An improved rat model of obstructive jaundice and its reversal by internal and external drainage

A novel ameliorated rat model of reversible obstructive jaundice

Obstructive jaundice is a common clinical symptom generally caused by bile duct stones, inflammatory hyperplasia, and tumors. It is characterized by hyperbilirubinemia and may trigger a variety of complications such as hypotension, kidney injury, endotoxemia, multiple organ dysfunction syndrome, and even death (Pavlidis and Pavlidis, 2018; Liu et al., 2021). Relieving bile duct obstruction and providing adequate drainage have been considered as the most effective therapies for obstructive jaundice. However, it has not yet been established whether it is beneficial to treat affected patients by pre-operative biliary drainage (Blacker et al., 2021). Moreover, the pathophysiological changes or mechanisms associated with the reversal of organ function following the relief of bile-duct obstruction are unclear (Huang et al., 2004). Therefore, it is necessary to establish an experimental model of reversible obstructive jaundice to simulate biliary drainage in clinical practice.

Expression of TLR2 and TLR5 in distal ileum of mice with obstructive jaundice and their role in intestinal mucosal injury

INTRODUCTION

The aim was to investigate the expression of TLR2 and TLR5 in the distal ileum of mice with obstructive jaundice (OJ) and their role in intestinal mucosal injury.

MATERIAL AND METHODS

A total of 100 male C57BL/6J mice were randomly assigned to two groups: (I) sham operation (SH); (II) bile duct ligation (BDL). The mice were respectively sacrificed before operation and on the 1^st, 3^rd, 5^th and 7^th days after operation to collect specimens. Various indicators were detected by PCR, immunohistochemistry and other methods.

RESULTS

TLR2 was increased gradually with the extension of OJ time in the BDL group (p < 0.05). However, the changes in the expression of TLR5 were not obvious at different time points. The amount of Bifidobacteria and Lactobacillus showed downward trends in intestinal tract of the BDL group. Furthermore, the amount of Escherichia coli was increased in intestinal tract of the BDL group. The pathological score of intestinal mucosa and the expression of NF-κB increased gradually in the BDL group with the extension of OJ time. There were positive correlations between the pathological score of intestinal mucosa and expressions of TLR2(r = 0.767, p < 0.05) and NF-κB (r = 0.817, p < 0.05) in BDL group. NF-κB expression was positively correlated with TLR2 expression(r = 0.706, p < 0.05).

CONCLUSIONS

Disturbance of intestinal flora caused by OJ could increase the expression of NF-κB via up-regulating the expression of TLR2 to activate the downstream signaling pathway, thus aggravated the injury of intestinal mucosa.

Intestinal mucosal injury induced by obstructive jaundice is associated with activation of TLR4/TRAF6/NF-κB pathways

OBJECTIVES

To investigate the role of TLR4/TRAF6/NF-κB pathways in intestinal mucosal injury induced by obstructive jaundice (OJ).

METHODS

A total of 100 male C57BL/6J mice were randomly assigned to two groups: (I) sham operation (SH); (II) OJ. The mice were sacrificed before operation and on the 1st, 3rd, 5th and 7th day after operation. The blood and terminal ileum were simultaneously collected under the aseptic condition for further detection.

RESULTS

In the SH group, TLR4 protein and mRNA rarely expressed in the intestinal mucosa of the mice and there were no significant differences at different time points (p>0.05). By contrast, in the OJ group TLR4 protein (0.12±0.06, 0.16±0.08, 0.27±0.10, 0.35±0.12 and 0.41±0.13, respectively) and mRNA (0.49±0.19, 0.62±0.23, 0.98±0.32, 1.42±0.41 and 1.72±0.49, respectively) increased gradually with the extension of time (p<0.05). Also in the OJ group, the levels of DAO and endotoxin in plasma as well as the expressions of NF-κB and caspase-3 increased gradually with the extension of time, showing positive correlation with the expression of TLR4 (p<0.05).

CONCLUSIONS

The expression of TLR4 was significantly up-regulated in the distal ileum of mice with OJ. Activation of the TLR4/TRAF6/NF-κB pathways was involved in the occurrence and development of intestinal mucosal injury and endotoxemia in mice with OJ.

Functional Changes of Paneth Cells in the Intestinal Epithelium of Mice with Obstructive Jaundice and After Internal and External Biliary Drainage

OBJECTIVE

To investigate the functional changes of Paneth cells in the intestinal epithelium of mice with obstructive jaundice (OJ) and after internal biliary drainage (ID) and external biliary drainage (ED).

METHODS

The experiment was divided into two stages. First stage: Mice were randomly assigned to two groups: (I) sham operation (SH); (II) OJ. The mice were sacrificed before the operation and on the 1st, 3rd, 5th and 7th day after the operation to collect specimens. Second stage: Mice were randomly assigned to four groups: (I) SH; (II) OJ; (III) OJ and ED; and (IV) OJ and ID. They were reoperated on day 5 for biliary drainage procedure. The specimens were collected on day 10.

RESULTS

The expressions of lysozyme and cryptdin-4 increased first and then decreased over time in group OJ, and the number of Paneth cells decreased gradually with the extension of OJ time（p<0.05. After the secondary operation on the mice to relieve OJ, the number of Paneth cells and expressions of lysozyme and cryptdin-4 in group ID increased more significantly than those in group ED（p<0.05）.

CONCLUSION

OJ could cause intestinal Paneth cells to dysfunction in mice. ID was more significant than ED in restoring the function of Paneth cells. It might be one of the mechanisms that make ID superior to ED.

A Simple and Easily Reproducible Model of Reversible Obstructive Jaundice in Rats

BACKGROUND/AIM

Cholangiocarcinoma and pancreatic carcinoma are major malignancies that cause obstructive jaundice (OJ). This study aimed to develop a simple and easily reproducible rat model of reversible OJ (ROJ).

MATERIALS AND METHODS

OJ was induced by clamping the common bile duct (CBD) using a U-shaped titanium hemoclip and its base was attached by ligation using 2-cm long 4-0 polypropylene suture. An anti-adhesive sheet was placed around the CBD. OJ was mitigated by pulling the suture to remove the clip under laparotomy 3 days later. Serum chemistry and liver histopathology were compared between the ROJ group and sham surgery (SH) groups.

RESULTS

Three days after inducing OJ, serum total bilirubin, aspartate aminotransferase, and alanine aminotransferase were remarkably elevated in the ROJ group and thereafter reduced significantly after mitigating OJ. Similar findings were confirmed by histopathology.

CONCLUSION

Our rat model of reversible OJ was considered simple and easily reproducible.

A simple rat model of in situ reversible obstructive jaundice in situ reversible obstructive jaundice model

PURPOSE

To develop a simple and reliable rat model of in situ reversible obstructive jaundice with low morbidity and mortality rates.

METHODS

Rats were divided into 4 groups with 8 rats each: the sham-operated (SH) group only underwent laparotomy, the control internal drainage (ID-C) group underwent choledochoduodenostomy, the new internal drainage (ID-N) group and the long-term internal drainage (ID-L) group underwent choledochocholedochostomy. Common bile duct ligation was performed in all the drainage groups 7 days before reversal procedures. All rats were sacrificed for samples 7 days after the last operation except rats of the ID-L group that survived 28 days before sacrifice. Body weight, liver function, histopathological changes, morbidity and mortality were assessed.

RESULTS

One rat died and 2 rats had complications with tube blockage in the ID-C group. No death or complications occurred in the ID-N and ID-L groups. The drainage tube remained patent in the long-term observation ID-L group. Body weight showed no significant difference between the ID-C and ID-N groups after 7 days drainage. Liver function was not fully recovered in the ID-C and ID-N groups after 7 days drainage, but statistical differences were only observed in the ID-C group compared with the SH and ID-L groups. Periportal inflammation and bile duct proliferation showed severer in the ID-C group than in the ID-N group.

CONCLUSION

The present study provided an efficient, simple, and reliable rat model that is especially suitable for long-term or consecutive studies of reversible obstructive jaundice.

Glutamine attenuates obstructive cholestasis in rats via farnesoid X receptor–mediated regulation of Bsep and Mrp2

To investigate the protective effect of glutamine (Gln) against obstructive cholestasis in association with farnesoid X receptor (FXR) activation, an obstructive cholestasis model was established in male Sprague–Dawley rats by bile duct ligation (BDL). Serum biomarkers and hematoxylin plus eosin staining were used to identify the degree of hepatic injury in the rats with obstructive cholestasis after Gln treatment. Immunohistochemistry, real-time PCR, Western blot, cultured primary rat hepatocytes with FXR knockdown, and dual-luciferase reporter assay were performed to elucidate the mechanisms underlying Gln hepatoprotection. We found that Gln treatment protected against obstructive cholestasis induced by BDL through reducing hepatocyte injury. Upregulation of the hepatic efflux transporters small heterodimer partner (Shp), bile salt export pump (Bsep), and multidrug resistance–associated protein 2 (Mrp2), and inhibition of the hepatic uptake transporter Na+/taurocholate cotransporting polypeptide (Ntcp) and the bile acid synthesis enzyme cholesterol 7α-hydroxylase (Cyp7a1) expression were observed in rats with BDL treated with Gln in vivo. Furthermore, the regulatory effect of Gln on Bsep and Mrp2 expression was abrogated after FXR knockdown in rat primary cultured hepatocytes. Luciferase assay HepG2 cells also illustrated FXR was a direct target for Gln treatment. In conclusion, the regulation of Bsep and Mrp2 expression mediated by FXR might be an important mechanism for Gln against obstructive cholestasis.

Morphological changes in the liver and kidneys of rats subjected to terminal ileum exclusion during obstructive cholestasis

PURPOSE

To investigate the effects of ileal exclusion on hepatic and renal morphology in extra-hepatic cholestasis.

METHODS

Twenty four rats were distributed into three groups. Group 1 (control) underwent laparotomy and laparorrhaphy. The animals in groups 2 and 3 underwent hepatic duct ligature and kept in cholestasis for four weeks. After this period, the rats in groups 2 and 3 underwent internal biliary derivation. In Group 3, the last ten centimeters of the terminal ileum were by passed and excluded. Four weeks later, histological and biochemical analysis were performed in all animals of the three groups.

RESULTS

In Group 1, no abnormalities regarding hepatic morphology were observed. All animals from groups 2 and 3 presented hepatic fibrosis. No difference was observed between the two groups. No morphological differences in renal histology could be identified among the three groups. There were differences in AST (p<0.05), ALT (p<0.05), direct bilirubin (p<0.05), ƔGT (p<0.05), urea (p<0.05) and creatinine (p<0.05) in Group 3 compared to control.

CONCLUSION

The distal ileum exclusion had no influence upon the hepatic and renal morphological alterations, and biochemical liver and kidney tests have worsened.

Influence of distal ileum exclusion on hepatic and renal functions in presence of extrahepatic cholestasis

OBJECTIVE

To verify whether the ileal exclusion interferes with liver and kidney functional changes secondary to extrahepatic cholestasis.

METHODS

We studied 24 rats, divided into three groups with eight individuals each: Group 1 (control), Group 2 (ligation of the hepatic duct combined with internal biliary drainage), and Group 3 (bile duct ligation combined with internal biliary drainage and exclusion of the terminal ileum). Animals in Group 1 (control) underwent sham laparotomy. The animals of groups 2 and 3 underwent ligation and section of the hepatic duct and were kept in cholestasis for four weeks. Next, they underwent an internal biliary bypass. In Group 3, besides the biliary-enteric bypass, we associated the exclusion of the last ten centimeters of the terminal ileum and carried out an ileocolic anastomosis. After four weeks of monitoring, blood was collected from all animals of the three groups for liver and kidney biochemical evaluation (albumin, ALT, AST, direct and indirect bilirubin, alkaline phosphatase, cGT, creatinine and urea).

RESULTS

there were increased values of ALT, AST, direct bilirubin, cGT, creatinine and urea in rats from Group 3 (p < 0.05).

CONCLUSION

ileal exclusion worsened liver and kidney functions in the murine model of extrahepatic cholestasis, being disadvantageous as therapeutic procedure for cholestatic disorders.

Effect of biliary drainage on inducible nitric oxide synthase, CD14 and TGR5 expression in obstructive jaundice rats

AIM: To investigate the effect of biliary drainage on inducible nitric oxide synthase (iNOS), CD14 and TGR5 expression in rats with obstructive jaundice (OJ).

METHODS: Male adult Sprague-Dawley rats were randomly assigned to four groups: OJ, sham operation (SH), internal biliary drainage (ID) and external biliary drainage (ED). Rat models were successfully established by two operations and succumbed for extraction of Kupffer cells (KCs) and liver tissue collection on the 8^th and 15^th day. KCs were isolated by in situ hepatic perfusion and digested with collagen IV, density gradient centrifuged by percoll reagent and purified by cell culture attachment. The isolated KCs were cultured with the endotoxin lipopolysaccharide (LPS) with and without the addition of ursodeoxycholic acid (UDCA). The expression of iNOS, CD14 and bile acid receptor-TGR5 protein in rat liver tissues was determined by immunohistochemistry. The expression of iNOS and CD14 messenger RNA (mRNA) on the isolated KCs was detected by reverse transcription polymerase chain reaction (PCR) and the TGR5 mRNA level in KCs was measured by real-time quantitative PCR.

RESULTS: The iNOS protein was markedly expressed in the liver of OJ rats, but rare expressed in SH rats. After relief of OJ, the iNOS expression was decidedly suppressed in the ID group (ID vs OJ, P < 0.01), but obviously increased in rats of ED (ED vs OJ, P = 0.004). When interfered only with LPS, the expression of iNOS mRNA by KCs was increased in the OJ group compared with the SH group (P = 0.004). After relief of biliary obstruction, the iNOS mRNA expression showed slight changes in the ED group (ED vs OJ, P = 0.71), but dropped in the ID group (ID vs OJ, P = 0.001). Compared with the simple intervention with LPS, the expressions of iNOS mRNA were significantly inhibited in all four groups after interfered with both LPS and UDCA (P < 0.01, respectively). After bile duct ligation, the CD14 protein expression in rat liver was significantly strengthened (OJ vs SH, P < 0.01), but the CD14 mRNA level by KCs was not up-regulated (OJ vs SH, P = 0.822). After relieving the OJ, the expression of CD14 protein was reduced in the ID group (ID vs OJ, P < 0.01), but not reduced in ED group (ED vs OJ, P = 0.591). And then the CD14 mRNA expression was aggravated by ED (ED vs OJ, P < 0.01), but was not significantly different between the ID group and the SH and OJ groups (ID vs SH, P = 0.944; ID vs OJ, P = 0.513, respectively). The expression of TGR5 protein and mRNA increased significantly in OJ rats (OJ vs SH, P = 0.001, respectively). After relief of OJ, ID could reduce the expression of TGR5 protein and mRNA to the levels of SH group (ID vs SH, P = 0.22 and P = 0.354, respectively), but ED could not (ED vs SH, P = 0.001, respectively).

CONCLUSION: ID could be attributed to the regulatory function of activation of KCs and release of inflammatory mediators.

Bile acid-induced expression of farnesoid X receptor as the basis for superiority of internal biliary drainage in experimental biliary obstruction

AIMS AND OBJECTIVES

The aim is to determine the efficacy of internal and external biliary drainage (ED) with special reference to the effect of bile acid on intestinal epithelium during experimental biliary obstruction. Methods. A total of 59 male Sprague Dawley rats were randomly assigned to four groups: (I) sham operation (SH); (II) obstructive jaundice (OJ); (III) OJ and ED; and (IV) OJ and internal biliary drainage (ID). The animals underwent surgical ligation of the bile duct on day 1. They were reoperated on day 8 for biliary drainage procedure. Blood cultures were obtained from portal vein and inferior vena cava on day 15. Samples were also drawn for serum total bile acid (TBA) and white blood cell (WBC) counts. The terminal ileum was harvested to study the tight junction-associated protein ("occludin") and bile acid receptor ("farnesoid X receptor" [FXR]) using immunohistochemical method.

RESULTS

Serum TBA (118.9 ± 39.0 μmol/L) and WBC (11.4 ± 2.7 × 10(9)/L) were significantly increased (p = 0.001) after bile duct ligation as compared with SH rats (38.0 ± 15.0 μmol/L and 5.5 ± 1.0 × 10(9)/L, respectively; p = 0.001). The resulting mucosal lesion was high grade and the expressions of FXR and Occludin were decreased. After ED, there was slight decrease in total WBCs, whereas TBA levels declined significantly. The expression of FXR was minimal and Occludin showed no change (ED vs. OJ: p = 0.533). However, both WBC and TBA decreased after ID. The ileal structure, grade of mucosal lesion, and expression of FXR/Occludin were comparable with SH group (p > 0.05). The rate of bacterial translocation was: 57.1% (OJ); 62.5% (ID); and 80% (ED) with identical strains in cultures from the portal vein and inferior vena cava.

CONCLUSION

Downregulation of TBA/FXR expression during biliary obstruction results in damage to intestinal epithelium. Unlike ED, ID restores FXR/Occludin expression in the terminal ileum through reappearance of intestinal bile acid, which thus appears to be a key factor in maintaining integrity of the epithelial barrier.

Changes of serum cytokines and expression of inducible nitric oxide synthase mRNA by Kupffer cells after relief from obstructive jaundice in rats

AIMS

To investigate the changes of serum endotoxin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and inducible nitric oxide synthase (iNOS) expression by Kupffer cells after relief of obstructive jaundice (OJ) by internal biliary drainage (ID) and external biliary drainage (ED) in rats.

MATERIALS AND METHODS

Forty eight adult Sprague Dawley rats were randomly assigned to four groups: OJ, ID, ED and sham operation (SH). Inducible nitric oxide synthase mRNA by the Kupffer cells was detected by reverse transcription polymerase chain reaction. The serum TNF-alpha and IL-6 were measured by enzyme linked immunosorbent assay and endotoxin by kinetic turbidimetric limulus tests.

RESULTS

Serum endotoxin, IL-6 and TNF-alpha levels were significantly elevated in OJ rats compared to that of SH rats (P < 0.01). After relief from OJ, the elevated endotoxin, IL-6 and TNF-alpha levels could be significantly depressed by ID (P < 0.01). However, the serum IL-6 level was increased in ED rats (P < 0.05) and the TNF-alpha level was not depressed by ED. Expression of iNOS mRNA by Kupffer cells was markedly stronger in the OJ group than in the SH group (P = 0.005). After relief from OJ, the iNOS mRNA expression was suppressed by ID (P = 0.139, ID vs OJ). However, the iNOS mRNA expression was promoted by ED (P = 0.321 ED vs OJ; P = 0.016 ED vs SH).

CONCLUSIONS

The levels of serum endotoxin, TNF-alpha and IL-6 and the expression of iNOS mRNA by Kupffer cells were increased in rats with obstructive jaundice. Internal biliary drainage could entirely reverse the changes, but external drainage only partially did.

Bile duct ligation in rats: A reliable model of hepatorenal syndrome?

The two most widely used experimental models of advanced liver disease are the administration of carbon tetrachloride, and common bile duct ligation (BDL), however, neither has been systematically evaluated as a model of hepatorenal syndrome (HRS). The BDL model in rats, studied at diverse time points, induced a progressive renal dysfunction without structural changes in the kidney. The authors concluded that BDL is a good model for further studies of HRS and its treatment. However, the renal impairment observed at the acute phase of the BDL model is based on a different pathophysiology than that of HRS. Specifically, in acute obstructive jaundice, cholemia predominates over parenchymal liver disease (reversible at this stage without portal hypertension or cirrhosis) and independently induces negative inotropic and chronotropic effects on the heart, impaired sympathetic vasoconstriction response and profound natriuresis and diuresis that might lead to volume depletion. In addition, systemic endotoxemia contributes to the prerenal etiology of renal impairment and promotes direct nephrotoxicity and acute tubular necrosis. On the other hand, the renal failure observed in the chronic BDL model (with development of biliary cirrhosis, portal hypertension and ascites) shares pathophysiological similarities with HRS, but the accordance of the chronic BDL model to the diagnostic criteria of HRS (e.g. absence of spontaneous bacterial peritonitis, no renal function improvement after plasma volume expansion) should have been confirmed. In conclusion, we think that the BDL model is not suitable for the study of the natural history of HRS, but the chronic BDL model might be valid for the study of established HRS and its potential therapies.

Reversibility of leukocyte dysfunction in rats with obstructive jaundice

BACKGROUND

The role of leukocytes in obstructive jaundice is obscure and the effect of relieving cholestasis on leukocyte function is unclear. We postulated that cholestasis affects systemic polymorphonuclear leukocyte function by deranging phagocytosis and hydrogen peroxide release and the leukocyte dysfunction is reversible by internal and external biliary drainage.

MATERIALS AND METHODS

Sixty male Sprague Dawley rats were randomly assigned to four groups: obstructive jaundice (OJ), sham operation (SH), OJ with internal drainage (ID), and OJ with external drainage (ED). The phagocytic functions of neutrophils and monocytes in whole blood were measured with flow cytometry using fluorescent microspheres. Intracellular hydrogen peroxide production by leukocytes was assessed with flow cytometry using dihydrorhodamine-123 as probes.

RESULTS

Leukocyte count and percentage of monocytes in rats with OJ was significantly increased compared with SH rats (P < 0.001). These elevations could be reversed by both ID and ED method (P < 0.001). The phagocytic function of neutrophils and monocytes was significantly depressed in OJ rats compared with that in SH rats (P < 0.001). After relief of the OJ, the suppressed phagocytic function of neutrophils and monocytes was completely improved in ID rats (ID versus OJ, P < 0.001), but only partially reversed in ED rats. The hydrogen peroxide production by monocytes and lymphocytes was significantly increased in OJ rats (P < 0.05). ID reversed the increased hydrogen peroxide generation (P < 0.05), but ED only partially did.

CONCLUSIONS

In our rodent model of biliary obstruction, deranged phagocytosis, and hydrogen peroxide generation by leukocytes was found. Internal drainage is superior to external drainage for reversal of the distorted leukocyte function.

Superoxide and nitric oxide production by Kupffer cells in rats with obstructive jaundice: effect of internal and external drainage

BACKGROUND AND AIMS

The role of Kupffer cells in obstructive jaundice (OJ) has not been fully understood. The aims of the present study were to measure superoxide and nitric oxide (NO) production by Kupffer cells in experimental OJ in rats and to investigate the response to internal and external biliary drainage.

METHODS

Eighty male Sprague-Dawley rats were assigned to four groups: sham operation, OJ, and internal and external biliary drainage. Kupffer cells were isolated on day 7 in the sham operation and OJ group, and on day 7 after drainage procedures. Cells were cultured with or without lipopolysaccharide (LPS). Superoxide production was quantified in cultured Kupffer cells at 2 h and 48 h, respectively, after cell isolation using the superoxide dismutase inhibitable ferricytochrome c reduction method. Nitrite production in cell culture supernatants was measured 48 h later using Greiss reagents.

RESULTS

Without LPS stimulation, Kupffer cells produced comparable superoxide and nitrite in each group (P > 0.05). With LPS stimulation, Kupffer cells in the OJ group produced significantly higher superoxide anions than the other groups (P = 0.006). Nitrite production was significantly increased in the OJ group and external biliary drainage group compared to rats in the sham operation and internal drainage groups (P < 0.01).

CONCLUSIONS

Kupffer cells from rats with OJ produce great amounts of endotoxin-mediated oxidants. Both internal and external biliary drainage can decrease the elevated superoxide production. Internal drainage is superior to external drainage for reversing the distortional capacity of NO production by Kupffer cells.