Environmental stressors impact on the human body. For the first time researchers at the Leipzig Helmholtz Center for Environmental Research have identified the mechanism for the bodies reaction to environmental stress.
The scientists used maternal smoking to examined the effect of environmental toxins on children on a molecular level and focused on micorRNA, a short single stranded RNA molecule that plays an important role in gene regulation.
Cigarettes do not only contain nicotine but a wide variety of chemical additives that have been recognized as toxic and represent a good environmental model to study the harmful effects of environmental toxins on the human immune system.
The objective for Dr Gunda Herberth was to reveal the influence of tobacco smoke on the development of children’s immune systems — at molecular level. : “For the first time we were able to describe the effect of prenatal environmental stressors on the regulation of microRNA.”
Prior studies have already demonstrated that smoking during pregnancy harms the unborn child and that 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 are also more common.
The immunologists specifically focused on the risk of children developing allergies when mothers smoked during pregnancy and 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 LINA-study, 315 mothers (6.6 percent of whom were smokers) and 441 children were consulted in these investigations.
The focus was on miR-223 and miR-155, because their role in regulating T cells had already been proven. “What we are now interested in finding out,” explains Dr. Gunda Herberth , “is whether or not these microRNAs link exposure to smoke, regulatory T cells and the risk of developing allergies.”
The results reflect that 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 LINA 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.” Thus, for the first time the association between prenatal environmental stressors and the regulation of microRNA is described.
The research has significance for the field of immunology as the impact of environmental stressors on microRNA is not only limited to smoking but also impacts on any significant toxic environmental event ranging from GMOS to pesticide application that the human body is exposed to on a daily basis.
Gunda Herberth, Mario Bauer, Michaela Gasch, Denise Hinz, Stefan Röder, Sven Olek, Tibor Kohajda, Ulrike Rolle-Kampczyk, Martin von Bergen, Ulrich Sack, Michael Borte, Irina Lehmann. Maternal and cord blood miR-223 expression associates with prenatal tobacco smoke exposure and low regulatory T-cell numbers. Journal of Allergy and Clinical Immunology, 2013; DOI: 10.1016/j.jaci.2013.06.036