Morphological and serum hyaluronic acid, laminin and type IV collagen changes in dimethylnitrosamine-induced hepatic fibrosis of rats

Epigallocatechin-3-gallate inhibits osteopontin expression and prevents experimentally induced hepatic fibrosis

Osteopontin (OPN) is a matricellular cytokine and a stress-induced profibrogenic molecule that promotes activation of stellate cells during the pathogenesis of hepatic fibrosis. We studied the protective effects of epigallocatechin-3-gallate (EGCG) to suppress oxidative stress, inhibit OPN expression, and prevent experimentally induced hepatic fibrosis. Liver injury was induced with intraperitoneal injections of N-nitrosodimethylamine (NDMA) in a dose of 1 mg/100 g body weight on 3 consecutive days of a week for 28 days. A group of rats received 0.2 mg EGCG/100 g body weight orally everyday during the study. The animals were sacrificed on day 28th from the beginning of exposure. Serum levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid were measured. Immunohistochemistry and/or real-time PCR were performed for α-SMA, 4-HNE, OPN, collagen type I, and type III. Serial administrations of NDMA produced well developed fibrosis and early cirrhosis in rat liver. Treatment with EGCG significantly reduced serum/plasma levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid and prevented deposition of collagen fibers in the hepatic tissue. Protein and/or mRNA levels demonstrated marked decrease in the expression of α-SMA, 4-HNE, OPN, collagen type I, and type III. Treatment with EGCG prevented excessive generation of reactive oxygen species, suppressed oxidative stress, significantly reduced serum and hepatic OPN levels, and markedly attenuated hepatic fibrosis. The results indicated that EGCG could be used as a potent therapeutic agent to prevent hepatic fibrogenesis and related adverse events.

Animal and Organoid Models of Liver Fibrosis

Liver fibrosis refers to the process underlying the development of chronic liver diseases, wherein liver cells are repeatedly destroyed and regenerated, which leads to an excessive deposition and abnormal distribution of the extracellular matrix such as collagen, glycoprotein and proteoglycan in the liver. Liver fibrosis thus constitutes the pathological repair response of the liver to chronic injury. Hepatic fibrosis is a key step in the progression of chronic liver disease to cirrhosis and an important factor affecting the prognosis of chronic liver disease. Further development of liver fibrosis may lead to structural disorders of the liver, nodular regeneration of hepatocytes and the formation of cirrhosis. Hepatic fibrosis is histologically reversible if treated aggressively during this period, but when fibrosis progresses to the stage of cirrhosis, reversal is very difficult, resulting in a poor prognosis. There are many causes of liver fibrosis, including liver injury caused by drugs, viral hepatitis, alcoholic liver, fatty liver and autoimmune disease. The mechanism underlying hepatic fibrosis differs among etiologies. The establishment of an appropriate animal model of liver fibrosis is not only an important basis for the in-depth study of the pathogenesis of liver fibrosis but also an important means for clinical experts to select drugs for the prevention and treatment of liver fibrosis. The present study focused on the modeling methods and fibrosis characteristics of different animal models of liver fibrosis, such as a chemical-induced liver fibrosis model, autoimmune liver fibrosis model, cholestatic liver fibrosis model, alcoholic liver fibrosis model and non-alcoholic liver fibrosis model. In addition, we also summarize the research and application prospects concerning new organoids in liver fibrosis models proposed in recent years. A suitable animal model of liver fibrosis and organoid fibrosis model that closely resemble the physiological state of the human body will provide bases for the in-depth study of the pathogenesis of liver fibrosis and the development of therapeutic drugs.

Beet root (Beta vulgaris) protects lipopolysaccharide and alcohol-induced liver damage in rat

The purpose of this study was to investigate the protective effects of beet root (Beta vulgaris var. rubra) in lipopolysaccharide (LPS) and alcohol induced liver damage. Beta vulgaris ethanol extract (BVEE) showed good antioxidant activity in the contents of polyphenol and flavonoid compounds, and the electron-donating ability and ABTS⁺ radical scavenging activity. As for anti-inflammatory effect in RAW 264.7 cells, inhibition rate of nitric oxide production was increased in dose dependent manner. In hepatotoxicity model induced by LPS and alcohol in rat, BVEE significantly decreased serum AST, ALT and γ-GTP concentrations in a dose-dependent manner. The histopathological changes after H&E staining showed that fat accumulation and inflammatory cell infiltration were decreased by BVEE. The collagen fibers around the central lobule observed by Masson's trichrome staining were also decreased by BVEE. In addition, as for the immunohistochemical staining and Transmission electron microscopy, BVEE improved morphological characteristics of damaged liver lesion. The increased mRNA expressions of NF-κB, MAPK1, MAPK3, CYP2E1, and α-SMA were significantly decreased in BVEE treated group. These results indicated that BVEE would have protective effects in hepatotoxicity by altering various indicators related to the liver damage induced by LPS or alcohol.

Restorative effects of hydroxysafflor yellow A on hepatic function in an experimental regression model of hepatic fibrosis induced by carbon tetrachloride

Hepatic fibrosis is a reversible pathological process, in which fibrotic tissue is excessively deposited in the liver during the repair process that follows hepatic injury. Early prevention or treatment of hepatic fibrosis has great significance on the treatment of chronic hepatic diseases. Hydroxysafflor yellow A (HSYA) is a water-soluble monomer extracted from safflower, which serves numerous pharmacological roles. However, it remains to be elucidated how HSYA regulates hepatic fibrogenesis. The aim of the present study was to reveal the possible mechanisms underlying the effects of HSYA on the prevention and treatment of hepatic fibrosis. A rat model of hepatic fibrosis was established in the present study, and the rats were administered various doses of HSYA. The effects of HSYA on pathological alterations of the liver tissue in rats with hepatic fibrosis were observed using hematoxylin-eosin staining and Masson staining. In order to explore the anti-hepatic fibrosis effects and underlying mechanisms of HSYA, serum levels, and hepatic function and hepatic fibrosis indices were evaluated. The results demonstrated that HSYA can improve the general condition of rats with hepatic fibrosis and relieve cellular swelling of the liver, fatty degeneration, necrosis, inflammatory cell infiltration and fibroplastic proliferation. Subsequent to administration of HSYA, globulin was increased during hepatic fibrosis caused by tetrachloromethane. However, total cholesterol, triglyceride, alanine aminotransferase, aspartate aminotransferase and levels of hyaluronic acid, laminin, procollagen III N-terminal peptide, collagen type IV and hydroxyproline were significantly reduced. The results additionally demonstrated that HSYA could enhance superoxide dismutase activity and reduce malondialdehyde levels, inhibiting lipid peroxidation caused by free radicals.

Intraperitoneal exposure of whitefish to microcystin-LR induces rapid liver injury followed by regeneration and resilience to subsequent exposures

To date, there has been no systematic approach comprehensively describing the sequence of pathological changes in fish during prolonged exposure to microcystin-LR (MC-LR). Towards this aim, juvenile whitefish individuals received an intraperitoneal injection with pure MC-LR, and the injection was repeated every week to maintain continuous exposure for 28days. During the exposure period, growth and condition of the fish were assessed based on biometric measurements. Additionally, selected biochemical markers were analysed in the fishes' blood, and their livers were carefully examined for morphological, ultrastructural, and molecular changes. The higher dose of MC-LR (100μg·kg^-1) caused severe liver injury at the beginning of the exposure period, whereas the lower dose (10μg·kg^-1) caused less, probably reversible injury, and its effects began to be observed later in the exposure period. These marked changes were accompanied by substantial MC-LR uptake by the liver. However, starting on the 7th day of exposure, cell debris began to be removed by phagocytes, then by 14th day, proliferation of liver cells had markedly increased, which led to reconstruction of the liver parenchyma at the end of the treatment. Surprisingly, despite weekly-repeated intraperitoneal injections, MC-LR did not accumulate over time of exposure which suggests its limited uptake in the later phase of exposure. In support, mRNA expression of the membrane transport protein oatp1d was decreased at the same time as the regenerative processes were observed. Our study shows that closing of active membrane transport may serve as one defence mechanism against further MC-LR intoxication.

Efficacy of Dietary Lipid Control in Healing High-Fat and High-Cholesterol Diet-Induced Fibrotic Steatohepatitis in Rats

Nonalcoholic steatohepatitis is related to lifestyle, particularly to dietary habits. We developed diet-induced fibrotic steatohepatitis model stroke-prone spontaneously hypertensive 5/Dmcr (SHRSP5/Dmcr) rats showing steatosis, hepatic inflammation, and severe fibrosis induced by high-fat and -cholesterol (HFC) diet feeding. We aimed to clarify the efficacy of dietary intervention on the disease before and after the appearance of fibrosis. Male SHRSP5/Dmcr rats were divided into 9 groups; of these, 6 groups were fed control or HFC diet for several weeks and the remaining 3 groups represented the dietary intervention groups, which were fed the control diet after HFC diet feeding for 2 (before the appearance of fibrosis) or 8 (after the appearance of fibrosis) weeks. Dietary intervention before the appearance of fibrosis significantly improved the steatosis and reset the increased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and serum total cholesterol (TC) levels. However, dietary intervention after the appearance of fibrosis was unable to reset the levels of hepatic TC, serum ALT, and fibrogenesis-related markers and had only a minor influence on hepatic fibrosis, although it reset the increased expression of transforming growth factor (TGF)-β1 and α-smooth muscle actin (SMA). It was noted that dietary intervention improved the increased AST levels; however, aggregated CD68-positive cells were still observed around the fibrosis area, which may be related to the findings of inflammatory cytokine mRNAs. Taken together, dietary intervention for fibrotic steatohepatitis improved steatosis, although it could not completely improve fibrosis.

Green tea extract therapy diminishes hepatic fibrosis mediated by dual exposure to carbon tetrachloride and ethanol: A histopathological study

The aim of the present study was to investigate the hepatoprotective effect of green tea extract (GTE) against the hepatic fibrosis induced by carbon tetrachloride (CCl₄), ethanol, and dual exposure to CCl₄ plus ethanol in rats. In particular, an investigation of the three-dimensional architecture was conducted using scanning electron microscopy. Various techniques revealed that hepatic fibrosis with intermingled fibers was located between cells in the CCl₄, ethanol and combined CCl₄ plus ethanol groups. The hepatic fibrosis differed among the ethanol, CCl₄ and CCl₄ plus ethanol groups in terms of the type, thickness and distribution of fibers. The fibrotic lesions virtually disappeared in all the groups after 25 days of treatment with GTE, returning the architecture of the liver tissue to its normal status. The rats were also found to regain normal body weight and fur color, which had earlier been discolored due to weight loss. The autopsy results also showed that the animal livers returned to the normal shape and color. GTE demonstrated the same clear action in attenuating the hepatofibrosis for all three inducing treatments, by impairing collagen fibers, eliminating lipid peroxidation and returning the liver architecture to normal. GTE presents a safe therapeutic strategy for hepatic fibrosis.

Bone marrow-derived stem cells ameliorate hepatic fibrosis by down-regulating interleukin-17

BACKGROUND

Accumulating evidences have identified the immunoregulatory features of stem cells. In this study, the immunoregulation of bone marrow-derived stem cells (BMSCs) transplanted into patients with HBV-related decompensated cirrhosis and mouse model of liver injury induced by carbon tetrachloride (CCl4) administration was observed.

RESULTS

Compared with healthy controls, patients with HBV-related decompensated cirrhosis showed significantly higher levels of TNF-alpha, IL-12, TGF-beta1, IL-17, and IL-8. However, only IL-17 was markedly decreased after autologous BMSCs transplantation during their follow-up. The same results were found in the CCl4-treated mice. Furthermore, we found that exogenous IL-17 partly abolished the therapeutic effect of BMSCs whereas IL-17-specific antibody promoted improvement of liver injury in CCl4-treated mice, resembling the therapeutic effect of BMSCs transplantation.

CONCLUSIONS

These data suggested that BMSCs transplantation induces a decrease of IL-17 level, which at least in part delineates the mechanisms of stem cells-mediated therapeutic benefit on liver disease.

Inhibition of hepatic fibrosis with artificial microRNA using ultrasound and cationic liposome-bearing microbubbles

We sought to investigate the antifibrotic effects of an artificial microRNA (miRNA) targeting connective tissue growth factor (CTGF) using the ultrasound-targeted cationic liposome-bearing microbubble destruction gene delivery system. Cationic liposomes were conjugated with microbubbles using a biotin-avidin system. Plasmids carrying the most effective artificial miRNA sequences were delivered by ultrasound-targeted cationic liposome-bearing microbubble destruction gene delivery system to rats with hepatic fibrosis. The results show that this method of gene delivery effectively transported the plasmids to the rat liver. The artificial miRNA reduced hepatic fibrosis pathological alterations as well as the protein and mRNA expressions of CTGF and transforming growth factor β1. Furthermore, the CTGF gene silencing decreased the levels of type I collagen and α-smooth muscle actin (P<0.01). These data suggest that delivery of an artificial miRNA targeted against CTGF using ultrasound-targeted cationic liposome-bearing microbubble destruction may be an efficacious therapeutic method to ameliorate hepatic fibrosis.

Curative propensity of green tea extract towards hepatic fibrosis induced by CCl(4): A histopathological study

Hepatic fibrosis constitutes a serious insult to the liver, with a substantial negative impact on the quality of life of such patients worldwide. It is a consequence of severe liver damage and occurs as the result of several factors. Chronic alcoholism is the most common cause. Fibrosis also results from chronic viral hepatitis and autoimmune hepatitis. Prolonged exposure to environmental toxins such as carbon tetrachloride (CCl(4)) can also lead to fibrosis. In the present study, the hepato-protective effects of green tea extract (GTE) on hepatic fibrosis in a rat liver CCl(4)-induced fibrosis model were examined histologically, 3-dimensionally and biochemically. GTE was prepared from dried green tea leaves and lyophilized. Male albino rats (n=20) weighing 200-250 g were divided into four groups: GI, control; GII, administered 50 mg/kg GTE dissolved in physiological saline daily for four weeks; GIII, administered 40% CCl(4) (1 ml/kg body weight) by subcutaneous injection daily for four weeks; and GIV, treated as GIII, followed by 50 mg/kg GTE dissolved in physiological saline daily for 4 weeks. Histology and 3-dimensional scanning electron microscopy showed hepatic fibrosis with intermingled fibers located between cells in the liver tissues of the CCl(4)-treated rats. Fibrotic lesions virtually disappeared after four weeks of treatment with GTE, returning the architecture of liver tissue back to its normal state. Also, the levels of the hepatic enzymes alanine aminotranferase and aspartate aminotransferase returned to their normal levels after treatment with GTE. The rats were found to regain their normal body weight and their fur color, which had faded due to weight loss. The autopsy results showed the animal liver returning to normal shape and color. Thus, green tea extract is a potent treatment for hepatic fibrosis caused by CCl(4) in this animal model.

Development of novel rat model for high-fat and high-cholesterol diet-induced steatohepatitis and severe fibrosis progression in SHRSP5/Dmcr

OBJECTIVES

Patients with nonalcoholic fatty liver disease are increasing worldwide, and preventive measures are an urgent need and primary concern today.

AIM

This study aimed to develop and clarify the usefulness of the SHRSP5/Dmcr rat, derived from a stroke-prone spontaneously hypertensive rat, as a novel animal model for time-course analysis of steatohepatitis and the severe fibrosis progression often observed in the disease.

METHODS

Ten-week-old male SHRSP5/Dmcr rats were divided into six groups: half were fed a high-fat and high-cholesterol-containing diet (HFC diet), and the others the control, stroke-prone (SP) diet for 2, 8, and 14 weeks.

RESULTS

The HFC diet significantly increased serum transaminase and gamma glutamyl transpeptidase activities, tumor necrosis factor alpha levels, and serum and hepatic total cholesterol levels over time. In contrast, this diet decreased serum albumin, glucose, and adiponectin levels throughout or the later stage of the feeding period, but did not influence serum insulin levels. Histopathologically, the HFC diet increased microvesicular steatosis, and focal or spotty necrosis with lymphocyte infiltrations were observed in the liver at 2 weeks, macrovesicular steatosis, ballooned hepatocytes with Mallory-Denk body formation in some, and multilobular necrosis and fibrosis at 8 weeks. Interestingly, this fibrosis formed a honeycomb network at 14 weeks. These changes are very similar to those observed in patients with non-alcoholic steatohepatitis.

CONCLUSIONS

SHRSP5/Dmcr rats appear to be a useful model for analyzing the time-dependent changes of HFC diet-induced steatohepatitis and fibrosis progression.

The significance of CD14+ monocytes in peripheral blood stem cells for the treatment of rat liver cirrhosis

BACKGROUND AIMS

Circulating monocytes have been exploited as an important progenitor cell resource for hepatocytes in vitro and are instrumental in the removal of fibrosis. We investigated the significance of monocytes in peripheral blood stem cells (PBSC) for the treatment of liver cirrhosis.

METHODS

Rat CD14+ monocytes in PBSC were mobilized with granulocyte-colony-stimulating factor (G-CSF) and harvested by magnetic cell sorting (MACS). Female rats with carbon tetrachloride (CCl₄-induced liver cirrhosis were injected CM-DiI-labeled monocytes, CD14⁻ cells (1 x 10⁷ cells/rat) or saline via the portal vein.

RESULTS

Rat CD14+ and CD11b+ monocytes in PBSC were partly positive for CD34, CD45, CD44, Oct3/4 and Sox2, suggesting monocytes with progenitor capacity. Compared with CD14⁻ cell-infused and saline-injected rats, rats undergoing monocyte transplantation showed a gradually increased serum albumin level and decreased portal vein pressure, resulting in a significantly improved survival rate. Meanwhile, monocyte transplantation apparently attenuated liver fibrosis by analysis for fibronectin, α2-(1)-procollagen, α-smooth muscle aorta (SMA) and transforming growth factor (TGF)-β. Transplanted monocytes mainly clustered in periportal areas of liver, in which 1.8% cells expressed hepatocyte marker albumin and CK18. The expression level of hepatocyte growth factor (HGF), TGF-α, extracellular matrix (EGF) and vascular endothelial growth factor (VEGF) increased, while monocyte transplantation enhanced hepatocyte proliferation. On the other hand, the activities and expression of matrix metalloproteinases (MMP) increased while tissue inhibitor of metalloproteinase (TIMP)-1 expression significantly reduced in monocyte-transplanted livers. Some transplanted monocytes expressed MMP-9 and -13.

CONCLUSIONS

The data suggest that CD14+ monocytes in PBSC contribute to hepatocyte regeneration and extracellular matrix (ECM) remodeling in rat liver cirrhosis much more than CD14⁻ cells, and might offer a therapeutic alternative for patients with liver cirrhosis.

New proposal for the staging of nonalcoholic steatohepatitis: evaluation of liver fibrosis on Gd-EOB-DTPA-enhanced MRI

PURPOSE

We investigated whether the gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI was useful for nonalcoholic steatohepatitis (NASH) staging based on the severity of liver fibrosis.

MATERIALS AND METHODS

Twenty-one male Sprague-Dawley rats aged 7 weeks, weighing about 150g in NASH group were fed a choline-deficient diet for 4, 7 or 10 weeks, and seven rats in the control group were fed a standard diet (n=7). After the feeding period, the rats were subjected to contrast-enhanced MRI (2D-FLASH; TR/TE=101/2.9ms, flip angle 90 degrees ). Gd-DTPA (0.1mmol Gd/kg) and Gd-EOB-DTPA (0.025mmol Gd/kg) were injected at 24-h intervals, and the speed of contrast injection was 1mL/s. Signal intensities of the liver were measured and the relative enhancement (RE), the time of maximum RE (T(max)) and elimination half-life of RE (T(1/2)) in the liver were compared. The fibrosis rate (%) was calculated with the following formula: fibrosis/whole areax100.

RESULTS

The fibrosis rates of each group were as follows: 0.52, 0.79, 2.84, and 0.50% (4, 7, 10 weeks and control groups). The fibrosis rate of the 10 weeks group was significantly higher than the control and 4 or 7 weeks groups. Although there was no difference between the T(max) and T(1/2) of each group after Gd-DTPA injection, the T(max) and T(1/2) of the 10 weeks group were significantly prolonged in comparison with the control and 4 or 7 weeks groups after Gd-EOB-DTPA injection (p<0.01). There was a significant correlation between the fibrosis rate and T(max) or T(1/2) after Gd-EOB-DTPA injection (r=0.90 or 0.97).

CONCLUSION

It was possible to assess the progress of liver fibrosis in NASH by evaluating the signal intensity-time course on Gd-EOB-DTPA-enhanced MRI.

Decreased hepatic nerve fiber innervation in patients with liver cirrhosis

BACKGROUND/AIMS

Hepatic nerve innervation plays important roles in hepatic metabolism and hemodynamic mechanisms. We compared the distribution patterns of hepatic nerves between normal livers and two liver diseases to elucidate the effects of liver disease on the distribution of hepatic nerves.

METHODS

Tissue specimens were obtained by ultrasonography-guided needle biopsies from 10 normal controls, 74 patients with chronic hepatitis (CH), and 35 patients with liver cirrhosis (LC). The obtained specimens were immunohistochemically stained using antibodies for S-100 protein and alpha-smooth-muscle actin (alpha-SMA). The degree of the expression in liver tissues was quantified by manual counting of positively stained nerve fibers under light microscopy. The serum hyaluronic acid level was assayed in all subjects to evaluate hepatic fibrosis. Electron microscopy examinations were also performed.

RESULTS

The hepatic nerve innervation was significantly lower in LC than in normal controls, as indicated by S-100 protein staining. alpha-SMA and hyaluronic acid levels were higher in LC and CH than in normal controls. Electron microscopy revealed that unmyelinated nerve fiber bundles in the intralobar connective tissue coursed in the vicinity of hepatic triads.

CONCLUSIONS

These results suggest that hepatic nerve innervation can be decreased by hepatic inflammatory responses and/or fibrotic changes in LC patients. Further study is needed to clarify this observation.

Potential of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for differential diagnosis of nonalcoholic steatohepatitis and fatty liver in rats using magnetic resonance imaging

RATIONALE AND OBJECTIVES

To investigate the potential of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for the differential diagnosis of nonalcoholic steatohepatitis (NASH) and fatty liver (FL).

METHODS

Twenty-one male rats were divided into 3 groups. Seven rats in the NASH group were fed a choline-deficient diet for 10 weeks, and the 7 rats in the FL group were fed a standard diet also containing 1% (wt/wt) orotic acid for 4 weeks. As a control, 7 rats were fed a standard diet. After the feeding period, all rats were subjected to contrast-enhanced dynamic and delayed MRI with a 2D-FLASH technique. Gd-DTPA (0.1 mmol Gd/kg) and Gd-EOB-DTPA (0.025 mmol Gd/kg) were injected into the tail vein at 24-hour intervals. Signal intensities of the liver were measured for each MR image and the relative enhancement (RE) was calculated. In addition, the time of maximum RE (Tmax) and the half-life of RE (T1/2) in liver were compared. After MRI, the liver was histologically analyzed to evaluate steatosis, hepatitis, and fibrosis.

RESULTS

Diffuse macrovesicular steatosis and severe fibrosis were observed in the NASH group, whereas diffuse microvesicular steatosis and rare fibrosis were observed in the FL group. Immediately after the Gd-DTPA injection, the RE in the liver of each group temporarily increased, and thereafter, rapid RE reduction was observed. However, a continuous increase and subsequent slow reduction of RE were induced after the Gd-EOB-DTPA injection. Although there was no difference between the Tmax and T1/2 of each group after the Gd-DTPA injection, Tmax and T1/2 of the NASH group were significantly prolonged in comparison with FL and control groups after the Gd-EOB-DTPA injection (P < 0.01).

CONCLUSIONS

It was possible to differentiate NASH and FL by evaluating the SI time course on Gd-EOB-DTPA enhanced MRI.