Beneficial effects of hepatic cyclooxygenase-2 expression against cholestatic injury after common bile duct ligation in mice.

BACKGROUND AND AIMS: Cyclooxygenase-2 (COX-2) is involved in different liver diseases, but little is known about the significance of COX-2 in cholestatic injury. This study was designed to elucidate the role of COX-2 expression in hepatocytes during the pathogenesis of obstructive cholestasis. METHODS: We used genetically modified mice constitutively expressing human COX-2 in hepatocytes. Transgenic mice (hCOX-2-Tg) and their wild-type (Wt) littermates were either subjected to a mid-abdominal laparotomy or common bile duct ligation (BDL) for 2 or 5 days. Then, we explored the mechanisms underlying the role of COX-2 and its derived prostaglandins in liver function, and the synthesis and excretion of bile acids (BA) in response to cholestatic liver injury. RESULTS: After BDL, hCOX-2-Tg mice showed lower grades of hepatic necrosis and inflammation than Wt mice, in part by a reduced hepatic neutrophil recruitment associated with lower mRNA levels of pro-inflammatory cytokines. Furthermore, hCOX-2-Tg mice displayed a differential metabolic pattern of BA synthesis that led to an improved clearance after BDL-induced accumulation. In addition, an enhanced response to the BDL-induced oxidative stress and hepatic apoptosis was observed. In vitro experiments using hepatic cells that stably express hCOX-2 confirmed the cytoprotective role of prostaglandin E2 against BA toxicity. CONCLUSIONS: Taken together, our data indicate that constitutive expression of COX-2 in hepatocytes ameliorates cholestatic liver injury in mice by reducing inflammation and cell damage and by modulating BA metabolism, pointing to a role for COX-2 as a defensive response against cholestasis-derived BA accumulation and injury.

Circular RNA Tmcc1 improves astrocytic glutamate metabolism and spatial memory via NF-κB and CREB signaling in a bile duct ligation mouse model: transcriptional and cellular analyses.

BACKGROUND: Hepatic encephalopathy-induced hyperammonemia alters astrocytic glutamate metabolism in the brain, which is involved in cognitive decline. To identify specific therapeutic strategies for the treatment of hepatic encephalopathy, various molecular signaling studies, such as non-coding RNA functional study, have been conducted. However, despite several reports of circular RNAs (circRNAs) in the brain, few studies of circRNAs in hepatic encephalopathy-induced neuropathophysiological diseases have been conducted. METHODS: In this study, we performed RNA sequencing to identify whether the candidate circRNA cirTmcc1 is specifically expressed in the brain cortex in a bile duct ligation (BDL) mouse model of hepatic encephalopathy. RESULTS: Based on transcriptional and cellular analysis, we investigated the circTmcc1-dysregulation-induced changes in the expression of several genes that are associated with intracellular metabolism and astrocyte function. We found that the circTmcc1 binds with the NF-κB p65-CREB transcriptional complex and regulates the expression of the astrocyte transporter EAAT2. Furthermore, circTmcc1 contributed to the secretion of proinflammatory mediators and glutamate metabolism in astrocytes and subsequently modulated an improvement in spatial memory by mediating neuronal synaptic plasticity. CONCLUSIONS: Thus, circTmcc1 may be a promising circRNA candidate for targeted interventions to prevent and treat the neuropathophysiological complications that occur due to hepatic encephalopathy.

The effect of crocin on cholestasis-induced spatial memory impairment with respect to the expression level of TFAM and PGC-1α and activity of catalase and superoxide dismutase in the hippocampus.

Large evidence has shown that cholestasis has a wide-range of deleterious effects on brain function, and also, on neurocognitive functions including learning and memory. On the other hand, crocin (derived from Crocus sativus) is a medicinal natural compound that induces neuroprotective and precognitive effects. In this study, we aimed to evaluate the effect of crocin on spatial learning and memory in cholestatic rats with respect to the level of mitochondrial transcriptional factor A (TFAM), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), catalase (CAT), and superoxide dismutase (SOD) in the hippocampus of male Wistar rats. Bile duct ligation (BDL) was used to induce cholestasis. Y-maze apparatus was used to assess spatial memory performance and real-time PCR was used to assess TFAM and PGC-1α gene expression. Also, crocin was injected intraperitoneal at the doses of 15, 20, and 30 mg/kg for thirty days. The results showed that BDL impaired spatial memory in rats. BDL also decreased SOD, TFAM, and PGC-1α level. In addition, crocin partially reversed the impairment effect of BDL on spatial memory. Crocin (30 mg/kg) also reversed the effect of BDL on SOD, TFAM, and PGC-1α. Of note, the effect of BDL on CAT activity was controversial. It seems that BDL can increase CAT activity. In addition, crocin (30 mg/kg) reversed the enhancement of CAT following BDL to its control level. In conclusion, crocin may induce a significant neuroprotective effect on cholestasis-induced memory impairment.

Electroacupuncture Ameliorates Intestinal Barrier Destruction in Mice With Bile Duct Ligation-Induced Liver Injury by Activating the Cholinergic Anti-Inflammatory Pathway.

OBJECTIVES: Electroacupuncture (EA) at Zusanli (ST36) can attenuate inflammation in different rodent models. However, the therapeutic mechanisms underlying its action in inhibiting intestinal barrier destruction and liver injury in cholestasis mice have not been clarified. This study aimed at investigating whether EA at ST36 could activate the cholinergic anti-inflammatory pathway to inhibit intestinal barrier destruction and liver injury in cholestasis mice. MATERIALS AND METHODS: Male Hmox1floxp/floxp C57BL/6 mice were randomized and subjected to a sham or bile duct ligation (BDL) surgery. The BDL mice were randomized and treated with, or without (BDL group), sham EA at ST36 (BDL+sham-ST36) or EA at ST36 (BDL+ST36), or received α-bungarotoxin (α-BGT), a specific inhibitor of nicotinic acetylcholine receptor α7 subunit (α7nAChR), before stimulation (BDL+ST36+α-BGT). These mice, together with a group of intestine-specific heme oxygenase-1 (HO-1) knockout (KO) Villin-Cre-HO-1-/- mice, were monitored for their body weights before and 14 days after BDL. The levels of plasma cytokines and liver injury-related alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by enzyme-linked immunoassay, and pathological changes in the intestinal mucosa and liver fibrosis as well as intestinal barrier permeability in individual mice were examined by histology and immunohistochemistry. The levels of α7nAChR, HO-1, ZO-1, Occludin, Claudin-1, and NF-κBp65 expression and NF-κBp65 phosphorylation in intestinal tissues were quantified. RESULTS: Compared with the sham group, BDL significantly increased the levels of plasma interleukin (IL)-1ß, IL-6, IL-10, tumor necrosis factor α, ALT, and AST and caused intestinal mucosal damages, high permeability, and liver fibrosis in mice, which were remarkably mitigated, except for further increased levels of plasma IL-10 in the BDL+ST36 group of mice. Similarly, EA at ST36 significantly up-regulated α7nAChR and HO-1 expression; mitigated the BDL-decreased ZO-1, Occludin, and Claudin-1 expression; and attenuated the BDL-increased NF-κBp65 phosphorylation in intestinal tissues of mice. The therapeutic effects of EA at ST36 were significantly abrogated by pretreatment with α-BGT or HO-1 KO. CONCLUSION: EA at ST36 inhibits the BDL-induced intestinal mucosal damage and liver fibrosis by activating the HO-1 cholinergic anti-inflammatory pathway in intestinal tissues of mice.

Transcriptome Profile in the Mouse Brain of Hepatic Encephalopathy and Alzheimer's Disease.

Hepatic encephalopathy (HE) is a chronic metabolic disease accompanied by neuropathological and neuropsychiatric features, including memory deficits, psychomotor dysfunction, depression, and anxiety. Alzheimer's disease (AD), the most common neurodegenerative disease, is characterized by tau hyperphosphorylation, excessive amyloid beta (Aß) accumulation, the formation of fibrillary tangles, hippocampus atrophy, and neuroinflammation. Recent studies have suggested a positive correlation between HE and AD. Some studies reported that an impaired cholesterol pathway, abnormal bile acid secretion, excessive ammonia level, impaired Aß clearance, astrocytic dysfunction, and abnormal γ-aminobutyric acid GABAergic neuronal signaling in HE may also be involved in AD pathology. However, the mechanisms and related genes involved in AD-like pathology in the HE brain are unclear. Thus, we compared the cortical transcriptome profile between an HE mouse model, bile duct ligation (BDL), and an AD mouse model, the 5×FAD. Our study showed that the expression of many genes implicated in HE is associated with neuronal dysfunction in AD mice. We found changes in various protein-coding RNAs, implicated in synapses, neurogenesis, neuron projection, neuron differentiation, and neurite outgrowth, and non-coding RNAs possibly associated with neuropathology. Our data provide an important resource for further studies to elucidate AD-like pathophysiology in HE patients.

Transcriptome Profile of Thyroid Glands in Bile Duct Ligation Mouse Model.

Thyroid hormone (TH) contributes to multiple cellular mechanisms in the liver, muscle cells, adipose tissue, and brain, etc. In particular, the liver is an important organ in TH metabolism for the conversion of thyronine (T4) into triiodothyronine (T3) by the deiodinase enzyme. TH levels were significantly decreased and thyroid-stimulating hormone (TSH) levels were significantly increased in patients with liver failure compared with normal subjects. Among liver failure diseases, hepatic encephalopathy (HE) deserves more attention because liver damage and neuropathologies occur simultaneously. Although there is numerous evidence of TH dysregulation in the HE model, specific mechanisms and genetic features of the thyroid glands in the HE model are not fully understood. Here, we investigated the significantly different genes in the thyroid glands of a bile duct ligation (BDL) mouse model as the HE model, compared to the thyroid glands of the control mouse using RNA sequencing. We also confirmed the alteration in mRNA levels of thyroid gland function-related genes in the BDL mouse model. Furthermore, we evaluated the increased level of free T4 and TSH in the BDL mouse blood. Thus, we emphasize the potential roles of TH in liver metabolism and suggest that thyroid dysfunction-related genes in the HE model should be highlighted for finding the appropriate solution for an impaired thyroid system in HE.

Superior Efficacy of a Bedaquiline, Delamanid, and Linezolid Combination Regimen in a Mouse Tuberculosis Model.

BACKGROUND: The treatment success rate of drug-resistant (DR) tuberculosis is alarmingly low. Therefore, more effective and less complex regimens are urgently required. METHODS: We compared the efficacy of an all oral DR tuberculosis drug regimen consisting of bedaquiline (25 mg/kg), delamanid (2.5 mg/kg), and linezolid (100 mg/kg) (BDL) on the mycobacterial load in the lungs and spleen of tuberculosis-infected mice during a treatment period of 24 weeks. This treatment was compared with the standard regimen of isoniazid, rifampicin, pyrazinamide, and ethambutol (HRZE). Relapse was assessed 12 weeks after treatment. Two logistic regression models were developed to compare the efficacy of both regimens. RESULTS: Culture negativity in the lungs was achieved at 8 and 20 weeks of treatment with BDL and HRZE, respectively. After 14 weeks of treatment only 1 mouse had relapse in the BDL group, while in the HRZE group relapse was still observed at 24 weeks of treatment. Predictions from the final mathematical models showed that a 95% cure rate was reached after 20.5 and 28.5 weeks of treatment with BDL and HRZE, respectively. CONCLUSION: The BDL regimen was observed to be more effective than HRZE and could be a valuable option for the treatment of DR tuberculosis.

RIP3 deficiency alleviates liver fibrosis by inhibiting ROCK1-TLR4-NF-κB pathway in macrophages.

Liver fibrosis is an important pathologic process in injured liver tissues. A protein kinase, receptor-interacting protein (RIP)3, plays a crucial role in mediating different diseases. However, the role of RIP3 in macrophages in liver fibrosis has not yet been studied. In our study, we found that RIP3 expression was up-regulated in liver tissues and macrophages of humans and mice with liver fibrosis. Absence of RIP3 in macrophages could alleviate inflammation and macrophage or neutrophil accumulation in mice after carbon tetrachloride (CCl4) or bile duct ligation (BDL) treatment. Importantly, RIP3 deficiency in macrophages could decrease CCl4-induced and BDL-induced liver fibrosis in mice. Moreover, RIP3 deficiency could inhibit the TLR4-NF-κB pathway through suppressing Rho-associated coiled-coil containing protein kinase (ROCK)1 in macrophages. To explore the connection of ROCK1 and RIP3 in macrophages of mice with liver fibrosis in vivo, ROCK1-overexpressed macrophages were infused to RIP3-deficient mice, which resulted in increased inflammation and liver fibrosis. In conclusion, our findings suggest that RIP3 plays a crucial proinflammatory role in liver fibrosis by regulating the ROCK1-TLR4-NF-κB signaling pathway in macrophages and therefore may be a potential therapeutic target for immune-mediated liver fibrosis.-Wei, S., Zhou, H., Wang, Q., Zhou, S., Li, C., Liu, R., Qiu, J., Shi, C., Lu, L. RIP3 deficiency alleviates liver fibrosis by inhibiting ROCK1-TLR4-NF-κB pathway in macrophages.

Vitamin D3 abates BDL-induced cholestasis and fibrosis in rats via regulating Hedgehog pathway.

Liver cholestasis is a complex disease of broad etiologies. Hedgehog (Hh) signaling has been shown to play a pivotal role in modulating liver repair post cholestatic liver injury. We here investigated the role of vitamin D in experimental liver cholestasis induced by bile-duct ligation (BDL) in rats. Male Sprague Dawley rats underwent BDL surgery and two weeks post-surgery; vitamin D was administered daily for two weeks. Serum markers of hepatocellular integrity were measured and fibrosis was detected by measuring α-SMA and hepatic TGF-ß1 as well as hepatic collagen content. Hh signaling was evaluated by measuring Smo and Gli1 levels. Histopathological examination of hepatic tissue was performed. Vitamin D alleviated obstructive cholestatic damage as illustrated by total bilirubin as well as gamma glutamyl transferase (γ-GT) serum levels. It also alleviated hepatocellular damage as suggested by reducing elevated serum aminotransferases induced by BDL. Antifibrotic activity of vitamin D was confirmed by decrease in mRNA and protein expression of α-SMA, as well as collagen content in hepatic tissue. Furthermore, vitamin D suppressed BDL-induced elevated hepatic TGF-ß1 mRNA and protein levels. BDL activated Hh signaling and upregulated its upstream component smoothened (Smo) and downstream target gene Gli1. Treatment with vitamin D reduced Smo mRNA levels and suppressed hepatic Gli1 mRNA and protein levels. Molecular docking of vitamin D to Smo revealed that vitamin D binds similarly to its endogenous cholesterol ligand and blocks its activation. These results demonstrate that vitamin D mitigated cholestatic liver injury through inhibiting Hh signaling.

Inactivation of caspase 8 in liver parenchymal cells confers protection against murine obstructive cholestasis.

BACKGROUND & AIMS: Caspase 8 (CASP8) is the apical initiator caspase in death receptor-mediated apoptosis. Strong evidence for a link between death receptor signaling pathways and cholestasis has recently emerged. Herein, we investigated the role of CASP8-dependent and independent pathways during experimental cholestasis. METHODS: Liver injury was characterized in a cohort of human sera (n = 28) and biopsies from patients with stage IV primary biliary cholangitis. In parallel, mice with either specific deletion of Casp8 in liver parenchymal cells (Casp8Δhepa) or hepatocytes (Casp8Δhep), and mice with constitutive Ripk3 (Ripk3-/-) deletion, were subjected to surgical ligation of the common bile duct (BDL) from 2 to 28 days. Floxed (Casp8fl/fl) and Ripk3+/+ mice were used as controls. Moreover, the pan-caspase inhibitor IDN-7314 was used, and cell death mechanisms were studied in primary isolated hepatocytes. RESULTS: Overexpression of activated caspase 3, CASP8 and RIPK3 was characteristic of liver explants from patients with primary biliary cholangitis. Twenty-eight days after BDL, Casp8Δhepamice showed decreased necrotic foci, serum aminotransferase levels and apoptosis along with diminished compensatory proliferation and ductular reaction. These results correlated with a decreased inflammatory profile and ameliorated liver fibrogenesis. A similar phenotype was observed in Ripk3-/- mice. IDN-7314 treatment decreased CASP8 levels but failed to prevent BDL-induced cholestasis, independently of CASP8 in hepatocytes. CONCLUSION: These findings show that intervention against CASP8 in liver parenchymal cells - specifically in cholangiocytes - might be a beneficial option for treating obstructive cholestasis, while broad pan-caspase inhibition might trigger undesirable side effects. LAY SUMMARY: Loss of caspase 8 - a protein involved in programmed cell death - in liver parenchymal cells protects against experimental cholestasis. Therefore, specific pharmacological intervention against caspase 8 might be a valid alternative for the treatment of obstructive cholestasis in the clinic, whereas broad pan-caspase inhibiting drugs might trigger undesirable side effects.

Curcumin attenuates hepatic fibrosis and insulin resistance induced by bile duct ligation in rats.

Recent studies have strongly indicated the hepatoprotective effect of curcumin; however, the precise mechanisms are not well understood. This study aimed to determine the protective effect of curcumin on hepatic damage and hepatic insulin resistance in biliary duct ligated (BDL) fibrotic rat model. To accomplish this, male Wistar rats were divided into four groups (eight for each): sham group, BDL group, sham+Cur group and BDL+Cur group. The last two groups received curcumin at a dose of 100 mg/kg daily for 4 weeks. The mRNA/protein expression levels of Ras-related C3 botulinum toxin substrate 1 (Rac1), Rac1-GTP, dinucleotide phosphate oxidase 1 (NOX1), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signalling 3 (SOCS3), insulin receptor substrate 1 (IRS1), extracellular signal-regulated kinase 1 (ERK1), specific protein 1 (Sp1) and hypoxia-inducible factor-1α (HIF-1α) were measured by real-time PCR and Western blotting, respectively. Fasting blood glucose, insulin and Leptin levels were determined and homoeostasis model assessment-estimated insulin resistance, as an index of insulin resistance, was calculated. Curcumin significantly attenuated liver injury and fibrosis, including amelioration of liver histological changes, reduction of hepatic enzymes, as well as decreased expression of liver fibrogenesis-associated variables, including Rac1, Rac1-GTP, NOX1, ERK1, HIF-1α and Sp1. Curcumin also attenuated leptin level and insulin resistance, which had increased in BDL rats (P<0·05). Furthermore, compared with the BDL group, we observed an increase in IRS1 and a decrease in SOCS3 and STAT3 expression in the curcumin-treated BDL group (P<0·05), indicating return of these parameters towards normalcy. In conclusion, Curcumin showed hepatoprotective activity against BDL-induced liver injury and hepatic insulin resistance by influencing the expression of some genes/proteins involved in these processes, and the results suggest that it can be used as a therapeutic option.

Protective Effects of Peroxiredoxin 4 (PRDX4) on Cholestatic Liver Injury.

Accumulating evidence indicates that oxidative stress plays a critical role in initiating the progression of inflammatory and fibrotic liver diseases, including cholestatic hepatitis. Peroxiredoxin 4 (PRDX4) is a secretory antioxidase that protects against oxidative damage by scavenging reactive oxygen species (ROS) in both the intracellular compartments and extracellular space. In this study, we examined the in vivo net effects of PRDX4 overexpression in a murine model of cholestasis. To induce cholestatic liver injury, we subjected C57BL/6J wild-type (WT) or human PRDX4 (hPRDX4) transgenic (Tg) mice to sham or bile duct ligation (BDL) surgery for seven days. Our results showed that the liver necrosis area was significantly suppressed in Tg BDL mice with a reduction in the severity of liver injuries. Furthermore, PRDX4 overexpression markedly reduced local and systemic oxidative stress generated by BDL. In addition, suppression of inflammatory cell infiltration, reduced proliferation of hepatocytes and intrahepatic bile ducts, and less fibrosis were also found in the liver of Tg BDL mice, along with a reduced mortality rate after BDL surgery. Interestingly, the composition of the hepatic bile acids (BAs) was more beneficial for Tg BDL mice than for WT BDL mice, suggesting that PRDX4 overexpression may affect BA metabolism during cholestasis. These features indicate that PRDX4 plays an important role in protecting against liver injury following BDL and might be a promising therapeutic modality for cholestatic diseases.

Serum and Hepatic Autofluorescence as a Real-Time Diagnostic Tool for Early Cholestasis Assessment.

While it is well established that various factors can impair the production and flow of bile and lead to cholestatic disease in hepatic and extrahepatic sites, an enhanced assessment of the biomarkers of the underlying pathophysiological mechanisms is still needed to improve early diagnosis and therapeutic strategies. Hence, we investigated fluorescing endogenous biomolecules as possible intrinsic biomarkers of molecular and cellular changes in cholestasis. Spectroscopic autofluorescence (AF) analysis was performed using a fiber optic probe (366 nm excitation), under living conditions and in serum, on the livers of male Wistar rats submitted to bile duct ligation (BDL, 24, 48, and 72 h). Biomarkers of liver injury were assayed biochemically. In the serum, AF analysis distinctly detected increased bilirubin at 24 h BDL. A continuous, significant increase in red-fluorescing porphyrin derivatives indicated the subversion of heme metabolism, consistent with an almost twofold increase in the serum iron at 72 h BDL. In the liver, changes in the AF of NAD(P)H and flavins, as well as lipopigments, indicated the impairment of mitochondrial functionality, oxidative stress, and the accumulation of oxidative products. A serum/hepatic AF profile can be thus proposed as a supportive diagnostic tool for the in situ, real-time study of bio-metabolic alterations in bile duct ligation (BDL) in experimental hepatology, with the potential to eventually translate to clinical diagnosis.

Borderless regulates glial extension and axon ensheathment.

Ensheathment of axons by glial processes is essential for normal brain function. While considerable progress has been made to define molecular and cellular mechanisms underlying the maintenance of axon ensheathment, less is known about molecular details of early events for the wrapping of axons by glial processes in the developing nervous system. In this study, we investigate the role of the transmembrane protein Borderless (Bdl) in the developing Drosophila visual system. Bdl belongs to the immunoglobulin (Ig) superfamily, and its in vivo function is unknown. We show that Bdl is expressed in wrapping glia (WG) in the developing eye disc. Cell-type-specific transgene rescue and knockdown indicate that Bdl is specifically required in WG for the extension of glial processes along photoreceptor axons in the optic lobe, and axon ensheathment. Our results identify Bdl as a novel glia-specific cell-surface recognition molecule in regulating glial extension and axon ensheathment.

ß-Arrestin 2 Promotes Hepatocyte Apoptosis by Inhibiting Akt Protein.

Recent studies reveal that multifunctional protein ß-arrestin 2 (Arrb2) modulates cell apoptosis. Survival and various aspects of liver injury were investigated in WT and Arrb2 KO mice after bile duct ligation (BDL). We found that deficiency of Arrb2 enhances survival and attenuates hepatic injury and fibrosis. Following BDL, Arrb2-deficient mice as compared with WT controls displayed a significant reduction of hepatocyte apoptosis as demonstrated by the TUNEL assay. Following BDL, the levels of phospho-Akt and phospho-glycogen synthase kinase 3ß (GSK3ß) in the livers were significantly increased in Arrb2 KO compared with WT mice, although p-p38 increased in WT but not in Arrb2-deficient mice. Inhibition of GSK3ß following BDL decreases hepatic apoptosis and decreased p-p38 in WT mice but not in Arrb2 KO mice. Activation of Fas receptor with Jo2 reduces phospho-Akt and increases apoptosis in WT cells and WT mice but not in Arrb2-deficient cells and Arrb2-deficient mice. Consistent with direct interaction of Arrb2 with and regulating Akt phosphorylation, the expression of a full-length or N terminus but not the C terminus of Arrb2 reduces Akt phosphorylation and coimmunoprecipates with Akt. These results reveal that the protective effect of deficiency of Arrb2 is due to loss of negative regulation of Akt due to BDL and decreased downstream GSK3ß and p38 MAPK signaling pathways.

Ammonia produces pathological changes in human hepatic stellate cells and is a target for therapy of portal hypertension.

BACKGROUND & AIMS: Hepatic stellate cells (HSCs) are vital to hepatocellular function and the liver response to injury. They share a phenotypic homology with astrocytes that are central in the pathogenesis of hepatic encephalopathy, a condition in which hyperammonemia plays a pathogenic role. This study tested the hypothesis that ammonia modulates human HSC activation in vitro and in vivo, and evaluated whether ammonia lowering, by using l-ornithine phenylacetate (OP), modifies HSC activation in vivo and reduces portal pressure in a bile duct ligation (BDL) model. METHODS: Primary human HSCs were isolated and cultured. Proliferation (BrdU), metabolic activity (MTS), morphology (transmission electron, light and immunofluorescence microscopy), HSC activation markers, ability to contract, changes in oxidative status (ROS) and endoplasmic reticulum (ER) were evaluated to identify effects of ammonia challenge (50 µM, 100 µM, 300 µM) over 24-72 h. Changes in plasma ammonia levels, markers of HSC activation, portal pressure and hepatic eNOS activity were quantified in hyperammonemic BDL animals, and after OP treatment. RESULTS: Pathophysiological ammonia concentrations caused significant and reversible changes in cell proliferation, metabolic activity and activation markers of hHSC in vitro. Ammonia also induced significant alterations in cellular morphology, characterised by cytoplasmic vacuolisation, ER enlargement, ROS production, hHSC contraction and changes in pro-inflammatory gene expression together with HSC-related activation markers such as α-SMA, myosin IIa, IIb, and PDGF-Rß. Treatment with OP significantly reduced plasma ammonia (BDL 199.1 µmol/L±43.65 vs. BDL+OP 149.27 µmol/L±51.1, p<0.05) and portal pressure (BDL 14±0.6 vs. BDL+OP 11±0.3 mmHg, p<0.01), which was associated with increased eNOS activity and abrogation of HSC activation markers. CONCLUSIONS: The results show for the first time that ammonia produces deleterious morphological and functional effects on HSCs in vitro. Targeting ammonia with the ammonia lowering drug OP reduces portal pressure and deactivates hHSC in vivo, highlighting the opportunity for evaluating ammonia lowering as a potential therapy in cirrhotic patients with portal hypertension.

3D molecular MR imaging of liver fibrosis and response to rapamycin therapy in a bile duct ligation rat model.

BACKGROUND & AIMS: Liver biopsy, the gold standard for assessing liver fibrosis, suffers from limitations due to sampling error and invasiveness. There is therefore a critical need for methods to non-invasively quantify fibrosis throughout the entire liver. The goal of this study was to use molecular Magnetic Resonance Imaging (MRI) of Type I collagen to non-invasively image liver fibrosis and assess response to rapamycin therapy. METHODS: Liver fibrosis was induced in rats by bile duct ligation (BDL). MRI was performed 4, 10, or 18 days following BDL. Some BDL rats were treated daily with rapamycin starting on day 4 and imaged on day 18. A three-dimensional (3D) inversion recovery MRI sequence was used to quantify the change in liver longitudinal relaxation rate (ΔR1) induced by the collagen-targeted probe EP-3533. Liver tissue was subjected to pathologic scoring of fibrosis and analyzed for Sirius Red staining and hydroxyproline content. RESULTS: ΔR1 increased significantly with time following BDL compared to controls in agreement with ex vivo measures of increasing fibrosis. Receiver operating characteristic curve analysis demonstrated the ability of ΔR1 to detect liver fibrosis and distinguish intermediate and late stages of fibrosis. EP-3533 MRI correctly characterized the response to rapamycin in 11 out of 12 treated rats compared to the standard of collagen proportional area (CPA). 3D MRI enabled characterization of disease heterogeneity throughout the whole liver. CONCLUSIONS: EP-3533 allowed for staging of liver fibrosis, assessment of response to rapamycin therapy, and demonstrated the ability to detect heterogeneity in liver fibrosis.

A novel hypothesis for an alkaline phosphatase 'rescue' mechanism in the hepatic acute phase immune response.

The liver isoform of the enzyme alkaline phosphatase (AP) has been used classically as a serum biomarker for hepatic disease states such as hepatitis, steatosis, cirrhosis, drug-induced liver injury, and hepatocellular carcinoma. Recent studies have demonstrated a more general anti-inflammatory role for AP, as it is capable of dephosphorylating potentially deleterious molecules such as nucleotide phosphates, the pathogenic endotoxin lipopolysaccharide (LPS), and the contact clotting pathway activator polyphosphate (polyP), thereby reducing inflammation and coagulopathy systemically. Yet the mechanism underlying the observed increase in liver AP levels in circulation during inflammatory insults is largely unknown. This paper hypothesizes an immunological role for AP in the liver and the potential of this system for damping generalized inflammation along with a wide range of ancillary pathologies. Based on the provided framework, a mechanism is proposed in which AP undergoes transcytosis in hepatocytes from the canalicular membrane to the sinusoidal membrane during inflammation and the enzyme's expression is upregulated as a result. Through a tightly controlled, nucleotide-stimulated negative feedback process, AP is transported in this model as an immune complex with immunoglobulin G by the asialoglycoprotein receptor through the cell and secreted into the serum, likely using the receptor's State 1 pathway. The subsequent dephosphorylation of inflammatory stimuli by AP and uptake of the circulating immune complex by endothelial cells and macrophages may lead to decreased inflammation and coagulopathy while providing an early upstream signal for the induction of a number of anti-inflammatory gene products, including AP itself.

Pioglitazone decreases portosystemic shunting by modulating inflammation and angiogenesis in cirrhotic and non-cirrhotic portal hypertensive rats.

BACKGROUND & AIMS: Development of the portal-hypertensive syndrome is mediated by splanchnic inflammation and neoangiogenesis. Since peroxisome proliferator-activated receptor gamma (PPARγ) agonists like pioglitazone (PIO) regulate inflammatory response and inhibit angiogenesis in endothelial cells, we evaluated PIO as treatment for experimental portal hypertension. METHODS: PIO (10 mg/kg) or vehicle (VEH) was administered from day 21-28 after bile duct ligation (BDL), from day 0-7 after partial portal vein ligation (PPVL) or sham-operation (SO), respectively. After treatment, systemic hemodynamics, splanchnic blood flow (SMABF), portal pressure (PP), and portosystemic shunting (PSS) were assessed. Splanchnic and hepatic tissues were analyzed for angiogenic and inflammatory markers. RESULTS: BDL and PPVL showed significantly increased PP, SMABF, and PSS compared to SO-VEH rats. While PIO treatment did not decrease PP or SMABF, PSS was significantly reduced both in cirrhotic (BDL-VEH: 71% to BDL-PIO: 41%; p<0.001) and non-cirrhotic (PPVL-VEH: 62% to PPVL-PIO: 40%; p=0.041) rats. PIO (10 µM, in vitro) inhibited endothelial cell migration and significantly increased PPARγ activity in vivo. In BDL rats, PIO decreased hepatic mRNA levels of PPARγ (p=0.01) and PlGF (p=0.071), and splanchnic mRNA expression of PPARγ (p=0.017), PDGFß (p=0.053) and TNFα (p=0.075). Accordingly, splanchnic protein expression of PPARγ (p=0.032), VEGFR2 (p=0.035), CD31 (p=0.060) and PDGFß (p=0.066) were lower in BDL-PIO vs. BDL-VEH animals. In PPVL rats, PIO treatment decreased splanchnic gene expression of Ang2 (-12.4 fold), eNOS (-9.3 fold), PDGF (-7.0 fold), PlGF (-11.9 fold), TGFb (-8.3 fold), VEGF-A (-11.3 fold), VEGFR1 (-5.9 fold), IL1b (-14.4 fold), and IL6 (-9.6 fold). CONCLUSIONS: Pioglitazone treatment decreases portosystemic shunting via modulation of splanchnic inflammation and neoangiogenesis. Pioglitazone should be assessed for potential beneficial effects in patients with portosystemic collaterals due to portal hypertension.