cell, effector memory CD8+T cell, and natural killer cell in the pathological mechanism, which can be better utilized for future research on RA. This study supplies a comprehensive strategy for discovering potential serum biomarkers of RA and provides a different perspective for comprehending the pathological mechanism of RA, identifying potential therapeutic targets, and disease management.

Genome-wide analysis of somatic noncoding mutation patterns in cancer

We established a genome-wide compendium of somatic mutation events in 3949 whole cancer genomes representing 19 tumor types. Protein-coding events captured well-established drivers. Noncoding events near tissue-specific genes, such as ALB in the liver or KLK3 in the prostate, characterized localized passenger mutation patterns and may reflect tumor-cell-of-origin imprinting. Noncoding events in regulatory promoter and enhancer regions frequently involved cancer-relevant genes such as BCL6, FGFR2, RAD51B, SMC6, TERT, and XBP1 and represent possible drivers. Unlike most noncoding regulatory events, XBP1 mutations primarily accumulated outside the gene's promoter, and we validated their effect on gene expression using CRISPR-interference screening and luciferase reporter assays. Broadly, our study provides a blueprint for capturing mutation events across the entire genome to guide advances in biological discovery, therapies, and diagnostics.

High throughput interrogation of human liver stellate cells reveals microenvironmental regulation of phenotype

Liver fibrosis is a common feature of progressive liver disease and is manifested as a dynamic series of alterations in both the biochemical and biophysical properties of the liver. Hepatic stellate cells (HSCs) reside within the perisinusoidal space of the liver sinusoid and are one of the main drivers of liver fibrosis, yet it remains unclear how changes to the sinusoidal microenvironment impact HSC phenotype in the context of liver fibrosis. Cellular microarrays were used to examine and deconstruct the impacts of bio-chemo-mechanical changes on activated HSCs in vitro. Extracellular matrix (ECM) composition and stiffness were found to act individually and in combination to regulate HSC fibrogenic phenotype and proliferation. Hyaluronic acid and collagen III promoted elevated collagen I expression while collagen IV mediated a decrease. Previously activated HSCs exhibited reduced lysyl oxidase (Lox) expression as array substrate stiffness increased, with less dependence on ECM composition. Collagens III and IV increased HSC proliferation, whereas hyaluronic acid had the opposite effect. Meta-analysis performed on these data revealed distinct phenotypic clusters (e.g. low fibrogenesis/high proliferation) as a direct function of their microenvironmental composition. Notably, soft microenvironments mimicking healthy tissue (1 kPa), promoted higher levels of intracellular collagen I and Lox expression in activated HSCs, compared to stiff microenvironments mimicking fibrotic tissue (25 kPa). Collectively, these data suggest potential HSC functional adaptations in response to specific bio-chemo-mechanical changes relevant towards the development of therapeutic interventions. These findings also underscore the importance of the microenvironment when interrogating HSC behavior in healthy, disease, and treatment settings. STATEMENT OF SIGNIFICANCE: In this work we utilized high-throughput cellular microarray technology to systematically interrogate the complex interactions between HSCs and their microenvironment in the context of liver fibrosis. We observed that HSC phenotype is regulated by ECM composition and stiffness, and that these phenotypes can be classified into distinct clusters based on their microenvironmental context. Moreover, the range of these phenotypic responses to microenvironmental stimuli is substantial and a direct consequence of the combinatorial pairing of ECM protein and stiffness signals. We also observed a novel role for microenvironmental context in affecting HSC responses to potential fibrosis therapeutics.

A Mixture of Pure, Isolated Polyphenols Worsens the Insulin Resistance and Induces Kidney and Liver Fibrosis Markers in Diet-Induced Obese Mice

Obesity is a worldwide epidemic with severe metabolic consequences. Polyphenols are secondary metabolites in plants and the most abundant dietary antioxidants, which possess a wide range of health effects. The most relevant food sources are fruit and vegetables, red wine, black and green tea, coffee, virgin olive oil, and chocolate, as well as nuts, seeds, herbs, and spices. The aim of this work was to evaluate the ability of a pure, isolated polyphenol supplementation to counteract the pernicious metabolic effects of a high-fat diet (HFD). Our results indicated that the administration of pure, isolated polyphenols under HFD conditions for 26 weeks worsened the glucose metabolism in diet-induced obese mice. The data showed that the main target organ for these undesirable effects were the kidneys, where we observed fibrotic, oxidative, and kidney-disease markers. This work led us to conclude that the administration of pure polyphenols as a food supplement would not be advisable. Instead, the ingestion of complete "whole" foods would be the best way to get the health effects of bioactive compounds such as polyphenols.

Conditions for maintenance of hepatocyte differentiation and function in 3D cultures

Spheroid cultures of primary human hepatocytes (PHH) are used in studies of hepatic drug metabolism and toxicity. The cultures are maintained under different conditions, with possible confounding results. We performed an in-depth analysis of the influence of various culture conditions to find the optimal conditions for the maintenance of an in vivo like phenotype. The formation, protein expression, and function of PHH spheroids were followed for three weeks in a high-throughput 384-well format. Medium composition affected spheroid histology, global proteome profile, drug metabolism and drug-induced toxicity. No epithelial-mesenchymal transition was observed. Media with fasting glucose and insulin levels gave spheroids with phenotypes closest to normal PHH. The most expensive medium resulted in PHH features most divergent from that of native PHH. Our results provide a protocol for culture of healthy PHH with maintained function - a prerequisite for studies of hepatocyte homeostasis and more reproducible hepatocyte research.

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3D spheroid cultures were established in 384-well format

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Eight different media variants were used to optimize the 3D cultures

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Optimized William's medium was as good as expensive commercial medium

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The 3D cultures were used to study drug metabolism and toxicity

Inhibition of fibronectin accumulation suppresses tumor growth

Understanding how the extracellular matrix affects cancer development constitutes an emerging research field. Fibronectin and collagen are two intriguing matrix components found in cancer. Large concentrations of fibronectin or collagen type I have been implicated in poor prognosis in patients. In a mouse model, we had shown that genetically decreasing circulating fibronectin resulted in smaller tumors. We therefore aimed to manipulate fibronectin pharmacologically and determine how cancer development is affected. Deletion of fibronectin in human breast cancer cells (MDA-MB-231) using shRNA (knockdown: Kd) improved survival and diminished tumor burden in a model of metastatic lesions and in a model of local growth. Based on these findings, it seemed reasonable to attempt to prevent fibronectin accumulation using a bacterial derived peptide called pUR4. Treatment with this peptide for 10 days in the breast cancer local growth model or for 5 days in a melanoma skin cancer model (B16) was associated with a significant suppression of cancer growth. Treatment aimed at inhibiting collagen type I accumulation without interfering with fibronectin could not affect any changes in vivo. In the absence of fibronectin, diminished cancer progression was due to inhibition of proliferation, even though changes in blood vessels were also detected. Decreased proliferation could be attributed to decreased ERK phosphorylation and diminished YAP expression. In summary, manipulating fibronectin diminishes cancer progression, mostly by suppressing cell proliferation. This suggests that matrix modulation could be used as an adjuvant to conventional therapy as long as a decrease in fibronectin is obtained.

Caffey disease is associated with distinct arginine to cysteine substitutions in the proα1(I) chain of type I procollagen

PURPOSE

Infantile Caffey disease is a rare disorder characterized by acute inflammation with subperiosteal new bone formation, associated with fever, pain, and swelling of the overlying soft tissue. Symptoms arise within the first weeks after birth and spontaneously resolve before the age of two years. Many, but not all, affected individuals carry the heterozygous pathogenic COL1A1 variant (c.3040C>T, p.(Arg1014Cys)).

METHODS

We sequenced COL1A1 in 28 families with a suspicion of Caffey disease and performed ultrastructural, immunocytochemical, and biochemical collagen studies on patient skin biopsies.

RESULTS

We identified the p.(Arg1014Cys) variant in 23 families and discovered a novel heterozygous pathogenic COL1A1 variant (c.2752C>T, p.(Arg918Cys)) in five. Both arginine to cysteine substitutions are located in the triple helical domain of the proα1(I) procollagen chain. Dermal fibroblasts (one patient with p.(Arg1014Cys) and one with p.(Arg918Cys)) produced molecules with disulfide-linked proα1(I) chains, which were secreted only with p.(Arg1014Cys). No intracellular accumulation of type I procollagen was detected. The dermis revealed mild ultrastructural abnormalities in collagen fibril diameter and packing.

CONCLUSION

The discovery of this novel pathogenic variant expands the limited spectrum of arginine to cysteine substitutions in type I procollagen. Furthermore, it confirms allelic heterogeneity in Caffey disease and impacts its molecular confirmation.

Ameliorative effects of Schisandrin B on Schistosoma mansoni-induced hepatic fibrosis in vivo

Schistosomiasis is second only to malaria as the most devastating parasitic disease in the world. It is caused by the helminths Schistosoma mansoni (S. mansoni), S. haematobium, or S. japonicum. Typically, patients with schistosomiasis suffer from symptoms of liver fibrosis and hepatosplenomegaly. Currently, patients were treated with praziquantel. Although praziquantel effectively kills the worm, it cannot prevent re-infection or resolve liver fibrosis. Also, current treatment options are not ample to completely cure liver fibrosis and splenic damages. Moreover, resistance of praziquantel has been reported in vivo and in vitro studies. Therefore, finding new effective treatment agents is urgently needed. Schisandrin B (Sch B) of Schisandra chinensis has been shown to protect against different liver injuries including fatty liver disease, hepatotoxicity, fibrosis, and hepatoma. We herein investigate the potential of using Sch B to treat S. mansoni-induced liver fibrosis. Results from the present study demonstrate that Sch B is beneficial in treating S. mansoni-induced liver fibrosis and splenic damages, through inhibition of inflammasome activation and apoptosis; and aside from that regulates host immune responses. Besides, Sch B treatment damages male adult worm in the mice, consequently helps to reduce egg production and lessen the parasite burden.

Collagen Characterization in a Model of Nonalcoholic Steatohepatitis with Fibrosis; A Call for Development of Targeted Therapeutics

Left untreated, nonalcoholic fatty liver disease can progress to nonalcoholic steatohepatitis (NASH), fibrosis, and end-stage liver disease. To date, few if any therapies have proven effective against NASH with fibrosis. Quantification and qualification of hepatic scar might enable development of more effective targeted therapies. In a murine model of NASH induced by diet, we characterized fibrillar collagen deposition within the hepatic parenchyma. At harvest, livers from the modified diet cohort exhibited NASH with fibrosis. Transcriptomic analysis of hepatic tissue revealed increased col1a1, col1a2, and col3a1, each of which correlated directly with hepatic hydroxyproline content. Circular polarized microscopic analysis of Picrosirius red-stained liver sections revealed deposition of collagen type I within the parenchyma. Development of therapeutics designed to mitigate collagen type I accumulation might prove effective in NASH with fibrosis.

Design and Evaluation of a Polypeptide that Mimics the Integrin Binding Site for EDA Fibronectin to Block Profibrotic Cell Activity

Fibrosis is characterized by excessive production of disorganized collagen- and fibronectin-rich extracellular matrices (ECMs) and is driven by the persistence of myofibroblasts within tissues. A key protein contributing to myofibroblast differentiation is extra domain A fibronectin (EDA-FN). We sought to target and interfere with interactions between EDA-FN and its integrin receptors to effectively inhibit profibrotic activity and myofibroblast formation. Molecular docking was used to assist in the design of a blocking polypeptide (antifibrotic 38-amino-acid polypeptide, AF38Pep) for specific inhibition of EDA-FN associations with the fibroblast-expressed integrins α₄β₁ and α₄β₇. Blocking peptides were designed and evaluated in silico before synthesis, confirmation of binding specificity, and evaluation in vitro. We identified the high-affinity EDA-FN C-C′ loop binding cleft within integrins α₄β₁ and α₄β₇. The polypeptide with the highest predicted binding affinity, AF38Pep, was synthesized and could achieve specific binding to myofibroblast fibronectin-rich ECM and EDA-FN C-C′ loop peptides. AF38Pep demonstrated potent myofibroblast inhibitory activity at 10 µg/mL and was not cytotoxic. Treatment with AF38Pep prevented integrin α₄β₁-mediated focal adhesion kinase (FAK) activation and early signaling through extracellular-signal-regulated kinases 1 and 2 (ERK1/2), attenuated the expression of pro-matrix metalloproteinase 9 (MMP9) and pro-MMP2, and inhibited collagen synthesis and deposition. Immunocytochemistry staining revealed an inhibition of α-smooth muscle actin (α-SMA) incorporation into actin stress fibers and attenuated cell contraction. Increases in the expression of mRNA associated with fibrosis and downstream from integrin signaling were inhibited by treatment with AF38Pep. Our study suggested that AF38Pep could successfully interfere with EDA-FN C-C′ loop-specific integrin interactions and could act as an effective inhibitor of fibroblast of myofibroblast differentiation.

Autophagy, tissue repair, and fibrosis: a delicate balance

Tissue repair and fibrosis, an abnormal form of repair, occur in most human organs in response to injury or inflammation. Fibroblasts play a major role in the normal repair process by differentiating into myofibroblasts that synthesize extracellular matrix (ECM) components and favor tissue remodeling to reestablish normal function and integrity. However, their persistent accumulation at the site of injury is a hallmark of fibrosis. Autophagy is a catabolic process that occurs in eukaryotic cells as a stress response to allow cell survival and maintenance of cellular homeostasis by degrading and recycling intracellular components. Recent advances identify autophagy as an important regulator of myofibroblast differentiation, tissue remodeling, and fibrogenesis. In this mini-review, we provide an overview of the interactions between autophagy, ECM, and fibrosis, and emphasize the molecular mechanisms involved in myofibroblast differentiation. We also describe the emerging concept of secretory autophagy as a new avenue for intercellular communication at the site of tissue injury and repair.

Fibronectin and Its Receptors in Hematopoiesis

Fibronectin is a ubiquitous extracellular matrix protein that is produced by many cell types in the bone marrow and distributed throughout it. Cells of the stem cell niche produce the various isoforms of this protein. Fibronectin not only provides the cells a scaffold to bind to, but it also modulates their behavior by binding to receptors on the adjacent hematopoietic stem cells and stromal cells. These receptors, which include integrins such as α4β1, α9β1, α4β7, α5β1, αvβ3, Toll-like receptor-4 (TLR-4), and CD44, are found on the hematopoietic stem cell. Because the knockout of fibronectin is lethal during embryonal development and because fibronectin is produced by almost all cell types in mammals, the study of its role in hematopoiesis is difficult. Nevertheless, strong and direct evidence exists for its stimulation of myelopoiesis and thrombopoiesis using in vivo models. Other reviewed effects can be deduced from the study of fibronectin receptors, which showed their activation modifies the behavior of hematopoietic stem cells. Erythropoiesis was only stimulated under hemolytic stress, and mostly late stages of lymphocytic differentiation were modulated. Because fibronectin is ubiquitously expressed, these interactions in health and disease need to be taken into account whenever any molecule is evaluated in hematopoiesis.

Specific, targetable interactions with the microenvironment influence imatinib-resistant chronic myeloid leukemia

Therapy resistance in leukemia may be due to cancer cell-intrinsic and/or -extrinsic mechanisms. Mutations within BCR-ABL1, the oncogene giving rise to chronic myeloid leukemia (CML), lead to resistance to tyrosine kinase inhibitors (TKI), and some are associated with clinically more aggressive disease and worse outcome. Using the retroviral transduction/transplantation model of CML and human cell lines we faithfully recapitulate accelerated disease course in TKI resistance. We show in various models, that murine and human imatinib-resistant leukemia cells positive for the oncogene BCR-ABL1T315I differ from BCR-ABL1 native (BCR-ABL1) cells with regards to niche location and specific niche interactions. We implicate a pathway via integrin β3, integrin-linked kinase (ILK) and its role in deposition of the extracellular matrix (ECM) protein fibronectin as causative of these differences. We demonstrate a trend towards a reduced BCR-ABL1T315I+ tumor burden and significantly prolonged survival of mice with BCR-ABL1T315I+ CML treated with fibronectin or an ILK inhibitor in xenogeneic and syngeneic murine transplantation models, respectively. These data suggest that interactions with ECM proteins via the integrin β3/ILK-mediated signaling pathway in BCR-ABL1T315I+ cells differentially and specifically influence leukemia progression. Niche targeting via modulation of the ECM may be a feasible therapeutic approach to consider in this setting.

Noninvasive Assessment of Liver Fibrosis: Current and Future Clinical and Molecular Perspectives

Liver fibrosis is one of the risk factors for hepatocellular carcinoma (HCC) development. The staging of liver fibrosis can be evaluated only via a liver biopsy, which is an invasive procedure. Noninvasive methods for the diagnosis of liver fibrosis can be divided into morphological tests such as elastography and serum biochemical tests. Transient elastography is reported to have excellent performance in the diagnosis of liver fibrosis and has been accepted as a useful tool for the prediction of HCC development and other clinical outcomes. Two-dimensional shear wave elastography is a new technique and provides a real-time stiffness image. Serum fibrosis markers have been studied based on the mechanism of fibrogenesis and fibrolysis. In the healthy liver, homeostasis of the extracellular matrix is maintained directly by enzymes called matrix metalloproteinases (MMPs) and their specific inhibitors, tissue inhibitors of metalloproteinases (TIMPs). MMPs and TIMPs could be useful serum biomarkers for liver fibrosis and promising candidates for the treatment of liver fibrosis. Further studies are required to establish liver fibrosis-specific markers based on further clinical and molecular research. In this review, we summarize noninvasive fibrosis tests and molecular mechanism of liver fibrosis in current daily clinical practice.

Relationship between IL-8 Circulating Levels and TLR2 Hepatic Expression in Women with Morbid Obesity and Nonalcoholic Steatohepatitis

The progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) is linked to systemic inflammation. Currently, two of the aspects that need further investigation are diagnosis and treatment of NASH. In this sense, the aim of this study was to assess the relationship between circulating levels of cytokines, hepatic expression of toll-like receptors (TLRs), and degrees of NAFLD, and to investigate whether these levels could serve as noninvasive biomarkers of NASH. The present study assessed plasma levels of cytokines in 29 normal-weight women and 82 women with morbid obesity (MO) (subclassified: normal liver (n = 29), simple steatosis (n = 32), and NASH (n = 21)). We used enzyme-linked immunosorbent assays (ELISAs) to quantify cytokine and TLR4 levels and RTqPCR to assess TLRs hepatic expression. IL-1β, IL-8, IL-10, TNF-α, tPAI-1, and MCP-1 levels were increased, and adiponectin levels were decreased in women with MO. IL-8 was significantly higher in MO with NASH than in NL. To sum up, high levels of IL-8 were associated with the diagnosis of NASH in a cohort of women with morbid obesity. Moreover, a positive correlation between TLR2 hepatic expression and IL-8 circulating levels was found.

Inflammatory networks cultivate cancer cell metastasis to the liver

The liver is the most frequent site of metastatic spread in malignancies that arise from the digestive system, including pancreatic ductal adenocarcinoma (PDAC). Metastasis to the liver is a major cause of morbidity and mortality in cancer patients, yet mechanisms that govern this process remain poorly understood. Until recently, liver tropism of metastasis was believed to be driven by mechanical factors that direct the passive flow of circulating cancer cells to the liver. However, emerging evidence now shows that liver metastasis is a dynamic process that is, at least in part, dependent on the formation of a "pro-metastatic niche". Key features of this niche are myeloid cells and fibrosis that support cancer cell colonization and growth. Inflammatory responses that are mounted early during primary tumor development are critical for the recruitment of myeloid cells and the deposition of extracellular matrix (ECM) proteins within the liver. Intriguingly, the inflammatory processes that direct the formation of a pro-metastatic niche share remarkable resemblance to mechanisms of liver injury and regeneration, suggesting that cancer co-opts physiological liver functions to support metastasis. Therefore, therapeutic strategies that target key elements of liver inflammation that form the basis of a pro-metastatic niche may lead to effective treatments for metastatic cancer.

Nonalcoholic Fatty Liver Disease: A Challenge from Mechanisms to Therapy

Focusing on previously published mechanisms of non-alcoholic fatty liver disease (NAFLD), their uncertainty does not always permit a clear elucidation of the grassroot alterations that are at the basis of the wide-spread illness, and thus curing it is still a challenge. There is somehow exceptional progress, but many controversies persist in NAFLD research and clinical investigation. It is likely that hidden mechanisms will be brought to light in the near future. Hereby, the authors present, with some criticism, classical mechanisms that stand at the basis of NAFLD, and consider contextually different emerging processes. Without ascertaining these complex interactions, investigators have a long way left ahead before finding an effective therapy for NAFLD beyond diet and exercise.

Metabolic Signature of Hepatic Fibrosis: From Individual Pathways to Systems Biology

Hepatic fibrosis is a major cause of morbidity and mortality worldwide, as it ultimately leads to cirrhosis, which is estimated to affect up to 2% of the global population. Hepatic fibrosis is confirmed by liver biopsy, and the erroneous nature of this technique necessitates the search for noninvasive alternatives. However, current biomarker algorithms for hepatic fibrosis have many limitations. Given that the liver is the largest organ and a major metabolic hub in the body, probing the metabolic signature of hepatic fibrosis holds promise for the discovery of new markers and therapeutic targets. Regarding individual metabolic pathways, accumulating evidence shows that hepatic fibrosis leads to alterations in carbohydrate metabolism, as aerobic glycolysis is aggravated in activated hepatic stellate cells (HSCs) and the whole fibrotic liver; in amino acid metabolism, as Fischer’s ratio (branched-chain amino acids/aromatic amino acids) decreases in patients with hepatic fibrosis; and in lipid metabolism, as HSCs lose vitamin A-containing lipid droplets during transdifferentiation, and cirrhotic patients have decreased serum lipids. The current review also summarizes recent findings of metabolic alterations relevant to hepatic fibrosis based on systems biology approaches, including transcriptomics, proteomics, and metabolomics in vitro, in animal models and in humans.

TGF-β in Hepatic Stellate Cell Activation and Liver Fibrogenesis-Updated 2019

Liver fibrosis is an advanced liver disease condition, which could progress to cirrhosis and hepatocellular carcinoma. To date, there is no direct approved antifibrotic therapy, and current treatment is mainly the removal of the causative factor. Transforming growth factor (TGF)-β is a master profibrogenic cytokine and a promising target to treat fibrosis. However, TGF-β has broad biological functions and its inhibition induces non-desirable side effects, which override therapeutic benefits. Therefore, understanding the pleiotropic effects of TGF-β and its upstream and downstream regulatory mechanisms will help to design better TGF-β based therapeutics. Here, we summarize recent discoveries and milestones on the TGF-β signaling pathway related to liver fibrosis and hepatic stellate cell (HSC) activation, emphasizing research of the last five years. This comprises impact of TGF-β on liver fibrogenesis related biological processes, such as senescence, metabolism, reactive oxygen species generation, epigenetics, circadian rhythm, epithelial mesenchymal transition, and endothelial-mesenchymal transition. We also describe the influence of the microenvironment on the response of HSC to TGF-β. Finally, we discuss new approaches to target the TGF-β pathway, name current clinical trials, and explain promises and drawbacks that deserve to be adequately addressed.

MicroRNA-29a Suppresses CD36 to Ameliorate High Fat Diet-Induced Steatohepatitis and Liver Fibrosis in Mice

MicroRNA-29 (miR-29) has been shown to play a critical role in reducing inflammation and fibrosis following liver injury. Non-alcoholic fatty liver disease (NAFLD) occurs when fat is deposited (steatosis) in the liver due to causes other than excessive alcohol use and is associated with liver fibrosis. In this study, we asked whether miR-29a could reduce experimental high fat diet (HFD)-induced obesity and liver fibrosis in mice. We performed systematical expression analyses of miR-29a transgenic mice (miR-29aTg mice) and wild-type littermates subjected to HFD-induced NAFLD. The results demonstrated that increased miR-29a not only alleviated HFD-induced body weight gain but also subcutaneous, visceral, and intestinal fat accumulation and hepatocellular steatosis in mice. Furthermore, hepatic tissue in the miR-29aTg mice displayed a weak fibrotic matrix concomitant with low fibrotic collagen1α1 expression within the affected tissues compared to the wild-type (WT) mice fed the HFD diet. Increased miR-29a signaling also resulted in the downregulation of expression of the epithelial mesenchymal transition-executing transcription factor snail, mesenchymal markers vimentin, and such pro-inflammation markers as il6 and mcp1 within the liver tissue. Meanwhile, miR-29aTg-HFD mice exhibited significantly lower levels of peroxisome proliferator-activated receptor γ (PPARγ), mitochondrial transcription factor A TFAM, and mitochondria DNA content in the liver than the WT-HFD mice. An in vitro luciferase reporter assay further confirmed that miR-29a mimic transfection reduced fatty acid translocase CD36 expression in HepG2 cells. Conclusion: Our data provide new insights that miR-29a can improve HDF-induced obesity, hepatocellular steatosis, and fibrosis, as well as highlight the role of miR-29a in regulation of NAFLD.

DynOVis: a web tool to study dynamic perturbations for capturing dose-over-time effects in biological networks

Background

The development of high throughput sequencing techniques provides us with the possibilities to obtain large data sets, which capture the effect of dynamic perturbations on cellular processes. However, because of the dynamic nature of these processes, the analysis of the results is challenging. Therefore, there is a great need for bioinformatics tools that address this problem.

Results

Here we present DynOVis, a network visualization tool that can capture dynamic dose-over-time effects in biological networks. DynOVis is an integrated work frame of R packages and JavaScript libraries and offers a force-directed graph network style, involving multiple network analysis methods such as degree threshold, but more importantly, it allows for node expression animations as well as a frame-by-frame view of the dynamic exposure. Valuable biological information can be highlighted on the nodes in the network, by the integration of various databases within DynOVis. This information includes pathway-to-gene associations from ConsensusPathDB, disease-to-gene associations from the Comparative Toxicogenomics databases, as well as Entrez gene ID, gene symbol, gene synonyms and gene type from the NCBI database.

Conclusions

DynOVis could be a useful tool to analyse biological networks which have a dynamic nature. It can visualize the dynamic perturbations in biological networks and allows the user to investigate the changes over time. The integrated data from various online databases makes it easy to identify the biological relevance of nodes in the network. With DynOVis we offer a service that is easy to use and does not require any bioinformatics skills to visualize a network.

Effect of glabridin on collagen deposition in liver and amelioration of hepatocyte destruction in diabetes rats

Abnormalities in insulin hormone levels leads to a hyperglycemic condition of diabetic mellitus. Hyperglycemia seriously induces organ and system destructions. The excessive accumulation of collagen fiber deposits occurs in inflammatory and reorganization processes of chronic liver diseases in type I insulin-dependent diabetes. Regarding the research objective, glabridin (GLB), an active compound of licorice, was used as a daily supplement (40 mg/kg) in order to decrease hepatocyte destruction and collagen deposition in liver tissue of diabetic animals induced by streptozotocin. A total of 40 were randomly allocated to five groups (each, n=10), control, control treated with GLB (GLB), diabetic rats (DM) injected with single dose of streptozotocin (60 mg/kg) to induce a diabetic condition, diabetic rats receiving GLB (DM+GLB; 40 mg/kg) and diabetic rats treated with glibenclamide (DM+GL; 4 mg/kg). Characteristic histopathological changes in liver cells and tissues of rats were determined by Masson's trichrome staining and transmission electron microscopy (TEM). Western blotting was used to detect the expression of the key markers, collagen type I and fibronectin proteins. The histological investigation of liver tissue of the DM group revealed that the collagen fiber deposition was increased in the periportal, pericentral and perisinusoidal spaces compared with controls. Hepatocytes appeared as small and fragmented cells in TEM examination. Collagenization of the perisinusoidal space was recently demonstrated to represent a new aspect of the microvascular abnormalities and liver fibrosis. Healthy hepatocytes with round nucleus were observed following supplementation of glabridin. In addition, collagen fiber deposition was reduced in the area adjacent to the perisinusoidal space. The expression of collagen type I and fibronectin decreased strongly following glabridin supplementation in DM+GLB rats compared with DM rats, indicating that the hepatic tissue reorganization regained its normal morphology. These findings suggest that it may be beneficial to examine the role of glabridin as a therapeutic agent in diabetes treatment in future research.

Blended electrospinning with human liver extracellular matrix for engineering new hepatic microenvironments

Tissue engineering of a transplantable liver could provide an alternative to donor livers for transplant, solving the problem of escalating donor shortages. One of the challenges for tissue engineers is the extracellular matrix (ECM); a finely controlled in vivo niche which supports hepatocytes. Polymers and decellularized tissue scaffolds each provide some of the necessary biological cues for hepatocytes, however, neither alone has proved sufficient. Enhancing microenvironments using bioactive molecules allows researchers to create more appropriate niches for hepatocytes. We combined decellularized human liver tissue with electrospun polymers to produce a niche for hepatocytes and compared the human liver ECM to its individual components; Collagen I, Laminin-521 and Fibronectin. The resulting scaffolds were validated using THLE-3 hepatocytes. Immunohistochemistry confirmed retention of proteins in the scaffolds. Mechanical testing demonstrated significant increases in the Young's Modulus of the decellularized ECM scaffold; providing significantly stiffer environments for hepatocytes. Each scaffold maintained hepatocyte growth, albumin production and influenced expression of key hepatic genes, with the decellularized ECM scaffolds exerting an influence which is not recapitulated by individual ECM components. Blended protein:polymer scaffolds provide a viable, translatable niche for hepatocytes and offers a solution to current obstacles in disease modelling and liver tissue engineering.

Ron Receptor Signaling Ameliorates Hepatic Fibrosis in a Diet-Induced Nonalcoholic Steatohepatitis Mouse Model

Liver fibrosis is commonly observed in the terminal stages of nonalcoholic steatohepatitis (NASH) and with no specific and effective antifibrotic therapies available, this disease is a major global health burden. The MSP/Ron receptor axis has been shown to have anti-inflammatory properties in a number of mouse models, due at least in part, to its ability to limit pro-inflammatory responses in tissue-resident macrophages and hepatocytes. In this study, we established the role of the Ron receptor in steatohepatitis-induced hepatic fibrosis using Ron ligand domain knockout mice on an apolipoprotein E knockout background (DKO). After 18 weeks of high-fat high-cholesterol feeding, loss of Ron activation resulted in exacerbated NASH-associated steatosis which is precedent to hepatocellular injury, inflammation and fibrosis. ¹H nuclear magnetic resonance (NMR)-based metabolomics identified significant changes in serum metabolites that can modulate the intrahepatic lipid pool in hepatic steatosis. Serum from DKO mice had higher concentrations of lipids, VLDL/LDL and pyruvate, whereas glycine levels were reduced. Parallel to the aggravated steatohepatitis, increased accumulation of collagen, inflammatory immune cells and collagen producing-myofibroblasts were seen in the livers of DKO mice. Gene expression profiling revealed that DKO mice exhibited elevated expression of genes encoding Ron receptor ligand MSP, collagens, ECM remodeling proteins and pro-fibrogenic cytokines in the liver. Our results demonstrate the protective effects of Ron receptor activation on NASH-induced hepatic fibrosis.

Glaucomatous cell derived matrices differentially modulate non-glaucomatous trabecular meshwork cellular behavior

Ocular hypertension is a causal risk-factor to developing glaucoma. This is associated with stiffening of the trabecular meshwork (TM), the primary site of resistance to aqueous-humor-outflow. The mechanisms underlying this stiffening or how pathologic extracellular matrix (ECM) affects cell function are poorly understood. It is recognized that mechanotransduction systems allow cells to sense and translate the intrinsic biophysical properties of ECM into intracellular signals to control gene transcription, protein expression, and cell behavior. Using an anterior segment perfusion model, we document that there are significantly more low flow regions that are much stiffer, and fewer high flow regions that are less stiff in glaucomatous TM (GTM) when compared to non-glaucomatous TMs (NTM). GTM tissue also has fewer cells overall when compared with NTM tissue. In order to study the role of pathologic ECM in glaucoma disease progression, we conducted studies using cell derived matrices (CDM). First, we characterized the mechanics, composition and organization of fibronectin in ECM deposited by GTM and NTM cells treated with glucocorticosteroids. Then, we determined that these GTM-derived ECM are able to induce stiffening of normal NTM cells, and alter their gene/protein expression to resemble that of a glaucomatous phenotype. Further, we demonstrate that GTM-derived ECM causes endoplasmic reticular stress in NTM. They also became resistant to being reorganized by these NTM cells. These phenomena were exacerbated by ECMs obtained from steroid treated glaucoma model groups. Collectively, our data demonstrates that CDMs represent a novel tool for the study of bidirectional interactions between TM cells and their immediate microenvironment.

STATEMENT OF SIGNIFICANCE

Extracellular matrix (ECM) changes are prevalent in a number of diseases. The precise mechanisms by which changes in the ECM contribute to disease progression is unclear, primarily due to absence of appropriate models. Here, using glaucoma as a disease model, we document changes in cell derived matrix (CDM) and tissue mechanics that contribute to the pathology. Subsequently, we determine the effect that ECMs from diseased and healthy individuals have on healthy cell behaviors. Data emanating from this study demonstrate that CDMs are a potent tool for the study of cell-ECM interactions.

Targeting renal fibrosis: Mechanisms and drug delivery systems

Renal fibrosis is the common outcome of many chronic kidney diseases (CKD) independent of the underlying etiology. Despite a host of promising experimental data, currently available strategies only ameliorate or delay the progression of CKD but do not reverse fibrosis. One of the major impediments of translating novel antifibrotic strategies from bench to bedside is due to the intricacies of the drug delivery process. In this review, we briefly describe mechanisms of renal fibrosis and methods of drug transfer into the kidney. Various tools used in gene therapy to administer nucleic acids in vivo are discussed. Furthermore, we review the modes of action of protein- or peptide-based drugs with target-specific antibodies and cytokines incorporated in hydrogels. Additionally, we assess an intriguing new method to deliver drugs specifically to tubular epithelial cells via conjugation with ligands binding to the megalin receptor. Finally, plant-derived compounds with antifibrotic properties are also summarized.

Exendin-4 partly ameliorates - hyperglycemia-mediated tissue damage in lungs of streptozotocin-induced diabetic mice

Glucagon-like peptide-1 (GLP-1) stimulates insulin secretion, - plays anti-inflammatory role in atherosclerosis, and has surfactant-releasing effects in lungs. GLP-1 analogues are used in diabetes therapy. This is the first study to investigate the effects of exendin-4, a GLP-1 receptor agonist, on lung injury in diabetic mice. BALB/c male mice were divided into four groups. The first group was given only citrate buffer, the second group was given only exendin-4, the third group was given only streptozotocin (STZ), and the fourth group was given both exendin-4 and STZ. Exendin-4 (3μg/kg) was administered daily by subcutaneous injection for 30days after mice were rendered diabetic with a single dose of STZ (200mg/kg). Structural alterations, oxidative stress, apoptosis, insulin signaling and expressions of prosurfactant-C, alpha-smooth muscle actin, collagen-I and fibronectin were evaluated in lung tissue. Diabetic mice lungs were characterized by induced oxidative stress, apoptosis, edema, and cell proliferation. They had honeycomb-like alveoli, thicker alveolar walls, and hypertrophic pneumocytes. Although exendin-4 treatment improved pulmonary edema, apoptosis, oxidative stress, and lung injury, it led to the disrupted insulin signaling and interstitial collagen accumulation in the lungs of diabetic mice. Exendin-4 ameliorates hyperglycemia-mediated lung damage by reducing glucose, -oxidative stress and stimulating cell proliferation. However, exendin-4 led to increased lung injury partly by reducing insulin signaling - and collagen accumulation around pulmonary vasculature in diabetic mice.

Engineering in vitro models of hepatofibrogenesis

Chronic liver disease is a major cause of morbidity and mortality worldwide marked by chronic inflammation and fibrosis/scarring, resulting in end-stage liver disease and its complications. Hepatic stellate cells (HSCs) are a dominant contributor to liver fibrosis by producing excessive extracellular matrix (ECM), irrespective of the underlying disease aetiologies, and for many decades research has focused on the development of a number of anti-fibrotic strategies targeting this cell. Despite major improvements in two-dimensional systems (2D) by using a variety of cell culture models of different complexity, an efficient anti-fibrogenic therapy has yet to be developed. The development of well-defined three-dimensional (3D) in vitro models, which mimic ECM structures as found in vivo, have demonstrated the importance of cell-matrix bio-mechanics, the complex interactions between HSCs and hepatocytes and other non-parenchymal cells, and this to improve and promote liver cell-specific functions. Henceforth, refinement of these 3D in vitro models, which reproduce the liver microenvironment, will lead to new objectives and to a possible new era in the search for antifibrogenic compounds.

A Subpopulation of Stromal Cells Controls Cancer Cell Homing to the Bone Marrow

Breast and prostate cancer cells home to the bone marrow, where they presumably hijack the hematopoietic stem cell niche. We characterize here the elusive premetastatic niche by examining the role of mesenchymal stromal cells (MSC) in cancer cell homing. Decreasing the number of MSC pharmacologically enhanced cancer cell homing to the bone marrow in mice. In contrast, increasing the number of these MSCs by various interventions including G-CSF administration diminished cancer cell homing. The MSC subpopulation that correlated best with cancer cells expressed stem, endothelial, and pericytic cell markers, suggesting these cells represent an undifferentiated component of the niche with vascular commitment. In humans, a MSC subpopulation carrying markers for endothelial and pericytic cells was lower in the presence of cytokeratin⁺ cells in bone marrow. Taken together, our data show that a subpopulation of MSC with both endothelial and pericytic cell surface markers suppresses the homing of cancer cells to the bone marrow. Similar to the presence of cytokeratin⁺ cells in the bone marrow, this MSC subpopulation could prove useful in determining the risk of metastatic disease, and its manipulation might offer a new possibility for diminishing bone metastasis formation.Significance: These findings establish an inverse relationship between a subpopulation of mesenchymal stromal cells and cancer cells in the bone marrow. Cancer Res; 78(1); 129-42. ©2017 AACR.

Fibronectins containing extradomain A or B enhance osteoblast differentiation via distinct integrins

Fibronectin is a multidomain protein secreted by various cell types. It forms a network of fibers within the extracellular matrix and impacts intracellular processes by binding to various molecules, primarily integrin receptors on the cells. Both the presence of several isoforms and the ability of the various domains and isoforms to bind to a variety of integrins result in a wide range of effects. In vivo findings suggest that fibronectin isoforms produced by the osteoblasts enhance their differentiation. Here we report that the isoform characterized by the presence of extradomain A activates α4β1 integrin and augments osteoblast differentiation. In addition, the isoform containing extradomain B enhances the binding of fibronectin through the RGD sequence to β3-containing integrin, resulting in increased mineralization by and differentiation of osteoblasts. Our study thus reveals novel functions for two fibronectin isoforms and the mediating receptors in osteoblast differentiation.

Circulating fibronectin contributes to mesangial expansion in a murine model of type 1 diabetes

Fibronectin is ubiquitously expressed in the extracellular matrix, and its accumulation in the glomerular mesangium in diabetic nephropathy is associated with deterioration of renal function in these patients. However, the exact role of fibronectin in the pathogenesis of diabetic nephropathy remains unknown. To clarify this, we administered fluorescent-labeled plasma fibronectin to wild-type mice and found it to accumulate in the mesangium. Using liver-specific conditional-knockout mice to decrease circulating fibronectin, we reduced circulating fibronectin by more than 90%. In streptozotocin-induced diabetes of these knockout mice, the pronounced fall in circulating fibronectin resulted in a decrease in mesangial expansion by 25% and a decline in albuminuria by 30% compared to diabetic control mice. Indeed, the amount of fibronectin in the kidney was reduced, as was the total amount of collagen. In vitro experiments confirmed that matrix accumulation of fibronectin was enhanced by increasing fibronectin only, glucose only, or the combination of both. Thus, circulating fibronectin contributes to mesangial expansion and exacerbation of albuminuria in a murine model of type 1 diabetes.

An O-Glycosylation of Fibronectin Mediates Hepatic Osteodystrophy Through α4β1 Integrin

Patients with cholestatic liver disease experience increased fracture risk. Higher circulating levels of a fibronectin isoform called oncofetal fibronectin (oFN) were detected in a subset of such patients. Administering this isoform to mice suppresses osteoblast differentiation and diminishes bone mineral density in vivo, suggesting it is responsible for bone loss in cholestatic liver disease. The aim of this study was to define the mechanism by which oFN affects osteoblast function and evaluate possible modifiers in experimental hepatic osteodystrophy. The fibronectin isoform oFN is characterized by the presence of various glycosylations. In line with this, adding oFN that underwent enzymatic O-deglycosylation to osteoblasts normalized nodule formation in vitro. Of three possible O-glycosylation sites in oFN, only a mutation at AA 33 of the variable region or binding of this glycosylated site with an antibody normalized osteoblast differentiation. Because the responsible site is located in the variable region of fibronectin, which binds to α4β1 or α4β7 integrins, these integrins were evaluated. We show that integrin α4β1 mediates the inhibitory effect of oFN both in vitro as well as in vivo. In a hepatic osteodystrophy mouse model, we demonstrate that liver fibrosis is associated with increased circulating oFN and diminished BMD. In addition, trabecular bone loss induced by oFN injection or fibrosis induction could be prevented by either administering an antibody that binds to α4 integrin (PS/2) or the CS1 peptide, which contains a binding site for α4β1 integrin. In summary, oFN inhibits osteoblast activity. This is because of an O-glycosylation in the variable region that results in decreased integrin-mediated signaling. This deleterious effect can be thwarted by binding α4β1 integrin. Thus, we have characterized the defect and the receptor mediating bone loss in patients with hepatic osteodystrophy and evaluated possible therapeutic interventions in a murine model. © 2016 American Society for Bone and Mineral Research.

Lack of Fibronectin Extra Domain A Alternative Splicing Exacerbates Endothelial Dysfunction in Diabetes

Glucose-induced changes of artery anatomy and function account for diabetic vascular complications, which heavily impact disease morbidity and mortality. Since fibronectin containing extra domain A (EDA + FN) is increased in diabetic vessels and participates to vascular remodeling, we wanted to elucidate whether and how EDA + FN is implicated in diabetes-induced endothelial dysfunction using isometric-tension recording in a murine model of diabetes. In thoracic aortas of EDA^−/−, EDA^+/+ (constitutively lacking and expressing EDA + FN respectively), and of wild-type mice (EDA^wt/wt), streptozotocin (STZ)-induced diabetes impaired endothelial vasodilation to acetylcholine, irrespective of genotype. However STZ + EDA^−/− mice exhibited increased endothelial dysfunction compared with STZ + EDA^+/+ and with STZ + EDA^wt/wt. Analysis of the underlying mechanisms revealed that STZ + EDA^−/− mice show increased oxidative stress as demonstrated by enhanced aortic superoxide anion, nitrotyrosine levels and expression of NADPH oxidase NOX4 and TGF-β1, the last two being reverted by treatment with the antioxidant n-acetylcysteine. In contrast, NOX1 expression and antioxidant potential were similar in aortas from the three genotypes. Interestingly, reduced eNOS expression in STZ + EDA^+/+ vessels is counteracted by increased eNOS coupling and function. Although EDA + FN participates to vascular remodelling, these findings show that it plays a crucial role in limiting diabetic endothelial dysfunction by preventing vascular oxidative stress.

Oxidative Stress and Liver Cancer: Etiology and Therapeutic Targets

Accumulating evidence has indicated that oxidative stress (OS) is associated with the development of hepatocellular carcinoma (HCC). However, the mechanisms remain largely unknown. Normally, OS occurs when the body receives any danger signal-from either an internal or external source-and further induces DNA oxidative damage and abnormal protein expression, placing the body into a state of vulnerability to the development of various diseases such as cancer. There are many factors involved in liver carcinogenesis, including hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, alcohol abuse, and nonalcoholic fatty liver disease (NAFLD). The relationship between OS and HCC has recently been attracting increasing attention. Therefore, elucidation of the impact of OS on the development of liver carcinogenesis is very important for the prevention and treatment of liver cancer. This review focuses mainly on the relationship between OS and the development of HCC from the perspective of cellular and molecular mechanisms and the etiology and therapeutic targets of HCC.

Fibronectin expression is critical for liver fibrogenesis in vivo and in vitro

Increased fibronectin (FN) expression has an important role during liver fibrosis. The present study examined FN expression in rats subjected to carbon tetrachloride (CCl4)‑induced liver fibrosis. In addition, the potential mechanisms underlying fibrogenesis were investigated by exposing hepatic stellate cells (HSCs) to transforming growth factor‑β (TGF‑β), which is a known inducer of myofibroblastic transformation of HSCs. Briefly, a rat model of liver fibrosis was created by administering intraperitoneal injections of CCl4. Furthermore, HSC‑T6 cells were stimulated with increasing doses of recombinant TGF‑β over 24 h. Hepatic fibrosis gradually increased following CCl4 administration in vivo. Western blotting and immunohistochemistry demonstrated that fibronectin (FN), TGF‑β and α‑smooth muscle actin (SMA) expression was increased following CCl4 injection, and the maximum expression levels were observed at 8 weeks. Once CCl4 treatment had been terminated, the expression levels of FN, TGF‑β and α‑SMA progressively declined to near baseline levels. Western blotting and quantitative polymerase chain reaction demonstrated that FN expression was gradually increased in response to TGF‑β‑stimulation of HSCs; maximum expression was achieved 12 h post‑treatment (P<0.01 vs. the baseline). In conclusion, these findings indicated that FN expression is an early and progressive event that occurs during liver fibrogenesis in vivo and in vitro.

EDA-Fibronectin Originating from Osteoblasts Inhibits the Immune Response against Cancer

Osteoblasts lining the inner surface of bone support hematopoietic stem cell differentiation by virtue of proximity to the bone marrow. The osteoblasts also modify their own differentiation by producing various isoforms of fibronectin (FN). Despite evidence for immune regulation by osteoblasts, there is limited knowledge of how osteoblasts modulate cells of the immune system. Here, we show that extra domain A (EDA)-FN produced by osteoblasts increases arginase production in myeloid-derived cells, and we identify α5β1 as the mediating receptor. In different mouse models of cancer, osteoblasts or EDA-FN was found to up-regulate arginase-1 expression in myeloid-derived cells, resulting in increased cancer growth. This harmful effect can be reduced by interfering with the integrin α5β1 receptor or inhibiting arginase. Conversely, in tissue injury, the expression of arginase-1 is normally beneficial as it dampens the immune response to allow wound healing. We show that EDA-FN protects against excessive fibrotic tissue formation in a liver fibrosis model. Our results establish an immune regulatory function for EDA-FN originating from the osteoblasts and identify new avenues for enhancing the immune reaction against cancer.

Osteoblasts produce an isoform of fibronectin (EDA-fibronectin) that acts on myeloid cells to increase arginase-1 expression and protect against fibrosis. However, it can also enhance cancer growth; interfering with the interaction between EDA-fibronectin and its receptor diminishes this effect.

Osteoblasts, which are the cells that produce bone, line the inner surface of the bone and are adjacent to the marrow that generates all the different blood cells. Osteoblasts have a close relationship with hematopoiesis, and it has been shown that a transient elimination of osteoblasts leads to the decrease of hematopoietic stem cells and progenitor cells. Fibronectin (FN) is an extracellular matrix protein with a known role in hematopoiesis in vitro that is secreted by osteoblasts. Here, we analyze the role of FN in hematopoiesis and find that an isoform that contains the extra domain A (EDA) and is produced by the osteoblasts affects both the number and future behavior of a subset of immune cells. EDA-FN protects against excessive fibrotic tissue formation in a liver fibrosis model. The same process, however, is detrimental in cancer, because it prevents the organism from mounting a potent immune response against the cancer and induces an increase of cancer growth. Mechanistically, we find that the EDA domain binds to the cell surface receptor α5β1 integrin and enhances the production of the anti-inflammatory and immunosuppressive factor arginase-1. We conclude that EDA-FN production by osteoblasts modulates immune cell behavior, and that interfering with this mechanism opens up new possibilities for enhancing an immune reaction against cancer.

Identification and characterization of a unique role for EDB fibronectin in phagocytosis

Abstract

Plasma fibronectin is a circulating protein that facilitates phagocytosis by connecting bacteria to immune cells. A fibronectin isoform, which includes a sequence of 90 AA called extra-domain B (EDB), is synthesized de novo at the messenger RNA (mRNA) level in immune cells, but the reason for its expression remains elusive. We detected an 80-fold increase in EDB-containing fibronectin in the cerebrospinal fluid of patients with bacterial meningitis that was most pronounced in staphylococcal infections. A role for this isoform in phagocytosis was further suggested by enhanced EDB fibronectin release after internalization of Staphylococcus aureus in vitro. Using transgenic mouse models, we established that immune cell production of fibronectin contributes to phagocytosis, more so than circulating plasma fibronectin, and that accentuated release of EDB-containing fibronectin by immune cells improved phagocytosis. In line with this, administration of EDB fibronectin enhanced in vitro phagocytosis to a larger extent than plasma fibronectin. This enhancement was mediated by αvβ3 integrin as shown using inhibitors or cells from β3 integrin knockout mice. Thus, we identified both a novel function for EDB fibronectin in augmenting phagocytosis over circulating plasma fibronectin, as well as the mediating receptor. Our data also establish for the first time, a direct role for β3 integrin in bacterial phagocytosis in mammals.

Key messages

• Fibronectin containing an extra domain called EDB is released in bacterial meningitis.

• EDB-containing fibronectin enhances phagocytosis more than plasma fibronectin.

• The enhancement is mediated by activation of αvβ3 integrin in the presence of EDB.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-015-1373-0) contains supplementary material, which is available to authorized users.

Molecular Mechanism Responsible for Fibronectin-controlled Alterations in Matrix Stiffness in Advanced Chronic Liver Fibrogenesis

Fibrosis is characterized by extracellular matrix (ECM) remodeling and stiffening. However, the functional contribution of tissue stiffening to noncancer pathogenesis remains largely unknown. Fibronectin (Fn) is an ECM glycoprotein substantially expressed during tissue repair. Here we show in advanced chronic liver fibrogenesis using a mouse model lacking Fn that, unexpectedly, Fn-null livers lead to more extensive liver cirrhosis, which is accompanied by increased liver matrix stiffness and deteriorated hepatic functions. Furthermore, Fn-null livers exhibit more myofibroblast phenotypes and accumulate highly disorganized/diffuse collagenous ECM networks composed of thinner and significantly increased number of collagen fibrils during advanced chronic liver damage. Mechanistically, mutant livers show elevated local TGF-β activity and lysyl oxidase expressions. A significant amount of active lysyl oxidase is released in Fn-null hepatic stellate cells in response to TGF-β1 through canonical and noncanonical Smad such as PI3 kinase-mediated pathways. TGF-β1-induced collagen fibril stiffness in Fn-null hepatic stellate cells is significantly higher compared with wild-type cells. Inhibition of lysyl oxidase significantly reduces collagen fibril stiffness, and treatment of Fn recovers collagen fibril stiffness to wild-type levels. Thus, our findings indicate an indispensable role for Fn in chronic liver fibrosis/cirrhosis in negatively regulating TGF-β bioavailability, which in turn modulates ECM remodeling and stiffening and consequently preserves adult organ functions. Furthermore, this regulatory mechanism by Fn could be translated for a potential therapeutic target in a broader variety of chronic fibrotic diseases.

Co-delivery of small molecule hedgehog inhibitor and miRNA for treating liver fibrosis

In liver fibrosis, secretion of growth factors and hedgehog (Hh) ligands by hepatic parenchyma upon repeated insults results in transdifferentiation of quiescent hepatic stellate cells (HSCs) into active myofibroblasts which secrete excessive amounts of extracellular matrix (ECM) proteins. An Hh inhibitor GDC-0449 and miR-29b1 can play an important role in treating liver fibrosis by inhibiting several pro-fibrotic genes. Our in-silico analysis indicate that miR-29b1 targets several profibrotic genes like collagen type I & IV, c-MYC, PDGF-β and PI3K/AKT which are upregulated in liver fibrosis. Common bile duct ligation (CBDL) resulted in an increase in Ptch-1, Shh and Gli-1 expression. miR-29b1 and GDC-0449 were co-formulated into micelles using methoxy poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate-graft-dodecanol-graft-tetraethylenepentamine) (mPEG-b-PCC-g-DC-g-TEPA) copolymer, and injected systemically into CBDL mice. High concentrations of GDC-0449 and miR-29b1 were delivered to liver cells as determined by in situ liver perfusion at 30 min post systemic administration of their micelle formulation. There was a significant decrease in collagen deposition in the liver and serum injury markers, leading to improvement in liver morphology. Combination therapy was more effective in providing hepatoprotection, lowering liver injury related serum enzyme levels, reducing fibrotic protein markers such as collagen, α-SMA, FN-1 and p-AKT compared to monotherapy. In conclusion, inhibition of Hh pathway and restoration of miR-29b1 have the potential to act synergistically in treating CBDL-induced liver fibrosis in mice.

Opposite Expression of SPARC between the Liver and Pancreas in Streptozotocin-Induced Diabetic Rats

Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates several cellular events, including inflammation and tissue remodelling. In this study, we investigated the tissue-specific expression of SPARC in streptozotocin (STZ)-induced diabetes, and found that SPARC was significantly up-regulated in the liver while down-regulated in the pancreas of STZ-induced diabetic rats. Chronic inflammation occurred in the diabetic pancreas accompanied by up-regulation of CCAAT/enhancer-binding protein beta (C/EBPβ) and its targets (TNFα, Il6, CRP, and Fn1) as well as myeloperoxidase (Mpo) and C-X-C chemokine receptor type 2 (Cxcr2). Diabetic liver showed significant up-regulation of Tgfb1 as well as moderately less up-regulated TNFα and reduced Fn1, resulting in elevated fibrogenesis. PARP-1 was not up-regulated during CD95-mediated apoptosis, resulting in restoration of high ATP levels in the diabetic liver. On the contrary, CD95-dependent apoptosis was not observed in the diabetic pancreas due to up-regulation of PARP-1 and ATP depletion, resulting in necrosis. The cytoprotective machinery was damaged by pancreatic inflammation, whereas adequate antioxidant capacity indicates low oxidative stress in the diabetic liver. High and low cellular insulin content was found in the diabetic liver and pancreas, respectively. Furthermore, we identified six novel interacting partner proteins of SPARC by co-immunoprecipitation in the diabetic liver and pancreas, and their interactions with SPARC were predicted by bioinformatics tools. Taken together, opposite expression of SPARC in the diabetic liver and pancreas may be related to inflammation and immune cell infiltration, degrees of apoptosis and fibrosis, cytoprotective machinery, and cellular insulin levels.

Pancreatic cancer exosomes initiate pre-metastatic niche formation in the liver

Pancreatic ductal adenocarcinomas (PDACs) are highly metastatic with poor prognosis, mainly due to delayed detection. We hypothesized that intercellular communication is critical for metastatic progression. Here, we show that PDAC-derived exosomes induce liver pre-metastatic niche formation in naive mice and consequently increase liver metastatic burden. Uptake of PDAC-derived exosomes by Kupffer cells caused transforming growth factor β secretion and upregulation of fibronectin production by hepatic stellate cells. This fibrotic microenvironment enhanced recruitment of bone marrow-derived macrophages. We found that macrophage migration inhibitory factor (MIF) was highly expressed in PDAC-derived exosomes, and its blockade prevented liver pre-metastatic niche formation and metastasis. Compared with patients whose pancreatic tumours did not progress, MIF was markedly higher in exosomes from stage I PDAC patients who later developed liver metastasis. These findings suggest that exosomal MIF primes the liver for metastasis and may be a prognostic marker for the development of PDAC liver metastasis.

Tumor angiogenesis in the absence of fibronectin or its cognate integrin receptors

Binding of α5β1 and αvβ3/β5 integrin receptors on the endothelium to their fibronectin substrate in the extracellular matrix has been targeted as a possible means of blocking tumor angiogenesis and tumor growth. However, clinical trials of blocking antibodies and peptides have been disappointing despite promising preclinical results, leading to questions about the mechanism of the inhibitors and the reasons for their failure. Here, using tissue-specific and inducible genetics to delete the α5 and αv receptors in the endothelium or their fibronectin substrate, either in the endothelium or globally, we show that both are dispensable for tumor growth, in transplanted tumors as well as spontaneous and angiogenesis-dependent RIP-Tag-driven pancreatic adenocarcinomas. In the nearly complete absence of fibronectin, no differences in vascular density or the deposition of basement membrane laminins, ColIV, Nid1, Nid2, or the TGFβ binding matrix proteins, fibrillin-1 and -2, could be observed. Our results reveal that fibronectin and the endothelial fibronectin receptor subunits, α5 and αv, are dispensable for tumor angiogenesis, suggesting that the inhibition of angiogenesis induced by antibodies or small molecules may occur through a dominant negative effect, rather than a simple functional block.

Inhibition of fibronectin deposition improves experimental liver fibrosis

BACKGROUND & AIMS

Common pathogenic steps in liver fibrosis are inflammation and accumulation of extracellular matrix proteins including collagen, which lead to disruption of tissue microarchitecture and liver dysfunction. Adequate fibronectin fibril formation is required for collagen matrix deposition in several cell types in vitro. We therefore hypothesized that preventing fibronectin fibril assembly will result in decreased collagen matrix accumulation, and hence diminish liver injury associated with fibrosis.

METHODS

In vitro studies on hepatic stellate cells and in vivo studies in mice were performed.

RESULTS

In vitro studies on hepatic stellate cells confirmed that a fibronectin assembly inhibitor, pUR4 diminishes the amount of both fibronectin and collagen, accumulating in the extracellular matrix, without affecting their production. Induction of fibrosis using CCl4 or DMN was therefore combined with pUR4-treatment. pUR4 normalized the amount of fibrotic tissue that accumulated with injury, and improved liver function. Specifically, pUR4-treatment decreased collagen accumulation, without changing its mRNA expression. Most interestingly, we did not detect any changes in Kupffer cell numbers (F4/80+) or α-smooth muscle actin expressing hepatic stellate cell numbers. Further, there was no impact on TGF-β or TNF-α. Thus, in line with the in vitro findings, decreased fibrosis is due to inhibition of matrix accumulation and not a direct effect on these cells.

CONCLUSIONS

In summary, a peptide that blocks fibronectin deposition results in decreased collagen accumulation and improved liver function during liver fibrogenesis. Thus, fibronectin matrix modulation offers a therapeutic benefit in preclinical models of liver fibrosis.