Isolation Of Hepatocytes Research Articles

Preapoptotic Cell Stress Response of Primary Hepatocytes

Primary hepatocytes are an important in vitro model for studying metabolism in man. Caspase-9 and Bcl-2-associated X protein (Bax) are regulators of the apoptotic pathway. Here we report on the translocation of procaspase-9 and Bax from cytoplasm to nuclei as well as on dispersion of mitochondria; these processes occur after isolation of primary hepatocytes. The observed changes appear similar to those at the beginning of apoptosis; however, the isolated hepatocytes are not apoptotic for the following reasons: (1) cells have a normal morphology and function; (2) the mitochondria are energized; (3) there is no apoptosis unless it is induced by, e.g., staurosporine or nodularin. Staurosporine does not trigger apoptosis through activation of caspase-9, as its activity is detected later than that of caspase-3. We propose that the translocation of procaspase-9 and Bax into the nuclei reduces the ability to trigger apoptosis through the intrinsic apoptotic pathway. The shifts of procaspase-9 and Bax are reversible in the absence of the apoptotic trigger; the spontaneous reversion was confirmed experimentally for procaspase-9, whereas Bax shifted from the nuclei to the cytosol and mitochondria after the initiation of apoptosis. To distinguish this process from apoptosis, we call it preapoptotic cell stress response. It shares some features with apoptosis; however, it is reversible and apoptosis has to be induced in addition to this process. Knowledge on preapoptotic cell stress response is important for assessing the quality of the cells used in cell therapies, in regenerative medicine, and of those used for modeling metabolic processes.

Trasplante celular hepático. Aspectos técnicos y metodológicos

Hepatic cell transplantation consists of grafting already differentiated cells such as hepatocytes. Human hepatocytes are viable and functionally active. Liver cell transplantation is carried out by means of a 3-step method: isolation of hepatocytes from donor liver rejected for orthotopic transplantation, preparing a cell suspension for infusion and, finally, hepatocytes are implanted into the recipient. There are established protocols for the isolation of human hepatocytes from unused segments of donor livers, based on collagenase digestion of cannulated liver tissue at 37 °C. The hepatocytes can be used fresh or cryopreserved. Cryopreservation of isolated human hepatocytes would then be available for planned use. In cell transplant, the important aspects are: infusion route, number of cells, number of infusions and viability of the cells. The cells are infused into the patient through a catheter inserted via portal vein or splenic artery. Liver cell transplantation allows liver tissue to be used that would, otherwise, be discarded, enabling multiple patients to be treated with hepatocytes from a single tissue donor.

Hepatic cell transplantation. Technical and methodological aspects

Hepatic cell transplantation consists of grafting already differentiated cells such as hepatocytes. Human hepatocytes are viable and functionally active.Liver cell transplantation is carried out by means of a 3-step method: isolation of hepatocytes from donor liver rejected for orthotopic transplantation, preparing a cell suspension for infusion and, finally, hepatocytes are implanted into the recipient. There are established protocols for the isolation of human hepatocytes from unused segments of donor livers, based on collagenase digestion of cannulated liver tissue at 37°C.The hepatocytes can be used fresh or cryopreserved. Cryopreservation of isolated human hepatocytes would then be available for planned use.In cell transplant, the important aspects are: infusion route, number of cells, number of infusions and viability of the cells. The cells are infused into the patient through a catheter inserted via portal vein or splenic artery.Liver cell transplantation allows liver tissue to be used that would, otherwise, be discarded, enabling multiple patients to be treated with hepatocytes from a single tissue donor.

Porcine hepatocyte isolation and reversible immortalization mediated by retroviral transfer and site-specific recombination

To develop a hepatocyte cell line, we immortalized primary porcine hepatocytes with a retroviral vector SSR#69 containing the Simian Virus 40 T antigen (SV40Tag). We first established a method of porcine hepatocyte isolation with a modified four-step retrograde perfusion technique. Then the porcine hepatocytes were immortalized with retroviral vector SSR#69 expressing SV40T and hygromycin-resistance genes flanked by paired loxP recombination targets. SV40T cDNA in the expanded cells was subsequently excised by Cre/LoxP site-specific recombination. The resultant hepatocytes with high viability (97%) were successfully immortalized with retroviral vector SSR#69. One of the immortalized clones showed the typical morphological appearance, TJPH-1, and was selected by clone rings and expanded in culture. After excision of the SV40T gene with Cre-recombinase, cells stopped growing. The population of reverted cells exhibited the characteristics of differentiated hepatocytes. In conclusion, we herein describe a modified method of hepatocyte isolation and subsequently established a porcine hepatocyte cell line mediated by retroviral transfer and site-specific recombination.

A Simple Isolation and Cryopreservation Method for Adult Human Hepatocytes

The objective of this study was to establish a stable method of isolation, culture and cryopreservation of adult primary hepatocytes to provide potential hepatocyte resources for the treatment of acute and chronic liver diseases by hepatocyte transplantation and bioartificial liver support systems, and for the use of hepatocytes as an in vitro model of the liver. Adult hepatocytes of 20 separate donors were isolated with a two-step extracoporeal collagenase perfusion technique. Seven preincubation time points (2h, 6h, 12h, 24h, 36h, 48h and 72h) were selected, then the hepatocytes were transferred to HepatoZYME-SFM medium containing 10% FBS and 10% DMSO, and were immediately put into an isopropanol progressive freezing container at -80 degrees C overnight and immersed in liquid nitrogen the next day. During the postthawing culture period, viability, plating efficiency, albumin secretion and urea synthesis were analyzed. The viability and plating efficiency of hepatocytes after partial hepatectomy using two-step extracorporeal collagenase perfusion technique were 75.0+/-4.6% and 72.0+/-6.0% respectively. Preincubation at 4? for 12 hours or 24 hours proved to be the optimal time at which the albumin secretion was higher than at other time points (p<0.05). Compared to the immediate cryopreservation groups (IC), we also found significant improvement in viability (61.4+/-4.8%/62.0+/-5.6% vs. 53.4+/-4.2%, p<0.05), plating efficiency (63.2+/-5.8%/62.6+/-3.6% vs. 55.2+/-4.6%, p<0.05), albumin secretion and urea synthesis (p<0.05) at these time points. The two-step extracorporeal collagenase perfusion technique after partial hepatectomy provides a novel, simple, and reliable method for hepatocyte isolation. The results of the present study suggest that recovery of human hepatocytes after isolation preincubation at 4 degrees C for 12 hours to 24 hours prior to cryopreservation can obtain hepatocytes ideal for use in pharmacotoxicology, bioartificial liver and cell therapy research purposes.

Experience of Microbiological Screening of Human Hepatocytes for Clinical Transplantation

Hepatocyte transplantation is being used in patients with liver-based metabolic disorders and acute liver failure. Hepatocytes are isolated from unused donor liver tissue under GMP conditions. Cells must be free of microbiological contamination to be safe for human use. The experience of microbiological screening during 72 hepatocyte isolation procedures at one center is reported. Samples were taken at different stages of the process and tested using a blood culture bottle system and Gram stain. Bacterial contamination was detected in 37.5% of the UW organ preservative solutions used to transport the liver tissue to the Cell Isolation Unit. After tissue processing the contamination was reduced to 7% overall in the final hepatocyte product, irrespective of the presence of initial contamination of the transport solution. The most common organisms recovered were coagulase-negative staphylococci, a skin commensal. A total of 41 preparations of fresh or cryopreserved hepatocytes were used for cell transplantation in children with liver-based metabolic disorders without any evidence of sepsis due to infusion of hepatocytes. In conclusion, the incidence of bacterial contamination of the final product was low, confirming the suitability of the organs used, hepatocyte isolation procedure, and the environmental conditions of the clean room.

Evaluation of a carp primary hepatocyte culture system for screening chemicals for oestrogenic activity

The presence of endocrine disrupting chemicals (EDCs) in the environment has driven the development of screening and testing assays to both identify chemicals with hormonal activity and evaluate their potential to cause adverse effects. As the number of animals used for research and regulatory purposes rises, and set against a desire to reduce animal testing, there is increased emphasis on the development and application of in vitro techniques to evaluate chemical risks to the environment. Induction of vitellogenin (VTG) in isolated fish liver cells has been used successfully to identify a wide range of EDCs, including both natural and synthetic oestrogens and a variety of other xenoestrogens. However, the vitellogenic response reported for hepatocytes in culture has been shown to vary widely, making comparisons between studies difficult. The work presented in this paper explored the variability of the vitellogenic response in primary cultures of common carp ( Cyprinus carpio) hepatocytes following exposure to the model oestrogenic compound, 17β-oestradiol (E2). As expected, variability in the vitellogenic response was observed, both in terms of the sensitivity and magnitude of VTG induction, for hepatocytes isolated from different fish. An apparent difference was observed in the response of isolated hepatocytes based on the sex of the donor fish; maximum levels of E2-stimulated VTG synthesis in hepatocytes derived from females appeared higher (1962 ng mL −1 ± 487 [ n = 9] compared with 1194 ng mL −1 ± 223 for hepatocytes from males [ n = 9]) and EC 50 values lower (1.61 ± 0.4 μM E2 for females and 2.12 ± 0.2 μM E2 for males). However, these differences were not statistically significant, likely in part due to the variation observed in the vitellogenic response. In particular, hepatocytes derived from female fish showed more variation than their male counterparts (the co-efficient of variation for females was 77% compared to 28% for males). Despite the variation observed in the vitellogenic response between different cultures, data from the different donor fish could be compared by standardising responses relative to the maximum VTG induction in each culture following exposure to E2. Adopting this approach in the future will allow for data from different hepatocyte cultures and from donor fish of different sexes, age and stage of maturity to be compared with greater consistency. Measurement of vtg mRNA expression was relatively more sensitive to the oestrogenic effects of E2 exposure than measurement of VTG protein (the LOEC at the transcriptome level was 10-fold lower [0.01 μM E2] than at the protein level [0.1 μM E2]) and changes in vtg mRNA expression showed less variation between individual hepatocyte isolations. Measurement of vtg mRNA in the hepatocyte culture system therefore may offer the most sensitive and consistent option for the screening of chemicals with oestrogenic activity in fish primary hepatocyte cultures.

A modified method of isolation and primary culture of rat hepatocytes

Objective To explore and modify the method of isolation and primary culture of rat hepatocytes. Methods Six-well plates were pre-coated with collagen m about 24 h before use. Rat hepa- tocytes were isolated by a modified two-step collagenase perfusion technique in situ, seeded in eligible den-sity,and cultured in RPMI 1640 medium containing 10% fetal bovine serum. The yield,viability,attach-ment and growth of hepatocytes were observed to estimate the feasibility. Results The isolation time of rat hepatocytes was shortened obviously. One-third of collagenase IV was saved. About(1.81±0.65)x 108 hepatytes were obtained from every rat,and the viability was (87.46±6.90 )%. The cells attached to the plates about 4 h after seeded ,grew well and had a two-to three-week survival. Conclusion The modi-fied method is economical,and less labor and time for isolation and culture of primary rat hepatocytes. The yield, viability and attachment rate are high enough to be used for various experiments. Key words: Hepatocytes; Collagenases ; Cell culture

S26948, a new specific peroxisome proliferator activated receptor gamma modulator improved in vivo hepatic insulin sensitivity in 48 h lipid infused rats

We examined whether S26948, a new specific peroxisome proliferator activated receptor γ modulator prevented insulin-resistance induced by a 48 h intralipid-infusion in normal rat (IL rats). The effect of S26948 (30 mg/kg) was compared to rosiglitazone (10 mg/kg). Rats were catheterized in the right jugular vein 4 days before the beginning of the 48 h lipid or saline infusions. Animals were intraperitoneally injected once daily with vehicle, S26948 or rosiglitazone. At the end of the infusion the rats underwent either a glucose tolerance test or a euglycemic–hyperinsulinemic clamp. Finally isolation and incubation of hepatocytes in another series of rats were performed. Intralipid infusion leads to a 4-fold increase in plasma free fatty acid concentration compared to controls (C). Both S26948 and rosiglitazone decreased plasma free fatty acid concentration in IL rats compared to vehicle treated IL rats. Glucose-induced insulin secretion was significantly increased in IL compared to C and was associated with insulin resistance. Both S26948 and rosiglitazone treatments normalized glucose-induced insulin secretion and improved insulin action in IL rats. However, S26948 specifically improved hepatic insulin sensitivity whereas rosiglitazone improved both hepatic insulin sensitivity and insulin-stimulated glucose utilization. Finally, studies on isolated hepatocytes showed differential effect of both compounds on gene expression of key enzymes of glucose metabolism. Our data show that non thiazolidinedione S26948 may represent an alternative way for the management of dysregulated hepatic insulin sensitivity.

Recent advances in techniques for isolation and culture of primary hepatocytes

Recent advances in techniques for isolation and culture of primary hepatocytes

Improved Survival of Fulminant Liver Failure by Transplantation of Microencapsulated Cryopreserved Porcine Hepatocytes in Mice

The aim of this study was to establish hepatocyte isolation in pigs, and to evaluate function of isolated hepatocytes after encapsulation, cryopreservation, and transplantation (Tx) in a mouse model of fulminant liver failure (FLF). After isolation, porcine hepatocytes were microencapsulated with alginate-poly-L-Lysine-alginate membranes and cryopreserved. In vitro, albumin production of free and encapsulated hepatocytes were measured by enzyme linked-immunoadsorbent assay. In vivo, encapsulated hepatocytes were transplanted into different groups of mice with FLF and the following experimental groups were performed: group 1, Tx of empty capsules; group 2, Tx of free primary porcine hepatocytes; group 3, Tx of fresh encapsulated porcine hepatocytes; group 4, Tx of cryopreserved encapsulated porcine hepatocytes. In vitro, fresh or cryopreserved encapsulated porcine hepatocytes showed a continuous decreasing metabolic function over 1 week (albumin and urea synthesis, drug catabolism). In vivo, groups 1 and 2 showed similar survival (18% and 25%, respectively, p > 0.05). In groups 3 and 4, Tx of fresh or cryopreserved encapsulated porcine hepatocytes significantly increased survival rate to 75% and 68%, respectively (p < 0.05). Primary porcine hepatocytes maintained metabolic functions after encapsulation and cryopreservation. In mice with FLF, Tx of encapsulated xenogeneic hepatocytes significantly improved survival. These results indicate that porcine hepatocytes can successfully be isolated, encapsulated, stored using cryopreservation, and transplanted into xenogeneic recipients with liver failure and sustain liver metabolic functions.

Insulin and epidermal growth factor suppress basal glucose-6-phosphatase catalytic subunit gene transcription through overlapping but distinct mechanisms.

The G6Pase (glucose-6-phosphatase catalytic subunit) catalyses the final step in the gluconeogenic and glycogenolytic pathways, the hydrolysis of glucose-6-phosphate to glucose. We show here that, in HepG2 hepatoma cells, EGF (epidermal growth factor) inhibits basal mouse G6Pase fusion gene transcription. Several studies have shown that insulin represses basal mouse G6Pase fusion gene transcription through FOXO1 (forkhead box O1), but Stoffel and colleagues have recently suggested that insulin can also regulate gene transcription through FOXA2 (forkhead box A2) [Wolfrum, Asilmaz, Luca, Friedman and Stoffel (2003) Proc. Natl. Acad. Sci. 100, 11624-11629]. A combined GR (glucocorticoid receptor)-FOXA2 binding site is located between -185 and -174 in the mouse G6Pase promoter overlapping two FOXO1 binding sites located between (-188 and -182) and (-174 and -168). Selective mutation of the FOXO1 binding sites reduced the effect of insulin, whereas mutation of the GR/FOXA2 binding site had no effect on the insulin response. In contrast, selective mutation of the FOXO1 and GR/FOXA2 binding sites both reduced the effect of EGF. The effect of these mutations was additive, since the combined mutation of both FOXO1 and GR/FOXA2 binding sites reduced the effect of EGF to a greater extent than the individual mutations. These results suggest that, in HepG2 cells, GR and/or FOXA2 are required for the inhibition of basal G6Pase gene transcription by EGF but not insulin. EGF also inhibits hepatic G6Pase gene expression in vivo, but in cultured hepatocytes EGF has the opposite effect of stimulating expression, an observation that may be explained by a switch in ErbB receptor sub-type expression following hepatocyte isolation.

Optimization of the isolation and cultivation of Cyprinus carpio primary hepatocytes

The aquatic environment is affected by numerous chemical contaminants. There is an increasing need to identify these chemicals and to evaluate their potential toxicity towards aquatic life. In this research we optimized techniques for primary cell culture of Cyprinus carpio hepatocytes as one adjunct model for ecotoxicological evaluation of the potential hazards of xenobiotics in the aquatic environment. In this study, Cyprinus carpio hepatocytes were isolated by mechanical separation, two-step collagenase perfusion, and pancreatin digestion. The hepatocytes or parenchymal cells could be separated from cell debris and from non-parenchymal cells by low-speed centrifugation (Percoll gradient centrifugation). The harvested hepatocytes were suspended in DMEM, M199 (cultured in 5% CO(2)), or L-15 (cultured without 5% CO(2)) medium then cultured at 17, 27, or 37 degrees C. Cell yield was counted by use of a hemocytometer, and the viability of the cells was assessed by use of the Trypan blue exclusion test. Results from these studies showed that the best method of isolation was pancreatin digestion (the cell yield was 2.7 x 10(8) per g (liver weight) and the viability was 98.4%) and the best medium was M199 (cultured in 5% CO(2)) or L-15 (cultured without 5% CO(2)). The optimum culture temperature was 27 degrees C. The primary hepatocytes culture of Cyprimus carpio grew well and satisfied requirements for most toxicological experiments in this condition.

Induction of paraoxonase 1 and apolipoprotein A-I gene expression by aspirin

Low-dose aspirin therapy has become a standard in the treatment of cardiovascular diseases. Aspirin has been shown to inhibit atherosclerosis in mouse models. To determine the mechanisms by which aspirin might inhibit atherosclerosis, we incubated HEPG2 cells and rat primary hepatocytes with aspirin or salicylic acid and noted an increase in paraoxonase 1(PON1) activity in the medium, together with an induction of PON1 and apolipoprotein A-I (apoA-I) gene expression. Mice treated with aspirin also showed a 2-fold increase in plasma PON1 activity and a significant induction of both PON1 and apoA-I gene expression in the liver. The induction of the PON1 gene in cell culture was accompanied by an increase in arylhydrocarbon receptor (AhR) gene expression. Accordingly, aspirin treatment of AhR(-/-) animals failed to induce PON1 gene expression. We previously suggested that aspirin might be hydrolyzed by serum PON1, which could account for its short plasma half-life of 10 min. Taken together with the current studies, we suggest that the antiatherosclerotic effects of aspirin might be mediated by its hydrolytic product salicylate and that the induction of PON1 and apoA-I might be important in the cardioprotective effects of aspirin.

Isolation of murine hepatocytes to measure protein synthesis ex vivo upon stimulation

Isolation of murine hepatocytes to measure protein synthesis ex vivo upon stimulation

Evaluation of Drug-Metabolizing and Functional Competence of Human Hepatocytes Incubated under Hypothermia in Different Media for Clinical Infusion

Hepatocyte transplantation has been proposed as a method to support patients with liver insufficiency. Key factors for clinical cell transplantation to progress is to prevent hepatocyte damage, loss of viability and cell functionality, factors that depend on the nature of the tissue used for isolation to a large extent. The main sources of tissue for hepatocyte isolation are marginal livers that are unsuitable for transplantation, and segments from reduced cadaveric grafts. Hepatocellular transplantation requires infusing human hepatocytes in suspension over a period of minutes to hours. The beneficial effect of hypothermic preservation of hepatocytes in infusion medium has been reported, but how critical issues towards the success of cell transplantation, such as the composition of infusion medium and duration of hepatocyte storage will affect hepatocyte quality for clinical cell infusion has not been systematically investigated. Infusion media composition is phosphate-buffered saline containing anticoagulants and human serum albumin. The supplementation of infusion media with glucose or N-acetyl-cystein, or with both components at the same time, has been investigated. After isolation, hepatocytes were suspended in each infusion medium and a sample at the 0 time point was harvested for cell viability and functional assessment. Thereafter, cells were incubated in different infusion media agitated on a rocker platform to simulate the clinical infusion technique. The time course of hepatocyte viability, funtionality (drug-metabolizing enzymes, ureogenic capability, ATP, glycogen, and GSH levels), apoptosis (caspase-3 activation), and attachment and monolayer formation were analyzed. The optimal preservation of cell viability, attaching capacity, and functionality, particularly GSH and glycogen levels, as well as drug-metabolizing cytochrome P450 enzymes, was found in infusion media supplemented with 2 mM N-acetyl-cystein and 15 mM glucose.

Hepatocyte-specific c-Met Deletion Disrupts Redox Homeostasis and Sensitizes to Fas-mediated Apoptosis

The hepatocyte growth factor and its receptor c-Met direct a pleiotropic signal transduction pathway that controls cell survival. We previously demonstrated that mice lacking c-Met (Met-KO) in hepatocytes were hypersensitive to Fas-induced liver injury. In this study, we used primary hepatocytes isolated from Met-KO and control (Cre-Ctrl) mice to address more directly the protective effects of c-Met signaling. Loss of c-Met function increased sensitivity to Fas-mediated apoptosis. Hepatocyte growth factor suppressed apoptosis in Cre-Ctrl but not Met-KO hepatocytes concurrently with up-regulation of NF-kappaB and major antiapoptotic proteins Bcl-2 and Bcl-xL. Intriguingly, Met-KO hepatocytes exhibited intrinsic activation of NF-kappaBas well as Bcl-2 and Bcl-xL. Furthermore, unchallenged Met-KO cells displayed oxidative stress as evidenced by overproduction of reactive oxygen species, which was associated with greater NADPH and Rac1 activities, was blocked by the known NADPH oxidase inhibitors, and was paralleled by increased lipid peroxidation and reduced glutathione (GSH) content. N-Acetylcysteine, an antioxidant and GSH precursor, significantly reduced Jo2-induced cell death. Conversely, the GSH-depleting agent buthionine sulfoximine completely abolished the protective effects of N-acetylcysteine in Met-KO hepatocytes. In conclusion, genetic inactivation of c-Met in mouse hepatocytes caused defects in redox regulation, which may account for the increased sensitivity to Fas-induced apoptosis and adaptive up-regulation of NF-kappaB survival signaling. These data provide evidence that intact c-Met signaling is a critical factor in the protection against excessive generation of endogenous reactive oxygen species.

Cold Preservation of the Liver With Oxygenation by a Two-Layer Method

The two-layer method (TLM) has recently been found to be superior to simple cold storage in University of Wisconsin (UW) solution as a means of pancreas preservation for islet transplantation. In this study, we investigated whether TLM would result in better hepatocyte function over UW cold storage and if it could be applied to hepatocyte transplantation. Hepatocytes from male Sprague Dawley rat livers were isolated and divided into three groups: a non-preservation group (group 1), a 10-h preservation group (group 2), and a 24-h preservation group (group 3). Groups 2 and 3 were then divided into three subgroups: a group preserved by the TLM (subgroup a), a group preserved in UW solution (subgroup b), and a group preserved in water (subgroup c). Isolated hepatocytes were evaluated for cell yield, viability, and adenosine triphosphate level after preservation. Hepatocytes were either cultured or transplanted. Although no differences in cell yield or morphological findings were observed between any of the groups, TLM significantly improved hepatocyte viability and adenosine triphosphate levels in comparison with UW cold storage. Albumin production or urea synthesis were significantly higher in subgroup 3a than in subgroup 3b at almost all time points. Surprisingly, after hepatocyte transplantation, the serum albumin level in subgroup 2a was significantly higher than in subgroup 2b at every time point. The results of this study demonstrated that liver preservation by the TLM before hepatocyte isolation might be beneficial and will be useful in the field of hepatotocyte transplantation.

Isolation of Primary Human Hepatocytes After Partial Hepatectomy: Criteria for Identification of the Most Promising Liver Specimen

Demands for primary human hepatocytes are continuously increasing, while supply is insufficient due to limited cell sources. To improve cell availability, the present study investigates the influence of donor liver characteristics on the outcome of hepatocyte isolation from surgically removed liver tissue (n = 50). Hepatocytes were isolated from liver specimens using a standardized two-step collagenase perfusion technique. The patient's sex, previous chemotherapy, or histopathology have shown no influence. Donor age significantly affected the isolation outcome, but was not found suitable for predicting cell yields. Preoperative blood parameters did not correlate with cell yield, although cell function was affected: total protein, albumin synthesis, and cell viability were significantly decreased for serum gamma-glutamyl-transferase (GGT) levels >60 U/L. Specimens from patients with benign diseases gave significantly higher cell yields than tissue removed due to secondary and primary tumors, respectively. The indication for surgery is a valuable basis for identifying the most yielding specimens. Hepatocytes from donors with high GGT levels appear to show reduced functional properties.

Cell Type–Dependent Pro- and Anti-Inflammatory Role of Signal Transducer and Activator of Transcription 3 in Alcoholic Liver Injury

Signal transducer and activator of transcription 3 (STAT3) is known to be activated in human alcoholic liver disease, but its role in the pathogenesis of alcoholic liver injury remains obscure. The role of STAT3 in alcoholic liver injury was investigated in hepatocyte-specific STAT3 knockout (H-STAT3KO) mice and macrophage/neutrophil-specific STAT3 KO (M/N-STAT3KO) mice. Alcoholic liver injury was achieved by feeding mice a liquid diet containing 5% ethanol for up to 8 weeks. Compared with wild-type mice, feeding H-STAT3KO mice with an ethanol-containing diet induced greater hepatic steatosis, hypertriglyceridemia, and hepatic expression of lipogenic genes (sterol regulatory element-binding protein, fatty acid synthase, acetyl-CoA carboxylase-1, and stearoyl-CoA desaturase 1), but less inflammation and lower expression of hepatic proinflammatory cytokines. In contrast, ethanol-fed M/N-STAT3KO mice showed more hepatic inflammation, worse injury, and increased hepatic expression of proinflammatory cytokines compared with wild-type mice. Kupffer cells isolated from ethanol-fed H-STAT3KO mice produced similar amounts of reactive oxygen species and tumor necrosis factor alpha, whereas Kupffer cells from M/N-STAT3KO mice produced more reactive oxygen species and tumor necrosis factor alpha compared with wild-type controls. These findings suggest that STAT3 regulates hepatic inflammation in a cell type-dependent manner during alcoholic liver injury: STAT3 in hepatocytes promotes whereas STAT3 in macrophages/Kupffer cells suppresses inflammation. In addition, activation of hepatocellular STAT3 ameliorates alcoholic fatty liver via inhibition of sterol regulatory element-binding protein 1c expression.