Abstract
Background: The short half-life of TRAIL (tumor necrosis factor–related apoptosis-inducing ligand) greatly limits its clinical application. This study was aimed to improve its potency on liver fibrosis through PEG (polyethylene glycol) modification prolonging the half-life of TRAIL.Methods: PEG, TRAIL, and the chemically synthesized complex PEG-TRAIL were used to treat 3T3 and LX-2 cells and liver fibrotic mice. In vitro, cell viability, apoptosis, and fibrosis were investigated using CCK-8 (cell counting kit-8) assay, flow cytometry, and Western blotting, respectively. In vivo, Sirius red staining, immunohistochemistry, and α-SMA (α-smooth muscle actin)/TUNEL (terminal deoxynucleotidyl transferase dUTP [2'-deoxyuridine 5'-triphosphate] nick end labeling) double-labeling immunofluorescence (IF) were performed after various treatments for liver fibrotic mice. The fibrotic liver was subjected to DR4 (death receptor 4)/TRAIL double-labeling IF to assess the retention of TRAIL enhanced by PEGylation.Results: The cells treated with PEG-TRAIL showed lower cell viability, higher apoptosis level, and stronger anti-fibrotic effect compared with PEG or TRAIL treatment. In vivo, PEGylated TRAIL exhibited a longer circulation than TRAIL did. Compared with TRAIL treatment, PEG-TRAIL caused a significant reduction of α-SMA and a markedly increase of apoptotic aHSCs. PEGylation is more likely to prolong the retention of TRAIL in circulation and enhance the possibility to target aHSCs and DR4-positive (DR4+) cells in the liver.Conclusion: PEG-TRAIL presents better anti-fibrotic and proapoptotic effects, for which, the prolonged circulation half-life in vivo may account. The PEG-TRAIL may serve as a new clinical therapeutic for liver fibrosis in the future.
Highlights
Liver fibrosis, a serious chronic liver disorder characterized by the superabundant extracellular matrix (ECM) accumulation, which induces various liver injury and leads to substantial morbidity and mortality (Bansal et al, 2011; Hasenfuss et al, 2014)
We investigated the effect of polyethylene glycol (PEG)-tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) on the viability and apoptosis of activated hepatic stellate cells (aHSCs) by cell counting kit-8 (CCK-8) assay and flow cytometry
The viability of both types of cells was significantly inhibited when the concentration of PEG-TRAIL exceeded 0.125 μg/ml (p < 0.01), identifying that 0.125 μg/ml is the efficient concentration of PEGTRAIL (Figure 1B)
Summary
A serious chronic liver disorder characterized by the superabundant extracellular matrix (ECM) accumulation, which induces various liver injury and leads to substantial morbidity and mortality (Bansal et al, 2011; Hasenfuss et al, 2014). Activated hepatic stellate cells (aHSCs) are the currently preferred targeted cells in anti-liver fibrotic therapy, and a variety of targeted drug delivery systems for HSCs have been explored and attempted for treating hepatic fibrosis in recent years (Sato et al, 2008; Bansal et al, 2011). TRAIL (tumor necrosis factor (TNF)–related apoptosisinducing ligand) is an important member of TNF superfamily. It is upregulated in aHSCs and has been proposed as a favorable candidate for therapy of many diseases because it can induce cellular apoptosis of some tumor cells, aHSCs, and virusinfected hepatocytes by activating caspase-3 (Holoch and Griffith, 2009; Xu et al, 2016). This study was aimed to improve its potency on liver fibrosis through PEG (polyethylene glycol) modification prolonging the half-life of TRAIL
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