Effects of retinoic acid on the development of liver fibrosis produced by carbon tetrachloride in mice

Intervention mechanism of marine-based chito-oligosaccharide on acute liver injury induced by AFB1 in rats

Aflatoxin B1 (AFB1) is extremely hepatotoxic, a causative agent of liver cancer, and can cause symptoms of acute or chronic liver damage. Chito-oligosaccharides (COS), obtained from the degradation of chitosan derived from shrimp and crab shells, is a natural antioxidant substance and its antitumor properties have been widely studied, but less research has been done on the prevention of AFB1-induced acute liver injury. In this study, rats were acutely exposed to 1 mg/kg BW AFB1 and simultaneously gavaged with different doses of COS for 8 days. The results showed that COS attenuated the hepatic histopathological changes and reduced serum biochemical indices (ALT, AST, ALP, and TBIL) in rats. It significantly inhibited MDA content and promoted SOD and GSH-Px activity production. Moreover, it also improved hepatocyte apoptosis. Furthermore, AFB1-vs-HCOS differential genes were enriched with 622 GO entries, and 380 were Biological Processes, 170 were Molecular Functions, 72 were Cellular Components. Differentially expressed genes (DEGs) analyzed by KEGG enrichment were more enriched in pathways, such as metabolism, PPAR signaling pathway, and peroxisome. Q-PCR technique verified that Lama5, Egr1, Cyp2b1, and Gadd45g in DEGs were associated with oxidative stress damage and apoptosis. In conclusion, COS intervention reduces the effect of AFB1 on hepatic genes and thus reduces the changes in hepatic gene function.

Dually fibronectin/CD44-mediated nanoparticles targeted disrupt the Golgi apparatus and inhibit the hedgehog signaling in activated hepatic stellate cells to alleviate liver fibrosis

Liver fibrosis is featured by activation of hepatic stellate cells (HSCs) and excessive accumulation of extracellular matrix (ECM). The Golgi apparatus in HSCs plays a vital role in synthesis and secretion of ECM proteins, while its targeted disruption in activated HSCs could be considered as a promising approach for liver fibrosis treatment. Here, we developed a multitask nanoparticle CREKA-CS-RA (CCR) to specifically target the Golgi apparatus of activated HSCs, based on CREKA (a specific ligand of fibronectin) and chondroitin sulfate (CS, a major ligand of CD44), in which retinoic acid (a Golgi apparatus-disturbing agent) chemically conjugated and vismodegib (a hedgehog inhibitor) encapsulated. Our results showed that CCR nanoparticles specifically targeted activated HSCs and preferentially accumulated in the Golgi apparatus. Systemic administration of CCR nanoparticles exhibited significantly accumulation in CCl4-induced fibrotic liver, which was attributed to specific recognition with fibronectin and CD44 on activated HSCs. CCR nanoparticles loaded with vismodegib not only disrupted Golgi apparatus structure and function but also inhibited the hedgehog signaling pathway, thus markedly suppressing HSC activation and ECM secretion in vitro and in vivo. Moreover, vismodegib-loaded CCR nanoparticles effectively inhibited the fibrogenic phenotype in CCl4-induced liver fibrosis mice without causing obvious toxicity. Collectively, these findings indicate that this multifunctional nanoparticle system can effectively deliver therapeutic agents to the Golgi apparatus of activated HSCs, thus has potential treatment of liver fibrosis with minimal side effects.

Ameliorative effects of camel milk and silymarin upon aflatoxin B1 induced hepatic injury in rats

Aflatoxin B1 (AFB1) poses a major risk to both human and animal health because it contaminates food, feed, and grains. These dangerous effects can be mitigated using natural components. The purpose of this study was to examine the ameliorative effects of camel milk and silymarin supplementation upon aflatoxin B1 induced hepatic injury in rats. This improvement was assessed by measuring leukocytic and deferential counts, serum biochemical parameters, and gene expression of Tumor Necrosis Factor (TNF-α), antioxidant gene (NAD(P)H quinone oxidoreductase 1 (NQO1)), and base excision repair genes (APE1 and OGG1) in the liver tissue, in addition to liver histopathology. Sixty mature males Wister white rats were used to perform the present study; the rats were distributed in six groups (ten rats/group). The control group (without any treatment) received saline by gavage. The camel milk group received 1 ml of camel milk/kg body weight. The silymarin group received 1 ml of silymarin suspension solution at a dose of 20 mg of silymarin/kg of b.wt. The aflatoxin group received an aflatoxin-contaminated diet at a dose of 1.4 mg of aflatoxin /kg of diet and received saline. The camel milk + aflatoxin group received the same previous oral doses of camel milk and an aflatoxin-contaminated diet at the same time. The silymarin + aflatoxin group received the same previous doses of silymarin orally and an aflatoxin-contaminated diet at the same time. The obtained data indicated the deleterious effect of aflatoxin B1 on the leukocytic count, activity of AST and ALT, serum proteins, ferritin, alpha-fetoprotein, carcinoembryonic antigen, liver pathology, and the expression of the studied genes. However, these deleterious effects were mitigated by camel milk and silymarin supplementation. Thus, we could conclude that the ingestion of camel milk and silymarin mitigated the negative effects of AFB1 on the hematology, activity of AST and ALT, serum proteins, ferritin, alpha-fetoprotein, carcinoembryonic antigen, liver pathology, and gene expression in the rat model.

Cyp4a12-mediated retinol metabolism in stellate cells is the antihepatic fibrosis mechanism of the Chinese medicine Fuzheng Huayu recipe

BACKGROUND

Hepatic stellate cells (HSCs), which contain multiple retinol-containing lipid droplets, are important profibrotic cells in liver fibrosis. Under Cyp4a12a/b oxidation, HSC activation was accompanied by the downregulation of genes involved in retinol metabolism, inducing RAE-1 production. By eliminating activated HSCs, NK cells expressing the activating receptor NKG2D are recruited to alleviate fibrosis. FZHY was found to significantly reduce the severity of liver fibrosis by inhibiting the activation and proliferation of HSCs. The molecular processes that govern retinol metabolism, on the other hand, are largely unexplored. This study focused on the regulation of Cyp4a12a/b by FZHY to elucidate the antifibrotic molecular mechanisms underlying the effect of FZHY on retinol metabolism.

METHODS

To investigate mechanisms and altered pathways of FZHY against carbon tetrachloride (CCl4)-induced liver fibrosis based on transcriptomics data. Bioinformatics analysis was used to screen its pharmacological targets. The predicted targets were confirmed by a series of in vitro and in vivo experiments, including mass spectrometry, in situ hybridization, immunofluorescence assays and real-time PCR. Then, the results were further characterized by recombinant adenovirus vectors that were constructed and transfected into the cultured primary HSCs.

RESULTS

Transcriptomics revealed that Cyp4a12a/b is nearly completely lost in liver fibrosis, and these effects might be partially reversed by FZHY therapy recovery. In vitro and in vivo studies indicated that Cyp4a12a/b deletion disrupted retinol metabolism and lowered Rae-1 expression. Activated HSCs successfully escape recognition and elimination by natural killer (NK) cells as a result of reduced Rae-1. Notablely, we discovered that FZHY may restore the Cyp4a12a/b capability, allowing the recovery of the cytotoxic function of NK cells against HSCs, and thereby reducing hepatic fibrosis by suppressing HSC activation.

CONCLUSION

Our findings revealed a new role for Cyp4a in retinol metabolism in the development of hepatic fibrosis, and they highlight Cyp4a12/Rae-1 signals as possible therapeutic targets for antifibrotic medicines.

Liver fibrosis therapy based on biomimetic nanoparticles which deplete activated hepatic stellate cells

Liver fibrosis is one of the most common liver diseases with substantial morbidity and mortality. However, effective therapy for liver fibrosis is still lacking. Considering the key fibrogenic role of activated hepatic stellate cells (aHSCs), here we reported a strategy to deplete aHSCs by inducing apoptosis as well as quiescence. Therefore, we engineered biomimetic all-trans retinoic acid (ATRA) loaded PLGA nanoparticles (NPs). HSC (LX2 cells) membranes, presenting the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), were coated on the surface of the nanoparticles, while the clinically approved agent ATRA with anti-fibrosis ability was encapsulated in the inner core. The biomimetic coating of TRAIL-expressing HSC membranes does not only provide homologous targeting to HSCs, but also effectively triggers apoptosis of aHSCs. ATRA could induce quiescence of activated fibroblasts. While TM-NPs (i.e. membrane coated NPs without ATRA) and ATRA/NPs (i.e. non-coated NPs loaded with ATRA) only showed the ability to induce apoptosis and decrease the α-SMA expression in aHSCs, respectively, TM-ATRA/NPs induced both apoptosis and quiescence in aHSCs, ultimately leading to improved fibrosis amelioration in both carbon tetrachloride-induced and methionine and choline deficient L-amino acid diet induced liver fibrosis mouse models. We conclude that biomimetic TM-ATRA/NPs may provide a novel strategy for effective antifibrosis therapy.

Anti-liver fibrosis effects of the total flavonoids of litchi semen on CCl4-induced liver fibrosis in rats associated with the upregulation of retinol metabolism

CONTEXT

The litchi semen are traditional medications for treating liver fibrosis (LF) in China. The mechanism remains unclear.

OBJECTIVE

This study investigates the anti-liver fibrotic mechanism of the total flavonoids of litchi semen (TFL).

MATERIALS AND METHODS

Sprague-Dawley rats with carbon tetrachloride-induced LF were treated with TFL (50 and 100 mg/kg) for 4 weeks. The anti-liver fibrotic effects of TFL were evaluated and the underlying mechanisms were investigated via histopathological analysis, proteomic analysis and molecular biology technology.

RESULTS

Significant anti-LF effects were observed in the high-TFL-dose group (TFL-H, p < 0.05). Five hundred and eighty-five and 95 differentially expressed proteins (DEPs) were identified in the LF rat model (M group) and TFL-H group, respectively. The DEPs were significantly enriched in the retinol metabolism pathway (p < 0.0001). The content of 9-cis-retinoic acid (0.93 ± 0.13 vs. 0.66 ± 0.10, p < 0.05, vs. the M group) increased significantly in the TFL-H group. The upregulation of RXRα (0.50 ± 0.05 vs. 0.27 ± 0.13 protein, p < 0.05), ALDH2 (1.24 ± 0.09 vs. 1.04 ± 0.08 protein, p < 0.05), MMP3 (0.89 ± 0.02 vs. 0.61 ± 0.12 protein, p < 0.05), Aldh1a7 (0.20 ± 0.03 vs. 0.03 ± 0.00 mRNA, p < 0.05) and Aox3 (0.72 ± 0.14 vs. 0.05 ± 0.01 mRNA, p < 0.05) after TFL treatment was verified.

CONCLUSIONS

TFL exhibited good anti-liver fibrotic effects, which may be related to the upregulation of the retinol metabolism pathway. TFL may be promising anti-LF agents with potential clinical application prospects.

Dysregulated Retinoic Acid Signaling in the Pathogenesis of Pseudoexfoliation Syndrome

Pseudoexfoliation (PEX) syndrome, a stress-induced fibrotic matrix process, is the most common recognizable cause of open-angle glaucoma worldwide. The recent identification of PEX-associated gene variants uncovered the vitamin A metabolic pathway as a factor influencing the risk of disease. In this study, we analyzed the role of the retinoic acid (RA) signaling pathway in the PEX-associated matrix metabolism and evaluated its targeting as a potential candidate for an anti-fibrotic intervention. We provided evidence that decreased expression levels of RA pathway components and diminished RA signaling activity occur in an antagonistic crosstalk with TGF-β1/Smad signaling in ocular tissues and cells from PEX patients when compared with age-matched controls. Genetic and pharmacologic modes of RA pathway inhibition induced the expression and production of PEX-associated matrix components by disease-relevant cell culture models in vitro. Conversely, RA signaling pathway activation by natural and synthetic retinoids was able to suppress PEX-associated matrix production and formation of microfibrillar networks via antagonization of Smad-dependent TGF-β1 signaling. The findings indicate that deficient RA signaling in conjunction with hyperactivated TGF-β1/Smad signaling is a driver of PEX-associated fibrosis, and that restoration of RA signaling may be a promising strategy for anti-fibrotic intervention in patients with PEX syndrome and glaucoma.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Retinoids in the Pathogenesis and Treatment of Liver Diseases

Vitamin A (VA), all-trans-retinol (ROL), and its analogs are collectively called retinoids. Acting through the retinoic acid receptors RARα, RARβ, and RARγ, all-trans-retinoic acid, an active metabolite of VA, is a potent regulator of numerous biological pathways, including embryonic and somatic cellular differentiation, immune functions, and energy metabolism. The liver is the primary organ for retinoid storage and metabolism in humans. For reasons that remain incompletely understood, a body of evidence shows that reductions in liver retinoids, aberrant retinoid metabolism, and reductions in RAR signaling are implicated in numerous diseases of the liver, including hepatocellular carcinoma, non-alcohol-associated fatty liver diseases, and alcohol-associated liver diseases. Conversely, restoration of retinoid signaling, pharmacological treatments with natural and synthetic retinoids, and newer agonists for specific RARs show promising benefits for treatment of a number of these liver diseases. Here we provide a comprehensive review of the literature demonstrating a role for retinoids in limiting the pathogenesis of these diseases and in the treatment of liver diseases.

A retinoic acid receptor β2 agonist protects against alcohol liver disease and modulates hepatic expression of canonical retinoid metabolism genes

Alcohol abuse reduces hepatic vitamin A (retinoids), reductions that are associated with progression of alcohol liver disease (ALD). Restoring hepatic retinoids through diet is contraindicated in ALD due to the negative effects of alcohol on retinoid metabolism. There are currently no drugs that can both mitigate alcohol-driven hepatic retinoid losses and progression of ALD. Using a mouse model of alcohol intake, we examined if an agonist for the retinoic acid (RA) receptor β2 (RARβ2), AC261066 (AC261) could prevent alcohol-driven hepatic retinoid losses and protect against ALD. Our results show that mice co-treated with AC261 and alcohol displayed mitigation of ALD, including reduced macro, and microvesicular steatosis, and liver damage. Alcohol intake led to increases in hepatic centrilobular levels of ALDH1A1, a rate-limiting enzyme in RA synthesis, and co-localization of ALDH1A1 with the alcohol-metabolizing enzyme CYP2E1, and 4-HNE, a marker of oxidative stress; expression of these targets was abrogated in mice co-treated with AC261 and alcohol. By RNA sequencing technology, we found that AC261 treatments opposed alcohol modulation of 68 transcripts involved in canonical retinoid metabolism. Alcohol modulation of these transcripts, including CES1D, CES1G, RBP1, RDH10, and CYP26A1, collectively favor hepatic retinoid hydrolysis and catabolism. However, despite this, co-administration of AC261 with alcohol did not mitigate alcohol-mediated depletions of hepatic retinoids, but did reduce alcohol-driven increases in serum retinol. Our data show that AC261 protected mice against ALD, even though AC261 did not prevent alcohol-mediated reductions in hepatic retinoids. These data warrant further studies of the anti-ALD properties of AC261.

Circulating Extracellular Vesicles Contain Liver-Derived RNA Species as Indicators of Severe Cholestasis-Induced Early Liver Fibrosis in Mice

Aims: Biliary diseases represent around 10% of all chronic liver diseases and affect both adults and children. Currently available biochemical tests detect cholestasis but not early liver fibrosis. Circulating extracellular vesicles (EVs) provide a noninvasive, real-time molecular snapshot of the injured organ. We thus aimed at searching for a panel of EV-based biomarkers for cholestasis-induced early liver fibrosis using mouse models. Results: Progressive and detectable histological evidence of collagen deposition and liver fibrosis was observed from day 8 after bile duct ligation (BDL) in mice. Whole transcriptome and small RNA sequencing analyses of circulating EVs revealed differentially enriched RNA species after BDL versus sham controls. Unsupervised hierarchical clustering identified a signature that allowed for discrimination between BDL and controls. In particular, 151 microRNAs (miRNAs) enriched in BDL-derived EVs were identified, of which 66 were conserved in humans. The liver was an important source of circulating EVs in BDL animals as evidenced by the enrichment of several hepatic mRNAs, such as Albumin and Haptoglobin. Interestingly, among experimentally validated miRNAs, miR192-5p, miR194-5p, miR22-3p, and miR29a-3p showed similar enrichment patterns also in EVs derived from 3,5-diethoxycarboncyl-1,4-dihydrocollidine-treated (drug-induced severe cholestasis) but not in mice with mild phenotype or non-cholestatic liver fibrosis. Innovation: A panel of mRNAs and miRNAs contained in circulating EVs, when combined, indicates hepatic damage and fibrosis in mice and represents promising biomarkers for human severe cholestasis-induced liver fibrosis. Conclusion: Analysis of EV-based miRNAs, in combination with hepatic injury RNA markers, can detect early cholestatic liver injury and fibrosis in mice. Antioxid. Redox Signal. 36, 480-504.

Erratum: Augmented Liver Uptake of the Membrane Voltage Sensor Tetraphenylphosphonium Distinguishes Early Fibrosis in a Mouse Model

[This corrects the article DOI: 10.3389/fphys.2021.676722.].

Augmented Liver Uptake of the Membrane Voltage Sensor Tetraphenylphosphonium Distinguishes Early Fibrosis in a Mouse Model

Mitochondrial (mito-) oxidative phosphorylation (OxPhos) is a critical determinant of cellular membrane potential/voltage. Dysregulation of OxPhos is a biochemical signature of advanced liver fibrosis. However, less is known about the net voltage of the liver in fibrosis. In this study, using the radiolabeled [³H] voltage sensor, tetraphenylphosphonium (TPP), which depends on membrane potential for cellular uptake/accumulation, we determined the net voltage of the liver in a mouse model of carbon tetrachloride (CCl₄)-induced hepatic fibrosis. We demonstrated that the liver uptake of ³H-TPP significantly increased at 4 weeks of CCl₄-administration (6.07 ± 0.69% ID/g, p < 0.05) compared with 6 weeks (4.85 ± 1.47% ID/g) and the control (3.50 ± 0.22% ID/g). Analysis of the fibrosis, collagen synthesis, and deposition showed that the increased ³H-TPP uptake at 4 weeks corresponds to early fibrosis (F1), according to the METAVIR scoring system. Biodistribution data revealed that the ³H-TPP accumulation is significant in the fibrogenic liver but not in other tissues. Mechanistically, the augmentation of the liver uptake of ³H-TPP in early fibrosis concurred with the upregulation of mito-electron transport chain enzymes, a concomitant increase in mito-oxygen consumption, and the activation of the AMPK-signaling pathway. Collectively, our results indicate that mito-metabolic response to hepatic insult may underlie the net increase in the voltage of the liver in early fibrosis.

Oral Delivery of Encapsulated All-Trans Retinoic Acid Ameliorates Disease in Rodent Models of Colitis

BACKGROUND

All-trans retinoic acid (ATRA) is a biologically active isomer of retinoic acid (RA). Topical ATRA (retin-a, retin-a micro, atralin, renova, and avita) is the active pharmaceutical ingredient for FDA-approved treatments for acne and skin wrinkles. Oral formulations (Vesanoid) treat acute promyelocytic leukemia, but oral dosing can induce severe side effects. Despite benefits in various rodent models of inflammatory bowel disease (IBD), toxicity and controversial clinical observations have diminished enthusiasm for ATRA IBD clinical trials. To circumvent these issues and to use ATRA's key role in maintaining gut tolerance, we developed a poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) encapsulated ATRA formulation aimed at directing ATRA delivery to immune structures of the gut, limiting systemic exposure. Initially, ATRA MS was developed as a component of a combinatorial product (TreXTAM) that also contained encapsulated transforming growth factor (TGF)-β and ATRA in a 1:2 w/w ratio. Although the combination was optimal, benefit was also observed when ATRA MS was given alone in the CD4+ CD25-T-cell adoptive transfer (ACT) colitis model.

METHODS

We used the ACT and DSS-induced murine models of colitis to expand on the dose-dependent effects of oral ATRA MS when given alone. The DSS model was also used to compare the efficacy of ATRA MS and soluble ATRA, while healthy animals were used to compare the pharmacokinetics of the two drugs.

RESULTS

In both the ACT and DSS-induced murine models of colitis, ATRA MS was observed to be effective in ameliorating disease. ATRA MS was also observed to be more effective than soluble ATRA in these models and displayed more favorable pharmacokinetics.

CONCLUSIONS

We suggest ATRA MS, as a standalone product, may attenuate IBD and perhaps limit fibrosis, while limiting systemic side effects.

Roles of nuclear receptors in hepatic stellate cells

Introduction: Hepatic stellate cells (HSCs) are essential for physiological homeostasis of the liver extracellular matrix (ECM). Excessive transdifferentiation of HSC from a quiescent to an activated phenotype contributes to disrupt this balance and can lead to liver fibrosis. Accumulating evidence has suggested that nuclear receptors (NRs) are involved in the regulation of HSC activation, proliferation, and function. Therefore, these NRs may be therapeutic targets to balance ECM homeostasis and inhibit HSC activation in liver fibrosis.Areas covered: In this review, the authors summarized the recent progress in the understanding of the regulatory role of NRs in HSCs and their potential as drug targets in liver fibrosis.Expert opinion: NRs are still potential therapy targets for inhibiting HSCs activation and liver fibrosis. However, the development of NRs agonists or antagonists to inhibit HSCs requires fully consideration of systemic effects.

Nuclear Receptors in Liver Fibrosis

Nuclear receptors are ligand-activated transcription factors that regulate gene expression of a variety of key molecular signals involved in liver fibrosis. The primary cellular driver of liver fibrogenesis are activated hepatic stellate cells. Different NRs regulate the hepatic expression of pro-inflammatory and pro-fibrogenic cytokines that promote the transformation of hepatic stellate cells into fibrogenic myofibroblasts. Importantly, nuclear receptors regulate gene expression circuits that promote hepatic fibrogenesis and/or allow liver fibrosis regression. In this review, we highlight the direct and indirect influence of nuclear receptors on liver fibrosis, with a focus on hepatic stellate cells, and discuss potential therapeutic effects of nuclear receptor modulation in regard to anti-fibrotic and anti-inflammatory effects. Further research on nuclear receptors-related signaling may lead to the clinical development of effective anti-fibrotic therapies for patients with liver disease.

Albumin inhibits the nuclear translocation of Smad3 via interleukin-1beta signaling in hepatic stellate cells

Activation of quiescent hepatic stellate cells (HSCs) to myofibroblasts plays a key role in liver fibrosis. We had previously shown that albumin and its derivative, R-III (a retinol-binding protein—albumin domain III fusion protein), inhibited HSC activation by sequestering retinoic acid (RA) and that R-III administration reduced carbon tetrachloride (CCl₄)-induced liver fibrosis. In this study, we aimed to elucidate the mechanism of action of albumin downstream of RA sequestration. Nuclear factor-κB p65 was evenly distributed in the cytoplasm in activated mouse HSCs, whereas albumin expression or R-III treatment (albumin/R-III) caused the nuclear translocation of p65, probably via RA sequestration, resulting in a dramatic increase in interleukin-1beta (IL-1β) expression. Albumin/R-III in turn induced the phosphorylation of Smad3 at the linker region, inhibiting its nuclear import in an IL-1β-dependent manner. Consistent with the in vitro results, the level of IL-1β mRNA expression was higher in CCl₄/R-III-treated livers than in CCl₄-treated livers. These findings reveal that albumin/R-III inhibits the transforming growth factor-β-Smad3 signaling as well as the retinoic acid receptor-mediated pathway, which probably contributes to the inhibition of HSC activation, and suggest that R-III may be an anti-fibrotic drug candidate.

Hyperdynamic circulatory syndrome in a mouse model transgenic for SerpinB3

INTRODUCTION AND OBJECTIVES

SerpinB3 is a cysteine protease inhibitor involved in several biological activities. It is progressively expressed in chronic liver disease, but not in normal liver. The role in vascular reactivity of this serpin, belonging to the same family of Angiotensin II, is still unknown. Our aim was to evaluate the in vivo and in vitro effects of SerpinB3 on systemic and splanchnic hemodynamics.

MATERIAL AND METHODS

Different hemodynamic parameters were evaluated by ultrasonography in two colonies of mice (transgenic for human SerpinB3 and C57BL/6J controls) at baseline and after chronic carbon tetrachloride (CCl₄) treatment. In vitro SerpinB3 effect on mesenteric microvessels of 5 Wistar-Kyoto rats was analyzed measuring its direct action on: (a) preconstricted arteries, (b) dose-response curves to phenylephrine, before and after inhibition of angiotensin II type 1 receptors with irbesartan. Hearts of SerpinB3 transgenic mice and of the corresponding controls were also analyzed by morphometric assessment.

RESULTS

In SerpinB3 transgenic mice, cardiac output (51.6±21.5 vs 30.1±10.8ml/min, p=0.003), hepatic artery pulsatility index (0.85±0.13 vs 0.65±0.11, p<0.001) and portal vein blood flow (5.3±3.2 vs 3.1±1.8ml/min, p=0.03) were significantly increased, compared to controls. In vitro, recombinant SerpinB3 had no direct hemodynamic effect on mesenteric arteries, but it increased their sensitivity to phenylephrine-mediated vasoconstriction (p<0.01). This effect was suppressed by inhibiting angiotensin II type-1 receptors.

CONCLUSIONS

In transgenic mice, SerpinB3 is associated with a hyperdynamic circulatory syndrome-like pattern, possibly mediated by angiotensin receptors.

Metabolic Hallmarks of Hepatic Stellate Cells in Liver Fibrosis

Liver fibrosis is a regenerative process that occurs after injury. It is characterized by the deposition of connective tissue by specialized fibroblasts and concomitant proliferative responses. Chronic damage that stimulates fibrogenic processes in the long-term may result in the deposition of excess matrix tissue and impairment of liver functions. End-stage fibrosis is referred to as cirrhosis and predisposes strongly to the loss of liver functions (decompensation) and hepatocellular carcinoma. Liver fibrosis is a pathology common to a number of different chronic liver diseases, including alcoholic liver disease, non-alcoholic fatty liver disease, and viral hepatitis. The predominant cell type responsible for fibrogenesis is hepatic stellate cells (HSCs). In response to inflammatory stimuli or hepatocyte death, HSCs undergo trans-differentiation to myofibroblast-like cells. Recent evidence shows that metabolic alterations in HSCs are important for the trans-differentiation process and thus offer new possibilities for therapeutic interventions. The aim of this review is to summarize current knowledge of the metabolic changes that occur during HSC activation with a particular focus on the retinol and lipid metabolism, the central carbon metabolism, and associated redox or stress-related signaling pathways.

Hepatitis C Virus Downregulates Core Subunits of Oxidative Phosphorylation, Reminiscent of the Warburg Effect in Cancer Cells

Hepatitis C Virus (HCV) mainly infects liver hepatocytes and replicates its single-stranded plus strand RNA genome exclusively in the cytoplasm. Viral proteins and RNA interfere with the host cell immune response, allowing the virus to continue replication. Therefore, in about 70% of cases, the viral infection cannot be cleared by the immune system, but a chronic infection is established, often resulting in liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Induction of cancer in the host cells can be regarded to provide further advantages for ongoing virus replication. One adaptation in cancer cells is the enhancement of cellular carbohydrate flux in glycolysis with a reduction of the activity of the citric acid cycle and aerobic oxidative phosphorylation. To this end, HCV downregulates the expression of mitochondrial oxidative phosphorylation complex core subunits quite early after infection. This so-called aerobic glycolysis is known as the “Warburg Effect” and serves to provide more anabolic metabolites upstream of the citric acid cycle, such as amino acids, pentoses and NADPH for cancer cell growth. In addition, HCV deregulates signaling pathways like those of TNF-β and MAPK by direct and indirect mechanisms, which can lead to fibrosis and HCC.

Golgi Apparatus-Targeted Chondroitin-Modified Nanomicelles Suppress Hepatic Stellate Cell Activation for the Management of Liver Fibrosis

Liver fibrosis is a serious liver disease associated with high morbidity and mortality. The activation of hepatic stellate cells (HSCs) and the overproduction of extracellular matrix proteins are key features during disease progression. In this work, chondroitin sulfate nanomicelles (CSmicelles) were developed as a delivery system targeting HSCs for the treatment of liver fibrosis. CS-deoxycholic acid conjugates (CS-DOCA) were synthesized via amide bond formation. Next, retinoic acid (RA) and doxorubicin (DOX) were encapsulated into CSmicells to afford a DOX+RA-CSmicelles codelivery system. CSmicelles were selectively taken up in activated HSCs and hepatoma (HepG2) cells other than in normal hepatocytes (LO2), the internalization of which was proven to be mediated by CD44 receptors. Interestingly, DOX+RA-CSmicelles preferentially accumulated in the Golgi apparatus, destroyed the Golgi structure, and ultimately downregulated collagen I production. Following tail-vein injection, DOX+RA-CSmicelles were delivered to the cirrhotic liver and showed synergistic antifibrosis effects in the CCl₄-induced fibrotic rat model. Further, immunofluorescence staining of dissected liver tissues revealed CD44-specific delivery of CS derivatives to activated HSCs. Together, our results demonstrate the great potential of CS based carrier systems for the targeted treatment of chronic liver diseases.

Cilostazol protects rats against alcohol-induced hepatic fibrosis via suppression of TGF-β1/CTGF activation and the cAMP/Epac1 pathway

Alcohol abuse and chronic alcohol consumption are major causes of alcoholic liver disease worldwide, particularly alcohol-induced hepatic fibrosis (AHF). Liver fibrosis is an important public health concern because of its high morbidity and mortality. The present study examined the mechanisms and effects of the phosphodiesterase III inhibitor cilostazol on AHF. Rats received alcohol infusions via gavage to induce liver fibrosis and were treated with colchicine (positive control) or cilostazol. The serum alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activities and the albumin/globulin (A/G), enzymes and hyaluronic acid (HA), type III precollagen (PC III), laminin (LA), and type IV collagen (IV-C) levels were measured using commercially available kits. α-smooth muscle actin (α-SMA), collagen I and III, transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), adenosine 3',5'-cyclic monophosphate (cAMP) and exchange protein directly activated by cAMP (Epac) 1/2 expression in liver tissue were measured using western blotting. The results demonstrated that cilostazol significantly increased the serum ADH and ALDH activities and decreased the liver hydroxyproline levels. Cilostazol increased the serum A/G ratio and inhibited the total serum protein, enzymes, HA, PCIII, LA and IV-C levels. Western blotting revealed that cilostazol effectively decreased liver α-SMA, collagen I and III, TGF-β1 and CTGF expression. Cilostazol significantly increased the cAMP and Epac1 levels in hepatic tissue. The present study suggests that cilostazol protects rats against AHF via suppression of TGF-β1/CTGF activation and the cAMP/Epac1 pathway.

Live imaging of collagen deposition during experimental hepatic schistosomiasis and recovery: a view on a dynamic process

Hepatic fibrosis is the central cause of chronic clinical pathology resulting from infection by the blood flukes Schistosoma japonicum or S. mansoni. Much has been elucidated regarding the molecular, cellular and immunological responses that correspond to the formation of the granulomatous response to trapped schistosome eggs. A central feature of this Th2 response is the deposition of collagen around the periphery of the granuloma. To date, traditional histology and transcriptional methods have been used to quantify the deposition of collagen and to monitor the formation of the hepatic granuloma during experimental animal models of schistosomiasis. We have investigated the dynamic nature of granuloma formation through the use of a transgenic mouse model (B6.Collagen 1(A) luciferase mice (B6.Coll 1A-luc⁺)). With this model and whole-animal bioluminescence imaging, we followed the deposition of collagen during an active schistosome infection with Chinese and Philippines geographical strains of S. japonicum and after clearance of the adult parasites by the drug praziquantel. Individual mice were re-imaged over the time course to provide robust real-time quantitation of the development of chronic fibrotic disease. This model provides an improved method to follow the course of hepatic schistosomiasis-induced hepatic pathology and effectively supports the current dogma of the formation of hepatic fibrosis, originally elucidated from static traditional histology. This study demonstrates the first use of the B6.Coll 1A-luc⁺ mouse to monitor the dynamics of disease development and the treatment of pathogen-induced infection with the underlying pathology of fibrosis.

In vitro inhibition of hepatic stellate cell activation by the autophagy-related lipid droplet protein ATG2A

Clinical studies have found that moderate intake of retinol or oleic acid can enlarge the lipid droplets of hepatic stellate cells and suppress their activation. However, the link between lipid droplets and cell activation is unknown. This study compared the dynamics of lipid droplet-associated protein expression between activated and reverted stellate cells. Reversion of the activated human stellate cell line LX-2 and inhibition of primary mouse stellate cell activation were induced by retinol or oleic acid, which resulted in larger lipid droplets and the downregulation of cell activation markers. Quantitative proteomics and immunoblotting were performed to compare lipid-droplet protein profiles between activated and reverted LX-2 cells. Compared to expression in activated cells, 50 lipid-droplet proteins were upregulated, whereas 28 were downregulated upon reversion. ATG2A was significantly enriched in lipid droplets of retinol/oleic acid-treated LX-2 cells and quiescent primary stellate cells. Reduced expression of α-SMA, increased expression of perilipin-3, enlarged lipid droplets, and suppression of autophagic flux were observed in ATG2A-deficient LX2 cells. Lipid-droplet protein profile changes during the reversion of activated stellate cells might provide new insights into the molecular mechanisms linking lipid droplets to liver fibrosis. ATG2A could represent a potential new drug target for hepatic fibrosis.

Chinese herbal formula Fuzheng Huayu alleviates CCl4-induced liver fibrosis in rats: a transcriptomic and proteomic analysis

Liver fibrosis is a consequence of chronic liver disease that can progress to liver cirrhosis or even hepatocarcinoma. Fuzheng Huayu (FZHY), a Chinese herbal formula, has been shown to exert anti-fibrotic effects. To better understand the molecular mechanisms underlying the anti-fibrotic effects of FZHY, we analyzed transcriptomic and proteomic combination profiles in CCl₄-induced liver fibrosis in rats, which were treated with extracted FZHY powder (0.35 g·kg^-1·d^-1, ig) for 3 weeks. We showed that FZHY administration significantly improved liver function, alleviated hepatic inflammatory and fibrotic changes, and decreased the hydroxyproline content in the livers of CCl₄-treated rats. When their liver tissues were examined using microarray and iTRAQ, we found 255 differentially expressed genes (fold change ≥1.5, P<0.05) and 499 differentially expressed proteins (fold change ≥1.2, P<0.05) in the FZHY and model groups. Functional annotation with DAVID (The Database for Annotation, Visualization and Integrated Discovery) showed that 15 enriched gene ontology terms, including drug metabolic process, response to extracellular stimulus, response to vitamins, arachidonic acid metabolic process, response to wounding, and oxidation reduction might be involved in the anti-fibrotic effects of FZHY; whereas KEGG pathway analysis revealed that eight enriched pathways, including arachidonic acid metabolism, retinol metabolism, metabolism of xenobiotics by cytochrome P450, and drug metabolism might also be involved. Moreover, the protein-protein interaction network demonstrated that 10 core genes/proteins overlapped, with Ugt2a3, Cyp2b1 and Cyp3a18 in retinol metabolism pathway overlapped to a higher degree. Compared to the model rats, the livers of FZHY-treated rats had significantly higher mRNA and protein expression levels of Ugt2a3, Cyp2b1 and Cyp3a18. Furthermore, the concentration of retinoic acid was significantly higher in the FZHY-treated rats compared with the model rats. The results suggest that the anti-fibrotic effects of FZHY emerge through multiple targets, multiple functions, and multiple pathways, including FZHY-regulated retinol metabolism, xenobiotic metabolism by cytochrome P450, and drug metabolism through up-regulated Ugt2a3, Cyp2b1, and Cyp3a18. These genes may play important anti-fibrotic roles in FZHY-treated rats.

Biochemical Evidence for the Antitumor Potential of Garcinia mangostana Linn. On Diethylnitrosamine-Induced Hepatic Carcinoma

Background

Garcinia mangostana is extensively used in most of the Indian herbal pharmaceuticals and nutraceuticals.

Objective

The objective of this study was to elucidate the underlying biochemical protective mechanism of G. Mangostana Linn. fruit extract (GME) in deterioration of diethylnitrosamine (DEN)-induced hepatic carcinoma (HCC) in rats.

Materials and Methods

The cancer was induced using DEN to the experimental rats and treated with GME (200, 400, and 600 mg/kg) to find its anticancer property. The cancer biomarkers such as alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), hepatic hydroxyl proline, total tissue protein, and tumor necrosis factor-alpha levels were measured using ELISA. The vascular endothelial growth factor expressions were also seen in liver tissues using immunohistochemistry.

Results

In addition, there was a significant increase in serum AFP, CEA, hepatic hydroxylproline, and total tissue protein levels in HCC group versus the negative control group. In contrast, the groups with HCC subjected to either high or low dose of GME elicited significant reduction of AFP, CEA, hepatic hydroxylproline, and increase in total protein in serum compared to the untreated HCC rats. Interestingly, treatment with GME elicited marked improvement in the liver histological feature and downregulation of tumor necrosis factor-alpha levels in HCC groups. GME extract may have chemopreventive benefits by reducing the tumor promoting growth factor levels in HCC-induced group.

Conclusion

To sum up, all findings on curative groups had proved clearly that the GME has anticarcinogenic effect on the development of liver cancer induced by DEN in rats.

SUMMARY

Garcinia mangostana Linn. (GME) may have chemopreventive property by reducing the tumor promoting growth factor and tumor necrosis factor-alpha levels in diethylnitrosamine (DEN)-induced hepatic cancerThe suppression in the levels of cancer biomarkers by GME due to the presence of anticancer phytoconstituentsThe histological studies proved the effective dose of GME against DEN-induced experimental hepatic cancer. Abbreviations used: TNF-α: Tumor necrosis factor-alpha, PBS: Phosphate buffered saline, ROS: Reactive oxygen species, DNA: Deoxyribonucleic acid, GSH: Glutathione, VEGF: Vascular endothelial growth factor.

Supersonic Shear Wave Imaging of the Spleen for Staging of Liver Fibrosis in Rats

The goal of the work described here was to explore the cause of spleen stiffness (SS) in hepatic fibrogenesis and evaluate the value of SS in liver fibrosis (LF) staging. LF was induced with carbon tetrachloride (CCl₄) in rats (n = 40). Supersonic shear wave imaging and contrast-enhanced ultrasound were performed to determine liver stiffness (LS), SS and splenic hemodynamics. SS, LS and free portal pressure exhibited moderate correlations with fibrosis stage (r = 0.744-0.835, p < 0.001). Time-intensity curves of contrast-enhanced ultrasound for the spleen were presented as decreasing peak intensity and slope of decrease, and increasing time to peak. Splenic sinus dilation and congestion were observed on histopathologic analysis. The area under the receiver operating characteristic curve of SS was higher than that of LS for differentiating LF stages 0-2 from stages 3-4 (Z = 2.293, p = 0.02). SS is a reliable diagnostic marker for the assessment of LF in the CCl₄ model, especially for severe fibrosis. Elevated portal pressure is the cause of increasing SS.

Nrf2 activation is required for curcumin to induce lipocyte phenotype in hepatic stellate cells

Hepatic fibrosis is a reversible scarring response that commonly occurs with chronic liver injury. During hepatic fibrogenesis, the major effector hepatic stellate cells (HSCs) become activated, featured by disappeared intracellular lipid droplets, decreased retinoid storage, and dysregulated expression of genes associated with lipid and retinoid metabolism. Compelling evidence suggested that recovery of retinoid droplets could inhibit HSC activation, while the precise molecular basis underlying the phenotypical switch still remained unclear. In this study, curcumin increased the abundance of lipid droplets and content of triglyceride in activated HSCs. In addition, curcumin could concentration-dependently regulate genes associated with lipid and retinoid metabolism. Further, consistent results were obtained from in vivo experiments. Curcumin increased Nrf2 expression and nuclear translocation, and its binding activity to DNA, which might be associated with suppression of Kelch-like ECH-associated protein 1 in HSCs. Of interest was that Nrf2 overexpression plasmids, in contract to Nrf2 siRNA, strengthened the effect of curcumin on induction of lipocyte phenotype. In in vivo system, Nrf2 knockdown mediated by Nrf2 shRNA lentivirus not only accelerated the lipid degradation in HSCs but also promoted the progression of CCl₄-induced hepatic fibrosis in mice. Noteworthily, Nrf2 knockdown abolished the protective effect of curcumin. In conclusion, curcumin could induce lipocyte phenotype of activated HSCs via activating Nrf2. Nrf2 could be a target molecule for antifibrotic strategy.

SerpinB3 Promotes Pro-fibrogenic Responses in Activated Hepatic Stellate Cells

SerpinB3 is a hypoxia- and hypoxia-inducible factor-2α-dependent cystein protease inhibitor that is up-regulated in hepatocellular carcinoma and in parenchymal cells during chronic liver diseases (CLD). SerpinB3 up-regulation in CLD patients has been reported to correlate with the extent of liver fibrosis and the production of transforming growth factor-β1, but the actual role of SerpinB3 in hepatic fibrogenesis is still poorly characterized. In the present study we analyzed the pro-fibrogenic action of SerpinB3 in cell cultures and in two different murine models of liver fibrosis. "In vitro" experiments revealed that SerpinB3 addition to either primary cultures of human activated myofibroblast-like hepatic stellate cells (HSC/MFs) or human stellate cell line (LX2 cells) strongly up-regulated the expression of genes involved in fibrogenesis and promoted oriented migration, but not cell proliferation. Chronic liver injury by CCl4 administration or by feeding a methionine/choline deficient diet to transgenic mice over-expressing human SerpinB3 in hepatocytes confirmed that SerpinB3 over-expression significantly increased the mRNA levels of pro-fibrogenic genes, collagen deposition and αSMA-positive HSC/MFs as compared to wild-type mice, without affecting parenchymal damage. The present study provides for the first time evidence that hepatocyte release of SerpinB3 during CLD can contribute to liver fibrogenesis by acting on HSC/MFs.

Efficacies of rosiglitazone and retinoin on bleomycin-induced pulmonary fibrosis in rats

The present study investigated the intervention efficacies of rosiglitazone (ROS) and retinoin (RET) on bleomycin-induced pulmonary fibrosis in rats. A total of 48 rats were randomly divided into the control group (group C), the model group (group M), the dexamethasone group (group D), the ROS group (group R), the RET group (group W) and the ROS + RET group (group L). Group M and the treatment groups were intratracheally injected with 5 mg/kg bleomycin, while group C was injected with saline. The lungs of rats in each group were inspected using high resolution computed tomography (HRCT), lung tissue hematoxylin and eosin staining and Masson staining; furthermore, lung L-hydroxyproline (Hyp) content and the concentration of transforming growth factor β1 (TGF-β1) serum of each group were also determined. The fibrosis score, Hyp content and TGF-β1 concentration of each treatment group were significantly lower when compared with group M (P<0.01), while the imaging results were improved when compared with group M, with lower alveolitis and fibrosis scores. Group L, R and W exhibited significantly lower fibrosis scores, Hyp content and TGF-β1 concentrations when compared with group D (P<0.05). Imaging results for group L, R and W indicated that while the imaging results were superior to group D, group L was lower than groups R and W (P<0.05). No significant difference in the fibrosis score, Hyp content and TGF-β1 concentration was exhibited between groups R and W (P>0.05). Findings from the present study conclude that ROS and RET are able to suppress bleomycin-induced pulmonary fibrosis with improved efficacies when compared with dexamethasone; furthermore, the combination of these two pharmacological agents may exert synergistic effects.

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

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

Combination Therapy of All-Trans Retinoic Acid With Ursodeoxycholic Acid in Patients With Primary Sclerosing Cholangitis: A Human Pilot Study

GOALS

To perform an exploratory pilot study of all-trans retinoic acid (ATRA) combined with ursodeoxycholic acid (UDCA) in patients with primary sclerosing cholangitis (PSC).

BACKGROUND

PSC is a progressive disorder for which there is no accepted therapy. Studies in human hepatocyte cultures and in animal models of cholestasis indicate that ATRA might have beneficial effects in cholestatic disorders.

STUDY

ATRA (45 mg/m/d, divided and given twice daily) was combined with moderate-dose UDCA in patients with PSC who had incomplete response to UDCA monotherapy. The combination was administered for 12 weeks, followed by a 12-week washout in which patients returned to UDCA monotherapy. We measured alkaline phosphatase (ALP), alanine aminotransferase (ALT), bilirubin, cholesterol, bile acids, and the bile acid intermediate 7α-hydroxy-4-cholesten-3-one (C4) at baseline, week 12, and after washout.

RESULTS

Fifteen patients completed 12 weeks of therapy. The addition of ATRA to UDCA reduced the median serum ALP levels (277±211 to 243±225 U/L, P=0.09) although this, the primary endpoint, did not reach significance. In contrast, median serum ALT (76±55 to 46±32 U/L, P=0.001) and C4 (9.8±19 to 7.9±11 ng/mL, P=0.03) levels significantly decreased. After washout, ALP and C4 levels nonsignificantly increased, whereas ALT levels significantly increased (46±32 to 74±74, P=0.0006), returning to baseline.

CONCLUSIONS

In this human pilot study, the combination of ATRA and UDCA did not achieve the primary endpoint (ALP); however, it significantly reduced ALT and the bile acid intermediate C4. ATRA appears to inhibit bile acid synthesis and reduce markers of inflammation, making it a potential candidate for further study in PSC (NCT 01456468).

How I treat acute myeloid leukemia presenting with preexisting comorbidities

Acute myeloid leukemia (AML) is a devastating disease with an incidence that progressively increases with advancing age. Currently, only ∼40% of younger and 10% of older adults are long-term survivors. If untreated, the overall prognosis of AML remains dismal. Initiation of therapy at diagnosis is usually urgent. Barriers to successful therapy for AML are the attendant toxicities directly related to chemotherapy or those associated with inevitable aplasia. Organ dysfunction often further complicates such toxicities and may even be prohibitive. There are few guidelines to manage such patients and the fear of crossing the medico-legal abyss may dominate. Such clinical scenarios provide particular challenges and require experience for optimal management. Herein, we discuss select examples of common pretreatment comorbidities, including cardiomyopathy, ischemic heart disease; chronic renal failure, with and without dialysis; hepatitis and cirrhosis; chronic pulmonary insufficiency; and cerebral vascular disease. These comorbidities usually render patients ineligible for clinical trials and enormous uncertainty regarding management reigns, often to the point of withholding definitive therapy. The scenarios described herein emphasize that with appropriate subspecialty support, many AML patients with comorbidities can undergo therapy with curative intent and achieve successful long-term outcome.

Fusion protein of retinol-binding protein and albumin domain III reduces liver fibrosis

Activated hepatic stellate cells (HSCs) play a key role in liver fibrosis, and inactivating HSCs has been considered a promising therapeutic approach. We previously showed that albumin and its derivative designed for stellate cell-targeting, retinol-binding protein-albumin domain III fusion protein (referred to as R-III), inactivate cultured HSCs. Here, we investigated the mechanism of action of albumin/R-III in HSCs and examined the anti-fibrotic potential of R-III in vivo. R-III treatment and albumin expression downregulated retinoic acid (RA) signaling which was involved in HSC activation. RA receptor agonist and retinaldehyde dehydrogenase overexpression abolished the anti-fibrotic effect of R-III and albumin, respectively. R-III uptake into cultured HSCs was significantly decreased by siRNA-STRA6, and injected R-III was localized predominantly in HSCs in liver. Importantly, R-III administration reduced CCl4- and bile duct ligation-induced liver fibrosis. R-III also exhibited a preventive effect against CCl4-inducd liver fibrosis. These findings suggest that the anti-fibrotic effect of albumin/R-III is, at least in part, mediated by downregulation of RA signaling and that R-III is a good candidate as a novel anti-fibrotic drug.

Deregulation of energy metabolism promotes antifibrotic effects in human hepatic stellate cells and prevents liver fibrosis in a mouse model

Liver fibrosis and cirrhosis result from uncontrolled secretion and accumulation of extracellular matrix (ECM) proteins by hepatic stellate cells (HSCs) that are activated by liver injury and inflammation. Despite the progress in understanding the biology liver fibrogenesis and the identification of potential targets for treating fibrosis, development of an effective therapy remains elusive. Since an uninterrupted supply of intracellular energy is critical for the activated-HSCs to maintain constant synthesis and secretion of ECM, we hypothesized that interfering with energy metabolism could affect ECM secretion. Here we report that a sublethal dose of the energy blocker, 3-bromopyruvate (3-BrPA) facilitates phenotypic alteration of activated LX-2 (a human hepatic stellate cell line), into a less-active form. This treatment-dependent reversal of activated-LX2 cells was evidenced by a reduction in α-smooth muscle actin (α-SMA) and collagen secretion, and an increase in activity of matrix metalloproteases. Mechanistically, 3-BrPA-dependent antifibrotic effects involved down-regulation of the mitochondrial metabolic enzyme, ATP5E, and up-regulation of glycolysis, as evident by elevated levels of lactate dehydrogenase, lactate production and its transporter, MCT4. Finally, the antifibrotic effects of 3-BrPA were validated in vivo in a mouse model of carbon tetrachloride-induced liver fibrosis. Results from histopathology & histochemical staining for collagen and α-SMA substantiated that 3-BrPA promotes antifibrotic effects in vivo. Taken together, our data indicate that sublethal, metronomic treatment with 3-BrPA blocks the progression of liver fibrosis suggesting its potential as a novel therapeutic for treating liver fibrosis.

An in vitro model for the pro-fibrotic effects of retinoids: mechanisms of action

BACKGROUND AND PURPOSE

Retinoids, including all-trans retinoic acid (tRA), have dose-dependent pro-fibrotic effects in experimental kidney diseases. To understand and eventually prevent such adverse effects, it is important to establish relevant in vitro models and unravel their mechanisms.

EXPERIMENTAL APPROACH

Fibrogenic effects of retinoids were assessed in NRK-49F renal fibroblasts using picro-Sirius red staining for collagens and quantified by spectrophotometric analysis of the eluted stain. Other methods included RT-qPCR, immunoassays and matrix metalloproteinase (MMP) activity assays.

KEY RESULTS

With or without TGF-β1, tRA was dose-dependently pro-fibrotic, notably increasing collagen accumulation. tRA and TGF-β1 additively suppressed expression of mRNA for MMP2, 3 and 13 and suppressed MMP activity. tRA, in the presence of TGF-β1, induced plasminogen activator inhibitor-1 (PAI-1) mRNA and they additively induced PAI-1 protein expression. A PAI-1 inhibitor, a pan-retinoic acid receptor (RAR) antagonist and a pan-retinoid X receptor (RXR) antagonist each partially prevented the pro-fibrotic effect of tRA. The dose-dependent pro-fibrotic effects of a pan-RXR agonist were similar to those of tRA. A pan-RAR agonist showed weaker, less dose-dependent pro-fibrotic effects and the pro-fibrotic effects of RARα and RARβ-selective agonists were even smaller. An RARγ-selective agonist did not affect fibrogenesis.

CONCLUSIONS AND IMPLICATIONS

An in vitro model for the pro-fibrotic effects of retinoids was established in NRK-49F cells. It was associated with reduced MMP activity and increased PAI-1 expression, and was probably mediated by RXR and RAR. To avoid or antagonize the pro-fibrotic activity of tRA, further studies on RAR isotype-selective agonists and PAI-1 inhibitors might be of value.

Retinoic acid inhibits pancreatic cancer cell migration and EMT through the downregulation of IL-6 in cancer associated fibroblast cells

Retinoic acid (RA) is a small molecular derivative of vitamin A that is stored in quiescent stellate cells in pancreas stroma. Cancer associated fibroblasts (CAFs) are activated fibroblast cells in pancreatic ductal adenocarcinoma tumor microenvironment. We treated CAFs with RA and found that these cells became static due to the low expression of α-SMA, FAP, and IL-6 and decreased production of extracellular matrix (ECM). Furthermore, we verified that the low secretion of IL-6 from CAFs was related to RA-induced inhibition of migration and epithelial-mesenchymal transition (EMT) of tumor cells. However, RA could not inhibit the migration and EMT of tumor cells directly. Therefore, our study showed that one of the therapeutic effects of RA on tumor cells is through its modulation of CAFs in tumor microenvironment. The tumor microenvironment plays an important role in promoting tumor migration and might be a promising target of biological treatment.

The controversial role of retinoic acid in fibrotic diseases: analysis of involved signaling pathways

Fibrotic diseases, such as liver, pulmonary and renal fibrosis, are common end-stage conditions and represent a major global health problem. Furthermore, effective therapeutic measures are presently unavailable. Extracellular matrix accumulation is the most prominent characteristic in the pathogenesis of fibrotic disease. Retinoic acid, including all-trans retinoic acid, 9-cis and 13-cis retinoic acid, play important roles in various physiological processes, such as in embryonic development, reproduction, vision, cell growth, differentiation, apoptosis and inflammation. Present studies report that retinoic acid treatment may affect various processes involved in the onset and progression of fibrotic disease. However, the therapeutic effects of retinoic acid in such diseases remain controversial. Several reports indicate that retinoic acid positively affects the progression of fibrosis and alleviates the accumulation of the extracellular matrix, whereas other studies report the opposite; that retinoic acid exacerbates fibrosis and induces extracellular matrix accumulation. Signaling pathways might be an important influencing factor and differences in signaling events might be responsible for the contradictory role of retinoic acid in fibrotic diseases. Since there was no review available that investigated the role of retinoic acid and the signaling pathways involved, we retrospectively studied the literature and provide a comprehensive analysis of retinoic acid’s role in fibrotic diseases, and provide an overview of the signal transduction pathways involved in its pathogenesis.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

The interaction between HCV and nuclear receptor-mediated pathways

Hepatitis C virus (HCV) is presently the leading indication for liver transplantation in Western countries. Treatment for HCV infection includes a combination of pegylated interferon and ribavirin, which produces highly variable response rates. This reflects the lack of information regarding the roles of host and viral components during viral pathogenesis. Vital processes regulated by the liver, including metabolism, lipid homeostasis, cellular proliferation, and the immune response, are known to be systematically dysregulated as a result of persistent HCV infection. Nuclear receptors and their ligands are recognized as indispensable regulators of liver homeostasis. Pathways mediated by the nuclear receptor superfamily have been shown to be profoundly disrupted during HCV infection, leading to an increased importance in elucidating the exact nature of this complex relationship. Expanded understanding of the role of nuclear receptors in HCV infection may therefore be an essential step in the search for a more universally effective treatment.

Induction of lipocalin-2 expression in acute and chronic experimental liver injury moderated by pro-inflammatory cytokines interleukin-1β through nuclear factor-κB activation

BACKGROUND

Lipocalin-2 (LCN2) belongs to the lipocalin superfamily, sharing a barrel-shaped tertiary structure with a hydrophobic pocket and an ability to bind lipophilic molecules. LCN2 has recently emerged as an important modulator of cellular homeostasis in several organs, i.e. heart, lung and kidney, but little is known about the expression of LCN2 in acute and chronic liver injury.

AIMS

In this study, we wanted to analyse the expression and regulation of LCN2 in models of acute and chronic experimental liver injury.

MATERIALS AND METHODS

We analysed LCN2 expression in livers of rats subjected to bile duct ligation or repeated doses of carbon tetrachloride and tested the impact of various pro-inflammatory cytokines in cultured primary liver cells.

RESULTS

By using primary cultures of hepatic stellate cells and hepatocytes isolated from normal and injured rat livers, we found a significant LCN2 expression in early hepatic stellate cell cultures, a lower expression in fully transdifferentiated myofibroblasts and no expression in freshly isolated hepatocytes. However, LCN2 expression and secretion in hepatocytes increased dramatically during culturing. In addition, chronic in vivo liver injury resulting from both bile duct ligation and repeated application of carbon tetrachloride resulted in rapid and well-sustained induction of LCN2 expression. Immunohistochemistry and primary liver cell isolation identified injured hepatocytes as the main source of LCN2 production. LCN2 is strongly induced in both primary hepatocytes and immortalized hepatocellular carcinoma cell line HepG2 by the pro-inflammatory cytokine interleukin-1β via nuclear factor-κB activation, but not by the profibrotic cytokines platelet-derived growth factor and transforming growth factor-β.

CONCLUSION

LCN2 expression shows clear correlation to liver damage and resulting inflammatory responses, rather than to the degree of liver fibrosis, which in fact may imply a distinct diagnostic value as an early biomarker of liver inflammation.

Leptospira santorosai Serovar Shermani detergent extract induces an increase in fibronectin production through a Toll-like receptor 2-mediated pathway

Leptospirosis can activate inflammatory responses through Toll-like receptors (TLRs) and may cause renal tubulointerstitial fibrosis characterized by the accumulation of extracellular matrix (ECM). We have previously demonstrated that Leptospira santorosai serovar Shermani detergent extract stimulates ECM accumulation in vitro. The aim of this study was to examine the mechanistic basis of these previous observations and, in particular, to examine the potential involvement of TLRs. The addition of serovar Shermani detergent extract led to an increase in fibronectin gene expression and production. Inhibition of TLR2 but not TLR4 expression abrogated serovar Shermani detergent extract-mediated increases in fibronectin production. This response was also blocked by the knockdown of the gene expression of the TLR2 downstream transducers myeloid differentiation factor 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6). Serovar Shermani detergent extract also activated nuclear factor-κB, and its inhibition by curcumin-attenuated serovar Shermani detergent extract induced increases in fibronectin production. These effects were also mimicked by the specific TLR2 agonist, Pam(3)CsK(4), a response that was also abrogated by the knockdown of MyD88 and TRAF6. Similarly, the administration of live leptospires to cells also induced fibronectin production that was blocked by inhibition of TLR2 and MyD88 expression. In conclusion, serovar Shermani detergent extract can induce fibronectin production through the TLR2-associated cascade, providing evidence of an association between TLRs and leptospirosis-mediated ECM deposition.

Hepatoprotection by carotenoids in isoniazid–rifampicin induced hepatic injury in rats

This study evaluates the hepatoprotective effect of carotenoids against isoniazid (INH) and rifampicin (RIF). Thirty-six adult rats were divided into the following 4 groups: (1) control group treated with normal saline; (2) INH + RIF group treated with 50 mg·(kg body mass)–1·day–1 of INH and RIF each; (3) INH + RIF+ carotenoids group treated with 50 mg·(kg body mass)–1·day–1 of INH and RIF each and 10 mg·(kg body mass)–1·day–1 of carotenoids; and (4) carotenoids group treated with 10 mg·(kg body mass)–1·day–1 of carotenoids for 28 days intragastrically. Oxidative stress and antioxidant levels in liver and blood, liver histology and change in transaminases were measured in all the above-mentioned groups. There was an increase in lipid peroxidation with a reduction in thiols, catalase, and superoxide dismutase (SOD) in the liver and blood of rats accompanied by an increase in transaminases, bilirubin, and alkaline phosphatase. Treatment with carotenoids along with INH + RIF partially reversed lipid peroxidation, thiols, catalase, and SOD in the liver and blood of rats. Elevated levels of the enzymes in serum were also reversed partially by this treatment. The degree of necrosis, portal triaditis, and inflammation were also lowered in the carotenoids group. In conclusion, carotenoids supplementation in INH + RIF treated rats showed partial protection.

Mesenchymal stem cell infusion therapy in a carbon tetrachloride-induced liver fibrosis model affects matrix metalloproteinase expression

In order to investigate the effects of bone marrow-derived MSCs (mesenchymal stem cells) in reversing liver fibrosis and to determine their possible mechanism of action, mouse MSCs were infused into the tail vein of a CCl(4) injection mouse chronic model. MSCs caused a decrease in liver fibrosis histopathologically, 4 weeks after transplantation. The reduction in liver collagen was confirmed by quantitative analysis. Moreover, lipid peroxidation in the CCl(4)/MSC group decreased significantly. Quantitative RT (reverse transcription)-PCR analysis showed administration of MSCs has a significant antifibrotic effect as evidenced by the decrease in expression of liver collagen and increase in MMP13 (matrix metalloproteinase 13) in the CCl(4)/MSC group when compared with the CCl(4) group, 4 weeks after transplantation. The expression of alphaSMA (smooth muscle actin) and TIMP1 was also down-regulated in the CCl(4)/MSC group. Additionally, the expression of MMP9 was significantly up-regulated in the CCl(4)-treated group; however, there was no significant change after MSC injection. Few engrafted cells in the recipient liver and were able to differentiate into albumin-positive cells. In conclusion, MSCs can enhance recovery of a CCl(4)-injured mouse liver through their influence in reducing collagen deposition by possibly affecting expression of MMPs.

Vitamin A deficiency injures liver parenchyma and alters the expression of hepatic extracellular matrix

Vitamin A is an essential lipid-soluble nutrient that is crucial for morphogenesis and adult tissue maintenance. The retinoid homeostasis in the liver depends on a regular supply of vitamin A from an adequate dietary intake to preserve the normal organ structure and functions. This study focuses on the effect of vitamin A deficiency on the morphology and extracellular proteins expression of the liver in adult Wistar rats. Animals were fed with a normal (control group) or deficient vitamin A diet for 3 months. At the end of the experimental period, histological examination of the livers under light and electron microscopy revealed that vitamin A deficiency produced a loss of hepatocyte cord disposition with an irregular parenchymal organization. Abundant fat droplets were present in the cytoplasm of the hepatocytes. Elongated myofibroblastic-like cells with an irregular cytoplasmic process and without lipid droplets could be seen at the perisinusoidal space, where an elevated intensity of alpha smooth muscle actin (alpha-SMA) was observed. These results suggest that an activation of hepatic stellate cells (HSCs) occurred. Moreover, immunochemical methods revealed that vitamin A deficiency led to an increased expression of hepatic fibronectin, laminin and collagen type IV. We propose that vitamin A deprivation caused liver injury and that HSCs underwent a process of activation in which they produced alpha-SMA and synthesized extracellular components. These changes may be a factor predisposing to liver fibrosis. In consequence, vitamin A deprivation could affect human and animal health.

p38-MAPK- and caspase-3-mediated superoxide-induced apoptosis of rat hepatic stellate cells: reversal by retinoic acid

Reactive oxygen species (ROS) activate retinoid-containing quiescent hepatic stellate cells (qHSCs) to retinoid-deficient fibrogenic myofibroblast-like cells (aHSCs). However, ROS also cause apoptosis of aHSCs, and apoptotic aHSCs are observed in inflammatory fibrotic liver. Here, we investigated mechanisms of the effects of oxidative stress on the survival of qHSCs and aHSCs. HSCs from normal rat liver were used after overnight culture (qHSCs), or in 3-5 passages (aHSCs). For in vivo induction of oxidative stress, tert-butylhydroperoxide was injected into control and CCl4-induced cirrhotic rats. Spontaneous caspase-3 activation and apoptosis, observed in cultured qHSCs, decreased with time and were unaffected by superoxide. In contrast, superoxide caused caspase-3 and p38-MAPK activation, reduction in Bcl-xL expression, and apoptosis in aHSCs. Inhibition of caspase-3 and p38-MAPK did not affect the viability of qHSCs in the absence or presence of superoxide, but inhibited superoxide-induced death of aHSCs. Glutathione (GSH) level and activities of superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were lower in aHSCs than qHSCs. Superoxide increased GSH content, and activities of SOD, catalase and GPx in qHSCs but not in aHSCs. Incubation of 13-cis-retinoic acid (RA)-treated aHSCs with superoxide increased their GSH content significantly, and prevented superoxide-induced p38-MAPK and caspase-3 activation while dramatically reducing the extent of apoptosis. Finally, oxidative stress induced in vivo caused apoptosis of aHSCs in cirrhotic but not of qHSCs in control rats. These results suggest that the absence of retinoids render aHSCs susceptible to superoxide-induced apoptosis via caspase-3 and p38-MAPK activation.