Transcriptional activation of the interleukin-8 gene by respiratory syncytial virus infection in alveolar epithelial cells: nuclear translocation of the RelA transcription factor as a mechanism producing airway mucosal inflammation

Abstract

The most common cause of epidemic pediatric respiratory disease, respiratory syncytial virus (RSV), stimulates interleukin-8 (IL-8) synthesis upon infecting airway epithelium, an event necessary for the development of mucosal inflammation. We investigated the mechanism for enhanced IL-8 production in human A549 type II pulmonary epithelial cells. Infection with sucrose-purified RSV (pRSV) produced a time-dependent increase in the transcriptional initiation rate of the IL-8 gene. Transient transfection of the human IL-8 promoter mutated in the binding site for nuclear factor-B (NF-B) demonstrated that this sequence was essential for pRSV-activated transcription. Gel mobility shift assays demonstrated pRSV induction of sequence-specific binding complexes; these complexes were supershifted only by antibodies directed to the potent NF-B transactivating subunit RelA. Both Western immunoblot and indirect immunofluorescence assays showed that cytoplasmic RelA in uninfected cells became localized to the nucleus after pRSV infection. RelA activation requires replicating RSV, because neither conditioned medium nor UV-inactivated pRSV was able to stimulate its translocation. We conclude that RelA undergoes changes in subcellular distribution in airway epithelial cells upon pRSV infection. The ability of replicating RSV to activate RelA translocation may play an important role in activating IL-8 and other inflammatory gene products necessary for airway mucosal inflammation seen in RSV disease.

Functional motifs responsible for human metapneumovirus M2-2-mediated innate immune evasion

“…P65, an importance member belonging to NF-κB superfamily, is also important in the induction of chemokines and cytokines by viruses including paramyxovirus (Garofalo et al, 1996;Tian et al, 2002). The significant role of the M2-2 motifs in modulating hMPV-induced NF-κB activation was also confirmed by enhanced p65 nuclear translocation in mutant-infected A549 cells, compared to rhMPV-WT-infected cells (Fig.…”

Citrate modulates lipopolysaccharide-induced monocyte inflammatory responses

“…Real-time PCR data were analysed by the delta-delta CT method [27]. of this plasmid have been shown to be identical to the full-length promoter in response to various inflammatory stimuli [28][29][30].…”

Understanding the mechanisms of viral induced asthma: New therapeutic directions

“…Several transcription factors are also activated, which may induce the expression of a range of genes such as NK-IL-6 and nuclear factor (NF)-kB. These factors regulate immunomodulatory mediators (TNF-α, IL-1β, IL-2, -6, -11 and GM-CSF), adhesion molecules (ICAM-1, VCAM-1 and E-selectin) and chemokines (IL-8, MIP-1α, MCP-1, eotaxin and RANTES) (Garofalo et al, 1996;Oh et al, 2002;John et al, 2003;Makela et al, 2003;Schaller et al, 2006). In combination these mediators and molecules induce the influx of inflammatory cells and may contribute to the development of infection-induced inflammatory and immune responses, AHR and asthma.…”