Validation of IKKb as therapeutic target in airway inflammatory disease by adenoviral-mediated delivery of dominant-negative IKKb to pulmonary epithelial cells

1 Asthma is an inflammatory disease of the lungs and the transcription factor NF-kB regulates the production of numerous inflammatory mediators that may have a role in the pathogenesis of asthma. Hence, the signalling pathways leading to NF-kB activation are considered prime targets for novel anti-inflammatory therapies. The prevention of NF-kB activity in mice, through the knockout of IKKb or p65, causes fatal liver degeneration in utero making it difficult to determine the full implications of inhibiting NF-kB activity in tissues physiologically relevant to human diseases. 2 This study used adenovirus delivery of a dominant inhibitor of NF-kB (IkBaDN) and dominantnegative IKKa (IKKa(KM)) and IKKb (IKKb(KA)) to investigate the role of the individual IKKs in NF-kB activation and inflammatory gene transcription by human pulmonary A549 cells. 3 Overexpression of IKKb(KA) or IkBaDN prevented NF-kB-dependent transcription and DNA binding. IKKb(KA) also prevented IkBa kinase activity. Similarly, IKKb(KA) and IkBaDN overexpression also inhibited IL-1band TNFa-dependent increases in ICAM-1, IL-8 and GMCSF in addition to IL-1b-mediated increases in cyclooxygenase-2 expression, whereas IKKa(KM) overexpression had little effect on these outputs. 4 IKKb(KA) also reduced cell viability and induced caspase-3 and PARP cleavage regardless of the stimuli, indicating the induction of apoptosis. This effect seemed to be directly related to IKKb kinase activity since IkBaDN only induced PARP cleavage in TNFa-treated cells. 5 These results demonstrate that inhibition of IKKb and NF-kB suppresses inflammatory mediator production and reduces A549 cell viability. Thus, novel therapies that target IKKb could have potent anti-inflammatory effects and may be beneficial in the treatment of certain cancers. British Journal of Pharmacology (2005) 145, 114–122. doi:10.1038/sj.bjp.0706170 Published online 21 February 2005

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