Ductular reaction (DR) is characterized by the proliferation of reactive bile ducts induced by liver injuries. DR is pathologically recognized as bile duct hyperplasia and is commonly observed in ...biliary disorders. It can also be identified in various liver disorders including nonalcoholic fatty liver disease. DR is associated with liver fibrosis and damage, and the extent of DR parallels to patient mortality. DR raises scientific interests because it is associated with transdifferentiation of liver cells and may play an important role in hepatic regeneration. The origin of active cells during DR can be cholangiocytes, hepatocytes, or hepatic progenitor cells, and associated signaling pathways could differ depending on the specific liver injury or animal models used in the study. Although further studies are needed to elucidate detailed mechanisms and the functional roles in liver diseases, DR can be a therapeutic target to inhibit liver fibrosis and to promote liver regeneration. This review summarizes previous studies of DR identified in patients and animal models as well as currently understood mechanisms of DR.
Increased lymphangiogenesis and lymph node metastasis, the important prognostic indicators of aggressive hepatobiliary malignancies such as hepatocellular cancer and cholangiocarcinoma, are ...associated with poor patient outcome. The liver produces 25% to 50% of total lymphatic fluid in the body and has a dense network of lymphatic vessels. The lymphatic system plays critical roles in fluid homeostasis and inflammation and immune response. Yet, lymphatic vessel alterations and function are grossly understudied in the context of liver pathology. Expansion of the lymphatic network has been documented in clinical samples of liver cancer; and although largely overlooked in the liver, tumor-induced lymphangiogenesis is an important player, increasing tumor metastasis in several cancers. This review aims to provide a detailed perspective on the current knowledge of alterations in the hepatic lymphatic system during liver malignancies, as well as various molecular signaling mechanisms and growth factors that may provide future targets for therapeutic intervention. In addition, the review also addresses current mechanisms and bottlenecks for effective therapeutic targeting of tumor-associated lymphangiogenesis.
Injury to the biliary epithelium triggers inflammation and fibrosis, which can result in severe liver diseases and may progress to malignancy. Development of a type 1 immune response has been linked ...to biliary injury pathogenesis; however, a subset of patients with biliary atresia, the most common childhood cholangiopathy, exhibit increased levels of Th2-promoting cytokines. The relationship among different inflammatory drivers, epithelial repair, and carcinogenesis remains unclear. Here, we determined that the Th2-activating cytokine IL-33 is elevated in biliary atresia patient serum and in the livers and bile ducts of mice with experimental biliary atresia. Administration of IL-33 to WT mice markedly increased cholangiocyte proliferation and promoted sustained cell growth, resulting in dramatic and rapid enlargement of extrahepatic bile ducts. The IL-33-dependent proliferative response was mediated by an increase in the number of type 2 innate lymphoid cells (ILC2s), which released high levels of IL-13 that in turn promoted cholangiocyte hyperplasia. Induction of the IL-33/ILC2/IL-13 circuit in a murine biliary injury model promoted epithelial repair; however, induction of this circuit in mice with constitutive activation of AKT and YAP in bile ducts induced cholangiocarcinoma with liver metastases. These findings reveal that IL-33 mediates epithelial proliferation and suggest that activation of IL-33/ILC2/IL-13 may improve biliary repair and disruption of the circuit may block progression of carcinogenesis.
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A therapeutically challenging subset of cells, termed cancer stem cells (CSCs) are responsible for cholangiocarcinoma (CCA) clinical severity. Presence of tumor-associated macrophages ...(TAMs) has prognostic significance in CCA and other malignancies. Thus, we hypothesized that CSCs may actively shape their tumor-supportive immune niche.
CCA cells were cultured in 3D conditions to generate spheres. CCA sphere analysis of in vivo tumorigenic-engraftment in immune-deficient mice and molecular characterization was performed. The in vitro and in vivo effect of CCA spheres on macrophage precursors was tested after culturing healthy donor cluster of differentiation (CD)14+ with CCA-sphere conditioned medium.
CCA spheres engrafted in 100% of transplanted mice and revealed a significant 20.3-fold increase in tumor-initiating fraction (p=0.0011) and a sustained tumorigenic potential through diverse xenograft-generations. Moreover, CCA spheres were highly enriched for CSC, liver cancer and embryonic stem cell markers both at gene and protein levels. Next, fluorescence-activated cell sorting analysis showed that in the presence of CCA sphere conditioned medium, CD14+ macrophages expressed key markers (CD68, CD115, human leukocyte antigen-D related, CD206) indicating that CCA sphere conditioned medium was a strong macrophage-activator. Gene expression profile of CCA sphere activated macrophages revealed unique molecular TAM-like features confirmed by high invasion capacity. Also, freshly isolated macrophages from CCA resections recapitulated a similar molecular phenotype of in vitro-educated macrophages. Consistent with invasive features, the largest CD163+ set was found in the tumor front of human CCA specimens (n=23) and correlated with a high level of serum cancer antigen 19.9 (n=17). Among mediators released by CCA spheres, only interleukin (IL)13, IL34 and osteoactivin were detected and further confirmed in CCA patient sera (n=12). Surprisingly, a significant association of IL13, IL34 and osteoactivin with sphere stem-like genes was provided by a CCA database (n=104). In vitro combination of IL13, IL34, osteoactivin was responsible for macrophage-differentiation and invasion, as well as for in vivo tumor-promoting effect.
CCA-CSCs molded a specific subset of stem-like associated macrophages thus providing a rationale for a synergistic therapeutic strategy for CCA-disease.
Immune plasticity represents an important hallmark of tumor outcome. Since cancer stem cells are able to manipulate stromal cells to their needs, a better definition of the key dysregulated immune subtypes responsible for cooperating in supporting tumor initiation may facilitate the development of new therapeutic approaches. Considering that human cholangiocarcinoma represents a clinical emergency, it is essential to move to predictive models in order to understand the adaptive process of macrophage component (imprinting, polarization and maintenance) engaged by tumor stem-like compartment.
Mechanisms of cholangiocyte responses to injury Sato, Keisaku; Meng, Fanyin; Giang, Thao ...
Biochimica et biophysica acta. Molecular basis of disease,
04/2018, Volume:
1864, Issue:
4
Journal Article
Peer reviewed
Open access
Cholangiocytes, epithelial cells that line the biliary epithelium, are the primary target cells for cholangiopathies including primary sclerosing cholangitis and primary biliary cholangitis. ...Quiescent cholangiocytes respond to biliary damage and acquire an activated neuroendocrine phenotype to maintain the homeostasis of the liver. The typical response of cholangiocytes is proliferation leading to bile duct hyperplasia, which is a characteristic of cholestatic liver diseases. Current studies have identified various signaling pathways that are associated with cholangiocyte proliferation/loss and liver fibrosis in cholangiopathies using human samples and rodent models. Although recent studies have demonstrated that extracellular vesicles and microRNAs could be mediators that regulate these messenger/receptor axes, further studies are required to confirm their roles. This review summarizes current studies of biliary response and cholangiocyte proliferation during cholestatic liver injury with particular emphasis on the secretin/secretin receptor axis. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.
•Cholangiocytes are heterogeneous showing different responses to injury.•Typical cholangiocyte responses are proliferation and fibrogenesis.•The secretin/secretin receptor axis is important for cholangiocyte responses.•There are several other pathways associated with cholangiocyte proliferation.
The biliary tree is an essential component of transplantable human liver tissue. Despite recent advances in liver tissue engineering, attempts at re-creating the intrahepatic biliary tree have not ...progressed significantly. The finer branches of the biliary tree are structurally and functionally complex and heterogeneous and require harnessing innate developmental processes for their regrowth. Here we demonstrate the ability of decellularized liver extracellular matrix (dECM) hydrogels to induce the in vitro formation of complex biliary networks using encapsulated immortalized mouse small biliary epithelial cells (cholangiocytes). This phenomenon is not observed using immortalized mouse large cholangiocytes, or with purified collagen 1 gels or Matrigel. We also show phenotypic stability via immunostaining for specific cholangiocyte markers. Moreover, tight junction formation and maturation was observed to occur between cholangiocytes, exhibiting polarization and transporter activity. To better define the mechanism of duct formation, we utilized three fluorescently labeled, but otherwise identical populations of cholangiocytes. The cells, in a proximity dependent manner, either branch out clonally, radiating from a single nucleation point, or assemble into multi-colored structures arising from separate populations. These findings present liver dECM as a promising biomaterial for intrahepatic bile duct tissue engineering and as a tool to study duct remodeling in vitro.
Tumor metastasis to the draining lymph nodes is critical in patient prognosis and is tightly regulated by molecular interactions mediated by lymphatic endothelial cells (LECs). The underlying ...mechanisms remain undefined in the head and neck squamous cell carcinomas (HNSCCs). Using HNSCC cells and LECs we determined the mechanisms mediating tumor-lymphatic cross talk. The effects of a pentacyclic triterpenoid, methyl 2-trifluoromethyl-3,11-dioxoolean-1,12-dien-30-oate (CF3DODA-Me), a potent anticancer agent, were studied on cancer-lymphatic interactions. In response to inflammation, LECs induced the chemokine (C-X-C motif) ligand 9/10/11 chemokines with a concomitant increase in the chemokine (C-X-C motif) receptor 3 (CXCR3) in tumor cells. CF3DODA-Me showed antiproliferative effects on tumor cells, altered cellular bioenergetics, suppressed matrix metalloproteinases and chemokine receptors, and the induction of CXCL11-CXCR3 axis and phosphatidylinositol 3-kinase/AKT pathways. Tumor cell migration to LECs was inhibited by blocking CXCL11 whereas recombinant CXCL11 significantly induced tumor migration, epithelial-to-mesenchymal transition, and matrix remodeling. Immunohistochemical analysis of HNSCC tumor arrays showed enhanced expression of CXCR3 and increased lymphatic vessel infiltration. Furthermore, The Cancer Genome Atlas RNA-sequencing data from HNSCC patients also showed a positive correlation between CXCR3 expression and lymphovascular invasion. Collectively, our data suggest a novel mechanism for cross talk between the LECs and HNSCC tumors through the CXCR3-CXCL11 axis and elucidate the role of the triterpenoid CF3DODA-Me in abrogating several of these tumor-promoting pathways.
Substance P (SP) is involved in the proliferation of cholangiocytes in bile duct–ligated (BDL) mice and human cholangiocarcinoma growth by interacting with the neurokinin‐1 receptor (NK‐1R). To ...identify whether SP regulates liver fibrosis during cholestasis, wild‐type or NK‐1R knockout (NK‐1R–/–) mice that received BDL or sham surgery and multidrug resistance protein 2 knockout (Mdr2–/–) mice treated with either an NK‐1R antagonist (L‐733,060) or saline were used. Additionally, wild‐type mice were treated with SP or saline intraperitoneally. In vivo, there was increased expression of tachykinin precursor 1 (coding SP) and NK‐1R in both BDL and Mdr2–/– mice compared to wild‐type mice. Expression of tachykinin precursor 1 and NK‐1R was significantly higher in liver samples from primary sclerosing cholangitis patients compared to healthy controls. Knockout of NK‐1R decreased BDL‐induced liver fibrosis, and treatment with L‐733,060 resulted in decreased liver fibrosis in Mdr2–/– mice, which was shown by decreased sirius red staining, fibrosis gene and protein expression, and reduced transforming growth factor‐β1 levels in serum and cholangiocyte supernatants. Furthermore, we observed that reduced liver fibrosis in NK‐1R–/– mice with BDL surgery or Mdr2–/– mice treated with L‐733,060 was associated with enhanced cellular senescence of hepatic stellate cells and decreased senescence of cholangiocytes. In vitro, L‐733,060 inhibited SP‐induced expression of fibrotic genes in hepatic stellate cells and cholangiocytes; treatment with L‐733,060 partially reversed the SP‐induced decrease of senescence gene expression in cultured hepatic stellate cells and the SP‐induced increase of senescence‐related gene expression in cultured cholangiocytes. Conclusion: Collectively, our results demonstrate the regulatory effects of the SP/NK‐1R axis on liver fibrosis through changes in cellular senescence during cholestatic liver injury. (Hepatology 2017;66:528–541).
Epigenetic changes are associated with the regulation of transcription of key cell regulatory genes micro RNAs (miRNAs) during different types of liver injury. This study evaluated the role of ...methylation-associated miRNA, miR-34a, in alcoholic liver diseases. We identified that ethanol feeding for 4 weeks significantly up-regulated 0.8% of known miRNA compared with controls, including miR-34a. Treatment of normal human hepatocytes (N-Heps) and cholangiocytes human intrahepatic biliary epithelial cells (HiBECs) with ethanol and lipopolysaccharide induced a significant increase of miR-34a expression. Overexpression of miR-34a decreased ethanol-induced apoptosis in both N-Heps and HiBECs. In support of the concept that the 5′-promoter region of miR-34a was noted to be embedded within a CpG island, the expression level of miR-34a was significantly increased after demethylation treatment in N-Heps and HiBECs. By methylation-specific PCR, we confirmed that miR-34a activation is associated with ethanol-linked hypomethylation of the miR-34a promoter. A combination of bioinformatics, dual-luciferase reporter assay, mass spectrometry, and Western blot analysis revealed that caspase-2 and sirtuin 1 are the direct targets of miR-34a. Furthermore, modulation of miR-34a also altered expression of matrix metalloproteases 1 and 2, the mediators involved in hepatic remodeling during alcoholic liver fibrosis. These findings provide the basis for an exciting field in which the epigenomic microRNAs of hepatic cells may be manipulated with potential therapeutic benefits in human alcoholic liver diseases.
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