Objective To observe the protective effects of Toll-like receptor(TLR)-4 siRNA against acute liver injury in mice induced by lipopolysaccharide(LPS)and D-galactosamine(D-GalN).Methods One hundred and fifty C57BL/6 male mice were divided into 5 groups: phosphate buffered solution(PBS)pretreatment group,negative control plasmid pretreatment group,TS4 pretreatment group,TS6 pretreatment group and TS7 pretreatment group.Acute liver injury was induced in mice by intraperitoneal coinjection of LPS(10 ng/g)and D-GalN(1 mg/g).In vivo delivery of siRNA was performed via the tail vein by hydrodynamic injections(50 μg siRNA dissolved in 1 mL PBS)24 h and 48 h before coinjection of LPS and D-GalN. Expression of TLR-4 in liver tissues was measured by immunohistochemistry.The changes of TLR-4,tumor necrosis factor(TNF)-α and macrophage nflammatory protein(MIP)-2 mRNA levels in liver tissues were determined by reverse transcriptasepolymerase chain reaction(RT-PCR)analysis.MIP-2 and TNF-α concentrations in the sera of mice were determined by enzyme-linked immunosorbent assay(ELISA). Levels of alanine transaminase (ALT) and aspartate transaminase(AST) in serum were measured by standard autoanalyzer techniques. Liver pathological changes were observed by haematoxylin-eosin staining, while cell apoptosis levels in liver were determined by terminal deoxynucleotidyl-mediated-dUTP nick end labeling (TUNEL)assay. The difference of survival rates in 5 groups was analyzed by Fisher's exact probability test.ResultsPretreatment with TLR-4 siRNA down-regulated the TLR-4 mRNA and protein expressions,and significantly decreased the mortality and liver injury caused by coinjection of LPS and D-GalN in C57BL/6 mice.TLR-4 siRNA significantly down-regulated the TNF-α and MIP-2 mRNA expression and cytokine levels as determined by RT-PCR and ELISA,respectively. TLR-4 siRNA abrogated hepatocyte necrosis and inflammatory infiltration and also remarkably reduced serum concentrations of transaminases. The percentage of TUNEL-positive hepatocytes was significantly reduced in TLR-4 siRNA pretreatment group(TS4 pretreatment group: 0.065±0.015 vs PBS pretreatment group; 0.346±0.062,P＜0.05).ConclusionIt suggest that inhibition of TLR-4 expression by TLR-4 siRNA may provide potential application value for preventing liver injury.

With various diseases ravaging internationally, the demands for recombinant adenoviral vector (Adv) vaccines have increased dramatically. To meet the demand for Adv vaccine, development of a new cell culture process is an effective strategy. Applying hyperosmotic stress in cells before virus infection could increase the yield of Adv in batch culture mode. Emerging perfusion culture can significantly increase the yield of Adv as well. Therefore, combining the hyperosmotic stress process with perfusion culture is expected to improve the yield of Adv at high cell density. In this study, a shake flask combined with a semi-perfusion culture was used as a scaled-down model for bioreactor perfusion culture. Media with osmotic pressure ranging from 300 to 405 mOsm were used to study the effect of hyperosmotic stress on cell growth and Adv production. The results showed that using a perfusion culture process with a hyperosmotic pressure medium (370 mOsm) during the cell growth phase and an isosmotic pressure medium (300 mOsm) during the virus production phase effectively increased the yield of Adv. This might be due to the increased expression of HSP70 protein during the late phases of virus replication. The Adv titer in a bioreactor with such a process reached 3.2×10¹⁰ IFU/mL, three times higher than that of the traditional perfusion culture process. More importantly, this is the first time that a strategy of combining the hyperosmotic stress process with perfusion culture is applied to the production of Adv in HEK 293 cells. It also reveals the reason why the hyperosmotic stress process increased the yield of Adv, which may facilitate the process optimization of for producing other Adv in HEK 293 cells.
Humans ; HEK293 Cells ; Genetic Vectors/genetics* ; Batch Cell Culture Techniques ; Bioreactors ; Perfusion