Abstract
Introduction: Poly I:C mimics a viral infection through the activation TLR3 and RNA helicases. Our aim was to characterize molecular changes occurring in the lung after polyI:C exposure in mice.
Methods: BALB/c mice were administered saline or poly I:C (30 μg/animal). At 7 timepoints after dosing (2-168h), poly I:C- and saline-treated mice were sacrificed, bronchoalveolar lavage was performed and lungs were snap-frozen. RNA from lung homogenates was isolated using the NuGen labeling method and assessed on Affymetrix standard murine whole genome arrays (MOE430 2.0) (n=6 per group). Differentially expressed genes were determined using an ANOVA, with pairwise comparisons between poly I:C and saline treatment at each timepoint. Functional ontologies were determined using GO annotations. Gene set enrichment analysis (GSEA) was determined for cytokine and immune cell signatures compiled from the literature.
Results: The peak response occurred 6-48h post-treatment. Hierarchical clustering across the study revealed 3 distinct temporal clusters (early, mid, and late phase). Inflammatory processes were enriched in the early phase (2-6h), TLR/IL-1 signaling genes in the mid phase (6-48h), and cell cycle pathways in the late phase (>72h). GSEA revealed activated NK and dendritic cell signatures up to 96h post-challenge, while several immune and myeloid related gene modules were also up-regulated between 6-96h post-challenge.
Conclusions: Inflammatory signatures including TLR and IL1-related genes were highly up-regulated in response to poly I:C challenge, indicating a strong inflammatory response potentially driven by NK and dendritic cells in the lungs of mice.
- © 2011 ERS