The in vitro and in vivo pharmacology of antisense oligonucleotides targeted to murine Stat6

Objective and Design: This study was designed to establish whether phosphor othioate (PS) antisense oligonucleotides (AS-ODN) targeted to Stat6 were ac tive in vivo in a mouse model of active sensitisation. Materials: Female Balb/c mice (6-8) per group were used for in vivo study. Treatment: Mice were treated with active PS AS-ODNs determined in initial i n vitro studies. Compounds were dosed daily (3-30 mg/kg i.v.) over the cour se of sensitisation to ovalbumin. Methods: Stat6 mRNA and protein levels were determined in the spleen after treatment (quantitative northern and western analysis respectively), in add ition to serum IgE (ELISA). ANOVA was used to determine any significant dif ferences between groups. Results: Both of the AS-ODNs tested in vivo, down regulated Stat6 mRNA and protein levels in the spleen by 40-50% although there was no effect on seru m IgE. These treatments also induced splenomegaly in vivo and caused spleno cyte proliferation in vitro. Conclusions: The AS-ODNs used can down regulate Stat6 mRNA and protein alth ough not sufficiently to influence IgE-levels. These effects are likely to be complicated in vivo by the immune-stimulation evident as splenomegaly.