Interleukin-6 inhibits oxidative injury and necrosis after extreme liver resection

Evaluating the Effects of Cryopreservation on the Viability and Gene Expression of Porcine-Ear-Skin Fibroblasts

Owing to the inherent heterogeneity and plasticity of fibroblasts, they are considered as the conventional biological resources for basic and clinical medical research. Thus, it is essential to generate knowledge about the establishment of fibroblast cultures and the effects of cryopreservation processes on their biological characteristics. Since the pig (Sus scrofa) possesses numerous genetic, physiological, and anatomical similarities with humans, porcine fibroblasts are naturally regarded as useful analogues of human fibroblasts. Nonetheless, less attention has been given to the alterations in viability and gene expression of cryopreserved porcine fibroblasts. In this study, we aimed to obtain fibroblasts from porcine ear skin and evaluate the effects of cryopreservation on the cell survival, proliferation, and gene expression profiles of the fibroblasts by trypan-blue-staining assay, Cell Counting kit-8 (CCK-8) assay, and RNA-sequencing analysis, respectively. Our results suggested that morphologically stable fibroblast cultures can be constructed from pig-ear skin. The post-thaw survival rate of the cryopreserved fibroblasts at 0 h and 24 h was over 90%. The proliferative activity of the cryopreserved fibroblasts was similar to that of the non-cryopreserved fibroblasts after 7 days of in vitro culture, which suggested that cryopreservation did not influence the viability. The RNA-sequencing analysis indicated that this should be attributed to the 867 differentially expressed genes (DGEs) identified, which are involved in molecular process related to cell recovery and survival after cryo-stimulation. In addition, eight important DEGs BMP2, GDF15, EREG, AREG, HBEGF, LIF, IL-6, and HOX-7 could potentially be applied to improve the efficiency of fibroblast cryopreservation, but comprehensive and systematic studies on understanding the underlying mechanisms responsible for their modulatory roles are urgently needed.

Serine proteases mediate leukocyte recruitment and hepatic microvascular injury in the acute phase following extended hepatectomy

OBJECTIVE

Post-hepatectomy liver failure (PHLF) is the main limitation of extended liver resection. The molecular mechanism and the role of leukocytes in the development of PHLF remain to be unveiled. We aimed to address the impact of serine proteases (SPs) on the acute phase after liver resection by intravitally analyzing leukocyte recruitment and changes in hemodynamics and microcirculation of the liver.

METHODS

C57BL/6 mice undergoing 60% partial hepatectomy were treated with aprotinin (broad-spectrum SP inhibitor), tranexamic acid (plasmin inhibitor), or vehicle. Sham-operated animals served as controls. In vivo fluorescence microscopy was used to quantify leukocyte-endothelial interactions immediately after, as well as 120 min after partial hepatectomy in postsinusoidal venules, along with measurement of sinusoidal perfusion rate and postsinusoidal shear rate. Recruitment of leukocytes, neutrophils, T cells, and parameters of liver injury were assessed in tissue/blood samples.

RESULTS

Leukocyte recruitment, sinusoidal perfusion failure rate, and shear rate were significantly increased in mice after 60% partial hepatectomy compared to sham-operated animals. The inhibition of SPs or plasmin significantly attenuated leukocyte recruitment and improved the perfusion rate in the remnant liver. ICAM-1 expression and neutrophil recruitment significantly increased after 60% partial hepatectomy and were strongly reduced by plasmin inhibition.

CONCLUSIONS

Endothelial activation and leukocyte recruitment in the liver in response to the increment of sinusoidal shear rate were hallmarks in the acute phase after liver resection. SPs mediated leukocyte recruitment and contributed to the impairment of sinusoidal perfusion in an ICAM-1-dependent manner in the acute phase after liver resection.

Antioxidant effects of Se-glutathione peroxidase in alcoholic liver disease

Oxidative damage induced by ethanol and its metabolites is one of the factors that fuels the development of alcoholic liver disease (ALD). Selenium (Se) is an effective cofactor for glutathione peroxidase (GPx), and has antioxidant effects that improve ALD. In patients with ALD, ethanol-induced oxidative damage inhibits the synthesis of related Se-containing proteins such as: selenoprotein P (Sepp1), albumin (ALB), and GPx in the liver, thus decreasing the overall Se level in patients. Both Se deficiency and excess can affect the expression of GPx, resulting in damage to the antioxidant defense system. This damage enhances oxidative stress by increasing the levels of reactive oxygen species (ROS) in the body, which aggravates the inflammatory response, lipid metabolism disorder, and lipid peroxidation and worsens ALD symptoms. A cascade of oxidative damages caused by ALD will deplete selenium deposition in the body, stimulate the expression of Gpx1, Sepp1, and Gpx4, and thus mobilize systemic selenoproteins, which can restore GPx activity in the hepatocytes of ALD patients, reduce the levels of reactive oxygen species and alleviate oxidative stress, the inflammatory response, lipid metabolism disorder, and lipid peroxidation, thus helping to mitigate ALD. This review provides a reference for future ALD studies that evaluate the regulation of Se levels and contributes to studies on the potential pathological mechanisms of Se imbalance in ALD.

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha protects a fibrotic liver from partial hepatectomy-induced advanced liver injury through regulating cell cycle arrest

Background

A fibrotic liver may have an impaired regenerative capacity. Because liver transplantation is donor limited, understanding the regenerative ability of a fibrotic liver is important.

Methods

A two‐thirds partial hepatectomy (PH) was performed in C57Bl/6 mice with or without carbon tetrachloride (CCl₄) treatment. Liver regeneration in the fibrotic liver after PH was assessed by the intrahepatic expression of the cell cycle regulators p53, p21, cyclin D1, c‐Fos and CDK2 using Western blot analysis. In addition, the expression of PGC‐1α and the cell proliferation‐related proteins PCNA and phosphate histone H3 was determined by Western blot and immunohistochemical staining analyses. Histone epigenetic modification of the PGC‐1α promoter was investigated through chromatin immunoprecipitation (ChIP) and reverse transcription–quantitative polymerase chain reaction (RT‐qPCR) assays. The impact of PGC‐1α on liver regeneration after PH was further evaluated in PGC‐1α‐knockout mice.

Results

A decreased expression of PGC‐1α and liver regeneration‐related genes in the fibrotic liver was detected after a PH. Histone acetylation at the PGC‐1α promoter led to increases in PGC‐1α expression and the survival rate in the fibrotic group after a PH. PGC‐1α‐mediated liver regeneration was further demonstrated in PGC‐1α^f/falbcre^+/0 mice.

Conclusion

Targeting PGC‐1α may represent a strategy to improve the treatment of PH in patients with liver fibrosis.

Child-Turcotte-Pugh Score as a Predictive Factor for Long-Term Survival After Repeat Hepatectomy for Recurrent Liver Metastases of Colorectal Cancer

Objective

We aimed to evaluate the changes in liver function after repeat hepatectomy and their relationship with survival of patient with colorectal cancer.

Summary of Background Data

Repeat hepatectomy has been accepted as an effective treatment for recurrent liver metastases; however, how repeat hepatectomy changes the liver function during the follow-up period is not well understood.

Methods

Data regarding patients underwent R0 resections at initial hepatectomy for colorectal cancer with liver metastasis from 2012 to 2017 were retrospectively reviewed. Patients were divided into groups according to the total number of hepatectomies. Overall survival and Child-Turcotte-Pugh score after hepatectomy were analyzed.

Results

Fifty-three patients underwent single hepatectomy and 37 patients underwent repeat hepatectomy. There was no significant difference in the overall survival rates between the 2 groups. At 27 months after the initial hepatectomy, mean Child-Turcotte-Pugh scores of patients with repeat hepatectomy started to become statistically higher than those of patients with single hepatectomy. Overall survival of patients who survived after 27 months from the initial hepatectomy showed a statistical difference between the 2 groups. The total number of liver metastases ≥ 4 and Child-Turcotte-Pugh score ≥ 6 at 27 months after the initial hepatectomy were significant risk factors for overall survival of patient who survived after 27 months from the initial hepatectomy.

Conclusions

Liver function after repeat hepatectomy can be deteriorated after a long-term period. Careful approach and continuous assessment of the liver function after hepatectomy are necessary to maintain long-term survival after repeat hepatectomy.

Human umbilical cord-derived mesenchymal stem cells affect urea synthesis and the cell apoptosis of human induced hepatocytes by secreting IL-6 in a serum-free co-culture system

BACKGROUND

Bioartificial livers (BALs) are emerging as a potential supportive therapy for liver diseases. However, the maintenance of hepatocyte function and viability is a major challenge. Mesenchymal stem cells (MSCs) have attracted extensive attention for providing trophic support to hepatocytes, but only few studies have explored the interaction between human MSCs and human hepatocytes, and very little is known about the underlying molecular mechanisms whereby MSCs affect hepatocyte function, especially in serum-free medium (SFM).

CONCLUSION

The SFM co-culture strategy showed major advantages in maintaining hiHep function and viability, which is of great significance for the clinical application of hiHeps in BALs. This article is protected by copyright. All rights reserved.

SHMT2 Promotes Liver Regeneration Through Glycine-activated Akt/mTOR Pathway

BACKGROUND

The development of liver transplantation (LT) is increasingly being limited by the unavailability of liver grafts. Unique regenerative capacity of liver in response to injuries makes living-donor liver transplantation (LDLT) a feasible strategy to meet clinical demands. Serine hydroxymethyl-transferase 2 (SHMT2) serves as the key enzyme in the biosynthesis of glycine. Glycine affects the activity of mammalian target of rapamycin (mTOR), which is important for cellular growth and proliferation. In this study, the effects of SHMT2 on mouse liver regeneration were investigated using a classical partial hepatectomy (PH) model.

METHODS

In vivo, PH was performed on mice with or without knockdown of SHMT2. In vitro, SHMT2 was overexpressed in primary hepatocytes, which were cultured in customized Dulbecco's modified eagle media and LY294002 (an Akt inhibitor). Relevant indexes of liver regeneration, cell proliferation, and Akt/mTOR signal pathways were analyzed.

RESULTS

After PH, the expression levels of SHMT2 fluctuated with time and knockdown of SHMT2 in vivo lowered the regenerative ability of liver, with reduced glycine levels compared to the scramble group. In addition, overexpression of SHMT2 in hepatocytes boosted glycine production while enhancing Akt/mTOR pathway activity. These results were validated by the application of LY294002 in vitro.

CONCLUSIONS

SHMT2 can contribute to liver regeneration after PH, and this is likely related to the activation of Akt/mTOR signaling pathway by its metabolic product, glycine, in hepatocytes. These results might have therapeutic implications for the prognosis of patients undergoing hepatic resection or transplantation.

Clinical translation of liver regeneration therapies: A conceptual road map

The increasing incidence of severe liver diseases worldwide has resulted in a high demand for curative liver transplantation. Unfortunately, the need for transplants by far eclipses the availability of suitable grafts leaving many waitlisted patients to face liver failure and often death. Routine use of smaller grafts (for example left lobes, split livers) from living or deceased donors could increase the number of life-saving transplants but is often limited by the graft versus recipient weight ratio defining the safety margins that minimize the risk of small for size syndrome (SFSS). SFSS is a severe complication characterized by failure of a small liver graft to regenerate and occurs when a donor graft is insufficient to meet the metabolic demand of the recipient, leading to liver failure as a result of insufficient liver mass. SFSS is not limited to transplantation but can also occur in the setting of hepatic surgical resections, where life-saving large resections of tumors may be limited by concerns of post-surgical liver failure. There are, as yet no available pro-regenerative therapies to enable liver regrowth and thus prevent SFSS. However, there is optimism around targeting factors and pathways that have been identified as regulators of liver regeneration to induce regrowth in vivo and ex vivo for clinical use. In this commentary, we propose a roadmap for developing such pro-regenerative therapy and for bringing it into the clinic. We summarize the clinical indications, preclinical models, pro-regenerative pathways and safety considerations necessary for developing such a drug.

The Beneficial Roles of SIRT1 in Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF) as a result of accumulated drugs in the human body metabolized into toxic agents and helps generate heavy oxidative stress, inflammation, and apoptosis, which induces necrosis in hepatocytes and ultimately damages the liver. Sirtuin 1 (SIRT1) is said to have multiple vital roles in cell proliferation, aging, and antistress systems of the human body. The levels of SIRT1 and its activation precisely modulate its critical role in the interaction between multiple step procedures of DILI. The nuclear factor kappa-light-chain-enhancer of activated B cell- (NF-κB-) mediated inflammation signaling pathway, reactive oxygen species (ROS), DNA damage, mitochondrial membrane potential collapse, and endoplasmic reticulum (ER) stress also contribute to aggravate DILI. Apoptosis is regarded as the terminal reaction followed by multiple signaling cascades including caspases, p53, and mitochondrial dysfunction which have been said to contribute in DILI. The SIRT1 activator is regarded as a potential candidate for DILI, because the former could inhibit signaling of p53, NF-κB, and ER stress. On the other hand, overexpression of SIRT1 also enhances the activation of antioxidant responses via Kelch-like ECH-associated protein 1- (Keap1-) nuclear factor- (erythroid-derived 2-) like 2 (Nrf2) signaling. The current manuscript will highlight the mechanism of DILI and the interaction of SIRT1 with various cytoplasmic factors leading to DILI along with the summary of potent SIRT1 agonists.

TAZ stimulates liver regeneration through interleukin-6-induced hepatocyte proliferation and inhibition of cell death after liver injury

In response to liver injury, the liver undergoes a regeneration process to retain its mass and function. However, the regeneration mechanism has not been fully clarified. This study investigated the role of transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo-signaling effector, in liver regeneration. We observed that TAZ stimulates liver regeneration after liver injury. After partial hepatectomy (PHx) or carbon tetrachloride damage, TAZ was required for liver regeneration to increase hepatic cell proliferation and resist hepatic apoptosis, which were decreased in liver-specific TAZ knockout (LKO) mice. TAZ stimulated macrophage infiltration, resulting in IL-6 production, which induced liver regeneration. In LKO mice, IL-6-induced activation of signal transducer and activator of transcription 3, ERK, and PKB was decreased. We also observed that periductal fibrogenesis was significantly increased in LKO mice during liver regeneration after PHx, which was caused by increased hepatic apoptosis. Our results suggest that TAZ stimulates liver regeneration through IL-6-induced hepatocyte proliferation and inhibition of cell death after liver injury.-Kim, A. R., Park, J. I., Oh, H. T., Kim, K. M., Hwang, J.-H., Jeong, M. G., Kim, E.-H., Hwang, E. S., Hong, J.-H. TAZ stimulates liver regeneration through interleukin-6-induced hepatocyte proliferation and inhibition of cell death after liver injury.

Nicotinamide induces liver regeneration and improves liver function by activating SIRT1

Nicotinamide (Nam) has recently been characterized as an agent for tissue regeneration due to the observed pro‑proliferation effects. However, the effect of Nam on liver regeneration remains undetermined. In the present study, the potency of Nam as a regimen to promote liver regeneration and restore liver function was evaluated following partial hepatectomy (PH) on C57BL/6 mice. Ki‑67 immunohistochemical and cell cycle analyses demonstrated that exogenous Nam supplementation promoted the proliferation of hepatocytes and accelerated the recovery of liver tissue. The addition of Nam protected liver function following PH, as evidenced by hematoxylin and eosin staining of liver tissue morphology and measurement of serum liver injury markers. Notably, immunoblotting results revealed that the expression and activity of NAD‑dependent protein deacetylase sirtuin‑1 (SIRT1) were significantly upregulated following treatment with Nam, suggesting that Nam may promote liver regeneration through activation of SIRT1. The present study demonstrated that Nam regulated the process of liver regeneration and improved liver function by activating SIRT1, suggesting that Nam has the potency to be used for promoting liver regeneration following surgical resection.

Resveratrol Improves Recovery and Survival of Diet-Induced Obese Mice Undergoing Extended Major (80%) Hepatectomy

INTRODUCTION

Loss of hepatic epidermal growth factor receptor (EGFR) expression is a cause for the increased perioperative risk for complications and death in patients with obesity and fatty liver undergoing liver resection. Herein, we set out to identify agents that might increase EGFR expression and improve recovery for patients with fatty liver undergoing resection. Using the diet-induced obese (DIO) mouse model of fatty liver, we examined resveratrol as a therapy to induce EGFR expression and improve outcomes following 80% partial hepatectomy (PH) in a murine model.

METHODS

DIO mice were fed resveratrol or carrier control by gavage. EGFR expression and the response to major (80%) PH were examined.

RESULTS

Based on an Illumina analysis, resveratrol was identified as increasing EGFR gene expression in A549 cells. Resveratrol was observed to also increase EGFR protein expression in A549 cells. DIO mice fed resveratrol by gavage (75 mg/kg) demonstrated an increased EGFR expression without the identified hepatic toxicity. Resveratrol and control mice subjected to 80% PH, a model of high mortality hepatectomy in DIO mice, demonstrated macroscopically decreased fatty liver and fewer liver hemorrhagic petechiae. Resveratrol pretreatment ameliorated liver injury and accelerated regeneration of the hepatic remnant after 80% PH including decreasing serum ALT and bilirubin, while increasing hepatic PCNA expression. Resveratrol increased induction of p-STAT3 and p-AKT after 80% hepatectomy. Resveratrol pretreatment significantly improved survival rates in DIO mice undergoing extended 80% PH.

CONCLUSIONS

Oral resveratrol restores EGFR expression in fatty liver. Resveratrol may be a promising protective agent in instances where extensive hepatic resection of fatty liver is required.

GDF11 induces kidney fibrosis, renal cell epithelial-to-mesenchymal transition, and kidney dysfunction and failure

BACKGROUND

GDF11 modulates embryonic patterning and kidney organogenesis. Herein, we sought to define GDF11 function in the adult kidney and in renal diseases.

METHODS

In vitro renal cell lines, genetic, and murine in vivo renal injury models were examined.

RESULTS

Among tissues tested, Gdf11 was highest in normal adult mouse kidney. Expression was increased acutely after 5/6 nephrectomy, ischemia-reperfusion injury, kanamycin toxicity, or unilateral ureteric obstruction. Systemic, high-dose GDF11 administration in adult mice led to renal failure, with accompanying kidney atrophy, interstitial fibrosis, epithelial-to-mesenchymal transition of renal tubular cells, and eventually death. These effects were associated with phosphorylation of SMAD2 and could be blocked by follistatin. In contrast, Gdf11 heterozygous mice showed reduced renal Gdf11 expression, renal fibrosis, and expression of fibrosis-associated genes both at baseline and after unilateral ureteric obstruction compared with wild-type littermates. The kidney-specific consequences of GDF11 dose modulation are direct effects on kidney cells. GDF11 induced proliferation and activation of NRK49f renal fibroblasts and also promoted epithelial-to-mesenchymal transition of IMCD-3 tubular epithelial cells in a SMAD3-dependent manner.

CONCLUSION

Taken together, these data suggest that GDF11 and its downstream signals are critical in vivo mediators of renal injury. These effects are through direct actions of GDF11 on renal tubular cells and fibroblasts. Thus, regulation of GDF11 presents a therapeutic target for diseases involving renal fibrosis and impaired tubular function.

Increased Level of Interleukin 6 Associates With Increased 90-Day and 1-Year Mortality in Patients With End-Stage Liver Disease

BACKGROUND & AIMS

Organ allocation for liver transplantation is based on prognosis, using the model for end-stage liver disease (MELD) or MELD including serum sodium (MELD-Na) score. These scores do not consider systemic inflammation and septic complications. Blood level of C-reactive protein (CRP), in addition to the MELD score, associates with mortality in patients with end-stage liver disease, whereas levels of interleukin 6 (IL6) have not been systematically studied.

METHODS

We performed a retrospective observational cohort study of 474 patients with end-stage liver disease (63.5% male; median age, 56.9 years), evaluated for liver transplantation in Germany, with at least 1 year of follow up. Data were collected on blood levels of CRP, IL6, and white blood cell count (WBC). Findings were analyzed in relation to mortality and compared with patients' MELD scores and MELD-Na scores. For survival analysis, the cohort was divided into quartiles of IL6, CRP, and WBC levels, as well as MELD scores. Log-rank test and the Cox proportional hazards regression model were used to compare the groups, and area under the receiver operating characteristic (AUROC) values were calculated.

RESULTS

Blood levels of IL6 and MELD scores associated with mortality: none of the patients with levels of IL6 below the first quartile (below 5.3 pg/mL) died within 1 year. In contrast, 67.7% of the patients in the highest quartile of IL6 level (37.0 pg/mL or more) died within 1 year. MELD score also correlated with mortality: among patients with MELD scores below 8.7, 0.9% died within 1 year, whereas in patients with MELD scores of 18.0 or more, 67.4% died within 1 year. The predictive value of level of IL6 (AUROC, 0.940) was higher than level of CRP (AUROC, 0.866) (P = .009) or WBC (AUROC, 0.773) (P < .001) for 90-day mortality. MELD scores associated with 90-day mortality (AUROC, 0.933) (P = .756) as did MELD-Na score (AUROC, 0.946) (P = .771). Level of IL6 associated with 1-year mortality (AUROC, 0.916) to a greater extent than liver synthesis or detoxification markers international normalized ratio (AUROC, 0.839) (P = .007) or bilirubin (AUROC 0.846) (P = .007). Level of IL6 was an independent, significant risk factor for mortality after adjustment for MELD score, MELD-Na score, level of CRP, or WBC.

CONCLUSIONS

In a retrospective analysis, we found high blood levels of IL6 to associate with 90-day and 1-year mortality in patients with end-stage liver disease; its predictive value was comparable to that of MELD or MELD-Na score, and was higher than that of level of CRP or WBC. Further studies should be performed to confirm the results in different cohorts.

Pharmacological Mobilization of Endogenous Bone Marrow Stem Cells Promotes Liver Regeneration after Extensive Liver Resection in Rats

Rapid regeneration of the remnant liver is critical for preventing liver failure and promoting recovery after extensive liver resection. Numerous studies have demonstrated the involvement of bone marrow-derived stem cells in liver regeneration and the potential benefits of bone marrow stem cell therapy. To avoid the preparation of stem cells, we proposed in this study to mobilize endogenous bone marrow stem cells pharmacologically with a combination of AMD3100 (A), an antagonist of CXCR4 and low-dose FK506 (F). Here we show that AF combination therapy significantly increased lineage negative (Lin-) CD34+ and Lin-CD133+ stem cells in peripheral blood and enhanced recruitment of CD133+ cells into the remnant liver in a rat model of 85% partial hepatectomy. Recruiting CD133+ stem cells in the remnant liver was associated with increased proliferation of hepatic oval cells and paralleled the increased SDF-1, CXCR4 and HGF expression. Importantly, AF combination therapy increased the number of Ki67 positive hepatocytes and BrdU incorporation in the remnant liver and improved serum levels of albumin. Our results demonstrate that pharmacological mobilization of endogenous bone marrow stem cells with AF combination therapy can enhance endogenous stem cell mobilization to promote liver regeneration and improve liver function after extensive hepatectomy.

Meloxicam increases epidermal growth factor receptor expression improving survival after hepatic resection in diet-induced obese mice

BACKGROUND

Patients with fatty liver have delayed regenerative responses, increased hepatocellular injury, and increased risk for perioperative mortality. Currently, no clinical therapy exists to prevent liver failure or improve regeneration in patients with fatty liver. Previously we demonstrated that obese mice have markedly reduced levels of epidermal growth factor receptor in liver. We sought to identify pharmacologic agents to increase epidermal growth factor receptor expression to improve hepatic regeneration in the setting of fatty liver resection.

METHODS

Lean (20% calories from fat) and diet-induced obese mice (60% calories from fat) were subjected to 70% or 80% hepatectomy.

RESULTS

Using the BaseSpace Correlation Engine of deposited gene arrays we identified agents that increased hepatic epidermal growth factor receptor. Meloxicam was identified as inducing epidermal growth factor receptor expression across species. Meloxicam improved hepatic steatosis in diet-induced obese mice both grossly and histologically. Immunohistochemistry and Western blot analysis demonstrated that meloxicam pretreatment of diet-induced obese mice dramatically increased epidermal growth factor receptor protein expression in hepatocytes. After 70% hepatectomy, meloxicam pretreatment ameliorated liver injury and significantly accelerated mitotic rates of hepatocytes in obese mice. Recovery of liver mass was accelerated in obese mice pretreated with meloxicam (by 26% at 24 hours and 38% at 48 hours, respectively). After 80% hepatectomy, survival was dramatically increased with meloxicam treatment.

CONCLUSION

Low epidermal growth factor receptor expression is a common feature of fatty liver disease. Meloxicam restores epidermal growth factor receptor expression in steatotic hepatocytes. Meloxicam pretreatment may be applied to improve outcome after fatty liver resection or transplantation with steatotic graft.

Bioenergetic adaptations of the human liver in the ALPPS procedure - how liver regeneration correlates with mitochondrial energy status

BACKGROUND

The Associating Liver Partition and Portal Ligation for Staged Hepatectomy (ALPPS) depends on a significant inter-stages kinetic growth rate (KGR). Liver regeneration is highly energy-dependent. The metabolic adaptations in ALPPS are unknown.

AIMS

i) Assess bioenergetics in both stages of ALPPS (T1 and T2) and compare them with control patients undergoing minor (miHp) and major hepatectomy (MaHp), respectively; ii) Correlate findings in ALPPS with volumetric data; iii) Investigate expression of genes involved in liver regeneration and energy metabolism.

METHODS

Five patients undergoing ALPPS, five controls undergoing miHp and five undergoing MaHp. Assessment of remnant liver bioenergetics in T1, T2 and controls. Analysis of gene expression and protein content in ALPPS.

RESULTS

Mitochondrial function was worsened in T1 versus miHp; and in T2 versus MaHp (p < 0.05); but improved from T1 to T2 (p < 0.05). Liver bioenergetics in T1 strongly correlated with KGR (p < 0.01). An increased expression of genes associated with liver regeneration (STAT3, ALR) and energy metabolism (PGC-1α, COX, Nampt) was found in T2 (p < 0.05).

CONCLUSION

Metabolic capacity in ALPPS is worse than in controls, improves between stages and correlates with volumetric growth. Bioenergetic adaptations in ALPPS could serve as surrogate markers of liver reserve and as target for energetic conditioning.

Epidermal growth factor receptor restoration rescues the fatty liver regeneration in mice

Hepatic steatosis is a common histological finding in obese patients. Even mild steatosis is associated with delayed hepatic regeneration and poor outcomes following liver resection or transplantation. We sought to identify and target molecular pathways that mediate this dysfunction. Lean mice and mice made obese through feeding of a high-fat, hypercaloric diet underwent 70 or 80% hepatectomy. After 70% resection, obese mice demonstrated 100% survival but experienced increased liver injury, reduced energy stores, reduced mitoses, increased necroapoptosis, and delayed recovery of liver mass. Increasing liver resection to 80% was associated with mortality of 40% in lean and 80% in obese mice (P < 0.05). Gene expression profiling showed decreased epidermal growth factor receptor (EGFR) in fatty liver. Meta-analysis of expression studies in mice, rats, and patients also demonstrated reduction of EGFR in fatty liver. In mice, both EGFR and phosphorylated EGFR decreased with increasing percent body fat. Hydrodynamic transfection of EGFR plasmids in mice corrected fatty liver regeneration, reducing liver injury, increasing proliferation, and improving survival after 80% resection. Loss of EGFR expression is rate limiting for liver regeneration in obesity. Therapies directed at increasing EGFR in steatosis might promote liver regeneration and survival following hepatic resection or transplantation.

Exogenous GDF11 induces cardiac and skeletal muscle dysfunction and wasting

Growth differentiation factor 11 (GDF11), a TGF-beta superfamily member, is highly homologous to myostatin and essential for embryonic patterning and organogenesis. Reports of GDF11 effects on adult tissues are conflicting, with some describing anti-aging and pro-regenerative activities on the heart and skeletal muscle while others opposite or no effects. Herein, we sought to determine the in vivo cardiac and skeletal muscle effects of excess GDF11. Mice were injected with GDF11 secreting cells, an identical model to that used to initially identify the in vivo effects of myostatin. GDF11 exposure in mice induced whole body wasting and profound loss of function in cardiac and skeletal muscle over a 14-day period. Loss of cardiac mass preceded skeletal muscle loss. Cardiac histologic and echocardiographic evaluation demonstrated loss of ventricular muscle wall thickness, decreased cardiomyocyte size, and decreased cardiac function 10 days following initiation of GDF11 exposure. Changes in skeletal muscle after GDF11 exposure were manifest at day 13 and were associated with wasting, decreased fiber size, and reduced strength. Changes in cardiomyocytes and skeletal muscle fibers were associated with activation of SMAD2, the ubiquitin-proteasome pathway and autophagy. Thus, GDF11 over administration in vivo results in cardiac and skeletal muscle loss, dysfunction, and death. Here, serum levels of GDF11 by Western blotting were 1.5-fold increased over controls. Although GDF11 effects in vivo are likely dose, route, and duration dependent, its physiologic changes are similar to myostatin and other Activin receptors ligands. These data support that GDF11, like its other closely related TGF-beta family members, induces loss of cardiac and skeletal muscle mass and function.

Constitutive androstane receptor (Car)-driven regeneration protects liver from failure following tissue loss

BACKGROUND & AIMS

Liver can recover following resection. If tissue loss is too excessive, however, liver failure will develop as is known from the small-for-size-syndrome (SFSS). The molecular processes underlying liver failure are ill-understood. Here, we explored the role and the clinical potential of Nr1i3 (constitutive androstane receptor, Car) in liver failure following hepatectomy.

METHODS

Activators of Car, various hepatectomies, Car(-/-) mice, humanized CAR mice, human tissue and ex vivo liver slice cultures were used to study Car in the SFSS. Pathways downstream of Car were investigated by in vivo siRNA knockdown.

RESULTS

Excessive tissue loss causing liver failure is associated with deficient induction of Car. Reactivation of Car by an agonist normalizes all features associated with experimental SFSS. The beneficial effects of Car activation are relayed through Foxm1, an essential promoter of the hepatocyte cell cycle. Deficiency in the CAR-FOXM1 axis likewise is evident in human SFSS. Activation of human CAR mitigates SFSS in humanized CAR mice and improves the culture of human liver slices.

CONCLUSIONS

Impaired hepatic Car-Foxm1 signaling provides a first molecular characterization of liver that fails to recover after tissue loss. Our findings place deficient regeneration as a principal cause behind the SFSS and suggest CAR agonists may bear clinical potential against liver failure.

LAY SUMMARY

The unique regenerative capacity of liver has its natural limits. Following tissue loss that is too excessive, such as through extended resection in the clinic, liver failure may develop. This is known as small-for-size-syndrome (SFSS) and represents the most frequent cause of death due to liver surgery. Here we show that deficient induction of the protein Car, a central regulator of liver function and growth, is a cause of liver failure following extended resection; reactivation of Car through pharmacological means is sufficient to prevent or rescue the SFSS.

STAT3 in the systemic inflammation of cancer cachexia

Weight loss is diagnostic of cachexia, a debilitating syndrome contributing mightily to morbidity and mortality in cancer. Most research has probed mechanisms leading to muscle atrophy and adipose wasting in cachexia; however cachexia is a truly systemic phenomenon. Presence of the tumor elicits an inflammatory response and profound metabolic derangements involving not only muscle and fat, but also the hypothalamus, liver, heart, blood, spleen and likely other organs. This global response is orchestrated in part through circulating cytokines that rise in conditions of cachexia. Exogenous Interleukin-6 (IL6) and related cytokines can induce most cachexia symptomatology, including muscle and fat wasting, the acute phase response and anemia, while IL-6 inhibition reduces muscle loss in cancer. Although mechanistic studies are ongoing, certain of these cachexia phenotypes have been causally linked to the cytokine-activated transcription factor, STAT3, including skeletal muscle wasting, cardiac dysfunction and hypothalamic inflammation. Correlative studies implicate STAT3 in fat wasting and the acute phase response in cancer cachexia. Parallel data in non-cancer models and disease states suggest both pathological and protective functions for STAT3 in other organs during cachexia. STAT3 also contributes to cancer cachexia through enhancing tumorigenesis, metastasis and immune suppression, particularly in tumors associated with high prevalence of cachexia. This review examines the evidence linking STAT3 to multi-organ manifestations of cachexia and the potential and perils for targeting STAT3 to reduce cachexia and prolong survival in cancer patients.

The Protective Effect of Transplanting Liver Cells Into the Mesentery on the Rescue of Acute Liver Failure After Massive Hepatectomy

Postoperative liver failure is one of the most critical complications following extensive hepatectomy. Although transplantation of allogeneic hepatocytes is an attractive therapy for posthepatectomy liver failure, transplanting cells via the portal veins typically causes portal vein embolization. The embolization by transplanted cells would be lethal in patients who have undergone massive hepatectomy. Thus, transplant surgeons need to select extrahepatic sites as transplant sites to prevent portal vein embolization. We aimed to investigate the mechanism of how liver cells transplanted into the mesentery protect recipient rats from acute liver failure after massive hepatectomy. We induced posthepatectomy liver failure by 90% hepatectomy in rats. Liver cells harvested from rat livers were transplanted into the mesenteries of hepatectomized rats. Twenty percent of the harvested cells, which consisted of hepatocytes and nonparenchymal cells, were transplanted into each recipient. The survival rate improved significantly in the liver cell transplantation group compared to the control group 7 days after hepatectomy (69 vs. 7%). Histological findings of the transplantation site, in vivo imaging system study findings, quantitative polymerase chain reaction assays of the transplanted cells, and serum albumin measurements of transplanted Nagase analbuminemic rats showed rapid deterioration of viable transplanted cells. Although viable transplanted cells deteriorated in the transplanted site, histological findings and an adenosine-5'-triphosphate (ATP) assay showed that the transplanted cells had a protective effect on the remaining livers. These results indicated that the paracrine effects of transplanted liver cells had therapeutic effects. The same protective effects were observed in the hepatocyte transplantation group, but not in the liver nonparenchymal cell transplantation group. Therefore, this effect on the remnant liver was mainly due to the hepatocytes among the transplanted liver cells. We demonstrated that transplanted liver cells protect the remnant liver from severe damage after massive hepatectomy.

Pathobiological mechanisms of peritoneal adhesions: The mesenchymal transition of rat peritoneal mesothelial cells induced by TGF-β1 and IL-6 requires activation of Erk1/2 and Smad2 linker region phosphorylation

Peritoneal adhesions, primarily caused by surgical procedures, are the leading cause of pelvic pain, bowel obstruction, and infertility. TGF-β1 and IL-6 have been found to be elevated in the peritoneal fluid of patients during/after abdominal surgery. However, it remains to be determined whether these cytokines interact and facilitate adhesion formation by promoting mesothelial to mesenchymal transition (MMT). In the present study, isolated rat peritoneal mesothelial cells were treated with TGF-β1 and/or IL-6 which elicited MMT as determined by morphologic and biochemical techniques. During this transition, cellular morphology changed from that of cobblestone polygonal cells to elongated/spindle-shaped fibroblast-like cells. There was decreased expression of genes characteristic of mesothelial cells, such as E-cadherin, and increased expression of genes characteristic of the myofibroblast phenotype, including α-smooth muscle actin and the EDA form of fibronectin, both of which appear to mediate the transfer of force to the extracellular matrix. Partial characterization of relevant signaling pathways identified Erk1/2 activation, which was enhanced by combined TGF-β1/IL-6 administration, as a crucial necessary factor in the transition. Erk1/2 activation as well as the phosphorylation of the linker region of Smad2 and MMT could be blocked by the MEK inhibitor, U0126, suggesting that such activation may be a potential pharmaceutical target to prevent MMT. In addition, the phenotypic transition could be prevented by hydrocortisone.

The Therapeutic Promise of Mesenchymal Stem Cells for Liver Restoration

Hepatocyte transplantation aims to provide a functional substitution of liver tissue lost due to trauma or toxins. Chronic liver diseases are associated with inflammation, deterioration of tissue homeostasis, and deprivation of metabolic capacity. Recent advances in liver biology have focused on the pro-regenerative features of mesenchymal stem cells (MSCs). We argue that MSCs represent an attractive therapeutic option to treat liver disease. Indeed, their pleiotropic actions include the modulation of immune reactions, the stimulation of cell proliferation, and the attenuation of cell death responses. These characteristics are highly warranted add-ons to their capacity for hepatocyte differentiation. Undoubtedly, the elucidation of the regenerative mechanisms of MSCs in different liver diseases will promote their versatile and disease-specific therapeutic use.

mTOR-Dependent Suppression of Remnant Liver Regeneration in Liver Failure After Massive Liver Resection in Rats

BACKGROUND AND AIMS

Massive hepatectomy often leads to fatal liver failure because of a small remnant liver volume. The aim of this study was to investigate the potential mechanisms leading to liver failure.

METHODS

Sprague-Dawley rats had performed a sham operation, 85 % partial hepatectomy (PH) or 90 % PH, and all had free access to water with or without supplemented glucose. Liver function and survival were evaluated. Liver parenchymal injury was assessed by evaluating hepatic pathology, blood biochemistry, and apoptotic and necrotic alterations. The regeneration response was assessed by the weight gain of the remnant liver, hepatocyte proliferation markers, and regeneration-related molecules.

RESULTS

The 90 % hepatectomy resulted in a significantly lower survival rate and impaired liver function; however, no significant more serious liver parenchymal injuries were detected. TNF-α, HGF, myc and IL-6 were either similarly expressed or overexpressed; however, the increase in remnant liver weight, mitotic index, and the presence of Ki-67 and PCNA were significantly lower in the 90 %-hepatectomized rats. mTOR, p70S6K and 4EBP1 were not activated in the remnant liver after a 90 % hepatectomy as obviously as those after an 85 % hepatectomy, which was concomitant with the higher expression of phospho-AMPK and a lower intrahepatic ATP level. Glucose treatment significantly improved the survival rate of 90 %-hepatectomized rats.

CONCLUSIONS

Suppression of remnant liver regeneration was observed in the 90 % PH and contributed to fatal liver failure. This suppressed liver regenerative capacity was related to the inhibited activation of mTOR signaling.

Dietary Vitamin D3 Restriction Exacerbates Disease Pathophysiology in the Spinal Cord of the G93A Mouse Model of Amyotrophic Lateral Sclerosis

Background

Dietary vitamin D₃ (D₃) restriction reduces paw grip endurance and motor performance in G93A mice, and increases inflammation and apoptosis in the quadríceps of females. ALS, a neuromuscular disease, causes progressive degeneration of motor neurons in the brain and spinal cord.

Objective

We analyzed the spinal cords of G93A mice following dietary D₃ restriction at 2.5% the adequate intake (AI) for oxidative damage (4-HNE, 3-NY), antioxidant enzymes (SOD2, catalase, GPx1), inflammation (TNF-α, IL-6, IL-10), apoptosis (bax/bcl-2 ratio, cleaved/pro-caspase 3 ratio), neurotrophic factor (GDNF) and neuron count (ChAT, SMI-36/SMI-32 ratio).

Methods

Beginning at age 25 d, 42 G93A mice were provided food ad libitum with either adequate (AI;1 IU D₃/g feed; 12 M, 11 F) or deficient (DEF; 0.025 IU D₃/g feed; 10 M, 9 F) D₃. At age 113 d, the spinal cords were analyzed for protein content. Differences were considered significant at P ≤ 0.10, since this was a pilot study.

Results

DEF mice had 16% higher 4-HNE (P = 0.056), 12% higher GPx1 (P = 0.057) and 23% higher Bax/Bcl2 ratio (P = 0.076) vs. AI. DEF females had 29% higher GPx1 (P = 0.001) and 22% higher IL-6 (P = 0.077) vs. AI females. DEF males had 23% higher 4-HNE (P = 0.066) and 18% lower SOD2 (P = 0.034) vs. AI males. DEF males had 27% lower SOD2 (P = 0.004), 17% lower GPx1 (P = 0.070), 29% lower IL-6 (P = 0.023) and 22% lower ChAT (P = 0.082) vs. DEF females.

Conclusion

D₃ deficiency exacerbates disease pathophysiology in the spinal cord of G93A mice, the exact mechanisms are sex-specific. This is in accord with our previous results in the quadriceps, as well as functional and disease outcomes.

Blockade of the apelin-APJ system promotes mouse liver regeneration by activating Kupffer cells after partial hepatectomy

BACKGROUND

Liver regeneration after massive hepatectomy or living donor liver transplantation is critical. The apelin-APJ system is involved in the regulation of cardiovascular function, inflammation, fluid homeostasis, the adipo-insular axis, and angiogenesis, but its function in liver regeneration remains unclear.

METHODS

We investigated the impact of pharmacologic blockade of the apelin-APJ system, using the specific APJ antagonist F13A on liver regeneration after hepatectomy in mice.

RESULTS

F13A-treated mice had significantly higher serum concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-6 than control mice, due to F13A-promoted activation of Kupffer cells. Compared with untreated mice, F13A enhanced the signal transducer and activator of transcription 3 and mitogen-activated protein kinase pathways, stimulated cell-cycle progression, and promoted hepatocyte proliferation and liver regeneration without inducing apoptosis or inflammation in regenerating livers. In vitro, Kupffer cells expressed APJ and were activated directly by F13A treatment, releasing TNF-α and IL-6. Moreover, F13A-treated mice had a higher survival rate than untreated mice in the extended hepatectomy model.

CONCLUSIONS

F13A treatment promotes early phase liver regeneration after hepatectomy by promoting the activation of Kupffer cells and increasing serum levels of TNF-α and IL-6. F13A treatment may become a therapeutic option to facilitate efficient liver regeneration after liver surgery.

Role for the endoplasmic reticulum stress sensor IRE1α in liver regenerative responses

BACKGROUND & AIMS

As the main detoxifying organ of the body, the liver possesses a remarkable ability to regenerate after toxic injury, tissue resection or viral infection. A growing number of cellular signaling pathways have been implicated in orchestrating the process of liver regeneration. Here we investigated the role of inositol-requiring enzyme-1α (IRE1α), a key signal transducer of the unfolded protein response (UPR), in liver regeneration.

METHODS

Using mice with hepatocyte-specific deletion of IRE1α, we examined the role of IRE1α in liver regeneration after challenges with carbon tetrachloride (CCl4) or hepatic surgery. We also investigated if IRE1α deficiency could affect the activation state of signal transducer and activator of transcription 3 (STAT3) in hepatocytes. Using co-immunoprecipitation and glutathione S-transferase (GST) pull-down assays, we analyzed whether IRE1α could interact with STAT3 to regulate its phosphorylation.

RESULTS

We found that in response to CCl4-induced liver damage or after two-thirds partial hepatectomy (PH), abrogation of IRE1α caused marked exacerbation of liver injury and impairment in regenerative proliferation of hepatocytes in mice. Furthermore, IRE1α deficiency resulted in dampened STAT3 activation, and restoration of IRE1α expression led to sustained phosphorylation of STAT3 in IRE1α-null hepatocytes. Additionally, IRE1α could directly and constitutively associate with STAT3, leading to elevated phosphorylation when stimulated by IL-6.

CONCLUSIONS

These results suggest that IRE1α may promote liver regeneration through acting as a signaling platform to regulate the STAT3 pathway.

Mesenchymal stem cells promote liver regeneration and prolong survival in small-for-size liver grafts: involvement of C-Jun N-terminal kinase, cyclin D1, and NF-κB

Background

The therapeutic potential of mesenchymal stem cells (MSCs) has been highlighted recently for treatment of acute or chronic liver injury, by possibly differentiating into hepatocyte-like cells, reducing inflammation, and enhancing tissue repair. Despite recent progress, exact mechanisms of action are not clearly elucidated. In this study, we attempted to explore whether and how MSCs protected hepatocytes and stimulated allograft regeneration in small-for-size liver transplantation (SFSLT).

Methods

SFSLT model was established with a 30% partial liver transplantation (30PLT) in rats. The differentiation potential and characteristics of bone marrow derived MSCs were explored in vitro. MSCs were infused transvenously immediately after graft implantation in therapy group. Expressions of apoptosis-, inflammatory-, anti-inflammatory-, and growth factor-related genes were measured by RT-PCR, activities of transcription factors AP-1 and NF-κB were analyzed by EMSA, and proliferative responses of the hepatic graft were evaluated by immunohistochemistry and western blot.

Results

MSCs were successfully induced into hepatocyte-like cells, osteoblasts and adipocytes in vitro. MSCs therapy could not only alleviate ischemia reperfusion injury and acute inflammation to promote liver regeneration, but also profoundly improve one week survival rate. It markedly up-regulated the mRNA expressions of HGF, Bcl-2, Bcl-XL, IL-6, IL-10, IP-10, and CXCR2, however, down-regulated TNF-α. Increased activities of AP-1 and NF-κB, as well as elevated expressions of p-c-Jun, cyclin D1, and proliferating cell nuclear antigen (PCNA), were also found in MSCs therapy group.

Conclusion

These data suggest that MSCs therapy promotes hepatocyte proliferation and prolongs survival in SFSLT by reducing ischemia reperfusion injury and acute inflammation, and sustaining early increased expressions of c-Jun N-terminal Kinase, Cyclin D1, and NF-κB.

A mutually beneficial relationship between hepatocytes and cardiomyocytes mitigates doxorubicin-induced toxicity

Use of doxorubicin (DOX) is limited by its toxicity in multiple organs. However, the relationship between different organs in response to DOX-induced injury is not well understood. We found that partial hepatectomy correlated with increased DOX-induced heart injury in vivo while supernatant prepared from DOX-treated hepatocytes mitigated DOX-induced cytotoxicity of cardiomyocytes in vitro. Meanwhile, the supernatant of DOX-treated cardiomyocytes mitigated DOX-induced cytotoxicity of hepatocytes. Investigation of the molecular mechanisms underlying these effects found that interleukin 6 (IL-6) was significantly up-regulated in DOX-treated tissues and cells, and supernatant from IL-6 treated cells had a similar effect to that from DOX-treated cells. Although the concentration of secreted IL-6 in supernatant from DOX-treated cells did not significantly differ, blockade of IL-6 signaling, by overexpressing SOCS3, suppressed expression of the downstream molecules trefoil factor family 3 (TFF3) and hepatocyte growth factor (HGF), impaired the mutually beneficial relationship between hepatocytes and cardiomyocytes. In conclusion, our study shows that a mutually beneficial relationship exists between hepatocytes and cardiomyocytes during the acute injury induced by DOX. Moreover, it demonstrates that this phenomenon may be indirectly caused by increased IL-6 expression and the activation of the downstream molecular mediators TFF3 and HGF in hepatocytes and cardiomyocytes, respectively.

Interleukin-6 is required for cell cycle arrest and activation of DNA repair enzymes after partial hepatectomy in mice

Background

Interleukin-6 (IL-6) has been shown to be vital for liver regeneration, however the specific mechanisms and factors involved remain incompletely defined. The present study aimed to investigate whether IL-6 exerts its protective effects via arresting the cell cycle allowing base excision and repair of oxidized DNA after hepatectomy.

Results

Following seventy percent partial hepatectomy (PH) in wild type (WT) mice IL-6 serum levels increased reaching peak levels at 3 hours. This was associated with markers of cell cycle arrest as p21 expression was increased and cyclin D1 and proliferating cell nuclear antigen (PCNA) expression decreased. In the absence of IL-6, markers of cell cycle arrest were absent and the number of bromodeoxyuridine (BrdU) positive cells was significantly higher at 28, 32 and 36 hours after PH. The mRNAs for DNA repair enzymes, including Neil-1, 8-oxodGTPase, OGG1, Apex1, and UDG (DNA glycosylase) were increased 2 to 4 fold in WT mice at 6 and/or 12 hours after PH compared to IL-6 knockout (KO) mice. The protein levels of Neil1 and OGG1 were also significantly increased in WT mice compared to KO mice. Pathological changes were far greater and survival was less in IL-6 KO mice than in WT mice. Administration of IL-6 in KO mice restored p21 and DNA repair enzyme expression to wild-type levels and survival was improved.

Conclusions

IL-6 caused cell cycle arrest and delayed proliferation during the first day after PH. This delay was associated with the activation of DNA repair enzymes resulting in accurate replication and restoration of hepatic mass.

Matrix metalloproteinase-9 in the initial injury after hepatectomy in mice

AIM

To investigate the role of matrix metalloproteinase (MMP)-9 in the pathogenesis of postoperative liver failure (PLF) after extended hepatectomy (EH).

METHODS

An insufficient volume of the remnant liver (RL) results in higher morbidity and mortality, and a murine model with 80%-hepatectomy was used. All investigations were performed 6 h after EH. Mice were first divided into two groups based on the postoperative course (i.e., the PLF caused or did not), and MMP-9 expression was measured by Western blotting. The source of MMP-9 was then determined by immunohistological stainings. Tissue inhibitor of metalloproteinase (TIMP)-1 is the endogenous inhibitor of MMP-9, and MMP-9 behavior was assessed by the experiments in wild-type, MMP-9(-/-) and TIMP-1(-/-) mice by Western blotting and gelatin zymography. The behavior of neutrophils was also assessed by immunohistological stainings. An anti-MMP-9 monoclonal antibody and a broad-spectrum MMP inhibitor were used to examine the role of MMP-9.

RESULTS

Symptomatic mice showed more severe PLF (histopathological assessments: 2.97 ± 0.92 vs 0.11 ± 0.08, P < 0.05) and a higher expression of MMP-9 (71085 ± 18274 vs 192856 ± 22263, P < 0.01). Nonnative leukocytes appeared to be the main source of MMP-9, because MMP-9 expression corresponding with CD11b positive-cell was observed in the findings of immunohistological stainings. In the histopathological findings, the PLF was improved in MMP-9(-/-) mice (1.65% ± 0.23% vs 0.65% ± 0.19%, P < 0.01) and it was worse in TIMP-1(-/-) mice (1.65% ± 0.23% vs 1.78% ± 0.31%, P < 0.01). Moreover, neutrophil migration was disturbed in MMP-9(-/-) mice in the immunohistological stainings. Two methods of MMP-9 inhibition revealed reduced PLF, and neutrophil migration was strongly disturbed in MMP-9-blocked mice in the histopathological assessments (9.6 ± 1.9 vs 4.2 ± 1.2, P < 0.05, and 9.9 ± 1.5 vs 5.7 ± 1.1, P < 0.05).

CONCLUSION

MMP-9 is important for the process of PLF. The initial injury is associated with MMP-9 derived from neutrophils, and MMP-9 blockade reduces PLF. MMP-9 may be a potential target to prevent PLF after EH and to overcome an insufficient RL.

Hypothermia predicts hepatic failure after extensive hepatectomy in mice

AIM

To investigate the effect of hypothermia on the function of the liver remnant (LR) after extended hepatectomy.

METHODS

We performed a 75% partial hepatectomy (PH) in male C57BL/6J mice. Body temperature was measured with a rectal probe. The study mice were prospectively grouped as hypothermic (HT) or normothermic (NT) if their body temperature was < 34 °C vs ≥ 34 °C, respectively. Blood and liver samples were obtained at 24 and 48 h after 75% PH. Various factors during and after 75% PH were compared at each time point and the most important factor for a good outcome after 75% PH was determined.

RESULTS

At 24 and 48 h after 75% PH, LR weight was decreased in HT mice compared with that in NT mice and the assay results in the HT mice were consistent with liver failure. NT mice had normal liver regeneration. Each intra- and post-operative factor which showed statistical significance in univariate analysis was evaluated by multivariate analysis. The most important factor for a good outcome after 75% PH was body temperature at both 24 and 48 h after surgery.

CONCLUSION

Hypothermia after an extensive hepatectomy predicts impending liver failure and may be a useful clinical marker for early detection of liver failure after extended hepatectomy.

Suppression of liver regeneration affects hepatic graft survival in small-for-size liver transplantation in rats

AIM

  Small-for-size liver transplantation (SFSLT) often results in hepatic graft failure and decreased survival. The present study was aimed to investigate the possible mechanism of hepatic graft failure in SFSLT in rats.

METHODS

  Rat models of full-size orthotopic liver transplantation, 50% partial liver transplantation and 30% partial liver transplantation were established. Proliferative responses of the hepatic graft were evaluated by immunohistochemical staining and western blotting. Apoptosis-, inflammatory-, anti-inflammatory- and growth factor-related genes were screened by quantitative reverse transcription polymerase chain reaction. Activities of transcription factors of AP-1 and nuclear factor (NF)-κB were analyzed by electrophoretic mobility shift assay.

RESULTS

  A 30% partial liver transplant not only resulted in marked structural damages to the hepatic graft, but also showed the lowest 7-day survival rate. In addition, sup pressed expressions of proliferating cell nuclear antigen (PCNA) and cyclin D1 by immunohistochemical staining and decreased expressions of cyclin D1 and p-c-Jun by western blotting were detected. Downregulated expressions of Bcl-2, Bcl-XL, interleukin (IL)-6, IL-10, IP-10 and CXCR2, upregulated expression of tumor necrosis factor-α, and decreased levels of AP-1 and NF-κB were also found following 30% partial liver transplantation after reperfusion.

CONCLUSION

  Liver regeneration is remarkably suppressed in SFSLT. The significant changes of intra-graft gene expression described above indicated that ischemia reperfusion injury would be severe in 30% partial liver transplantation. The capability of liver regeneration secondary to ischemia reperfusion injury might determine hepatic graft survival in SFSLT.

The regenerative activity of interleukin-6

Interleukin-6 (IL-6) is a cytokine which is involved in many inflammatory processes and in the development of cancer. In addition, IL-6 has been shown to be important for the induction of hepatic acute-phase proteins, for the regeneration of the liver and for the stimulation of B-cells. IL-6 binds to a transmembrane IL-6 receptor (IL-6R), which is present on hepatocytes and some leukocytes. The complex of IL-6 and IL-6R associates with a second protein, gp130, which is expressed on all cells of the body. Since neither IL-6 nor IL-6R has a measurable affinity for gp130, cells, which do not express IL-6R, are not responsive to the cytokine IL-6. It could be shown, however, that a naturally occurring soluble IL-6R (sIL-6R) in complex with IL-6 can bind to gp130 on cells with no IL-6R expression. Therefore, cells shedding the sIL-6R render cells, which only express gp130, responsive to the cytokine. This process has been called trans-signaling. In the present chapter, we summarize the known activities of IL-6 with a special emphasis on regenerative activities, which often depend on the sIL-6R. A designer cytokine called Hyper-IL-6, which is a fusion protein of IL-6 and the sIL-6R, can mimic IL-6 trans-signaling responses in vitro and in vivo with considerably higher efficacy than the combination of the natural proteins IL-6 and sIL-6R. We present recent examples from animal models in which the therapeutic potential of Hyper-IL-6 has been evaluated. We propose that Hyper-IL-6 can be used to induce potent regeneration responses in liver, kidney, and other tissues and therefore will be a novel therapeutic approach in regenerative medicine.

Liver failure after extended hepatectomy in mice is mediated by a p21-dependent barrier to liver regeneration

BACKGROUND & AIMS

Extended liver resection leads to hepatic failure because of a small remnant liver volume. Excessive parenchymal damage has been proposed as the principal cause of this failure, but little is known about the contribution of a primary deficiency in liver regeneration. We developed a mouse model to assess the regenerative capacity of a critically small liver remnant.

METHODS

Extended (86%) hepatectomy (eHx) was modified to minimize collateral damage; effects were compared with those of standard (68%) partial hepatectomy (pHx) in mice. Markers of liver integrity and survival were evaluated after resection. Liver regeneration was assessed by weight gain, proliferative activity (analyses of Ki67, proliferating cell nuclear antigen, phosphorylated histone 3, mitosis, and ploidy), and regeneration-associated molecules. Knockout mice were used to study the role of p21.

RESULTS

Compared with pHx, survival of mice was reduced after eHx, and associated with cholestasis and impaired liver function. However, no significant differences in hepatocyte death, sinusoidal injury, oxidative stress, or energy depletion were observed between mice after eHx or pHx. No defect in the initiation of hepatocyte proliferation was apparent. However, restoration of liver mass was delayed after eHx and associated with inadequate induction of Foxm1b and a p21-dependent delay in cell-cycle progression. In p21(-/-) mice, the cell cycle was restored, the gain in liver weight was accelerated, and survival improved after eHx.

CONCLUSIONS

Significant parenchymal injury is not required for liver failure to develop after extended hepatectomy. Rather, liver dysfunction after eHx results from a transient, p21-dependent block before hepatocyte division. Therefore, a deficiency in cell-cycle progression causes liver failure after extended hepatectomy and can be overcome by inhibition of p21.

Effect of specific activation of γ-aminobutyric acid receptor in vivo on oxidative stress-induced damage after extended hepatectomy

AIM

  γ-Aminobutyric acid (GABA) is a multifunctional molecule with various physiological effects throughout the body. The regulation of GABA receptor (GABAR) plays a key role in reducing the damage mediated by oxidative stress (OS). Extended hepatectomy causes fatal OS-induced injury in the liver remnant. We aimed to investigate the effect of a GABAR agonist in extended hepatectomy.

METHODS

  Saline or a GABAR agonist (43.56 nmol/g bodyweight of muscimol) was administrated intravenously at 4 h preoperatively. C57BL/6 mice were divided into three groups: laparotomy only, 90% hepatectomy with saline and 90% hepatectomy with a GABAR agonist. Liver samples were obtained at 6 h after surgery.

RESULTS

  Survival curves were prolonged by the GABAR agonist. Histopathological findings and biochemical profiles showed that the GABAR agonist reduced liver damage. Immunohistological assessment demonstrated that the GABAR agonist prevented apoptotic induction. As shown by 4-hydroxynonenal, which reflects OS-induced damage, 90% hepatectomy caused OS and the GABAR agonist reduced OS. We measured ataxia-telangiectasia mutated kinase (ATM), H2AX, Akt and free radical scavenging enzymes because they may be affected by GABAR regulation, and found that Akt was greatly decreased after 90% hepatectomy, but it recovered with the GABAR agonist.

CONCLUSION

  GABAR is activated by a specific agonist in the liver in vivo. This activation reduces OS-mediated damage after extended hepatectomy in vivo, and the mechanism via an Akt-dependent pathway may be a key.

Conformational technique for non-anatomic resection of liver lesions

Safe margin-negative hepatic resection with maximal preservation of normal liver parenchyma is the primary operative objective in treating patients with metastatic or primary liver malignancies. A technique to perform non-anatomic liver resection(s) for large lesions that may involve major hepatic vascular structures is herein described. This technique employs linear cutting stapler technology and specific mobilization of the liver to perform single or multiple large spherical resections of liver lesions.

Inflammation, organomegaly, and muscle wasting despite hyperphagia in a mouse model of burn cachexia

BACKGROUND

Burn injury results in a chronic inflammatory, hypermetabolic, and hypercatabolic state persisting long after initial injury and wound healing. Burn survivors experience a profound and prolonged loss of lean body mass, fat mass, and bone mineral density, associated with significant morbidity and reduced quality of life. Understanding the mechanisms responsible is essential for developing therapies. A complete characterization of the pathophysiology of burn cachexia in a reproducible mouse model was lacking.

METHODS

Young adult (12-16 weeks of age) male C57BL/6J mice were given full thickness burns using heated brass plates or sham injury. Food and water intake, organ and muscle weights, and muscle fiber diameters were measured. Body composition was determined by Piximus. Plasma analyte levels were determined by bead array assay.

RESULTS

Survival and weight loss were dependent upon burn size. The body weight nadir in burned mice was 14 days, at which time we observed reductions in total body mass, lean carcass mass, individual muscle weights, and muscle fiber cross-sectional area. Muscle loss was associated with increased expression of the muscle ubiquitin ligase, MuRF1. Burned mice also exhibited reduced fat mass and bone mineral density, concomitant with increased liver, spleen, and heart mass. Recovery of initial body weight occurred at 35 days; however, burned mice exhibited hyperphagia and polydipsia out to 80 days. Burned mice had significant increases in serum cytokine, chemokine, and acute phase proteins, consistent with findings in human burn subjects.

CONCLUSIONS

This study describes a mouse model that largely mimics human pathophysiology following severe burn injury. These baseline data provide a framework for mouse-based pharmacological and genetic investigation of burn-injury-associated cachexia.

Simple and reproducible hepatectomy in the mouse using the clip technique

AIM

To investigate the reliability of massive hepatectomy models by using clip techniques.

METHODS

We analyzed anatomical findings in 100 mice following massive hepatectomy induced by liver reduction > 70%. The impact of various factors in the different models was also analyzed, including learning curves, operative time, survival curves, and histopathological findings.

RESULTS

According to anatomical results, models with 75%, 80%, and 90% hepatectomy produced massive hepatectomy. Learning curves and operative times were most optimal with the clip technique. Each hepatectomy performed using the clip technique produced a reasonable survival curve, and there were no differences in histopathological findings between the suture and clip techniques.

CONCLUSION

Massive hepatectomy by the clip technique is simple and can provide reliable and relevant data.

Matrix metalloproteinase-9 contributes to parenchymal hemorrhage and necrosis in the remnant liver after extended hepatectomy in mice

AIM

To investigate the effect of matrix metalloproteinase-9 (MMP-9) on the remnant liver after massive hepatectomy in the mouse.

METHODS

Age-matched, C57BL/6 wild-type (WT), MMP-9(-/-), and tissue inhibitors of metalloproteinases (TIMP)-1(-/-) mice were used. The mice received 80%-partial hepatectomy (PH). Samples were obtained at 6 h after 80%-PH, and we used histology, immunohistochemical staining, western blotting analysis and zymography to investigate the effect of PH on MMP-9. The role of MMP-9 after PH was investigated using a monoclonal antibody and MMP inhibitor.

RESULTS

We examined the remnant liver 6 h after 80%-PH and found that MMP-9 deficiency attenuated the formation of hemorrhage and necrosis. There were significantly fewer and smaller hemorrhagic and necrotic lesions in MMP-9(-/-) remnant livers compared with WT and TIMP-1(-/-) livers (P < 0.01), with no difference between WT and TIMP-1(-/-) mice. Serum alanine aminotransaminase levels were significantly lower in MMP-9(-/-) mice compared with those in TIMP-1(-/-) mice (WT: 476 ± 83 IU/L, MMP-9(-/-): 392 ± 30 IU/L, TIMP-1(-/-): 673 ± 73 IU/L, P < 0.01). Western blotting and gelatin zymography demonstrated a lack of MMP-9 expression and activity in MMP-9(-/-) mice, which was in contrast to WT and TIMP-1(-/-) mice. No change in MMP-2 expression was observed in any of the study groups. Similar to MMP-9(-/-) mice, when WT mice were treated with MMP-9 monoclonal antibody or the synthetic inhibitor GM6001, hemorrhagic and necrotic lesions were significantly smaller and fewer than in control mice (P < 0.05). These results suggest that MMP-9 plays an important role in the development of parenchymal hemorrhage and necrosis in the small remnant liver.

CONCLUSION

Successful MMP-9 inhibition attenuates the formation of hemorrhage and necrosis and might be a potential therapy to ameliorate liver injury after massive hepatectomy.

Three dimensional cultures of rat liver cells using a natural self-assembling nanoscaffold in a clinically relevant bioreactor for bioartificial liver construction

Till date, no bioartificial liver (BAL) procedure has obtained FDA approval or widespread clinical acceptance, mainly because of multifactorial limitations such as the use of microscale or undefined biomaterials, indirect and lower oxygenation levels in liver cells, short-term undesirable functions, and a lack of 3D interaction of growth factor/cytokine signaling in liver cells. To overcome preclinical limitations, primary rat liver cells were cultured on a naturally self-assembling peptide nanoscaffold (SAPN) in a clinically relevant bioreactor for up to 35 days, under 3D interaction with suitable growth factors and cytokine signaling agents, alone or combination (e.g., Group I: EPO, Group II: Activin A, Group III: IL-6, Group IV: BMP-4, Group V: BMP4 + EPO, Group VI: EPO + IL-6, Group VII: BMP4 + IL-6, Group VIII: Activin A + EPO, Group IX: IL-6 + Activin A, Group X: Activin A + BMP4, Group XI: EPO + Activin A + BMP-4 + IL-6 + HGF, and Group XII: Control). Major liver specific functions such as albumin secretion, urea metabolism, ammonia detoxification, phase contrast microscopy, immunofluorescence of liver specific markers (Albumin and CYP3A1), mitochondrial status, glutamic oxaloacetic transaminase (GOT) activity, glutamic pyruvic transaminase (GPT) activity, and cell membrane stability by the lactate dehydrogenase (LDH) test were also examined and compared with the control over time. In addition, we examined the drug biotransformation potential of a diazepam drug in a two-compartment model (cell matrix phase and supernatant), which is clinically important. This present study demonstrates an optimized 3D signaling/scaffolding in a preclinical BAL model, as well as preclinical drug screening for better drug development.

Is surgical resection superior to transplantation in the treatment of hepatocellular carcinoma?

OBJECTIVE

To compare outcomes for patients with hepatocellular carcinoma (HCC) treated with either liver resection or transplantation.

METHODS

A retrospective, single-institution analysis of 413 HCC patients from 1999 to 2009.

RESULTS

A total of 413 patients with HCC underwent surgical resection (n = 106) and transplantation (n = 270) or were listed without receiving transplantation (n = 37). Excluding transplanted patients with incidental tumors (n = 50), 257 patients with suspected HCC were listed with the intent to transplant (ITT). The median diameter of the largest tumor by radiography was 6.0 cm in resected, 3.0 cm in transplanted, and 3.4 cm in the listed-but-not-transplanted patients. Median time to transplant was 48 days. Recurrence rates were 19.8% for resection and 12.1% for all ITT patients. Overall, patient survival for resection versus ITT patients was similar (5-year survival of 53.0% vs 52.0%, not significant). However, for HCC patients with model end-stage liver disease (MELD) scores less than 10 and who radiologically met Milan or UCSF (University of California, San Francisco) criteria, 1-year and 5-year survival rates were significantly improved in resected patients. For patients with MELD score less than 10 and who met Milan criteria, 1-year and 5-year survival were 92.0% and 63.0% for resection (n = 26) versus 83.0% and 41.0% for ITT (n = 73, P = 0.036). For those with MELD score less than 10 and met UCSF criteria, 1-year and 5-year survival was 94.0% and 62.0% for resection (n = 33) versus 81.0% and 40.0% for ITT (n = 78, P = 0.027).

CONCLUSIONS

Among known HCC patients with preserved liver function, resection was associated with superior patient survival versus transplantation. These results suggest that surgical resection should remain the first line therapy for patients with HCC and compensated liver function who are candidates for resection.

Opposing roles of RAGE and Myd88 signaling in extensive liver resection

In extensive liver resection secondary to primary or metastatic liver tumors, or in living donor liver transplantation, strategies to quell deleterious inflammatory responses and facilitate regeneration are essential. The receptor for advanced glycation endproducts (RAGE) and myeloid differentiating factor 88 (Myd88) are implicated in the inflammatory response. To establish the contributions of RAGE vs. Myd88 signaling in extensive liver resection, we probed the effect of RAGE and/or Myd88, the latter primarily a key transducer of major toll-like receptors and also implicated in interleukin-1 (Il1) signaling, in a murine model of extensive (85%) hepatectomy. We report that, although Myd88 is thoroughly essential for survival via regulation of NF-κB and TNF-α, deletion of RAGE significantly improved survival compared to wild-type, Myd88-null, or RAGE-null/Myd88-null mice. RAGE opposes Myd88 signaling at multiple levels: by suppression of p65 levels, thereby reducing activation of NF-κB and consequent production of cyclin D1, and by suppression of Il6-mediated phosphorylation of Stat3, thereby down-regulating Pim1 and suppressing the hyperplastic response. Further, RAGE-dependent suppression of glyoxalase1, a detoxification pathway for pre-AGEs, enhances AGE levels and suppresses Il6 action. We conclude that blockade of RAGE may rescue liver remnants from the multiple signals that preclude adaptive proliferation triggered primarily by Myd88 signaling pathways.

Is surgical resection superior to transplantation in the treatment of hepatocellular carcinoma?

OBJECTIVE

To compare outcomes for patients with hepatocellular carcinoma (HCC) treated with either liver resection or transplantation.

METHODS

A retrospective, single-institution analysis of 413 HCC patients from 1999 to 2009.

RESULTS

A total of 413 patients with HCC underwent surgical resection (n = 106) and transplantation (n = 270) or were listed without receiving transplantation (n = 37). Excluding transplanted patients with incidental tumors (n = 50), 257 patients with suspected HCC were listed with the intent to transplant (ITT). The median diameter of the largest tumor by radiography was 6.0 cm in resected, 3.0 cm in transplanted, and 3.4 cm in the listed-but-not-transplanted patients. Median time to transplant was 48 days. Recurrence rates were 19.8% for resection and 12.1% for all ITT patients. Overall, patient survival for resection versus ITT patients was similar (5-year survival of 53.0% vs 52.0%, not significant). However, for HCC patients with model end-stage liver disease (MELD) scores less than 10 and who radiologically met Milan or UCSF (University of California, San Francisco) criteria, 1-year and 5-year survival rates were significantly improved in resected patients. For patients with MELD score less than 10 and who met Milan criteria, 1-year and 5-year survival were 92.0% and 63.0% for resection (n = 26) versus 83.0% and 41.0% for ITT (n = 73, P = 0.036). For those with MELD score less than 10 and met UCSF criteria, 1-year and 5-year survival was 94.0% and 62.0% for resection (n = 33) versus 81.0% and 40.0% for ITT (n = 78, P = 0.027).

CONCLUSIONS

Among known HCC patients with preserved liver function, resection was associated with superior patient survival versus transplantation. These results suggest that surgical resection should remain the first line therapy for patients with HCC and compensated liver function who are candidates for resection.

STAT3 activation in skeletal muscle links muscle wasting and the acute phase response in cancer cachexia

Background

Cachexia, or weight loss despite adequate nutrition, significantly impairs quality of life and response to therapy in cancer patients. In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response. Acute phase proteins, including fibrinogen and serum amyloid A (SAA) are synthesized by hepatocytes in response to IL-6 as part of the innate immune response. To gain insight into the relationships among these observations, we studied mice with moderate and severe Colon-26 (C26)-carcinoma cachexia.

Methodology/Principal Findings

Moderate and severe C26 cachexia was associated with high serum IL-6 and IL-6 family cytokines and highly similar patterns of skeletal muscle gene expression. The top canonical pathways up-regulated in both were the complement/coagulation cascade, proteasome, MAPK signaling, and the IL-6 and STAT3 pathways. Cachexia was associated with increased muscle pY705-STAT3 and increased STAT3 localization in myonuclei. STAT3 target genes, including SOCS3 mRNA and acute phase response proteins, were highly induced in cachectic muscle. IL-6 treatment and STAT3 activation both also induced fibrinogen in cultured C2C12 myotubes. Quantitation of muscle versus liver fibrinogen and SAA protein levels indicates that muscle contributes a large fraction of serum acute phase proteins in cancer.

Conclusions/Significance

These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer. Through IL-6/STAT3 activation, skeletal muscle is induced to synthesize acute phase proteins, thus establishing a molecular link between the observations of high IL-6, increased acute phase response proteins and muscle wasting in cancer. These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such that amino acids liberated by increased proteolysis in cachexia are synthesized into acute phase proteins and exported into the blood.