Hepatic Epithelial Cells Research Articles

Mesenchymal stem cells rescue acute hepatic failure by polarizing M2 macrophages

AIMTo investigate whether M1 or M2 polarization contributes to the therapeutic effects of mesenchymal stem cells (MSCs) in acute hepatic failure (AHF).METHODSMSCs were transfused into rats with AHF induced by D-galactosamine (DGalN). The therapeutic effects of MSCs were evaluated based on survival rate and hepatocyte proliferation and apoptosis. Hepatocyte regeneration capacity was evaluated by the expression of the hepatic progenitor surface marker epithelial cell adhesion molecule (EpCAM). Macrophage polarization was analyzed by M1 markers [CD68, tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), inducible nitric oxide synthase (INOS)] and M2 markers [CD163, interleukin (IL)-4, IL-10, arginase-1 (Arg-1)] in the survival and death groups after MSC transplantation.RESULTSThe survival rate in the MSC-treated group was increased compared with the DPBS-treated control group (37.5% vs 10%). MSC treatment protected rats with AHF by reducing apoptotic hepatocytes and promoting hepatocyte regeneration. Immunohistochemical analysis showed that MSC treatment significantly increased the expression of EpCAM compared with the control groups (P < 0.001). Expression of EpCAM in the survival group was significantly up-regulated compared with the death group after MSC transplantation (P = 0.003). Transplantation of MSCs significantly improved the expression of CD163 and increased the gene expression of IL-10 and Arg-1 in the survival group. IL-4 concentrations were significantly increased compared to the death group after MSC transplantation (88.51 ± 24.51 pg/mL vs 34.61 ± 6.6 pg/mL, P < 0.001). In contrast, macrophages showed strong expression of CD68, TNF-α, and INOS in the death group. The concentration of IFN-γ was significantly increased compared to the survival group after MSC transplantation (542.11 ± 51.59 pg/mL vs 104.07 ± 42.80 pg/mL, P < 0.001).CONCLUSIONM2 polarization contributes to the therapeutic effects of MSCs in AHF by altering levels of anti-inflammatory and pro-inflammatory factors.

Efflux transport of estrogen glucuronides by human MRP2, MRP3, MRP4 and BCRP

Estrone, estradiol and estriol are endogenous human estrogens that are rapidly conjugated with glucuronic acid in both intestinal and hepatic epithelial cells. The resulting glucuronides, estrone-3-glucuronide (E1-G), estradiol-3- and 17-glucuronides (E2-3G and E2-17G), as well as estriol-3- and 16-glucuronides (E3-3G and E3-16G) are found in human plasma and urine. Unlike E2-17G, the efflux transport of other estrogen glucuronides by human transporters has not yet been investigated comprehensively. We have studied the transport of E1-G, E2-3G, E3-3G, E3-16G and estrone-3-sulfate (E1-S), another important estrogen conjugate, using the vesicular transport assay with recombinant human MRP2, MRP3, MRP4, MDR1 and BCRP that were expressed in insect cells. The transport screening assays revealed that whereas E1-S was a good and specific substrate for BCRP, the less transporter-specific conjugates, E1-G and E2-3G, were still transported by BCRP at 10-fold higher rates than E1-S. BCRP also transported E3-16G at higher rates than the studied MRPs, while it transported E3-3G at lower rates than MRP3. MRP2 exhibited lower or equal transport rates of E1-G, E2-3G, E3-3G and E3-16G in comparison to MRP3 and BCRP in the screening assays, mainly due to its high Km values, between 180 and 790 μM. MRP3 transported all the tested glucuronides at rather similar rates, at Km values below 20 μM, but lower Vmax values than other transporters. In the case of E3-3G, MRP3 was the most active transporter in the screening assay. MRP4 transported only E3-16G at considerable rates, while none of the tested estrogen conjugates was transported by MDR1 at higher rates than control vesicles. These new results, in combination with previously reported in vivo human data, stimulate our understanding on the substrate specificity and role of efflux transporters in disposition of estrogen glucuronides in humans.

Increased YAP Activation Is Associated With Hepatic Cyst Epithelial Cell Proliferation in ARPKD/CHF

Autosomal recessive polycystic kidney disease/congenital hepatic fibrosis (ARPKD/CHF) is a rare but fatal genetic disease characterized by progressive cyst development in the kidneys and liver. Liver cysts arise from aberrantly proliferative cholangiocytes accompanied by pericystic fibrosis and inflammation. Yes-associated protein (YAP), the downstream effector of the Hippo signaling pathway, is implicated in human hepatic malignancies such as hepatocellular carcinoma, cholangiocarcinoma, and hepatoblastoma, but its role in hepatic cystogenesis in ARPKD/CHF is unknown. We studied the role of the YAP in hepatic cyst development using polycystic kidney (PCK) rats, an orthologous model of ARPKD, and in human ARPKD/CHF patients. The liver cyst wall epithelial cells (CWECs) in PCK rats were highly proliferative and exhibited expression of YAP. There was increased expression of YAP target genes, Ccnd1 (cyclin D1) and Ctgf (connective tissue growth factor), in PCK rat livers. Extensive expression of YAP and its target genes was also detected in human ARPKD/CHF liver samples. Finally, pharmacological inhibition of YAP activity with verteporfin and short hairpin (sh) RNA-mediated knockdown of YAP expression in isolated liver CWECs significantly reduced their proliferation. These data indicate that increased YAP activity, possibly through dysregulation of the Hippo signaling pathway, is associated with hepatic cyst growth in ARPKD/CHF.

Selectivity in the Efflux of Glucuronides by Human Transporters: MRP4 Is Highly Active toward 4-Methylumbelliferone and 1-Naphthol Glucuronides, while MRP3 Exhibits Stereoselective Propranolol Glucuronide Transport.

Xenobiotic and endobiotic glucuronides, which are generated in hepatic and intestinal epithelial cells, are excreted via efflux transporters. Multidrug resistance proteins 2-4 (MRP2-MRP4) and the breast cancer resistance protein (BCRP) are efflux transporters that are expressed in these polarized cells, on either the basolateral or apical membranes. Their localization, along with expression levels, affects the glucuronide excretion pathways. We have studied the transport of three planar cyclic glucuronides and glucuronides of the two propranolol enantiomers, by the vesicular transport assay, using vesicles from baculovirus-infected insect cells expressing human MRP2, MRP3, MRP4, or BCRP. The transport of estradiol-17β-glucuronide by recombinant MRP2-4 and BCRP, as demonstrated by kinetic values, were within the ranges previously reported. Our results revealed high transport rates and apparent affinity of MRP4 toward the glucuronides of 4-methylumbelliferone, 1-naphthol, and 1-hydroxypyrene (Km values of 168, 13, and 3 μM, respectively) in comparison to MRP3 (Km values of 278, 98, and 8 μM, respectively). MRP3 exhibited lower rates, but stereoselective transport of propranolol glucuronides, with higher affinity toward the R-enantiomer than the S-enantiomer (Km values 154 vs 434 μM). The glucuronide of propranolol R-enantiomer was not significantly transported by either MRP2, MRP4, or BCRP. Of the tested small glucuronides in this study, BCRP transported only 1-hydroxypyrene glucuronide, at very high rates and high apparent affinity (Vmax and Km values of 4400 pmol/mg/min and 11 μM). The transport activity of MRP2 with all of the studied small glucuronides was relatively very low, even though it transported the reference compound, estradiol-17β-glucuronide, at a high rate (Vmax = 3500 pmol/mg/min). Our results provide new information, at the molecular level, of efflux transport of the tested glucuronides, which could explain their disposition in vivo, as well as provide new tools for in vitro studies of MRP3, MRP4, and BCRP.

Impaired autophagic flux and p62-mediated EMT are involved in arsenite-induced transformation of L-02 cells

Autophagy is a catabolic process essential for preserving cellular homeostasis, and the epithelial-to-mesenchymal transition (EMT) is involved during tissue development and cancer progression. In arsenite-treated human hepatic epithelial (L-02) cells, arsenite reduced the autophagic flux, which caused accumulation of p62, an adaptor and receptor of autophagy. Further, in arsenite-transformed L-02 cells, the levels of E-cadherin were attenuated, but the levels of vimentin, which is expressed in mesenchymal cells, and Snail, a transcription regulator of the EMT, were up-regulated. Thus, after chronic exposure of L-02 cells to arsenite, the impaired autophagic flux induced the accumulation of p62, which up-regulated the expression of Snail, a protein involved in arsenite-induced EMT of these cells. Knockdown of p62 by siRNA reversed the arsenite-induced EMT and decreased the capacities of arsenite-transformed L-02 cells for colony formation and invasion and migration. Therefore, in arsenite-induced transformation of L-02 cells, the accumulation of p62, by impairing autophagic flux, mediates the EMT via Snail. These results provide a previously unknown mechanism underlying arsenic toxicity and carcinogenicity.

Two new iridoid glycosides from the leaves of Callicarpa nudiflora

Two new iridoid glycosides, callicoside C (1) and callicoside D (2), together with three known compounds (3–5), were isolated from the leaves of Callicarpa nudiflora. Their structures were established by 1D and 2D NMR spectroscopy and mass spectrometry. In an in vitro bioassay, compound 1 showed pronounced hepatoprotective activity against d-galactosamine-induced toxicity in WB-F344 rat hepatic epithelial stem-like cells.

Cellular responses to T-2 toxin and/or deoxynivalenol that induce cartilage damage are not specific to chondrocytes

The relationship between T-2 toxin and deoxynivalenol (DON) and the risk of Kashin-Beck disease is still controversial since it is poorly known about their selectivity in cartilage damage. We aimed to compare the cytotoxicity of T-2 toxin and DON on cell lines representative of cell types encountered in vivo, including human chondrocytes (C28/I2), human hepatic epithelial cells (L-02) and human tubular epithelial cells (HK-2). In addition, we determined the distribution of T-2 toxin and DON in Sprague-Dawley (SD) rats after a single dose exposure. T-2 toxin or DON decreased proliferation in a time- and concentration-dependent manner and their combination showed a similar antagonistic effect in C28/I2, L-02 and HK-2 cells. Moreover, we observed cell cycle arrest and apoptosis, associated with increased oxidative stress and decline in mitochondrial membrane potential induced by T-2 toxin and/or DON. In vivo study showed that T-2 toxin and DON did not accumulate preferentially in the knee joint compared to liver and kidney after an acute exposure in SD rats. These results suggest that T-2 toxin and/or DON inhibit proliferation and induce apoptosis through a possible mechanism involving reactive oxygen species-mediated mitochondrial pathway that is not specific for chondrocytes in vitro or joint tissues in vivo.

Ameliorative Effect of Curcumin-Encapsulated Hyaluronic Acid-PLA Nanoparticles on Thioacetamide-Induced Murine Hepatic Fibrosis.

In this study, we developed curcumin-encapsulated hyaluronic acid–polylactide nanoparticles (CEHPNPs) to be used for liver fibrosis amelioration. CD44, the hyaluronic acid (HA) receptor, is upregulated on the surface of cancer cells and on activated hepatic stellate cells (aHSCs) rather than normal cells. CEHPNPs could bind to CD44 and be internalized effectively through endocytosis to release curcumin, a poor water-soluble liver protective agent. Thus, CEHPNPs were potentially not only improving drug efficiency, but also targeting aHSCs. HA and polylactide (PLA) were crosslinked by adipic acid dihydrazide (ADH). The synthesis of HA–PLA was monitored by Fourier-transform infrared (FTIR) and Nuclear Magnetic Resonance (NMR). The average particle size was approximately 60–70 nm as determined by dynamic light scattering (DLS) and scanning electron microscope (SEM). Zeta potential was around −30 mV, which suggested a good stability of the particles. This drug delivery system induced significant aHSC cell death without affecting quiescent HSCs, hepatic epithelial, and parenchymal cells. This system reduced drug dosage without sacrificing therapeutic efficacy. The cytotoxicity IC50 (inhibitory concentration at 50%) value of CEHPNPs was approximately 1/30 to that of the free drug treated group in vitro. Additionally, the therapeutic effects of CEHPNPs were as effective as the group treated with the same curcumin dose intensity in vivo. CEHPNPs significantly reduced serum aspartate transaminase/alanine transaminase (ALT/AST) significantly, and attenuated tissue collagen production and cell proliferation as revealed by liver biopsy. Conclusively, the advantages of superior biosafety and satisfactory therapeutic effect mean that CEHPNPs hold great potential for treating hepatic fibrosis.

Emerging advancements in liver regeneration and organogenesis as tools for liver replacement.

Although the liver possesses a unique, innate ability to regenerate through mass compensation, transplantation remains the only therapy when damage outpaces regeneration, or liver metabolic capacity is irreversibly impacted. Recent insight from developmental biology has greatly influenced the advancement of alternative options to transplantation in these settings. Factors known to direct liver cell specification, expansion, and differentiation have been used to generate hepatocyte-like cells from stem and somatic cells for developing cell therapies. Additionally, interactions between hepatic epithelial and nonepithelial cells key to establishing hepatic architecture have been used in tissue engineering approaches to advance self-organizing hepatic organoids and bioartificial liver devices. Simultaneously, recent clinically applicable advances in human hepatocyte transplantation and promotion of innate hepatic regeneration have been limited. Although mature hepatocytes have the potential to bridge to, or replace whole organ transplantation, limits in the ability to obtain healthy cells, stabilize in-vitro expansion, cryopreserve, and alleviate rejection, still exist. Alternative sources for generating hepatocytes hold promise for cell therapy and tissue engineering. These may allow generation of autologous or universal donor cells that eliminate the need for immunosuppression; however, limits exist regarding hepatocyte maturity and efficacy at liver repopulation, as well as applicability to human chronic liver disease.

NF-kB-regulated exosomal miR-155 promotes the inflammation associated with arsenite carcinogenesis

In the cancer microenvironment, extracellular communication allows various types of cells to coordinate and execute biological functions. Emerging evidence indicates that exosomes, as mediators of cell communication, are involved in tumor progression. Little is known, however, about the mechanism by which exosomal miRNAs regulate inflammatory infiltration in arsenite-induced liver cancer. The present research aimed to determine if miRNAs secreted from arsenite-transformed human hepatic epithelial (L-02) cells are transferred into normal L-02 and THLE-3 cells, which are functionally active in the recipient cells. The results show that the exosomes from arsenite-transformed L-02 cells enhance miR-155 expression and the pro-inflammatory properties of normal L-02 and THLE-3 cells. Transformed cells transfer miR-155 into normal L-02 cells via exosomes. The inhibition of NF-κB by siRNA and inhibitor, which reduces miR-155 levels in exosomes derived from transformed L-02 cells, blocks inflammation. Arsenite-transformed cells secrete exosomes to enhance inflammation, but the inhibition of the synthesis of exosomes fails to stimulate inflammation. miR-155 is involved in exosome-mediated intercellular communication between neoplastic and normal liver cells. In addition, miR-155, IL-6, and IL-8 were over-expressed in the serum of arsenite exposure group. And there was a positive correlation between miR-155 and IL-6 or IL-8 levels. Further, exosomal miR-155 was up-regulated in the serum of arsenite exposure group. Thus, these results show that exosomes derived from transformed L-02 cells transfer miR-155 to surrounding cells, which induces pro-inflammatory activity of normal liver cells. The findings support the concept that exosomal miRNAs are involved in cell–cell communication during carcinogenesis induced by environmental chemicals.

The environmental carcinogen benzo[a]pyrene induces a Warburg-like metabolic reprogramming dependent on NHE1 and associated with cell survival.

Cancer cells display alterations in many cellular processes. One core hallmark of cancer is the Warburg effect which is a glycolytic reprogramming that allows cells to survive and proliferate. Although the contributions of environmental contaminants to cancer development are widely accepted, the underlying mechanisms have to be clarified. Benzo[a]pyrene (B[a]P), the prototype of polycyclic aromatic hydrocarbons, exhibits genotoxic and carcinogenic effects, and it is a human carcinogen according to the International Agency for Research on Cancer. In addition to triggering apoptotic signals, B[a]P may induce survival signals, both of which are likely to be involved in cancer promotion. We previously suggested that B[a]P-induced mitochondrial dysfunctions, especially membrane hyperpolarization, might trigger cell survival signaling in rat hepatic epithelial F258 cells. Here, we further characterized these dysfunctions by focusing on energy metabolism. We found that B[a]P promoted a metabolic reprogramming. Cell respiration decreased and lactate production increased. These changes were associated with alterations in the tricarboxylic acid cycle which likely involve a dysfunction of the mitochondrial complex II. The glycolytic shift relied on activation of the Na+/H+ exchanger 1 (NHE1) and appeared to be a key feature in B[a]P-induced cell survival related to changes in cell phenotype (epithelial-to-mesenchymal transition and cell migration).

An efficient and simple co-culture method for isolating primary human hepatic cells: Potential application for tumor microenvironment research.

Co-cultivation of non-parenchymal cells(NPCs) and tumor cells from the same donor is important for metastatic cancer research. This study aimed to optimize a protocol for liver NPC isolation. Two novel 3D organotypic co‑culture models for hepatocyte, endothelial cell(EC) and Kupffer cell(KC) isolation were used. Long‑term cell co‑culture, density gradient centrifugation and magnetic‑activated cell sorting(MACS) were established. ECs were isolated from the co‑culture system; the purity of the ECs was 92±1.2%. The island‑like shape of hepatocytes was noted in the 3D co‑culture system, and spindle cells were found in the rest space. Immunofluorescence analysis showed a net structure; the connective tissue was positively stained with VE‑cadherin or CD68, which were ECs and KCs/macrophages. KCs were enriched in this system and separated by using selective adherence to plastic. Clec4f+ KCs consisted of 87±6.3% of these cells. Heterogeneous endothelium populations were detected, including sinusoid ECs, microvascular ECs and hepatic lymphatic vessel epithelial cells. In addition, hepatic progenitor cells were isolated and differentiated into hepatoblasts. Dendritic cells(DCs), invariant natural killer T(iNKT) cells were further separated by density gradient centrifugation and magnetic bead sorting. In the present study, high protein expression levels of desmin and GFAP were observed in the hepatic stellate cells(HSCs). Most of the HSCs were α‑SMA‑positive cells, which underlined the identity of activated HSCs. Intrahepatic human biliary epithelial cells(hBECs) were semi‑purified by centrifugation on a Percoll gradient and were further immunopurified. In conclusion, we provide an efficient long‑term culture method to obtain liver NPCs in sufficient number and purity.

A novel arrangement of midgut epithelium and hepatic cells implies a novel regulation of the insulin signaling pathway in long-lived millipedes

Nutrients absorbed by the epithelial cells of the millipede midgut are channeled to a contiguous population of hepatic cells where sugars are stored as glycogen. In insects and other arthropods, however, nutrients absorbed by midgut epithelia are first passed across the epithelial basal surface to the hemolymph before storage in fat body. The inter-digitation of cellular processes at the interface of hepatic and midgut epithelial cells offers a vast surface area for exchange of nutrients. At this interface, numerous small vesicles with the dimensions of exosomes (∼30nm) may represent the mediators of nutrient exchange. Longevity and the developmental arrest of diapause are associated with reduced insulin signaling. The long lifespans for which millipedes are known may be attributable to a novel pathway with reduced insulin signaling represented by the novel arrangement of hepatic storage cells and midgut epithelial absorbing cells.

The lncRNA MALAT1, acting through HIF-1α stabilization, enhances arsenite-induced glycolysis in human hepatic L-02 cells

Accelerated glycolysis, a common process in tumor cells called the Warburg effect, is associated with various biological phenomena. However, the role of glycolysis induced by arsenite, a well-established human carcinogen, is unknown. Long non-coding RNAs (lncRNAs) act as regulators in various cancers, but how lncRNAs regulate glucose metabolism remains largely unexplored. We have found that, in human hepatic epithelial (L−02) cells, arsenite increases lactate production; glucose consumption; and expression of glycolysis-related genes, including HK-2, Eno-1, and Glut-4. In L-02 cells exposed to arsenite, the lncRNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and hypoxia inducible factors (HIFs)-α, the transcriptional regulators of cellular response to hypoxia, are over-expressed. In addition, HIF-1α, not HIF-2α, is involved in arsenite-induced glycolysis, and MALAT1 enhances arsenite-induced glycolysis. Although MALAT1 regulates HIF-α and promotes arsenite-induced glycolysis, MALAT1 promotes glycolysis through HIF-1α, not HIF-2α. Moreover, arsenite-increased MALAT1 enhances the disassociation of Von Hippel–Lindau (VHL) tumor suppressor from HIF-1α, alleviating VHL-mediated ubiquitination of HIF-1α, which causes accumulation of HIF-1α. In sum, these findings indicate that MALAT1, acting through HIF-1α stabilization, is a mediator that enhances glycolysis induced by arsenite. These results provide a link between the induction of lncRNAs and the glycolysis in cells exposed to arsenite, and thus establish a previously unknown mechanism for arsenite-induced hepatotoxicity.

MicroRNA-21 activation of ERK signaling via PTEN is involved in arsenite-induced autophagy in human hepatic L-02 cells.

Autophagy, an evolutionarily conserved cellular process, has diverse physiological and pathological roles in biological functions. Whether autophagy is induced by arsenite, a well-established human carcinogen, and the molecular mechanisms involved, remain to be established. Further, microRNAs (miRNAs) act as regulators in various cancers, but how miRNAs regulate autophagy remains largely unexplored. We have found that, in human hepatic epithelial (L-02) cells, arsenite increases levels of autophagy-related proteins in a concentration- and time-dependent manner and elevates the number of autophagic vacuoles (AVs). Arsenite also activates the ERK pathway in a dose- and time-dependent manner. In L-02 cells exposed to arsenite, microRNA-21 (miRNA-21) is over-expressed, and its target proteins, PTEN, PDCD4, and Spry1, are decreased. Moreover, inhibition of miR-21 increases levels of PTEN, and reduces levels of Beclin 1 and LC3 II/I, indicating that miR-21 is involved in arsenite-induced autophagy. In addition, ectopic expression of PTEN blocks the effect of miR-21 on the arsenite-induced autophagy and decreases p-ERK levels. Also, ERK promotes the autophagy induced by arsenite. In sum, upon exposure of cells to arsenite, over-expression of miR-21 activates ERK through PTEN, factors that participate in arsenite-induced autophagy. This link, mediated through miRNAs, establishes a mechanism for the development of autophagy that is associated with arsenic toxicity. Such information contributes to an understanding of the liver toxicity caused by arsenite.

Induction of hepatic tissues in multicellular spheroids composed ofmurine fetal hepatic cells and embedded hydrogel beads.

IntroductionThree-dimensional (3D) multicellular spheroids are useful tools for simulation of cellular functions in vitro. However, it is difficult to culture certain epithelial cell types under 3D spheroid conditions because these cells cannot resist autonomous cell death, triggered by disordered cell polarity. The objective of this study was to find a method that enables spheroid culture of such epithelial cells utilizing hydrogel beads without cell death.MethodsWe used murine E14.5 fetal hepatic cells for the spheroid composition because they are sensitive to disorganized structures. Spheroids were formed by injecting 1-μl fresh medium containing 1000 fetal hepatic cells and the same number of alginate hydrogel beads (20 μm in diameter) into a 3% methylcellulose medium in the presence of dexamethasone and oncostatin M to induce hepatic differentiation. After 7 days of culture, microstructures were observed using hematoxylin and eosin staining and immunostaining using anti-CK8/18 antibody. Albumin secretion rate was determined by the enzyme-linked immunosorbent assay method. In addition, polarity-related proteins, E-cadherin, ezrin, and MRP2 were observed with immunostaining.ResultsControl spheroids without the use of alginate hydrogel beads showed extensive internal lack of epithelial hepatic cells. The spheroids containing alginate hydrogel beads exhibited sheet- or cord-like structures of epithelial hepatic cells, and it was clear that cell death of epithelial cells had been prevented. Albumin secretion data also supported the improvement of epithelial hepatic cell viability when alginate hydrogel beads were used. Localization of polarity-related proteins indicated the partial reconstitution of cell polarity in the spheroids using alginate hydrogel beads.ConclusionBased on these data, we concluded that the application of alginate hydrogel beads was effective in improving the epithelial hepatic cell culture of multicellular spheroids.

The Cytolethal Distending Toxin Subunit CdtB of Helicobacter Induces a Th17-related and Antimicrobial Signature in Intestinal and Hepatic Cells In Vitro.

Enterohepatic Helicobacter species are associated with several digestive diseases. Helicobacter pullorum is an emerging human foodborne pathogen, and Helicobacter hepaticus is a mouse pathogen; both species are associated with intestinal and/or hepatic diseases. They possess virulence factors, such as cytolethal distending toxin (CDT). Data indicate that CDT may be involved in chronic inflammatory responses, via its active subunit, CdtB. The proinflammatory properties of the CdtB of H. pullorum and H. hepaticus were assessed on human intestinal and hepatic epithelial cells in vitro. Interleukin 8 expression was evaluated by using wild-type strains and their corresponding CdtB isogenic mutants and by delivering CdtB directly into the cells. Nuclear factor κB nuclear translocation and transcriptomic characteristics in response to CdtB were also evaluated. The CdtB of these Helicobacter species induced nuclear factor κB nuclear translocation and exhibited proinflammatory properties, mainly the expression of T-helper type 17-related genes and genes encoding antimicrobial products also involved in cancer. The Histidine residue in position 265 of the CdtB catalytic site appeared to play a role in the regulation of most of these genes. As for flagellin or lipopolysaccharides, CdtB also induced expression of inflammation-associated genes related to antimicrobial activity.

Differential Lipotoxic Effects of Palmitate and Oleate in Activated Human Hepatic Stellate Cells and Epithelial Hepatoma Cells

Background/Aims: Nonalcoholic fatty liver disease (NAFLD) progression to fibrosis, cirrhosis and hepatocellular carcinoma, alters the cellular composition of this organ. During late-stage NAFLD, fibrotic and possibly cancerous cells can proliferate and, like normal hepatocytes, are exposed to high concentrations of fatty acids from both surrounding tissue and circulating lipid sources. We hypothesized that primary human activated hepatic stellate cells and epithelial hepatoma (HepG2) cells respond differently to lipotoxic conditions, and investigated the mechanisms involved. Methods: Primary activated hepatic stellate cells and HepG2 cells were exposed to pathophysiological concentrations of fatty acids and comparative studies of lipid metabolic and stress response pathways were performed. Results: Both cell types remained proliferative during exposure to a combination of palmitate plus oleate reflective of the general saturated versus unsaturated fatty acid composition of western diets. However, exposure to either high palmitate or high oleate alone induced cytotoxicity in activated stellate cells, while only palmitate caused cytotoxicity in HepG2 cells. mRNA microarray and biochemical comparisons revealed that stellate cells stored markedly less fatty acids as neutral lipids, and had reduced capacity for beta-oxidation. Similar to previous observations in HepG2 cells, palmitate, but not oleate, induced ER stress and actin stress fiber formation in activated stellate cells. In contrast, oleate, but not palmitate, induced the inflammatory signal TXNIP, decreased cytoskeleton proteins, and decreased cell polarity preceding cell death in activated stellate cells. Conclusions: Palmitate-induced lipotoxicity was associated with ER stress pathways in both primary activated hepatic stellate cells and epithelial hepatoma cells, whereas high oleate caused lipotoxicity only in activated stellate cells, possibly through a distinct mechanism involving disruption of cytoskeleton components. This may have implications for optimal dietary fatty acid compositions during various stages of NAFLD.

CRYOGELS BASED ON POLYELECTROLYTE COMPLEX BETWEEN CHITOSAN AND GELATIN FORMED UNDER CRYOCONDITIONS FOR TISSUE ENGINEERING

Cryogelation technique is a versatile technique for design of various biocompatible scaffolds based on natural polymers as gelatin(Gel), chitosan and casein using cryogelation technique. [1-4] Cryogelation is the process of the formation of macroporous polymer systems, so called cryogels, with well-developed 3D structure of interconnected pores. Cryogels have porosity of 90-95% and macro-channels of 20-150 µm in size. Interconnected pores provide unrestricted penetration of nutrients and provides high surface area for attachment and proliferation of mammalian cells.[1,2] Previously, the preparation of Gel based cryogel was carried out in environmentally friendly way using enzymatic reaction under cryoconditions.[3] To prepare stable materials we developed a preparation method allowing avoid the use of toxic reducing agent borohydride for reduction of Schiff's base.[4] In this study we used dextran dialdehyde as a mild nontoxic cross-linker for preparation of cryogels based on different types of gelatin and chitosan. Additionally the cryogels were cross-linked via formation of polyelectrolyte complex(PEC) between oppositely charged groups of gelatine and chitosan. Physico-chemical properties, elastic modulus and degradation of the materials based on different ratios of dextran-gelatin anddextran-gelatin-chitosan at physiological conditions were inverstigated. Human hepatic epithelial cell culture line and fibroblasts cells grow in the dextran-gelatin-chitosan cryogel scaffolds were studied. The type of gelatin significantly affected the migration, proliferation of cell and also microscopic morphology of the scaffold. The dextran-chitosan-gelatin (fish)(1:1:1wt %) based materials show better fibroblast growth compare to dextran-fish gelatin only. The cryogels containing dextran-chitosan-gelatin(bovine A)(1:1:1wt %) revealed good attachment and proliferation of hepatocytes inside of the material, whereas the cell line formed clusters on the surface of the PEC cryogel based on dextran-chitosan-gelatin(bovine A)(Fig. 1).

A MALAT1/HIF-2α feedback loop contributes to arsenite carcinogenesis

Arsenic is well established as a human carcinogen, but the molecular mechanisms leading to arsenic-induced carcinogenesis are complex and elusive. It is also not known if lncRNAs are involved in arsenic-induced liver carcinogenesis. We have found that MALAT1, a non-coding RNA, is over-expressed in the sera of people exposed to arsenite and in hepatocellular carcinomas (HCCs), and MALAT1 has a close relation with the clinicopathological characteristics of HCC. In addition, hypoxia-inducible factor (HIF)-2α is up-regulated in HCCs, and MALAT1 and HIF-2α have a positive correlation in HCC tissues. During the malignant transformation of human hepatic epithelial (L-02) cells induced by a low concentration (2.0 μM) of arsenite, MALAT1 and HIF-2α are increased. In addition, arsenite-induced MALAT1 causes disassociation of the von Hippel-Lindau (VHL) protein from HIF-2α, therefore, alleviating VHL-mediated HIF-2α ubiquitination, which causes HIF-2α accumulation. In turn, HIF-2α transcriptionally regulates MALAT1, thus forming a positive feedback loop to ensure expression of arsenite-induced MALAT1 and HIF-2α, which are involved in malignant transformation. Moreover, MALAT1 and HIF-2α promote the invasive and metastatic capacities of arsenite-induced transformed L-02 cells and in HCC-LM3 cells. The capacities of MALAT1 and HIF-2α to promote tumor growth are validated in mouse xenograft models. In mice, arsenite induces an inflammatory response, and MALAT1 and HIF-2α are over-expressed. Together, these findings suggest that the MALAT1/HIF-2α feedback loop is involved in regulation of arsenite-induced malignant transformation. Our results not only confirm a novel mechanism involving reciprocal regulation between MALAT1 and HIF-2α, but also expand the understanding of the carcinogenic potential of arsenite.