Effects of glycine on phagocytosis and secretion by Kupffer cells in vitro

Acoustic Delivery of Plasma Low-Density Lipoprotein into Liver via ApoB100-Targeted Microbubbles Inhibits Atherosclerotic Plaque Growth

Atherosclerosis is the main risk factor for cardiovascular disease, which accounts for the majority of mortality worldwide. A significantly increased plasma level of low-density lipoprotein cholesterol (LDL-C), surrounded by a monolayer of phospholipids, free cholesterol, and one apolipoprotein B-100 (ApoB-100) in the blood, plays the most significant role in driving the development of atherosclerosis. Commercially available cholesterol-lowering drugs are not sufficient for preventing recurrent cardiovascular events. Developing alternative strategies to decrease the plasma cholesterol levels is desirable. Herein, we develop an approach for reducing LDL-C levels using gas-filled microbubbles (MBs) that were coated with anti-ApoB100 antibodies. These targeted MBApoB100 could selectively capture LDL particles in the bloodstream through forming LDL-MBApoB100 complexes and transport them to the liver for degradation. Further immunofluorescence staining and lipidomic analyses showed that these LDL-MBApoB100 complexes may be taken up by Kupffer cells and delivered to liver cells and bile acids, greatly inhibiting atherosclerotic plaque growth. More importantly, ultrasound irradiation of these LDL-MBApoB100 complexes that accumulated in the liver may induce acoustic cavitation effects, significantly enhancing the delivery of LDL into liver cells and accelerating their degradation. Our study provides a strategy for decreasing LDL-C levels and inhibiting the progression of atherosclerosis.

Boron Facilitates Amelioration of Hepatic Injury by the Osmolyte Glycine and Resolves Injury by Improving the Tissue Redox Homeostasis

Background: Glycine is a conditional non-essential amino acid in human and other mammals. It is abundant in the liver and is known for a wide spectrum of characteristics including the antioxidant, antiinflammatory, immunomodulatory, and cryoprotective effects. The amino acid is a naturally occurring osmolyte compatible with protein surface interactions and has been reported in literature as a potent therapeutic immuno-nutrient for liver diseases such as alcoholic liver disease. Oral glycine administration protects ethanol-induced liver injury, improves serum and tissue lipid profile, and alleviates hepatic injury in various conditions. In recent years, sodium salt of boron (borax) has been reported for its beneficial effects on cellular stress, including the effects on cell survival, immunity, and tissue redox state. Incidentally both glycine and boron prevent apoptosis and promote cell survival under stress. Objective: This study investigates the beneficial effect of borax on liver protection by glycine. Methods: Briefly, liver toxicity was induced in rats by a single intraperitoneal injection of thioacetamide (400 mg/kg b. wt.). Results: Significant changes in oxidative stress and liver function test parameters, the molybdenum Fe-S flavin hydroxylase activity, nitric oxide and tissue histopathology were observed in thioacetamide treated positive control group. The changes were ameliorated both by glycine as well as borax, but the combinatorial treatment yielded a better response indicating the impact of boron supplementation on glycine mediated protection of liver injury in experimental animal model. Conclusions: The study has clinical implications as the hepatotoxicity caused by thioacetamide mimics features of hepatitis C infection in human.

Inhibition of the sterol regulatory element-binding protein pathway suppresses hepatocellular carcinoma by repressing inflammation in mice

Obesity is a critical risk factor for hepatocellular carcinoma (HCC). However, it remains unknown whether inhibition of de novo lipid biosynthesis can suppress HCC. In this study, we blocked the sterol regulatory element-binding protein (SREBP) pathway, one of the key determinants of lipid homeostasis, by ablating 78-kDa cell-surface glycoprotein or SREBP cleavage-activating protein in hepatocytes, as well as by administering a chemical compound called betulin. We found that either genetically or pharmacologically inhibiting the SREBP pathway dramatically reduced diethylnitrosamine-induced HCC progression by down-regulating tumor-promoting cytokines, including interleukin (IL)-6, tumor necrosis factor alpha, and IL-1β.

CONCLUSION

Inhibition of de novo lipid biosynthesis by suppressing the SREBP pathway prevents HCC. This study identifies a previously underappreciated role of the SREBP pathway in HCC and suggests a novel metabolic strategy to control liver cancer. (Hepatology 2017;65:1936-1947).

Effect of lipopolysaccharide on proliferation, secretion and ultrastructure of murine liver Kupffer cells under high glucose conditions

AIM

To investigate the effect of lipopolysaccharide (LPS) on the proliferation, secretion and ultrastructure of liver Kupffer cells (KCs) under high glucose conditions.

METHODS

Murine liver KCs were cultured, amplified, and then randomly divided into a high glucose group [(HG), 25.0 mmol/L D-glucose], a normal glucose group [(CON), 11.1 mmol/L D-glucose], a LPS + high glucose group [(LPS-HG), 25.0 mmol/L D-glucose], and a LPS + normal glucose group [(LPS-CON), 11.1 mmol/L D-glucose)]. The KCs in each group were cultured for 24 h, and then LPS was added for the LPS-HG and LPS-CON groups. After 6 h of continuous cultivation, cell proliferation and cell cycle were detected by MTT colorimetric assay and flow cytometry, respectively. Cell supernatants were collected to determine the levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β and IL-6 by Luminex xMAP technique. The ultrastructure of KCs was observed by transmission electron microscopy (TEM).

RESULTS

MTT colorimetric assay showed that the optical density (OD) of murine liver KCs treated with LPS for 6 h under high glucose conditions increased significantly, but the OD values decreased significantly in the HG and LPS-HG groups compared with those of the CON and LPS-CON groups (P < 0.05). Flow cytometry revealed that high glucose arrested the cell cycle in G0/G1 phase; the percentage of G0/G1 phase cells decreased and that of S + G2/M phase cells increased significantly (P < 0.01) after KCs were treated with LPS for 6. The Luminex xMAP assay showed that the levels of TNF-α, IL-1β and IL-6 increased significantly after murine liver KCs were treated with LPS for 6 h under high glucose conditions, and the changes in TNF-α and IL-1β were more obvious. TEM revealed obvious ultrastructural alterations of KCs treated with LPS for 6 h under high glucose conditions. A large number of autophagosomes were observed in the LPS-HG group, and only few were noted in the HG group. Only vacuolar degenerations were visible in the CON and LPS-CON groups.

CONCLUSION

LPS can activate and enhance the proliferation and secretion of murine liver Kupffer cells under high glucose conditions. Both LPS and hyperglycemia can induce ultrastructural alterations of KCs including autophagy.

Immunostimulatory effect of fermented red ginseng in the mouse model

In this study, Woongjin fermented red ginseng extract (WFRG) was evaluated for its potential ability to act as an adjuvant for the immune response of mice. For the in vitro study, macrophages were treated with serial concentrations (1 μg/mL, 10 μg/mL, and 100 μg/mL) of WFRG. For in vivo studies, mice were administered different concentrations (10 mg/kg/day, 100 mg/kg/day, and 200 mg/kg/day) of WFRG orally for 21 days. In vitro, the production of nitric oxide and TNF-α by RAW 264.7 cells increased in a dose-dependent manner. In vivo, WFRG enhanced the proliferation of splenocytes induced by two mitogens (i.e., concanavalin A and lipopolysaccharide [LPS]) and increased LPS-induced production of TNF-α and IL-6, but not IL-1β. In conclusion, WFRG has the potential to modulate immune function and should be further investigated as an immunostimulatory agent.