Fluvastatin reduced liver injury in rat model of extrahepatic cholestasis

Transcriptome analysis reveals the molecular mechanism of Yiqi Rougan decoction in reducing CCl4-induced liver fibrosis in rats

Background

Liver fibrosis develops from various chronic liver diseases, and there is currently a lack of specific treatment strategies. Yiqi Rougan decoction (YQRG) is a traditional Chinese medicine that has shown durative effects in the treatment of liver fibrosis; however, the mechanism associated with YQRG-related improvements in liver fibrosis remains to be experimentally determined. This study evaluated the therapeutic effect of YQRG on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats and its molecular mechanism.

Methods

We used low-, medium-, and high-dose YQRG to treat CCl₄-induced liver fibrosis in rats, followed by assessment of liver injury and fibrosis according to liver appearance, body weight, liver mass index, histopathologic examination, and serum testing. Additionally, we performed transcriptome analysis using RNA-sequencing (RNA-seq) technology, including cluster, Gene Ontology (GO), and pathway analyses, to identify differentially expressed genes (DEGs), and protein and gene expression were detected by immunofluorescence (IFC), western blot and real-time quantitative PCR.

Results

The results showed that YQRG effectively alleviated CCl₄-induced liver injury and fibrosis in rats, including observations of improved liver function, decreased activity of hepatic stellate cells (HSCs), and decreased extracellular matrix (ECM) deposition. Moreover, we identified downregulated and upregulated DEGs in the model group relative to the control and YQRG-treated groups, with GO analysis revealing their enrichment in biological processes, such as endoplasmic reticulum stress (ERS), apoptosis, and autophagy. Furthermore, pathway analysis showed that YQRG treatment downregulated the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/Akt (PI3K/AKT) signalling pathways and upregulated other signalling pathways, including those related to peroxisome proliferator-activated receptors(PPAR) and AMP-activated protein kinase(AMPK), with these findings subsequently verified experimentally.

Conclusion

These findings showed that YQRG improved CCl₄-induced liver fibrosis through multiple mechanisms and pathways, offering critical insight into the YQRG-related therapeutic mechanism and promoting further research into its potential application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00552-w.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications, such as variceal bleeding, ascites or hepatic encephalopathy. As such, clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis. At present, non-selective β-blockers, vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia. In contrast, safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue. In recent years, several preclinical and clinical trials have focused on this latter component and other therapeutic avenues. In this review, we highlight novel data in this context and address potentially interesting therapeutic options for the future.

Atorvastatin does not protect against ischemia-reperfusion damage in cholestatic rat livers

BACKGROUND

Extrahepatic cholestasis sensitizes the liver to ischemia/reperfusion (I/R) injury during surgery for perihilar cholangiocarcinoma. It is associated with pre-existent sterile inflammation, microvascular perfusion defects, and impaired energy status. Statins have been shown to protect against I/R injury in normal and steatotic mouse livers. Therefore, the hepatoprotective properties of atorvastatin were evaluated in a rat model of cholestatic I/R injury.

METHODS

Male Wistar rats were subjected to 70% hepatic ischemia (during 30 min) at 7 days after bile duct ligation. Rats were randomized to atorvastatin treatment or vehicle-control in three test arms: (1) oral treatment with 5 mg/kg during 7 days after bile duct ligation; (2) intravenous treatment with 2.5, 5, or 7.5 mg/kg at 24 h before ischemia; and (3) intravenous treatment with 5 mg/kg at 30 min before ischemia. Hepatocellular damage was assessed by plasma alanine aminotransferase (ALT) and histological necrosis.

RESULTS

I/R induced severe hepatocellular injury in the cholestatic rat livers (~10-fold increase in ALT at 6 h after I/R and ~30% necrotic areas at 24 h after I/R). Both oral and intravenous atorvastatin treatment decreased ALT levels before ischemia. Intravenous atorvastatin treatment at 5 mg/kg at 24 h before ischemia was the only regimen that reduced ALT levels at 6 h after reperfusion, but not at 24 h after reperfusion. None of the tested regimens were able to reduce histological necrosis at 24 h after reperfusion.

CONCLUSION

Pre-treatment with atorvastatin did not protect cholestatic livers from hepatocellular damage after I/R. Clinical studies investigating the role of statins in the protection against hepatic I/R injury should not include cholestatic patients with perihilar cholangiocarcinoma. These patients require (pharmacological) interventions that specifically target the cholestasis-associated hepatopathology.

Modulation of the Unfolded Protein Response by Tauroursodeoxycholic Acid Counteracts Apoptotic Cell Death and Fibrosis in a Mouse Model for Secondary Biliary Liver Fibrosis

The role of endoplasmic reticulum stress and the unfolded protein response (UPR) in cholestatic liver disease and fibrosis is not fully unraveled. Tauroursodeoxycholic acid (TUDCA), a hydrophilic bile acid, has been shown to reduce endoplasmic reticulum (ER) stress and counteract apoptosis in different pathologies. We aimed to investigate the therapeutic potential of TUDCA in experimental secondary biliary liver fibrosis in mice, induced by common bile duct ligation. The kinetics of the hepatic UPR and apoptosis during the development of biliary fibrosis was studied by measuring markers at six different timepoints post-surgery by qPCR and Western blot. Next, we investigated the therapeutic potential of TUDCA, 10 mg/kg/day in drinking water, on liver damage (AST/ALT levels) and fibrosis (Sirius red-staining), in both a preventive and therapeutic setting. Common bile duct ligation resulted in the increased protein expression of CCAAT/enhancer-binding protein homologous protein (CHOP) at all timepoints, along with upregulation of pro-apoptotic caspase 3 and 12, tumor necrosis factor receptor superfamily, member 1A (TNFRsf1a) and Fas-Associated protein with Death Domain (FADD) expression. Treatment with TUDCA led to a significant reduction of liver fibrosis, accompanied by a slight reduction of liver damage, decreased hepatic protein expression of CHOP and reduced gene and protein expression of pro-apoptotic markers. These data indicate that TUDCA exerts a beneficial effect on liver fibrosis in a model of cholestatic liver disease, and suggest that this effect might, at least in part, be attributed to decreased hepatic UPR signaling and apoptotic cell death.

Role of matrix metalloproteinases in cholestasis and hepatic ischemia/reperfusion injury: A review

Matrix metalloproteinases (MMPs) are a family of proteases using zinc-dependent catalysis to break down extracellular matrix (ECM) components, allowing cell movement and tissue reorganization. Like many other proteases, MMPs are produced as zymogens, an inactive form, which are activated after their release from cells. Hepatic ischemia/reperfusion (I/R) is associated with MMP activation and release, with profound effects on tissue integrity: their inappropriate, prolonged or excessive expression has harmful consequences for the liver. Kupffer cells and hepatic stellate cells can secrete MMPs though sinusoidal endothelial cells are a further source of MMPs. After liver transplantation, biliary complications are mainly attributable to cholangiocytes, which, compared with hepatocytes, are particularly susceptible to injury and ultimately a major cause of increased graft dysfunction and patient morbidity. This paper focuses on liver I/R injury and cholestasis and reviews factors and mechanisms involved in MMP activation together with synthetic compounds used in their regulation. In this respect, recent data have demonstrated that the role of MMPs during I/R may go beyond the mere destruction of the ECM and may be much more complex than previously thought. We thus discuss the role of MMPs as an important factor in cholestasis associated with I/R injury.

Rosuvastatin improves hepatopulmonary syndrome through inhibition of inflammatory angiogenesis of lung

The hepatopulmonary syndrome (HPS) is characterized by hypoxia and increased intrapulmonary shunts in cirrhotic patients. Emerging evidence showed promising results of treating HPS by abolishment of intrapulmonary inflammation and angiogenesis. Rosuvastatin is a kind of 3-hydroxy-methyl-3-glutamyl coenzyme A reductase inhibitor. In addition to lipid-lowering effects, it has anti-inflammation and anti-angiogenesis properties. We postulated that rosuvastatin treatment can ameliorate HPS. Common bile duct ligation (CBDL) was applied in an experimental HPS animal model. CBDL rats received 2-week rosuvastatin (20 mg/kg/day) treatments from the fifteenth day after operation. The haemodynamic data, blood gas analysis, liver biochemistries, tumour necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were examined after rosuvastatin treatment. The liver and lung tissues were dissected for histopathological studies and protein analyses. In the parallel groups, intrapulmonary shunts were determined. The haemodynamic and liver biochemistries were not changed after rosuvastatin treatment in CBDL rats, but the alveolar-arterial oxygen pressure gradient was significantly decreased, implying that HPS-induced hypoxia was reversed after rosuvastatin treatment. In addition, rosuvastatin treatment reduced intrapulmonary shunts and plasma levels of VEGF and TNF-α. Besides, the intrapulmonary protein expression of nuclear factor kappa B (NF-κB), VEGF receptor (VEGFR)-1,2 and Rho-associated A kinase were significantly down-regulated and the intrapulmonary angiogenesis was ameliorated. We concluded that rosuvastatin alleviates experimental HPS through blockade of pulmonary inflammatory angiogenesis via TNF-α/NF-κB and VEGF/Rho-associated A kinase pathways down-regulation.

Fluvastatin inhibits the induction of inducible nitric oxide synthase, an inflammatory biomarker, in hepatocytes

AIM

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors), which were originally designed to lower plasma cholesterol levels, are increasingly recognized as anti-inflammatory agents. In the inflamed liver, pro-inflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS). Overproduction of NO by iNOS has been implicated as a factor in liver injury. We examined pro-inflammatory cytokine-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of statins. We hypothesized that statins are involved in the downregulation of iNOS, resulting in decreased hepatic inflammation.

METHODS

Hepatocytes were isolated from rats by collagenase perfusion and centrifugation. Primary cultured hepatocytes were treated with interleukin (IL)-1β in the presence or absence of fluvastatin. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

IL-1β produced increased levels of NO. This effect was inhibited by fluvastatin, which exerted its maximal effects at 100 μM. Fluvastatin decreased the levels of iNOS protein and its mRNA expression. Fluvastatin had no effects on IκB degradation and nuclear factor-κB activation. However, fluvastatin inhibited the upregulation of type I IL-1 receptor mRNA and protein expression. Transfection experiments demonstrated that fluvastatin suppressed iNOS induction by the inhibition of promoter transactivation and mRNA stabilization. Fluvastatin reduced the expression of an iNOS gene antisense-transcript, which is involved in iNOS mRNA stability.

CONCLUSION

Results indicate that fluvastatin inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. Fluvastatin may provide therapeutic potential in iNOS induction involved in various liver injuries.

Pravastatin modulates liver bile acid and cholesterol homeostasis in rats with chronic cholestasis

BACKGROUND AND AIM

The administration of pravastatin to patients with cholestatic liver disease has suggested the potential of the drug with regard to reducing raised plasma cholesterol and bile acid levels. Information about the mechanisms associated with this effect is lacking. Thus, the aim of the present study is to evaluate pravastatin effects on the liver bile acid and cholesterol homeostasis in healthy and cholestatic rats.

METHODS

Control sham-operated and reversibly bile duct-obstructed (BDO) rats were treated with pravastatin (1 or 5 mg/kg) or the vehicle alone for 7 days after surgery.

RESULTS

Lower doses of pravastatin reduced bile acid plasma concentrations in cholestatic animals. The effect was associated with reduced liver mRNA expression of Cyp7a1, Cyp8b1, Mrp2, Ugt1a1 and the increased expression of Bsep. In addition, BDO-induced increase in the liver content of cholesterol was normalized by pravastatin. The change was accompanied by the reduced liver expression of Hmg-CoA reductase, LDL receptor, and Acat2, and induced the expression of Abca1 and Mdr2. These changes corresponded with the upregulation of nuclear receptors LXRα and PPARα, and the downregulation of FXR, CAR, SREBP-2 and HNF1α. High doses of pravastatin lacked any positive effects on bile acids and cholesterol homeostasis, and blocked bile formation through the reduction of the biliary excretion of bile acids.

CONCLUSIONS

Pravastatin rendered a positive reduction in BDO-induced increases in plasma bile acid concentrations and cholesterol liver content, mainly through the transcriptionally-mediated downregulation of genes involved in the synthesis of these compounds in the liver.

Effects of Ganoderma lucidum on obstructive jaundice-induced oxidative stress

OBJECTIVE

Obstructive jaundice develops after occlusion of the common bile duct. Direct hyperbilirubinaemia, which occurs secondary to the condition, causes various life-threatening pathologies. Cytoprotective effects of Ganoderma lucidum (GL) have previously been shown. In this study, the effects of GL on oxidative stress and oxidant DNA damage in experimental obstructive jaundice were evaluated.

METHODS

Sixty Wistar albino adult female rats were randomly divided into six weight-matched equal groups: sham group, bile duct ligated group (BDL); after sham operation 250 mg/kg/d of GL administered group, after sham operation 500 mg/kg/d of GL administered group, after bile duct ligation 250 mg/kg/d of GL administered (GL1BDL) group, and after bile duct ligation 500 mg/kg/d of GL administered (GL2BDL) group. GL polysaccharide was orally administered to the rats via gavage tube once a day for 14 days after bile duct ligation.

RESULTS

The plasma malondialdehyde levels of the GL1BDL and GL2BDL groups were significantly lower than those of the BDL group (p < 0.01). The plasma 8-hydroxy-2'-deoxyguanosine levels of the GL1BDL and GL2BDL groups were significantly lower than those of the BDL group (p < 0.001). The liver tissue Cu-Zn superoxide dismutase level of the GL2BDL group was significantly higher than that of the BDL group (p < 0.05).

CONCLUSION

GL protected against DNA and liver tissue damage by reducing oxidative stress in obstructive jaundice.

Effect of rosuvastatin on cholestasis-induced hepatic injury in rat livers

Recent studies reported that 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors have pleotropic effects independent of their lipid-lowering properties. The present study was undertaken to determine whether treatment with rosuvastatin (RO) would be beneficial in a rat model of bile duct ligation (BDL). Animals were divided into three groups: a sham group (group I), a BDL group treated with vehicle (group II), and a BDL group treated with RO (10 mg/kg) (group III). Serum levels of total bilirubin, gamma-glutamyl transpeptidase, alanine aminotransferase, and aspartate aminotransferase decreased significantly in group III when compared to group II. Lipid peroxides and NO levels of group III were found to be significantly lower than those of group II. Antioxidant enzymes (superoxide dismutase, glutathione-S-transferase, and catalase) activity in liver tissues markedly decreased in group II, whereas treatment with RO preserved antioxidant enzyme activity. DT-diaphorase activity in group II was significantly higher than that in group III. The histopathological results showed multiple numbers of newly formed bile ductules with inflammatory cells infiltration in group II. These pathological changes were improved in group III. Our data indicate that RO ameliorates hepatic injury, inflammation, lipid peroxidation and increases antioxidant enzymes activity in rats subjected to BDL. RO may have a beneficial effect on treatment of cholestatic liver diseases.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Effects of the administration of pentoxifylline and prednisolone on the evolution of portal fibrogenesis secondary to biliary obstruction-an experimental study in growing animals

BACKGROUND

Many chronic liver diseases lead to progressive hepatic fibrosis, a condition that can ultimately result in loss of organ function and severe portal hypertension necessitating hepatic transplantation. Within the last few decades, studies have been conducted to demonstrate the possibility of drug modulation of hepatic fibrogenesis. Regarding biliary obstruction, it has been suggested that administration of corticosteroids could promote better late outcomes for children with biliary atresia submitted to Kasai's portoenterostomy. Models used to test potential antifibrogenic drugs such as pentoxifylline (PTX) have not included growing animals.

METHODS

In this experimental study, 119 young rats (21st or 22nd days) were submitted to laparotomy and common bile duct ligation (CBDL) or to sham surgery (SHAM). Animals were allocated into 5 groups, according to surgical procedure, and administered the following solutions: (1) CBDL + distilled water, (2) SHAM + distilled water, (3) CBDL + PTX, (4) CBDL + prednisolone (PRED), and (5) CBDL + PTX + PRED (PTX + PRED). Each group was further divided into 2 subgroups according to the length of the experiment (15 or 30 days). At the end of the defined period, animals were weighed, and a hepatic fragment was collected from each one for analyses.

RESULTS

The PTX animals exhibited increased weight gain compared to animals in the PRED or PTX + PRED groups. Animals from the 3 therapeutic groups (PTX, PRED, and PTX + PRED) showed diminished collagen-filled area in portal spaces. Total portal space area was increased in the PTX group.

CONCLUSIONS

Hepatic fibrosis induced by bile duct ligation in young rats could be modulated by pharmacologic interventions. Administration of PTX or PRED, or the combination of both, resulted in diminished collagen-filled areas in portal spaces.

Co-medications that modulate liver injury and repair influence clinical outcome of acetaminophen-associated liver injury

BACKGROUND & AIMS

Acetaminophen-induced liver injury is the most common cause of acute liver failure in the United States; it occurs inadvertently in approximately half of all cases. Concomitant use of other medications might impact susceptibility to acetaminophen hepatotoxicity. We investigated its association with administration of drugs that have been shown to modulate liver injury and/or repair in preclinical studies.

METHODS

We analyzed data from 6386 cases of acetaminophen-associated liver injury that were defined in the FDA database of reported adverse events. Data reported in the severe adverse event categories of "died" or "life-threatening" (defined as "fatal" cases, n = 2512) were compared with those of "non-fatal" cases (n = 3874). Potential associations between fatality and concomitant use of 9 drug classes were assessed using multiple logistic regression analyses after adjusting for other variables.

RESULTS

Among female subjects, concomitant use of statins, fibrates or nonsteroidal anti-inflammatory drugs was associated with decreased likelihood of fatality, whereas ethanol use was associated with increased likelihood. Among male subjects, concomitant use of statins was associated with decreased likelihood of fatality, whereas concomitant use of sympathetic stimulants or ethanol was associated with increased likelihood. Concomitant use of angiotensin converting enzyme inhibitors or angiotensin receptor II antagonists was associated with decreased likelihood of fatality among younger subjects.

CONCLUSIONS

Concomitant use of medications that have been shown in preclinical studies to modulate liver injury and/or repair influenced acetaminophen hepatotoxicity. Drugs that reduce injury or increase repair are protective, whereas those that exacerbate injury or reduce repair are detrimental.

Prolactin stimulates the proliferation of normal female cholangiocytes by differential regulation of Ca2+-dependent PKC isoforms

Background

Prolactin promotes proliferation of several cells. Prolactin receptor exists as two isoforms: long and short, which activate different transduction pathways including the Ca²⁺-dependent PKC-signaling. No information exists on the role of prolactin in the regulation of the growth of female cholangiocytes. The rationale for using cholangiocytes from female rats is based on the fact that women are preferentially affected by specific cholangiopathies including primary biliary cirrhosis. We propose to evaluate the role and mechanisms of action by which prolactin regulates the growth of female cholangiocytes.

Results

Normal cholangiocytes express both isoforms (long and short) of prolactin receptors, whose expression increased following BDL. The administration of prolactin to normal female rats increased cholangiocyte proliferation. In purified normal female cholangiocytes, prolactin stimulated cholangiocyte proliferation, which was associated with increased [Ca²⁺]_i levels and PKCβ-I phosphorylation but decreased PKCα phosphorylation. Administration of an anti-prolactin antibody to BDL female rats decreased cholangiocyte proliferation. Normal female cholangiocytes express and secrete prolactin, which was increased in BDL rats. The data show that prolactin stimulates normal cholangiocyte growth by an autocrine mechanism involving phosphorylation of PKCβ-I and dephosphorylation of PKCα.

Conclusion

We suggest that in female rats: (i) prolactin has a trophic effect on the growth of normal cholangiocytes by phosphorylation of PKCβ-I and dephosphorylation of PKCα; and (iii) cholangiocytes express and secrete prolactin, which by an autocrine mechanism participate in regulation of cholangiocyte proliferation. Prolactin may be an important therapeutic approach for the management of cholangiopathies affecting female patients.