Cancer-associated fibroblasts (CAFs) transdifferentiated from hepatic stellate cells (HSCs) are a critical determinant of liver metastasis of colorectal cancer (CRC). How... More
Cancer-associated fibroblasts (CAFs) transdifferentiated from hepatic stellate cells (HSCs) are a critical determinant of liver metastasis of colorectal cancer (CRC). However, the mechanisms behind transforming growth factor β (TGF-β)-stimulated activation of HSCs into CAFs remain poorly understood. Immunoprecipitation coupled with mass spectrometry identified tuftelin 1 (TUFT1) as a novel TGF-β receptor II (TβRII) binding protein in primary human HSCs and immortalized LX2 cells. TUFT1 interacts with TβRII via its fragments (amino acids 1–86, 87–157), protecting TβRII from lysosomal degradation to facilitate TGF-β signaling and myofibroblastic activation of HSCs. Mechanistically, TUFT1 competes with caveolin-1 for TβRII binding, retrieving TβRII from the lipid rafts/caveolae-mediated degradation pathway and sorting it into the endosome-mediated trafficking and signaling pathway. Clinically, TUFT1 expression was confirmed in the CAFs of patient-derived colorectal cancer liver metastasis (CRCLM) tissues. Both protein and transcript analyses revealed higher TUFT1 expression in the CAFs of CRCLM than in HSCs. Furthermore, bulk RNA sequencing indicated that knocking down TUFT1 altered the TGF-β transcriptome of HSCs and suppressed HSC expression of tumor-promoting factors. In HSC/CRC co-implantation and portal vein tumor injection mouse models, targeting TUFT1 of HSCs inhibited HSC activation and restricted CRC growth in both subcutaneous and hepatic sites. Taken together, our findings uncover the novel function of TUFT1 in the hepatic tumor microenvironment, highlighting its role as a critical regulator of HSC activation and the pro-metastatic hepatic niche via promoting TβRII protein stability. Targeting TUFT1 in HSCs presents a promising therapeutic approach for combating CRCLM. Less
Background The induction of apoptosis in hepatic stellate cells (HSCs) is a promising therapeutic strategy against hepatitis B virus (HBV)-related hepatic fibrosis. The u... More
Background The induction of apoptosis in hepatic stellate cells (HSCs) is a promising therapeutic strategy against hepatitis B virus (HBV)-related hepatic fibrosis. The underlying mechanisms of apoptosis in HSCs, however, are unknown under consideration of HBV infection. In this study, the effects of HBV on apoptosis and endoplasmic reticulum (ER) stress signaling in HSCs were examined. Methods The effects of conditioned media (CM) from HepG2.2.15 on apoptosis induced by the proteasome inhibitor MG132 in LX-2 and HHSteC were studied in regard to c-Jun. In combination with c-Fos, c-Jun forms the AP-1 early response transcription factor, leading to AP-1 activation, signal transduction, endoplasmic reticulum (ER) stress and apoptosis. Results In LX-2 cells, MG132 treatment was associated with the phosphorylation of c-Jun, activation of AP-1 and apoptosis. However, in the presence of CM from HepG2.2.15, these phenomena were attenuated. In HHSteC cells, similar results were observed. HBV genomic DNA is not involved in the process of HSC apoptosis. It is possible that HBeAg has an inhibitory effect on MG132-induced apoptosis in LX-2. We also observed the upregulation of several ER stress-associated genes, such as cAMP responsive element binding protein 3-like 3, inhibin-beta A and solute carrier family 17-member 2, in the presence of CM from HepG2.2.15, or CM from PXB cells infected with HBV. Conclusions HBV inhibits the activation of c-Jun/AP-1 in HSCs, contributing to the attenuation of apoptosis and resulting in hepatic fibrosis. HBV also up-regulated several ER stress genes associated with cell growth and fibrosis. These mechanistic insights might shed new light on a treatment strategy for HBV-associated hepatic fibrosis. Less
Background
Immuno-genetic studies suggest a functional link between NK cells and λ-IFNs. We recently showed that NK cells are negative for the IFN-λ receptor IFN-λR1 ... More
Background
Immuno-genetic studies suggest a functional link between NK cells and λ-IFNs. We recently showed that NK cells are negative for the IFN-λ receptor IFN-λR1 and do not respond to IFN-λ, suggesting a rather indirect association between IL-28B genotype and NK cell activity.
Methods
A total of 75 HCV(+) patients and 67 healthy controls were enrolled into this study. IL-28B (rs12979860) and IFNL-4 (rs368234815) genotypes were determined by rtPCR. Total PBMC, monocytes, and NK cells were stimulated with IL-29, the TLR-7/8 agonist R848, or a combination of both. NK cell IFN-Îł response was analysed by FACS. IL-12 and IL-18 secretion of monocytes was studied by ELISA. In blocking experiments anti-IL-12/anti-IL-18 were used.
Results
Following stimulation of total PBMCs with R848 we found NK cell IFN- Îł responses to vary with the IL-28B genotype, with carriers of a T/T genotype displaying the lowest frequency of IFN-Îł(+)NK cells. When isolated NK cells were studied no such associations were observed, indicating an indirect association between IL-28B genotype and NK cell activity. Accordingly, we found R848-stimulated monocytes of patients with a T/T genotype to be significantly less effective in triggering NK cell IFN- Îł production than monocytes from carriers of a non-T/T genotype. In line with these findings we observed monocytes from T/T patients to secrete significantly lower concentrations of IL-12 than monocytes from non-T/T individuals.
Conclusions
Our data indicate that monocytes from carriers of an IL-28B T/T genotype display a reduced ability to stimulate NK cell activity and, thus, provide a link between IL-28B genotype and NK functions.
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The mammalian diffuse stellate cell system comprises retinoid-storing cells capable of remarkable transformations from a quiescent to an activated myofibroblast-like phen... More
The mammalian diffuse stellate cell system comprises retinoid-storing cells capable of remarkable transformations from a quiescent to an activated myofibroblast-like phenotype. Activated pancreatic stellate cells (PSCs) attract attention owing to the pivotal role they play in development of tissue fibrosis in chronic pancreatitis and pancreatic cancer. However, little is known about the actual role of PSCs in the normal pancreas. These enigmatic cells have recently been shown to respond to physiological stimuli in a manner that is markedly different from their neighbouring pancreatic acinar cells (PACs). Here, we demonstrate the capacity of PSCs to generate nitric oxide (NO), a free radical messenger mediating, for example, inflammation and vasodilatation. We show that production of cytosolic NO in PSCs is unambiguously related to cytosolic Ca2+ signals. Only stimuli that evoke Ca2+ signals in the PSCs elicit consequent NO generation. We provide fresh evidence for the striking difference between signalling pathways in PSCs and adjacent PACs, because PSCs, in contrast to PACs, generate substantial Ca2+-mediated and NOS-dependent NO signals. We also show that inhibition of NO generation protects both PSCs and PACs from necrosis. Our results highlight the interplay between Ca2+ and NO signalling pathways in cell–cell communication, and also identify a potential therapeutic target for anti-inflammatory therapies. Less
Autophagy, a type II programmed cell death, is essential for cell survival under stress, e.g. lung injury, and bone marrow-derived mesenchymal stem cells (BM-MSCs) have g... More
Autophagy, a type II programmed cell death, is essential for cell survival under stress, e.g. lung injury, and bone marrow-derived mesenchymal stem cells (BM-MSCs) have great potential for cell therapy. However, the mechanisms underlying the BM-MSC activation of autophagy to provide a therapeutic effect in ischaemia/reperfusion-induced lung injury (IRI) remain unclear. Thus, we investigate the activation of autophagy in IRI following transplantation with BM-MSCs. Seventy mice were pre-treated with BM-MSCs before they underwent lung IRI surgery in vivo. Human pulmonary micro-vascular endothelial cells (HPMVECs) were pre-conditioned with BM-MSCs by oxygen-glucose deprivation/reoxygenation (OGD) in vitro. Expression markers for autophagy and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signalling pathway were analysed. In IRI-treated mice, administration of BM-MSCs significantly attenuated lung injury and inflammation, and increased the level of autophagy. In OGD-treated HPMVECs, co-culture with BM-MSCs attenuated endothelial permeability by decreasing the level of cell death and enhanced autophagic activation. Moreover, administration of BM-MSCs decreased the level of PI3K class I and p-Akt while the expression of PI3K class III was increased. Finally, BM-MSCs-induced autophagic activity was prevented using the inhibitor LY294002. Administration of BM-MSCs attenuated lung injury by improving the autophagy level via the PI3K/Akt signalling pathway. These findings provide further understanding of the mechanisms related to BM-MSCs and will help to develop new cell-based therapeutic strategies in lung injury. Less
MicroRNA-122 (miR-122) is one of the most abundant miRs in the liver. Previous studies have demonstrated that miR-122 plays a role in inflammation in the liver and functi... More
MicroRNA-122 (miR-122) is one of the most abundant miRs in the liver. Previous studies have demonstrated that miR-122 plays a role in inflammation in the liver and functions in hepatic stellate cells (HSCs), which reside in the space of Disse. Here, we showed that the transient inhibition of PKR-activating protein (PACT) expression, by miR-122 or siRNA targeting of PACT, suppressed the production of proinflammatory cytokines, such as interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1) and IL-1β, in human HSC LX-2. Sequence and functional analyses confirmed that miR-122 directly targeted the 3′-untranslated region of PACT. Immunofluorescence analysis revealed that miR-122 blocked NF-κB-nuclear translocation in LX-2 cells. We also showed that conditioned medium from miR-122-transfected LX-2 cells suppressed human monocyte-derived THP-1 cell migration. Taken together, our study indicates that miR-122 may downregulate cytokine production in HSCs and macrophage chemotaxis and that the targeting of miR-122 may have therapeutic potential for preventing the progression of liver diseases. Less
Current in vitro and animal tests for drug development are failing to emulate the systemic organ complexity of the human body and, therefore, to accurately predict drug t... More
Current in vitro and animal tests for drug development are failing to emulate the systemic organ complexity of the human body and, therefore, to accurately predict drug toxicity. In this study, we present a multi-organ-chip capable of maintaining 3D tissues derived from cell lines, primary cells and biopsies of various human organs. We designed a multi-organ-chip with co-cultures of human artificial liver microtissues and skin biopsies, each a 1/100 000 of the biomass of their original human organ counterparts, and have successfully proven its long-term performance. The system supports two different culture modes: i) tissue exposed to the fluid flow, or ii) tissue shielded from the underlying fluid flow by standard Transwell® cultures. Crosstalk between the two tissues was observed in 14-day co-cultures exposed to fluid flow. Applying the same culture mode, liver microtissues showed sensitivity at different molecular levels to the toxic substance troglitazone during a 6-day exposure. Finally, an astonishingly stable long-term performance of the Transwell®-based co-cultures could be observed over a 28-day period. This mode facilitates exposure of skin at the air–liquid interface. Thus, we provide here a potential new tool for systemic substance testing. Less
