Biliary fibrosis in microsurgical extrahepatic cholestasis in the rat

Mast cell-mediated splanchnic cholestatic inflammation

INTRODUCTION

Splanchnic mast cells increase in chronic liver and in acute-on-chronic liver diseases. We administered Ketotifen, a mast cell stabilizer, and measured the mast cells in the splanchnic organs of cholestatic rats.

MATERIAL AND METHODS

These groups were studied: sham-operated rats (S; n = 15), untreated microsurgical cholestasic rats (C; n = 20) and rats treated with Ketotifen: early (SK-e; n = 20 and CKe; n = 18), and late (SK-l; n = 15 and CK-l; n = 14).

RESULTS

The cholestatic rats showed systemic and splanchnic impairments, such as ascites, portal hypertension, and biliary proliferation and fibrosis. The rats also showed a splanchnic increase of TNF-α, IL-1β and MCP-1, and a reduction of IL-4, IL-10 and antioxidants. An increase of VEGF in the ileum and mesenteric lymphatic complex was associated with a liver reduction of TGF-β1. Ketotifen reduces the degree of hepatic insufficiency and the splanchnic inflammatory mediators, as well as VEGF and TGF-ß1 levels. Ketotifen also reduces the connective tissue mast cells in the mesenteric lymphatic complex of cholestatic rats, while increases the hepatic mucosal mast cells.

CONCLUSIONS

In cholestatic rats, Ketotifen improves liver function and ascites, and also reduces pro-inflammatory mediators in the splanchnic area. The decrease in connective tissue mast cells in the mesenteric lymphatic complex due to the administration of Ketotifen would lead to the improvement of the inflammatory splanchnic response, and consequently the abovementioned complications.

Utility of Diffusion-Weighted MRI to Detect Changes in Liver Diffusion in Benign and Malignant Distal Bile Duct Obstruction: The Influence of Choice of b-Values

PURPOSE

The study sought to evaluate the potential of diffusion-weighted magnetic resonance imaging to detect changes in liver diffusion in benign and malignant distal bile duct obstruction and to investigate the effect of the choice of b-values on apparent diffusion coefficient (ADC).

METHODS

Diffusion-weighted imaging was acquired with b-values of 200, 600, 800, and 1000 s/mm². ADC values were obtained in 4 segments of the liver. The mean ADC values of 16 patients with malignant distal bile duct obstruction, 14 patients with benign distal bile duct obstruction, and a control group of 16 healthy patients were compared.

RESULTS

Mean ADC values for 4 liver segments were lower in the malignant obstruction group than in the benign obstruction and control groups using b = 200 s/mm² (P < .05). Mean ADC values of the left lobe medial and lateral segments were lower in the malignant obstruction group than in the benign obstructive and control groups using b = 600 s/mm² (P < .05). Mean ADC values of the right lobe posterior segment were lower in the malignant and benign obstruction groups than in the control group using b = 1000 s/mm² (P < .05). Using b = 800 s/mm², ADC values of all 4 liver segments in each group were not significantly different (P > .05). There were no correlations between the ADC values of liver segments and liver function tests.

CONCLUSION

Measurement of ADC shows good potential for detecting changes in liver diffusion in patients with distal bile duct obstruction. Calculated ADC values were affected by the choice of b-values.

Decompensated liver cirrhosis and neural regulation of mesenteric vascular tone in rats: role of sympathetic, nitrergic and sensory innervations

We evaluated the possible alterations produced by liver cholestasis (LC), a model of decompensated liver cirrhosis in sympathetic, sensory and nitrergic nerve function in rat superior mesenteric arteries (SMA). The vasoconstrictor response to electrical field stimulation (EFS) was greater in LC animals. Alpha-adrenoceptor antagonist phentolamine and P2 purinoceptor antagonist suramin decreased this response in LC animals more than in control animals. Both non-specific nitric oxide synthase (NOS) L-NAME and calcitonin gene related peptide (CGRP) (8-37) increased the vasoconstrictor response to EFS more strongly in LC than in control segments. Vasomotor responses to noradrenaline (NA) or CGRP were greater in LC segments, while NO analogue DEA-NO induced a similar vasodilation in both experimental groups. The release of NA was not modified, while those of ATP, nitrite and CGRP were increased in segments from LC. Alpha 1 adrenoceptor, Rho kinase (ROCK) 1 and 2 and total myosin phosphatase (MYPT) expressions were not modified, while alpha 2B adrenoceptor, nNOS expression and nNOS and MYPT phosphorylation were increased by LC. Together, these alterations might counteract the increased splanchnic vasodilation observed in the last phases of decompensated liver cirrhosis.

The effect of curcumin on liver fibrosis in the rat model of microsurgical cholestasis

We aimed to determine the effects of curcumin on liver fibrosis and to clarify the role of nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) in a model of microsurgical cholestasis in the early stage of extrahepatic biliary atresia.

A novel rat model simulating biliary atresia after a Kasai operation

PURPOSE

The mechanisms of liver fibrosis in biliary atresia (BA) after a Kasai operation deserve studying to improve the clinical outcomes. This study aimed to create a rat model simulating BA after a Kasai operation.

METHODS

We inserted a polyethylene tube (PE10) into the common hepatic duct (CHD) and ligated the common bile duct (CBD) in 30 newborn rats and injected 95% ethanol into IHD at postoperative week-one (POW-1). The PE10 was removed at POW-3. The rats were sacrificed at POW-5. The CBD cystojejunostomy was performed on another 10 rats at POW-5.

RESULTS

The IHD obliteration and CBD dilatation were noted at POW-3 cholangiography before removal of the PE tube. The gross findings at sacrifice in the rats without cystojejunostomy included biliary fibrosis, CBD cyst, and IHD obliteration. The microscopic findings of the liver were like BA. Seven of the 10 rats with CBD cystojejunostomy were jaundice-free at POW-8. The fibrosis grade at POW-8 of the rats with CBD cystojejunostomy was significantly lower in the jaundice-free rats (Ishak fibrosis score, 3.4 ± 0.9 and 1.5 ± 0.3 in the jaundiced rats and jaundice-free rats, respectively, p < .05).

CONCLUSION

Based on our study, CBD cystojejunostomy five weeks after CBD ligation with ethanol injection into the IHD in newborn rats can provide a model for investigating mechanisms and treatments of liver fibrosis in BA after a Kasai operation.

A half century (1961-2011) of applying microsurgery to experimental liver research

The development of microsurgery has been dependent on experimental animals. Microsurgery could be a very valuable technique to improve experimental models of liver diseases. Microdissection and microsutures are the two main microsurgical techniques that can be considered for classifying the experimental models developed for liver research in the rat. Partial portal vein ligation, extrahepatic cholestasis and hepatectomies are all models based on microdissection. On the other hand, in portacaval shunts, orthotopic liver transplantation and partial heterotopic liver transplantation, the microsuture techniques stand out. By reducing surgical complications, these microsurgical techniques allow for improving the resulting experimental models. If good experimental models for liver research are successfully developed, the results obtained from their study might be particularly useful in patients with liver disease. Therefore experimental liver microsurgery could be an invaluable way to translate laboratory data on liver research into new clinical diagnostic and therapeutic strategies.

Trolox mitigates fibrosis in a bile duct ligation model

Several studies suggest that free radicals may play a role in cholestatic liver injury. The aim of this work was to evaluate the role of trolox in chronic bile duct ligation (BDL). Liver injury was induced by 28-day BDL to male Wistar rats. Animals were divided in four groups of six rats. Trolox was administered daily (50 mg/kg, p.o.). Alanine aminotransferase (ALT) was quantified in serum. Fibrosis was assessed measuring liver hydroxyproline content. Reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, catalase (CAT), and glutathione peroxidase (GPx) activities were measured in liver. Transforming growth factor-β (TGF-β), interleukin-6 (IL-6), and interleukin-10 (IL-10) were determined by western blot and quantified densitometrically. Our results show that trolox treatment in BDL rats prevented the increase in ALT. Collagen was increased by chronic BDL, but trolox administration preserved the normal collagen concentration. BDL produced high levels of the cytokine TGF-β1, IL-6, and IL-10 levels. Trolox administration was effective to partially prevent the increase of TGF-β1 and IL-6, and it was able to further augment the levels of IL-10. Oxidative stress (assessed by lipid peroxidation and liver glutathione content) was increased by BDL; this process was normalized by trolox. The activities of CAT and GPx were altered by BDL, and trolox prevented these events. We found that there is a close relationship between cholestatic liver damage and oxidative stress generation, and this was effectively prevented by trolox. Our study shows that the beneficial effects of trolox are because of its important antioxidant and immunomodulatory properties.

The interstitial lymphatic peritoneal mesothelium axis in portal hypertensive ascites: when in danger, go back to the sea

Portal hypertension induces a splanchnic and systemic low-grade inflammatory response that could induce the expression of three phenotypes, named ischemia-reperfusion, leukocytic, and angiogenic phenotypes.During the splanchnic expression of these phenotypes, interstitial edema, increased lymph flow, and lymphangiogenesis are produced in the gastrointestinal tract. Associated liver disease increases intestinal bacterial translocation, splanchnic lymph flow, and induces ascites and hepatorenal syndrome. Extrahepatic cholestasis in the rat allows to study the worsening of the portal hypertensive syndrome when associated with chronic liver disease. The splanchnic interstitium, the mesenteric lymphatics, and the peritoneal mesothelium seem to create an inflammatory pathway that could have a key pathophysiological relevance in the production of the portal hypertension syndrome complications. The hypothetical comparison between the ascitic and the amniotic fluids allows for translational investigation. From a phylogenetic point of view, the ancestral mechanisms for amniotic fluid production were essential for animal survival out of the aquatic environment. However, their hypothetical appearance in the cirrhotic patient is considered pathological since ultimately they lead to ascites development. But, the adult human being would take advantage of the potential beneficial effects of this “amniotic-like fluid” to manage the interstitial fluids without adverse effects when chronic liver disease aggravates.

Bile duct ligation: step-by-step to cholangiocyte inflammatory tumorigenesis

Chronic liver inflammation after murine bile duct ligation could evolve according to three interrelated phenotypes, which would have different metabolic, functional and histologic characteristics. Liver injury secondary to extrahepatic cholestasis would induce an early ischemic-reperfusion phenotype with cholangiocyte depolarization, abnormal ion transport, hypometabolism with anaerobic glycolysis and hepatocytic apoptosis. This phenotype, in turn, could trigger the switch to a leukocytic phenotype by the cholangiocytes, with an intense anaplerotic activity, hypermetabolism, extracellular matrix degradation and moderated proliferation to create a pseudotissue with metabolic autonomy and paracrine functions. In the long-term cholestasis-drive tumorigenesis, the tumorous tissue would principally consist of cholangiocyte parenchyma, with an impressive biosynthetic activity through the tricarboxylic cell cycle. In terms of the tumorous stroma, made up by fibroplasia and angiogenesis, it would favor the tumor trophism. In conclusion, the great intensity and persistence in the expression of these phenotypes by the cholestatic cholangiocyte would favor chronic inflammatory tumorigenesis.

Splanchnic Th(2) and Th(1) cytokine redistribution in microsurgical cholestatic rats

BACKGROUND

Long-term extrahepatic cholestasis in the rat induces ductular proliferation and fibrosis in the liver, portal hypertension, splenomegaly, portosystemic collateral circulation, and ascites. These splanchnic alterations could have an inflammatory pathophysiology.

MATERIAL AND METHODS

We measured serum levels of hepatobiliary injury markers and the acute phase proteins, alpha-1-major acid protein (alpha(1)-MAP) and alpha-1-acid glycoprotein (alpha(1)-GPA) in rats 6 wk after microsurgical extrahepatic cholestasis. We also assayed Th(1) (TNF-alpha and IL-1beta) and Th(2) (IL-4 and IL-10) cytokine levels in the liver, ileum, spleen, and mesenteric lymph complex by enzyme-linked immunosorbent assay (ELISA) techniques. Liver fibrosis was measured by Sirius red stain and by using an image system computer-assisted method and mast cell liver infiltration by Giemsa stain.

RESULTS

The cholestatic rats showed an increase (P<0.001) in serum levels of bile acids, total and direct bilirubin, AST, ALT, AST/ALT index, gamma-GT, alkaline phosphatase, alpha(1)- MAP, alpha(1)-GPA, and LDH (P<0.05) in relation to sham-operated rats. TNF-alpha, IL-1beta, IL-4, and IL-10 increased in the ileum (P<0.01) and mesenteric lymph complex (P<0.001), and decreased in the liver (P<0.001). A marked bile proliferation associated with fibrosis (P<0.001) and mast cell infiltration was also shown in the liver of cholestatic rats.

CONCLUSION

The splanchnic redistribution of cytokines, with an increase of Th(1) and Th(2) production in the small bowel and in the mesenteric lymph complex, supports the key role of inflammatory mechanisms in rats with secondary biliary fibrosis.

The value of microsurgery in liver research

The use of an operating microscope in rat liver surgery makes it possible to obtain new experimental models and improve the already existing macrosurgical models. Thus, microsurgery could be a very valuable technique to improve experimental models of hepatic insufficiency. In the current review, we present the microsurgical techniques most frequently used in the rat, such as the portacaval shunt, the extrahepatic biliary tract resection, partial and total hepatectomies and heterotopic and orthotopic liver transplantation. Hence, reducing surgical complications allows for perfecting the resulting experimental models. Thus, liver atrophy related to portacaval shunt, prehepatic portal hypertension secondary to partial portal vein ligation, cholestasis by resection of the extrahepatic biliary tract, hepatic regeneration after partial hepatectomies, acute liver failure associated with subtotal or total hepatectomy and finally complications derived from preservation or rejection in orthotopic and heterotopic liver transplantation can be studied in more standardized experimental models. The results obtained are therefore more reliable and facilitates the flow of knowledge from the bench to the bedside. Some of these microsurgical techniques, because of their simplicity, can be performed by researchers without any prior surgical training. Other more complex microsurgical techniques require in-depth surgical training. These techniques are ideal for achieving a complete surgical training and more select microsurgical models for hepatology research.

Experimental obstructive cholestasis: the wound-like inflammatory liver response

Obstructive cholestasis causes hepatic cirrhosis and portal hypertension. The pathophysiological mechanisms involved in the development of liver disease are multiple and linked. We propose grouping these mechanisms according to the three phenotypes mainly expressed in the interstitial space in order to integrate them.Experimental extrahepatic cholestasis is the model most frequently used to study obstructive cholestasis. The early liver interstitial alterations described in these experimental models would produce an ischemia/reperfusion phenotype with oxidative and nitrosative stress. Then, the hyperexpression of a leukocytic phenotype, in which Kupffer cells and neutrophils participate, would induce enzymatic stress. And finally, an angiogenic phenotype, responsible for peribiliary plexus development with sinusoidal arterialization, occurs. In addition, an intense cholangiocyte proliferation, which acquires neuroendocrine abilities, stands out. This histopathological finding is also associated with fibrosis.It is proposed that the sequence of these inflammatory phenotypes, perhaps with a trophic meaning, ultimately produces a benign tumoral biliary process - although it poses severe hepatocytic insufficiency. Moreover, the persistence of this benign tumor disease would induce a higher degree of dedifferentiation and autonomy and, therefore, its malign degeneration.