Deletion of individual exons and induction of soluble murine interleukin-5receptor-alpha chain expression through antisense oligonucleotide-mediatedredirection of pre-mRNA splicing

Expression of the interleukin-5 receptor-alpha (IL-5R alpha) chain is thoug ht to play an important role in the pathogenesis of asthma and other eosino philic diseases. With antisense oligonucleotides (ASOs) chemically modified to provide increased hybridization affinity for RNA but that do not suppor t RNase H-mediated cleavage (2'-O-methoxyethyl-modified ASOs), we show that constitutive splicing of murine IL-5R alpha mRNA can be modulated in cells such that individual exons may be selectively deleted from mature transcri pts. Specific deletion of individual exons and redirection of alternative s plicing of the IL-5R alpha mRNA have been achieved with this approach, by t argeting 3'-splice sites or exon sequences immediately downstream of an alt ernative splice site. ASO targeting with these strategies resulted in inhib ition of mRNA and protein levels of the membrane IL-5R alpha isoform capabl e of signaling IL-5-mediated growth and antiapoptotic signals to eosinophil s. Membrane isoform IL-5R alpha inhibition was coupled with an increase in expression of mRNA for the alternatively spliced soluble isoform, which bin ds IL-5 extracellularly and may block its function. These observations sugg est the potential general therapeutic use of an antisense approach to incre ase expression of variant RNA transcripts and to thereby produce proteins d evoid of specific functional domains that may impact disease processes, as well as its specific utility for modulating expression of a key cytokine re ceptor implicated in allergic inflammation.