Related Experiment Video
Updated: Aug 14, 2026
Using RNA-interference to Investigate the Innate Immune Response in Mouse Macrophages
Published on: November 3, 2014
Serum mannan binding protein inhibits mannosylated liposome-mediated transfection to macrophages
P Opanasopit1, K Hyoudou, M Nishikawa
1Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Abstract:
The effects of serum mannan binding proteins (MBP) in the transfection of plasmid DNA/Man-liposome complex via mannose receptor-mediated endocytosis was studied in vitro using cultured mouse peritoneal macrophages. Plasmid DNA encoding luciferase gene was complexed with cationic mannosylated liposomes (Man-liposomes), composed of cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) and dioleoyl phosphatidylethanolamine (DOPE). The transfection efficiency, as well as the binding and uptake of the plasmid DNA/Man-liposome complex, was investigated with or without serum MBP. The in vitro transfection efficiency of the complex was significantly reduced on increasing the amount of serum MBP. In addition, the cellular association of the complex was also reduced. These results indicate that serum MBP specifically binds to the mannose moieties on the complex and suppresses its cellular uptake, resulting in inhibition of the gene transfection in macrophages. Such an interaction is an obstacle to mannose receptor-mediated in vivo gene transfer to mannose receptor-positive cells using mannosylated gene carriers.
Insights
Serum mannan binding proteins (MBP) hinder gene transfection by binding to mannosylated liposomes, reducing their uptake in macrophages. This interaction obstructs mannose receptor-mediated gene delivery to target cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Gene Therapy
Background:
- Mannose receptor-mediated endocytosis is a key pathway for cellular uptake.
- Mannosylated liposomes are investigated as gene delivery vehicles.
- Serum proteins can influence the efficacy of targeted delivery systems.
Purpose of the Study:
- To investigate the effect of serum mannan binding proteins (MBP) on the transfection efficiency of plasmid DNA/Man-liposome complexes.
- To elucidate the mechanism by which serum MBP affects mannose receptor-mediated endocytosis.
- To assess the potential of mannosylated gene carriers for in vivo applications.
Main Methods:
- In vitro transfection of cultured mouse peritoneal macrophages using plasmid DNA complexed with cationic mannosylated liposomes (Man-liposomes).
- Complexes composed of Man-C4-Chol and DOPE were used.
- Transfection efficiency, binding, and cellular uptake were measured with and without varying concentrations of serum MBP.
Main Results:
- In vitro transfection efficiency of the plasmid DNA/Man-liposome complex was significantly reduced by increasing serum MBP concentrations.
- Cellular association (binding and uptake) of the complex was also reduced in the presence of serum MBP.
- Serum MBP was found to specifically bind to the mannose moieties on the liposomes, inhibiting cellular uptake.
Conclusions:
- Serum MBP acts as an inhibitory factor in mannose receptor-mediated gene transfection.
- The binding of serum MBP to mannosylated liposomes impedes cellular uptake and reduces transfection efficiency.
- This interaction presents a significant obstacle for the development of mannosylated gene carriers for in vivo gene transfer to mannose receptor-positive cells.
