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Nrf2 Ameliorates DDC-Induced Sclerosing Cholangitis and Biliary Fibrosis and Improves the Regenerative Capacity of the Liver.

ABSTRACT: The Nrf2 pathway protects against oxidative stress and induces regeneration of various tissues. Here, we investigated whether Nrf2 protects from sclerosing cholangitis and biliary fibrosis and simultaneously induces liver regeneration. Diet containing 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) was fed to Nrf2-KO mice (Nrf2-/-), mice with liver-specific hyperactivated Nrf2 (HKeap1-/-) and wild-type (WT) littermates to induce cholangitis, liver fibrosis, and oval cell expansion. HKeap1-/--mice were protected from almost all DDC-induced injury compared with WT and Nrf2-/-. Liver injury in Nrf2-/- and WT mice was mostly similar, albeit Nrf2-/- suffered more from DDC diet as seen for several parameters. Nrf2 activity was especially important for the expression of the hepatic efflux transporters Abcg2 and Abcc2-4, which are involved in hepatic toxin elimination. Surprisingly, cell proliferation was more enhanced in Nrf2-/-- and HKeap1-/--mice compared with WT. Interestingly, Nrf2-/--mice failed to sufficiently activate oval cell expansion after DDC treatment and showed almost no resident oval cell population under control conditions. The resident oval cell population of untreated HKeap1-/--mice was increased and DDC treatment resulted in a stronger oval cell expansion compared with WT. We provide evidence that Nrf2 activation protects from DDC-induced sclerosing cholangitis and biliary fibrosis. Moreover, our data establish a possible role of Nrf2 in oval cell expansion.

SUBMITTER: Fragoulis A

PROVIDER: S-EPMC6542338 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Nrf2 Ameliorates DDC-Induced Sclerosing Cholangitis and Biliary Fibrosis and Improves the Regenerative Capacity of the Liver.

Fragoulis Athanassios A Schenkel Julia J Herzog Miriam M Schellenberg Tim T Jahr Holger H Pufe Thomas T Trautwein Christian C Kensler Thomas W TW Streetz Konrad L KL Wruck Christoph Jan CJ

Toxicological sciences : an official journal of the Society of Toxicology 20190601 2

The Nrf2 pathway protects against oxidative stress and induces regeneration of various tissues. Here, we investigated whether Nrf2 protects from sclerosing cholangitis and biliary fibrosis and simultaneously induces liver regeneration. Diet containing 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) was fed to Nrf2-KO mice (Nrf2-/-), mice with liver-specific hyperactivated Nrf2 (HKeap1-/-) and wild-type (WT) littermates to induce cholangitis, liver fibrosis, and oval cell expansion. HKeap1-/--mic ...[more]

PMID: 30825315

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Project description:The pathogenesis of primary sclerosing cholangitis (PSC) and the mechanistic link to inflammatory bowel disease remain ill-defined. Ectonucleoside triphosphate diphosphohydrolase-1 (ENTPD1)/clusters of differentiation (CD) 39, the dominant purinergic ecto-enzyme, modulates intestinal inflammation. Here, we have explored the role of CD39 in biliary injury and fibrosis. The impact of CD39 deletion on disease severity was studied in multidrug resistance protein 2 (Mdr2)-/- and 3,5-diethoxycarbonyl-1,4-dihydrocollidine mouse models of sclerosing cholangitis and biliary fibrosis. Antibody-mediated CD8+ T-cell depletion, selective gut decontamination, experimental colitis, and administration of stable adenosine triphosphate (ATP) agonist were performed. Retinoic acid-induced gut imprinting on T cells was studied in vitro. Over half of Mdr2-/-;CD39-/- double mutants, expected by Mendelian genetics, died in utero. Compared to Mdr2-/-;CD39+/+, surviving Mdr2-/-;CD39-/- mice demonstrated exacerbated liver injury, fibrosis, and ductular reaction. CD39 deficiency led to a selective increase in hepatic CD8+ T cells and integrin α4β7, a T-cell gut-tropism receptor. CD8+ cell depletion in Mdr2-/-;CD39-/- mice diminished hepatobiliary injury and fibrosis. Treatment with antibiotics attenuated, whereas dextran sulfate sodium-induced colitis exacerbated, liver fibrosis in Mdr2-/- mice. Colonic administration of αβ-ATP into CD39-sufficient Mdr2-/- mice triggered hepatic CD8+ cell influx and recapitulated the severe phenotype observed in Mdr2-/-;CD39-/- mice. In vitro, addition of ATP promoted the retinoic acid-induced imprinting of gut-homing integrin α4β7 on naive CD8+ cells. CD39 expression was relatively low in human normal or PSC livers but abundantly present on immune cells of the colon and further up-regulated in samples of patients with inflammatory bowel disease. Conclusion: CD39 deletion promotes biliary injury and fibrosis through gut-imprinted CD8+ T cells. Pharmacological modulation of purinergic signaling may represent a promising approach for the treatment of PSC. (Hepatology Communications 2017;1:957-972).

Project description:Purinergic signaling is important in the activation and differentiation of macrophages, which play divergent roles in the pathophysiology of liver fibrosis. The ectonucleotidase CD39 is known to modulate the immunoregulatory phenotype of macrophages, but whether this specifically impacts cholestatic liver injury is unknown. Here, we investigated the role of macrophage-expressed CD39 on the development of biliary injury and fibrosis in a mouse model of sclerosing cholangitis. Myeloid-specific CD39-deficient mice (LysMCreCd39fl/fl) were generated. Global CD39 null (Cd39-/-), wild-type (WT), LysMCreCd39fl/fl, and Cd39fl/fl control mice were exposed to 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to induce biliary fibrosis. Hepatic hydroxyproline levels, liver histology, immunohistochemistry, mRNA expression levels, and serum biochemistry were then assessed. Following 3 weeks of DDC-feeding, Cd39-/- mice exhibited more severe fibrosis, when compared to WT mice as reflected by morphology and increased liver collagen content. Myeloid-specific CD39 deletion in LysMCreCd39fl/fl mice recapitulated the phenotype of global Cd39-/-, after exposure to DDC, and resulted in similar worsening of liver fibrosis when compared to Cd39fl/fl control animals. Further, DDC-treated LysMCreCd39fl/fl mice exhibited elevated serum levels of transaminases and total bilirubin, as well as increased hepatic expression of the profibrogenic genes Tgf-β1, Tnf-α, and α-Sma. However, no clear differences were observed in the expression of macrophage-elaborated specific cytokines between LysMCreCd39fl/fl and Cd39fl/fl animals subjected to biliary injury. Our results in the DDC-induced biliary type liver fibrosis model suggest that loss of CD39 expression on myeloid cells largely accounts for the exacerbated sclerosing cholangitis in global CD39 knockouts. These findings indicate that macrophage expressed CD39 protects from biliary liver injury and fibrosis and support a potential therapeutic target for human hepatobiliary diseases.

Project description:In the multidrug resistance protein 2 (Mdr2)-/- mouse model, low phospholipid bile instigates biliary epithelial injury, sterile inflammation, and fibrosis, thereby recapitulating disease mechanisms implicated in biliary atresia (BA) and primary sclerosing cholangitis. We hypothesize that T lymphocytes contribute to the biliary injury and fibrosis in murine sclerosing cholangitis (SC) and that they are susceptible to suppression by regulatory T cells (Tregs). In juvenile Mdr2-/- mice, intrahepatic CD8+ lymphocytes were expanded, and contraction of intrahepatic Tregs coincided with rising serum alanine transferase and alkaline phosphatase (ALP) levels between days 14-30 of life. Antibody-mediated depletion of intrahepatic CD8+ lymphocytes during that time reduced ALP levels and the expression of osteopontin (Opn), a pro-fibrogenic cytokine. Depletion of intrahepatic Tregs with anti-CD25 antibody between days 7-30 increased intrahepatic CD8+ T cells, Opn expression, and fibrosis. Conversely, expansion of intrahepatic Tregs with interleukin 2/anti-interleukin 2 immune complexes (IL-2c) downregulated hepatic expression of Opn and Tnf, reduced frequency of intrahepatic CD8+ lymphocytes, and diminished biliary injury and fibrosis. Treatment with IL-2c upregulated hepatic Treg expression of CD39, an ectonucleotidase capable of hydrolyzing pro-inflammatory adenosine triphosphate. In vitro, Tregs expressing CD39 suppressed the proliferation of hepatic CD8+ lymphocytes from Mdr2-/- mice more efficiently than those lacking CD39. In infants with BA, infiltration of interlobular bile ducts with CD8+ cells was associated with biliary expression of Opn and its transcription was negatively correlated with mRNA expression of Treg-associated genes. Conclusion: Hepatic CD8+ T lymphocytes drive biliary injury and fibrosis in murine SC. Their proliferation is controlled by hepatic Tregs through the purinergic pathway, which is responsive to IL-2c, suggesting that Treg-directed low-dose Il-2 treatment may be considered as therapy for SC.

Project description:UnlabelledHepatic fibrosis is marked by activation of hepatic stellate cells (HSCs). Cholestatic injury precedes liver fibrosis, and cholangiocytes interact with HSCs promoting fibrosis. Mast cells (MCs) infiltrate following liver injury and release histamine, increasing biliary proliferation. We evaluated if inhibition of MC-derived histamine decreases biliary proliferation and fibrosis. Wild-type and multidrug resistance 2 knockout mice (9-11 weeks) were treated with cromolyn sodium for 1 week to block MC-derived histamine. Biliary mass and proliferation were evaluated by immunohistochemistry for cytokeratin 19 and Ki-67. Bile flow, bicarbonate excretion, and total bile acids were measured in all mice. Fibrosis was evaluated by sirius red/fast green staining and by quantitative polymerase chain reaction for alpha-smooth muscle actin, fibronectin, collagen type 1a, and transforming growth factor-beta 1. HSC activation was evaluated by quantitative polymerase chain reaction in total liver and immunofluorescent staining in tissues for synaptophysin 9. Histamine serum secretion was measured by enzymatic immunoassay. Mouse liver and human liver samples from control or primary sclerosing cholangitis patients were evaluated for MC markers by quantitative polymerase chain reaction and immunohistochemistry. In vitro, cultured MCs were transfected with histidine decarboxylase short hairpin RNA to decrease histamine secretion and subsequently cocultured with cholangiocytes or HSCs prior to measuring fibrosis markers, proliferation, and transforming growth factor-beta 1 secretion. Treatment with cromolyn sodium decreased biliary proliferation, fibrosis, histamine secretion, and bile flow in multidrug resistance 2 knockout mice. Primary sclerosing cholangitis mice and patients have increased MCs. Knockdown of MC histidine decarboxylase decreased cholangiocyte and HSC proliferation/activation.ConclusionMCs are recruited to proliferating cholangiocytes and promote fibrosis. Inhibition of MC-derived histamine decreases fibrosis, and regulation of MC mediators may be therapeutic for primary sclerosing cholangitis. (Hepatology 2016;64:1202-1216).

Dataset Information

Nrf2 Ameliorates DDC-Induced Sclerosing Cholangitis and Biliary Fibrosis and Improves the Regenerative Capacity of the Liver.

Publications

Nrf2 Ameliorates DDC-Induced Sclerosing Cholangitis and Biliary Fibrosis and Improves the Regenerative Capacity of the Liver.

Similar Datasets

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