Transcription profiling of mouse lung tissue after exposure to mainstream tobacco smoke

We have examined the impact of subchronic levels of tobacoo smoke on murine lungs. We have used high density DNA microarray and analysed lung tissues from mice exposed to mainstream tobacco smoke (MTS). Our results reveal induction of inflammatory cytokine interleukin-6 (IL-6) and its antagonist suppressor of cytokine signalling (SOCS3) mRNA in smoking group. We also show that these changes are transient and are reversed completely after a period of cessation of smoking. Experiment Overall Design: Male C57B1/CBA mice were exposed to MTS from two cigarettes daily, 5 days/week for 6 or 12 weeks. Mice were sacrificed immediately, or six weeks following the last cigarette. Left lung lobes were removed and flash frozen. Total RNA was isolated from a small part of the frozen lung and was hybridized against universal mouse reference RNA to Agilent Oligo DNA microarrays (Agilent Technologies) containing 22,000 transcripts. Microarrays were normalized using a global LOWESS approach and analyzed by MAANOVA 2.0 and SAM. Microarray results were validated by real time RT-PCR. Impact of alteration in expression of select genes was further validated by analysing their total protein levels in lung tissue homogenates.