Alpha-smooth-muscle actin expression in normal and fibrotic human livers

Team players in the pathogenesis of metabolic dysfunctions-associated steatotic liver disease: The basis of development of pharmacotherapy

Nutrient metabolism is regulated by several factors. Social determinants of health with or without genetics are the primary regulator of metabolism, and an unhealthy lifestyle affects all modulators and mediators, leading to the adaptation and finally to the exhaustion of cellular functions. Hepatic steatosis is defined by presence of fat in more than 5% of hepatocytes. In hepatocytes, fat is stored as triglycerides in lipid droplet. Hepatic steatosis results from a combination of multiple intracellular processes. In a healthy individual nutrient metabolism is regulated at several steps. It ranges from the selection of nutrients in a grocery store to the last step of consumption of ATP as an energy or as a building block of a cell as structural component. Several hormones, peptides, and genes have been described that participate in nutrient metabolism. Several enzymes participate in each nutrient metabolism as described above from ingestion to generation of ATP. As of now several publications have revealed very intricate regulation of nutrient metabolism, where most of the regulatory factors are tied to each other bidirectionally, making it difficult to comprehend chronological sequence of events. Insulin hormone is the primary regulator of all nutrients' metabolism both in prandial and fasting states. Insulin exerts its effects directly and indirectly on enzymes involved in the three main cellular function processes; metabolic, inflammation and repair, and cell growth and regeneration. Final regulators that control the enzymatic functions through stimulation or suppression of a cell are nuclear receptors in especially farnesoid X receptor and peroxisome proliferator-activated receptor/RXR ligands, adiponectin, leptin, and adiponutrin. Insulin hormone has direct effect on these final modulators. Whereas blood glucose level, serum lipids, incretin hormones, bile acids in conjunction with microbiota are intermediary modulators which are controlled by lifestyle. The purpose of this review is to overview the key players in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD) that help us understand the disease natural course, risk stratification, role of lifestyle and pharmacotherapy in each individual patient with MASLD to achieve personalized care and target the practice of precision medicine. PubMed and Google Scholar databases were used to identify publication related to metabolism of carbohydrate and fat in states of health and disease states; MASLD, cardiovascular disease and cancer. More than 1000 publications including original research and review papers were reviewed.

Progress in Biomarkers Related to Biliary Atresia

Biliary atresia (BA) is a congenital cholestatic disease that can seriously damage children's liver function. It is one of the main reasons for liver transplantation in children. Early diagnosis of BA is crucial to the prognosis of patients, but there is still a lack of reliable non-invasive diagnostic methods. Additionally, as some children are in urgent need of liver transplantation, evaluating the stage of liver fibrosis and postoperative native liver survival in children with BA using a straightforward, efficient, and less traumatic method is a major focus of doctors. In recent years, an increasing number of BA-related biomarkers have been identified and have shown great potential in the following three aspects of clinical practice: diagnosis, evaluation of the stage of liver fibrosis, and prediction of native liver survival. This review focuses on the pathophysiological function and clinical application of three novel BA-related biomarkers, namely MMP-7, FGF-19, and M2BPGi. Furthermore, progress in well-known biomarkers of BA such as gamma-glutamyltransferase, circulating cytokines, and other potential biomarkers is discussed, aiming to provide a reference for clinical practice.

A functional chicken-liver hydrolysate-based supplement ameliorates alcohol liver disease via regulation of antioxidation, anti-inflammation, and antiapoptosis

Tons of broiler livers are produced yearly in Taiwan but always considered waste. Our team has successfully patented and characterized a chicken-liver hydrolysate (CLH) with several biofunctions. Chronic alcohol consumption causes hepatosteatosis or even hepatitis, cirrhosis, and cancers. This study was to investigate the hepatoprotection of CLH-based supplement (GBHP01™) against chronic alcohol consumption. Results showed that GBHP01™ could reduce (p < .05) enlarged liver size, lipid accumulation/steatosis scores, and higher serum AST, ALT, γ-GT, triglyceride, and cholesterol levels induced by an alcoholic liquid diet. GBHP01™ reduced liver inflammation and apoptosis in alcoholic liquid-diet-fed mice via decreasing TBARS, interleukin-6, interleukin-1β, and tumor necrosis factor-α levels, increasing reduced GSH/TEAC levels and activities of SOD, CAT and GPx, as well as downregulating CYP2E1, BAX/BCL2, Cleaved CASPASE-9/Total CASPASE-9 and Active CASPASE-3/Pro-CASPASE-3 (p < .05). Furthermore, GBHP01™ elevated hepatic alcohol metabolism (ADH and ALDH activities) (p < .05). In conclusion, this study prove the hepatoprotection of GBHP01™ against alcohol consumption.

Changes of biliary cilia, smooth muscle tissue distribution, innervation and extracellular matrices during morphological evolution of hepatic architectures in vertebrates

BACKGROUND

The liver architecture of vertebrates can be classified into two types, the portal triad type (having periportal bile ducts) and the non-portal triad type (having bile ducts independent of the course of portal veins). The former is typically detectable in livers of tetrapods and cartilaginous fish, and its ancestral state is found in the hagfish, an earliest diverged lineage among vertebrates. Teleosts other than osteoglossomorphs have the latter. The aim of the present study is to reveal the changes of the hepatic innervation, biliary cilia and smooth muscle distribution, and extracellular matrices along vertebrate evolution with attention to the two types of liver architectures.

METHODS

The hepatic innervation, biliary cilia and smooth muscle distribution, and collagen deposition were immunohistochemically and histochemically compared among livers of various vertebrates, using anti-acetylated tubulin and anti-α-smooth muscle actin antibodies, and Sirius red staining. These were also ultrastructurally examined.

RESULTS

Although the hagfish liver had periportal intrahepatic bile ducts and ductules as detected in mammalian livers, it lacked smooth muscles around bile ducts and portal veins. Extracellular matrices in their connective tissues had thick collagen fibers. Its innervation was restricted to intrahepatic bile ducts and portal veins in the hilum. In livers of other vertebrates, including teleosts, the innervation was broadly detectable, especially around bile ducts, hepatic arteries and portal veins (afferent vessels), but not around central veins (efferent vessels). The chondrichthyans ultrastructurally had smooth muscle tissue around bile ducts. Cilia distribution was confirmed in intrahepatic bile ducts of tetrapods and basal actinopterygians. Teleosts other than osteoglossomorphs lacked cilia in their intrahepatic bile ducts.

CONCLUSIONS

The liver architecture of the hagfish may be unique for innervation and extracellular matrices. Hepatic innervation may not have occurred in vertebrate ancestors. Hepatic innervation in bile ducts, hepatic arteries and portal veins may have been conserved among the extant jawed vertebrates. Cilia distribution in bile ducts may have changed during evolution of actinopterygians.

Deleterious liver-adipose crosstalk in obesity: Hydroethanolic extract of Lampaya medicinalis Phil. (Verbenaceae) counteracts fatty acid-induced fibrotic marker expression in human hepatocytes

Elevated circulating fatty acids in obesity may induce hepatic steatosis, leading to liver inflammation, fibrosis and nonalcoholic fatty liver disease (NAFLD). On the other hand, impaired communication between hepatocytes and adipose tissue (AT) in obesity influences adipose lipolysis and fibrosis, negatively affecting metabolic function. Infusions of Lampaya medicinalis Phil. (Verbenaceae) are used in Chilean folk medicine to treat inflammatory diseases. Hydroethanolic extract of lampaya (HEL) contains flavonoids that may explain its anti-inflammatory effect, but it is unknown whether HEL modulates fibrogenic processes in hepatocytes. We studied lipolysis and expression of fibrosis markers after exposure of visceral AT explants from subjects with obesity to HepG2-secreted factors. In addition, we evaluated the effect of HEL on palmitic acid (PA, C16:0) and oleic acid (OA; C18:1)-induced fibrotic marker expression in HepG2 hepatocytes. Results: Exposure to HepG2-secreted factors increased visceral AT lipolysis and expression of CTGF and collagen I. Exposure to OA/PA elevated collagen I, CTGF, fibronectin, α-smooth muscle actin, MMP-2 and MMP-9 expression in HepG2 cells, and these effects were prevented by HEL co-treatment. Conclusion: HEL effect counteracting OA/PA-induced fibrotic marker expression in HepG2 hepatocytes may represent a preventive approach against hepatic fibrosis and deleterious liver-adipose crosstalk in obesity.

Dendropanoxide, a Triterpenoid from Dendropanax morbifera, Ameliorates Hepatic Fibrosis by Inhibiting Activation of Hepatic Stellate Cells through Autophagy Inhibition

Hepatic fibrosis results from chronic liver damage and is characterized by excessive accumulation of extracellular matrix (ECM). In this study, we showed that dendropanoxide (DPX), isolated from Dendropanax morbifera, had anti-fibrotic effects on hepatic fibrosis by inhibiting hepatic stellate cell (HSC) activation. DPX suppressed mRNA and protein expression of α-SMA, fibronectin, and collagen in activated HSCs. Moreover, DPX (40 mg/kg) treatment significantly lowered levels of liver injury markers (aspartate aminotransferase and alanine transaminase), expression of fibrotic markers, and deposition of ECM in a carbon tetrachloride-induced mouse model. Anti-fibrotic effects of DPX were comparable to those of silymarin in a hepatic fibrosis mouse model. As a possible mechanism of anti-fibrotic effects, we showed that DPX inhibited autophagosome formation (LC3B-II) and degradation of p62, which have important roles in HSC activation. These findings suggest that DPX inhibits HSC activation by inhibiting autophagy and can be utilized in hepatic fibrosis therapy.

TG68, a Novel Thyroid Hormone Receptor-β Agonist for the Treatment of NAFLD

Activation of thyroid hormone receptor β (THRβ) has shown beneficial effects on metabolic alterations, including non-alcoholic fatty liver disease (NAFLD). Here, we investigated the effect of TG68, a novel THRβ agonist, on fatty liver accumulation and liver injury in mice fed a high-fat diet (HFD). C57BL/6 mice fed HFD for 17 or 18 weeks, a time when all mice developed massive steatohepatitis, were then given TG68 at a dose of 9.35 or 2.8 mg/kg for 2 or 3 weeks, respectively. As a reference compound, the same treatment was adopted using equimolar doses of MGL-3196, a selective THRβ agonist currently in clinical phase III. The results showed that treatment with TG68 led to a reduction in liver weight, hepatic steatosis, serum transaminases, and circulating triglycerides. qRT-PCR analyses demonstrated activation of THRβ, as confirmed by increased mRNA levels of Deiodinase-1 and Malic enzyme-1, and changes in lipid metabolism, as revealed by increased expression of Acyl-CoA Oxidase-1 and Carnitine palmitoyltransferase-1. The present results showed that this novel THRβ agonist exerts an anti-steatogenic effect coupled with amelioration of liver injury in the absence of extra-hepatic side effects, suggesting that TG68 may represent a useful tool for the treatment of NAFLD.

The inhibitory effect of PLGA-encapsulated berberine on hepatotoxicity and α-smooth muscle actin (α-SMA) gene expression

BACKGROUND

Liver injury results in excessive extracellular matrix (ECM) deposition in the liver, which is mainly produced by hepatic stellate cells (HSC). Alpha-smooth muscle actin (α-SMA) and liver enzymes are the two hallmarks of liver injury. Previously, it has been confirmed that berberine (BBR) attenuates liver injury. This study aimed to investigate the protective effect of Poly Lactic-co-Glycolic Acid (PLGA) encapsulated BBR against liver injury.

METHODS

Nanoprecipitation, encapsulation, and physio-chemical characterization of BBR-PLGA nanoparticles (BBR-PLGA-NP) have been done. The protective effects of BBR-PLGA-NPs and BBR against carbon tetrachloride (CCl4)-treated Wistar rats were investigated. The serum levels of alanine aminotransferase and aspartate transaminase were measured, and the expression level of α-SMA was quantified by qRT-PCR. To evaluate the liver changes, morphological and histological staining was done.

RESULTS

BBR-PLGA-NPs markedly reduced serum ALT and AST in rats treated with CCl4. Although the expression level of α-SMA was downregulated in the CCl4-injected rats that were treated with BBR, α-SMA expression in this group was still remarkably higher than the control group. α-SMA mRNA was significantly under-expressed (p < 0.05) by BBR-PLGA-NPs and the hepatic histology revealed BBR-PLGA-NPs made further improvements than free BBR.

CONCLUSION

The use of nanoparticle to encapsulate BBR is a worthy approach to enhance the curative effect of BBR against liver injuries, which donate a safe and effective drug delivery strategy to treat liver injuries.

Hepatic stellate cell as a Mac-2-binding protein-producing cell in patients with liver fibrosis

BACKGROUND

Mac-2 binding protein (M2BP) glycosylated isomer (M2BPGi) is a serum marker of liver fibrosis; M2BPGi is a glycosylated form of M2BP. Hepatocytes and hepatic stellate cells (HSCs) have been studied to determine the source of M2BP. This study proposes to identify the origin of M2BP in fibrotic liver.

METHODS

Using liver fibrosis tissue specimens from 15 patients with liver cancer, M2BP mRNA and M2BP were detected by in situ hybridization and immunohistochemistry, respectively. The expression levels of M2BP mRNA were evaluated with scores of 3, 2, and 1. Fluorescent in situ hybridization was carried out to evaluate the distribution of M2BP mRNA and the activated-HSC marker αSMA mRNA; multicolor fluorescent immunohistochemistry was used for protein localization of M2BP, αSMA, and CD68. The Kruskal-Wallis test analyzed the relationship between M2BP mRNA expression and existing serum fibrosis markers.

RESULTS

M2BP mRNA was expressed in spindle-shaped cells along the fibrous septa and in the perisinusoidal area of the fibrotic liver. The HSC markers αSMA mRNA and M2BP mRNA were colocalized in the spindle-shaped cells; on the protein level, M2BP was expressed in Kupffer cells. M2BP mRNA expression was positively correlated with serum M2BPGi levels. Aspartate transaminase-to-platelet ratio index, Fibrosis-4, hyaluronic acid, and the 15-minute indocyanine green retention rate were significantly correlated with M2BP mRNA expression.

CONCLUSIONS

M2BP mRNA transcription in fibrotic liver was primarily observed in HSCs but not at the M2BP level, which suggests that HSCs might produce and introduce M2BP to Kupffer cells and serum.

Adipocyte Fatty Acid Binding Protein Promotes the Onset and Progression of Liver Fibrosis via Mediating the Crosstalk between Liver Sinusoidal Endothelial Cells and Hepatic Stellate Cells

Development of liver fibrosis results in drastic changes in the liver microenvironment, which in turn accelerates disease progression. Although the pathological function of various hepatic cells in fibrogenesis is identified, the crosstalk between them remains obscure. The present study demonstrates that hepatic expression of adipocyte fatty acid binding protein (A-FABP) is induced especially in the liver sinusoidal endothelial cells (LSECs) in mice after bile duct ligation (BDL). Genetic ablation and pharmacological inhibition of A-FABP attenuate BDL- or carbon tetrachloride-induced liver fibrosis in mice associating with reduced collagen accumulation, LSEC capillarization, and hepatic stellate cell (HSC) activation. Mechanistically, elevated A-FABP promotes LSEC capillarization by activating Hedgehog signaling, thus impairs the gatekeeper function of LSEC on HSC activation. LSEC-derived A-FABP also acts on HSCs in paracrine manner to potentiate the transactivation of transforming growth factor β1 (TGFβ1) by activating c-Jun N-terminal kinase (JNK)/c-Jun signaling. Elevated TGFβ1 subsequently exaggerates liver fibrosis. These findings uncover a novel pathological mechanism of liver fibrosis in which LSEC-derived A-FABP is a key regulator modulating the onset and progression of the disease. Targeting A-FABP may represent a potential approach against liver fibrosis.

Hepatic stellate cells - from past till present: morphology, human markers, human cell lines, behavior in normal and liver pathology

Hepatic stellate cell (HSC), initially analyzed by von Kupffer, in 1876, revealed to be an extraordinary mesenchymal cell, essential for both hepatocellular function and lesions, being the hallmark of hepatic fibrogenesis and carcinogenesis. Apart from their implications in hepatic injury, HSCs play a vital role in liver development and regeneration, xenobiotic response, intermediate metabolism, and regulation of immune response. In this review, we discuss the current state of knowledge regarding HSCs morphology, human HSCs markers and human HSC cell lines. We also summarize the latest findings concerning their roles in normal and liver pathology, focusing on their impact in fibrogenesis, chronic viral hepatitis and liver tumors.

Self-Assembling Peptide Solution Accelerates Hemostasis

Objective: One of the leading causes of death following traumatic injury is exsanguination. Biological material-based hemostatic agents such as fibrin, thrombin, and albumin have a high risk for causing infection. Synthetic peptide-based hemostatic agents offer an attractive alternative. The objective of this study is to explore the potential of h9e peptide as an effective hemostatic agent in both in vitro and in vivo models. Approach: In vitro blood coagulation kinetics in the presence of h9e peptide was determined as a function of gelation time using a dynamic rheometer. In vivo hemostatic effects were studied using the Wistar rat model. Results were compared to those of the commercial hemostatic product Celox™, a chitosan-based product. Adhesion of h9e peptide was evaluated using the platelet adhesion test. Biocompatibility of h9e peptide was studied in vivo using a mouse model. Results: After h9e peptide solution was mixed with blood, gelation started immediately, increased rapidly with time, and reached more than 100 Pa within 3 s. Blood coagulation strength increased as h9e peptide wt% concentration increased. In the rat model, h9e peptide solution at 5% weight concentration significantly reduced both bleeding time and blood loss, outperforming Celox. Preliminary pathological studies indicate that h9e peptide solution is biocompatible and did not have negative effects when injected subcutaneously in a mouse model. Innovation: For the first time, h9e peptide was found to have highly efficient hemostatic effects by forming nanoweb-like structures, which act as a preliminary thrombus and a surface to arrest bleeding 82% faster compared to the commercial hemostatic agent Celox. Conclusion: This study demonstrates that h9e peptide is a promising hemostatic biomaterial, not only because of its greater hemostatic effect than commercial product Celox but also because of its excellent biocompatibility based on the in vivo mouse model study.

The impact of achieving a sustained virological response with direct-acting antivirals on serum autotaxin levels in chronic hepatitis C patients

Background

Autotaxin (ATX) is an emerging biomarker for liver fibrosis. Achievement of sustained virological response (SVR) by direct-acting antivirals (DAAs) results in hepatic fibrosis regression in chronic hepatitis C (CHC) patients. In this context, the clinical implications of ATX have not yet been well-defined. In this study, we aimed to assess the impact of achieving SVR with DAA therapy on serum ATX levels and whether these levels can reflect the regression of hepatic fibrosis in CHC patients. We evaluated serum ATX levels at baseline and 12 weeks post-DAA therapy in 48 CHC patients. We compared ATX with FIB4 score and AST-to-Platelet Ratio Index (APRI) as regards the detection of grade F3–4 fibrosis.

Results

Serum ATX levels were significantly declined in 47 patients after the achievement of SVR12 (p < 0.001). The diagnostic ability of ATX for the detection of grade F3–4 fibrosis was inferior to FIB4 and APRI scores at baseline and SVR12.

Conclusion

Achievement of SVR with DAA therapy causes a significant decline in serum autotaxin concentrations, suggesting early regression of hepatic fibrosis in CHC patients. However, its diagnostic capability for routine patient monitoring and follow-up is still under debate.

Immunohistological analysis on distribution of smooth muscle tissues in livers of various vertebrates with attention to different liver architectures

BACKGROUND

The liver architecture of vertebrates can be classified into two types, the portal triad type (having periportal bile ducts) and the non-portal triad type (having non-periportal bile ducts). The former is detectable from the hagfish, which is the most ancestral vertebrate, to tetrapod livers whereas many actinopterygian livers have the latter. The aim of the present study is to reveal the distribution of smooth muscle tissue in livers of various vertebrates with attention to their architectures.

METHODS

Smooth muscle was immunohistochemically compared in hepatic blood vessels and bile ducts of various vertebrates, using an anti-alpha-smooth muscle actin (ASMA) antibody.

RESULTS

Smooth muscle was noted in the gallbladder and hepatic artery in all vertebrates, including the hagfish. Bile ducts having ASMA-positive smooth muscles were absent in the hagfish, but detected in the Chondrichthyes and conserved in actinopterygians with or without portal triads during the evolution of vertebrates. In tetrapods having portal triads, reptiles had a tendency to have strongly ASMA-positive biliary smooth muscle tissues whereas other tetrapods had bile ducts with poor smooth muscle tissues. Although the hagfish livers never had ASMA-positive smooth muscle tissue in the walls of portal and central veins, it was observed in discontinuous distributions or not observed in portal veins and central veins of chondrichthyans and actinopterygians. By contrast, in most tetrapods, ASMA-positive smooth muscle tissue was detectable in portal veins, which supported the adjacent endothelial cells as a circular layer. Central veins did not consistently have smooth muscle tissue in these groups.

DISCUSSION AND CONCLUSION

The hagfish liver may retain more ancestral characteristics than other vertebrates in terms of smooth muscle distribution in the vascular and biliary systems. Actinopterygians might have a different mechanism of bile transport from tetrapods from their smooth muscle distribution in intrahepatic bile ducts. The circular smooth muscle distribution in portal veins might be a characteristic acquired by tetrapods.

Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

Sex Differences in Rat Intervertebral Disc Structure and Function Following Annular Puncture Injury

STUDY DESIGN

A rat puncture injury intervertebral disc (IVD) degeneration model with structural, biomechanical, and histological analyses.

OBJECTIVE

To determine if males and females have distinct responses in the IVD after injury.

SUMMARY OF BACKGROUND DATA

Low back pain (LBP) and spinal impairments are more common in women than men. However, sex differences in IVD response to injury have been underexplored, particularly in animal models where sex differences can be measured without gender confounds.

METHODS

Forty-eight male and female Sprague Dawley rats underwent sham, single annular puncture with tumor necrosis factor α (TNFα) injection (1×), or triple annular puncture with TNFα injection (3×) surgery. Six weeks after surgery, lumbar IVDs were assessed by radiologic IVD height, spinal motion segment biomechanical testing, histological degeneration grading, second harmonic generation (SHG) imaging, and immunofluorescence for fibronectin and α-smooth muscle actin.

RESULTS

Annular puncture injuries significantly increased degenerative grade and IVD height loss for males and females, but females had increased degeneration grade particularly in the annulus fibrosus (AF). Despite IVD height loss, biomechanical properties were largely unaffected by injury at 6 weeks. However, biomechanical measures sensitive to outer AF differed by sex after 3× injury-male IVDs had greater torsional stiffness, torque range, and viscoelastic creep responses. SHG intensity of outer AF was reduced after injury only in female IVDs, suggesting sex differences in collagen remodeling. Both males and females exhibited decreased cellularity and increased fibronectin expression at injury sites.

CONCLUSION

IVD injury results in distinct degeneration and functional healing responses between males and females. The subtle sex differences identified in this animal model suggest differences in response to IVD injury that might explain some of the variance observed in human LBP, and demonstrate the need to better understand differences in male and female IVD degeneration patterns and pain pathogenesis.

LEVEL OF EVIDENCE

N/A.

Matrix stiffness modulates the activity of MMP-9 and TIMP-1 in hepatic stellate cells to perpetuate fibrosis

Liver fibrosis is characterised by a dense and highly cross-linked extracellular matrix (ECM) which promotes progression of diseases such as hepatocellular carcinoma. The fibrotic microenvironment is characterised by an increased stiffness, with rigidity associated with disease progression. External stiffness is known to promote hepatic stellate cell (HSC) activation through mechanotransduction, leading to increased secretion of ECM components. HSCs are key effector cells which maintain the composition of the ECM in health and disease, not only by regulating secretion of ECM proteins such as collagen, but also ECM-degrading enzymes called matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Uninhibited MMPs degrade ECM proteins to reduce external rigidity. Using fibronectin-coated polyacrylamide gels to alter substrate rigidity without altering ligand density, we show that fibrotic rigidities downregulate MMP-9 expression and secretion, and also upregulate secretion of TIMP-1, though not its expression. Using tissue immunofluorescence studies, we also report that the expression of MMP-9 is significantly decreased in activated HSCs in fibrotic tissues associated with hepatocellular carcinoma. This suggests the presence of a mechanical network that allows HSCs to maintain a fibrotic ECM, with external rigidity providing feedback which affects MMP-9 and TIMP-1 secretion, which may become dysregulated in fibrosis.

Integrative omics analysis identifies macrophage migration inhibitory factor signaling pathways underlying human hepatic fibrogenesis and fibrosis

The genetic basis underlying liver fibrosis remains largely unknown. We conducted a study to identify genetic alleles and underlying pathways associated with hepatic fibrogenesis and fibrosis at the genome-wide level in 121 human livers. By accepting a liberal significance level of P<1e-4, we identified 73 and 71 candidate loci respectively affecting the variability in alpha-smooth muscle actin (α-SMA) levels (fibrogenesis) and total collagen content (fibrosis). The top genetic loci associated with the two markers were BAZA1 and NOL10 for α-SMA expression and FAM46A for total collagen content (P<1e-6). We further investigated the relationship between the candidate loci and the nearby gene transcription levels (cis-expression quantitative trait loci) in the same liver samples. We found that 44 candidate loci for α-SMA expression and 44 for total collagen content were also associated with the transcription of the nearby genes (P<0.05). Pathway analyses of these genes indicated that macrophage migration inhibitory factor (MIF) related pathway is significantly associated with fibrogenesis and fibrosis, though different genes were enriched for each marker. The association between the single nucleotide polymorphisms, MIF and α-SMA showed that decreased MIF expression is correlated with increased α-SMA expression, suggesting that variations in MIF locus might affect the susceptibility of fibrogenesis through controlling MIF gene expression. In summary, our study identified candidate alleles and pathways underlying both fibrogenesis and fibrosis in human livers. Our bioinformatics analyses suggested MIF pathway as a strong candidate involved in liver fibrosis, thus further investigation for the role of the MIF pathway in liver fibrosis is warranted. The study was reviewed and approved by the Institutional Review Board (IRB) of Wayne State University (approval No. 201842) on May 17, 2018.

Serum Mac-2 binding protein glycosylation isomer predicts the activation of hepatic stellate cells after liver transplantation

BACKGROUND AND AIM

Serum Mac-2 binding protein glycosylation isomer (M2BPGi) is a novel fibrosis marker for various chronic liver diseases. We investigated the ability of M2BPGi to predict liver fibrosis in liver transplant (LT) recipients.

METHODS

A total of 116 liver biopsies were performed in 113 LT recipients. The serum level of M2BPGi was also measured on the same day. The median age at LT and liver biopsy was 1.1 and 11.8 years, respectively. Serum M2BPGi levels and liver fibrosis status using METAVIR fibrosis score were compared. Immunohistological evaluation by anti-α-smooth-muscle actin (αSMA) was performed, and the relationship between αSMA positive rate and serum M2BPGi levels was investigated.

RESULTS

The median M2BPGi level was 0.78 (range, 0.22-9.50), and 65, 29, 16, 5, and 1 patient(s) had METAVIR fibrosis scores of F0, F1, F2, F3, and F4, respectively. In patients with F0 fibrosis, median M2BPGi level was 0.69 and was significantly lower than in patients with F1 (median 0.99, P < 0.01), F2 (median 1.00, P = 0.01), and F3 fibrosis (median 1.53, P < 0.01). Area-under-the-curve analysis of the ability of M2BPGi level to predict liver fibrosis grade were > F1: 0.716, > F2: 0.720, and > F3: 0.900. Three patients with acute cellular rejection showed high levels of M2BPGi, which decreased after the treatment. A positive correlation existed between M2BPGi levels and αSMA positive rate (r²  = 0.715, P < 0.01).

CONCLUSION

Mac-2 binding protein glycosylation isomer is a novel liver fibrosis marker in LT recipients and is also increased in patients with acute liver injuries, especially acute cellular rejection, even when fibrosis is absent.

Human hepatic stellate cell isolation and characterization

The hepatic stellate cells (HSCs) localize at the space of Disse in the liver and have multiple functions. They are identified as the major contributor to hepatic fibrosis. Significant understanding of HSCs has been achieved using rodent models and isolated murine HSCs; as well as investigating human liver tissues and human HSCs. There is growing interest and need of translating rodent study findings to human HSCs and human liver diseases. However, species-related differences impose challenges on the translational research. In this review, we focus on the current information on human HSCs isolation methods, human HSCs markers, and established human HSC cell lines.

ENOblock, a unique small molecule inhibitor of the non-glycolytic functions of enolase, alleviates the symptoms of type 2 diabetes

Type 2 diabetes mellitus (T2DM) significantly impacts on human health and patient numbers are predicted to rise. Discovering novel drugs and targets for treating T2DM is a research priority. In this study, we investigated targeting of the glycolysis enzyme, enolase, using the small molecule ENOblock, which binds enolase and modulates its non-glycolytic ‘moonlighting’ functions. In insulin-responsive cells ENOblock induced enolase nuclear translocation, where this enzyme acts as a transcriptional repressor. In a mammalian model of T2DM, ENOblock treatment reduced hyperglycemia and hyperlipidemia. Liver and kidney tissue of ENOblock-treated mice showed down-regulation of known enolase target genes and reduced enolase enzyme activity. Indicators of secondary diabetic complications, such as tissue apoptosis, inflammatory markers and fibrosis were inhibited by ENOblock treatment. Compared to the well-characterized anti-diabetes drug, rosiglitazone, ENOblock produced greater beneficial effects on lipid homeostasis, fibrosis, inflammatory markers, nephrotoxicity and cardiac hypertrophy. ENOblock treatment was associated with the down-regulation of phosphoenolpyruvate carboxykinase and sterol regulatory element-binding protein-1, which are known to produce anti-diabetic effects. In summary, these findings indicate that ENOblock has potential for therapeutic development to treat T2DM. Previously considered as a ‘boring’ housekeeping gene, these results also implicate enolase as a novel drug target for T2DM.

Relevance of activated hepatic stellate cells in predicting the development of pediatric liver allograft fibrosis

Activated hepatic stellate cells (HSCs) are the main collagen-producing cells in liver fibrogenesis. With the purpose of analyzing their presence and relevance in predicting liver allograft fibrosis development, 162 liver biopsies of 54 pediatric liver transplantation (LT) recipients were assessed at 6 months, 3 years, and 7 years after LT. The proportion of activated HSCs, identified by α-smooth muscle actin (ASMA) immunostaining, and the amount of fibrosis, identified by picrosirius red (PSR%) staining, were determined by computer-based morphometric analysis. Fibrosis was also staged by using the semiquantitative liver allograft fibrosis score (LAFSc), specifically designed to score fibrosis in the pediatric LT population. Liver allograft fibrosis displayed progression over time by PSR% (P < 0.001) and by LAFSc (P < 0.001). The ASMA expression decreased in the long term, with inverse evolution with respect to fibrosis (P < 0.01). Patients with ASMA-positive HSCs area ≥ 8% at 6 months (n = 20) developed a higher fibrosis proportion compared to those with ASMA-positive HSCs area ≤ 8% (n = 34) at the same period of time and in the long term (P = 0.03 and P < 0.01, respectively), but not at 3 years (P = 0.8). ASMA expression ≥ 8% at 6 months was found to be an independent risk factor for 7-year fibrosis development by PSR% (r(2) = 0.5; P < 0.01) and by LAFSc (r(2) = 0.3; P = 0.03). Furthermore, ASMA expression ≥ 8% at 3 years showed an association with the development of fibrosis at 7 years (P = 0.02). In conclusion, there is a high proportion of activated HSCs in pediatric LT recipients. ASMA ≥ 8% at 6 months seems to be a risk factor for early and longterm fibrosis development. In addition, activated HSCs showed inverse evolution with respect to fibrosis in the long term. Liver Transplantation 22 822-829 2016 AASLD.

Serum autotaxin levels correlate with hepatic dysfunction and severity in postoperative biliary atresia

OBJECTIVE

To investigate correlation of serum autotaxin and disease severity in biliary atresia (BA).

METHODS

Eighty postoperative BA patients and 15 controls were recruited. Serum autotaxin levels were determined by enzyme-linked immunosorbent assay.

RESULTS

BA patients had greater serum autotaxin and liver stiffness than controls. Serum autotaxin and liver stiffness were markedly elevated in BA patients with jaundice compared to those without jaundice. Furthermore, serum autotaxin was correlated with liver stiffness and biochemical parameters in BA.

CONCLUSIONS

Elevated serum autotaxin was correlated with hepatic dysfunction in BA. Accordingly, serum autotaxin is a promising biomarker reflecting the severity in BA.

Myofibroblastic reaction is a common event in metastatic disease of breast carcinoma: a descriptive study

BACKGROUND

The modification of stromal components with the disappearance of CD34 positive fibrocytes and by contrast the acquisition of smooth-muscle actin positive myofibroblasts is a frequent event in breast carcinomas but has been little studied in its metastatic sites. Therefore, the aim of the present study is to examine the stromal expression of CD34 and SMA in lymph node and liver metastases which are two of the most frequent metastatic breast cancer sites.

METHODS

The distribution of CD34 fibrocytes and SMA myofibroblasts has been studied by immunohistochemistry in 41 lymph node and 36 liver metastases from patients with invasive carcinoma of no special type.

RESULTS

No CD 34 fibrocytes were noted in the stroma of metastasis. By contrast, smooth-muscle actin stromal expression was observed in 95.1% of lymph node and 97.2% of liver metastases, independently of histological features of tumours.

CONCLUSIONS

Myofibroblasts represent a major and constant component in the metastatic tumoral stroma of breast carcinoma highlighting that these cells could play an active role in tumour cells proliferation and spread.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_196.

Serum autotaxin is a parameter for the severity of liver cirrhosis and overall survival in patients with liver cirrhosis--a prospective cohort study

Background

Autotaxin (ATX) and its product lysophosphatidic acid (LPA) are considered to be involved in the development of liver fibrosis and elevated levels of serum ATX have been found in patients with hepatitis C virus associated liver fibrosis. However, the clinical role of systemic ATX in the stages of liver cirrhosis was unknown. Here we investigated the relation of ATX serum levels and severity of cirrhosis as well as prognosis of cirrhotic patients.

Methods

Patients with liver cirrhosis were prospectively enrolled and followed until death, liver transplantation or last contact. Blood samples drawn at the day of inclusion in the study were assessed for ATX content by an enzyme-linked immunosorbent assay. ATX levels were correlated with the stage as well as complications of cirrhosis. The prognostic value of ATX was investigated by uni- and multivariate Cox regression analyses. LPA concentration was determined by liquid chromatography-tandem mass spectrometry.

Results

270 patients were enrolled. Subjects with liver cirrhosis showed elevated serum levels of ATX as compared to healthy subjects (0.814±0.42 mg/l vs. 0.258±0.40 mg/l, P<0.001). Serum ATX levels correlated with the Child-Pugh stage and the MELD (model of end stage liver disease) score and LPA levels (r = 0.493, P = 0.027). Patients with hepatic encephalopathy (P = 0.006), esophageal varices (P = 0.002) and portal hypertensive gastropathy (P = 0.008) had higher ATX levels than patients without these complications. Low ATX levels were a parameter independently associated with longer overall survival (hazard ratio 0.575, 95% confidence interval 0.365–0.905, P = 0.017).

Conclusion

Serum ATX is an indicator for the severity of liver disease and the prognosis of cirrhotic patients.

An amphipathic alpha-helical peptide from apolipoprotein A1 stabilizes protein polymer vesicles

L4F, an alpha helical peptide inspired by the lipid-binding domain of the ApoA1 protein, has potential applications in the reduction of inflammation involved with cardiovascular disease as well as an antioxidant effect that inhibits liver fibrosis. In addition to its biological activity, amphipathic peptides such as L4F are likely candidates to direct the molecular assembly of peptide nanostructures. Here we describe the stabilization of the amphipathic L4F peptide through fusion to a high molecular weight protein polymer. Comprised of multiple pentameric repeats, elastin-like polypeptides (ELPs) are biodegradable protein polymers inspired from the human gene for tropoelastin. Dynamic light scattering confirmed that the fusion peptide forms nanoparticles with a hydrodynamic radius of approximately 50nm, which is unexpectedly above that observed for the free ELP (~5.1nm). To further investigate their morphology, conventional and cryogenic transmission electron microscopy were used to reveal that they are unilamellar vesicles. On average, these vesicles are 49nm in radius with lamellae 8nm in thickness. To evaluate their therapeutic potential, the L4F nanoparticles were incubated with hepatic stellate cells. Stellate cell activation leads to hepatic fibrosis; furthermore, their activation is suppressed by anti-oxidant activity of ApoA1 mimetic peptides. Consistent with this observation, L4F nanoparticles were found to suppress hepatic stellate cell activation in vitro. To evaluate the in vivo potential for these nanostructures, their plasma pharmacokinetics were evaluated in rats. Despite the assembly of nanostructures, both free L4F and L4F nanoparticles exhibited similar half-lives of approximately 1h in plasma. This is the first study reporting the stabilization of peptide-based vesicles using ApoA1 mimetic peptides fused to a protein polymer; furthermore, this platform for peptide-vesicle assembly may have utility in the design of biodegradable nanostructures.

Activation of platelet-derived growth factor receptor alpha contributes to liver fibrosis

Chronic liver injury leads to fibrosis, cirrhosis, and loss of liver function. Liver cirrhosis is the 12th leading cause of death in the United States, and it is the primary risk factor for developing liver cancer. Fibrosis and cirrhosis result from activation of hepatic stellate cells (HSCs), which are the primary collagen producing cell type in the liver. Here, we show that platelet-derived growth factor receptor α (PDGFRα) is expressed by human HSCs, and PDGFRα expression is elevated in human liver disease. Using a green fluorescent protein (GFP) reporter mouse strain, we evaluated the role of PDGFRα in liver disease in mice and found that mouse HSCs express PDGFRα and expression is upregulated during carbon tetrachloride (CCl₄) induced liver injury and fibrosis injection. This fibrotic response is reduced in Pdgfrα heterozygous mice, consistent with the hypothesis that liver fibrosis requires upregulation and activation of PDGFRα. These results indicate that Pdgfrα expression is important in the fibrotic response to liver injury in humans and mice, and suggest that blocking PDGFRα–specific signaling pathways in HSCs may provide therapeutic benefit for patients with chronic liver disease.

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

Fibrotic tissue in the liver is mainly composed of collagen. Fibronectin, which is also present in fibrotic matrices, is required for collagen matrix assembly in vitro. It also modulates the amount of growth factors and their release from the matrix. We therefore examined the effects of the absence of fibronectin on the development of fibrosis in mice.

Conditional deletion of fibronectin in the liver using the Mx promoter to drive cre expression resulted in increased collagen production and hence a more pronounced fibrosis in response to dimethylnitrosamine in mice. Exclusive deletion of fibronectin in hepatocytes or normalization of circulating fibronectin in Mx-cKO mice did not affect the development of fibrosis suggesting a role for fibronectin production by other liver cell types. The boosted fibrosis in fibronectin-deficient mice was associated with enhanced stellate cell activation and proliferation, elevated concentrations of active TGF-β, and increased TGF-β-mediated signaling.

In vitro experiments revealed that collagen-type-I production by fibronectin-deficient hepatic stellate cells stimulated with TGF-β was more pronounced, and was associated with augmented Smad3-mediated signaling. Interfering with TGF-β signaling using SB431542 normalized collagen-type-I production in fibronectin-deficient hepatic stellate cells. Furthermore, precoating culture plates with fibronectin, but not collagen, or providing fibronectin fibrils unable to interact with RGD binding integrins via the RGD domain significantly diminished the amount of active TGF-β in fibronectin-deficient stellate cells and normalized collagen-type-I production in response to TGF-β stimulation. Thus, excessive stellate cell activation and production of collagen results from increased active TGF-β and TGF-β signaling in the absence of fibronectin.

In conclusion, our data indicate that fibronectin controls the availability of active TGF-β in the injured liver, which impacts the severity of the resulting fibrosis. We therefore propose a novel role for locally produced fibronectin in protecting the liver from an excessive TGF-β-mediated response.

Lineage tracing demonstrates no evidence of cholangiocyte epithelial-to-mesenchymal transition in murine models of hepatic fibrosis

Whether or not cholangiocytes or their hepatic progenitors undergo an epithelial-to-mesenchymal transition (EMT) to become matrix-producing myofibroblasts during biliary fibrosis is a significant ongoing controversy. To assess whether EMT is active during biliary fibrosis, we used Alfp-Cre × Rosa26-YFP mice, in which the epithelial cells of the liver (hepatocytes, cholangiocytes, and their bipotential progenitors) are heritably labeled at high efficiency with yellow fluorescent protein (YFP). Primary cholangiocytes isolated from our reporter strain were able to undergo EMT in vitro when treated with transforming growth factor-β1 alone or in combination with tumor necrosis factor-α, as indicated by adoption of fibroblastoid morphology, intracellular relocalization of E-cadherin, and expression of α-smooth muscle actin (α-SMA). To determine whether EMT occurs in vivo, we induced liver fibrosis in Alfp-Cre × Rosa26-YFP mice using the bile duct ligation (BDL) (2, 4, and 8 weeks), carbon tetrachloride (CCl(4) ) (3 weeks), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC; 2 and 3 weeks) models. In no case did we find evidence of colocalization of YFP with the mesenchymal markers S100A4, vimentin, α-SMA, or procollagen 1α2, although these proteins were abundant in the peribiliary regions.

CONCLUSION

Hepatocytes and cholangiocytes do not undergo EMT in murine models of hepatic fibrosis.

Vinculin and cellular retinol-binding protein-1 are markers for quiescent and activated hepatic stellate cells in formalin-fixed paraffin embedded human liver

Hepatic stellate cells (HSCs) have important roles in the pathogenesis of liver fibrosis and cirrhosis. As response to chronic injury HSCs are activated and change from quiescent into myofibroblast-like cells. Several HSC-specific markers have been described in rat or mouse models. The aim of our work was to identify the best marker(s) for human HSCs. To this end we used the automated high throughput NexES IHC staining device (Ventana Medical Systems) to incubate sections under standardized conditions. Formalin fixed paraffin embedded (FFPE) normal and diseased human livers were studied. With immunohistochemistry we examined the expression of synemin, desmin, vimentin, vinculin, neurotrophin-3 (NT-3), alpha-smooth muscle actin (alpha-SMA), cellular retinol-binding protein-1 (CRBP-1), glial fibrillary acidic protein (GFAP), cysteine- and glycine-rich protein 2 (CRP2), and cytoglobin/stellate cell activation-associated protein (cygb/STAP). This is the first study in which a series of HSC markers is compared on serial FFPE human tissues. CRBP-1 clearly stains lobular HSCs without reacting with smooth muscle cells (SMCs) and shows variable cholangiocyte positivity. Vinculin has a similar staining pattern as CRBP-1 but additionally stains SMCs, and (myo)fibroblasts. In conclusion, we therefore propose to use CRBP-1 and/or vinculin to stain HSCs in human liver tissues.

Stellate cell contraction: role, regulation, and potential therapeutic target

The contraction of hepatic stellate cells has been proposed to mediate fibrosis by regulating sinusoidal blood flow and extracellular matrix remodeling. Abundant data from diverse, yet complementary, experimental methods support a robust model for the regulation of contractile force generation by stellate cells. In this model, soluble factors associated with liver injury, including endothelin 1 and nitric oxide, are transduced primarily through Rho signaling pathways that promote the myosin II-powered generation of contractile force by stellate cells. The enhanced knowledge of the role and differential regulation of stellate cell contraction may facilitate the discovery of new and targeted strategies for the prevention and treatment of hepatic fibrosis.

p75 Neurotrophin receptor is a marker for precursors of stellate cells and portal fibroblasts in mouse fetal liver

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) and portal fibroblasts (PFs) are 2 distinct mesenchymal cells in adult liver. HSCs in sinusoids accumulate lipids and express p75 neurotrophin receptor (p75NTR). HSCs and PFs play pivotal roles in liver regeneration and fibrosis. However, the roles of mesenchymal cells in fetal liver remain poorly understood. In this study, we aimed to characterize mesenchymal cells in mouse fetal liver.

METHODS

We prepared an anti-p75NTR monoclonal antibody applicable for flow cytometry and immunohistochemistry. p75NTR(+) cells isolated from fetal liver by flow cytometry were characterized by reverse-transcription polymerase chain reaction, immunohistochemistry, and cell cultivation. Lipid-containing cells were visualized by Oil-red O staining.

RESULTS

p75NTR(+) cells in fetal liver were clearly distinct from endothelial cells and showed characteristics of mesenchymal cells. At embryonic day (E) 10.5, p75NTR(+) cells were present at the periphery of the liver bud in close contact with endothelial cells, and spread over the liver at E11.5. With the formation of the liver architecture, they began to localize to 2 distinct areas, parenchymal and portal areas, and lipid-containing p75NTR(+) cells increased accordingly. p75NTR(+) cells around portal veins were adjacent to cholangiocytes and expressed Jagged1, a crucial factor for the commitment of hepatoblasts to cholangiocytes. By cultivation, p75NTR(+) cells showed features of adult HSCs with markedly increased expression of glial fibrillary acidic protein and alpha-smooth muscle actin.

CONCLUSIONS

p75NTR(+) mesenchymal cells in fetal liver include progenitors for HSCs and PFs, and the anti-p75NTR monoclonal antibody is useful for their isolation.

Comparative studies on expression of alpha-smooth muscle actin in hepatic stellate cells in chronic hepatitis B and C

BACKGROUND/AIMS

Chronic hepatitis B and hepatitis C are common causes of liver fibrosis and cirrhosis. We performed a comparative study on the expression of alpha-smooth muscle actin (alpha-SMA) in hepatic stellate cells (HSCs), a marker of HSC activation, in patients with chronic hepatitis B and hepatitis C.

PATIENTS AND METHODS

Using immunohistochemistry and a semi-quantitative scoring method, the expression of alpha-SMA in HSCs was studied in patients with chronic hepatitis B (n = 50) and hepatitis C (n = 50). The HSC activation index was correlated with age, sex, AST, ALT, viral genotype, viral titers, degrees of hepatic steatosis, necroinflammatory grades and fibrotic stages.

RESULTS

The HSC activation index correlated significantly (P < 0.05) with necroinflmmatory grades and fibrotic stages in chronic hepatitis B or hepatitis C. Besides, the HSC activation index also correlated significantly (P < 0.05) with hepatic steatosis and marginally significantly (P = 0.08) with serum viral titers in chronic hepatitis C. There was no significant difference in biochemical and histological activities between patients with hepatitis B and hepatitis C, but the latter had a significantly higher HSC activation index than the former. Multiple regression analysis in all 100 patients showed that the HSC activation index correlated significantly (P < 0.05) with necroinflammatory grades, fibrotic stages and hepatitis C (versus hepatitis B).

CONCLUSION

In chronic viral hepatitis, the HSC activation index correlated significantly and independently with necroinflammation and fibrosis. Additionally, the HSC activation index was significantly higher in patients with chronic hepatitis C. These data may be compatible with the postulation that hepatitis C virus can directly activate HSCs.

Liver fibrosis

Liver damage leads to an inflammatory response and to the activation and proliferation of mesenchymal cell populations within the liver which remodel the extracellular matrix as part of an orchestrated wound-healing response. Chronic damage results in a progressive accumulation of scarring proteins (fibrosis) that, with increasing severity, alters tissue structure and function, leading to cirrhosis and liver failure. Efforts to modulate the fibrogenesis process have focused on understanding the biology of the heterogeneous liver fibroblast populations. The fibroblasts are derived from sources within and out with the liver. Fibroblasts expressing alpha-smooth muscle actin (myofibroblasts) may be derived from the transdifferentiation of quiescent hepatic stellate cells. Other fibroblasts emerge from the portal tracts within the liver. At least a proportion of these cells in diseased liver originate from the bone marrow. In addition, fibrogenic fibroblasts may also be generated through liver epithelial (hepatocyte and biliary epithelial cell)-mesenchymal transition. Whatever their origin, it is clear that fibrogenic fibroblast activity is sensitive to (and may be active in) the cytokine and chemokine profiles of liver-resident leucocytes such as macrophages. They may also be a component driving the regeneration of tissue. Understanding the complex intercellular interactions regulating liver fibrogenesis is of increasing importance in view of predicted increases in chronic liver disease and the current paucity of effective therapies.

Liver cirrhosis and hepatic stellate cells

The cirrhosis represents the final stage of several chronic hepatic diseases and it is characterized by the presence of fibrosis and morphologic conversion from the normal hepatic architecture into structurally abnormal nodules. In the evolution of the disease there is loss of the normal vascular relationship and portal hypertension. There are also regenerative hepatocellular alterations that become more prominent with the progression of the disease. The liver transplantation continues to be the only therapeutic option in cases of disease in terminal phase. The hepatic stellate cells (HSC) are perisinusoidal cells that store vitamin A and produce growth factors, citocins, prostaglandins and other bioactive substances. They can suffer an activation process that convert them to cells with a phenotype similar to myofibroblasts. When activated, they present increased capacity of proliferation, mobility, contractility and synthesis of collagen and other components of extracellular matrix. They possess cytoplasmic processes adhered to sinusoids and can affect the sinusoidal blood flow. HSC are important in pathogenesis of fibrosis and portal hypertension.

Hepatic Stellate Cells in Biopsies From Liver Allografts With Acute Rejection

BACKGROUND

[corrected] Hepatic stellate cells (HSCs) are nonparenchymal elements that play a major role in fibrogenesis due to various pathologies. HSCs are easily activated by certain injuries, which produce contraction and relaxation of HSCs, resulting in hepatic microcirculatory disturbances. The present study sought to analyze the expression of alpha-smooth muscle actin (alpha-SMA) positive HSCs in liver allografts during acute rejection episodes (ARE), determining whether it was related to the pathogenesis of this immune response.

MATERIALS AND METHODS

Using immunohistochemistry and a semiquantitative scoring system, the expression of alpha-SMA in HSCs was analyzed in liver allografts with ARE (group 1, n = 64) or without ARE (group 2, n = 20). Normal liver tissue from transplant donors (group 3, n = 53) served as the control materials.

RESULTS

Significantly more alpha-SMA positive HSCs were found in group 2 than in the other two groups (P < .05). The minimal difference observed between groups 1 and 3 was not statistically significant. As well, no statistical association was found between expression of alpha-SMA and the clinical parameters of age, gender, etiology of liver failure, donor type (partial or whole), posttransplantation period, and liver function tests.

CONCLUSIONS

While these results represent preliminary findings, it may be possible that HSC expression is a protective mechanism during ARE in hepatic allograft patients. If this is true, enhanced expression of this protein may mitigate ARE in liver allograft patients.

The effect of vitamin A on CCl4-induced hepatic injuries in rats: a histochemical, immunohistochemical and ultrastructural study

In this study, we aimed to investigate the effect of vitamin A on the transformation of the Ito cells to fibrogenic form and suppression of the development of fibrosis. Carbon tetrachloride intoxication was performed on rats for 2, 8, 12 or 20 weeks and 5x10(4) IU vitamin A (as retinol palmitate) was injected subcutaneously once every 4 weeks. Ito cells were detected by gold chloride impregnation, as well as desmin and alpha-smooth muscle actin (alpha-SMA) immunohistochemistry. Additionally, all groups were examined ultrastructurally. The number of Ito cells that were labelled positively with gold impregnation decreased in the fibrotic groups; however, alpha-SMA and desmin immunopositive Ito cells increased. The samples from animals that were treated with vitamin A showed an increase in labelling with gold impregnation but a decrease in alpha-SMA immunopositivity. The data showed that vitamin A can prevent hepatic injury, by suppressing the transformation of Ito cells to fibrogenic form. We conclude that vitamin A has potential for the treatment of hepatic fibrotic diseases. Alpha-SMA immunohistochemistry was found to be more informative than desmin immunohistochemistry for monitoring liver fibrosis.

Proteomic analysis of livers of patients with primary hepatolithiasis

Primary hepatolithiasis or intrahepatic calculi (IHC), which is characterized by the formation of gallstones in the intrahepatic bile duct, is an intractable liver disease and suspected to be one of the causes of cholangiocellular carcinoma. To obtain an insight into the disease, we performed proteomic analysis of liver tissue specimens of paired affected and unaffected hepatic segments from patients with primary hepatolithiasis by two-dimensional gel electrophoresis followed by identification of proteins. For the specimens from the unaffected segments, 125 spots out of 613 spots were identified, defining 83 unique protein names. For the specimens from the affected segments, 102 spots out of 671 spots were identified, defining 74 unique protein names. To further precisely compare, we used two-dimensional fluorescence difference gel electrophoresis. Consequently we identified 12 up-regulated proteins and 21 down-regulated proteins. The up-regulated proteins contained the proteins related to liver fibrosis and to cellular oxidoreduction. The down-regulated proteins contained RAF kinase inhibitor protein, chaperonin and proteins related to principal liver function.

A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populations

Activation of hepatic stellate cells (HSCs) and other resident mesenchymal cells into myofibroblasts expressing alpha smooth muscle actin (alphaSMA) and collagen I is a key event in liver fibrogenesis. However, the temporal expression profiles of alphaSMA and collagen I genes in these cells is unknown. To address this question, we studied alphaSMA and collagen alpha1(I) transcriptional patterns in primary cultures of HSCs, and additionally, in an in vivo model of secondary biliary fibrosis using transgenic mice that express the Discomsoma sp. red fluorescent protein (RFP) and the enhanced green fluorescent protein (EGFP) reporter genes under direction of the mouse alphaSMA and collagen alpha1(I) promoter/enhancers, respectively. The alphaSMA-RFP mice were crossed with collagen-EGFP mice to generate double transgenic mice. Reporter gene expression in cultured HSCs demonstrated that both transgenes were induced at day 3 with continued expression through day 14. Interestingly, alphaSMA and collagen alpha1(I) transgenes were not coexpressed in all cells. Flow cytometry analysis showed three different patterns of gene expression: alphaSMA-RFP positive cells, collagen-EGFP positive cells, and cells expressing both transgenes. AlphaSMA-only and alphaSMA/collagen expressing cells showed higher expression levels of synaptophysin, reelin, MMP13, TIMP1, and ICAM-1 compared to collagen-only expressing cells, as assessed by real-time PCR. Following bile duct ligation, alphaSMA and collagen alpha1(I) transgenes were differentially expressed by peribiliary, parenchymal and vascular fibrogenic cells. Peribiliary cells preferentially expressed collagen alpha1(I), while parenchymal myofibroblasts expressed both alphaSMA and collagen alpha1(I). In conclusion, these data demonstrate heterogeneity of gene expression in myofibroblastic cells during active fibrogenesis. These reporter mice provide a useful tool to further characterize fibrogenic cell types and to evaluate antifibrotic drugs.

Regulation of the mesangial cell myofibroblast phenotype by actin polymerization

Mesangial cells in diverse glomerular diseases become myofibroblast-like, characterized by activation of smooth muscle alpha-actin (alpha-SMA) expression. In cultured mesangial cells, serum-deprivation markedly increases alpha-SMA expression, cell size, and stress fiber formation. Since stress fibers are assembled from actin monomers, we investigated the hypothesis that alterations in stress fiber formation regulate alpha-SMA expression and hypertrophy. Human mesangial cells were treated with agents that disrupt or stabilize actin stress fibers. Depolymerization of actin stress fibers in serum-deprived cells with actin-depolymerizing agents, cytochalasin B (CytB) and latrunculin B (LatB), or with inhibitors of Rho-kinase, Y-27632 and HA-1077 decreased alpha-SMA mRNA as judged by Northern blot analysis. Western blot analysis showed that CytB also reduced alpha-SMA protein levels. In serum-fed cells, agents that stabilized actin stress fibers, jasplakinolide (Jas) and phalloidin, increased alpha-SMA mRNA and protein. Treatment of human or rat mesangial cells with CytB, LatB, or Y-27632 decreased alpha-SMA promoter activity. In contrast, Jas increased promoter activity 5.6-fold in rat mesangial cells. The presence of an RNA polymerase inhibitor blocked degradation of alpha-SMA mRNA in cells treated with CytB suggesting that destabilization of this message is dependent on a newly transcribed or rapidly degraded factor. Inhibition of actin polymerization by CytB, LatB, Y-27623, and HA-1077 inhibited incorporation of (3)[H]-leucine into newly synthesized protein. Additionally, CytB and LatB decreased cell volume as determined by flow cytometry. Collectively, these results indicate that the state of polymerization of the actin cytoskeleton regulates alpha-SMA expression, hypertrophy, and myofibroblast differentiation in mesangial cells.

Intrahepatic expression of the hepatic stellate cell marker fibroblast activation protein correlates with the degree of fibrosis in hepatitis C virus infection

BACKGROUND

Activated hepatic stellate cells (HSCs), recognised by their alpha smooth muscle actin immunoreactivity, are primarily responsible for liver fibrosis. However, the presence of alpha smooth muscle actin positive HSCs is not always associated with the development of liver fibrosis. Recently, other markers of human HSCs including the gelatinase fibroblast activation protein (FAP) and glial fibrillary acidic protein have been identified.

AIMS

We examined the relationship between the expression of these HSC markers and the severity of liver injury in patients with chronic hepatitis C virus infection.

METHODS

Liver tissue from 27 patients was examined using immunohistochemistry. Linear correlation analysis was used to compare staining scores with the stage and grade of liver injury.

RESULTS-CONCLUSIONS

FAP expression, seen at the tissue-remodelling interface, was strongly and significantly correlated with the severity of liver fibrosis. A weaker correlation was seen between glial fibrillary acidic protein expression and fibrosis stage. This contrasted with the absence of a relationship between alpha smooth muscle actin and the fibrotic score. A correlation was also observed between FAP expression and necroinflammatory score. In summary, FAP expression identifies a HSC subpopulation at the tissue-remodelling interface that is related to the severity of liver fibrosis.

Characterization of the inflammatory infiltrate in canine chronic hepatitis

Canine chronic hepatitis (CCH) is a progressive inflammatory disease of unknown etiology. To characterize the inflammatory infiltrate, 16 dogs with CCH were selected and classified into three groups based on the stage of fibrosis, as evaluated with Masson's trichrome stain. The inflammatory infiltrate in each liver section was immunohistochemically characterized and evaluated using CD3, lysozyme, lamba and kappa light chain, and alpha-smooth muscle actin antibodies. Numerous breeds were affected, and middle-aged females predominated in this select group. Necroinflammatory activity progressively increased and then waned as the hepatitis progressed to cirrhosis. CD3+ lymphocytes were the most numerous lymphoid cells in dogs with CCH. Degenerate hepatocytes were occasionally surrounded by CD3+ lymphocytes. Necrosis was positively correlated with the number of CD3+ lymphocytes. The lamba and kappa light chain-positive cell infiltrate was variable but generally mild. A positive correlation between the lambda and kappa light chain-positive cells and the portal alpha-smooth muscle actin was found. The number of alpha-smooth muscle actin-positive cells (myofibroblasts) in portal triads and fibrous septa was positively correlated with the stage of fibrosis. In contrast, no correlation was found between the number of lysozyme-positive cells (Kupffer cells) and the stage of fibrosis. These results further support the idea of an immune-mediated process in CCH and suggest that periductular myofibroblasts play an important role in canine liver fibrogenesis.

Pathology and pathogenesis of idiopathic portal hypertension with an emphasis on the liver

Idiopathic portal hypertension (IPH) is characterized by a long-standing presinusoidal portal hypertension of unknown etiology in adults. Some unidentified agent(s) affect(s) the intrahepatic small portal veins or portal tracts. Immunological disturbance, thromboembolism, infectious etiology and/or increased fibrogenesis in portal tracts are suspected as being candidates for the primary agent(s). During the long clinical course of IPH, several pathological changes may occur, including subcapsular parenchymal atrophy, atrophy of the liver, portal and parenchymal fibrosis, and portal venous phlebosclerosis and thrombosis. The last-named of these lesions is mostly found in patients with a history of splenectomy. Subcapsular parenchymal and hepatic atrophy may result from a hepatocellular dropout via apoptosis or necrosis because of intrahepatic hemodynamic disturbances, particularly chronic portal venous blood insufficiency. Pericellular fibrosis and thin fibrous septa are also frequently found and associated with activated perisinusoidal cells positive for smooth muscle actin. At the same time, vague nodular hyperplasia of hepatocytes not surrounded by fibrous septa is not infrequently seen. It may resemble nodular regenerative hyperplasia, partial nodular transformation, or focal nodular hyperplasia. However, liver cirrhosis does not occur even at the terminal stage. Taking these findings into consideration, a new staging of IPH with a combination of hepatic parenchymal atrophy and portal venous thrombosis was proposed: non-atrophic liver without subcapsular parenchymal atrophy (stage I), non-atrophic liver with subcapsular parenchymal atrophy (stage II), atrophic liver with subcapsular parenchymal atrophy (stage III), and portal venous occlusive thrombosis (stage IV). IPH livers are likely to progress from stage I to stage III. Stage IV, which occurs relatively late, has a poor prognosis. This staging is applicable to clinical and autopsy cases without any histological data.

Ito cell morphology, alpha-smooth muscle actin and collagen type IV expression in the liver of patients with gastric and colorectal tumors

The alteration in sinusoidal collagen type IV occurrence, and myofibroblastic (alpha-SMA-positive) Ito cellular transformation are described in the liver of patients with malignant gastric and colorectal tumors, using electron microscopy as well as light microscopical and ultrastructural immunohistochemistry. The ultrastructural finding revealed transformation of Ito cells mostly into transitional cells in highly differentiated primary tumors and into transitional and myofibroblast-like cells with expressed changes in the other sinusoidal cells in poorly differentiated tumors. Ito cell numbers increased significantly in the livers of cancer patients. A highly significant statistical association was obtained between Ito cell numbers on the one hand and collagen type IV and alpha-SMA immunoreactivity on the other hand in the pericentral zone of the liver lobule. Ultrastructural immunohistochemistry showed increased collagen IV immune deposits in the space of Disse, assembled for the most part around and inside transitional cells. Alpha-SMA immunoreactivity was detected in activated Ito cells diffuse in the lobule, with stronger expression in the intermediate and pericentral zones. It is suggested that stimuli which can influence Ito cell transformation are produced by tumor cells from the primary tumor (TGF-beta1, TNF-alpha, PDGF-beta etc.) and from the metastasizing gastric or colorectal tumor cells--matrix metalloproteinase-2 (MMP-2). It is suggested that sinusoidal extracellular matrix deterioration creates a barrier for cancer invasion on the one hand, or possibly facilitates metastasizing by ensurance of matrix for adhesion on the other hand.

Hepatic stellate cell activation and liver fibrosis are associated with necroinflammatory injury and Th1-like response in chronic hepatitis C

BACKGROUND/AIMS

The involvement of a direct viral cytopathic effect or an immune-mediated mechanism in the progression of hepatic damage in chronic hepatitis C is controversial. The type of immune response is itself a matter of controversy, and histological data are lacking. The aim of this study was to identify the factors associated with the progression of liver injury in 30 HCV/RNA-positive untreated patients with chronic hepatitis.

METHODS

Necroinflammatory and architectural damage were evaluated using Ishak's score. Activated hepatic stellate cells (HSC) were visualized by immunohistochemistry for alpha-smooth muscle actin (alphaSMA) and quantitated by morphometry. Plasma HCV/RNA was evaluated using a competitive RT-PCR method. To study the type of immune response involved in the progression of liver injury, interferon gamma (IFNgamma)-positive cells (as expression of a Th1-like response) were evaluated by immunohistochemistry and quantitated by morphometry.

RESULTS

HSC were mostly detected close to areas of lobular necroinflammation or lining fibrotic septa. The alphaSMA- and Sirius Red-positive parenchyma correlated significantly with necroinflammatory and architectural scores. IFNgamma-positive cells were detected in periportal areas associated with the inflammatory infiltrates and significantly correlated with architectural damage. No relationship was found between the histological features of liver injury and viral load.

CONCLUSIONS

HSC activation and progression of liver injury are unrelated to viral load but associated with a Th1-like response, a plausible target for the treatment of chronic hepatitis C.

Fibroblast activation protein: a cell surface dipeptidyl peptidase and gelatinase expressed by stellate cells at the tissue remodelling interface in human cirrhosis

Fibroblast activation protein (FAP) is a cell surface-bound protease of the prolyl oligopeptidase gene family expressed at sites of tissue remodelling. This study aimed to delineate the expression of FAP in cirrhotic human liver and examine its biochemical activities. Seventeen cirrhotic and 8 normal liver samples were examined by immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR). Hepatic stellate cells (HSC) were isolated and immunostained. Recombinant FAP and immunopurified, natural FAP were analyzed for protease activities and similarities to dipeptidyl peptidase IV (DPPIV), a structurally related enzyme. FAP-specific messenger RNA and immunoreactivity were detected in cirrhotic, but not normal, livers. FAP immunoreactivity was most intense on perisinusoidal cells of the periseptal regions within regenerative nodules (15 of 15 cases); this pattern coincides with the tissue remodelling interface. In addition, human FAP was expressed by cells within the fibrous septa (10 of 15 cases). Cell morphology, location, and colocalization with glial fibrillary acidic protein (GFAP) indicated that FAP is present on HSC in vivo. Similarly, isolated HSC expressed FAP in vitro. Both natural FAP from cirrhotic liver and recombinant FAP were shown to have gelatinase and dipeptidyl peptidase activities. FAP is a cell-bound, dual-specificity dipeptidyl peptidase and gelatinase expressed by activated HSC at the tissue remodelling interface in human cirrhosis. FAP may contribute to the HSC-induced extracellular matrix (ECM) changes of cirrhosis.

Quantitative analysis of liver fibrosis and stellate cell changes in patients with chronic hepatitis C after interferon therapy

OBJECTIVE

The proliferation and differentiation of stellate (Ito, or fat-storing) cells into myofibroblast-like cells is responsible for the development of liver fibrosis. Using computer image analysis, we evaluated the changes of alpha smooth muscle actin-positive stellate cells and liver fibrosis after interferon-alpha or -beta (IFN-alpha, beta) therapy in patients with chronic hepatitis C.

METHODS

Patients with chronic hepatitis C were treated with IFN-alpha or -beta and were divided into three groups on the basis of clinical criteria; a complete responder group (CR, 18 of 51), a partial responder group (PR, 17 to 51), and a nonresponder group (NR, 16 of 51). Liver fibrosis was assessed from specimens stained with Sirius red and was quantitated by computer image analysis. We also evaluated alpha-smooth muscle actin expression in the liver before and after IFN therapy by a semiquantitative scoring method (the alpha-smooth muscle actin index).

RESULTS

Before IFN therapy, a large number of stellate cells expressing a-smooth muscle actin were present in the liver biopsy specimens. There was a significant correlation (r = 0.699, p < 0.05) between the change in the percent area of fibrosis and the alpha-smooth muscle actin index before and after IFN therapy in all groups. The complete responder group also showed a significant reduction of a-smooth muscle actin-expressing cells that was correlated with the reduction of serum ALT (r = 0.686, p < 0.05).

CONCLUSION

These results suggest a-smooth muscle actin-expressing cells are responsible for liver fibrosis, and the elimination of factors stimulating matrix synthesis (e.g., hepatitis virus) may decrease liver fibrosis.

Development of hepatic sinusoidal structure with special reference to the Ito cells

To elucidate sinusoidal cell structure and function under normal conditions and their behavior in diseased settings, an understanding of their developmental aspects is needed. At day 10 of gestation in mice and rats or at 5 weeks of gestation in humans, the hepatic cords grow into the mesenchymal tissue of the septum transversum, and the primitive sinusoidlike structure is simultaneously observed between the liver cell cords. In the margin of the growing liver primordium, mesenchymal cells in the septum transversum are trapped in the subendothelial space. These subendothelial cells are at the early stages of organogenesis and become progenitors of the Ito cells. By days 12-14 of gestation in mice and rats or 8 weeks of gestation in humans, the basic structure of the sinusoids has developed. Embryonic hepatic sinusoids are usually lined by a continuous endothelium without basement membranes, and an incompletely fenestrated sinusoid appears at the middle gestational stage. In the late gestational stages, the Ito cells exhibit myofibroblastlike features in humans, mice, and rats. In association with this event, perisinusoidal reticular networks are gradually intensified. After birth until days 4-5 in mice and rats, the sinusoidal and perisinusoidal structures are almost completely formed, although slight morphological differences from those in adult livers still exist. What happens to sinusoidal endothelial cells and Ito cells in hepatic fibrosis-cirrhosis of the adult may be a deviated or uncontrolled occurrence of what goes on during the fetal period, i.e., a continuous nonfenestrated sinusoidal lining in the early embryonic stage and a myofibroblastlike transformation of Ito cells in late fetal life.