Transcriptional induction of multiple cytokines by human respiratory syncytial virus requires activation of NF-kappa B and is inhibited by sodium salicylate and aspirin

Abstract

Infection of the lung epithelial cell line A549 by respiratory syncytial virus (RSV) resulted in the elevated synthesis of multiple cellular cytokines, including a number of interleukins (ILs). Detailed studies of IL-11 induction revealed that it required infection by viable virus and involved a net increase in the steady state level of IL-11 mRNA. Nuclear run-on assays showed a direct effect of RSV on IL-11 gene transcription. Mutational analysis of the IL-11 promoter fused to a reporter luciferase gene demonstrated the requirement of a region 720 nucleotides upstream of the mRNA start site in the transcriptional induction of IL-11 by RSV. Two nearly identical 10-nucleotide-long sequences GGGGTCTCCC and GGGTCTCCCC in this region resembled the NF-kappa B consensus motif. Mutation of either sequence greatly reduced RSV-mediated induction of IL-11 promoter activity. NF-kappa B sites in IL-1 alpha, IL-6, and IL-8 promoters were also required for RSV-mediated induction of transcription of these promoters. Immunological studies and use of reporter gene constructs provided direct evidence for the activation and nuclear translocation of NF-kappa B by RSV. Sodium salicylate and aspirin, inhibitors of NF-kappa B activation, abolished transcriptional induction of all these cytokines by RSV. Together, these studies demonstrated an essential role of NF-kappa B in RSV-mediated transcription of multiple cytokines genes and suggested a possible use of salicylates in managing airway inflammation and viral pathogenesis during RSV infection.