Cocultures of porcine hepatocytes and Kupffer cells as an improved in vitro model for the study of hepatotoxic compounds

Single-cell multi-omics deciphers hepatocyte dedifferentiation and illuminates maintenance strategies

Due to the similarity to human hepatocytes, porcine hepatocytes play an important role in hepatic research and drug evaluation. However, once hepatocytes were cultured in vitro, it was often prone to dedifferentiate, resulting in the loss of their characteristic features and normal functions, which impede their application in liver transplantation and hepatotoxic drugs evaluation. Up to now, this process has yet to be thoroughly investigated from the single-cell resolution and multi-omics perspective. In this study, we utilized 10× multiome technology to dissect the heterogeneity of porcine hepatocytes at different time points (Days 0, 1, 3, 5 and 7) during dedifferentiation. We comprehensively investigated cell heterogeneity, cellular dynamics, signalling pathways, potential gene targets, enhancer-driven gene regulatory networks, cell-cell communications of these cells and the conservation of mechanisms across species. We found that a series of critical signalling pathways driven by ERK, PI3K, Src and TGF-β were activated during this process, especially in the early stage of dedifferentiation. Based on these discoveries, we constructed a chemical combination targeting these pathways, which effectively inhibited the dedifferentiation of porcine hepatocytes in vitro. To validate the effectiveness of this combination, we transplanted such treated hepatocytes into FRGN mice, and the results demonstrated that these cells could effectively repopulate the liver and improve the survival of mice.

Protective Action of Cannabidiol on Tiamulin Toxicity in Humans-In Vitro Study

The growing awareness and need to protect public health, including food safety, require a thorough study of the mechanism of action of veterinary drugs in consumers to reduce their negative impact on humans. Inappropriate use of veterinary drugs in animal husbandry, such as tiamulin, leads to the appearance of residues in edible animal tissues. The use of natural substances of plant origin, extracted from hemp (Cannabis sativa L.), such as cannabidiol (CBD), is one of the solutions to minimize the negative effects of tiamulin. This study aimed to determine the effect of CBD on the cytotoxicity of tiamulin in humans. The cytotoxic activity of tiamulin and the effect of its mixtures with CBD were tested after 72 h exposure to three human cell lines: SH-SY5Y, HepG2 and HEK-293. Cytotoxic concentrations (IC50) of the tested drug and in combination with CBD were assessed using five biochemical endpoints: mitochondrial and lysosomal activity, proliferation, cell membrane integrity and effects on DNA synthesis. Oxidative stress, cell death and cellular morphology were also assessed. The nature of the interaction between the veterinary drug and CBD was assessed using the combination index. The long-term effect of tiamulin inhibited lysosomal (SH-SY5SY) and mitochondrial (HepG2) activity and DNA synthesis (HEK-293). IC50 values for tiamulin ranged from 2.1 to >200 µg/mL (SH-SY5SY), 13.9 to 39.5 µg/mL (HepG2) and 8.5 to 76.9 µg/mL (HEK-293). IC50 values for the drug/CBD mixtures were higher. Reduced levels of oxidative stress, apoptosis and changes in cell morphology were demonstrated after exposure to the mixtures. Interactions between the veterinary drug and CBD showed a concentration-dependent nature of tiamulin in cell culture, ranging from antagonistic (low concentrations) to synergistic effects at high drug concentrations. The increased risk to human health associated with the presence of the veterinary drug in food products and the protective nature of CBD use underline the importance of these studies in food toxicology and require further investigation.

Phenothiazine derivatives and their impact on the necroptosis and necrosis processes. A review

The current review focuses on the effect of phenothiazine derivatives, tested in vitro, on necrosis and necroptosis, the latter constitutes one of the kinds of programmed cell death. Necroptosis is a necrotic and inflammatory type of programmed cell death. Phenothiazines are D1 and D2-like family receptor antagonists, which are used in the treatment of schizophrenia. Necroptosis begins from TNF-α, whose synthesis is stimulated by dopamine receptors, thus it can be concluded that phenothiazine derivatives may modulate necroptosis. We identified 19 papers reporting in vitro assays of necroptosis and necrosis in which phenothiazine derivatives, and both normal and cancer cell lines were used. Chlorpromazine, fluphenazine, levomepromazine, perphenazine, promethazine, thioridazine, trifluoperazine, and novel derivatives can modulate necroptosis and necrosis. The type of a drug, concentration and a cell line have an impact on the ultimate effect. Unfortunately, the authors confirmed both processes on the basis of TNF-α and ATP levels as well as the final steps of necrosis/necroptosis related to membrane permeability (PI staining, LDH release, and HMGB1 amount), which makes it impossible to understand the complete mechanism of phenothiazines impact on necroptosis and necrosis. Studies analyzing the effect of phenothiazines on RIPK1, RIPK3, or MLKL has not been performed yet. Only the analysis of the expression of those proteins as well as necrosis and necroptosis inhibitors can help us to comprehend how phenothiazine derivatives act, and how to improve their therapeutic potential.

Evaluation of a Flat Membrane Hepatocyte Bioreactor for Pharmacotoxicological Applications: Evidence that Inhibition of Spontaneously Produced Nitric Oxide Improves Cell Functionality

A laboratory-scale bioreactor was re-evaluated, with the aim of improving its use for the perfused culture of rat hepatocytes. In contrast to conventional culture systems, the flat membrane bioreactor (FMB) showed good functionality and biochemical competence during 2-3 days. Hepatocytes cultured in the FMB, specifically in a "sandwich" configuration, were functionally stable, as shown by a high rate of urea biosynthesis after challenge with NH4Cl, a low alanine-aminotransferase leakage and suppressed spontaneous nitric oxide (NO) production. Moreover, the time-course of the disappearance of cyclosporin A (CsA) from the perfusate demonstrated the high biotransformation capacity of cells in the FMB. The effect of CsA on the modulation of urea and spontaneous NO production demonstrated flexibility, in that minor changes could be observed at diverse time intervals and in a non-destructive way. The monitoring of nitrite levels during various steps of isolation and culture suggested that spontaneously produced NO has a negative impact on hepatocyte metabolic and functional integrity. In spite of the sophisticated techniques that are being used for the preparation of bioreactors, with hepatocytes surviving for longer periods, our data have shed light on some factors that could be important for the successful use of similar models for pharmacotoxicological and other biomedical applications.

Porcine hepatocyte-Kupffer cell co-culture as an in vitro model for testing the efficacy of anti-inflammatory substances

As Kupffer cells are highly involved in the regulation of hepatic inflammatory response, the main goal of this study was to improve and to characterize a hepatocyte-Kupffer cell co-culture of pig origin for modelling endotoxin-induced hepatic inflammation and for testing the efficacy of potential anti-inflammatory substances. This monolayer co-culture was prepared from primary isolated swine hepatocytes and Kupffer cells in the ratio of 6:1 and 2:1, mimicking different states of liver inflammation. The prepared cell cultures were characterized by immunohistochemical CD-68 detection. Lipopolysaccharide (LPS) challenge of both co-cultures resulted in elevated interleukin-8 (IL-8) and that of 6:1 co-cultures in increased IL-6 production with a higher extent than on hepatocyte monocultures, justifying the key role of Kupffer cells in pro-inflammatory cytokine production. LPS-induced IL-8 production was successfully attenuated by concomitant application of both sodium butyrate and terpinen-4-ol on hepatocyte monocultures, but not on co-cultures, demonstrating the importance of the presence of Kupffer cells in cell cultures as inflammatory models. Based on these initial data, the applied porcine primary hepatocyte-Kupffer cell co-culture is suggested to be a proper tool for in vitro investigations on liver physiology and hepatic inflammation in pigs and can be used as a useful model mimicking in vivo conditions in veterinary research.

Metabolite profiling and pharmacokinetic evaluation of hydrocortisone in a perfused three-dimensional human liver bioreactor

Endotoxin lipopolysaccharide (LPS) is known to cause liver injury primarily involving inflammatory cells such as Kupffer cells, but few in vitro culture models are applicable for investigation of inflammatory effects on drug metabolism. We have developed a three-dimensional human microphysiological hepatocyte-Kupffer cell coculture system and evaluated the anti-inflammatory effect of glucocorticoids on liver cultures. LPS was introduced to the cultures to elicit an inflammatory response and was assessed by the release of proinflammatory cytokines, interleukin 6 and tumor necrosis factor α. A sensitive and specific reversed-phase-ultra high-performance liquid chromatography-quadrupole time of flight-mass spectrometry method was used to evaluate hydrocortisone disappearance and metabolism at near physiologic levels. For this, the systems were dosed with 100 nM hydrocortisone and circulated for 2 days; hydrocortisone was depleted to approximately 30 nM, with first-order kinetics. Phase I metabolites, including tetrahydrocortisone and dihydrocortisol, accounted for 8-10% of the loss, and 45-52% consisted of phase II metabolites, including glucuronides of tetrahydrocortisol and tetrahydrocortisone. Pharmacokinetic parameters, i.e., half-life, rate of elimination, clearance, and area under the curve, were 23.03 hours, 0.03 hour(-1), 6.6 × 10(-5) l⋅hour(-1), and 1.03 (mg/l)*h, respectively. The ability of the bioreactor to predict the in vivo clearance of hydrocortisone was characterized, and the obtained intrinsic clearance values correlated with human data. This system offers a physiologically relevant tool for investigating hepatic function in an inflamed liver.

Lysosomal disruption preferentially targets acute myeloid leukemia cells and progenitors

Despite efforts to understand and treat acute myeloid leukemia (AML), there remains a need for more comprehensive therapies to prevent AML-associated relapses. To identify new therapeutic strategies for AML, we screened a library of on- and off-patent drugs and identified the antimalarial agent mefloquine as a compound that selectively kills AML cells and AML stem cells in a panel of leukemia cell lines and in mice. Using a yeast genome-wide functional screen for mefloquine sensitizers, we identified genes associated with the yeast vacuole, the homolog of the mammalian lysosome. Consistent with this, we determined that mefloquine disrupts lysosomes, directly permeabilizes the lysosome membrane, and releases cathepsins into the cytosol. Knockdown of the lysosomal membrane proteins LAMP1 and LAMP2 resulted in decreased cell viability, as did treatment of AML cells with known lysosome disrupters. Highlighting a potential therapeutic rationale for this strategy, leukemic cells had significantly larger lysosomes compared with normal cells, and leukemia-initiating cells overexpressed lysosomal biogenesis genes. These results demonstrate that lysosomal disruption preferentially targets AML cells and AML progenitor cells, providing a rationale for testing lysosomal disruption as a novel therapeutic strategy for AML.

In vitro and in vivo studies of the toxic effects of perfluorononanoic acid on rat hepatocytes and Kupffer cells

This study investigated the toxic effects of perfluorononanoic acid (PFNA), a persistent organic pollutant, on rat hepatocytes and Kupffer cells in vitro and in vivo. The results showed that administration of 5μM PFNA increased the viabilities of the hepatocytes and the Kupffer cells. An exposure of 50μM PFNA did not alter the viabilities of both cells, as well as the release of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) from the primary cultured hepatocytes or the hepatocytes co-cultured with Kupffer cells. An exposure of 100μM PFNA only decreased the viability of the hepatocytes. The administration of PFNA changed the hepatocyte expression of several genes related to lipid metabolism in vitro and in vivo. Oil Red O Staining revealed that 5mg PFNA/kg/D treatment lead to dramatic accumulation of lipids in rat liver. At the same dose PFNA damaged hepatocytes histopathologically. Up-regulated expressions of the inflammatory cytokines occurred in the Kupffer cells treated with 50μM PFNA and in the livers of the rat receiving a 5mg PFNA/kg/D treatment. In addition, these cytokines also increased in serum of the rat receiving higher dose of PFNA. In summary, on the one hand, PFNA exposure affected the viability of the hepatocytes, hepatic lipid metabolism and lead to lipid accumulation in liver. On the other hand, for the first time, PFNA exposure was demonstrated to affect the viability of the Kupffer cells as well as their expression of cytokines, which involved in regulation of various liver functions. Therefore, we conclude that both the hepatocyte and the Kupffer cell contribute to the observed hepatotoxicity of PFNA.

Interactions of deoxynivalenol and lipopolysaccharides on cytokine excretion and mRNA expression in porcine hepatocytes and Kupffer cell enriched hepatocyte cultures

The effects of deoxynivalenol (DON) on the mRNA expression of cytokines and inflammation-related genes, as well as the cytokine secretion of porcine hepatocytes and Kupffer cell enriched hepatocyte cultures (co-cultures), were investigated in the absence or presence of LPS. DON and LPS acted in a synergistic manner with regard to a significantly increased mRNA expression of TNF-alpha in hepatocytes exposed to 500 nM or 2000 nM DON, or non-significant increase in co-cultures after 3h of exposure. TNF-alpha supernatant concentrations were increased due to LPS but did not reflect the synergistic effects with DON as observed at mRNA level. IL-6 mRNA in hepatocyte cultures at 6h paralleled the TNF-alpha supernatant pattern at this time point. In co-cultures and hepatocytes, a DON dose dependent induction of IL-6 mRNA was detected in cells not exposed to LPS. Supernatant concentrations of LPS-induced IL-6 were significantly decreased by 2000 nM DON in both types of cell cultures. Also the mRNA expression of the anti-inflammatory IL-10 was increased by DON to various degrees depending on DON-dose, stimulation with LPS and time point of measurement. After 6h, expression of iNOS was only induced by 2000 nM DON, but not in LPS treated cells. Even if mRNA induction was not paralleled by related supernatant concentrations of TNF-alpha, IL-6 and IL-10 under the conditions of the present investigations, it was clearly demonstrated that DON has the potential to provoke and modulate immunological reactions of porcine liver cells.

Metabolism of bromhexine in pig hepatocyte cultures

The metabolism of bromhexine [N-cyclohexyl-N-methyl-2-(2-amino-3,5-di-bromo-benzyl)-amine] was studied using pig hepatocyte cultures and LC/MS/MS techniques. Phase I 'single-step' reactions, i.e. hydroxylation and demethylation occurred the fastest whereas the formation of hydroxylated/demethylated and aminal hydroxylated metabolites, which can be considered as multiple-step reactions, occurred more slowly. Phase II conjugates were detected for all hydroxylated metabolites. The glucuronides of the hydroxylated/demethylated components tended to accumulate. In addition to metabolites known to be formed in vivo, three unknown components related to bromhexine were detected. Two of these metabolites accumulated during incubation. Based on the fragmentation patterns, a possible molecular structure is proposed for these components.

Generation and functional characterization of a clonal murine periportal Kupffer cell line from H-2Kb -tsA58 mice

Murine Kupffer cells (KCs) are heterogeneous and survive only for a short time in vitro. Here, a clonal, murine KC line was generated from transgenic mice, expressing the thermolabile mutant tsA58 of the Simian virus 40 large T antigen under the control of the H-2K(b) promoter. Thirty-three degrees Celsius and 37 degrees C but not 39 degrees C have been permissive for growth of the clone; it required conditioned media from hepatocytes and endothelial cells for proliferation. In contrast to primary cells, the cells of the clone were uniform, survived detachment, and could therefore be analyzed by cytofluorimetry. The clone, as primary KCs, constitutively expressed nonspecific esterase, peroxidase, MOMA-2, BM8, scavenger receptor A, CD14, and Toll-like receptor 4 (TLR4); the antigen-presenting molecules CD40, CD80, and CD1d; and endocytosed dextran-fluorescein isothiocyanate. It lacked complement, Fc receptors, F4/80 marker, and the phagosomal coat protein tryptophan aspartate-containing coat protein (TACO). The clone exhibited CD14- and TLR4/MD2-independent, plasma-dependent lipopolysaccharide (LPS) binding, Escherichia coli and Streptococcus pneumoniae phagocytosis, and LPS- and interferon-gamma-induced NO production but no tumor necrosis factor alpha, interleukin (IL)-6, or IL-10 release. The large size, surface-marker expression, and capacity to clear gram-negative and -positive bacteria indicate that the clone was derived from the periportal, large KC subpopulation. The clone allows molecular studies of anti-infective and immune functions of KCs.

Kupffer cell-mediated cytotoxicity induced by lipopolysaccharide0111:B4 is greater in dogs than in rats and monkeys

To clarify the mechanism of sensitivity to an endotoxin lipopolysaccharide LPS0111:B4, which causes severe liver injury in a variety of animals, we have developed an in vitro assay to measure Kupffer cell-mediated cytotoxicity in the human liver cell line, WRL68. This assay could detect the decrease in Kupffer cell activity induced by gadolinium chloride (GdCl3), which is an inhibitor in Kupffer cells. Among Kupffer cells derived from dogs, rats, and monkeys, LPS-activated canine Kupffer cells exhibited remarkably high cytotoxicity against WRL68 cells. This species difference is correlated with a species difference in the lethality of LPS0111:B4. Additionally, the conditioned medium of LPS-activated canine Kupffer cells was also cytotoxic to WRL68 cells. To identify the mediators of this cytotoxicity, we measured the accelerated release of interleukin-1 beta, and interleukin-6 from Kupffer cells on stimulation with LPS0111:B4. From the correlation of the response to LPS0111:B4, interleukin-1 beta and interleukin-6 are considered to be responsible for the canine Kupffer cell-mediated cytotoxicity of LPS0111:B4.

Suppression of the acute inflammatory response of porcine alveolar- and liver macrophages

During infection and inflammation drug disposition and hepatic metabolism are markedly affected in mammals. Pro-inflammatory mediators play an important role in the suppression of (cytochrome-P450-mediated) drug metabolism. Inflammatory mediators like cytokines, nitric oxide (NO), reactive oxygen species (ROS) and eicosanoids are released by activated macrophages from various sources, including liver and lung. It was the aim of this study to investigate ways to suppress the activation of macrophages during the onset of the inflammatory cascade. Therefore porcine lung and liver macrophages were isolated, and incubated with lipopolysaccharide (LPS) to initiate an acute inflammatory response, represented by the release of high amounts of tumour necrosis factor-alpha (TNF-alpha) into the culture medium. Additionally the primary macrophages were coincubated with phosphodiesterase-IV-(PDE-IV)-inhibitors or beta-adrenoceptor agonists that in previous studies demonstrated strong suppressive effects on TNF-alpha release. Especially the beta-adrenoceptor agonists showed to be very potent TNF-alpha suppressants, which indicates that the beta-adrenoceptor might be an interesting target for suppression of activation of macrophages. This was strengthened by the observation that the beta-adrenoceptor expression was not altered during the onset of the inflammatory cascade.