Abstract
It has been suggested that binding of phosphorothioate oligodeoxynucleotides (P=S ODNs) to macrophage scavenger receptors (SR-AI/II) is the primary mechanism of P=S ODN uptake into cells in vivo. To address the role of scavenger receptors in P=S ODN distribution in vivo, several pharmacokinetic and pharmacological parameters were compared in tissues from scavenger receptor knockout mice (SR-A−/−) and their wild-type counterparts after i.v. administration of 5- and 20-mg/kg doses of P=S ODN. With an antibody that recognizes P=S ODN, no differences in cellular distribution or staining intensity in livers, kidneys, lungs, or spleens taken from SR-A−/− versus wild-type mice could be detected at the histological level. There were no significant differences in P=S ODN concentrations in these organs as measured by capillary gel electrophoresis as well, although the concentration of P=S ODN in isolated Kupffer cells from livers of SR-A−/− mice was 25% lower than that in Kupffer cells from wild-type mice. Furthermore, a P=S ODN targeting murine A-raf reduced A-raf RNA levels to a similar extent in livers from SRA−/− (92.8%) and wild-type (88.3%) mice. Finally, in vitro P=S ODN uptake studies in peritoneal macrophages from SR-A−/− versus wild-type mice indicate that other high- and low-affinity uptake mechanisms predominate. Taken as a whole, our data suggest that, although there may be some contribution to P=S ODN uptake by the SR-AI/II receptor, this mechanism alone cannot account for the bulk of P=S ODN distribution into tissues and cells in vivo, including macrophages.
Footnotes
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Send reprint requests to: Madeline Butler, ISIS Pharmaceuticals, 2292 Faraday Ave., Carlsbad, CA 92008. E-mail:mbutler{at}isisph.com
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↵1 Current address: Department of Medicine, the University of British Columbia, Vancouver, British Columbia V5Z4E3, Canada.
- Abbreviations:
- P=S ODN
- phosphorothioate oligodeoxynucleotides
- SR-AI/II
- macrophage scavenger receptors
- SR-A−/−
- macrophage scavenger receptor knockout mice
- CGE
- quantitative capillary gel eletrophoresis
- LDL
- low-density lipoproteins
- Ox-LDL
- oxidized LDL
- Ac-LDL
- acetylated LDL
- poly(I)
- polyinosinic acid
- malBSA
- maleylated BSA
- SPE
- solid-phase extraction
- Received August 11, 1999.
- Accepted October 6, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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