Administration of naked plasmid encoding hepatic stimulator substance by hydrodynamic tail vein injection protects mice from hepatic failure by suppressing the mitochondrial permeability transition

Hepatopoietin Cn (HPPCn) Generates Protective Effects on Acute Liver Injury

Objective: To observe the protective role of hapatopoietin Cn (HPPcn) on acute liver injury.

Methods: Six hours after 10 mmol/L CCl₄, 150 mmol/L ethanol, or 0.6 mmol/L H₂O₂ treatment, SMMC7721 human hepatoma cells were incubated with 10, 100, or 200 ng/ml recombinant human HPPCn protein (rhHPPCn) for an additional 24 h. The cell survival rate was analyzed using the CCK-8 assay. The CCl₄-induced apoptosis of SMMC7721 cells was detected by flow cytometry. Then, the levels of glutamic oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), malondialdehyde (MDA), lactate dehydrogenase (LDH), glutathione peroxidase (GSH-PX), and superoxide dismutase (SOD) in SMMC7721 cell lysates and cell culture supernatant were detected. SMMC7721 cells were treated with different concentrations of rhHPPCn (0, 10, and 100 ng/ml). The cell proliferation indexes (BrdU incorporation and PCNA expression) were detected by immunohistochemistry (IHC). An acute liver injury mouse model was established by a one-time intraperitoneal injection of 20% CCl₄ at a volume of 5 ml/kg body weight. One hour after CCl₄ injection, 1.25 or 2.5 mg rhHPPCn/12 h/kg body weight was injected via the tail vein. The serum levels of GOT and GPT were detected at different time points. Pathological changes in the liver were evaluated. PCNA expression levels were observed by IHC.

Results: rhHPPCn increased the survival rate of SMMC7721 cells and inhibited chemical toxicity-induced cell apoptosis. The levels of GOT, GPT, MDA, and LDH in the cell supernatant were significantly reduced, while GSH-PX and SOD were significantly increased after rhHPPCn treatment in the CCl₄-treated SMMC7721 cells. BrdU incorporation and PCNA expression increased in a concentration-dependent manner, indicating that rhHPPCn promotes cell proliferation. The results showed that rhHPPCn significantly reduced the serum levels of GOT and GPT in CCl₄-induced acute liver injury mice. rhHPPCn alleviated the tissue damage and increased PCNA expression, indicating the promotion of proliferation after acute injury.

Conclusion: rhHPPCn protects hepatocytes from chemical toxins by promoting proliferation and inhibiting apoptosis in vivo and in vitro. Our study provides new insights for the clinical treatment of acute liver injury.

Treatment of AECHB and Severe Hepatitis (Liver Failure)

This chapter describes the general treatment and immune principles and internal management for AECHB and HBV ACLF, including ICU monitoring, general supportive medications/nutrition/nursing, immune therapy, artificial liver supportive systems, hepatocyte/stem cell, and liver transplant, management for special populations, frequently clinical complications and the utilization of Chinese traditional medicines.

Early clinical indicators of severe hepatitis B include acratia, gastrointestinal symptoms, a daily increase in serum bilirubin >1 mg/dL, toxic intestinal paralysis, bleeding tendency and mild mind anomaly or character change, and the presence of other diseases inducing severe hepatitis. Laboratory indicators include T-Bil, PTA, cholinesterase, pre-albumin and albumin. The roles of immune indicators (such as IL-6, TNF-α, and fgl2), gene polymorphisms, HBV genotypes, and gene mutations as early clinical indicators.

Intensive Care Unit monitor patients with severe hepatitis include intracranial pressure, infection, blood dynamics, respiratory function, renal function, blood coagulation function, nutritional status and blood purification process. Nursing care should not only include routine care, but psychological and special care (complications).

Nutrition support and nursing care should be maintained throughout treatment for severe hepatitis. Common methods of evaluating nutritional status include direct human body measurement, creatinine height index (CHI) and subject global assessment of nutrition (SGA). Malnourished patients should receive enteral or parenteral nutrition support.

Immune therapies for severe hepatitis include promoting hepatocyte regeneration (e.g. with glucagon, hepatocyte growth factor and prostaglandin E1), glucocorticoid suppressive therapy, and targeting molecular blocking. Corticosteroid treatment should be early and sufficient, and adverse drug reactions monitored. Treatments currently being investigated are those targeting Toll-like receptors, NK cell/NK cell receptors, macrophage/immune coagulation system, CTLA-4/PD-1 and stem cell transplantation.

In addition to conventional drugs and radioiodine, corticosteroids and artificial liver treatment can also be considered for severe hepatitis patients with hyperthyreosis. Patients with gestational severe hepatitis require preventive therapy for fetal growth restriction, and it is necessary to choose the timing and method of fetal delivery. For patients with both diabetes and severe hepatitis, insulin is preferred to oral antidiabetic agents to control blood glucose concentration. Liver toxicity of corticosteroids and immune suppressors should be monitored during treatment for severe hepatitis in patients with connective tissue diseases including SLE, RA and sicca syndrome. Patient with connective tissue diseases should preferably be started after the antiviral treatment with nucleos(t)ide analogues.

An artificial liver can improve patients’ liver function; remove endotoxins, blood ammonia and other toxins; correct amino acid metabolism and coagulation disorders; and reverse internal environment imbalances. Non-bioartificial livers are suitable for patients with early and middle stage severe hepatitis; for late-stage patients waiting for liver transplantation; and for transplanted patients with rejection reaction or transplant failure. The type of artificial liver should be determined by each patient’s condition and previous treatment purpose, and patients should be closely monitored for adverse reactions and complications. Bio- and hybrid artificial livers are still under development.

MELD score is the international standard for choosing liver transplantation. Surgical methods mainly include the in situ classic type and the piggyback type; transplantation includes no liver prophase, no liver phase or new liver phase. Preoperative preparation, management of intraoperative and postoperative complications and postoperative long-term treatment are keys to success.

Severe hepatitis belongs to the categories of “acute jaundice”, “scourge jaundice”, and “hot liver” in traditional Chinese medicine. Treatment methods include Chinese traditional medicines, acupuncture and acupoint injection, external application of drugs, umbilical compress therapy, drip, blow nose therapy, earpins, and clysis. Dietary care is also an important part of traditional Chinese medicine treatment.

Lack of hepatic stimulator substance expression promotes hepatocellular carcinoma metastasis partly through ERK-activated epithelial-mesenchymal transition

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies due to its high frequency of metastasis via the epithelial-mesenchymal transition (EMT) pathway. Hepatic stimulator substance (HSS) can protect hepatocytes from injury and promote liver growth. Recent studies indicated that HSS expression is increased in HCC tissues; however, whether HSS expression is potentially associated with HCC metastasis, particularly through the EMT pathway, remains largely unknown. In this study, the relationship between HSS expression and HCC metastasis was investigated in clinical samples of HCC. Meanwhile, the regulation of HCC metastasis and EMT progression by HSS were also analyzed in both in vitro and in vivo models. The results showed that the expression of 23 kDa HSS was significantly decreased among HCC tissues with angioinvasion. A decrease in HSS predicted poor prognosis with a lower survival rate. Furthermore, the growth of xenograft tumors after inoculating MHCC97H-HSS-shRNA (HCC) cells into nude mice was notably accelerated compared to those inoculated with HSS-expressing cells. Further analysis revealed that knockdown of HSS expression in both MHCC97H and HepG2 cells could enhance the migration of these HCC cells. Concurrently, interference of HSS expression by shRNA promoted conversion of morphologically epithelial-like HCC cells into mesenchymal-like cells, together with downregulations of epithelial markers (such as E-cadherin and zonula occludens-1) and upregulation of mesenchymal-like makers (such as α-SMA, β-catenin, and fibronectin). Furthermore, it was demonstrated that, as well as promoting EMT, HSS-shRNA induced the phosphorylation of extracellular signal-regulated kinase (ERK) and elevated the expression of the EMT-related transcription factor Snail. Specific inhibition of HSS-shRNA-induced ERK phosphorylation by PD98059 attenuated HCC cell migration in a dose-dependent manner. In conclusion, we demonstrated that downregulation of HSS expression contributes to HCC metastasis partially through the ERK-activated EMT pathway.

Long noncoding RNA Gomafu upregulates Foxo1 expression to promote hepatic insulin resistance by sponging miR-139-5p

Long non-coding RNA Gomafu is involved in diabetes-related diseases. However, its role in insulin resistance (IR) remains unclear. Our objective is to explore the role of Gomafu in hepatic IR and glucose intolerance. Gomafu expression was determined in livers of ob/ob mice and high-fat diet (HFD) mice. The binding activity of NF-κB on the Gomafu promoter was measured by chromatin immunoprecipitation and quantitative real-time PCR assays. Increased Gomafu expression was observed in the livers of obese mice. Besides, the binding of NF-κB on the Gomafu promoter was also observed in hepatocytes from ob/ob mice. Further study showed that knockdown of NF-κB p65 alleviated the increase in hepatic Gomafu expression in vivo and in vitro. Knockdown of hepatic Gomafu inhibited hepatic glucose production (HGP) and improved insulin sensitivity in obese mice, whereas, overexpression of hepatic Gomafu resulted in an increase in random and fasting blood glucose levels in lean mice. In addition, we demonstrated that Gomafu functioned as miR-139 sponge and led to the de-repression of its target gene Foxo1, which played an important role in gluconeogenesis and HGP in hepatocytes. Finally, silenced Foxo1 expression abolished the effect of Gomafu overexpression on gluconeogenesis and glucose production in hepatocytes. Taken together, our data suggested that the increase in Gomafu expression contributed to hepatic IR in obese mice.

Hepatic stimulator substance resists hepatic ischemia/reperfusion injury by regulating Drp1 translocation and activation

Ischemia/reperfusion injury, induced by abnormal mitochondrial fission-related apoptosis, is a major concern in liver transplantation settings. Our previous studies have demonstrated that hepatic stimulator substance (HSS) is an antiapoptotic effector and could protect liver from ischemia/reperfusion injury. However, the underlying mechanism remains unclear. In the present study, we report that in vitro and in vivo HSS could regulate mitochondrial fission and hepatocyte apoptosis during liver ischemia/reperfusion injury by orchestrating the translocation and activation of dynamin-related protein 1 (Drp1). Using a mouse model of ischemia/reperfusion-induced liver injury, we found that HSS-haploinsufficient (HSS^+/- ) mice displayed exacerbated liver damage based on their increased serum aminotransferase levels, cell structural destruction, and apoptosis levels compared to wild-type (HSS^+/+ ) littermates. Disruption of HSS markedly increased cyclin-dependent kinase 1 (CDK1) and Bax expression, accompanied by elevated phosphorylated Drp1 and release of cytochrome c. In parallel in vitro studies, we found that HSS could inhibit the expression of CDK1 and that HSS inhibits hepatocyte apoptosis through its suppression of CDK1/cyclin B-mediated phosphorylation at Ser-616 of Drp1, thereby decreasing Drp1 accumulation in mitochondria and Drp1-mediated activation of the mitochondrial fission program. On the contrary, knockdown of HSS increased CDK1 as well as Drp1 phosphorylation and aggravated hepatocellular apoptosis. Mechanistic investigation showed that HSS was able to reduce the stability and translation of CDK1 mRNA by modulating the expression of several microRNAs (miRs), including miR-410-3p, miR-490-3p, and miR-582-5p.

CONCLUSION

Our data reveal a novel mechanism for HSS in regulating the mitochondrial fission machinery and further suggest that modulation of HSS may provide a therapeutic approach for combating liver damage. (Hepatology 2017;66:1989-2001).

Hepatic stimulator substance inhibits calcium overflow through the mitochondria-associated membrane compartment during nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is considered a disorder of the endoplasmic reticulum (ER) and mitochondria. Recent studies have shown that the ER and mitochondrial membranes overlap by 15-20%, a region referred to as the 'mitochondria-associated ER membrane' (MAM). Some proteins, including sarco/ER calcium ATPase (SERCA), are located in the MAM and have an important role in Ca²⁺ signaling and homeostasis between the ER and the mitochondria. Our previous study showed that hepatic stimulator substance (HSS) inhibits the ER stress induced by reactive oxygen species, thus reducing mitochondrial damage. However, the mechanism underlying the protective effect of HSS on the ER and ER-mitochondrial interaction remains unclear. In this study, we confirmed that the exogenous expression of HSS protected the liver from steatosis in mice with nonalcoholic steatohepatitis. More importantly, the protection provided by HSS allowed SERCA in the MAM compartment to function well, preventing the extensive influx of cytosolic free Ca²⁺ to the mitochondria, thus preserving the mitochondrial functions from calcium overload and relieving palmitic-acid-induced hepatocyte steatosis. Our results suggest that the protective effect of HSS on SERCA expression is associated with the maintenance of calcium homeostasis within the MAM, thus ameliorating the disordered Ca²⁺ communication between the ER and mitochondria.

Cirrhotic liver regeneration after partial hepatectomy

The liver is an organ with strong regenerative ability, and its regenerative mechanism is very complex. The liver regenerative process is regulated by various kinds of factors, which coordinate highly, and is also influenced by many other factors. Studies have shown that liver cirrhosis is an important factor affecting liver regeneration, and cirrhotic liver shows significantly impaired regenerative function. Liver cancer frequently occurs following cirrhosis in China, so further definition of the regenerative mechanism after partial hepatectomy in these patients has far-reaching significance for improving their prognosis. Nowadays, most studies on the regulatory mechanism of cirrhotic liver regeneration on focused on different signaling pathways and various related cytokines. This review summarizes the findings of these studies.

Amelioration of nonalcoholic fatty liver disease by hepatic stimulator substance via preservation of carnitine palmitoyl transferase-1 activity

Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease and so far is supposed to be related with mitochondrial impairment. Hepatic stimulator substance (HSS) has been defined as a liver-protective factor promoting hepatocyte DNA synthesis and hepatic proliferation after liver intoxication. We previously reported that HSS ameliorated hepatocyte death, probably because of its preservation of mitochondria. This study aims to explore whether HSS could protect carnitine palmitoyl transferase-1 (CPT-1), an essential enzyme responsible for β-oxidation of free fatty acids in mitochondria, from lipotoxicity, thus alleviating hepatic lipid deposition. To test this, the HSS gene was delivered into C57BL/6J mice and efficiently expressed in the liver. NASH mice were prepared with high-fat diet or methionine-choline-deficient diet. The results showed that hepatic inflammation and liver functions were alleviated in the HSS-transfected mice; meanwhile, the activity of CPT-1 was obviously protected. Moreover, oleic acid (OA) treatment resulted in remarkable lipid accumulation in HepG2 cells; this deposition was improved by HSS transfection. Simultaneously, the CPT-1 activity, which was impaired by OA treatment, was profoundly rescued in the HSS-expressing cells. CPT-1 activity was more severely impaired if the OA treatment was combined with S15176, a CPT-1 inhibitor. However, this impairment was effectively reduced by the HSS transfection, and the effect was enhanced by C75, a CPT-1 activator. Interestingly, if the cells were transfected with HSS-siRNA, the preservation of CPT-1 provided by HSS was again diminished. In conclusion, HSS reduces lipotoxicity to mitochondria most likely via preservation of CPT-1.

Deceleration of liver regeneration by knockdown of augmenter of liver regeneration gene is associated with impairment of mitochondrial DNA synthesis in mice

Hepatic stimulator substance, also known as augmenter of liver regeneration (ALR), is a novel hepatic mitogen that stimulates liver regeneration after partial hepatectomy (PH). Recent work has indicated that a lack of ALR expression inhibited liver regeneration in rats, and the mechanism seems to be related to increased cell apoptosis. The mitochondria play an important role during liver regeneration. Adequate ATP supply, which is largely dependent on effective mitochondrial biogenesis, is essential for progress of liver regeneration. However, ALR gene expression during liver regeneration, particularly its function with mitochondrial DNA synthesis, remains poorly understood. In this study, ALR expression in hepatocytes of mice was suppressed with ALR short-hairpin RNA interference or ALR deletion (knockout, KO). The ALR-defective mice underwent PH, and the liver was allowed to regenerate for 1 wk. Analysis of liver growth and its correlation with mitochondrial biogenesis showed that both ALR mRNA and protein levels increased robustly in control mice with a maximum at days 3 and 4 post-PH. However, ALR knockdown inhibited hepatic DNA synthesis and decelerated liver regeneration after PH. Furthermore, both in the ALR-knockdown and ALR-KO mice, expression of mitochondrial transcription factor A and peroxisome proliferator-activated receptor-γ coactivator-1α were reduced, resulting in impaired mitochondrial biogenesis. In conclusion, ALR is apparently required to ensure appropriate liver regeneration following PH in mice, and deletion of the ALR gene may delay liver regeneration in part due to impaired mitochondrial biogenesis.

Autophagy in anti-apoptotic effect of augmenter of liver regeneration in HepG2 cells

AIM

To investigate the role of autophagy in the anti-apoptotic effect of augmenter of liver regeneration (ALR).

METHODS

Autophagy was induced through serum deprivation. An ALR-expressing plasmid was transfected into HepG2 cells, and autophagic flux was determined using fluorescence microscopy, electron microscopy, Western blot and quantitative polymerase chain reaction (qPCR) assays. After ALR-expressing plasmid transfection, an autophagy inhibitor [3-methyladenine (3-MA)] was added to HepG2 cells, and apoptosis was observed using fluorescence microscopy and flow cytometry.

RESULTS

Autophagy was activated in HepG2 cells, peaking at 24 h after serum deprivation. Microtubule-associated protein light chain three-II levels were higher in HepG2 cells treated with ALR than in control cells, fluorescence microscopy, electron microscopy and qPCR studies showed the similar trend, and p62 levels showed the opposite trend, which indicated that ALR may play an important role in increasing autophagy flux. The numbers of apoptotic cells were substantially higher in HepG2 cells treated with both ALR and 3-MA than in cells treated with ALR alone. Therefore, the protective effect of ALR was significantly attenuated or abolished when autophagy was inhibited, indicating that the anti-apoptotic effect of ALR may be related to autophagy.

CONCLUSION

ALR protects cells from apoptosis partly through increased autophagy in HepG2 cells and may be valuable as a new therapeutic treatment for liver disease.

Adenoviral gene transfer of hepatic stimulator substance confers resistance against hepatic ischemia-reperfusion injury by improving mitochondrial function

Hepatic stimulator substance (HSS) has been suggested to protect liver cells from various toxins. However, the precise role of HSS in hepatic ischemia-reperfusion (I/R) injury remains unknown. This study aims to elucidate whether overexpression of HSS could attenuate hepatic ischemia-reperfusion injury and its possible mechanisms. Both in vivo hepatic I/R injury in mice and in vitro hypoxia-reoxygenation (H/R) in a cell model were used to evaluate the effect of HSS protection after adenoviral gene transfer. Moreover, a possible mitochondrial mechanism of HSS protection was investigated. Efficient transfer of the HSS gene into liver inhibited hepatic I/R injury in mice, as evidenced by improvement in liver function tests, the preservation of hepatic morphology, and a reduction in hepatocyte apoptosis. HSS overexpression also inhibited H/R-induced cell death, as detected by cell viability and cell apoptosis assays. The underlying mechanism of this hepatic protection might involve the attenuation of mitochondrial dysfunction and mitochondrial-dependent cell apoptosis, as shown by the good preservation of mitochondrial ultrastructure, mitochondrial membrane potential, and the inhibition of cytochrome c leakage and caspase activity. Moreover, the suppression of H/R-induced mitochondrial ROS production and the maintenance of mitochondrial respiratory chain complex activities may participate in this mechanism. This new function of HSS expands the possibility of its application for the prevention of I/R injury, such as hepatic resection and liver transplantation in clinical practice.

Hepatic stimulator substance alleviates toxin-induced and immune-mediated liver injury and fibrosis in rats

BACKGROUND

Liver fibrosis is a common scarring response to chronic liver injury. It is a precursor to cirrhosis and liver carcinoma. Hepatic stimulator substance (HSS), a known liver-specific but species-nonspecific growth factor, has been shown to protect hepatocytes from various toxins.

METHODS

We have investigated the effects of HSS therapy on carbon tetrachloride (CCl(4))-induced and porcine-serum-mediated hepatic injury and fibrosis. We hypothesize that HSS might attenuate liver injury and fibrosis by suppressing oxidative stress, down-regulating profibrogenic factors, and blocking HSCs activation.

RESULTS

This report demonstrated that HSS therapy diminished α-smooth muscle actin expression, decreased intrahepatic reactive oxygen species (ROS) level, and down-regulated transforming growth factor (TGF)-β1, platelet-derived growth factor (PDGF)-BB, and tissue inhibitor of metalloproteinase (TIMP)-1 expression. In addition, HSS treatment significantly protected the liver from injury by improving liver function tests and histological architecture of the liver.

CONCLUSIONS

These results provided novel insights into the mechanisms of HSS in the protection of the liver. Our results suggested that HSS might be a therapeutic antifibrotic agent for the treatment of liver fibrosis.