CATIONIC LIPID IS NOT REQUIRED FOR UPTAKE AND SELECTIVE INHIBITORY ACTIVITY OF ICAM-1 PHOSPHOROTHIOATE ANTISENSE OLIGONUCLEOTIDES IN KERATINOCYTES

Keratinocyte intercellular adhesion molecule-1 (ICAM-1) is important i n mediating retention of T cells within the epidermal compartment. To determine if antisense oligonucleotides designed to hybridize to vario us ICAM-1 mRNA regions could selectively influence cultured keratinocy te ICAM-1 expression following gamma interferon (IFN-gamma), cells wer e exposed to several antisense compounds, in the absence and presence of cationic lipid (lipofectin). Keratinocytes rapidly internalized sen se and antisense compounds (within 30-60 min), even in the absence of lipofectin with approximately 30% of the cell possessing positive nucl ei. Such nuclear accumulation was not observed in the absence of lipof ectin in cultured fibroblasts, smooth muscle cells, or endothelial cel ls, even though total cellular uptake within the cytoplasm was signifi cantly increased in all these cell types. Using how cytometry, IFN-gam ma-inducible ICAM-1 expression was reduced 50% by antisense compounds with lipofectin, and by 30% without lipofectin. This inhibition was sp ecific as no change was observed for HLA-DR or tumor necrosis factor-a lpha receptor expression. Northern blot hybridization studies confirme d that ICAM-1 antisense oligonucleotides selectively and significantly inhibited ICAM-1 expression. These results suggest that such antisens e compounds interact with keratinocytes differently than other cell ty pes, and provide the in vitro basis for clinical trials in which reduc tion (or elimination) of ICAM-1 expression by epidermal keratinocytes could be selectively accomplished without necessarily influencing derm al cell types such as fibroblasts, endothelial cells, or smooth muscle cells.