Enhanced Wnt Signalling in Hepatocytes is Associated with Schistosoma japonicum Infection and Contributes to Liver Fibrosis. Sci Rep. 2017;7:230. [PMID: 28331224 PMCID: PMC5428310 DOI: 10.1038/s41598-017-00377-4]

Pathology and molecular mechanisms of Schistosoma japonicum-associated liver fibrosis

Schistosomiasis has been widely disseminated around the world, and poses a significant threat to human health. Schistosoma eggs and soluble egg antigen (SEA) mediated inflammatory responses promote the formation of egg granulomas and liver fibrosis. With continuous liver injuries and inflammatory stimulation, liver fibrosis can develop into liver cirrhosis and liver cancer. Therefore, anti-fibrotic therapy is crucial to increase the survival rate of patients. However, current research on antifibrotic treatments for schistosomiasis requires further exploration. In the complicated microenvironment of schistosome infections, it is important to understand the mechanism and pathology of schistosomiasis-associated liver fibrosis(SSLF). In this review, we discuss the role of SEA in inhibiting liver fibrosis, describe its mechanism, and comprehensively explore the role of host-derived and schistosome-derived microRNAs (miRNAs) in SSLF. Inflammasomes and cytokines are significant factors in promoting SSLF, and we discuss the mechanisms of some critical inflammatory signals and pro-fibrotic cytokines. Natural killer(NK) cells and Natural killer T(NKT) cells can inhibit SSLF but are rarely described, therefore, we highlight their significance. This summarizes and provides insights into the mechanisms of key molecules involved in SSLF development.

FXR deficiency in hepatocytes disrupts the bile acid homeostasis and inhibits autophagy to promote liver injury in Schistosoma japonicum-infected mice

Background

Schistosomiasis, with 250 million people affected, is characterized by its serious hepatic inflammatory response and fibrosis formation, which could lead to dangerous complications, such as portal hypertension, splenomegaly and even ascites. But until now, the pathogenesis of schistosomiasis remains largely unknown. Farnesoid X Receptor (FXR), a bile acid-activated nuclear transcription factor mainly expresses in hepatocytes in the liver, can regulate liver diseases by controlling bile acid metabolism.

Methodology/Principal findings

In this study, we found that the expression of FXR was decreased in the liver of infected mice as shown by western blot and RT-qPCR assays. Furthermore, hepatocyte-specific FXR-deficient mice (FXR^flox/floxAlb^Cre, FXR-HKO) were generated and infected with ~16 cercariae of S. japonicum for five weeks. We found that FXR deficiency in hepatocytes promoted the progression of liver injury, aggravated weight loss and death caused by infection, and promoted inflammatory cytokines production, such as IL-6, IL-1β, TNF-α, IL-4, IL-10, and IL-13. Surprisingly, hepatic granulomas and fibrosis were not affected. In addition, using UPLC-MS/MS spectrometry, it was found that S. japonicum infection resulted in elevated bile acids in the liver of mice, which was more obvious in FXR-deficient mice. Meanwhile, autophagy was induced in littermate control mice due to the infection, but it was significantly decreased in FXR-HKO mice.

Conclusions/Significance

All these findings suggest that FXR deficiency in hepatocytes disrupts bile acid homeostasis and inhibits autophagy, which may aggravate the damages of hepatocytes caused by S. japonicum infection. It highlights that FXR in hepatocytes plays a regulatory role in the progression of schistosomiasis.

The liver, a critical metabolic organ, consists of approximately 80% parenchymal hepatocytes. Hepatic schistosomiasis results in inflammatory granulomas response and fibrosis formation that inevitably affects hepatocytes. However, whether and how hepatocytes involved in the progression of liver injury caused by S. japonicum is not clear. Here, we found that, the level of FXR, a key regulator of bile acid metabolism in hepatocytes, was clearly decreased in the liver of mice with this worm infection. Further, we found that FXR specifically deficient in hepatocytes increased bile acids toxicity and inhibited hepatocellular autophagy induced by worm infection, which therefore accelerated the progression of schistosomiasis by promoting hepatocyte injuries but not the formation of egg granulomas and hepatic fibrosis. Our work provides a regulatory loop of FXR/bile acids-autophagy in schistosomiasis, which suggests a role of hepatic FXR in the protection from hepatic damages caused by infection with S. japonicum.

Pathogenesis of Liver Fibrosis and Its TCM Therapeutic Perspectives

Liver fibrosis is a pathological process of abnormal tissue proliferation in the liver caused by various pathogenic factors, which will further develop into cirrhosis or even hepatocellular carcinoma if liver injury is not intervened in time. As a diffuse progressive liver disease, its clinical manifestations are mostly excessive deposition of collagen-rich extracellular matrix resulting in scar formation due to liver injury. Hepatic fibrosis can be caused by hepatitis B and C, fatty liver, alcohol, and rare diseases such as hemochromatosis. As the metabolic center of the body, the liver regulates various vital activities. During the development of fibrosis, it is influenced by many other factors in addition to the central event of hepatic stellate cell activation. Currently, with the increasing understanding of TCM, the advantages of TCM with multiple components, pathways, and targets have been demonstrated. In this review, we will describe the factors influencing liver fibrosis, focusing on the effects of cells, intestinal flora, iron death, signaling pathways, autophagy and angiogenesis on liver fibrosis, and the therapeutic effects of herbal medicine on liver fibrosis.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

C5a Activates a Pro-Inflammatory Gene Expression Profile in Human Gaucher iPSC-Derived Macrophages

Gaucher disease (GD) is an autosomal recessive disorder caused by bi-allelic GBA1 mutations that reduce the activity of the lysosomal enzyme β-glucocerebrosidase (GCase). GCase catalyzes the conversion of glucosylceramide (GluCer), a ubiquitous glycosphingolipid, to glucose and ceramide. GCase deficiency causes the accumulation of GluCer and its metabolite glucosylsphingosine (GluSph) in a number of tissues and organs. In the immune system, GCase deficiency deregulates signal transduction events, resulting in an inflammatory environment. It is known that the complement system promotes inflammation, and complement inhibitors are currently being considered as a novel therapy for GD; however, the mechanism by which complement drives systemic macrophage-mediated inflammation remains incompletely understood. To help understand the mechanisms involved, we used human GD-induced pluripotent stem cell (iPSC)-derived macrophages. We found that GD macrophages exhibit exacerbated production of inflammatory cytokines via an innate immune response mediated by receptor 1 for complement component C5a (C5aR1). Quantitative RT-PCR and ELISA assays showed that in the presence of recombinant C5a (rC5a), GD macrophages secreted 8-10-fold higher levels of TNF-α compared to rC5a-stimulated control macrophages. PMX53, a C5aR1 blocker, reversed the enhanced GD macrophage TNF-α production, indicating that the observed effect was predominantly C5aR1-mediated. To further analyze the extent of changes induced by rC5a stimulation, we performed gene array analysis of the rC5a-treated macrophage transcriptomes. We found that rC5a-stimulated GD macrophages exhibit increased expression of genes involved in TNF-α inflammatory responses compared to rC5a-stimulated controls. Our results suggest that rC5a-induced inflammation in GD macrophages activates a unique immune response, supporting the potential use of inhibitors of the C5a-C5aR1 receptor axis to mitigate the chronic inflammatory abnormalities associated with GD.

The role of let-7b in the inhibition of hepatic stellate cell activation by rSjP40

BACKGROUND

Hepatic stellate cells (HSCs) are one of the main cell types involved in liver fibrosis induced by many factors, including schistosomes. Previous studies in our lab have shown that recombinant P40 protein from Schistosoma japonicum (rSjP40) can inhibit HSC activation in vitro. Let-7b is a member of the let-7 microRNA family and plays an inhibitory role in a variety of diseases and inflammatory conditions. In this study, we investigated the role of let-7b in the inhibition of HSC activation by rSjP40.

METHODS

Expression of let-7b was detected by quantitative real-time PCR. A dual luciferase assay was used to confirm direct interaction between let-7b and collagen I. We also used western blot to assess protein levels of TGFβRI and collagen type I α1 (COL1A1).

RESULTS

We found that rSjP40 up-regulates expression of let-7b in HSCs. Let-7b inhibits collagen I expression by directly targeting the 3'UTR region of the collagen I gene. Furthermore, we discovered that let-7b inhibitor partially restores the loss of collagen I expression caused by rSjP40.

CONCLUSION

Our research clarifies the role of let-7b in the inhibition of HSC activation by rSjP40 and will provide new insights and ideas for the inhibition of HSC activation and treatment of liver fibrosis.

Inflammasomes and Fibrosis

Fibrosis is the final common pathway of inflammatory diseases in various organs. The inflammasomes play an important role in the progression of fibrosis as innate immune receptors. There are four main members of the inflammasomes, such as NOD-like receptor protein 1 (NLRP1), NOD-like receptor protein 3 (NLRP3), NOD-like receptor C4 (NLRC4), and absent in melanoma 2 (AIM2), among which NLRP3 inflammasome is the most studied. NLRP3 inflammasome is typically composed of NLRP3, ASC and pro-caspase-1. The activation of inflammasome involves both "classical" and "non-classical" pathways and the former pathway is better understood. The "classical" activation pathway of inflammasome is that the backbone protein is activated by endogenous/exogenous stimulation, leading to inflammasome assembly. After the formation of "classic" inflammasome, pro-caspase-1 could self-activate. Caspase-1 cleaves cytokine precursors into mature cytokines, which are secreted extracellularly. At present, the "non-classical" activation pathway of inflammasome has not formed a unified model for activation process. This article reviews the role of NLRP1, NLRP3, NLRC4, AIM2 inflammasome, Caspase-1, IL-1β, IL-18 and IL-33 in the fibrogenesis.

Wnt3a upregulation is involved in TGFβ1-induced cardiac hypertrophy

Pathological cardiac hypertrophy, characterized by enlarged cell size and fetal gene reactivation, ultimately leads to cardiac dysfunction and heart failure. The expression of transforming growth factor beta 1 (TGFβ1) is often elevated in experimental models of cardiac hypertrophy. In the present study, we observed the activation of Wnt/β-catenin signaling in TGFβ1-induced cardiac hypertrophy. TGFβ1 stimulation decreased the phosphorylation levels of β-catenin and triggered the nuclear accumulation of β-catenin. In turn, TGFβ1 enhanced the expression of c-Myc, which is a transcriptional target of canonical Wnt/β-catenin pathway. Knockdown of β-catenin completely blocked TGFβ1-induced c-Myc upregulation. Wnt3a is an important Wnt ligand associated with cardiac fibrosis and hypertrophy. Further investigation revealed that TGFβ1 can upregulate Wnt3a expression in an ALK5-Smad2/3-dependent manner. A consensus Smad binding sequence is located within the Wnt3a promoter, and TGFβ1 stimulation enhanced recruitment of Smad2/3 onto the Wnt3a promoter. Meanwhile, Wnt3a overexpression also stimulated TGFβ1 expression. Chemical inhibition of Wnt/β-catenin signaling partially attenuated TGFβ1-induced hypertrophic responses. These findings suggest crosstalk between TGFβ1 and canonical Wnt/β-catenin pathways in cardiac hypertrophy.

MicroRNA-221: A Fine Tuner and Potential Biomarker of Chronic Liver Injury

The last decade has witnessed significant advancements in our understanding of how small noncoding RNAs, such as microRNAs (miRNAs), regulate disease progression. One such miRNA, miR-221, has been shown to play a key role in the progression of liver fibrosis, a common feature of most liver diseases. Many reports have demonstrated the upregulation of miR-221 in liver fibrosis caused by multiple etiologies such as viral infections and nonalcoholic steatohepatitis. Inhibition of miR-221 via different strategies has shown promising results in terms of the suppression of fibrogenic gene signatures in vitro, as well as in vivo, in independent mouse models of liver fibrosis. In addition, miR-221 has also been suggested as a noninvasive serum biomarker for liver fibrosis and cirrhosis. In this review, we discuss the biology of miR-221, its significance and use as a biomarker during progression of liver fibrosis, and finally, potential and robust approaches that can be utilized to suppress liver fibrosis via inhibition of miR-221.

Study of Dickkopf-1 (DKK-1) in patients with chronic viral hepatitis C-related liver cirrhosis with and without hepatocellular carcinoma

Aim of the study

Dickkopf-1 (DKK-1) is a secreted protein which acts as an inhibitor of Wnt/β-catenin signaling. DKK-1 was found to be a helpful biomarker for many cancers including hepatocellular carcinoma (HCC). HCC is multifactorial in origin and its main etiology in Egypt is attributed to chronic hepatitis C virus (HCV) infection. Objectives: To assess the serum level and diagnostic performance of DKK-1 and α-fetoprotein (AFP) in Egyptian patients with chronic HCV-related liver cirrhosis with and without HCC.

Material and methods

80 subjects were divided into: a control group (group I, 20 healthy volunteers) and two patient groups: group II (HCV with liver cirrhosis, 30 patients), and group III, (HCV-related liver cirrhosis with HCC, 30 patients). Thorough physical examination, triphasic computed tomography, calculation of Child-Pugh score, laboratory investigations (complete blood picture, liver profile, hepatitis B surface antigen, anti-HCV antibodies, AFP (chemiluminometry) and DKK-1 (ELISA) were performed.

Results

There was a significant decrease in DKK-1 level in HCV patients with liver cirrhosis (group II) and HCV patients with HCC (group III) compared to the control group (group I) (p < 0.001). However, there was a significant increase in DKK-1 level in HCV patients with HCC (group III) compared to HCV patients with liver cirrhosis (group II) (p < 0.033). The ROC curve showed that DKK-1 has less sensitivity but higher specificity in HCV patients with HCC (group III) compared with HCV patients with liver cirrhosis (group II).

Conclusions

The combination of DKK-1 and AFP could further improve the diagnostic accuracy of HCV-related cirrhosis with or without HCC.

Myricetin Possesses Anthelmintic Activity and Attenuates Hepatic Fibrosis via Modulating TGFβ1 and Akt Signaling and Shifting Th1/Th2 Balance in Schistosoma japonicum-Infected Mice

Schistosomiasis is a zoonotic and debilitating parasitic disease caused by Schistosoma japonicum. Praziquantel remains the choice for treating schistosomiasis, but its efficacy could be hampered by emergence of resistance. In this study, using large-scale drug screening, we selected out myricetin, a natural flavonol compound, having a good anti-schistosome effect. We found that myricetin exhibited dose and time-dependent insecticidal effect on S. japonicum in vitro, with an LC₅₀ of 600 μM for 24 h, and inhibited female spawning. The drug mainly destroyed the body structure of the worms and induced apoptosis of the worm cells, which in turn led to death. In addition, oral administration of myricetin in mice infected with S. japonicum showed a deworming effect in vivo, as evidenced by a significant reduction in the liver egg load. H&E staining, quantitative RT-PCR, and Western blotting assays showed that myricetin significantly alleviated liver fibrosis in mice infected with S. japonicum. Myricetin also effectively inhibited the expression of TGFβ1, Smad2, phospho-Smad2, Smad3, phospho-Smad3, ERK, phospho-ERK, Akt, and phospho-Akt in the liver of infected mice, suggesting that myricetin attenuated liver fibrosis in mice via modulating TGFβ1 and Akt signaling. Flow cytometric analysis of Th subtypes (Th1/Th2/Th17/Treg) in the mouse spleen further revealed that myricetin significantly increased the percentage Th1 cells in infected mice and reduced the proportion of Th2 cells and Th17 cells. Immunology multiplex assay further showed that myricetin attenuated S. japonicum-induced rise in the plasma levels of IL-4, IL-5, IL-10, IL-13, and IL-17A in infected mice while increasing the plasma contents of IFN-γ, IL-12, and IL-7. In conclusion, our study provides the first direct evidence that myricin possesses potent anti-schistosome activities in vitro and in vivo, and offers new insights into the mechanisms of action by myricetin. The present findings suggest that myricetin could be further explored as a therapeutic agent for S. japonicum.

Hepatitis C virus core protein modulates several signaling pathways involved in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer, and hepatitis C virus (HCV) infection plays a major role in HCC development. The molecular mechanisms by which HCV infection leads to HCC are varied. HCV core protein is an important risk factor in HCV-associated liver pathogenesis and can modulate several signaling pathways involved in cell cycle regulation, cell growth promotion, cell proliferation, apoptosis, oxidative stress and lipid metabolism. The dysregulation of signaling pathways such as transforming growth factor β (TGF-β), vascular endothelial growth factor (VEGF), Wnt/β-catenin (WNT), cyclooxygenase-2 (COX-2) and peroxisome proliferator-activated receptor α (PPARα) by HCV core protein is implicated in the development of HCC. Therefore, it has been suggested that this protein be considered a favorable target for further studies in the development of HCC. In addition, considering the axial role of these signaling pathways in HCC, they are considered druggable targets for cancer therapy. Therefore, using strategies to limit the dysregulation effects of core protein on these signaling pathways seems necessary to prevent HCV-related HCC.

Ziziphus spina-christi leaf extract ameliorates schistosomiasis liver granuloma, fibrosis, and oxidative stress through downregulation of fibrinogenic signaling in mice

Schistosomiasis is a widespread parasitic infection that affects humans, as well as wild and domestic animals. It ranks second after malaria, with a significant health and socio-economic impact in the developing countries. The objective of this study was to assess the anti-schistosomal impact of Ziziphus spina-christi leaf extract (ZLE) on Schistosoma mansoni-induced liver fibrosis in CD-1 Swiss male albino mice. S. mansoni infection was achieved by dipping of mouse tails in schistosomal cercariae. ZLE treatment was initiated at 46 days post-infection by administering a dose of the extract on a daily basis for 10 consecutive days. S. mansoni infection resulted in liver granuloma and fibrosis, with a drastic elevation in liver function factors, nitric oxide, and lipid peroxidation, which were associated with a reduction in glutathione content and substantial inhibition of antioxidant enzyme activities compared to those of the control. Induction of hepatic granuloma, oxidative stress, and fibrosis in the liver was controlled by ZLE administration, which also produced inhibition of matrix metalloproteinase-9, alpha-smooth muscle actin, transforming growth factor-β, and tissue inhibitors of metalloproteinases expressions. In addition, the S. mansoni-infected group exhibited an increase in Bax and caspase-3 levels and a decrease in Bcl-2 level. However, treatment with ZLE mainly mitigated apoptosis in the liver. Thus, the findings of this study revealed that Ziziphus spina-christi had anti-apoptotic, anti-fibrotic, antioxidant, and protective effects on S. mansoni-induced liver wounds. The benefits of Ziziphus spina-christi extract on S. mansoni were partly partially mediated by enhancing anti-fibrinogenic and nuclear factor erythroid 2–related factor 2 (Nrf2) pathways.

Emerging role and therapeutic implication of Wnt signaling pathways in liver fibrosis

Activation of hepatic stellate cells (HSCs) is a pivotal cellular event in liver fibrosis. Therefore, improving our understanding of the molecular pathways that are involved in these processes is essential to generate new therapies for liver fibrosis. Greater knowledge of the role of the Wnt signaling pathway in liver fibrosis could improve understanding of the liver fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the Wnt signaling pathway, which significantly participates in liver fibrosis and HSC activation, and look ahead on new perspectives of Wnt signaling pathway research. Moreover, we will discuss the different interactions with Wnt signaling pathway-regulated liver fibrosis. The Wnt signaling pathway modulates several important aspects of function, including cell proliferation, activation and differentiation. Targeting the Wnt signaling pathway can be a promising direction in liver fibrosis treatment. We discuss new perspectives of Wnt signaling pathway activation in liver fibrosis. For example, antagonist to Wnt and Wnt ligands could inhibit liver fibrosis by regulating Wnt/β-catenin signaling pathway. These findings identify the Wnt signaling pathway as a potentially important for therapeutic targets in liver fibrosis. Future studies are needed in order to find safer and more effective Wnt-based drugs.

The WNT signaling pathways in wound healing and fibrosis

The WNT signaling pathways are major regulators of organ development. Ample research over the past few decades revealed that these pathways are critically involved in adult tissue homeostasis and stem cell function as well as the development of chronic diseases, such as cancer and fibrosis. In this review, we will describe the different WNT signal pathways, summarize the current evidence of WNT signal involvement in wound healing and fibrosis, and highlight potential novel therapeutic options for fibrotic disorders targeting WNT signaling pathways.

CTGF secreted by mesenchymal-like hepatocellular carcinoma cells plays a role in the polarization of macrophages in hepatocellular carcinoma progression

M2 macrophages play critical roles in the progression of hepatocellular carcinoma (HCC), and they are associated with poor outcomes. TGF-β-induced epithelial-mesenchymal transition (EMT) has been shown to be critically important to cancer cell dissemination in HCC. However, the relationship between stromal-like HCC cells and M2 macrophages formation is not clear. Here, we interrogated the molecular link between mesenchymal-like HCC cells and the formation of M2 macrophages. We demonstrated that mesenchymal-like HCC cells secrete connective tissue growth factor (CTGF) to polarized macrophages. Reciprocally, Chemokine ligand 18 (CCL18) from M2 macrophages promotes HCC progression. Furthermore, CTGF and CCL18 were increased significantly in HCC compared to adjacent normal liver tissues. In summary, our study discovered a positive feedback loop between CTGF and CCL18 in HCC metastasis. Targeting CTGF or CCL18 might provide beneficial effects for the clinical treatment of HCC.