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.
Mechanisms of cholangiocyte responses to injury Sato, Keisaku; Meng, Fanyin; Giang, Thao ...
Biochimica et biophysica acta. Molecular basis of disease,
04/2018, Letnik:
1864, Številka:
4
Journal Article
Recenzirano
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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.
Cholangiopathies, such as primary sclerosing cholangitis, biliary atresia, and cholangiocarcinoma, have limited experimental models. Not only cholangiocytes but also other hepatic cells including ...hepatic stellate cells and macrophages are involved in the pathophysiology of cholangiopathies, and these hepatic cells orchestrate the coordinated response against diseased conditions. Classic two‐dimensional monolayer cell cultures do not resemble intercellular cell‐to‐cell interaction and communication; however, three‐dimensional cell culture systems, such as organoids and spheroids, can mimic cellular interaction and architecture between hepatic cells. Previous studies have demonstrated the generation of hepatic or biliary organoids/spheroids using various cell sources including pluripotent stem cells, hepatic progenitor cells, primary cells from liver biopsies, and immortalized cell lines. Gene manipulation, such as transfection and transduction can be performed in organoids, and established organoids have functional characteristics which can be suitable for drug screening. This review summarizes current methodologies for organoid/spheroid formation and a potential for three‐dimensional hepatic cell cultures as in vitro models of cholangiopathies.
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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.
Nonalcoholic fatty liver disease (NAFLD) is one of the most important causes of liver-related morbidity and mortality in children. Recently, we have reported the effects of docosahexaenoic acid ...(DHA), the major dietary long-chain polyunsaturated fatty acids, in children with NAFLD. DHA exerts a potent anti-inflammatory activity through the G protein-coupled receptor (GPR)120. Our aim was to investigate in pediatric NAFLD the mechanisms underlying the effects of DHA administration on histo-pathological aspects, GPR120 expression, hepatic progenitor cell activation and macrophage pool.
20 children with untreated NAFLD were included. Children were treated with DHA for 18 months. Liver biopsies before and after the treatment were analyzed. Hepatic progenitor cell activation, macrophage pool and GPR120 expression were evaluated and correlated with clinical and histo-pathological parameters.
GPR120 was expressed by hepatocytes, liver macrophages, and hepatic progenitor cells. After DHA treatment, the following modifications were present: i) the improvement of histo-pathological parameters such as NAFLD activity score, ballooning, and steatosis; ii) the reduction of hepatic progenitor cell activation in correlation with histo-pathological parameters; iii) the reduction of the number of inflammatory macrophages; iv) the increase of GPR120 expression in hepatocytes; v) the reduction of serine-311-phosphorylated nuclear factor kappa B (NF-κB) nuclear translocation in hepatocytes and macrophages in correlation with serum inflammatory cytokines.
DHA could modulate hepatic progenitor cell activation, hepatocyte survival and macrophage polarization through the interaction with GPR120 and NF-κB repression. In this scenario, the modulation of GPR120 exploits a novel crucial role in the regulation of the cell-to-cell cross-talk that drives inflammatory response, hepatic progenitor cell activation and hepatocyte survival.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Hepatic progenitor cells (HPCs) play a major role in liver repair and regeneration. We evaluated HPC involvement in pediatric nonalcoholic fatty liver disease (pNAFLD). Thirty biopsies of consecutive ...children and adolescents with untreated NAFLD (19 with nonalcoholic steatohepatitis NASH and 11 without NASH) were studied using immunohistochemistry and immunofluorescence. HPCs and HPC‐expressing adipokines (e.g., adiponectin, resistin, and glucagon‐like peptide 1 GLP‐1) were counted and correlated with steatosis, inflammation, hepatocyte ballooning, fibrosis, and NAFLD activity score (NAS). The HPC compartment was expanded in pNAFLD, especially in children with NASH, and was independently associated with degree of fibrosis (r = 0.303; P = 0.033). NASH livers were also characterized by increased hepatocyte apoptosis, cell‐cycle arrest, and an expanded pool of intermediate hepatocytes. Adiponectin expression in HPCs of pNAFLD patients was down‐regulated with respect to the healthy liver, and this expression was inversely correlated with NAS score (r = −0.792; P < 0.001) and steatosis (r = −0.769; P < 0.001). Resistin expression in HPCs increased in pNAFLD and was related to degree of fibrosis (r = 0.432; P < 0.05). GLP‐1 was overexpressed in HPCs of pNAFLD patients, and GLP‐1 expression was related to degree of steatosis (r = 0.577; P < 0.05) and NAS (r = 0.594; P < 0.01). Conclusions: HPC activation is involved in the response of the liver to oxidative stress in pNAFLD and is correlated with fibrosis and the progression toward NASH. HPCs express adiponectin, resistin, and GLP‐1, which become available to resident liver cells and are strongly associated with the severity of NAFLD. These results may have important pathophysiological implications in the modulation of hepatic insulin resistance and the progression of liver injury. (HEPATOLOGY 2012;56:2142–2153)
This review focuses on various components of bile acid signaling in relation to cholangiocytes. Their roles as targets for potential therapies for cholangiopathies are also explored. While many ...factors are involved in these complex signaling pathways, this review emphasizes the roles of transmembrane G protein coupled receptor(TGR5), farnesoid X receptor(FXR), ursodeoxycholic acid(UDCA) and the bicarbonate umbrella. Following a general background on cholangiocytes and bile acids,we will expand the review and include sections that are most recently known(within 5–7 years) regarding the field of bile acid signaling and cholangiocyte function. These findings all demonstrate that bile acids influence biliary functions which can, in turn, regulate the cholangiocyte response during pathological events.
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).
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