RESUMO
BACKGROUND AND AIMS: Inflammatory response is crucial for bile acid (BA)-induced cholestatic liver injury, but molecular mechanisms remain to be elucidated. Solute Carrier Family 35 Member C1 (SLC35C1) can transport Guanosine diphosphate-fucose into the Golgi to facilitate protein glycosylation. Its mutation leads to the deficiency of leukocyte adhesion and enhances inflammation in humans. However, little is known about its role in liver diseases. APPROACH AND RESULTS: Hepatic SLC35C1 mRNA transcripts and protein expression were significantly increased in patients with obstructive cholestasis and mouse models of cholestasis. Immunofluorescence revealed that the upregulated SLC35C1 expression mainly occurred in hepatocytes. Liver-specific ablation of Slc35c1 ( Slc35c1 cKO ) significantly aggravated liver injury in mouse models of cholestasis induced by bile duct ligation and 1% cholic acid-feeding, evidenced by increased liver necrosis, inflammation, fibrosis, and bile ductular proliferation. The Slc35c1 cKO increased hepatic chemokine Ccl2 and Cxcl2 expression and T cell, neutrophil, and F4/80 macrophage infiltration but did not affect the levels of serum and liver BA in mouse models of cholestasis. Liquid chromatography with tandem mass spectrometry analysis revealed that hepatic Slc35c1 deficiency substantially reduced the fucosylation of cell-cell adhesion protein CEACAM1 at N153. Mechanistically, cholestatic levels of conjugated BAs stimulated SLC35C1 expression by activating the STAT3 signaling to facilitate CEACAM1 fucosylation at N153, and deficiency in the fucosylation of CEACAM1 at N135 enhanced the BA-stimulated CCL2 and CXCL2 mRNA expression in primary mouse hepatocytes and Primary Liver Carcinoma/Poliomyelitis Research Foundation/5- ASBT cells. CONCLUSIONS: Elevated hepatic SLC35C1 expression attenuates cholestatic liver injury by enhancing CEACAM1 fucosylation to suppress CCL2 and CXCL2 expression and liver inflammation.
RESUMO
BACKGROUND AND AIMS: Bile acids trigger a hepatic inflammatory response, causing cholestatic liver injury. Runt-related transcription factor-1 (RUNX1), primarily known as a master modulator in hematopoiesis, plays a pivotal role in mediating inflammatory responses. However, RUNX1 in hepatocytes is poorly characterized, and its role in cholestasis is unclear. Herein, we aimed to investigate the role of hepatic RUNX1 and its underlying mechanisms in cholestasis. APPROACH AND RESULTS: Hepatic expression of RUNX1 was examined in cholestatic patients and mouse models. Mice with liver-specific ablation of Runx1 were generated. Bile duct ligation and 1% cholic acid diet were used to induce cholestasis in mice. Primary mouse hepatocytes and the human hepatoma PLC/RPF/5- ASBT cell line were used for mechanistic studies. Hepatic RUNX1 mRNA and protein levels were markedly increased in cholestatic patients and mice. Liver-specific deletion of Runx1 aggravated inflammation and liver injury in cholestatic mice induced by bile duct ligation or 1% cholic acid feeding. Mechanistic studies indicated that elevated bile acids stimulated RUNX1 expression by activating the RUNX1 -P2 promoter through JAK/STAT3 signaling. Increased RUNX1 is directly bound to the promotor region of inflammatory chemokines, including CCL2 and CXCL2 , and transcriptionally repressed their expression in hepatocytes, leading to attenuation of liver inflammatory response. Blocking the JAK signaling or STAT3 phosphorylation completely abolished RUNX1 repression of bile acid-induced CCL2 and CXCL2 in hepatocytes. CONCLUSIONS: This study has gained initial evidence establishing the functional role of hepatocyte RUNX1 in alleviating liver inflammation during cholestasis through JAK/STAT3 signaling. Modulating hepatic RUNX1 activity could be a new therapeutic target for cholestasis.
Assuntos
Ácidos e Sais Biliares , Colestase , Inflamação , Animais , Humanos , Camundongos , Ácidos e Sais Biliares/efeitos adversos , Ácidos e Sais Biliares/metabolismo , Colestase/etiologia , Colestase/metabolismo , Ácidos Cólicos/efeitos adversos , Ácidos Cólicos/farmacologia , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Inflamação/etiologia , Inflamação/genética , Inflamação/metabolismo , Fígado/metabolismo , Fator de Transcrição STAT3/metabolismoRESUMO
BACKGROUND & AIMS: The nuclear factor of activated T-cells (NFAT) plays an important role in immune responses by regulating the expression of inflammatory genes. However, it is not known whether NFAT plays any role in the bile acid (BA)-induced hepatic inflammatory response. Thus, we aimed to examine the functional role of NFATc3 in cholestatic liver injury in mice and humans. METHODS: Gene and protein expression and cellular localization were assessed in primary hepatocyte cultures (mouse and human) and cholestatic liver tissues (murine models and patients with primary biliary cholangitis [PBC] or primary sclerosing cholangitis [PSC]) by quantitative PCR, western blot and immunohistochemistry. Specific NFAT inhibitors were used in vivo and in vitro. Gene reporter assays and ChIP-PCR were used to determine promoter activity. RESULTS: NFAT isoforms c1 and c3 were expressed in human and mouse hepatocytes. When treated with cholestatic levels of BAs, nuclear translocation of NFATc3 was increased in both human and mouse hepatocytes and was associated with elevated mRNA levels of IL-8, CXCL2, and CXCL10 in these cells. Blocking NFAT activation with pathway-specific inhibitors or knocking down Nfatc3 expression significantly decreased BA-driven induction of these cytokines in mouse hepatocytes. Nuclear expression of NFATc3/Nfatc3 protein was increased in cholestatic livers, both in mouse models (bile duct ligation or Abcb4-/- mice) and in patients with PBC and PSC in association with elevated tissue levels of Cxcl2 (mice) or IL-8 (humans). Gene reporter assays and ChIP-PCR demonstrated that the NFAT response element in the IL-8 promoter played a key role in BA-induced human IL-8 expression. Finally, blocking NFAT activation in vivo in Abcb4-/- mice reduced cholestatic liver injury. CONCLUSIONS: NFAT plays an important role in BA-stimulated hepatic cytokine expression in cholestasis. Blocking hepatic NFAT activation may reduce cholestatic liver injury in humans. LAY SUMMARY: Bile acid induces liver injury by stimulating the expression of inflammatory genes in hepatocytes through activation of the transcription factor NFAT. Blocking this activation in vitro (in hepatocyte cultures) and in vivo (in cholestatic mice) decreased the expression of inflammatory genes and reduced liver injury.
Assuntos
Colangite Esclerosante/metabolismo , Citocinas/metabolismo , Cirrose Hepática Biliar/metabolismo , Fígado/metabolismo , Fatores de Transcrição NFATC/metabolismo , Transdução de Sinais/efeitos dos fármacos , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Animais , Ácidos e Sais Biliares/metabolismo , Ácidos e Sais Biliares/farmacologia , Células Cultivadas , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Hepatócitos/metabolismo , Humanos , Cirrose Hepática Biliar/tratamento farmacológico , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores de Transcrição NFATC/antagonistas & inibidores , Fatores de Transcrição NFATC/genética , Pirazóis/farmacologia , Pirazóis/uso terapêutico , Transdução de Sinais/genética , Resultado do Tratamento , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATPRESUMO
BACKGROUND & AIMS: Bile acid transporters maintain bile acid homeostasis. Little is known about the functions of some transporters in cholestasis or their regulatory mechanism. We investigated the hepatic expression of solute carrier organic anion transporter family member 3A1 (SLCO3A1, also called OATP3A1) and assessed its functions during development of cholestasis. METHODS: We measured levels of OATP3A1 protein and messenger RNA and localized the protein in liver tissues from 22 patients with cholestasis and 21 patients without cholestasis, using real-time quantitative polymerase chain reaction, immunoblot, and immunofluorescence analyses. We performed experiments with Slco3a1-knockout and C57BL/6J (control) mice. Mice and Sprague-Dawley rats underwent bile duct ligation (BDL) or a sham operation. Some mice were placed on a 1% cholic acid (CA) diet to induce cholestasis or on a control diet. Serum and liver tissues were collected and analyzed; hepatic levels of bile acids and 7-α-C4 were measured using liquid chromatography/mass spectrometry. Human primary hepatocytes and hepatoma (PLC/PRF/5) cell lines were used to study mechanisms that regulate OATP3A1 expression and transport. RESULTS: Hepatic levels of OATP3A1 messenger RNA and protein were significantly increased in liver tissues from patients with cholestasis and from rodents with BDL or 1% CA diet-induced cholestasis. Levels of fibroblast growth factor 19 (FGF19, FGF15 in rodents) were also increased in liver tissues from patients and rodents with cholestasis. FGF19 signaling activated the Sp1 transcription factor and nuclear factor κB to increase expression of OATP3A1 in hepatocytes; we found binding sites for these factors in the SLCO3A1 promoter. Slco3a1-knockout mice had shorter survival times and increased hepatic levels of bile acid, and they developed more liver injury after the 1% CA diet or BDL than control mice. In hepatoma cell lines, we found OATP3A1 to take prostaglandin E2 and thyroxine into cells and efflux bile acids. CONCLUSIONS: We found levels of OATP3A1 to be increased in cholestatic liver tissues from patients and rodents compared with healthy liver tissues. We show that OATP3A1 functions as a bile acid efflux transporter that is up-regulated as an adaptive response to cholestasis.
Assuntos
Ácidos e Sais Biliares/metabolismo , Colestase/metabolismo , Transportadores de Ânions Orgânicos/fisiologia , Animais , MAP Quinases Reguladas por Sinal Extracelular/fisiologia , Fatores de Crescimento de Fibroblastos/análise , Fatores de Crescimento de Fibroblastos/fisiologia , Humanos , Fígado/química , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Transportadores de Ânions Orgânicos/análise , Ratos , Ratos Sprague-Dawley , Transdução de Sinais , Fator de Transcrição Sp1/fisiologia , Fator de Transcrição RelA/fisiologiaRESUMO
The manipulation of bile acid (BA) homeostasis by blocking the ileal apical Na+-dependent bile salt transporter (ASBT/SLC10A2) may have therapeutic effects in nonalcoholic fatty liver disease. We developed a novel ASBT inhibitor, an N-(3,4-o-dichlorophenyl)-2-(3-trifluoromethoxy) benzamide derivative referred to as IMB17-15, and investigated its therapeutic effects and the molecular mechanisms underlying the effects. Syrian golden hamsters were challenged with high-fat diet (HFD) to induce NAFLD and were subsequently administered 400 mg/kg IMB17-15 by gavage daily for 21 days. Serum, liver, and fecal samples were collected for further analysis. Plasma concentration-time profiles of IMB17-15 were also constructed. The human hepatocyte cell line HL-7702 was treated with Oleic acid (OA) with or without IMB17-15. Western blotting and real-time PCR were used to study the molecular mechanisms of IMB17-15. We found that IMB17-15 inhibited ASBT and subsequently suppressed ileal farnesoid X receptor (FXR) and FXR-activated fibroblast growth factor15/19 (FGF15/19) expression, which reduced the hepatic phosphorylated extracellular regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) levels and upregulated the cholesterol 7α-hydroxylase (CYP7A1) activity. Additionally, IMB17-15 stimulated adenosine monophosphate (AMP)-activated protein kinase (AMPKα) phosphorylation and enhanced peroxisome proliferator activated receptor α (PPARα) expression and thus promoted triglyceride (TG) oxidation and high-density lipoprotein cholesterol (HDL-c) metabolism through an ASBT-independent mechanism. In conclusion, a novel ASBT inhibitor known as IMB17-15 protected hamsters against HFD-induced NFALD by manipulating BA and lipid homeostasis. IMB17-15 also reduced lipid deposition in human hepatic cell lines, indicating that it may be useful as a therapy for NAFLD patients.
Assuntos
Benzamidas/uso terapêutico , Hepatopatia Gordurosa não Alcoólica/prevenção & controle , Transportadores de Ânions Orgânicos Dependentes de Sódio/antagonistas & inibidores , Sulfonamidas/uso terapêutico , Simportadores/antagonistas & inibidores , Animais , Benzamidas/farmacocinética , Benzamidas/toxicidade , Linhagem Celular , Citocinas/metabolismo , Dieta Hiperlipídica , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Fígado/patologia , Masculino , Mesocricetus , Camundongos , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/patologia , Sulfonamidas/farmacocinética , Sulfonamidas/toxicidadeRESUMO
In our previous research, ten antioxidant pentapeptides including FYKWP, FTGMD, GFEPY, YLPYA, FPPYERRQ, GFYAA, FSGLR, FPYLRH, VPDDD, and GIEWA were identified from the hydrolysate of miiuy croaker (Miichthys miiuy) swim bladder. In this work, their protective function on H2O2-induced oxidative damage to human umbilical vein endothelial cells (HUVECs) was studied. Results indicated that there was no significant difference in the HUVEC viability between the normal group and the treated groups with the 10 pentapeptides at the concentration of 100 µM for 24 h (p < 0.05). Furthermore, FPYLRH of 100 µg/mL extremely significantly (p < 0.001) increased the viability (80.58% ± 5.01%) of HUVECs with H2O2-induced oxidative damage compared with that of the model group. The protective mechanism indicated that FPYLRH could extremely significantly (p < 0.001) increase the levels of superoxide dismutase (SOD) (211.36 ± 8.29 U/mg prot) and GSH-Px (53.06 ± 2.34 U/mg prot) and decrease the contents of reactive oxygen species (ROS) (139.1 ± 11.8% of control), malondialdehyde (MDA) (13.66 ± 0.71 nM/mg), and nitric oxide (NO) (4.36 ± 0.32 µM/L) at the concentration of 100 µM in HUVECs with H2O2-induced oxidative damage compared with those of the model group. In addition, FPYLRH dose-dependently protected DNA in oxidative damage HUVECs model. These results suggested that FPYLRH could significantly attenuate the H2O2-induced stress injury in HUVECs and might be used as a potential natural antioxidant in the functional food industries.
Assuntos
Antioxidantes/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Oligopeptídeos/farmacologia , Perciformes/metabolismo , Hidrolisados de Proteína/metabolismo , Sacos Aéreos/química , Sacos Aéreos/metabolismo , Sequência de Aminoácidos , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Proteínas de Peixes/química , Proteínas de Peixes/metabolismo , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Oxidantes/farmacologia , Substâncias Protetoras/farmacologia , Hidrolisados de Proteína/química , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismoRESUMO
BACKGROUND & AIMS: Cholestatic liver injury is mediated by bile acid-induced inflammatory responses. We hypothesized that superior therapeutic effects might be achieved by combining treatments that reduce the bile acid pool size with one that blocks inflammation. METHODS: Bile duct-ligated (BDL) rats and Mdr2(Abcb4)-/- mice were treated with all-trans retinoic acid (atRA), a potent inhibitor of bile acid synthesis, 5 mg/kg/d by gavage, or Cenicriviroc (CVC), a known antagonist of CCR2 and CCR5, 50 mg/kg/d alone or in combination for 14 days and 1 month respectively. RESULTS: All-trans retinoic acid alone reduced bile acid pool size and liver necrosis in BDL rats. However, the combination with CVC further reduced liver to body weight ratio, bile acid pool size, plasma liver enzyme, bilirubin, liver necrosis and fibrosis when compared to the atRA treatment. The assessment of hepatic hydroxyproline content further confirmed the reduced liver injury concurrent with reduction of pro-inflammatory cytokines emphasizing the synergistic effects of these two agents. Profiling of hepatic inflammatory cells revealed that combination therapy reduced neutrophils and T cells but not macrophages. The superior therapeutic effects of combination treatment were also confirmed in Mdr2-/- mice where a significant reduction in plasma liver enzymes, bilirubin, liver fibrosis, bile duct proliferation and hepatic infiltration of neutrophils and T cells and expression of cytokines were found. CONCLUSIONS: Multitargeted therapy is an important paradigm for treating cholestatic liver injury. The combination of CVC with atRA or other FXR activators may warrant a clinical trial in patients with cholestatic liver disease.
Assuntos
Ácidos e Sais Biliares/metabolismo , Colestase/tratamento farmacológico , Imidazóis/farmacologia , Hepatopatias/tratamento farmacológico , Tretinoína/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Animais , Colestase/complicações , Colestase/patologia , Modelos Animais de Doenças , Quimioterapia Combinada , Ligadura , Fígado/patologia , Hepatopatias/etiologia , Hepatopatias/patologia , Masculino , Camundongos , Camundongos Knockout , Ratos , Ratos Sprague-Dawley , Receptores de Citocinas/antagonistas & inibidores , Sulfóxidos , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATPRESUMO
The Na+-dependent taurocholate cotransporting polypeptide (NTCP/SLC10A1) is a hepatocyte-specific solute carrier, which plays an important role in maintaining bile salt homeostasis in mammals. The absence of a hepatic Na+-dependent bile salt transport system in marine skate and rainbow trout raises a question regarding the function of the Slc10a1 gene in these species. Here, we have characterized the Slc10a1 gene in the marine skate, Leucoraja erinacea The transcript of skate Slc10a1 (skSlc10a1) encodes 319 amino acids and shares 46% identity to human NTCP (hNTCP) with similar topology to mammalian NTCP. SkSlc10a1 mRNA was mostly confined to the brain and testes with minimal expression in the liver. An FXR-bile salt reporter assay indicated that skSlc10a1 transported taurocholic acid (TCA) and scymnol sulfate, but not as effectively as hNTCP. An [3H]TCA uptake assay revealed that skSlc10a1 functioned as a Na+-dependent transporter, but with low affinity for TCA (Km = 92.4 µM) and scymnol sulfate (Ki = 31 µM), compared with hNTCP (TCA, Km = 5.4 µM; Scymnol sulfate, Ki = 3.5 µM). In contrast, the bile salt concentration in skate plasma was 2 µM, similar to levels seen in mammals. Interestingly, skSlc10a1 demonstrated transport activity for the neurosteroids dehydroepiandrosterone sulfate and estrone-3-sulfate at physiological concentration, similar to hNTCP. Together, our findings indicate that skSlc10a1 is not a physiological bile salt transporter, providing a molecular explanation for the absence of a hepatic Na+-dependent bile salt uptake system in skate. We speculate that Slc10a1 is a neurosteroid transporter in skate that gained its substrate specificity for bile salts later in vertebrate evolution.
Assuntos
Ácidos e Sais Biliares/metabolismo , Transportadores de Ânions Orgânicos Dependentes de Sódio/química , Transportadores de Ânions Orgânicos Dependentes de Sódio/metabolismo , Rajidae/metabolismo , Sódio/metabolismo , Simportadores/química , Simportadores/metabolismo , Ácido Taurocólico/metabolismo , Animais , Ácidos e Sais Biliares/química , Sítios de Ligação , Humanos , Fígado/metabolismo , Especificidade de Órgãos , Transportadores de Ânions Orgânicos Dependentes de Sódio/sangue , Ligação Proteica , Homologia de Sequência , Rajidae/classificação , Sódio/química , Especificidade da Espécie , Relação Estrutura-Atividade , Simportadores/sangue , Ácido Taurocólico/química , Distribuição TecidualRESUMO
GOALS: To perform an exploratory pilot study of all-trans retinoic acid (ATRA) combined with ursodeoxycholic acid (UDCA) in patients with primary sclerosing cholangitis (PSC). BACKGROUND: PSC is a progressive disorder for which there is no accepted therapy. Studies in human hepatocyte cultures and in animal models of cholestasis indicate that ATRA might have beneficial effects in cholestatic disorders. STUDY: ATRA (45 mg/m/d, divided and given twice daily) was combined with moderate-dose UDCA in patients with PSC who had incomplete response to UDCA monotherapy. The combination was administered for 12 weeks, followed by a 12-week washout in which patients returned to UDCA monotherapy. We measured alkaline phosphatase (ALP), alanine aminotransferase (ALT), bilirubin, cholesterol, bile acids, and the bile acid intermediate 7α-hydroxy-4-cholesten-3-one (C4) at baseline, week 12, and after washout. RESULTS: Fifteen patients completed 12 weeks of therapy. The addition of ATRA to UDCA reduced the median serum ALP levels (277±211 to 243±225 U/L, P=0.09) although this, the primary endpoint, did not reach significance. In contrast, median serum ALT (76±55 to 46±32 U/L, P=0.001) and C4 (9.8±19 to 7.9±11 ng/mL, P=0.03) levels significantly decreased. After washout, ALP and C4 levels nonsignificantly increased, whereas ALT levels significantly increased (46±32 to 74±74, P=0.0006), returning to baseline. CONCLUSIONS: In this human pilot study, the combination of ATRA and UDCA did not achieve the primary endpoint (ALP); however, it significantly reduced ALT and the bile acid intermediate C4. ATRA appears to inhibit bile acid synthesis and reduce markers of inflammation, making it a potential candidate for further study in PSC (NCT 01456468).
Assuntos
Colagogos e Coleréticos/administração & dosagem , Colangite Esclerosante/tratamento farmacológico , Tretinoína/administração & dosagem , Ácido Ursodesoxicólico/administração & dosagem , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Alanina Transaminase/sangue , Fosfatase Alcalina/sangue , Ácidos e Sais Biliares/biossíntese , Colangite Esclerosante/sangue , Colangite Esclerosante/fisiopatologia , Colestenonas/sangue , Quimioterapia Combinada , Feminino , Humanos , Fígado/fisiopatologia , Testes de Função Hepática , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: The mechanism by which bile acids induce liver injury in cholestasis remains controversial. Although high levels of bile acids are toxic when applied to liver cells, the level of toxic bile acids in the liver of most cholestatic animals and patients is <10 µM, indicating there must be alternative mechanisms. Recent studies suggest that the inflammatory response may play an important role in bile acid-induced liver injury, as pro-inflammatory cytokine expression is stimulated by bile acids in mouse hepatocyte cultures. To elucidate the mechanisms of bile acid-induced liver injury, we assessed signs of liver damage and gene expression in Abcb4-/- mice, a well-known model for cholestasis. Key Messages: Elevated plasma levels of bile acids were detected as early as 10 days after birth and at all later ages in Abcb4-/- mice compared to their wild-type littermate controls. Parallel increases in expression of Tnfα, Ccl2, Cxcl1, and Cxcl2 mRNA occurred at these early time points and throughout 12 weeks in Abcb4-/- livers. Marked hepatic neutrophil infiltration was first detected in 3-week mice, whereas histological evidence of liver injury was not detected until 6-weeks of age. Subsequent in vitro studies demonstrated that normal hepatocytes but not other non-parenchymal liver cells responded to bile acids with inflammatory cytokine induction. CONCLUSION: Bile acids induce the expression of pro-inflammatory cytokines in hepatocytes in Abcb4-/- mice that initiates an inflammatory response. This inflammatory response plays an important role in the development of cholestatic liver injury in this and other cholestatic conditions. Furthermore, understanding of these inflammatory mechanisms should lead to new therapeutic approaches for cholestatic liver diseases.
Assuntos
Ácidos e Sais Biliares/efeitos adversos , Inflamação/patologia , Fígado/patologia , Envelhecimento/metabolismo , Alanina Transaminase/sangue , Animais , Ácidos e Sais Biliares/sangue , Citocinas/metabolismo , Humanos , Fígado/metabolismo , Camundongos , Neutrófilos/metabolismoRESUMO
BACKGROUND & AIMS: Multidrug resistance-associated protein 2 (MRP2) excretes conjugated organic anions including bilirubin and bile acids. Malfunction of MRP2 leads to jaundice in patients. Studies in rodents indicate that Radixin plays a critical role in determining Mrp2 canalicular membrane expression. However, it is not known how human hepatic MRP2 expression is regulated in cholestasis. METHODS: We assessed liver MRP2 expression in patients with obstructive cholestasis caused by gallstone blockage of bile ducts, and investigated the regulatory mechanism in HepG2 cells. RESULTS: Western blot detected that liver MRP2 protein expression in obstructive cholestatic patients (n=30) was significantly reduced to 25% of the non-cholestatic controls (n=23). Immunoprecipitation identified Ezrin but not Radixin associating with MRP2 in human livers, and the increased amount of phospho-Ezrin Thr567 was positively correlated with the amount of co-precipitated MRP2 in cholestatic livers, whereas Ezrin and Radixin total protein levels were unchanged in cholestasis. Further detailed studies indicate that Ezrin Thr567 phosphorylation plays an important role in MRP2 internalization in HepG2 cells. Since increased expression of PKCα, δ and ε were detected in these cholestatic livers, we further confirmed that these PKCs stimulated Ezrin phosphorylation and reduced MRP2 membrane expression in HepG2 cells. Finally, we identified GP78 as the key ubiquitin ligase E3 involved in MRP2 proteasome degradation. CONCLUSIONS: Activation of liver PKCs during cholestasis leads to Ezrin Thr567 phosphorylation resulting in MRP2 internalization and degradation where ubiquitin ligase E3 GP78 is involved. This process provides a mechanistic explanation for jaundice seen in patients with obstructive cholestasis.
Assuntos
Colestase/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Adulto , Canalículos Biliares/metabolismo , Estudos de Casos e Controles , Colestase/etiologia , Colestase/patologia , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/genética , Feminino , Cálculos Biliares/complicações , Técnicas de Silenciamento de Genes , Células Hep G2 , Humanos , Fígado/metabolismo , Fígado/patologia , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade , Modelos Biológicos , Proteína 2 Associada à Farmacorresistência Múltipla , Fosforilação , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores do Fator Autócrino de Motilidade/antagonistas & inibidores , Receptores do Fator Autócrino de Motilidade/genética , Receptores do Fator Autócrino de Motilidade/metabolismo , Treonina/químicaRESUMO
AIM: (-)-Epigallocatechin-3-gallate (EGCG) is one of the most abundant polyphenols in green tea with strong antioxidant activity and various therapeutic effects. In this study, we investigated the anti-fibrotic effects of EGCG and underlying mechanisms in bile duct-ligated (BDL) rats and a liver fibrosis model in vitro. METHODS: BDL rats were treated with EGCG (25 mg·kg(-1)·d(-1), po) for 14 d, and then the serum, bile and liver samples were collected. Liver fibrosis was assessed by serum, urine and bile biochemistry analyses and morphological studies of liver tissues. TGF-ß1-stimulated human hepatic stellate LX-2 cells were used as a liver fibrosis model in vitro. The expression of liver fibrogenic genes and signaling proteins in the PI3K/Akt/Smad pathway was examined using Western blotting and/or real-time PCR. RESULTS: In BDL rats, EGCG treatment significantly ameliorates liver necrosis, inflammation and fibrosis, and suppressed expression of the genes associated with liver inflammation and fibrogenesis, including TNF-α, IL-1ß, TGF-ß1, MMP-9, α-SMA, and COL1A1. In LX-2 cells, application of EGCG (10, 25 µmol/L) dose-dependently suppressed TGF-ß1-stimulated expression of COL1A1, MMP-2, MMP-9, TGF-ß1, TIMP1, and α-SMA. Furthermore, EGCG significantly suppressed the phosphorylation of Smad2/3 and Akt in the livers of BDL rats and in TGF-ß1-stimulated LX-2 cells. Application of LY294002, a specific inhibitor of PI3K, produced similar effects as EGCG did in TGF-ß1-stimulated LX-2 cells, but co-application of EGCG and LY294002 did not produce additive effects. CONCLUSION: EGCG exerts anti-fibrotic effects in BDL rats and TGF-ß1-stimulated LX-2 cells in vitro via inhibiting the PI3K/Akt/Smad pathway.
Assuntos
Catequina/análogos & derivados , Colestase/complicações , Cirrose Hepática/complicações , Cirrose Hepática/tratamento farmacológico , Fígado/efeitos dos fármacos , Fígado/patologia , Transdução de Sinais/efeitos dos fármacos , Animais , Ductos Biliares/efeitos dos fármacos , Ductos Biliares/metabolismo , Ductos Biliares/patologia , Catequina/uso terapêutico , Linhagem Celular , Células Estreladas do Fígado/efeitos dos fármacos , Células Estreladas do Fígado/metabolismo , Células Estreladas do Fígado/patologia , Humanos , Fígado/metabolismo , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Masculino , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Sprague-Dawley , Proteínas Smad/metabolismoRESUMO
Deficiency of ABCB4 is associated with several forms of cholestasis in humans. Abcb4(-/-) mice also develop cholestasis, but it remains uncertain what role other canalicular transporters play in the development of this disease. We examined the expression of these transporters in Abcb4(-/-) mice compared with their wild-type littermate controls at ages of 10 days and 3, 6, and 12 wk. Elevated plasma bile acid levels were already detected at 10 days and at all ages thereafter in Abcb4(-/-) mice. The expression of Bsep, Mrp2, Atp8b1, Abcg5, and Abcg8 liver proteins did not change at 10 days, but Bsep, Mrp2, and Atp8b1 were reduced, whereas Abcg5 and Abcg8 expression were increased in Abcb4(-/-) mice at all later ages. Lower bile acid concentrations were also detected in the bile of 6-wk-old Abcb4(-/-) mice. Immunofluorescence labeling revealed distorted canalicular architecture in the liver tissue by 12 wk in Abcb4(-/-) mice. Whereas Bsep and Mrp2 remained associated with the apical membrane, Atp8b1 was now localized in discrete punctuate structures adjacent to the canalicular membrane in these mice. Expression of Bsep mRNA was increased in the livers of 10-day-old Abcb4(-/-) mice, whereas Ost-α was decreased. By 12 wk, Bsep, Mrp2, and Abcg5 mRNA were all increased, whereas Ost-α and Ntcp were reduced. These findings indicate that canalicular transporters that determine the formation of bile are altered early in the development of cholestasis in Abcb4(-/-) mice and may contribute to the pathogenesis of cholestasis in this disorder.
Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP , Ácidos e Sais Biliares/biossíntese , Canalículos Biliares , Colestase Intra-Hepática/metabolismo , Proteínas de Membrana Transportadoras , Subfamília B de Transportador de Cassetes de Ligação de ATP/deficiência , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Animais , Ácidos e Sais Biliares/sangue , Canalículos Biliares/lesões , Canalículos Biliares/metabolismo , Canalículos Biliares/patologia , Proteínas de Membrana Transportadoras/análise , Proteínas de Membrana Transportadoras/classificação , Proteínas de Membrana Transportadoras/metabolismo , Camundongos , Modelos Animais , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATPRESUMO
Chronic cholestasis results in liver injury and eventually liver failure. Although ursodeoxycholic acid (UDCA) showed limited benefits in primary biliary cirrhosis, there is an urgent need to develop alternative therapy for chronic cholestatic disorders. Previous studies from our laboratory demonstrated that all-trans-retinoic acid (atRA) is a potent suppressor of CYP7A1, the rate-limiting enzyme in bile acid synthesis. atRA also repressed the expression of tumor growth factor-ß and collagen 1A1 in activated primary human stellate cells and LX2 cells. When administered together with UDCA to bile duct-ligated rats, this combined therapy significantly reduced the bile acid pool size and improved liver conditions. To further examine whether atRA alone or in combination with UDCA has greater beneficial effects than UDCA treatment alone, we assessed this treatment in two additional chronic cholestatic rodent models: α-naphthylisothiocyanate (ANIT)-treated rats and the Mdr2(-/-) (Abcb4(-/-)) knockout mouse. atRA alone significantly reduced bile duct proliferation, inflammation, and hydroxyproline levels in ANIT-treated rats, whereas the combination of atRA and UDCA significantly reduced plasma bile salt level compared with UDCA treatment. atRA alone or in combination with UDCA significantly reduced plasma levels of alkaline phosphatase and bile salts in 12-week-old Mdr2(-/-) mice. Reduced bile duct proliferation and inflammation were also observed in the livers of these mice. Together, atRA alone or in combination with UDCA significantly reduced the severity of liver injury in these two animal models, further supporting the combination treatment of atRA and UDCA as a potential new therapy for patients with chronic cholestatic liver disease who have not responded fully to UDCA.
Assuntos
1-Naftilisotiocianato/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Colagogos e Coleréticos/uso terapêutico , Colestase/tratamento farmacológico , Fígado/efeitos dos fármacos , Tretinoína/uso terapêutico , Animais , Ácidos e Sais Biliares/biossíntese , Ácidos e Sais Biliares/sangue , Proliferação de Células/efeitos dos fármacos , Colagogos e Coleréticos/administração & dosagem , Colestase/induzido quimicamente , Colestase/genética , Colestase/patologia , Doença Crônica , Modelos Animais de Doenças , Quimioterapia Combinada , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos , Camundongos Knockout , Ratos , Ratos Sprague-Dawley , Tretinoína/administração & dosagem , Ácido Ursodesoxicólico/administração & dosagem , Ácido Ursodesoxicólico/uso terapêutico , Membro 4 da Subfamília B de Transportadores de Cassetes de Ligação de ATPRESUMO
The sea lamprey (Petromyzon marinus) is a genetically programmed animal model for biliary atresia, as it loses its bile ducts and gallbladder during metamorphosis. However, in contrast to patients with biliary atresia or other forms of cholestasis who develop progressive disease, the postmetamorphosis lampreys grow normally to adult size. To understand how the adult lamprey thrives without the ability to secrete bile, we examined bile salt homeostasis in larval and adult lampreys. Adult livers were severely cholestatic, with levels of bile salts >1 mM, but no evidence of necrosis, fibrosis, or inflammation. Interestingly, both larvae and adults had normal plasma levels (â¼10 µM) of bile salts. In larvae, petromyzonol sulfate (PZS) was the predominant bile salt, whereas the major bile salts in adult liver were sulfated C27 bile alcohols. Cytotoxicity assays revealed that PZS was highly toxic. Pharmacokinetic studies in free-swimming adults revealed that â¼35% of intravenously injected bromosulfophthalein (BSP) was eliminated over a 72-hour period. Collection of urine and feces demonstrated that both endogenous and exogenous organic anions, including biliverdin, bile salts, and BSP, were predominantly excreted by way of the kidney, with minor amounts also detected in feces. Gene expression analysis detected marked up-regulation of orthologs of known organic anion and bile salt transporters in the kidney, with lesser effects in the intestine and gills in adults compared to larvae. These findings indicate that adult lampreys tolerate cholestasis by altering hepatic bile salt composition, while maintaining normal plasma bile salt levels predominantly through renal excretion of bile products. Therefore, we conclude that strategies to accelerate renal excretion of bile salt and other toxins should be beneficial for patients with cholestasis. (HEPATOLOGY 2013;57:2418-2426).
Assuntos
Ácidos e Sais Biliares/metabolismo , Atresia Biliar/metabolismo , Colestase/metabolismo , Rim/metabolismo , Petromyzon/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Homeostase , Larva/metabolismo , Fígado/metabolismo , Masculino , Transportadores de Ânions Orgânicos/metabolismoRESUMO
UNLABELLED: Multidrug resistance-associated protein 3 (MRP3, ABC subfamily C [ABCC]3) plays an important role in protecting hepatocytes and other tissues by excreting an array of toxic organic anion conjugates, including bile salts. MRP3/ABCC3 expression is increased in the liver of some cholestatic patients, but the molecular mechanism of this up-regulation remains elusive. In this report, we assessed liver MRP3/ABCC3 expression in patients (n = 22) with obstructive cholestasis caused by gallstone blockage of bile ducts and noncholestatic patient controls (n = 22). MRP3/ABCC3 messenger RNA (mRNA) and protein expression were significantly increased by 3.4- and 4.6-fold, respectively, in these cholestatic patients where elevated plasma tumor necrosis factor alpha (TNFα) (4.7-fold; P < 0.01) and hepatic specificity protein 1 transcription factor (SP1) and liver receptor homolog 1 expression (3.1- and 2.1-fold at mRNA level, 3.5- and 2.5-fold at protein level, respectively) were also observed. The induction of hepatic MRP3/ABCC3 mRNA expression is significantly positively correlated with the level of plasma TNFα in these patients. In HepG2 cells, TNFα treatment induced SP1 and MRP3/ABCC3 expression in a dose- and time-dependent manner, where increased phosphorylation of c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) was also detected. These inductions were significantly reduced in the presence of the JNK inhibitor, SP600125. TNFα treatment enhanced HepG2 cell nuclear extract-binding activity to the MRP3/ABCC3 promoter, but was abolished by SP600125, as demonstrated by electrophoretic mobility shift assay (EMSA). An increase in nuclear protein-binding activity to the MRP3/ABCC3 promoter, consisting primarily of SP1, was also observed in liver samples from cholestatic patients, as assessed by supershift EMSA assays. CONCLUSIONS: Our findings indicate that up-regulation of hepatic MRP3/ABCC3 expression in human obstructive cholestasis is likely triggered by TNFα, mediated by activation of JNK/SAPK and SP1.
Assuntos
Colestase/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Fator de Transcrição Sp1/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Adulto , Biópsia por Agulha , Western Blotting , Estudos de Casos e Controles , Colestase/genética , Colestase/patologia , Progressão da Doença , Feminino , Imunofluorescência , Regulação da Expressão Gênica , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Masculino , Pessoa de Meia-Idade , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/métodos , Sensibilidade e Especificidade , Transdução de Sinais , Técnicas de Cultura de Tecidos , Células Tumorais Cultivadas/efeitos dos fármacos , Fator de Necrose Tumoral alfa/sangue , Regulação para CimaRESUMO
The apical sodium-dependent bile salt transporter (ASBT) plays a pivotal role in maintaining bile acid homeostasis. Inhibition of ASBT would reduce bile acid pool size and lower cholesterol levels. In this report, a series of novel arylsulfonylaminobenzanilides were designed and synthesized as potential inhibitors of ASBT. Most of them demonstrated great potency against ASBT's bile acid transport activity. In particular, compound 5g2 inhibited ASBT activity with an IC50 value of 0.11 µM. These compounds represent potential cholesterol-lowering drugs.
Assuntos
Anilidas/química , Anilidas/farmacologia , Sulfonatos de Arila/química , Transportadores de Ânions Orgânicos Dependentes de Sódio/antagonistas & inibidores , Simportadores/antagonistas & inibidores , Anilidas/síntese química , Linhagem Celular , Desenho de Fármacos , Humanos , Estrutura MolecularRESUMO
BACKGROUND & AIMS: OATP1B3/SLCO1B3 is a human liver-specific transporter for the clearance of endogenous compounds (eg, bile acid [BA]) and xenobiotics. The functional role of OATP1B3 in humans has not been characterized, as SLCO1B3 is poorly conserved among species without mouse orthologs. METHODS: Slc10a1-knockout (Slc10a1-/-), Slc10a1hSLCO1B3 (endogenous mouse Slc10a1 promoter-driven human-SLCO1B3 expression in Slc10a1-/- mice), and human SLCO1B3 liver-specific transgenic (hSLCO1B3-LTG) mice were generated and challenged with 0.1% ursodeoxycholic-acid (UDCA), 1% cholic-acid (CA) diet, or bile duct ligation (BDL) for functional studies. Primary hepatocytes and hepatoma-PLC/RPF/5 cells were used for mechanistic studies. RESULTS: Serum BA levels in Slc10a1-/- mice were substantially increased with or without 0.1% UDCA feeding compared with wild-type (WT) mice. This increase was attenuated in Slc10a1hSLCO1B3-mice, indicating that OATP1B3 functions as a significant hepatic BA uptake transporter. In vitro assay using primary hepatocytes from WT, Slc10a1-/-, and Slc10a1hSLCO1B3-mice indicated that OATP1B3 has a similar capacity in taking up taurocholate/TCA as Ntcp. Furthermore, TCA-induced bile flow was significantly impaired in Slc10a1-/- mice but partially recovered in Slc10a1hSLC01B3-mice, indicating that OATP1B3 can partially compensate the NTCP function in vivo. Liver-specific overexpression of OATP1B3 markedly increased the level of hepatic conjugated BA and cholestatic liver injury in 1% CA-fed and BDL mice. Mechanistic studies revealed that conjugated BAs stimulated Ccl2 and Cxcl2 in hepatocytes to increase hepatic neutrophil infiltration and proinflammatory cytokine production (eg, IL-6), which activated STAT3 to repress OATP1B3 expression by binding to its promoter. CONCLUSIONS: Human OATP1B3 is a significant BA uptake transporter and can partially compensate Ntcp for conjugated BA uptake in mice. Its downregulation in cholestasis is an adaptive protective response.
Assuntos
Colestase , Transportadores de Ânions Orgânicos , Humanos , Camundongos , Animais , Fígado/metabolismo , Transportadores de Ânions Orgânicos/metabolismo , Ácidos e Sais Biliares/metabolismo , Ácido UrsodesoxicólicoRESUMO
Tumor necrosis factor receptor superfamily member-12A (TNFRSF12A) plays a critical role in inflammation and cell death. It is expressed in multiple tissues yet extremely low in normal liver. To date, little is known about its role in cholestasis. Therefore, we sought to delineate the role of TNFRSF12A in cholestasis and its underlying mechanisms. Human liver tissues were collected from patients with obstructive cholestasis (OC) or primary biliary cholangitis (PBC). Tnfrsf12a knockout (KO) mice were generated. Cholestasis was induced by bile-duct ligation (BDL) or 0.1% 5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-feeding. Human hepatoma PLC/PRF/5-ASBT and THP1 cell lines or primary mouse hepatocytes were used for mechanistic studies. Hepatic TNFRSF12A expression was markedly increased in OC or PBC patients. Genetic ablation of Tnfrsf12a in BDL- and 0.1%DDC-induced cholestatic mice significantly attenuated cholestatic liver injury with remarkable reduction of hepatocyte pyroptosis but without changing scores of necroptosis and apoptosis. Morphological features of hepatocyte pyroptosis and increased levels of pyroptosis-related proteins, NLRP3, cleaved-Caspase-1, and cleaved-GSDMD in OC patients and BDL-mice confirmed this observation. Further mechanistic studies revealed that bile acids (BAs) induced TNFRSF12A expression by enhancing the transcription factor c-JUN binding to the TNFRSF12A promoter and subsequently initiated hepatocyte pyroptosis by the NFκB/Caspase-1/GSDMD signaling. Interestingly, TWEAK, a typical ligand of TNFRSF12A, secreted by infiltrated macrophages in cholestatic livers, enhanced TNFRSF12A-induced hepatocyte pyroptosis. Taken together, we report, for the first time, that hepatic TNFRSF12A is dramatically increased in human cholestasis. Deletion of TNFRSF12A inhibits BAs-induced hepatocyte pyroptosis through the NFκB/Caspase-1/GSDMD signaling and thereby ameliorates cholestatic liver injury. As such, targeting TNFRSF12A could be a promising approach to treating cholestasis.