QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) All Versions of this Article: dmd.107.015610v1 35/9/1694    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wagner, M. Articles by Trauner, M. Search for Related Content PubMed PubMed Citation Articles by Wagner, M. Articles by Trauner, M.

Hepatobiliary Transporter Expression in Intercellular Adhesion Molecule 1 Knockout and Fas Receptor-Deficient Mice after Common Bile Duct Ligation Is Independent of the Degree of Inflammation and Oxidative Stress

Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Medicine (M.W., G.Z., P.F., J.G., D.S., M.T.) and Department of Pathology (A.F., K.Z., H.D.), Medical University, Graz, Austria; Exponent, Inc., Irvine, California (J.S.G.); and Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas (H.J.)

(Received March 6, 2007; Accepted June 15, 2007)

	Abstract

Top Abstract Materials and Methods Results Discussion References

 
Liver injury in intercellular adhesion molecule 1 knockout (ICAM^-/-) and Fas receptor-deficient (lpr) mice is markedly reduced after common bile duct ligation (CBDL) due to significantly reduced inflammation and oxidative stress. Liver injury in CBDL rodents is counteracted by adaptive hepatobiliary transporter induction. Since hepatobiliary transporter expression in obstructive cholestasis may be regulated not only by accumulating bile acids but also by inflammatory mediators and oxidative stress, we hypothesized that differences in the inflammatory response may affect hepatobiliary transporter expression in CBDL, which would contribute to reduced liver injury. Therefore, expression of major hepatobiliary transporters (Ntcp, Bsep, Mrp2-4, Ost/ß) was determined by Taqman RT-PCR and Western blotting in sham-operated animals and 3 days after CBDL in wild-type, ICAM^-/- and lpr mice of the endotoxin-sensitive C57BL/6 and the endotoxin-resistant C3H/HeJ strains. CBDL resulted in a significant decrease of Ntcp in all genotypes. Canalicular transporters Bsep and Mrp2 were repressed only in the endotoxin-sensitive strain regardless of the genotype. Mrp3 was moderately induced in ICAM^-/-, lpr, and endotoxin-resistant mice, whereas Mrp4 was only induced in the endotoxin-resistant strain. Ostß was massively induced in all CBDL mice, whereas Ost was reduced. In conclusion, markedly reduced inflammation and oxidative stress in CBDL ICAM^-/- and lpr mice does not profoundly affect hepatobiliary transporter expression. Therefore, transporter expression does not account for reduced liver injury in ICAM^-/- and lpr mice. Induction of the adaptive transporter response after CBDL is independent of the degree of the inflammatory response. Rather, retention of biliary constituents may determine transporter expression in CBDL.

In addition to bile acids, proinflammatory cytokines and oxidative stress have profound effects on bile secretion and hepatobiliary transporter expression (Green et al., 1996; Trauner et al., 1997b, 1998; Kubitz et al., 1999; Geier et al., 2003, 2005a,b; Siewert et al., 2004; Perez et al., 2006). As such, expression of hepatocellular organic anion uptake systems at the basolateral membrane (i.e., Ntcp, Oatp1, Oatp2, Oatp4) as well as efflux pumps at the canalicular membrane (Bsep, Mrp2) are reduced in lipopolysaccharide-challenged rodents (Green et al., 1996; Trauner et al., 1997a, 1998; Lee et al., 2000; Geier et al., 2003; Li and Klaassen, 2004). Again, comparable transporter changes were observed in liver biopsies from patients with inflammation-induced cholestasis (Zollner et al., 2001). Inflammation-induced down-regulation of transporters is thought to predispose and prolong cholestatic conditions via the reduction of canalicular bile flow irrespective of the initial etiology. However, the relative contribution of retained endogenous bile acids and inflammatory mediators and oxidative stress in regard to transporter dysregulation and cholestatic liver injury in biliary obstruction is largely undefined.

CBDL-induced cholestatic liver injury is markedly reduced in intercellular adhesion molecule 1 gene knockout (ICAM^-/-) and Fas receptor-deficient (lpr) mice, which has been attributed to reduced inflammation, parenchymal neutrophil extravasation, and reactive oxygen formation (Gujral et al., 2003, 2004a,b) (Table 1). Because proinflammatory cytokines are key regulators of hepatobiliary transporter expression, we hypothesized that differences in the regulation of hepatobiliary transport systems as a result of a reduced inflammatory response and reduced oxidative stress may contribute to reduced cholestatic liver injury in CBDL ICAM^-/- and lpr mice. This study was therefore designed to compare hepatocellular transporter expression patterns in CBDL ICAM^-/-, lpr mice, and wild-type controls.

View this table: [in this window] [in a new window]   TABLE 1 Comprehensive summary of the key findings on hepatic injury and inflammatory gene expression of wild-type, ICAM–/–, and lpr mice from endotoxin-sensitive (C57BL6/6J) and endotoxin-resistant (C3H/HeJ) strains after 3-day CBDL as published in detail previously (Gujral et al., 2004a,b)

	Materials and Methods

Top Abstract Materials and Methods Results Discussion References

 
Animals and Experimental Protocol. Experimental protocol (i.e., CBDL for 3 days) and characterization of cholestatic liver injury in male wild-type mice of the endotoxin-sensitive strain, C57BL6/6J, and the endotoxin-resistant strain, C3H/HeJ (Gujral et al., 2004b), ICAM^-/- (C57BL6/6J), and Fas receptor-deficient lpr mice (C57BL6/6J and C3H/HeJ) were published previously (Gujral et al., 2004a, b). Aliquots of frozen liver from four to five of these animals were stored in liquid nitrogen and used for further total RNA and protein preparation.

RNA Isolation, Reverse Transcription, and TaqMan Real-Time PCR. Total hepatic RNA from four to five mice was isolated and reverse-transcribed into cDNA as described previously (Fickert et al., 2004). Real-time PCR was performed as described previously (Wagner et al., 2003). Primers and probes used for Taqman RT-PCR are described elsewhere (Wagner et al., 2005).

Preparation of Liver and Analysis of Transporter Protein Levels by Western Blotting. Crude liver membranes were prepared from four to five wild-type and lpr mice of the C57BL6/6J and C3H/HeJ strains as described previously (Fickert et al., 2001; Wagner et al., 2003) whenever sufficient tissue aliquots were available. Transporter protein levels were determined using polyclonal first antibodies against Bsep (dilution, 1:7500; rabbit; kindly provided by Dr. Renxue Wang, British Columbia Cancer Research Center, Vancouver, Canada) (Wang et al., 2001), Ntcp (dilution, 1:2500; rabbit; kindly provided by Dr. Bruno Stieger, University Hospital, Zurich, Switzerland), Mrp2 (dilution, 1:1000; rabbit; kindly provided by Dr. Bruno Stieger, University Hospital, Zurich, Switzerland), Mrp3 (dilution, 1:1000; rabbit; kindly provided by Dr. Dietrich Keppler, Deutsches Krebsforschungszentrum, Heidelberg, Germany) as described previously (Fickert et al., 2001; Wagner et al., 2003). Blots were reprobed with an anti-ß-actin antibody (dilution, 1:5000; rabbit; Sigma, Steinheim, Germany) to confirm the specificity of the observed changes in transporter protein levels. Immune complexes were then detected using horseradish-conjugated goat anti-rabbit IgG F(ab9)2 fragments (dilution, 1:1000; Dako, Glastrup, Denmark) according to the ECL Western blotting detection system (GE Healthcare, Vienna, Austria).

Statistical Analysis. Four to five animals of each group were studied in parallel. Data are reported as means ± S.D. For statistical analysis sham-operated animals were compared with the respective CBDL group using Student's t test to test for the effects of CBDL. analysis of variance with Bonferroni post-testing was used in the sham and CBDL groups to test for differences among the respective genotypes within one strain. The Sigmastat statistic program (SPSS Inc., Chicago, IL) was used. A p value <0.05 was considered significant.

	Results

Top Abstract Materials and Methods Results Discussion References

 
CBDL-Induced Changes in Canalicular Transporter Expression Are Independent of the Inflammatory Response in ICAM^-/- and lpr Mice of the Endotoxin-Sensitive C57BL6/6J Strain. CBDL for 3 days resulted in a robust and significant down-regulation of Bsep mRNA to 31%, 24%, and 26% compared with sham-operated controls in wild-type, ICAM^-/-, and lpr mice, respectively. No significant differences in the degree of Bsep repression were observed among genotypes (Fig. 1A). Bsep protein levels did not change significantly in CBDL wild-type (1.3-fold compared with wild-type sham) and lpr (1.4-fold compared with lpr sham) (Fig. 1C). Mrp2 mRNA levels also showed a trend for reduction after CBDL to 69%, 50%, and 52% compared with sham-operated controls in wild-type, ICAM^-/-, and lpr mice, respectively, although statistical significance was achieved only in lpr mice (Fig. 1B). Mrp2 protein levels tended to be reduced in wild-type mice (70%) and were significantly lower in lpr mice (50%) following CBDL (Fig. 1D). Taken together, these results suggest that the reduced inflammatory response in ICAM^-/- and lpr mice has no major impact on canalicular transporter alterations in response to CBDL.

View larger version (26K): [in this window] [in a new window]   FIG. 1. Canalicular transporter expression in endotoxin-sensitive wild-type, ICAM-/-, and lpr mice. Values of RT-PCR are expressed as percentage of sham-operated wild-type mice (100%) ± S.D. from n = 4 to 5 in each group (*, sham-operated versus 3-day CBDL, p < 0.05) (A and B). Protein data of Western blotting are expressed as the -fold change compared with the sham-operated wild-type animals; two representative animals per group are shown (*, sham-operated versus 3-day CBDL, p < 0.05) (C and D). A and C, 3-day CBDL results in a significant down-regulation of Bsep mRNA in all genotypes, whereas Bsep protein remains unaffected. B and D, 3-day CBDL results in a significant Mrp2 mRNA down-regulation in lpr mice, whereas wild-type and ICAM-/- mice only showed a trend for reduction. This was paralleled by Mrp2 protein levels.

View larger version (30K): [in this window] [in a new window]   FIG. 2. Basolateral transporter expression in endotoxin-sensitive wild-type, ICAM-/- and lpr mice. Values of RT-PCR are expressed as percentage of sham-operated wild-type mice (100%) ± S.D. from n = 4 to 5 in each group (*, sham-operated versus 3-day CBDL, p < 0.05) (A-C, F, and G). Protein data of Western blotting are expressed as the -fold change compared with the sham-operated wild-type animals; two representative animals per group are shown (*, sham-operated versus 3-day CBDL, p < 0.05) (D and E). A and D, 3-day CBDL results in a significant Ntcp mRNA and protein down-regulation in all genotypes. B and E, 3-day CBDL results in a significant Mrp3 mRNA up-regulation in ICAM-/- and lpr mice, whereas in wild-type mice, Mrp3 mRNA only tended to increase without reaching statistical significance. This was paralleled by Mrp3 protein levels. C, Mrp4 mRNA did not change after 3-day CBDL. F, 3-day CBDL results in significant Ost mRNA down-regulation in wild-type animals and tended to decrease in lpr and ICAM-/- mice. G, 3-day CBDL results in significant Ostß mRNA up-regulation in all genotypes.

CBDL Alters Basolateral but Not Canalicular Transporter Expression in the Endotoxin-Resistant C3H/HeJ Strain, Independent of the Fas Receptor. In contrast to the endotoxin-sensitive strain, 3-day CBDL did not significantly alter Bsep mRNA and protein expression levels in endotoxin-resistant mice (Fig. 3, A and C). Also, Mrp2 mRNA and protein levels remained unaffected (Fig. 3, B and D).

View larger version (23K): [in this window] [in a new window]   FIG. 3. Canalicular transporter expression in endotoxin-resistent wild-type and lpr mice. Values of RT-PCR are expressed as percentage of sham-operated wild-type mice (100%) ± S.D. from n = 4 to 5 in each group (*, sham-operated versus 3-day CBDL, p < 0.05) (A and B). Protein data of Western blotting are expressed as the -fold change compared with the sham-operated wild-type animals; two representative animals per group are shown (*, sham-operated versus 3-day CBDL, p < 0.05) (C and D). A to D, Bsep and Mrp2 mRNA as well as protein levels remained unchanged after CBDL in both genotypes.

View larger version (26K): [in this window] [in a new window]   FIG. 4. Basolateral transporter expression in endotoxin-resistent wild-type and lpr mice. Values of RT-PCR are expressed as percentage of sham-operated wild-type mice (100%) ± S.D. from n = 4to5in each group (*, sham-operated versus 3-day CBDL, p < 0.05) (A-C, F, and G). Protein data of Western blotting are expressed as the -fold change compared with the sham-operated wild-type animals; two representative animals per group are shown (*, sham-operated versus 3-day CBDL, p < 0.05) (D and E). A and D, 3-day CBDL results in a significant Ntcp mRNA and protein down-regulation in both genotypes. B and C, 3-day CBDL results in significant Mrp3 and Mrp4 mRNA up-regulation in both genotypes. E, Mrp3 protein remains unaffected by CBDL in both genotypes. F, 3-day CBDL results in significant Ost mRNA down-regulation in wild-type mice, whereas lpr mice remain unaffected. G, 3-day CBDL results in a robust Ostß mRNA up-regulation in both genotypes.

	Discussion

Top Abstract Materials and Methods Results Discussion References

 
We undertook studies to determine the relative importance of inflammation and oxidative stress for the molecular regulation of hepatobiliary transporter expression in a mouse model of obstructive cholestasis. Cholestatic liver injury after CBDL is reduced in ICAM^-/- and lpr mice, as reflected by reduced size of necrotic bile infarcts and significantly lower ALT levels (Gujral et al., 2004a,b). Reduced cholestatic liver injury in these animals can be explained by reduced parenchymal and portal neutrophil extravasation, reduced expression of inflammatory mediators such as cytokines, and markers of oxidative stress following CBDL (Gujral et al., 2004a,b) (Table 1). In addition, cholestatic liver injury and markers of inflammation after CBDL are also reduced in endotoxin-resistant C3H/HeJ mice, a strain with a generally lower inflammatory response to cell injury (Gujral et al., 2004b). Therefore, we applied these mouse models with different degrees of inflammation and oxidative stress in response to biliary obstruction.

The current study shows, however, that differences in the inflammatory response to cholestasis in ICAM^-/- and lpr mice are not accompanied by significant differences in hepatobiliary transporter expression in response to CBDL, indicating that retained biliary constituents (e.g., bile acids and bilirubin), which were elevated to similar extents (Gujral et al., 2004a), rather than inflammatory mediators and oxidative stress may determine hepatobiliary transporter expression in cholestasis. However, we found strain-specific differences in transporter expression. As such, endotoxin-resistant animals did not show reduced canalicular Bsep and Mrp2 expressions after CBDL, effects which are thought to be pro-cholestatic (Trauner et al., 1997a; Lee et al., 2000). In addition, only endotoxin-resistant mice displayed Mrp4 induction, and induction of Ostß was more pronounced compared with endotoxin-sensitive mice. Induction of basolateral Mrp4 and Ostß is thought to be anti-cholestatic by acting as adaptive bile acid overflow systems under cholestatic conditions, thereby reducing the potentially hepatotoxic intracellular bile acid load (Wagner et al., 2003; Boyer et al., 2006). Although factors other than susceptibility to endotoxins might account for observed transporter differences between both strains, it is attractive to speculate that the preservation of canalicular transporter systems in line with the induction of basolateral overflow pumps could at least in part contribute to reduced cholestatic injury in this mouse strain.

Differences in the degree of inflammation and oxidative stress within genotypes, however, did not markedly affect canalicular and basolateral transporter expression in wild-type, lCAM^-/-, and lpr mice after CBDL. In general, canalicular bile acid transporters such as Bsep and Mrp2 are down-regulated by proinflammatory cytokines and induced by bile acids (Trauner and Boyer, 2003). Bsep expression during longer-standing obstructive cholestasis is, however, relatively well preserved compared with other membrane transporters in animal models as well as in human cholestatic liver disease (Lee et al., 2000; Zollner et al., 2001, 2003b; Wagner et al., 2003). The preserved Bsep expression may operate as an adaptive mechanism under cholestatic conditions and may still promote the biliary excretion of accumulating bile acids (Lee et al., 2000). Also similar to Bsep, Mrp2 expression did not markedly differ among the genotypes after CBDL. In experimental models of inflammation, lipopolysaccharide treatment profoundly reduced Mrp2 expression levels (Trauner et al., 1997a; Geier et al., 2003). Reduced expression and binding activity of transactivating nuclear receptors (Kim et al., 2003; Fang et al., 2004) as well as post-transcriptional mechanisms (e.g., retrieval from the canalicular membrane) (Kubitz et al., 1999) may be responsible for transporter reduction in inflammation. On the other hand, activation of nuclear receptors such as farnesoid X receptor by bile acids results in increased Mrp2 expression (Fickert et al., 2001; Schuetz et al., 2001; Zollner et al., 2003a). The findings of the current study indicate that the decrease of Mrp2 in endotoxin-sensitive animals cannot be counteracted by accumulating bile acids despite differences in the inflammatory response to cholestatic injury. Resistance to endotoxin, however, prevented Mrp2 down-regulation.

Down-regulation of the major bile acid uptake system Ntcp is a common protective mechanism of liver cells under cholestatic conditions in rodents and human (Gartung et al., 1996; Trauner et al., 1998; Fickert et al., 2001; Zollner et al., 2001, 2003b). In contrast to canalicular bile acid transporters, proinflammatory cytokines as well as bile acids are able to down-regulate Ntcp. In our experiments, Ntcp was down-regulated independent of the degree of inflammation and oxidative stress, suggesting that retention of bile acids may account for protective Ntcp repression in obstructive cholestasis (Geier et al., 2005b; Zollner et al., 2005). This finding is in line with our previous observation that Kupffer cell depletion and cytokine antagonists in CBDL rodents did not affect Ntcp down-regulation (Geier et al., 2005b).

Basolateral bile acid export pumps such as Mrp3, Mrp4, and Ost/ß are adaptively induced by bile acids in bile acid feeding experiments and CBDL, as well as in human cholestatic liver disease (Wagner et al., 2003; Zollner et al., 2003a,b; Boyer et al., 2006). Endotoxin/cytokine challenge was reported to either down-regulate (Hartmann et al., 2002; Siewert et al., 2004; Teng and Piquette-Miller, 2005) or induce (Bohan et al., 2003; Lee and Piquette-Miller, 2003; Cherrington et al., 2004; Donner et al., 2004) Mrp3 expression, whereas effects on Mrp4 and Ost/ß expression have not been studied yet. We observed a marginally higher adaptive Mrp3 induction in ICAM^-/- and lpr compared with wild-type mice of the endotoxin-sensitive strain in response to CBDL. The higher Mrp3 induction is obviously due to lower Mrp3 baseline expression in sham-operated ICAM^-/- and lpr mice, but may also, to some extent, contribute to lower hepatocellular injury as observed in these animals. Higher Mrp3 expression levels in mice with reduced inflammation rather supports a suppressive role of inflammatory mediators for Mrp3 expression (Hartmann et al., 2002; Siewert et al., 2004; Teng and Piquette-Miller, 2005). Mrp4 expression after CBDL was independent of ICAM and Fas receptor expression, which therefore implies only a minor role, if any, for inflammation and proinflammatory cytokines in Mrp4 regulation. The subunits of the heteromeric organic solute transporter Ost/ß were differentially expressed as early as 3 days after CBDL. The Ostß subunit is more sensitive to bile acids than the Ost subunit in regard to inducibility by bile acids and CBDL, as well as their regulation by farnesoid X receptor (Boyer et al., 2006; Zollner et al., 2006b). This may explain why Ost is down-regulated as early as 3 days after CBDL, and Ostß is already markedly induced. Reduction in Ost expression was more pronounced in wild-type animals, but this did not significantly differ between genotypes. Similarly, Ostß induction was independent of ICAM and Fas expression, which again indicates that accumulated biliary constituents rather than cytokines might be involved in the regulation of transporter gene expression in CBDL.

These findings are not only important from a regulatory point of view, but also may have potential therapeutic implications. Adaptive transport systems (e.g., Mrp3, Mrp4, Ost/ß) are endogenously over-expressed largely independent of the degree of inflammation. Therefore, it is reasonable to speculate that additional exogenous stimulation of these transporters, e.g., via their regulating nuclear receptors, may further enhance adaptive transporter response irrespective of the inflammatory component. Reduced transporter expression in the inflammatory-competent mice would have suggested a compromised transporter regulation, as is shown for the acute phase responses, and, thus, less effective nuclear receptor stimulation (Beigneux et al., 2002; Kim et al., 2003).

In summary, we herein demonstrate that reduced inflammation and oxidative stress in ICAM^-/- and lpr mice do not markedly affect hepatobiliary transporter expression in obstructive cholestasis. Rather, the retention of biliary constituents such as bile acids and bilirubin may determine expression of hepatic transport proteins in CBDL. Moreover, differences in hepatobiliary transporter expression cannot sufficiently explain reduced cholestatic liver injury observed in ICAM^-/- and lpr mice after CBDL. In contrast, differences in neutrophil accumulation, cytokine levels, and oxidative stress modify the extent of cholestatic liver injury in these models.

	Footnotes

 
This work was supported by Grant P18613 [GenBank] -B05 from the Austrian Science Foundation and by National Institutes of Health Grant AA-12916.

doi:10.1124/dmd.107.015610.

ABBREVIATIONS: ABC, ATP-binding cassette; Bsep (Abcb11), bile salt export pump; CBDL, common bile duct ligation; ICAM-1, intercellular adhesion molecule 1; lpr mice, Fas receptor-deficient mice; Mrp, multidrug resistance-associated protein; Ntcp (Slc10a1), Na⁺/taurocholate cotransporter; Oatp, organic anion transporter; Ost, organic solute transporter.

Address correspondence to: Dr. Michael Trauner, Professor of Medicine and Molecular Hepatology, Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Dept. of Medicine, Medical University Graz, Auenbruggerplatz 15, A-8036 Graz, Austria. E-mail: michael.trauner{at}medunigraz.at

	References

Top Abstract Materials and Methods Results Discussion References

 


Beigneux AP, Moser AH, Shigenaga JK, Grunfeld C, and Feingold KR (2002) Reduction in cytochrome P-450 enzyme expression is associated with repression of CAR (constitutive androstane receptor) and PXR (pregnane X receptor) in mouse liver during the acute phase response. Biochem Biophys Res Commun 293: 145-149.[CrossRef][Medline]

Bohan A, Chen WS, Denson LA, Held MA, and Boyer JL (2003) Tumor necrosis factor alpha-dependent up-regulation of Lrh-1 and Mrp3(Abcc3) reduces liver injury in obstructive cholestasis. J Biol Chem 278: 36688-36698.[Abstract/Free Full Text]

Boyer JL, Trauner M, Mennone A, Soroka CJ, Cai SY, Moustafa T, Zollner G, Lee JY, and Ballatori N (2006) Upregulation of a basolateral FXR-dependent bile acid efflux transporter OSTalpha-OSTbeta in cholestasis in humans and rodents. Am J Physiol Gastrointest Liver Physiol 290: G1124-G1130.[Abstract/Free Full Text]

Cherrington NJ, Slitt AL, Li N, and Klaassen CD (2004) Lipopolysaccharide-mediated regulation of hepatic transporter mRNA levels in rats. Drug Metab Dispos 32: 734-741.[Abstract/Free Full Text]

Donner MG, Warskulat U, Saha N, and Haussinger D (2004) Enhanced expression of basolateral multidrug resistance protein isoforms Mrp3 and Mrp5 in rat liver by LPS. Biol Chem 385: 331-339.[CrossRef][Medline]

Fang C, Yoon S, Tindberg N, Jarvelainen HA, Lindros KO, and Ingelman-Sundberg M (2004) Hepatic expression of multiple acute phase proteins and down-regulation of nuclear receptors after acute endotoxin exposure. Biochem Pharmacol 67: 1389-1397.[CrossRef][Medline]

Fickert P, Fuchsbichler A, Wagner M, Zollner G, Kaser A, Tilg H, Krause R, Lammert F, Langner C, Zatloukal K, et al. (2004) Regurgitation of bile acids from leaky bile ducts causes sclerosing cholangitis in Mdr2 (Abcb4) knockout mice. Gastroenterology 127: 261-274.[CrossRef]

Fickert P, Zollner G, Fuchsbichler A, Stumptner C, Pojer C, Zenz R, Lammert F, Stieger B, Meier PJ, Zatloukal K, et al. (2001) Effects of ursodeoxycholic and cholic acid feeding on hepatocellular transporter expression in mouse liver. Gastroenterology 121: 170-183.[CrossRef][Medline]

Gartung C, Ananthanarayanan M, Rahman MA, Schuele S, Nundy S, Soroka CJ, Stolz A, Suchy FJ, and Boyer JL (1996) Down-regulation of expression and function of the rat liver Na+/bile acid cotransporter in extrahepatic cholestasis. Gastroenterology 110: 199-209.[CrossRef][Medline]

Geier A, Dietrich CG, Voigt S, Ananthanarayanan M, Lammert F, Schmitz A, Trauner M, Wasmuth HE, Boraschi D, Balasubramaniyan N, et al. (2005a) Cytokine-dependent regulation of hepatic organic anion transporter gene transactivators in mouse liver. Am J Physiol Gastrointest Liver Physiol 289: G831-841.[Abstract/Free Full Text]

Geier A, Dietrich CG, Voigt S, Kim SK, Gerloff T, Kullak-Ublick GA, Lorenzen J, Matern S, and Gartung C (2003) Effects of proinflammatory cytokines on rat organic anion transporters during toxic liver injury and cholestasis. Hepatology 38: 345-354.[Medline]

Geier A, Wagner M, Dietrich CG, and Trauner M (2007) Principles of hepatic organic anion transporter regulation during cholestasis, inflammation and liver regeneration. Biochim Bio-phys Acta 1773: 283-308.[Medline]

Geier A, Zollner G, Dietrich CG, Wagner M, Fickert P, Denk H, van Rooijen N, Matern S, Gartung C, and Trauner M (2005b) Cytokine-independent repression of rodent Ntcp in obstructive cholestasis. Hepatology 41: 470-477.[CrossRef]

Green RM, Beier D, and Gollan JL (1996) Regulation of hepatocyte bile salt transporters by endotoxin and inflammatory cytokines in rodents. Gastroenterology 111: 193-198.[CrossRef][Medline]

Gujral JS, Farhood A, Bajt ML, and Jaeschke H (2003) Neutrophils aggravate acute liver injury during obstructive cholestasis in bile duct-ligated mice. Hepatology 38: 355-363.[Medline]

Gujral JS, Liu J, Farhood A, Hinson JA, and Jaeschke H (2004a) Functional importance of ICAM-1 in the mechanism of neutrophil-induced liver injury in bile duct-ligated mice. Am J Physiol Gastrointest Liver Physiol 286: G499-507.[Abstract/Free Full Text]

Gujral JS, Liu J, Farhood A, and Jaeschke H (2004b) Reduced oncotic necrosis in Fas receptor-deficient C57BL/6J-lpr mice after bile duct ligation. Hepatology 40: 998-1007.[CrossRef]

Hartmann G, Cheung AK, and Piquette-Miller M (2002) Inflammatory cytokines, but not bile acids, regulate expression of murine hepatic anion transporters in endotoxemia. J Pharmacol Exp Ther 303: 273-281.[Abstract/Free Full Text]

Kim MS, Shigenaga J, Moser A, Feingold K, and Grunfeld C (2003) Repression of farnesoid X receptor during the acute phase response. J Biol Chem 278: 8988-8995.[Abstract/Free Full Text]

Kubitz R, Wettstein M, Warskulat U, and Haussinger D (1999) Regulation of the multidrug resistance protein 2 in the rat liver by lipopolysaccharide and dexamethasone. Gastroenterology 116: 401-410.[CrossRef][Medline]

Lee G and Piquette-Miller M (2003) Cytokines alter the expression and activity of the multidrug resistance transporters in human hepatoma cell lines; analysis using RT-PCR and cDNA microarrays. J Pharm Sci 92: 2152-2163.[CrossRef][Medline]

Lee JM, Trauner M, Soroka CJ, Stieger B, Meier PJ, and Boyer JL (2000) Expression of the bile salt export pump is maintained after chronic cholestasis in the rat. Gastroenterology 118: 163-172.[CrossRef][Medline]

Li N and Klaassen CD (2004) Role of liver-enriched transcription factors in the down-regulation of organic anion transporting polypeptide 4 (oatp4; oatplb2; slc21a10) by lipopolysaccharide. Mol Pharmacol 66: 694-701.[Abstract/Free Full Text]

Perez LM, Milkiewicz P, Elias E, Coleman R, Sanchez Pozzi EJ, and Roma MG (2006) Oxidative stress induces internalization of the bile salt export pump, Bsep, and bile salt secretory failure in isolated rat hepatocyte couplets: a role for protein kinase C and prevention by protein kinase A. Toxicol Sci 91: 150-158.[Abstract/Free Full Text]

Schuetz EG, Strom S, Yasuda K, Lecureur V, Assem M, Brimer C, Lamba J, Kim RB, Ramachandran V, Komoroski BJ, et al. (2001) Disrupted bile acid homeostasis reveals an unexpected interaction among nuclear hormone receptors, transporters, and cytochrome P450. J Biol Chem 276: 39411-39418.[Abstract/Free Full Text]

Siewert E, Dietrich CG, Lammert F, Heinrich PC, Matern S, Gartung C, and Geier A (2004) Interleukin-6 regulates hepatic transporters during acute-phase response. Biochem Biophys Res Commun 322: 232-238.[CrossRef][Medline]

Teng S and Piquette-Miller M (2005) The involvement of the pregnane X receptor in hepatic gene regulation during inflammation in mice. J Pharmacol Exp Ther 312: 841-848.[Abstract/Free Full Text]

Trauner M, Arrese M, Lee H, Boyer JL, and Karpen SJ (1998) Endotoxin downregulates rat hepatic ntcp gene expression via decreased activity of critical transcription factors. J Clin Invest 101: 2092-2100.[Medline]

Trauner M, Arrese M, Soroka CJ, Ananthanarayanan M, Koeppel TA, Schlosser SF, Suchy FJ, Keppler D, and Boyer JL (1997a) The rat canalicular conjugate export pump (Mrp2) is down-regulated in intrahepatic and obstructive cholestasis. Gastroenterology 113: 255-264.[CrossRef][Medline]

Trauner M and Boyer JL (2003) Bile salt transporters: molecular characterization, function, and regulation. Physiol Rev 83: 633-671.[Abstract/Free Full Text]

Trauner M and Boyer JL (2004) Cholestatic syndromes. Curr Opin Gastroenterol 20: 220-230.[CrossRef][Medline]

Trauner M, Nathanson MH, Rydberg SA, Koeppel TA, Gartung C, Sessa WC, and Boyer JL (1997b) Endotoxin impairs biliary glutathione and HCO3-excretion and blocks the choleretic effect of nitric oxide in rat liver. Hepatology 25: 1184-1191.[CrossRef][Medline]

Wagner M, Fickert P, Zollner G, Fuchsbichler A, Silbert D, Tsybrovskyy O, Zatloukal K, Guo GL, Schuetz JD, Gonzalez FJ, et al. (2003) Role of farnesoid X receptor in determining hepatic ABC transporter expression and liver injury in bile duct-ligated mice. Gastroenterology 125: 825-838.[CrossRef]

Wagner M, Halilbasic E, Marschall HU, Zollner G, Fickert P, Langner C, Zatloukal K, Denk H, and Trauner M (2005) CAR and PXR agonists stimulate hepatic bile acid and bilirubin detoxification and elimination pathways in mice. Hepatology 42: 420-430.[CrossRef][Medline]

Wang R, Salem M, Yousef IM, Tuchweber B, Lam P, Childs SJ, Helgason CD, Ackerley C, Phillips MJ, and Ling V (2001) Targeted inactivation of sister of P-glycoprotein gene (spgp) in mice results in nonprogressive but persistent intrahepatic cholestasis. Proc Natl Acad Sci U SA 98: 2011-2016.[Abstract/Free Full Text]

Zollner G, Fickert P, Fuchsbichler A, Silbert D, Wagner M, Arbeiter S, Gonzalez FJ, Marschall HU, Zatloukal K, Denk H, et al. (2003a) Role of nuclear bile acid receptor, FXR, in adaptive ABC transporter regulation by cholic and ursodeoxycholic acid in mouse liver, kidney and intestine. J Hepatol 39: 480-488.[CrossRef][Medline]

Zollner G, Fickert P, Silbert D, Fuchsbichler A, Marschall HU, Zatloukal K, Denk H, and Trauner M (2003b) Adaptive changes in hepatobiliary transporter expression in primary biliary cirrhosis. J Hepatol 38: 717-727.[CrossRef][Medline]

Zollner G, Fickert P, Zenz R, Fuchsbichler A, Stumptner C, Kenner L, Ferenci P, Stauber RE, Krejs GJ, Denk H, et al. (2001) Hepatobiliary transporter expression in percutaneous liver biopsies of patients with cholestatic liver diseases. Hepatology 33: 633-646.[CrossRef]

Zollner G, Marschall HU, Wagner M, and Trauner M (2006a) Role of nuclear receptors in the adaptive response to bile acids and cholestasis: pathogenetic and therapeutic considerations. Mol Pharm 3: 231-251.[CrossRef][Medline]

Zollner G, Wagner M, Fickert P, Geier A, Fuchsbichler A, Silbert D, Gumhold J, Zatloukal K, Kaser A, Tilg H, et al. (2005) Role of nuclear receptors and hepatocyte-enriched transcription factors for Ntcp repression in biliary obstruction in mouse liver. Am J Physiol Gastrointest Liver Physiol 289: G798-805.[Abstract/Free Full Text]

Zollner G, Wagner M, Moustafa T, Fickert P, Silbert D, Gumhold J, Fuchsbichler A, Halilbasic E, Denk H, Marschall HU, et al. (2006b) Coordinated induction of bile acid detoxification and alternative elimination in mice: role of FXR-regulated organic solute transporter-alpha/beta in the adaptive response to bile acids. Am J Physiol Gastrointest Liver Physiol 290: G923-932.[Abstract/Free Full Text]

This Article Abstract Full Text (PDF) All Versions of this Article: dmd.107.015610v1 35/9/1694    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wagner, M. Articles by Trauner, M. Search for Related Content PubMed PubMed Citation Articles by Wagner, M. Articles by Trauner, M.