Silencing of genes coding for transcription factors: Biological effects of decoy oligonucleotides on cystic fibrosis bronchial epithelial cells

Chronic pulmonary inflammation in the lungs of patients affected by cystic fibrosis is characterized by massive intra-bronchial recruitment of neutrophils, initiated and sustained upon interaction of pathogens (including Pseudomonas aeruginosa) with surface bronchial cells, associated with release of chemokines, including interleukins IL-8 and IL-6. This process leads to progressive tissue damage. In order to develop novel therapeutic strategies altering this process, the transcription factor (TF) decoy approach was applied, based on the intracellular delivery of double stranded oligodeoxynucleotides (ODNs) mimicking the binding sites of transcription factors and causing inhibition of the binding of TF-related proteins to regulatory sequences present in the promoter of specific genes. Since the promoters IL-8 and IL-6 contain consensus sequences for NF-kB and Sp1, IB3-1 cells were transfected with double stranded TF "decoy" ODNs targeting NF-kB and Sp1. Inhibition of Sp1 activity using transcription factor decoy molecules leads to inhibition of the expression of IL-6 gene; in addition, NF-kB decoy ODNs produced inhibition of transcription of IL-8. In conclusion, these results suggest that intracellular delivery of "decoy" molecules aimed to compete with the NF-kB and Sp1 transcription factors is a promising strategy to obtain selective inhibition of expression of IL-8 and IL-6 genes stimulated in epithelial cells of the respiratory tract upon surface interaction with bacteria.