Activation Of Hepatic Progenitor Cells Research Articles

Autophagy in hepatic progenitor cells modulates exosomal miRNAs to inhibit liver fibrosis in schistosomiasis.

Schistosoma infection is one of the major causes of liver fibrosis. Emerging roles of hepatic progenitor cells (HPCs) in the pathogenesis of liver fibrosis have been identified. Nevertheless, the precise mechanism underlying the role of HPCs in liver fibrosis in schistosomiasis remains unclear. This study examined how autophagy in HPCs affects schistosomiasis-induced liver fibrosis by modulating exosomal miRNAs. The activation of HPCs was verified by immunohistochemistry (IHC) and immunofluorescence (IF) staining in fibrotic liver from patients and mice with Schistosoma japonicum infection. By coculturing HPCs with hepatic stellate cells (HSCs) and assessing the autophagy level in HPCs by proteomic analysis and in vitro phenotypic assays, we found that impaired autophagy degradation in these activated HPCs was mediated by lysosomal dysfunction. Blocking autophagy by the autophagy inhibitor chloroquine (CQ) significantly diminished liver fibrosis and granuloma formation in S. japonicum-infected mice. HPC-secreted extracellular vehicles (EVs) were further isolated and studied by miRNA sequencing. miR-1306-3p, miR-493-3p, and miR-34a-5p were identified, and their distribution into EVs was inhibited due to impaired autophagy in HPCs, which contributed to suppressing HSC activation. In conclusion, we showed that the altered autophagy process upon HPC activation may prevent liver fibrosis by modulating exosomal miRNA release and inhibiting HSC activation in schistosomiasis. Targeting the autophagy degradation process may be a therapeutic strategy for liver fibrosis during Schistosoma infection.

Hepatic progenitor cell-originated ductular reaction facilitates liver fibrosis through activation of hedgehog signaling.

Background: It is poorly understood what cellular types participate in ductular reaction (DR) and whether DR facilitates recovery from injury or accelerates hepatic fibrosis. The aim of this study is to gain insights into the role of hepatic progenitor cell (HPC)-originated DR during fibrotic progression. Methods: DR in liver specimens of PBC, chronic HBV infection (CHB) or NAFLD, and four rodent fibrotic models by different pathogenic processes was evaluated. Gli1 expression was inhibited in rodent models or cell culture and organoid models by AAV-shGli1 or treating with GANT61. Results: Severity of liver fibrosis was positively correlated with DR extent in patients with PBC, CHB or NAFLD. HPCs were activated, expanded, differentiated into reactive cholangiocytes and constituted "HPC-originated DR", accompanying with exacerbated fibrosis in rodent models of HPC activation & proliferation (CCl4/2-AAF-treated), Μdr2-/- spontaneous PSC, BDL-cholestatic fibrosis or WD-fed/CCl4-treated NASH-fibrosis. Gli1 expression was significantly increased in enriched pathways in vivo and in vitro. Enhanced Gli1 expression was identified in KRT19+-reactive cholangiocytes. Suppressing Gli1 expression by administration of AAV-shGli1 or GANT61 ameliorated HPC-originated DR and fibrotic extent. KRT19 expression was reduced after GANT61 treatment in sodium butyrate-stimulated WB-F344 cells or organoids or in cells transduced with Gli1 knockdown lentiviral vectors. In contrast, KRT19 expression was elevated after transducing Gli1 overexpression lentiviral vectors in these cells. Conclusions: During various modes of chronic injury, Gli1 acted as an important mediator of HPC activation, expansion, differentiation into reactive cholangiocytes that formed DR, and subsequently provoked hepatic fibrogenesis.

Liver histology and hepatic progenitor cell activity in pediatric acute liver failure: Implications for clinical outcome.

Hepatic progenitor cell (HPC) activity and regenerative process that follows pediatric acute liver failure (PALF) is still not well understood. This clinicopathological study was thus conducted with an aim to study the correlation of liver histology and HPC activity with outcomes in PALF. All PALF patients with available hepatic histological specimens were included and specimens were analyzed for hepatocyte loss, HPC activity [using cytokeratin (CK) 7, CK19, sex-determining region Y-related high mobility group box(SOX)9 and epithelial cell adhesion molecule (EpCAM)], hepatocyte proliferation (using Ki67), and hepatocyte senescence (using p53 and p21). Ninety-four children were included: 22 (23.4%) survived with native liver (SNL) (i.e., the good outcome group) while rest (i.e., the poor outcome group) either died [33%, 35.1%] or received liver transplant (LT) [39%, 41.5%]. When compared to subjects with poor outcomes, those in the SNL group exhibited significantly less severe hepatocyte loss, fewer HPC/hpf, more proliferating hepatocytes, and less senescent hepatocytes (p < .05). Increasing severity of hepatocyte loss (adjusted OR: 9.95, 95% CI: 4.22-23.45, p < .001) was identified as an independent predictor of poor outcome. Eighty percent children with >50% native hepatocyte loss had poor outcome within 10 days of hospitalization. In PALF, more severe hepatocyte loss, higher number of HPC activation, lesser number of proliferating hepatocytes, and greater number of senescent hepatocytes are associated with a poor outcome. Loss of >50% hepatocytes is an independent predictor of poor outcome in PALF.

SAT-369 - Hepatic progenitor cell activation through the interaction of mesenchymal stem cells and liver sinusoidal endothelial cells

SAT-369 - Hepatic progenitor cell activation through the interaction of mesenchymal stem cells and liver sinusoidal endothelial cells

Targeted blocking of CCR2 and CXCR2 improves the efficacy of transarterial chemoembolization of hepatocarcinoma

BackgroundTransarterial chemoembolization (TACE) has been shown to prolong survival in patients with unresectable hepatocellular carcinoma (HCC); however, the long-term survival remains dismal. Targeting macrophage and neutrophil infiltration is a promising strategy. The CCL2/CCR2 and CXCLs/CXCR2 axes are required for recruitment of macrophages and neutrophils, respectively, in HCC. We investigated the feasibility of CCL2/CCR2 and CXCLs/CXCR2 as therapeutic targets in combination with TACE for treating HCC.MethodsExpression of CCL2/CCR2 and CXCLs/CXCR2 was analyzed in the primary rat HCC model and one HCC cohort. The relationship between expression levels, neutrophil and macrophage infiltration, hepatocarcinogenesis progression in the rat model, and survival of HCC patients was assessed. The anti-tumor effects of blocking the CCL2/CCR2 and CXCLs/CXCR2 axes by CCR2 and CXCR2 antagonists in combination with TACE were evaluated in HCC rats. The numbers of macrophages, neutrophils, and hepatic progenitor cells were further determined to explore the underlying mechanisms.ResultsHigh macrophage and neutrophil infiltration and CXCL8 expression were associated with poor prognosis in the TCGA liver cancer dataset. High expression of CCL2/CCR2 and CXCL8/CXCR2 in clinical HCC specimens was associated with reduced survival. Expression of CCL2/CCR2 and CXCL1/CXCR2 was correlated with hepatocarcinogenesis progression in the primary rat HCC model. Blockade of CCL2/CCR2 and CXCLs/CXCR2 enhanced the anti-tumor effect of TACE treatment in this model. Blocking the CCL2/CCR2 and CXCLs/CXCR2 axes with CCR2 and CXCR2 antagonists in TACE-treated rats reduced macrophage and neutrophil infiltration and hepatic progenitor cell activation and thus overcame TACE resistance in HCC.ConclusionsThe results demonstrate the translational potential of immunotherapy targeting the CCL2/CCR2 and CXCLs/CXCR2 axes in combination with TACE therapy for the treatment of HCC.

Doxorubicin-liposome combined with clodronate-liposome inhibits hepatocellular carcinoma through the depletion of macrophages and tumor cells

Macrophages in the liver have capacities of capturing and phagocytosing nanocarriers. Macrophages also play an important role in the inflammatory microenvironment and in the tumorigenesis, development and progression of hepatocellular carcinoma (HCC). Several studies have shown that depletion of macrophages is a viable strategy for drug delivery and tumor microenvironment regulation. We prepared liposomes containing doxorubicin and clodronate using an ammonium sulfate gradient and thin film hydration method. The repressive therapeutic effects of liposomes were compared by intrasplenic injection at different stages of a primary HCC model induced by diethylnitrosamine (DEN) in rats. Doxorubicin-liposome (DOX-LIP) and clodronate-liposome (CL-LIP) about 180–200 nm were successfully prepared and characterized. We found that DOX-LIP combined with CL-LIP could effectively inhibit the occurrence and development of liver cancer without major organ damage and side effects. The combination of doxorubicin and clodronate liposomes notably decreased hepatic CD68 + macrophages, enriched DOX in plasma and accumulated it for a long time in the liver and spleen, thus improving the tumor microenvironment, inhibiting the activation of hepatic progenitor cells (HPCs) and promoting the apoptosis of tumor cells, and finally producing the inhibitory and therapeutic effects of HCC in rats. Results of this study were expected to provide a new prospect for the chemotherapy of HCC.

P53 positively regulates the proliferation of hepatic progenitor cells promoted by laminin-521

Hepatic progenitor cells (HPCs) hold tremendous potential for liver regeneration, but their well-known limitation of proliferation hampers their broader use. There is evidence that laminin is required for the proliferation of HPCs, but the laminin isoform that plays the dominant role and the key intracellular downstream targets that mediate the regulation of HPC proliferation have yet to be determined. Here we showed that p53 expression increased gradually and reached maximal levels around 8 days when laminin α4, α5, β2, β1, and γ1 subunit levels also reached a maximum during HPC activation and expansion. Laminin-521 (LN-521) promoted greater proliferation of HPCs than do laminin, matrigel or other laminin isoforms. Inactivation of p53 by PFT-α or Ad-p53V143A inhibited the promotion of proliferation by LN-521. Further complementary MRI and bioluminescence imaging analysis showed that p53 inactivation decreased the proliferation of transplanted HPCs in vivo. p53 was activated by LN-521 through the Integrin α6β1/FAK-Src-Paxillin/Akt axis. Activated p53 was involved in the nuclear translocation of CDK4 and inactivation of Rb by inducing p27Kip1. Taken together, this study identifies LN-521 as an ideal candidate substrate for HPC culture and uncovers an unexpected positive role for p53 in regulating proliferation of HPCs, which makes it a potential target for HPC-based regenerative medicine.

Capsaicin suppresses hepatocarcinogenesis by inhibiting the stemness of hepatic progenitor cells via SIRT1/SOX2 signaling pathway.

Capsaicin, a functional component of chili pepper, possesses anti-inflammatory, analgesic, and anti-cancer properties. This study aimed to determine the property of capsaicin against hepatocarcinogenesis in vivo and investigate the role of the SIRT1/SOX2 pathway in the mode of action of capsaicin in hepatic progenitor cells (HPCs), which is related to hepatocarcinogenesis. We prepared a diethylnitrosamine-induced liver cancer model in rats to examine hepatocarcinogenesis, and delivered liposomal capsaicin through the subcutaneous transposition of the spleen to the liver. Liver sections from rats and hepatocarcinoma patients were stained for the markers of HPCs or SIRT1/SOX2 signaling. SIRT1/SOX2 signalling expression was measured using immunoprecipitation and western blot. We found that capsaicin significantly inhibited hepatocarcinogenesis. Notably, capsaicin inhibited HPCs activation in vivo but did not induce apoptosis in the normal hepatic progenitor cell line in rats in vitro. This suggests that capsaicin suppresses hepatocarcinogenesis by inhibiting the stemness of HPCs. Moreover, capsaicin can induce this inhibition by reducing the stability of SOX2. SIRT1 is overexpressed in liver cancer and acts as a tumor promoter via SOX2 deacetylation. Using immunoprecipitation, we identified direct binding between SIRT1 and SOX2. The capsaicin treatment resulted in SIRT1 downregulation which reduced deacetylation, and increased nuclear export as well as subsequent ubiquitous degradation of SOX2. Altogether, we report that capsaicin suppresses hepatocarcinogenesis by inhibiting the stemness of HPCs via SIRT1/SOX2 signaling. It may serve as a promising therapeutic candidate for liver cancer.

Sirt1 Promotes the Restoration of Hepatic Progenitor Cell (HPC)-Mediated Liver Fatty Injury in NAFLD Through Activating the Wnt/β-Catenin Signal Pathway.

Non-alcoholic fatty liver disease (NAFLD) has developed into the world's largest chronic epidemic. In NAFLD, hepatic steatosis causes hepatocytes dysfunction and even apoptosis. The liver has a strong restoration or regeneration ability after an injury, however, it is unclear through which pattern fatty liver injury in NAFLD is repaired and what the repair mechanism is. Here, we found that in the high-fat diet (HFD)-induced NAFLD mice model, fatty liver injury caused the significant ductular reaction (DR), which is a marker to promote the repair of liver injury. SOX9+ and HNF4α+ biphenotype also suggested that hepatic progenitor cells (HPCs) were activated by fatty liver injury in the HFD-elicited NAFLD mice model. Concurrently, fatty liver injury also activated the Wnt/β-catenin signal pathway, which is a necessary process for HPC differentiation into mature hepatocytes. However, Sirt1 knockdown weakened HPC activation and Wnt/β-catenin signal in Sirt1+/− mice with HFD feeding. In rat-derived WB-F344 hepatic stem cell line, Sirt1 overexpression (OE) or Sirt1 activator–Resveratrol promoted HPC differentiation via activating Wnt/β-catenin signal pathway. Glycogen PAS staining demonstrated that Sirt1 OE promoted WB-F344 cells to differentiate into mature hepatocytes with glycogen synthesis ability, while Sirt1 inhibitor EX527 or Wnt/β-catenin pathway inhibitor HF535 decreased glycogen positive cells. Together, our data suggested that Sirt1 plays a vital role in activating HPCs to repair fatty liver injury or promote liver regeneration through the Wnt/β-catenin signal pathway in NAFLD, which might provide a new strategy for fatty liver injury or NAFLD therapy.

Oncostatin M promotes hepatic progenitor cell activation and hepatocarcinogenesis via macrophage-derived tumor necrosis factor-α

Hepatocellular carcinoma (HCC) usually occurs at the late stage of chronic liver injury. Oncostatin M (OSM) is a tumor-associated cytokine highly expressed in cirrhosis and HCC patients; however, its role in hepatocarcinogenesis has not been clearly elucidated. In this study, we investigated the effect of OSM on HCC occurrence in a rat model of N-diethylnitrosamine-induced HCC. OSM overexpression significantly increased the number of tumor nodules and shortened the overall survival of the rats. Notably, OSM promoted HPC activation in vivo but did not directly regulate the proliferation of the HPC cell line in vitro. Further, OSM induced tumor necrosis factor-α (TNF-α) secretion and CD68+ macrophage accumulation, which were positively correlated with HPC activation. Additionally, TNF-α or macrophage depletion inhibited the promoting effect of OSM on hepatocarcinogenesis and HPC activation. Furthermore, OSM expression in the peritumoral tissues of HCC was positively correlated with poor overall survival of patients. In conclusion, OSM plays an important role in hepatocarcinogenesis by regulating the liver inflammation environment. Hence, OSM could be used as a potential target for HCC prevention and therapy or as an indicator of HCC prognosis.

Mutational Signature Analysis Reveals Widespread Contribution of Pyrrolizidine Alkaloid Exposure to Human Liver Cancer.

Mutational signature analyses are an effective tool in identifying cancer etiology. Humans are frequently exposed to pyrrolizidine alkaloids (PAs), the most common carcinogenic phytotoxins widely distributed in herbal remedies and foods. However, due to the lack of human epidemiological data, PAs are classified as group II hepatocarcinogens by the World Health Organization. This study identified a PA mutational signature as the biomarker to investigate the association of PA exposure with human liver cancer. Pyrrole-protein adducts (PPAs), the PA exposure biomarker, were measured and found in 32% of surgically resected specimens from 34 patients with liver cancer in Hong Kong. Next, we delineated the mode of mutagenic and tumorigenic actions of retrorsine, a representative PA, in mice and human hepatocytes (HepaRG). Retrorsine induced DNA adduction, DNA damage, and activation of tumorigenic hepatic progenitor cells, which initiated hepatocarcinogenesis. PA mutational signature, as the unique molecular fingerprint of PA-induced mutation, was derived from exome mutations in retrorsine-exposed mice and HepaRG cells. Notably, PA mutational signature was validated in genomes of patients with PPA-positive liver cancer but not patients with PPA-negative liver cancer, confirming the specificity of this biomarker in revealing PA-associated liver cancers. Furthermore, we examined the established PA mutational signature in 1,513 liver cancer genomes and found that PA-associated liver cancers were potentially prevalent in Asia (Mainland China [48%], Hong Kong [44%], Japan [22%], South Korea [6%], Southeast Asia [25%]) but minor in Western countries (North America [3%] and Europe [5%]). This study provides a clinical indication of PA-associated liver cancer. We discovered an unexpectedly extensive implication of PA exposure in patients with liver cancer, laying the scientific basis for precautionary approaches and prevention of PA-associated human liver cancers.

Inhibition of nuclear factor (erythroid-derived 2)-like 2 promotes hepatic progenitor cell activation and differentiation

The stem cell ability to self-renew and lead regeneration relies on the balance of complex signals in their microenvironment. The identification of modulators of hepatic progenitor cell (HPC) activation is determinant for liver regeneration and may improve cell transplantation for end-stage liver disease. This investigation used different models to point out the Nuclear factor (erythroid-derived 2)-like 2 (NRF2) as a key regulator of the HPC fate. We initially proved that in vivo models of biliary epithelial cells (BECs)/HPC activation show hepatic oxidative stress, which activates primary BECs/HPCs in vitro. NRF2 downregulation and silencing were associated with morphological, phenotypic, and functional modifications distinctive of differentiated cells. Furthermore, NRF2 activation in the biliary tract repressed the ductular reaction in injured liver. To definitely assess the importance of NRF2 in HPC biology, we applied a xenograft model by inhibiting NRF2 in the human derived HepaRG cell line and transplanting into SCID/beige mice administered with anti-Fas antibody to induce hepatocellular apoptosis; this resulted in effective human hepatocyte repopulation with reduced liver injury. To conclude, NRF2 inhibition leads to the activation and differentiation of liver progenitors. This redox-dependent transcription factor represents a potential target to regulate the commitment of undifferentiated hepatic progenitors into specific lineages.

Secretin Treatment Promotes Hepatic Progenitor Cell Activation, Ductal‐Canalicular Junction Formation and Amelioration of Liver Damage in a Model of Late‐Stage Primary Biliary Cholangitis

Introduction PBC is a cholestatic disease characterized by bile duct loss, ductular reaction and liver fibrosis. The canals of Hering (CoH) are the site of ductulo-canalicular junction (DCJ) that maintain proper bile drainage from the liver, and contain the hepatic progenitor cell (HPC) population. CoH loss is noted in PBC and correlates with scoring. Secretin binds to its receptor (SR, expressed by large cholangiocytes) to promote biliary proliferation during cholestasis; however, during large duct damage, small cholangiocytes acquire large cholangiocyte phenotypes including SR expression. Secretin/SR expression is downregulated in late-stage PBC; therefore, we aimed to understand the role of the secretin/SR axis during PBC. We hypothesized that secretin treatment restores DCJ through HPC activation and ameliorates liver phenotypes associated with late-stage PBC. Methods Female 34 wk old wild-type (WT) and dominant-negative transforming growth factor-β receptor II (dnTGFβRII, model of late-stage PBC) mice were treated with control or secretin (2.5 nmol/kg BW) for 8 wk by IP implanted minipumps. Cholangitis activity, hepatitis activity and bile duct loss were determined by the Nakanuma scoring system. Ductular reaction was measured by semi-quantitative CK-19 immunostaining. Liver fibrosis was evaluated by Sirius Red staining, collagen-1a immunostaining and qPCR for α-SMA. Hepatic stellate cell (HSC) presence was determined by desmin immunostaining. Cholestasis was indicated by hepatic total bile acid (TBA) levels using EIA. DCJ presence was evaluated by co-immunostaining for ABC transporter bile salt export pump (BSEP)/CK-19 and semi-quantification. HPC activation was assessed by Sox9 staining and semi-quantification. Results dnTGFβRII mice had an increase in cholangitis and hepatitis activity; however, 8 wks of secretin treatment significantly reduces cholangitis, but not hepatitis, activity. dnTGFβRII mice present with ductular reaction and significant bile duct loss, which was reversed with 8 wks secretin treatment. Hepatic TBA levels, liver fibrosis and HSC presence are increased in dnTGFβRII mice, but significantly reduced following 8 wks of secretin treatment. In line with human studies, dnTGFβRII mice have significant loss of DCJ and reduced HPC number; however, 8 wks of secretin treatment restores these parameters. Conclusion Long-term secretin treatment (i) reduces ductular reaction, (ii) reverses bile duct loss, (iii) decreases liver fibrosis, (iv) promotes HPC activity and (v) restores DCJ presence in a model of late-stage PBC. Secretin maintenance of the DCJ may be due to (i) the restoration of bile flow and release of toxic bile acids or (ii) secretin binding to SR acquired on small cholangiocytes/HPCs. Treatment with secretin may be a therapeutic option for late-stage PBC patients.

Clinical implications of hepatic progenitor cell activation in non-alcoholic fatty liver disease

Hepatoma Research is an open access journal and focuses on all topics related to hepatoma. The following articles are especially welcome: pathogenesis, clinical examination and early diagnosis of hepatoma, complications of hepatoma, and their preventions and treatments, etc.

Redox Control of the Immune Response in the Hepatic Progenitor Cell Niche.

The liver commonly self-regenerates by a proliferation of mature cell types. Nevertheless, in case of severe or protracted damage, the organ renewal is mediated by the hepatic progenitor cells (HPCs), adult progenitors capable of differentiating toward the biliary and the hepatocyte lineages. This regeneration process is determined by the formation of a stereotypical niche surrounding the emerging progenitors. The organization of the HPC niche microenvironment is crucial to drive biliary or hepatocyte regeneration. Furthermore, this is the site of a complex immunological activity mediated by several immune and non-immune cells. Indeed, several cytokines produced by monocytes, macrophages and T-lymphocytes may promote the activation of HPCs in the niche. On the other side, HPCs may produce pro-inflammatory cytokines induced by liver inflammation. The inflamed liver is characterized by high generation of reactive oxygen and nitrogen species, which in turn lead to the oxidation of macromolecules and the alteration of signaling pathways. Reactive species and redox signaling are involved in both the immunological and the adult stem cell regeneration processes. It is then conceivable that redox balance may finely regulate the immune response in the HPC niche, modulating the regeneration process and the immune activity of HPCs. In this perspective article, we summarize the current knowledge on the role of reactive species in the regulation of hepatic immunity, suggesting future research directions for the study of redox signaling on the immunomodulatory properties of HPCs.

Loss of SRSF2 triggers hepatic progenitor cell activation and tumor development in mice

Splicing factor SRSF2 is frequently mutated or up-regulated in human cancers. Here, we observe that hepatocyte-specific deletion of Srsf2 trigger development of hepatocellular carcinoma (HCC) in mice, which also involves inflammation and fibrosis. Importantly, we find that, when compensatory hepatocyte proliferation is impaired, activation of hepatic progenitor cells (HPCs) play an important role in liver regeneration and tumor formation. Moreover, the cells of HCC- bearing livers display both HPC and hepatocyte markers, with gene expression profiling suggesting HPC origin and embryonic origin. Mechanically, we demonstrate that levels of oncofetal genes insulin-like growth factor 2 (Igf2) and H19 are significantly increased in the tumors, likely due to decreased DNA methylation of the Igf2/H19 locus. Consequently, signaling via the Igf2 pathway is highly activated in the tumors. Thus, our data demonstrate that loss of Srsf2 triggers HPC-mediated regeneration and activation of oncofetal genes, which altogether promote HCC development and progression in mice.

Nodular Regenerative Hyperplasia: Expression Pattern of Glutamine Synthetase and a Potential Role for Hepatic Progenitor Cells.

Nodular regenerative hyperplasia (NRH) is one of the most frequent causes of noncirrhotic intrahepatic hypertension, but is a difficult histologic diagnosis. The expression of glutamine synthetase (GS) and cytokeratin 7 (CK7) has been reported to be increased in other regenerative/vascular conditions, while CK7 and BerEP4 are also markers of hepatic progenitor cells. The aims of this study were to investigate the use of GS, CK7, and BerEP4 as the potential markers for NRH. This is a retrospective case series of NRH at Centre Hospitalier de l'Universite de Montreal between 1993 and 2013. Normal liver from partial hepatectomies for tumors were used as controls. GS, CK7, CK19, and BerEP4 immunohistochemical stains were performed on all specimens. Immunohistochemical staining patterns were scored from 0 to 3+. NRH was identified in 46 samples obtained from 26 patients. Liver chemistry profile was cholestatic in 45% of the patients. In 93% of the NRH cases, there was abnormal zone 2 expression of GS. Weak panacinar GS staining was seen in all the NRH cases. Aberrant CK7 expression was present in all cases of NRH, but were not associated with cholestasis. BerEP4 was overexpressed in 47% of the NRH cases (P<0.05); all cases with diffuse BerEP4 staining also showed extensive CK7 expression (P<0.01). NRH showed increased immunohistochemical GS staining that may support its morphologic diagnosis. Our findings suggest that there is an activation of hepatic progenitor cells in NRH.

Hepatic progenitor cell activation is induced by the depletion of the gut microbiome in mice.

The homeostasis of the gut microbiome is crucial for human health and for liver function. However, it has not been established whether the gut microbiome influence hepatic progenitor cells (HPCs). HPCs are capable of self‐renewal and differentiate into hepatocytes and cholangiocytes; however, HPCs are normally quiescent and are rare in adults. After sustained liver damage, a ductular reaction occurs, and the number of HPCs is substantially increased. Here, we administered five broad‐spectrum antibiotics for 14 days to deplete the gut microbiomes of male C57BL/6 mice, and we measured the plasma aminotransferases and other biochemical indices. The expression levels of two HPC markers, SRY‐related high mobility group‐box gene 9 (Sox9) and cytokeratin (CK), were also measured. The plasma aminotransferase activities were not affected, but the triglyceride, lactate dehydrogenase, low‐density lipoprotein, and high‐density lipoprotein concentrations were significantly altered; this suggests that liver function is affected by the composition of the gut microbiome. The mRNA expression of Sox9 was significantly higher in the treated mice than it was in the control mice (p < 0.0001), and a substantial expression of Sox9 and CK was observed around the bile ducts. The mRNA expression levels of proinflammatory factors (interleukin [IL]‐1β, IL‐6, tumor necrosis factor [TNF]‐α, and TNF‐like weak inducer of apoptosis [Tweak]) were also significantly higher in the antibiotic‐treated mice than the levels in the control mice. These data imply that the depletion of the gut microbiome leads to liver damage, negatively impacts the hepatic metabolism and function, and activates HPCs. However, the underlying mechanisms remain to be determined.

Lipopolysaccharide induces the differentiation of hepatic progenitor cells into myofibroblasts constitutes the hepatocarcinogenesis-associated microenvironment.

Hepatocellular carcinoma (HCC) generally occurs in the presence of chronic liver injury, often as a sequela of liver fibrosis. Hepatic progenitor cells (HPCs) are known to be capable of forming both hepatocytes and cholangiocytes in chronic liver injury, which are also considered a source of myofibroblasts and tumor-initiating cells, under carcinogenic circumstances. However, the underlying mechanisms that activate HPCs to give rise to HCC are still unclear. In current study, the correlation between HPCs activation and liver fibrosis and carcinogenesis was investigated in rats and human specimens. We analyzed the role of HPCs in tumorigenesis, by transplanting exogenous HPCs in a diethylnitrosamine-induced rat HCC model. Our data indicated that HPC activation correlated with hepatic fibrosis and hepatocarcinogenesis. We further found that exogenous HPC infusion promoted liver fibrosis and hepatocarcinogenesis, while lipopolysaccharides (LPS) played an important role in this process. However, results of our study indicated that LPS did not induce HPCs to form tumor in nude mice directly. Rather, LPS induced myofibroblast-like morphology in HPCs, which enhanced the tumorigenic potential of HPCs. Further experiments showed that LPS/Toll-like receptor 4 (TLR4) signaling mediated the differentiation of HPCs into myofibroblasts and enhanced the production of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), which led to the aberrant expression of Ras and p53 signaling pathways in HPCs, and finally, promoted the proliferation and malignant transformation of HPCs, by long non-coding RNA regulation. Besides, examination of HCC clinical samples demonstrated that IL-6 and TNF-α production correlated with HPC activation, hepatic fibrosis, and HCC recurrence. Our study indicates that both myofibroblasts and tumor cells are derived from HPCs. HPC-derived myofibroblasts create tumor microenvironment and contribute to the proliferation and malignant transformation of HPCs. Furthermore, LPS present in the chronic liver inflammation microenvironment might play an important role in hepatocarcinogenesis, by regulating the plastic potential of HPCs.

High-throughput sequencing identifies aetiology-dependent differences in ductular reaction in human chronic liver disease.

Ductular reaction (DR) represents the activation of hepatic progenitor cells (HPCs) and has been associated with features of advanced chronic liver disease; yet it is not clear whether these cells contribute to disease progression and how the composition of their micro-environment differs depending on the aetiology. This study aimed to identify HPC-associated signalling pathways relevant in different chronic liver diseases using a high-throughput sequencing approach. DR/HPCs were isolated using laser microdissection from patient samples diagnosed with HCV or primary sclerosing cholangitis (PSC), as models for hepatocellular or biliary regeneration. Key signals were validated at the protein level for a cohort of 56 patients (20 early and 36 advanced stage). In total, 330 genes were significantly differentially expressed between the HPCs in HCV and PSC. Recruitment and homing of inflammatory cells were distinctly different depending on the aetiology. HPCs in PSC were characterised by a response to oxidative stress (e.g. JUN, VNN1) and neutrophil-attractant chemokines (CXCL5, CXCL6, IL-8), whereas HPCs in HCV were identified by T- and B-lymphocyte infiltration. Moreover, we found that communication between HPCs and macrophages was aetiology driven. In PSC, a high frequency of CCL28-positive macrophages was observed in the portal infiltrate, already in early disease in the absence of advanced fibrosis, while in HCV, HPCs showed a strong expression of the macrophage scavenger receptor MARCO. Interestingly, DR/HPCs in PSC showed more deposition of ECM (e.g. FN1, LAMC2, collagens) compared to HCV, where an increase of pro-invasive genes (e.g. PDGFRA, IGF2) was observed. Additionally, endothelial cells in the vicinity of DR/HPCs showed differential immunopositivity (e.g. IGF2 and INHBA expression). In conclusion, our data shine light on the role of DR/HPCs in immune signalling, fibrogenesis and angiogenesis in chronic liver disease. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.