Targeting Transcription Factor Activity as a Strategy to Inhibit Pro-Inflammatory Genes Involved in Cystic Fibrosis: Decoy Oligonucleotides and Low-Molecular Weight Compounds

The development of drugs able to inhibit the expression of pro-inflammatory genes is of great interest in the treatment of cystic fibrosis (CF). Chronic pulmonary inflammation in the lungs of patients affected by CF is characterized by massive intra-bronchial infiltrates of neutrophils. This process is initiated upon interaction of pathogens (including Pseudomonas aeruginosa) with surface bronchial cells. Consequently, they release cytokines, the most represented being the potent neutrophilic chemokine Interleukin (IL)-8 and the pro-inflammatory cytokine IL-6. The chronic inflammatory process is crucial, since it leads to progressive tissue damage and severe respiratory insufficiency. In order to reduce the adverse effects of the excessive inflammatory response, one of the approaches leading to inhibition of IL-8 and IL-6 gene expression is the transcription factor (TF) decoy approach, based on intracellular delivery of double stranded oligodeoxynucleotides (ODNs) mimicking the binding sites of TFs and causing inhibition of binding of TFrelated proteins to regulatory sequences identified in the promoters of specific genes. Since the promoters of IL-8 and IL-6 contain consensus sequences for NF-κ B and Sp1, double stranded TF "decoy" ODNs targeting NF-κB and Sp1 can be used. Alternatively, screening of drugs targeting relevant TFs can be performed using drug cocktails constituted by extracts from medicinal plants inhibiting TF/DNA interactions. Finally, virtual screening might lead to identification of putative bioactive molecules to be validated using molecular and cellular approaches. By these means, low-molecular drugs targeting NF-κB and inhibiting IL-8 gene expression are available for pre-clinical testing using experimental systems recapitulating chronic pulmonary inflammation of patients affected by CF.