Related Experiment Videos
Liver uptake of phosphodiester oligodeoxynucleotides is mediated by scavenger receptors
E A Biessen1, H Vietsch, J Kuiper
1Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, 2300 RA Leiden, The Netherlands.
Abstract:
The therapeutic activity of antisense oligodeoxynucleotides (ODNs) often is impaired due to premature degradation and poor ability to reach the (intra)cellular target. In this study, we addressed the in vivo fate of ODNs and characterized the major sites responsible for the clearance of intravenously injected phosphodiester ODN. On injection into rats, 32P-ODNs (miscellaneous sequences and GT-containing ODNs with variable G content) are rapidly cleared from the bloodstream (t1/2 = 0.6-0.7 min), with the liver being the main site of elimination. The contribution of the liver to ODN clearance depended on its sequence and varied considerably. Hepatic uptake tended to be lower for G-rich ODNs as a result of increased bone marrow uptake. Within the liver, both Kupffer cells (KC) and endothelial cells (EC) were responsible for 32P-ODN uptake. To elucidate the mechanism of liver uptake, 32P-ODN binding studies using isolated EC and KC were performed. Binding to both cell types seemed to be saturable, of moderate affinity, and mediated by a membrane-bound protein. The inhibition profiles of 32P-ODN binding to EC and KC by various (poly)anions were essentially equal and corresponded closely to those of 125I-acetylated low-density lipoprotein. In summary, the results indicate that scavenger receptors on nonparenchymal liver and bone marrow cells contribute to the elimination of ODNs from the bloodstream. Minor changes in ODN sequence markedly affect receptor recognition, resulting in considerable shifts in the biodistribution of antisense ODNs.
Insights
Antisense oligodeoxynucleotides (ODNs) are quickly removed from blood, primarily by the liver and bone marrow. Sequence changes significantly alter ODN uptake by scavenger receptors, affecting their distribution.
Area of Science:
- Pharmacology
- Molecular Biology
- Biochemistry
Background:
- Antisense oligodeoxynucleotides (ODNs) show therapeutic promise but face challenges with degradation and cellular delivery.
- Understanding the in vivo fate and clearance mechanisms of ODNs is crucial for optimizing their therapeutic efficacy.
Purpose of the Study:
- To investigate the in vivo biodistribution and clearance of intravenously injected phosphodiester ODNs in rats.
- To identify the primary organs and cellular components responsible for ODN elimination from circulation.
- To elucidate the mechanism of ODN uptake by liver cells.
Main Methods:
- Administration of 32P-labeled ODNs with varying sequences to rats.
- Quantification of ODN levels in blood and organs over time.
- In vitro binding studies using isolated Kupffer cells (KC) and endothelial cells (EC).
- Analysis of ODN binding inhibition by various polyanions.
Main Results:
- ODNs were rapidly cleared from the bloodstream (t1/2 = 0.6-0.7 min), with the liver as the main elimination site.
- Hepatic uptake varied with ODN sequence; G-rich ODNs showed lower liver uptake and higher bone marrow uptake.
- Both KC and EC in the liver contributed to ODN uptake, mediated by saturable, moderately affine membrane-bound proteins.
- ODN binding inhibition profiles matched those of acetylated LDL, suggesting scavenger receptor involvement.
Conclusions:
- Scavenger receptors on nonparenchymal liver and bone marrow cells play a significant role in ODN clearance.
- Minor alterations in ODN sequence can substantially impact receptor recognition and subsequent biodistribution.
- These findings are critical for designing ODN-based therapeutics with improved pharmacokinetic profiles.