Identification of genes induced by inflammatory cytokines in airway epithelium

Epithelial cells lining the airways are thought to play a prominent role in respiratory diseases. We utilized cDNA representational difference analysi s to identify the genes in which expression is induced by the proinflammato ry cytokines tumor necrosis factor-alpha and interleukin-1 beta in primary human bronchial epithelial cells and hence are relevant to airway inflammat ion. Hybridization of the subtraction product to arrayed cDNAs indicated th at known tumor necrosis factor-alpha- and interleukin-1 beta -inducible gen es such as B94, Zfp36, and regulated on activation normal T cell expressed and secreted were represented, confirming the success of the subtraction ex periment. A 1,152-clone library potentially representing genes with higher transcript levels in cytokine-treated human bronchial epithelial cells was generated and sequenced. Sequence similarity searches indicated that these clones represented 57 genes of known function, 1 gene of unknown function, 6 expressed sequence tags, and 2 novel sequences. The expression of 19 of t hese clones was studied by a combination of Northern blotting and RT-PCR an alyses and confirmation of differential expression for 10 known genes, 2 ex pressed sequence tags, and a novel sequence not represented in any of the p ublic databases was obtained. Thus cDNA representational difference analysi s was utilized to isolate known and novel differentially expressed genes, w hich putatively play a role in airway inflammation.