Rifaximin Prevents Intestinal Barrier Dysfunction and Alleviates Liver Injury in MCT-induced HSOS Mice.

OBJECTIVE: Rifaximin is an effective component of treatment strategies for liver and intestinal diseases. However, the efficacy of rifaximin in hepatic sinusoidal obstruction syndrome (HSOS) has not been explored. The present study aimed to investigate the efficacy and mechanism of rifaximin in HSOS. METHODS: An HSOS model was established in mice through the administration of monocrotaline (MCT, 800 mg/kg), and part of the HSOS mice were intragastrically administered with rifaximin. Then, the efficacy of rifaximin in HSOS was evaluated based on the liver pathological findings, liver proinflammatory cytokines, and alanine aminotransferase and aspartate aminotransferase levels. The Ussing chamber was used to evaluate the intestinal permeability, and tight junction (TJ) proteins were measured by Western blotting and real-time polymerase chain reaction to evaluate the intestinal barrier integrity. Then, the serum proinflammatory cytokine levels were evaluated by enzyme-linked immunosorbent assay. Afterwards, an in vitro experiment was performed to determine the relationship between rifaximin and TJ proteins. RESULTS: Rifaximin effectively alleviated the MCT-induced HSOS liver injury, suppressed the expression of liver proinflammatory cytokines, and reduced the serum levels of tumor necrosis factor-alpha and interleukin-6. Furthermore, rifaximin reduced the intestinal permeability, improved the intestinal barrier integrity, and promoted the expression of TJ proteins. CONCLUSION: The results revealed that the intestinal barrier integrity was destroyed in MCT-induced HSOS. The significant alleviation of MCT-induced HSOS induced by rifaximin might be correlated to the repairment of intestinal barrier integrity via the regulation of the TJ protein expression.

Andrographolide attenuated MCT-induced HSOS via regulating NRF2-initiated mitochondrial biogenesis and antioxidant response.

Hepatic sinusoidal obstruction syndrome (HSOS) is a death-dealing liver disease with a fatality rate of up to 67%. In the study present, we explored the efficacy of andrographolide (Andro), a diterpene lactone from Andrographis Herba, in ameliorating the monocrotaline (MCT)-induced HSOS and the underlying mechanism. The alleviation of Andro on MCT-induced rats HSOS was proved by biochemical index detection, electron microscope observation, and liver histological evaluation. Detection of hepatic ATP content, mitochondrial DNA (mtDNA) copy number, and protein expression of nuclear respiratory factor-1 (NRF1) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) demonstrated that Andro strengthened mitochondrial biogenesis in livers from MCT-treated rats. Chromatin immunoprecipitation assay exhibited that Andro enhanced the occupation of nuclear factor erythroid 2-related factor 2 (NFE2L2, also known as NRF2) in the promoter regions of both PPARGC1A and NRF1. Andro also activated the NRF2-dependent anti-oxidative response and alleviated liver oxidative injury. In Nrf2 knock-out mice, MCT induced more severe liver damage, and Andro showed no alleviation in it. Furthermore, the Andro-activated mitochondrial biogenesis and anti-oxidative response were reduced in Nrf2 knock-out mice. Contrastingly, knocking out Kelch-like ECH-associated protein 1 (Keap1), a NRF2 repressor, reduced MCT-induced liver damage. Results from co-immunoprecipitation, molecular docking analysis, biotin-Andro pull-down, cellular thermal shift assay, and surface plasmon resonance assay showed that Andro hindered the NRF2-KEAP1 interaction via directly binding to KEAP1. In conclusion, our results revealed that NRF2-dependent liver mitochondrial biogenesis and anti-oxidative response were essential for the Andro-provided alleviation of the MCT-induced HSOS. Graphical Headlights: 1. Andro alleviated MCT-induced HSOS via activating antioxidative response and promoting mitochondrial biogenesis. 2. Andro-activated antioxidative response and mitochondrial biogenesis were NRF2-dependent. 3. Andro activated NRF2 via binding to KEAP1.

[Posttransplant complications: GVHD and SOS/VOD].

Several novel agents (e.g., molecularly targeted drug, bispecific antibody, antibody-drug conjugate, chimeric antigen receptor T-cell therapy) have successively emerged in clinical practice and are occasionally used in allogeneic hematopoietic cell transplantation (allo-HCT) settings. These drugs are expected to reduce pretransplant tumors, lower the risk of relapse with posttransplant maintenance therapy, and consequently improve transplant outcomes. Additionally, some molecularly targeted drugs could be adapted to treat steroid-refractory acute and/or chronic graft-versus-host disease (GVHD), which remained the leading cause of nonrelapse mortality after allo-HCT. However, these agents develop an excessive immune reaction, including GVHD, or presented an increased risk of sinusoidal obstruction syndrome (SOS)/veno-occlusive disease (VOD) as their "off-target" effects. Thus, this review aimed to summarize the risk assessment and management of post-posttransplant complications, focusing on GVHD and SOS/VOD, in the era of molecularly targeted therapy. Moreover, recent advances in GVHD or SOS/VOD prophylaxis and treatment using novel agents/devices are also discussed.

Melatonin attenuates monocrotaline-induced hepatic sinusoidal obstruction syndrome in rats via activation of Sirtuin-3.

Melatonin possesses potent hepatoprotective properties, but it remains to be elucidated whether melatonin has a therapeutic effect on monocrotaline (MCT)-induced hepatic sinusoidal obstruction syndrome (HSOS). In this study, male Sprague Dawley rats were intraperitoneally injected with melatonin or the same volume of vehicle at 0 and 24 h after MCT intragastric administration. Next, hematoxylin-eosin staining and electron microscopy were performed to evaluate the hepatic sinusoidal injury of rats. Endothelial cell marker RECA-1 was observed by immunohistochemistry. Hepatic oxidative stress was analyzed by detecting malondialdehyde, glutathione S-transferase, and reactive oxygen species. Assessment of liver function was carried out by analysis of serum aspartate aminotransferase, alanine aminotransferase, total bilirubin, and albumin levels. Real-time polymerase chain reaction and Western blot analysis were used to identify liver Sirtuin-3 (SIRT3) and active matrix metallopeptidase 9 (MMP-9) expression. Besides, liver sinusoidal endothelial cells (LSECs) were used for the in vitro functional verification experiment. Specifically, liver histology of the melatonin-treated groups showed that the pathological damages caused by MCT were significantly attenuated, total HSOS scores were decreased, and the elevation of serum hyaluronic acid observed in the model group was also reduced. Moreover, melatonin treatment also improved the survival of rats after partial hepatectomy. Administration of melatonin ameliorated MCT-induced LSECs injury, hepatic oxidative stress, and hepatic dysfunction. Furthermore, melatonin treatment increased SIRT3 expression while attenuating MMP-9 activity in liver tissues. Cell experiment also demonstrated that SIRT3 might mediate the protective effect of melatonin on LSECs. Collectively, our study provided the potential rationale for the application of melatonin for the prevention of MCT-induced HSOS.

Defibrotide improved the outcome of monocrotaline induced rat hepatic sinusoidal obstruction syndrome.

BACKGROUND AND AIM: Pyrrolizidine alkaloids (PA) induced hepatic sinusoidal obstruction syndrome (HSOS) occurred worldwide and the mortality rate remained high because there were no specific therapies. Defibrotide was effective for HSOS following hematopoietic stem cell transplantation. But the pathogenesis of the two types of HSOS were not equivalent. The purpose of this study was to see if defibrotide was also effective in PA induced rat HSOS. METHODS: First we improved rat HSOS model by using higher dose (230 mg/kg) of monocrotaline (a kind of PA) as the dose of median lethal dose. So drug effectiveness could be assessed by survival time. Next, male SD rats were divided into 5 groups. They were control group, model group, low dose low molecular weight heparin (LMWH) treatment group, high dose LMWH treatment group and defibrotide treatment group. Rats' survival time, liver function, white blood cell count and cytokines were compared among the groups. The DeLeve score was used to assess the severity of liver pathology. RESULTS: The model group exhibited typical liver pathology of HSOS, such as hepatic sinus dilation, congestion, endothelial injury of central lobular vein, coagulative necrosis of hepatocytes and fibrin deposition in the subendothelial. The pathologic characteristics indicated that the model was built up successfully. The survival rate was significantly higher in defibrotide group (81.8%) than model group (43.7%), while the survival rates were similar in the two LMWH groups (62.5% and 75%) and model group. The survival time only be prolonged by defibrotide (P=0.028) but not LMWH (P>0.05). DeLeve score was improved most in the defibrotide group than the two LMWH groups (both P<0.01). Changes in DeLeve score, liver function, plasma level of tumor necrosis factor α and plasminogen activator inhibitor-1 exhibited the same trends. CONCLUSION: Defibrotide could improve the outcome of monocrotaline-induced rat HSOS indicating that defibrotide might be a better choice than LMWH in clinical practice.

Model establishment and microarray analysis of mice with oxaliplatin­induced hepatic sinusoidal obstruction syndrome.

Hepatic sinusoidal obstruction syndrome (HSOS) is a serious side effect of oxaliplatin (OXA) treatment. The present study aimed to establish a reproducible mouse model of OXA­induced HSOS and to preliminarily explore the underlying molecular mechanisms using mRNA microarray analysis. A total of 45 C57BL/6 male mice were randomly divided into five groups: Control, 5 mg/kg OXA, 10 mg/kg OXA, 15 mg/kg OXA and 20 mg/kg OXA. The mice were respectively injected intraperitoneally with 5% glucose solution, or 5, 10, 15 or 20 mg/kg OXA solution once a week for 6 consecutive weeks. The body weight of the mice was recorded every day. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. Hematoxylin and eosin staining, Sirius red staining and scanning electron microscopy were used to identify pathological changes. mRNA microarray was used to analyze changes in the gene expression profiles mainly from the functional aspects of Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. The oxidation mechanism was verified by measuring oxidative stress­related markers and reactive oxygen species with dihydroethidium probe technology, according to the microarray results. Among all of the OXA groups, 10 mg/kg OXA resulted in an acceptable survival rate of 78%. The mice showed obvious splenomegaly, increases in serum levels of ALT and AST, aggravation of liver pathological injuries and hepatic sinusoidal injuries. The microarray results suggested that mRNA expression changes after OXA treatment were associated with 'oxidative stress', 'coagulation function', 'steroid anabolism' and 'pro­inflammatory responses'. The results confirmed that OXA aggravated oxidative damage in the livers of the mice. The present study successfully established a mouse model of OXA­induced HSOS and preliminarily analyzed the underlying molecular mechanisms involved, thus laying a foundation for a subsequent in­depth study.

Bear bile powder attenuates senecionine-induced hepatic sinusoidal obstruction syndrome in mice.

Hepatic sinusoidal obstruction syndrome (HSOS) via exposure to pyrrolizidine alkaloids (PAs) is with high mortality and there is no effective treatment in clinics. Bear bile powder (BBP) is a famous traditional animal drug for curing a variety of hepatobiliary diseases such as cholestasis, inflammation, and fibrosis. Here, we aim to evaluate the protective effect of BBP against HSOS induced by senecionine, a highly hepatotoxic PA compound. Our results showed that BBP treatment protected mice from senecionine-induced HSOS dose-dependently, which was evident by improved liver histology including reduced infiltration of inflammatory cells and collagen positive cells, alleviated intrahepatic hemorrhage and hepatic sinusoidal endothelial cells, as well as decreased conventional serum liver function indicators. In addition, BBP treatment lowered matrix metalloproteinase 9 and pyrrole-protein adducts, two well-known markers positively associated with the severity of PA-induced HSOS. Further investigation showed that BBP treatment prevents the development of liver fibrosis by decreasing transforming growth factor beta and downstream fibrotic molecules. BBP treatment also alleviated senecionine-induced liver inflammation and lowered the pro-inflammatory cytokines, in which tauroursodeoxycholic acid played an important role. What's more, BBP treatment also decreased the accumulation of hydrophobic bile acids, such as cholic acid, taurocholic acid, glycocholic acid, as well. We concluded that BBP attenuates senecionine-induced HSOS in mice by repairing the bile acids homeostasis, preventing liver fibrosis, and alleviating liver inflammation. Our present study helps to pave the way to therapeutic approaches of the treatment of PA-induced liver injury in clinics.

A TMT-based shotgun proteomics uncovers overexpression of thrombospondin 1 as a contributor in pyrrolizidine alkaloid-induced hepatic sinusoidal obstruction syndrome.

Hepatic sinusoidal obstruction disease (HSOS) is a rare but life-threatening vascular liver disease. However, its underlying mechanism and molecular changes in HSOS are largely unknown, thus greatly hindering the development of its effective treatment. Hepatic sinusoidal endothelial cells (HSECs) are the primary and essential target for HSOS. A tandem mass tag-based shotgun proteomics study was performed using primary cultured HSECs from mice with HSOS induced by senecionine, a representative toxic pyrrolizidine alkaloid (PA). Dynamic changes in proteome were found at the initial period of damage and the essential role of thrombospondin 1 (TSP1) was highlighted in PA-induced HSOS. TSP1 over-expression was further confirmed in human HSECs and liver samples from patients with PA-induced HSOS. LSKL peptide, a known TSP1 inhibitor, protected mice from senecionine-induced HSOS. In addition, TSP1 was found to be covalently modified by dehydropyrrolizidine alkaloids in human HSECs and mouse livers upon senecionine treatment, thus to form the pyrrole-protein adduct. These findings provide useful information on early changes in HSECs upon PA treatment and uncover TSP1 overexpression as a contributor in PA-induced HSOS.

Transient elastography of liver: Could it be a guide for diagnosis and management strategy in hepatic veno-occlusive disease (sinusoidal obstruction syndrome)?

Hepatic veno-occlusive disease (VOD), also termed sinusoidal obstruction syndrome (SOS), is a rare and life threatening complication of hematopoetic stem cell transplantation (HSCT). Many conditions can mimic the clinical signs of VOD/SOS. Differential diagnosis and diagnosis of the disease at an early stage is important, since the severe form of the disease has higher mortality rates and early-initiated specific treatment has better response rates. A sensitive and specific non-invasive imaging technique that can diagnose the disease at an early stage is still an unmet need today. We aimed to determine the role of liver stiffness measurement (LSM) with transient elastograph (TE) for the diagnosis of VOD/SOS after allogeneic HSCT. Between January 2019 and October 2021, a total of 49 patients underwent allogeneic HSCT and were retrospectively analyzed. Thirty-one adult patients who had a two or more LSM value were included in the study. Revised European Society for Blood and Marrow Transplantation (EBMT) was the criteria used for the diagnosis of VOD/SOS. Two of 31 patients developed VOD/SOS (6.4 %). Very high LSM values were detected in all patients who developed VOD/SOS. Early and specific VOD/SOS treatment resulted in improvement of LSM values together with other related features. However, LSM values did not increase significantly in patients with high a bilirubin level (≥2 mg/dl) without VOD/SOS. This study demonstrates that TE might be a promising non-invasive imaging method for diagnosis, follow-up and differential diagnosis of this dismal complication of HSCT. Yet, these results need to be supported by prospective studies.

Gynura segetum induces hepatic sinusoidal obstruction syndrome in mice by impairing autophagy.

PURPOSE: To investigate the underlying mechanism of hepatic sinusoidal obstruction syndrome (HSOS) induced by Gynura segetum by measuring autophagy in mouse models. METHODS: The model group was administered G. segetum (30 g/kg/d) by gavage, while the normal control group was administered an equal volume of saline daily for five weeks. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatic histopathological examinations, and Masson staining were performed to evaluate liver injury. Liver intercellular adhesion molecule-1 (ICAM-1) and P-selectin were evaluated by immunohistochemistry. Hepatocellular apoptosis was assessed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Protein expression levels of autophagy markers were measured using Western blot analysis. RESULTS: Gynura segetum was found to significantly induce liver injury compared with control mice, as evidenced by the increase of serum transaminases, a decrease in triglyceride levels, and histopathological changes in mice. Gynura segetum remarkably induced hepatocellular apoptosis and upregulated the expressions of ICAM-1 and P-selectin and also downregulated the protein expression levels of LC3, Atg12 and cytoplasmic polyadenylation element binding protein. CONCLUSIONS: Our results suggested that G. segetum induced liver injury with HSOS, and it was partly due to its ability to impair the autophagy pathway.

Anatomic and Clinical Pathology Characterization of Drug-Induced Sinusoidal Obstruction Syndrome (Veno-Occlusive Disease) in Cynomolgus Macaques.

Sinusoidal obstruction syndrome (SOS) is a unique form of liver injury that occurs after exposure to chemotherapeutic drugs and toxins. The diagnosis of SOS in humans remains a challenge as the clinical criteria have low specificity and there are no reliable noninvasive biomarkers. The mechanism of injury is believed to be damage to liver endothelial cells, primarily sinusoidal endothelial cells (SECs), which leads to sinusoidal dilation, central venous fibrosis, and/or nodular regeneration. Nonclinical data suggest that this uncommon liver toxicity can be recapitulated in cynomolgus monkeys, and it is critical that pathologists are familiar with its characteristic clinicopathologic features. Elevations in liver enzymes, in particular aspartate aminotransferase, associated with isolated thrombocytopenia, should raise the suspicion of SEC injury for specific drug classes. Characterization of liver microscopic findings in monkeys benefits from the use of appropriate stains, such as reticulin stain, and VEGFR2 and CD34 immunohistochemical (IHC) stains. CD41 IHC demonstrates platelet accumulation in injured sinusoids, the likely cause of thrombocytopenia commonly reported in SOS. In conclusion, this report provides a comprehensive characterization of the pathology findings of drug-induced SOS in monkeys with the objectives of ensuring appropriate nonclinical recognition of the liability and informing clinical development strategy and monitoring.

Bear bile powder attenuates senecionine-induced hepatic sinusoidal obstruction syndrome in mice / 中国天然药物

Hepatic sinusoidal obstruction syndrome (HSOS) via exposure to pyrrolizidine alkaloids (PAs) is with high mortality and there is no effective treatment in clinics. Bear bile powder (BBP) is a famous traditional animal drug for curing a variety of hepatobiliary diseases such as cholestasis, inflammation, and fibrosis. Here, we aim to evaluate the protective effect of BBP against HSOS induced by senecionine, a highly hepatotoxic PA compound. Our results showed that BBP treatment protected mice from senecionine-induced HSOS dose-dependently, which was evident by improved liver histology including reduced infiltration of inflammatory cells and collagen positive cells, alleviated intrahepatic hemorrhage and hepatic sinusoidal endothelial cells, as well as decreased conventional serum liver function indicators. In addition, BBP treatment lowered matrix metalloproteinase 9 and pyrrole-protein adducts, two well-known markers positively associated with the severity of PA-induced HSOS. Further investigation showed that BBP treatment prevents the development of liver fibrosis by decreasing transforming growth factor beta and downstream fibrotic molecules. BBP treatment also alleviated senecionine-induced liver inflammation and lowered the pro-inflammatory cytokines, in which tauroursodeoxycholic acid played an important role. What's more, BBP treatment also decreased the accumulation of hydrophobic bile acids, such as cholic acid, taurocholic acid, glycocholic acid, as well. We concluded that BBP attenuates senecionine-induced HSOS in mice by repairing the bile acids homeostasis, preventing liver fibrosis, and alleviating liver inflammation. Our present study helps to pave the way to therapeutic approaches of the treatment of PA-induced liver injury in clinics.

Metabolic Toxification of 1,2-Unsaturated Pyrrolizidine Alkaloids Causes Human Hepatic Sinusoidal Obstruction Syndrome: The Update.

Saturated and unsaturated pyrrolizidine alkaloids (PAs) are present in more than 6000 plant species growing in countries all over the world. They have a typical heterocyclic structure in common, but differ in their potential toxicity, depending on the presence or absence of a double bond between C1 and C2. Fortunately, most plants contain saturated PAs without this double bond and are therefore not toxic for consumption by humans or animals. In a minority of plants, however, PAs with this double bond between C1 and C2 exhibit strong hepatotoxic, genotoxic, cytotoxic, neurotoxic, and tumorigenic potentials. If consumed in error and in large emouns, plants with 1,2-unsaturated PAs induce metabolic breaking-off of the double bonds of the unsaturated PAs, generating PA radicals that may trigger severe liver injury through a process involving microsomal P450 (CYP), with preference of its isoforms CYP 2A6, CYP 3A4, and CYP 3A5. This toxifying CYP-dependent conversion occurs primarily in the endoplasmic reticulum of the hepatocytes equivalent to the microsomal fraction. Toxified PAs injure the protein membranes of hepatocytes, and after passing their plasma membranes, more so the liver sinusoidal endothelial cells (LSECs), leading to life-threatening hepatic sinusoidal obstruction syndrome (HSOS). This injury is easily diagnosed by blood pyrrolizidine protein adducts, which are perfect diagnostic biomarkers, supporting causality evaluation using the updated RUCAM (Roussel Uclaf Causality Assessment Method). HSOS is clinically characterized by weight gain due to fluid accumulation (ascites, pleural effusion, and edema), and may lead to acute liver failure, liver transplantation, or death. In conclusion, plant-derived PAs with a double bond between C1 and C2 are potentially hepatotoxic after metabolic removal of the double bond, and may cause PA-HSOS with a potential lethal outcome, even if PA consumption is stopped.

Oxaliplatin-induced hepatic sinusoidal obstruction syndrome.

Oxaliplatin (OXA) is a third-generation platinum anticancer drug that is mainly used for the treatment of metastatic colorectal cancer (CRC). Of note, hepatic sinusoidal obstruction syndrome (HSOS) induced by OXA has become a key concern for patients with CRC receiving chemotherapy with OXA in recent years. Splenomegaly, thrombocytopenia, abnormal liver function, and portal hypertension are some of the main clinical characteristics seen in patients with OXA-induced HSOS. Previous studies have suggested that oxidative stress, inflammatory damage, liver fibrosis, and platelet aggregation and adhesion may be involved in the pathogenesis of OXA-induced HSOS. Currently, there are no specific drugs for prevention and treatment of OXA-induced HSOS. In this review, we summarized the epidemiology, pathological characteristics, clinical predictive indicators, related mechanisms, possible prevention and treatment of OXA-related HSOS.

miR-511-3p promotes hepatic sinusoidal obstruction syndrome by activating hedgehog pathway via targeting Ptch1.

As a major complication of hematopoietic stem cell transplantation, the incidence of hepatic sinusoidal obstruction syndrome (HSOS) is as high as 70%. Previous evidence has demonstrated that miR-511-3p was involved in HSOS, but the mechanism remains unclear. This study aims to examine the mechanism underlying miR-511-3p regulating HSOS. Monocrotaline (MCT) was used to create an HSOS rat model and to treat liver sinusoidal endothelial cells (LSECs). Hematoxylin & eosin (H&E) and Masson staining were used to detect pathological changes in liver tissue. The expression of miR-511-3p and Hedgehog pathway-related proteins was assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The effect of miR-511-3p in regulating HSOS was investigated by 3-(4,5)-dimethylthiahiazo-2)-3,5-diphenytetrazoliumromide (MTT), enzyme-linked immunosorbent assay (ELISA) assay, and flow cytometry. Finally, the interaction between miR-511-3p and patched1 (Ptch1) was determined by luciferase reporter assay. The rats showed a typical HSOS phenotype, including LSEC damage, liver injury, and fibrosis after MCT administration. miR-511-3p was upregulated in hepatic tissue of rat HSOS model and MCT-induced LSECs. miR-511-3p directly targeted Ptch1 and suppressed Ptch1 expression to activate the Hedgehog signaling pathway. Depletion of miR-511-3p showed a protective effect against MCT-induced HSOS, as evidenced by decreased HSOS pathogenesis factors, matrix metalloproteinases-2 (MMP-2), matrix metalloproteinases-9 (MMP-9), tumor necrosis factor-α (TNF-α), and interleukin 1 ß (IL-1ß), and decreased LSEC apoptosis rates. Nevertheless, knockdown of Ptch1 reversed the protective effect of miR-511-3p depletion against MCT-induced LSEC injury and apoptosis. miR-511-3p aggravates HSOS by activating the Hedgehog signaling pathway through targeting Ptch1, and miR-511-3p may develop as the potential therapy for the treatment of HSOS.NEW & NOTEWORTHY miR-511-3p is upregulated in HSOS in vivo and in vitro models. miR-511-3p activates the Hedgehog pathway by directly targeting Ptch1. Knockdown of miR-511-3p shows a protective effect against LSEC injury and apoptosis via Hedgehog signaling pathway. Inhibition of Ptch1 reserves the effect of miR-511-3p knockdown on LSEC damage and apoptosis.

Characterization of liver injury induced by a pyrrolizidine alkaloid in rats.

BACKGROUND: Pyrrolizidine alkaloids (PAs) are common phytotoxins. PA intoxication is reported to cause severe acute liver damage, typically known as hepatic sinusoidal obstruction syndrome (HSOS), but it remains obscure whether the acute liver damage may progress into chronic liver disease characterized by hepatic fibrosis. PURPOSE: This study aims to characterize the biochemical markers of liver injury and histological features of regressive and progressive liver fibrosis, and to examine changes in hepatic gene expression that may underpin mechanisms of fibrogenesis in rats induced by retrorsine (RTS), a representative toxic PA. STUDY DESIGN/METHODS: Rats were gavaged with RTS via two dosing regimens, i.e. a single dose of 40 mg/kg (Group 1) and two doses of 40 mg/kg and 20 mg/kg on day 0 and day 7 (Group 2), respectively. Rats receiving one (Group 3) or two (Group 4) doses of vehicle served as negative controls. The animals were followed for up to 16 weeks by serum biochemical analyses and histological examination, and gene expression assays of liver tissues. RESULTS: Acute liver injury on day 2 manifested as HSOS, characterized by sinusoidal dilation, endothelial cell damage, and elevated serum alanine aminotransferase activity and bilirubin levels. In Group 1, mild liver fibrosis developed at sinusoids and perisinusoidal space surrounding the central veins at week 1 and 2, and thereafter, all liver injury resolved gradually. In Group 2, liver fibrosis progressed within the 16-week observation period. No apparent liver injury was observed in Groups 3 and 4. Compared with negative control groups, RTS induced myofibroblastic activation, TGF-ß1 signaling, and changes in expression of matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1). These dynamic changes differed in Groups 1 and 2, corresponding with the regression and progression of liver fibrosis, respectively, in these groups. CONCLUSION: This study has provided in-vivo proof of concept that "one hit" and "two hits" of RTS lead to acute resolving liver injury and chronic progressive liver fibrosis, respectively. These animal models may serve as powerful tools for studying RTS toxicology and related preventive and therapeutic strategies and as positive controls for studying other PA- and non-PA-induced liver injury.