PEGylated lactoferrin enhanced its hepatoprotective effects on acute liver injury induced by carbon tetrachloride in rats

Polyethylene glycol (PEG) is attached to proteins in order to increase their half-life in circulation and reduce their immunogenicity in vivo. The present study was conducted to examine whether two different sizes of PEGylated bovine lactoferrin (40k-PEG-bLf and 20k-PEG-bLf) would enhance the protective effect of native bLf on liver injury induced by carbon tetrachloride (CCl4) in rats. Silymarin, a known hepatoprotective drug was used as a positive control. Compared to native bLf, the treatment of PEGylated bLf more markedly prevented the elevation of serum levels of hepatic enzyme markers and inhibited fatty degeneration and the hepatic necrosis induced by CCl4. 40k-PEG-bLf showed a more significant suppressive effect on CCl4-induced hepatic injury than 20k-PEG-bLf. The treatment with PEGylated bLf elevated serum SOD activity reduced by CCl4 more significantly than native bLf. 40k-PEG-bLf enhanced serum SOD activity more significantly than 20k-PEG-bLf. Immunohistochemical study showed that the PEGylation of bLf enhanced its intracellular transportation to hepatocytes. The increases in intracellular transportation of the PEGylated bLf in order were: 40k-PEG-bLf > 20k-PEG-bLf > native bLf. These findings suggested that the mechanism of the enhancement of hepatoprotective effect by PEGylated bLf was associated with an increase in the intracellular transportation of PEGylated bLf in hepatocytes.