Thrombospondin-1 is a novel negative regulator of liver regeneration after partial hepatectomy through transforming growth factor-beta1 activation in mice

Benchmark N-glycoproteomics study of common differential tissue and serum N-glycoproteins of patients with hepatocellular carcinoma

For hepatocellular carcinoma (HCC), N-glycosylation has been proved to be widely involved in various aspects of the disease, including development, metastasis, subtyping, diagnosis and prognosis. The common practice is to discover biomarkers in situ of cancer occurrence (i.e., cancer vs. adjacent tissues) yet to clinically monitor in sera because of non-invasiveness. This study benchmarks N-glycoproteomics characterization of common differential tissue and serum N-glycoproteins of patients with HCC. Differential N-glycosylation in matched tissue and serum samples from the same patients were quantitatively characterized at the intact N-glycopeptide molecular level, and 29 common N-glycoproteins were found. Subcellular localization analysis was carried out to confirm the tissue originality. Secreted N-glycoprotein APOH was up-regulated, and transmembrane and intracellular N-glycoproteins including OSMR, GAT2, CSF-1 and MAGI3 were down-regulated.

Molecular Pathways Governing the Termination of Liver Regeneration

The liver has the unique capacity to regenerate, and up to 70% of the liver can be removed without detrimental consequences to the organism. Liver regeneration is a complex process involving multiple signaling networks and organs. Liver regeneration proceeds through three phases: the initiation phase, the growth phase, and the termination phase. Termination of liver regeneration occurs when the liver reaches a liver-to-body weight that is required for homeostasis, the so-called "hepatostat." The initiation and growth phases have been the subject of many studies. The molecular pathways that govern the termination phase, however, remain to be fully elucidated. This review summarizes the pathways and molecules that signal the cessation of liver regrowth after partial hepatectomy and answers the question, "What factors drive the hepatostat?" SIGNIFICANCE STATEMENT: Unraveling the pathways underlying the cessation of liver regeneration enables the identification of druggable targets that will allow us to gain pharmacological control over liver regeneration. For these purposes, it would be useful to understand why the regenerative capacity of the liver is hampered under certain pathological circumstances so as to artificially modulate the regenerative processes (e.g., by blocking the cessation pathways) to improve clinical outcomes and safeguard the patient's life.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Approaching Thrombospondin-1 as a Potential Target for Mesenchymal Stromal Cells to Support Liver Regeneration after Partial Hepatectomy in Mouse and Humans

Extended liver resection carries the risk of post-surgery liver failure involving thrombospondin-1-mediated aggravation of hepatic epithelial plasticity and function. Mesenchymal stromal cells (MSCs), by interfering with thrombospondin-1 (THBS1), counteract hepatic dysfunction, though the mechanisms involved remain unknown. Herein, two-thirds partial hepatectomy in mice increased hepatic THBS1, downstream transforming growth factor-β3, and perturbation of liver tissue homeostasis. All these events were ameliorated by hepatic transfusion of human bone marrow-derived MSCs. Treatment attenuated platelet and macrophage recruitment to the liver, both major sources of THBS1. By mitigating THBS1, MSCs muted surgery-induced tissue deterioration and dysfunction, and thus supported post-hepatectomy regeneration. After liver surgery, patients displayed increased tissue THBS1, which is associated with functional impairment and may indicate a higher risk of post-surgery complications. Since liver dysfunction involving THBS1 improves with MSC treatment in various animal models, it seems feasible to also modulate THBS1 in humans to impede post-surgery acute liver failure.

Thrombospondin 1 enhances systemic inflammation and disease severity in acute-on-chronic liver failure

BACKGROUND

The key role of thrombospondin 1 (THBS1) in the pathogenesis of acute-on-chronic liver failure (ACLF) is unclear. Here, we present a transcriptome approach to evaluate THBS1 as a potential biomarker in ACLF disease pathogenesis.

METHODS

Biobanked peripheral blood mononuclear cells (PBMCs) from 330 subjects with hepatitis B virus (HBV)-related etiologies, including HBV-ACLF, liver cirrhosis (LC), and chronic hepatitis B (CHB), and normal controls (NC) randomly selected from the Chinese Group on the Study of Severe Hepatitis B (COSSH) prospective multicenter cohort underwent transcriptome analyses (ACLF = 20; LC = 10; CHB = 10; NC = 15); the findings were externally validated in participants from COSSH cohort, an ACLF rat model and hepatocyte-specific THBS1 knockout mice.

RESULTS

THBS1 was the top significantly differentially expressed gene in the PBMC transcriptome, with the most significant upregulation in ACLF, and quantitative polymerase chain reaction (ACLF = 110; LC = 60; CHB = 60; NC = 45) was used to verify that THBS1 expression corresponded to ACLF disease severity outcome, including inflammation and hepatocellular apoptosis. THBS1 showed good predictive ability for ACLF short-term mortality, with an area under the receiver operating characteristic curve (AUROC) of 0.8438 and 0.7778 at 28 and 90 days, respectively. Enzyme-linked immunosorbent assay validation of the plasma THBS1 using an expanded COSSH cohort subjects (ACLF = 198; LC = 50; CHB = 50; NC = 50) showed significant correlation between THBS1 with ALT and γ-GT (P = 0.01), and offered a similarly good prognostication predictive ability (AUROC = 0.7445 and 0.7175) at 28 and 90 days, respectively. ACLF patients with high-risk short-term mortality were identified based on plasma THBS1 optimal cut-off value (< 28 µg/ml). External validation in ACLF rat serum and livers confirmed the functional association between THBS1, the immune response and hepatocellular apoptosis. Hepatocyte-specific THBS1 knockout improved mouse survival, significantly repressed major inflammatory cytokines, enhanced the expression of several anti-inflammatory mediators and impeded hepatocellular apoptosis.

CONCLUSIONS

THBS1 might be an ACLF disease development-related biomarker, promoting inflammatory responses and hepatocellular apoptosis, that could provide clinicians with a new molecular target for improving diagnostic and therapeutic strategies.

Hyperglycaemia induces metabolic reprogramming into a glycolytic phenotype and promotes epithelial-mesenchymal transitions via YAP/TAZ-Hedgehog signalling axis in pancreatic cancer

BACKGROUND

Hyperglycaemia is a well-known initial symptom in patients with pancreatic ductal adenocarcinoma (PDAC). Metabolic reprogramming in cancer, described as the Warburg effect, can induce epithelial-mesenchymal transition (EMT).

METHODS

The biological impact of hyperglycaemia on malignant behaviour in PDAC was examined by in vitro and in vivo experiments.

RESULTS

Hyperglycaemia promoted EMT by inducing metabolic reprogramming into a glycolytic phenotype via yes-associated protein (YAP)/PDZ-binding motif (TAZ) overexpression, accompanied by GLUT1 overexpression and enhanced phosphorylation Akt in PDAC. In addition, hyperglycaemia enhanced chemoresistance by upregulating ABCB1 expression and triggered PDAC switch into pure basal-like subtype with activated Hedgehog pathway (GLI1 high, GATA6 low expression) through YAP/TAZ overexpression. PDAC is characterised by abundant stroma that harbours tumour-promoting properties and chemoresistance. Hyperglycaemia promotes the production of collagen fibre-related proteins (fibronectin, fibroblast activation protein, COL1A1 and COL11A1) by stimulating YAP/TAZ expression in cancer-associated fibroblasts (CAFs). Knockdown of YAP and/or TAZ or treatment with YAP/TAZ inhibitor (K975) abolished EMT, chemoresistance and a favourable tumour microenvironment even under hyperglycemic conditions in vitro and in vivo.

CONCLUSION

Hyperglycaemia induces metabolic reprogramming into glycolytic phenotype and promotes EMT via YAP/TAZ-Hedgehog signalling axis, and YAP/TAZ could be a novel therapeutic target in PDAC.

Thrombospondin-1 overexpression stimulates loss of Smad4 and accelerates malignant behavior via TGF-β signal activation in pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is characterized by abundant stroma and cancer-associated fibroblasts (CAFs) provide a favorable tumor microenvironment. Smad4 is known as tumor suppressor in several types of cancers including PDAC, and loss of Smad4 triggers accelerated cell invasiveness and metastatic potential. The thrombospondin-1 (TSP-1) can act as a major activator of latent transforming growth factor-β (TGF-β) in vivo. However, the roles of TSP-1 and the mediator of Smad4 loss and TGF-β signal activation during PDAC progression have not yet been addressed. The aim is to elucidate the biological role of TSP-1 in PDAC progression.

METHODS AND RESULTS

High substrate stiffness stimulated TSP-1 expression in CAFs, and TSP-1 knockdown inhibited cell proliferation with suppressed profibrogenic and activated stroma-related gene expressions in CAFs. Paracrine TSP-1 treatment for PDAC cells promoted cell proliferation and epithelial mesenchymal transition (EMT) with activated TGF-β signals such as phosphorylated Akt and Smad2/3 expressions. Surprisingly, knockdown of DPC4 (Smad4 gene) induced TSP-1 overexpression with TGF-β signal activation in PDAC cells. Interestingly, TSP-1 overexpression also induced downregulation of Smad4 expression and enhanced cell proliferation in vitro and in vivo. Treatment with LSKL peptide, which antagonizes TSP-1-mediated latent TGF-β activation, attenuated cell proliferation, migration and chemoresistance with enhanced apoptosis in PDAC cells.

CONCLUSIONS

TSP-1 derived from CAFs stimulates loss of Smad4 expression in cancer cells and accelerates malignant behavior by TGF-β signal activation in PDAC. TSP-1 could be a novel therapeutic target, not only for CAFs in stiff stroma, but also for cancer cells in the PDAC microenvironment.

Assessment for the minimal invasiveness of laparoscopic liver resection by interleukin-6 and thrombospondin-1

BACKGROUND

Laparoscopic surgery has been introduced as a minimally invasive technique for the treatment of various field. However, there are few reports that have scientifically investigated the minimally invasive nature of laparoscopic liver resection (LLR).

AIM

To investigate whether LLR is scientifically less invasive than open liver resection.

METHODS

During December 2011 to April 2015, blood samples were obtained from 30 patients who treated with laparoscopic (n = 10, 33%) or open (n = 20, 67%) partial liver resection for liver tumor. The levels of serum interleukin-6 (IL-6) and plasma thrombospondin-1 (TSP-1) were measured using ELISA kit at four time points including preoperative, immediate after operation, postoperative day 1 (POD1) and POD3. Then, we investigated the impact of the operative approaches during partial hepatectomy on the clinical time course including IL-6 and TSP-1.

RESULTS

Serum level of IL-6 on POD1 in laparoscopic hepatectomy was significantly lower than those in open hepatectomy (8.7 vs 30.3 pg/mL, respectively) (P = 0.003). Plasma level of TSP-1 on POD3 in laparoscopic hepatectomy was significantly higher than those in open hepatectomy (1704.0 vs 548.3 ng/mL, respectively) (P = 0.009), and have already recovered to preoperative level in laparoscopic approach. In patients with higher IL-6 Levels on POD1, plasma level of TSP-1 on POD3 was significantly lower than those in patients with lower IL-6 Levels on POD1. Multivariate analysis showed that open approach was the only independent factor related to higher level of IL-6 on POD1 [odds ratio (OR), 7.48; 95% confidence interval (CI): 1.28-63.3; P = 0.02]. Furthermore, the higher level of serum IL-6 on POD1 was significantly associated with lower level of plasm TSP-1 on POD3 (OR, 5.32; 95%CI: 1.08-32.2; P = 0.04) in multivariate analysis.

CONCLUSION

In partial hepatectomy, laparoscopic approach might be minimally invasive surgery with less IL-6 production compared to open approach.

Mesenchymal stromal cells mitigate liver damage after extended resection in the pig by modulating thrombospondin-1/TGF-β

Post-surgery liver failure is a serious complication for patients after extended partial hepatectomies (ePHx). Previously, we demonstrated in the pig model that transplantation of mesenchymal stromal cells (MSC) improved circulatory maintenance and supported multi-organ functions after 70% liver resection. Mechanisms behind the beneficial MSC effects remained unknown. Here we performed 70% liver resection in pigs with and without MSC treatment, and animals were monitored for 24 h post surgery. Gene expression profiles were determined in the lung and liver. Bioinformatics analysis predicted organ-independent MSC targets, importantly a role for thrombospondin-1 linked to transforming growth factor-β (TGF-β) and downstream signaling towards providing epithelial plasticity and epithelial-mesenchymal transition (EMT). This prediction was supported histologically and mechanistically, the latter with primary hepatocyte cell cultures. MSC attenuated the surgery-induced increase of tissue damage, of thrombospondin-1 and TGF-β, as well as of epithelial plasticity in both the liver and lung. This suggests that MSC ameliorated surgery-induced hepatocellular stress and EMT, thus supporting epithelial integrity and facilitating regeneration. MSC-derived soluble factor(s) did not directly interfere with intracellular TGF-β signaling, but inhibited thrombospondin-1 secretion from thrombocytes and non-parenchymal liver cells, therewith obviously reducing the availability of active TGF-β.

Improving Liver Graft Function Using CD47 Blockade in the Setting of Normothermic Machine Perfusion

BACKGROUND

Towards the goal of utilizing more livers for transplantation, transplant centers are looking to increase the use of organs from "marginal" donors. Livers from these donors, however, have been shown to be more susceptible to preservation and reperfusion injury.

METHODS

Using a porcine model of donation after circulatory death (DCD), we studied the use of antibody-mediated CD47 blockade to further improve liver graft function undergoing normothermic machine perfusion. Livers from 20 pigs (5 per group) were brought under either 30 or 60 minutes of warm ischemia time (WIT) followed by the administration of CD47mAb treatment or IgG control antibodies and 6 hours of normothermic extracorporeal liver perfusion (NELP).

RESULTS

After 6 hours of NELP, CD47mAb-treated livers with 30 or 60 minutes WIT had significantly lower ALT levels and higher bile production compared to their respective control groups. Blockade of the CD47 signaling pathway resulted in significantly lower TSP-1 protein levels, lower expression of Caspase-3, and higher expression of pERK.

CONCLUSIONS

These findings suggested that CD47mAb treatment decreases ischemia/reperfusion injury through CD47/TSP-1 signaling downregulation and the presence of necrosis/apoptosis after reperfusion, and could increase liver regeneration during normothermic perfusion of the liver.Supplemental Visual Abstract; http://links.lww.com/TP/C146.

Far upstream element-binding protein 1 facilitates hepatocellular carcinoma invasion and metastasis

Previous research suggests that far upstream element-binding protein 1 (FUBP1) plays an important role in various tumors including epatocellular carcinoma (HCC). However, the role of FUBP1 in liver cancer remains controversial, and the regulatory pathway by FUBP1 awaits to be determined. This study aims to identify the role of FUBP1 in HCC progression. Our result shows that the high level of FUBP1 expression in HCC predicts poor prognosis after surgery. Overexpression of FUBP1 promotes HCC proliferation, invasion, and metastasis by activating transforming growth factor-β (TGF-β)/Smad pathway and enhancing epithelial-mesenchymal transition (EMT) in vitro and in vivo. Inhibitor of Thrombospondin-1 (LSKL) could inhibit HCC proliferation and invasion in vitro and in vivo by blocking the activation of TGF-β/Smad pathway mediated by thrombospondin-1 (THBS1). Our study identified the critical role of FUBP1-THBS1-TGF-β signaling axis in HCC and provides potentially new therapeutic modalities in HCC.

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

Chronic liver disease when accompanied by underlying fibrosis, is characterized by an accumulation of extracellular matrix (ECM) proteins and chronic inflammation. Although traditionally considered as a passive and largely architectural structure, the ECM is now being recognized as a source of potent damage-associated molecular pattern (DAMP)s with immune-active peptides and domains. In parallel, the ECM anchors a range of cytokines, chemokines and growth factors, all of which are capable of modulating immune responses. A growing body of evidence shows that ECM proteins themselves are capable of modulating immunity either directly via ligation with immune cell receptors including integrins and TLRs, or indirectly through release of immunoactive molecules such as cytokines which are stored within the ECM structure. Notably, ECM deposition and remodeling during injury and fibrosis can result in release or formation of ECM-DAMPs within the tissue, which can promote local inflammatory immune response and chemotactic immune cell recruitment and inflammation. It is well described that the ECM and immune response are interlinked and mutually participate in driving fibrosis, although their precise interactions in the context of chronic liver disease are poorly understood. This review aims to describe the known pro-/anti-inflammatory and fibrogenic properties of ECM proteins and DAMPs, with particular reference to the immunomodulatory properties of the ECM in the context of chronic liver disease. Finally, we discuss the importance of developing novel biotechnological platforms based on decellularized ECM-scaffolds, which provide opportunities to directly explore liver ECM-immune cell interactions in greater detail.

CD44 expression enhances chemoresistance and implies occult micrometastases after conversion hepatectomy for initially unresectable colorectal liver metastases

AIM

The objective of this study was to examine the clinical and biological significance of CD44 expression in conversion hepatectomy for initially unresectable colorectal liver metastases.

METHODS

Fifty-four patients who received chemotherapy followed by hepatectomy (conversion hepatectomy) for initially unresectable liver metastases were enrolled. CD44 expression and its clinical significance were examined in 52 resected specimens; two specimens revealed no residual cancer cells. The biological significance of CD44 expression in the chemoresistance response to fluorouracil, oxaliplatin or irinotecan, three major anti-cancer agents for colon cancer in the clinical setting, was examined using colon cancer cell lines.

RESULTS

Membrane CD44 expression in the residual cancer cells after chemotherapy for colorectal liver metastases was detectable in 19 patients (37%), and was significantly associated with high proliferative activity represented by Ki-67 expression (P = 0.003). CD44 expression was also significantly associated with shorter disease-free survival and worse overall survival after hepatectomy (hazard ratio and P-values were 2.570, 0.007 and 3.457, 0.026, respectively). In SW480 and HT29 colon cancer cells, siRNA-mediated CD44 knockdown attenuated cell growth. Additionally, CD44 knockdown overcame chemoresistance in response to fluorouracil and oxaliplatin with enhanced apoptosis and p27 upregulation, respectively. For irinotecan, CD44 knockdown showed no additional effect in chemoresistance.

CONCLUSIONS

CD44 enhances chemoresistance in response to anti-cancer drugs (fluorouracil and oxaliplatin) in colon cancer cells. CD44 expression in liver metastases after chemotherapy implies the presence of occult micrometastases and is a worse prognostic factor in patients with conversion hepatectomy for initially unresectable colorectal liver metastases.

Enhanced thrombospondin-1 causes dysfunction of vascular endothelial cells derived from Fabry disease-induced pluripotent stem cells

BACKGROUND

Fabry disease (FD) is a recessive X-linked lysosomal storage disorder caused by α-galactosidase A (GLA) deficiency. Although the mechanism is unclear, GLA deficiency causes an accumulation of globotriaosylceramide (Gb3), leading to vasculopathy.

METHODS

To explore the relationship between the accumulation of Gb3 and vasculopathy, induced pluripotent stem cells generated from four Fabry patients (FD-iPSCs) were differentiated into vascular endothelial cells (VECs). Genome editing using CRISPR-Cas9 system was carried out to correct the GLA mutation or to delete Thrombospondin-1 (TSP-1). Global transcriptomes were compared between wild-type (WT)- and FD-VECs by RNA-sequencing analysis.

FINDINGS

Here, we report that overexpression of TSP-1 contributes to the dysfunction of VECs in FD. VECs originating from FD-iPSCs (FD-VECs) showed aberrant angiogenic functionality even upon treatment with recombinant α-galactosidase. Intriguingly, FD-VECs produced more p-SMAD2 and TSP-1 than WT-VECs. We also found elevated TSP-1 in the peritubular capillaries of renal tissues biopsied from FD patients. Inhibition of SMAD2 signaling or knock out of TSP-1 (TSP-1-/-) rescues normal vascular functionality in FD-VECs, like in gene-corrected FD-VECs. In addition, the enhanced oxygen consumption rate is reduced in TSP-1-/- FD-VECs.

INTERPRETATION

The overexpression of TSP-1 secondary to Gb3 accumulation is primarily responsible for the observed FD-VEC dysfunction. Our findings implicate dysfunctional VEC angiogenesis in the peritubular capillaries in some of the complications of Fabry disease.

FUNDING

This study was supported by grant 2018M3A9H1078330 from the National Research Foundation of the Republic of Korea.

Thrombospondin-1 Exacerbates Acute Liver Failure and Hepatic Encephalopathy Pathology in Mice by Activating Transforming Growth Factor β1

Severe hepatic insults can lead to acute liver failure and hepatic encephalopathy (HE). Transforming growth factor β1 (TGFβ1) has been shown to contribute to HE during acute liver failure; however, TGFβ1 must be activated to bind its receptor and generate downstream effects. One protein that can activate TGFβ1 is thrombospondin-1 (TSP-1). Therefore, the aim of this study was to assess TSP-1 during acute liver failure and HE pathogenesis. C57Bl/6 or TSP-1 knockout (TSP-1-/-) mice were injected with azoxymethane (AOM) to induce acute liver failure and HE. Liver damage, neurologic decline, and molecular analyses of TSP-1 and TGFβ1 signaling were performed. AOM-treated mice had increased TSP-1 and TGFβ1 mRNA and protein expression in the liver. TSP-1-/- mice administered AOM had reduced liver injury as assessed by histology and serum transaminase levels compared with C57Bl/6 AOM-treated mice. TSP-1-/- mice treated with AOM had reduced TGFβ1 signaling that was associated with less hepatic cell death as assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and cleaved caspase 3 expression. TSP-1-/- AOM-treated mice had a reduced rate of neurologic decline, less cerebral edema, and a decrease in microglia activation in comparison with C57Bl/6 mice treated with AOM. Taken together, TSP-1 is an activator of TGFβ1 signaling during AOM-induced acute liver failure and contributes to both liver pathology and HE progression.

Thrombospondin-1: A Key Protein That Induces Fibrosis in Diabetic Complications

Fibrosis accompanies most common pathophysiological features of diabetes complications in different organs. It is characterized by an excessive accumulation of extracellular matrix (ECM) components, the response to which contributes to inevitable organ injury. The extracellular protein thrombospondin-1 (TSP-1), a kind of extracellular glycoprotein, is upregulated by the increased activity of some transcription factors and results in fibrosis by activating multiple pathways in diabetes. The results of studies from our team and other colleagues indicate that TSP-1 is associated with the pathological process leading to diabetic complications and is considered to be the most important factor in fibrosis. This review summarizes the molecular mechanism of increased TSP-1 induced by hyperglycemia and the role of TSP-1 in fibrosis during the development of diabetes complications.

The Predictive Role of Tenascin-C and Cellular Communication Network Factor 3 (CCN3) in Post Hepatectomy Liver Failure in a Rat Model and 50 Patients Following Partial Hepatectomy

Background

Matricellular proteins of the extracellular matrix (ECM) include tenascin-C (TNC) and cellular communication network factor 3 (CCN3). This study aimed to investigate the role of TNC and CCN3 as prognostic factors for post hepatectomy liver failure (PHLF) in a rat model of partial hepatectomy and 50 patients following partial hepatectomy.

Material/Methods

Sprague-Dawley rats underwent 85% (n=53) or 90% hepatectomy (n=53) in the partial hepatectomy (PHx) model. TNC and CCN3 mRNA expression in residual liver tissue was evaluated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and enzyme-linked immunoassay (ELISA) determined the serum levels of TNC and CCN3. In 50 patients who underwent partial hepatectomy, TNC and CCN3 serum levels were measured on postoperative day 1 and day 3.

Results

In the rat partial hepatectomy model, mRNA and serum levels of TNC and CCN3 were significantly increased within the first 24 h, and were higher in the 90% PHx group compared with the 85% PHx group. Fifty patients who underwent partial hepatectomy, included patients with PHLF (n=12) and patients without PHLF (n=38). Multivariate analysis confirmed that serum levels on postoperative day 3 TNC^high+CCN3^high was a significant predictor of PHLF, which was associated with more than twice the risk of severe morbidity when compared with the low-risk patients (80% vs. 30%) and a significantly longer hospital stay (17 days vs. 8 days).

Conclusions

Further studies are needed to evaluate the potential role of the matricellular proteins, TNC and CCN3 as early clinical predictors for PHLF.

Incomplete Differentiation of Engrafted Bone Marrow Endothelial Progenitor Cells Initiates Hepatic Fibrosis in the Rat

Normal liver sinusoidal endothelial cells (LSECs) promote quiescence of hepatic stellate cells (HSCs). Prior to fibrosis, LSECs undergo capillarization, which is permissive for HSC activation, the proximate event in hepatic fibrosis. The aims of this study were to elucidate the nature of and mechanisms leading to capillarization and to determine how LSECs promote HSC quiescence and why "capillarized LSECs" lose control of HSC activation. The contribution of bone marrow (BM) endothelial progenitor cells to capillarization was identified using rats transplanted with transgenic enhanced green fluorescent protein-positive BM. Shotgun proteomics and informatics were used to identify the LSEC mediator that maintains HSC quiescence. The study shows that capillarization is due to repair of injured LSECs by BM endothelial progenitors that engraft but fail to fully mature. Lack of maturation of BM-derived LSECs is due to cell autonomous pathways that inhibit the nitric oxide pathway. We identify heparin binding epidermal growth factor-like growth factor (HB-EGF) as the signal that maintains HSC quiescence and show that immature LSECs are unable to shed HB-EGF from the cytosolic membrane. Conclusion: Chronic liver injury can recruit BM progenitors of LSECs that engraft and fail to fully differentiate, which creates an environment that is permissive for hepatic fibrosis; elucidation of these early events in the fibrotic process will provide targets for treatment of hepatic fibrosis.

Subcutaneous Inoculation of Echinococcus multilocularis Induces Delayed Regeneration after Partial Hepatectomy

Alveolar echinococcosis (AE) is caused by the larval stage of echinococcus multilocularis (E. multilocularis), and hepatectomy is the main modality in hepatic AE patients. Liver regeneration after partial hepatectomy (PHx) in such patients is challenging, and further investigation is needed. Thus far, knowledge regarding the possible impact of E. multilocularis on liver regeneration after PHx is limited. Herein, a subcutaneous infection model of E. multilocularis was developed in C57 BL/6 mice, and after 3 months, PHx was performed. Plasma and liver samples were harvested under inhalational isofluorane (2%) anaesthesia at designated post-PHx time points (0, 24, 48, 96 and 168 h). The parameters included the future remnant liver/body weight ratio (FLR/BW), liver function tests (AST and ALT) and related cytokines (TNF-α, IL-6, Factor V, HMGB1, TGF-β, TSP-1, and TLR4) and proteins (MyD88 and STAT3). To assess the proliferation intensity of hepatocytes, BrdU, Ki67 and PAS staining were carried out in regenerated liver tissue. The FLR/BW in the infected group from 48 h after surgery was lower than that in the control group. The BrdU positive hepatocyte proportions reached their peak at 48 h in the control group and 96 h in the infected group and then gradually decreased. During the first 48 h after surgery, both the AST and ALT levels in the infected group were lower; however, these levels were altered from 96 h after surgery. In the infected group, the concentrations and mRNA expression levels of the pre-inflammatory cytokines TNF-α and IL-6 demonstrated a delayed peak. Moreover, post-operatively, the TGF-β and TSP-1 levels showed high levels in the infected group at each different time-point compared to those in the control group; however, high levels of TGF-β were observed at 96 h in the control group. The MyD88 and STAT3 protein expression levels in the infected group were markedly higher than those in the control group 96 h after surgery. Delayed liver regeneration after PHx was observed in the C57 BL/6 mice with the subcutaneous infection of E. multilocularis in the current study. This phenomenon could be partially explained by the alteration in the pro-inflammatory cytokines in the immunotolerant milieu induced by chronic E. multilocularis infection.

Elevated ADAMTS13 Activity is Associated with Poor Postoperative Outcome in Patients Undergoing Liver Resection

Recently, von-Willebrand-Factor (vWF) has been shown to correlate with postoperative liver dysfunction (LD). Accordingly, “disintegrin-like metalloprotease with thrombospondin type1 motif” (ADAMTS13) is known to cleave vWF in less active fragments. Thus, we aimed to evaluate the diagnostic potential of ADAMTS13-activity (ADAMTS13-AC) to identify patients with postoperative LD after hepatectomy. Accordingly 37 patients undergoing hepatectomy for different neoplastic entities were included in this study. Plasma ADAMTS13-AC and vWF-Ag were measured 1 day prior to (preOP), 1 and 5 days (POD1/5) after hepatectomy. In accordance to the ISGLS-criteria LD was prospectively recorded. In this context, perioperative ADAMTS13-AC- and vWF-Ag/ADAMTS13-AC-ratio- levels revealed a significant increase after hepatectomy. Accordingly, elevated vWF-Ag/ADAMTS13-AC-ratio significantly predicted LD (preOP AUC: 0.75, p = 0.02; POD1 AUC: 0.80, p = 0.03). Patients who fulfilled our perioperative vWF-Ag/ADAMTS13-AC-ratio cut-off-levels (preOP: ≥116, POD1: ≥165) suffered from significantly higher incidences of LD (preOP: 70% vs. 30%, p = 0.01; POD1: 83% vs. 17%, p = 0.001). In conclusion, perioperative ADAMTS13-AC measurement may serve as a useful parameter to early detect high-risk patients developing postoperative LD prior to liver resection in patients suffering from hepatic malignancies. Indeed, further investigations have to be performed to consolidate its role as a predictive marker for LD.

Cellular network modeling and single cell gene expression analysis reveals novel hepatic stellate cell phenotypes controlling liver regeneration dynamics

Background

Recent results from single cell gene and protein regulation studies are starting to uncover the previously underappreciated fact that individual cells within a population exhibit high variability in the expression of mRNA and proteins (i.e., molecular variability). By combining cellular network modeling, and high-throughput gene expression measurements in single cells, we seek to reconcile the high molecular variability in single cells with the relatively low variability in tissue-scale gene and protein expression and the highly coordinated functional responses of tissues to physiological challenges. In this study, we focus on relating the dynamic changes in distributions of hepatic stellate cell (HSC) functional phenotypes to the tightly regulated physiological response of liver regeneration.

Results

We develop a mathematical model describing contributions of HSC functional phenotype populations to liver regeneration and test model predictions through isolation and transcriptional characterization of single HSCs. We identify and characterize four HSC transcriptional states contributing to liver regeneration, two of which are described for the first time in this work. We show that HSC state populations change in vivo in response to acute challenges (in this case, 70% partial hepatectomy) and chronic challenges (chronic ethanol consumption). Our results indicate that HSCs influence the dynamics of liver regeneration through steady-state tissue preconditioning prior to an acute insult and through dynamic control of cell state balances. Furthermore, our modeling approach provides a framework to understand how balances among cell states influence tissue dynamics.

Conclusions

Taken together, our combined modeling and experimental studies reveal novel HSC transcriptional states and indicate that baseline differences in HSC phenotypes as well as a dynamic balance of transitions between these phenotypes control liver regeneration responses.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0605-7) contains supplementary material, which is available to authorized users.

Thrombospondin-1 regulation of latent TGF-β activation: A therapeutic target for fibrotic disease

Transforming growth factor-β (TGF-β) is a central player in fibrotic disease. Clinical trials with global inhibitors of TGF-β have been disappointing, suggesting that a more targeted approach is warranted. Conversion of the latent precursor to the biologically active form of TGF-β represents a novel approach to selectively modulating TGF-β in disease, as mechanisms employed to activate latent TGF-β are typically cell, tissue, and/or disease specific. In this review, we will discuss the role of the matricellular protein, thrombospondin 1 (TSP-1), in regulation of latent TGF-β activation and the use of an antagonist of TSP-1 mediated TGF-β activation in a number of diverse fibrotic diseases. In particular, we will discuss the TSP-1/TGF-β pathway in fibrotic complications of diabetes, liver fibrosis, and in multiple myeloma. We will also discuss emerging evidence for a role for TSP-1 in arterial remodeling, biomechanical modulation of TGF-β activity, and in immune dysfunction. As TSP-1 expression is upregulated by factors induced in fibrotic disease, targeting the TSP-1/TGF-β pathway potentially represents a more selective approach to controlling TGF-β activity in disease.

Cylindrospermopsin toxicity in mice following a 90-d oral exposure

Cylindrospermopsin (CYN) is a toxin associated with numerous species of freshwater cyanobacteria throughout the world. It is postulated to have caused an episode of serious illnesses in Australia through treated drinking water, as well as lethal effects in livestock exposed to water from farm ponds. Toxicity included effects indicative of both hepatic and renal dysfunction. In humans, symptoms progressed from initial hepatomegaly, vomiting, and malaise to acidosis and hypokalemia, bloody diarrhea, and hyperemia in mucous membranes. Laboratory animal studies predominantly involved the intraperitoneal (i.p.) route of administration and confirmed this pattern of toxicity with changes in liver enzyme activities and histopathology consistent with hepatic injury and adverse renal effects. The aim of this study was designed to assess subchronic oral exposure (90 d) of purified CYN from 75 to 300 µg/kg/d in mouse. At the end of the dosing period, examinations of animals noted (1) elevated organ to body weight ratios of liver and kidney at all dose levels, (2) treatment-related increases in serum alanine aminotransferase (ALT) activity, (3) decreased blood urea nitrogen (BUN) and cholesterol concentrations in males, and (4) elevated monocyte counts in both genders. Histopathological alterations included hepatocellular hypertrophy and cord disruption in the liver, as well as renal cellular hypertrophy, tubule dilation, and cortical tubule lesions that were more prominent in males. A series of genes were differentially expressed including Bax (apoptosis), Rpl6 (tissue regeneration), Fabp4 (fatty acid metabolism), and Proc (blood coagulation). Males were more sensitive to many renal end points suggestive of toxicity. At the end of exposure, toxicity was noted at all dose levels, and the 75 µg/kg group exhibited significant effects in liver and kidney/body weight ratios, reduced BUN, increased serum monocytes, and multiple signs of histopathology indicating that a no-observed-adverse-effect level could not be determined for any dose level.

Splenectomy after partial hepatectomy accelerates liver regeneration in mice by promoting tight junction formation via polarity protein Par 3-aPKC

AIMS

Several experimental studies have demonstrated that removal of the spleen accelerates liver regeneration after partial hepatectomy. While the mechanism of splenectomy promotes liver regeneration by the improvement of the formation of tight junction and the establishment of hepatocyte polarity is still unknown.

MAIN METHODS

We analyzed the cytokines, genes and proteins expression between 70% partial hepatectomy mice (PHx) and simultaneous 70% partial hepatectomy and splenectomy mice (PHs) at predetermined timed points.

KEY FINDINGS

Compared with the PHx group mice, splenectomy accelerated hepatocyte proliferation in PHs group. The expression of Zonula occludens-1 (ZO-1) indicated that splenectomy promotes the formation of tight junction during liver regeneration. TNF-α, IL-6, HGF, TSP-1 and TGF-β1 were essential factors for the formation of tight junction and the establishment of hepatocytes polarity in liver regeneration. After splenectomy, Partitioning defective 3 homolog (Par 3) and atypical protein kinase C (aPKC) regulate hepatocyte localization and junctional structures in regeneration liver.

SIGNIFICANCE

Our data suggest that the time course expression of TNF-α, IL-6, HGF, TSP-1, and TGF-β1 and the change of platelets take part in liver regeneration. Combination with splenectomy accelerates liver regeneration by improvement of the tight junction formation which may help to establish hepatocyte polarity via Par 3-aPKC. This may provide a clue for us that splenectomy could accelerate liver regeneration after partial hepatectomy of hepatocellular carcinoma and living donor liver transplantation.

Deficiency of periostin impairs liver regeneration in mice after partial hepatectomy

Periostin (Postn) is a crucial extracellular remodeling factor that has been implicated in the pathogenesis of hepatic inflammation, fibrosis, non-alcoholic fatty liver disease and liver cancer. However, the role of Postn in liver regeneration remains unclear. Here, we demonstrate that Postn mRNA and protein levels are significantly upregulated in the mice after 2/3 partial hepatectomy (PHx). Compared with wild-type mice, Postn-deficient mice exhibit lower liver/body weight ratio and less Ki67-positive cells at days 2, 8 and 14 after PHx. Macrophage infiltration and the levels of TNF-α, IL-6 and HGF in the livers of Postn-deficient mice are significantly decreased compared with wild-type mice one day after PHx. In addition, overexpression of Postn leads to higher liver/body weight ratio and more Ki67-positive cells in the livers of mice and promotes hepatocyte proliferation in vitro. Moreover, liver sinusoidal endothelial cells, biliary epithelial cells and hepatocytes can express Postn after PHx, and Postn deficiency impairs angiogenesis during liver regeneration. Our findings indicate that Postn deficiency impairs liver regeneration in mice after PHx and Postn might be a novel promoter for liver regeneration.

The pathogenesis of diclofenac induced immunoallergic hepatitis in a canine model of liver injury

Hypersensitivity to non-steroidal anti-inflammatory drugs is a common adverse drug reaction and may result in serious inflammatory reactions of the liver. To investigate mechanism of immunoallergic hepatitis beagle dogs were given 1 or 3 mg/kg/day (HD) oral diclofenac for 28 days. HD diclofenac treatment caused liver function test abnormalities, reduced haematocrit and haemoglobin but induced reticulocyte, WBC, platelet, neutrophil and eosinophil counts. Histopathology evidenced hepatic steatosis and glycogen depletion, apoptosis, acute lobular hepatitis, granulomas and mastocytosis. Whole genome scans revealed 663 significantly regulated genes of which 82, 47 and 25 code for stress, immune response and inflammation. Immunopathology confirmed strong induction of IgM, the complement factors C3&B, SAA, SERPING1 and others of the classical and alternate pathway. Alike, marked expression of CD205 and CD74 in Kupffer cells and lymphocytes facilitate antigen presentation and B-cell differentiation. The highly induced HIF1A and KLF6 protein expression in mast cells and macrophages sustain inflammation. Furthermore, immunogenomics discovered 24, 17, 6 and 11 significantly regulated marker genes to hallmark M1/M2 polarized macrophages, lymphocytic and granulocytic infiltrates; note, the latter was confirmed by CAE staining. Other highly regulated genes included alpha-2-macroglobulin, CRP, hepcidin, IL1R1, S100A8 and CCL20. Diclofenac treatment caused unprecedented induction of myeloperoxidase in macrophages and oxidative stress as shown by SOD1/SOD2 immunohistochemistry. Lastly, bioinformatics defined molecular circuits of inflammation and consisted of 161 regulated genes.

Altogether, the mechanism of diclofenac induced liver hypersensitivity reactions involved oxidative stress, macrophage polarization, mastocytosis, complement activation and an erroneous programming of the innate and adaptive immune system.

Simvastatin augments activation of liver regeneration through attenuating transforming growth factor-β1 induced-apoptosis in obstructive jaundice rats

Obstructive jaundice, owing to biliary obstruction, has been illustrated to trigger various biochemical, histological and immunological changes, leading to liver damage or even failure. The detailed molecular mechanism of simvastatin (Sim) involvement in liver regeneration during obstructive jaundice progression remains poorly elucidated. In the present study, an acute obstructive jaundice rat model was established by ligation and division of common bile duct, which was used to investigate the effects of Sim as a hepatoprotective treatment. Male Sprague-Dawley rats were randomly divided into four groups: Sham-operated, bile duct ligation (BDL) plus saline treatment [0.02 mg/kg/d, intraperitoneally (i.p.)], BDL plus low-dose Sim treatment (0.02 mg/kg, i.p.) and BDL plus high-dose Sim treatment (0.2 mg/kg, i.p.). During this experiment, the BDL+normal saline (NS) group demonstrated increased levels of transforming growth factor-β1 (TGF-β1) expression. Furthermore, Sim-treated animals demonstrated significantly downregulated TGF-β1 expression and improved liver function vs. the BDL+NS group, indicating a TGF-β1 antagonizing function. Additionally, Sim increased hepatocyte DNA synthesis in BDL rats compared to both the BDL+NS and Sham group. Apoptosis was increased in BDL+NS compared to the Sham group, and Sim markedly reduced hepatocyte apoptosis in the BDL group. Moreover, analysis of TGF-β1 signaling pathways demonstrated that there was an increased hepatic TGF-β1 and Smad3 expression in the BDL group, which was attenuated in the presence of Sim. In contrast to TGF-β1, Sim induced the activity of the Smad7 (an inhibitor of TGF-β1 signaling) mRNA and Smad7 protein expression. Sim displays hepatoprotective effects in liver cells via the upregulation of Smad7 expression and impaired TGF-β signaling. Furthermore, the observations of the present study may provide evidence on the mechanism behind Sim blunting TGF-β1 signaling, which is used to ameliorate the complication of liver damage and reduce the mortality rates associated with obstructive jaundice.

β1-Integrin Deletion From the Lens Activates Cellular Stress Responses Leading to Apoptosis and Fibrosis

Purpose

Previous research showed that the absence of β1-integrin from the mouse lens after embryonic day (E) 13.5 (β1MLR10) leads to the perinatal apoptosis of lens epithelial cells (LECs) resulting in severe microphthalmia. This study focuses on elucidating the molecular connections between β1-integrin deletion and this phenotype.

Methods

RNA sequencing was performed to identify differentially regulated genes (DRGs) in β1MLR10 lenses at E15.5. By using bioinformatics analysis and literature searching, Egr1 (early growth response 1) was selected for further study. The activation status of certain signaling pathways (focal adhesion kinase [FAK]/Erk, TGF-β, and Akt signaling) was studied via Western blot and immunohistochemistry. Mice lacking both β1-integrin and Egr1 genes from the lenses were created (β1MLR10/Egr1-/-) to study their relationship.

Results

RNA sequencing identified 120 DRGs that include candidates involved in the cellular stress response, fibrosis, and/or apoptosis. Egr1 was investigated in detail, as it mediates cellular stress responses in various cell types, and is recognized as an upstream regulator of numerous other β1MLR10 lens DRGs. In β1MLR10 mice, Egr1 levels are elevated shortly after β1-integrin loss from the lens. Further, pErk1/2 and pAkt are elevated in β1MLR10 LECs, thus providing the potential signaling mechanism that causes Egr1 upregulation in the mutant. Indeed, deletion of Egr1 from β1MLR10 lenses partially rescues the microphthalmia phenotype.

Conclusions

β1-integrin regulates the appropriate levels of Erk1/2 and Akt phosphorylation in LECs, whereas its deficiency results in the overexpression of Egr1, culminating in reduced cell survival. These findings provide insight into the molecular mechanism underlying the microphthalmia observed in β1MLR10 mice.

Thrombospondin-1 expression may be implicated in liver atrophic mechanism due to obstructed portal venous flow

AIM

Liver is an amazing organ that can undergo regenerative and atrophic changes inversely, depending on blood flow conditions. Although the regenerative mechanism has been extensively studied, the atrophic mechanism remains to be elucidated.

METHODS AND RESULTS

To assess the molecular mechanism of liver atrophy due to reduced portal blood flow, we analyzed the gene expressions between atrophic and hypertrophic livers induced by portal vein embolization in three human liver tissues using microarray analyses. Thrombospondin (TSP)-1 is an extracellular protein and a negative regulator of liver regeneration through its activation of the transforming growth factor-β/Smad signaling pathway. TSP-1 was extracted as the most upregulated gene in atrophic liver compared to hypertrophic liver due to portal flow obstruction in human. Liver atrophic and hypertrophic changes were confirmed by HE and proliferating cell nuclear antigen staining and terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling. In an in vivo model with portal ligation, TSP-1 and phosphorylated Smad2 expression were continuously induced at 6 h and thereafter in the portal ligated liver, whereas the induction was transient at 6 h in the portal non-ligated liver. Indeed, while cell proliferation represented by proliferating cell nuclear antigen expression at 48 h was induced in the portal ligated liver, the sinusoidal dilatation and hepatocyte cell death with terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling was detectable at 48 h in the portal ligated liver.

CONCLUSIONS

Obstructed portal flow induces persistent TSP-1 expression and transforming growth factor-β/Smad signal activation in atrophic liver. Thrombospondin-1 may be implicated in the liver atrophic change due to obstructed portal flow as a pro-atrophic factor.

TGF-β activation by bone marrow-derived thrombospondin-1 causes Schistosoma- and hypoxia-induced pulmonary hypertension

Pulmonary arterial hypertension (PAH) is an obstructive disease of the precapillary pulmonary arteries. Schistosomiasis-associated PAH shares altered vascular TGF-β signalling with idiopathic, heritable and autoimmune-associated etiologies; moreover, TGF-β blockade can prevent experimental pulmonary hypertension (PH) in pre-clinical models. TGF-β is regulated at the level of activation, but how TGF-β is activated in this disease is unknown. Here we show TGF-β activation by thrombospondin-1 (TSP-1) is both required and sufficient for the development of PH in Schistosoma-exposed mice. Following Schistosoma exposure, TSP-1 levels in the lung increase, via recruitment of circulating monocytes, while TSP-1 inhibition or knockout bone marrow prevents TGF-β activation and protects against PH development. TSP-1 blockade also prevents the PH in a second model, chronic hypoxia. Lastly, the plasma concentration of TSP-1 is significantly increased in subjects with scleroderma following PAH development. Targeting TSP-1-dependent activation of TGF-β could thus be a therapeutic approach in TGF-β-dependent vascular diseases.

Thrombospondin-1 (TSP-1) activates latent TGF-β in the extracellular matrix. Here the authors show that inappropriate activation of latent TGF-β in murine, bovine and human lung by monocyte-produced TSP-1 causes pulmonary hypertension, and that interference with the activation process prevents disease development.

Proliferation‑inhibiting pathways in liver regeneration (Review)

Liver regeneration, an orchestrated process, is the primary compensatory mechanism following liver injury caused by various factors. The process of liver regeneration consists of three stages: Initiation, proliferation and termination. Proliferation‑promoting factors, which stimulate the recovery of mitosis in quiescent hepatocytes, are essential in the initiation and proliferation steps of liver regeneration. Proliferation‑promoting factors act as the 'motor' of liver regeneration, whereas proliferation inhibitors arrest cell proliferation when the remnant liver reaches a suitable size. Certain proliferation inhibitors are also expressed and activated in the first two steps of liver regeneration. Anti‑proliferation factors, acting as a 'brake', control the speed of proliferation and determine the terminal point of liver regeneration. Furthermore, anti‑proliferation factors function as a 'steering‑wheel', ensuring that the regeneration process proceeds in the right direction by preventing proliferation in the wrong direction, as occurs in oncogenesis. Therefore, proliferation inhibitors to ensure safe and stable liver regeneration are as important as proliferation‑promoting factors. Cytokines, including transforming growth factor‑β and interleukin‑1, and tumor suppressor genes, including p53 and p21, are important members of the proliferation inhibitor family in liver regeneration. Certain anti‑proliferation factors are involved in the process of gene expression and protein modification. The suppression of liver regeneration led by metabolism, hormone activity and pathological performance have been reviewed previously. However, less is known regarding the proliferation inhibitors of liver regeneration and further investigations are required. Detailed information regarding the majority of known anti‑proliferation signaling pathways also remains fragmented. The present review aimed to understand the signalling pathways that inhbit proliferation in the process of liver regeneration.

Role of thrombospondin 1 in liver diseases

Thrombospondin 1 (TSP1) is a matricellular glycoprotein that can be secreted by many cell types. Through binding to extracellular proteins and/or cell surface receptors, TSP1 modulates a variety of cellular functions. Since its discovery in 1971, TSP1 has been found to play important roles in multiple biological processes including angiogenesis, apoptosis, latent transforming growth factor-β activation, and immune regulation. Thrombospondin 1 is also involved in regulating many organ functions. However, the role of TSP1 in liver diseases has not been extensively addressed. In this review, we summarize the findings about the possible role that TSP1 plays in chronic liver diseases focusing on non-alcoholic fatty liver diseases, liver fibrosis, and hepatocellular carcinoma.

Liver resection for cancer: New developments in prediction, prevention and management of postresectional liver failure

Hepatic failure is a feared complication that accounts for up to 75% of mortality after extensive liver resection. Despite improved perioperative care, the increasing complexity and extensiveness of surgical interventions, in combination with an expanding number of resections in patients with compromised liver function, still results in an incidence of postresectional liver failure (PLF) of 1-9%. Preventive measures aim to enhance future remnant liver size and function. Numerous non-invasive techniques to assess liver function and predict remnant liver volume are being developed, along with introduction of novel surgical strategies that augment growth of the future remnant liver. Detection of PLF is often too late and treatment is primarily symptomatic. Current therapeutic research focuses on ([bio]artificial) liver function support and regenerative medicine. In this review we discuss the current state and new developments in prediction, prevention and management of PLF, in light of novel insights into the aetiology of this complex syndrome.

LAY SUMMARY

Liver failure is the main cause of death after partial liver resection for cancer, and is presumably caused by an insufficient quantity and function of the liver remnant. Detection of liver failure is often too late, and current treatment focuses on relieve of symptoms. New research initiatives explore artificial support of liver function and stimulation of regrowth of the remnant liver.

Liver surgery for metastatic colorectal cancer: the surgical oncologist perspective

Neoadjuvant/conversion chemotherapy has emerged as an indispensable tool to achieve resectability of initially unresectable metastatic colorectal cancer and improves oncological outcomes. In parallel, surgical strategy has adopted a more aggressive treatment approach to achieve complete tumor clearance. However, chemotherapy affects liver function and combined with extensive liver resection, morbidity has increased, thereby compromising oncological outcome. There is an imperative need for careful patient selection to optimize patient management. In this review, we discuss available evidence and indications for neoadjuvant treatment in the management of colorectal cancer liver metastases, on preoperative patient selection and identification of high-risk patients, potential treatment strategies to promote postoperative liver regeneration to avoid postoperative morbidity and potentially deleterious side effects of these therapies on tumor growth.

Molecular Cues Guiding Matrix Stiffness in Liver Fibrosis

Tissue and matrix stiffness affect cell properties during morphogenesis, cell growth, differentiation, and migration and are altered in the tissue remodeling following injury and the pathological progression. However, detailed molecular mechanisms underlying alterations of stiffness in vivo are still poorly understood. Recent engineering technologies have developed powerful techniques to characterize the mechanical properties of cell and matrix at nanoscale levels. Extracellular matrix (ECM) influences mechanical tension and activation of pathogenic signaling during the development of chronic fibrotic diseases. In this short review, we will focus on the present knowledge of the mechanisms of how ECM stiffness is regulated during the development of liver fibrosis and the molecules involved in ECM stiffness as a potential therapeutic target for liver fibrosis.

Identification of Pathways in Liver Repair Potentially Targeted by Secretory Proteins from Human Mesenchymal Stem Cells

BACKGROUND

The beneficial impact of mesenchymal stem cells (MSC) on both acute and chronic liver diseases has been confirmed, although the molecular mechanisms behind it remain elusive. We aim to identify factors secreted by undifferentiated and hepatocytic differentiated MSC in vitro in order to delineate liver repair pathways potentially targeted by MSC.

METHODS

Secreted factors were determined by protein arrays and related pathways identified by biomathematical analyses.

RESULTS

MSC from adipose tissue and bone marrow expressed a similar pattern of surface markers. After hepatocytic differentiation, CD54 (intercellular adhesion molecule 1, ICAM-1) increased and CD166 (activated leukocyte cell adhesion molecule, ALCAM) decreased. MSC secreted different factors before and after differentiation. These comprised cytokines involved in innate immunity and growth factors regulating liver regeneration. Pathway analysis revealed cytokine-cytokine receptor interactions, chemokine signalling pathways, the complement and coagulation cascades as well as the Januskinase-signal transducers and activators of transcription (JAK-STAT) and nucleotide-binding oligomerization domain-like receptor (NOD-like receptor) signalling pathways as relevant networks. Relationships to transforming growth factor β (TGF-β) and hypoxia-inducible factor 1-α (HIF1-α) signalling seemed also relevant.

CONCLUSION

MSC secreted proteins, which differed depending on cell source and degree of differentiation. The factors might address inflammatory and growth factor pathways as well as chemo-attraction and innate immunity. Since these are prone to dysregulation in most liver diseases, MSC release hepatotropic factors, potentially supporting liver regeneration.

SARS coronavirus papain-like protease induces Egr-1-dependent up-regulation of TGF-β1 via ROS/p38 MAPK/STAT3 pathway

SARS coronavirus (SARS-CoV) papain-like protease (PLpro) has been identified in TGF-β1 up-regulation in human promonocytes (Proteomics 2012, 12: 3193-205). This study investigates the mechanisms of SARS-CoV PLpro-induced TGF-β1 promoter activation in human lung epithelial cells and mouse models. SARS-CoV PLpro dose- and time-dependently up-regulates TGF-β1 and vimentin in A549 cells. Dual luciferase reporter assays with TGF-β1 promoter plasmids indicated that TGF-β1 promoter region between -175 to -60, the Egr-1 binding site, was responsible for TGF-β1 promoter activation induced by SARS-CoV PLpro. Subcellular localization analysis of transcription factors showed PLpro triggering nuclear translocation of Egr-1, but not NF-κB and Sp-1. Meanwhile, Egr-1 silencing by siRNA significantly reduced PLpro-induced up-regulation of TGF-β1, TSP-1 and pro-fibrotic genes. Furthermore, the inhibitors for ROS (YCG063), p38 MAPK (SB203580), and STAT3 (Stattic) revealed ROS/p38 MAPK/STAT3 pathway involving in Egr-1 dependent activation of TGF-β1 promoter induced by PLpro. In a mouse model with a direct pulmonary injection, PLpro stimulated macrophage infiltration into lung, up-regulating Egr-1, TSP-1, TGF-β1 and vimentin expression in lung tissues. The results revealed that SARS-CoV PLpro significantly triggered Egr-1 dependent activation of TGF-β1 promoter via ROS/p38 MAPK/STAT3 pathway, correlating with up-regulation of pro-fibrotic responses in vitro and in vivo.

Dynamic Change of Total Bilirubin after Portal Vein Embolization is Predictive of Major Complications and Posthepatectomy Mortality in Patients with Hilar Cholangiocarcinoma

OBJECTIVES

This study aims to evaluate the role of dynamic change in total bilirubin after portal vein embolization (PVE) in predicting major complications and 30-day mortality in patients with hilar cholangiocarcinoma (HCCA).

METHODS

Retrospective analysis of prospectively maintained data of 64 HCCA patients who underwent PVE before hepatectomy in our institution was used. Total bilirubin and other parameters were measured daily in peri-PVE period. The difference between them and the baseline value from days 0-5 to day -1 (∆D1) and days 5-14 to day -1 (∆D2) were calculated. The relationship between ∆D1 and ∆D2 of total bilirubin and major complications as well as 30-day mortality was analyzed.

RESULTS

Out of 64 patients, 10 developed major complications (15.6 %) and 6 patients (9.3 %) had died within 30 days after surgery. The ∆D2 of total bilirubin after PVE was most significantly associated with major complications (P < 0.001) and 30-day mortality (P = 0.002). In addition, it was found to be an independent predictor of major complications after PVE (odds ratio (OR) = 1.050; 95 % CI 1.017-1.084). ASA >3 (OR = 12.048; 95 % CI 1.019-143.321), ∆D2 of total bilirubin (OR = 1.058; 95 % CI 1.007-1.112), and ∆D2 of prealbumin (OR = 0.975; 95 % CI 0.952-0.999) were associated with higher risk of 30-day mortality after PVE. Receiver operating characteristic curves showed that ∆D2 of total bilirubin were better predictors than ∆D1 for major complications (AUC (∆D2) 0.817; P = 0.002 vs. AUC (∆D1) 0.769; P = 0.007) and 30-day mortality (ACU(∆D2) 0.868; P = 0.003 vs. AUC(∆D1) 0.721;P = 0.076).

CONCLUSION

Patients with increased total bilirubin in 5-14 days after PVE may indicate a higher risk of major complications and 30-day mortality if the major hepatectomy were performed.

The profile of platelet α-granule released molecules affects postoperative liver regeneration

Platelets promote liver regeneration through site-specific serotonin release from dense granules, triggering proliferative signaling in hepatocytes. However, the effects of factors derived from platelet α-granules on liver regeneration are unclear, because α-granules contain bioactive molecules with opposing functions. Because α-granule molecules are stored in separate compartments, it has been suggested that platelets selectively release their α-granule content dependent on the environmental stimulus. Therefore, we investigated the pattern of circulating α-granule molecules during liver regeneration in 157 patients undergoing partial hepatectomy. We measured plasma levels of α-granule-derived factors in the liver vein at the end of liver resection, as well as on the first postoperative day. We observed a rapid accumulation of platelets within the liver after induction of liver regeneration. Platelet count and P-selectin (a ubiquitous cargo of α-granules) were not associated with postoperative liver dysfunction. However, low plasma levels of vascular endothelial growth factor (VEGF), but high levels of thrombospondin 1 (TSP-1), predicted liver dysfunction after resection. Patients with an unfavorable postoperative α-granule release profile (high TSP-1/low VEGF) showed substantially worse postoperative clinical outcomes. The unfavorable postoperative α-granule release profile was associated with increased postoperative portal venous pressure and von Willebrand factor antigen levels as a marker for intrahepatic endothelial dysfunction.

CONCLUSION

The postoperative profile of circulating platelet-derived factors correlates with the ability of the remnant liver to regenerate. Portal venous pressure and intrahepatic endothelial dysfunction might account for the selective granule release profile. Selective modulation of platelet α-granule release in patients may represent an attractive target for therapeutic interventions to improve liver regeneration and clinical outcomes after partial hepatectomy.

The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer's Disease

The early diagnosis of Alzheimer’s disease (AD) has become important to the reversal and treatment of neurodegeneration, which may be relevant to premature brain aging that is associated with chronic disease progression. Clinical proteomics allows the detection of various proteins in fluids such as the urine, plasma, and cerebrospinal fluid for the diagnosis of AD. Interest in lipidomics has accelerated with plasma testing for various lipid biomarkers that may with clinical proteomics provide a more reproducible diagnosis for early brain aging that is connected to other chronic diseases. The combination of proteomics with lipidomics may decrease the biological variability between studies and provide reproducible results that detect a community’s susceptibility to AD. The diagnosis of chronic disease associated with AD that now involves genomics may provide increased sensitivity to avoid inadvertent errors related to plasma versus cerebrospinal fluid testing by proteomics and lipidomics that identify new disease biomarkers in body fluids, cells, and tissues. The diagnosis of AD by various plasma biomarkers with clinical proteomics may now require the involvement of lipidomics and genomics to provide interpretation of proteomic results from various laboratories around the world.

Pharmacological Intervention in Hepatic Stellate Cell Activation and Hepatic Fibrosis

The activation and transdifferentiation of hepatic stellate cells (HSCs) into contractile, matrix-producing myofibroblasts (MFBs) are central events in hepatic fibrogenesis. These processes are driven by autocrine- and paracrine-acting soluble factors (i.e., cytokines and chemokines). Proof-of-concept studies of the last decades have shown that both the deactivation and removal of hepatic MFBs as well as antagonizing profibrogenic factors are in principle suitable to attenuate ongoing hepatic fibrosis. Although several drugs show potent antifibrotic activities in experimental models of hepatic fibrosis, there is presently no effective pharmaceutical intervention specifically approved for the treatment of liver fibrosis. Pharmaceutical interventions are generally hampered by insufficient supply of drugs to the diseased liver tissue and/or by adverse effects as a result of affecting non-target cells. Therefore, targeted delivery systems that bind specifically to receptors solely expressed on activated HSCs or transdifferentiated MFBs and delivery systems that can improve drug distribution to the liver in general are urgently needed. In this review, we summarize current strategies for targeted delivery of drugs to the liver and in particular to pro-fibrogenic liver cells. The applicability and efficacy of sequestering molecules, selective protein carriers, lipid-based drug vehicles, viral vectors, transcriptional targeting approaches, therapeutic liver- and HSC-specific nanoparticles, and miRNA-based strategies are discussed. Some of these delivery systems that had already been successfully tested in experimental animal models of ongoing hepatic fibrogenesis are expected to translate into clinically useful therapeutics specifically targeting HSCs.

Tissue Remodelling following Resection of Porcine Liver

AIM

To study genes regulating the extracellular matrix (ECM) and investigate the tissue remodelling following liver resection in porcine.

METHODS

Four pigs with 60% partial hepatectomy- (PHx-) induced liver regeneration were studied over six weeks. Four pigs underwent sham surgery and another four pigs were used as controls of the normal liver growth. Liver biopsies were taken upon laparotomy, after three and six weeks. Gene expression profiles were obtained using porcine-specific oligonucleotide microarrays. Immunohistochemical staining was performed and a proliferative index was assessed.

RESULTS

More differentially expressed genes were associated with the regulation of ECM in the resection group compared to the sham and control groups. Secreted protein acidic and rich in cysteine (SPARC) and collagen 1, alpha 2 (COL1A2) were both upregulated in the early phase of liver regeneration, validated by immunopositive cells during the remodelling phase of liver regeneration. A broadened connective tissue was demonstrated by Masson's Trichrome staining, and an immunohistochemical staining against pan-Cytokeratin (pan-CK) demonstrated a distinct pattern of migrating cells, followed by proliferating cell nuclear antigen (PCNA) positive nuclei.

CONCLUSIONS

The present study demonstrates both a distinct pattern of PCNA positive nuclei and a deposition of ECM proteins in the remodelling phase of liver regeneration.

Thrombospondin-1 (TSP1)-producing B cells restore antigen (Ag)-specific immune tolerance in an allergic environment

Restoration of the antigen (Ag)-specific immune tolerance in an allergic environment is refractory. B cells are involved in immune regulation. Whether B cells facilitate the generation of Ag-specific immune tolerance in an allergic environment requires further investigation. This paper aims to elucidate the mechanism by which B cells restore the Ag-specific immune tolerance in an allergic environment. In this study, a B cell-deficient mouse model was created by injecting an anti-CD20 antibody. The frequency of tolerogenic dendritic cell (TolDC) was assessed by flow cytometry. The levels of cytokines were determined by enzyme-linked immunosorbent assay. The expression of thrombospondin-1 (TSP1) was assessed by quantitative real-time RT-PCR, Western blotting, and methylation-specific PCR. The results showed that B cells were required in the generation of the TGF-β-producing TolDCs in mice. B cell-derived TSP1 converted the latent TGF-β to the active TGF-β in DCs, which generated TGF-β-producing TolDCs. Exposure to IL-13 inhibited the expression of TSP1 in B cells by enhancing the TSP1 gene DNA methylation. Treating food allergy mice with Ag-specific immunotherapy and IL-13 antagonists restored the generation of TolDCs and enhanced the effect of specific immunotherapy. In conclusion, B cells play a critical role in the restoration of specific immune tolerance in an allergic environment. Blocking IL-13 in an allergic environment facilitated the generation of TolDCs and enhanced the therapeutic effect of immunotherapy.

Plasma thrombospondin 1 as a predictor of postoperative liver dysfunction

BACKGROUND

Liver regeneration following liver resection involves a complex interplay of growth factors and their antagonists. Thrombospondin 1 has recently been identified as a critical inhibitor of liver regeneration by the activation of transforming growth factor β1 in mice, and preliminary data seem to confirm its relevance in humans. This study aimed to confirm these observations in an independent validation cohort.

METHODS

Perioperative circulating levels of thrombospondin 1 were measured in patients undergoing liver resection between January 2012 and September 2013. Postoperative liver dysfunction was defined according to the International Study Group of Liver Surgery and classification of morbidity was based on the criteria by Dindo et al.

RESULTS

In 85 patients (44 major and 41 minor liver resections), plasma levels of thrombospondin 1 increased 1 day after liver resection (mean 51·6 ng/ml before surgery and 68·3 ng/ml on postoperative day 1; P = 0·001). Circulating thrombospondin 1 concentration on the first postoperative day specifically predicted liver dysfunction (area under the receiver operating characteristic (ROC) curve 0·818, P = 0·003) and was confirmed as a significant predictor in multivariable analysis (Exp(B) 1·020, 95 per cent c.i. 1·005 to 1·035; P = 0·009). Patients with a high thrombospondin 1 concentration (over 80 ng/ml) on postoperative day 1 more frequently had postoperative liver dysfunction than those with a lower level (28 versus 2 per cent) and severe morbidity (44 versus 15 per cent), and their length of hospital stay was more than doubled (19·7 versus 9·9 days).

CONCLUSION

Thrombospondin 1 may prove a helpful clinical marker to predict postoperative liver dysfunction as early as postoperative day 1.

Effect of LSKL peptide on thrombospondin 1-mediated transforming growth factor β signal activation and liver regeneration after hepatectomy in an experimental model

Background

A strategy for accelerating liver regeneration after hepatectomy would offer great benefits in preventing postoperative liver failure and improving surgical outcomes. Transforming growth factor (TGF) β is a potent inhibitor of hepatocyte proliferation. Recently, thrombospondin (TSP) 1 has been identified as a negative regulator of liver regeneration by activation of local TGF-β signals. This study aimed to clarify whether the LSKL (leucine–serine–lysine–leucine) peptide, which inhibits TSP-1-mediated TGF-β activation, promotes liver regeneration after hepatectomy in mice.

Methods

Mice were operated on with a 70 per cent hepatectomy or sham procedure. Operated mice received either LSKL peptide or normal saline intraperitoneally at abdominal closure and 6 h after hepatectomy. Perioperative plasma TSP-1 levels were measured by enzyme-linked immunosorbent assay in patients undergoing hepatectomy.

Results

Administration of LSKL peptide attenuated Smad2 phosphorylation at 6 h. S-phase entry of hepatocytes was accelerated at 24 and 48 h by LSKL peptide, which resulted in faster recovery of the residual liver and bodyweight. Haematoxylin and eosin tissue staining and blood biochemical examinations revealed no significant adverse effects following the two LSKL peptide administrations. In the clinical setting, plasma TSP-1 levels were lowest on the first day after hepatectomy. However, plasma TSP-1 levels at this stage were significantly higher in patients with subsequent liver dysfunction compared with levels in those without liver dysfunction following hepatectomy.

Conclusion

Only two doses of LSKL peptide during the early period after hepatectomy can promote liver regeneration. The transient inhibition of TSP-1/TGF-β signal activation using LSKL peptide soon after hepatectomy may be a promising strategy to promote subsequent liver regeneration.

TALEN-mediated gene editing of the thrombospondin-1 locus in axolotl

Loss-of-function genetics provides strong evidence for a gene's function in a wild-type context. In many model systems, this approach has been invaluable for discovering the function of genes in diverse biological processes. Axolotls are urodele amphibians (salamanders) with astonishing regenerative abilities, capable of regenerating entire limbs, portions of the tail (including spinal cord), heart, and brain into adulthood. With their relatively short generation time among salamanders, they offer an outstanding opportunity to interrogate natural mechanisms for appendage and organ regeneration provided that the tools are developed to address these long-standing questions. Here we demonstrate targeted modification of the thrombospondin-1 (tsp-1) locus using transcription-activator-like effector nucleases (TALENs) and identify a role of tsp-1 in recruitment of myeloid cells during limb regeneration. We find that while tsp-1-edited mosaic animals still regenerate limbs, they exhibit a reduced subepidermal collagen layer in limbs and an increased number of myeloid cells within blastemas. This work presents a protocol for generating and genotyping mosaic axolotls with TALEN-mediated gene edits.

Nuclear Factor I-C acts as a regulator of hepatocyte proliferation at the onset of liver regeneration

BACKGROUND & AIMS

Knockout studies of the murine Nuclear Factor I-C (NFI-C) transcription factor revealed abnormal skin wound healing and growth of its appendages, suggesting a role in controlling cell proliferation in adult regenerative processes. Liver regeneration following partial hepatectomy (PH) is a well-established regenerative model whereby changes elicited in hepatocytes lead to their rapid and phased proliferation. Although NFI-C is highly expressed in the liver, no hepatic function was yet established for this transcription factor. This study aimed to determine whether NFI-C may play a role in hepatocyte proliferation and liver regeneration.

METHODS

Liver regeneration and cell proliferation pathways following two-thirds PH were investigated in NFI-C knockout (ko) and wild-type (wt) mice.

RESULTS

We show that the absence of NFI-C impaired hepatocyte proliferation because of plasminogen activator I (PAI-1) overexpression and the subsequent suppression of urokinase plasminogen activator (uPA) activity and hepatocyte growth factor (HGF) signalling, a potent hepatocyte mitogen. This indicated that NFI-C first acts to promote hepatocyte proliferation at the onset of liver regeneration in wt mice. The subsequent transient down regulation of NFI-C, as can be explained by a self-regulatory feedback loop with transforming growth factor beta 1 (TGF-ß1), may limit the number of hepatocytes entering the first wave of cell division and/or prevent late initiations of mitosis.

CONCLUSION

NFI-C acts as a regulator of the phased hepatocyte proliferation during liver regeneration.

Prognostic value of Ki-67 expression in conversion therapy for colorectal liver-limited metastases

INTRODUCTION

The objective of this study was to examine the prognostic value of Ki-67 expression in conversion therapy for colorectal liver-confined metastases.

METHODS

We enrolled a total of 96 patients including 54 patients who received oxaliplatin- or irinotecan-based chemotherapy and curative hepatectomy for initially unresectable metastases (conversion group) and 42 patients with initially resectable liver metastases (straight hepatectomy group). Ki-67 expression was examined in 96 resected specimens but excluded the 2 specimens that revealed no residual cancer cells in conversion group.

RESULTS

Conversion therapy leads to greater survival that is equivalent to that straight hepatectomy group. In conversion group, high Ki-67 expression (> 30%) levels were detectable in 33 patients (64%) after chemotherapy prior to conversion therapy. High Ki-67 expression was significantly associated with shorter disease-free survival and worse overall survival (P < 0.01 in both), and was an independent worse prognostic factor of disease-free survival and overall survival (hazard ratio [HR] and P-values were 5.608, 0.001 and 5.366, 0.04, respectively) in patients with conversion therapy. Interestingly, even in the patients with RECIST PR (n = 32), high Ki-67 expression was significantly shorter disease-free survival compared to low Ki-67 expression (P < 0.001). In contrast to conversion group, there was no significant difference in disease free survival and overall survival between low (n = 14, 33%) and high (n = 28, 67%) Ki-67 expressions in patients with straight hepatectomy (P = 0.14 and 0.74, respectively).

CONCLUSIONS

Residual Ki-67 expression is a useful biomarker for worse prognostic outcomes after conversion therapy. High Ki-67 expression may be a biomarker of micrometastases containing aggressive cancer cells.