Pneumologie 2013; 67 - A12
DOI: 10.1055/s-0033-1357060

In utero exposure to mainstream cigarette smoke alters neonatal pulmonary signaling networks and postnatal lung function

S Dehmel 1, P Nathan 1, K Milger 1, R Prungnaud 1, R Imker 1, G John 1, A Önder Yildirim 1, M Irmler 2, J Beckers 2, 3, O Eickelberg 1, S Krauss-Etschmann 1
  • 1Institute for Lung Biology and Disease iLBD, Comprehensive Pneumology Center CPC, Helmholtz Zentrum München, München, Germany, Member of the German Center for Lung Research
  • 2Institute of Experimental Genetics, Helmholtz Zentrum München, München, Germany
  • 3Chair of Experimental Genetics, Technische Universität München, Freising, Germany

Background & Aim: Epidemiologic studies showed that maternal smoking during pregnancy is a main risk factor to develop asthma later in life. However, the underlying mechanisms are insufficiently understood. MicroRNAs (miRs) act as master regulators of bronchoalveolar tissue morphogenesis and immune system development during embryo-fetal life. We therefore asked how maternal smoking during pregnancy affects 1) pulmonary maternal immune responses and 2) miR/mRNA networks in lungs of offspring in late fetal stage.

Methods: Pregnant (P) and non-pregnant (NP) BALB/c mice were exposed to filtered air (FA) or mainstream cigarette smoke (MCS) daily starting on embryonic day (E)2.5 until E17.5. Weight gain progression was assessed during pregnancy and in the first weeks of life. Lung function was investigated in offspring mice using Flexivent® and Buxco® devices. RT-qPCR was used to measure T cell-specific transcription factor expression (Tbx21 (Th1), Gata3 (Th2), Rorc (Th17), Foxp3 (Treg)) in maternal lung and spleen. Gene expression profiling of fetal (E18.5) lungs (n = 6/group & sex) was performed on Affymetrix GeneChips®. Pathway and network analysis was done using Ingenuity® software.

Results: NP MCS mice had a weight decrease that was more pronounced and occurred at an earlier stage (E7.5 vs. E13.5) compared to P MCS mice. Female MCS offspring mice showed significantly lower lung/body weight ratios at E18.5 and increased baseline airway resistance at 3w of age compared to FA offspring. At 8w of age male MCS offspring mice had increased airway hyperreactivity to methacholine compared to FA offspring. Maternal pulmonary Tbx21 and Gata3 mRNA decreased, while Rorc mRNA increased in MCS vs. FA mice and Foxp3 mRNA remained unchanged. No differences were observed in spleen. Functional analysis of fetal pulmonary gene expression at E18.5 indicates a network of molecules regulating pulmonary development that is affected by MCS exposure on multiple levels including changes in transcription factor and microRNA expression.

Conclusions: The smoke exposure model replicates growth retardation in human new-borns and lung growth and function seems to be more compromised in female offspring at early stages while male offspring was affected later. Gender-specific interaction of smoke-dysregulated miRs with single pathways and effects on development are currently investigated.