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CNR: Alamanacco della Scienza


N. 14 - 16 ott 2013
ISSN 2037-4801

International info   a cura di Cecilia Migali


Smoking affects children‘s immune systems

The Leipzig Helmholtz Center for Environmental Research (Ufz) has gained new insights on the influence of tobacco smoke 'in utero'. For the first time, it could be demonstrated with smoking pregnant women and their children, how exposure to tobacco smoke affects the development of human immune system on molecular level. The focus thereby was on microRna – a short, single-stranded Rna molecule that is now recognised as playing an important role in gene regulation. From the results that were recently published in the 'Journal of Allergy and Clinical Immunology', one thing is certain: "for the first time we were able to describe the effect of prenatal environmental stressors on the regulation of microRna", says Gunda Herberth, from the Ufz, author of the study with Irina Lehmann.

Former studies have already proven that smoking during pregnancy can harm the unborn child: newborns from smoking mothers have shown low birth weights and impaired lung functions; later on in life respiratory diseases, diabetes type II, asthma or cardiovascular diseases were also more common. However, the exact molecular mechanisms and processes that are behind such developments still struggle researchers. For this reason, Herberth and Lehmann decided to address the relatively recent research area of microRna.

The scientists from Leipzig examined microRna-223, microRna-155 and regulatory T cells – not only in the blood samples of pregnant women (36 weeks pregnant) but also at birth in the cord blood of their babies. At the same time, questionnaires were filled out and urine samples of the pregnant women were tested to substantiate the effect from exposure to tobacco smoke and/or from volatile organic compounds resulting from smoking. From the pool of mothers participating in the study, 315 mothers (6.6 percent of whom were smokers) and 441 children were consulted in these investigations. 

By measuring the concentration of these microRnas as well as the number of regulatory T cells in maternal and cord blood, it could be shown that a high exposure to inhaled volatile organic compounds (Vocs) associated with tobacco smoke coincides with high values for miR-223. At the same time it was also found that increased values for maternal and umbilical cord blood miR-223 correlate with low regulatory T-cell numbers. Finally, it could be shown that low regulatory T-cell numbers in umbilical cord blood was an indication that children exposed to tobacco smoke were more likely to develop an allergy before the age of three compared to those children with normal values for miR-223 and Treg cells. Furthermore, the probability of developing eczema was almost twice as high for these children.

"After already being able to demonstrate the influence of prenatal smoking on regulatory T-cell numbers in cord blood from our study, the current epidemiological investigation delves even deeper into molecular processes", Dr. Gunda Herberth and Dr. Irina Lehmann resume. "Now", the immunologists from Leipzig explicate, "we will know more about the molecular processes that trigger off stressors from smoke during pregnancy". 

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