Hepatic tumor necrosis factor-alpha production and distant organ dysfunction in a murine model of obstructive jaundice

Bile acids-induced lung injury: update of reverse translational biology

The presence of bile acids in lung tissue is associated with some clinical features observed in various medical specialties, but it took time to understand that these are due to a "bile acid-induced lung injury" since specific translational studies and cross-disciplinary awareness were lacking. We used a reverse translational approach to update and summarize the current knowledge about the mechanisms of bile acid-induced lung injury. This has been done in a cross-disciplinary fashion since these conditions may occur in patients of various age and in different medical fields. We here define these clinical conditions, then we review the physiopathology of these conditions and the animal models used to mimic them and, finally, their pathobiology. Mechanisms of bile acid-induced lung injury have been partially clarified overtime and are represented by: 1) the interaction with secretory phospholipase A2 pathway, 2) the effect on surfactant function and structure, 3) the biological effects on inflammation and local immunity, 4) the direct cellular toxicity. These mechanisms are schematically illustrated and histological comparisons between ARDS induced by bile acids and other triggers are also provided. Based on these mechanisms we propose possible direct therapeutic applications and, finally, we discuss further research steps to improve the understanding of processes that generate pathological clinical conditions.

Pathophysiology of lung injury induced by common bile duct ligation in mice

Background

Liver dysfunction and cirrhosis affect vasculature in several organ systems and cause impairment of organ functions, thereby increasing morbidity and mortality. Establishment of a mouse model of hepatopulmonary syndrome (HPS) would provide greater insights into the genetic basis of the disease. Our objectives were to establish a mouse model of lung injury after common bile duct ligation (CBDL) and to investigate pulmonary pathogenesis for application in future therapeutic approaches.

Methods

Eight-week-old Balb/c mice were subjected to CBDL. Immunohistochemical analyses and real-time quantitative reverse transcriptional polymerase chain reaction were performed on pulmonary tissues. The presence of HPS markers was detected by western blot and microarray analyses.

Results

We observed extensive proliferation of CD31-positive pulmonary vascular endothelial cells at 2 weeks after CBDL and identified 10 upregulated and 9 down-regulated proteins that were associated with angiogenesis. TNF-α and MMP-9 were highly expressed at 3 weeks after CBDL and were less expressed in the lungs of the control group.

Conclusions

We constructed a mouse lung injury model by using CBDL. Contrary to our expectation, lung pathology in our mouse model exhibited differences from that of rat models, and the mechanisms responsible for these differences are unknown. This phenomenon may be explained by contrasting processes related to TNF induction of angiogenic signaling pathways in the inflammatory phase. Thus, we suggest that our mouse model can be applied to pulmonary pathological analyses in the inflammatory phase, i.e., to systemic inflammatory response syndrome, acute lung injury, and multiple organ dysfunction syndrome.

Dexamethasone pretreatment attenuates lung and kidney injury in cholestatic rats induced by hepatic ischemia/reperfusion

Hepatic ischemia followed by reperfusion (IR) results in mild to severe organ injury, in which tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) seem to be involved. Thus, we aim to assess the influence of hepatic ischemia/reperfusion injury on remote organs in addition to cholestasis and consider the possible efficacy of steroid pretreatment in reducing the injury. A common bile duct ligation model was done on 24 male Sprague-Dawley rats. After 7 days, the rats were divided randomly into control group, IR group, and dexamethasone (DEX) group. The IR group showed significant increases in serum alanine aminotransferase, aspartate aminotransferase, and creatinine levels compared with the control and DEX groups. By ELISA techniques, higher levels of TNF-α and IL-1β in lung and kidney tissues were measured in the IR group than in the control and DEX groups, these were verified by immunohistochemistry. The lung histology of the IR group rats showed neutrophil infiltration, interstitial edema, and alveolar wall thickening. Kidney histology of the IR group rats showed vacuolization of the proximal tubular epithelial cells and tubular dilatation with granular eosinophilic casts. Better morphological aspects were observed in the DEX-pretreated animals. Minimal lesions were observed in the control. The results suggest that hepatic ischemia/reperfusion injury in cholestatic rats induced lung and kidney injuries. Pretreatment with dexamethasone reduced the IR-induced injury in addition to cholestasis.

Persistent elevation of hepatocyte growth factor activator inhibitors in cholangiopathies affects liver fibrosis and differentiation

Alteration of cell surface proteolysis has been proposed to play a role in liver fibrosis, a grave complication of biliary atresia (BA). In this study we investigated the roles of hepatocyte growth factor activator inhibitor (HAI)-1 and -2 in the progression of BA. The expression levels of HAI-1 and -2 were significantly increased in BA livers compared with those in neonatal hepatitis and correlated with disease progression. In BA livers, HAI-1 and -2 were coexpressed in cells involved in ductular reactions. In other selective cholangiopathies, ductular cells positive for HAI-1 or HAI-2 also increased in number. Inflammatory cytokines, growth factors, and bile acids differentially up-regulated expression of HAI-1 and -2 transcripts in fetal liver cells and this induction could be antagonized by a cyclooxygenase-2 inhibitor. Conditioned media from cell lines stably overexpressing HAI-1 or HAI-2 enhanced the fibrogenic activity of portal fibroblasts and stellate cells, suggesting that both proteins might be involved in liver fibrosis. Because HAI-1 and -2 colocalized in ductular reactions sharing similar features to those observed during normal liver development, we sought to investigate the role of HAI-1 and -2 in cholangiopathies by exploring their functions in fetal liver cells. Knockdown of HAI-1 or HAI-2 promoted bidirectional differentiation of hepatoblast-derived cells. In addition, we showed that the hepatocyte growth factor activator, mitogen-activated protein kinase kinase 1, and phosphatidylinositol 3-kinase signaling pathways were involved in hepatic differentiation enhanced by HAI-2 knockdown.

CONCLUSION

HAI-1 and -2 are overexpressed in the liver in cholangiopathies with ductular reactions and are possibly involved in liver fibrosis and hepatic differentiation; they could be investigated as disease markers and potential therapeutic targets.

Protective effect and mechanisms of radix astragali injection on the intestinal mucosa of rats with obstructive jaundice

Objective. To research the protective effects and mechanisms of Radix Astragali injection on the intestinal mucosa of rats with obstructive jaundice (OJ). Methods. The rats were randomly divided into sham-operated, model control and Radix Astragali treated group. We observed the pathological changes of intestinal mucosa, expression levels of Bax and NF-κB proteins, and apoptosis indexes in intestinal mucosa as well as serum NO, MDA and SOD contents, respectively, on 7d, 14d, 21d and 28d after operation. Results. The pathological severity score (on 7d and 14d), apoptotic indexes (on 14d) of the intestinal mucosa and serum MDA content (on 14d) of treated group were significantly lower than those in the model control group (P < .05). The serum SOD contents (on all time points) of treated group were significantly higher than those in the model control group (P < .05). The sham-operated group (on 21d) of the product of staining intensity and positive rate of Bax protein was significantly lower than model control group (P < .05). Conclusion. Radix Astragali injection could protect the intestinal mucosa of OJ rats by increasing the content of SOD, reducing the content of MDA, inhibiting the apoptosis and relieving the pathological changes of intestinal mucosa.

Effects of Salvia miltiorrhizae on ICAM-1, TLR4, NF-kappaB and Bax proteins expression in multiple organs of rats with severe acute pancreatitis or obstructive jaundice

To observe the protective effects of Salvia miltiorrhizae injection on multiple organs of rats with SAP or OJ. Two hundred eighty-eight rats were used for SAP-associated experiments and OJ-associated experiments. The rats were randomly divided into sham-operated, model control and treated group. According to the different time points after operation, the SAP rats in each group were subdivided into 3, 6 and 12 h groups while the OJ rats were divided into 7, 14, 21 and 28 days groups. The mortality rates, pathological changes and ICAM-1 (only in lung), TLR4 (only in liver), Bax and NF-kappaB proteins expression in multiple organs (liver, kidney, lung, intestinal mucosa, spleen, thymus and lymph nodes) were observed, respectively. The mortality rates of treated groups decreased in both SAP and OJ experiments. Compared to model control group, the pathological changes can be seen in treated groups including; (1) the pathological changes of multiple organs in SAP and OJ experiments were improved, the pathological severity scores of kidney (at 6 h), intestinal mucosa (at 12 h), spleen (at 6 and 12 h), thymus (at 3 and 6 h) and lymph nodes (at 3 and 6 h) in SAP experiment and of liver (on 21 and 28 days), lung (21 days), intestinal mucosa (on 21 and 28 days) and spleen (on 21 and 28 days) in OJ experiment significantly declined (P < 0.05 or P < 0.01); (2) the positive rate of Bax protein in pancreas (at 3 h) and liver (on 6 and 12 h) in SAP experiment and in liver (on 28 days), kidney (on 21 days), and thymus (on 28 days) in OJ experiment were significantly lower (P < 0.05 or P < 0.01); (3) the positive rate of NF-kappaB in liver (at 12 h) and kidney (at 6 h) in SAP experiment and in liver (on 21 days), kidney (on 28 days), intestinal mucosa (on 28 days) and thymus (on 14 days) in OJ experiment significantly decreased (P < 0.05). (4) the positive rate of ICAM-1 in lungs (at 12 h) in SAP experiment was significantly less (P < 0.05). Salvia miltiorrhizae injection can protect multiple organs of SAP or OJ rats and inhibit the expression of ICAM-1, TLR4, NF-kappaB and regulate Bax proteins. Salvia miltiorrhizae may relieve the inflammation response and enhance the immunity function of SAP and OJ rats.

Protective effects of Salvia miltiorrhizae on multiple organs of rats with obstructive jaundice

PURPOSE

we aim to explore the protective effects of Salvia miltiorrhizae injection on multiple organs of obstructive jaundice (OJ) rats through observing the impact of this injection on the pathological alterations in these organs and the contents of endotoxin, PLA(2), and TNF-alpha in the blood.

METHODS

A total of 90 mice were randomly divided into sham-operated group, model-control group, and Salvia miltiorrhizae-treated group (n = 30). According to the duration of postoperative administration, each group was further divided into two subgroups, namely, 21 d subgroup (consecutive administration for 21 d, n = 15) and 28 d subgroup (consecutive administration for 28 d, n = 15). After administration, the pathological alterations in multiple organs were observed and the contents of endotoxin, PLA(2), and TNF-alpha in the blood were determined.

RESULTS

Compared to model control group, the number of dead rats in treated group decreased though there was no statistical difference between the two groups. The pathological alterations in the liver, kidney, and spleen in treated group showed varying degrees of mitigation. At all time points, the contents of plasma endotoxin declined significantly. On day 28, plasma PLA(2) content in treated group was significantly lower than that in model-control group.

CONCLUSION

Salvia miltiorrhizae injection is able to obviously reduce the contents of inflammatory mediators in the blood of OJ rats and exert some protective effects on multiple organs of these rats.

Reduced liver fibrosis in hypoxia-inducible factor-1alpha-deficient mice

Liver fibrosis is characterized by excessive deposition of extracellular matrix in the liver during chronic injury. During early stages of this disease, cells begin to synthesize and secrete profibrotic proteins that stimulate matrix production and inhibit matrix degradation. Although it is clear that these proteins are important for development of fibrosis, what remains unknown is the mechanism by which chronic liver injury stimulates their production. In the present study, the hypothesis was tested that hypoxia-inducible factor-1alpha (HIF-1alpha) is activated in the liver during chronic injury and regulates expression of profibrotic proteins. To investigate this hypothesis, mice were subjected to bile duct ligation (BDL), an animal model of liver fibrosis. HIF-1alpha protein was increased in the livers of mice subjected to BDL by 3 days after surgery. To test the hypothesis that HIF-1alpha is required for the development of fibrosis, control and HIF-1alpha-deficient mice were subjected to BDL. Levels of type I collagen and alpha-smooth muscle actin mRNA and protein were increased in control mice by 14 days after BDL. These levels were significantly reduced in HIF-1alpha-deficient mice. Next, the levels of several profibrotic mediators were measured to elucidate the mechanism by which HIF-1alpha promotes liver fibrosis. Platelet-derived growth factor (PDGF)-A, PDGF-B, and plasminogen activator inhibitor-1 mRNA levels were increased to a greater extent in control mice subjected to BDL compared with HIF-1alpha-deficient mice at 7 and 14 days after BDL. Results from these studies suggest that HIF-1alpha is a critical regulator of profibrotic mediator production during the development of liver fibrosis.

Excessive inflammation but decreased immunological response renders liver susceptible to infection in bile duct ligated mice

BACKGROUND/AIMS

Obstructive jaundice (OJ) is associated with increased surgical morbidity and infectious complication. The aim of the current study was to clarify the mechanism of excessive inflammation and susceptibility to infection in OJ.

METHODS

C57/BL6 mice were subjected to bile duct ligation (BDL) or sham surgery. Expression tumor necrosis factor-alpha, macrophage inflammatory protein-2, monocyte chemoattractant protein-1, inducible protein-10, and interleukin (IL)-10, activation of nuclear factor kappa B, fluorescence activated cell sorter analysis, serum alanine aminotransferase levels, and histology were examined. Survival after lipopolysaccharide (LPS) administration or cecal ligation and puncture 3 or 14 d after surgery was determined. IL-1beta and interferon-gamma expression was examined after LPS administration.

RESULTS

OJ induced nuclear factor kappa B activation and increased expression of macrophage inflammatory protein-2, which caused significant increases in neutrophil recruitment. Serum alanine aminotransferase levels increased consistent with histological observations in OJ. Mononuclear cells were recruited in the liver after BDL associated with monocyte chemoattractant protein-1 up-regulation. The recruitment of NK and T cells was varied, consistent with IP-10 expression during the time course of OJ. IL-10 expression was significantly up-regulated 14 d after BDL. After LPS administration, the mice at 3 d after BDL and at 3 and 14 d after sham surgery were all still alive, but all mice at 14 d after BDL died. After LPS administration, IL-1beta significantly increased in the mice at 14 d after BDL.

CONCLUSIONS

Immune response such as expression of pro- and anti-inflammatory mediators and recruitment of immune cells may thus differ over the time course of OJ. Prolonged OJ may cause excessive inflammation, thus result in susceptibility to infection.

Obstructive cholestasis induces TNF-alpha- and IL-1 -mediated periportal downregulation of Bsep and zonal regulation of Ntcp, Oatp1a4, and Oatp1b2

Inverse acinar regulation of Mrp2 and 3 represents an adaptive response to hepatocellular cholestatic injury. We studied whether obstructive cholestasis (bile duct ligation) and LPS treatment affect the zonal expression of Bsep (Abcb11), Mrp4 (Abcc4), Ntcp (Slc10a1), and Oatp isoforms (Slco1a1, Slco1a4, and slco1b2) in rat liver, as analyzed by semiquantitative immunofluorescence. Contribution of TNF-alpha and IL-1beta to transporter zonation in obstructive cholestasis was studied by cytokine inactivation. In normal liver Bsep, Mrp4, Ntcp, and Oatp1a1 were homogeneously distributed in the acinus, whereas Oatp1a4 and Oatp1b2 expression increased from zone 1 to 3. Glutamine synthetase-positive pericentral hepatocytes exhibited markedly lower Oatp1a4 expression than the remaining zone 3 hepatocytes. In cholestatic liver Bsep and Ntcp immunofluorescence in periportal hepatocytes significantly decreased to 66 +/- 4% (P < 0.01) and 67 +/- 7% (P < 0.05), whereas it was not altered in pericentral hepatocytes. Oatp1a4 was significantly induced in hepatocytes with a primarily low expression, i.e., in periportal hepatocytes and in glutamine synthetase-positive pericentral hepatocytes. Likewise, Oatp1b2 was upregulated in periportal hepatocytes. Mrp4 zonal induction was homogeneous. Inactivation of TNF-alpha and IL-1beta prevented periportal downregulation of Bsep. Recruitment of neutrophils and polymorphonuclear cells mainly occurred in the periportal zone. Likewise, IL-1beta induction was largely found periportally. No significant transporter zonation was seen following LPS treatment. In conclusion, zonal downregulation of Bsep in obstructive cholestasis is associated with portal inflammation and is mediated by TNF-alpha and IL-1beta. Periportal downregulation of Ntcp and induction of Oatp1a4 and Oatp1b2 may represent adaptive mechanisms to reduce cholestatic injury in hepatocytes with profound downregulation of Bsep and Mrp2.

Altered Kupffer cell function in biliary obstruction

BACKGROUND

An altered Kupffer cell (KC) response is thought to be responsible for the characteristic phenotype observed after biliary obstruction: a phenotype marked by a defect in the hepatic reticuloendothelial system and a hypersensitivity to endotoxin. Few studies, however, have directly examined KC function. We have sought to define the specific alterations in function and phenotype that occur in the KC after biliary obstruction.

METHODS

KCs were isolated from female C57BL/6 mice 4 days after a sham or common bile duct ligation (CBDL) operation. Phagocytosis, oxidative burst potential, and intracellular bacterial killing were measured as markers of reticuloendothelial system function. The KC response to endotoxin was assessed by measuring tumor necrosis factor alpha and interleukin 6 levels in the media after stimulation with lipopolysaccharide (LPS) or with LPS plus LPS-binding protein (LBP).

RESULTS

CBDL KCs demonstrated a significant increase in phagocytic ability and significantly decreased baseline oxidative stress, compared with Shams. The oxidative burst potential, however, was equivalent or higher for CBDL KCs. CBDL KCs also demonstrated increased numbers of viable intracellular bacteria after infection; however, it is unclear if this finding represents impaired intracellular bacterial killing or increased phagocytosis of bacteria. With respect to the KC response to endotoxin, CBDL KCs were found to be less sensitive to the stimulatory effects of LPS alone but were exquisitely sensitive to the effects of LBP. LBP levels were found to be significantly elevated in CBDL animals, and CBDL KCs demonstrated a dose-dependent, exaggerated tumor necrosis factor alpha and interleukin 6 response to LPS administered with LBP.

CONCLUSIONS

KC function is clearly altered after biliary obstruction. Phagocytic ability is actually increased, although the ability of CBDL KCs to kill bacteria within the phagosome remains ill defined. CBDL KCs are exquisitely sensitive to the effects of LBP, and LBP levels are elevated after biliary obstruction. LBP may be responsible for the increased proinflammatory response observed after endotoxin challenge in animals with biliary obstruction.

Effects of obstructive jaundice on the peripheral nerve: an ultrastructural study in rats

Obstructive jaundice (OJ) and hepatic disorders have been shown to be associated with peripheral neuropathy in several clinical studies. The study evaluated the effect of OJ on the ultrastructure of the rat sciatic nerve. In the OJ group, jaundice was created by ligation of common bile duct in Wistar-Albino rats. In the sham-operated control group the same procedure was performed without ligation of the bile duct. On day 7, all rats were re-operated and sciatic nerves were explored to harvest 2-cm-long nerve segments for quantitative and qualitative histopathological analysis by light and electron microscopy. Bilirubin was measured on serum samples. Bilirubin levels were significantly higher in jaundiced rats compared with that of controls (8.46 +/- 0.45 vs. 0.80 +/- 0.14 mmol/l, means +/- SD, p < 0.01). Control nerves did not show anything other than the normal histology. In the OJ group, degenerative changes such as irregularities, thinning, ruffling and invaginations, irregularshaped bodies, vacuolizations and focal segmental demyelination were observed in the myelin sheath. Myelin clusters were noted in the axoplasm. A varying degree of swelling was noted in the nucleus and cytoplasm of the Schwann cells. Morphometric analysis of specimens obtained from sciatic nerves showed that myelin injury (370.9 +/- 51.3 vs. 11.6 +/- 0.5 axons), axonal edema (142.1 +/- 24.2 vs. 10.6 +/- 0.5 edematous axons) and Schwann cell degeneration (50.3 +/- 11.6 vs. 3.2 +/- 0.2 Schwann cells) was significantly higher in the jaundiced rats than in the control group (p < 0.01). The ultrastructural alterations spotted in the rat peripheral nerve were attributed to hyperbilirubinemia and increased concentrations of several neurotoxic substances released from the Kupffer cells in OJ. Neuropathy in jaundiced patients seems to result from accompanying degenerative changes in the peripheral nervous system. However, the exact nature and initiating factors of this nerve injury remains to be unveiled.

Regulation and function of trefoil factor family 3 expression in the biliary tree

Microarray analysis identified trefoil factor family 3 (TFF3) as a gene expressed in biliary epithelial cells (BECs), regulated by interleukin (IL)-6, and potentially involved in biliary pathophysiology. We therefore studied the regulation and function of BEC TFF3, in vitro and in vivo in IL-6(+/+) and IL-6(-/-) mice subjected to chronic bile duct ligation for 12 weeks. In vitro studies showed that IL-6 wild-type (IL-6(+/+)) BECs expressed higher TFF3 mRNA and protein levels than IL-6-deficient (IL-6(-/-)) BECs. BEC TFF3 expression is dependent primarily on signal transducer and activator of transcription (STAT3) signaling, but the reciprocal negative regulation known to exist between the intracellular IL-6/gp130 signaling pathways, STAT3 and mitogen-activated protein kinase (MAPK), importantly contributes to BEC TFF3 expression. Specifically blocking STAT3 activity with a dominant-negative molecule or treatment with a growth factor such as hepatocyte growth factor, which increases MAPK signaling, decreases BEC TFF3 expression. In contrast, specifically blocking MAPK activity with PD98059 significantly increased BEC TFF3 expression. Higher BEC TFF3 levels in IL-6(+/+) BECs were associated with significantly better migration than IL-6(-/-) BECs in a wound-healing assay and defective IL-6(-/-) BEC migration was reversed with exogenous TFF3. In vivo, hepatic TFF3 mRNA and protein expression was limited to BECs and dependent significantly on STAT3 signaling, but was influenced by other factors present after bile duct ligation. Comparable results were obtained in normal and diseased human tissue samples. In conclusion the regulation and function of BEC TFF3 expression is similar to the colon. BEC TFF3 expression depends primarily on gp130/STAT3 and contributes to BEC migration and wound healing. Therefore, use of recombinant IL-6 or TFF3 peptides should exert a therapeutic role in preventing biliary strictures in liver allografts.

ETHYL PYRUVATE REDUCES LIVER INJURY IN A MURINE MODEL OF EXTRAHEPATIC CHOLESTASIS

Ethyl pyruvate has been shown to ameliorate liver injury and decrease expression of several proinflammatory cytokines when used to treat mice with hemorrhagic shock or alcoholic hepatitis. Herein we sought to determine whether delayed treatment with ethyl pyruvate dissolved in a Ringer's-type balanced salt solution--Ringer's ethyl pyruvate solution (REPS)--would be beneficial in a murine model of common bile duct ligation (CBDL)-induced liver injury. Male C57BL/6 mice were subjected to a sham (n = 6) procedure or CBDL (n = 27). Twenty-four hours after operation, mice subjected to CBDL were randomized to receive treatment with either REPS (40 mg/kg of ethyl pyruvate per dose) or Ringer's lactate solution (RLS) every 8 h over a 72 h period. Compared with sham-treated controls, CBDL in RLS-treated mice was associated with histological evidence of hepatocellular necrosis as well as significant increases in the plasma concentrations of alanine aminotransferase and total bilirubin. Relative to sham-treated controls, CBDL in RLS-treated mice also was associated with increased hepatic lipid peroxidation and increased hepatic expression of transcripts for TNF, IL-6, and iNOS. All of these changes were significantly attenuated by delayed treatment with REPS after CBDL. In the RLS-treated group, CBDL was associated with increased NF-kappaB DNA binding in nuclear extracts prepared from liver tissue. Treatment with REPS increased NF-kappaB DNA binding still further. CBDL was associated with increased hepatocellular apoptosis in both the RLS- and REPS-treated groups. These data support the view that ethyl pyruvate ameliorates hepatic inflammation, lipid peroxidation, and necrosis in mice subjected to CBDL. Ethyl pyruvate warrants further evaluation as an adjunctive treatment to ameliorate liver injury from extrahepatic biliary obstruction.

Host immune responses and intestinal permeability in patients with jaundice

BACKGROUND

Systemic endotoxaemia is implicated in the development of complications associated with obstructive jaundice. The aims of these studies were to assess the systemic immune response to intervention in patients with jaundice and to compare the effects of surgical and non-surgical biliary drainage on host immune function and gut barrier function.

METHODS

In the first study, 18 jaundiced and 12 control patients were studied to assess systemic immune responses before and after intervention. In the second study, immune responses and gut barrier function were assessed following surgical and non-operative biliary decompression in 45 patients with jaundice.

RESULTS

Endotoxin antibody concentrations fell significantly in patients with jaundice immediately after surgical intervention, but not after non-operative biliary drainage. This decrease was associated with a significant increase in serum P(55) soluble tumour necrosis factor (sTNF) receptor concentration (5.3 versus 10.5 ng/ml; P < 0.001), urinary excretion of P(55) TNF receptors (21.4 versus 78.8 ng/ml; P = 0.002) and intestinal permeability (lactulose : mannitol ratio 0.032 versus 0.082; P = 0.048). Intestinal permeability was significantly increased in patients with jaundice compared with controls (0.033 versus 0.015; P = 0.002).

CONCLUSION

These data suggest that obstructive jaundice is associated with impaired gut barrier function and activation of host immune function that is exacerbated by intervention. Surgery causes an exaggerated pathophysiological disturbance not seen with non-operative biliary drainage procedures.

Endogenous interferon gamma protects against cholestatic liver injury in mice

Cholestatic patients suffer from high perioperative morbidity and mortality, but the pathophysiology is still unknown. Interferon gamma (IFN-gamma) may play a role during cholestasis. Therefore, bile duct ligation (BDL) was induced in IFN-gamma alpha-chain receptor-deficient (IFN-gammaR(1)-/-) and wild-type (IFN-gammaR(1)+/+) mice. BDL elicited increased IFN-gamma messenger RNA and protein levels in the liver. One week after BDL, IFN-gammaR(1)+/+ mice showed less severe jaundice and liver injury than IFN-gammaR(1)-/- mice, as reflected by lower bilirubin and liver enzyme levels. In accordance, livers of IFN-gammaR(1)+/+ mice displayed smaller areas of necrosis by two-thirds than IFN-gammaR(1)-/- mice on histopathologic examination (P <.05), whereas mitotic activity and proliferating cell nuclear antigen (PCNA) labeling index was more than twice as high in IFN-gammaR(1)+/+ mice (P <.05). Livers of IFN-gammaR(1)+/+ mice displayed higher rates of apoptosis as indicated by DNA fragmentation rate, the number of apoptotic bodies, and poly ADP-ribose polymerase (PARP) immunostaining. BDL was not associated with lethality in IFN-gammaR(1)+/+ mice; IFN-gammaR(1)-/- mice, however, died from 10 days onward and survival after 2 weeks was 62% (10 of 16). In conclusion, these data suggest that IFN-gamma protects against liver injury during extrahepatic cholestasis by stimulation of apoptosis and subsequent proliferation of hepatocytes, leading to elegant removal of damaged hepatocytes, thus preventing necrosis and concomitant inflammatory responses.

Effect of internal biliary drainage on plasma levels of endotoxin, cytokines, and C-reactive protein in patients with obstructive jaundice

Preoperative biliary drainage may improve the cytokine and acute-phase response derangements observed in patients with obstructive jaundice. We conducted a prospective longitudinal, before-after trial in our 600-bed teaching hospital. Twenty-four patients with obstructive jaundice were investigated, 11 with benign obstruction and 13 with malignant disease. Endoscopic internal biliary drainage was performed in all patients (7 by papillotomy and 17 by endoprostheses). Endotoxin, tumor necrosis factor alpha (TNF-a), interleukin-6 (IL-6), nitric oxide production, and C-reactive protein (CRP) were determined at admission and on days 2 and 7 after internal biliary drainage was accomplished. Bile cultures were obtained before and at the time of drainage. Endotoxin, IL-6, TNF-a, and CRP were significantly higher in patients with cancer. After internal drainage, endotoxin (11.4 vs. 2 EU/L; p <0.05), TNF-a (87.5 vs. 48 pg/ml; p = 0.03), and IL-6 (324 vs. 232 pg/ml; p <0.05) plasma levels decreased significantly in the early postdrainage period in patients with cancer. Endotoxin, cytokines, as well as the CRP plasma values, however, increased again on day 7 after drainage. This trend was less marked in patients with benign obstruction. Patients with positive bile cultures after drainage displayed higher levels of CRP (115 vs. 62 mg/L; p = 0.03), IL-6 (598 vs. 330 pg/ml; p = 0.04), and endotoxin (10.6 vs. 4.8 EU/L; p = 0.02) than those with negative bile cultures. Biliary tract obstruction is associated with an increase in endotoxin levels, a positive acute-phase response, and plasma cytokine elevation. After biliary drainage a transitory improvement of these alterations was observed, although values remained high 1 week postdrainage. These findings were associated with positive bile cultures.

Endotoxin potentiates hepatocyte apoptosis in cholestasis

BACKGROUND

Cholestasis is a component of liver disease of almost any etiology, including septic liver injury. The cellular mechanisms of liver injury in cholestasis and sepsis remain unresolved. We evaluated apoptosis, a well-orchestrated and potentially reversible mechanism of cell death, in bile duct-ligated and endotoxin-injected rats.

STUDY DESIGN

Male Sprague-Dawley rats were randomly assigned to six groups (n = 6-9): bile duct-ligated+endotoxin (B+E), sham+endotoxin (S+E), bile duct-ligated (B), sham (S), endotoxin (E), and normal (N). On day 1, the bile ducts of B+E and B rats were ligated and severed. S+E and S animals underwent biliary manipulation only. On day 3, B+E, S+E, and E groups received 3 mg/kg endotoxin i.v.. On day 4, livers from all rats were excised, fixed, and stained (hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling [TUNEL]). Portions were frozen for DNA fragmentation analysis. Caspase 3 activity was determined using isolated hepatocytes.

RESULTS

Livers from all groups (B+E, S+E, E, and B) except normal and sham displayed apoptosis by hematoxylin and eosin staining, TUNEL staining, and DNA fragmentation. Histologic evaluation revealed 10% to 20% necrosis in endotoxin-treated animals (B+E, S+E, and E). Caspase 3 activity was significantly higher in endotoxin-treated animals versus animals without endotoxin (treated 0.450 +/- 0.08 versus nontreated 0.135 +/- 0.05, p < 0.0001) (mean +/- SD).

CONCLUSIONS

Cholestatic livers had apoptosis without progression to necrosis. When exposed to the second insult of endotoxin, cholestatic livers received an acute on chronic apoptotic trigger, and proceeded to necrosis. Endotoxin was a potent hepatotoxic insult because all treated rat livers displayed both apoptosis and necrosis.

Alterations of tumor necrosis factor-alpha and interleukin 6 production and activity of the reticuloendothelial system in experimental obstructive jaundice in rats

BACKGROUND

Immunological changes are well recognised in obstructive jaundice. The aim of this study was to monitor plasma tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) levels in rats with obstructive jaundice.

METHODS

The ability of splenocytes and peritoneal exudate cells (PEC) to produce these cytokines both spontaneously and on induction with lipopolysaccharide (LPS), was compared in rats with and without obstructive jaundice (OJ). The activity of the reticuloendothelial system (RES) was also measured.

RESULTS

Serum cytokine levels in OJ rats were higher than in control rats. PEC cultures produced significantly more IL-6, compared with control rats, declining thereafter. TNF-alpha activity in the splenocyte cultures of OJ rats was also higher than in the control group. Pronounced differences were found in the ability to produce TNF-alpha by PEC, i.e., TNF-alpha production was much stronger on day 7 in OJ rats than in controls. On day 14 TNF-alpha production was much lower and the spontaneous response was equal to the LPS-induced one. On day 21 the cells of OJ rats partially regained the ability to produce TNF-alpha RES activity of OJ rats was significantly suppressed in the liver and spleen, whereas the phagocytic activity in the lungs was elevated.

CONCLUSION

We have demonstrated that the immune reactivity of OJ rats, initially elevated, underwent subsequent depression. The study also revealed a major effect of the operation alone on the studied parameters.

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

BACKGROUND

A simple and reproducible rat model that allows studies of the reversal of obstructive jaundice (OJ) by internal (ID) and external (ED) drainage is not available at present.

METHODS

OJ was induced in rats by double ligation and division of the common bile duct. To minimize tissue handling and dissection the duodenum was extracted with a ophthalmic muscle hook and the common bile duct isolated using very fine forceps. One week after bile duct ligation, ID was accomplished by implanting a length of infant feeding tube between the dilated bile duct and the duodenum. ED was achieved by placing a PVC tube into the dilated bile duct and exteriorizing the other end at the nape of the neck.

RESULTS

Minimal adhesions were found around the dilated common bile duct, which made relaparotomy for drainage easy. Alanine transaminase, total bilirubin, alkaline phosphatase, and gamma-glutamyltransferase were significantly raised after bile duct ligation. All parameters returned to control levels after ID for 7 days. In the ED group plasma albumin was significantly decreased and alkaline phosphatase remained marginally elevated.

CONCLUSIONS

We have developed a simple and reproducible rat model that allows for the study of reversal of OJ by ID or ED. We also demonstrated that ID is superior to ED in reversing impaired liver function in OJ.

NF-kappaB is activated in cholestasis and functions to reduce liver injury

Selected bile acids activate a nuclear factor-kappa B (NF-kappaB)-dependent survival signaling cascade in cultured hepatocytes. These data suggest that in cholestasis where liver tissue bile acid concentrations are increased, NF-kappaB should be activated and inhibition of NF-kappaB should potentiate liver injury. Our aims were to test these two predictions. Cholestasis was obtained by common bile duct ligation in mice. NF-kappaB activation was demonstrated in nuclear extracts by the electrophoretic mobility gel shift assay from 3-day bile duct-ligated (BDL) mice but not in controls. Immunohistochemistry for NF-kappaB demonstrated nuclear localization in hepatocytes of BDL mice consistent with its activation in this liver cell type. Electrophoretic mobility gel shift assay and immunohistochemistry for NF-kappaB in BDL tumor necrosis factor-receptor 1 knockout mice demonstrated hepatocyte NF-kappaB activation, suggesting that tumor necrosis factor-alpha was not responsible for the activation of this transcription factor. Liver injury was assessed in BDL mice after administration of the adenovirus 5 inhibitor of kappa B superrepressor (Ad5IkappaBsr) to inhibit NF-kappaB. TUNEL-positive cells and serum alanine aminotransferase values were increased at least threefold in mice treated with the Ad5IkappaBsr versus the empty virus. Liver histology also demonstrated increased liver injury in the BDL mice treated with the Ad5IkappaBsr. In conclusion, NF-kappaB is activated in hepatocytes during obstructive cholestasis and functions to reduce liver injury.

Attenuated febrile response to lipopolysaccharide in rats with biliary obstruction

Patients with biliary tract obstruction have unexplained, inordinately high rates of perioperative morbidity and mortality, whereas cholestatic animals display abnormal hypothalamic responses to pyrogenic stimuli. We asked if obstructive cholestasis was associated with abnormal fever generation. Male Sprague-Dawley rats (250 g) underwent laparotomy for implantation of thermistors and either bile duct resection (BDR) or sham operation. After recovery, temperatures were recorded by telemetry and conscious, unrestrained rats in each group were injected intraperitoneally with either interleukin-1beta (IL-1beta;1 microg/kg) or Escherichia coli lipopolysaccharide (LPS; 50 microg/kg). Baseline temperatures in both groups were similar. Febrile responses after IL-1beta injection in BDR and sham groups were not significantly different. However, in response to LPS injection, BDR rats showed an initial hypothermia with a subsequently attenuated febrile response. Administration of anti-tumor necrosis factor-alpha (TNF-alpha) antibody 2 h before LPS injection blocked the LPS-induced hypothermia seen in BDR animals. However, serum levels of TNF-alpha were not significantly different between sham and BDR animals after LPS injection at any time point measured (0, 1.5, and 3 h).

Intermittent hepatic pedicle clamping reduces liver and lung injury

BACKGROUND

Temporary occlusion of the hepatic hilum is used to control hemorrhage during liver resection, but can result in widespread organ dysfunction.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to either continuous (Group C) or intermittent (Group R) hepatic ischemia. The total ischemia time (60 min) was divided into four 15-min periods in Group R. Blood and lung tissue specimens were collected 2 h after the induction of ischemia (early phase), and 24 h after the termination of ischemia (late phase). Plasma lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) concentrations were measured. Histologic sections were studied using hematoxylin and eosin, as well as naphthol AS-D chloroacetate esterase techniques.

RESULTS

In the early phase, LDH, ALT, TNF-alpha, and IL-6 concentrations were significantly higher in Group C than in Group R. Pulmonary septal thickening and polymorphonuclear leukocyte infiltration were less severe in Group R than in Group C. These differences were significant in the late phase.

CONCLUSIONS

Intermittent hepatic pedicle clamping reduces the ischemia-reperfusion injury not only to the liver but also to the lungs. This technique may improve the outcome in patients undergoing liver resection.

Cholestatic liver injury increases circulating TNF-alpha and IL-6 and mortality after Escherichia coli endotoxemia

We employed a bile duct ligation (BDL) model of cholestatic liver injury to test the hypothesis that this form of preexisting hepatic dysfunction alters the kinetics of circulating TNF-alpha and IL-6 after Escherichia coli endotoxemia, thereby augmenting mortality and lung injury by a TNF-alpha:leukotriene (LT) axis of inflammation. Male rats were catheterized 13 d after BDL or sham surgery and studied while awake 18 to 24 h later. Cholestasis after BDL was confirmed by baseline serum bilirubin (BDL = 7.34 +/- 0.72 mg/dl, mean +/- SEM, n = 17 versus Sham = 0.25 +/- 0.07, n = 20; p < 0.005) and histopathology. Sham and BDL animals received E. coli lipopolysaccharide serotype O55:B5 (LPS, 5 mg/kg i.v.) or 0.9% NaCl (NS) ending at t = 0 and were monitored over 24 h for vital signs and hemodynamics. In parallel studies, lipoxygenase inhibition was performed using diethylcarbamazine or the 5-lipoxygenase activating-protein inhibitor MK-886. Blood was collected at baseline and at t = 1.5, 3.5, and 24 h for formed elements and for serum endotoxin, TNF-alpha, IL-6, bilirubin, and alanine aminotransferase (ALT). Organs were evaluated at 24 h for histopathology, including neutrophil (PMN) densities and wet/dry weight (W/D) ratios. Cholestasis reduced survival after otherwise nonlethal endotoxemia, with seven of 11 BDL + LPS rats dying within 24 h versus no deaths in BDL + NS (n = 6), Sham + LPS (n = 14), or Sham + NS (n = 6) animals (p < 0.01). Despite equivalent serum endotoxin between groups, circulating TNF-alpha was 8-fold higher in BDL + LPS than in Sham + LPS rats at 1.5 and 3.5 h (p < 0.001), whereas serum TNF-alpha did not differ between BDL + NS and Sham + NS rats. IL-6 likewise was increased differentially by 1.5 h in BDL + LPS animals (11.98 +/- 2.42 ng/ml) versus Sham + LPS rats (3.05 +/- 0.58 ng/ml, p < 0.05). Hypothermia, bradycardic hypotension, and leukopenia were most severe and prolonged in BDL + LPS rats, which also had significantly higher ALT values, W/D ratios, and organ PMN counts. LT inhibition failed to reduce BDL-related differences in serum cytokines or survival after endotoxemia. Thus, cholestasis augments inflammatory responses to gram-negative endotoxemia, sensitizing the host to enhanced fluid flux in multiple organs and to mortality by a LT-independent mechanism.

Enhanced endothelial cell injury by activated neutrophils in patients with obstructive jaundice

BACKGROUND/AIMS

A high incidence of complications has been documented in patients with obstructive jaundice after operations. Recent reports have revealed that neutrophils are involved in the mechanism causing postoperative complications. However, there are few reports investigating the interaction between neutrophils and endothelial cells in obstructive jaundice. The aim of this study was to evaluate neutrophil-mediated endothelial cell injury in patients with obstructive jaundice.

METHODS

Patients were divided into three groups: those with normal liver, obstructive jaundice, and relief of obstructive jaundice. Neutrophils were isolated from patients individually. Human umbilical vein endothelial cells and neutrophils were co-cultured after addition of phorbol myristate acetate. The release of lactate dehydrogenase and thrombomodulin was measured in the medium.

RESULTS

Lactate dehydrogenase and thrombomodulin were released in the co-culture medium, and Eglin C, which is an elastase inhibitor, reduced the release of lactate dehydrogenase and thrombomodulin in a dose-dependent manner. The release of lactate dehydrogenase and thrombomodulin in the group with relief of obstructive jaundice was significantly higher than in the group with normal liver. There was no significant difference between the group with obstructive jaundice and the group with normal liver. The elastase activity in neutrophil suspension was similarly higher in the group with relief of obstructive jaundice than in the group with normal liver.

CONCLUSIONS

This study suggests that neutrophils in patients with obstructive jaundice are not activated before its relief. After relief of obstructive jaundice, neutrophils are strongly primed and have the potential to cause endothelial cell injury. The neutrophil "priming" in patients with obstructive jaundice may be associated with the frequent occurrence of postoperative complications.